[PATCH v7 3/5] dmaengine: xilinx: dpdma: Add the Xilinx DisplayPort DMA engine driver

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

From: Hyun Kwon <hyun.kwon@xilinx.com>

The ZynqMP DisplayPort subsystem includes a DMA engine called DPDMA with
6 DMa channels (4 for display and 2 for audio). This driver exposes the
DPDMA through the dmaengine API, to be used by audio (ALSA) and display
(DRM) drivers for the DisplayPort subsystem.

Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>
Signed-off-by: Tejas Upadhyay <tejasu@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
Changes since v6:

- Reject transactions without DMA_PREP_LOAD_EOT

Changes since v5:

- Update copyright year
- Use GFP_NOWAIT to allocate descriptor
- Drop check of deprecated direction parameter in channel configuration
- Don't reject channel configuration if the channel is busy

Changes since v4:

- Support DMA_PREP_LOAD_EOT, ignoring any transaction that doesn't have
  the flag set, as requested in the review of v4

Changes since v3:

- Fix uninitialized variable in xilinx_dpdma_config()
- Free pending and active descriptors upon termination
- Switch to DMA_PREP_REPEAT

Changes since v2:

- Switch to virt-dma
- Support interleaved cyclic transfers and nothing else
- Fix terminate_all behaviour (don't wait)
- Fix bug in extended address handling for hw desc
- Clean up video group handling
- Update driver name
- Use macros for bitfields
- Remove unneeded header
- Coding style and typo fixes

Changes since v1:

- Remove unneeded #include
- Drop enum xilinx_dpdma_chan_id
- Update compatible string
- Drop DT subnodes
- Replace XILINX_DPDMA_NUM_CHAN with ARRAY_SIZE(xdev->chan)
- Disable IRQ at remove() time
- Use devm_platform_ioremap_resource()
- Don't inline functions manually
- Add section headers
- Merge DMA engine implementation in their wrappers
- Rename xilinx_dpdma_sw_desc::phys to dma_addr
- Use GENMASK()
- Use FIELD_PREP/FIELD_GET
- Fix MSB handling in xilinx_dpdma_sw_desc_addr_64()
- Fix logic in xilinx_dpdma_chan_prep_slave_sg()
- Document why xilinx_dpdma_config() doesn't need to check most
  parameters
- Remove debugfs support
- Rechedule errored descriptor
- Align the line size with 128bit
- SPDX header formatting
---
 MAINTAINERS                       |    1 +
 drivers/dma/Kconfig               |   10 +
 drivers/dma/xilinx/Makefile       |    1 +
 drivers/dma/xilinx/xilinx_dpdma.c | 1533 +++++++++++++++++++++++++++++
 4 files changed, 1545 insertions(+)
 create mode 100644 drivers/dma/xilinx/xilinx_dpdma.c

diff --git a/MAINTAINERS b/MAINTAINERS
index fa52d4f9f8c8..6c20a6d338f0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18858,6 +18858,7 @@ M:	Laurent Pinchart <laurent.pinchart@ideasonboard.com>
 L:	dmaengine@vger.kernel.org
 S:	Supported
 F:	Documentation/devicetree/bindings/dma/xilinx/xlnx,zynqmp-dpdma.yaml
+F:	drivers/dma/xilinx/xilinx_dpdma.c
 F:	include/dt-bindings/dma/xlnx-zynqmp-dpdma.h
 
 XILLYBUS DRIVER
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index de41d7928bff..668e9636c547 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -707,6 +707,16 @@ config XILINX_ZYNQMP_DMA
 	help
 	  Enable support for Xilinx ZynqMP DMA controller.
 
+config XILINX_ZYNQMP_DPDMA
+	tristate "Xilinx DPDMA Engine"
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for Xilinx ZynqMP DisplayPort DMA. Choose this option
+	  if you have a Xilinx ZynqMP SoC with a DisplayPort subsystem. The
+	  driver provides the dmaengine required by the DisplayPort subsystem
+	  display driver.
+
 config ZX_DMA
 	tristate "ZTE ZX DMA support"
 	depends on ARCH_ZX || COMPILE_TEST
diff --git a/drivers/dma/xilinx/Makefile b/drivers/dma/xilinx/Makefile
index e921de575b55..767bb45f641f 100644
--- a/drivers/dma/xilinx/Makefile
+++ b/drivers/dma/xilinx/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_XILINX_DMA) += xilinx_dma.o
 obj-$(CONFIG_XILINX_ZYNQMP_DMA) += zynqmp_dma.o
+obj-$(CONFIG_XILINX_ZYNQMP_DPDMA) += xilinx_dpdma.o
diff --git a/drivers/dma/xilinx/xilinx_dpdma.c b/drivers/dma/xilinx/xilinx_dpdma.c
new file mode 100644
index 000000000000..af88a6762ef4
--- /dev/null
+++ b/drivers/dma/xilinx/xilinx_dpdma.c
@@ -0,0 +1,1533 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Xilinx ZynqMP DPDMA Engine driver
+ *
+ * Copyright (C) 2015 - 2020 Xilinx, Inc.
+ *
+ * Author: Hyun Woo Kwon <hyun.kwon@xilinx.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dmapool.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+
+#include <dt-bindings/dma/xlnx-zynqmp-dpdma.h>
+
+#include "../dmaengine.h"
+#include "../virt-dma.h"
+
+/* DPDMA registers */
+#define XILINX_DPDMA_ERR_CTRL				0x000
+#define XILINX_DPDMA_ISR				0x004
+#define XILINX_DPDMA_IMR				0x008
+#define XILINX_DPDMA_IEN				0x00c
+#define XILINX_DPDMA_IDS				0x010
+#define XILINX_DPDMA_INTR_DESC_DONE(n)			BIT((n) + 0)
+#define XILINX_DPDMA_INTR_DESC_DONE_MASK		GENMASK(5, 0)
+#define XILINX_DPDMA_INTR_NO_OSTAND(n)			BIT((n) + 6)
+#define XILINX_DPDMA_INTR_NO_OSTAND_MASK		GENMASK(11, 6)
+#define XILINX_DPDMA_INTR_AXI_ERR(n)			BIT((n) + 12)
+#define XILINX_DPDMA_INTR_AXI_ERR_MASK			GENMASK(17, 12)
+#define XILINX_DPDMA_INTR_DESC_ERR(n)			BIT((n) + 16)
+#define XILINX_DPDMA_INTR_DESC_ERR_MASK			GENMASK(23, 18)
+#define XILINX_DPDMA_INTR_WR_CMD_FIFO_FULL		BIT(24)
+#define XILINX_DPDMA_INTR_WR_DATA_FIFO_FULL		BIT(25)
+#define XILINX_DPDMA_INTR_AXI_4K_CROSS			BIT(26)
+#define XILINX_DPDMA_INTR_VSYNC				BIT(27)
+#define XILINX_DPDMA_INTR_CHAN_ERR_MASK			0x00041000
+#define XILINX_DPDMA_INTR_CHAN_ERR			0x00fff000
+#define XILINX_DPDMA_INTR_GLOBAL_ERR			0x07000000
+#define XILINX_DPDMA_INTR_ERR_ALL			0x07fff000
+#define XILINX_DPDMA_INTR_CHAN_MASK			0x00041041
+#define XILINX_DPDMA_INTR_GLOBAL_MASK			0x0f000000
+#define XILINX_DPDMA_INTR_ALL				0x0fffffff
+#define XILINX_DPDMA_EISR				0x014
+#define XILINX_DPDMA_EIMR				0x018
+#define XILINX_DPDMA_EIEN				0x01c
+#define XILINX_DPDMA_EIDS				0x020
+#define XILINX_DPDMA_EINTR_INV_APB			BIT(0)
+#define XILINX_DPDMA_EINTR_RD_AXI_ERR(n)		BIT((n) + 1)
+#define XILINX_DPDMA_EINTR_RD_AXI_ERR_MASK		GENMASK(6, 1)
+#define XILINX_DPDMA_EINTR_PRE_ERR(n)			BIT((n) + 7)
+#define XILINX_DPDMA_EINTR_PRE_ERR_MASK			GENMASK(12, 7)
+#define XILINX_DPDMA_EINTR_CRC_ERR(n)			BIT((n) + 13)
+#define XILINX_DPDMA_EINTR_CRC_ERR_MASK			GENMASK(18, 13)
+#define XILINX_DPDMA_EINTR_WR_AXI_ERR(n)		BIT((n) + 19)
+#define XILINX_DPDMA_EINTR_WR_AXI_ERR_MASK		GENMASK(24, 19)
+#define XILINX_DPDMA_EINTR_DESC_DONE_ERR(n)		BIT((n) + 25)
+#define XILINX_DPDMA_EINTR_DESC_DONE_ERR_MASK		GENMASK(30, 25)
+#define XILINX_DPDMA_EINTR_RD_CMD_FIFO_FULL		BIT(32)
+#define XILINX_DPDMA_EINTR_CHAN_ERR_MASK		0x02082082
+#define XILINX_DPDMA_EINTR_CHAN_ERR			0x7ffffffe
+#define XILINX_DPDMA_EINTR_GLOBAL_ERR			0x80000001
+#define XILINX_DPDMA_EINTR_ALL				0xffffffff
+#define XILINX_DPDMA_CNTL				0x100
+#define XILINX_DPDMA_GBL				0x104
+#define XILINX_DPDMA_GBL_TRIG_MASK(n)			((n) << 0)
+#define XILINX_DPDMA_GBL_RETRIG_MASK(n)			((n) << 6)
+#define XILINX_DPDMA_ALC0_CNTL				0x108
+#define XILINX_DPDMA_ALC0_STATUS			0x10c
+#define XILINX_DPDMA_ALC0_MAX				0x110
+#define XILINX_DPDMA_ALC0_MIN				0x114
+#define XILINX_DPDMA_ALC0_ACC				0x118
+#define XILINX_DPDMA_ALC0_ACC_TRAN			0x11c
+#define XILINX_DPDMA_ALC1_CNTL				0x120
+#define XILINX_DPDMA_ALC1_STATUS			0x124
+#define XILINX_DPDMA_ALC1_MAX				0x128
+#define XILINX_DPDMA_ALC1_MIN				0x12c
+#define XILINX_DPDMA_ALC1_ACC				0x130
+#define XILINX_DPDMA_ALC1_ACC_TRAN			0x134
+
+/* Channel register */
+#define XILINX_DPDMA_CH_BASE				0x200
+#define XILINX_DPDMA_CH_OFFSET				0x100
+#define XILINX_DPDMA_CH_DESC_START_ADDRE		0x000
+#define XILINX_DPDMA_CH_DESC_START_ADDRE_MASK		GENMASK(15, 0)
+#define XILINX_DPDMA_CH_DESC_START_ADDR			0x004
+#define XILINX_DPDMA_CH_DESC_NEXT_ADDRE			0x008
+#define XILINX_DPDMA_CH_DESC_NEXT_ADDR			0x00c
+#define XILINX_DPDMA_CH_PYLD_CUR_ADDRE			0x010
+#define XILINX_DPDMA_CH_PYLD_CUR_ADDR			0x014
+#define XILINX_DPDMA_CH_CNTL				0x018
+#define XILINX_DPDMA_CH_CNTL_ENABLE			BIT(0)
+#define XILINX_DPDMA_CH_CNTL_PAUSE			BIT(1)
+#define XILINX_DPDMA_CH_CNTL_QOS_DSCR_WR_MASK		GENMASK(5, 2)
+#define XILINX_DPDMA_CH_CNTL_QOS_DSCR_RD_MASK		GENMASK(9, 6)
+#define XILINX_DPDMA_CH_CNTL_QOS_DATA_RD_MASK		GENMASK(13, 10)
+#define XILINX_DPDMA_CH_CNTL_QOS_VID_CLASS		11
+#define XILINX_DPDMA_CH_STATUS				0x01c
+#define XILINX_DPDMA_CH_STATUS_OTRAN_CNT_MASK		GENMASK(24, 21)
+#define XILINX_DPDMA_CH_VDO				0x020
+#define XILINX_DPDMA_CH_PYLD_SZ				0x024
+#define XILINX_DPDMA_CH_DESC_ID				0x028
+
+/* DPDMA descriptor fields */
+#define XILINX_DPDMA_DESC_CONTROL_PREEMBLE		0xa5
+#define XILINX_DPDMA_DESC_CONTROL_COMPLETE_INTR		BIT(8)
+#define XILINX_DPDMA_DESC_CONTROL_DESC_UPDATE		BIT(9)
+#define XILINX_DPDMA_DESC_CONTROL_IGNORE_DONE		BIT(10)
+#define XILINX_DPDMA_DESC_CONTROL_FRAG_MODE		BIT(18)
+#define XILINX_DPDMA_DESC_CONTROL_LAST			BIT(19)
+#define XILINX_DPDMA_DESC_CONTROL_ENABLE_CRC		BIT(20)
+#define XILINX_DPDMA_DESC_CONTROL_LAST_OF_FRAME		BIT(21)
+#define XILINX_DPDMA_DESC_ID_MASK			GENMASK(15, 0)
+#define XILINX_DPDMA_DESC_HSIZE_STRIDE_HSIZE_MASK	GENMASK(17, 0)
+#define XILINX_DPDMA_DESC_HSIZE_STRIDE_STRIDE_MASK	GENMASK(31, 18)
+#define XILINX_DPDMA_DESC_ADDR_EXT_NEXT_ADDR_MASK	GENMASK(15, 0)
+#define XILINX_DPDMA_DESC_ADDR_EXT_SRC_ADDR_MASK	GENMASK(31, 16)
+
+#define XILINX_DPDMA_ALIGN_BYTES			256
+#define XILINX_DPDMA_LINESIZE_ALIGN_BITS		128
+
+#define XILINX_DPDMA_NUM_CHAN				6
+
+struct xilinx_dpdma_chan;
+
+/**
+ * struct xilinx_dpdma_hw_desc - DPDMA hardware descriptor
+ * @control: control configuration field
+ * @desc_id: descriptor ID
+ * @xfer_size: transfer size
+ * @hsize_stride: horizontal size and stride
+ * @timestamp_lsb: LSB of time stamp
+ * @timestamp_msb: MSB of time stamp
+ * @addr_ext: upper 16 bit of 48 bit address (next_desc and src_addr)
+ * @next_desc: next descriptor 32 bit address
+ * @src_addr: payload source address (1st page, 32 LSB)
+ * @addr_ext_23: payload source address (3nd and 3rd pages, 16 LSBs)
+ * @addr_ext_45: payload source address (4th and 5th pages, 16 LSBs)
+ * @src_addr2: payload source address (2nd page, 32 LSB)
+ * @src_addr3: payload source address (3rd page, 32 LSB)
+ * @src_addr4: payload source address (4th page, 32 LSB)
+ * @src_addr5: payload source address (5th page, 32 LSB)
+ * @crc: descriptor CRC
+ */
+struct xilinx_dpdma_hw_desc {
+	u32 control;
+	u32 desc_id;
+	u32 xfer_size;
+	u32 hsize_stride;
+	u32 timestamp_lsb;
+	u32 timestamp_msb;
+	u32 addr_ext;
+	u32 next_desc;
+	u32 src_addr;
+	u32 addr_ext_23;
+	u32 addr_ext_45;
+	u32 src_addr2;
+	u32 src_addr3;
+	u32 src_addr4;
+	u32 src_addr5;
+	u32 crc;
+} __aligned(XILINX_DPDMA_ALIGN_BYTES);
+
+/**
+ * struct xilinx_dpdma_sw_desc - DPDMA software descriptor
+ * @hw: DPDMA hardware descriptor
+ * @node: list node for software descriptors
+ * @dma_addr: DMA address of the software descriptor
+ */
+struct xilinx_dpdma_sw_desc {
+	struct xilinx_dpdma_hw_desc hw;
+	struct list_head node;
+	dma_addr_t dma_addr;
+};
+
+/**
+ * struct xilinx_dpdma_tx_desc - DPDMA transaction descriptor
+ * @vdesc: virtual DMA descriptor
+ * @chan: DMA channel
+ * @descriptors: list of software descriptors
+ * @error: an error has been detected with this descriptor
+ */
+struct xilinx_dpdma_tx_desc {
+	struct virt_dma_desc vdesc;
+	struct xilinx_dpdma_chan *chan;
+	struct list_head descriptors;
+	bool error;
+};
+
+#define to_dpdma_tx_desc(_desc) \
+	container_of(_desc, struct xilinx_dpdma_tx_desc, vdesc)
+
+/**
+ * struct xilinx_dpdma_chan - DPDMA channel
+ * @vchan: virtual DMA channel
+ * @reg: register base address
+ * @id: channel ID
+ * @wait_to_stop: queue to wait for outstanding transacitons before stopping
+ * @running: true if the channel is running
+ * @first_frame: flag for the first frame of stream
+ * @video_group: flag if multi-channel operation is needed for video channels
+ * @lock: lock to access struct xilinx_dpdma_chan
+ * @desc_pool: descriptor allocation pool
+ * @err_task: error IRQ bottom half handler
+ * @desc.pending: Descriptor schedule to the hardware, pending execution
+ * @desc.active: Descriptor being executed by the hardware
+ * @xdev: DPDMA device
+ */
+struct xilinx_dpdma_chan {
+	struct virt_dma_chan vchan;
+	void __iomem *reg;
+	unsigned int id;
+
+	wait_queue_head_t wait_to_stop;
+	bool running;
+	bool first_frame;
+	bool video_group;
+
+	spinlock_t lock; /* lock to access struct xilinx_dpdma_chan */
+	struct dma_pool *desc_pool;
+	struct tasklet_struct err_task;
+
+	struct {
+		struct xilinx_dpdma_tx_desc *pending;
+		struct xilinx_dpdma_tx_desc *active;
+	} desc;
+
+	struct xilinx_dpdma_device *xdev;
+};
+
+#define to_xilinx_chan(_chan) \
+	container_of(_chan, struct xilinx_dpdma_chan, vchan.chan)
+
+/**
+ * struct xilinx_dpdma_device - DPDMA device
+ * @common: generic dma device structure
+ * @reg: register base address
+ * @dev: generic device structure
+ * @irq: the interrupt number
+ * @axi_clk: axi clock
+ * @chan: DPDMA channels
+ * @ext_addr: flag for 64 bit system (48 bit addressing)
+ */
+struct xilinx_dpdma_device {
+	struct dma_device common;
+	void __iomem *reg;
+	struct device *dev;
+	int irq;
+
+	struct clk *axi_clk;
+	struct xilinx_dpdma_chan *chan[XILINX_DPDMA_NUM_CHAN];
+
+	bool ext_addr;
+};
+
+/* -----------------------------------------------------------------------------
+ * I/O Accessors
+ */
+
+static inline u32 dpdma_read(void __iomem *base, u32 offset)
+{
+	return ioread32(base + offset);
+}
+
+static inline void dpdma_write(void __iomem *base, u32 offset, u32 val)
+{
+	iowrite32(val, base + offset);
+}
+
+static inline void dpdma_clr(void __iomem *base, u32 offset, u32 clr)
+{
+	dpdma_write(base, offset, dpdma_read(base, offset) & ~clr);
+}
+
+static inline void dpdma_set(void __iomem *base, u32 offset, u32 set)
+{
+	dpdma_write(base, offset, dpdma_read(base, offset) | set);
+}
+
+/* -----------------------------------------------------------------------------
+ * Descriptor Operations
+ */
+
+/**
+ * xilinx_dpdma_sw_desc_set_dma_addrs - Set DMA addresses in the descriptor
+ * @sw_desc: The software descriptor in which to set DMA addresses
+ * @prev: The previous descriptor
+ * @dma_addr: array of dma addresses
+ * @num_src_addr: number of addresses in @dma_addr
+ *
+ * Set all the DMA addresses in the hardware descriptor corresponding to @dev
+ * from @dma_addr. If a previous descriptor is specified in @prev, its next
+ * descriptor DMA address is set to the DMA address of @sw_desc. @prev may be
+ * identical to @sw_desc for cyclic transfers.
+ */
+static void xilinx_dpdma_sw_desc_set_dma_addrs(struct xilinx_dpdma_device *xdev,
+					       struct xilinx_dpdma_sw_desc *sw_desc,
+					       struct xilinx_dpdma_sw_desc *prev,
+					       dma_addr_t dma_addr[],
+					       unsigned int num_src_addr)
+{
+	struct xilinx_dpdma_hw_desc *hw_desc = &sw_desc->hw;
+	unsigned int i;
+
+	hw_desc->src_addr = lower_32_bits(dma_addr[0]);
+	if (xdev->ext_addr)
+		hw_desc->addr_ext |=
+			FIELD_PREP(XILINX_DPDMA_DESC_ADDR_EXT_SRC_ADDR_MASK,
+				   upper_32_bits(dma_addr[0]));
+
+	for (i = 1; i < num_src_addr; i++) {
+		u32 *addr = &hw_desc->src_addr2;
+
+		addr[i-1] = lower_32_bits(dma_addr[i]);
+
+		if (xdev->ext_addr) {
+			u32 *addr_ext = &hw_desc->addr_ext_23;
+			u32 addr_msb;
+
+			addr_msb = upper_32_bits(dma_addr[i]) & GENMASK(15, 0);
+			addr_msb <<= 16 * ((i - 1) % 2);
+			addr_ext[(i - 1) / 2] |= addr_msb;
+		}
+	}
+
+	if (!prev)
+		return;
+
+	prev->hw.next_desc = lower_32_bits(sw_desc->dma_addr);
+	if (xdev->ext_addr)
+		prev->hw.addr_ext |=
+			FIELD_PREP(XILINX_DPDMA_DESC_ADDR_EXT_NEXT_ADDR_MASK,
+				   upper_32_bits(sw_desc->dma_addr));
+}
+
+/**
+ * xilinx_dpdma_chan_alloc_sw_desc - Allocate a software descriptor
+ * @chan: DPDMA channel
+ *
+ * Allocate a software descriptor from the channel's descriptor pool.
+ *
+ * Return: a software descriptor or NULL.
+ */
+static struct xilinx_dpdma_sw_desc *
+xilinx_dpdma_chan_alloc_sw_desc(struct xilinx_dpdma_chan *chan)
+{
+	struct xilinx_dpdma_sw_desc *sw_desc;
+	dma_addr_t dma_addr;
+
+	sw_desc = dma_pool_zalloc(chan->desc_pool, GFP_ATOMIC, &dma_addr);
+	if (!sw_desc)
+		return NULL;
+
+	sw_desc->dma_addr = dma_addr;
+
+	return sw_desc;
+}
+
+/**
+ * xilinx_dpdma_chan_free_sw_desc - Free a software descriptor
+ * @chan: DPDMA channel
+ * @sw_desc: software descriptor to free
+ *
+ * Free a software descriptor from the channel's descriptor pool.
+ */
+static void
+xilinx_dpdma_chan_free_sw_desc(struct xilinx_dpdma_chan *chan,
+			       struct xilinx_dpdma_sw_desc *sw_desc)
+{
+	dma_pool_free(chan->desc_pool, sw_desc, sw_desc->dma_addr);
+}
+
+/**
+ * xilinx_dpdma_chan_dump_tx_desc - Dump a tx descriptor
+ * @chan: DPDMA channel
+ * @tx_desc: tx descriptor to dump
+ *
+ * Dump contents of a tx descriptor
+ */
+static void xilinx_dpdma_chan_dump_tx_desc(struct xilinx_dpdma_chan *chan,
+					   struct xilinx_dpdma_tx_desc *tx_desc)
+{
+	struct xilinx_dpdma_sw_desc *sw_desc;
+	struct device *dev = chan->xdev->dev;
+	unsigned int i = 0;
+
+	dev_dbg(dev, "------- TX descriptor dump start -------\n");
+	dev_dbg(dev, "------- channel ID = %d -------\n", chan->id);
+
+	list_for_each_entry(sw_desc, &tx_desc->descriptors, node) {
+		struct xilinx_dpdma_hw_desc *hw_desc = &sw_desc->hw;
+
+		dev_dbg(dev, "------- HW descriptor %d -------\n", i++);
+		dev_dbg(dev, "descriptor DMA addr: %pad\n", &sw_desc->dma_addr);
+		dev_dbg(dev, "control: 0x%08x\n", hw_desc->control);
+		dev_dbg(dev, "desc_id: 0x%08x\n", hw_desc->desc_id);
+		dev_dbg(dev, "xfer_size: 0x%08x\n", hw_desc->xfer_size);
+		dev_dbg(dev, "hsize_stride: 0x%08x\n", hw_desc->hsize_stride);
+		dev_dbg(dev, "timestamp_lsb: 0x%08x\n", hw_desc->timestamp_lsb);
+		dev_dbg(dev, "timestamp_msb: 0x%08x\n", hw_desc->timestamp_msb);
+		dev_dbg(dev, "addr_ext: 0x%08x\n", hw_desc->addr_ext);
+		dev_dbg(dev, "next_desc: 0x%08x\n", hw_desc->next_desc);
+		dev_dbg(dev, "src_addr: 0x%08x\n", hw_desc->src_addr);
+		dev_dbg(dev, "addr_ext_23: 0x%08x\n", hw_desc->addr_ext_23);
+		dev_dbg(dev, "addr_ext_45: 0x%08x\n", hw_desc->addr_ext_45);
+		dev_dbg(dev, "src_addr2: 0x%08x\n", hw_desc->src_addr2);
+		dev_dbg(dev, "src_addr3: 0x%08x\n", hw_desc->src_addr3);
+		dev_dbg(dev, "src_addr4: 0x%08x\n", hw_desc->src_addr4);
+		dev_dbg(dev, "src_addr5: 0x%08x\n", hw_desc->src_addr5);
+		dev_dbg(dev, "crc: 0x%08x\n", hw_desc->crc);
+	}
+
+	dev_dbg(dev, "------- TX descriptor dump end -------\n");
+}
+
+/**
+ * xilinx_dpdma_chan_alloc_tx_desc - Allocate a transaction descriptor
+ * @chan: DPDMA channel
+ *
+ * Allocate a tx descriptor.
+ *
+ * Return: a tx descriptor or NULL.
+ */
+static struct xilinx_dpdma_tx_desc *
+xilinx_dpdma_chan_alloc_tx_desc(struct xilinx_dpdma_chan *chan)
+{
+	struct xilinx_dpdma_tx_desc *tx_desc;
+
+	tx_desc = kzalloc(sizeof(*tx_desc), GFP_NOWAIT);
+	if (!tx_desc)
+		return NULL;
+
+	INIT_LIST_HEAD(&tx_desc->descriptors);
+	tx_desc->chan = chan;
+	tx_desc->error = false;
+
+	return tx_desc;
+}
+
+/**
+ * xilinx_dpdma_chan_free_tx_desc - Free a virtual DMA descriptor
+ * @vdesc: virtual DMA descriptor
+ *
+ * Free the virtual DMA descriptor @vdesc including its software descriptors.
+ */
+static void xilinx_dpdma_chan_free_tx_desc(struct virt_dma_desc *vdesc)
+{
+	struct xilinx_dpdma_sw_desc *sw_desc, *next;
+	struct xilinx_dpdma_tx_desc *desc;
+
+	if (!vdesc)
+		return;
+
+	desc = to_dpdma_tx_desc(vdesc);
+
+	list_for_each_entry_safe(sw_desc, next, &desc->descriptors, node) {
+		list_del(&sw_desc->node);
+		xilinx_dpdma_chan_free_sw_desc(desc->chan, sw_desc);
+	}
+
+	kfree(desc);
+}
+
+/**
+ * xilinx_dpdma_chan_prep_interleaved_dma - Prepare an interleaved dma
+ *					    descriptor
+ * @chan: DPDMA channel
+ * @xt: dma interleaved template
+ *
+ * Prepare a tx descriptor including internal software/hardware descriptors
+ * based on @xt.
+ *
+ * Return: A DPDMA TX descriptor on success, or NULL.
+ */
+static struct xilinx_dpdma_tx_desc *
+xilinx_dpdma_chan_prep_interleaved_dma(struct xilinx_dpdma_chan *chan,
+				       struct dma_interleaved_template *xt)
+{
+	struct xilinx_dpdma_tx_desc *tx_desc;
+	struct xilinx_dpdma_sw_desc *sw_desc;
+	struct xilinx_dpdma_hw_desc *hw_desc;
+	size_t hsize = xt->sgl[0].size;
+	size_t stride = hsize + xt->sgl[0].icg;
+
+	if (!IS_ALIGNED(xt->src_start, XILINX_DPDMA_ALIGN_BYTES)) {
+		dev_err(chan->xdev->dev, "buffer should be aligned at %d B\n",
+			XILINX_DPDMA_ALIGN_BYTES);
+		return NULL;
+	}
+
+	tx_desc = xilinx_dpdma_chan_alloc_tx_desc(chan);
+	if (!tx_desc)
+		return NULL;
+
+	sw_desc = xilinx_dpdma_chan_alloc_sw_desc(chan);
+	if (!sw_desc) {
+		xilinx_dpdma_chan_free_tx_desc(&tx_desc->vdesc);
+		return NULL;
+	}
+
+	xilinx_dpdma_sw_desc_set_dma_addrs(chan->xdev, sw_desc, sw_desc,
+					   &xt->src_start, 1);
+
+	hw_desc = &sw_desc->hw;
+	hsize = ALIGN(hsize, XILINX_DPDMA_LINESIZE_ALIGN_BITS / 8);
+	hw_desc->xfer_size = hsize * xt->numf;
+	hw_desc->hsize_stride =
+		FIELD_PREP(XILINX_DPDMA_DESC_HSIZE_STRIDE_HSIZE_MASK, hsize) |
+		FIELD_PREP(XILINX_DPDMA_DESC_HSIZE_STRIDE_STRIDE_MASK,
+			   stride / 16);
+	hw_desc->control |= XILINX_DPDMA_DESC_CONTROL_PREEMBLE;
+	hw_desc->control |= XILINX_DPDMA_DESC_CONTROL_COMPLETE_INTR;
+	hw_desc->control |= XILINX_DPDMA_DESC_CONTROL_IGNORE_DONE;
+	hw_desc->control |= XILINX_DPDMA_DESC_CONTROL_LAST_OF_FRAME;
+
+	list_add_tail(&sw_desc->node, &tx_desc->descriptors);
+
+	return tx_desc;
+}
+
+/* -----------------------------------------------------------------------------
+ * DPDMA Channel Operations
+ */
+
+/**
+ * xilinx_dpdma_chan_enable - Enable the channel
+ * @chan: DPDMA channel
+ *
+ * Enable the channel and its interrupts. Set the QoS values for video class.
+ */
+static void xilinx_dpdma_chan_enable(struct xilinx_dpdma_chan *chan)
+{
+	u32 reg;
+
+	reg = (XILINX_DPDMA_INTR_CHAN_MASK << chan->id)
+	    | XILINX_DPDMA_INTR_GLOBAL_MASK;
+	dpdma_write(chan->xdev->reg, XILINX_DPDMA_IEN, reg);
+	reg = (XILINX_DPDMA_EINTR_CHAN_ERR_MASK << chan->id)
+	    | XILINX_DPDMA_INTR_GLOBAL_ERR;
+	dpdma_write(chan->xdev->reg, XILINX_DPDMA_EIEN, reg);
+
+	reg = XILINX_DPDMA_CH_CNTL_ENABLE
+	    | FIELD_PREP(XILINX_DPDMA_CH_CNTL_QOS_DSCR_WR_MASK,
+			 XILINX_DPDMA_CH_CNTL_QOS_VID_CLASS)
+	    | FIELD_PREP(XILINX_DPDMA_CH_CNTL_QOS_DSCR_RD_MASK,
+			 XILINX_DPDMA_CH_CNTL_QOS_VID_CLASS)
+	    | FIELD_PREP(XILINX_DPDMA_CH_CNTL_QOS_DATA_RD_MASK,
+			 XILINX_DPDMA_CH_CNTL_QOS_VID_CLASS);
+	dpdma_set(chan->reg, XILINX_DPDMA_CH_CNTL, reg);
+}
+
+/**
+ * xilinx_dpdma_chan_disable - Disable the channel
+ * @chan: DPDMA channel
+ *
+ * Disable the channel and its interrupts.
+ */
+static void xilinx_dpdma_chan_disable(struct xilinx_dpdma_chan *chan)
+{
+	u32 reg;
+
+	reg = XILINX_DPDMA_INTR_CHAN_MASK << chan->id;
+	dpdma_write(chan->xdev->reg, XILINX_DPDMA_IEN, reg);
+	reg = XILINX_DPDMA_EINTR_CHAN_ERR_MASK << chan->id;
+	dpdma_write(chan->xdev->reg, XILINX_DPDMA_EIEN, reg);
+
+	dpdma_clr(chan->reg, XILINX_DPDMA_CH_CNTL, XILINX_DPDMA_CH_CNTL_ENABLE);
+}
+
+/**
+ * xilinx_dpdma_chan_pause - Pause the channel
+ * @chan: DPDMA channel
+ *
+ * Pause the channel.
+ */
+static void xilinx_dpdma_chan_pause(struct xilinx_dpdma_chan *chan)
+{
+	dpdma_set(chan->reg, XILINX_DPDMA_CH_CNTL, XILINX_DPDMA_CH_CNTL_PAUSE);
+}
+
+/**
+ * xilinx_dpdma_chan_unpause - Unpause the channel
+ * @chan: DPDMA channel
+ *
+ * Unpause the channel.
+ */
+static void xilinx_dpdma_chan_unpause(struct xilinx_dpdma_chan *chan)
+{
+	dpdma_clr(chan->reg, XILINX_DPDMA_CH_CNTL, XILINX_DPDMA_CH_CNTL_PAUSE);
+}
+
+static u32 xilinx_dpdma_chan_video_group_ready(struct xilinx_dpdma_chan *chan)
+{
+	struct xilinx_dpdma_device *xdev = chan->xdev;
+	u32 channels = 0;
+	unsigned int i;
+
+	for (i = ZYNQMP_DPDMA_VIDEO0; i <= ZYNQMP_DPDMA_VIDEO2; i++) {
+		if (xdev->chan[i]->video_group && !xdev->chan[i]->running)
+			return 0;
+
+		if (xdev->chan[i]->video_group)
+			channels |= BIT(i);
+	}
+
+	return channels;
+}
+
+/**
+ * xilinx_dpdma_chan_queue_transfer - Queue the next transfer
+ * @chan: DPDMA channel
+ *
+ * Queue the next descriptor, if any, to the hardware. If the channel is
+ * stopped, start it first. Otherwise retrigger it with the next descriptor.
+ */
+static void xilinx_dpdma_chan_queue_transfer(struct xilinx_dpdma_chan *chan)
+{
+	struct xilinx_dpdma_device *xdev = chan->xdev;
+	struct xilinx_dpdma_sw_desc *sw_desc;
+	struct xilinx_dpdma_tx_desc *desc;
+	struct virt_dma_desc *vdesc;
+	u32 reg, channels;
+
+	lockdep_assert_held(&chan->lock);
+
+	if (chan->desc.pending)
+		return;
+
+	if (!chan->running) {
+		xilinx_dpdma_chan_unpause(chan);
+		xilinx_dpdma_chan_enable(chan);
+		chan->first_frame = true;
+		chan->running = true;
+	}
+
+	if (chan->video_group)
+		channels = xilinx_dpdma_chan_video_group_ready(chan);
+	else
+		channels = BIT(chan->id);
+
+	if (!channels)
+		return;
+
+	vdesc = vchan_next_desc(&chan->vchan);
+	if (!vdesc)
+		return;
+
+	desc = to_dpdma_tx_desc(vdesc);
+	chan->desc.pending = desc;
+	list_del(&desc->vdesc.node);
+
+	/*
+	 * Assign the cookie to descriptors in this transaction. Only 16 bit
+	 * will be used, but it should be enough.
+	 */
+	list_for_each_entry(sw_desc, &desc->descriptors, node)
+		sw_desc->hw.desc_id = desc->vdesc.tx.cookie;
+
+	sw_desc = list_first_entry(&desc->descriptors,
+				   struct xilinx_dpdma_sw_desc, node);
+	dpdma_write(chan->reg, XILINX_DPDMA_CH_DESC_START_ADDR,
+		    lower_32_bits(sw_desc->dma_addr));
+	if (xdev->ext_addr)
+		dpdma_write(chan->reg, XILINX_DPDMA_CH_DESC_START_ADDRE,
+			    FIELD_PREP(XILINX_DPDMA_CH_DESC_START_ADDRE_MASK,
+				       upper_32_bits(sw_desc->dma_addr)));
+
+	if (chan->first_frame)
+		reg = XILINX_DPDMA_GBL_TRIG_MASK(channels);
+	else
+		reg = XILINX_DPDMA_GBL_RETRIG_MASK(channels);
+
+	chan->first_frame = false;
+
+	dpdma_write(xdev->reg, XILINX_DPDMA_GBL, reg);
+}
+
+/**
+ * xilinx_dpdma_chan_ostand - Number of outstanding transactions
+ * @chan: DPDMA channel
+ *
+ * Read and return the number of outstanding transactions from register.
+ *
+ * Return: Number of outstanding transactions from the status register.
+ */
+static u32 xilinx_dpdma_chan_ostand(struct xilinx_dpdma_chan *chan)
+{
+	return FIELD_GET(XILINX_DPDMA_CH_STATUS_OTRAN_CNT_MASK,
+			 dpdma_read(chan->reg, XILINX_DPDMA_CH_STATUS));
+}
+
+/**
+ * xilinx_dpdma_chan_no_ostand - Notify no outstanding transaction event
+ * @chan: DPDMA channel
+ *
+ * Notify waiters for no outstanding event, so waiters can stop the channel
+ * safely. This function is supposed to be called when 'no outstanding'
+ * interrupt is generated. The 'no outstanding' interrupt is disabled and
+ * should be re-enabled when this event is handled. If the channel status
+ * register still shows some number of outstanding transactions, the interrupt
+ * remains enabled.
+ *
+ * Return: 0 on success. On failure, -EWOULDBLOCK if there's still outstanding
+ * transaction(s).
+ */
+static int xilinx_dpdma_chan_notify_no_ostand(struct xilinx_dpdma_chan *chan)
+{
+	u32 cnt;
+
+	cnt = xilinx_dpdma_chan_ostand(chan);
+	if (cnt) {
+		dev_dbg(chan->xdev->dev, "%d outstanding transactions\n", cnt);
+		return -EWOULDBLOCK;
+	}
+
+	/* Disable 'no outstanding' interrupt */
+	dpdma_write(chan->xdev->reg, XILINX_DPDMA_IDS,
+		    XILINX_DPDMA_INTR_NO_OSTAND(chan->id));
+	wake_up(&chan->wait_to_stop);
+
+	return 0;
+}
+
+/**
+ * xilinx_dpdma_chan_wait_no_ostand - Wait for the no outstanding irq
+ * @chan: DPDMA channel
+ *
+ * Wait for the no outstanding transaction interrupt. This functions can sleep
+ * for 50ms.
+ *
+ * Return: 0 on success. On failure, -ETIMEOUT for time out, or the error code
+ * from wait_event_interruptible_timeout().
+ */
+static int xilinx_dpdma_chan_wait_no_ostand(struct xilinx_dpdma_chan *chan)
+{
+	int ret;
+
+	/* Wait for a no outstanding transaction interrupt upto 50msec */
+	ret = wait_event_interruptible_timeout(chan->wait_to_stop,
+					       !xilinx_dpdma_chan_ostand(chan),
+					       msecs_to_jiffies(50));
+	if (ret > 0) {
+		dpdma_write(chan->xdev->reg, XILINX_DPDMA_IEN,
+			    XILINX_DPDMA_INTR_NO_OSTAND(chan->id));
+		return 0;
+	}
+
+	dev_err(chan->xdev->dev, "not ready to stop: %d trans\n",
+		xilinx_dpdma_chan_ostand(chan));
+
+	if (ret == 0)
+		return -ETIMEDOUT;
+
+	return ret;
+}
+
+/**
+ * xilinx_dpdma_chan_poll_no_ostand - Poll the outstanding transaction status
+ * @chan: DPDMA channel
+ *
+ * Poll the outstanding transaction status, and return when there's no
+ * outstanding transaction. This functions can be used in the interrupt context
+ * or where the atomicity is required. Calling thread may wait more than 50ms.
+ *
+ * Return: 0 on success, or -ETIMEDOUT.
+ */
+static int xilinx_dpdma_chan_poll_no_ostand(struct xilinx_dpdma_chan *chan)
+{
+	u32 cnt, loop = 50000;
+
+	/* Poll at least for 50ms (20 fps). */
+	do {
+		cnt = xilinx_dpdma_chan_ostand(chan);
+		udelay(1);
+	} while (loop-- > 0 && cnt);
+
+	if (loop) {
+		dpdma_write(chan->xdev->reg, XILINX_DPDMA_IEN,
+			    XILINX_DPDMA_INTR_NO_OSTAND(chan->id));
+		return 0;
+	}
+
+	dev_err(chan->xdev->dev, "not ready to stop: %d trans\n",
+		xilinx_dpdma_chan_ostand(chan));
+
+	return -ETIMEDOUT;
+}
+
+/**
+ * xilinx_dpdma_chan_stop - Stop the channel
+ * @chan: DPDMA channel
+ *
+ * Stop a previously paused channel by first waiting for completion of all
+ * outstanding transaction and then disabling the channel.
+ *
+ * Return: 0 on success, or -ETIMEDOUT if the channel failed to stop.
+ */
+static int xilinx_dpdma_chan_stop(struct xilinx_dpdma_chan *chan)
+{
+	unsigned long flags;
+	int ret;
+
+	ret = xilinx_dpdma_chan_wait_no_ostand(chan);
+	if (ret)
+		return ret;
+
+	spin_lock_irqsave(&chan->lock, flags);
+	xilinx_dpdma_chan_disable(chan);
+	chan->running = false;
+	spin_unlock_irqrestore(&chan->lock, flags);
+
+	return 0;
+}
+
+/**
+ * xilinx_dpdma_chan_done_irq - Handle hardware descriptor completion
+ * @chan: DPDMA channel
+ *
+ * Handle completion of the currently active descriptor (@chan->desc.active). As
+ * we currently support cyclic transfers only, this just invokes the cyclic
+ * callback. The descriptor will be completed at the VSYNC interrupt when a new
+ * descriptor replaces it.
+ */
+static void xilinx_dpdma_chan_done_irq(struct xilinx_dpdma_chan *chan)
+{
+	struct xilinx_dpdma_tx_desc *active = chan->desc.active;
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->lock, flags);
+
+	if (active)
+		vchan_cyclic_callback(&active->vdesc);
+	else
+		dev_warn(chan->xdev->dev,
+			 "DONE IRQ with no active descriptor!\n");
+
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+/**
+ * xilinx_dpdma_chan_vsync_irq - Handle hardware descriptor scheduling
+ * @chan: DPDMA channel
+ *
+ * At VSYNC the active descriptor may have been replaced by the pending
+ * descriptor. Detect this through the DESC_ID and perform appropriate
+ * bookkeeping.
+ */
+static void xilinx_dpdma_chan_vsync_irq(struct  xilinx_dpdma_chan *chan)
+{
+	struct xilinx_dpdma_tx_desc *pending;
+	struct xilinx_dpdma_sw_desc *sw_desc;
+	unsigned long flags;
+	u32 desc_id;
+
+	spin_lock_irqsave(&chan->lock, flags);
+
+	pending = chan->desc.pending;
+	if (!chan->running || !pending)
+		goto out;
+
+	desc_id = dpdma_read(chan->reg, XILINX_DPDMA_CH_DESC_ID);
+
+	/* If the retrigger raced with vsync, retry at the next frame. */
+	sw_desc = list_first_entry(&pending->descriptors,
+				   struct xilinx_dpdma_sw_desc, node);
+	if (sw_desc->hw.desc_id != desc_id)
+		goto out;
+
+	/*
+	 * Complete the active descriptor, if any, promote the pending
+	 * descriptor to active, and queue the next transfer, if any.
+	 */
+	if (chan->desc.active)
+		vchan_cookie_complete(&chan->desc.active->vdesc);
+	chan->desc.active = pending;
+	chan->desc.pending = NULL;
+
+	xilinx_dpdma_chan_queue_transfer(chan);
+
+out:
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+/**
+ * xilinx_dpdma_chan_err - Detect any channel error
+ * @chan: DPDMA channel
+ * @isr: masked Interrupt Status Register
+ * @eisr: Error Interrupt Status Register
+ *
+ * Return: true if any channel error occurs, or false otherwise.
+ */
+static bool
+xilinx_dpdma_chan_err(struct xilinx_dpdma_chan *chan, u32 isr, u32 eisr)
+{
+	if (!chan)
+		return false;
+
+	if (chan->running &&
+	    ((isr & (XILINX_DPDMA_INTR_CHAN_ERR_MASK << chan->id)) ||
+	    (eisr & (XILINX_DPDMA_EINTR_CHAN_ERR_MASK << chan->id))))
+		return true;
+
+	return false;
+}
+
+/**
+ * xilinx_dpdma_chan_handle_err - DPDMA channel error handling
+ * @chan: DPDMA channel
+ *
+ * This function is called when any channel error or any global error occurs.
+ * The function disables the paused channel by errors and determines
+ * if the current active descriptor can be rescheduled depending on
+ * the descriptor status.
+ */
+static void xilinx_dpdma_chan_handle_err(struct xilinx_dpdma_chan *chan)
+{
+	struct xilinx_dpdma_device *xdev = chan->xdev;
+	struct xilinx_dpdma_tx_desc *active;
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->lock, flags);
+
+	dev_dbg(xdev->dev, "cur desc addr = 0x%04x%08x\n",
+		dpdma_read(chan->reg, XILINX_DPDMA_CH_DESC_START_ADDRE),
+		dpdma_read(chan->reg, XILINX_DPDMA_CH_DESC_START_ADDR));
+	dev_dbg(xdev->dev, "cur payload addr = 0x%04x%08x\n",
+		dpdma_read(chan->reg, XILINX_DPDMA_CH_PYLD_CUR_ADDRE),
+		dpdma_read(chan->reg, XILINX_DPDMA_CH_PYLD_CUR_ADDR));
+
+	xilinx_dpdma_chan_disable(chan);
+	chan->running = false;
+
+	if (!chan->desc.active)
+		goto out_unlock;
+
+	active = chan->desc.active;
+	chan->desc.active = NULL;
+
+	xilinx_dpdma_chan_dump_tx_desc(chan, active);
+
+	if (active->error)
+		dev_dbg(xdev->dev, "repeated error on desc\n");
+
+	/* Reschedule if there's no new descriptor */
+	if (!chan->desc.pending &&
+	    list_empty(&chan->vchan.desc_issued)) {
+		active->error = true;
+		list_add_tail(&active->vdesc.node,
+			      &chan->vchan.desc_issued);
+	} else {
+		xilinx_dpdma_chan_free_tx_desc(&active->vdesc);
+	}
+
+out_unlock:
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+/* -----------------------------------------------------------------------------
+ * DMA Engine Operations
+ */
+
+static struct dma_async_tx_descriptor *
+xilinx_dpdma_prep_interleaved_dma(struct dma_chan *dchan,
+				  struct dma_interleaved_template *xt,
+				  unsigned long flags)
+{
+	struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
+	struct xilinx_dpdma_tx_desc *desc;
+
+	if (xt->dir != DMA_MEM_TO_DEV)
+		return NULL;
+
+	if (!xt->numf || !xt->sgl[0].size)
+		return NULL;
+
+	if (!(flags & DMA_PREP_REPEAT) || !(flags & DMA_PREP_LOAD_EOT))
+		return NULL;
+
+	desc = xilinx_dpdma_chan_prep_interleaved_dma(chan, xt);
+	if (!desc)
+		return NULL;
+
+	vchan_tx_prep(&chan->vchan, &desc->vdesc, flags | DMA_CTRL_ACK);
+
+	return &desc->vdesc.tx;
+}
+
+/**
+ * xilinx_dpdma_alloc_chan_resources - Allocate resources for the channel
+ * @dchan: DMA channel
+ *
+ * Allocate a descriptor pool for the channel.
+ *
+ * Return: 0 on success, or -ENOMEM if failed to allocate a pool.
+ */
+static int xilinx_dpdma_alloc_chan_resources(struct dma_chan *dchan)
+{
+	struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
+	size_t align = __alignof__(struct xilinx_dpdma_sw_desc);
+
+	chan->desc_pool = dma_pool_create(dev_name(chan->xdev->dev),
+					  chan->xdev->dev,
+					  sizeof(struct xilinx_dpdma_sw_desc),
+					  align, 0);
+	if (!chan->desc_pool) {
+		dev_err(chan->xdev->dev,
+			"failed to allocate a descriptor pool\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/**
+ * xilinx_dpdma_free_chan_resources - Free all resources for the channel
+ * @dchan: DMA channel
+ *
+ * Free resources associated with the virtual DMA channel, and destroy the
+ * descriptor pool.
+ */
+static void xilinx_dpdma_free_chan_resources(struct dma_chan *dchan)
+{
+	struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
+
+	vchan_free_chan_resources(&chan->vchan);
+
+	dma_pool_destroy(chan->desc_pool);
+	chan->desc_pool = NULL;
+}
+
+static void xilinx_dpdma_issue_pending(struct dma_chan *dchan)
+{
+	struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	if (vchan_issue_pending(&chan->vchan))
+		xilinx_dpdma_chan_queue_transfer(chan);
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+}
+
+static int xilinx_dpdma_config(struct dma_chan *dchan,
+			       struct dma_slave_config *config)
+{
+	struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
+	unsigned long flags;
+
+	/*
+	 * The destination address doesn't need to be specified as the DPDMA is
+	 * hardwired to the destination (the DP controller). The transfer
+	 * width, burst size and port window size are thus meaningless, they're
+	 * fixed both on the DPDMA side and on the DP controller side.
+	 */
+
+	spin_lock_irqsave(&chan->lock, flags);
+
+	/*
+	 * Abuse the slave_id to indicate that the channel is part of a video
+	 * group.
+	 */
+	if (chan->id >= ZYNQMP_DPDMA_VIDEO0 && chan->id <= ZYNQMP_DPDMA_VIDEO2)
+		chan->video_group = config->slave_id != 0;
+
+	spin_unlock_irqrestore(&chan->lock, flags);
+
+	return 0;
+}
+
+static int xilinx_dpdma_pause(struct dma_chan *dchan)
+{
+	xilinx_dpdma_chan_pause(to_xilinx_chan(dchan));
+
+	return 0;
+}
+
+static int xilinx_dpdma_resume(struct dma_chan *dchan)
+{
+	xilinx_dpdma_chan_unpause(to_xilinx_chan(dchan));
+
+	return 0;
+}
+
+/**
+ * xilinx_dpdma_terminate_all - Terminate the channel and descriptors
+ * @dchan: DMA channel
+ *
+ * Pause the channel without waiting for ongoing transfers to complete. Waiting
+ * for completion is performed by xilinx_dpdma_synchronize() that will disable
+ * the channel to complete the stop.
+ *
+ * All the descriptors associated with the channel that are guaranteed not to
+ * be touched by the hardware. The pending and active descriptor are not
+ * touched, and will be freed either upon completion, or by
+ * xilinx_dpdma_synchronize().
+ *
+ * Return: 0 on success, or -ETIMEDOUT if the channel failed to stop.
+ */
+static int xilinx_dpdma_terminate_all(struct dma_chan *dchan)
+{
+	struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
+	struct xilinx_dpdma_device *xdev = chan->xdev;
+	LIST_HEAD(descriptors);
+	unsigned long flags;
+	unsigned int i;
+
+	/* Pause the channel (including the whole video group if applicable). */
+	if (chan->video_group) {
+		for (i = ZYNQMP_DPDMA_VIDEO0; i <= ZYNQMP_DPDMA_VIDEO2; i++) {
+			if (xdev->chan[i]->video_group &&
+			    xdev->chan[i]->running) {
+				xilinx_dpdma_chan_pause(xdev->chan[i]);
+				xdev->chan[i]->video_group = false;
+			}
+		}
+	} else {
+		xilinx_dpdma_chan_pause(chan);
+	}
+
+	/* Gather all the descriptors we can free and free them. */
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	vchan_get_all_descriptors(&chan->vchan, &descriptors);
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+
+	vchan_dma_desc_free_list(&chan->vchan, &descriptors);
+
+	return 0;
+}
+
+/**
+ * xilinx_dpdma_synchronize - Synchronize callback execution
+ * @dchan: DMA channel
+ *
+ * Synchronizing callback execution ensures that all previously issued
+ * transfers have completed and all associated callbacks have been called and
+ * have returned.
+ *
+ * This function waits for the DMA channel to stop. It assumes it has been
+ * paused by a previous call to dmaengine_terminate_async(), and that no new
+ * pending descriptors have been issued with dma_async_issue_pending(). The
+ * behaviour is undefined otherwise.
+ */
+static void xilinx_dpdma_synchronize(struct dma_chan *dchan)
+{
+	struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
+	unsigned long flags;
+
+	xilinx_dpdma_chan_stop(chan);
+
+	spin_lock_irqsave(&chan->vchan.lock, flags);
+	if (chan->desc.pending) {
+		vchan_terminate_vdesc(&chan->desc.pending->vdesc);
+		chan->desc.pending = NULL;
+	}
+	if (chan->desc.active) {
+		vchan_terminate_vdesc(&chan->desc.active->vdesc);
+		chan->desc.active = NULL;
+	}
+	spin_unlock_irqrestore(&chan->vchan.lock, flags);
+
+	vchan_synchronize(&chan->vchan);
+}
+
+/* -----------------------------------------------------------------------------
+ * Interrupt and Tasklet Handling
+ */
+
+/**
+ * xilinx_dpdma_err - Detect any global error
+ * @isr: Interrupt Status Register
+ * @eisr: Error Interrupt Status Register
+ *
+ * Return: True if any global error occurs, or false otherwise.
+ */
+static bool xilinx_dpdma_err(u32 isr, u32 eisr)
+{
+	if (isr & XILINX_DPDMA_INTR_GLOBAL_ERR ||
+	    eisr & XILINX_DPDMA_EINTR_GLOBAL_ERR)
+		return true;
+
+	return false;
+}
+
+/**
+ * xilinx_dpdma_handle_err_irq - Handle DPDMA error interrupt
+ * @xdev: DPDMA device
+ * @isr: masked Interrupt Status Register
+ * @eisr: Error Interrupt Status Register
+ *
+ * Handle if any error occurs based on @isr and @eisr. This function disables
+ * corresponding error interrupts, and those should be re-enabled once handling
+ * is done.
+ */
+static void xilinx_dpdma_handle_err_irq(struct xilinx_dpdma_device *xdev,
+					u32 isr, u32 eisr)
+{
+	bool err = xilinx_dpdma_err(isr, eisr);
+	unsigned int i;
+
+	dev_dbg_ratelimited(xdev->dev,
+			    "error irq: isr = 0x%08x, eisr = 0x%08x\n",
+			    isr, eisr);
+
+	/* Disable channel error interrupts until errors are handled. */
+	dpdma_write(xdev->reg, XILINX_DPDMA_IDS,
+		    isr & ~XILINX_DPDMA_INTR_GLOBAL_ERR);
+	dpdma_write(xdev->reg, XILINX_DPDMA_EIDS,
+		    eisr & ~XILINX_DPDMA_EINTR_GLOBAL_ERR);
+
+	for (i = 0; i < ARRAY_SIZE(xdev->chan); i++)
+		if (err || xilinx_dpdma_chan_err(xdev->chan[i], isr, eisr))
+			tasklet_schedule(&xdev->chan[i]->err_task);
+}
+
+/**
+ * xilinx_dpdma_enable_irq - Enable interrupts
+ * @xdev: DPDMA device
+ *
+ * Enable interrupts.
+ */
+static void xilinx_dpdma_enable_irq(struct xilinx_dpdma_device *xdev)
+{
+	dpdma_write(xdev->reg, XILINX_DPDMA_IEN, XILINX_DPDMA_INTR_ALL);
+	dpdma_write(xdev->reg, XILINX_DPDMA_EIEN, XILINX_DPDMA_EINTR_ALL);
+}
+
+/**
+ * xilinx_dpdma_disable_irq - Disable interrupts
+ * @xdev: DPDMA device
+ *
+ * Disable interrupts.
+ */
+static void xilinx_dpdma_disable_irq(struct xilinx_dpdma_device *xdev)
+{
+	dpdma_write(xdev->reg, XILINX_DPDMA_IDS, XILINX_DPDMA_INTR_ERR_ALL);
+	dpdma_write(xdev->reg, XILINX_DPDMA_EIDS, XILINX_DPDMA_EINTR_ALL);
+}
+
+/**
+ * xilinx_dpdma_chan_err_task - Per channel tasklet for error handling
+ * @data: tasklet data to be casted to DPDMA channel structure
+ *
+ * Per channel error handling tasklet. This function waits for the outstanding
+ * transaction to complete and triggers error handling. After error handling,
+ * re-enable channel error interrupts, and restart the channel if needed.
+ */
+static void xilinx_dpdma_chan_err_task(unsigned long data)
+{
+	struct xilinx_dpdma_chan *chan = (struct xilinx_dpdma_chan *)data;
+	struct xilinx_dpdma_device *xdev = chan->xdev;
+	unsigned long flags;
+
+	/* Proceed error handling even when polling fails. */
+	xilinx_dpdma_chan_poll_no_ostand(chan);
+
+	xilinx_dpdma_chan_handle_err(chan);
+
+	dpdma_write(xdev->reg, XILINX_DPDMA_IEN,
+		    XILINX_DPDMA_INTR_CHAN_ERR_MASK << chan->id);
+	dpdma_write(xdev->reg, XILINX_DPDMA_EIEN,
+		    XILINX_DPDMA_EINTR_CHAN_ERR_MASK << chan->id);
+
+	spin_lock_irqsave(&chan->lock, flags);
+	xilinx_dpdma_chan_queue_transfer(chan);
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+static irqreturn_t xilinx_dpdma_irq_handler(int irq, void *data)
+{
+	struct xilinx_dpdma_device *xdev = data;
+	unsigned long mask;
+	unsigned int i;
+	u32 status;
+	u32 error;
+
+	status = dpdma_read(xdev->reg, XILINX_DPDMA_ISR);
+	error = dpdma_read(xdev->reg, XILINX_DPDMA_EISR);
+	if (!status && !error)
+		return IRQ_NONE;
+
+	dpdma_write(xdev->reg, XILINX_DPDMA_ISR, status);
+	dpdma_write(xdev->reg, XILINX_DPDMA_EISR, error);
+
+	if (status & XILINX_DPDMA_INTR_VSYNC) {
+		/*
+		 * There's a single VSYNC interrupt that needs to be processed
+		 * by each running channel to update the active descriptor.
+		 */
+		for (i = 0; i < ARRAY_SIZE(xdev->chan); i++) {
+			struct xilinx_dpdma_chan *chan = xdev->chan[i];
+
+			if (chan)
+				xilinx_dpdma_chan_vsync_irq(chan);
+		}
+	}
+
+	mask = FIELD_GET(XILINX_DPDMA_INTR_DESC_DONE_MASK, status);
+	if (mask) {
+		for_each_set_bit(i, &mask, ARRAY_SIZE(xdev->chan))
+			xilinx_dpdma_chan_done_irq(xdev->chan[i]);
+	}
+
+	mask = FIELD_GET(XILINX_DPDMA_INTR_NO_OSTAND_MASK, status);
+	if (mask) {
+		for_each_set_bit(i, &mask, ARRAY_SIZE(xdev->chan))
+			xilinx_dpdma_chan_notify_no_ostand(xdev->chan[i]);
+	}
+
+	mask = status & XILINX_DPDMA_INTR_ERR_ALL;
+	if (mask || error)
+		xilinx_dpdma_handle_err_irq(xdev, mask, error);
+
+	return IRQ_HANDLED;
+}
+
+/* -----------------------------------------------------------------------------
+ * Initialization & Cleanup
+ */
+
+static int xilinx_dpdma_chan_init(struct xilinx_dpdma_device *xdev,
+				  unsigned int chan_id)
+{
+	struct xilinx_dpdma_chan *chan;
+
+	chan = devm_kzalloc(xdev->dev, sizeof(*chan), GFP_KERNEL);
+	if (!chan)
+		return -ENOMEM;
+
+	chan->id = chan_id;
+	chan->reg = xdev->reg + XILINX_DPDMA_CH_BASE
+		  + XILINX_DPDMA_CH_OFFSET * chan->id;
+	chan->running = false;
+	chan->xdev = xdev;
+
+	spin_lock_init(&chan->lock);
+	init_waitqueue_head(&chan->wait_to_stop);
+
+	tasklet_init(&chan->err_task, xilinx_dpdma_chan_err_task,
+		     (unsigned long)chan);
+
+	chan->vchan.desc_free = xilinx_dpdma_chan_free_tx_desc;
+	vchan_init(&chan->vchan, &xdev->common);
+
+	xdev->chan[chan->id] = chan;
+
+	return 0;
+}
+
+static void xilinx_dpdma_chan_remove(struct xilinx_dpdma_chan *chan)
+{
+	if (!chan)
+		return;
+
+	tasklet_kill(&chan->err_task);
+	list_del(&chan->vchan.chan.device_node);
+}
+
+static struct dma_chan *of_dma_xilinx_xlate(struct of_phandle_args *dma_spec,
+					    struct of_dma *ofdma)
+{
+	struct xilinx_dpdma_device *xdev = ofdma->of_dma_data;
+	uint32_t chan_id = dma_spec->args[0];
+
+	if (chan_id >= ARRAY_SIZE(xdev->chan))
+		return NULL;
+
+	if (!xdev->chan[chan_id])
+		return NULL;
+
+	return dma_get_slave_channel(&xdev->chan[chan_id]->vchan.chan);
+}
+
+static int xilinx_dpdma_probe(struct platform_device *pdev)
+{
+	struct xilinx_dpdma_device *xdev;
+	struct dma_device *ddev;
+	unsigned int i;
+	int ret;
+
+	xdev = devm_kzalloc(&pdev->dev, sizeof(*xdev), GFP_KERNEL);
+	if (!xdev)
+		return -ENOMEM;
+
+	xdev->dev = &pdev->dev;
+	xdev->ext_addr = sizeof(dma_addr_t) > 4;
+
+	INIT_LIST_HEAD(&xdev->common.channels);
+
+	platform_set_drvdata(pdev, xdev);
+
+	xdev->axi_clk = devm_clk_get(xdev->dev, "axi_clk");
+	if (IS_ERR(xdev->axi_clk))
+		return PTR_ERR(xdev->axi_clk);
+
+	xdev->reg = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(xdev->reg))
+		return PTR_ERR(xdev->reg);
+
+	xdev->irq = platform_get_irq(pdev, 0);
+	if (xdev->irq < 0) {
+		dev_err(xdev->dev, "failed to get platform irq\n");
+		return xdev->irq;
+	}
+
+	ret = request_irq(xdev->irq, xilinx_dpdma_irq_handler, IRQF_SHARED,
+			  dev_name(xdev->dev), xdev);
+	if (ret) {
+		dev_err(xdev->dev, "failed to request IRQ\n");
+		return ret;
+	}
+
+	ddev = &xdev->common;
+	ddev->dev = &pdev->dev;
+
+	dma_cap_set(DMA_SLAVE, ddev->cap_mask);
+	dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
+	dma_cap_set(DMA_INTERLEAVE, ddev->cap_mask);
+	dma_cap_set(DMA_REPEAT, ddev->cap_mask);
+	dma_cap_set(DMA_LOAD_EOT, ddev->cap_mask);
+	ddev->copy_align = fls(XILINX_DPDMA_ALIGN_BYTES - 1);
+
+	ddev->device_alloc_chan_resources = xilinx_dpdma_alloc_chan_resources;
+	ddev->device_free_chan_resources = xilinx_dpdma_free_chan_resources;
+	ddev->device_prep_interleaved_dma = xilinx_dpdma_prep_interleaved_dma;
+	/* TODO: Can we achieve better granularity ? */
+	ddev->device_tx_status = dma_cookie_status;
+	ddev->device_issue_pending = xilinx_dpdma_issue_pending;
+	ddev->device_config = xilinx_dpdma_config;
+	ddev->device_pause = xilinx_dpdma_pause;
+	ddev->device_resume = xilinx_dpdma_resume;
+	ddev->device_terminate_all = xilinx_dpdma_terminate_all;
+	ddev->device_synchronize = xilinx_dpdma_synchronize;
+	ddev->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED);
+	ddev->directions = BIT(DMA_MEM_TO_DEV);
+	ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
+
+	for (i = 0; i < ARRAY_SIZE(xdev->chan); ++i) {
+		ret = xilinx_dpdma_chan_init(xdev, i);
+		if (ret < 0) {
+			dev_err(xdev->dev, "failed to initialize channel %u\n",
+				i);
+			goto error;
+		}
+	}
+
+	ret = clk_prepare_enable(xdev->axi_clk);
+	if (ret) {
+		dev_err(xdev->dev, "failed to enable the axi clock\n");
+		goto error;
+	}
+
+	ret = dma_async_device_register(ddev);
+	if (ret) {
+		dev_err(xdev->dev, "failed to register the dma device\n");
+		goto error_dma_async;
+	}
+
+	ret = of_dma_controller_register(xdev->dev->of_node,
+					 of_dma_xilinx_xlate, ddev);
+	if (ret) {
+		dev_err(xdev->dev, "failed to register DMA to DT DMA helper\n");
+		goto error_of_dma;
+	}
+
+	xilinx_dpdma_enable_irq(xdev);
+
+	dev_info(&pdev->dev, "Xilinx DPDMA engine is probed\n");
+
+	return 0;
+
+error_of_dma:
+	dma_async_device_unregister(ddev);
+error_dma_async:
+	clk_disable_unprepare(xdev->axi_clk);
+error:
+	for (i = 0; i < ARRAY_SIZE(xdev->chan); i++)
+		xilinx_dpdma_chan_remove(xdev->chan[i]);
+
+	free_irq(xdev->irq, xdev);
+
+	return ret;
+}
+
+static int xilinx_dpdma_remove(struct platform_device *pdev)
+{
+	struct xilinx_dpdma_device *xdev = platform_get_drvdata(pdev);
+	unsigned int i;
+
+	/* Start by disabling the IRQ to avoid races during cleanup. */
+	free_irq(xdev->irq, xdev);
+
+	xilinx_dpdma_disable_irq(xdev);
+	of_dma_controller_free(pdev->dev.of_node);
+	dma_async_device_unregister(&xdev->common);
+	clk_disable_unprepare(xdev->axi_clk);
+
+	for (i = 0; i < ARRAY_SIZE(xdev->chan); i++)
+		xilinx_dpdma_chan_remove(xdev->chan[i]);
+
+	return 0;
+}
+
+static const struct of_device_id xilinx_dpdma_of_match[] = {
+	{ .compatible = "xlnx,zynqmp-dpdma",},
+	{ /* end of table */ },
+};
+MODULE_DEVICE_TABLE(of, xilinx_dpdma_of_match);
+
+static struct platform_driver xilinx_dpdma_driver = {
+	.probe			= xilinx_dpdma_probe,
+	.remove			= xilinx_dpdma_remove,
+	.driver			= {
+		.name		= "xilinx-zynqmp-dpdma",
+		.of_match_table	= xilinx_dpdma_of_match,
+	},
+};
+
+module_platform_driver(xilinx_dpdma_driver);
+
+MODULE_AUTHOR("Xilinx, Inc.");
+MODULE_DESCRIPTION("Xilinx ZynqMP DPDMA driver");
+MODULE_LICENSE("GPL v2");
-- 
Regards,

Laurent Pinchart