From: Srikanth Thokala <srikanth.thok...@intel.com>

Add Synopsys PCIe DWC core embedded-DMA functionality for local host

Cc: Arnd Bergmann <a...@arndb.de>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Mark Gross <mgr...@linux.intel.com>
Signed-off-by: Srikanth Thokala <srikanth.thok...@intel.com>
---
 drivers/misc/xlink-pcie/local_host/Makefile |   1 +
 drivers/misc/xlink-pcie/local_host/dma.c    | 577 ++++++++++++++++++++
 drivers/misc/xlink-pcie/local_host/epf.c    |  15 +-
 drivers/misc/xlink-pcie/local_host/epf.h    |  41 ++
 4 files changed, 631 insertions(+), 3 deletions(-)
 create mode 100644 drivers/misc/xlink-pcie/local_host/dma.c

diff --git a/drivers/misc/xlink-pcie/local_host/Makefile 
b/drivers/misc/xlink-pcie/local_host/Makefile
index 514d3f0c91bc..54fc118e2dd1 100644
--- a/drivers/misc/xlink-pcie/local_host/Makefile
+++ b/drivers/misc/xlink-pcie/local_host/Makefile
@@ -1,2 +1,3 @@
 obj-$(CONFIG_XLINK_PCIE_LH_DRIVER) += mxlk_ep.o
 mxlk_ep-objs := epf.o
+mxlk_ep-objs += dma.o
diff --git a/drivers/misc/xlink-pcie/local_host/dma.c 
b/drivers/misc/xlink-pcie/local_host/dma.c
new file mode 100644
index 000000000000..811e5eebb7ab
--- /dev/null
+++ b/drivers/misc/xlink-pcie/local_host/dma.c
@@ -0,0 +1,577 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*****************************************************************************
+ *
+ * Intel Keem Bay XLink PCIe Driver
+ *
+ * Copyright (C) 2020 Intel Corporation
+ *
+ ****************************************************************************/
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/wait.h>
+
+#include "epf.h"
+
+#define DMA_DBI_OFFSET                 (0x380000)
+
+/* PCIe DMA control 1 register definitions. */
+#define DMA_CH_CONTROL1_CB_SHIFT       (0)
+#define DMA_CH_CONTROL1_TCB_SHIFT      (1)
+#define DMA_CH_CONTROL1_LLP_SHIFT      (2)
+#define DMA_CH_CONTROL1_LIE_SHIFT      (3)
+#define DMA_CH_CONTROL1_CS_SHIFT       (5)
+#define DMA_CH_CONTROL1_CCS_SHIFT      (8)
+#define DMA_CH_CONTROL1_LLE_SHIFT      (9)
+#define DMA_CH_CONTROL1_CB_MASK                (BIT(DMA_CH_CONTROL1_CB_SHIFT))
+#define DMA_CH_CONTROL1_TCB_MASK       (BIT(DMA_CH_CONTROL1_TCB_SHIFT))
+#define DMA_CH_CONTROL1_LLP_MASK       (BIT(DMA_CH_CONTROL1_LLP_SHIFT))
+#define DMA_CH_CONTROL1_LIE_MASK       (BIT(DMA_CH_CONTROL1_LIE_SHIFT))
+#define DMA_CH_CONTROL1_CS_MASK                (0x3 << 
DMA_CH_CONTROL1_CS_SHIFT)
+#define DMA_CH_CONTROL1_CCS_MASK       (BIT(DMA_CH_CONTROL1_CCS_SHIFT))
+#define DMA_CH_CONTROL1_LLE_MASK       (BIT(DMA_CH_CONTROL1_LLE_SHIFT))
+
+/* DMA control 1 register Channel Status */
+#define DMA_CH_CONTROL1_CS_RUNNING     (0x1 << DMA_CH_CONTROL1_CS_SHIFT)
+#define DMA_CH_CONTROL1_CS_HALTED      (0x2 << DMA_CH_CONTROL1_CS_SHIFT)
+#define DMA_CH_CONTROL1_CS_STOPPED     (0x3 << DMA_CH_CONTROL1_CS_SHIFT)
+
+/* PCIe DMA Engine enable register definitions. */
+#define DMA_ENGINE_EN_SHIFT            (0)
+#define DMA_ENGINE_EN_MASK             (BIT(DMA_ENGINE_EN_SHIFT))
+
+/* PCIe DMA interrupt registers definitions. */
+#define DMA_ABORT_INTERRUPT_SHIFT      (16)
+#define DMA_ABORT_INTERRUPT_MASK       (0xFF << DMA_ABORT_INTERRUPT_SHIFT)
+#define DMA_ABORT_INTERRUPT_CH_MASK(_c) (BIT(_c) << DMA_ABORT_INTERRUPT_SHIFT)
+#define DMA_DONE_INTERRUPT_MASK                (0xFF)
+#define DMA_DONE_INTERRUPT_CH_MASK(_c) (BIT(_c))
+#define DMA_ALL_INTERRUPT_MASK \
+       (DMA_ABORT_INTERRUPT_MASK | DMA_DONE_INTERRUPT_MASK)
+
+#define DMA_LL_ERROR_SHIFT             (16)
+#define DMA_CPL_ABORT_SHIFT            (8)
+#define DMA_CPL_TIMEOUT_SHIFT          (16)
+#define DMA_DATA_POI_SHIFT             (24)
+#define DMA_AR_ERROR_CH_MASK(_c)       (BIT(_c))
+#define DMA_LL_ERROR_CH_MASK(_c)       (BIT(_c) << DMA_LL_ERROR_SHIFT)
+#define DMA_UNREQ_ERROR_CH_MASK(_c)    (BIT(_c))
+#define DMA_CPL_ABORT_ERROR_CH_MASK(_c)        (BIT(_c) << DMA_CPL_ABORT_SHIFT)
+#define DMA_CPL_TIMEOUT_ERROR_CH_MASK(_c) (BIT(_c) << DMA_CPL_TIMEOUT_SHIFT)
+#define DMA_DATA_POI_ERROR_CH_MASK(_c) (BIT(_c) << DMA_DATA_POI_SHIFT)
+
+#define DMA_LLLAIE_SHIFT               (16)
+#define DMA_LLLAIE_MASK                        (0xF << DMA_LLLAIE_SHIFT)
+
+#define DMA_CHAN_WRITE_MAX_WEIGHT      (0x7)
+#define DMA_CHAN_READ_MAX_WEIGHT       (0x3)
+#define DMA_CHAN0_WEIGHT_OFFSET                (0)
+#define DMA_CHAN1_WEIGHT_OFFSET                (5)
+#define DMA_CHAN2_WEIGHT_OFFSET                (10)
+#define DMA_CHAN3_WEIGHT_OFFSET                (15)
+#define DMA_CHAN_WRITE_ALL_MAX_WEIGHT                                  \
+       ((DMA_CHAN_WRITE_MAX_WEIGHT << DMA_CHAN0_WEIGHT_OFFSET) |       \
+        (DMA_CHAN_WRITE_MAX_WEIGHT << DMA_CHAN1_WEIGHT_OFFSET) |       \
+        (DMA_CHAN_WRITE_MAX_WEIGHT << DMA_CHAN2_WEIGHT_OFFSET) |       \
+        (DMA_CHAN_WRITE_MAX_WEIGHT << DMA_CHAN3_WEIGHT_OFFSET))
+#define DMA_CHAN_READ_ALL_MAX_WEIGHT                                   \
+       ((DMA_CHAN_READ_MAX_WEIGHT << DMA_CHAN0_WEIGHT_OFFSET) |        \
+        (DMA_CHAN_READ_MAX_WEIGHT << DMA_CHAN1_WEIGHT_OFFSET) |        \
+        (DMA_CHAN_READ_MAX_WEIGHT << DMA_CHAN2_WEIGHT_OFFSET) |        \
+        (DMA_CHAN_READ_MAX_WEIGHT << DMA_CHAN3_WEIGHT_OFFSET))
+
+#define PCIE_REGS_PCIE_APP_CNTRL       0x8
+#define APP_XFER_PENDING               BIT(6)
+#define PCIE_REGS_PCIE_SII_PM_STATE_1  0xb4
+#define PM_LINKST_IN_L1                        BIT(10)
+
+#define DMA_POLLING_TIMEOUT            1000000
+#define DMA_ENABLE_TIMEOUT             1000
+#define DMA_PCIE_PM_L1_TIMEOUT         20
+
+struct __packed pcie_dma_reg {
+       u32 dma_ctrl_data_arb_prior;
+       u32 reserved1;
+       u32 dma_ctrl;
+       u32 dma_write_engine_en;
+       u32 dma_write_doorbell;
+       u32 reserved2;
+       u32 dma_write_channel_arb_weight_low;
+       u32 dma_write_channel_arb_weight_high;
+       u32 reserved3[3];
+       u32 dma_read_engine_en;
+       u32 dma_read_doorbell;
+       u32 reserved4;
+       u32 dma_read_channel_arb_weight_low;
+       u32 dma_read_channel_arb_weight_high;
+       u32 reserved5[3];
+       u32 dma_write_int_status;
+       u32 reserved6;
+       u32 dma_write_int_mask;
+       u32 dma_write_int_clear;
+       u32 dma_write_err_status;
+       u32 dma_write_done_imwr_low;
+       u32 dma_write_done_imwr_high;
+       u32 dma_write_abort_imwr_low;
+       u32 dma_write_abort_imwr_high;
+       u16 dma_write_ch_imwr_data[8];
+       u32 reserved7[4];
+       u32 dma_write_linked_list_err_en;
+       u32 reserved8[3];
+       u32 dma_read_int_status;
+       u32 reserved9;
+       u32 dma_read_int_mask;
+       u32 dma_read_int_clear;
+       u32 reserved10;
+       u32 dma_read_err_status_low;
+       u32 dma_rd_err_sts_h;
+       u32 reserved11[2];
+       u32 dma_read_linked_list_err_en;
+       u32 reserved12;
+       u32 dma_read_done_imwr_low;
+       u32 dma_read_done_imwr_high;
+       u32 dma_read_abort_imwr_low;
+       u32 dma_read_abort_imwr_high;
+       u16 dma_read_ch_imwr_data[8];
+};
+
+struct __packed pcie_dma_chan {
+       u32 dma_ch_control1;
+       u32 reserved1;
+       u32 dma_transfer_size;
+       u32 dma_sar_low;
+       u32 dma_sar_high;
+       u32 dma_dar_low;
+       u32 dma_dar_high;
+       u32 dma_llp_low;
+       u32 dma_llp_high;
+};
+
+enum xpcie_ep_engine_type {
+       WRITE_ENGINE,
+       READ_ENGINE
+};
+
+static u32 dma_chan_offset[2][DMA_CHAN_NUM] = {
+       { 0x200, 0x400, 0x600, 0x800 },
+       { 0x300, 0x500, 0x700, 0x900 }
+};
+
+static void __iomem *intel_xpcie_ep_get_dma_base(struct pci_epf *epf)
+{
+       struct device *dev = &epf->dev;
+       struct xpcie_epf *xpcie_epf = (struct xpcie_epf *)dev->driver_data;
+
+       return xpcie_epf->dbi_base + DMA_DBI_OFFSET;
+}
+
+static int intel_xpcie_ep_dma_disable(void __iomem *dma_base,
+                                     enum xpcie_ep_engine_type rw)
+{
+       struct __iomem pcie_dma_reg * dma_reg =
+                               (struct __iomem pcie_dma_reg *)dma_base;
+       void __iomem *int_mask, *int_clear;
+       void __iomem *engine_en, *ll_err;
+       int i;
+
+       if (rw == WRITE_ENGINE) {
+               engine_en = (void __iomem *)&dma_reg->dma_write_engine_en;
+               int_mask = (void __iomem *)&dma_reg->dma_write_int_mask;
+               int_clear = (void __iomem *)&dma_reg->dma_write_int_clear;
+               ll_err = (void __iomem *)&dma_reg->dma_write_linked_list_err_en;
+       } else {
+               engine_en = (void __iomem *)&dma_reg->dma_read_engine_en;
+               int_mask = (void __iomem *)&dma_reg->dma_read_int_mask;
+               int_clear = (void __iomem *)&dma_reg->dma_read_int_clear;
+               ll_err = (void __iomem *)&dma_reg->dma_read_linked_list_err_en;
+       }
+
+       iowrite32(0x0, engine_en);
+
+       /* Mask all interrupts. */
+       iowrite32(DMA_ALL_INTERRUPT_MASK, int_mask);
+
+       /* Clear all interrupts. */
+       iowrite32(DMA_ALL_INTERRUPT_MASK, int_clear);
+
+       /* Disable LL abort interrupt (LLLAIE). */
+       iowrite32(0, ll_err);
+
+       /* Wait until the engine is disabled. */
+       for (i = 0; i < DMA_ENABLE_TIMEOUT; i++) {
+               if (!(ioread32(engine_en) & DMA_ENGINE_EN_MASK))
+                       return 0;
+               msleep(20);
+       }
+
+       return -EBUSY;
+}
+
+static void intel_xpcie_ep_dma_enable(void __iomem *dma_base,
+                                     enum xpcie_ep_engine_type rw)
+{
+       struct __iomem pcie_dma_reg * dma_reg =
+                               (struct __iomem pcie_dma_reg *)(dma_base);
+       void __iomem *engine_en, *ll_err, *arb_weight;
+       struct __iomem pcie_dma_chan * dma_chan;
+       void __iomem *int_mask, *int_clear;
+       u32 offset, weight;
+       int i;
+
+       if (rw == WRITE_ENGINE) {
+               engine_en = (void __iomem *)&dma_reg->dma_write_engine_en;
+               int_mask = (void __iomem *)&dma_reg->dma_write_int_mask;
+               int_clear = (void __iomem *)&dma_reg->dma_write_int_clear;
+               ll_err = (void __iomem *)&dma_reg->dma_write_linked_list_err_en;
+               arb_weight = (void __iomem *)
+                            &dma_reg->dma_write_channel_arb_weight_low;
+               weight = DMA_CHAN_WRITE_ALL_MAX_WEIGHT;
+       } else {
+               engine_en = (void __iomem *)&dma_reg->dma_read_engine_en;
+               int_mask = (void __iomem *)&dma_reg->dma_read_int_mask;
+               int_clear = (void __iomem *)&dma_reg->dma_read_int_clear;
+               ll_err = (void __iomem *)&dma_reg->dma_read_linked_list_err_en;
+               arb_weight = (void __iomem *)
+                            &dma_reg->dma_read_channel_arb_weight_low;
+               weight = DMA_CHAN_READ_ALL_MAX_WEIGHT;
+       }
+
+       iowrite32(DMA_ENGINE_EN_MASK, engine_en);
+
+       /* Unmask all interrupts, so that the interrupt line gets asserted. */
+       iowrite32(~(u32)DMA_ALL_INTERRUPT_MASK, int_mask);
+
+       /* Clear all interrupts. */
+       iowrite32(DMA_ALL_INTERRUPT_MASK, int_clear);
+
+       /* Set channel round robin weight. */
+       iowrite32(weight, arb_weight);
+
+       /* Enable LL abort interrupt (LLLAIE). */
+       iowrite32(DMA_LLLAIE_MASK, ll_err);
+
+       /* Enable linked list mode. */
+       for (i = 0; i < DMA_CHAN_NUM; i++) {
+               offset = dma_chan_offset[rw][i];
+               dma_chan = (struct __iomem pcie_dma_chan *)(dma_base + offset);
+               iowrite32(DMA_CH_CONTROL1_LLE_MASK,
+                         (void __iomem *)&dma_chan->dma_ch_control1);
+       }
+}
+
+/*
+ * Make sure EP is not in L1 state when DMA doorbell.
+ * The DMA controller may start the wrong channel if doorbell occurs at the
+ * same time as controller is transitioning to L1.
+ */
+static int intel_xpcie_ep_dma_doorbell(struct xpcie_epf *xpcie_epf, int chan,
+                                      void __iomem *doorbell)
+{
+       int i = DMA_PCIE_PM_L1_TIMEOUT, rc = 0;
+       u32 val, pm_val;
+
+       val = ioread32(xpcie_epf->apb_base + PCIE_REGS_PCIE_APP_CNTRL);
+       iowrite32(val | APP_XFER_PENDING,
+                 xpcie_epf->apb_base + PCIE_REGS_PCIE_APP_CNTRL);
+       pm_val = ioread32(xpcie_epf->apb_base + PCIE_REGS_PCIE_SII_PM_STATE_1);
+       while (pm_val & PM_LINKST_IN_L1) {
+               if (i-- < 0) {
+                       rc = -ETIME;
+                       break;
+               }
+               udelay(5);
+               pm_val = ioread32(xpcie_epf->apb_base +
+                                 PCIE_REGS_PCIE_SII_PM_STATE_1);
+       }
+
+       iowrite32((u32)chan, doorbell);
+
+       iowrite32(val & ~APP_XFER_PENDING,
+                 xpcie_epf->apb_base + PCIE_REGS_PCIE_APP_CNTRL);
+
+       return rc;
+}
+
+static int intel_xpcie_ep_dma_err_status(void __iomem *err_status, int chan)
+{
+       if (ioread32(err_status) &
+           (DMA_AR_ERROR_CH_MASK(chan) | DMA_LL_ERROR_CH_MASK(chan)))
+               return -EIO;
+
+       return 0;
+}
+
+static int intel_xpcie_ep_dma_rd_err_sts_h(void __iomem *err_status,
+                                          int chan)
+{
+       if (ioread32(err_status) &
+           (DMA_UNREQ_ERROR_CH_MASK(chan) |
+            DMA_CPL_ABORT_ERROR_CH_MASK(chan) |
+            DMA_CPL_TIMEOUT_ERROR_CH_MASK(chan) |
+            DMA_DATA_POI_ERROR_CH_MASK(chan)))
+               return -EIO;
+
+       return 0;
+}
+
+static void
+intel_xpcie_ep_dma_setup_ll_descs(struct __iomem pcie_dma_chan * dma_chan,
+                                 struct xpcie_dma_ll_desc_buf *desc_buf,
+                                 int descs_num)
+{
+       struct xpcie_dma_ll_desc *descs = desc_buf->virt;
+       int i;
+
+       /* Setup linked list descriptors */
+       for (i = 0; i < descs_num - 1; i++)
+               descs[i].dma_ch_control1 = DMA_CH_CONTROL1_CB_MASK;
+       descs[descs_num - 1].dma_ch_control1 = DMA_CH_CONTROL1_LIE_MASK |
+                                               DMA_CH_CONTROL1_CB_MASK;
+       descs[descs_num].dma_ch_control1 = DMA_CH_CONTROL1_LLP_MASK |
+                                          DMA_CH_CONTROL1_TCB_MASK;
+       descs[descs_num].src_addr = (phys_addr_t)desc_buf->phys;
+
+       /* Setup linked list settings */
+       iowrite32(DMA_CH_CONTROL1_LLE_MASK | DMA_CH_CONTROL1_CCS_MASK,
+                 (void __iomem *)&dma_chan->dma_ch_control1);
+       iowrite32((u32)desc_buf->phys, (void __iomem *)&dma_chan->dma_llp_low);
+       iowrite32((u64)desc_buf->phys >> 32,
+                 (void __iomem *)&dma_chan->dma_llp_high);
+}
+
+int intel_xpcie_ep_dma_write_ll(struct pci_epf *epf, int chan, int descs_num)
+{
+       struct xpcie_epf *xpcie_epf = epf_get_drvdata(epf);
+       void __iomem *dma_base = xpcie_epf->dma_base;
+       struct __iomem pcie_dma_chan * dma_chan;
+       struct xpcie_dma_ll_desc_buf *desc_buf;
+       struct __iomem pcie_dma_reg * dma_reg =
+                               (struct __iomem pcie_dma_reg *)(dma_base);
+       int i, rc;
+
+       if (descs_num <= 0 || descs_num > XPCIE_NUM_TX_DESCS)
+               return -EINVAL;
+
+       if (chan < 0 || chan >= DMA_CHAN_NUM)
+               return -EINVAL;
+
+       dma_chan = (struct __iomem pcie_dma_chan *)
+               (dma_base + dma_chan_offset[WRITE_ENGINE][chan]);
+
+       desc_buf = &xpcie_epf->tx_desc_buf[chan];
+
+       intel_xpcie_ep_dma_setup_ll_descs(dma_chan, desc_buf, descs_num);
+
+       /* Start DMA transfer. */
+       rc = intel_xpcie_ep_dma_doorbell(xpcie_epf, chan,
+                                        (void __iomem *)
+                                        &dma_reg->dma_write_doorbell);
+       if (rc)
+               return rc;
+
+       /* Wait for DMA transfer to complete. */
+       for (i = 0; i < DMA_POLLING_TIMEOUT; i++) {
+               usleep_range(5, 10);
+               if (ioread32((void __iomem *)&dma_reg->dma_write_int_status) &
+                   (DMA_DONE_INTERRUPT_CH_MASK(chan) |
+                    DMA_ABORT_INTERRUPT_CH_MASK(chan)))
+                       break;
+       }
+       if (i == DMA_POLLING_TIMEOUT) {
+               dev_err(&xpcie_epf->epf->dev, "DMA Wr timeout\n");
+               rc = -ETIME;
+               goto cleanup;
+       }
+
+       rc = intel_xpcie_ep_dma_err_status((void __iomem *)
+                                          &dma_reg->dma_write_err_status,
+                                          chan);
+
+cleanup:
+       /* Clear the done/abort interrupt. */
+       iowrite32((DMA_DONE_INTERRUPT_CH_MASK(chan) |
+                  DMA_ABORT_INTERRUPT_CH_MASK(chan)),
+                 (void __iomem *)&dma_reg->dma_write_int_clear);
+
+       if (rc) {
+               if (intel_xpcie_ep_dma_disable(dma_base, WRITE_ENGINE)) {
+                       dev_err(&xpcie_epf->epf->dev,
+                               "failed to disable WR DMA\n");
+                       return rc;
+               }
+               intel_xpcie_ep_dma_enable(dma_base, WRITE_ENGINE);
+       }
+
+       return rc;
+}
+
+int intel_xpcie_ep_dma_read_ll(struct pci_epf *epf, int chan, int descs_num)
+{
+       struct xpcie_epf *xpcie_epf = epf_get_drvdata(epf);
+       void __iomem *dma_base = xpcie_epf->dma_base;
+       struct xpcie_dma_ll_desc_buf *desc_buf;
+       struct __iomem pcie_dma_reg * dma_reg =
+                               (struct __iomem pcie_dma_reg *)(dma_base);
+       struct __iomem pcie_dma_chan * dma_chan;
+       int i, rc;
+
+       if (descs_num <= 0 || descs_num > XPCIE_NUM_RX_DESCS)
+               return -EINVAL;
+
+       if (chan < 0 || chan >= DMA_CHAN_NUM)
+               return -EINVAL;
+
+       dma_chan = (struct __iomem pcie_dma_chan *)
+               (dma_base + dma_chan_offset[READ_ENGINE][chan]);
+
+       desc_buf = &xpcie_epf->rx_desc_buf[chan];
+
+       intel_xpcie_ep_dma_setup_ll_descs(dma_chan, desc_buf, descs_num);
+
+       /* Start DMA transfer. */
+       rc = intel_xpcie_ep_dma_doorbell(xpcie_epf, chan,
+                                        (void __iomem *)
+                                        &dma_reg->dma_read_doorbell);
+       if (rc)
+               return rc;
+
+       /* Wait for DMA transfer to complete. */
+       for (i = 0; i < DMA_POLLING_TIMEOUT; i++) {
+               usleep_range(5, 10);
+               if (ioread32((void __iomem *)&dma_reg->dma_read_int_status) &
+                   (DMA_DONE_INTERRUPT_CH_MASK(chan) |
+                    DMA_ABORT_INTERRUPT_CH_MASK(chan)))
+                       break;
+       }
+       if (i == DMA_POLLING_TIMEOUT) {
+               dev_err(&xpcie_epf->epf->dev, "DMA Rd timeout\n");
+               rc = -ETIME;
+               goto cleanup;
+       }
+
+       rc = intel_xpcie_ep_dma_err_status((void __iomem *)
+                                          &dma_reg->dma_read_err_status_low,
+                                          chan);
+       if (!rc) {
+               rc =
+               intel_xpcie_ep_dma_rd_err_sts_h((void __iomem *)
+                                               &dma_reg->dma_rd_err_sts_h,
+                                               chan);
+       }
+cleanup:
+       /* Clear the done/abort interrupt. */
+       iowrite32((DMA_DONE_INTERRUPT_CH_MASK(chan) |
+                  DMA_ABORT_INTERRUPT_CH_MASK(chan)),
+                 (void __iomem *)&dma_reg->dma_read_int_clear);
+
+       if (rc) {
+               if (intel_xpcie_ep_dma_disable(dma_base, READ_ENGINE)) {
+                       dev_err(&xpcie_epf->epf->dev,
+                               "failed to disable RD DMA\n");
+                       return rc;
+               }
+               intel_xpcie_ep_dma_enable(dma_base, READ_ENGINE);
+       }
+
+       return rc;
+}
+
+static void intel_xpcie_ep_dma_free_ll_descs_mem(struct xpcie_epf *xpcie_epf)
+{
+       struct device *dma_dev = xpcie_epf->epf->epc->dev.parent;
+       int i;
+
+       for (i = 0; i < DMA_CHAN_NUM; i++) {
+               if (xpcie_epf->tx_desc_buf[i].virt) {
+                       dma_free_coherent(dma_dev,
+                                         xpcie_epf->tx_desc_buf[i].size,
+                                         xpcie_epf->tx_desc_buf[i].virt,
+                                         xpcie_epf->tx_desc_buf[i].phys);
+               }
+               if (xpcie_epf->rx_desc_buf[i].virt) {
+                       dma_free_coherent(dma_dev,
+                                         xpcie_epf->rx_desc_buf[i].size,
+                                         xpcie_epf->rx_desc_buf[i].virt,
+                                         xpcie_epf->rx_desc_buf[i].phys);
+               }
+
+               memset(&xpcie_epf->tx_desc_buf[i], 0,
+                      sizeof(struct xpcie_dma_ll_desc_buf));
+               memset(&xpcie_epf->rx_desc_buf[i], 0,
+                      sizeof(struct xpcie_dma_ll_desc_buf));
+       }
+}
+
+static int intel_xpcie_ep_dma_alloc_ll_descs_mem(struct xpcie_epf *xpcie_epf)
+{
+       struct device *dma_dev = xpcie_epf->epf->epc->dev.parent;
+       int tx_num = XPCIE_NUM_TX_DESCS + 1;
+       int rx_num = XPCIE_NUM_RX_DESCS + 1;
+       size_t tx_size, rx_size;
+       int i;
+
+       tx_size = tx_num * sizeof(struct xpcie_dma_ll_desc);
+       rx_size = rx_num * sizeof(struct xpcie_dma_ll_desc);
+
+       for (i = 0; i < DMA_CHAN_NUM; i++) {
+               xpcie_epf->tx_desc_buf[i].virt =
+                       dma_alloc_coherent(dma_dev, tx_size,
+                                          &xpcie_epf->tx_desc_buf[i].phys,
+                                          GFP_KERNEL);
+               xpcie_epf->rx_desc_buf[i].virt =
+                       dma_alloc_coherent(dma_dev, rx_size,
+                                          &xpcie_epf->rx_desc_buf[i].phys,
+                                          GFP_KERNEL);
+
+               if (!xpcie_epf->tx_desc_buf[i].virt ||
+                   !xpcie_epf->rx_desc_buf[i].virt) {
+                       intel_xpcie_ep_dma_free_ll_descs_mem(xpcie_epf);
+                       return -ENOMEM;
+               }
+
+               xpcie_epf->tx_desc_buf[i].size = tx_size;
+               xpcie_epf->rx_desc_buf[i].size = rx_size;
+       }
+       return 0;
+}
+
+int intel_xpcie_ep_dma_reset(struct pci_epf *epf)
+{
+       struct xpcie_epf *xpcie_epf = epf_get_drvdata(epf);
+
+       /* Disable the DMA read/write engine. */
+       if (intel_xpcie_ep_dma_disable(xpcie_epf->dma_base, WRITE_ENGINE) ||
+           intel_xpcie_ep_dma_disable(xpcie_epf->dma_base, READ_ENGINE))
+               return -EBUSY;
+
+       intel_xpcie_ep_dma_enable(xpcie_epf->dma_base, WRITE_ENGINE);
+       intel_xpcie_ep_dma_enable(xpcie_epf->dma_base, READ_ENGINE);
+
+       return 0;
+}
+
+int intel_xpcie_ep_dma_uninit(struct pci_epf *epf)
+{
+       struct xpcie_epf *xpcie_epf = epf_get_drvdata(epf);
+
+       if (intel_xpcie_ep_dma_disable(xpcie_epf->dma_base, WRITE_ENGINE) ||
+           intel_xpcie_ep_dma_disable(xpcie_epf->dma_base, READ_ENGINE))
+               return -EBUSY;
+
+       intel_xpcie_ep_dma_free_ll_descs_mem(xpcie_epf);
+
+       return 0;
+}
+
+int intel_xpcie_ep_dma_init(struct pci_epf *epf)
+{
+       struct xpcie_epf *xpcie_epf = epf_get_drvdata(epf);
+       int rc;
+
+       xpcie_epf->dma_base = intel_xpcie_ep_get_dma_base(epf);
+
+       rc = intel_xpcie_ep_dma_alloc_ll_descs_mem(xpcie_epf);
+       if (rc)
+               return rc;
+
+       return intel_xpcie_ep_dma_reset(epf);
+}
diff --git a/drivers/misc/xlink-pcie/local_host/epf.c 
b/drivers/misc/xlink-pcie/local_host/epf.c
index ae07b364734d..fc29180aa508 100644
--- a/drivers/misc/xlink-pcie/local_host/epf.c
+++ b/drivers/misc/xlink-pcie/local_host/epf.c
@@ -45,6 +45,8 @@ static irqreturn_t intel_xpcie_err_interrupt(int irq, void 
*args)
 
        xpcie_epf = container_of(xpcie, struct xpcie_epf, xpcie);
        val = ioread32(xpcie_epf->apb_base + PCIE_REGS_PCIE_ERR_INTR_FLAGS);
+       if (val & LINK_REQ_RST_FLG)
+               intel_xpcie_ep_dma_reset(xpcie_epf->epf);
 
        iowrite32(val, xpcie_epf->apb_base + PCIE_REGS_PCIE_ERR_INTR_FLAGS);
 
@@ -325,8 +327,17 @@ static int intel_xpcie_epf_bind(struct pci_epf *epf)
                goto err_cleanup_bars;
        }
 
+       ret = intel_xpcie_ep_dma_init(epf);
+       if (ret) {
+               dev_err(&epf->dev, "DMA initialization failed\n");
+               goto err_free_err_irq;
+       }
+
        return 0;
 
+err_free_err_irq:
+       free_irq(xpcie_epf->irq_err, &xpcie_epf->xpcie);
+
 err_cleanup_bars:
        intel_xpcie_cleanup_bars(epf);
 
@@ -335,11 +346,9 @@ static int intel_xpcie_epf_bind(struct pci_epf *epf)
 
 static void intel_xpcie_epf_unbind(struct pci_epf *epf)
 {
-       struct xpcie_epf *xpcie_epf = epf_get_drvdata(epf);
        struct pci_epc *epc = epf->epc;
 
-       free_irq(xpcie_epf->irq, &xpcie_epf->xpcie);
-       free_irq(xpcie_epf->irq_err, &xpcie_epf->xpcie);
+       intel_xpcie_ep_dma_uninit(epf);
 
        pci_epc_stop(epc);
 
diff --git a/drivers/misc/xlink-pcie/local_host/epf.h 
b/drivers/misc/xlink-pcie/local_host/epf.h
index 2b38c87b3701..6ce5260e67be 100644
--- a/drivers/misc/xlink-pcie/local_host/epf.h
+++ b/drivers/misc/xlink-pcie/local_host/epf.h
@@ -20,6 +20,38 @@
 
 #define KEEMBAY_XPCIE_STEPPING_MAXLEN 8
 
+#define DMA_CHAN_NUM           (4)
+
+#define XPCIE_NUM_TX_DESCS     (64)
+#define XPCIE_NUM_RX_DESCS     (64)
+
+extern bool dma_ll_mode;
+
+struct xpcie_dma_ll_desc {
+       u32 dma_ch_control1;
+       u32 dma_transfer_size;
+       union {
+               struct {
+                       u32 dma_sar_low;
+                       u32 dma_sar_high;
+               };
+               phys_addr_t src_addr;
+       };
+       union {
+               struct {
+                       u32 dma_dar_low;
+                       u32 dma_dar_high;
+               };
+               phys_addr_t dst_addr;
+       };
+} __packed;
+
+struct xpcie_dma_ll_desc_buf {
+       struct xpcie_dma_ll_desc *virt;
+       dma_addr_t phys;
+       size_t size;
+};
+
 struct xpcie_epf {
        struct pci_epf *epf;
        void *vaddr[BAR_5 + 1];
@@ -34,6 +66,15 @@ struct xpcie_epf {
        void __iomem *dma_base;
        void __iomem *dbi_base;
        char stepping[KEEMBAY_XPCIE_STEPPING_MAXLEN];
+
+       struct xpcie_dma_ll_desc_buf    tx_desc_buf[DMA_CHAN_NUM];
+       struct xpcie_dma_ll_desc_buf    rx_desc_buf[DMA_CHAN_NUM];
 };
 
+int intel_xpcie_ep_dma_init(struct pci_epf *epf);
+int intel_xpcie_ep_dma_uninit(struct pci_epf *epf);
+int intel_xpcie_ep_dma_reset(struct pci_epf *epf);
+int intel_xpcie_ep_dma_read_ll(struct pci_epf *epf, int chan, int descs_num);
+int intel_xpcie_ep_dma_write_ll(struct pci_epf *epf, int chan, int descs_num);
+
 #endif /* XPCIE_EPF_HEADER_ */
-- 
2.17.1

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