dma: Add Xilinx AXI Video Direct Memory Access Engine driver support

This is the driver for the AXI Video Direct Memory Access (AXI
VDMA) core, which is a soft Xilinx IP core that provides high-
bandwidth direct memory access between memory and AXI4-Stream
type video target peripherals. The core provides efficient two
dimensional DMA operations with independent asynchronous read
and write channel operation.

This module works on Zynq (ARM Based SoC) and Microblaze platforms.

Signed-off-by: Srikanth Thokala <[e-mail]>
Acked-by: Jassi Brar <[e-mail]>
Reviewed-by: Levente Kurusa <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/Kconfig

···
 	  multiplexing capability for DMA request sources(slot).
 	  This module can be found on Freescale Vybrid and LS-1 SoCs.
 
+config XILINX_VDMA
+	tristate "Xilinx AXI VDMA Engine"
+	depends on (ARCH_ZYNQ || MICROBLAZE)
+	select DMA_ENGINE
+	help
+	  Enable support for Xilinx AXI VDMA Soft IP.
+
+	  This engine provides high-bandwidth direct memory access
+	  between memory and AXI4-Stream video type target
+	  peripherals including peripherals which support AXI4-
+	  Stream Video Protocol.  It has two stream interfaces/
+	  channels, Memory Mapped to Stream (MM2S) and Stream to
+	  Memory Mapped (S2MM) for the data transfers.
+
 config DMA_ENGINE
 	bool
 

drivers/dma/Makefile

···
 obj-$(CONFIG_MOXART_DMA) += moxart-dma.o
 obj-$(CONFIG_FSL_EDMA) += fsl-edma.o
 obj-$(CONFIG_QCOM_BAM_DMA) += qcom_bam_dma.o
+obj-y += xilinx/

drivers/dma/xilinx/Makefile

···
+obj-$(CONFIG_XILINX_VDMA) += xilinx_vdma.o

drivers/dma/xilinx/xilinx_vdma.c

···
+/*
+ * DMA driver for Xilinx Video DMA Engine
+ *
+ * Copyright (C) 2010-2014 Xilinx, Inc. All rights reserved.
+ *
+ * Based on the Freescale DMA driver.
+ *
+ * Description:
+ * The AXI Video Direct Memory Access (AXI VDMA) core is a soft Xilinx IP
+ * core that provides high-bandwidth direct memory access between memory
+ * and AXI4-Stream type video target peripherals. The core provides efficient
+ * two dimensional DMA operations with independent asynchronous read (S2MM)
+ * and write (MM2S) channel operation. It can be configured to have either
+ * one channel or two channels. If configured as two channels, one is to
+ * transmit to the video device (MM2S) and another is to receive from the
+ * video device (S2MM). Initialization, status, interrupt and management
+ * registers are accessed through an AXI4-Lite slave interface.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/amba/xilinx_dma.h>
+#include <linux/bitops.h>
+#include <linux/dmapool.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_dma.h>
+#include <linux/of_platform.h>
+#include <linux/of_irq.h>
+#include <linux/slab.h>
+
+#include "../dmaengine.h"
+
+/* Register/Descriptor Offsets */
+#define XILINX_VDMA_MM2S_CTRL_OFFSET		0x0000
+#define XILINX_VDMA_S2MM_CTRL_OFFSET		0x0030
+#define XILINX_VDMA_MM2S_DESC_OFFSET		0x0050
+#define XILINX_VDMA_S2MM_DESC_OFFSET		0x00a0
+
+/* Control Registers */
+#define XILINX_VDMA_REG_DMACR			0x0000
+#define XILINX_VDMA_DMACR_DELAY_MAX		0xff
+#define XILINX_VDMA_DMACR_DELAY_SHIFT		24
+#define XILINX_VDMA_DMACR_FRAME_COUNT_MAX	0xff
+#define XILINX_VDMA_DMACR_FRAME_COUNT_SHIFT	16
+#define XILINX_VDMA_DMACR_ERR_IRQ		BIT(14)
+#define XILINX_VDMA_DMACR_DLY_CNT_IRQ		BIT(13)
+#define XILINX_VDMA_DMACR_FRM_CNT_IRQ		BIT(12)
+#define XILINX_VDMA_DMACR_MASTER_SHIFT		8
+#define XILINX_VDMA_DMACR_FSYNCSRC_SHIFT	5
+#define XILINX_VDMA_DMACR_FRAMECNT_EN		BIT(4)
+#define XILINX_VDMA_DMACR_GENLOCK_EN		BIT(3)
+#define XILINX_VDMA_DMACR_RESET			BIT(2)
+#define XILINX_VDMA_DMACR_CIRC_EN		BIT(1)
+#define XILINX_VDMA_DMACR_RUNSTOP		BIT(0)
+#define XILINX_VDMA_DMACR_FSYNCSRC_MASK		GENMASK(6, 5)
+
+#define XILINX_VDMA_REG_DMASR			0x0004
+#define XILINX_VDMA_DMASR_EOL_LATE_ERR		BIT(15)
+#define XILINX_VDMA_DMASR_ERR_IRQ		BIT(14)
+#define XILINX_VDMA_DMASR_DLY_CNT_IRQ		BIT(13)
+#define XILINX_VDMA_DMASR_FRM_CNT_IRQ		BIT(12)
+#define XILINX_VDMA_DMASR_SOF_LATE_ERR		BIT(11)
+#define XILINX_VDMA_DMASR_SG_DEC_ERR		BIT(10)
+#define XILINX_VDMA_DMASR_SG_SLV_ERR		BIT(9)
+#define XILINX_VDMA_DMASR_EOF_EARLY_ERR		BIT(8)
+#define XILINX_VDMA_DMASR_SOF_EARLY_ERR		BIT(7)
+#define XILINX_VDMA_DMASR_DMA_DEC_ERR		BIT(6)
+#define XILINX_VDMA_DMASR_DMA_SLAVE_ERR		BIT(5)
+#define XILINX_VDMA_DMASR_DMA_INT_ERR		BIT(4)
+#define XILINX_VDMA_DMASR_IDLE			BIT(1)
+#define XILINX_VDMA_DMASR_HALTED		BIT(0)
+#define XILINX_VDMA_DMASR_DELAY_MASK		GENMASK(31, 24)
+#define XILINX_VDMA_DMASR_FRAME_COUNT_MASK	GENMASK(23, 16)
+
+#define XILINX_VDMA_REG_CURDESC			0x0008
+#define XILINX_VDMA_REG_TAILDESC		0x0010
+#define XILINX_VDMA_REG_REG_INDEX		0x0014
+#define XILINX_VDMA_REG_FRMSTORE		0x0018
+#define XILINX_VDMA_REG_THRESHOLD		0x001c
+#define XILINX_VDMA_REG_FRMPTR_STS		0x0024
+#define XILINX_VDMA_REG_PARK_PTR		0x0028
+#define XILINX_VDMA_PARK_PTR_WR_REF_SHIFT	8
+#define XILINX_VDMA_PARK_PTR_RD_REF_SHIFT	0
+#define XILINX_VDMA_REG_VDMA_VERSION		0x002c
+
+/* Register Direct Mode Registers */
+#define XILINX_VDMA_REG_VSIZE			0x0000
+#define XILINX_VDMA_REG_HSIZE			0x0004
+
+#define XILINX_VDMA_REG_FRMDLY_STRIDE		0x0008
+#define XILINX_VDMA_FRMDLY_STRIDE_FRMDLY_SHIFT	24
+#define XILINX_VDMA_FRMDLY_STRIDE_STRIDE_SHIFT	0
+
+#define XILINX_VDMA_REG_START_ADDRESS(n)	(0x000c + 4 * (n))
+
+/* HW specific definitions */
+#define XILINX_VDMA_MAX_CHANS_PER_DEVICE	0x2
+
+#define XILINX_VDMA_DMAXR_ALL_IRQ_MASK	\
+		(XILINX_VDMA_DMASR_FRM_CNT_IRQ | \
+		 XILINX_VDMA_DMASR_DLY_CNT_IRQ | \
+		 XILINX_VDMA_DMASR_ERR_IRQ)
+
+#define XILINX_VDMA_DMASR_ALL_ERR_MASK	\
+		(XILINX_VDMA_DMASR_EOL_LATE_ERR | \
+		 XILINX_VDMA_DMASR_SOF_LATE_ERR | \
+		 XILINX_VDMA_DMASR_SG_DEC_ERR | \
+		 XILINX_VDMA_DMASR_SG_SLV_ERR | \
+		 XILINX_VDMA_DMASR_EOF_EARLY_ERR | \
+		 XILINX_VDMA_DMASR_SOF_EARLY_ERR | \
+		 XILINX_VDMA_DMASR_DMA_DEC_ERR | \
+		 XILINX_VDMA_DMASR_DMA_SLAVE_ERR | \
+		 XILINX_VDMA_DMASR_DMA_INT_ERR)
+
+/*
+ * Recoverable errors are DMA Internal error, SOF Early, EOF Early
+ * and SOF Late. They are only recoverable when C_FLUSH_ON_FSYNC
+ * is enabled in the h/w system.
+ */
+#define XILINX_VDMA_DMASR_ERR_RECOVER_MASK	\
+		(XILINX_VDMA_DMASR_SOF_LATE_ERR | \
+		 XILINX_VDMA_DMASR_EOF_EARLY_ERR | \
+		 XILINX_VDMA_DMASR_SOF_EARLY_ERR | \
+		 XILINX_VDMA_DMASR_DMA_INT_ERR)
+
+/* Axi VDMA Flush on Fsync bits */
+#define XILINX_VDMA_FLUSH_S2MM		3
+#define XILINX_VDMA_FLUSH_MM2S		2
+#define XILINX_VDMA_FLUSH_BOTH		1
+
+/* Delay loop counter to prevent hardware failure */
+#define XILINX_VDMA_LOOP_COUNT		1000000
+
+/**
+ * struct xilinx_vdma_desc_hw - Hardware Descriptor
+ * @next_desc: Next Descriptor Pointer @0x00
+ * @pad1: Reserved @0x04
+ * @buf_addr: Buffer address @0x08
+ * @pad2: Reserved @0x0C
+ * @vsize: Vertical Size @0x10
+ * @hsize: Horizontal Size @0x14
+ * @stride: Number of bytes between the first
+ *	    pixels of each horizontal line @0x18
+ */
+struct xilinx_vdma_desc_hw {
+	u32 next_desc;
+	u32 pad1;
+	u32 buf_addr;
+	u32 pad2;
+	u32 vsize;
+	u32 hsize;
+	u32 stride;
+} __aligned(64);
+
+/**
+ * struct xilinx_vdma_tx_segment - Descriptor segment
+ * @hw: Hardware descriptor
+ * @node: Node in the descriptor segments list
+ * @phys: Physical address of segment
+ */
+struct xilinx_vdma_tx_segment {
+	struct xilinx_vdma_desc_hw hw;
+	struct list_head node;
+	dma_addr_t phys;
+} __aligned(64);
+
+/**
+ * struct xilinx_vdma_tx_descriptor - Per Transaction structure
+ * @async_tx: Async transaction descriptor
+ * @segments: TX segments list
+ * @node: Node in the channel descriptors list
+ */
+struct xilinx_vdma_tx_descriptor {
+	struct dma_async_tx_descriptor async_tx;
+	struct list_head segments;
+	struct list_head node;
+};
+
+/**
+ * struct xilinx_vdma_chan - Driver specific VDMA channel structure
+ * @xdev: Driver specific device structure
+ * @ctrl_offset: Control registers offset
+ * @desc_offset: TX descriptor registers offset
+ * @lock: Descriptor operation lock
+ * @pending_list: Descriptors waiting
+ * @active_desc: Active descriptor
+ * @allocated_desc: Allocated descriptor
+ * @done_list: Complete descriptors
+ * @common: DMA common channel
+ * @desc_pool: Descriptors pool
+ * @dev: The dma device
+ * @irq: Channel IRQ
+ * @id: Channel ID
+ * @direction: Transfer direction
+ * @num_frms: Number of frames
+ * @has_sg: Support scatter transfers
+ * @genlock: Support genlock mode
+ * @err: Channel has errors
+ * @tasklet: Cleanup work after irq
+ * @config: Device configuration info
+ * @flush_on_fsync: Flush on Frame sync
+ */
+struct xilinx_vdma_chan {
+	struct xilinx_vdma_device *xdev;
+	u32 ctrl_offset;
+	u32 desc_offset;
+	spinlock_t lock;
+	struct list_head pending_list;
+	struct xilinx_vdma_tx_descriptor *active_desc;
+	struct xilinx_vdma_tx_descriptor *allocated_desc;
+	struct list_head done_list;
+	struct dma_chan common;
+	struct dma_pool *desc_pool;
+	struct device *dev;
+	int irq;
+	int id;
+	enum dma_transfer_direction direction;
+	int num_frms;
+	bool has_sg;
+	bool genlock;
+	bool err;
+	struct tasklet_struct tasklet;
+	struct xilinx_vdma_config config;
+	bool flush_on_fsync;
+};
+
+/**
+ * struct xilinx_vdma_device - VDMA device structure
+ * @regs: I/O mapped base address
+ * @dev: Device Structure
+ * @common: DMA device structure
+ * @chan: Driver specific VDMA channel
+ * @has_sg: Specifies whether Scatter-Gather is present or not
+ * @flush_on_fsync: Flush on frame sync
+ */
+struct xilinx_vdma_device {
+	void __iomem *regs;
+	struct device *dev;
+	struct dma_device common;
+	struct xilinx_vdma_chan *chan[XILINX_VDMA_MAX_CHANS_PER_DEVICE];
+	bool has_sg;
+	u32 flush_on_fsync;
+};
+
+/* Macros */
+#define to_xilinx_chan(chan) \
+	container_of(chan, struct xilinx_vdma_chan, common)
+#define to_vdma_tx_descriptor(tx) \
+	container_of(tx, struct xilinx_vdma_tx_descriptor, async_tx)
+
+/* IO accessors */
+static inline u32 vdma_read(struct xilinx_vdma_chan *chan, u32 reg)
+{
+	return ioread32(chan->xdev->regs + reg);
+}
+
+static inline void vdma_write(struct xilinx_vdma_chan *chan, u32 reg, u32 value)
+{
+	iowrite32(value, chan->xdev->regs + reg);
+}
+
+static inline void vdma_desc_write(struct xilinx_vdma_chan *chan, u32 reg,
+				   u32 value)
+{
+	vdma_write(chan, chan->desc_offset + reg, value);
+}
+
+static inline u32 vdma_ctrl_read(struct xilinx_vdma_chan *chan, u32 reg)
+{
+	return vdma_read(chan, chan->ctrl_offset + reg);
+}
+
+static inline void vdma_ctrl_write(struct xilinx_vdma_chan *chan, u32 reg,
+				   u32 value)
+{
+	vdma_write(chan, chan->ctrl_offset + reg, value);
+}
+
+static inline void vdma_ctrl_clr(struct xilinx_vdma_chan *chan, u32 reg,
+				 u32 clr)
+{
+	vdma_ctrl_write(chan, reg, vdma_ctrl_read(chan, reg) & ~clr);
+}
+
+static inline void vdma_ctrl_set(struct xilinx_vdma_chan *chan, u32 reg,
+				 u32 set)
+{
+	vdma_ctrl_write(chan, reg, vdma_ctrl_read(chan, reg) | set);
+}
+
+/* -----------------------------------------------------------------------------
+ * Descriptors and segments alloc and free
+ */
+
+/**
+ * xilinx_vdma_alloc_tx_segment - Allocate transaction segment
+ * @chan: Driver specific VDMA channel
+ *
+ * Return: The allocated segment on success and NULL on failure.
+ */
+static struct xilinx_vdma_tx_segment *
+xilinx_vdma_alloc_tx_segment(struct xilinx_vdma_chan *chan)
+{
+	struct xilinx_vdma_tx_segment *segment;
+	dma_addr_t phys;
+
+	segment = dma_pool_alloc(chan->desc_pool, GFP_ATOMIC, &phys);
+	if (!segment)
+		return NULL;
+
+	memset(segment, 0, sizeof(*segment));
+	segment->phys = phys;
+
+	return segment;
+}
+
+/**
+ * xilinx_vdma_free_tx_segment - Free transaction segment
+ * @chan: Driver specific VDMA channel
+ * @segment: VDMA transaction segment
+ */
+static void xilinx_vdma_free_tx_segment(struct xilinx_vdma_chan *chan,
+					struct xilinx_vdma_tx_segment *segment)
+{
+	dma_pool_free(chan->desc_pool, segment, segment->phys);
+}
+
+/**
+ * xilinx_vdma_tx_descriptor - Allocate transaction descriptor
+ * @chan: Driver specific VDMA channel
+ *
+ * Return: The allocated descriptor on success and NULL on failure.
+ */
+static struct xilinx_vdma_tx_descriptor *
+xilinx_vdma_alloc_tx_descriptor(struct xilinx_vdma_chan *chan)
+{
+	struct xilinx_vdma_tx_descriptor *desc;
+	unsigned long flags;
+
+	if (chan->allocated_desc)
+		return chan->allocated_desc;
+
+	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
+	if (!desc)
+		return NULL;
+
+	spin_lock_irqsave(&chan->lock, flags);
+	chan->allocated_desc = desc;
+	spin_unlock_irqrestore(&chan->lock, flags);
+
+	INIT_LIST_HEAD(&desc->segments);
+
+	return desc;
+}
+
+/**
+ * xilinx_vdma_free_tx_descriptor - Free transaction descriptor
+ * @chan: Driver specific VDMA channel
+ * @desc: VDMA transaction descriptor
+ */
+static void
+xilinx_vdma_free_tx_descriptor(struct xilinx_vdma_chan *chan,
+			       struct xilinx_vdma_tx_descriptor *desc)
+{
+	struct xilinx_vdma_tx_segment *segment, *next;
+
+	if (!desc)
+		return;
+
+	list_for_each_entry_safe(segment, next, &desc->segments, node) {
+		list_del(&segment->node);
+		xilinx_vdma_free_tx_segment(chan, segment);
+	}
+
+	kfree(desc);
+}
+
+/* Required functions */
+
+/**
+ * xilinx_vdma_free_desc_list - Free descriptors list
+ * @chan: Driver specific VDMA channel
+ * @list: List to parse and delete the descriptor
+ */
+static void xilinx_vdma_free_desc_list(struct xilinx_vdma_chan *chan,
+					struct list_head *list)
+{
+	struct xilinx_vdma_tx_descriptor *desc, *next;
+
+	list_for_each_entry_safe(desc, next, list, node) {
+		list_del(&desc->node);
+		xilinx_vdma_free_tx_descriptor(chan, desc);
+	}
+}
+
+/**
+ * xilinx_vdma_free_descriptors - Free channel descriptors
+ * @chan: Driver specific VDMA channel
+ */
+static void xilinx_vdma_free_descriptors(struct xilinx_vdma_chan *chan)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->lock, flags);
+
+	xilinx_vdma_free_desc_list(chan, &chan->pending_list);
+	xilinx_vdma_free_desc_list(chan, &chan->done_list);
+
+	xilinx_vdma_free_tx_descriptor(chan, chan->active_desc);
+	chan->active_desc = NULL;
+
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+/**
+ * xilinx_vdma_free_chan_resources - Free channel resources
+ * @dchan: DMA channel
+ */
+static void xilinx_vdma_free_chan_resources(struct dma_chan *dchan)
+{
+	struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);
+
+	dev_dbg(chan->dev, "Free all channel resources.\n");
+
+	xilinx_vdma_free_descriptors(chan);
+	dma_pool_destroy(chan->desc_pool);
+	chan->desc_pool = NULL;
+}
+
+/**
+ * xilinx_vdma_chan_desc_cleanup - Clean channel descriptors
+ * @chan: Driver specific VDMA channel
+ */
+static void xilinx_vdma_chan_desc_cleanup(struct xilinx_vdma_chan *chan)
+{
+	struct xilinx_vdma_tx_descriptor *desc, *next;
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->lock, flags);
+
+	list_for_each_entry_safe(desc, next, &chan->done_list, node) {
+		dma_async_tx_callback callback;
+		void *callback_param;
+
+		/* Remove from the list of running transactions */
+		list_del(&desc->node);
+
+		/* Run the link descriptor callback function */
+		callback = desc->async_tx.callback;
+		callback_param = desc->async_tx.callback_param;
+		if (callback) {
+			spin_unlock_irqrestore(&chan->lock, flags);
+			callback(callback_param);
+			spin_lock_irqsave(&chan->lock, flags);
+		}
+
+		/* Run any dependencies, then free the descriptor */
+		dma_run_dependencies(&desc->async_tx);
+		xilinx_vdma_free_tx_descriptor(chan, desc);
+	}
+
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+/**
+ * xilinx_vdma_do_tasklet - Schedule completion tasklet
+ * @data: Pointer to the Xilinx VDMA channel structure
+ */
+static void xilinx_vdma_do_tasklet(unsigned long data)
+{
+	struct xilinx_vdma_chan *chan = (struct xilinx_vdma_chan *)data;
+
+	xilinx_vdma_chan_desc_cleanup(chan);
+}
+
+/**
+ * xilinx_vdma_alloc_chan_resources - Allocate channel resources
+ * @dchan: DMA channel
+ *
+ * Return: '0' on success and failure value on error
+ */
+static int xilinx_vdma_alloc_chan_resources(struct dma_chan *dchan)
+{
+	struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);
+
+	/* Has this channel already been allocated? */
+	if (chan->desc_pool)
+		return 0;
+
+	/*
+	 * We need the descriptor to be aligned to 64bytes
+	 * for meeting Xilinx VDMA specification requirement.
+	 */
+	chan->desc_pool = dma_pool_create("xilinx_vdma_desc_pool",
+				chan->dev,
+				sizeof(struct xilinx_vdma_tx_segment),
+				__alignof__(struct xilinx_vdma_tx_segment), 0);
+	if (!chan->desc_pool) {
+		dev_err(chan->dev,
+			"unable to allocate channel %d descriptor pool\n",
+			chan->id);
+		return -ENOMEM;
+	}
+
+	dma_cookie_init(dchan);
+	return 0;
+}
+
+/**
+ * xilinx_vdma_tx_status - Get VDMA transaction status
+ * @dchan: DMA channel
+ * @cookie: Transaction identifier
+ * @txstate: Transaction state
+ *
+ * Return: DMA transaction status
+ */
+static enum dma_status xilinx_vdma_tx_status(struct dma_chan *dchan,
+					dma_cookie_t cookie,
+					struct dma_tx_state *txstate)
+{
+	return dma_cookie_status(dchan, cookie, txstate);
+}
+
+/**
+ * xilinx_vdma_is_running - Check if VDMA channel is running
+ * @chan: Driver specific VDMA channel
+ *
+ * Return: '1' if running, '0' if not.
+ */
+static bool xilinx_vdma_is_running(struct xilinx_vdma_chan *chan)
+{
+	return !(vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR) &
+		 XILINX_VDMA_DMASR_HALTED) &&
+		(vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR) &
+		 XILINX_VDMA_DMACR_RUNSTOP);
+}
+
+/**
+ * xilinx_vdma_is_idle - Check if VDMA channel is idle
+ * @chan: Driver specific VDMA channel
+ *
+ * Return: '1' if idle, '0' if not.
+ */
+static bool xilinx_vdma_is_idle(struct xilinx_vdma_chan *chan)
+{
+	return vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR) &
+		XILINX_VDMA_DMASR_IDLE;
+}
+
+/**
+ * xilinx_vdma_halt - Halt VDMA channel
+ * @chan: Driver specific VDMA channel
+ */
+static void xilinx_vdma_halt(struct xilinx_vdma_chan *chan)
+{
+	int loop = XILINX_VDMA_LOOP_COUNT;
+
+	vdma_ctrl_clr(chan, XILINX_VDMA_REG_DMACR, XILINX_VDMA_DMACR_RUNSTOP);
+
+	/* Wait for the hardware to halt */
+	do {
+		if (vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR) &
+		    XILINX_VDMA_DMASR_HALTED)
+			break;
+	} while (loop--);
+
+	if (!loop) {
+		dev_err(chan->dev, "Cannot stop channel %p: %x\n",
+			chan, vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR));
+		chan->err = true;
+	}
+
+	return;
+}
+
+/**
+ * xilinx_vdma_start - Start VDMA channel
+ * @chan: Driver specific VDMA channel
+ */
+static void xilinx_vdma_start(struct xilinx_vdma_chan *chan)
+{
+	int loop = XILINX_VDMA_LOOP_COUNT;
+
+	vdma_ctrl_set(chan, XILINX_VDMA_REG_DMACR, XILINX_VDMA_DMACR_RUNSTOP);
+
+	/* Wait for the hardware to start */
+	do {
+		if (!(vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR) &
+		      XILINX_VDMA_DMASR_HALTED))
+			break;
+	} while (loop--);
+
+	if (!loop) {
+		dev_err(chan->dev, "Cannot start channel %p: %x\n",
+			chan, vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR));
+
+		chan->err = true;
+	}
+
+	return;
+}
+
+/**
+ * xilinx_vdma_start_transfer - Starts VDMA transfer
+ * @chan: Driver specific channel struct pointer
+ */
+static void xilinx_vdma_start_transfer(struct xilinx_vdma_chan *chan)
+{
+	struct xilinx_vdma_config *config = &chan->config;
+	struct xilinx_vdma_tx_descriptor *desc;
+	unsigned long flags;
+	u32 reg;
+	struct xilinx_vdma_tx_segment *head, *tail = NULL;
+
+	if (chan->err)
+		return;
+
+	spin_lock_irqsave(&chan->lock, flags);
+
+	/* There's already an active descriptor, bail out. */
+	if (chan->active_desc)
+		goto out_unlock;
+
+	if (list_empty(&chan->pending_list))
+		goto out_unlock;
+
+	desc = list_first_entry(&chan->pending_list,
+				struct xilinx_vdma_tx_descriptor, node);
+
+	/* If it is SG mode and hardware is busy, cannot submit */
+	if (chan->has_sg && xilinx_vdma_is_running(chan) &&
+	    !xilinx_vdma_is_idle(chan)) {
+		dev_dbg(chan->dev, "DMA controller still busy\n");
+		goto out_unlock;
+	}
+
+	/*
+	 * If hardware is idle, then all descriptors on the running lists are
+	 * done, start new transfers
+	 */
+	if (chan->has_sg) {
+		head = list_first_entry(&desc->segments,
+					struct xilinx_vdma_tx_segment, node);
+		tail = list_entry(desc->segments.prev,
+				  struct xilinx_vdma_tx_segment, node);
+
+		vdma_ctrl_write(chan, XILINX_VDMA_REG_CURDESC, head->phys);
+	}
+
+	/* Configure the hardware using info in the config structure */
+	reg = vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR);
+
+	if (config->frm_cnt_en)
+		reg |= XILINX_VDMA_DMACR_FRAMECNT_EN;
+	else
+		reg &= ~XILINX_VDMA_DMACR_FRAMECNT_EN;
+
+	/*
+	 * With SG, start with circular mode, so that BDs can be fetched.
+	 * In direct register mode, if not parking, enable circular mode
+	 */
+	if (chan->has_sg || !config->park)
+		reg |= XILINX_VDMA_DMACR_CIRC_EN;
+
+	if (config->park)
+		reg &= ~XILINX_VDMA_DMACR_CIRC_EN;
+
+	vdma_ctrl_write(chan, XILINX_VDMA_REG_DMACR, reg);
+
+	if (config->park && (config->park_frm >= 0) &&
+			(config->park_frm < chan->num_frms)) {
+		if (chan->direction == DMA_MEM_TO_DEV)
+			vdma_write(chan, XILINX_VDMA_REG_PARK_PTR,
+				config->park_frm <<
+					XILINX_VDMA_PARK_PTR_RD_REF_SHIFT);
+		else
+			vdma_write(chan, XILINX_VDMA_REG_PARK_PTR,
+				config->park_frm <<
+					XILINX_VDMA_PARK_PTR_WR_REF_SHIFT);
+	}
+
+	/* Start the hardware */
+	xilinx_vdma_start(chan);
+
+	if (chan->err)
+		goto out_unlock;
+
+	/* Start the transfer */
+	if (chan->has_sg) {
+		vdma_ctrl_write(chan, XILINX_VDMA_REG_TAILDESC, tail->phys);
+	} else {
+		struct xilinx_vdma_tx_segment *segment, *last = NULL;
+		int i = 0;
+
+		list_for_each_entry(segment, &desc->segments, node) {
+			vdma_desc_write(chan,
+					XILINX_VDMA_REG_START_ADDRESS(i++),
+					segment->hw.buf_addr);
+			last = segment;
+		}
+
+		if (!last)
+			goto out_unlock;
+
+		/* HW expects these parameters to be same for one transaction */
+		vdma_desc_write(chan, XILINX_VDMA_REG_HSIZE, last->hw.hsize);
+		vdma_desc_write(chan, XILINX_VDMA_REG_FRMDLY_STRIDE,
+				last->hw.stride);
+		vdma_desc_write(chan, XILINX_VDMA_REG_VSIZE, last->hw.vsize);
+	}
+
+	list_del(&desc->node);
+	chan->active_desc = desc;
+
+out_unlock:
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+/**
+ * xilinx_vdma_issue_pending - Issue pending transactions
+ * @dchan: DMA channel
+ */
+static void xilinx_vdma_issue_pending(struct dma_chan *dchan)
+{
+	struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);
+
+	xilinx_vdma_start_transfer(chan);
+}
+
+/**
+ * xilinx_vdma_complete_descriptor - Mark the active descriptor as complete
+ * @chan : xilinx DMA channel
+ *
+ * CONTEXT: hardirq
+ */
+static void xilinx_vdma_complete_descriptor(struct xilinx_vdma_chan *chan)
+{
+	struct xilinx_vdma_tx_descriptor *desc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&chan->lock, flags);
+
+	desc = chan->active_desc;
+	if (!desc) {
+		dev_dbg(chan->dev, "no running descriptors\n");
+		goto out_unlock;
+	}
+
+	dma_cookie_complete(&desc->async_tx);
+	list_add_tail(&desc->node, &chan->done_list);
+
+	chan->active_desc = NULL;
+
+out_unlock:
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+/**
+ * xilinx_vdma_reset - Reset VDMA channel
+ * @chan: Driver specific VDMA channel
+ *
+ * Return: '0' on success and failure value on error
+ */
+static int xilinx_vdma_reset(struct xilinx_vdma_chan *chan)
+{
+	int loop = XILINX_VDMA_LOOP_COUNT;
+	u32 tmp;
+
+	vdma_ctrl_set(chan, XILINX_VDMA_REG_DMACR, XILINX_VDMA_DMACR_RESET);
+
+	tmp = vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR) &
+		XILINX_VDMA_DMACR_RESET;
+
+	/* Wait for the hardware to finish reset */
+	do {
+		tmp = vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR) &
+			XILINX_VDMA_DMACR_RESET;
+	} while (loop-- && tmp);
+
+	if (!loop) {
+		dev_err(chan->dev, "reset timeout, cr %x, sr %x\n",
+			vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR),
+			vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR));
+		return -ETIMEDOUT;
+	}
+
+	chan->err = false;
+
+	return 0;
+}
+
+/**
+ * xilinx_vdma_chan_reset - Reset VDMA channel and enable interrupts
+ * @chan: Driver specific VDMA channel
+ *
+ * Return: '0' on success and failure value on error
+ */
+static int xilinx_vdma_chan_reset(struct xilinx_vdma_chan *chan)
+{
+	int err;
+
+	/* Reset VDMA */
+	err = xilinx_vdma_reset(chan);
+	if (err)
+		return err;
+
+	/* Enable interrupts */
+	vdma_ctrl_set(chan, XILINX_VDMA_REG_DMACR,
+		      XILINX_VDMA_DMAXR_ALL_IRQ_MASK);
+
+	return 0;
+}
+
+/**
+ * xilinx_vdma_irq_handler - VDMA Interrupt handler
+ * @irq: IRQ number
+ * @data: Pointer to the Xilinx VDMA channel structure
+ *
+ * Return: IRQ_HANDLED/IRQ_NONE
+ */
+static irqreturn_t xilinx_vdma_irq_handler(int irq, void *data)
+{
+	struct xilinx_vdma_chan *chan = data;
+	u32 status;
+
+	/* Read the status and ack the interrupts. */
+	status = vdma_ctrl_read(chan, XILINX_VDMA_REG_DMASR);
+	if (!(status & XILINX_VDMA_DMAXR_ALL_IRQ_MASK))
+		return IRQ_NONE;
+
+	vdma_ctrl_write(chan, XILINX_VDMA_REG_DMASR,
+			status & XILINX_VDMA_DMAXR_ALL_IRQ_MASK);
+
+	if (status & XILINX_VDMA_DMASR_ERR_IRQ) {
+		/*
+		 * An error occurred. If C_FLUSH_ON_FSYNC is enabled and the
+		 * error is recoverable, ignore it. Otherwise flag the error.
+		 *
+		 * Only recoverable errors can be cleared in the DMASR register,
+		 * make sure not to write to other error bits to 1.
+		 */
+		u32 errors = status & XILINX_VDMA_DMASR_ALL_ERR_MASK;
+		vdma_ctrl_write(chan, XILINX_VDMA_REG_DMASR,
+				errors & XILINX_VDMA_DMASR_ERR_RECOVER_MASK);
+
+		if (!chan->flush_on_fsync ||
+		    (errors & ~XILINX_VDMA_DMASR_ERR_RECOVER_MASK)) {
+			dev_err(chan->dev,
+				"Channel %p has errors %x, cdr %x tdr %x\n",
+				chan, errors,
+				vdma_ctrl_read(chan, XILINX_VDMA_REG_CURDESC),
+				vdma_ctrl_read(chan, XILINX_VDMA_REG_TAILDESC));
+			chan->err = true;
+		}
+	}
+
+	if (status & XILINX_VDMA_DMASR_DLY_CNT_IRQ) {
+		/*
+		 * Device takes too long to do the transfer when user requires
+		 * responsiveness.
+		 */
+		dev_dbg(chan->dev, "Inter-packet latency too long\n");
+	}
+
+	if (status & XILINX_VDMA_DMASR_FRM_CNT_IRQ) {
+		xilinx_vdma_complete_descriptor(chan);
+		xilinx_vdma_start_transfer(chan);
+	}
+
+	tasklet_schedule(&chan->tasklet);
+	return IRQ_HANDLED;
+}
+
+/**
+ * xilinx_vdma_tx_submit - Submit DMA transaction
+ * @tx: Async transaction descriptor
+ *
+ * Return: cookie value on success and failure value on error
+ */
+static dma_cookie_t xilinx_vdma_tx_submit(struct dma_async_tx_descriptor *tx)
+{
+	struct xilinx_vdma_tx_descriptor *desc = to_vdma_tx_descriptor(tx);
+	struct xilinx_vdma_chan *chan = to_xilinx_chan(tx->chan);
+	dma_cookie_t cookie;
+	unsigned long flags;
+	int err;
+
+	if (chan->err) {
+		/*
+		 * If reset fails, need to hard reset the system.
+		 * Channel is no longer functional
+		 */
+		err = xilinx_vdma_chan_reset(chan);
+		if (err < 0)
+			return err;
+	}
+
+	spin_lock_irqsave(&chan->lock, flags);
+
+	cookie = dma_cookie_assign(tx);
+
+	/* Append the transaction to the pending transactions queue. */
+	list_add_tail(&desc->node, &chan->pending_list);
+
+	/* Free the allocated desc */
+	chan->allocated_desc = NULL;
+
+	spin_unlock_irqrestore(&chan->lock, flags);
+
+	return cookie;
+}
+
+/**
+ * xilinx_vdma_dma_prep_interleaved - prepare a descriptor for a
+ *	DMA_SLAVE transaction
+ * @dchan: DMA channel
+ * @xt: Interleaved template pointer
+ * @flags: transfer ack flags
+ *
+ * Return: Async transaction descriptor on success and NULL on failure
+ */
+static struct dma_async_tx_descriptor *
+xilinx_vdma_dma_prep_interleaved(struct dma_chan *dchan,
+				 struct dma_interleaved_template *xt,
+				 unsigned long flags)
+{
+	struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);
+	struct xilinx_vdma_tx_descriptor *desc;
+	struct xilinx_vdma_tx_segment *segment, *prev = NULL;
+	struct xilinx_vdma_desc_hw *hw;
+
+	if (!is_slave_direction(xt->dir))
+		return NULL;
+
+	if (!xt->numf || !xt->sgl[0].size)
+		return NULL;
+
+	/* Allocate a transaction descriptor. */
+	desc = xilinx_vdma_alloc_tx_descriptor(chan);
+	if (!desc)
+		return NULL;
+
+	dma_async_tx_descriptor_init(&desc->async_tx, &chan->common);
+	desc->async_tx.tx_submit = xilinx_vdma_tx_submit;
+	async_tx_ack(&desc->async_tx);
+
+	/* Allocate the link descriptor from DMA pool */
+	segment = xilinx_vdma_alloc_tx_segment(chan);
+	if (!segment)
+		goto error;
+
+	/* Fill in the hardware descriptor */
+	hw = &segment->hw;
+	hw->vsize = xt->numf;
+	hw->hsize = xt->sgl[0].size;
+	hw->stride = xt->sgl[0].icg <<
+			XILINX_VDMA_FRMDLY_STRIDE_STRIDE_SHIFT;
+	hw->stride |= chan->config.frm_dly <<
+			XILINX_VDMA_FRMDLY_STRIDE_FRMDLY_SHIFT;
+
+	if (xt->dir != DMA_MEM_TO_DEV)
+		hw->buf_addr = xt->dst_start;
+	else
+		hw->buf_addr = xt->src_start;
+
+	/* Link the previous next descriptor to current */
+	prev = list_last_entry(&desc->segments,
+				struct xilinx_vdma_tx_segment, node);
+	prev->hw.next_desc = segment->phys;
+
+	/* Insert the segment into the descriptor segments list. */
+	list_add_tail(&segment->node, &desc->segments);
+
+	prev = segment;
+
+	/* Link the last hardware descriptor with the first. */
+	segment = list_first_entry(&desc->segments,
+				   struct xilinx_vdma_tx_segment, node);
+	prev->hw.next_desc = segment->phys;
+
+	return &desc->async_tx;
+
+error:
+	xilinx_vdma_free_tx_descriptor(chan, desc);
+	return NULL;
+}
+
+/**
+ * xilinx_vdma_terminate_all - Halt the channel and free descriptors
+ * @chan: Driver specific VDMA Channel pointer
+ */
+static void xilinx_vdma_terminate_all(struct xilinx_vdma_chan *chan)
+{
+	/* Halt the DMA engine */
+	xilinx_vdma_halt(chan);
+
+	/* Remove and free all of the descriptors in the lists */
+	xilinx_vdma_free_descriptors(chan);
+}
+
+/**
+ * xilinx_vdma_channel_set_config - Configure VDMA channel
+ * Run-time configuration for Axi VDMA, supports:
+ * . halt the channel
+ * . configure interrupt coalescing and inter-packet delay threshold
+ * . start/stop parking
+ * . enable genlock
+ *
+ * @dchan: DMA channel
+ * @cfg: VDMA device configuration pointer
+ *
+ * Return: '0' on success and failure value on error
+ */
+int xilinx_vdma_channel_set_config(struct dma_chan *dchan,
+					struct xilinx_vdma_config *cfg)
+{
+	struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);
+	u32 dmacr;
+
+	if (cfg->reset)
+		return xilinx_vdma_chan_reset(chan);
+
+	dmacr = vdma_ctrl_read(chan, XILINX_VDMA_REG_DMACR);
+
+	chan->config.frm_dly = cfg->frm_dly;
+	chan->config.park = cfg->park;
+
+	/* genlock settings */
+	chan->config.gen_lock = cfg->gen_lock;
+	chan->config.master = cfg->master;
+
+	if (cfg->gen_lock && chan->genlock) {
+		dmacr |= XILINX_VDMA_DMACR_GENLOCK_EN;
+		dmacr |= cfg->master << XILINX_VDMA_DMACR_MASTER_SHIFT;
+	}
+
+	chan->config.frm_cnt_en = cfg->frm_cnt_en;
+	if (cfg->park)
+		chan->config.park_frm = cfg->park_frm;
+	else
+		chan->config.park_frm = -1;
+
+	chan->config.coalesc = cfg->coalesc;
+	chan->config.delay = cfg->delay;
+
+	if (cfg->coalesc <= XILINX_VDMA_DMACR_FRAME_COUNT_MAX) {
+		dmacr |= cfg->coalesc << XILINX_VDMA_DMACR_FRAME_COUNT_SHIFT;
+		chan->config.coalesc = cfg->coalesc;
+	}
+
+	if (cfg->delay <= XILINX_VDMA_DMACR_DELAY_MAX) {
+		dmacr |= cfg->delay << XILINX_VDMA_DMACR_DELAY_SHIFT;
+		chan->config.delay = cfg->delay;
+	}
+
+	/* FSync Source selection */
+	dmacr &= ~XILINX_VDMA_DMACR_FSYNCSRC_MASK;
+	dmacr |= cfg->ext_fsync << XILINX_VDMA_DMACR_FSYNCSRC_SHIFT;
+
+	vdma_ctrl_write(chan, XILINX_VDMA_REG_DMACR, dmacr);
+
+	return 0;
+}
+EXPORT_SYMBOL(xilinx_vdma_channel_set_config);
+
+/**
+ * xilinx_vdma_device_control - Configure DMA channel of the device
+ * @dchan: DMA Channel pointer
+ * @cmd: DMA control command
+ * @arg: Channel configuration
+ *
+ * Return: '0' on success and failure value on error
+ */
+static int xilinx_vdma_device_control(struct dma_chan *dchan,
+				      enum dma_ctrl_cmd cmd, unsigned long arg)
+{
+	struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);
+
+	if (cmd != DMA_TERMINATE_ALL)
+		return -ENXIO;
+
+	xilinx_vdma_terminate_all(chan);
+
+	return 0;
+}
+
+/* -----------------------------------------------------------------------------
+ * Probe and remove
+ */
+
+/**
+ * xilinx_vdma_chan_remove - Per Channel remove function
+ * @chan: Driver specific VDMA channel
+ */
+static void xilinx_vdma_chan_remove(struct xilinx_vdma_chan *chan)
+{
+	/* Disable all interrupts */
+	vdma_ctrl_clr(chan, XILINX_VDMA_REG_DMACR,
+		      XILINX_VDMA_DMAXR_ALL_IRQ_MASK);
+
+	if (chan->irq > 0)
+		free_irq(chan->irq, chan);
+
+	tasklet_kill(&chan->tasklet);
+
+	list_del(&chan->common.device_node);
+}
+
+/**
+ * xilinx_vdma_chan_probe - Per Channel Probing
+ * It get channel features from the device tree entry and
+ * initialize special channel handling routines
+ *
+ * @xdev: Driver specific device structure
+ * @node: Device node
+ *
+ * Return: '0' on success and failure value on error
+ */
+static int xilinx_vdma_chan_probe(struct xilinx_vdma_device *xdev,
+				  struct device_node *node)
+{
+	struct xilinx_vdma_chan *chan;
+	bool has_dre = false;
+	u32 value, width;
+	int err;
+
+	/* Allocate and initialize the channel structure */
+	chan = devm_kzalloc(xdev->dev, sizeof(*chan), GFP_KERNEL);
+	if (!chan)
+		return -ENOMEM;
+
+	chan->dev = xdev->dev;
+	chan->xdev = xdev;
+	chan->has_sg = xdev->has_sg;
+
+	spin_lock_init(&chan->lock);
+	INIT_LIST_HEAD(&chan->pending_list);
+	INIT_LIST_HEAD(&chan->done_list);
+
+	/* Retrieve the channel properties from the device tree */
+	has_dre = of_property_read_bool(node, "xlnx,include-dre");
+
+	chan->genlock = of_property_read_bool(node, "xlnx,genlock-mode");
+
+	err = of_property_read_u32(node, "xlnx,datawidth", &value);
+	if (err) {
+		dev_err(xdev->dev, "missing xlnx,datawidth property\n");
+		return err;
+	}
+	width = value >> 3; /* Convert bits to bytes */
+
+	/* If data width is greater than 8 bytes, DRE is not in hw */
+	if (width > 8)
+		has_dre = false;
+
+	if (!has_dre)
+		xdev->common.copy_align = fls(width - 1);
+
+	if (of_device_is_compatible(node, "xlnx,axi-vdma-mm2s-channel")) {
+		chan->direction = DMA_MEM_TO_DEV;
+		chan->id = 0;
+
+		chan->ctrl_offset = XILINX_VDMA_MM2S_CTRL_OFFSET;
+		chan->desc_offset = XILINX_VDMA_MM2S_DESC_OFFSET;
+
+		if (xdev->flush_on_fsync == XILINX_VDMA_FLUSH_BOTH ||
+		    xdev->flush_on_fsync == XILINX_VDMA_FLUSH_MM2S)
+			chan->flush_on_fsync = true;
+	} else if (of_device_is_compatible(node,
+					    "xlnx,axi-vdma-s2mm-channel")) {
+		chan->direction = DMA_DEV_TO_MEM;
+		chan->id = 1;
+
+		chan->ctrl_offset = XILINX_VDMA_S2MM_CTRL_OFFSET;
+		chan->desc_offset = XILINX_VDMA_S2MM_DESC_OFFSET;
+
+		if (xdev->flush_on_fsync == XILINX_VDMA_FLUSH_BOTH ||
+		    xdev->flush_on_fsync == XILINX_VDMA_FLUSH_S2MM)
+			chan->flush_on_fsync = true;
+	} else {
+		dev_err(xdev->dev, "Invalid channel compatible node\n");
+		return -EINVAL;
+	}
+
+	/* Request the interrupt */
+	chan->irq = irq_of_parse_and_map(node, 0);
+	err = request_irq(chan->irq, xilinx_vdma_irq_handler, IRQF_SHARED,
+			  "xilinx-vdma-controller", chan);
+	if (err) {
+		dev_err(xdev->dev, "unable to request IRQ %d\n", chan->irq);
+		return err;
+	}
+
+	/* Initialize the tasklet */
+	tasklet_init(&chan->tasklet, xilinx_vdma_do_tasklet,
+			(unsigned long)chan);
+
+	/*
+	 * Initialize the DMA channel and add it to the DMA engine channels
+	 * list.
+	 */
+	chan->common.device = &xdev->common;
+
+	list_add_tail(&chan->common.device_node, &xdev->common.channels);
+	xdev->chan[chan->id] = chan;
+
+	/* Reset the channel */
+	err = xilinx_vdma_chan_reset(chan);
+	if (err < 0) {
+		dev_err(xdev->dev, "Reset channel failed\n");
+		return err;
+	}
+
+	return 0;
+}
+
+/**
+ * of_dma_xilinx_xlate - Translation function
+ * @dma_spec: Pointer to DMA specifier as found in the device tree
+ * @ofdma: Pointer to DMA controller data
+ *
+ * Return: DMA channel pointer on success and NULL on error
+ */
+static struct dma_chan *of_dma_xilinx_xlate(struct of_phandle_args *dma_spec,
+						struct of_dma *ofdma)
+{
+	struct xilinx_vdma_device *xdev = ofdma->of_dma_data;
+	int chan_id = dma_spec->args[0];
+
+	if (chan_id >= XILINX_VDMA_MAX_CHANS_PER_DEVICE)
+		return NULL;
+
+	return dma_get_slave_channel(&xdev->chan[chan_id]->common);
+}
+
+/**
+ * xilinx_vdma_probe - Driver probe function
+ * @pdev: Pointer to the platform_device structure
+ *
+ * Return: '0' on success and failure value on error
+ */
+static int xilinx_vdma_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct xilinx_vdma_device *xdev;
+	struct device_node *child;
+	struct resource *io;
+	u32 num_frames;
+	int i, err;
+
+	/* Allocate and initialize the DMA engine structure */
+	xdev = devm_kzalloc(&pdev->dev, sizeof(*xdev), GFP_KERNEL);
+	if (!xdev)
+		return -ENOMEM;
+
+	xdev->dev = &pdev->dev;
+
+	/* Request and map I/O memory */
+	io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	xdev->regs = devm_ioremap_resource(&pdev->dev, io);
+	if (IS_ERR(xdev->regs))
+		return PTR_ERR(xdev->regs);
+
+	/* Retrieve the DMA engine properties from the device tree */
+	xdev->has_sg = of_property_read_bool(node, "xlnx,include-sg");
+
+	err = of_property_read_u32(node, "xlnx,num-fstores", &num_frames);
+	if (err < 0) {
+		dev_err(xdev->dev, "missing xlnx,num-fstores property\n");
+		return err;
+	}
+
+	err = of_property_read_u32(node, "xlnx,flush-fsync",
+					&xdev->flush_on_fsync);
+	if (err < 0)
+		dev_warn(xdev->dev, "missing xlnx,flush-fsync property\n");
+
+	/* Initialize the DMA engine */
+	xdev->common.dev = &pdev->dev;
+
+	INIT_LIST_HEAD(&xdev->common.channels);
+	dma_cap_set(DMA_SLAVE, xdev->common.cap_mask);
+	dma_cap_set(DMA_PRIVATE, xdev->common.cap_mask);
+
+	xdev->common.device_alloc_chan_resources =
+				xilinx_vdma_alloc_chan_resources;
+	xdev->common.device_free_chan_resources =
+				xilinx_vdma_free_chan_resources;
+	xdev->common.device_prep_interleaved_dma =
+				xilinx_vdma_dma_prep_interleaved;
+	xdev->common.device_control = xilinx_vdma_device_control;
+	xdev->common.device_tx_status = xilinx_vdma_tx_status;
+	xdev->common.device_issue_pending = xilinx_vdma_issue_pending;
+
+	platform_set_drvdata(pdev, xdev);
+
+	/* Initialize the channels */
+	for_each_child_of_node(node, child) {
+		err = xilinx_vdma_chan_probe(xdev, child);
+		if (err < 0)
+			goto error;
+	}
+
+	for (i = 0; i < XILINX_VDMA_MAX_CHANS_PER_DEVICE; i++)
+		if (xdev->chan[i])
+			xdev->chan[i]->num_frms = num_frames;
+
+	/* Register the DMA engine with the core */
+	dma_async_device_register(&xdev->common);
+
+	err = of_dma_controller_register(node, of_dma_xilinx_xlate,
+					 xdev);
+	if (err < 0) {
+		dev_err(&pdev->dev, "Unable to register DMA to DT\n");
+		dma_async_device_unregister(&xdev->common);
+		goto error;
+	}
+
+	dev_info(&pdev->dev, "Xilinx AXI VDMA Engine Driver Probed!!\n");
+
+	return 0;
+
+error:
+	for (i = 0; i < XILINX_VDMA_MAX_CHANS_PER_DEVICE; i++)
+		if (xdev->chan[i])
+			xilinx_vdma_chan_remove(xdev->chan[i]);
+
+	return err;
+}
+
+/**
+ * xilinx_vdma_remove - Driver remove function
+ * @pdev: Pointer to the platform_device structure
+ *
+ * Return: Always '0'
+ */
+static int xilinx_vdma_remove(struct platform_device *pdev)
+{
+	struct xilinx_vdma_device *xdev = platform_get_drvdata(pdev);
+	int i;
+
+	of_dma_controller_free(pdev->dev.of_node);
+
+	dma_async_device_unregister(&xdev->common);
+
+	for (i = 0; i < XILINX_VDMA_MAX_CHANS_PER_DEVICE; i++)
+		if (xdev->chan[i])
+			xilinx_vdma_chan_remove(xdev->chan[i]);
+
+	return 0;
+}
+
+static const struct of_device_id xilinx_vdma_of_ids[] = {
+	{ .compatible = "xlnx,axi-vdma-1.00.a",},
+	{}
+};
+
+static struct platform_driver xilinx_vdma_driver = {
+	.driver = {
+		.name = "xilinx-vdma",
+		.owner = THIS_MODULE,
+		.of_match_table = xilinx_vdma_of_ids,
+	},
+	.probe = xilinx_vdma_probe,
+	.remove = xilinx_vdma_remove,
+};
+
+module_platform_driver(xilinx_vdma_driver);
+
+MODULE_AUTHOR("Xilinx, Inc.");
+MODULE_DESCRIPTION("Xilinx VDMA driver");
+MODULE_LICENSE("GPL v2");

include/linux/amba/xilinx_dma.h

···
+/*
+ * Xilinx DMA Engine drivers support header file
+ *
+ * Copyright (C) 2010-2014 Xilinx, Inc. All rights reserved.
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __DMA_XILINX_DMA_H
+#define __DMA_XILINX_DMA_H
+
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+
+/**
+ * struct xilinx_vdma_config - VDMA Configuration structure
+ * @frm_dly: Frame delay
+ * @gen_lock: Whether in gen-lock mode
+ * @master: Master that it syncs to
+ * @frm_cnt_en: Enable frame count enable
+ * @park: Whether wants to park
+ * @park_frm: Frame to park on
+ * @coalesc: Interrupt coalescing threshold
+ * @delay: Delay counter
+ * @reset: Reset Channel
+ * @ext_fsync: External Frame Sync source
+ */
+struct xilinx_vdma_config {
+	int frm_dly;
+	int gen_lock;
+	int master;
+	int frm_cnt_en;
+	int park;
+	int park_frm;
+	int coalesc;
+	int delay;
+	int reset;
+	int ext_fsync;
+};
+
+int xilinx_vdma_channel_set_config(struct dma_chan *dchan,
+					struct xilinx_vdma_config *cfg);
+
+#endif