drivers/dma/imx-dma.c - maze/linux - Git at Google

 /*
  * drivers/dma/imx-dma.c
  *
  * This file contains a driver for the Freescale i.MX DMA engine
  * found on i.MX1/21/27
  *
  * Copyright 2010 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
  *
  * The code contained herein is licensed under the GNU General Public
  * License. You may obtain a copy of the GNU General Public License
  * Version 2 or later at the following locations:
  *
  * http://www.opensource.org/licenses/gpl-license.html
  * http://www.gnu.org/copyleft/gpl.html
  */
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/platform_device.h>
 #include <linux/dmaengine.h>

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

 struct imxdma_channel {
 	struct imxdma_engine		*imxdma;
 	unsigned int			channel;
 	unsigned int			imxdma_channel;

 	enum dma_slave_buswidth		word_size;
 	dma_addr_t			per_address;
 	u32				watermark_level;
 	struct dma_chan			chan;
 	spinlock_t			lock;
 	struct dma_async_tx_descriptor	desc;
 	dma_cookie_t			last_completed;
 	enum dma_status			status;
 	int				dma_request;
 	struct scatterlist		*sg_list;
 };

 #define MAX_DMA_CHANNELS 8

 struct imxdma_engine {
 	struct device			*dev;
 	struct device_dma_parameters	dma_parms;
 	struct dma_device		dma_device;
 	struct imxdma_channel		channel[MAX_DMA_CHANNELS];
 };

 static struct imxdma_channel *to_imxdma_chan(struct dma_chan *chan)
 {
 	return container_of(chan, struct imxdma_channel, chan);
 }

 static void imxdma_handle(struct imxdma_channel *imxdmac)
 {
 	if (imxdmac->desc.callback)
 		imxdmac->desc.callback(imxdmac->desc.callback_param);
 	imxdmac->last_completed = imxdmac->desc.cookie;
 }

 static void imxdma_irq_handler(int channel, void *data)
 {
 	struct imxdma_channel *imxdmac = data;

 	imxdmac->status = DMA_SUCCESS;
 	imxdma_handle(imxdmac);
 }

 static void imxdma_err_handler(int channel, void *data, int error)
 {
 	struct imxdma_channel *imxdmac = data;

 	imxdmac->status = DMA_ERROR;
 	imxdma_handle(imxdmac);
 }

 static void imxdma_progression(int channel, void *data,
 		struct scatterlist *sg)
 {
 	struct imxdma_channel *imxdmac = data;

 	imxdmac->status = DMA_SUCCESS;
 	imxdma_handle(imxdmac);
 }

 static int imxdma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
 		unsigned long arg)
 {
 	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
 	struct dma_slave_config *dmaengine_cfg = (void *)arg;
 	int ret;
 	unsigned int mode = 0;

 	switch (cmd) {
 	case DMA_TERMINATE_ALL:
 		imxdmac->status = DMA_ERROR;
 		imx_dma_disable(imxdmac->imxdma_channel);
 		return 0;
 	case DMA_SLAVE_CONFIG:
 		if (dmaengine_cfg->direction == DMA_FROM_DEVICE) {
 			imxdmac->per_address = dmaengine_cfg->src_addr;
 			imxdmac->watermark_level = dmaengine_cfg->src_maxburst;
 			imxdmac->word_size = dmaengine_cfg->src_addr_width;
 		} else {
 			imxdmac->per_address = dmaengine_cfg->dst_addr;
 			imxdmac->watermark_level = dmaengine_cfg->dst_maxburst;
 			imxdmac->word_size = dmaengine_cfg->dst_addr_width;
 		}

 		switch (imxdmac->word_size) {
 		case DMA_SLAVE_BUSWIDTH_1_BYTE:
 			mode = IMX_DMA_MEMSIZE_8;
 			break;
 		case DMA_SLAVE_BUSWIDTH_2_BYTES:
 			mode = IMX_DMA_MEMSIZE_16;
 			break;
 		default:
 		case DMA_SLAVE_BUSWIDTH_4_BYTES:
 			mode = IMX_DMA_MEMSIZE_32;
 			break;
 		}
 		ret = imx_dma_config_channel(imxdmac->imxdma_channel,
 				mode | IMX_DMA_TYPE_FIFO,
 				IMX_DMA_MEMSIZE_32 | IMX_DMA_TYPE_LINEAR,
 				imxdmac->dma_request, 1);

 		if (ret)
 			return ret;

 		imx_dma_config_burstlen(imxdmac->imxdma_channel,
 				imxdmac->watermark_level * imxdmac->word_size);

 		return 0;
 	default:
 		return -ENOSYS;
 	}

 	return -EINVAL;
 }

 static enum dma_status imxdma_tx_status(struct dma_chan *chan,
 					    dma_cookie_t cookie,
 					    struct dma_tx_state *txstate)
 {
 	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
 	dma_cookie_t last_used;
 	enum dma_status ret;

 	last_used = chan->cookie;

 	ret = dma_async_is_complete(cookie, imxdmac->last_completed, last_used);
 	dma_set_tx_state(txstate, imxdmac->last_completed, last_used, 0);

 	return ret;
 }

 static dma_cookie_t imxdma_assign_cookie(struct imxdma_channel *imxdma)
 {
 	dma_cookie_t cookie = imxdma->chan.cookie;

 	if (++cookie < 0)
 		cookie = 1;

 	imxdma->chan.cookie = cookie;
 	imxdma->desc.cookie = cookie;

 	return cookie;
 }

 static dma_cookie_t imxdma_tx_submit(struct dma_async_tx_descriptor *tx)
 {
 	struct imxdma_channel *imxdmac = to_imxdma_chan(tx->chan);
 	dma_cookie_t cookie;

 	spin_lock_irq(&imxdmac->lock);

 	cookie = imxdma_assign_cookie(imxdmac);

 	imx_dma_enable(imxdmac->imxdma_channel);

 	spin_unlock_irq(&imxdmac->lock);

 	return cookie;
 }

 static int imxdma_alloc_chan_resources(struct dma_chan *chan)
 {
 	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
 	struct imx_dma_data *data = chan->private;

 	imxdmac->dma_request = data->dma_request;

 	dma_async_tx_descriptor_init(&imxdmac->desc, chan);
 	imxdmac->desc.tx_submit = imxdma_tx_submit;
 	/* txd.flags will be overwritten in prep funcs */
 	imxdmac->desc.flags = DMA_CTRL_ACK;

 	imxdmac->status = DMA_SUCCESS;

 	return 0;
 }

 static void imxdma_free_chan_resources(struct dma_chan *chan)
 {
 	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);

 	imx_dma_disable(imxdmac->imxdma_channel);

 	if (imxdmac->sg_list) {
 		kfree(imxdmac->sg_list);
 		imxdmac->sg_list = NULL;
 	}
 }

 static struct dma_async_tx_descriptor *imxdma_prep_slave_sg(
 		struct dma_chan *chan, struct scatterlist *sgl,
 		unsigned int sg_len, enum dma_data_direction direction,
 		unsigned long flags)
 {
 	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
 	struct scatterlist *sg;
 	int i, ret, dma_length = 0;
 	unsigned int dmamode;

 	if (imxdmac->status == DMA_IN_PROGRESS)
 		return NULL;

 	imxdmac->status = DMA_IN_PROGRESS;

 	for_each_sg(sgl, sg, sg_len, i) {
 		dma_length += sg->length;
 	}

 	if (direction == DMA_FROM_DEVICE)
 		dmamode = DMA_MODE_READ;
 	else
 		dmamode = DMA_MODE_WRITE;

 	switch (imxdmac->word_size) {
 	case DMA_SLAVE_BUSWIDTH_4_BYTES:
 		if (sgl->length & 3 || sgl->dma_address & 3)
 			return NULL;
 		break;
 	case DMA_SLAVE_BUSWIDTH_2_BYTES:
 		if (sgl->length & 1 || sgl->dma_address & 1)
 			return NULL;
 		break;
 	case DMA_SLAVE_BUSWIDTH_1_BYTE:
 		break;
 	default:
 		return NULL;
 	}

 	ret = imx_dma_setup_sg(imxdmac->imxdma_channel, sgl, sg_len,
 		 dma_length, imxdmac->per_address, dmamode);
 	if (ret)
 		return NULL;

 	return &imxdmac->desc;
 }

 static struct dma_async_tx_descriptor *imxdma_prep_dma_cyclic(
 		struct dma_chan *chan, dma_addr_t dma_addr, size_t buf_len,
 		size_t period_len, enum dma_data_direction direction)
 {
 	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
 	struct imxdma_engine *imxdma = imxdmac->imxdma;
 	int i, ret;
 	unsigned int periods = buf_len / period_len;
 	unsigned int dmamode;

 	dev_dbg(imxdma->dev, "%s channel: %d buf_len=%d period_len=%d\n",
 			__func__, imxdmac->channel, buf_len, period_len);

 	if (imxdmac->status == DMA_IN_PROGRESS)
 		return NULL;
 	imxdmac->status = DMA_IN_PROGRESS;

 	ret = imx_dma_setup_progression_handler(imxdmac->imxdma_channel,
 			imxdma_progression);
 	if (ret) {
 		dev_err(imxdma->dev, "Failed to setup the DMA handler\n");
 		return NULL;
 	}

 	if (imxdmac->sg_list)
 		kfree(imxdmac->sg_list);

 	imxdmac->sg_list = kcalloc(periods + 1,
 			sizeof(struct scatterlist), GFP_KERNEL);
 	if (!imxdmac->sg_list)
 		return NULL;

 	sg_init_table(imxdmac->sg_list, periods);

 	for (i = 0; i < periods; i++) {
 		imxdmac->sg_list[i].page_link = 0;
 		imxdmac->sg_list[i].offset = 0;
 		imxdmac->sg_list[i].dma_address = dma_addr;
 		imxdmac->sg_list[i].length = period_len;
 		dma_addr += period_len;
 	}

 	/* close the loop */
 	imxdmac->sg_list[periods].offset = 0;
 	imxdmac->sg_list[periods].length = 0;
 	imxdmac->sg_list[periods].page_link =
 		((unsigned long)imxdmac->sg_list | 0x01) & ~0x02;

 	if (direction == DMA_FROM_DEVICE)
 		dmamode = DMA_MODE_READ;
 	else
 		dmamode = DMA_MODE_WRITE;

 	ret = imx_dma_setup_sg(imxdmac->imxdma_channel, imxdmac->sg_list, periods,
 		 IMX_DMA_LENGTH_LOOP, imxdmac->per_address, dmamode);
 	if (ret)
 		return NULL;

 	return &imxdmac->desc;
 }

 static void imxdma_issue_pending(struct dma_chan *chan)
 {
 	/*
 	 * Nothing to do. We only have a single descriptor
 	 */
 }

 static int __init imxdma_probe(struct platform_device *pdev)
 {
 	struct imxdma_engine *imxdma;
 	int ret, i;

 	imxdma = kzalloc(sizeof(*imxdma), GFP_KERNEL);
 	if (!imxdma)
 		return -ENOMEM;

 	INIT_LIST_HEAD(&imxdma->dma_device.channels);

 	dma_cap_set(DMA_SLAVE, imxdma->dma_device.cap_mask);
 	dma_cap_set(DMA_CYCLIC, imxdma->dma_device.cap_mask);

 	/* Initialize channel parameters */
 	for (i = 0; i < MAX_DMA_CHANNELS; i++) {
 		struct imxdma_channel *imxdmac = &imxdma->channel[i];

 		imxdmac->imxdma_channel = imx_dma_request_by_prio("dmaengine",
 				DMA_PRIO_MEDIUM);
 		if ((int)imxdmac->channel < 0) {
 			ret = -ENODEV;
 			goto err_init;
 		}

 		imx_dma_setup_handlers(imxdmac->imxdma_channel,
 		       imxdma_irq_handler, imxdma_err_handler, imxdmac);

 		imxdmac->imxdma = imxdma;
 		spin_lock_init(&imxdmac->lock);

 		imxdmac->chan.device = &imxdma->dma_device;
 		imxdmac->channel = i;

 		/* Add the channel to the DMAC list */
 		list_add_tail(&imxdmac->chan.device_node, &imxdma->dma_device.channels);
 	}

 	imxdma->dev = &pdev->dev;
 	imxdma->dma_device.dev = &pdev->dev;

 	imxdma->dma_device.device_alloc_chan_resources = imxdma_alloc_chan_resources;
 	imxdma->dma_device.device_free_chan_resources = imxdma_free_chan_resources;
 	imxdma->dma_device.device_tx_status = imxdma_tx_status;
 	imxdma->dma_device.device_prep_slave_sg = imxdma_prep_slave_sg;
 	imxdma->dma_device.device_prep_dma_cyclic = imxdma_prep_dma_cyclic;
 	imxdma->dma_device.device_control = imxdma_control;
 	imxdma->dma_device.device_issue_pending = imxdma_issue_pending;

 	platform_set_drvdata(pdev, imxdma);

 	imxdma->dma_device.dev->dma_parms = &imxdma->dma_parms;
 	dma_set_max_seg_size(imxdma->dma_device.dev, 0xffffff);

 	ret = dma_async_device_register(&imxdma->dma_device);
 	if (ret) {
 		dev_err(&pdev->dev, "unable to register\n");
 		goto err_init;
 	}

 	return 0;

 err_init:
 	while (--i >= 0) {
 		struct imxdma_channel *imxdmac = &imxdma->channel[i];
 		imx_dma_free(imxdmac->imxdma_channel);
 	}

 	kfree(imxdma);
 	return ret;
 }

 static int __exit imxdma_remove(struct platform_device *pdev)
 {
 	struct imxdma_engine *imxdma = platform_get_drvdata(pdev);
 	int i;

         dma_async_device_unregister(&imxdma->dma_device);

 	for (i = 0; i < MAX_DMA_CHANNELS; i++) {
 		struct imxdma_channel *imxdmac = &imxdma->channel[i];

 		 imx_dma_free(imxdmac->imxdma_channel);
 	}

         kfree(imxdma);

         return 0;
 }

 static struct platform_driver imxdma_driver = {
 	.driver		= {
 		.name	= "imx-dma",
 	},
 	.remove		= __exit_p(imxdma_remove),
 };

 static int __init imxdma_module_init(void)
 {
 	return platform_driver_probe(&imxdma_driver, imxdma_probe);
 }
 subsys_initcall(imxdma_module_init);

 MODULE_AUTHOR("Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>");
 MODULE_DESCRIPTION("i.MX dma driver");
 MODULE_LICENSE("GPL");
	/*
	* drivers/dma/imx-dma.c
	*
	* This file contains a driver for the Freescale i.MX DMA engine
	* found on i.MX1/21/27
	*
	* Copyright 2010 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
	*
	* The code contained herein is licensed under the GNU General Public
	* License. You may obtain a copy of the GNU General Public License
	* Version 2 or later at the following locations:
	*
	* http://www.opensource.org/licenses/gpl-license.html
	* http://www.gnu.org/copyleft/gpl.html
	*/
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/types.h>
	#include <linux/mm.h>
	#include <linux/interrupt.h>
	#include <linux/spinlock.h>
	#include <linux/device.h>
	#include <linux/dma-mapping.h>
	#include <linux/slab.h>
	#include <linux/platform_device.h>
	#include <linux/dmaengine.h>

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

	struct imxdma_channel {
	struct imxdma_engine *imxdma;
	unsigned int channel;
	unsigned int imxdma_channel;

	enum dma_slave_buswidth word_size;
	dma_addr_t per_address;
	u32 watermark_level;
	struct dma_chan chan;
	spinlock_t lock;
	struct dma_async_tx_descriptor desc;
	dma_cookie_t last_completed;
	enum dma_status status;
	int dma_request;
	struct scatterlist *sg_list;
	};

	#define MAX_DMA_CHANNELS 8

	struct imxdma_engine {
	struct device *dev;
	struct device_dma_parameters dma_parms;
	struct dma_device dma_device;
	struct imxdma_channel channel[MAX_DMA_CHANNELS];
	};

	static struct imxdma_channel to_imxdma_chan(struct dma_chan chan)
	{
	return container_of(chan, struct imxdma_channel, chan);
	}

	static void imxdma_handle(struct imxdma_channel *imxdmac)
	{
	if (imxdmac->desc.callback)
	imxdmac->desc.callback(imxdmac->desc.callback_param);
	imxdmac->last_completed = imxdmac->desc.cookie;
	}

	static void imxdma_irq_handler(int channel, void *data)
	{
	struct imxdma_channel *imxdmac = data;

	imxdmac->status = DMA_SUCCESS;
	imxdma_handle(imxdmac);
	}

	static void imxdma_err_handler(int channel, void *data, int error)
	{
	struct imxdma_channel *imxdmac = data;

	imxdmac->status = DMA_ERROR;
	imxdma_handle(imxdmac);
	}

	static void imxdma_progression(int channel, void *data,
	struct scatterlist *sg)
	{
	struct imxdma_channel *imxdmac = data;

	imxdmac->status = DMA_SUCCESS;
	imxdma_handle(imxdmac);
	}

	static int imxdma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
	unsigned long arg)
	{
	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
	struct dma_slave_config dmaengine_cfg = (void )arg;
	int ret;
	unsigned int mode = 0;

	switch (cmd) {
	case DMA_TERMINATE_ALL:
	imxdmac->status = DMA_ERROR;
	imx_dma_disable(imxdmac->imxdma_channel);
	return 0;
	case DMA_SLAVE_CONFIG:
	if (dmaengine_cfg->direction == DMA_FROM_DEVICE) {
	imxdmac->per_address = dmaengine_cfg->src_addr;
	imxdmac->watermark_level = dmaengine_cfg->src_maxburst;
	imxdmac->word_size = dmaengine_cfg->src_addr_width;
	} else {
	imxdmac->per_address = dmaengine_cfg->dst_addr;
	imxdmac->watermark_level = dmaengine_cfg->dst_maxburst;
	imxdmac->word_size = dmaengine_cfg->dst_addr_width;
	}

	switch (imxdmac->word_size) {
	case DMA_SLAVE_BUSWIDTH_1_BYTE:
	mode = IMX_DMA_MEMSIZE_8;
	break;
	case DMA_SLAVE_BUSWIDTH_2_BYTES:
	mode = IMX_DMA_MEMSIZE_16;
	break;
	default:
	case DMA_SLAVE_BUSWIDTH_4_BYTES:
	mode = IMX_DMA_MEMSIZE_32;
	break;
	}
	ret = imx_dma_config_channel(imxdmac->imxdma_channel,
	mode \| IMX_DMA_TYPE_FIFO,
	IMX_DMA_MEMSIZE_32 \| IMX_DMA_TYPE_LINEAR,
	imxdmac->dma_request, 1);

	if (ret)
	return ret;

	imx_dma_config_burstlen(imxdmac->imxdma_channel,
	imxdmac->watermark_level * imxdmac->word_size);

	return 0;
	default:
	return -ENOSYS;
	}

	return -EINVAL;
	}

	static enum dma_status imxdma_tx_status(struct dma_chan *chan,
	dma_cookie_t cookie,
	struct dma_tx_state *txstate)
	{
	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
	dma_cookie_t last_used;
	enum dma_status ret;

	last_used = chan->cookie;

	ret = dma_async_is_complete(cookie, imxdmac->last_completed, last_used);
	dma_set_tx_state(txstate, imxdmac->last_completed, last_used, 0);

	return ret;
	}

	static dma_cookie_t imxdma_assign_cookie(struct imxdma_channel *imxdma)
	{
	dma_cookie_t cookie = imxdma->chan.cookie;

	if (++cookie < 0)
	cookie = 1;

	imxdma->chan.cookie = cookie;
	imxdma->desc.cookie = cookie;

	return cookie;
	}

	static dma_cookie_t imxdma_tx_submit(struct dma_async_tx_descriptor *tx)
	{
	struct imxdma_channel *imxdmac = to_imxdma_chan(tx->chan);
	dma_cookie_t cookie;

	spin_lock_irq(&imxdmac->lock);

	cookie = imxdma_assign_cookie(imxdmac);

	imx_dma_enable(imxdmac->imxdma_channel);

	spin_unlock_irq(&imxdmac->lock);

	return cookie;
	}

	static int imxdma_alloc_chan_resources(struct dma_chan *chan)
	{
	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
	struct imx_dma_data *data = chan->private;

	imxdmac->dma_request = data->dma_request;

	dma_async_tx_descriptor_init(&imxdmac->desc, chan);
	imxdmac->desc.tx_submit = imxdma_tx_submit;
	/* txd.flags will be overwritten in prep funcs */
	imxdmac->desc.flags = DMA_CTRL_ACK;

	imxdmac->status = DMA_SUCCESS;

	return 0;
	}

	static void imxdma_free_chan_resources(struct dma_chan *chan)
	{
	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);

	imx_dma_disable(imxdmac->imxdma_channel);

	if (imxdmac->sg_list) {
	kfree(imxdmac->sg_list);
	imxdmac->sg_list = NULL;
	}
	}

	static struct dma_async_tx_descriptor *imxdma_prep_slave_sg(
	struct dma_chan chan, struct scatterlist sgl,
	unsigned int sg_len, enum dma_data_direction direction,
	unsigned long flags)
	{
	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
	struct scatterlist *sg;
	int i, ret, dma_length = 0;
	unsigned int dmamode;

	if (imxdmac->status == DMA_IN_PROGRESS)
	return NULL;

	imxdmac->status = DMA_IN_PROGRESS;

	for_each_sg(sgl, sg, sg_len, i) {
	dma_length += sg->length;
	}

	if (direction == DMA_FROM_DEVICE)
	dmamode = DMA_MODE_READ;
	else
	dmamode = DMA_MODE_WRITE;

	switch (imxdmac->word_size) {
	case DMA_SLAVE_BUSWIDTH_4_BYTES:
	if (sgl->length & 3 \|\| sgl->dma_address & 3)
	return NULL;
	break;
	case DMA_SLAVE_BUSWIDTH_2_BYTES:
	if (sgl->length & 1 \|\| sgl->dma_address & 1)
	return NULL;
	break;
	case DMA_SLAVE_BUSWIDTH_1_BYTE:
	break;
	default:
	return NULL;
	}

	ret = imx_dma_setup_sg(imxdmac->imxdma_channel, sgl, sg_len,
	dma_length, imxdmac->per_address, dmamode);
	if (ret)
	return NULL;

	return &imxdmac->desc;
	}

	static struct dma_async_tx_descriptor *imxdma_prep_dma_cyclic(
	struct dma_chan *chan, dma_addr_t dma_addr, size_t buf_len,
	size_t period_len, enum dma_data_direction direction)
	{
	struct imxdma_channel *imxdmac = to_imxdma_chan(chan);
	struct imxdma_engine *imxdma = imxdmac->imxdma;
	int i, ret;
	unsigned int periods = buf_len / period_len;
	unsigned int dmamode;

	dev_dbg(imxdma->dev, "%s channel: %d buf_len=%d period_len=%d\n",
	__func__, imxdmac->channel, buf_len, period_len);

	if (imxdmac->status == DMA_IN_PROGRESS)
	return NULL;
	imxdmac->status = DMA_IN_PROGRESS;

	ret = imx_dma_setup_progression_handler(imxdmac->imxdma_channel,
	imxdma_progression);
	if (ret) {
	dev_err(imxdma->dev, "Failed to setup the DMA handler\n");
	return NULL;
	}

	if (imxdmac->sg_list)
	kfree(imxdmac->sg_list);

	imxdmac->sg_list = kcalloc(periods + 1,
	sizeof(struct scatterlist), GFP_KERNEL);
	if (!imxdmac->sg_list)
	return NULL;

	sg_init_table(imxdmac->sg_list, periods);

	for (i = 0; i < periods; i++) {
	imxdmac->sg_list[i].page_link = 0;
	imxdmac->sg_list[i].offset = 0;
	imxdmac->sg_list[i].dma_address = dma_addr;
	imxdmac->sg_list[i].length = period_len;
	dma_addr += period_len;
	}

	/* close the loop */
	imxdmac->sg_list[periods].offset = 0;
	imxdmac->sg_list[periods].length = 0;
	imxdmac->sg_list[periods].page_link =
	((unsigned long)imxdmac->sg_list \| 0x01) & ~0x02;

	if (direction == DMA_FROM_DEVICE)
	dmamode = DMA_MODE_READ;
	else
	dmamode = DMA_MODE_WRITE;

	ret = imx_dma_setup_sg(imxdmac->imxdma_channel, imxdmac->sg_list, periods,
	IMX_DMA_LENGTH_LOOP, imxdmac->per_address, dmamode);
	if (ret)
	return NULL;

	return &imxdmac->desc;
	}

	static void imxdma_issue_pending(struct dma_chan *chan)
	{
	/*
	* Nothing to do. We only have a single descriptor
	*/
	}

	static int __init imxdma_probe(struct platform_device *pdev)
	{
	struct imxdma_engine *imxdma;
	int ret, i;

	imxdma = kzalloc(sizeof(*imxdma), GFP_KERNEL);
	if (!imxdma)
	return -ENOMEM;

	INIT_LIST_HEAD(&imxdma->dma_device.channels);

	dma_cap_set(DMA_SLAVE, imxdma->dma_device.cap_mask);
	dma_cap_set(DMA_CYCLIC, imxdma->dma_device.cap_mask);

	/* Initialize channel parameters */
	for (i = 0; i < MAX_DMA_CHANNELS; i++) {
	struct imxdma_channel *imxdmac = &imxdma->channel[i];

	imxdmac->imxdma_channel = imx_dma_request_by_prio("dmaengine",
	DMA_PRIO_MEDIUM);
	if ((int)imxdmac->channel < 0) {
	ret = -ENODEV;
	goto err_init;
	}

	imx_dma_setup_handlers(imxdmac->imxdma_channel,
	imxdma_irq_handler, imxdma_err_handler, imxdmac);

	imxdmac->imxdma = imxdma;
	spin_lock_init(&imxdmac->lock);

	imxdmac->chan.device = &imxdma->dma_device;
	imxdmac->channel = i;

	/* Add the channel to the DMAC list */
	list_add_tail(&imxdmac->chan.device_node, &imxdma->dma_device.channels);
	}

	imxdma->dev = &pdev->dev;
	imxdma->dma_device.dev = &pdev->dev;

	imxdma->dma_device.device_alloc_chan_resources = imxdma_alloc_chan_resources;
	imxdma->dma_device.device_free_chan_resources = imxdma_free_chan_resources;
	imxdma->dma_device.device_tx_status = imxdma_tx_status;
	imxdma->dma_device.device_prep_slave_sg = imxdma_prep_slave_sg;
	imxdma->dma_device.device_prep_dma_cyclic = imxdma_prep_dma_cyclic;
	imxdma->dma_device.device_control = imxdma_control;
	imxdma->dma_device.device_issue_pending = imxdma_issue_pending;

	platform_set_drvdata(pdev, imxdma);

	imxdma->dma_device.dev->dma_parms = &imxdma->dma_parms;
	dma_set_max_seg_size(imxdma->dma_device.dev, 0xffffff);

	ret = dma_async_device_register(&imxdma->dma_device);
	if (ret) {
	dev_err(&pdev->dev, "unable to register\n");
	goto err_init;
	}

	return 0;

	err_init:
	while (--i >= 0) {
	struct imxdma_channel *imxdmac = &imxdma->channel[i];
	imx_dma_free(imxdmac->imxdma_channel);
	}

	kfree(imxdma);
	return ret;
	}

	static int __exit imxdma_remove(struct platform_device *pdev)
	{
	struct imxdma_engine *imxdma = platform_get_drvdata(pdev);
	int i;

	dma_async_device_unregister(&imxdma->dma_device);

	for (i = 0; i < MAX_DMA_CHANNELS; i++) {
	struct imxdma_channel *imxdmac = &imxdma->channel[i];

	imx_dma_free(imxdmac->imxdma_channel);
	}

	kfree(imxdma);

	return 0;
	}

	static struct platform_driver imxdma_driver = {
	.driver = {
	.name = "imx-dma",
	},
	.remove = __exit_p(imxdma_remove),
	};

	static int __init imxdma_module_init(void)
	{
	return platform_driver_probe(&imxdma_driver, imxdma_probe);
	}
	subsys_initcall(imxdma_module_init);

	MODULE_AUTHOR("Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>");
	MODULE_DESCRIPTION("i.MX dma driver");
	MODULE_LICENSE("GPL");