/*
 * Copyright 2012 Marvell International Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>
#include <linux/dmaengine.h>
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/platform_data/mmp_dma.h>
#include <linux/dmapool.h>
#include <linux/of_device.h>
#include <linux/of_dma.h>
#include <linux/of.h>
#include <linux/dma/mmp-pdma.h>

#include "dmaengine.h"

#define DCSR            0x0000
#define DALGN           0x00a0
#define DINT            0x00f0
#define DDADR           0x0200
#define DSADR(n)        (0x0204 + ((n) << 4))
#define DTADR(n)        (0x0208 + ((n) << 4))
#define DCMD            0x020c

#define DCSR_RUN        BIT(31) /* Run Bit (read / write) */
#define DCSR_NODESC     BIT(30) /* No-Descriptor Fetch (read / write) */
#define DCSR_STOPIRQEN  BIT(29) /* Stop Interrupt Enable (read / write) */
#define DCSR_REQPEND    BIT(8)  /* Request Pending (read-only) */
#define DCSR_STOPSTATE  BIT(3)  /* Stop State (read-only) */
#define DCSR_ENDINTR    BIT(2)  /* End Interrupt (read / write) */
#define DCSR_STARTINTR  BIT(1)  /* Start Interrupt (read / write) */
#define DCSR_BUSERR     BIT(0)  /* Bus Error Interrupt (read / write) */

#define DCSR_EORIRQEN   BIT(28) /* End of Receive Interrupt Enable (R/W) */
#define DCSR_EORJMPEN   BIT(27) /* Jump to next descriptor on EOR */
#define DCSR_EORSTOPEN  BIT(26) /* STOP on an EOR */
#define DCSR_SETCMPST   BIT(25) /* Set Descriptor Compare Status */
#define DCSR_CLRCMPST   BIT(24) /* Clear Descriptor Compare Status */
#define DCSR_CMPST      BIT(10) /* The Descriptor Compare Status */
#define DCSR_EORINTR    BIT(9)  /* The end of Receive */

#define DRCMR(n)        ((((n) < 64) ? 0x0100 : 0x1100) + (((n) & 0x3f) << 2))
#define DRCMR_MAPVLD    BIT(7)  /* Map Valid (read / write) */
#define DRCMR_CHLNUM    0x1f    /* mask for Channel Number (read / write) */

#define DDADR_DESCADDR  0xfffffff0      /* Address of next descriptor (mask) */
#define DDADR_STOP      BIT(0)  /* Stop (read / write) */

#define DCMD_INCSRCADDR BIT(31) /* Source Address Increment Setting. */
#define DCMD_INCTRGADDR BIT(30) /* Target Address Increment Setting. */
#define DCMD_FLOWSRC    BIT(29) /* Flow Control by the source. */
#define DCMD_FLOWTRG    BIT(28) /* Flow Control by the target. */
#define DCMD_STARTIRQEN BIT(22) /* Start Interrupt Enable */
#define DCMD_ENDIRQEN   BIT(21) /* End Interrupt Enable */
#define DCMD_ENDIAN     BIT(18) /* Device Endian-ness. */
#define DCMD_BURST8     (1 << 16)       /* 8 byte burst */
#define DCMD_BURST16    (2 << 16)       /* 16 byte burst */
#define DCMD_BURST32    (3 << 16)       /* 32 byte burst */
#define DCMD_WIDTH1     (1 << 14)       /* 1 byte width */
#define DCMD_WIDTH2     (2 << 14)       /* 2 byte width (HalfWord) */
#define DCMD_WIDTH4     (3 << 14)       /* 4 byte width (Word) */
#define DCMD_LENGTH     0x01fff         /* length mask (max = 8K - 1) */

#define PDMA_MAX_DESC_BYTES     DCMD_LENGTH

struct mmp_pdma_desc_hw {
        u32 ddadr;      /* Points to the next descriptor + flags */
        u32 dsadr;      /* DSADR value for the current transfer */
        u32 dtadr;      /* DTADR value for the current transfer */
        u32 dcmd;       /* DCMD value for the current transfer */
} __aligned(32);

struct mmp_pdma_desc_sw {
        struct mmp_pdma_desc_hw desc;
        struct list_head node;
        struct list_head tx_list;
        struct dma_async_tx_descriptor async_tx;
};

struct mmp_pdma_phy;

struct mmp_pdma_chan {
        struct device *dev;
        struct dma_chan chan;
        struct dma_async_tx_descriptor desc;
        struct mmp_pdma_phy *phy;
        enum dma_transfer_direction dir;

        struct mmp_pdma_desc_sw *cyclic_first;  /* first desc_sw if channel
                                                 * is in cyclic mode */

        /* channel's basic info */
        struct tasklet_struct tasklet;
        u32 dcmd;
        u32 drcmr;
        u32 dev_addr;

        /* list for desc */
        spinlock_t desc_lock;           /* Descriptor list lock */
        struct list_head chain_pending; /* Link descriptors queue for pending */
        struct list_head chain_running; /* Link descriptors queue for running */
        bool idle;                      /* channel statue machine */
        bool byte_align;

        struct dma_pool *desc_pool;     /* Descriptors pool */
};

struct mmp_pdma_phy {
        int idx;
        void __iomem *base;
        struct mmp_pdma_chan *vchan;
};

struct mmp_pdma_device {
        int                             dma_channels;
        void __iomem                    *base;
        struct device                   *dev;
        struct dma_device               device;
        struct mmp_pdma_phy             *phy;
        spinlock_t phy_lock; /* protect alloc/free phy channels */
};

#define tx_to_mmp_pdma_desc(tx)                                 \
        container_of(tx, struct mmp_pdma_desc_sw, async_tx)
#define to_mmp_pdma_desc(lh)                                    \
        container_of(lh, struct mmp_pdma_desc_sw, node)
#define to_mmp_pdma_chan(dchan)                                 \
        container_of(dchan, struct mmp_pdma_chan, chan)
#define to_mmp_pdma_dev(dmadev)                                 \
        container_of(dmadev, struct mmp_pdma_device, device)

static void set_desc(struct mmp_pdma_phy *phy, dma_addr_t addr)
{
        u32 reg = (phy->idx << 4) + DDADR;

        writel(addr, phy->base + reg);
}

static void enable_chan(struct mmp_pdma_phy *phy)
{
        u32 reg, dalgn;

        if (!phy->vchan)
                return;

        reg = DRCMR(phy->vchan->drcmr);
        writel(DRCMR_MAPVLD | phy->idx, phy->base + reg);

        dalgn = readl(phy->base + DALGN);
        if (phy->vchan->byte_align)
                dalgn |= 1 << phy->idx;
        else
                dalgn &= ~(1 << phy->idx);
        writel(dalgn, phy->base + DALGN);

        reg = (phy->idx << 2) + DCSR;
        writel(readl(phy->base + reg) | DCSR_RUN, phy->base + reg);
}

static void disable_chan(struct mmp_pdma_phy *phy)
{
        u32 reg;

        if (!phy)
                return;

        reg = (phy->idx << 2) + DCSR;
        writel(readl(phy->base + reg) & ~DCSR_RUN, phy->base + reg);
}

static int clear_chan_irq(struct mmp_pdma_phy *phy)
{
        u32 dcsr;
        u32 dint = readl(phy->base + DINT);
        u32 reg = (phy->idx << 2) + DCSR;

        if (!(dint & BIT(phy->idx)))
                return -EAGAIN;

        /* clear irq */
        dcsr = readl(phy->base + reg);
        writel(dcsr, phy->base + reg);
        if ((dcsr & DCSR_BUSERR) && (phy->vchan))
                dev_warn(phy->vchan->dev, "DCSR_BUSERR\n");

        return 0;
}

static irqreturn_t mmp_pdma_chan_handler(int irq, void *dev_id)
{
        struct mmp_pdma_phy *phy = dev_id;

        if (clear_chan_irq(phy) != 0)
                return IRQ_NONE;

        tasklet_schedule(&phy->vchan->tasklet);
        return IRQ_HANDLED;
}

static irqreturn_t mmp_pdma_int_handler(int irq, void *dev_id)
{
        struct mmp_pdma_device *pdev = dev_id;
        struct mmp_pdma_phy *phy;
        u32 dint = readl(pdev->base + DINT);
        int i, ret;
        int irq_num = 0;

        while (dint) {
                i = __ffs(dint);
                /* only handle interrupts belonging to pdma driver*/
                if (i >= pdev->dma_channels)
                        break;
                dint &= (dint - 1);
                phy = &pdev->phy[i];
                ret = mmp_pdma_chan_handler(irq, phy);
                if (ret == IRQ_HANDLED)
                        irq_num++;
        }

        if (irq_num)
                return IRQ_HANDLED;

        return IRQ_NONE;
}

/* lookup free phy channel as descending priority */
static struct mmp_pdma_phy *lookup_phy(struct mmp_pdma_chan *pchan)
{
        int prio, i;
        struct mmp_pdma_device *pdev = to_mmp_pdma_dev(pchan->chan.device);
        struct mmp_pdma_phy *phy, *found = NULL;
        unsigned long flags;

        /*
         * dma channel priorities
         * ch 0 - 3,  16 - 19  <--> (0)
         * ch 4 - 7,  20 - 23  <--> (1)
         * ch 8 - 11, 24 - 27  <--> (2)
         * ch 12 - 15, 28 - 31  <--> (3)
         */

        spin_lock_irqsave(&pdev->phy_lock, flags);
        for (prio = 0; prio <= ((pdev->dma_channels - 1) & 0xf) >> 2; prio++) {
                for (i = 0; i < pdev->dma_channels; i++) {
                        if (prio != (i & 0xf) >> 2)
                                continue;
                        phy = &pdev->phy[i];
                        if (!phy->vchan) {
                                phy->vchan = pchan;
                                found = phy;
                                goto out_unlock;
                        }
                }
        }

out_unlock:
        spin_unlock_irqrestore(&pdev->phy_lock, flags);
        return found;
}

static void mmp_pdma_free_phy(struct mmp_pdma_chan *pchan)
{
        struct mmp_pdma_device *pdev = to_mmp_pdma_dev(pchan->chan.device);
        unsigned long flags;
        u32 reg;

        if (!pchan->phy)
                return;

        /* clear the channel mapping in DRCMR */
        reg = DRCMR(pchan->drcmr);
        writel(0, pchan->phy->base + reg);

        spin_lock_irqsave(&pdev->phy_lock, flags);
        pchan->phy->vchan = NULL;
        pchan->phy = NULL;
        spin_unlock_irqrestore(&pdev->phy_lock, flags);
}

/**
 * start_pending_queue - transfer any pending transactions
 * pending list ==> running list
 */
static void start_pending_queue(struct mmp_pdma_chan *chan)
{
        struct mmp_pdma_desc_sw *desc;

        /* still in running, irq will start the pending list */
        if (!chan->idle) {
                dev_dbg(chan->dev, "DMA controller still busy\n");
                return;
        }

        if (list_empty(&chan->chain_pending)) {
                /* chance to re-fetch phy channel with higher prio */
                mmp_pdma_free_phy(chan);
                dev_dbg(chan->dev, "no pending list\n");
                return;
        }

        if (!chan->phy) {
                chan->phy = lookup_phy(chan);
                if (!chan->phy) {
                        dev_dbg(chan->dev, "no free dma channel\n");
                        return;
                }
        }

        /*
         * pending -> running
         * reintilize pending list
         */
        desc = list_first_entry(&chan->chain_pending,
                                struct mmp_pdma_desc_sw, node);
        list_splice_tail_init(&chan->chain_pending, &chan->chain_running);

        /*
         * Program the descriptor's address into the DMA controller,
         * then start the DMA transaction
         */
        set_desc(chan->phy, desc->async_tx.phys);
        enable_chan(chan->phy);
        chan->idle = false;
}


/* desc->tx_list ==> pending list */
static dma_cookie_t mmp_pdma_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct mmp_pdma_chan *chan = to_mmp_pdma_chan(tx->chan);
        struct mmp_pdma_desc_sw *desc = tx_to_mmp_pdma_desc(tx);
        struct mmp_pdma_desc_sw *child;
        unsigned long flags;
        dma_cookie_t cookie = -EBUSY;

        spin_lock_irqsave(&chan->desc_lock, flags);

        list_for_each_entry(child, &desc->tx_list, node) {
                cookie = dma_cookie_assign(&child->async_tx);
        }

        /* softly link to pending list - desc->tx_list ==> pending list */
        list_splice_tail_init(&desc->tx_list, &chan->chain_pending);

        spin_unlock_irqrestore(&chan->desc_lock, flags);

        return cookie;
}

static struct mmp_pdma_desc_sw *
mmp_pdma_alloc_descriptor(struct mmp_pdma_chan *chan)
{
        struct mmp_pdma_desc_sw *desc;
        dma_addr_t pdesc;

        desc = dma_pool_zalloc(chan->desc_pool, GFP_ATOMIC, &pdesc);
        if (!desc) {
                dev_err(chan->dev, "out of memory for link descriptor\n");
                return NULL;
        }

        INIT_LIST_HEAD(&desc->tx_list);
        dma_async_tx_descriptor_init(&desc->async_tx, &chan->chan);
        /* each desc has submit */
        desc->async_tx.tx_submit = mmp_pdma_tx_submit;
        desc->async_tx.phys = pdesc;

        return desc;
}

/**
 * mmp_pdma_alloc_chan_resources - Allocate resources for DMA channel.
 *
 * This function will create a dma pool for descriptor allocation.
 * Request irq only when channel is requested
 * Return - The number of allocated descriptors.
 */

static int mmp_pdma_alloc_chan_resources(struct dma_chan *dchan)
{
        struct mmp_pdma_chan *chan = to_mmp_pdma_chan(dchan);

        if (chan->desc_pool)
                return 1;

        chan->desc_pool = dma_pool_create(dev_name(&dchan->dev->device),
                                          chan->dev,
                                          sizeof(struct mmp_pdma_desc_sw),
                                          __alignof__(struct mmp_pdma_desc_sw),
                                          0);
        if (!chan->desc_pool) {
                dev_err(chan->dev, "unable to allocate descriptor pool\n");
                return -ENOMEM;
        }

        mmp_pdma_free_phy(chan);
        chan->idle = true;
        chan->dev_addr = 0;
        return 1;
}

static void mmp_pdma_free_desc_list(struct mmp_pdma_chan *chan,
                                    struct list_head *list)
{
        struct mmp_pdma_desc_sw *desc, *_desc;

        list_for_each_entry_safe(desc, _desc, list, node) {
                list_del(&desc->node);
                dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys);
        }
}

static void mmp_pdma_free_chan_resources(struct dma_chan *dchan)
{
        struct mmp_pdma_chan *chan = to_mmp_pdma_chan(dchan);
        unsigned long flags;

        spin_lock_irqsave(&chan->desc_lock, flags);
        mmp_pdma_free_desc_list(chan, &chan->chain_pending);
        mmp_pdma_free_desc_list(chan, &chan->chain_running);
        spin_unlock_irqrestore(&chan->desc_lock, flags);

        dma_pool_destroy(chan->desc_pool);
        chan->desc_pool = NULL;
        chan->idle = true;
        chan->dev_addr = 0;
        mmp_pdma_free_phy(chan);
        return;
}

static struct dma_async_tx_descriptor *
mmp_pdma_prep_memcpy(struct dma_chan *dchan,
                     dma_addr_t dma_dst, dma_addr_t dma_src,
                     size_t len, unsigned long flags)
{
        struct mmp_pdma_chan *chan;
        struct mmp_pdma_desc_sw *first = NULL, *prev = NULL, *new;
        size_t copy = 0;

        if (!dchan)
                return NULL;

        if (!len)
                return NULL;

        chan = to_mmp_pdma_chan(dchan);
        chan->byte_align = false;

        if (!chan->dir) {
                chan->dir = DMA_MEM_TO_MEM;
                chan->dcmd = DCMD_INCTRGADDR | DCMD_INCSRCADDR;
                chan->dcmd |= DCMD_BURST32;
        }

        do {
                /* Allocate the link descriptor from DMA pool */
                new = mmp_pdma_alloc_descriptor(chan);
                if (!new) {
                        dev_err(chan->dev, "no memory for desc\n");
                        goto fail;
                }

                copy = min_t(size_t, len, PDMA_MAX_DESC_BYTES);
                if (dma_src & 0x7 || dma_dst & 0x7)
                        chan->byte_align = true;

                new->desc.dcmd = chan->dcmd | (DCMD_LENGTH & copy);
                new->desc.dsadr = dma_src;
                new->desc.dtadr = dma_dst;

                if (!first)
                        first = new;
                else
                        prev->desc.ddadr = new->async_tx.phys;

                new->async_tx.cookie = 0;
                async_tx_ack(&new->async_tx);

                prev = new;
                len -= copy;

                if (chan->dir == DMA_MEM_TO_DEV) {
                        dma_src += copy;
                } else if (chan->dir == DMA_DEV_TO_MEM) {
                        dma_dst += copy;
                } else if (chan->dir == DMA_MEM_TO_MEM) {
                        dma_src += copy;
                        dma_dst += copy;
                }

                /* Insert the link descriptor to the LD ring */
                list_add_tail(&new->node, &first->tx_list);
        } while (len);

        first->async_tx.flags = flags; /* client is in control of this ack */
        first->async_tx.cookie = -EBUSY;

        /* last desc and fire IRQ */
        new->desc.ddadr = DDADR_STOP;
        new->desc.dcmd |= DCMD_ENDIRQEN;

        chan->cyclic_first = NULL;

        return &first->async_tx;

fail:
        if (first)
                mmp_pdma_free_desc_list(chan, &first->tx_list);
        return NULL;
}

static struct dma_async_tx_descriptor *
mmp_pdma_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl,
                       unsigned int sg_len, enum dma_transfer_direction dir,
                       unsigned long flags, void *context)
{
        struct mmp_pdma_chan *chan = to_mmp_pdma_chan(dchan);
        struct mmp_pdma_desc_sw *first = NULL, *prev = NULL, *new = NULL;
        size_t len, avail;
        struct scatterlist *sg;
        dma_addr_t addr;
        int i;

        if ((sgl == NULL) || (sg_len == 0))
                return NULL;

        chan->byte_align = false;

        for_each_sg(sgl, sg, sg_len, i) {
                addr = sg_dma_address(sg);
                avail = sg_dma_len(sgl);

                do {
                        len = min_t(size_t, avail, PDMA_MAX_DESC_BYTES);
                        if (addr & 0x7)
                                chan->byte_align = true;

                        /* allocate and populate the descriptor */
                        new = mmp_pdma_alloc_descriptor(chan);
                        if (!new) {
                                dev_err(chan->dev, "no memory for desc\n");
                                goto fail;
                        }

                        new->desc.dcmd = chan->dcmd | (DCMD_LENGTH & len);
                        if (dir == DMA_MEM_TO_DEV) {
                                new->desc.dsadr = addr;
                                new->desc.dtadr = chan->dev_addr;
                        } else {
                                new->desc.dsadr = chan->dev_addr;
                                new->desc.dtadr = addr;
                        }

                        if (!first)
                                first = new;
                        else
                                prev->desc.ddadr = new->async_tx.phys;

                        new->async_tx.cookie = 0;
                        async_tx_ack(&new->async_tx);
                        prev = new;

                        /* Insert the link descriptor to the LD ring */
                        list_add_tail(&new->node, &first->tx_list);

                        /* update metadata */
                        addr += len;
                        avail -= len;
                } while (avail);
        }

        first->async_tx.cookie = -EBUSY;
        first->async_tx.flags = flags;

        /* last desc and fire IRQ */
        new->desc.ddadr = DDADR_STOP;
        new->desc.dcmd |= DCMD_ENDIRQEN;

        chan->dir = dir;
        chan->cyclic_first = NULL;

        return &first->async_tx;

fail:
        if (first)
                mmp_pdma_free_desc_list(chan, &first->tx_list);
        return NULL;
}

static struct dma_async_tx_descriptor *
mmp_pdma_prep_dma_cyclic(struct dma_chan *dchan,
                         dma_addr_t buf_addr, size_t len, size_t period_len,
                         enum dma_transfer_direction direction,
                         unsigned long flags)
{
        struct mmp_pdma_chan *chan;
        struct mmp_pdma_desc_sw *first = NULL, *prev = NULL, *new;
        dma_addr_t dma_src, dma_dst;

        if (!dchan || !len || !period_len)
                return NULL;

        /* the buffer length must be a multiple of period_len */
        if (len % period_len != 0)
                return NULL;

        if (period_len > PDMA_MAX_DESC_BYTES)
                return NULL;

        chan = to_mmp_pdma_chan(dchan);

        switch (direction) {
        case DMA_MEM_TO_DEV:
                dma_src = buf_addr;
                dma_dst = chan->dev_addr;
                break;
        case DMA_DEV_TO_MEM:
                dma_dst = buf_addr;
                dma_src = chan->dev_addr;
                break;
        default:
                dev_err(chan->dev, "Unsupported direction for cyclic DMA\n");
                return NULL;
        }

        chan->dir = direction;

        do {
                /* Allocate the link descriptor from DMA pool */
                new = mmp_pdma_alloc_descriptor(chan);
                if (!new) {
                        dev_err(chan->dev, "no memory for desc\n");
                        goto fail;
                }

                new->desc.dcmd = (chan->dcmd | DCMD_ENDIRQEN |
                                  (DCMD_LENGTH & period_len));
                new->desc.dsadr = dma_src;
                new->desc.dtadr = dma_dst;

                if (!first)
                        first = new;
                else
                        prev->desc.ddadr = new->async_tx.phys;

                new->async_tx.cookie = 0;
                async_tx_ack(&new->async_tx);

                prev = new;
                len -= period_len;

                if (chan->dir == DMA_MEM_TO_DEV)
                        dma_src += period_len;
                else
                        dma_dst += period_len;

                /* Insert the link descriptor to the LD ring */
                list_add_tail(&new->node, &first->tx_list);
        } while (len);

        first->async_tx.flags = flags; /* client is in control of this ack */
        first->async_tx.cookie = -EBUSY;

        /* make the cyclic link */
        new->desc.ddadr = first->async_tx.phys;
        chan->cyclic_first = first;

        return &first->async_tx;

fail:
        if (first)
                mmp_pdma_free_desc_list(chan, &first->tx_list);
        return NULL;
}

static int mmp_pdma_config(struct dma_chan *dchan,
                           struct dma_slave_config *cfg)
{
        struct mmp_pdma_chan *chan = to_mmp_pdma_chan(dchan);
        u32 maxburst = 0, addr = 0;
        enum dma_slave_buswidth width = DMA_SLAVE_BUSWIDTH_UNDEFINED;

        if (!dchan)
                return -EINVAL;

        if (cfg->direction == DMA_DEV_TO_MEM) {
                chan->dcmd = DCMD_INCTRGADDR | DCMD_FLOWSRC;
                maxburst = cfg->src_maxburst;
                width = cfg->src_addr_width;
                addr = cfg->src_addr;
        } else if (cfg->direction == DMA_MEM_TO_DEV) {
                chan->dcmd = DCMD_INCSRCADDR | DCMD_FLOWTRG;
                maxburst = cfg->dst_maxburst;
                width = cfg->dst_addr_width;
                addr = cfg->dst_addr;
        }

        if (width == DMA_SLAVE_BUSWIDTH_1_BYTE)
                chan->dcmd |= DCMD_WIDTH1;
        else if (width == DMA_SLAVE_BUSWIDTH_2_BYTES)
                chan->dcmd |= DCMD_WIDTH2;
        else if (width == DMA_SLAVE_BUSWIDTH_4_BYTES)
                chan->dcmd |= DCMD_WIDTH4;

        if (maxburst == 8)
                chan->dcmd |= DCMD_BURST8;
        else if (maxburst == 16)
                chan->dcmd |= DCMD_BURST16;
        else if (maxburst == 32)
                chan->dcmd |= DCMD_BURST32;

        chan->dir = cfg->direction;
        chan->dev_addr = addr;
        /* FIXME: drivers should be ported over to use the filter
         * function. Once that's done, the following two lines can
         * be removed.
         */
        if (cfg->slave_id)
                chan->drcmr = cfg->slave_id;

        return 0;
}

static int mmp_pdma_terminate_all(struct dma_chan *dchan)
{
        struct mmp_pdma_chan *chan = to_mmp_pdma_chan(dchan);
        unsigned long flags;

        if (!dchan)
                return -EINVAL;

        disable_chan(chan->phy);
        mmp_pdma_free_phy(chan);
        spin_lock_irqsave(&chan->desc_lock, flags);
        mmp_pdma_free_desc_list(chan, &chan->chain_pending);
        mmp_pdma_free_desc_list(chan, &chan->chain_running);
        spin_unlock_irqrestore(&chan->desc_lock, flags);
        chan->idle = true;

        return 0;
}

static unsigned int mmp_pdma_residue(struct mmp_pdma_chan *chan,
                                     dma_cookie_t cookie)
{
        struct mmp_pdma_desc_sw *sw;
        u32 curr, residue = 0;
        bool passed = false;
        bool cyclic = chan->cyclic_first != NULL;

        /*
         * If the channel does not have a phy pointer anymore, it has already
         * been completed. Therefore, its residue is 0.
         */
        if (!chan->phy)
                return 0;

        if (chan->dir == DMA_DEV_TO_MEM)
                curr = readl(chan->phy->base + DTADR(chan->phy->idx));
        else
                curr = readl(chan->phy->base + DSADR(chan->phy->idx));

        list_for_each_entry(sw, &chan->chain_running, node) {
                u32 start, end, len;

                if (chan->dir == DMA_DEV_TO_MEM)
                        start = sw->desc.dtadr;
                else
                        start = sw->desc.dsadr;

                len = sw->desc.dcmd & DCMD_LENGTH;
                end = start + len;

                /*
                 * 'passed' will be latched once we found the descriptor which
                 * lies inside the boundaries of the curr pointer. All
                 * descriptors that occur in the list _after_ we found that
                 * partially handled descriptor are still to be processed and
                 * are hence added to the residual bytes counter.
                 */

                if (passed) {
                        residue += len;
                } else if (curr >= start && curr <= end) {
                        residue += end - curr;
                        passed = true;
                }

                /*
                 * Descriptors that have the ENDIRQEN bit set mark the end of a
                 * transaction chain, and the cookie assigned with it has been
                 * returned previously from mmp_pdma_tx_submit().
                 *
                 * In case we have multiple transactions in the running chain,
                 * and the cookie does not match the one the user asked us
                 * about, reset the state variables and start over.
                 *
                 * This logic does not apply to cyclic transactions, where all
                 * descriptors have the ENDIRQEN bit set, and for which we
                 * can't have multiple transactions on one channel anyway.
                 */
                if (cyclic || !(sw->desc.dcmd & DCMD_ENDIRQEN))
                        continue;

                if (sw->async_tx.cookie == cookie) {
                        return residue;
                } else {
                        residue = 0;
                        passed = false;
                }
        }

        /* We should only get here in case of cyclic transactions */
        return residue;
}

static enum dma_status mmp_pdma_tx_status(struct dma_chan *dchan,
                                          dma_cookie_t cookie,
                                          struct dma_tx_state *txstate)
{
        struct mmp_pdma_chan *chan = to_mmp_pdma_chan(dchan);
        enum dma_status ret;

        ret = dma_cookie_status(dchan, cookie, txstate);
        if (likely(ret != DMA_ERROR))
                dma_set_residue(txstate, mmp_pdma_residue(chan, cookie));

        return ret;
}

/**
 * mmp_pdma_issue_pending - Issue the DMA start command
 * pending list ==> running list
 */
static void mmp_pdma_issue_pending(struct dma_chan *dchan)
{
        struct mmp_pdma_chan *chan = to_mmp_pdma_chan(dchan);
        unsigned long flags;

        spin_lock_irqsave(&chan->desc_lock, flags);
        start_pending_queue(chan);
        spin_unlock_irqrestore(&chan->desc_lock, flags);
}

/*
 * dma_do_tasklet
 * Do call back
 * Start pending list
 */
static void dma_do_tasklet(unsigned long data)
{
        struct mmp_pdma_chan *chan = (struct mmp_pdma_chan *)data;
        struct mmp_pdma_desc_sw *desc, *_desc;
        LIST_HEAD(chain_cleanup);
        unsigned long flags;
        struct dmaengine_desc_callback cb;

        if (chan->cyclic_first) {
                spin_lock_irqsave(&chan->desc_lock, flags);
                desc = chan->cyclic_first;
                dmaengine_desc_get_callback(&desc->async_tx, &cb);
                spin_unlock_irqrestore(&chan->desc_lock, flags);

                dmaengine_desc_callback_invoke(&cb, NULL);

                return;
        }

        /* submit pending list; callback for each desc; free desc */
        spin_lock_irqsave(&chan->desc_lock, flags);

        list_for_each_entry_safe(desc, _desc, &chan->chain_running, node) {
                /*
                 * move the descriptors to a temporary list so we can drop
                 * the lock during the entire cleanup operation
                 */
                list_move(&desc->node, &chain_cleanup);

                /*
                 * Look for the first list entry which has the ENDIRQEN flag
                 * set. That is the descriptor we got an interrupt for, so
                 * complete that transaction and its cookie.
                 */
                if (desc->desc.dcmd & DCMD_ENDIRQEN) {
                        dma_cookie_t cookie = desc->async_tx.cookie;
                        dma_cookie_complete(&desc->async_tx);
                        dev_dbg(chan->dev, "completed_cookie=%d\n", cookie);
                        break;
                }
        }

        /*
         * The hardware is idle and ready for more when the
         * chain_running list is empty.
         */
        chan->idle = list_empty(&chan->chain_running);

        /* Start any pending transactions automatically */
        start_pending_queue(chan);
        spin_unlock_irqrestore(&chan->desc_lock, flags);

        /* Run the callback for each descriptor, in order */
        list_for_each_entry_safe(desc, _desc, &chain_cleanup, node) {
                struct dma_async_tx_descriptor *txd = &desc->async_tx;

                /* Remove from the list of transactions */
                list_del(&desc->node);
                /* Run the link descriptor callback function */
                dmaengine_desc_get_callback(txd, &cb);
                dmaengine_desc_callback_invoke(&cb, NULL);

                dma_pool_free(chan->desc_pool, desc, txd->phys);
        }
}

static int mmp_pdma_remove(struct platform_device *op)
{
        struct mmp_pdma_device *pdev = platform_get_drvdata(op);
        struct mmp_pdma_phy *phy;
        int i, irq = 0, irq_num = 0;


        for (i = 0; i < pdev->dma_channels; i++) {
                if (platform_get_irq(op, i) > 0)
                        irq_num++;
        }

        if (irq_num != pdev->dma_channels) {
                irq = platform_get_irq(op, 0);
                devm_free_irq(&op->dev, irq, pdev);
        } else {
                for (i = 0; i < pdev->dma_channels; i++) {
                        phy = &pdev->phy[i];
                        irq = platform_get_irq(op, i);
                        devm_free_irq(&op->dev, irq, phy);
                }
        }

        dma_async_device_unregister(&pdev->device);
        return 0;
}

static int mmp_pdma_chan_init(struct mmp_pdma_device *pdev, int idx, int irq)
{
        struct mmp_pdma_phy *phy  = &pdev->phy[idx];
        struct mmp_pdma_chan *chan;
        int ret;

        chan = devm_kzalloc(pdev->dev, sizeof(*chan), GFP_KERNEL);
        if (chan == NULL)
                return -ENOMEM;

        phy->idx = idx;
        phy->base = pdev->base;

        if (irq) {
                ret = devm_request_irq(pdev->dev, irq, mmp_pdma_chan_handler,
                                       IRQF_SHARED, "pdma", phy);
                if (ret) {
                        dev_err(pdev->dev, "channel request irq fail!\n");
                        return ret;
                }
        }

        spin_lock_init(&chan->desc_lock);
        chan->dev = pdev->dev;
        chan->chan.device = &pdev->device;
        tasklet_init(&chan->tasklet, dma_do_tasklet, (unsigned long)chan);
        INIT_LIST_HEAD(&chan->chain_pending);
        INIT_LIST_HEAD(&chan->chain_running);

        /* register virt channel to dma engine */
        list_add_tail(&chan->chan.device_node, &pdev->device.channels);

        return 0;
}

static const struct of_device_id mmp_pdma_dt_ids[] = {
        { .compatible = "marvell,pdma-1.0", },
        {}
};
MODULE_DEVICE_TABLE(of, mmp_pdma_dt_ids);

static struct dma_chan *mmp_pdma_dma_xlate(struct of_phandle_args *dma_spec,
                                           struct of_dma *ofdma)
{
        struct mmp_pdma_device *d = ofdma->of_dma_data;
        struct dma_chan *chan;

        chan = dma_get_any_slave_channel(&d->device);
        if (!chan)
                return NULL;

        to_mmp_pdma_chan(chan)->drcmr = dma_spec->args[0];

        return chan;
}

static int mmp_pdma_probe(struct platform_device *op)
{
        struct mmp_pdma_device *pdev;
        const struct of_device_id *of_id;
        struct mmp_dma_platdata *pdata = dev_get_platdata(&op->dev);
        struct resource *iores;
        int i, ret, irq = 0;
        int dma_channels = 0, irq_num = 0;
        const enum dma_slave_buswidth widths =
                DMA_SLAVE_BUSWIDTH_1_BYTE   | DMA_SLAVE_BUSWIDTH_2_BYTES |
                DMA_SLAVE_BUSWIDTH_4_BYTES;

        pdev = devm_kzalloc(&op->dev, sizeof(*pdev), GFP_KERNEL);
        if (!pdev)
                return -ENOMEM;

        pdev->dev = &op->dev;

        spin_lock_init(&pdev->phy_lock);

        iores = platform_get_resource(op, IORESOURCE_MEM, 0);
        pdev->base = devm_ioremap_resource(pdev->dev, iores);
        if (IS_ERR(pdev->base))
                return PTR_ERR(pdev->base);

        of_id = of_match_device(mmp_pdma_dt_ids, pdev->dev);
        if (of_id)
                of_property_read_u32(pdev->dev->of_node, "#dma-channels",
                                     &dma_channels);
        else if (pdata && pdata->dma_channels)
                dma_channels = pdata->dma_channels;
        else
                dma_channels = 32;      /* default 32 channel */
        pdev->dma_channels = dma_channels;

        for (i = 0; i < dma_channels; i++) {
                if (platform_get_irq(op, i) > 0)
                        irq_num++;
        }

        pdev->phy = devm_kcalloc(pdev->dev, dma_channels, sizeof(*pdev->phy),
                                 GFP_KERNEL);
        if (pdev->phy == NULL)
                return -ENOMEM;

        INIT_LIST_HEAD(&pdev->device.channels);

        if (irq_num != dma_channels) {
                /* all chan share one irq, demux inside */
                irq = platform_get_irq(op, 0);
                ret = devm_request_irq(pdev->dev, irq, mmp_pdma_int_handler,
                                       IRQF_SHARED, "pdma", pdev);
                if (ret)
                        return ret;
        }

        for (i = 0; i < dma_channels; i++) {
                irq = (irq_num != dma_channels) ? 0 : platform_get_irq(op, i);
                ret = mmp_pdma_chan_init(pdev, i, irq);
                if (ret)
                        return ret;
        }

        dma_cap_set(DMA_SLAVE, pdev->device.cap_mask);
        dma_cap_set(DMA_MEMCPY, pdev->device.cap_mask);
        dma_cap_set(DMA_CYCLIC, pdev->device.cap_mask);
        dma_cap_set(DMA_PRIVATE, pdev->device.cap_mask);
        pdev->device.dev = &op->dev;
        pdev->device.device_alloc_chan_resources = mmp_pdma_alloc_chan_resources;
        pdev->device.device_free_chan_resources = mmp_pdma_free_chan_resources;
        pdev->device.device_tx_status = mmp_pdma_tx_status;
        pdev->device.device_prep_dma_memcpy = mmp_pdma_prep_memcpy;
        pdev->device.device_prep_slave_sg = mmp_pdma_prep_slave_sg;
        pdev->device.device_prep_dma_cyclic = mmp_pdma_prep_dma_cyclic;
        pdev->device.device_issue_pending = mmp_pdma_issue_pending;
        pdev->device.device_config = mmp_pdma_config;
        pdev->device.device_terminate_all = mmp_pdma_terminate_all;
        pdev->device.copy_align = DMAENGINE_ALIGN_8_BYTES;
        pdev->device.src_addr_widths = widths;
        pdev->device.dst_addr_widths = widths;
        pdev->device.directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
        pdev->device.residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;

        if (pdev->dev->coherent_dma_mask)
                dma_set_mask(pdev->dev, pdev->dev->coherent_dma_mask);
        else
                dma_set_mask(pdev->dev, DMA_BIT_MASK(64));

        ret = dma_async_device_register(&pdev->device);
        if (ret) {
                dev_err(pdev->device.dev, "unable to register\n");
                return ret;
        }

        if (op->dev.of_node) {
                /* Device-tree DMA controller registration */
                ret = of_dma_controller_register(op->dev.of_node,
                                                 mmp_pdma_dma_xlate, pdev);
                if (ret < 0) {
                        dev_err(&op->dev, "of_dma_controller_register failed\n");
                        return ret;
                }
        }

        platform_set_drvdata(op, pdev);
        dev_info(pdev->device.dev, "initialized %d channels\n", dma_channels);
        return 0;
}

static const struct platform_device_id mmp_pdma_id_table[] = {
        { "mmp-pdma", },
        { },
};

static struct platform_driver mmp_pdma_driver = {
        .driver         = {
                .name   = "mmp-pdma",
                .of_match_table = mmp_pdma_dt_ids,
        },
        .id_table       = mmp_pdma_id_table,
        .probe          = mmp_pdma_probe,
        .remove         = mmp_pdma_remove,
};

bool mmp_pdma_filter_fn(struct dma_chan *chan, void *param)
{
        struct mmp_pdma_chan *c = to_mmp_pdma_chan(chan);

        if (chan->device->dev->driver != &mmp_pdma_driver.driver)
                return false;

        c->drcmr = *(unsigned int *)param;

        return true;
}
EXPORT_SYMBOL_GPL(mmp_pdma_filter_fn);

module_platform_driver(mmp_pdma_driver);

MODULE_DESCRIPTION("MARVELL MMP Peripheral DMA Driver");
MODULE_AUTHOR("Marvell International Ltd.");
MODULE_LICENSE("GPL v2");