/*
   * 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		0x0204
  #define DTADR		0x0208
  #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_ALIGNMENT		3

  #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
  ");
  
  	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);
  		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->phy->vchan->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
  ");
  		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
  ");
  		return;
  	}
  
  	if (!chan->phy) {
  		chan->phy = lookup_phy(chan);
  		if (!chan->phy) {
  			dev_dbg(chan->dev, "no free dma channel
  ");
  			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_alloc(chan->desc_pool, GFP_ATOMIC, &pdesc);
  	if (!desc) {
  		dev_err(chan->dev, "out of memory for link descriptor
  ");
  		return NULL;
  	}
  
  	memset(desc, 0, sizeof(*desc));
  	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
  ");
  		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
  ");
  			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
  ");
  				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, void *context)

  {
  	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
  ");
  		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
  ");
  			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_control(struct dma_chan *dchan, enum dma_ctrl_cmd cmd,

  			    unsigned long arg)

  {
  	struct mmp_pdma_chan *chan = to_mmp_pdma_chan(dchan);
  	struct dma_slave_config *cfg = (void *)arg;
  	unsigned long flags;

  	u32 maxburst = 0, addr = 0;
  	enum dma_slave_buswidth width = DMA_SLAVE_BUSWIDTH_UNDEFINED;
  
  	if (!dchan)
  		return -EINVAL;
  
  	switch (cmd) {
  	case DMA_TERMINATE_ALL:
  		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;
  		break;
  	case DMA_SLAVE_CONFIG:
  		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;

  		break;
  	default:
  		return -ENOSYS;
  	}

  	return 0;

  }
  
  static enum dma_status mmp_pdma_tx_status(struct dma_chan *dchan,

  					  dma_cookie_t cookie,
  					  struct dma_tx_state *txstate)

  {

  	return dma_cookie_status(dchan, cookie, txstate);

  }
  
  /**
   * 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;

  	if (chan->cyclic_first) {
  		dma_async_tx_callback cb = NULL;
  		void *cb_data = NULL;

  		spin_lock_irqsave(&chan->desc_lock, flags);
  		desc = chan->cyclic_first;
  		cb = desc->async_tx.callback;
  		cb_data = desc->async_tx.callback_param;
  		spin_unlock_irqrestore(&chan->desc_lock, flags);
  
  		if (cb)
  			cb(cb_data);
  
  		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
  ", 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 */
  		if (txd->callback)
  			txd->callback(txd->callback_param);
  
  		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);
  
  	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(struct mmp_pdma_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!
  ");
  			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 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;
  
  	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(struct mmp_pdma_chan),
  				 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_control = mmp_pdma_control;
  	pdev->device.copy_align = PDMA_ALIGNMENT;
  
  	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
  ");
  		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
  ");
  			return ret;
  		}
  	}

  	platform_set_drvdata(op, pdev);

  	dev_info(pdev->device.dev, "initialized %d channels
  ", 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",
  		.owner  = THIS_MODULE,
  		.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");