drivers/dma/mmp_pdma.c

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

#define DCSR_EORIRQEN	(1 << 28)       /* End of Receive Interrupt Enable (R/W) */
#define DCSR_EORJMPEN	(1 << 27)       /* Jump to next descriptor on EOR */
#define DCSR_EORSTOPEN	(1 << 26)       /* STOP on an EOR */
#define DCSR_SETCMPST	(1 << 25)       /* Set Descriptor Compare Status */
#define DCSR_CLRCMPST	(1 << 24)       /* Clear Descriptor Compare Status */
#define DCSR_CMPST	(1 << 10)       /* The Descriptor Compare Status */
#define DCSR_EORINTR	(1 << 9)        /* The end of Receive */

#define DRCMR(n)	((((n) < 64) ? 0x0100 : 0x1100) + \
				 (((n) & 0x3f) << 2))
#define DRCMR_MAPVLD	(1 << 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	(1 << 0)	/* Stop (read / write) */

#define DCMD_INCSRCADDR	(1 << 31)	/* Source Address Increment Setting. */
#define DCMD_INCTRGADDR	(1 << 30)	/* Target Address Increment Setting. */
#define DCMD_FLOWSRC	(1 << 29)	/* Flow Control by the source. */
#define DCMD_FLOWTRG	(1 << 28)	/* Flow Control by the target. */
#define DCMD_STARTIRQEN	(1 << 22)	/* Start Interrupt Enable */
#define DCMD_ENDIRQEN	(1 << 21)	/* End Interrupt Enable */
#define DCMD_ENDIAN	(1 << 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;

	/* 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 */

	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;

	if (!phy->vchan)
		return;

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

	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) {
		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)) {
		/* 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;
	}
	return -EAGAIN;
}

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

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;
	else
		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);
}

/* desc->tx_list ==> pending list */
static void append_pending_queue(struct mmp_pdma_chan *chan,
					struct mmp_pdma_desc_sw *desc)
{
	struct mmp_pdma_desc_sw *tail =
				to_mmp_pdma_desc(chan->chain_pending.prev);

	if (list_empty(&chan->chain_pending))
		goto out_splice;

	/* one irq per queue, even appended */
	tail->desc.ddadr = desc->async_tx.phys;
	tail->desc.dcmd &= ~DCMD_ENDIRQEN;

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

/**
 * 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);
	}

	append_pending_queue(chan, desc);

	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\n");
		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\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);

	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);

		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;

	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;

	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);

			/* 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;

	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;
	int ret = 0;
	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 ret;
}

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;

	/* submit pending list; callback for each desc; free desc */

	spin_lock_irqsave(&chan->desc_lock, flags);

	/* update the cookie if we have some descriptors to cleanup */
	if (!list_empty(&chan->chain_running)) {
		dma_cookie_t cookie;

		desc = to_mmp_pdma_desc(chan->chain_running.prev);
		cookie = desc->async_tx.cookie;
		dma_cookie_complete(&desc->async_tx);

		dev_dbg(chan->dev, "completed_cookie=%d\n", cookie);
	}

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

	/* the hardware is now idle and ready for more */
	chan->idle = true;

	/* 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_DISABLED, "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 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, *candidate;

retry:
	candidate = NULL;

	/* walk the list of channels registered with the current instance and
	 * find one that is currently unused */
	list_for_each_entry(chan, &d->device.channels, device_node)
		if (chan->client_count == 0) {
			candidate = chan;
			break;
		}

	if (!candidate)
		return NULL;

	/* dma_get_slave_channel will return NULL if we lost a race between
	 * the lookup and the reservation */
	chan = dma_get_slave_channel(candidate);

	if (chan) {
		struct mmp_pdma_chan *c = to_mmp_pdma_chan(chan);
		c->drcmr = dma_spec->args[0];
		return chan;
	}

	goto retry;
}

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);
	if (!iores)
		return -EINVAL;

	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_kzalloc(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_DISABLED, "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);
	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_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\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;
		}
	}

	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",
		.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 Periphera DMA Driver");
MODULE_AUTHOR("Marvell International Ltd.");
MODULE_LICENSE("GPL v2");