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From:   mgross@linux.intel.com
To:     markgross@kernel.org, mgross@linux.intel.com, arnd@arndb.de,
        bp@suse.de, damien.lemoal@wdc.com, dragan.cvetic@xilinx.com,
        gregkh@linuxfoundation.org, corbet@lwn.net,
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        peng.fan@nxp.com, robh+dt@kernel.org, shawnguo@kernel.org,
        jassisinghbrar@gmail.com
Cc:     linux-kernel@vger.kernel.org,
        Srikanth Thokala <srikanth.thokala@intel.com>
Subject: [PATCH v6 10/34] misc: xlink-pcie: lh: Add PCIe EP DMA functionality
Date:   Fri, 12 Feb 2021 14:22:40 -0800
Message-Id: <20210212222304.110194-11-mgross@linux.intel.com>
In-Reply-To: <20210212222304.110194-1-mgross@linux.intel.com>
References: <20210212222304.110194-1-mgross@linux.intel.com>
Precedence: bulk

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

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

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Mark Gross <mgross@linux.intel.com>
Signed-off-by: Mark Gross <mgross@linux.intel.com>
Signed-off-by: Srikanth Thokala <srikanth.thokala@intel.com>
---
 drivers/misc/xlink-pcie/local_host/Makefile |   1 +
 drivers/misc/xlink-pcie/local_host/dma.c    | 575 ++++++++++++++++++++
 drivers/misc/xlink-pcie/local_host/epf.c    |  15 +-
 drivers/misc/xlink-pcie/local_host/epf.h    |  41 ++
 4 files changed, 629 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..42978fb0db49
--- /dev/null
+++ b/drivers/misc/xlink-pcie/local_host/dma.c
@@ -0,0 +1,575 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Intel Keem Bay XLink PCIe Driver
+ *
+ * Copyright (C) 2021 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 0234756e89ae..7019aecd6a81 100644
--- a/drivers/misc/xlink-pcie/local_host/epf.c
+++ b/drivers/misc/xlink-pcie/local_host/epf.c
@@ -43,6 +43,8 @@ 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);
 
@@ -285,8 +287,17 @@ 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);
 
@@ -295,11 +306,9 @@ 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 a60cd43fe555..82410404d54e 100644
--- a/drivers/misc/xlink-pcie/local_host/epf.h
+++ b/drivers/misc/xlink-pcie/local_host/epf.h
@@ -18,6 +18,38 @@
 
 #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];
@@ -32,6 +64,15 @@ 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