arch/arm/mach-imx/dma-v1.c

/*
 *  linux/arch/arm/plat-mxc/dma-v1.c
 *
 *  i.MX DMA registration and IRQ dispatching
 *
 * Copyright 2006 Pavel Pisa <pisa@cmp.felk.cvut.cz>
 * Copyright 2008 Juergen Beisert, <kernel@pengutronix.de>
 * Copyright 2008 Sascha Hauer, <s.hauer@pengutronix.de>
 *
 * 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.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/clk.h>
#include <linux/scatterlist.h>
#include <linux/io.h>

#include <asm/system.h>
#include <asm/irq.h>
#include <mach/hardware.h>
#include <mach/dma-v1.h>

#define DMA_DCR     0x00		/* Control Register */
#define DMA_DISR    0x04		/* Interrupt status Register */
#define DMA_DIMR    0x08		/* Interrupt mask Register */
#define DMA_DBTOSR  0x0c		/* Burst timeout status Register */
#define DMA_DRTOSR  0x10		/* Request timeout Register */
#define DMA_DSESR   0x14		/* Transfer Error Status Register */
#define DMA_DBOSR   0x18		/* Buffer overflow status Register */
#define DMA_DBTOCR  0x1c		/* Burst timeout control Register */
#define DMA_WSRA    0x40		/* W-Size Register A */
#define DMA_XSRA    0x44		/* X-Size Register A */
#define DMA_YSRA    0x48		/* Y-Size Register A */
#define DMA_WSRB    0x4c		/* W-Size Register B */
#define DMA_XSRB    0x50		/* X-Size Register B */
#define DMA_YSRB    0x54		/* Y-Size Register B */
#define DMA_SAR(x)  (0x80 + ((x) << 6))	/* Source Address Registers */
#define DMA_DAR(x)  (0x84 + ((x) << 6))	/* Destination Address Registers */
#define DMA_CNTR(x) (0x88 + ((x) << 6))	/* Count Registers */
#define DMA_CCR(x)  (0x8c + ((x) << 6))	/* Control Registers */
#define DMA_RSSR(x) (0x90 + ((x) << 6))	/* Request source select Registers */
#define DMA_BLR(x)  (0x94 + ((x) << 6))	/* Burst length Registers */
#define DMA_RTOR(x) (0x98 + ((x) << 6))	/* Request timeout Registers */
#define DMA_BUCR(x) (0x98 + ((x) << 6))	/* Bus Utilization Registers */
#define DMA_CCNR(x) (0x9C + ((x) << 6))	/* Channel counter Registers */

#define DCR_DRST           (1<<1)
#define DCR_DEN            (1<<0)
#define DBTOCR_EN          (1<<15)
#define DBTOCR_CNT(x)      ((x) & 0x7fff)
#define CNTR_CNT(x)        ((x) & 0xffffff)
#define CCR_ACRPT          (1<<14)
#define CCR_DMOD_LINEAR    (0x0 << 12)
#define CCR_DMOD_2D        (0x1 << 12)
#define CCR_DMOD_FIFO      (0x2 << 12)
#define CCR_DMOD_EOBFIFO   (0x3 << 12)
#define CCR_SMOD_LINEAR    (0x0 << 10)
#define CCR_SMOD_2D        (0x1 << 10)
#define CCR_SMOD_FIFO      (0x2 << 10)
#define CCR_SMOD_EOBFIFO   (0x3 << 10)
#define CCR_MDIR_DEC       (1<<9)
#define CCR_MSEL_B         (1<<8)
#define CCR_DSIZ_32        (0x0 << 6)
#define CCR_DSIZ_8         (0x1 << 6)
#define CCR_DSIZ_16        (0x2 << 6)
#define CCR_SSIZ_32        (0x0 << 4)
#define CCR_SSIZ_8         (0x1 << 4)
#define CCR_SSIZ_16        (0x2 << 4)
#define CCR_REN            (1<<3)
#define CCR_RPT            (1<<2)
#define CCR_FRC            (1<<1)
#define CCR_CEN            (1<<0)
#define RTOR_EN            (1<<15)
#define RTOR_CLK           (1<<14)
#define RTOR_PSC           (1<<13)

/*
 * struct imx_dma_channel - i.MX specific DMA extension
 * @name: name specified by DMA client
 * @irq_handler: client callback for end of transfer
 * @err_handler: client callback for error condition
 * @data: clients context data for callbacks
 * @dma_mode: direction of the transfer %DMA_MODE_READ or %DMA_MODE_WRITE
 * @sg: pointer to the actual read/written chunk for scatter-gather emulation
 * @resbytes: total residual number of bytes to transfer
 *            (it can be lower or same as sum of SG mapped chunk sizes)
 * @sgcount: number of chunks to be read/written
 *
 * Structure is used for IMX DMA processing. It would be probably good
 * @struct dma_struct in the future for external interfacing and use
 * @struct imx_dma_channel only as extension to it.
 */

struct imx_dma_channel {
	const char *name;
	void (*irq_handler) (int, void *);
	void (*err_handler) (int, void *, int errcode);
	void (*prog_handler) (int, void *, struct scatterlist *);
	void *data;
	unsigned int dma_mode;
	struct scatterlist *sg;
	unsigned int resbytes;
	int dma_num;

	int in_use;

	u32 ccr_from_device;
	u32 ccr_to_device;

	struct timer_list watchdog;

	int hw_chaining;
};

static void __iomem *imx_dmav1_baseaddr;

static void imx_dmav1_writel(unsigned val, unsigned offset)
{
	__raw_writel(val, imx_dmav1_baseaddr + offset);
}

static unsigned imx_dmav1_readl(unsigned offset)
{
	return __raw_readl(imx_dmav1_baseaddr + offset);
}

static struct imx_dma_channel imx_dma_channels[IMX_DMA_CHANNELS];

static struct clk *dma_clk;

static int imx_dma_hw_chain(struct imx_dma_channel *imxdma)
{
	if (cpu_is_mx27())
		return imxdma->hw_chaining;
	else
		return 0;
}

/*
 * imx_dma_sg_next - prepare next chunk for scatter-gather DMA emulation
 */
static inline int imx_dma_sg_next(int channel, struct scatterlist *sg)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];
	unsigned long now;

	if (!imxdma->name) {
		printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
		       __func__, channel);
		return 0;
	}

	now = min(imxdma->resbytes, sg->length);
	if (imxdma->resbytes != IMX_DMA_LENGTH_LOOP)
		imxdma->resbytes -= now;

	if ((imxdma->dma_mode & DMA_MODE_MASK) == DMA_MODE_READ)
		imx_dmav1_writel(sg->dma_address, DMA_DAR(channel));
	else
		imx_dmav1_writel(sg->dma_address, DMA_SAR(channel));

	imx_dmav1_writel(now, DMA_CNTR(channel));

	pr_debug("imxdma%d: next sg chunk dst 0x%08x, src 0x%08x, "
		"size 0x%08x\n", channel,
		 imx_dmav1_readl(DMA_DAR(channel)),
		 imx_dmav1_readl(DMA_SAR(channel)),
		 imx_dmav1_readl(DMA_CNTR(channel)));

	return now;
}

/**
 * imx_dma_setup_single - setup i.MX DMA channel for linear memory to/from
 * device transfer
 *
 * @channel: i.MX DMA channel number
 * @dma_address: the DMA/physical memory address of the linear data block
 *		to transfer
 * @dma_length: length of the data block in bytes
 * @dev_addr: physical device port address
 * @dmamode: DMA transfer mode, %DMA_MODE_READ from the device to the memory
 *           or %DMA_MODE_WRITE from memory to the device
 *
 * Return value: if incorrect parameters are provided -%EINVAL.
 *		Zero indicates success.
 */
int
imx_dma_setup_single(int channel, dma_addr_t dma_address,
		     unsigned int dma_length, unsigned int dev_addr,
		     unsigned int dmamode)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];

	imxdma->sg = NULL;
	imxdma->dma_mode = dmamode;

	if (!dma_address) {
		printk(KERN_ERR "imxdma%d: imx_dma_setup_single null address\n",
		       channel);
		return -EINVAL;
	}

	if (!dma_length) {
		printk(KERN_ERR "imxdma%d: imx_dma_setup_single zero length\n",
		       channel);
		return -EINVAL;
	}

	if ((dmamode & DMA_MODE_MASK) == DMA_MODE_READ) {
		pr_debug("imxdma%d: %s dma_addressg=0x%08x dma_length=%d "
			"dev_addr=0x%08x for read\n",
			channel, __func__, (unsigned int)dma_address,
			dma_length, dev_addr);

		imx_dmav1_writel(dev_addr, DMA_SAR(channel));
		imx_dmav1_writel(dma_address, DMA_DAR(channel));
		imx_dmav1_writel(imxdma->ccr_from_device, DMA_CCR(channel));
	} else if ((dmamode & DMA_MODE_MASK) == DMA_MODE_WRITE) {
		pr_debug("imxdma%d: %s dma_addressg=0x%08x dma_length=%d "
			"dev_addr=0x%08x for write\n",
			channel, __func__, (unsigned int)dma_address,
			dma_length, dev_addr);

		imx_dmav1_writel(dma_address, DMA_SAR(channel));
		imx_dmav1_writel(dev_addr, DMA_DAR(channel));
		imx_dmav1_writel(imxdma->ccr_to_device,
				DMA_CCR(channel));
	} else {
		printk(KERN_ERR "imxdma%d: imx_dma_setup_single bad dmamode\n",
		       channel);
		return -EINVAL;
	}

	imx_dmav1_writel(dma_length, DMA_CNTR(channel));

	return 0;
}
EXPORT_SYMBOL(imx_dma_setup_single);

/**
 * imx_dma_setup_sg - setup i.MX DMA channel SG list to/from device transfer
 * @channel: i.MX DMA channel number
 * @sg: pointer to the scatter-gather list/vector
 * @sgcount: scatter-gather list hungs count
 * @dma_length: total length of the transfer request in bytes
 * @dev_addr: physical device port address
 * @dmamode: DMA transfer mode, %DMA_MODE_READ from the device to the memory
 *           or %DMA_MODE_WRITE from memory to the device
 *
 * The function sets up DMA channel state and registers to be ready for
 * transfer specified by provided parameters. The scatter-gather emulation
 * is set up according to the parameters.
 *
 * The full preparation of the transfer requires setup of more register
 * by the caller before imx_dma_enable() can be called.
 *
 * %BLR(channel) holds transfer burst length in bytes, 0 means 64 bytes
 *
 * %RSSR(channel) has to be set to the DMA request line source %DMA_REQ_xxx
 *
 * %CCR(channel) has to specify transfer parameters, the next settings is
 * typical for linear or simple scatter-gather transfers if %DMA_MODE_READ is
 * specified
 *
 * %CCR_DMOD_LINEAR | %CCR_DSIZ_32 | %CCR_SMOD_FIFO | %CCR_SSIZ_x
 *
 * The typical setup for %DMA_MODE_WRITE is specified by next options
 * combination
 *
 * %CCR_SMOD_LINEAR | %CCR_SSIZ_32 | %CCR_DMOD_FIFO | %CCR_DSIZ_x
 *
 * Be careful here and do not mistakenly mix source and target device
 * port sizes constants, they are really different:
 * %CCR_SSIZ_8, %CCR_SSIZ_16, %CCR_SSIZ_32,
 * %CCR_DSIZ_8, %CCR_DSIZ_16, %CCR_DSIZ_32
 *
 * Return value: if incorrect parameters are provided -%EINVAL.
 * Zero indicates success.
 */
int
imx_dma_setup_sg(int channel,
		 struct scatterlist *sg, unsigned int sgcount,
		 unsigned int dma_length, unsigned int dev_addr,
		 unsigned int dmamode)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];

	if (imxdma->in_use)
		return -EBUSY;

	imxdma->sg = sg;
	imxdma->dma_mode = dmamode;
	imxdma->resbytes = dma_length;

	if (!sg || !sgcount) {
		printk(KERN_ERR "imxdma%d: imx_dma_setup_sg empty sg list\n",
		       channel);
		return -EINVAL;
	}

	if (!sg->length) {
		printk(KERN_ERR "imxdma%d: imx_dma_setup_sg zero length\n",
		       channel);
		return -EINVAL;
	}

	if ((dmamode & DMA_MODE_MASK) == DMA_MODE_READ) {
		pr_debug("imxdma%d: %s sg=%p sgcount=%d total length=%d "
			"dev_addr=0x%08x for read\n",
			channel, __func__, sg, sgcount, dma_length, dev_addr);

		imx_dmav1_writel(dev_addr, DMA_SAR(channel));
		imx_dmav1_writel(imxdma->ccr_from_device, DMA_CCR(channel));
	} else if ((dmamode & DMA_MODE_MASK) == DMA_MODE_WRITE) {
		pr_debug("imxdma%d: %s sg=%p sgcount=%d total length=%d "
			"dev_addr=0x%08x for write\n",
			channel, __func__, sg, sgcount, dma_length, dev_addr);

		imx_dmav1_writel(dev_addr, DMA_DAR(channel));
		imx_dmav1_writel(imxdma->ccr_to_device, DMA_CCR(channel));
	} else {
		printk(KERN_ERR "imxdma%d: imx_dma_setup_sg bad dmamode\n",
		       channel);
		return -EINVAL;
	}

	imx_dma_sg_next(channel, sg);

	return 0;
}
EXPORT_SYMBOL(imx_dma_setup_sg);

int
imx_dma_config_channel(int channel, unsigned int config_port,
	unsigned int config_mem, unsigned int dmareq, int hw_chaining)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];
	u32 dreq = 0;

	imxdma->hw_chaining = 0;

	if (hw_chaining) {
		imxdma->hw_chaining = 1;
		if (!imx_dma_hw_chain(imxdma))
			return -EINVAL;
	}

	if (dmareq)
		dreq = CCR_REN;

	imxdma->ccr_from_device = config_port | (config_mem << 2) | dreq;
	imxdma->ccr_to_device = config_mem | (config_port << 2) | dreq;

	imx_dmav1_writel(dmareq, DMA_RSSR(channel));

	return 0;
}
EXPORT_SYMBOL(imx_dma_config_channel);

void imx_dma_config_burstlen(int channel, unsigned int burstlen)
{
	imx_dmav1_writel(burstlen, DMA_BLR(channel));
}
EXPORT_SYMBOL(imx_dma_config_burstlen);

/**
 * imx_dma_setup_handlers - setup i.MX DMA channel end and error notification
 * handlers
 * @channel: i.MX DMA channel number
 * @irq_handler: the pointer to the function called if the transfer
 *		ends successfully
 * @err_handler: the pointer to the function called if the premature
 *		end caused by error occurs
 * @data: user specified value to be passed to the handlers
 */
int
imx_dma_setup_handlers(int channel,
		       void (*irq_handler) (int, void *),
		       void (*err_handler) (int, void *, int),
		       void *data)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];
	unsigned long flags;

	if (!imxdma->name) {
		printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
		       __func__, channel);
		return -ENODEV;
	}

	local_irq_save(flags);
	imx_dmav1_writel(1 << channel, DMA_DISR);
	imxdma->irq_handler = irq_handler;
	imxdma->err_handler = err_handler;
	imxdma->data = data;
	local_irq_restore(flags);
	return 0;
}
EXPORT_SYMBOL(imx_dma_setup_handlers);

/**
 * imx_dma_setup_progression_handler - setup i.MX DMA channel progression
 * handlers
 * @channel: i.MX DMA channel number
 * @prog_handler: the pointer to the function called if the transfer progresses
 */
int
imx_dma_setup_progression_handler(int channel,
			void (*prog_handler) (int, void*, struct scatterlist*))
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];
	unsigned long flags;

	if (!imxdma->name) {
		printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
		       __func__, channel);
		return -ENODEV;
	}

	local_irq_save(flags);
	imxdma->prog_handler = prog_handler;
	local_irq_restore(flags);
	return 0;
}
EXPORT_SYMBOL(imx_dma_setup_progression_handler);

/**
 * imx_dma_enable - function to start i.MX DMA channel operation
 * @channel: i.MX DMA channel number
 *
 * The channel has to be allocated by driver through imx_dma_request()
 * or imx_dma_request_by_prio() function.
 * The transfer parameters has to be set to the channel registers through
 * call of the imx_dma_setup_single() or imx_dma_setup_sg() function
 * and registers %BLR(channel), %RSSR(channel) and %CCR(channel) has to
 * be set prior this function call by the channel user.
 */
void imx_dma_enable(int channel)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];
	unsigned long flags;

	pr_debug("imxdma%d: imx_dma_enable\n", channel);

	if (!imxdma->name) {
		printk(KERN_CRIT "%s: called for  not allocated channel %d\n",
		       __func__, channel);
		return;
	}

	if (imxdma->in_use)
		return;

	local_irq_save(flags);

	imx_dmav1_writel(1 << channel, DMA_DISR);
	imx_dmav1_writel(imx_dmav1_readl(DMA_DIMR) & ~(1 << channel), DMA_DIMR);
	imx_dmav1_writel(imx_dmav1_readl(DMA_CCR(channel)) | CCR_CEN |
		CCR_ACRPT, DMA_CCR(channel));

	if ((cpu_is_mx21() || cpu_is_mx27()) &&
			imxdma->sg && imx_dma_hw_chain(imxdma)) {
		imxdma->sg = sg_next(imxdma->sg);
		if (imxdma->sg) {
			u32 tmp;
			imx_dma_sg_next(channel, imxdma->sg);
			tmp = imx_dmav1_readl(DMA_CCR(channel));
			imx_dmav1_writel(tmp | CCR_RPT | CCR_ACRPT,
				DMA_CCR(channel));
		}
	}
	imxdma->in_use = 1;

	local_irq_restore(flags);
}
EXPORT_SYMBOL(imx_dma_enable);

/**
 * imx_dma_disable - stop, finish i.MX DMA channel operatin
 * @channel: i.MX DMA channel number
 */
void imx_dma_disable(int channel)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];
	unsigned long flags;

	pr_debug("imxdma%d: imx_dma_disable\n", channel);

	if (imx_dma_hw_chain(imxdma))
		del_timer(&imxdma->watchdog);

	local_irq_save(flags);
	imx_dmav1_writel(imx_dmav1_readl(DMA_DIMR) | (1 << channel), DMA_DIMR);
	imx_dmav1_writel(imx_dmav1_readl(DMA_CCR(channel)) & ~CCR_CEN,
			DMA_CCR(channel));
	imx_dmav1_writel(1 << channel, DMA_DISR);
	imxdma->in_use = 0;
	local_irq_restore(flags);
}
EXPORT_SYMBOL(imx_dma_disable);

static void imx_dma_watchdog(unsigned long chno)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[chno];

	imx_dmav1_writel(0, DMA_CCR(chno));
	imxdma->in_use = 0;
	imxdma->sg = NULL;

	if (imxdma->err_handler)
		imxdma->err_handler(chno, imxdma->data, IMX_DMA_ERR_TIMEOUT);
}

static irqreturn_t dma_err_handler(int irq, void *dev_id)
{
	int i, disr;
	struct imx_dma_channel *imxdma;
	unsigned int err_mask;
	int errcode;

	disr = imx_dmav1_readl(DMA_DISR);

	err_mask = imx_dmav1_readl(DMA_DBTOSR) |
		   imx_dmav1_readl(DMA_DRTOSR) |
		   imx_dmav1_readl(DMA_DSESR)  |
		   imx_dmav1_readl(DMA_DBOSR);

	if (!err_mask)
		return IRQ_HANDLED;

	imx_dmav1_writel(disr & err_mask, DMA_DISR);

	for (i = 0; i < IMX_DMA_CHANNELS; i++) {
		if (!(err_mask & (1 << i)))
			continue;
		imxdma = &imx_dma_channels[i];
		errcode = 0;

		if (imx_dmav1_readl(DMA_DBTOSR) & (1 << i)) {
			imx_dmav1_writel(1 << i, DMA_DBTOSR);
			errcode |= IMX_DMA_ERR_BURST;
		}
		if (imx_dmav1_readl(DMA_DRTOSR) & (1 << i)) {
			imx_dmav1_writel(1 << i, DMA_DRTOSR);
			errcode |= IMX_DMA_ERR_REQUEST;
		}
		if (imx_dmav1_readl(DMA_DSESR) & (1 << i)) {
			imx_dmav1_writel(1 << i, DMA_DSESR);
			errcode |= IMX_DMA_ERR_TRANSFER;
		}
		if (imx_dmav1_readl(DMA_DBOSR) & (1 << i)) {
			imx_dmav1_writel(1 << i, DMA_DBOSR);
			errcode |= IMX_DMA_ERR_BUFFER;
		}
		if (imxdma->name && imxdma->err_handler) {
			imxdma->err_handler(i, imxdma->data, errcode);
			continue;
		}

		imx_dma_channels[i].sg = NULL;

		printk(KERN_WARNING
		       "DMA timeout on channel %d (%s) -%s%s%s%s\n",
		       i, imxdma->name,
		       errcode & IMX_DMA_ERR_BURST ?    " burst" : "",
		       errcode & IMX_DMA_ERR_REQUEST ?  " request" : "",
		       errcode & IMX_DMA_ERR_TRANSFER ? " transfer" : "",
		       errcode & IMX_DMA_ERR_BUFFER ?   " buffer" : "");
	}
	return IRQ_HANDLED;
}

static void dma_irq_handle_channel(int chno)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[chno];

	if (!imxdma->name) {
		/*
		 * IRQ for an unregistered DMA channel:
		 * let's clear the interrupts and disable it.
		 */
		printk(KERN_WARNING
		       "spurious IRQ for DMA channel %d\n", chno);
		return;
	}

	if (imxdma->sg) {
		u32 tmp;
		struct scatterlist *current_sg = imxdma->sg;
		imxdma->sg = sg_next(imxdma->sg);

		if (imxdma->sg) {
			imx_dma_sg_next(chno, imxdma->sg);

			tmp = imx_dmav1_readl(DMA_CCR(chno));

			if (imx_dma_hw_chain(imxdma)) {
				/* FIXME: The timeout should probably be
				 * configurable
				 */
				mod_timer(&imxdma->watchdog,
					jiffies + msecs_to_jiffies(500));

				tmp |= CCR_CEN | CCR_RPT | CCR_ACRPT;
				imx_dmav1_writel(tmp, DMA_CCR(chno));
			} else {
				imx_dmav1_writel(tmp & ~CCR_CEN, DMA_CCR(chno));
				tmp |= CCR_CEN;
			}

			imx_dmav1_writel(tmp, DMA_CCR(chno));

			if (imxdma->prog_handler)
				imxdma->prog_handler(chno, imxdma->data,
						current_sg);

			return;
		}

		if (imx_dma_hw_chain(imxdma)) {
			del_timer(&imxdma->watchdog);
			return;
		}
	}

	imx_dmav1_writel(0, DMA_CCR(chno));
	imxdma->in_use = 0;
	if (imxdma->irq_handler)
		imxdma->irq_handler(chno, imxdma->data);
}

static irqreturn_t dma_irq_handler(int irq, void *dev_id)
{
	int i, disr;

	if (cpu_is_mx21() || cpu_is_mx27())
		dma_err_handler(irq, dev_id);

	disr = imx_dmav1_readl(DMA_DISR);

	pr_debug("imxdma: dma_irq_handler called, disr=0x%08x\n",
		     disr);

	imx_dmav1_writel(disr, DMA_DISR);
	for (i = 0; i < IMX_DMA_CHANNELS; i++) {
		if (disr & (1 << i))
			dma_irq_handle_channel(i);
	}

	return IRQ_HANDLED;
}

/**
 * imx_dma_request - request/allocate specified channel number
 * @channel: i.MX DMA channel number
 * @name: the driver/caller own non-%NULL identification
 */
int imx_dma_request(int channel, const char *name)
{
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];
	unsigned long flags;
	int ret = 0;

	/* basic sanity checks */
	if (!name)
		return -EINVAL;

	if (channel >= IMX_DMA_CHANNELS) {
		printk(KERN_CRIT "%s: called for  non-existed channel %d\n",
		       __func__, channel);
		return -EINVAL;
	}

	local_irq_save(flags);
	if (imxdma->name) {
		local_irq_restore(flags);
		return -EBUSY;
	}
	memset(imxdma, 0, sizeof(*imxdma));
	imxdma->name = name;
	local_irq_restore(flags); /* request_irq() can block */

	if (cpu_is_mx21() || cpu_is_mx27()) {
		ret = request_irq(MX2x_INT_DMACH0 + channel,
				dma_irq_handler, 0, "DMA", NULL);
		if (ret) {
			imxdma->name = NULL;
			pr_crit("Can't register IRQ %d for DMA channel %d\n",
					MX2x_INT_DMACH0 + channel, channel);
			return ret;
		}
		init_timer(&imxdma->watchdog);
		imxdma->watchdog.function = &imx_dma_watchdog;
		imxdma->watchdog.data = channel;
	}

	return ret;
}
EXPORT_SYMBOL(imx_dma_request);

/**
 * imx_dma_free - release previously acquired channel
 * @channel: i.MX DMA channel number
 */
void imx_dma_free(int channel)
{
	unsigned long flags;
	struct imx_dma_channel *imxdma = &imx_dma_channels[channel];

	if (!imxdma->name) {
		printk(KERN_CRIT
		       "%s: trying to free free channel %d\n",
		       __func__, channel);
		return;
	}

	local_irq_save(flags);
	/* Disable interrupts */
	imx_dma_disable(channel);
	imxdma->name = NULL;

	if (cpu_is_mx21() || cpu_is_mx27())
		free_irq(MX2x_INT_DMACH0 + channel, NULL);

	local_irq_restore(flags);
}
EXPORT_SYMBOL(imx_dma_free);

/**
 * imx_dma_request_by_prio - find and request some of free channels best
 * suiting requested priority
 * @channel: i.MX DMA channel number
 * @name: the driver/caller own non-%NULL identification
 *
 * This function tries to find a free channel in the specified priority group
 * if the priority cannot be achieved it tries to look for free channel
 * in the higher and then even lower priority groups.
 *
 * Return value: If there is no free channel to allocate, -%ENODEV is returned.
 *               On successful allocation channel is returned.
 */
int imx_dma_request_by_prio(const char *name, enum imx_dma_prio prio)
{
	int i;
	int best;

	switch (prio) {
	case (DMA_PRIO_HIGH):
		best = 8;
		break;
	case (DMA_PRIO_MEDIUM):
		best = 4;
		break;
	case (DMA_PRIO_LOW):
	default:
		best = 0;
		break;
	}

	for (i = best; i < IMX_DMA_CHANNELS; i++)
		if (!imx_dma_request(i, name))
			return i;

	for (i = best - 1; i >= 0; i--)
		if (!imx_dma_request(i, name))
			return i;

	printk(KERN_ERR "%s: no free DMA channel found\n", __func__);

	return -ENODEV;
}
EXPORT_SYMBOL(imx_dma_request_by_prio);

static int __init imx_dma_init(void)
{
	int ret = 0;
	int i;

	if (cpu_is_mx1())
		imx_dmav1_baseaddr = MX1_IO_ADDRESS(MX1_DMA_BASE_ADDR);
	else if (cpu_is_mx21())
		imx_dmav1_baseaddr = MX21_IO_ADDRESS(MX21_DMA_BASE_ADDR);
	else if (cpu_is_mx27())
		imx_dmav1_baseaddr = MX27_IO_ADDRESS(MX27_DMA_BASE_ADDR);
	else
		return 0;

	dma_clk = clk_get(NULL, "dma");
	if (IS_ERR(dma_clk))
		return PTR_ERR(dma_clk);
	clk_enable(dma_clk);

	/* reset DMA module */
	imx_dmav1_writel(DCR_DRST, DMA_DCR);

	if (cpu_is_mx1()) {
		ret = request_irq(MX1_DMA_INT, dma_irq_handler, 0, "DMA", NULL);
		if (ret) {
			pr_crit("Wow!  Can't register IRQ for DMA\n");
			return ret;
		}

		ret = request_irq(MX1_DMA_ERR, dma_err_handler, 0, "DMA", NULL);
		if (ret) {
			pr_crit("Wow!  Can't register ERRIRQ for DMA\n");
			free_irq(MX1_DMA_INT, NULL);
			return ret;
		}
	}

	/* enable DMA module */
	imx_dmav1_writel(DCR_DEN, DMA_DCR);

	/* clear all interrupts */
	imx_dmav1_writel((1 << IMX_DMA_CHANNELS) - 1, DMA_DISR);

	/* disable interrupts */
	imx_dmav1_writel((1 << IMX_DMA_CHANNELS) - 1, DMA_DIMR);

	for (i = 0; i < IMX_DMA_CHANNELS; i++) {
		imx_dma_channels[i].sg = NULL;
		imx_dma_channels[i].dma_num = i;
	}

	return ret;
}

arch_initcall(imx_dma_init);