[PATCH v4 2/2] dma: Add Xilinx AXI Central Direct Memory Access Engine driver support

Kedareswara rao Appana
2015-05-21T17:22:54Z

This is the driver for the AXI Central Direct Memory Access (AXI
CDMA) core, which is a soft Xilinx IP core that provides high-bandwidth
Direct Memory Access (DMA) between a memory-mapped source address and a
memory-mapped destination address.

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

Signed-off-by: Srikanth Thokala <sthokal@xilinx.com>
Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
---
This patch is rebased on the commit
Merge tag 'nfs-for-4.1-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Changes in v4:
- used GFP_NOWAIT instead of GFP_KERNEL during the desc allocation
- Modified spin_lock handling moved the spin_lock to the appropriate functions
- device_control api is removed and updated driver as per newer APi's.
Changes in v3:
- Check for CDMA idle condition before changing the configuration.
- Modified the xilinx_dma.h header file location to the
include/linux/dma/xilinx_dma.h
Changes in v2:
- Rebased on 3.16-rc7.

drivers/dma/Kconfig | 12 +
drivers/dma/xilinx/Makefile | 1 +
drivers/dma/xilinx/xilinx_cdma.c | 987 +++++++++++++++++++++++++++++++++++++++
include/linux/dma/xilinx_dma.h | 15 +-
4 files changed, 1014 insertions(+), 1 deletion(-)
create mode 100644 drivers/dma/xilinx/xilinx_cdma.c

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index bda2cb0..c42cf24 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -492,4 +492,16 @@ config QCOM_BAM_DMA
Enable support for the QCOM BAM DMA controller. This controller
provides DMA capabilities for a variety of on-chip devices.

+config XILINX_CDMA
+ tristate "Xilinx AXI CDMA Engine"
+ depends on (ARCH_ZYNQ || MICROBLAZE)
+ select DMA_ENGINE
+ help
+ Enable support for Xilinx AXI CDMA Soft IP.
+
+ The AXI CDMA is a soft IP which provides high-bandwidth
+ Direct Memory Access (DMA) between a memory-mapped source
+ address and a memory-mapped destination address using the
+ AXI4 protocol.
+
endif
diff --git a/drivers/dma/xilinx/Makefile b/drivers/dma/xilinx/Makefile
index 3c4e9f2..f909d34 100644
--- a/drivers/dma/xilinx/Makefile
+++ b/drivers/dma/xilinx/Makefile
@@ -1 +1,2 @@
obj-$(CONFIG_XILINX_VDMA) += xilinx_vdma.o
+obj-$(CONFIG_XILINX_VDMA) += xilinx_cdma.o
diff --git a/drivers/dma/xilinx/xilinx_cdma.c b/drivers/dma/xilinx/xilinx_cdma.c
new file mode 100644
index 0000000..eda443a
--- /dev/null
+++ b/drivers/dma/xilinx/xilinx_cdma.c
@@ -0,0 +1,987 @@
+/*
+ * DMA driver for Xilinx Central DMA Engine
+ *
+ * Copyright (C) 2010 - 2015 Xilinx, Inc. All rights reserved.
+ *
+ * Based on the Freescale DMA driver.
+ *
+ * Description:
+ * The AXI CDMA, is a soft IP, which provides high-bandwidth Direct Memory
+ * Access (DMA) between a memory-mapped source address and a memory-mapped
+ * destination address.
+ *
+ * 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/bitops.h>
+#include <linux/dmapool.h>
+#include <linux/dma/xilinx_dma.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_irq.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+
+#include "../dmaengine.h"
+
+/* Register Offsets */
+#define XILINX_CDMA_CONTROL_OFFSET 0x00
+#define XILINX_CDMA_STATUS_OFFSET 0x04
+#define XILINX_CDMA_CDESC_OFFSET 0x08
+#define XILINX_CDMA_TDESC_OFFSET 0x10
+#define XILINX_CDMA_SRCADDR_OFFSET 0x18
+#define XILINX_CDMA_DSTADDR_OFFSET 0x20
+#define XILINX_CDMA_BTT_OFFSET 0x28
+
+/* General register bits definitions */
+#define XILINX_CDMA_CR_RESET BIT(2)
+#define XILINX_CDMA_CR_SGMODE BIT(3)
+
+#define XILINX_CDMA_SR_IDLE BIT(1)
+
+#define XILINX_CDMA_XR_IRQ_IOC_MASK BIT(12)
+#define XILINX_CDMA_XR_IRQ_DELAY_MASK BIT(13)
+#define XILINX_CDMA_XR_IRQ_ERROR_MASK BIT(14)
+#define XILINX_CDMA_XR_IRQ_ALL_MASK GENMASK(14, 12)
+
+#define XILINX_CDMA_XR_DELAY_MASK GENMASK(31, 24)
+#define XILINX_CDMA_XR_COALESCE_MASK GENMASK(23, 16)
+
+#define XILINX_CDMA_DELAY_MAX GENMASK(7, 0)
+#define XILINX_CDMA_DELAY_SHIFT 24
+
+#define XILINX_CDMA_COALESCE_MAX GENMASK(7, 0)
+#define XILINX_CDMA_COALESCE_SHIFT 16
+
+/* Delay loop counter to prevent hardware failure */
+#define XILINX_CDMA_RESET_LOOP 1000000
+
+/* Maximum transfer length */
+#define XILINX_CDMA_MAX_TRANS_LEN GENMASK(22, 0)
+
+/**
+ * struct xilinx_cdma_desc_hw - Hardware Descriptor
+ * @next_desc: Next Descriptor Pointer @0x00
+ * @pad1: Reserved @0x04
+ * @src_addr: Source address @0x08
+ * @pad2: Reserved @0x0C
+ * @dest_addr: Destination address @0x10
+ * @pad3: Reserved @0x14
+ * @control: Control field @0x18
+ * @status: Status field @0x1C
+ */
+struct xilinx_cdma_desc_hw {
+ u32 next_desc;
+ u32 pad1;
+ u32 src_addr;
+ u32 pad2;
+ u32 dest_addr;
+ u32 pad3;
+ u32 control;
+ u32 status;
+} __aligned(64);
+
+/**
+ * struct xilinx_cdma_tx_segment - Descriptor segment
+ * @hw: Hardware descriptor
+ * @node: Node in the descriptor segments list
+ * @phys: Physical address of segment
+ */
+struct xilinx_cdma_tx_segment {
+ struct xilinx_cdma_desc_hw hw;
+ struct list_head node;
+ dma_addr_t phys;
+} __aligned(64);
+
+/**
+ * struct xilinx_cdma_tx_descriptor - Per Transaction structure
+ * @async_tx: Async transaction descriptor
+ * @segments: TX segments list
+ * @node: Node in the channel descriptors list
+ */
+struct xilinx_cdma_tx_descriptor {
+ struct dma_async_tx_descriptor async_tx;
+ struct list_head segments;
+ struct list_head node;
+};
+
+/**
+ * struct xilinx_cdma_chan - Driver specific cdma channel structure
+ * @xdev: Driver specific device structure
+ * @lock: Descriptor operation lock
+ * @done_list: Complete descriptors
+ * @pending_list: Descriptors waiting
+ * @active_desc: Active descriptor
+ * @common: DMA common channel
+ * @desc_pool: Descriptors pool
+ * @dev: The dma device
+ * @irq: Channel IRQ
+ * @has_sg: Support scatter transfers
+ * @err: Channel has errors
+ * @idle: Channel status
+ * @tasklet: Cleanup work after irq
+ */
+struct xilinx_cdma_chan {
+ struct xilinx_cdma_device *xdev;
+ spinlock_t lock;
+ struct list_head done_list;
+ struct list_head pending_list;
+ struct xilinx_cdma_tx_descriptor *active_desc;
+ struct dma_chan common;
+ struct dma_pool *desc_pool;
+ struct device *dev;
+ int irq;
+ bool has_sg;
+ int err;
+ bool idle;
+ struct tasklet_struct tasklet;
+};
+
+/**
+ * struct xilinx_cdma_device - CDMA device structure
+ * @regs: I/O mapped base address
+ * @dev: Device Structure
+ * @common: DMA device structure
+ * @chan: Driver specific cdma channel
+ * @has_sg: Specifies whether Scatter-Gather is present or not
+ */
+struct xilinx_cdma_device {
+ void __iomem *regs;
+ struct device *dev;
+ struct dma_device common;
+ struct xilinx_cdma_chan *chan;
+ bool has_sg;
+};
+
+/* Macros */
+#define to_xilinx_chan(chan) \
+ container_of(chan, struct xilinx_cdma_chan, common)
+#define to_cdma_tx_descriptor(tx) \
+ container_of(tx, struct xilinx_cdma_tx_descriptor, async_tx)
+
+/* IO accessors */
+static inline void cdma_write(struct xilinx_cdma_chan *chan, u32 reg, u32 val)
+{
+ writel(val, chan->xdev->regs + reg);
+}
+
+static inline u32 cdma_read(struct xilinx_cdma_chan *chan, u32 reg)
+{
+ return readl(chan->xdev->regs + reg);
+}
+
+static inline void cdma_ctrl_clr(struct xilinx_cdma_chan *chan, u32 reg,
+ u32 clr)
+{
+ cdma_write(chan, reg, cdma_read(chan, reg) & ~clr);
+}
+
+static inline void cdma_ctrl_set(struct xilinx_cdma_chan *chan, u32 reg,
+ u32 set)
+{
+ cdma_write(chan, reg, cdma_read(chan, reg) | set);
+}
+
+/* -----------------------------------------------------------------------------
+ * Descriptors and segments alloc and free
+ */
+
+/**
+ * xilinx_cdma_alloc_tx_segment - Allocate transaction segment
+ * @chan: Driver specific cdma channel
+ *
+ * Return: The allocated segment on success and NULL on failure.
+ */
+static struct xilinx_cdma_tx_segment *
+xilinx_cdma_alloc_tx_segment(struct xilinx_cdma_chan *chan)
+{
+ struct xilinx_cdma_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_cdma_free_tx_segment - Free transaction segment
+ * @chan: Driver specific cdma channel
+ * @segment: cdma transaction segment
+ */
+static void xilinx_cdma_free_tx_segment(struct xilinx_cdma_chan *chan,
+ struct xilinx_cdma_tx_segment *segment)
+{
+ dma_pool_free(chan->desc_pool, segment, segment->phys);
+}
+
+/**
+ * xilinx_cdma_tx_descriptor - Allocate transaction descriptor
+ * @chan: Driver specific cdma channel
+ *
+ * Return: The allocated descriptor on success and NULL on failure.
+ */
+static struct xilinx_cdma_tx_descriptor *
+xilinx_cdma_alloc_tx_descriptor(struct xilinx_cdma_chan *chan)
+{
+ struct xilinx_cdma_tx_descriptor *desc;
+
+ desc = kzalloc(sizeof(*desc), GFP_KERNEL);
+ if (!desc)
+ return NULL;
+
+ INIT_LIST_HEAD(&desc->segments);
+
+ return desc;
+}
+
+/**
+ * xilinx_cdma_free_tx_descriptor - Free transaction descriptor
+ * @chan: Driver specific cdma channel
+ * @desc: cdma transaction descriptor
+ */
+static void
+xilinx_cdma_free_tx_descriptor(struct xilinx_cdma_chan *chan,
+ struct xilinx_cdma_tx_descriptor *desc)
+{
+ struct xilinx_cdma_tx_segment *segment, *next;
+
+ if (!desc)
+ return;
+
+ list_for_each_entry_safe(segment, next, &desc->segments, node) {
+ list_del(&segment->node);
+ xilinx_cdma_free_tx_segment(chan, segment);
+ }
+
+ kfree(desc);
+}
+
+/**
+ * xilinx_cdma_alloc_chan_resources - Allocate channel resources
+ * @dchan: DMA channel
+ *
+ * Return: '0' on success and failure value on error
+ */
+static int xilinx_cdma_alloc_chan_resources(struct dma_chan *dchan)
+{
+ struct xilinx_cdma_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 DMA specification requirement.
+ */
+ chan->desc_pool = dma_pool_create("xilinx_cdma_desc_pool",
+ chan->dev,
+ sizeof(struct xilinx_cdma_tx_segment),
+ __alignof__(struct xilinx_cdma_tx_segment), 0);
+ if (!chan->desc_pool) {
+ dev_err(chan->dev,
+ "unable to allocate channel descriptor pool\n");
+ return -ENOMEM;
+ }
+
+ dma_cookie_init(dchan);
+ return 0;
+}
+
+/**
+ * xilinx_cdma_free_desc_list - Free descriptors list
+ * @chan: Driver specific cdma channel
+ * @list: List to parse and delete the descriptor
+ */
+static void xilinx_cdma_free_desc_list(struct xilinx_cdma_chan *chan,
+ struct list_head *list)
+{
+ struct xilinx_cdma_tx_descriptor *desc, *next;
+
+ list_for_each_entry_safe(desc, next, list, node) {
+ list_del(&desc->node);
+ xilinx_cdma_free_tx_descriptor(chan, desc);
+ }
+}
+
+/**
+ * xilinx_cdma_free_chan_resources - Free channel resources
+ * @dchan: DMA channel
+ */
+static void xilinx_cdma_free_chan_resources(struct dma_chan *dchan)
+{
+ struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
+ unsigned long flags;
+
+ spin_lock_irqsave(&chan->lock, flags);
+ xilinx_cdma_free_desc_list(chan, &chan->done_list);
+ xilinx_cdma_free_desc_list(chan, &chan->pending_list);
+ spin_unlock_irqrestore(&chan->lock, flags);
+
+ dma_pool_destroy(chan->desc_pool);
+ chan->desc_pool = NULL;
+}
+
+/**
+ * xilinx_cdma_chan_desc_cleanup - Clean channel descriptors
+ * @chan: Driver specific cdma channel
+ */
+static void xilinx_cdma_chan_desc_cleanup(struct xilinx_cdma_chan *chan)
+{
+ struct xilinx_cdma_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_cdma_free_tx_descriptor(chan, desc);
+ }
+
+ spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+/**
+ * xilinx_cdma_tx_status - Get CDMA transaction status
+ * @dchan: DMA channel
+ * @cookie: Transaction identifier
+ * @txstate: Transaction state
+ *
+ * Return: DMA transaction status
+ */
+static enum dma_status xilinx_tx_status(struct dma_chan *dchan,
+ dma_cookie_t cookie,
+ struct dma_tx_state *txstate)
+{
+ return dma_cookie_status(dchan, cookie, txstate);
+}
+
+/**
+ * xilinx_cdma_is_idle - Check if cdma channel is idle
+ * @chan: Driver specific cdma channel
+ *
+ * Return: 'true' if idle, 'false' if not.
+ */
+static bool cdma_is_idle(struct xilinx_cdma_chan *chan)
+{
+ return cdma_read(chan, XILINX_CDMA_STATUS_OFFSET) & XILINX_CDMA_SR_IDLE;
+}
+
+/**
+ * xilinx_cdma_start_transfer - Starts cdma transfer
+ * @chan: Driver specific channel struct pointer
+ */
+static void xilinx_cdma_start_transfer(struct xilinx_cdma_chan *chan)
+{
+ struct xilinx_cdma_tx_descriptor *desc;
+ struct xilinx_cdma_tx_segment *head, *tail;
+
+ if (chan->err)
+ return;
+
+ if (list_empty(&chan->pending_list))
+ return;
+
+ if (!chan->idle)
+ return;
+
+ /* If hardware is busy, cannot submit */
+ if (chan->has_sg && !cdma_is_idle(chan)) {
+ tail = list_entry(desc->segments.prev,
+ struct xilinx_cdma_tx_segment, node);
+ cdma_write(chan, XILINX_CDMA_TDESC_OFFSET, tail->phys);
+ goto out_free_desc;
+ }
+
+ desc = list_first_entry(&chan->pending_list,
+ struct xilinx_cdma_tx_descriptor, node);
+
+ if (chan->has_sg) {
+ head = list_first_entry(&desc->segments,
+ struct xilinx_cdma_tx_segment, node);
+ tail = list_entry(desc->segments.prev,
+ struct xilinx_cdma_tx_segment, node);
+
+ cdma_write(chan, XILINX_CDMA_CDESC_OFFSET, head->phys);
+
+ /* Update tail ptr register which will start the transfer */
+ cdma_write(chan, XILINX_CDMA_TDESC_OFFSET, tail->phys);
+ } else {
+ /* In simple mode */
+ struct xilinx_cdma_tx_segment *segment;
+ struct xilinx_cdma_desc_hw *hw;
+
+ segment = list_first_entry(&desc->segments,
+ struct xilinx_cdma_tx_segment,
+ node);
+
+ hw = &segment->hw;
+
+ cdma_write(chan, XILINX_CDMA_SRCADDR_OFFSET, hw->src_addr);
+ cdma_write(chan, XILINX_CDMA_DSTADDR_OFFSET, hw->dest_addr);
+
+ /* Start the transfer */
+ cdma_write(chan, XILINX_CDMA_BTT_OFFSET,
+ hw->control & XILINX_CDMA_MAX_TRANS_LEN);
+ }
+
+out_free_desc:
+ list_del(&desc->node);
+ chan->idle = false;
+ chan->active_desc = desc;
+}
+
+/**
+ * xilinx_cdma_issue_pending - Issue pending transactions
+ * @dchan: DMA channel
+ */
+static void xilinx_cdma_issue_pending(struct dma_chan *dchan)
+{
+ struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
+ unsigned long flags;
+
+ spin_lock_irqsave(&chan->lock, flags);
+ xilinx_cdma_start_transfer(chan);
+ spin_unlock_irqrestore(&chan->lock, flags);
+}
+
+/**
+ * xilinx_cdma_complete_descriptor - Mark the active descriptor as complete
+ * @chan : xilinx DMA channel
+ */
+static void xilinx_cdma_complete_descriptor(struct xilinx_cdma_chan *chan)
+{
+ struct xilinx_cdma_tx_descriptor *desc;
+
+ desc = chan->active_desc;
+ if (!desc) {
+ dev_dbg(chan->dev, "no running descriptors\n");
+ return;
+ }
+
+ dma_cookie_complete(&desc->async_tx);
+ list_add_tail(&desc->node, &chan->done_list);
+
+ chan->active_desc = NULL;
+}
+
+/**
+ * xilinx_cdma_chan_reset - Reset CDMA channel
+ * @chan: Driver specific CDMA channel
+ *
+ * Return: '0' on success and failure value on error
+ */
+static int xilinx_cdma_chan_reset(struct xilinx_cdma_chan *chan)
+{
+ int loop = XILINX_CDMA_RESET_LOOP;
+ u32 tmp;
+
+ cdma_ctrl_set(chan, XILINX_CDMA_CONTROL_OFFSET,
+ XILINX_CDMA_CR_RESET);
+
+ tmp = cdma_read(chan, XILINX_CDMA_CONTROL_OFFSET) &
+ XILINX_CDMA_CR_RESET;
+
+ /* Wait for the hardware to finish reset */
+ do {
+ tmp = cdma_read(chan, XILINX_CDMA_CONTROL_OFFSET) &
+ XILINX_CDMA_CR_RESET;
+ } while (loop-- && tmp);
+
+ if (!loop) {
+ dev_err(chan->dev, "reset timeout, cr %x, sr %x\n",
+ cdma_read(chan, XILINX_CDMA_CONTROL_OFFSET),
+ cdma_read(chan, XILINX_CDMA_STATUS_OFFSET));
+ return -EBUSY;
+ }
+
+ /* Enable interrupts */
+ cdma_ctrl_set(chan, XILINX_CDMA_CONTROL_OFFSET,
+ XILINX_CDMA_XR_IRQ_ALL_MASK);
+
+ /* Enable SG Mode */
+ if (chan->has_sg)
+ cdma_ctrl_set(chan, XILINX_CDMA_CONTROL_OFFSET,
+ XILINX_CDMA_CR_SGMODE);
+ return 0;
+}
+
+/**
+ * xilinx_cdma_irq_handler - CDMA Interrupt handler
+ * @irq: IRQ number
+ * @data: Pointer to the Xilinx CDMA channel structure
+ *
+ * Return: IRQ_HANDLED/IRQ_NONE
+ */
+static irqreturn_t xilinx_cdma_irq_handler(int irq, void *data)
+{
+ struct xilinx_cdma_chan *chan = data;
+ u32 status;
+
+ status = cdma_read(chan, XILINX_CDMA_STATUS_OFFSET);
+ if (!(status & XILINX_CDMA_XR_IRQ_ALL_MASK))
+ return IRQ_NONE;
+
+ /* Ack the interrupts */
+ cdma_write(chan, XILINX_CDMA_STATUS_OFFSET,
+ XILINX_CDMA_XR_IRQ_ALL_MASK);
+
+ if (status & XILINX_CDMA_XR_IRQ_ERROR_MASK) {
+ dev_err(chan->dev,
+ "Channel %x has errors %x, cdr %x tdr %x\n",
+ (u32)chan,
+ (u32)cdma_read(chan, XILINX_CDMA_STATUS_OFFSET),
+ (u32)cdma_read(chan, XILINX_CDMA_CDESC_OFFSET),
+ (u32)cdma_read(chan, XILINX_CDMA_TDESC_OFFSET));
+ chan->err = true;
+ }
+
+ /*
+ * Device takes too long to do the transfer when user requires
+ * responsiveness
+ */
+ if (status & XILINX_CDMA_XR_IRQ_DELAY_MASK)
+ dev_dbg(chan->dev, "Inter-packet latency too long\n");
+
+ if (status & XILINX_CDMA_XR_IRQ_IOC_MASK) {
+ spin_lock(&chan->lock);
+ xilinx_cdma_complete_descriptor(chan);
+ chan->idle = true;
+ xilinx_cdma_start_transfer(chan);
+ spin_unlock(&chan->lock);
+ }
+
+ tasklet_schedule(&chan->tasklet);
+ return IRQ_HANDLED;
+}
+
+/**
+ * xilinx_cdma_do_tasklet - Schedule completion tasklet
+ * @data: Pointer to the Xilinx cdma channel structure
+ */
+static void xilinx_cdma_do_tasklet(unsigned long data)
+{
+ struct xilinx_cdma_chan *chan = (struct xilinx_cdma_chan *)data;
+
+ xilinx_cdma_chan_desc_cleanup(chan);
+}
+
+/**
+ * xilinx_cdma_tx_submit - Submit DMA transaction
+ * @tx: Async transaction descriptor
+ *
+ * Return: cookie value on success and failure value on error
+ */
+static dma_cookie_t xilinx_cdma_tx_submit(struct dma_async_tx_descriptor *tx)
+{
+ struct xilinx_cdma_chan *chan = to_xilinx_chan(tx->chan);
+ struct xilinx_cdma_tx_descriptor *desc = to_cdma_tx_descriptor(tx);
+ 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_cdma_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);
+
+ spin_unlock_irqrestore(&chan->lock, flags);
+
+ return cookie;
+}
+
+/**
+ * xilinx_cdma_prep_memcpy - prepare descriptors for a memcpy transaction
+ * @dchan: DMA channel
+ * @dma_dst: destination address
+ * @dma_src: source address
+ * @len: transfer length
+ * @flags: transfer ack flags
+ *
+ * Return: Async transaction descriptor on success and NULL on failure
+ */
+static struct dma_async_tx_descriptor *
+xilinx_cdma_prep_memcpy(struct dma_chan *dchan, dma_addr_t dma_dst,
+ dma_addr_t dma_src, size_t len, unsigned long flags)
+{
+ struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
+ struct xilinx_cdma_desc_hw *hw;
+ struct xilinx_cdma_tx_descriptor *desc;
+ struct xilinx_cdma_tx_segment *segment, *prev;
+
+ if (!len || len > XILINX_CDMA_MAX_TRANS_LEN)
+ return NULL;
+
+ desc = xilinx_cdma_alloc_tx_descriptor(chan);
+ if (!desc)
+ return NULL;
+
+ dma_async_tx_descriptor_init(&desc->async_tx, &chan->common);
+ desc->async_tx.tx_submit = xilinx_cdma_tx_submit;
+ async_tx_ack(&desc->async_tx);
+
+ /* Allocate the link descriptor from DMA pool */
+ segment = xilinx_cdma_alloc_tx_segment(chan);
+ if (!segment)
+ goto error;
+
+ hw = &segment->hw;
+ hw->control = len;
+ hw->src_addr = dma_src;
+ hw->dest_addr = dma_dst;
+
+ /* Fill the previous next descriptor with current */
+ prev = list_last_entry(&desc->segments,
+ struct xilinx_cdma_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_cdma_tx_segment, node);
+ prev->hw.next_desc = segment->phys;
+
+ return &desc->async_tx;
+
+error:
+ xilinx_cdma_free_tx_descriptor(chan, desc);
+ return NULL;
+}
+
+/**
+ * xilinx_cdma_terminate_all - Free the descriptors
+ * @dchan: DMA Channel pointer
+ *
+ * Return: '0' always
+ */
+static int xilinx_cdma_terminate_all(struct dma_chan *dchan)
+{
+ struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
+ unsigned long flags;
+
+ spin_lock_irqsave(&chan->lock, flags);
+
+ /* Reset the channel */
+ xilinx_cdma_chan_reset(chan);
+
+ /* Remove and free all of the descriptors in the lists */
+ xilinx_cdma_free_desc_list(chan, &chan->pending_list);
+ xilinx_cdma_free_desc_list(chan, &chan->done_list);
+
+ spin_unlock_irqrestore(&chan->lock, flags);
+
+ return 0;
+}
+
+/**
+ * xilinx_cdma_channel_set_config - Configure cdma channel
+ * @dchan: DMA channel
+ * @cfg: cdma device configuration pointer
+ *
+ * Return: '0' on success and failure value on error
+ */
+int xilinx_cdma_channel_set_config(struct dma_chan *dchan,
+ struct xilinx_cdma_config *cfg)
+{
+ struct xilinx_cdma_chan *chan = to_xilinx_chan(dchan);
+ u32 reg = cdma_read(chan, XILINX_CDMA_CONTROL_OFFSET);
+
+ if (!cdma_is_idle(chan))
+ return -EBUSY;
+
+ if (cfg->reset)
+ return xilinx_cdma_chan_reset(chan);
+
+ if (cfg->coalesc <= XILINX_CDMA_COALESCE_MAX) {
+ reg &= ~XILINX_CDMA_XR_COALESCE_MASK;
+ reg |= cfg->coalesc << XILINX_CDMA_COALESCE_SHIFT;
+ }
+
+ if (cfg->delay <= XILINX_CDMA_DELAY_MAX) {
+ reg &= ~XILINX_CDMA_XR_DELAY_MASK;
+ reg |= cfg->delay << XILINX_CDMA_DELAY_SHIFT;
+ }
+
+ cdma_write(chan, XILINX_CDMA_CONTROL_OFFSET, reg);
+
+ return 0;
+}
+EXPORT_SYMBOL(xilinx_cdma_channel_set_config);
+
+/* -----------------------------------------------------------------------------
+ * Probe and remove
+ */
+
+/**
+ * xilinx_cdma_free_channel - Channel remove function
+ * @chan: Driver specific cdma channel
+ */
+static void xilinx_cdma_free_channel(struct xilinx_cdma_chan *chan)
+{
+ /* Disable Interrupts */
+ cdma_ctrl_clr(chan, XILINX_CDMA_CONTROL_OFFSET,
+ XILINX_CDMA_XR_IRQ_ALL_MASK);
+
+ if (chan->irq > 0)
+ free_irq(chan->irq, chan);
+
+ tasklet_kill(&chan->tasklet);
+
+ list_del(&chan->common.device_node);
+}
+
+/**
+ * xilinx_cdma_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_cdma_chan_probe(struct xilinx_cdma_device *xdev,
+ struct device_node *node)
+{
+ struct xilinx_cdma_chan *chan;
+ bool has_dre;
+ u32 value, width;
+ int err;
+
+ /* Alloc channel */
+ chan = devm_kzalloc(xdev->dev, sizeof(*chan), GFP_NOWAIT);
+ if (!chan)
+ return -ENOMEM;
+
+ chan->dev = xdev->dev;
+ chan->has_sg = xdev->has_sg;
+ chan->xdev = xdev;
+
+ 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");
+
+ err = of_property_read_u32(node, "xlnx,datawidth", &value);
+ if (err) {
+ dev_err(xdev->dev, "unable to read datawidth property");
+ 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);
+
+ /* Request the interrupt */
+ chan->irq = irq_of_parse_and_map(node, 0);
+ err = request_irq(chan->irq, xilinx_cdma_irq_handler, IRQF_SHARED,
+ "xilinx-cdma-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_cdma_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;
+
+ /* Initialize the channel */
+ err = xilinx_cdma_chan_reset(chan);
+ if (err) {
+ dev_err(xdev->dev, "Reset channel failed\n");
+ return err;
+ }
+
+ chan->idle = true;
+
+ 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_cdma_device *xdev = ofdma->of_dma_data;
+
+ return dma_get_slave_channel(&xdev->chan->common);
+}
+
+/**
+ * xilinx_cdma_probe - Driver probe function
+ * @pdev: Pointer to the platform_device structure
+ *
+ * Return: '0' on success and failure value on error
+ */
+static int xilinx_cdma_probe(struct platform_device *pdev)
+{
+ struct xilinx_cdma_device *xdev;
+ struct device_node *child, *node;
+ struct resource *res;
+ int ret;
+
+ xdev = devm_kzalloc(&pdev->dev, sizeof(*xdev), GFP_KERNEL);
+ if (!xdev)
+ return -ENOMEM;
+
+ xdev->dev = &(pdev->dev);
+ INIT_LIST_HEAD(&xdev->common.channels);
+
+ node = pdev->dev.of_node;
+
+ /* Map the registers */
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ xdev->regs = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(xdev->regs))
+ return PTR_ERR(xdev->regs);
+
+ /* Check if SG is enabled */
+ xdev->has_sg = of_property_read_bool(node, "xlnx,include-sg");
+
+ dma_cap_set(DMA_MEMCPY, xdev->common.cap_mask);
+ xdev->common.device_prep_dma_memcpy = xilinx_cdma_prep_memcpy;
+ xdev->common.device_terminate_all = xilinx_cdma_terminate_all;
+ xdev->common.device_issue_pending = xilinx_cdma_issue_pending;
+ xdev->common.device_alloc_chan_resources =
+ xilinx_cdma_alloc_chan_resources;
+ xdev->common.device_free_chan_resources =
+ xilinx_cdma_free_chan_resources;
+ xdev->common.device_tx_status = xilinx_tx_status;
+ xdev->common.dev = &pdev->dev;
+
+ platform_set_drvdata(pdev, xdev);
+
+ child = of_get_next_child(node, NULL);
+ if (!child) {
+ dev_err(&pdev->dev, "No channel found\n");
+ return PTR_ERR(child);
+ }
+
+ ret = xilinx_cdma_chan_probe(xdev, child);
+ if (ret) {
+ dev_err(&pdev->dev, "Probing channel failed\n");
+ goto free_chan_resources;
+ }
+
+ dma_async_device_register(&xdev->common);
+
+ ret = of_dma_controller_register(node, of_dma_xilinx_xlate, xdev);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to register DMA to DT\n");
+ dma_async_device_unregister(&xdev->common);
+ goto free_chan_resources;
+ }
+
+ dev_info(&pdev->dev, "Xilinx AXI CDMA Engine driver Probed!!\n");
+
+ return 0;
+
+free_chan_resources:
+ xilinx_cdma_free_channel(xdev->chan);
+
+ return ret;
+}
+
+/**
+ * xilinx_cdma_remove - Driver remove function
+ * @pdev: Pointer to the platform_device structure
+ *
+ * Return: Always '0'
+ */
+static int xilinx_cdma_remove(struct platform_device *pdev)
+{
+ struct xilinx_cdma_device *xdev = platform_get_drvdata(pdev);
+
+ of_dma_controller_free(pdev->dev.of_node);
+ dma_async_device_unregister(&xdev->common);
+
+ xilinx_cdma_free_channel(xdev->chan);
+
+ return 0;
+}
+
+static const struct of_device_id xilinx_cdma_of_match[] = {
+ { .compatible = "xlnx,axi-cdma-1.00.a", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, xilinx_cdma_of_match);
+
+static struct platform_driver xilinx_cdma_driver = {
+ .driver = {
+ .name = "xilinx-cdma",
+ .owner = THIS_MODULE,
+ .of_match_table = xilinx_cdma_of_match,
+ },
+ .probe = xilinx_cdma_probe,
+ .remove = xilinx_cdma_remove,
+};
+
+module_platform_driver(xilinx_cdma_driver);
+
+MODULE_AUTHOR("Xilinx, Inc.");
+MODULE_DESCRIPTION("Xilinx CDMA driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/dma/xilinx_dma.h b/include/linux/dma/xilinx_dma.h
index 34b98f2..fb74ff7 100644
--- a/include/linux/dma/xilinx_dma.h
+++ b/include/linux/dma/xilinx_dma.h
@@ -41,7 +41,20 @@ struct xilinx_vdma_config {
int ext_fsync;
};

+/**
+ * struct xilinx_cdma_config - CDMA Configuration structure
+ * @coalesc: Interrupt coalescing threshold
+ * @delay: Delay counter
+ * @reset: Reset Channel
+ */
+struct xilinx_cdma_config {
+ int coalesc;
+ int delay;
+ int reset;
+};
+
int xilinx_vdma_channel_set_config(struct dma_chan *dchan,
struct xilinx_vdma_config *cfg);
-
+int xilinx_cdma_channel_set_config(struct dma_chan *dchan,
+ struct xilinx_cdma_config *cfg);
#endif
--
2.1.2