usb: hub: Translate USB 3.0 hub port status into old version

[people/ms/u-boot.git] / common / usb_hub.c

/*
 * Most of this source has been derived from the Linux USB
 * project:
 * (C) Copyright Linus Torvalds 1999
 * (C) Copyright Johannes Erdfelt 1999-2001
 * (C) Copyright Andreas Gal 1999
 * (C) Copyright Gregory P. Smith 1999
 * (C) Copyright Deti Fliegl 1999 (new USB architecture)
 * (C) Copyright Randy Dunlap 2000
 * (C) Copyright David Brownell 2000 (kernel hotplug, usb_device_id)
 * (C) Copyright Yggdrasil Computing, Inc. 2000
 *     (usb_device_id matching changes by Adam J. Richter)
 *
 * Adapted for U-Boot:
 * (C) Copyright 2001 Denis Peter, MPL AG Switzerland
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

/****************************************************************************
 * HUB "Driver"
 * Probes device for being a hub and configurate it
 */

#include <common.h>
#include <command.h>
#include <dm.h>
#include <errno.h>
#include <memalign.h>
#include <asm/processor.h>
#include <asm/unaligned.h>
#include <linux/ctype.h>
#include <linux/list.h>
#include <asm/byteorder.h>
#ifdef CONFIG_SANDBOX
#include <asm/state.h>
#endif
#include <asm/unaligned.h>

DECLARE_GLOBAL_DATA_PTR;

#include <usb.h>

#define USB_BUFSIZ      512

#define HUB_SHORT_RESET_TIME    20
#define HUB_LONG_RESET_TIME     200

#define PORT_OVERCURRENT_MAX_SCAN_COUNT         3

struct usb_device_scan {
        struct usb_device *dev;         /* USB hub device to scan */
        struct usb_hub_device *hub;     /* USB hub struct */
        int port;                       /* USB port to scan */
        struct list_head list;
};

static LIST_HEAD(usb_scan_list);

__weak void usb_hub_reset_devices(int port)
{
        return;
}

static inline bool usb_hub_is_superspeed(struct usb_device *hdev)
{
        return hdev->descriptor.bDeviceProtocol == 3;
}

#ifdef CONFIG_DM_USB
bool usb_hub_is_root_hub(struct udevice *hub)
{
        if (device_get_uclass_id(hub->parent) != UCLASS_USB_HUB)
                return true;

        return false;
}
#endif

static int usb_get_hub_descriptor(struct usb_device *dev, void *data, int size)
{
        unsigned short dtype = USB_DT_HUB;

        if (usb_hub_is_superspeed(dev))
                dtype = USB_DT_SS_HUB;

        return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                USB_REQ_GET_DESCRIPTOR, USB_DIR_IN | USB_RT_HUB,
                dtype << 8, 0, data, size, USB_CNTL_TIMEOUT);
}

static int usb_clear_port_feature(struct usb_device *dev, int port, int feature)
{
        return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                                USB_REQ_CLEAR_FEATURE, USB_RT_PORT, feature,
                                port, NULL, 0, USB_CNTL_TIMEOUT);
}

static int usb_set_port_feature(struct usb_device *dev, int port, int feature)
{
        return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                                USB_REQ_SET_FEATURE, USB_RT_PORT, feature,
                                port, NULL, 0, USB_CNTL_TIMEOUT);
}

static int usb_get_hub_status(struct usb_device *dev, void *data)
{
        return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                        USB_REQ_GET_STATUS, USB_DIR_IN | USB_RT_HUB, 0, 0,
                        data, sizeof(struct usb_hub_status), USB_CNTL_TIMEOUT);
}

int usb_get_port_status(struct usb_device *dev, int port, void *data)
{
        int ret;

        ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                        USB_REQ_GET_STATUS, USB_DIR_IN | USB_RT_PORT, 0, port,
                        data, sizeof(struct usb_port_status), USB_CNTL_TIMEOUT);

#ifdef CONFIG_DM_USB
        if (ret < 0)
                return ret;

        /*
         * Translate the USB 3.0 hub port status field into the old version
         * that U-Boot understands. Do this only when the hub is not root hub.
         * For root hub, the port status field has already been translated
         * in the host controller driver (see xhci_submit_root() in xhci.c).
         *
         * Note: this only supports driver model.
         */

        if (!usb_hub_is_root_hub(dev->dev) && usb_hub_is_superspeed(dev)) {
                struct usb_port_status *status = (struct usb_port_status *)data;
                u16 tmp = (status->wPortStatus) & USB_SS_PORT_STAT_MASK;

                if (status->wPortStatus & USB_SS_PORT_STAT_POWER)
                        tmp |= USB_PORT_STAT_POWER;
                if ((status->wPortStatus & USB_SS_PORT_STAT_SPEED) ==
                    USB_SS_PORT_STAT_SPEED_5GBPS)
                        tmp |= USB_PORT_STAT_SUPER_SPEED;

                status->wPortStatus = tmp;
        }
#endif

        return ret;
}


static void usb_hub_power_on(struct usb_hub_device *hub)
{
        int i;
        struct usb_device *dev;
        unsigned pgood_delay = hub->desc.bPwrOn2PwrGood * 2;
        const char *env;

        dev = hub->pusb_dev;

        debug("enabling power on all ports\n");
        for (i = 0; i < dev->maxchild; i++) {
                usb_set_port_feature(dev, i + 1, USB_PORT_FEAT_POWER);
                debug("port %d returns %lX\n", i + 1, dev->status);
        }

#ifdef CONFIG_SANDBOX
        /*
         * Don't set timeout / delay values here. This results
         * in these values still being reset to 0.
         */
        if (state_get_skip_delays())
                return;
#endif

        /*
         * Wait for power to become stable,
         * plus spec-defined max time for device to connect
         * but allow this time to be increased via env variable as some
         * devices break the spec and require longer warm-up times
         */
        env = getenv("usb_pgood_delay");
        if (env)
                pgood_delay = max(pgood_delay,
                                  (unsigned)simple_strtol(env, NULL, 0));
        debug("pgood_delay=%dms\n", pgood_delay);

        /*
         * Do a minimum delay of the larger value of 100ms or pgood_delay
         * so that the power can stablize before the devices are queried
         */
        hub->query_delay = get_timer(0) + max(100, (int)pgood_delay);

        /*
         * Record the power-on timeout here. The max. delay (timeout)
         * will be done based on this value in the USB port loop in
         * usb_hub_configure() later.
         */
        hub->connect_timeout = hub->query_delay + 1000;
        debug("devnum=%d poweron: query_delay=%d connect_timeout=%d\n",
              dev->devnum, max(100, (int)pgood_delay),
              max(100, (int)pgood_delay) + 1000);
}

#ifndef CONFIG_DM_USB
static struct usb_hub_device hub_dev[USB_MAX_HUB];
static int usb_hub_index;

void usb_hub_reset(void)
{
        usb_hub_index = 0;

        /* Zero out global hub_dev in case its re-used again */
        memset(hub_dev, 0, sizeof(hub_dev));
}

static struct usb_hub_device *usb_hub_allocate(void)
{
        if (usb_hub_index < USB_MAX_HUB)
                return &hub_dev[usb_hub_index++];

        printf("ERROR: USB_MAX_HUB (%d) reached\n", USB_MAX_HUB);
        return NULL;
}
#endif

#define MAX_TRIES 5

static inline char *portspeed(int portstatus)
{
        char *speed_str;

        switch (portstatus & USB_PORT_STAT_SPEED_MASK) {
        case USB_PORT_STAT_SUPER_SPEED:
                speed_str = "5 Gb/s";
                break;
        case USB_PORT_STAT_HIGH_SPEED:
                speed_str = "480 Mb/s";
                break;
        case USB_PORT_STAT_LOW_SPEED:
                speed_str = "1.5 Mb/s";
                break;
        default:
                speed_str = "12 Mb/s";
                break;
        }

        return speed_str;
}

/**
 * usb_hub_port_reset() - reset a port given its usb_device pointer
 *
 * Reset a hub port and see if a device is present on that port, providing
 * sufficient time for it to show itself. The port status is returned.
 *
 * @dev:        USB device to reset
 * @port:       Port number to reset (note ports are numbered from 0 here)
 * @portstat:   Returns port status
 */
static int usb_hub_port_reset(struct usb_device *dev, int port,
                              unsigned short *portstat)
{
        int err, tries;
        ALLOC_CACHE_ALIGN_BUFFER(struct usb_port_status, portsts, 1);
        unsigned short portstatus, portchange;
        int delay = HUB_SHORT_RESET_TIME; /* start with short reset delay */

#ifdef CONFIG_DM_USB
        debug("%s: resetting '%s' port %d...\n", __func__, dev->dev->name,
              port + 1);
#else
        debug("%s: resetting port %d...\n", __func__, port + 1);
#endif
        for (tries = 0; tries < MAX_TRIES; tries++) {
                err = usb_set_port_feature(dev, port + 1, USB_PORT_FEAT_RESET);
                if (err < 0)
                        return err;

                mdelay(delay);

                if (usb_get_port_status(dev, port + 1, portsts) < 0) {
                        debug("get_port_status failed status %lX\n",
                              dev->status);
                        return -1;
                }
                portstatus = le16_to_cpu(portsts->wPortStatus);
                portchange = le16_to_cpu(portsts->wPortChange);

                debug("portstatus %x, change %x, %s\n", portstatus, portchange,
                                                        portspeed(portstatus));

                debug("STAT_C_CONNECTION = %d STAT_CONNECTION = %d" \
                      "  USB_PORT_STAT_ENABLE %d\n",
                      (portchange & USB_PORT_STAT_C_CONNECTION) ? 1 : 0,
                      (portstatus & USB_PORT_STAT_CONNECTION) ? 1 : 0,
                      (portstatus & USB_PORT_STAT_ENABLE) ? 1 : 0);

                /*
                 * Perhaps we should check for the following here:
                 * - C_CONNECTION hasn't been set.
                 * - CONNECTION is still set.
                 *
                 * Doing so would ensure that the device is still connected
                 * to the bus, and hasn't been unplugged or replaced while the
                 * USB bus reset was going on.
                 *
                 * However, if we do that, then (at least) a San Disk Ultra
                 * USB 3.0 16GB device fails to reset on (at least) an NVIDIA
                 * Tegra Jetson TK1 board. For some reason, the device appears
                 * to briefly drop off the bus when this second bus reset is
                 * executed, yet if we retry this loop, it'll eventually come
                 * back after another reset or two.
                 */

                if (portstatus & USB_PORT_STAT_ENABLE)
                        break;

                /* Switch to long reset delay for the next round */
                delay = HUB_LONG_RESET_TIME;
        }

        if (tries == MAX_TRIES) {
                debug("Cannot enable port %i after %i retries, " \
                      "disabling port.\n", port + 1, MAX_TRIES);
                debug("Maybe the USB cable is bad?\n");
                return -1;
        }

        usb_clear_port_feature(dev, port + 1, USB_PORT_FEAT_C_RESET);
        *portstat = portstatus;
        return 0;
}

int usb_hub_port_connect_change(struct usb_device *dev, int port)
{
        ALLOC_CACHE_ALIGN_BUFFER(struct usb_port_status, portsts, 1);
        unsigned short portstatus;
        int ret, speed;

        /* Check status */
        ret = usb_get_port_status(dev, port + 1, portsts);
        if (ret < 0) {
                debug("get_port_status failed\n");
                return ret;
        }

        portstatus = le16_to_cpu(portsts->wPortStatus);
        debug("portstatus %x, change %x, %s\n",
              portstatus,
              le16_to_cpu(portsts->wPortChange),
              portspeed(portstatus));

        /* Clear the connection change status */
        usb_clear_port_feature(dev, port + 1, USB_PORT_FEAT_C_CONNECTION);

        /* Disconnect any existing devices under this port */
        if (((!(portstatus & USB_PORT_STAT_CONNECTION)) &&
             (!(portstatus & USB_PORT_STAT_ENABLE))) ||
            usb_device_has_child_on_port(dev, port)) {
                debug("usb_disconnect(&hub->children[port]);\n");
                /* Return now if nothing is connected */
                if (!(portstatus & USB_PORT_STAT_CONNECTION))
                        return -ENOTCONN;
        }

        /* Reset the port */
        ret = usb_hub_port_reset(dev, port, &portstatus);
        if (ret < 0) {
                if (ret != -ENXIO)
                        printf("cannot reset port %i!?\n", port + 1);
                return ret;
        }

        switch (portstatus & USB_PORT_STAT_SPEED_MASK) {
        case USB_PORT_STAT_SUPER_SPEED:
                speed = USB_SPEED_SUPER;
                break;
        case USB_PORT_STAT_HIGH_SPEED:
                speed = USB_SPEED_HIGH;
                break;
        case USB_PORT_STAT_LOW_SPEED:
                speed = USB_SPEED_LOW;
                break;
        default:
                speed = USB_SPEED_FULL;
                break;
        }

#ifdef CONFIG_DM_USB
        struct udevice *child;

        ret = usb_scan_device(dev->dev, port + 1, speed, &child);
#else
        struct usb_device *usb;

        ret = usb_alloc_new_device(dev->controller, &usb);
        if (ret) {
                printf("cannot create new device: ret=%d", ret);
                return ret;
        }

        dev->children[port] = usb;
        usb->speed = speed;
        usb->parent = dev;
        usb->portnr = port + 1;
        /* Run it through the hoops (find a driver, etc) */
        ret = usb_new_device(usb);
        if (ret < 0) {
                /* Woops, disable the port */
                usb_free_device(dev->controller);
                dev->children[port] = NULL;
        }
#endif
        if (ret < 0) {
                debug("hub: disabling port %d\n", port + 1);
                usb_clear_port_feature(dev, port + 1, USB_PORT_FEAT_ENABLE);
        }

        return ret;
}

static int usb_scan_port(struct usb_device_scan *usb_scan)
{
        ALLOC_CACHE_ALIGN_BUFFER(struct usb_port_status, portsts, 1);
        unsigned short portstatus;
        unsigned short portchange;
        struct usb_device *dev;
        struct usb_hub_device *hub;
        int ret = 0;
        int i;

        dev = usb_scan->dev;
        hub = usb_scan->hub;
        i = usb_scan->port;

        /*
         * Don't talk to the device before the query delay is expired.
         * This is needed for voltages to stabalize.
         */
        if (get_timer(0) < hub->query_delay)
                return 0;

        ret = usb_get_port_status(dev, i + 1, portsts);
        if (ret < 0) {
                debug("get_port_status failed\n");
                if (get_timer(0) >= hub->connect_timeout) {
                        debug("devnum=%d port=%d: timeout\n",
                              dev->devnum, i + 1);
                        /* Remove this device from scanning list */
                        list_del(&usb_scan->list);
                        free(usb_scan);
                        return 0;
                }
                return 0;
        }

        portstatus = le16_to_cpu(portsts->wPortStatus);
        portchange = le16_to_cpu(portsts->wPortChange);
        debug("Port %d Status %X Change %X\n", i + 1, portstatus, portchange);

        /*
         * No connection change happened, wait a bit more.
         *
         * For some situation, the hub reports no connection change but a
         * device is connected to the port (eg: CCS bit is set but CSC is not
         * in the PORTSC register of a root hub), ignore such case.
         */
        if (!(portchange & USB_PORT_STAT_C_CONNECTION) &&
            !(portstatus & USB_PORT_STAT_CONNECTION)) {
                if (get_timer(0) >= hub->connect_timeout) {
                        debug("devnum=%d port=%d: timeout\n",
                              dev->devnum, i + 1);
                        /* Remove this device from scanning list */
                        list_del(&usb_scan->list);
                        free(usb_scan);
                        return 0;
                }
                return 0;
        }

        /* A new USB device is ready at this point */
        debug("devnum=%d port=%d: USB dev found\n", dev->devnum, i + 1);

        usb_hub_port_connect_change(dev, i);

        if (portchange & USB_PORT_STAT_C_ENABLE) {
                debug("port %d enable change, status %x\n", i + 1, portstatus);
                usb_clear_port_feature(dev, i + 1, USB_PORT_FEAT_C_ENABLE);
                /*
                 * The following hack causes a ghost device problem
                 * to Faraday EHCI
                 */
#ifndef CONFIG_USB_EHCI_FARADAY
                /*
                 * EM interference sometimes causes bad shielded USB
                 * devices to be shutdown by the hub, this hack enables
                 * them again. Works at least with mouse driver
                 */
                if (!(portstatus & USB_PORT_STAT_ENABLE) &&
                    (portstatus & USB_PORT_STAT_CONNECTION) &&
                    usb_device_has_child_on_port(dev, i)) {
                        debug("already running port %i disabled by hub (EMI?), re-enabling...\n",
                              i + 1);
                        usb_hub_port_connect_change(dev, i);
                }
#endif
        }

        if (portstatus & USB_PORT_STAT_SUSPEND) {
                debug("port %d suspend change\n", i + 1);
                usb_clear_port_feature(dev, i + 1, USB_PORT_FEAT_SUSPEND);
        }

        if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
                debug("port %d over-current change\n", i + 1);
                usb_clear_port_feature(dev, i + 1,
                                       USB_PORT_FEAT_C_OVER_CURRENT);
                /* Only power-on this one port */
                usb_set_port_feature(dev, i + 1, USB_PORT_FEAT_POWER);
                hub->overcurrent_count[i]++;

                /*
                 * If the max-scan-count is not reached, return without removing
                 * the device from scan-list. This will re-issue a new scan.
                 */
                if (hub->overcurrent_count[i] <=
                    PORT_OVERCURRENT_MAX_SCAN_COUNT)
                        return 0;

                /* Otherwise the device will get removed */
                printf("Port %d over-current occurred %d times\n", i + 1,
                       hub->overcurrent_count[i]);
        }

        if (portchange & USB_PORT_STAT_C_RESET) {
                debug("port %d reset change\n", i + 1);
                usb_clear_port_feature(dev, i + 1, USB_PORT_FEAT_C_RESET);
        }

        /*
         * We're done with this device, so let's remove this device from
         * scanning list
         */
        list_del(&usb_scan->list);
        free(usb_scan);

        return 0;
}

static int usb_device_list_scan(void)
{
        struct usb_device_scan *usb_scan;
        struct usb_device_scan *tmp;
        static int running;
        int ret = 0;

        /* Only run this loop once for each controller */
        if (running)
                return 0;

        running = 1;

        while (1) {
                /* We're done, once the list is empty again */
                if (list_empty(&usb_scan_list))
                        goto out;

                list_for_each_entry_safe(usb_scan, tmp, &usb_scan_list, list) {
                        int ret;

                        /* Scan this port */
                        ret = usb_scan_port(usb_scan);
                        if (ret)
                                goto out;
                }
        }

out:
        /*
         * This USB controller has finished scanning all its connected
         * USB devices. Set "running" back to 0, so that other USB controllers
         * will scan their devices too.
         */
        running = 0;

        return ret;
}

static struct usb_hub_device *usb_get_hub_device(struct usb_device *dev)
{
        struct usb_hub_device *hub;

#ifndef CONFIG_DM_USB
        /* "allocate" Hub device */
        hub = usb_hub_allocate();
#else
        hub = dev_get_uclass_priv(dev->dev);
#endif

        return hub;
}

static int usb_hub_configure(struct usb_device *dev)
{
        int i, length;
        ALLOC_CACHE_ALIGN_BUFFER(unsigned char, buffer, USB_BUFSIZ);
        unsigned char *bitmap;
        short hubCharacteristics;
        struct usb_hub_descriptor *descriptor;
        struct usb_hub_device *hub;
        __maybe_unused struct usb_hub_status *hubsts;
        int ret;

        hub = usb_get_hub_device(dev);
        if (hub == NULL)
                return -ENOMEM;
        hub->pusb_dev = dev;

        /* Get the the hub descriptor */
        ret = usb_get_hub_descriptor(dev, buffer, 4);
        if (ret < 0) {
                debug("usb_hub_configure: failed to get hub " \
                      "descriptor, giving up %lX\n", dev->status);
                return ret;
        }
        descriptor = (struct usb_hub_descriptor *)buffer;

        length = min_t(int, descriptor->bLength,
                       sizeof(struct usb_hub_descriptor));

        ret = usb_get_hub_descriptor(dev, buffer, length);
        if (ret < 0) {
                debug("usb_hub_configure: failed to get hub " \
                      "descriptor 2nd giving up %lX\n", dev->status);
                return ret;
        }
        memcpy((unsigned char *)&hub->desc, buffer, length);
        /* adjust 16bit values */
        put_unaligned(le16_to_cpu(get_unaligned(
                        &descriptor->wHubCharacteristics)),
                        &hub->desc.wHubCharacteristics);
        /* set the bitmap */
        bitmap = (unsigned char *)&hub->desc.u.hs.DeviceRemovable[0];
        /* devices not removable by default */
        memset(bitmap, 0xff, (USB_MAXCHILDREN+1+7)/8);
        bitmap = (unsigned char *)&hub->desc.u.hs.PortPowerCtrlMask[0];
        memset(bitmap, 0xff, (USB_MAXCHILDREN+1+7)/8); /* PowerMask = 1B */

        for (i = 0; i < ((hub->desc.bNbrPorts + 1 + 7)/8); i++)
                hub->desc.u.hs.DeviceRemovable[i] =
                        descriptor->u.hs.DeviceRemovable[i];

        for (i = 0; i < ((hub->desc.bNbrPorts + 1 + 7)/8); i++)
                hub->desc.u.hs.PortPowerCtrlMask[i] =
                        descriptor->u.hs.PortPowerCtrlMask[i];

        dev->maxchild = descriptor->bNbrPorts;
        debug("%d ports detected\n", dev->maxchild);

        hubCharacteristics = get_unaligned(&hub->desc.wHubCharacteristics);
        switch (hubCharacteristics & HUB_CHAR_LPSM) {
        case 0x00:
                debug("ganged power switching\n");
                break;
        case 0x01:
                debug("individual port power switching\n");
                break;
        case 0x02:
        case 0x03:
                debug("unknown reserved power switching mode\n");
                break;
        }

        if (hubCharacteristics & HUB_CHAR_COMPOUND)
                debug("part of a compound device\n");
        else
                debug("standalone hub\n");

        switch (hubCharacteristics & HUB_CHAR_OCPM) {
        case 0x00:
                debug("global over-current protection\n");
                break;
        case 0x08:
                debug("individual port over-current protection\n");
                break;
        case 0x10:
        case 0x18:
                debug("no over-current protection\n");
                break;
        }

        debug("power on to power good time: %dms\n",
              descriptor->bPwrOn2PwrGood * 2);
        debug("hub controller current requirement: %dmA\n",
              descriptor->bHubContrCurrent);

        for (i = 0; i < dev->maxchild; i++)
                debug("port %d is%s removable\n", i + 1,
                      hub->desc.u.hs.DeviceRemovable[(i + 1) / 8] & \
                      (1 << ((i + 1) % 8)) ? " not" : "");

        if (sizeof(struct usb_hub_status) > USB_BUFSIZ) {
                debug("usb_hub_configure: failed to get Status - " \
                      "too long: %d\n", descriptor->bLength);
                return -EFBIG;
        }

        ret = usb_get_hub_status(dev, buffer);
        if (ret < 0) {
                debug("usb_hub_configure: failed to get Status %lX\n",
                      dev->status);
                return ret;
        }

#ifdef DEBUG
        hubsts = (struct usb_hub_status *)buffer;
#endif

        debug("get_hub_status returned status %X, change %X\n",
              le16_to_cpu(hubsts->wHubStatus),
              le16_to_cpu(hubsts->wHubChange));
        debug("local power source is %s\n",
              (le16_to_cpu(hubsts->wHubStatus) & HUB_STATUS_LOCAL_POWER) ? \
              "lost (inactive)" : "good");
        debug("%sover-current condition exists\n",
              (le16_to_cpu(hubsts->wHubStatus) & HUB_STATUS_OVERCURRENT) ? \
              "" : "no ");
        usb_hub_power_on(hub);

        /*
         * Reset any devices that may be in a bad state when applying
         * the power.  This is a __weak function.  Resetting of the devices
         * should occur in the board file of the device.
         */
        for (i = 0; i < dev->maxchild; i++)
                usb_hub_reset_devices(i + 1);

        /*
         * Only add the connected USB devices, including potential hubs,
         * to a scanning list. This list will get scanned and devices that
         * are detected (either via port connected or via port timeout)
         * will get removed from this list. Scanning of the devices on this
         * list will continue until all devices are removed.
         */
        for (i = 0; i < dev->maxchild; i++) {
                struct usb_device_scan *usb_scan;

                usb_scan = calloc(1, sizeof(*usb_scan));
                if (!usb_scan) {
                        printf("Can't allocate memory for USB device!\n");
                        return -ENOMEM;
                }
                usb_scan->dev = dev;
                usb_scan->hub = hub;
                usb_scan->port = i;
                list_add_tail(&usb_scan->list, &usb_scan_list);
        }

        /*
         * And now call the scanning code which loops over the generated list
         */
        ret = usb_device_list_scan();

        return ret;
}

static int usb_hub_check(struct usb_device *dev, int ifnum)
{
        struct usb_interface *iface;
        struct usb_endpoint_descriptor *ep = NULL;

        iface = &dev->config.if_desc[ifnum];
        /* Is it a hub? */
        if (iface->desc.bInterfaceClass != USB_CLASS_HUB)
                goto err;
        /* Some hubs have a subclass of 1, which AFAICT according to the */
        /*  specs is not defined, but it works */
        if ((iface->desc.bInterfaceSubClass != 0) &&
            (iface->desc.bInterfaceSubClass != 1))
                goto err;
        /* Multiple endpoints? What kind of mutant ninja-hub is this? */
        if (iface->desc.bNumEndpoints != 1)
                goto err;
        ep = &iface->ep_desc[0];
        /* Output endpoint? Curiousier and curiousier.. */
        if (!(ep->bEndpointAddress & USB_DIR_IN))
                goto err;
        /* If it's not an interrupt endpoint, we'd better punt! */
        if ((ep->bmAttributes & 3) != 3)
                goto err;
        /* We found a hub */
        debug("USB hub found\n");
        return 0;

err:
        debug("USB hub not found: bInterfaceClass=%d, bInterfaceSubClass=%d, bNumEndpoints=%d\n",
              iface->desc.bInterfaceClass, iface->desc.bInterfaceSubClass,
              iface->desc.bNumEndpoints);
        if (ep) {
                debug("   bEndpointAddress=%#x, bmAttributes=%d",
                      ep->bEndpointAddress, ep->bmAttributes);
        }

        return -ENOENT;
}

int usb_hub_probe(struct usb_device *dev, int ifnum)
{
        int ret;

        ret = usb_hub_check(dev, ifnum);
        if (ret)
                return 0;
        ret = usb_hub_configure(dev);
        return ret;
}

#ifdef CONFIG_DM_USB
int usb_hub_scan(struct udevice *hub)
{
        struct usb_device *udev = dev_get_parent_priv(hub);

        return usb_hub_configure(udev);
}

static int usb_hub_post_probe(struct udevice *dev)
{
        debug("%s\n", __func__);
        return usb_hub_scan(dev);
}

static const struct udevice_id usb_hub_ids[] = {
        { .compatible = "usb-hub" },
        { }
};

U_BOOT_DRIVER(usb_generic_hub) = {
        .name   = "usb_hub",
        .id     = UCLASS_USB_HUB,
        .of_match = usb_hub_ids,
        .flags  = DM_FLAG_ALLOC_PRIV_DMA,
};

UCLASS_DRIVER(usb_hub) = {
        .id             = UCLASS_USB_HUB,
        .name           = "usb_hub",
        .post_bind      = dm_scan_fdt_dev,
        .post_probe     = usb_hub_post_probe,
        .child_pre_probe        = usb_child_pre_probe,
        .per_child_auto_alloc_size = sizeof(struct usb_device),
        .per_child_platdata_auto_alloc_size = sizeof(struct usb_dev_platdata),
        .per_device_auto_alloc_size = sizeof(struct usb_hub_device),
};

static const struct usb_device_id hub_id_table[] = {
        {
                .match_flags = USB_DEVICE_ID_MATCH_DEV_CLASS,
                .bDeviceClass = USB_CLASS_HUB
        },
        { }     /* Terminating entry */
};

U_BOOT_USB_DEVICE(usb_generic_hub, hub_id_table);

#endif