]> git.ipfire.org Git - thirdparty/kernel/linux.git/commitdiff
dmaengine: switchtec-dma: Implement hardware initialization and cleanup
authorKelvin Cao <kelvin.cao@microchip.com>
Mon, 2 Mar 2026 21:04:18 +0000 (14:04 -0700)
committerVinod Koul <vkoul@kernel.org>
Mon, 9 Mar 2026 07:28:22 +0000 (08:28 +0100)
Initialize the hardware and create the dma channel queues.

Signed-off-by: Kelvin Cao <kelvin.cao@microchip.com>
Co-developed-by: George Ge <george.ge@microchip.com>
Signed-off-by: George Ge <george.ge@microchip.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Link: https://patch.msgid.link/20260302210419.3656-3-logang@deltatee.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
drivers/dma/switchtec_dma.c

index 2e722633310747b1c02a7da3afcf1fdfb96b029b..4c0dacc24608f568db100892aaaaf613afc90db4 100644 (file)
@@ -19,16 +19,976 @@ MODULE_DESCRIPTION("Switchtec PCIe Switch DMA Engine");
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Kelvin Cao");
 
+#define        SWITCHTEC_DMAC_CHAN_CTRL_OFFSET         0x1000
+#define        SWITCHTEC_DMAC_CHAN_CFG_STS_OFFSET      0x160000
+
+#define SWITCHTEC_DMA_CHAN_HW_REGS_SIZE                0x1000
+#define SWITCHTEC_DMA_CHAN_FW_REGS_SIZE                0x80
+
+#define SWITCHTEC_REG_CAP              0x80
+#define SWITCHTEC_REG_CHAN_CNT         0x84
+#define SWITCHTEC_REG_TAG_LIMIT                0x90
+#define SWITCHTEC_REG_CHAN_STS_VEC     0x94
+#define SWITCHTEC_REG_SE_BUF_CNT       0x98
+#define SWITCHTEC_REG_SE_BUF_BASE      0x9a
+
+#define SWITCHTEC_CHAN_CTRL_PAUSE      BIT(0)
+#define SWITCHTEC_CHAN_CTRL_HALT       BIT(1)
+#define SWITCHTEC_CHAN_CTRL_RESET      BIT(2)
+#define SWITCHTEC_CHAN_CTRL_ERR_PAUSE  BIT(3)
+
+#define SWITCHTEC_CHAN_STS_PAUSED      BIT(9)
+#define SWITCHTEC_CHAN_STS_HALTED      BIT(10)
+#define SWITCHTEC_CHAN_STS_PAUSED_MASK GENMASK(29, 13)
+
+#define SWITCHTEC_DMA_SQ_SIZE  SZ_32K
+#define SWITCHTEC_DMA_CQ_SIZE  SZ_32K
+
+#define SWITCHTEC_DMA_RING_SIZE        SZ_32K
+
+static const char * const channel_status_str[] = {
+       [13] = "received a VDM with length error status",
+       [14] = "received a VDM or Cpl with Unsupported Request error status",
+       [15] = "received a VDM or Cpl with Completion Abort error status",
+       [16] = "received a VDM with ECRC error status",
+       [17] = "received a VDM with EP error status",
+       [18] = "received a VDM with Reserved Cpl error status",
+       [19] = "received only part of split SE CplD",
+       [20] = "the ISP_DMAC detected a Completion Time Out",
+       [21] = "received a Cpl with Unsupported Request status",
+       [22] = "received a Cpl with Completion Abort status",
+       [23] = "received a Cpl with a reserved status",
+       [24] = "received a TLP with ECRC error status in its metadata",
+       [25] = "received a TLP with the EP bit set in the header",
+       [26] = "the ISP_DMAC tried to process a SE with an invalid Connection ID",
+       [27] = "the ISP_DMAC tried to process a SE with an invalid Remote Host interrupt",
+       [28] = "a reserved opcode was detected in an SE",
+       [29] = "received a SE Cpl with error status",
+};
+
+struct chan_hw_regs {
+       u16 cq_head;
+       u16 rsvd1;
+       u16 sq_tail;
+       u16 rsvd2;
+       u8 ctrl;
+       u8 rsvd3[3];
+       u16 status;
+       u16 rsvd4;
+};
+
+#define PERF_BURST_SCALE_MASK  GENMASK_U32(3,   2)
+#define PERF_MRRS_MASK         GENMASK_U32(6,   4)
+#define PERF_INTERVAL_MASK     GENMASK_U32(10,  8)
+#define PERF_BURST_SIZE_MASK   GENMASK_U32(14, 12)
+#define PERF_ARB_WEIGHT_MASK   GENMASK_U32(31, 24)
+
+#define SE_BUF_BASE_MASK       GENMASK_U32(10,  2)
+#define SE_BUF_LEN_MASK                GENMASK_U32(20, 12)
+#define SE_THRESH_MASK         GENMASK_U32(31, 23)
+
+#define SWITCHTEC_CHAN_ENABLE  BIT(1)
+
+struct chan_fw_regs {
+       u32 valid_en_se;
+       u32 cq_base_lo;
+       u32 cq_base_hi;
+       u16 cq_size;
+       u16 rsvd1;
+       u32 sq_base_lo;
+       u32 sq_base_hi;
+       u16 sq_size;
+       u16 rsvd2;
+       u32 int_vec;
+       u32 perf_cfg;
+       u32 rsvd3;
+       u32 perf_latency_selector;
+       u32 perf_fetched_se_cnt_lo;
+       u32 perf_fetched_se_cnt_hi;
+       u32 perf_byte_cnt_lo;
+       u32 perf_byte_cnt_hi;
+       u32 rsvd4;
+       u16 perf_se_pending;
+       u16 perf_se_buf_empty;
+       u32 perf_chan_idle;
+       u32 perf_lat_max;
+       u32 perf_lat_min;
+       u32 perf_lat_last;
+       u16 sq_current;
+       u16 sq_phase;
+       u16 cq_current;
+       u16 cq_phase;
+};
+
+struct switchtec_dma_chan {
+       struct switchtec_dma_dev *swdma_dev;
+       struct dma_chan dma_chan;
+       struct chan_hw_regs __iomem *mmio_chan_hw;
+       struct chan_fw_regs __iomem *mmio_chan_fw;
+
+       /* Serialize hardware control register access */
+       spinlock_t hw_ctrl_lock;
+
+       struct tasklet_struct desc_task;
+
+       /* Serialize descriptor preparation */
+       spinlock_t submit_lock;
+       bool ring_active;
+       int cid;
+
+       /* Serialize completion processing */
+       spinlock_t complete_lock;
+       bool comp_ring_active;
+
+       /* channel index and irq */
+       int index;
+       int irq;
+
+       /*
+        * In driver context, head is advanced by producer while
+        * tail is advanced by consumer.
+        */
+
+       /* the head and tail for both desc_ring and hw_sq */
+       int head;
+       int tail;
+       int phase_tag;
+       struct switchtec_dma_hw_se_desc *hw_sq;
+       dma_addr_t dma_addr_sq;
+
+       /* the tail for hw_cq */
+       int cq_tail;
+       struct switchtec_dma_hw_ce *hw_cq;
+       dma_addr_t dma_addr_cq;
+
+       struct list_head list;
+
+       struct switchtec_dma_desc *desc_ring[SWITCHTEC_DMA_RING_SIZE];
+};
+
 struct switchtec_dma_dev {
        struct dma_device dma_dev;
        struct pci_dev __rcu *pdev;
        void __iomem *bar;
+
+       struct switchtec_dma_chan **swdma_chans;
+       int chan_cnt;
+       int chan_status_irq;
+};
+
+enum chan_op {
+       ENABLE_CHAN,
+       DISABLE_CHAN,
+};
+
+enum switchtec_dma_opcode {
+       SWITCHTEC_DMA_OPC_MEMCPY = 0,
+       SWITCHTEC_DMA_OPC_RDIMM = 0x1,
+       SWITCHTEC_DMA_OPC_WRIMM = 0x2,
+       SWITCHTEC_DMA_OPC_RHI = 0x6,
+       SWITCHTEC_DMA_OPC_NOP = 0x7,
+};
+
+struct switchtec_dma_hw_se_desc {
+       u8 opc;
+       u8 ctrl;
+       __le16 tlp_setting;
+       __le16 rsvd1;
+       __le16 cid;
+       __le32 byte_cnt;
+       __le32 addr_lo; /* SADDR_LO/WIADDR_LO */
+       __le32 addr_hi; /* SADDR_HI/WIADDR_HI */
+       __le32 daddr_lo;
+       __le32 daddr_hi;
+       __le16 dfid;
+       __le16 sfid;
+};
+
+#define SWITCHTEC_CE_SC_LEN_ERR                BIT(0)
+#define SWITCHTEC_CE_SC_UR             BIT(1)
+#define SWITCHTEC_CE_SC_CA             BIT(2)
+#define SWITCHTEC_CE_SC_RSVD_CPL       BIT(3)
+#define SWITCHTEC_CE_SC_ECRC_ERR       BIT(4)
+#define SWITCHTEC_CE_SC_EP_SET         BIT(5)
+#define SWITCHTEC_CE_SC_D_RD_CTO       BIT(8)
+#define SWITCHTEC_CE_SC_D_RIMM_UR      BIT(9)
+#define SWITCHTEC_CE_SC_D_RIMM_CA      BIT(10)
+#define SWITCHTEC_CE_SC_D_RIMM_RSVD_CPL        BIT(11)
+#define SWITCHTEC_CE_SC_D_ECRC         BIT(12)
+#define SWITCHTEC_CE_SC_D_EP_SET       BIT(13)
+#define SWITCHTEC_CE_SC_D_BAD_CONNID   BIT(14)
+#define SWITCHTEC_CE_SC_D_BAD_RHI_ADDR BIT(15)
+#define SWITCHTEC_CE_SC_D_INVD_CMD     BIT(16)
+#define SWITCHTEC_CE_SC_MASK           GENMASK(16, 0)
+
+struct switchtec_dma_hw_ce {
+       __le32 rdimm_cpl_dw0;
+       __le32 rdimm_cpl_dw1;
+       __le32 rsvd1;
+       __le32 cpl_byte_cnt;
+       __le16 sq_head;
+       __le16 rsvd2;
+       __le32 rsvd3;
+       __le32 sts_code;
+       __le16 cid;
+       __le16 phase_tag;
+};
+
+struct switchtec_dma_desc {
+       struct dma_async_tx_descriptor txd;
+       struct switchtec_dma_hw_se_desc *hw;
+       u32 orig_size;
+       bool completed;
 };
 
+static int wait_for_chan_status(struct chan_hw_regs __iomem *chan_hw, u32 mask,
+                               bool set)
+{
+       u32 status;
+
+       return readl_poll_timeout_atomic(&chan_hw->status, status,
+                                        (set && (status & mask)) ||
+                                        (!set && !(status & mask)),
+                                        10, 100 * USEC_PER_MSEC);
+}
+
+static int halt_channel(struct switchtec_dma_chan *swdma_chan)
+{
+       struct chan_hw_regs __iomem *chan_hw = swdma_chan->mmio_chan_hw;
+       struct pci_dev *pdev;
+       int ret;
+
+       rcu_read_lock();
+       pdev = rcu_dereference(swdma_chan->swdma_dev->pdev);
+       if (!pdev) {
+               ret = -ENODEV;
+               goto unlock_and_exit;
+       }
+
+       spin_lock(&swdma_chan->hw_ctrl_lock);
+       writeb(SWITCHTEC_CHAN_CTRL_HALT, &chan_hw->ctrl);
+       ret = wait_for_chan_status(chan_hw, SWITCHTEC_CHAN_STS_HALTED, true);
+       spin_unlock(&swdma_chan->hw_ctrl_lock);
+
+unlock_and_exit:
+       rcu_read_unlock();
+       return ret;
+}
+
+static int unhalt_channel(struct switchtec_dma_chan *swdma_chan)
+{
+       struct chan_hw_regs __iomem *chan_hw = swdma_chan->mmio_chan_hw;
+       struct pci_dev *pdev;
+       u8 ctrl;
+       int ret;
+
+       rcu_read_lock();
+       pdev = rcu_dereference(swdma_chan->swdma_dev->pdev);
+       if (!pdev) {
+               ret = -ENODEV;
+               goto unlock_and_exit;
+       }
+
+       spin_lock(&swdma_chan->hw_ctrl_lock);
+       ctrl = readb(&chan_hw->ctrl);
+       ctrl &= ~SWITCHTEC_CHAN_CTRL_HALT;
+       writeb(ctrl, &chan_hw->ctrl);
+       ret = wait_for_chan_status(chan_hw, SWITCHTEC_CHAN_STS_HALTED, false);
+       spin_unlock(&swdma_chan->hw_ctrl_lock);
+
+unlock_and_exit:
+       rcu_read_unlock();
+       return ret;
+}
+
+static void flush_pci_write(struct chan_hw_regs __iomem *chan_hw)
+{
+       readl(&chan_hw->cq_head);
+}
+
+static int reset_channel(struct switchtec_dma_chan *swdma_chan)
+{
+       struct chan_hw_regs __iomem *chan_hw = swdma_chan->mmio_chan_hw;
+       struct pci_dev *pdev;
+
+       rcu_read_lock();
+       pdev = rcu_dereference(swdma_chan->swdma_dev->pdev);
+       if (!pdev) {
+               rcu_read_unlock();
+               return -ENODEV;
+       }
+
+       spin_lock(&swdma_chan->hw_ctrl_lock);
+       writel(SWITCHTEC_CHAN_CTRL_RESET | SWITCHTEC_CHAN_CTRL_ERR_PAUSE,
+              &chan_hw->ctrl);
+       flush_pci_write(chan_hw);
+
+       udelay(1000);
+
+       writel(SWITCHTEC_CHAN_CTRL_ERR_PAUSE, &chan_hw->ctrl);
+       spin_unlock(&swdma_chan->hw_ctrl_lock);
+       flush_pci_write(chan_hw);
+
+       rcu_read_unlock();
+       return 0;
+}
+
+static int pause_reset_channel(struct switchtec_dma_chan *swdma_chan)
+{
+       struct chan_hw_regs __iomem *chan_hw = swdma_chan->mmio_chan_hw;
+       struct pci_dev *pdev;
+
+       rcu_read_lock();
+       pdev = rcu_dereference(swdma_chan->swdma_dev->pdev);
+       if (!pdev) {
+               rcu_read_unlock();
+               return -ENODEV;
+       }
+
+       spin_lock(&swdma_chan->hw_ctrl_lock);
+       writeb(SWITCHTEC_CHAN_CTRL_PAUSE, &chan_hw->ctrl);
+       spin_unlock(&swdma_chan->hw_ctrl_lock);
+
+       flush_pci_write(chan_hw);
+
+       rcu_read_unlock();
+
+       /* wait 60ms to ensure no pending CEs */
+       mdelay(60);
+
+       return reset_channel(swdma_chan);
+}
+
+static int channel_op(struct switchtec_dma_chan *swdma_chan, int op)
+{
+       struct chan_fw_regs __iomem *chan_fw = swdma_chan->mmio_chan_fw;
+       struct pci_dev *pdev;
+       u32 valid_en_se;
+
+       rcu_read_lock();
+       pdev = rcu_dereference(swdma_chan->swdma_dev->pdev);
+       if (!pdev) {
+               rcu_read_unlock();
+               return -ENODEV;
+       }
+
+       valid_en_se = readl(&chan_fw->valid_en_se);
+       if (op == ENABLE_CHAN)
+               valid_en_se |= SWITCHTEC_CHAN_ENABLE;
+       else
+               valid_en_se &= ~SWITCHTEC_CHAN_ENABLE;
+
+       writel(valid_en_se, &chan_fw->valid_en_se);
+
+       rcu_read_unlock();
+       return 0;
+}
+
+static int enable_channel(struct switchtec_dma_chan *swdma_chan)
+{
+       return channel_op(swdma_chan, ENABLE_CHAN);
+}
+
+static int disable_channel(struct switchtec_dma_chan *swdma_chan)
+{
+       return channel_op(swdma_chan, DISABLE_CHAN);
+}
+
+static void
+switchtec_dma_cleanup_completed(struct switchtec_dma_chan *swdma_chan)
+{
+       struct device *chan_dev = &swdma_chan->dma_chan.dev->device;
+       struct switchtec_dma_desc *desc;
+       struct switchtec_dma_hw_ce *ce;
+       struct dmaengine_result res;
+       int tail, cid, se_idx, i;
+       __le16 phase_tag;
+       u32 sts_code;
+       __le32 *p;
+
+       do {
+               spin_lock_bh(&swdma_chan->complete_lock);
+               if (!swdma_chan->comp_ring_active) {
+                       spin_unlock_bh(&swdma_chan->complete_lock);
+                       break;
+               }
+
+               ce = &swdma_chan->hw_cq[swdma_chan->cq_tail];
+               /*
+                * phase_tag is updated by hardware, ensure the value is
+                * not from the cache
+                */
+               phase_tag = smp_load_acquire(&ce->phase_tag);
+               if (le16_to_cpu(phase_tag) == swdma_chan->phase_tag) {
+                       spin_unlock_bh(&swdma_chan->complete_lock);
+                       break;
+               }
+
+               cid = le16_to_cpu(ce->cid);
+               se_idx = cid & (SWITCHTEC_DMA_SQ_SIZE - 1);
+               desc = swdma_chan->desc_ring[se_idx];
+
+               tail = swdma_chan->tail;
+
+               res.residue = desc->orig_size - le32_to_cpu(ce->cpl_byte_cnt);
+
+               sts_code = le32_to_cpu(ce->sts_code);
+
+               if (!(sts_code & SWITCHTEC_CE_SC_MASK)) {
+                       res.result = DMA_TRANS_NOERROR;
+               } else {
+                       if (sts_code & SWITCHTEC_CE_SC_D_RD_CTO)
+                               res.result = DMA_TRANS_READ_FAILED;
+                       else
+                               res.result = DMA_TRANS_WRITE_FAILED;
+
+                       dev_err(chan_dev, "CID 0x%04x failed, SC 0x%08x\n", cid,
+                               (u32)(sts_code & SWITCHTEC_CE_SC_MASK));
+
+                       p = (__le32 *)ce;
+                       for (i = 0; i < sizeof(*ce) / 4; i++) {
+                               dev_err(chan_dev, "CE DW%d: 0x%08x\n", i,
+                                       le32_to_cpu(*p));
+                               p++;
+                       }
+               }
+
+               desc->completed = true;
+
+               swdma_chan->cq_tail++;
+               swdma_chan->cq_tail &= SWITCHTEC_DMA_CQ_SIZE - 1;
+
+               rcu_read_lock();
+               if (!rcu_dereference(swdma_chan->swdma_dev->pdev)) {
+                       rcu_read_unlock();
+                       spin_unlock_bh(&swdma_chan->complete_lock);
+                       return;
+               }
+               writew(swdma_chan->cq_tail, &swdma_chan->mmio_chan_hw->cq_head);
+               rcu_read_unlock();
+
+               if (swdma_chan->cq_tail == 0)
+                       swdma_chan->phase_tag = !swdma_chan->phase_tag;
+
+               /*  Out of order CE */
+               if (se_idx != tail) {
+                       spin_unlock_bh(&swdma_chan->complete_lock);
+                       continue;
+               }
+
+               do {
+                       dma_cookie_complete(&desc->txd);
+                       dma_descriptor_unmap(&desc->txd);
+                       dmaengine_desc_get_callback_invoke(&desc->txd, &res);
+                       desc->txd.callback = NULL;
+                       desc->txd.callback_result = NULL;
+                       desc->completed = false;
+
+                       tail++;
+                       tail &= SWITCHTEC_DMA_SQ_SIZE - 1;
+
+                       /*
+                        * Ensure the desc updates are visible before updating
+                        * the tail index
+                        */
+                       smp_store_release(&swdma_chan->tail, tail);
+                       desc = swdma_chan->desc_ring[swdma_chan->tail];
+                       if (!desc->completed)
+                               break;
+               } while (CIRC_CNT(READ_ONCE(swdma_chan->head), swdma_chan->tail,
+                                 SWITCHTEC_DMA_SQ_SIZE));
+
+               spin_unlock_bh(&swdma_chan->complete_lock);
+       } while (1);
+}
+
+static void
+switchtec_dma_abort_desc(struct switchtec_dma_chan *swdma_chan, int force)
+{
+       struct switchtec_dma_desc *desc;
+       struct dmaengine_result res;
+
+       if (!force)
+               switchtec_dma_cleanup_completed(swdma_chan);
+
+       spin_lock_bh(&swdma_chan->complete_lock);
+
+       while (CIRC_CNT(swdma_chan->head, swdma_chan->tail,
+                       SWITCHTEC_DMA_SQ_SIZE) >= 1) {
+               desc = swdma_chan->desc_ring[swdma_chan->tail];
+
+               res.residue = desc->orig_size;
+               res.result = DMA_TRANS_ABORTED;
+
+               dma_cookie_complete(&desc->txd);
+               dma_descriptor_unmap(&desc->txd);
+               if (!force)
+                       dmaengine_desc_get_callback_invoke(&desc->txd, &res);
+               desc->txd.callback = NULL;
+               desc->txd.callback_result = NULL;
+
+               swdma_chan->tail++;
+               swdma_chan->tail &= SWITCHTEC_DMA_SQ_SIZE - 1;
+       }
+
+       spin_unlock_bh(&swdma_chan->complete_lock);
+}
+
+static void switchtec_dma_chan_stop(struct switchtec_dma_chan *swdma_chan)
+{
+       int rc;
+
+       rc = halt_channel(swdma_chan);
+       if (rc)
+               return;
+
+       rcu_read_lock();
+       if (!rcu_dereference(swdma_chan->swdma_dev->pdev)) {
+               rcu_read_unlock();
+               return;
+       }
+
+       writel(0, &swdma_chan->mmio_chan_fw->sq_base_lo);
+       writel(0, &swdma_chan->mmio_chan_fw->sq_base_hi);
+       writel(0, &swdma_chan->mmio_chan_fw->cq_base_lo);
+       writel(0, &swdma_chan->mmio_chan_fw->cq_base_hi);
+
+       rcu_read_unlock();
+}
+
+static int switchtec_dma_terminate_all(struct dma_chan *chan)
+{
+       struct switchtec_dma_chan *swdma_chan =
+               container_of(chan, struct switchtec_dma_chan, dma_chan);
+
+       spin_lock_bh(&swdma_chan->complete_lock);
+       swdma_chan->comp_ring_active = false;
+       spin_unlock_bh(&swdma_chan->complete_lock);
+
+       return pause_reset_channel(swdma_chan);
+}
+
+static void switchtec_dma_synchronize(struct dma_chan *chan)
+{
+       struct switchtec_dma_chan *swdma_chan =
+               container_of(chan, struct switchtec_dma_chan, dma_chan);
+
+       int rc;
+
+       switchtec_dma_abort_desc(swdma_chan, 1);
+
+       rc = enable_channel(swdma_chan);
+       if (rc)
+               return;
+
+       rc = reset_channel(swdma_chan);
+       if (rc)
+               return;
+
+       rc = unhalt_channel(swdma_chan);
+       if (rc)
+               return;
+
+       spin_lock_bh(&swdma_chan->submit_lock);
+       swdma_chan->head = 0;
+       spin_unlock_bh(&swdma_chan->submit_lock);
+
+       spin_lock_bh(&swdma_chan->complete_lock);
+       swdma_chan->comp_ring_active = true;
+       swdma_chan->phase_tag = 0;
+       swdma_chan->tail = 0;
+       swdma_chan->cq_tail = 0;
+       swdma_chan->cid = 0;
+       dma_cookie_init(chan);
+       spin_unlock_bh(&swdma_chan->complete_lock);
+}
+
+static void switchtec_dma_desc_task(unsigned long data)
+{
+       struct switchtec_dma_chan *swdma_chan = (void *)data;
+
+       switchtec_dma_cleanup_completed(swdma_chan);
+}
+
+static irqreturn_t switchtec_dma_isr(int irq, void *chan)
+{
+       struct switchtec_dma_chan *swdma_chan = chan;
+
+       if (swdma_chan->comp_ring_active)
+               tasklet_schedule(&swdma_chan->desc_task);
+
+       return IRQ_HANDLED;
+}
+
+static irqreturn_t switchtec_dma_chan_status_isr(int irq, void *dma)
+{
+       struct switchtec_dma_dev *swdma_dev = dma;
+       struct dma_device *dma_dev = &swdma_dev->dma_dev;
+       struct switchtec_dma_chan *swdma_chan;
+       struct chan_hw_regs __iomem *chan_hw;
+       struct device *chan_dev;
+       struct dma_chan *chan;
+       u32 chan_status;
+       int bit;
+
+       list_for_each_entry(chan, &dma_dev->channels, device_node) {
+               swdma_chan = container_of(chan, struct switchtec_dma_chan,
+                                         dma_chan);
+               chan_dev = &swdma_chan->dma_chan.dev->device;
+               chan_hw = swdma_chan->mmio_chan_hw;
+
+               rcu_read_lock();
+               if (!rcu_dereference(swdma_dev->pdev)) {
+                       rcu_read_unlock();
+                       goto out;
+               }
+
+               chan_status = readl(&chan_hw->status);
+               chan_status &= SWITCHTEC_CHAN_STS_PAUSED_MASK;
+               rcu_read_unlock();
+
+               bit = ffs(chan_status);
+               if (!bit)
+                       dev_dbg(chan_dev, "No pause bit set.\n");
+               else
+                       dev_err(chan_dev, "Paused, %s\n",
+                               channel_status_str[bit - 1]);
+       }
+
+out:
+       return IRQ_HANDLED;
+}
+
+static void switchtec_dma_free_desc(struct switchtec_dma_chan *swdma_chan)
+{
+       struct switchtec_dma_dev *swdma_dev = swdma_chan->swdma_dev;
+       size_t size;
+       int i;
+
+       size = SWITCHTEC_DMA_SQ_SIZE * sizeof(*swdma_chan->hw_sq);
+       if (swdma_chan->hw_sq)
+               dma_free_coherent(swdma_dev->dma_dev.dev, size,
+                                 swdma_chan->hw_sq, swdma_chan->dma_addr_sq);
+
+       size = SWITCHTEC_DMA_CQ_SIZE * sizeof(*swdma_chan->hw_cq);
+       if (swdma_chan->hw_cq)
+               dma_free_coherent(swdma_dev->dma_dev.dev, size,
+                                 swdma_chan->hw_cq, swdma_chan->dma_addr_cq);
+
+       for (i = 0; i < SWITCHTEC_DMA_RING_SIZE; i++)
+               kfree(swdma_chan->desc_ring[i]);
+}
+
+static int switchtec_dma_alloc_desc(struct switchtec_dma_chan *swdma_chan)
+{
+       struct switchtec_dma_dev *swdma_dev = swdma_chan->swdma_dev;
+       struct chan_fw_regs __iomem *chan_fw = swdma_chan->mmio_chan_fw;
+       struct switchtec_dma_desc *desc;
+       struct pci_dev *pdev;
+       size_t size;
+       int rc, i;
+
+       swdma_chan->head = 0;
+       swdma_chan->tail = 0;
+       swdma_chan->cq_tail = 0;
+
+       size = SWITCHTEC_DMA_SQ_SIZE * sizeof(*swdma_chan->hw_sq);
+       swdma_chan->hw_sq = dma_alloc_coherent(swdma_dev->dma_dev.dev, size,
+                                              &swdma_chan->dma_addr_sq,
+                                              GFP_NOWAIT);
+       if (!swdma_chan->hw_sq) {
+               rc = -ENOMEM;
+               goto free_and_exit;
+       }
+
+       size = SWITCHTEC_DMA_CQ_SIZE * sizeof(*swdma_chan->hw_cq);
+       swdma_chan->hw_cq = dma_alloc_coherent(swdma_dev->dma_dev.dev, size,
+                                              &swdma_chan->dma_addr_cq,
+                                              GFP_NOWAIT);
+       if (!swdma_chan->hw_cq) {
+               rc = -ENOMEM;
+               goto free_and_exit;
+       }
+
+       /* reset host phase tag */
+       swdma_chan->phase_tag = 0;
+
+       for (i = 0; i < SWITCHTEC_DMA_RING_SIZE; i++) {
+               desc = kzalloc_obj(*desc, GFP_NOWAIT);
+               if (!desc) {
+                       rc = -ENOMEM;
+                       goto free_and_exit;
+               }
+
+               dma_async_tx_descriptor_init(&desc->txd, &swdma_chan->dma_chan);
+               desc->hw = &swdma_chan->hw_sq[i];
+               desc->completed = true;
+
+               swdma_chan->desc_ring[i] = desc;
+       }
+
+       rcu_read_lock();
+       pdev = rcu_dereference(swdma_dev->pdev);
+       if (!pdev) {
+               rcu_read_unlock();
+               rc = -ENODEV;
+               goto free_and_exit;
+       }
+
+       /* set sq/cq */
+       writel(lower_32_bits(swdma_chan->dma_addr_sq), &chan_fw->sq_base_lo);
+       writel(upper_32_bits(swdma_chan->dma_addr_sq), &chan_fw->sq_base_hi);
+       writel(lower_32_bits(swdma_chan->dma_addr_cq), &chan_fw->cq_base_lo);
+       writel(upper_32_bits(swdma_chan->dma_addr_cq), &chan_fw->cq_base_hi);
+
+       writew(SWITCHTEC_DMA_SQ_SIZE, &swdma_chan->mmio_chan_fw->sq_size);
+       writew(SWITCHTEC_DMA_CQ_SIZE, &swdma_chan->mmio_chan_fw->cq_size);
+
+       rcu_read_unlock();
+       return 0;
+
+free_and_exit:
+       switchtec_dma_free_desc(swdma_chan);
+       return rc;
+}
+
+static int switchtec_dma_alloc_chan_resources(struct dma_chan *chan)
+{
+       struct switchtec_dma_chan *swdma_chan =
+               container_of(chan, struct switchtec_dma_chan, dma_chan);
+       struct switchtec_dma_dev *swdma_dev = swdma_chan->swdma_dev;
+       u32 perf_cfg;
+       int rc;
+
+       rc = switchtec_dma_alloc_desc(swdma_chan);
+       if (rc)
+               return rc;
+
+       rc = enable_channel(swdma_chan);
+       if (rc)
+               return rc;
+
+       rc = reset_channel(swdma_chan);
+       if (rc)
+               return rc;
+
+       rc = unhalt_channel(swdma_chan);
+       if (rc)
+               return rc;
+
+       swdma_chan->ring_active = true;
+       swdma_chan->comp_ring_active = true;
+       swdma_chan->cid = 0;
+
+       dma_cookie_init(chan);
+
+       rcu_read_lock();
+       if (!rcu_dereference(swdma_dev->pdev)) {
+               rcu_read_unlock();
+               return -ENODEV;
+       }
+
+       perf_cfg = readl(&swdma_chan->mmio_chan_fw->perf_cfg);
+       rcu_read_unlock();
+
+       dev_dbg(&chan->dev->device, "Burst Size:  0x%x\n",
+               FIELD_GET(PERF_BURST_SIZE_MASK, perf_cfg));
+
+       dev_dbg(&chan->dev->device, "Burst Scale: 0x%x\n",
+               FIELD_GET(PERF_BURST_SCALE_MASK, perf_cfg));
+
+       dev_dbg(&chan->dev->device, "Interval:    0x%x\n",
+               FIELD_GET(PERF_INTERVAL_MASK, perf_cfg));
+
+       dev_dbg(&chan->dev->device, "Arb Weight:  0x%x\n",
+               FIELD_GET(PERF_ARB_WEIGHT_MASK, perf_cfg));
+
+       dev_dbg(&chan->dev->device, "MRRS:        0x%x\n",
+               FIELD_GET(PERF_MRRS_MASK, perf_cfg));
+
+       return SWITCHTEC_DMA_SQ_SIZE;
+}
+
+static void switchtec_dma_free_chan_resources(struct dma_chan *chan)
+{
+       struct switchtec_dma_chan *swdma_chan =
+               container_of(chan, struct switchtec_dma_chan, dma_chan);
+
+       spin_lock_bh(&swdma_chan->submit_lock);
+       swdma_chan->ring_active = false;
+       spin_unlock_bh(&swdma_chan->submit_lock);
+
+       spin_lock_bh(&swdma_chan->complete_lock);
+       swdma_chan->comp_ring_active = false;
+       spin_unlock_bh(&swdma_chan->complete_lock);
+
+       switchtec_dma_chan_stop(swdma_chan);
+       switchtec_dma_abort_desc(swdma_chan, 0);
+       switchtec_dma_free_desc(swdma_chan);
+
+       disable_channel(swdma_chan);
+}
+
+static int switchtec_dma_chan_init(struct switchtec_dma_dev *swdma_dev,
+                                  struct pci_dev *pdev, int i)
+{
+       struct dma_device *dma = &swdma_dev->dma_dev;
+       struct switchtec_dma_chan *swdma_chan;
+       u32 valid_en_se, thresh;
+       int se_buf_len, irq, rc;
+       struct dma_chan *chan;
+
+       swdma_chan = kzalloc_obj(*swdma_chan, GFP_KERNEL);
+       if (!swdma_chan)
+               return -ENOMEM;
+
+       swdma_chan->phase_tag = 0;
+       swdma_chan->index = i;
+       swdma_chan->swdma_dev = swdma_dev;
+
+       spin_lock_init(&swdma_chan->hw_ctrl_lock);
+       spin_lock_init(&swdma_chan->submit_lock);
+       spin_lock_init(&swdma_chan->complete_lock);
+       tasklet_init(&swdma_chan->desc_task, switchtec_dma_desc_task,
+                    (unsigned long)swdma_chan);
+
+       swdma_chan->mmio_chan_fw =
+               swdma_dev->bar + SWITCHTEC_DMAC_CHAN_CFG_STS_OFFSET +
+               i * SWITCHTEC_DMA_CHAN_FW_REGS_SIZE;
+       swdma_chan->mmio_chan_hw =
+               swdma_dev->bar + SWITCHTEC_DMAC_CHAN_CTRL_OFFSET +
+               i * SWITCHTEC_DMA_CHAN_HW_REGS_SIZE;
+
+       swdma_dev->swdma_chans[i] = swdma_chan;
+
+       rc = pause_reset_channel(swdma_chan);
+       if (rc)
+               goto free_and_exit;
+
+       /* init perf tuner */
+       writel(FIELD_PREP(PERF_BURST_SCALE_MASK, 1) |
+              FIELD_PREP(PERF_MRRS_MASK, 3) |
+              FIELD_PREP(PERF_BURST_SIZE_MASK, 6) |
+              FIELD_PREP(PERF_ARB_WEIGHT_MASK, 1),
+              &swdma_chan->mmio_chan_fw->perf_cfg);
+
+       valid_en_se = readl(&swdma_chan->mmio_chan_fw->valid_en_se);
+
+       dev_dbg(&pdev->dev, "Channel %d: SE buffer base %d\n", i,
+               FIELD_GET(SE_BUF_BASE_MASK, valid_en_se));
+
+       se_buf_len = FIELD_GET(SE_BUF_LEN_MASK, valid_en_se);
+       dev_dbg(&pdev->dev, "Channel %d: SE buffer count %d\n", i, se_buf_len);
+
+       thresh = se_buf_len / 2;
+       valid_en_se |= FIELD_GET(SE_THRESH_MASK, thresh);
+       writel(valid_en_se, &swdma_chan->mmio_chan_fw->valid_en_se);
+
+       /* request irqs */
+       irq = readl(&swdma_chan->mmio_chan_fw->int_vec);
+       dev_dbg(&pdev->dev, "Channel %d: CE irq vector %d\n", i, irq);
+
+       rc = pci_request_irq(pdev, irq, switchtec_dma_isr, NULL, swdma_chan,
+                            KBUILD_MODNAME);
+       if (rc)
+               goto free_and_exit;
+
+       swdma_chan->irq = irq;
+
+       chan = &swdma_chan->dma_chan;
+       chan->device = dma;
+       dma_cookie_init(chan);
+
+       list_add_tail(&chan->device_node, &dma->channels);
+
+       return 0;
+
+free_and_exit:
+       kfree(swdma_chan);
+       return rc;
+}
+
+static int switchtec_dma_chan_free(struct pci_dev *pdev,
+                                  struct switchtec_dma_chan *swdma_chan)
+{
+       spin_lock_bh(&swdma_chan->submit_lock);
+       swdma_chan->ring_active = false;
+       spin_unlock_bh(&swdma_chan->submit_lock);
+
+       spin_lock_bh(&swdma_chan->complete_lock);
+       swdma_chan->comp_ring_active = false;
+       spin_unlock_bh(&swdma_chan->complete_lock);
+
+       pci_free_irq(pdev, swdma_chan->irq, swdma_chan);
+       tasklet_kill(&swdma_chan->desc_task);
+
+       switchtec_dma_chan_stop(swdma_chan);
+
+       return 0;
+}
+
+static int switchtec_dma_chans_release(struct pci_dev *pdev,
+                                      struct switchtec_dma_dev *swdma_dev)
+{
+       int i;
+
+       for (i = 0; i < swdma_dev->chan_cnt; i++)
+               switchtec_dma_chan_free(pdev, swdma_dev->swdma_chans[i]);
+
+       return 0;
+}
+
+static int switchtec_dma_chans_enumerate(struct switchtec_dma_dev *swdma_dev,
+                                        struct pci_dev *pdev, int chan_cnt)
+{
+       struct dma_device *dma = &swdma_dev->dma_dev;
+       int base, cnt, rc, i;
+
+       swdma_dev->swdma_chans = kcalloc(chan_cnt, sizeof(*swdma_dev->swdma_chans),
+                                        GFP_KERNEL);
+
+       if (!swdma_dev->swdma_chans)
+               return -ENOMEM;
+
+       base = readw(swdma_dev->bar + SWITCHTEC_REG_SE_BUF_BASE);
+       cnt = readw(swdma_dev->bar + SWITCHTEC_REG_SE_BUF_CNT);
+
+       dev_dbg(&pdev->dev, "EP SE buffer base %d\n", base);
+       dev_dbg(&pdev->dev, "EP SE buffer count %d\n", cnt);
+
+       INIT_LIST_HEAD(&dma->channels);
+
+       for (i = 0; i < chan_cnt; i++) {
+               rc = switchtec_dma_chan_init(swdma_dev, pdev, i);
+               if (rc) {
+                       dev_err(&pdev->dev, "Channel %d: init channel failed\n",
+                               i);
+                       chan_cnt = i;
+                       goto err_exit;
+               }
+       }
+
+       return chan_cnt;
+
+err_exit:
+       for (i = 0; i < chan_cnt; i++)
+               switchtec_dma_chan_free(pdev, swdma_dev->swdma_chans[i]);
+
+       kfree(swdma_dev->swdma_chans);
+
+       return rc;
+}
+
 static void switchtec_dma_release(struct dma_device *dma_dev)
 {
        struct switchtec_dma_dev *swdma_dev =
                container_of(dma_dev, struct switchtec_dma_dev, dma_dev);
+       int i;
+
+       for (i = 0; i < swdma_dev->chan_cnt; i++)
+               kfree(swdma_dev->swdma_chans[i]);
+
+       kfree(swdma_dev->swdma_chans);
 
        put_device(dma_dev->dev);
        kfree(swdma_dev);
@@ -37,9 +997,9 @@ static void switchtec_dma_release(struct dma_device *dma_dev)
 static int switchtec_dma_create(struct pci_dev *pdev)
 {
        struct switchtec_dma_dev *swdma_dev;
+       int chan_cnt, nr_vecs, irq, rc;
        struct dma_device *dma;
        struct dma_chan *chan;
-       int nr_vecs, rc;
 
        /*
         * Create the switchtec dma device
@@ -58,18 +1018,51 @@ static int switchtec_dma_create(struct pci_dev *pdev)
        if (rc < 0)
                goto err_exit;
 
+       irq = readw(swdma_dev->bar + SWITCHTEC_REG_CHAN_STS_VEC);
+       pci_dbg(pdev, "Channel pause irq vector %d\n", irq);
+
+       rc = pci_request_irq(pdev, irq, NULL, switchtec_dma_chan_status_isr,
+                            swdma_dev, KBUILD_MODNAME);
+       if (rc)
+               goto err_exit;
+
+       swdma_dev->chan_status_irq = irq;
+
+       chan_cnt = readl(swdma_dev->bar + SWITCHTEC_REG_CHAN_CNT);
+       if (!chan_cnt) {
+               pci_err(pdev, "No channel configured.\n");
+               rc = -ENXIO;
+               goto err_exit;
+       }
+
+       chan_cnt = switchtec_dma_chans_enumerate(swdma_dev, pdev, chan_cnt);
+       if (chan_cnt < 0) {
+               pci_err(pdev, "Failed to enumerate dma channels: %d\n",
+                       chan_cnt);
+               rc = -ENXIO;
+               goto err_exit;
+       }
+
+       swdma_dev->chan_cnt = chan_cnt;
+
        dma = &swdma_dev->dma_dev;
        dma->copy_align = DMAENGINE_ALIGN_8_BYTES;
        dma->dev = get_device(&pdev->dev);
 
+       dma->device_alloc_chan_resources = switchtec_dma_alloc_chan_resources;
+       dma->device_free_chan_resources = switchtec_dma_free_chan_resources;
+       dma->device_terminate_all = switchtec_dma_terminate_all;
+       dma->device_synchronize = switchtec_dma_synchronize;
        dma->device_release = switchtec_dma_release;
 
        rc = dma_async_device_register(dma);
        if (rc) {
                pci_err(pdev, "Failed to register dma device: %d\n", rc);
-               goto err_exit;
+               goto err_chans_release_exit;
        }
 
+       pci_dbg(pdev, "Channel count: %d\n", chan_cnt);
+
        list_for_each_entry(chan, &dma->channels, device_node)
                pci_dbg(pdev, "%s\n", dma_chan_name(chan));
 
@@ -77,7 +1070,13 @@ static int switchtec_dma_create(struct pci_dev *pdev)
 
        return 0;
 
+err_chans_release_exit:
+       switchtec_dma_chans_release(pdev, swdma_dev);
+
 err_exit:
+       if (swdma_dev->chan_status_irq)
+               free_irq(swdma_dev->chan_status_irq, swdma_dev);
+
        iounmap(swdma_dev->bar);
        kfree(swdma_dev);
        return rc;
@@ -120,9 +1119,13 @@ static void switchtec_dma_remove(struct pci_dev *pdev)
 {
        struct switchtec_dma_dev *swdma_dev = pci_get_drvdata(pdev);
 
+       switchtec_dma_chans_release(pdev, swdma_dev);
+
        rcu_assign_pointer(swdma_dev->pdev, NULL);
        synchronize_rcu();
 
+       pci_free_irq(pdev, swdma_dev->chan_status_irq, swdma_dev);
+
        pci_free_irq_vectors(pdev);
 
        dma_async_device_unregister(&swdma_dev->dma_dev);