mpls_iptunnel: fix sparse warn: remove incorrect rcu_dereference

[linux/fpc-iii.git] / 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/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_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;

        if (xt->frame_size != 1)
                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 + xt->sgl[0].size) <<
                        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 */
        if (!list_empty(&desc->segments)) {
                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 int xilinx_vdma_terminate_all(struct dma_chan *dchan)
{
        struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);

        /* Halt the DMA engine */
        xilinx_vdma_halt(chan);

        /* Remove and free all of the descriptors in the lists */
        xilinx_vdma_free_descriptors(chan);

        return 0;
}

/**
 * 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);

/* -----------------------------------------------------------------------------
 * 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_terminate_all = xilinx_vdma_terminate_all;
        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",
                .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");