drivers/dma/fsl-edma.c

/*
 * drivers/dma/fsl-edma.c
 *
 * Copyright 2013-2014 Freescale Semiconductor, Inc.
 *
 * Driver for the Freescale eDMA engine with flexible channel multiplexing
 * capability for DMA request sources. The eDMA block can be found on some
 * Vybrid and Layerscape SoCs.
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_dma.h>

#include "virt-dma.h"

#define EDMA_CR			0x00
#define EDMA_ES			0x04
#define EDMA_ERQ		0x0C
#define EDMA_EEI		0x14
#define EDMA_SERQ		0x1B
#define EDMA_CERQ		0x1A
#define EDMA_SEEI		0x19
#define EDMA_CEEI		0x18
#define EDMA_CINT		0x1F
#define EDMA_CERR		0x1E
#define EDMA_SSRT		0x1D
#define EDMA_CDNE		0x1C
#define EDMA_INTR		0x24
#define EDMA_ERR		0x2C

#define EDMA_TCD_SADDR(x)	(0x1000 + 32 * (x))
#define EDMA_TCD_SOFF(x)	(0x1004 + 32 * (x))
#define EDMA_TCD_ATTR(x)	(0x1006 + 32 * (x))
#define EDMA_TCD_NBYTES(x)	(0x1008 + 32 * (x))
#define EDMA_TCD_SLAST(x)	(0x100C + 32 * (x))
#define EDMA_TCD_DADDR(x)	(0x1010 + 32 * (x))
#define EDMA_TCD_DOFF(x)	(0x1014 + 32 * (x))
#define EDMA_TCD_CITER_ELINK(x)	(0x1016 + 32 * (x))
#define EDMA_TCD_CITER(x)	(0x1016 + 32 * (x))
#define EDMA_TCD_DLAST_SGA(x)	(0x1018 + 32 * (x))
#define EDMA_TCD_CSR(x)		(0x101C + 32 * (x))
#define EDMA_TCD_BITER_ELINK(x)	(0x101E + 32 * (x))
#define EDMA_TCD_BITER(x)	(0x101E + 32 * (x))

#define EDMA_CR_EDBG		BIT(1)
#define EDMA_CR_ERCA		BIT(2)
#define EDMA_CR_ERGA		BIT(3)
#define EDMA_CR_HOE		BIT(4)
#define EDMA_CR_HALT		BIT(5)
#define EDMA_CR_CLM		BIT(6)
#define EDMA_CR_EMLM		BIT(7)
#define EDMA_CR_ECX		BIT(16)
#define EDMA_CR_CX		BIT(17)

#define EDMA_SEEI_SEEI(x)	((x) & 0x1F)
#define EDMA_CEEI_CEEI(x)	((x) & 0x1F)
#define EDMA_CINT_CINT(x)	((x) & 0x1F)
#define EDMA_CERR_CERR(x)	((x) & 0x1F)

#define EDMA_TCD_ATTR_DSIZE(x)		(((x) & 0x0007))
#define EDMA_TCD_ATTR_DMOD(x)		(((x) & 0x001F) << 3)
#define EDMA_TCD_ATTR_SSIZE(x)		(((x) & 0x0007) << 8)
#define EDMA_TCD_ATTR_SMOD(x)		(((x) & 0x001F) << 11)
#define EDMA_TCD_ATTR_SSIZE_8BIT	(0x0000)
#define EDMA_TCD_ATTR_SSIZE_16BIT	(0x0100)
#define EDMA_TCD_ATTR_SSIZE_32BIT	(0x0200)
#define EDMA_TCD_ATTR_SSIZE_64BIT	(0x0300)
#define EDMA_TCD_ATTR_SSIZE_32BYTE	(0x0500)
#define EDMA_TCD_ATTR_DSIZE_8BIT	(0x0000)
#define EDMA_TCD_ATTR_DSIZE_16BIT	(0x0001)
#define EDMA_TCD_ATTR_DSIZE_32BIT	(0x0002)
#define EDMA_TCD_ATTR_DSIZE_64BIT	(0x0003)
#define EDMA_TCD_ATTR_DSIZE_32BYTE	(0x0005)

#define EDMA_TCD_SOFF_SOFF(x)		(x)
#define EDMA_TCD_NBYTES_NBYTES(x)	(x)
#define EDMA_TCD_SLAST_SLAST(x)		(x)
#define EDMA_TCD_DADDR_DADDR(x)		(x)
#define EDMA_TCD_CITER_CITER(x)		((x) & 0x7FFF)
#define EDMA_TCD_DOFF_DOFF(x)		(x)
#define EDMA_TCD_DLAST_SGA_DLAST_SGA(x)	(x)
#define EDMA_TCD_BITER_BITER(x)		((x) & 0x7FFF)

#define EDMA_TCD_CSR_START		BIT(0)
#define EDMA_TCD_CSR_INT_MAJOR		BIT(1)
#define EDMA_TCD_CSR_INT_HALF		BIT(2)
#define EDMA_TCD_CSR_D_REQ		BIT(3)
#define EDMA_TCD_CSR_E_SG		BIT(4)
#define EDMA_TCD_CSR_E_LINK		BIT(5)
#define EDMA_TCD_CSR_ACTIVE		BIT(6)
#define EDMA_TCD_CSR_DONE		BIT(7)

#define EDMAMUX_CHCFG_DIS		0x0
#define EDMAMUX_CHCFG_ENBL		0x80
#define EDMAMUX_CHCFG_SOURCE(n)		((n) & 0x3F)

#define DMAMUX_NR	2

#define FSL_EDMA_BUSWIDTHS	BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) | \
				BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) | \
				BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) | \
				BIT(DMA_SLAVE_BUSWIDTH_8_BYTES)

struct fsl_edma_hw_tcd {
	__le32	saddr;
	__le16	soff;
	__le16	attr;
	__le32	nbytes;
	__le32	slast;
	__le32	daddr;
	__le16	doff;
	__le16	citer;
	__le32	dlast_sga;
	__le16	csr;
	__le16	biter;
};

struct fsl_edma_sw_tcd {
	dma_addr_t			ptcd;
	struct fsl_edma_hw_tcd		*vtcd;
};

struct fsl_edma_slave_config {
	enum dma_transfer_direction	dir;
	enum dma_slave_buswidth		addr_width;
	u32				dev_addr;
	u32				burst;
	u32				attr;
};

struct fsl_edma_chan {
	struct virt_dma_chan		vchan;
	enum dma_status			status;
	struct fsl_edma_engine		*edma;
	struct fsl_edma_desc		*edesc;
	struct fsl_edma_slave_config	fsc;
	struct dma_pool			*tcd_pool;
};

struct fsl_edma_desc {
	struct virt_dma_desc		vdesc;
	struct fsl_edma_chan		*echan;
	bool				iscyclic;
	unsigned int			n_tcds;
	struct fsl_edma_sw_tcd		tcd[];
};

struct fsl_edma_engine {
	struct dma_device	dma_dev;
	void __iomem		*membase;
	void __iomem		*muxbase[DMAMUX_NR];
	struct clk		*muxclk[DMAMUX_NR];
	struct mutex		fsl_edma_mutex;
	u32			n_chans;
	int			txirq;
	int			errirq;
	bool			big_endian;
	struct fsl_edma_chan	chans[];
};

/*
 * R/W functions for big- or little-endian registers:
 * The eDMA controller's endian is independent of the CPU core's endian.
 * For the big-endian IP module, the offset for 8-bit or 16-bit registers
 * should also be swapped opposite to that in little-endian IP.
 */

static u32 edma_readl(struct fsl_edma_engine *edma, void __iomem *addr)
{
	if (edma->big_endian)
		return ioread32be(addr);
	else
		return ioread32(addr);
}

static void edma_writeb(struct fsl_edma_engine *edma, u8 val, void __iomem *addr)
{
	/* swap the reg offset for these in big-endian mode */
	if (edma->big_endian)
		iowrite8(val, (void __iomem *)((unsigned long)addr ^ 0x3));
	else
		iowrite8(val, addr);
}

static void edma_writew(struct fsl_edma_engine *edma, u16 val, void __iomem *addr)
{
	/* swap the reg offset for these in big-endian mode */
	if (edma->big_endian)
		iowrite16be(val, (void __iomem *)((unsigned long)addr ^ 0x2));
	else
		iowrite16(val, addr);
}

static void edma_writel(struct fsl_edma_engine *edma, u32 val, void __iomem *addr)
{
	if (edma->big_endian)
		iowrite32be(val, addr);
	else
		iowrite32(val, addr);
}

static struct fsl_edma_chan *to_fsl_edma_chan(struct dma_chan *chan)
{
	return container_of(chan, struct fsl_edma_chan, vchan.chan);
}

static struct fsl_edma_desc *to_fsl_edma_desc(struct virt_dma_desc *vd)
{
	return container_of(vd, struct fsl_edma_desc, vdesc);
}

static void fsl_edma_enable_request(struct fsl_edma_chan *fsl_chan)
{
	void __iomem *addr = fsl_chan->edma->membase;
	u32 ch = fsl_chan->vchan.chan.chan_id;

	edma_writeb(fsl_chan->edma, EDMA_SEEI_SEEI(ch), addr + EDMA_SEEI);
	edma_writeb(fsl_chan->edma, ch, addr + EDMA_SERQ);
}

static void fsl_edma_disable_request(struct fsl_edma_chan *fsl_chan)
{
	void __iomem *addr = fsl_chan->edma->membase;
	u32 ch = fsl_chan->vchan.chan.chan_id;

	edma_writeb(fsl_chan->edma, ch, addr + EDMA_CERQ);
	edma_writeb(fsl_chan->edma, EDMA_CEEI_CEEI(ch), addr + EDMA_CEEI);
}

static void fsl_edma_chan_mux(struct fsl_edma_chan *fsl_chan,
			unsigned int slot, bool enable)
{
	u32 ch = fsl_chan->vchan.chan.chan_id;
	void __iomem *muxaddr;
	unsigned chans_per_mux, ch_off;

	chans_per_mux = fsl_chan->edma->n_chans / DMAMUX_NR;
	ch_off = fsl_chan->vchan.chan.chan_id % chans_per_mux;
	muxaddr = fsl_chan->edma->muxbase[ch / chans_per_mux];
	slot = EDMAMUX_CHCFG_SOURCE(slot);

	if (enable)
		iowrite8(EDMAMUX_CHCFG_ENBL | slot, muxaddr + ch_off);
	else
		iowrite8(EDMAMUX_CHCFG_DIS, muxaddr + ch_off);
}

static unsigned int fsl_edma_get_tcd_attr(enum dma_slave_buswidth addr_width)
{
	switch (addr_width) {
	case 1:
		return EDMA_TCD_ATTR_SSIZE_8BIT | EDMA_TCD_ATTR_DSIZE_8BIT;
	case 2:
		return EDMA_TCD_ATTR_SSIZE_16BIT | EDMA_TCD_ATTR_DSIZE_16BIT;
	case 4:
		return EDMA_TCD_ATTR_SSIZE_32BIT | EDMA_TCD_ATTR_DSIZE_32BIT;
	case 8:
		return EDMA_TCD_ATTR_SSIZE_64BIT | EDMA_TCD_ATTR_DSIZE_64BIT;
	default:
		return EDMA_TCD_ATTR_SSIZE_32BIT | EDMA_TCD_ATTR_DSIZE_32BIT;
	}
}

static void fsl_edma_free_desc(struct virt_dma_desc *vdesc)
{
	struct fsl_edma_desc *fsl_desc;
	int i;

	fsl_desc = to_fsl_edma_desc(vdesc);
	for (i = 0; i < fsl_desc->n_tcds; i++)
		dma_pool_free(fsl_desc->echan->tcd_pool, fsl_desc->tcd[i].vtcd,
			      fsl_desc->tcd[i].ptcd);
	kfree(fsl_desc);
}

static int fsl_edma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
		unsigned long arg)
{
	struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
	struct dma_slave_config *cfg = (void *)arg;
	unsigned long flags;
	LIST_HEAD(head);

	switch (cmd) {
	case DMA_TERMINATE_ALL:
		spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
		fsl_edma_disable_request(fsl_chan);
		fsl_chan->edesc = NULL;
		vchan_get_all_descriptors(&fsl_chan->vchan, &head);
		spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);
		vchan_dma_desc_free_list(&fsl_chan->vchan, &head);
		return 0;

	case DMA_SLAVE_CONFIG:
		fsl_chan->fsc.dir = cfg->direction;
		if (cfg->direction == DMA_DEV_TO_MEM) {
			fsl_chan->fsc.dev_addr = cfg->src_addr;
			fsl_chan->fsc.addr_width = cfg->src_addr_width;
			fsl_chan->fsc.burst = cfg->src_maxburst;
			fsl_chan->fsc.attr = fsl_edma_get_tcd_attr(cfg->src_addr_width);
		} else if (cfg->direction == DMA_MEM_TO_DEV) {
			fsl_chan->fsc.dev_addr = cfg->dst_addr;
			fsl_chan->fsc.addr_width = cfg->dst_addr_width;
			fsl_chan->fsc.burst = cfg->dst_maxburst;
			fsl_chan->fsc.attr = fsl_edma_get_tcd_attr(cfg->dst_addr_width);
		} else {
			return -EINVAL;
		}
		return 0;

	case DMA_PAUSE:
		spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
		if (fsl_chan->edesc) {
			fsl_edma_disable_request(fsl_chan);
			fsl_chan->status = DMA_PAUSED;
		}
		spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);
		return 0;

	case DMA_RESUME:
		spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
		if (fsl_chan->edesc) {
			fsl_edma_enable_request(fsl_chan);
			fsl_chan->status = DMA_IN_PROGRESS;
		}
		spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);
		return 0;

	default:
		return -ENXIO;
	}
}

static size_t fsl_edma_desc_residue(struct fsl_edma_chan *fsl_chan,
		struct virt_dma_desc *vdesc, bool in_progress)
{
	struct fsl_edma_desc *edesc = fsl_chan->edesc;
	void __iomem *addr = fsl_chan->edma->membase;
	u32 ch = fsl_chan->vchan.chan.chan_id;
	enum dma_transfer_direction dir = fsl_chan->fsc.dir;
	dma_addr_t cur_addr, dma_addr;
	size_t len, size;
	int i;

	/* calculate the total size in this desc */
	for (len = i = 0; i < fsl_chan->edesc->n_tcds; i++)
		len += le32_to_cpu(edesc->tcd[i].vtcd->nbytes)
			* le16_to_cpu(edesc->tcd[i].vtcd->biter);

	if (!in_progress)
		return len;

	if (dir == DMA_MEM_TO_DEV)
		cur_addr = edma_readl(fsl_chan->edma, addr + EDMA_TCD_SADDR(ch));
	else
		cur_addr = edma_readl(fsl_chan->edma, addr + EDMA_TCD_DADDR(ch));

	/* figure out the finished and calculate the residue */
	for (i = 0; i < fsl_chan->edesc->n_tcds; i++) {
		size = le32_to_cpu(edesc->tcd[i].vtcd->nbytes)
			* le16_to_cpu(edesc->tcd[i].vtcd->biter);
		if (dir == DMA_MEM_TO_DEV)
			dma_addr = le32_to_cpu(edesc->tcd[i].vtcd->saddr);
		else
			dma_addr = le32_to_cpu(edesc->tcd[i].vtcd->daddr);

		len -= size;
		if (cur_addr >= dma_addr && cur_addr < dma_addr + size) {
			len += dma_addr + size - cur_addr;
			break;
		}
	}

	return len;
}

static enum dma_status fsl_edma_tx_status(struct dma_chan *chan,
		dma_cookie_t cookie, struct dma_tx_state *txstate)
{
	struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
	struct virt_dma_desc *vdesc;
	enum dma_status status;
	unsigned long flags;

	status = dma_cookie_status(chan, cookie, txstate);
	if (status == DMA_COMPLETE)
		return status;

	if (!txstate)
		return fsl_chan->status;

	spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
	vdesc = vchan_find_desc(&fsl_chan->vchan, cookie);
	if (fsl_chan->edesc && cookie == fsl_chan->edesc->vdesc.tx.cookie)
		txstate->residue = fsl_edma_desc_residue(fsl_chan, vdesc, true);
	else if (vdesc)
		txstate->residue = fsl_edma_desc_residue(fsl_chan, vdesc, false);
	else
		txstate->residue = 0;

	spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);

	return fsl_chan->status;
}

static void fsl_edma_set_tcd_regs(struct fsl_edma_chan *fsl_chan,
				  struct fsl_edma_hw_tcd *tcd)
{
	struct fsl_edma_engine *edma = fsl_chan->edma;
	void __iomem *addr = fsl_chan->edma->membase;
	u32 ch = fsl_chan->vchan.chan.chan_id;

	/*
	 * TCD parameters are stored in struct fsl_edma_hw_tcd in little
	 * endian format. However, we need to load the TCD registers in
	 * big- or little-endian obeying the eDMA engine model endian.
	 */
	edma_writew(edma, 0, addr + EDMA_TCD_CSR(ch));
	edma_writel(edma, le32_to_cpu(tcd->saddr), addr + EDMA_TCD_SADDR(ch));
	edma_writel(edma, le32_to_cpu(tcd->daddr), addr + EDMA_TCD_DADDR(ch));

	edma_writew(edma, le16_to_cpu(tcd->attr), addr + EDMA_TCD_ATTR(ch));
	edma_writew(edma, le16_to_cpu(tcd->soff), addr + EDMA_TCD_SOFF(ch));

	edma_writel(edma, le32_to_cpu(tcd->nbytes), addr + EDMA_TCD_NBYTES(ch));
	edma_writel(edma, le32_to_cpu(tcd->slast), addr + EDMA_TCD_SLAST(ch));

	edma_writew(edma, le16_to_cpu(tcd->citer), addr + EDMA_TCD_CITER(ch));
	edma_writew(edma, le16_to_cpu(tcd->biter), addr + EDMA_TCD_BITER(ch));
	edma_writew(edma, le16_to_cpu(tcd->doff), addr + EDMA_TCD_DOFF(ch));

	edma_writel(edma, le32_to_cpu(tcd->dlast_sga), addr + EDMA_TCD_DLAST_SGA(ch));

	edma_writew(edma, le16_to_cpu(tcd->csr), addr + EDMA_TCD_CSR(ch));
}

static inline
void fsl_edma_fill_tcd(struct fsl_edma_hw_tcd *tcd, u32 src, u32 dst,
		       u16 attr, u16 soff, u32 nbytes, u32 slast, u16 citer,
		       u16 biter, u16 doff, u32 dlast_sga, bool major_int,
		       bool disable_req, bool enable_sg)
{
	u16 csr = 0;

	/*
	 * eDMA hardware SGs require the TCDs to be stored in little
	 * endian format irrespective of the register endian model.
	 * So we put the value in little endian in memory, waiting
	 * for fsl_edma_set_tcd_regs doing the swap.
	 */
	tcd->saddr = cpu_to_le32(src);
	tcd->daddr = cpu_to_le32(dst);

	tcd->attr = cpu_to_le16(attr);

	tcd->soff = cpu_to_le16(EDMA_TCD_SOFF_SOFF(soff));

	tcd->nbytes = cpu_to_le32(EDMA_TCD_NBYTES_NBYTES(nbytes));
	tcd->slast = cpu_to_le32(EDMA_TCD_SLAST_SLAST(slast));

	tcd->citer = cpu_to_le16(EDMA_TCD_CITER_CITER(citer));
	tcd->doff = cpu_to_le16(EDMA_TCD_DOFF_DOFF(doff));

	tcd->dlast_sga = cpu_to_le32(EDMA_TCD_DLAST_SGA_DLAST_SGA(dlast_sga));

	tcd->biter = cpu_to_le16(EDMA_TCD_BITER_BITER(biter));
	if (major_int)
		csr |= EDMA_TCD_CSR_INT_MAJOR;

	if (disable_req)
		csr |= EDMA_TCD_CSR_D_REQ;

	if (enable_sg)
		csr |= EDMA_TCD_CSR_E_SG;

	tcd->csr = cpu_to_le16(csr);
}

static struct fsl_edma_desc *fsl_edma_alloc_desc(struct fsl_edma_chan *fsl_chan,
		int sg_len)
{
	struct fsl_edma_desc *fsl_desc;
	int i;

	fsl_desc = kzalloc(sizeof(*fsl_desc) + sizeof(struct fsl_edma_sw_tcd) * sg_len,
				GFP_NOWAIT);
	if (!fsl_desc)
		return NULL;

	fsl_desc->echan = fsl_chan;
	fsl_desc->n_tcds = sg_len;
	for (i = 0; i < sg_len; i++) {
		fsl_desc->tcd[i].vtcd = dma_pool_alloc(fsl_chan->tcd_pool,
					GFP_NOWAIT, &fsl_desc->tcd[i].ptcd);
		if (!fsl_desc->tcd[i].vtcd)
			goto err;
	}
	return fsl_desc;

err:
	while (--i >= 0)
		dma_pool_free(fsl_chan->tcd_pool, fsl_desc->tcd[i].vtcd,
				fsl_desc->tcd[i].ptcd);
	kfree(fsl_desc);
	return NULL;
}

static struct dma_async_tx_descriptor *fsl_edma_prep_dma_cyclic(
		struct dma_chan *chan, dma_addr_t dma_addr, size_t buf_len,
		size_t period_len, enum dma_transfer_direction direction,
		unsigned long flags)
{
	struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
	struct fsl_edma_desc *fsl_desc;
	dma_addr_t dma_buf_next;
	int sg_len, i;
	u32 src_addr, dst_addr, last_sg, nbytes;
	u16 soff, doff, iter;

	if (!is_slave_direction(fsl_chan->fsc.dir))
		return NULL;

	sg_len = buf_len / period_len;
	fsl_desc = fsl_edma_alloc_desc(fsl_chan, sg_len);
	if (!fsl_desc)
		return NULL;
	fsl_desc->iscyclic = true;

	dma_buf_next = dma_addr;
	nbytes = fsl_chan->fsc.addr_width * fsl_chan->fsc.burst;
	iter = period_len / nbytes;

	for (i = 0; i < sg_len; i++) {
		if (dma_buf_next >= dma_addr + buf_len)
			dma_buf_next = dma_addr;

		/* get next sg's physical address */
		last_sg = fsl_desc->tcd[(i + 1) % sg_len].ptcd;

		if (fsl_chan->fsc.dir == DMA_MEM_TO_DEV) {
			src_addr = dma_buf_next;
			dst_addr = fsl_chan->fsc.dev_addr;
			soff = fsl_chan->fsc.addr_width;
			doff = 0;
		} else {
			src_addr = fsl_chan->fsc.dev_addr;
			dst_addr = dma_buf_next;
			soff = 0;
			doff = fsl_chan->fsc.addr_width;
		}

		fsl_edma_fill_tcd(fsl_desc->tcd[i].vtcd, src_addr, dst_addr,
				  fsl_chan->fsc.attr, soff, nbytes, 0, iter,
				  iter, doff, last_sg, true, false, true);
		dma_buf_next += period_len;
	}

	return vchan_tx_prep(&fsl_chan->vchan, &fsl_desc->vdesc, flags);
}

static struct dma_async_tx_descriptor *fsl_edma_prep_slave_sg(
		struct dma_chan *chan, struct scatterlist *sgl,
		unsigned int sg_len, enum dma_transfer_direction direction,
		unsigned long flags, void *context)
{
	struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
	struct fsl_edma_desc *fsl_desc;
	struct scatterlist *sg;
	u32 src_addr, dst_addr, last_sg, nbytes;
	u16 soff, doff, iter;
	int i;

	if (!is_slave_direction(fsl_chan->fsc.dir))
		return NULL;

	fsl_desc = fsl_edma_alloc_desc(fsl_chan, sg_len);
	if (!fsl_desc)
		return NULL;
	fsl_desc->iscyclic = false;

	nbytes = fsl_chan->fsc.addr_width * fsl_chan->fsc.burst;
	for_each_sg(sgl, sg, sg_len, i) {
		/* get next sg's physical address */
		last_sg = fsl_desc->tcd[(i + 1) % sg_len].ptcd;

		if (fsl_chan->fsc.dir == DMA_MEM_TO_DEV) {
			src_addr = sg_dma_address(sg);
			dst_addr = fsl_chan->fsc.dev_addr;
			soff = fsl_chan->fsc.addr_width;
			doff = 0;
		} else {
			src_addr = fsl_chan->fsc.dev_addr;
			dst_addr = sg_dma_address(sg);
			soff = 0;
			doff = fsl_chan->fsc.addr_width;
		}

		iter = sg_dma_len(sg) / nbytes;
		if (i < sg_len - 1) {
			last_sg = fsl_desc->tcd[(i + 1)].ptcd;
			fsl_edma_fill_tcd(fsl_desc->tcd[i].vtcd, src_addr,
					  dst_addr, fsl_chan->fsc.attr, soff,
					  nbytes, 0, iter, iter, doff, last_sg,
					  false, false, true);
		} else {
			last_sg = 0;
			fsl_edma_fill_tcd(fsl_desc->tcd[i].vtcd, src_addr,
					  dst_addr, fsl_chan->fsc.attr, soff,
					  nbytes, 0, iter, iter, doff, last_sg,
					  true, true, false);
		}
	}

	return vchan_tx_prep(&fsl_chan->vchan, &fsl_desc->vdesc, flags);
}

static void fsl_edma_xfer_desc(struct fsl_edma_chan *fsl_chan)
{
	struct virt_dma_desc *vdesc;

	vdesc = vchan_next_desc(&fsl_chan->vchan);
	if (!vdesc)
		return;
	fsl_chan->edesc = to_fsl_edma_desc(vdesc);
	fsl_edma_set_tcd_regs(fsl_chan, fsl_chan->edesc->tcd[0].vtcd);
	fsl_edma_enable_request(fsl_chan);
	fsl_chan->status = DMA_IN_PROGRESS;
}

static irqreturn_t fsl_edma_tx_handler(int irq, void *dev_id)
{
	struct fsl_edma_engine *fsl_edma = dev_id;
	unsigned int intr, ch;
	void __iomem *base_addr;
	struct fsl_edma_chan *fsl_chan;

	base_addr = fsl_edma->membase;

	intr = edma_readl(fsl_edma, base_addr + EDMA_INTR);
	if (!intr)
		return IRQ_NONE;

	for (ch = 0; ch < fsl_edma->n_chans; ch++) {
		if (intr & (0x1 << ch)) {
			edma_writeb(fsl_edma, EDMA_CINT_CINT(ch),
				base_addr + EDMA_CINT);

			fsl_chan = &fsl_edma->chans[ch];

			spin_lock(&fsl_chan->vchan.lock);
			if (!fsl_chan->edesc->iscyclic) {
				list_del(&fsl_chan->edesc->vdesc.node);
				vchan_cookie_complete(&fsl_chan->edesc->vdesc);
				fsl_chan->edesc = NULL;
				fsl_chan->status = DMA_COMPLETE;
			} else {
				vchan_cyclic_callback(&fsl_chan->edesc->vdesc);
			}

			if (!fsl_chan->edesc)
				fsl_edma_xfer_desc(fsl_chan);

			spin_unlock(&fsl_chan->vchan.lock);
		}
	}
	return IRQ_HANDLED;
}

static irqreturn_t fsl_edma_err_handler(int irq, void *dev_id)
{
	struct fsl_edma_engine *fsl_edma = dev_id;
	unsigned int err, ch;

	err = edma_readl(fsl_edma, fsl_edma->membase + EDMA_ERR);
	if (!err)
		return IRQ_NONE;

	for (ch = 0; ch < fsl_edma->n_chans; ch++) {
		if (err & (0x1 << ch)) {
			fsl_edma_disable_request(&fsl_edma->chans[ch]);
			edma_writeb(fsl_edma, EDMA_CERR_CERR(ch),
				fsl_edma->membase + EDMA_CERR);
			fsl_edma->chans[ch].status = DMA_ERROR;
		}
	}
	return IRQ_HANDLED;
}

static irqreturn_t fsl_edma_irq_handler(int irq, void *dev_id)
{
	if (fsl_edma_tx_handler(irq, dev_id) == IRQ_HANDLED)
		return IRQ_HANDLED;

	return fsl_edma_err_handler(irq, dev_id);
}

static void fsl_edma_issue_pending(struct dma_chan *chan)
{
	struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
	unsigned long flags;

	spin_lock_irqsave(&fsl_chan->vchan.lock, flags);

	if (vchan_issue_pending(&fsl_chan->vchan) && !fsl_chan->edesc)
		fsl_edma_xfer_desc(fsl_chan);

	spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);
}

static struct dma_chan *fsl_edma_xlate(struct of_phandle_args *dma_spec,
		struct of_dma *ofdma)
{
	struct fsl_edma_engine *fsl_edma = ofdma->of_dma_data;
	struct dma_chan *chan, *_chan;
	unsigned long chans_per_mux = fsl_edma->n_chans / DMAMUX_NR;

	if (dma_spec->args_count != 2)
		return NULL;

	mutex_lock(&fsl_edma->fsl_edma_mutex);
	list_for_each_entry_safe(chan, _chan, &fsl_edma->dma_dev.channels, device_node) {
		if (chan->client_count)
			continue;
		if ((chan->chan_id / chans_per_mux) == dma_spec->args[0]) {
			chan = dma_get_slave_channel(chan);
			if (chan) {
				chan->device->privatecnt++;
				fsl_edma_chan_mux(to_fsl_edma_chan(chan),
					dma_spec->args[1], true);
				mutex_unlock(&fsl_edma->fsl_edma_mutex);
				return chan;
			}
		}
	}
	mutex_unlock(&fsl_edma->fsl_edma_mutex);
	return NULL;
}

static int fsl_edma_alloc_chan_resources(struct dma_chan *chan)
{
	struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);

	fsl_chan->tcd_pool = dma_pool_create("tcd_pool", chan->device->dev,
				sizeof(struct fsl_edma_hw_tcd),
				32, 0);
	return 0;
}

static void fsl_edma_free_chan_resources(struct dma_chan *chan)
{
	struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
	unsigned long flags;
	LIST_HEAD(head);

	spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
	fsl_edma_disable_request(fsl_chan);
	fsl_edma_chan_mux(fsl_chan, 0, false);
	fsl_chan->edesc = NULL;
	vchan_get_all_descriptors(&fsl_chan->vchan, &head);
	spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);

	vchan_dma_desc_free_list(&fsl_chan->vchan, &head);
	dma_pool_destroy(fsl_chan->tcd_pool);
	fsl_chan->tcd_pool = NULL;
}

static int fsl_dma_device_slave_caps(struct dma_chan *dchan,
		struct dma_slave_caps *caps)
{
	caps->src_addr_widths = FSL_EDMA_BUSWIDTHS;
	caps->dstn_addr_widths = FSL_EDMA_BUSWIDTHS;
	caps->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
	caps->cmd_pause = true;
	caps->cmd_terminate = true;

	return 0;
}

static int
fsl_edma_irq_init(struct platform_device *pdev, struct fsl_edma_engine *fsl_edma)
{
	int ret;

	fsl_edma->txirq = platform_get_irq_byname(pdev, "edma-tx");
	if (fsl_edma->txirq < 0) {
		dev_err(&pdev->dev, "Can't get edma-tx irq.\n");
		return fsl_edma->txirq;
	}

	fsl_edma->errirq = platform_get_irq_byname(pdev, "edma-err");
	if (fsl_edma->errirq < 0) {
		dev_err(&pdev->dev, "Can't get edma-err irq.\n");
		return fsl_edma->errirq;
	}

	if (fsl_edma->txirq == fsl_edma->errirq) {
		ret = devm_request_irq(&pdev->dev, fsl_edma->txirq,
				fsl_edma_irq_handler, 0, "eDMA", fsl_edma);
		if (ret) {
			dev_err(&pdev->dev, "Can't register eDMA IRQ.\n");
			 return  ret;
		}
	} else {
		ret = devm_request_irq(&pdev->dev, fsl_edma->txirq,
				fsl_edma_tx_handler, 0, "eDMA tx", fsl_edma);
		if (ret) {
			dev_err(&pdev->dev, "Can't register eDMA tx IRQ.\n");
			return  ret;
		}

		ret = devm_request_irq(&pdev->dev, fsl_edma->errirq,
				fsl_edma_err_handler, 0, "eDMA err", fsl_edma);
		if (ret) {
			dev_err(&pdev->dev, "Can't register eDMA err IRQ.\n");
			return  ret;
		}
	}

	return 0;
}

static int fsl_edma_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct fsl_edma_engine *fsl_edma;
	struct fsl_edma_chan *fsl_chan;
	struct resource *res;
	int len, chans;
	int ret, i;

	ret = of_property_read_u32(np, "dma-channels", &chans);
	if (ret) {
		dev_err(&pdev->dev, "Can't get dma-channels.\n");
		return ret;
	}

	len = sizeof(*fsl_edma) + sizeof(*fsl_chan) * chans;
	fsl_edma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL);
	if (!fsl_edma)
		return -ENOMEM;

	fsl_edma->n_chans = chans;
	mutex_init(&fsl_edma->fsl_edma_mutex);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	fsl_edma->membase = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(fsl_edma->membase))
		return PTR_ERR(fsl_edma->membase);

	for (i = 0; i < DMAMUX_NR; i++) {
		char clkname[32];

		res = platform_get_resource(pdev, IORESOURCE_MEM, 1 + i);
		fsl_edma->muxbase[i] = devm_ioremap_resource(&pdev->dev, res);
		if (IS_ERR(fsl_edma->muxbase[i]))
			return PTR_ERR(fsl_edma->muxbase[i]);

		sprintf(clkname, "dmamux%d", i);
		fsl_edma->muxclk[i] = devm_clk_get(&pdev->dev, clkname);
		if (IS_ERR(fsl_edma->muxclk[i])) {
			dev_err(&pdev->dev, "Missing DMAMUX block clock.\n");
			return PTR_ERR(fsl_edma->muxclk[i]);
		}

		ret = clk_prepare_enable(fsl_edma->muxclk[i]);
		if (ret) {
			dev_err(&pdev->dev, "DMAMUX clk block failed.\n");
			return ret;
		}

	}

	ret = fsl_edma_irq_init(pdev, fsl_edma);
	if (ret)
		return ret;

	fsl_edma->big_endian = of_property_read_bool(np, "big-endian");

	INIT_LIST_HEAD(&fsl_edma->dma_dev.channels);
	for (i = 0; i < fsl_edma->n_chans; i++) {
		struct fsl_edma_chan *fsl_chan = &fsl_edma->chans[i];

		fsl_chan->edma = fsl_edma;

		fsl_chan->vchan.desc_free = fsl_edma_free_desc;
		vchan_init(&fsl_chan->vchan, &fsl_edma->dma_dev);

		edma_writew(fsl_edma, 0x0, fsl_edma->membase + EDMA_TCD_CSR(i));
		fsl_edma_chan_mux(fsl_chan, 0, false);
	}

	dma_cap_set(DMA_PRIVATE, fsl_edma->dma_dev.cap_mask);
	dma_cap_set(DMA_SLAVE, fsl_edma->dma_dev.cap_mask);
	dma_cap_set(DMA_CYCLIC, fsl_edma->dma_dev.cap_mask);

	fsl_edma->dma_dev.dev = &pdev->dev;
	fsl_edma->dma_dev.device_alloc_chan_resources
		= fsl_edma_alloc_chan_resources;
	fsl_edma->dma_dev.device_free_chan_resources
		= fsl_edma_free_chan_resources;
	fsl_edma->dma_dev.device_tx_status = fsl_edma_tx_status;
	fsl_edma->dma_dev.device_prep_slave_sg = fsl_edma_prep_slave_sg;
	fsl_edma->dma_dev.device_prep_dma_cyclic = fsl_edma_prep_dma_cyclic;
	fsl_edma->dma_dev.device_control = fsl_edma_control;
	fsl_edma->dma_dev.device_issue_pending = fsl_edma_issue_pending;
	fsl_edma->dma_dev.device_slave_caps = fsl_dma_device_slave_caps;

	platform_set_drvdata(pdev, fsl_edma);

	ret = dma_async_device_register(&fsl_edma->dma_dev);
	if (ret) {
		dev_err(&pdev->dev, "Can't register Freescale eDMA engine.\n");
		return ret;
	}

	ret = of_dma_controller_register(np, fsl_edma_xlate, fsl_edma);
	if (ret) {
		dev_err(&pdev->dev, "Can't register Freescale eDMA of_dma.\n");
		dma_async_device_unregister(&fsl_edma->dma_dev);
		return ret;
	}

	/* enable round robin arbitration */
	edma_writel(fsl_edma, EDMA_CR_ERGA | EDMA_CR_ERCA, fsl_edma->membase + EDMA_CR);

	return 0;
}

static int fsl_edma_remove(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct fsl_edma_engine *fsl_edma = platform_get_drvdata(pdev);
	int i;

	of_dma_controller_free(np);
	dma_async_device_unregister(&fsl_edma->dma_dev);

	for (i = 0; i < DMAMUX_NR; i++)
		clk_disable_unprepare(fsl_edma->muxclk[i]);

	return 0;
}

static const struct of_device_id fsl_edma_dt_ids[] = {
	{ .compatible = "fsl,vf610-edma", },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, fsl_edma_dt_ids);

static struct platform_driver fsl_edma_driver = {
	.driver		= {
		.name	= "fsl-edma",
		.of_match_table = fsl_edma_dt_ids,
	},
	.probe          = fsl_edma_probe,
	.remove		= fsl_edma_remove,
};

static int __init fsl_edma_init(void)
{
	return platform_driver_register(&fsl_edma_driver);
}
subsys_initcall(fsl_edma_init);

static void __exit fsl_edma_exit(void)
{
	platform_driver_unregister(&fsl_edma_driver);
}
module_exit(fsl_edma_exit);

MODULE_ALIAS("platform:fsl-edma");
MODULE_DESCRIPTION("Freescale eDMA engine driver");
MODULE_LICENSE("GPL v2");