Merge tag 'usb-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

[thirdparty/linux.git] / drivers / usb / host / xhci-ring.c

// SPDX-License-Identifier: GPL-2.0
/*
 * xHCI host controller driver
 *
 * Copyright (C) 2008 Intel Corp.
 *
 * Author: Sarah Sharp
 * Some code borrowed from the Linux EHCI driver.
 */

/*
 * Ring initialization rules:
 * 1. Each segment is initialized to zero, except for link TRBs.
 * 2. Ring cycle state = 0.  This represents Producer Cycle State (PCS) or
 *    Consumer Cycle State (CCS), depending on ring function.
 * 3. Enqueue pointer = dequeue pointer = address of first TRB in the segment.
 *
 * Ring behavior rules:
 * 1. A ring is empty if enqueue == dequeue.  This means there will always be at
 *    least one free TRB in the ring.  This is useful if you want to turn that
 *    into a link TRB and expand the ring.
 * 2. When incrementing an enqueue or dequeue pointer, if the next TRB is a
 *    link TRB, then load the pointer with the address in the link TRB.  If the
 *    link TRB had its toggle bit set, you may need to update the ring cycle
 *    state (see cycle bit rules).  You may have to do this multiple times
 *    until you reach a non-link TRB.
 * 3. A ring is full if enqueue++ (for the definition of increment above)
 *    equals the dequeue pointer.
 *
 * Cycle bit rules:
 * 1. When a consumer increments a dequeue pointer and encounters a toggle bit
 *    in a link TRB, it must toggle the ring cycle state.
 * 2. When a producer increments an enqueue pointer and encounters a toggle bit
 *    in a link TRB, it must toggle the ring cycle state.
 *
 * Producer rules:
 * 1. Check if ring is full before you enqueue.
 * 2. Write the ring cycle state to the cycle bit in the TRB you're enqueuing.
 *    Update enqueue pointer between each write (which may update the ring
 *    cycle state).
 * 3. Notify consumer.  If SW is producer, it rings the doorbell for command
 *    and endpoint rings.  If HC is the producer for the event ring,
 *    and it generates an interrupt according to interrupt modulation rules.
 *
 * Consumer rules:
 * 1. Check if TRB belongs to you.  If the cycle bit == your ring cycle state,
 *    the TRB is owned by the consumer.
 * 2. Update dequeue pointer (which may update the ring cycle state) and
 *    continue processing TRBs until you reach a TRB which is not owned by you.
 * 3. Notify the producer.  SW is the consumer for the event ring, and it
 *   updates event ring dequeue pointer.  HC is the consumer for the command and
 *   endpoint rings; it generates events on the event ring for these.
 */

#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>
#include "xhci.h"
#include "xhci-trace.h"

static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd,
                         u32 field1, u32 field2,
                         u32 field3, u32 field4, bool command_must_succeed);

/*
 * Returns zero if the TRB isn't in this segment, otherwise it returns the DMA
 * address of the TRB.
 */
dma_addr_t xhci_trb_virt_to_dma(struct xhci_segment *seg,
                union xhci_trb *trb)
{
        unsigned long segment_offset;

        if (!seg || !trb || trb < seg->trbs)
                return 0;
        /* offset in TRBs */
        segment_offset = trb - seg->trbs;
        if (segment_offset >= TRBS_PER_SEGMENT)
                return 0;
        return seg->dma + (segment_offset * sizeof(*trb));
}

static bool trb_is_noop(union xhci_trb *trb)
{
        return TRB_TYPE_NOOP_LE32(trb->generic.field[3]);
}

static bool trb_is_link(union xhci_trb *trb)
{
        return TRB_TYPE_LINK_LE32(trb->link.control);
}

static bool last_trb_on_seg(struct xhci_segment *seg, union xhci_trb *trb)
{
        return trb == &seg->trbs[TRBS_PER_SEGMENT - 1];
}

static bool last_trb_on_ring(struct xhci_ring *ring,
                        struct xhci_segment *seg, union xhci_trb *trb)
{
        return last_trb_on_seg(seg, trb) && (seg->next == ring->first_seg);
}

static bool link_trb_toggles_cycle(union xhci_trb *trb)
{
        return le32_to_cpu(trb->link.control) & LINK_TOGGLE;
}

static bool last_td_in_urb(struct xhci_td *td)
{
        struct urb_priv *urb_priv = td->urb->hcpriv;

        return urb_priv->num_tds_done == urb_priv->num_tds;
}

static bool unhandled_event_trb(struct xhci_ring *ring)
{
        return ((le32_to_cpu(ring->dequeue->event_cmd.flags) & TRB_CYCLE) ==
                ring->cycle_state);
}

static void inc_td_cnt(struct urb *urb)
{
        struct urb_priv *urb_priv = urb->hcpriv;

        urb_priv->num_tds_done++;
}

static void trb_to_noop(union xhci_trb *trb, u32 noop_type)
{
        if (trb_is_link(trb)) {
                /* unchain chained link TRBs */
                trb->link.control &= cpu_to_le32(~TRB_CHAIN);
        } else {
                trb->generic.field[0] = 0;
                trb->generic.field[1] = 0;
                trb->generic.field[2] = 0;
                /* Preserve only the cycle bit of this TRB */
                trb->generic.field[3] &= cpu_to_le32(TRB_CYCLE);
                trb->generic.field[3] |= cpu_to_le32(TRB_TYPE(noop_type));
        }
}

/* Updates trb to point to the next TRB in the ring, and updates seg if the next
 * TRB is in a new segment.  This does not skip over link TRBs, and it does not
 * effect the ring dequeue or enqueue pointers.
 */
static void next_trb(struct xhci_hcd *xhci,
                struct xhci_ring *ring,
                struct xhci_segment **seg,
                union xhci_trb **trb)
{
        if (trb_is_link(*trb) || last_trb_on_seg(*seg, *trb)) {
                *seg = (*seg)->next;
                *trb = ((*seg)->trbs);
        } else {
                (*trb)++;
        }
}

/*
 * See Cycle bit rules. SW is the consumer for the event ring only.
 */
void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring)
{
        unsigned int link_trb_count = 0;

        /* event ring doesn't have link trbs, check for last trb */
        if (ring->type == TYPE_EVENT) {
                if (!last_trb_on_seg(ring->deq_seg, ring->dequeue)) {
                        ring->dequeue++;
                        goto out;
                }
                if (last_trb_on_ring(ring, ring->deq_seg, ring->dequeue))
                        ring->cycle_state ^= 1;
                ring->deq_seg = ring->deq_seg->next;
                ring->dequeue = ring->deq_seg->trbs;
                goto out;
        }

        /* All other rings have link trbs */
        if (!trb_is_link(ring->dequeue)) {
                if (last_trb_on_seg(ring->deq_seg, ring->dequeue))
                        xhci_warn(xhci, "Missing link TRB at end of segment\n");
                else
                        ring->dequeue++;
        }

        while (trb_is_link(ring->dequeue)) {
                ring->deq_seg = ring->deq_seg->next;
                ring->dequeue = ring->deq_seg->trbs;

                if (link_trb_count++ > ring->num_segs) {
                        xhci_warn(xhci, "Ring is an endless link TRB loop\n");
                        break;
                }
        }
out:
        trace_xhci_inc_deq(ring);

        return;
}

/*
 * See Cycle bit rules. SW is the consumer for the event ring only.
 *
 * If we've just enqueued a TRB that is in the middle of a TD (meaning the
 * chain bit is set), then set the chain bit in all the following link TRBs.
 * If we've enqueued the last TRB in a TD, make sure the following link TRBs
 * have their chain bit cleared (so that each Link TRB is a separate TD).
 *
 * Section 6.4.4.1 of the 0.95 spec says link TRBs cannot have the chain bit
 * set, but other sections talk about dealing with the chain bit set.  This was
 * fixed in the 0.96 specification errata, but we have to assume that all 0.95
 * xHCI hardware can't handle the chain bit being cleared on a link TRB.
 *
 * @more_trbs_coming:   Will you enqueue more TRBs before calling
 *                      prepare_transfer()?
 */
static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring,
                        bool more_trbs_coming)
{
        u32 chain;
        union xhci_trb *next;
        unsigned int link_trb_count = 0;

        chain = le32_to_cpu(ring->enqueue->generic.field[3]) & TRB_CHAIN;

        if (last_trb_on_seg(ring->enq_seg, ring->enqueue)) {
                xhci_err(xhci, "Tried to move enqueue past ring segment\n");
                return;
        }

        next = ++(ring->enqueue);

        /* Update the dequeue pointer further if that was a link TRB */
        while (trb_is_link(next)) {

                /*
                 * If the caller doesn't plan on enqueueing more TDs before
                 * ringing the doorbell, then we don't want to give the link TRB
                 * to the hardware just yet. We'll give the link TRB back in
                 * prepare_ring() just before we enqueue the TD at the top of
                 * the ring.
                 */
                if (!chain && !more_trbs_coming)
                        break;

                /* If we're not dealing with 0.95 hardware or isoc rings on
                 * AMD 0.96 host, carry over the chain bit of the previous TRB
                 * (which may mean the chain bit is cleared).
                 */
                if (!(ring->type == TYPE_ISOC &&
                      (xhci->quirks & XHCI_AMD_0x96_HOST)) &&
                    !xhci_link_trb_quirk(xhci)) {
                        next->link.control &= cpu_to_le32(~TRB_CHAIN);
                        next->link.control |= cpu_to_le32(chain);
                }
                /* Give this link TRB to the hardware */
                wmb();
                next->link.control ^= cpu_to_le32(TRB_CYCLE);

                /* Toggle the cycle bit after the last ring segment. */
                if (link_trb_toggles_cycle(next))
                        ring->cycle_state ^= 1;

                ring->enq_seg = ring->enq_seg->next;
                ring->enqueue = ring->enq_seg->trbs;
                next = ring->enqueue;

                if (link_trb_count++ > ring->num_segs) {
                        xhci_warn(xhci, "%s: Ring link TRB loop\n", __func__);
                        break;
                }
        }

        trace_xhci_inc_enq(ring);
}

/*
 * Return number of free normal TRBs from enqueue to dequeue pointer on ring.
 * Not counting an assumed link TRB at end of each TRBS_PER_SEGMENT sized segment.
 * Only for transfer and command rings where driver is the producer, not for
 * event rings.
 */
static unsigned int xhci_num_trbs_free(struct xhci_hcd *xhci, struct xhci_ring *ring)
{
        struct xhci_segment *enq_seg = ring->enq_seg;
        union xhci_trb *enq = ring->enqueue;
        union xhci_trb *last_on_seg;
        unsigned int free = 0;
        int i = 0;

        /* Ring might be empty even if enq != deq if enq is left on a link trb */
        if (trb_is_link(enq)) {
                enq_seg = enq_seg->next;
                enq = enq_seg->trbs;
        }

        /* Empty ring, common case, don't walk the segments */
        if (enq == ring->dequeue)
                return ring->num_segs * (TRBS_PER_SEGMENT - 1);

        do {
                if (ring->deq_seg == enq_seg && ring->dequeue >= enq)
                        return free + (ring->dequeue - enq);
                last_on_seg = &enq_seg->trbs[TRBS_PER_SEGMENT - 1];
                free += last_on_seg - enq;
                enq_seg = enq_seg->next;
                enq = enq_seg->trbs;
        } while (i++ <= ring->num_segs);

        return free;
}

/*
 * Check to see if there's room to enqueue num_trbs on the ring and make sure
 * enqueue pointer will not advance into dequeue segment. See rules above.
 * return number of new segments needed to ensure this.
 */

static unsigned int xhci_ring_expansion_needed(struct xhci_hcd *xhci, struct xhci_ring *ring,
                                               unsigned int num_trbs)
{
        struct xhci_segment *seg;
        int trbs_past_seg;
        int enq_used;
        int new_segs;

        enq_used = ring->enqueue - ring->enq_seg->trbs;

        /* how many trbs will be queued past the enqueue segment? */
        trbs_past_seg = enq_used + num_trbs - (TRBS_PER_SEGMENT - 1);

        /*
         * Consider expanding the ring already if num_trbs fills the current
         * segment (i.e. trbs_past_seg == 0), not only when num_trbs goes into
         * the next segment. Avoids confusing full ring with special empty ring
         * case below
         */
        if (trbs_past_seg < 0)
                return 0;

        /* Empty ring special case, enqueue stuck on link trb while dequeue advanced */
        if (trb_is_link(ring->enqueue) && ring->enq_seg->next->trbs == ring->dequeue)
                return 0;

        new_segs = 1 + (trbs_past_seg / (TRBS_PER_SEGMENT - 1));
        seg = ring->enq_seg;

        while (new_segs > 0) {
                seg = seg->next;
                if (seg == ring->deq_seg) {
                        xhci_dbg(xhci, "Ring expansion by %d segments needed\n",
                                 new_segs);
                        xhci_dbg(xhci, "Adding %d trbs moves enq %d trbs into deq seg\n",
                                 num_trbs, trbs_past_seg % TRBS_PER_SEGMENT);
                        return new_segs;
                }
                new_segs--;
        }

        return 0;
}

/* Ring the host controller doorbell after placing a command on the ring */
void xhci_ring_cmd_db(struct xhci_hcd *xhci)
{
        if (!(xhci->cmd_ring_state & CMD_RING_STATE_RUNNING))
                return;

        xhci_dbg(xhci, "// Ding dong!\n");

        trace_xhci_ring_host_doorbell(0, DB_VALUE_HOST);

        writel(DB_VALUE_HOST, &xhci->dba->doorbell[0]);
        /* Flush PCI posted writes */
        readl(&xhci->dba->doorbell[0]);
}

static bool xhci_mod_cmd_timer(struct xhci_hcd *xhci)
{
        return mod_delayed_work(system_wq, &xhci->cmd_timer,
                        msecs_to_jiffies(xhci->current_cmd->timeout_ms));
}

static struct xhci_command *xhci_next_queued_cmd(struct xhci_hcd *xhci)
{
        return list_first_entry_or_null(&xhci->cmd_list, struct xhci_command,
                                        cmd_list);
}

/*
 * Turn all commands on command ring with status set to "aborted" to no-op trbs.
 * If there are other commands waiting then restart the ring and kick the timer.
 * This must be called with command ring stopped and xhci->lock held.
 */
static void xhci_handle_stopped_cmd_ring(struct xhci_hcd *xhci,
                                         struct xhci_command *cur_cmd)
{
        struct xhci_command *i_cmd;

        /* Turn all aborted commands in list to no-ops, then restart */
        list_for_each_entry(i_cmd, &xhci->cmd_list, cmd_list) {

                if (i_cmd->status != COMP_COMMAND_ABORTED)
                        continue;

                i_cmd->status = COMP_COMMAND_RING_STOPPED;

                xhci_dbg(xhci, "Turn aborted command %p to no-op\n",
                         i_cmd->command_trb);

                trb_to_noop(i_cmd->command_trb, TRB_CMD_NOOP);

                /*
                 * caller waiting for completion is called when command
                 *  completion event is received for these no-op commands
                 */
        }

        xhci->cmd_ring_state = CMD_RING_STATE_RUNNING;

        /* ring command ring doorbell to restart the command ring */
        if ((xhci->cmd_ring->dequeue != xhci->cmd_ring->enqueue) &&
            !(xhci->xhc_state & XHCI_STATE_DYING)) {
                xhci->current_cmd = cur_cmd;
                xhci_mod_cmd_timer(xhci);
                xhci_ring_cmd_db(xhci);
        }
}

/* Must be called with xhci->lock held, releases and aquires lock back */
static int xhci_abort_cmd_ring(struct xhci_hcd *xhci, unsigned long flags)
{
        struct xhci_segment *new_seg    = xhci->cmd_ring->deq_seg;
        union xhci_trb *new_deq         = xhci->cmd_ring->dequeue;
        u64 crcr;
        int ret;

        xhci_dbg(xhci, "Abort command ring\n");

        reinit_completion(&xhci->cmd_ring_stop_completion);

        /*
         * The control bits like command stop, abort are located in lower
         * dword of the command ring control register.
         * Some controllers require all 64 bits to be written to abort the ring.
         * Make sure the upper dword is valid, pointing to the next command,
         * avoiding corrupting the command ring pointer in case the command ring
         * is stopped by the time the upper dword is written.
         */
        next_trb(xhci, NULL, &new_seg, &new_deq);
        if (trb_is_link(new_deq))
                next_trb(xhci, NULL, &new_seg, &new_deq);

        crcr = xhci_trb_virt_to_dma(new_seg, new_deq);
        xhci_write_64(xhci, crcr | CMD_RING_ABORT, &xhci->op_regs->cmd_ring);

        /* Section 4.6.1.2 of xHCI 1.0 spec says software should also time the
         * completion of the Command Abort operation. If CRR is not negated in 5
         * seconds then driver handles it as if host died (-ENODEV).
         * In the future we should distinguish between -ENODEV and -ETIMEDOUT
         * and try to recover a -ETIMEDOUT with a host controller reset.
         */
        ret = xhci_handshake_check_state(xhci, &xhci->op_regs->cmd_ring,
                        CMD_RING_RUNNING, 0, 5 * 1000 * 1000,
                        XHCI_STATE_REMOVING);
        if (ret < 0) {
                xhci_err(xhci, "Abort failed to stop command ring: %d\n", ret);
                xhci_halt(xhci);
                xhci_hc_died(xhci);
                return ret;
        }
        /*
         * Writing the CMD_RING_ABORT bit should cause a cmd completion event,
         * however on some host hw the CMD_RING_RUNNING bit is correctly cleared
         * but the completion event in never sent. Wait 2 secs (arbitrary
         * number) to handle those cases after negation of CMD_RING_RUNNING.
         */
        spin_unlock_irqrestore(&xhci->lock, flags);
        ret = wait_for_completion_timeout(&xhci->cmd_ring_stop_completion,
                                          msecs_to_jiffies(2000));
        spin_lock_irqsave(&xhci->lock, flags);
        if (!ret) {
                xhci_dbg(xhci, "No stop event for abort, ring start fail?\n");
                xhci_cleanup_command_queue(xhci);
        } else {
                xhci_handle_stopped_cmd_ring(xhci, xhci_next_queued_cmd(xhci));
        }
        return 0;
}

void xhci_ring_ep_doorbell(struct xhci_hcd *xhci,
                unsigned int slot_id,
                unsigned int ep_index,
                unsigned int stream_id)
{
        __le32 __iomem *db_addr = &xhci->dba->doorbell[slot_id];
        struct xhci_virt_ep *ep = &xhci->devs[slot_id]->eps[ep_index];
        unsigned int ep_state = ep->ep_state;

        /* Don't ring the doorbell for this endpoint if there are pending
         * cancellations because we don't want to interrupt processing.
         * We don't want to restart any stream rings if there's a set dequeue
         * pointer command pending because the device can choose to start any
         * stream once the endpoint is on the HW schedule.
         */
        if ((ep_state & EP_STOP_CMD_PENDING) || (ep_state & SET_DEQ_PENDING) ||
            (ep_state & EP_HALTED) || (ep_state & EP_CLEARING_TT))
                return;

        trace_xhci_ring_ep_doorbell(slot_id, DB_VALUE(ep_index, stream_id));

        writel(DB_VALUE(ep_index, stream_id), db_addr);
        /* flush the write */
        readl(db_addr);
}

/* Ring the doorbell for any rings with pending URBs */
static void ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
                unsigned int slot_id,
                unsigned int ep_index)
{
        unsigned int stream_id;
        struct xhci_virt_ep *ep;

        ep = &xhci->devs[slot_id]->eps[ep_index];

        /* A ring has pending URBs if its TD list is not empty */
        if (!(ep->ep_state & EP_HAS_STREAMS)) {
                if (ep->ring && !(list_empty(&ep->ring->td_list)))
                        xhci_ring_ep_doorbell(xhci, slot_id, ep_index, 0);
                return;
        }

        for (stream_id = 1; stream_id < ep->stream_info->num_streams;
                        stream_id++) {
                struct xhci_stream_info *stream_info = ep->stream_info;
                if (!list_empty(&stream_info->stream_rings[stream_id]->td_list))
                        xhci_ring_ep_doorbell(xhci, slot_id, ep_index,
                                                stream_id);
        }
}

void xhci_ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
                unsigned int slot_id,
                unsigned int ep_index)
{
        ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
}

static struct xhci_virt_ep *xhci_get_virt_ep(struct xhci_hcd *xhci,
                                             unsigned int slot_id,
                                             unsigned int ep_index)
{
        if (slot_id == 0 || slot_id >= MAX_HC_SLOTS) {
                xhci_warn(xhci, "Invalid slot_id %u\n", slot_id);
                return NULL;
        }
        if (ep_index >= EP_CTX_PER_DEV) {
                xhci_warn(xhci, "Invalid endpoint index %u\n", ep_index);
                return NULL;
        }
        if (!xhci->devs[slot_id]) {
                xhci_warn(xhci, "No xhci virt device for slot_id %u\n", slot_id);
                return NULL;
        }

        return &xhci->devs[slot_id]->eps[ep_index];
}

static struct xhci_ring *xhci_virt_ep_to_ring(struct xhci_hcd *xhci,
                                              struct xhci_virt_ep *ep,
                                              unsigned int stream_id)
{
        /* common case, no streams */
        if (!(ep->ep_state & EP_HAS_STREAMS))
                return ep->ring;

        if (!ep->stream_info)
                return NULL;

        if (stream_id == 0 || stream_id >= ep->stream_info->num_streams) {
                xhci_warn(xhci, "Invalid stream_id %u request for slot_id %u ep_index %u\n",
                          stream_id, ep->vdev->slot_id, ep->ep_index);
                return NULL;
        }

        return ep->stream_info->stream_rings[stream_id];
}

/* Get the right ring for the given slot_id, ep_index and stream_id.
 * If the endpoint supports streams, boundary check the URB's stream ID.
 * If the endpoint doesn't support streams, return the singular endpoint ring.
 */
struct xhci_ring *xhci_triad_to_transfer_ring(struct xhci_hcd *xhci,
                unsigned int slot_id, unsigned int ep_index,
                unsigned int stream_id)
{
        struct xhci_virt_ep *ep;

        ep = xhci_get_virt_ep(xhci, slot_id, ep_index);
        if (!ep)
                return NULL;

        return xhci_virt_ep_to_ring(xhci, ep, stream_id);
}


/*
 * Get the hw dequeue pointer xHC stopped on, either directly from the
 * endpoint context, or if streams are in use from the stream context.
 * The returned hw_dequeue contains the lowest four bits with cycle state
 * and possbile stream context type.
 */
static u64 xhci_get_hw_deq(struct xhci_hcd *xhci, struct xhci_virt_device *vdev,
                           unsigned int ep_index, unsigned int stream_id)
{
        struct xhci_ep_ctx *ep_ctx;
        struct xhci_stream_ctx *st_ctx;
        struct xhci_virt_ep *ep;

        ep = &vdev->eps[ep_index];

        if (ep->ep_state & EP_HAS_STREAMS) {
                st_ctx = &ep->stream_info->stream_ctx_array[stream_id];
                return le64_to_cpu(st_ctx->stream_ring);
        }
        ep_ctx = xhci_get_ep_ctx(xhci, vdev->out_ctx, ep_index);
        return le64_to_cpu(ep_ctx->deq);
}

static int xhci_move_dequeue_past_td(struct xhci_hcd *xhci,
                                unsigned int slot_id, unsigned int ep_index,
                                unsigned int stream_id, struct xhci_td *td)
{
        struct xhci_virt_device *dev = xhci->devs[slot_id];
        struct xhci_virt_ep *ep = &dev->eps[ep_index];
        struct xhci_ring *ep_ring;
        struct xhci_command *cmd;
        struct xhci_segment *new_seg;
        union xhci_trb *new_deq;
        int new_cycle;
        dma_addr_t addr;
        u64 hw_dequeue;
        bool cycle_found = false;
        bool td_last_trb_found = false;
        u32 trb_sct = 0;
        int ret;

        ep_ring = xhci_triad_to_transfer_ring(xhci, slot_id,
                        ep_index, stream_id);
        if (!ep_ring) {
                xhci_warn(xhci, "WARN can't find new dequeue, invalid stream ID %u\n",
                          stream_id);
                return -ENODEV;
        }
        /*
         * A cancelled TD can complete with a stall if HW cached the trb.
         * In this case driver can't find td, but if the ring is empty we
         * can move the dequeue pointer to the current enqueue position.
         * We shouldn't hit this anymore as cached cancelled TRBs are given back
         * after clearing the cache, but be on the safe side and keep it anyway
         */
        if (!td) {
                if (list_empty(&ep_ring->td_list)) {
                        new_seg = ep_ring->enq_seg;
                        new_deq = ep_ring->enqueue;
                        new_cycle = ep_ring->cycle_state;
                        xhci_dbg(xhci, "ep ring empty, Set new dequeue = enqueue");
                        goto deq_found;
                } else {
                        xhci_warn(xhci, "Can't find new dequeue state, missing td\n");
                        return -EINVAL;
                }
        }

        hw_dequeue = xhci_get_hw_deq(xhci, dev, ep_index, stream_id);
        new_seg = ep_ring->deq_seg;
        new_deq = ep_ring->dequeue;
        new_cycle = hw_dequeue & 0x1;

        /*
         * We want to find the pointer, segment and cycle state of the new trb
         * (the one after current TD's last_trb). We know the cycle state at
         * hw_dequeue, so walk the ring until both hw_dequeue and last_trb are
         * found.
         */
        do {
                if (!cycle_found && xhci_trb_virt_to_dma(new_seg, new_deq)
                    == (dma_addr_t)(hw_dequeue & ~0xf)) {
                        cycle_found = true;
                        if (td_last_trb_found)
                                break;
                }
                if (new_deq == td->last_trb)
                        td_last_trb_found = true;

                if (cycle_found && trb_is_link(new_deq) &&
                    link_trb_toggles_cycle(new_deq))
                        new_cycle ^= 0x1;

                next_trb(xhci, ep_ring, &new_seg, &new_deq);

                /* Search wrapped around, bail out */
                if (new_deq == ep->ring->dequeue) {
                        xhci_err(xhci, "Error: Failed finding new dequeue state\n");
                        return -EINVAL;
                }

        } while (!cycle_found || !td_last_trb_found);

deq_found:

        /* Don't update the ring cycle state for the producer (us). */
        addr = xhci_trb_virt_to_dma(new_seg, new_deq);
        if (addr == 0) {
                xhci_warn(xhci, "Can't find dma of new dequeue ptr\n");
                xhci_warn(xhci, "deq seg = %p, deq ptr = %p\n", new_seg, new_deq);
                return -EINVAL;
        }

        if ((ep->ep_state & SET_DEQ_PENDING)) {
                xhci_warn(xhci, "Set TR Deq already pending, don't submit for 0x%pad\n",
                          &addr);
                return -EBUSY;
        }

        /* This function gets called from contexts where it cannot sleep */
        cmd = xhci_alloc_command(xhci, false, GFP_ATOMIC);
        if (!cmd) {
                xhci_warn(xhci, "Can't alloc Set TR Deq cmd 0x%pad\n", &addr);
                return -ENOMEM;
        }

        if (stream_id)
                trb_sct = SCT_FOR_TRB(SCT_PRI_TR);
        ret = queue_command(xhci, cmd,
                lower_32_bits(addr) | trb_sct | new_cycle,
                upper_32_bits(addr),
                STREAM_ID_FOR_TRB(stream_id), SLOT_ID_FOR_TRB(slot_id) |
                EP_ID_FOR_TRB(ep_index) | TRB_TYPE(TRB_SET_DEQ), false);
        if (ret < 0) {
                xhci_free_command(xhci, cmd);
                return ret;
        }
        ep->queued_deq_seg = new_seg;
        ep->queued_deq_ptr = new_deq;

        xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
                       "Set TR Deq ptr 0x%llx, cycle %u\n", addr, new_cycle);

        /* Stop the TD queueing code from ringing the doorbell until
         * this command completes.  The HC won't set the dequeue pointer
         * if the ring is running, and ringing the doorbell starts the
         * ring running.
         */
        ep->ep_state |= SET_DEQ_PENDING;
        xhci_ring_cmd_db(xhci);
        return 0;
}

/* flip_cycle means flip the cycle bit of all but the first and last TRB.
 * (The last TRB actually points to the ring enqueue pointer, which is not part
 * of this TD.)  This is used to remove partially enqueued isoc TDs from a ring.
 */
static void td_to_noop(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
                       struct xhci_td *td, bool flip_cycle)
{
        struct xhci_segment *seg        = td->start_seg;
        union xhci_trb *trb             = td->first_trb;

        while (1) {
                trb_to_noop(trb, TRB_TR_NOOP);

                /* flip cycle if asked to */
                if (flip_cycle && trb != td->first_trb && trb != td->last_trb)
                        trb->generic.field[3] ^= cpu_to_le32(TRB_CYCLE);

                if (trb == td->last_trb)
                        break;

                next_trb(xhci, ep_ring, &seg, &trb);
        }
}

/*
 * Must be called with xhci->lock held in interrupt context,
 * releases and re-acquires xhci->lock
 */
static void xhci_giveback_urb_in_irq(struct xhci_hcd *xhci,
                                     struct xhci_td *cur_td, int status)
{
        struct urb      *urb            = cur_td->urb;
        struct urb_priv *urb_priv       = urb->hcpriv;
        struct usb_hcd  *hcd            = bus_to_hcd(urb->dev->bus);

        if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS) {
                xhci_to_hcd(xhci)->self.bandwidth_isoc_reqs--;
                if (xhci_to_hcd(xhci)->self.bandwidth_isoc_reqs == 0) {
                        if (xhci->quirks & XHCI_AMD_PLL_FIX)
                                usb_amd_quirk_pll_enable();
                }
        }
        xhci_urb_free_priv(urb_priv);
        usb_hcd_unlink_urb_from_ep(hcd, urb);
        trace_xhci_urb_giveback(urb);
        usb_hcd_giveback_urb(hcd, urb, status);
}

static void xhci_unmap_td_bounce_buffer(struct xhci_hcd *xhci,
                struct xhci_ring *ring, struct xhci_td *td)
{
        struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
        struct xhci_segment *seg = td->bounce_seg;
        struct urb *urb = td->urb;
        size_t len;

        if (!ring || !seg || !urb)
                return;

        if (usb_urb_dir_out(urb)) {
                dma_unmap_single(dev, seg->bounce_dma, ring->bounce_buf_len,
                                 DMA_TO_DEVICE);
                return;
        }

        dma_unmap_single(dev, seg->bounce_dma, ring->bounce_buf_len,
                         DMA_FROM_DEVICE);
        /* for in tranfers we need to copy the data from bounce to sg */
        if (urb->num_sgs) {
                len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs, seg->bounce_buf,
                                           seg->bounce_len, seg->bounce_offs);
                if (len != seg->bounce_len)
                        xhci_warn(xhci, "WARN Wrong bounce buffer read length: %zu != %d\n",
                                  len, seg->bounce_len);
        } else {
                memcpy(urb->transfer_buffer + seg->bounce_offs, seg->bounce_buf,
                       seg->bounce_len);
        }
        seg->bounce_len = 0;
        seg->bounce_offs = 0;
}

static int xhci_td_cleanup(struct xhci_hcd *xhci, struct xhci_td *td,
                           struct xhci_ring *ep_ring, int status)
{
        struct urb *urb = NULL;

        /* Clean up the endpoint's TD list */
        urb = td->urb;

        /* if a bounce buffer was used to align this td then unmap it */
        xhci_unmap_td_bounce_buffer(xhci, ep_ring, td);

        /* Do one last check of the actual transfer length.
         * If the host controller said we transferred more data than the buffer
         * length, urb->actual_length will be a very big number (since it's
         * unsigned).  Play it safe and say we didn't transfer anything.
         */
        if (urb->actual_length > urb->transfer_buffer_length) {
                xhci_warn(xhci, "URB req %u and actual %u transfer length mismatch\n",
                          urb->transfer_buffer_length, urb->actual_length);
                urb->actual_length = 0;
                status = 0;
        }
        /* TD might be removed from td_list if we are giving back a cancelled URB */
        if (!list_empty(&td->td_list))
                list_del_init(&td->td_list);
        /* Giving back a cancelled URB, or if a slated TD completed anyway */
        if (!list_empty(&td->cancelled_td_list))
                list_del_init(&td->cancelled_td_list);

        inc_td_cnt(urb);
        /* Giveback the urb when all the tds are completed */
        if (last_td_in_urb(td)) {
                if ((urb->actual_length != urb->transfer_buffer_length &&
                     (urb->transfer_flags & URB_SHORT_NOT_OK)) ||
                    (status != 0 && !usb_endpoint_xfer_isoc(&urb->ep->desc)))
                        xhci_dbg(xhci, "Giveback URB %p, len = %d, expected = %d, status = %d\n",
                                 urb, urb->actual_length,
                                 urb->transfer_buffer_length, status);

                /* set isoc urb status to 0 just as EHCI, UHCI, and OHCI */
                if (usb_pipetype(urb->pipe) == PIPE_ISOCHRONOUS)
                        status = 0;
                xhci_giveback_urb_in_irq(xhci, td, status);
        }

        return 0;
}


/* Complete the cancelled URBs we unlinked from td_list. */
static void xhci_giveback_invalidated_tds(struct xhci_virt_ep *ep)
{
        struct xhci_ring *ring;
        struct xhci_td *td, *tmp_td;

        list_for_each_entry_safe(td, tmp_td, &ep->cancelled_td_list,
                                 cancelled_td_list) {

                ring = xhci_urb_to_transfer_ring(ep->xhci, td->urb);

                if (td->cancel_status == TD_CLEARED) {
                        xhci_dbg(ep->xhci, "%s: Giveback cancelled URB %p TD\n",
                                 __func__, td->urb);
                        xhci_td_cleanup(ep->xhci, td, ring, td->status);
                } else {
                        xhci_dbg(ep->xhci, "%s: Keep cancelled URB %p TD as cancel_status is %d\n",
                                 __func__, td->urb, td->cancel_status);
                }
                if (ep->xhci->xhc_state & XHCI_STATE_DYING)
                        return;
        }
}

static int xhci_reset_halted_ep(struct xhci_hcd *xhci, unsigned int slot_id,
                                unsigned int ep_index, enum xhci_ep_reset_type reset_type)
{
        struct xhci_command *command;
        int ret = 0;

        command = xhci_alloc_command(xhci, false, GFP_ATOMIC);
        if (!command) {
                ret = -ENOMEM;
                goto done;
        }

        xhci_dbg(xhci, "%s-reset ep %u, slot %u\n",
                 (reset_type == EP_HARD_RESET) ? "Hard" : "Soft",
                 ep_index, slot_id);

        ret = xhci_queue_reset_ep(xhci, command, slot_id, ep_index, reset_type);
done:
        if (ret)
                xhci_err(xhci, "ERROR queuing reset endpoint for slot %d ep_index %d, %d\n",
                         slot_id, ep_index, ret);
        return ret;
}

static int xhci_handle_halted_endpoint(struct xhci_hcd *xhci,
                                struct xhci_virt_ep *ep,
                                struct xhci_td *td,
                                enum xhci_ep_reset_type reset_type)
{
        unsigned int slot_id = ep->vdev->slot_id;
        int err;

        /*
         * Avoid resetting endpoint if link is inactive. Can cause host hang.
         * Device will be reset soon to recover the link so don't do anything
         */
        if (ep->vdev->flags & VDEV_PORT_ERROR)
                return -ENODEV;

        /* add td to cancelled list and let reset ep handler take care of it */
        if (reset_type == EP_HARD_RESET) {
                ep->ep_state |= EP_HARD_CLEAR_TOGGLE;
                if (td && list_empty(&td->cancelled_td_list)) {
                        list_add_tail(&td->cancelled_td_list, &ep->cancelled_td_list);
                        td->cancel_status = TD_HALTED;
                }
        }

        if (ep->ep_state & EP_HALTED) {
                xhci_dbg(xhci, "Reset ep command for ep_index %d already pending\n",
                         ep->ep_index);
                return 0;
        }

        err = xhci_reset_halted_ep(xhci, slot_id, ep->ep_index, reset_type);
        if (err)
                return err;

        ep->ep_state |= EP_HALTED;

        xhci_ring_cmd_db(xhci);

        return 0;
}

/*
 * Fix up the ep ring first, so HW stops executing cancelled TDs.
 * We have the xHCI lock, so nothing can modify this list until we drop it.
 * We're also in the event handler, so we can't get re-interrupted if another
 * Stop Endpoint command completes.
 *
 * only call this when ring is not in a running state
 */

static int xhci_invalidate_cancelled_tds(struct xhci_virt_ep *ep)
{
        struct xhci_hcd         *xhci;
        struct xhci_td          *td = NULL;
        struct xhci_td          *tmp_td = NULL;
        struct xhci_td          *cached_td = NULL;
        struct xhci_ring        *ring;
        u64                     hw_deq;
        unsigned int            slot_id = ep->vdev->slot_id;
        int                     err;

        xhci = ep->xhci;

        list_for_each_entry_safe(td, tmp_td, &ep->cancelled_td_list, cancelled_td_list) {
                xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
                               "Removing canceled TD starting at 0x%llx (dma) in stream %u URB %p",
                               (unsigned long long)xhci_trb_virt_to_dma(
                                       td->start_seg, td->first_trb),
                               td->urb->stream_id, td->urb);
                list_del_init(&td->td_list);
                ring = xhci_urb_to_transfer_ring(xhci, td->urb);
                if (!ring) {
                        xhci_warn(xhci, "WARN Cancelled URB %p has invalid stream ID %u.\n",
                                  td->urb, td->urb->stream_id);
                        continue;
                }
                /*
                 * If a ring stopped on the TD we need to cancel then we have to
                 * move the xHC endpoint ring dequeue pointer past this TD.
                 * Rings halted due to STALL may show hw_deq is past the stalled
                 * TD, but still require a set TR Deq command to flush xHC cache.
                 */
                hw_deq = xhci_get_hw_deq(xhci, ep->vdev, ep->ep_index,
                                         td->urb->stream_id);
                hw_deq &= ~0xf;

                if (td->cancel_status == TD_HALTED ||
                    trb_in_td(xhci, td->start_seg, td->first_trb, td->last_trb, hw_deq, false)) {
                        switch (td->cancel_status) {
                        case TD_CLEARED: /* TD is already no-op */
                        case TD_CLEARING_CACHE: /* set TR deq command already queued */
                                break;
                        case TD_DIRTY: /* TD is cached, clear it */
                        case TD_HALTED:
                                td->cancel_status = TD_CLEARING_CACHE;
                                if (cached_td)
                                        /* FIXME  stream case, several stopped rings */
                                        xhci_dbg(xhci,
                                                 "Move dq past stream %u URB %p instead of stream %u URB %p\n",
                                                 td->urb->stream_id, td->urb,
                                                 cached_td->urb->stream_id, cached_td->urb);
                                cached_td = td;
                                break;
                        }
                } else {
                        td_to_noop(xhci, ring, td, false);
                        td->cancel_status = TD_CLEARED;
                }
        }

        /* If there's no need to move the dequeue pointer then we're done */
        if (!cached_td)
                return 0;

        err = xhci_move_dequeue_past_td(xhci, slot_id, ep->ep_index,
                                        cached_td->urb->stream_id,
                                        cached_td);
        if (err) {
                /* Failed to move past cached td, just set cached TDs to no-op */
                list_for_each_entry_safe(td, tmp_td, &ep->cancelled_td_list, cancelled_td_list) {
                        if (td->cancel_status != TD_CLEARING_CACHE)
                                continue;
                        xhci_dbg(xhci, "Failed to clear cancelled cached URB %p, mark clear anyway\n",
                                 td->urb);
                        td_to_noop(xhci, ring, td, false);
                        td->cancel_status = TD_CLEARED;
                }
        }
        return 0;
}

/*
 * Returns the TD the endpoint ring halted on.
 * Only call for non-running rings without streams.
 */
static struct xhci_td *find_halted_td(struct xhci_virt_ep *ep)
{
        struct xhci_td  *td;
        u64             hw_deq;

        if (!list_empty(&ep->ring->td_list)) { /* Not streams compatible */
                hw_deq = xhci_get_hw_deq(ep->xhci, ep->vdev, ep->ep_index, 0);
                hw_deq &= ~0xf;
                td = list_first_entry(&ep->ring->td_list, struct xhci_td, td_list);
                if (trb_in_td(ep->xhci, td->start_seg, td->first_trb,
                                td->last_trb, hw_deq, false))
                        return td;
        }
        return NULL;
}

/*
 * When we get a command completion for a Stop Endpoint Command, we need to
 * unlink any cancelled TDs from the ring.  There are two ways to do that:
 *
 *  1. If the HW was in the middle of processing the TD that needs to be
 *     cancelled, then we must move the ring's dequeue pointer past the last TRB
 *     in the TD with a Set Dequeue Pointer Command.
 *  2. Otherwise, we turn all the TRBs in the TD into No-op TRBs (with the chain
 *     bit cleared) so that the HW will skip over them.
 */
static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id,
                                    union xhci_trb *trb, u32 comp_code)
{
        unsigned int ep_index;
        struct xhci_virt_ep *ep;
        struct xhci_ep_ctx *ep_ctx;
        struct xhci_td *td = NULL;
        enum xhci_ep_reset_type reset_type;
        struct xhci_command *command;
        int err;

        if (unlikely(TRB_TO_SUSPEND_PORT(le32_to_cpu(trb->generic.field[3])))) {
                if (!xhci->devs[slot_id])
                        xhci_warn(xhci, "Stop endpoint command completion for disabled slot %u\n",
                                  slot_id);
                return;
        }

        ep_index = TRB_TO_EP_INDEX(le32_to_cpu(trb->generic.field[3]));
        ep = xhci_get_virt_ep(xhci, slot_id, ep_index);
        if (!ep)
                return;

        ep_ctx = xhci_get_ep_ctx(xhci, ep->vdev->out_ctx, ep_index);

        trace_xhci_handle_cmd_stop_ep(ep_ctx);

        if (comp_code == COMP_CONTEXT_STATE_ERROR) {
        /*
         * If stop endpoint command raced with a halting endpoint we need to
         * reset the host side endpoint first.
         * If the TD we halted on isn't cancelled the TD should be given back
         * with a proper error code, and the ring dequeue moved past the TD.
         * If streams case we can't find hw_deq, or the TD we halted on so do a
         * soft reset.
         *
         * Proper error code is unknown here, it would be -EPIPE if device side
         * of enadpoit halted (aka STALL), and -EPROTO if not (transaction error)
         * We use -EPROTO, if device is stalled it should return a stall error on
         * next transfer, which then will return -EPIPE, and device side stall is
         * noted and cleared by class driver.
         */
                switch (GET_EP_CTX_STATE(ep_ctx)) {
                case EP_STATE_HALTED:
                        xhci_dbg(xhci, "Stop ep completion raced with stall, reset ep\n");
                        if (ep->ep_state & EP_HAS_STREAMS) {
                                reset_type = EP_SOFT_RESET;
                        } else {
                                reset_type = EP_HARD_RESET;
                                td = find_halted_td(ep);
                                if (td)
                                        td->status = -EPROTO;
                        }
                        /* reset ep, reset handler cleans up cancelled tds */
                        err = xhci_handle_halted_endpoint(xhci, ep, td, reset_type);
                        if (err)
                                break;
                        ep->ep_state &= ~EP_STOP_CMD_PENDING;
                        return;
                case EP_STATE_STOPPED:
                        /*
                         * NEC uPD720200 sometimes sets this state and fails with
                         * Context Error while continuing to process TRBs.
                         * Be conservative and trust EP_CTX_STATE on other chips.
                         */
                        if (!(xhci->quirks & XHCI_NEC_HOST))
                                break;
                        fallthrough;
                case EP_STATE_RUNNING:
                        /* Race, HW handled stop ep cmd before ep was running */
                        xhci_dbg(xhci, "Stop ep completion ctx error, ep is running\n");

                        command = xhci_alloc_command(xhci, false, GFP_ATOMIC);
                        if (!command) {
                                ep->ep_state &= ~EP_STOP_CMD_PENDING;
                                return;
                        }
                        xhci_queue_stop_endpoint(xhci, command, slot_id, ep_index, 0);
                        xhci_ring_cmd_db(xhci);

                        return;
                default:
                        break;
                }
        }

        /* will queue a set TR deq if stopped on a cancelled, uncleared TD */
        xhci_invalidate_cancelled_tds(ep);
        ep->ep_state &= ~EP_STOP_CMD_PENDING;

        /* Otherwise ring the doorbell(s) to restart queued transfers */
        xhci_giveback_invalidated_tds(ep);
        ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
}

static void xhci_kill_ring_urbs(struct xhci_hcd *xhci, struct xhci_ring *ring)
{
        struct xhci_td *cur_td;
        struct xhci_td *tmp;

        list_for_each_entry_safe(cur_td, tmp, &ring->td_list, td_list) {
                list_del_init(&cur_td->td_list);

                if (!list_empty(&cur_td->cancelled_td_list))
                        list_del_init(&cur_td->cancelled_td_list);

                xhci_unmap_td_bounce_buffer(xhci, ring, cur_td);

                inc_td_cnt(cur_td->urb);
                if (last_td_in_urb(cur_td))
                        xhci_giveback_urb_in_irq(xhci, cur_td, -ESHUTDOWN);
        }
}

static void xhci_kill_endpoint_urbs(struct xhci_hcd *xhci,
                int slot_id, int ep_index)
{
        struct xhci_td *cur_td;
        struct xhci_td *tmp;
        struct xhci_virt_ep *ep;
        struct xhci_ring *ring;

        ep = xhci_get_virt_ep(xhci, slot_id, ep_index);
        if (!ep)
                return;

        if ((ep->ep_state & EP_HAS_STREAMS) ||
                        (ep->ep_state & EP_GETTING_NO_STREAMS)) {
                int stream_id;

                for (stream_id = 1; stream_id < ep->stream_info->num_streams;
                                stream_id++) {
                        ring = ep->stream_info->stream_rings[stream_id];
                        if (!ring)
                                continue;

                        xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
                                        "Killing URBs for slot ID %u, ep index %u, stream %u",
                                        slot_id, ep_index, stream_id);
                        xhci_kill_ring_urbs(xhci, ring);
                }
        } else {
                ring = ep->ring;
                if (!ring)
                        return;
                xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
                                "Killing URBs for slot ID %u, ep index %u",
                                slot_id, ep_index);
                xhci_kill_ring_urbs(xhci, ring);
        }

        list_for_each_entry_safe(cur_td, tmp, &ep->cancelled_td_list,
                        cancelled_td_list) {
                list_del_init(&cur_td->cancelled_td_list);
                inc_td_cnt(cur_td->urb);

                if (last_td_in_urb(cur_td))
                        xhci_giveback_urb_in_irq(xhci, cur_td, -ESHUTDOWN);
        }
}

/*
 * host controller died, register read returns 0xffffffff
 * Complete pending commands, mark them ABORTED.
 * URBs need to be given back as usb core might be waiting with device locks
 * held for the URBs to finish during device disconnect, blocking host remove.
 *
 * Call with xhci->lock held.
 * lock is relased and re-acquired while giving back urb.
 */
void xhci_hc_died(struct xhci_hcd *xhci)
{
        int i, j;

        if (xhci->xhc_state & XHCI_STATE_DYING)
                return;

        xhci_err(xhci, "xHCI host controller not responding, assume dead\n");
        xhci->xhc_state |= XHCI_STATE_DYING;

        xhci_cleanup_command_queue(xhci);

        /* return any pending urbs, remove may be waiting for them */
        for (i = 0; i <= HCS_MAX_SLOTS(xhci->hcs_params1); i++) {
                if (!xhci->devs[i])
                        continue;
                for (j = 0; j < 31; j++)
                        xhci_kill_endpoint_urbs(xhci, i, j);
        }

        /* inform usb core hc died if PCI remove isn't already handling it */
        if (!(xhci->xhc_state & XHCI_STATE_REMOVING))
                usb_hc_died(xhci_to_hcd(xhci));
}

static void update_ring_for_set_deq_completion(struct xhci_hcd *xhci,
                struct xhci_virt_device *dev,
                struct xhci_ring *ep_ring,
                unsigned int ep_index)
{
        union xhci_trb *dequeue_temp;

        dequeue_temp = ep_ring->dequeue;

        /* If we get two back-to-back stalls, and the first stalled transfer
         * ends just before a link TRB, the dequeue pointer will be left on
         * the link TRB by the code in the while loop.  So we have to update
         * the dequeue pointer one segment further, or we'll jump off
         * the segment into la-la-land.
         */
        if (trb_is_link(ep_ring->dequeue)) {
                ep_ring->deq_seg = ep_ring->deq_seg->next;
                ep_ring->dequeue = ep_ring->deq_seg->trbs;
        }

        while (ep_ring->dequeue != dev->eps[ep_index].queued_deq_ptr) {
                /* We have more usable TRBs */
                ep_ring->dequeue++;
                if (trb_is_link(ep_ring->dequeue)) {
                        if (ep_ring->dequeue ==
                                        dev->eps[ep_index].queued_deq_ptr)
                                break;
                        ep_ring->deq_seg = ep_ring->deq_seg->next;
                        ep_ring->dequeue = ep_ring->deq_seg->trbs;
                }
                if (ep_ring->dequeue == dequeue_temp) {
                        xhci_dbg(xhci, "Unable to find new dequeue pointer\n");
                        break;
                }
        }
}

/*
 * When we get a completion for a Set Transfer Ring Dequeue Pointer command,
 * we need to clear the set deq pending flag in the endpoint ring state, so that
 * the TD queueing code can ring the doorbell again.  We also need to ring the
 * endpoint doorbell to restart the ring, but only if there aren't more
 * cancellations pending.
 */
static void xhci_handle_cmd_set_deq(struct xhci_hcd *xhci, int slot_id,
                union xhci_trb *trb, u32 cmd_comp_code)
{
        unsigned int ep_index;
        unsigned int stream_id;
        struct xhci_ring *ep_ring;
        struct xhci_virt_ep *ep;
        struct xhci_ep_ctx *ep_ctx;
        struct xhci_slot_ctx *slot_ctx;
        struct xhci_td *td, *tmp_td;

        ep_index = TRB_TO_EP_INDEX(le32_to_cpu(trb->generic.field[3]));
        stream_id = TRB_TO_STREAM_ID(le32_to_cpu(trb->generic.field[2]));
        ep = xhci_get_virt_ep(xhci, slot_id, ep_index);
        if (!ep)
                return;

        ep_ring = xhci_virt_ep_to_ring(xhci, ep, stream_id);
        if (!ep_ring) {
                xhci_warn(xhci, "WARN Set TR deq ptr command for freed stream ID %u\n",
                                stream_id);
                /* XXX: Harmless??? */
                goto cleanup;
        }

        ep_ctx = xhci_get_ep_ctx(xhci, ep->vdev->out_ctx, ep_index);
        slot_ctx = xhci_get_slot_ctx(xhci, ep->vdev->out_ctx);
        trace_xhci_handle_cmd_set_deq(slot_ctx);
        trace_xhci_handle_cmd_set_deq_ep(ep_ctx);

        if (cmd_comp_code != COMP_SUCCESS) {
                unsigned int ep_state;
                unsigned int slot_state;

                switch (cmd_comp_code) {
                case COMP_TRB_ERROR:
                        xhci_warn(xhci, "WARN Set TR Deq Ptr cmd invalid because of stream ID configuration\n");
                        break;
                case COMP_CONTEXT_STATE_ERROR:
                        xhci_warn(xhci, "WARN Set TR Deq Ptr cmd failed due to incorrect slot or ep state.\n");
                        ep_state = GET_EP_CTX_STATE(ep_ctx);
                        slot_state = le32_to_cpu(slot_ctx->dev_state);
                        slot_state = GET_SLOT_STATE(slot_state);
                        xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
                                        "Slot state = %u, EP state = %u",
                                        slot_state, ep_state);
                        break;
                case COMP_SLOT_NOT_ENABLED_ERROR:
                        xhci_warn(xhci, "WARN Set TR Deq Ptr cmd failed because slot %u was not enabled.\n",
                                        slot_id);
                        break;
                default:
                        xhci_warn(xhci, "WARN Set TR Deq Ptr cmd with unknown completion code of %u.\n",
                                        cmd_comp_code);
                        break;
                }
                /* OK what do we do now?  The endpoint state is hosed, and we
                 * should never get to this point if the synchronization between
                 * queueing, and endpoint state are correct.  This might happen
                 * if the device gets disconnected after we've finished
                 * cancelling URBs, which might not be an error...
                 */
        } else {
                u64 deq;
                /* 4.6.10 deq ptr is written to the stream ctx for streams */
                if (ep->ep_state & EP_HAS_STREAMS) {
                        struct xhci_stream_ctx *ctx =
                                &ep->stream_info->stream_ctx_array[stream_id];
                        deq = le64_to_cpu(ctx->stream_ring) & SCTX_DEQ_MASK;
                } else {
                        deq = le64_to_cpu(ep_ctx->deq) & ~EP_CTX_CYCLE_MASK;
                }
                xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
                        "Successful Set TR Deq Ptr cmd, deq = @%08llx", deq);
                if (xhci_trb_virt_to_dma(ep->queued_deq_seg,
                                         ep->queued_deq_ptr) == deq) {
                        /* Update the ring's dequeue segment and dequeue pointer
                         * to reflect the new position.
                         */
                        update_ring_for_set_deq_completion(xhci, ep->vdev,
                                ep_ring, ep_index);
                } else {
                        xhci_warn(xhci, "Mismatch between completed Set TR Deq Ptr command & xHCI internal state.\n");
                        xhci_warn(xhci, "ep deq seg = %p, deq ptr = %p\n",
                                  ep->queued_deq_seg, ep->queued_deq_ptr);
                }
        }
        /* HW cached TDs cleared from cache, give them back */
        list_for_each_entry_safe(td, tmp_td, &ep->cancelled_td_list,
                                 cancelled_td_list) {
                ep_ring = xhci_urb_to_transfer_ring(ep->xhci, td->urb);
                if (td->cancel_status == TD_CLEARING_CACHE) {
                        td->cancel_status = TD_CLEARED;
                        xhci_dbg(ep->xhci, "%s: Giveback cancelled URB %p TD\n",
                                 __func__, td->urb);
                        xhci_td_cleanup(ep->xhci, td, ep_ring, td->status);
                } else {
                        xhci_dbg(ep->xhci, "%s: Keep cancelled URB %p TD as cancel_status is %d\n",
                                 __func__, td->urb, td->cancel_status);
                }
        }
cleanup:
        ep->ep_state &= ~SET_DEQ_PENDING;
        ep->queued_deq_seg = NULL;
        ep->queued_deq_ptr = NULL;
        /* Restart any rings with pending URBs */
        ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
}

static void xhci_handle_cmd_reset_ep(struct xhci_hcd *xhci, int slot_id,
                union xhci_trb *trb, u32 cmd_comp_code)
{
        struct xhci_virt_ep *ep;
        struct xhci_ep_ctx *ep_ctx;
        unsigned int ep_index;

        ep_index = TRB_TO_EP_INDEX(le32_to_cpu(trb->generic.field[3]));
        ep = xhci_get_virt_ep(xhci, slot_id, ep_index);
        if (!ep)
                return;

        ep_ctx = xhci_get_ep_ctx(xhci, ep->vdev->out_ctx, ep_index);
        trace_xhci_handle_cmd_reset_ep(ep_ctx);

        /* This command will only fail if the endpoint wasn't halted,
         * but we don't care.
         */
        xhci_dbg_trace(xhci, trace_xhci_dbg_reset_ep,
                "Ignoring reset ep completion code of %u", cmd_comp_code);

        /* Cleanup cancelled TDs as ep is stopped. May queue a Set TR Deq cmd */
        xhci_invalidate_cancelled_tds(ep);

        /* Clear our internal halted state */
        ep->ep_state &= ~EP_HALTED;

        xhci_giveback_invalidated_tds(ep);

        /* if this was a soft reset, then restart */
        if ((le32_to_cpu(trb->generic.field[3])) & TRB_TSP)
                ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
}

static void xhci_handle_cmd_enable_slot(struct xhci_hcd *xhci, int slot_id,
                struct xhci_command *command, u32 cmd_comp_code)
{
        if (cmd_comp_code == COMP_SUCCESS)
                command->slot_id = slot_id;
        else
                command->slot_id = 0;
}

static void xhci_handle_cmd_disable_slot(struct xhci_hcd *xhci, int slot_id)
{
        struct xhci_virt_device *virt_dev;
        struct xhci_slot_ctx *slot_ctx;

        virt_dev = xhci->devs[slot_id];
        if (!virt_dev)
                return;

        slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->out_ctx);
        trace_xhci_handle_cmd_disable_slot(slot_ctx);

        if (xhci->quirks & XHCI_EP_LIMIT_QUIRK)
                /* Delete default control endpoint resources */
                xhci_free_device_endpoint_resources(xhci, virt_dev, true);
}

static void xhci_handle_cmd_config_ep(struct xhci_hcd *xhci, int slot_id,
                u32 cmd_comp_code)
{
        struct xhci_virt_device *virt_dev;
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_ep_ctx *ep_ctx;
        unsigned int ep_index;
        u32 add_flags;

        /*
         * Configure endpoint commands can come from the USB core configuration
         * or alt setting changes, or when streams were being configured.
         */

        virt_dev = xhci->devs[slot_id];
        if (!virt_dev)
                return;
        ctrl_ctx = xhci_get_input_control_ctx(virt_dev->in_ctx);
        if (!ctrl_ctx) {
                xhci_warn(xhci, "Could not get input context, bad type.\n");
                return;
        }

        add_flags = le32_to_cpu(ctrl_ctx->add_flags);

        /* Input ctx add_flags are the endpoint index plus one */
        ep_index = xhci_last_valid_endpoint(add_flags) - 1;

        ep_ctx = xhci_get_ep_ctx(xhci, virt_dev->out_ctx, ep_index);
        trace_xhci_handle_cmd_config_ep(ep_ctx);

        return;
}

static void xhci_handle_cmd_addr_dev(struct xhci_hcd *xhci, int slot_id)
{
        struct xhci_virt_device *vdev;
        struct xhci_slot_ctx *slot_ctx;

        vdev = xhci->devs[slot_id];
        if (!vdev)
                return;
        slot_ctx = xhci_get_slot_ctx(xhci, vdev->out_ctx);
        trace_xhci_handle_cmd_addr_dev(slot_ctx);
}

static void xhci_handle_cmd_reset_dev(struct xhci_hcd *xhci, int slot_id)
{
        struct xhci_virt_device *vdev;
        struct xhci_slot_ctx *slot_ctx;

        vdev = xhci->devs[slot_id];
        if (!vdev) {
                xhci_warn(xhci, "Reset device command completion for disabled slot %u\n",
                          slot_id);
                return;
        }
        slot_ctx = xhci_get_slot_ctx(xhci, vdev->out_ctx);
        trace_xhci_handle_cmd_reset_dev(slot_ctx);

        xhci_dbg(xhci, "Completed reset device command.\n");
}

static void xhci_handle_cmd_nec_get_fw(struct xhci_hcd *xhci,
                struct xhci_event_cmd *event)
{
        if (!(xhci->quirks & XHCI_NEC_HOST)) {
                xhci_warn(xhci, "WARN NEC_GET_FW command on non-NEC host\n");
                return;
        }
        xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
                        "NEC firmware version %2x.%02x",
                        NEC_FW_MAJOR(le32_to_cpu(event->status)),
                        NEC_FW_MINOR(le32_to_cpu(event->status)));
}

static void xhci_complete_del_and_free_cmd(struct xhci_command *cmd, u32 status)
{
        list_del(&cmd->cmd_list);

        if (cmd->completion) {
                cmd->status = status;
                complete(cmd->completion);
        } else {
                kfree(cmd);
        }
}

void xhci_cleanup_command_queue(struct xhci_hcd *xhci)
{
        struct xhci_command *cur_cmd, *tmp_cmd;
        xhci->current_cmd = NULL;
        list_for_each_entry_safe(cur_cmd, tmp_cmd, &xhci->cmd_list, cmd_list)
                xhci_complete_del_and_free_cmd(cur_cmd, COMP_COMMAND_ABORTED);
}

void xhci_handle_command_timeout(struct work_struct *work)
{
        struct xhci_hcd *xhci;
        unsigned long   flags;
        char            str[XHCI_MSG_MAX];
        u64             hw_ring_state;
        u32             cmd_field3;
        u32             usbsts;

        xhci = container_of(to_delayed_work(work), struct xhci_hcd, cmd_timer);

        spin_lock_irqsave(&xhci->lock, flags);

        /*
         * If timeout work is pending, or current_cmd is NULL, it means we
         * raced with command completion. Command is handled so just return.
         */
        if (!xhci->current_cmd || delayed_work_pending(&xhci->cmd_timer)) {
                spin_unlock_irqrestore(&xhci->lock, flags);
                return;
        }

        cmd_field3 = le32_to_cpu(xhci->current_cmd->command_trb->generic.field[3]);
        usbsts = readl(&xhci->op_regs->status);
        xhci_dbg(xhci, "Command timeout, USBSTS:%s\n", xhci_decode_usbsts(str, usbsts));

        /* Bail out and tear down xhci if a stop endpoint command failed */
        if (TRB_FIELD_TO_TYPE(cmd_field3) == TRB_STOP_RING) {
                struct xhci_virt_ep     *ep;

                xhci_warn(xhci, "xHCI host not responding to stop endpoint command\n");

                ep = xhci_get_virt_ep(xhci, TRB_TO_SLOT_ID(cmd_field3),
                                      TRB_TO_EP_INDEX(cmd_field3));
                if (ep)
                        ep->ep_state &= ~EP_STOP_CMD_PENDING;

                xhci_halt(xhci);
                xhci_hc_died(xhci);
                goto time_out_completed;
        }

        /* mark this command to be cancelled */
        xhci->current_cmd->status = COMP_COMMAND_ABORTED;

        /* Make sure command ring is running before aborting it */
        hw_ring_state = xhci_read_64(xhci, &xhci->op_regs->cmd_ring);
        if (hw_ring_state == ~(u64)0) {
                xhci_hc_died(xhci);
                goto time_out_completed;
        }

        if ((xhci->cmd_ring_state & CMD_RING_STATE_RUNNING) &&
            (hw_ring_state & CMD_RING_RUNNING))  {
                /* Prevent new doorbell, and start command abort */
                xhci->cmd_ring_state = CMD_RING_STATE_ABORTED;
                xhci_dbg(xhci, "Command timeout\n");
                xhci_abort_cmd_ring(xhci, flags);
                goto time_out_completed;
        }

        /* host removed. Bail out */
        if (xhci->xhc_state & XHCI_STATE_REMOVING) {
                xhci_dbg(xhci, "host removed, ring start fail?\n");
                xhci_cleanup_command_queue(xhci);

                goto time_out_completed;
        }

        /* command timeout on stopped ring, ring can't be aborted */
        xhci_dbg(xhci, "Command timeout on stopped ring\n");
        xhci_handle_stopped_cmd_ring(xhci, xhci->current_cmd);

time_out_completed:
        spin_unlock_irqrestore(&xhci->lock, flags);
        return;
}

static void handle_cmd_completion(struct xhci_hcd *xhci,
                struct xhci_event_cmd *event)
{
        unsigned int slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
        u64 cmd_dma;
        dma_addr_t cmd_dequeue_dma;
        u32 cmd_comp_code;
        union xhci_trb *cmd_trb;
        struct xhci_command *cmd;
        u32 cmd_type;

        if (slot_id >= MAX_HC_SLOTS) {
                xhci_warn(xhci, "Invalid slot_id %u\n", slot_id);
                return;
        }

        cmd_dma = le64_to_cpu(event->cmd_trb);
        cmd_trb = xhci->cmd_ring->dequeue;

        trace_xhci_handle_command(xhci->cmd_ring, &cmd_trb->generic);

        cmd_dequeue_dma = xhci_trb_virt_to_dma(xhci->cmd_ring->deq_seg,
                        cmd_trb);
        /*
         * Check whether the completion event is for our internal kept
         * command.
         */
        if (!cmd_dequeue_dma || cmd_dma != (u64)cmd_dequeue_dma) {
                xhci_warn(xhci,
                          "ERROR mismatched command completion event\n");
                return;
        }

        cmd = list_first_entry(&xhci->cmd_list, struct xhci_command, cmd_list);

        cancel_delayed_work(&xhci->cmd_timer);

        cmd_comp_code = GET_COMP_CODE(le32_to_cpu(event->status));

        /* If CMD ring stopped we own the trbs between enqueue and dequeue */
        if (cmd_comp_code == COMP_COMMAND_RING_STOPPED) {
                complete_all(&xhci->cmd_ring_stop_completion);
                return;
        }

        if (cmd->command_trb != xhci->cmd_ring->dequeue) {
                xhci_err(xhci,
                         "Command completion event does not match command\n");
                return;
        }

        /*
         * Host aborted the command ring, check if the current command was
         * supposed to be aborted, otherwise continue normally.
         * The command ring is stopped now, but the xHC will issue a Command
         * Ring Stopped event which will cause us to restart it.
         */
        if (cmd_comp_code == COMP_COMMAND_ABORTED) {
                xhci->cmd_ring_state = CMD_RING_STATE_STOPPED;
                if (cmd->status == COMP_COMMAND_ABORTED) {
                        if (xhci->current_cmd == cmd)
                                xhci->current_cmd = NULL;
                        goto event_handled;
                }
        }

        cmd_type = TRB_FIELD_TO_TYPE(le32_to_cpu(cmd_trb->generic.field[3]));
        switch (cmd_type) {
        case TRB_ENABLE_SLOT:
                xhci_handle_cmd_enable_slot(xhci, slot_id, cmd, cmd_comp_code);
                break;
        case TRB_DISABLE_SLOT:
                xhci_handle_cmd_disable_slot(xhci, slot_id);
                break;
        case TRB_CONFIG_EP:
                if (!cmd->completion)
                        xhci_handle_cmd_config_ep(xhci, slot_id, cmd_comp_code);
                break;
        case TRB_EVAL_CONTEXT:
                break;
        case TRB_ADDR_DEV:
                xhci_handle_cmd_addr_dev(xhci, slot_id);
                break;
        case TRB_STOP_RING:
                WARN_ON(slot_id != TRB_TO_SLOT_ID(
                                le32_to_cpu(cmd_trb->generic.field[3])));
                if (!cmd->completion)
                        xhci_handle_cmd_stop_ep(xhci, slot_id, cmd_trb,
                                                cmd_comp_code);
                break;
        case TRB_SET_DEQ:
                WARN_ON(slot_id != TRB_TO_SLOT_ID(
                                le32_to_cpu(cmd_trb->generic.field[3])));
                xhci_handle_cmd_set_deq(xhci, slot_id, cmd_trb, cmd_comp_code);
                break;
        case TRB_CMD_NOOP:
                /* Is this an aborted command turned to NO-OP? */
                if (cmd->status == COMP_COMMAND_RING_STOPPED)
                        cmd_comp_code = COMP_COMMAND_RING_STOPPED;
                break;
        case TRB_RESET_EP:
                WARN_ON(slot_id != TRB_TO_SLOT_ID(
                                le32_to_cpu(cmd_trb->generic.field[3])));
                xhci_handle_cmd_reset_ep(xhci, slot_id, cmd_trb, cmd_comp_code);
                break;
        case TRB_RESET_DEV:
                /* SLOT_ID field in reset device cmd completion event TRB is 0.
                 * Use the SLOT_ID from the command TRB instead (xhci 4.6.11)
                 */
                slot_id = TRB_TO_SLOT_ID(
                                le32_to_cpu(cmd_trb->generic.field[3]));
                xhci_handle_cmd_reset_dev(xhci, slot_id);
                break;
        case TRB_NEC_GET_FW:
                xhci_handle_cmd_nec_get_fw(xhci, event);
                break;
        default:
                /* Skip over unknown commands on the event ring */
                xhci_info(xhci, "INFO unknown command type %d\n", cmd_type);
                break;
        }

        /* restart timer if this wasn't the last command */
        if (!list_is_singular(&xhci->cmd_list)) {
                xhci->current_cmd = list_first_entry(&cmd->cmd_list,
                                                struct xhci_command, cmd_list);
                xhci_mod_cmd_timer(xhci);
        } else if (xhci->current_cmd == cmd) {
                xhci->current_cmd = NULL;
        }

event_handled:
        xhci_complete_del_and_free_cmd(cmd, cmd_comp_code);

        inc_deq(xhci, xhci->cmd_ring);
}

static void handle_vendor_event(struct xhci_hcd *xhci,
                                union xhci_trb *event, u32 trb_type)
{
        xhci_dbg(xhci, "Vendor specific event TRB type = %u\n", trb_type);
        if (trb_type == TRB_NEC_CMD_COMP && (xhci->quirks & XHCI_NEC_HOST))
                handle_cmd_completion(xhci, &event->event_cmd);
}

static void handle_device_notification(struct xhci_hcd *xhci,
                union xhci_trb *event)
{
        u32 slot_id;
        struct usb_device *udev;

        slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->generic.field[3]));
        if (!xhci->devs[slot_id]) {
                xhci_warn(xhci, "Device Notification event for "
                                "unused slot %u\n", slot_id);
                return;
        }

        xhci_dbg(xhci, "Device Wake Notification event for slot ID %u\n",
                        slot_id);
        udev = xhci->devs[slot_id]->udev;
        if (udev && udev->parent)
                usb_wakeup_notification(udev->parent, udev->portnum);
}

/*
 * Quirk hanlder for errata seen on Cavium ThunderX2 processor XHCI
 * Controller.
 * As per ThunderX2errata-129 USB 2 device may come up as USB 1
 * If a connection to a USB 1 device is followed by another connection
 * to a USB 2 device.
 *
 * Reset the PHY after the USB device is disconnected if device speed
 * is less than HCD_USB3.
 * Retry the reset sequence max of 4 times checking the PLL lock status.
 *
 */
static void xhci_cavium_reset_phy_quirk(struct xhci_hcd *xhci)
{
        struct usb_hcd *hcd = xhci_to_hcd(xhci);
        u32 pll_lock_check;
        u32 retry_count = 4;

        do {
                /* Assert PHY reset */
                writel(0x6F, hcd->regs + 0x1048);
                udelay(10);
                /* De-assert the PHY reset */
                writel(0x7F, hcd->regs + 0x1048);
                udelay(200);
                pll_lock_check = readl(hcd->regs + 0x1070);
        } while (!(pll_lock_check & 0x1) && --retry_count);
}

static void handle_port_status(struct xhci_hcd *xhci,
                               struct xhci_interrupter *ir,
                               union xhci_trb *event)
{
        struct usb_hcd *hcd;
        u32 port_id;
        u32 portsc, cmd_reg;
        int max_ports;
        unsigned int hcd_portnum;
        struct xhci_bus_state *bus_state;
        bool bogus_port_status = false;
        struct xhci_port *port;

        /* Port status change events always have a successful completion code */
        if (GET_COMP_CODE(le32_to_cpu(event->generic.field[2])) != COMP_SUCCESS)
                xhci_warn(xhci,
                          "WARN: xHC returned failed port status event\n");

        port_id = GET_PORT_ID(le32_to_cpu(event->generic.field[0]));
        max_ports = HCS_MAX_PORTS(xhci->hcs_params1);

        if ((port_id <= 0) || (port_id > max_ports)) {
                xhci_warn(xhci, "Port change event with invalid port ID %d\n",
                          port_id);
                return;
        }

        port = &xhci->hw_ports[port_id - 1];
        if (!port || !port->rhub || port->hcd_portnum == DUPLICATE_ENTRY) {
                xhci_warn(xhci, "Port change event, no port for port ID %u\n",
                          port_id);
                bogus_port_status = true;
                goto cleanup;
        }

        /* We might get interrupts after shared_hcd is removed */
        if (port->rhub == &xhci->usb3_rhub && xhci->shared_hcd == NULL) {
                xhci_dbg(xhci, "ignore port event for removed USB3 hcd\n");
                bogus_port_status = true;
                goto cleanup;
        }

        hcd = port->rhub->hcd;
        bus_state = &port->rhub->bus_state;
        hcd_portnum = port->hcd_portnum;
        portsc = readl(port->addr);

        xhci_dbg(xhci, "Port change event, %d-%d, id %d, portsc: 0x%x\n",
                 hcd->self.busnum, hcd_portnum + 1, port_id, portsc);

        trace_xhci_handle_port_status(port, portsc);

        if (hcd->state == HC_STATE_SUSPENDED) {
                xhci_dbg(xhci, "resume root hub\n");
                usb_hcd_resume_root_hub(hcd);
        }

        if (hcd->speed >= HCD_USB3 &&
            (portsc & PORT_PLS_MASK) == XDEV_INACTIVE) {
                if (port->slot_id && xhci->devs[port->slot_id])
                        xhci->devs[port->slot_id]->flags |= VDEV_PORT_ERROR;
        }

        if ((portsc & PORT_PLC) && (portsc & PORT_PLS_MASK) == XDEV_RESUME) {
                xhci_dbg(xhci, "port resume event for port %d\n", port_id);

                cmd_reg = readl(&xhci->op_regs->command);
                if (!(cmd_reg & CMD_RUN)) {
                        xhci_warn(xhci, "xHC is not running.\n");
                        goto cleanup;
                }

                if (DEV_SUPERSPEED_ANY(portsc)) {
                        xhci_dbg(xhci, "remote wake SS port %d\n", port_id);
                        /* Set a flag to say the port signaled remote wakeup,
                         * so we can tell the difference between the end of
                         * device and host initiated resume.
                         */
                        bus_state->port_remote_wakeup |= 1 << hcd_portnum;
                        xhci_test_and_clear_bit(xhci, port, PORT_PLC);
                        usb_hcd_start_port_resume(&hcd->self, hcd_portnum);
                        xhci_set_link_state(xhci, port, XDEV_U0);
                        /* Need to wait until the next link state change
                         * indicates the device is actually in U0.
                         */
                        bogus_port_status = true;
                        goto cleanup;
                } else if (!test_bit(hcd_portnum, &bus_state->resuming_ports)) {
                        xhci_dbg(xhci, "resume HS port %d\n", port_id);
                        port->resume_timestamp = jiffies +
                                msecs_to_jiffies(USB_RESUME_TIMEOUT);
                        set_bit(hcd_portnum, &bus_state->resuming_ports);
                        /* Do the rest in GetPortStatus after resume time delay.
                         * Avoid polling roothub status before that so that a
                         * usb device auto-resume latency around ~40ms.
                         */
                        set_bit(HCD_FLAG_POLL_RH, &hcd->flags);
                        mod_timer(&hcd->rh_timer,
                                  port->resume_timestamp);
                        usb_hcd_start_port_resume(&hcd->self, hcd_portnum);
                        bogus_port_status = true;
                }
        }

        if ((portsc & PORT_PLC) &&
            DEV_SUPERSPEED_ANY(portsc) &&
            ((portsc & PORT_PLS_MASK) == XDEV_U0 ||
             (portsc & PORT_PLS_MASK) == XDEV_U1 ||
             (portsc & PORT_PLS_MASK) == XDEV_U2)) {
                xhci_dbg(xhci, "resume SS port %d finished\n", port_id);
                complete(&port->u3exit_done);
                /* We've just brought the device into U0/1/2 through either the
                 * Resume state after a device remote wakeup, or through the
                 * U3Exit state after a host-initiated resume.  If it's a device
                 * initiated remote wake, don't pass up the link state change,
                 * so the roothub behavior is consistent with external
                 * USB 3.0 hub behavior.
                 */
                if (port->slot_id && xhci->devs[port->slot_id])
                        xhci_ring_device(xhci, port->slot_id);
                if (bus_state->port_remote_wakeup & (1 << hcd_portnum)) {
                        xhci_test_and_clear_bit(xhci, port, PORT_PLC);
                        usb_wakeup_notification(hcd->self.root_hub,
                                        hcd_portnum + 1);
                        bogus_port_status = true;
                        goto cleanup;
                }
        }

        /*
         * Check to see if xhci-hub.c is waiting on RExit to U0 transition (or
         * RExit to a disconnect state).  If so, let the driver know it's
         * out of the RExit state.
         */
        if (hcd->speed < HCD_USB3 && port->rexit_active) {
                complete(&port->rexit_done);
                port->rexit_active = false;
                bogus_port_status = true;
                goto cleanup;
        }

        if (hcd->speed < HCD_USB3) {
                xhci_test_and_clear_bit(xhci, port, PORT_PLC);
                if ((xhci->quirks & XHCI_RESET_PLL_ON_DISCONNECT) &&
                    (portsc & PORT_CSC) && !(portsc & PORT_CONNECT))
                        xhci_cavium_reset_phy_quirk(xhci);
        }

cleanup:

        /* Don't make the USB core poll the roothub if we got a bad port status
         * change event.  Besides, at that point we can't tell which roothub
         * (USB 2.0 or USB 3.0) to kick.
         */
        if (bogus_port_status)
                return;

        /*
         * xHCI port-status-change events occur when the "or" of all the
         * status-change bits in the portsc register changes from 0 to 1.
         * New status changes won't cause an event if any other change
         * bits are still set.  When an event occurs, switch over to
         * polling to avoid losing status changes.
         */
        xhci_dbg(xhci, "%s: starting usb%d port polling.\n",
                 __func__, hcd->self.busnum);
        set_bit(HCD_FLAG_POLL_RH, &hcd->flags);
        spin_unlock(&xhci->lock);
        /* Pass this up to the core */
        usb_hcd_poll_rh_status(hcd);
        spin_lock(&xhci->lock);
}

/*
 * This TD is defined by the TRBs starting at start_trb in start_seg and ending
 * at end_trb, which may be in another segment.  If the suspect DMA address is a
 * TRB in this TD, this function returns that TRB's segment.  Otherwise it
 * returns 0.
 */
struct xhci_segment *trb_in_td(struct xhci_hcd *xhci,
                struct xhci_segment *start_seg,
                union xhci_trb  *start_trb,
                union xhci_trb  *end_trb,
                dma_addr_t      suspect_dma,
                bool            debug)
{
        dma_addr_t start_dma;
        dma_addr_t end_seg_dma;
        dma_addr_t end_trb_dma;
        struct xhci_segment *cur_seg;

        start_dma = xhci_trb_virt_to_dma(start_seg, start_trb);
        cur_seg = start_seg;

        do {
                if (start_dma == 0)
                        return NULL;
                /* We may get an event for a Link TRB in the middle of a TD */
                end_seg_dma = xhci_trb_virt_to_dma(cur_seg,
                                &cur_seg->trbs[TRBS_PER_SEGMENT - 1]);
                /* If the end TRB isn't in this segment, this is set to 0 */
                end_trb_dma = xhci_trb_virt_to_dma(cur_seg, end_trb);

                if (debug)
                        xhci_warn(xhci,
                                "Looking for event-dma %016llx trb-start %016llx trb-end %016llx seg-start %016llx seg-end %016llx\n",
                                (unsigned long long)suspect_dma,
                                (unsigned long long)start_dma,
                                (unsigned long long)end_trb_dma,
                                (unsigned long long)cur_seg->dma,
                                (unsigned long long)end_seg_dma);

                if (end_trb_dma > 0) {
                        /* The end TRB is in this segment, so suspect should be here */
                        if (start_dma <= end_trb_dma) {
                                if (suspect_dma >= start_dma && suspect_dma <= end_trb_dma)
                                        return cur_seg;
                        } else {
                                /* Case for one segment with
                                 * a TD wrapped around to the top
                                 */
                                if ((suspect_dma >= start_dma &&
                                                        suspect_dma <= end_seg_dma) ||
                                                (suspect_dma >= cur_seg->dma &&
                                                 suspect_dma <= end_trb_dma))
                                        return cur_seg;
                        }
                        return NULL;
                } else {
                        /* Might still be somewhere in this segment */
                        if (suspect_dma >= start_dma && suspect_dma <= end_seg_dma)
                                return cur_seg;
                }
                cur_seg = cur_seg->next;
                start_dma = xhci_trb_virt_to_dma(cur_seg, &cur_seg->trbs[0]);
        } while (cur_seg != start_seg);

        return NULL;
}

static void xhci_clear_hub_tt_buffer(struct xhci_hcd *xhci, struct xhci_td *td,
                struct xhci_virt_ep *ep)
{
        /*
         * As part of low/full-speed endpoint-halt processing
         * we must clear the TT buffer (USB 2.0 specification 11.17.5).
         */
        if (td->urb->dev->tt && !usb_pipeint(td->urb->pipe) &&
            (td->urb->dev->tt->hub != xhci_to_hcd(xhci)->self.root_hub) &&
            !(ep->ep_state & EP_CLEARING_TT)) {
                ep->ep_state |= EP_CLEARING_TT;
                td->urb->ep->hcpriv = td->urb->dev;
                if (usb_hub_clear_tt_buffer(td->urb))
                        ep->ep_state &= ~EP_CLEARING_TT;
        }
}

/* Check if an error has halted the endpoint ring.  The class driver will
 * cleanup the halt for a non-default control endpoint if we indicate a stall.
 * However, a babble and other errors also halt the endpoint ring, and the class
 * driver won't clear the halt in that case, so we need to issue a Set Transfer
 * Ring Dequeue Pointer command manually.
 */
static int xhci_requires_manual_halt_cleanup(struct xhci_hcd *xhci,
                struct xhci_ep_ctx *ep_ctx,
                unsigned int trb_comp_code)
{
        /* TRB completion codes that may require a manual halt cleanup */
        if (trb_comp_code == COMP_USB_TRANSACTION_ERROR ||
                        trb_comp_code == COMP_BABBLE_DETECTED_ERROR ||
                        trb_comp_code == COMP_SPLIT_TRANSACTION_ERROR)
                /* The 0.95 spec says a babbling control endpoint
                 * is not halted. The 0.96 spec says it is.  Some HW
                 * claims to be 0.95 compliant, but it halts the control
                 * endpoint anyway.  Check if a babble halted the
                 * endpoint.
                 */
                if (GET_EP_CTX_STATE(ep_ctx) == EP_STATE_HALTED)
                        return 1;

        return 0;
}

int xhci_is_vendor_info_code(struct xhci_hcd *xhci, unsigned int trb_comp_code)
{
        if (trb_comp_code >= 224 && trb_comp_code <= 255) {
                /* Vendor defined "informational" completion code,
                 * treat as not-an-error.
                 */
                xhci_dbg(xhci, "Vendor defined info completion code %u\n",
                                trb_comp_code);
                xhci_dbg(xhci, "Treating code as success.\n");
                return 1;
        }
        return 0;
}

static int finish_td(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
                     struct xhci_ring *ep_ring, struct xhci_td *td,
                     u32 trb_comp_code)
{
        struct xhci_ep_ctx *ep_ctx;

        ep_ctx = xhci_get_ep_ctx(xhci, ep->vdev->out_ctx, ep->ep_index);

        switch (trb_comp_code) {
        case COMP_STOPPED_LENGTH_INVALID:
        case COMP_STOPPED_SHORT_PACKET:
        case COMP_STOPPED:
                /*
                 * The "Stop Endpoint" completion will take care of any
                 * stopped TDs. A stopped TD may be restarted, so don't update
                 * the ring dequeue pointer or take this TD off any lists yet.
                 */
                return 0;
        case COMP_USB_TRANSACTION_ERROR:
        case COMP_BABBLE_DETECTED_ERROR:
        case COMP_SPLIT_TRANSACTION_ERROR:
                /*
                 * If endpoint context state is not halted we might be
                 * racing with a reset endpoint command issued by a unsuccessful
                 * stop endpoint completion (context error). In that case the
                 * td should be on the cancelled list, and EP_HALTED flag set.
                 *
                 * Or then it's not halted due to the 0.95 spec stating that a
                 * babbling control endpoint should not halt. The 0.96 spec
                 * again says it should.  Some HW claims to be 0.95 compliant,
                 * but it halts the control endpoint anyway.
                 */
                if (GET_EP_CTX_STATE(ep_ctx) != EP_STATE_HALTED) {
                        /*
                         * If EP_HALTED is set and TD is on the cancelled list
                         * the TD and dequeue pointer will be handled by reset
                         * ep command completion
                         */
                        if ((ep->ep_state & EP_HALTED) &&
                            !list_empty(&td->cancelled_td_list)) {
                                xhci_dbg(xhci, "Already resolving halted ep for 0x%llx\n",
                                         (unsigned long long)xhci_trb_virt_to_dma(
                                                 td->start_seg, td->first_trb));
                                return 0;
                        }
                        /* endpoint not halted, don't reset it */
                        break;
                }
                /* Almost same procedure as for STALL_ERROR below */
                xhci_clear_hub_tt_buffer(xhci, td, ep);
                xhci_handle_halted_endpoint(xhci, ep, td, EP_HARD_RESET);
                return 0;
        case COMP_STALL_ERROR:
                /*
                 * xhci internal endpoint state will go to a "halt" state for
                 * any stall, including default control pipe protocol stall.
                 * To clear the host side halt we need to issue a reset endpoint
                 * command, followed by a set dequeue command to move past the
                 * TD.
                 * Class drivers clear the device side halt from a functional
                 * stall later. Hub TT buffer should only be cleared for FS/LS
                 * devices behind HS hubs for functional stalls.
                 */
                if (ep->ep_index != 0)
                        xhci_clear_hub_tt_buffer(xhci, td, ep);

                xhci_handle_halted_endpoint(xhci, ep, td, EP_HARD_RESET);

                return 0; /* xhci_handle_halted_endpoint marked td cancelled */
        default:
                break;
        }

        /* Update ring dequeue pointer */
        ep_ring->dequeue = td->last_trb;
        ep_ring->deq_seg = td->last_trb_seg;
        inc_deq(xhci, ep_ring);

        return xhci_td_cleanup(xhci, td, ep_ring, td->status);
}

/* sum trb lengths from ring dequeue up to stop_trb, _excluding_ stop_trb */
static int sum_trb_lengths(struct xhci_hcd *xhci, struct xhci_ring *ring,
                           union xhci_trb *stop_trb)
{
        u32 sum;
        union xhci_trb *trb = ring->dequeue;
        struct xhci_segment *seg = ring->deq_seg;

        for (sum = 0; trb != stop_trb; next_trb(xhci, ring, &seg, &trb)) {
                if (!trb_is_noop(trb) && !trb_is_link(trb))
                        sum += TRB_LEN(le32_to_cpu(trb->generic.field[2]));
        }
        return sum;
}

/*
 * Process control tds, update urb status and actual_length.
 */
static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
                struct xhci_ring *ep_ring,  struct xhci_td *td,
                           union xhci_trb *ep_trb, struct xhci_transfer_event *event)
{
        struct xhci_ep_ctx *ep_ctx;
        u32 trb_comp_code;
        u32 remaining, requested;
        u32 trb_type;

        trb_type = TRB_FIELD_TO_TYPE(le32_to_cpu(ep_trb->generic.field[3]));
        ep_ctx = xhci_get_ep_ctx(xhci, ep->vdev->out_ctx, ep->ep_index);
        trb_comp_code = GET_COMP_CODE(le32_to_cpu(event->transfer_len));
        requested = td->urb->transfer_buffer_length;
        remaining = EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));

        switch (trb_comp_code) {
        case COMP_SUCCESS:
                if (trb_type != TRB_STATUS) {
                        xhci_warn(xhci, "WARN: Success on ctrl %s TRB without IOC set?\n",
                                  (trb_type == TRB_DATA) ? "data" : "setup");
                        td->status = -ESHUTDOWN;
                        break;
                }
                td->status = 0;
                break;
        case COMP_SHORT_PACKET:
                td->status = 0;
                break;
        case COMP_STOPPED_SHORT_PACKET:
                if (trb_type == TRB_DATA || trb_type == TRB_NORMAL)
                        td->urb->actual_length = remaining;
                else
                        xhci_warn(xhci, "WARN: Stopped Short Packet on ctrl setup or status TRB\n");
                goto finish_td;
        case COMP_STOPPED:
                switch (trb_type) {
                case TRB_SETUP:
                        td->urb->actual_length = 0;
                        goto finish_td;
                case TRB_DATA:
                case TRB_NORMAL:
                        td->urb->actual_length = requested - remaining;
                        goto finish_td;
                case TRB_STATUS:
                        td->urb->actual_length = requested;
                        goto finish_td;
                default:
                        xhci_warn(xhci, "WARN: unexpected TRB Type %d\n",
                                  trb_type);
                        goto finish_td;
                }
        case COMP_STOPPED_LENGTH_INVALID:
                goto finish_td;
        default:
                if (!xhci_requires_manual_halt_cleanup(xhci,
                                                       ep_ctx, trb_comp_code))
                        break;
                xhci_dbg(xhci, "TRB error %u, halted endpoint index = %u\n",
                         trb_comp_code, ep->ep_index);
                fallthrough;
        case COMP_STALL_ERROR:
                /* Did we transfer part of the data (middle) phase? */
                if (trb_type == TRB_DATA || trb_type == TRB_NORMAL)
                        td->urb->actual_length = requested - remaining;
                else if (!td->urb_length_set)
                        td->urb->actual_length = 0;
                goto finish_td;
        }

        /* stopped at setup stage, no data transferred */
        if (trb_type == TRB_SETUP)
                goto finish_td;

        /*
         * if on data stage then update the actual_length of the URB and flag it
         * as set, so it won't be overwritten in the event for the last TRB.
         */
        if (trb_type == TRB_DATA ||
                trb_type == TRB_NORMAL) {
                td->urb_length_set = true;
                td->urb->actual_length = requested - remaining;
                xhci_dbg(xhci, "Waiting for status stage event\n");
                return 0;
        }

        /* at status stage */
        if (!td->urb_length_set)
                td->urb->actual_length = requested;

finish_td:
        return finish_td(xhci, ep, ep_ring, td, trb_comp_code);
}

/*
 * Process isochronous tds, update urb packet status and actual_length.
 */
static int process_isoc_td(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
                struct xhci_ring *ep_ring, struct xhci_td *td,
                union xhci_trb *ep_trb, struct xhci_transfer_event *event)
{
        struct urb_priv *urb_priv;
        int idx;
        struct usb_iso_packet_descriptor *frame;
        u32 trb_comp_code;
        bool sum_trbs_for_length = false;
        u32 remaining, requested, ep_trb_len;
        int short_framestatus;

        trb_comp_code = GET_COMP_CODE(le32_to_cpu(event->transfer_len));
        urb_priv = td->urb->hcpriv;
        idx = urb_priv->num_tds_done;
        frame = &td->urb->iso_frame_desc[idx];
        requested = frame->length;
        remaining = EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
        ep_trb_len = TRB_LEN(le32_to_cpu(ep_trb->generic.field[2]));
        short_framestatus = td->urb->transfer_flags & URB_SHORT_NOT_OK ?
                -EREMOTEIO : 0;

        /* handle completion code */
        switch (trb_comp_code) {
        case COMP_SUCCESS:
                /* Don't overwrite status if TD had an error, see xHCI 4.9.1 */
                if (td->error_mid_td)
                        break;
                if (remaining) {
                        frame->status = short_framestatus;
                        if (xhci->quirks & XHCI_TRUST_TX_LENGTH)
                                sum_trbs_for_length = true;
                        break;
                }
                frame->status = 0;
                break;
        case COMP_SHORT_PACKET:
                frame->status = short_framestatus;
                sum_trbs_for_length = true;
                break;
        case COMP_BANDWIDTH_OVERRUN_ERROR:
                frame->status = -ECOMM;
                break;
        case COMP_BABBLE_DETECTED_ERROR:
                sum_trbs_for_length = true;
                fallthrough;
        case COMP_ISOCH_BUFFER_OVERRUN:
                frame->status = -EOVERFLOW;
                if (ep_trb != td->last_trb)
                        td->error_mid_td = true;
                break;
        case COMP_INCOMPATIBLE_DEVICE_ERROR:
        case COMP_STALL_ERROR:
                frame->status = -EPROTO;
                break;
        case COMP_USB_TRANSACTION_ERROR:
                frame->status = -EPROTO;
                sum_trbs_for_length = true;
                if (ep_trb != td->last_trb)
                        td->error_mid_td = true;
                break;
        case COMP_STOPPED:
                sum_trbs_for_length = true;
                break;
        case COMP_STOPPED_SHORT_PACKET:
                /* field normally containing residue now contains tranferred */
                frame->status = short_framestatus;
                requested = remaining;
                break;
        case COMP_STOPPED_LENGTH_INVALID:
                requested = 0;
                remaining = 0;
                break;
        default:
                sum_trbs_for_length = true;
                frame->status = -1;
                break;
        }

        if (td->urb_length_set)
                goto finish_td;

        if (sum_trbs_for_length)
                frame->actual_length = sum_trb_lengths(xhci, ep->ring, ep_trb) +
                        ep_trb_len - remaining;
        else
                frame->actual_length = requested;

        td->urb->actual_length += frame->actual_length;

finish_td:
        /* Don't give back TD yet if we encountered an error mid TD */
        if (td->error_mid_td && ep_trb != td->last_trb) {
                xhci_dbg(xhci, "Error mid isoc TD, wait for final completion event\n");
                td->urb_length_set = true;
                return 0;
        }

        return finish_td(xhci, ep, ep_ring, td, trb_comp_code);
}

static int skip_isoc_td(struct xhci_hcd *xhci, struct xhci_td *td,
                        struct xhci_virt_ep *ep, int status)
{
        struct urb_priv *urb_priv;
        struct usb_iso_packet_descriptor *frame;
        int idx;

        urb_priv = td->urb->hcpriv;
        idx = urb_priv->num_tds_done;
        frame = &td->urb->iso_frame_desc[idx];

        /* The transfer is partly done. */
        frame->status = -EXDEV;

        /* calc actual length */
        frame->actual_length = 0;

        /* Update ring dequeue pointer */
        ep->ring->dequeue = td->last_trb;
        ep->ring->deq_seg = td->last_trb_seg;
        inc_deq(xhci, ep->ring);

        return xhci_td_cleanup(xhci, td, ep->ring, status);
}

/*
 * Process bulk and interrupt tds, update urb status and actual_length.
 */
static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
                struct xhci_ring *ep_ring, struct xhci_td *td,
                union xhci_trb *ep_trb, struct xhci_transfer_event *event)
{
        struct xhci_slot_ctx *slot_ctx;
        u32 trb_comp_code;
        u32 remaining, requested, ep_trb_len;

        slot_ctx = xhci_get_slot_ctx(xhci, ep->vdev->out_ctx);
        trb_comp_code = GET_COMP_CODE(le32_to_cpu(event->transfer_len));
        remaining = EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
        ep_trb_len = TRB_LEN(le32_to_cpu(ep_trb->generic.field[2]));
        requested = td->urb->transfer_buffer_length;

        switch (trb_comp_code) {
        case COMP_SUCCESS:
                ep->err_count = 0;
                /* handle success with untransferred data as short packet */
                if (ep_trb != td->last_trb || remaining) {
                        xhci_warn(xhci, "WARN Successful completion on short TX\n");
                        xhci_dbg(xhci, "ep %#x - asked for %d bytes, %d bytes untransferred\n",
                                 td->urb->ep->desc.bEndpointAddress,
                                 requested, remaining);
                }
                td->status = 0;
                break;
        case COMP_SHORT_PACKET:
                xhci_dbg(xhci, "ep %#x - asked for %d bytes, %d bytes untransferred\n",
                         td->urb->ep->desc.bEndpointAddress,
                         requested, remaining);
                td->status = 0;
                break;
        case COMP_STOPPED_SHORT_PACKET:
                td->urb->actual_length = remaining;
                goto finish_td;
        case COMP_STOPPED_LENGTH_INVALID:
                /* stopped on ep trb with invalid length, exclude it */
                ep_trb_len      = 0;
                remaining       = 0;
                break;
        case COMP_USB_TRANSACTION_ERROR:
                if (xhci->quirks & XHCI_NO_SOFT_RETRY ||
                    (ep->err_count++ > MAX_SOFT_RETRY) ||
                    le32_to_cpu(slot_ctx->tt_info) & TT_SLOT)
                        break;

                td->status = 0;

                xhci_handle_halted_endpoint(xhci, ep, td, EP_SOFT_RESET);
                return 0;
        default:
                /* do nothing */
                break;
        }

        if (ep_trb == td->last_trb)
                td->urb->actual_length = requested - remaining;
        else
                td->urb->actual_length =
                        sum_trb_lengths(xhci, ep_ring, ep_trb) +
                        ep_trb_len - remaining;
finish_td:
        if (remaining > requested) {
                xhci_warn(xhci, "bad transfer trb length %d in event trb\n",
                          remaining);
                td->urb->actual_length = 0;
        }

        return finish_td(xhci, ep, ep_ring, td, trb_comp_code);
}

/*
 * If this function returns an error condition, it means it got a Transfer
 * event with a corrupted Slot ID, Endpoint ID, or TRB DMA address.
 * At this point, the host controller is probably hosed and should be reset.
 */
static int handle_tx_event(struct xhci_hcd *xhci,
                           struct xhci_interrupter *ir,
                           struct xhci_transfer_event *event)
{
        struct xhci_virt_ep *ep;
        struct xhci_ring *ep_ring;
        unsigned int slot_id;
        int ep_index;
        struct xhci_td *td = NULL;
        dma_addr_t ep_trb_dma;
        struct xhci_segment *ep_seg;
        union xhci_trb *ep_trb;
        int status = -EINPROGRESS;
        struct xhci_ep_ctx *ep_ctx;
        u32 trb_comp_code;
        int td_num = 0;
        bool handling_skipped_tds = false;

        slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
        ep_index = TRB_TO_EP_ID(le32_to_cpu(event->flags)) - 1;
        trb_comp_code = GET_COMP_CODE(le32_to_cpu(event->transfer_len));
        ep_trb_dma = le64_to_cpu(event->buffer);

        ep = xhci_get_virt_ep(xhci, slot_id, ep_index);
        if (!ep) {
                xhci_err(xhci, "ERROR Invalid Transfer event\n");
                goto err_out;
        }

        ep_ring = xhci_dma_to_transfer_ring(ep, ep_trb_dma);
        ep_ctx = xhci_get_ep_ctx(xhci, ep->vdev->out_ctx, ep_index);

        if (GET_EP_CTX_STATE(ep_ctx) == EP_STATE_DISABLED) {
                xhci_err(xhci,
                         "ERROR Transfer event for disabled endpoint slot %u ep %u\n",
                          slot_id, ep_index);
                goto err_out;
        }

        /* Some transfer events don't always point to a trb, see xhci 4.17.4 */
        if (!ep_ring) {
                switch (trb_comp_code) {
                case COMP_STALL_ERROR:
                case COMP_USB_TRANSACTION_ERROR:
                case COMP_INVALID_STREAM_TYPE_ERROR:
                case COMP_INVALID_STREAM_ID_ERROR:
                        xhci_dbg(xhci, "Stream transaction error ep %u no id\n",
                                 ep_index);
                        if (ep->err_count++ > MAX_SOFT_RETRY)
                                xhci_handle_halted_endpoint(xhci, ep, NULL,
                                                            EP_HARD_RESET);
                        else
                                xhci_handle_halted_endpoint(xhci, ep, NULL,
                                                            EP_SOFT_RESET);
                        goto cleanup;
                case COMP_RING_UNDERRUN:
                case COMP_RING_OVERRUN:
                case COMP_STOPPED_LENGTH_INVALID:
                        goto cleanup;
                default:
                        xhci_err(xhci, "ERROR Transfer event for unknown stream ring slot %u ep %u\n",
                                 slot_id, ep_index);
                        goto err_out;
                }
        }

        /* Count current td numbers if ep->skip is set */
        if (ep->skip)
                td_num += list_count_nodes(&ep_ring->td_list);

        /* Look for common error cases */
        switch (trb_comp_code) {
        /* Skip codes that require special handling depending on
         * transfer type
         */
        case COMP_SUCCESS:
                if (EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)) == 0)
                        break;
                if (xhci->quirks & XHCI_TRUST_TX_LENGTH ||
                    ep_ring->last_td_was_short)
                        trb_comp_code = COMP_SHORT_PACKET;
                else
                        xhci_warn_ratelimited(xhci,
                                              "WARN Successful completion on short TX for slot %u ep %u: needs XHCI_TRUST_TX_LENGTH quirk?\n",
                                              slot_id, ep_index);
                break;
        case COMP_SHORT_PACKET:
                break;
        /* Completion codes for endpoint stopped state */
        case COMP_STOPPED:
                xhci_dbg(xhci, "Stopped on Transfer TRB for slot %u ep %u\n",
                         slot_id, ep_index);
                break;
        case COMP_STOPPED_LENGTH_INVALID:
                xhci_dbg(xhci,
                         "Stopped on No-op or Link TRB for slot %u ep %u\n",
                         slot_id, ep_index);
                break;
        case COMP_STOPPED_SHORT_PACKET:
                xhci_dbg(xhci,
                         "Stopped with short packet transfer detected for slot %u ep %u\n",
                         slot_id, ep_index);
                break;
        /* Completion codes for endpoint halted state */
        case COMP_STALL_ERROR:
                xhci_dbg(xhci, "Stalled endpoint for slot %u ep %u\n", slot_id,
                         ep_index);
                status = -EPIPE;
                break;
        case COMP_SPLIT_TRANSACTION_ERROR:
                xhci_dbg(xhci, "Split transaction error for slot %u ep %u\n",
                         slot_id, ep_index);
                status = -EPROTO;
                break;
        case COMP_USB_TRANSACTION_ERROR:
                xhci_dbg(xhci, "Transfer error for slot %u ep %u on endpoint\n",
                         slot_id, ep_index);
                status = -EPROTO;
                break;
        case COMP_BABBLE_DETECTED_ERROR:
                xhci_dbg(xhci, "Babble error for slot %u ep %u on endpoint\n",
                         slot_id, ep_index);
                status = -EOVERFLOW;
                break;
        /* Completion codes for endpoint error state */
        case COMP_TRB_ERROR:
                xhci_warn(xhci,
                          "WARN: TRB error for slot %u ep %u on endpoint\n",
                          slot_id, ep_index);
                status = -EILSEQ;
                break;
        /* completion codes not indicating endpoint state change */
        case COMP_DATA_BUFFER_ERROR:
                xhci_warn(xhci,
                          "WARN: HC couldn't access mem fast enough for slot %u ep %u\n",
                          slot_id, ep_index);
                status = -ENOSR;
                break;
        case COMP_BANDWIDTH_OVERRUN_ERROR:
                xhci_warn(xhci,
                          "WARN: bandwidth overrun event for slot %u ep %u on endpoint\n",
                          slot_id, ep_index);
                break;
        case COMP_ISOCH_BUFFER_OVERRUN:
                xhci_warn(xhci,
                          "WARN: buffer overrun event for slot %u ep %u on endpoint",
                          slot_id, ep_index);
                break;
        case COMP_RING_UNDERRUN:
                /*
                 * When the Isoch ring is empty, the xHC will generate
                 * a Ring Overrun Event for IN Isoch endpoint or Ring
                 * Underrun Event for OUT Isoch endpoint.
                 */
                xhci_dbg(xhci, "underrun event on endpoint\n");
                if (!list_empty(&ep_ring->td_list))
                        xhci_dbg(xhci, "Underrun Event for slot %d ep %d "
                                        "still with TDs queued?\n",
                                 TRB_TO_SLOT_ID(le32_to_cpu(event->flags)),
                                 ep_index);
                goto cleanup;
        case COMP_RING_OVERRUN:
                xhci_dbg(xhci, "overrun event on endpoint\n");
                if (!list_empty(&ep_ring->td_list))
                        xhci_dbg(xhci, "Overrun Event for slot %d ep %d "
                                        "still with TDs queued?\n",
                                 TRB_TO_SLOT_ID(le32_to_cpu(event->flags)),
                                 ep_index);
                goto cleanup;
        case COMP_MISSED_SERVICE_ERROR:
                /*
                 * When encounter missed service error, one or more isoc tds
                 * may be missed by xHC.
                 * Set skip flag of the ep_ring; Complete the missed tds as
                 * short transfer when process the ep_ring next time.
                 */
                ep->skip = true;
                xhci_dbg(xhci,
                         "Miss service interval error for slot %u ep %u, set skip flag\n",
                         slot_id, ep_index);
                goto cleanup;
        case COMP_NO_PING_RESPONSE_ERROR:
                ep->skip = true;
                xhci_dbg(xhci,
                         "No Ping response error for slot %u ep %u, Skip one Isoc TD\n",
                         slot_id, ep_index);
                goto cleanup;

        case COMP_INCOMPATIBLE_DEVICE_ERROR:
                /* needs disable slot command to recover */
                xhci_warn(xhci,
                          "WARN: detect an incompatible device for slot %u ep %u",
                          slot_id, ep_index);
                status = -EPROTO;
                break;
        default:
                if (xhci_is_vendor_info_code(xhci, trb_comp_code)) {
                        status = 0;
                        break;
                }
                xhci_warn(xhci,
                          "ERROR Unknown event condition %u for slot %u ep %u , HC probably busted\n",
                          trb_comp_code, slot_id, ep_index);
                goto cleanup;
        }

        do {
                /* This TRB should be in the TD at the head of this ring's
                 * TD list.
                 */
                if (list_empty(&ep_ring->td_list)) {
                        /*
                         * Don't print wanings if it's due to a stopped endpoint
                         * generating an extra completion event if the device
                         * was suspended. Or, a event for the last TRB of a
                         * short TD we already got a short event for.
                         * The short TD is already removed from the TD list.
                         */

                        if (!(trb_comp_code == COMP_STOPPED ||
                              trb_comp_code == COMP_STOPPED_LENGTH_INVALID ||
                              ep_ring->last_td_was_short)) {
                                xhci_warn(xhci, "WARN Event TRB for slot %d ep %d with no TDs queued?\n",
                                                TRB_TO_SLOT_ID(le32_to_cpu(event->flags)),
                                                ep_index);
                        }
                        if (ep->skip) {
                                ep->skip = false;
                                xhci_dbg(xhci, "td_list is empty while skip flag set. Clear skip flag for slot %u ep %u.\n",
                                         slot_id, ep_index);
                        }
                        if (trb_comp_code == COMP_STALL_ERROR ||
                            xhci_requires_manual_halt_cleanup(xhci, ep_ctx,
                                                              trb_comp_code)) {
                                xhci_handle_halted_endpoint(xhci, ep, NULL,
                                                            EP_HARD_RESET);
                        }
                        goto cleanup;
                }

                /* We've skipped all the TDs on the ep ring when ep->skip set */
                if (ep->skip && td_num == 0) {
                        ep->skip = false;
                        xhci_dbg(xhci, "All tds on the ep_ring skipped. Clear skip flag for slot %u ep %u.\n",
                                 slot_id, ep_index);
                        goto cleanup;
                }

                td = list_first_entry(&ep_ring->td_list, struct xhci_td,
                                      td_list);
                if (ep->skip)
                        td_num--;

                /* Is this a TRB in the currently executing TD? */
                ep_seg = trb_in_td(xhci, td->start_seg, td->first_trb,
                                td->last_trb, ep_trb_dma, false);

                /*
                 * Skip the Force Stopped Event. The event_trb(event_dma) of FSE
                 * is not in the current TD pointed by ep_ring->dequeue because
                 * that the hardware dequeue pointer still at the previous TRB
                 * of the current TD. The previous TRB maybe a Link TD or the
                 * last TRB of the previous TD. The command completion handle
                 * will take care the rest.
                 */
                if (!ep_seg && (trb_comp_code == COMP_STOPPED ||
                           trb_comp_code == COMP_STOPPED_LENGTH_INVALID)) {
                        goto cleanup;
                }

                if (!ep_seg) {

                        if (ep->skip && usb_endpoint_xfer_isoc(&td->urb->ep->desc)) {
                                skip_isoc_td(xhci, td, ep, status);
                                goto cleanup;
                        }

                        /*
                         * Some hosts give a spurious success event after a short
                         * transfer. Ignore it.
                         */
                        if ((xhci->quirks & XHCI_SPURIOUS_SUCCESS) &&
                            ep_ring->last_td_was_short) {
                                ep_ring->last_td_was_short = false;
                                goto cleanup;
                        }

                        /*
                         * xhci 4.10.2 states isoc endpoints should continue
                         * processing the next TD if there was an error mid TD.
                         * So host like NEC don't generate an event for the last
                         * isoc TRB even if the IOC flag is set.
                         * xhci 4.9.1 states that if there are errors in mult-TRB
                         * TDs xHC should generate an error for that TRB, and if xHC
                         * proceeds to the next TD it should genete an event for
                         * any TRB with IOC flag on the way. Other host follow this.
                         * So this event might be for the next TD.
                         */
                        if (td->error_mid_td &&
                            !list_is_last(&td->td_list, &ep_ring->td_list)) {
                                struct xhci_td *td_next = list_next_entry(td, td_list);

                                ep_seg = trb_in_td(xhci, td_next->start_seg, td_next->first_trb,
                                                   td_next->last_trb, ep_trb_dma, false);
                                if (ep_seg) {
                                        /* give back previous TD, start handling new */
                                        xhci_dbg(xhci, "Missing TD completion event after mid TD error\n");
                                        ep_ring->dequeue = td->last_trb;
                                        ep_ring->deq_seg = td->last_trb_seg;
                                        inc_deq(xhci, ep_ring);
                                        xhci_td_cleanup(xhci, td, ep_ring, td->status);
                                        td = td_next;
                                }
                        }

                        if (!ep_seg) {
                                /* HC is busted, give up! */
                                xhci_err(xhci,
                                        "ERROR Transfer event TRB DMA ptr not "
                                        "part of current TD ep_index %d "
                                        "comp_code %u\n", ep_index,
                                        trb_comp_code);
                                trb_in_td(xhci, td->start_seg, td->first_trb,
                                          td->last_trb, ep_trb_dma, true);
                                return -ESHUTDOWN;
                        }
                }
                if (trb_comp_code == COMP_SHORT_PACKET)
                        ep_ring->last_td_was_short = true;
                else
                        ep_ring->last_td_was_short = false;

                if (ep->skip) {
                        xhci_dbg(xhci,
                                 "Found td. Clear skip flag for slot %u ep %u.\n",
                                 slot_id, ep_index);
                        ep->skip = false;
                }

                ep_trb = &ep_seg->trbs[(ep_trb_dma - ep_seg->dma) /
                                                sizeof(*ep_trb)];

                trace_xhci_handle_transfer(ep_ring,
                                (struct xhci_generic_trb *) ep_trb);

                /*
                 * No-op TRB could trigger interrupts in a case where
                 * a URB was killed and a STALL_ERROR happens right
                 * after the endpoint ring stopped. Reset the halted
                 * endpoint. Otherwise, the endpoint remains stalled
                 * indefinitely.
                 */

                if (trb_is_noop(ep_trb)) {
                        if (trb_comp_code == COMP_STALL_ERROR ||
                            xhci_requires_manual_halt_cleanup(xhci, ep_ctx,
                                                              trb_comp_code))
                                xhci_handle_halted_endpoint(xhci, ep, td,
                                                            EP_HARD_RESET);
                        goto cleanup;
                }

                td->status = status;

                /* update the urb's actual_length and give back to the core */
                if (usb_endpoint_xfer_control(&td->urb->ep->desc))
                        process_ctrl_td(xhci, ep, ep_ring, td, ep_trb, event);
                else if (usb_endpoint_xfer_isoc(&td->urb->ep->desc))
                        process_isoc_td(xhci, ep, ep_ring, td, ep_trb, event);
                else
                        process_bulk_intr_td(xhci, ep, ep_ring, td, ep_trb, event);
cleanup:
                handling_skipped_tds = ep->skip &&
                        trb_comp_code != COMP_MISSED_SERVICE_ERROR &&
                        trb_comp_code != COMP_NO_PING_RESPONSE_ERROR;

        /*
         * If ep->skip is set, it means there are missed tds on the
         * endpoint ring need to take care of.
         * Process them as short transfer until reach the td pointed by
         * the event.
         */
        } while (handling_skipped_tds);

        return 0;

err_out:
        xhci_err(xhci, "@%016llx %08x %08x %08x %08x\n",
                 (unsigned long long) xhci_trb_virt_to_dma(
                         ir->event_ring->deq_seg,
                         ir->event_ring->dequeue),
                 lower_32_bits(le64_to_cpu(event->buffer)),
                 upper_32_bits(le64_to_cpu(event->buffer)),
                 le32_to_cpu(event->transfer_len),
                 le32_to_cpu(event->flags));
        return -ENODEV;
}

/*
 * This function handles one OS-owned event on the event ring. It may drop
 * xhci->lock between event processing (e.g. to pass up port status changes).
 */
static int xhci_handle_event_trb(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
                                 union xhci_trb *event)
{
        u32 trb_type;

        trace_xhci_handle_event(ir->event_ring, &event->generic);

        /*
         * Barrier between reading the TRB_CYCLE (valid) flag before, and any
         * speculative reads of the event's flags/data below.
         */
        rmb();
        trb_type = TRB_FIELD_TO_TYPE(le32_to_cpu(event->event_cmd.flags));
        /* FIXME: Handle more event types. */

        switch (trb_type) {
        case TRB_COMPLETION:
                handle_cmd_completion(xhci, &event->event_cmd);
                break;
        case TRB_PORT_STATUS:
                handle_port_status(xhci, ir, event);
                break;
        case TRB_TRANSFER:
                handle_tx_event(xhci, ir, &event->trans_event);
                break;
        case TRB_DEV_NOTE:
                handle_device_notification(xhci, event);
                break;
        default:
                if (trb_type >= TRB_VENDOR_DEFINED_LOW)
                        handle_vendor_event(xhci, event, trb_type);
                else
                        xhci_warn(xhci, "ERROR unknown event type %d\n", trb_type);
        }
        /* Any of the above functions may drop and re-acquire the lock, so check
         * to make sure a watchdog timer didn't mark the host as non-responsive.
         */
        if (xhci->xhc_state & XHCI_STATE_DYING) {
                xhci_dbg(xhci, "xHCI host dying, returning from event handler.\n");
                return -ENODEV;
        }

        return 0;
}

/*
 * Update Event Ring Dequeue Pointer:
 * - When all events have finished
 * - To avoid "Event Ring Full Error" condition
 */
static void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
                                     struct xhci_interrupter *ir,
                                     bool clear_ehb)
{
        u64 temp_64;
        dma_addr_t deq;

        temp_64 = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
        deq = xhci_trb_virt_to_dma(ir->event_ring->deq_seg,
                                   ir->event_ring->dequeue);
        if (deq == 0)
                xhci_warn(xhci, "WARN something wrong with SW event ring dequeue ptr\n");
        /*
         * Per 4.9.4, Software writes to the ERDP register shall always advance
         * the Event Ring Dequeue Pointer value.
         */
        if ((temp_64 & ERST_PTR_MASK) == (deq & ERST_PTR_MASK) && !clear_ehb)
                return;

        /* Update HC event ring dequeue pointer */
        temp_64 = ir->event_ring->deq_seg->num & ERST_DESI_MASK;
        temp_64 |= deq & ERST_PTR_MASK;

        /* Clear the event handler busy flag (RW1C) */
        if (clear_ehb)
                temp_64 |= ERST_EHB;
        xhci_write_64(xhci, temp_64, &ir->ir_set->erst_dequeue);
}

/* Clear the interrupt pending bit for a specific interrupter. */
static void xhci_clear_interrupt_pending(struct xhci_hcd *xhci,
                                         struct xhci_interrupter *ir)
{
        if (!ir->ip_autoclear) {
                u32 irq_pending;

                irq_pending = readl(&ir->ir_set->irq_pending);
                irq_pending |= IMAN_IP;
                writel(irq_pending, &ir->ir_set->irq_pending);
        }
}

/*
 * Handle all OS-owned events on an interrupter event ring. It may drop
 * and reaquire xhci->lock between event processing.
 */
static int xhci_handle_events(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
{
        int event_loop = 0;
        int err;
        u64 temp;

        xhci_clear_interrupt_pending(xhci, ir);

        /* Event ring hasn't been allocated yet. */
        if (!ir->event_ring || !ir->event_ring->dequeue) {
                xhci_err(xhci, "ERROR interrupter event ring not ready\n");
                return -ENOMEM;
        }

        if (xhci->xhc_state & XHCI_STATE_DYING ||
            xhci->xhc_state & XHCI_STATE_HALTED) {
                xhci_dbg(xhci, "xHCI dying, ignoring interrupt. Shouldn't IRQs be disabled?\n");

                /* Clear the event handler busy flag (RW1C) */
                temp = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
                xhci_write_64(xhci, temp | ERST_EHB, &ir->ir_set->erst_dequeue);
                return -ENODEV;
        }

        /* Process all OS owned event TRBs on this event ring */
        while (unhandled_event_trb(ir->event_ring)) {
                err = xhci_handle_event_trb(xhci, ir, ir->event_ring->dequeue);

                /*
                 * If half a segment of events have been handled in one go then
                 * update ERDP, and force isoc trbs to interrupt more often
                 */
                if (event_loop++ > TRBS_PER_SEGMENT / 2) {
                        xhci_update_erst_dequeue(xhci, ir, false);

                        if (ir->isoc_bei_interval > AVOID_BEI_INTERVAL_MIN)
                                ir->isoc_bei_interval = ir->isoc_bei_interval / 2;

                        event_loop = 0;
                }

                /* Update SW event ring dequeue pointer */
                inc_deq(xhci, ir->event_ring);

                if (err)
                        break;
        }

        xhci_update_erst_dequeue(xhci, ir, true);

        return 0;
}

/*
 * xHCI spec says we can get an interrupt, and if the HC has an error condition,
 * we might get bad data out of the event ring.  Section 4.10.2.7 has a list of
 * indicators of an event TRB error, but we check the status *first* to be safe.
 */
irqreturn_t xhci_irq(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        irqreturn_t ret = IRQ_NONE;
        u32 status;

        spin_lock(&xhci->lock);
        /* Check if the xHC generated the interrupt, or the irq is shared */
        status = readl(&xhci->op_regs->status);
        if (status == ~(u32)0) {
                xhci_hc_died(xhci);
                ret = IRQ_HANDLED;
                goto out;
        }

        if (!(status & STS_EINT))
                goto out;

        if (status & STS_HCE) {
                xhci_warn(xhci, "WARNING: Host Controller Error\n");
                goto out;
        }

        if (status & STS_FATAL) {
                xhci_warn(xhci, "WARNING: Host System Error\n");
                xhci_halt(xhci);
                ret = IRQ_HANDLED;
                goto out;
        }

        /*
         * Clear the op reg interrupt status first,
         * so we can receive interrupts from other MSI-X interrupters.
         * Write 1 to clear the interrupt status.
         */
        status |= STS_EINT;
        writel(status, &xhci->op_regs->status);
        ret = IRQ_HANDLED;

        /* This is the handler of the primary interrupter */
        xhci_handle_events(xhci, xhci->interrupters[0]);
out:
        spin_unlock(&xhci->lock);

        return ret;
}

irqreturn_t xhci_msi_irq(int irq, void *hcd)
{
        return xhci_irq(hcd);
}
EXPORT_SYMBOL_GPL(xhci_msi_irq);

/****           Endpoint Ring Operations        ****/

/*
 * Generic function for queueing a TRB on a ring.
 * The caller must have checked to make sure there's room on the ring.
 *
 * @more_trbs_coming:   Will you enqueue more TRBs before calling
 *                      prepare_transfer()?
 */
static void queue_trb(struct xhci_hcd *xhci, struct xhci_ring *ring,
                bool more_trbs_coming,
                u32 field1, u32 field2, u32 field3, u32 field4)
{
        struct xhci_generic_trb *trb;

        trb = &ring->enqueue->generic;
        trb->field[0] = cpu_to_le32(field1);
        trb->field[1] = cpu_to_le32(field2);
        trb->field[2] = cpu_to_le32(field3);
        /* make sure TRB is fully written before giving it to the controller */
        wmb();
        trb->field[3] = cpu_to_le32(field4);

        trace_xhci_queue_trb(ring, trb);

        inc_enq(xhci, ring, more_trbs_coming);
}

/*
 * Does various checks on the endpoint ring, and makes it ready to queue num_trbs.
 * expand ring if it start to be full.
 */
static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
                u32 ep_state, unsigned int num_trbs, gfp_t mem_flags)
{
        unsigned int link_trb_count = 0;
        unsigned int new_segs = 0;

        /* Make sure the endpoint has been added to xHC schedule */
        switch (ep_state) {
        case EP_STATE_DISABLED:
                /*
                 * USB core changed config/interfaces without notifying us,
                 * or hardware is reporting the wrong state.
                 */
                xhci_warn(xhci, "WARN urb submitted to disabled ep\n");
                return -ENOENT;
        case EP_STATE_ERROR:
                xhci_warn(xhci, "WARN waiting for error on ep to be cleared\n");
                /* FIXME event handling code for error needs to clear it */
                /* XXX not sure if this should be -ENOENT or not */
                return -EINVAL;
        case EP_STATE_HALTED:
                xhci_dbg(xhci, "WARN halted endpoint, queueing URB anyway.\n");
                break;
        case EP_STATE_STOPPED:
        case EP_STATE_RUNNING:
                break;
        default:
                xhci_err(xhci, "ERROR unknown endpoint state for ep\n");
                /*
                 * FIXME issue Configure Endpoint command to try to get the HC
                 * back into a known state.
                 */
                return -EINVAL;
        }

        if (ep_ring != xhci->cmd_ring) {
                new_segs = xhci_ring_expansion_needed(xhci, ep_ring, num_trbs);
        } else if (xhci_num_trbs_free(xhci, ep_ring) <= num_trbs) {
                xhci_err(xhci, "Do not support expand command ring\n");
                return -ENOMEM;
        }

        if (new_segs) {
                xhci_dbg_trace(xhci, trace_xhci_dbg_ring_expansion,
                                "ERROR no room on ep ring, try ring expansion");
                if (xhci_ring_expansion(xhci, ep_ring, new_segs, mem_flags)) {
                        xhci_err(xhci, "Ring expansion failed\n");
                        return -ENOMEM;
                }
        }

        while (trb_is_link(ep_ring->enqueue)) {
                /* If we're not dealing with 0.95 hardware or isoc rings
                 * on AMD 0.96 host, clear the chain bit.
                 */
                if (!xhci_link_trb_quirk(xhci) &&
                    !(ep_ring->type == TYPE_ISOC &&
                      (xhci->quirks & XHCI_AMD_0x96_HOST)))
                        ep_ring->enqueue->link.control &=
                                cpu_to_le32(~TRB_CHAIN);
                else
                        ep_ring->enqueue->link.control |=
                                cpu_to_le32(TRB_CHAIN);

                wmb();
                ep_ring->enqueue->link.control ^= cpu_to_le32(TRB_CYCLE);

                /* Toggle the cycle bit after the last ring segment. */
                if (link_trb_toggles_cycle(ep_ring->enqueue))
                        ep_ring->cycle_state ^= 1;

                ep_ring->enq_seg = ep_ring->enq_seg->next;
                ep_ring->enqueue = ep_ring->enq_seg->trbs;

                /* prevent infinite loop if all first trbs are link trbs */
                if (link_trb_count++ > ep_ring->num_segs) {
                        xhci_warn(xhci, "Ring is an endless link TRB loop\n");
                        return -EINVAL;
                }
        }

        if (last_trb_on_seg(ep_ring->enq_seg, ep_ring->enqueue)) {
                xhci_warn(xhci, "Missing link TRB at end of ring segment\n");
                return -EINVAL;
        }

        return 0;
}

static int prepare_transfer(struct xhci_hcd *xhci,
                struct xhci_virt_device *xdev,
                unsigned int ep_index,
                unsigned int stream_id,
                unsigned int num_trbs,
                struct urb *urb,
                unsigned int td_index,
                gfp_t mem_flags)
{
        int ret;
        struct urb_priv *urb_priv;
        struct xhci_td  *td;
        struct xhci_ring *ep_ring;
        struct xhci_ep_ctx *ep_ctx = xhci_get_ep_ctx(xhci, xdev->out_ctx, ep_index);

        ep_ring = xhci_triad_to_transfer_ring(xhci, xdev->slot_id, ep_index,
                                              stream_id);
        if (!ep_ring) {
                xhci_dbg(xhci, "Can't prepare ring for bad stream ID %u\n",
                                stream_id);
                return -EINVAL;
        }

        ret = prepare_ring(xhci, ep_ring, GET_EP_CTX_STATE(ep_ctx),
                           num_trbs, mem_flags);
        if (ret)
                return ret;

        urb_priv = urb->hcpriv;
        td = &urb_priv->td[td_index];

        INIT_LIST_HEAD(&td->td_list);
        INIT_LIST_HEAD(&td->cancelled_td_list);

        if (td_index == 0) {
                ret = usb_hcd_link_urb_to_ep(bus_to_hcd(urb->dev->bus), urb);
                if (unlikely(ret))
                        return ret;
        }

        td->urb = urb;
        /* Add this TD to the tail of the endpoint ring's TD list */
        list_add_tail(&td->td_list, &ep_ring->td_list);
        td->start_seg = ep_ring->enq_seg;
        td->first_trb = ep_ring->enqueue;

        return 0;
}

unsigned int count_trbs(u64 addr, u64 len)
{
        unsigned int num_trbs;

        num_trbs = DIV_ROUND_UP(len + (addr & (TRB_MAX_BUFF_SIZE - 1)),
                        TRB_MAX_BUFF_SIZE);
        if (num_trbs == 0)
                num_trbs++;

        return num_trbs;
}

static inline unsigned int count_trbs_needed(struct urb *urb)
{
        return count_trbs(urb->transfer_dma, urb->transfer_buffer_length);
}

static unsigned int count_sg_trbs_needed(struct urb *urb)
{
        struct scatterlist *sg;
        unsigned int i, len, full_len, num_trbs = 0;

        full_len = urb->transfer_buffer_length;

        for_each_sg(urb->sg, sg, urb->num_mapped_sgs, i) {
                len = sg_dma_len(sg);
                num_trbs += count_trbs(sg_dma_address(sg), len);
                len = min_t(unsigned int, len, full_len);
                full_len -= len;
                if (full_len == 0)
                        break;
        }

        return num_trbs;
}

static unsigned int count_isoc_trbs_needed(struct urb *urb, int i)
{
        u64 addr, len;

        addr = (u64) (urb->transfer_dma + urb->iso_frame_desc[i].offset);
        len = urb->iso_frame_desc[i].length;

        return count_trbs(addr, len);
}

static void check_trb_math(struct urb *urb, int running_total)
{
        if (unlikely(running_total != urb->transfer_buffer_length))
                dev_err(&urb->dev->dev, "%s - ep %#x - Miscalculated tx length, "
                                "queued %#x (%d), asked for %#x (%d)\n",
                                __func__,
                                urb->ep->desc.bEndpointAddress,
                                running_total, running_total,
                                urb->transfer_buffer_length,
                                urb->transfer_buffer_length);
}

static void giveback_first_trb(struct xhci_hcd *xhci, int slot_id,
                unsigned int ep_index, unsigned int stream_id, int start_cycle,
                struct xhci_generic_trb *start_trb)
{
        /*
         * Pass all the TRBs to the hardware at once and make sure this write
         * isn't reordered.
         */
        wmb();
        if (start_cycle)
                start_trb->field[3] |= cpu_to_le32(start_cycle);
        else
                start_trb->field[3] &= cpu_to_le32(~TRB_CYCLE);
        xhci_ring_ep_doorbell(xhci, slot_id, ep_index, stream_id);
}

static void check_interval(struct xhci_hcd *xhci, struct urb *urb,
                                                struct xhci_ep_ctx *ep_ctx)
{
        int xhci_interval;
        int ep_interval;

        xhci_interval = EP_INTERVAL_TO_UFRAMES(le32_to_cpu(ep_ctx->ep_info));
        ep_interval = urb->interval;

        /* Convert to microframes */
        if (urb->dev->speed == USB_SPEED_LOW ||
                        urb->dev->speed == USB_SPEED_FULL)
                ep_interval *= 8;

        /* FIXME change this to a warning and a suggestion to use the new API
         * to set the polling interval (once the API is added).
         */
        if (xhci_interval != ep_interval) {
                dev_dbg_ratelimited(&urb->dev->dev,
                                "Driver uses different interval (%d microframe%s) than xHCI (%d microframe%s)\n",
                                ep_interval, ep_interval == 1 ? "" : "s",
                                xhci_interval, xhci_interval == 1 ? "" : "s");
                urb->interval = xhci_interval;
                /* Convert back to frames for LS/FS devices */
                if (urb->dev->speed == USB_SPEED_LOW ||
                                urb->dev->speed == USB_SPEED_FULL)
                        urb->interval /= 8;
        }
}

/*
 * xHCI uses normal TRBs for both bulk and interrupt.  When the interrupt
 * endpoint is to be serviced, the xHC will consume (at most) one TD.  A TD
 * (comprised of sg list entries) can take several service intervals to
 * transmit.
 */
int xhci_queue_intr_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
                struct urb *urb, int slot_id, unsigned int ep_index)
{
        struct xhci_ep_ctx *ep_ctx;

        ep_ctx = xhci_get_ep_ctx(xhci, xhci->devs[slot_id]->out_ctx, ep_index);
        check_interval(xhci, urb, ep_ctx);

        return xhci_queue_bulk_tx(xhci, mem_flags, urb, slot_id, ep_index);
}

/*
 * For xHCI 1.0 host controllers, TD size is the number of max packet sized
 * packets remaining in the TD (*not* including this TRB).
 *
 * Total TD packet count = total_packet_count =
 *     DIV_ROUND_UP(TD size in bytes / wMaxPacketSize)
 *
 * Packets transferred up to and including this TRB = packets_transferred =
 *     rounddown(total bytes transferred including this TRB / wMaxPacketSize)
 *
 * TD size = total_packet_count - packets_transferred
 *
 * For xHCI 0.96 and older, TD size field should be the remaining bytes
 * including this TRB, right shifted by 10
 *
 * For all hosts it must fit in bits 21:17, so it can't be bigger than 31.
 * This is taken care of in the TRB_TD_SIZE() macro
 *
 * The last TRB in a TD must have the TD size set to zero.
 */
static u32 xhci_td_remainder(struct xhci_hcd *xhci, int transferred,
                              int trb_buff_len, unsigned int td_total_len,
                              struct urb *urb, bool more_trbs_coming)
{
        u32 maxp, total_packet_count;

        /* MTK xHCI 0.96 contains some features from 1.0 */
        if (xhci->hci_version < 0x100 && !(xhci->quirks & XHCI_MTK_HOST))
                return ((td_total_len - transferred) >> 10);

        /* One TRB with a zero-length data packet. */
        if (!more_trbs_coming || (transferred == 0 && trb_buff_len == 0) ||
            trb_buff_len == td_total_len)
                return 0;

        /* for MTK xHCI 0.96, TD size include this TRB, but not in 1.x */
        if ((xhci->quirks & XHCI_MTK_HOST) && (xhci->hci_version < 0x100))
                trb_buff_len = 0;

        maxp = usb_endpoint_maxp(&urb->ep->desc);
        total_packet_count = DIV_ROUND_UP(td_total_len, maxp);

        /* Queueing functions don't count the current TRB into transferred */
        return (total_packet_count - ((transferred + trb_buff_len) / maxp));
}


static int xhci_align_td(struct xhci_hcd *xhci, struct urb *urb, u32 enqd_len,
                         u32 *trb_buff_len, struct xhci_segment *seg)
{
        struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
        unsigned int unalign;
        unsigned int max_pkt;
        u32 new_buff_len;
        size_t len;

        max_pkt = usb_endpoint_maxp(&urb->ep->desc);
        unalign = (enqd_len + *trb_buff_len) % max_pkt;

        /* we got lucky, last normal TRB data on segment is packet aligned */
        if (unalign == 0)
                return 0;

        xhci_dbg(xhci, "Unaligned %d bytes, buff len %d\n",
                 unalign, *trb_buff_len);

        /* is the last nornal TRB alignable by splitting it */
        if (*trb_buff_len > unalign) {
                *trb_buff_len -= unalign;
                xhci_dbg(xhci, "split align, new buff len %d\n", *trb_buff_len);
                return 0;
        }

        /*
         * We want enqd_len + trb_buff_len to sum up to a number aligned to
         * number which is divisible by the endpoint's wMaxPacketSize. IOW:
         * (size of currently enqueued TRBs + remainder) % wMaxPacketSize == 0.
         */
        new_buff_len = max_pkt - (enqd_len % max_pkt);

        if (new_buff_len > (urb->transfer_buffer_length - enqd_len))
                new_buff_len = (urb->transfer_buffer_length - enqd_len);

        /* create a max max_pkt sized bounce buffer pointed to by last trb */
        if (usb_urb_dir_out(urb)) {
                if (urb->num_sgs) {
                        len = sg_pcopy_to_buffer(urb->sg, urb->num_sgs,
                                                 seg->bounce_buf, new_buff_len, enqd_len);
                        if (len != new_buff_len)
                                xhci_warn(xhci, "WARN Wrong bounce buffer write length: %zu != %d\n",
                                          len, new_buff_len);
                } else {
                        memcpy(seg->bounce_buf, urb->transfer_buffer + enqd_len, new_buff_len);
                }

                seg->bounce_dma = dma_map_single(dev, seg->bounce_buf,
                                                 max_pkt, DMA_TO_DEVICE);
        } else {
                seg->bounce_dma = dma_map_single(dev, seg->bounce_buf,
                                                 max_pkt, DMA_FROM_DEVICE);
        }

        if (dma_mapping_error(dev, seg->bounce_dma)) {
                /* try without aligning. Some host controllers survive */
                xhci_warn(xhci, "Failed mapping bounce buffer, not aligning\n");
                return 0;
        }
        *trb_buff_len = new_buff_len;
        seg->bounce_len = new_buff_len;
        seg->bounce_offs = enqd_len;

        xhci_dbg(xhci, "Bounce align, new buff len %d\n", *trb_buff_len);

        return 1;
}

/* This is very similar to what ehci-q.c qtd_fill() does */
int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
                struct urb *urb, int slot_id, unsigned int ep_index)
{
        struct xhci_ring *ring;
        struct urb_priv *urb_priv;
        struct xhci_td *td;
        struct xhci_generic_trb *start_trb;
        struct scatterlist *sg = NULL;
        bool more_trbs_coming = true;
        bool need_zero_pkt = false;
        bool first_trb = true;
        unsigned int num_trbs;
        unsigned int start_cycle, num_sgs = 0;
        unsigned int enqd_len, block_len, trb_buff_len, full_len;
        int sent_len, ret;
        u32 field, length_field, remainder;
        u64 addr, send_addr;

        ring = xhci_urb_to_transfer_ring(xhci, urb);
        if (!ring)
                return -EINVAL;

        full_len = urb->transfer_buffer_length;
        /* If we have scatter/gather list, we use it. */
        if (urb->num_sgs && !(urb->transfer_flags & URB_DMA_MAP_SINGLE)) {
                num_sgs = urb->num_mapped_sgs;
                sg = urb->sg;
                addr = (u64) sg_dma_address(sg);
                block_len = sg_dma_len(sg);
                num_trbs = count_sg_trbs_needed(urb);
        } else {
                num_trbs = count_trbs_needed(urb);
                addr = (u64) urb->transfer_dma;
                block_len = full_len;
        }
        ret = prepare_transfer(xhci, xhci->devs[slot_id],
                        ep_index, urb->stream_id,
                        num_trbs, urb, 0, mem_flags);
        if (unlikely(ret < 0))
                return ret;

        urb_priv = urb->hcpriv;

        /* Deal with URB_ZERO_PACKET - need one more td/trb */
        if (urb->transfer_flags & URB_ZERO_PACKET && urb_priv->num_tds > 1)
                need_zero_pkt = true;

        td = &urb_priv->td[0];

        /*
         * Don't give the first TRB to the hardware (by toggling the cycle bit)
         * until we've finished creating all the other TRBs.  The ring's cycle
         * state may change as we enqueue the other TRBs, so save it too.
         */
        start_trb = &ring->enqueue->generic;
        start_cycle = ring->cycle_state;
        send_addr = addr;

        /* Queue the TRBs, even if they are zero-length */
        for (enqd_len = 0; first_trb || enqd_len < full_len;
                        enqd_len += trb_buff_len) {
                field = TRB_TYPE(TRB_NORMAL);

                /* TRB buffer should not cross 64KB boundaries */
                trb_buff_len = TRB_BUFF_LEN_UP_TO_BOUNDARY(addr);
                trb_buff_len = min_t(unsigned int, trb_buff_len, block_len);

                if (enqd_len + trb_buff_len > full_len)
                        trb_buff_len = full_len - enqd_len;

                /* Don't change the cycle bit of the first TRB until later */
                if (first_trb) {
                        first_trb = false;
                        if (start_cycle == 0)
                                field |= TRB_CYCLE;
                } else
                        field |= ring->cycle_state;

                /* Chain all the TRBs together; clear the chain bit in the last
                 * TRB to indicate it's the last TRB in the chain.
                 */
                if (enqd_len + trb_buff_len < full_len) {
                        field |= TRB_CHAIN;
                        if (trb_is_link(ring->enqueue + 1)) {
                                if (xhci_align_td(xhci, urb, enqd_len,
                                                  &trb_buff_len,
                                                  ring->enq_seg)) {
                                        send_addr = ring->enq_seg->bounce_dma;
                                        /* assuming TD won't span 2 segs */
                                        td->bounce_seg = ring->enq_seg;
                                }
                        }
                }
                if (enqd_len + trb_buff_len >= full_len) {
                        field &= ~TRB_CHAIN;
                        field |= TRB_IOC;
                        more_trbs_coming = false;
                        td->last_trb = ring->enqueue;
                        td->last_trb_seg = ring->enq_seg;
                        if (xhci_urb_suitable_for_idt(urb)) {
                                memcpy(&send_addr, urb->transfer_buffer,
                                       trb_buff_len);
                                le64_to_cpus(&send_addr);
                                field |= TRB_IDT;
                        }
                }

                /* Only set interrupt on short packet for IN endpoints */
                if (usb_urb_dir_in(urb))
                        field |= TRB_ISP;

                /* Set the TRB length, TD size, and interrupter fields. */
                remainder = xhci_td_remainder(xhci, enqd_len, trb_buff_len,
                                              full_len, urb, more_trbs_coming);

                length_field = TRB_LEN(trb_buff_len) |
                        TRB_TD_SIZE(remainder) |
                        TRB_INTR_TARGET(0);

                queue_trb(xhci, ring, more_trbs_coming | need_zero_pkt,
                                lower_32_bits(send_addr),
                                upper_32_bits(send_addr),
                                length_field,
                                field);
                td->num_trbs++;
                addr += trb_buff_len;
                sent_len = trb_buff_len;

                while (sg && sent_len >= block_len) {
                        /* New sg entry */
                        --num_sgs;
                        sent_len -= block_len;
                        sg = sg_next(sg);
                        if (num_sgs != 0 && sg) {
                                block_len = sg_dma_len(sg);
                                addr = (u64) sg_dma_address(sg);
                                addr += sent_len;
                        }
                }
                block_len -= sent_len;
                send_addr = addr;
        }

        if (need_zero_pkt) {
                ret = prepare_transfer(xhci, xhci->devs[slot_id],
                                       ep_index, urb->stream_id,
                                       1, urb, 1, mem_flags);
                urb_priv->td[1].last_trb = ring->enqueue;
                urb_priv->td[1].last_trb_seg = ring->enq_seg;
                field = TRB_TYPE(TRB_NORMAL) | ring->cycle_state | TRB_IOC;
                queue_trb(xhci, ring, 0, 0, 0, TRB_INTR_TARGET(0), field);
                urb_priv->td[1].num_trbs++;
        }

        check_trb_math(urb, enqd_len);
        giveback_first_trb(xhci, slot_id, ep_index, urb->stream_id,
                        start_cycle, start_trb);
        return 0;
}

/* Caller must have locked xhci->lock */
int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
                struct urb *urb, int slot_id, unsigned int ep_index)
{
        struct xhci_ring *ep_ring;
        int num_trbs;
        int ret;
        struct usb_ctrlrequest *setup;
        struct xhci_generic_trb *start_trb;
        int start_cycle;
        u32 field;
        struct urb_priv *urb_priv;
        struct xhci_td *td;

        ep_ring = xhci_urb_to_transfer_ring(xhci, urb);
        if (!ep_ring)
                return -EINVAL;

        /*
         * Need to copy setup packet into setup TRB, so we can't use the setup
         * DMA address.
         */
        if (!urb->setup_packet)
                return -EINVAL;

        /* 1 TRB for setup, 1 for status */
        num_trbs = 2;
        /*
         * Don't need to check if we need additional event data and normal TRBs,
         * since data in control transfers will never get bigger than 16MB
         * XXX: can we get a buffer that crosses 64KB boundaries?
         */
        if (urb->transfer_buffer_length > 0)
                num_trbs++;
        ret = prepare_transfer(xhci, xhci->devs[slot_id],
                        ep_index, urb->stream_id,
                        num_trbs, urb, 0, mem_flags);
        if (ret < 0)
                return ret;

        urb_priv = urb->hcpriv;
        td = &urb_priv->td[0];
        td->num_trbs = num_trbs;

        /*
         * Don't give the first TRB to the hardware (by toggling the cycle bit)
         * until we've finished creating all the other TRBs.  The ring's cycle
         * state may change as we enqueue the other TRBs, so save it too.
         */
        start_trb = &ep_ring->enqueue->generic;
        start_cycle = ep_ring->cycle_state;

        /* Queue setup TRB - see section 6.4.1.2.1 */
        /* FIXME better way to translate setup_packet into two u32 fields? */
        setup = (struct usb_ctrlrequest *) urb->setup_packet;
        field = 0;
        field |= TRB_IDT | TRB_TYPE(TRB_SETUP);
        if (start_cycle == 0)
                field |= 0x1;

        /* xHCI 1.0/1.1 6.4.1.2.1: Transfer Type field */
        if ((xhci->hci_version >= 0x100) || (xhci->quirks & XHCI_MTK_HOST)) {
                if (urb->transfer_buffer_length > 0) {
                        if (setup->bRequestType & USB_DIR_IN)
                                field |= TRB_TX_TYPE(TRB_DATA_IN);
                        else
                                field |= TRB_TX_TYPE(TRB_DATA_OUT);
                }
        }

        queue_trb(xhci, ep_ring, true,
                  setup->bRequestType | setup->bRequest << 8 | le16_to_cpu(setup->wValue) << 16,
                  le16_to_cpu(setup->wIndex) | le16_to_cpu(setup->wLength) << 16,
                  TRB_LEN(8) | TRB_INTR_TARGET(0),
                  /* Immediate data in pointer */
                  field);

        /* If there's data, queue data TRBs */
        /* Only set interrupt on short packet for IN endpoints */
        if (usb_urb_dir_in(urb))
                field = TRB_ISP | TRB_TYPE(TRB_DATA);
        else
                field = TRB_TYPE(TRB_DATA);

        if (urb->transfer_buffer_length > 0) {
                u32 length_field, remainder;
                u64 addr;

                if (xhci_urb_suitable_for_idt(urb)) {
                        memcpy(&addr, urb->transfer_buffer,
                               urb->transfer_buffer_length);
                        le64_to_cpus(&addr);
                        field |= TRB_IDT;
                } else {
                        addr = (u64) urb->transfer_dma;
                }

                remainder = xhci_td_remainder(xhci, 0,
                                urb->transfer_buffer_length,
                                urb->transfer_buffer_length,
                                urb, 1);
                length_field = TRB_LEN(urb->transfer_buffer_length) |
                                TRB_TD_SIZE(remainder) |
                                TRB_INTR_TARGET(0);
                if (setup->bRequestType & USB_DIR_IN)
                        field |= TRB_DIR_IN;
                queue_trb(xhci, ep_ring, true,
                                lower_32_bits(addr),
                                upper_32_bits(addr),
                                length_field,
                                field | ep_ring->cycle_state);
        }

        /* Save the DMA address of the last TRB in the TD */
        td->last_trb = ep_ring->enqueue;
        td->last_trb_seg = ep_ring->enq_seg;

        /* Queue status TRB - see Table 7 and sections 4.11.2.2 and 6.4.1.2.3 */
        /* If the device sent data, the status stage is an OUT transfer */
        if (urb->transfer_buffer_length > 0 && setup->bRequestType & USB_DIR_IN)
                field = 0;
        else
                field = TRB_DIR_IN;
        queue_trb(xhci, ep_ring, false,
                        0,
                        0,
                        TRB_INTR_TARGET(0),
                        /* Event on completion */
                        field | TRB_IOC | TRB_TYPE(TRB_STATUS) | ep_ring->cycle_state);

        giveback_first_trb(xhci, slot_id, ep_index, 0,
                        start_cycle, start_trb);
        return 0;
}

/*
 * The transfer burst count field of the isochronous TRB defines the number of
 * bursts that are required to move all packets in this TD.  Only SuperSpeed
 * devices can burst up to bMaxBurst number of packets per service interval.
 * This field is zero based, meaning a value of zero in the field means one
 * burst.  Basically, for everything but SuperSpeed devices, this field will be
 * zero.  Only xHCI 1.0 host controllers support this field.
 */
static unsigned int xhci_get_burst_count(struct xhci_hcd *xhci,
                struct urb *urb, unsigned int total_packet_count)
{
        unsigned int max_burst;

        if (xhci->hci_version < 0x100 || urb->dev->speed < USB_SPEED_SUPER)
                return 0;

        max_burst = urb->ep->ss_ep_comp.bMaxBurst;
        return DIV_ROUND_UP(total_packet_count, max_burst + 1) - 1;
}

/*
 * Returns the number of packets in the last "burst" of packets.  This field is
 * valid for all speeds of devices.  USB 2.0 devices can only do one "burst", so
 * the last burst packet count is equal to the total number of packets in the
 * TD.  SuperSpeed endpoints can have up to 3 bursts.  All but the last burst
 * must contain (bMaxBurst + 1) number of packets, but the last burst can
 * contain 1 to (bMaxBurst + 1) packets.
 */
static unsigned int xhci_get_last_burst_packet_count(struct xhci_hcd *xhci,
                struct urb *urb, unsigned int total_packet_count)
{
        unsigned int max_burst;
        unsigned int residue;

        if (xhci->hci_version < 0x100)
                return 0;

        if (urb->dev->speed >= USB_SPEED_SUPER) {
                /* bMaxBurst is zero based: 0 means 1 packet per burst */
                max_burst = urb->ep->ss_ep_comp.bMaxBurst;
                residue = total_packet_count % (max_burst + 1);
                /* If residue is zero, the last burst contains (max_burst + 1)
                 * number of packets, but the TLBPC field is zero-based.
                 */
                if (residue == 0)
                        return max_burst;
                return residue - 1;
        }
        if (total_packet_count == 0)
                return 0;
        return total_packet_count - 1;
}

/*
 * Calculates Frame ID field of the isochronous TRB identifies the
 * target frame that the Interval associated with this Isochronous
 * Transfer Descriptor will start on. Refer to 4.11.2.5 in 1.1 spec.
 *
 * Returns actual frame id on success, negative value on error.
 */
static int xhci_get_isoc_frame_id(struct xhci_hcd *xhci,
                struct urb *urb, int index)
{
        int start_frame, ist, ret = 0;
        int start_frame_id, end_frame_id, current_frame_id;

        if (urb->dev->speed == USB_SPEED_LOW ||
                        urb->dev->speed == USB_SPEED_FULL)
                start_frame = urb->start_frame + index * urb->interval;
        else
                start_frame = (urb->start_frame + index * urb->interval) >> 3;

        /* Isochronous Scheduling Threshold (IST, bits 0~3 in HCSPARAMS2):
         *
         * If bit [3] of IST is cleared to '0', software can add a TRB no
         * later than IST[2:0] Microframes before that TRB is scheduled to
         * be executed.
         * If bit [3] of IST is set to '1', software can add a TRB no later
         * than IST[2:0] Frames before that TRB is scheduled to be executed.
         */
        ist = HCS_IST(xhci->hcs_params2) & 0x7;
        if (HCS_IST(xhci->hcs_params2) & (1 << 3))
                ist <<= 3;

        /* Software shall not schedule an Isoch TD with a Frame ID value that
         * is less than the Start Frame ID or greater than the End Frame ID,
         * where:
         *
         * End Frame ID = (Current MFINDEX register value + 895 ms.) MOD 2048
         * Start Frame ID = (Current MFINDEX register value + IST + 1) MOD 2048
         *
         * Both the End Frame ID and Start Frame ID values are calculated
         * in microframes. When software determines the valid Frame ID value;
         * The End Frame ID value should be rounded down to the nearest Frame
         * boundary, and the Start Frame ID value should be rounded up to the
         * nearest Frame boundary.
         */
        current_frame_id = readl(&xhci->run_regs->microframe_index);
        start_frame_id = roundup(current_frame_id + ist + 1, 8);
        end_frame_id = rounddown(current_frame_id + 895 * 8, 8);

        start_frame &= 0x7ff;
        start_frame_id = (start_frame_id >> 3) & 0x7ff;
        end_frame_id = (end_frame_id >> 3) & 0x7ff;

        xhci_dbg(xhci, "%s: index %d, reg 0x%x start_frame_id 0x%x, end_frame_id 0x%x, start_frame 0x%x\n",
                 __func__, index, readl(&xhci->run_regs->microframe_index),
                 start_frame_id, end_frame_id, start_frame);

        if (start_frame_id < end_frame_id) {
                if (start_frame > end_frame_id ||
                                start_frame < start_frame_id)
                        ret = -EINVAL;
        } else if (start_frame_id > end_frame_id) {
                if ((start_frame > end_frame_id &&
                                start_frame < start_frame_id))
                        ret = -EINVAL;
        } else {
                        ret = -EINVAL;
        }

        if (index == 0) {
                if (ret == -EINVAL || start_frame == start_frame_id) {
                        start_frame = start_frame_id + 1;
                        if (urb->dev->speed == USB_SPEED_LOW ||
                                        urb->dev->speed == USB_SPEED_FULL)
                                urb->start_frame = start_frame;
                        else
                                urb->start_frame = start_frame << 3;
                        ret = 0;
                }
        }

        if (ret) {
                xhci_warn(xhci, "Frame ID %d (reg %d, index %d) beyond range (%d, %d)\n",
                                start_frame, current_frame_id, index,
                                start_frame_id, end_frame_id);
                xhci_warn(xhci, "Ignore frame ID field, use SIA bit instead\n");
                return ret;
        }

        return start_frame;
}

/* Check if we should generate event interrupt for a TD in an isoc URB */
static bool trb_block_event_intr(struct xhci_hcd *xhci, int num_tds, int i,
                                 struct xhci_interrupter *ir)
{
        if (xhci->hci_version < 0x100)
                return false;
        /* always generate an event interrupt for the last TD */
        if (i == num_tds - 1)
                return false;
        /*
         * If AVOID_BEI is set the host handles full event rings poorly,
         * generate an event at least every 8th TD to clear the event ring
         */
        if (i && ir->isoc_bei_interval && xhci->quirks & XHCI_AVOID_BEI)
                return !!(i % ir->isoc_bei_interval);

        return true;
}

/* This is for isoc transfer */
static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
                struct urb *urb, int slot_id, unsigned int ep_index)
{
        struct xhci_interrupter *ir;
        struct xhci_ring *ep_ring;
        struct urb_priv *urb_priv;
        struct xhci_td *td;
        int num_tds, trbs_per_td;
        struct xhci_generic_trb *start_trb;
        bool first_trb;
        int start_cycle;
        u32 field, length_field;
        int running_total, trb_buff_len, td_len, td_remain_len, ret;
        u64 start_addr, addr;
        int i, j;
        bool more_trbs_coming;
        struct xhci_virt_ep *xep;
        int frame_id;

        xep = &xhci->devs[slot_id]->eps[ep_index];
        ep_ring = xhci->devs[slot_id]->eps[ep_index].ring;
        ir = xhci->interrupters[0];

        num_tds = urb->number_of_packets;
        if (num_tds < 1) {
                xhci_dbg(xhci, "Isoc URB with zero packets?\n");
                return -EINVAL;
        }
        start_addr = (u64) urb->transfer_dma;
        start_trb = &ep_ring->enqueue->generic;
        start_cycle = ep_ring->cycle_state;

        urb_priv = urb->hcpriv;
        /* Queue the TRBs for each TD, even if they are zero-length */
        for (i = 0; i < num_tds; i++) {
                unsigned int total_pkt_count, max_pkt;
                unsigned int burst_count, last_burst_pkt_count;
                u32 sia_frame_id;

                first_trb = true;
                running_total = 0;
                addr = start_addr + urb->iso_frame_desc[i].offset;
                td_len = urb->iso_frame_desc[i].length;
                td_remain_len = td_len;
                max_pkt = usb_endpoint_maxp(&urb->ep->desc);
                total_pkt_count = DIV_ROUND_UP(td_len, max_pkt);

                /* A zero-length transfer still involves at least one packet. */
                if (total_pkt_count == 0)
                        total_pkt_count++;
                burst_count = xhci_get_burst_count(xhci, urb, total_pkt_count);
                last_burst_pkt_count = xhci_get_last_burst_packet_count(xhci,
                                                        urb, total_pkt_count);

                trbs_per_td = count_isoc_trbs_needed(urb, i);

                ret = prepare_transfer(xhci, xhci->devs[slot_id], ep_index,
                                urb->stream_id, trbs_per_td, urb, i, mem_flags);
                if (ret < 0) {
                        if (i == 0)
                                return ret;
                        goto cleanup;
                }
                td = &urb_priv->td[i];
                td->num_trbs = trbs_per_td;
                /* use SIA as default, if frame id is used overwrite it */
                sia_frame_id = TRB_SIA;
                if (!(urb->transfer_flags & URB_ISO_ASAP) &&
                    HCC_CFC(xhci->hcc_params)) {
                        frame_id = xhci_get_isoc_frame_id(xhci, urb, i);
                        if (frame_id >= 0)
                                sia_frame_id = TRB_FRAME_ID(frame_id);
                }
                /*
                 * Set isoc specific data for the first TRB in a TD.
                 * Prevent HW from getting the TRBs by keeping the cycle state
                 * inverted in the first TDs isoc TRB.
                 */
                field = TRB_TYPE(TRB_ISOC) |
                        TRB_TLBPC(last_burst_pkt_count) |
                        sia_frame_id |
                        (i ? ep_ring->cycle_state : !start_cycle);

                /* xhci 1.1 with ETE uses TD_Size field for TBC, old is Rsvdz */
                if (!xep->use_extended_tbc)
                        field |= TRB_TBC(burst_count);

                /* fill the rest of the TRB fields, and remaining normal TRBs */
                for (j = 0; j < trbs_per_td; j++) {
                        u32 remainder = 0;

                        /* only first TRB is isoc, overwrite otherwise */
                        if (!first_trb)
                                field = TRB_TYPE(TRB_NORMAL) |
                                        ep_ring->cycle_state;

                        /* Only set interrupt on short packet for IN EPs */
                        if (usb_urb_dir_in(urb))
                                field |= TRB_ISP;

                        /* Set the chain bit for all except the last TRB  */
                        if (j < trbs_per_td - 1) {
                                more_trbs_coming = true;
                                field |= TRB_CHAIN;
                        } else {
                                more_trbs_coming = false;
                                td->last_trb = ep_ring->enqueue;
                                td->last_trb_seg = ep_ring->enq_seg;
                                field |= TRB_IOC;
                                if (trb_block_event_intr(xhci, num_tds, i, ir))
                                        field |= TRB_BEI;
                        }
                        /* Calculate TRB length */
                        trb_buff_len = TRB_BUFF_LEN_UP_TO_BOUNDARY(addr);
                        if (trb_buff_len > td_remain_len)
                                trb_buff_len = td_remain_len;

                        /* Set the TRB length, TD size, & interrupter fields. */
                        remainder = xhci_td_remainder(xhci, running_total,
                                                   trb_buff_len, td_len,
                                                   urb, more_trbs_coming);

                        length_field = TRB_LEN(trb_buff_len) |
                                TRB_INTR_TARGET(0);

                        /* xhci 1.1 with ETE uses TD Size field for TBC */
                        if (first_trb && xep->use_extended_tbc)
                                length_field |= TRB_TD_SIZE_TBC(burst_count);
                        else
                                length_field |= TRB_TD_SIZE(remainder);
                        first_trb = false;

                        queue_trb(xhci, ep_ring, more_trbs_coming,
                                lower_32_bits(addr),
                                upper_32_bits(addr),
                                length_field,
                                field);
                        running_total += trb_buff_len;

                        addr += trb_buff_len;
                        td_remain_len -= trb_buff_len;
                }

                /* Check TD length */
                if (running_total != td_len) {
                        xhci_err(xhci, "ISOC TD length unmatch\n");
                        ret = -EINVAL;
                        goto cleanup;
                }
        }

        /* store the next frame id */
        if (HCC_CFC(xhci->hcc_params))
                xep->next_frame_id = urb->start_frame + num_tds * urb->interval;

        if (xhci_to_hcd(xhci)->self.bandwidth_isoc_reqs == 0) {
                if (xhci->quirks & XHCI_AMD_PLL_FIX)
                        usb_amd_quirk_pll_disable();
        }
        xhci_to_hcd(xhci)->self.bandwidth_isoc_reqs++;

        giveback_first_trb(xhci, slot_id, ep_index, urb->stream_id,
                        start_cycle, start_trb);
        return 0;
cleanup:
        /* Clean up a partially enqueued isoc transfer. */

        for (i--; i >= 0; i--)
                list_del_init(&urb_priv->td[i].td_list);

        /* Use the first TD as a temporary variable to turn the TDs we've queued
         * into No-ops with a software-owned cycle bit. That way the hardware
         * won't accidentally start executing bogus TDs when we partially
         * overwrite them.  td->first_trb and td->start_seg are already set.
         */
        urb_priv->td[0].last_trb = ep_ring->enqueue;
        /* Every TRB except the first & last will have its cycle bit flipped. */
        td_to_noop(xhci, ep_ring, &urb_priv->td[0], true);

        /* Reset the ring enqueue back to the first TRB and its cycle bit. */
        ep_ring->enqueue = urb_priv->td[0].first_trb;
        ep_ring->enq_seg = urb_priv->td[0].start_seg;
        ep_ring->cycle_state = start_cycle;
        usb_hcd_unlink_urb_from_ep(bus_to_hcd(urb->dev->bus), urb);
        return ret;
}

/*
 * Check transfer ring to guarantee there is enough room for the urb.
 * Update ISO URB start_frame and interval.
 * Update interval as xhci_queue_intr_tx does. Use xhci frame_index to
 * update urb->start_frame if URB_ISO_ASAP is set in transfer_flags or
 * Contiguous Frame ID is not supported by HC.
 */
int xhci_queue_isoc_tx_prepare(struct xhci_hcd *xhci, gfp_t mem_flags,
                struct urb *urb, int slot_id, unsigned int ep_index)
{
        struct xhci_virt_device *xdev;
        struct xhci_ring *ep_ring;
        struct xhci_ep_ctx *ep_ctx;
        int start_frame;
        int num_tds, num_trbs, i;
        int ret;
        struct xhci_virt_ep *xep;
        int ist;

        xdev = xhci->devs[slot_id];
        xep = &xhci->devs[slot_id]->eps[ep_index];
        ep_ring = xdev->eps[ep_index].ring;
        ep_ctx = xhci_get_ep_ctx(xhci, xdev->out_ctx, ep_index);

        num_trbs = 0;
        num_tds = urb->number_of_packets;
        for (i = 0; i < num_tds; i++)
                num_trbs += count_isoc_trbs_needed(urb, i);

        /* Check the ring to guarantee there is enough room for the whole urb.
         * Do not insert any td of the urb to the ring if the check failed.
         */
        ret = prepare_ring(xhci, ep_ring, GET_EP_CTX_STATE(ep_ctx),
                           num_trbs, mem_flags);
        if (ret)
                return ret;

        /*
         * Check interval value. This should be done before we start to
         * calculate the start frame value.
         */
        check_interval(xhci, urb, ep_ctx);

        /* Calculate the start frame and put it in urb->start_frame. */
        if (HCC_CFC(xhci->hcc_params) && !list_empty(&ep_ring->td_list)) {
                if (GET_EP_CTX_STATE(ep_ctx) == EP_STATE_RUNNING) {
                        urb->start_frame = xep->next_frame_id;
                        goto skip_start_over;
                }
        }

        start_frame = readl(&xhci->run_regs->microframe_index);
        start_frame &= 0x3fff;
        /*
         * Round up to the next frame and consider the time before trb really
         * gets scheduled by hardare.
         */
        ist = HCS_IST(xhci->hcs_params2) & 0x7;
        if (HCS_IST(xhci->hcs_params2) & (1 << 3))
                ist <<= 3;
        start_frame += ist + XHCI_CFC_DELAY;
        start_frame = roundup(start_frame, 8);

        /*
         * Round up to the next ESIT (Endpoint Service Interval Time) if ESIT
         * is greate than 8 microframes.
         */
        if (urb->dev->speed == USB_SPEED_LOW ||
                        urb->dev->speed == USB_SPEED_FULL) {
                start_frame = roundup(start_frame, urb->interval << 3);
                urb->start_frame = start_frame >> 3;
        } else {
                start_frame = roundup(start_frame, urb->interval);
                urb->start_frame = start_frame;
        }

skip_start_over:

        return xhci_queue_isoc_tx(xhci, mem_flags, urb, slot_id, ep_index);
}

/****           Command Ring Operations         ****/

/* Generic function for queueing a command TRB on the command ring.
 * Check to make sure there's room on the command ring for one command TRB.
 * Also check that there's room reserved for commands that must not fail.
 * If this is a command that must not fail, meaning command_must_succeed = TRUE,
 * then only check for the number of reserved spots.
 * Don't decrement xhci->cmd_ring_reserved_trbs after we've queued the TRB
 * because the command event handler may want to resubmit a failed command.
 */
static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd,
                         u32 field1, u32 field2,
                         u32 field3, u32 field4, bool command_must_succeed)
{
        int reserved_trbs = xhci->cmd_ring_reserved_trbs;
        int ret;

        if ((xhci->xhc_state & XHCI_STATE_DYING) ||
                (xhci->xhc_state & XHCI_STATE_HALTED)) {
                xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n");
                return -ESHUTDOWN;
        }

        if (!command_must_succeed)
                reserved_trbs++;

        ret = prepare_ring(xhci, xhci->cmd_ring, EP_STATE_RUNNING,
                        reserved_trbs, GFP_ATOMIC);
        if (ret < 0) {
                xhci_err(xhci, "ERR: No room for command on command ring\n");
                if (command_must_succeed)
                        xhci_err(xhci, "ERR: Reserved TRB counting for "
                                        "unfailable commands failed.\n");
                return ret;
        }

        cmd->command_trb = xhci->cmd_ring->enqueue;

        /* if there are no other commands queued we start the timeout timer */
        if (list_empty(&xhci->cmd_list)) {
                xhci->current_cmd = cmd;
                xhci_mod_cmd_timer(xhci);
        }

        list_add_tail(&cmd->cmd_list, &xhci->cmd_list);

        queue_trb(xhci, xhci->cmd_ring, false, field1, field2, field3,
                        field4 | xhci->cmd_ring->cycle_state);
        return 0;
}

/* Queue a slot enable or disable request on the command ring */
int xhci_queue_slot_control(struct xhci_hcd *xhci, struct xhci_command *cmd,
                u32 trb_type, u32 slot_id)
{
        return queue_command(xhci, cmd, 0, 0, 0,
                        TRB_TYPE(trb_type) | SLOT_ID_FOR_TRB(slot_id), false);
}

/* Queue an address device command TRB */
int xhci_queue_address_device(struct xhci_hcd *xhci, struct xhci_command *cmd,
                dma_addr_t in_ctx_ptr, u32 slot_id, enum xhci_setup_dev setup)
{
        return queue_command(xhci, cmd, lower_32_bits(in_ctx_ptr),
                        upper_32_bits(in_ctx_ptr), 0,
                        TRB_TYPE(TRB_ADDR_DEV) | SLOT_ID_FOR_TRB(slot_id)
                        | (setup == SETUP_CONTEXT_ONLY ? TRB_BSR : 0), false);
}

int xhci_queue_vendor_command(struct xhci_hcd *xhci, struct xhci_command *cmd,
                u32 field1, u32 field2, u32 field3, u32 field4)
{
        return queue_command(xhci, cmd, field1, field2, field3, field4, false);
}

/* Queue a reset device command TRB */
int xhci_queue_reset_device(struct xhci_hcd *xhci, struct xhci_command *cmd,
                u32 slot_id)
{
        return queue_command(xhci, cmd, 0, 0, 0,
                        TRB_TYPE(TRB_RESET_DEV) | SLOT_ID_FOR_TRB(slot_id),
                        false);
}

/* Queue a configure endpoint command TRB */
int xhci_queue_configure_endpoint(struct xhci_hcd *xhci,
                struct xhci_command *cmd, dma_addr_t in_ctx_ptr,
                u32 slot_id, bool command_must_succeed)
{
        return queue_command(xhci, cmd, lower_32_bits(in_ctx_ptr),
                        upper_32_bits(in_ctx_ptr), 0,
                        TRB_TYPE(TRB_CONFIG_EP) | SLOT_ID_FOR_TRB(slot_id),
                        command_must_succeed);
}

/* Queue an evaluate context command TRB */
int xhci_queue_evaluate_context(struct xhci_hcd *xhci, struct xhci_command *cmd,
                dma_addr_t in_ctx_ptr, u32 slot_id, bool command_must_succeed)
{
        return queue_command(xhci, cmd, lower_32_bits(in_ctx_ptr),
                        upper_32_bits(in_ctx_ptr), 0,
                        TRB_TYPE(TRB_EVAL_CONTEXT) | SLOT_ID_FOR_TRB(slot_id),
                        command_must_succeed);
}

/*
 * Suspend is set to indicate "Stop Endpoint Command" is being issued to stop
 * activity on an endpoint that is about to be suspended.
 */
int xhci_queue_stop_endpoint(struct xhci_hcd *xhci, struct xhci_command *cmd,
                             int slot_id, unsigned int ep_index, int suspend)
{
        u32 trb_slot_id = SLOT_ID_FOR_TRB(slot_id);
        u32 trb_ep_index = EP_ID_FOR_TRB(ep_index);
        u32 type = TRB_TYPE(TRB_STOP_RING);
        u32 trb_suspend = SUSPEND_PORT_FOR_TRB(suspend);

        return queue_command(xhci, cmd, 0, 0, 0,
                        trb_slot_id | trb_ep_index | type | trb_suspend, false);
}

int xhci_queue_reset_ep(struct xhci_hcd *xhci, struct xhci_command *cmd,
                        int slot_id, unsigned int ep_index,
                        enum xhci_ep_reset_type reset_type)
{
        u32 trb_slot_id = SLOT_ID_FOR_TRB(slot_id);
        u32 trb_ep_index = EP_ID_FOR_TRB(ep_index);
        u32 type = TRB_TYPE(TRB_RESET_EP);

        if (reset_type == EP_SOFT_RESET)
                type |= TRB_TSP;

        return queue_command(xhci, cmd, 0, 0, 0,
                        trb_slot_id | trb_ep_index | type, false);
}