sound/soc/fsl/fsl_asrc_dma.c - kernel/bruno - Git at Google

 /*
  * Freescale ASRC ALSA SoC Platform (DMA) driver
  *
  * Copyright (C) 2014 Freescale Semiconductor, Inc.
  *
  * Author: Nicolin Chen <nicoleotsuka@gmail.com>
  *
  * This file is licensed under the terms of the GNU General Public License
  * version 2. This program is licensed "as is" without any warranty of any
  * kind, whether express or implied.
  */

 #include <linux/dma-mapping.h>
 #include <linux/module.h>
 #include <linux/platform_data/dma-imx.h>
 #include <sound/dmaengine_pcm.h>
 #include <sound/pcm_params.h>

 #include "fsl_asrc.h"

 #define FSL_ASRC_DMABUF_SIZE	(256 * 1024)

 static struct snd_pcm_hardware snd_imx_hardware = {
 	.info = SNDRV_PCM_INFO_INTERLEAVED |
 		SNDRV_PCM_INFO_BLOCK_TRANSFER |
 		SNDRV_PCM_INFO_MMAP |
 		SNDRV_PCM_INFO_MMAP_VALID |
 		SNDRV_PCM_INFO_PAUSE |
 		SNDRV_PCM_INFO_RESUME,
 	.buffer_bytes_max = FSL_ASRC_DMABUF_SIZE,
 	.period_bytes_min = 128,
 	.period_bytes_max = 65535, /* Limited by SDMA engine */
 	.periods_min = 2,
 	.periods_max = 255,
 	.fifo_size = 0,
 };

 static bool filter(struct dma_chan *chan, void *param)
 {
 	if (!imx_dma_is_general_purpose(chan))
 		return false;

 	chan->private = param;

 	return true;
 }

 static void fsl_asrc_dma_complete(void *arg)
 {
 	struct snd_pcm_substream *substream = arg;
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct fsl_asrc_pair *pair = runtime->private_data;

 	pair->pos += snd_pcm_lib_period_bytes(substream);
 	if (pair->pos >= snd_pcm_lib_buffer_bytes(substream))
 		pair->pos = 0;

 	snd_pcm_period_elapsed(substream);
 }

 static int fsl_asrc_dma_prepare_and_submit(struct snd_pcm_substream *substream)
 {
 	u8 dir = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? OUT : IN;
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct fsl_asrc_pair *pair = runtime->private_data;
 	struct device *dev = rtd->platform->dev;
 	unsigned long flags = DMA_CTRL_ACK;

 	/* Prepare and submit Front-End DMA channel */
 	if (!substream->runtime->no_period_wakeup)
 		flags |= DMA_PREP_INTERRUPT;

 	pair->pos = 0;
 	pair->desc[!dir] = dmaengine_prep_dma_cyclic(
 			pair->dma_chan[!dir], runtime->dma_addr,
 			snd_pcm_lib_buffer_bytes(substream),
 			snd_pcm_lib_period_bytes(substream),
 			dir == OUT ? DMA_TO_DEVICE : DMA_FROM_DEVICE, flags);
 	if (!pair->desc[!dir]) {
 		dev_err(dev, "failed to prepare slave DMA for Front-End\n");
 		return -ENOMEM;
 	}

 	pair->desc[!dir]->callback = fsl_asrc_dma_complete;
 	pair->desc[!dir]->callback_param = substream;

 	dmaengine_submit(pair->desc[!dir]);

 	/* Prepare and submit Back-End DMA channel */
 	pair->desc[dir] = dmaengine_prep_dma_cyclic(
 			pair->dma_chan[dir], 0xffff, 64, 64, DMA_DEV_TO_DEV, 0);
 	if (!pair->desc[dir]) {
 		dev_err(dev, "failed to prepare slave DMA for Back-End\n");
 		return -ENOMEM;
 	}

 	dmaengine_submit(pair->desc[dir]);

 	return 0;
 }

 static int fsl_asrc_dma_trigger(struct snd_pcm_substream *substream, int cmd)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct fsl_asrc_pair *pair = runtime->private_data;
 	int ret;

 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_RESUME:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 		ret = fsl_asrc_dma_prepare_and_submit(substream);
 		if (ret)
 			return ret;
 		dma_async_issue_pending(pair->dma_chan[IN]);
 		dma_async_issue_pending(pair->dma_chan[OUT]);
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
 	case SNDRV_PCM_TRIGGER_SUSPEND:
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 		dmaengine_terminate_all(pair->dma_chan[OUT]);
 		dmaengine_terminate_all(pair->dma_chan[IN]);
 		break;
 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 static int fsl_asrc_dma_hw_params(struct snd_pcm_substream *substream,
 				  struct snd_pcm_hw_params *params)
 {
 	enum dma_slave_buswidth buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
 	struct snd_dmaengine_dai_dma_data *dma_params_fe = NULL;
 	struct snd_dmaengine_dai_dma_data *dma_params_be = NULL;
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct fsl_asrc_pair *pair = runtime->private_data;
 	struct fsl_asrc *asrc_priv = pair->asrc_priv;
 	struct dma_slave_config config_fe, config_be;
 	enum asrc_pair_index index = pair->index;
 	struct device *dev = rtd->platform->dev;
 	int stream = substream->stream;
 	struct imx_dma_data *tmp_data;
 	struct snd_soc_dpcm *dpcm;
 	struct dma_chan *tmp_chan;
 	struct device *dev_be;
 	u8 dir = tx ? OUT : IN;
 	dma_cap_mask_t mask;
 	int ret;

 	/* Fetch the Back-End dma_data from DPCM */
 	list_for_each_entry(dpcm, &rtd->dpcm[stream].be_clients, list_be) {
 		struct snd_soc_pcm_runtime *be = dpcm->be;
 		struct snd_pcm_substream *substream_be;
 		struct snd_soc_dai *dai = be->cpu_dai;

 		if (dpcm->fe != rtd)
 			continue;

 		substream_be = snd_soc_dpcm_get_substream(be, stream);
 		dma_params_be = snd_soc_dai_get_dma_data(dai, substream_be);
 		dev_be = dai->dev;
 		break;
 	}

 	if (!dma_params_be) {
 		dev_err(dev, "failed to get the substream of Back-End\n");
 		return -EINVAL;
 	}

 	/* Override dma_data of the Front-End and config its dmaengine */
 	dma_params_fe = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
 	dma_params_fe->addr = asrc_priv->paddr + REG_ASRDx(!dir, index);
 	dma_params_fe->maxburst = dma_params_be->maxburst;

 	pair->dma_chan[!dir] = fsl_asrc_get_dma_channel(pair, !dir);
 	if (!pair->dma_chan[!dir]) {
 		dev_err(dev, "failed to request DMA channel\n");
 		return -EINVAL;
 	}

 	memset(&config_fe, 0, sizeof(config_fe));
 	ret = snd_dmaengine_pcm_prepare_slave_config(substream, params, &config_fe);
 	if (ret) {
 		dev_err(dev, "failed to prepare DMA config for Front-End\n");
 		return ret;
 	}

 	ret = dmaengine_slave_config(pair->dma_chan[!dir], &config_fe);
 	if (ret) {
 		dev_err(dev, "failed to config DMA channel for Front-End\n");
 		return ret;
 	}

 	/* Request and config DMA channel for Back-End */
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
 	dma_cap_set(DMA_CYCLIC, mask);

 	/* Get DMA request of Back-End */
 	tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
 	tmp_data = tmp_chan->private;
 	pair->dma_data.dma_request = tmp_data->dma_request;
 	dma_release_channel(tmp_chan);

 	/* Get DMA request of Front-End */
 	tmp_chan = fsl_asrc_get_dma_channel(pair, dir);
 	tmp_data = tmp_chan->private;
 	pair->dma_data.dma_request2 = tmp_data->dma_request;
 	pair->dma_data.peripheral_type = tmp_data->peripheral_type;
 	pair->dma_data.priority = tmp_data->priority;
 	dma_release_channel(tmp_chan);

 	pair->dma_chan[dir] = dma_request_channel(mask, filter, &pair->dma_data);
 	if (!pair->dma_chan[dir]) {
 		dev_err(dev, "failed to request DMA channel for Back-End\n");
 		return -EINVAL;
 	}

 	if (asrc_priv->asrc_width == 16)
 		buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
 	else
 		buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;

 	config_be.direction = DMA_DEV_TO_DEV;
 	config_be.src_addr_width = buswidth;
 	config_be.src_maxburst = dma_params_be->maxburst;
 	config_be.dst_addr_width = buswidth;
 	config_be.dst_maxburst = dma_params_be->maxburst;

 	if (tx) {
 		config_be.src_addr = asrc_priv->paddr + REG_ASRDO(index);
 		config_be.dst_addr = dma_params_be->addr;
 	} else {
 		config_be.dst_addr = asrc_priv->paddr + REG_ASRDI(index);
 		config_be.src_addr = dma_params_be->addr;
 	}

 	ret = dmaengine_slave_config(pair->dma_chan[dir], &config_be);
 	if (ret) {
 		dev_err(dev, "failed to config DMA channel for Back-End\n");
 		return ret;
 	}

 	snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);

 	return 0;
 }

 static int fsl_asrc_dma_hw_free(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct fsl_asrc_pair *pair = runtime->private_data;

 	snd_pcm_set_runtime_buffer(substream, NULL);

 	if (pair->dma_chan[IN])
 		dma_release_channel(pair->dma_chan[IN]);

 	if (pair->dma_chan[OUT])
 		dma_release_channel(pair->dma_chan[OUT]);

 	pair->dma_chan[IN] = NULL;
 	pair->dma_chan[OUT] = NULL;

 	return 0;
 }

 static int fsl_asrc_dma_startup(struct snd_pcm_substream *substream)
 {
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct device *dev = rtd->platform->dev;
 	struct fsl_asrc *asrc_priv = dev_get_drvdata(dev);
 	struct fsl_asrc_pair *pair;

 	pair = kzalloc(sizeof(struct fsl_asrc_pair), GFP_KERNEL);
 	if (!pair) {
 		dev_err(dev, "failed to allocate pair\n");
 		return -ENOMEM;
 	}

 	pair->asrc_priv = asrc_priv;

 	runtime->private_data = pair;

 	snd_pcm_hw_constraint_integer(substream->runtime,
 				      SNDRV_PCM_HW_PARAM_PERIODS);
 	snd_soc_set_runtime_hwparams(substream, &snd_imx_hardware);

 	return 0;
 }

 static int fsl_asrc_dma_shutdown(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct fsl_asrc_pair *pair = runtime->private_data;
 	struct fsl_asrc *asrc_priv;

 	if (!pair)
 		return 0;

 	asrc_priv = pair->asrc_priv;

 	if (asrc_priv->pair[pair->index] == pair)
 		asrc_priv->pair[pair->index] = NULL;

 	kfree(pair);

 	return 0;
 }

 static snd_pcm_uframes_t fsl_asrc_dma_pcm_pointer(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct fsl_asrc_pair *pair = runtime->private_data;

 	return bytes_to_frames(substream->runtime, pair->pos);
 }

 static struct snd_pcm_ops fsl_asrc_dma_pcm_ops = {
 	.ioctl		= snd_pcm_lib_ioctl,
 	.hw_params	= fsl_asrc_dma_hw_params,
 	.hw_free	= fsl_asrc_dma_hw_free,
 	.trigger	= fsl_asrc_dma_trigger,
 	.open		= fsl_asrc_dma_startup,
 	.close		= fsl_asrc_dma_shutdown,
 	.pointer	= fsl_asrc_dma_pcm_pointer,
 };

 static int fsl_asrc_dma_pcm_new(struct snd_soc_pcm_runtime *rtd)
 {
 	struct snd_card *card = rtd->card->snd_card;
 	struct snd_pcm_substream *substream;
 	struct snd_pcm *pcm = rtd->pcm;
 	int ret, i;

 	ret = dma_coerce_mask_and_coherent(card->dev, DMA_BIT_MASK(32));
 	if (ret) {
 		dev_err(card->dev, "failed to set DMA mask\n");
 		return ret;
 	}

 	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_LAST; i++) {
 		substream = pcm->streams[i].substream;
 		if (!substream)
 			continue;

 		ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, pcm->card->dev,
 				FSL_ASRC_DMABUF_SIZE, &substream->dma_buffer);
 		if (ret) {
 			dev_err(card->dev, "failed to allocate DMA buffer\n");
 			goto err;
 		}
 	}

 	return 0;

 err:
 	if (--i == 0 && pcm->streams[i].substream)
 		snd_dma_free_pages(&pcm->streams[i].substream->dma_buffer);

 	return ret;
 }

 static void fsl_asrc_dma_pcm_free(struct snd_pcm *pcm)
 {
 	struct snd_pcm_substream *substream;
 	int i;

 	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_LAST; i++) {
 		substream = pcm->streams[i].substream;
 		if (!substream)
 			continue;

 		snd_dma_free_pages(&substream->dma_buffer);
 		substream->dma_buffer.area = NULL;
 		substream->dma_buffer.addr = 0;
 	}
 }

 struct snd_soc_platform_driver fsl_asrc_platform = {
 	.ops		= &fsl_asrc_dma_pcm_ops,
 	.pcm_new	= fsl_asrc_dma_pcm_new,
 	.pcm_free	= fsl_asrc_dma_pcm_free,
 };
 EXPORT_SYMBOL_GPL(fsl_asrc_platform);
	/*
	* Freescale ASRC ALSA SoC Platform (DMA) driver
	*
	* Copyright (C) 2014 Freescale Semiconductor, Inc.
	*
	* Author: Nicolin Chen <nicoleotsuka@gmail.com>
	*
	* This file is licensed under the terms of the GNU General Public License
	* version 2. This program is licensed "as is" without any warranty of any
	* kind, whether express or implied.
	*/

	#include <linux/dma-mapping.h>
	#include <linux/module.h>
	#include <linux/platform_data/dma-imx.h>
	#include <sound/dmaengine_pcm.h>
	#include <sound/pcm_params.h>

	#include "fsl_asrc.h"

	#define FSL_ASRC_DMABUF_SIZE (256 * 1024)

	static struct snd_pcm_hardware snd_imx_hardware = {
	.info = SNDRV_PCM_INFO_INTERLEAVED \|
	SNDRV_PCM_INFO_BLOCK_TRANSFER \|
	SNDRV_PCM_INFO_MMAP \|
	SNDRV_PCM_INFO_MMAP_VALID \|
	SNDRV_PCM_INFO_PAUSE \|
	SNDRV_PCM_INFO_RESUME,
	.buffer_bytes_max = FSL_ASRC_DMABUF_SIZE,
	.period_bytes_min = 128,
	.period_bytes_max = 65535, /* Limited by SDMA engine */
	.periods_min = 2,
	.periods_max = 255,
	.fifo_size = 0,
	};

	static bool filter(struct dma_chan chan, void param)
	{
	if (!imx_dma_is_general_purpose(chan))
	return false;

	chan->private = param;

	return true;
	}

	static void fsl_asrc_dma_complete(void *arg)
	{
	struct snd_pcm_substream *substream = arg;
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct fsl_asrc_pair *pair = runtime->private_data;

	pair->pos += snd_pcm_lib_period_bytes(substream);
	if (pair->pos >= snd_pcm_lib_buffer_bytes(substream))
	pair->pos = 0;

	snd_pcm_period_elapsed(substream);
	}

	static int fsl_asrc_dma_prepare_and_submit(struct snd_pcm_substream *substream)
	{
	u8 dir = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? OUT : IN;
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct fsl_asrc_pair *pair = runtime->private_data;
	struct device *dev = rtd->platform->dev;
	unsigned long flags = DMA_CTRL_ACK;

	/* Prepare and submit Front-End DMA channel */
	if (!substream->runtime->no_period_wakeup)
	flags \|= DMA_PREP_INTERRUPT;

	pair->pos = 0;
	pair->desc[!dir] = dmaengine_prep_dma_cyclic(
	pair->dma_chan[!dir], runtime->dma_addr,
	snd_pcm_lib_buffer_bytes(substream),
	snd_pcm_lib_period_bytes(substream),
	dir == OUT ? DMA_TO_DEVICE : DMA_FROM_DEVICE, flags);
	if (!pair->desc[!dir]) {
	dev_err(dev, "failed to prepare slave DMA for Front-End\n");
	return -ENOMEM;
	}

	pair->desc[!dir]->callback = fsl_asrc_dma_complete;
	pair->desc[!dir]->callback_param = substream;

	dmaengine_submit(pair->desc[!dir]);

	/* Prepare and submit Back-End DMA channel */
	pair->desc[dir] = dmaengine_prep_dma_cyclic(
	pair->dma_chan[dir], 0xffff, 64, 64, DMA_DEV_TO_DEV, 0);
	if (!pair->desc[dir]) {
	dev_err(dev, "failed to prepare slave DMA for Back-End\n");
	return -ENOMEM;
	}

	dmaengine_submit(pair->desc[dir]);

	return 0;
	}

	static int fsl_asrc_dma_trigger(struct snd_pcm_substream *substream, int cmd)
	{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct fsl_asrc_pair *pair = runtime->private_data;
	int ret;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	case SNDRV_PCM_TRIGGER_RESUME:
	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
	ret = fsl_asrc_dma_prepare_and_submit(substream);
	if (ret)
	return ret;
	dma_async_issue_pending(pair->dma_chan[IN]);
	dma_async_issue_pending(pair->dma_chan[OUT]);
	break;
	case SNDRV_PCM_TRIGGER_STOP:
	case SNDRV_PCM_TRIGGER_SUSPEND:
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
	dmaengine_terminate_all(pair->dma_chan[OUT]);
	dmaengine_terminate_all(pair->dma_chan[IN]);
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}

	static int fsl_asrc_dma_hw_params(struct snd_pcm_substream *substream,
	struct snd_pcm_hw_params *params)
	{
	enum dma_slave_buswidth buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
	struct snd_dmaengine_dai_dma_data *dma_params_fe = NULL;
	struct snd_dmaengine_dai_dma_data *dma_params_be = NULL;
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct fsl_asrc_pair *pair = runtime->private_data;
	struct fsl_asrc *asrc_priv = pair->asrc_priv;
	struct dma_slave_config config_fe, config_be;
	enum asrc_pair_index index = pair->index;
	struct device *dev = rtd->platform->dev;
	int stream = substream->stream;
	struct imx_dma_data *tmp_data;
	struct snd_soc_dpcm *dpcm;
	struct dma_chan *tmp_chan;
	struct device *dev_be;
	u8 dir = tx ? OUT : IN;
	dma_cap_mask_t mask;
	int ret;

	/* Fetch the Back-End dma_data from DPCM */
	list_for_each_entry(dpcm, &rtd->dpcm[stream].be_clients, list_be) {
	struct snd_soc_pcm_runtime *be = dpcm->be;
	struct snd_pcm_substream *substream_be;
	struct snd_soc_dai *dai = be->cpu_dai;

	if (dpcm->fe != rtd)
	continue;

	substream_be = snd_soc_dpcm_get_substream(be, stream);
	dma_params_be = snd_soc_dai_get_dma_data(dai, substream_be);
	dev_be = dai->dev;
	break;
	}

	if (!dma_params_be) {
	dev_err(dev, "failed to get the substream of Back-End\n");
	return -EINVAL;
	}

	/* Override dma_data of the Front-End and config its dmaengine */
	dma_params_fe = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
	dma_params_fe->addr = asrc_priv->paddr + REG_ASRDx(!dir, index);
	dma_params_fe->maxburst = dma_params_be->maxburst;

	pair->dma_chan[!dir] = fsl_asrc_get_dma_channel(pair, !dir);
	if (!pair->dma_chan[!dir]) {
	dev_err(dev, "failed to request DMA channel\n");
	return -EINVAL;
	}

	memset(&config_fe, 0, sizeof(config_fe));
	ret = snd_dmaengine_pcm_prepare_slave_config(substream, params, &config_fe);
	if (ret) {
	dev_err(dev, "failed to prepare DMA config for Front-End\n");
	return ret;
	}

	ret = dmaengine_slave_config(pair->dma_chan[!dir], &config_fe);
	if (ret) {
	dev_err(dev, "failed to config DMA channel for Front-End\n");
	return ret;
	}

	/* Request and config DMA channel for Back-End */
	dma_cap_zero(mask);
	dma_cap_set(DMA_SLAVE, mask);
	dma_cap_set(DMA_CYCLIC, mask);

	/* Get DMA request of Back-End */
	tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
	tmp_data = tmp_chan->private;
	pair->dma_data.dma_request = tmp_data->dma_request;
	dma_release_channel(tmp_chan);

	/* Get DMA request of Front-End */
	tmp_chan = fsl_asrc_get_dma_channel(pair, dir);
	tmp_data = tmp_chan->private;
	pair->dma_data.dma_request2 = tmp_data->dma_request;
	pair->dma_data.peripheral_type = tmp_data->peripheral_type;
	pair->dma_data.priority = tmp_data->priority;
	dma_release_channel(tmp_chan);

	pair->dma_chan[dir] = dma_request_channel(mask, filter, &pair->dma_data);
	if (!pair->dma_chan[dir]) {
	dev_err(dev, "failed to request DMA channel for Back-End\n");
	return -EINVAL;
	}

	if (asrc_priv->asrc_width == 16)
	buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
	else
	buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;

	config_be.direction = DMA_DEV_TO_DEV;
	config_be.src_addr_width = buswidth;
	config_be.src_maxburst = dma_params_be->maxburst;
	config_be.dst_addr_width = buswidth;
	config_be.dst_maxburst = dma_params_be->maxburst;

	if (tx) {
	config_be.src_addr = asrc_priv->paddr + REG_ASRDO(index);
	config_be.dst_addr = dma_params_be->addr;
	} else {
	config_be.dst_addr = asrc_priv->paddr + REG_ASRDI(index);
	config_be.src_addr = dma_params_be->addr;
	}

	ret = dmaengine_slave_config(pair->dma_chan[dir], &config_be);
	if (ret) {
	dev_err(dev, "failed to config DMA channel for Back-End\n");
	return ret;
	}

	snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);

	return 0;
	}

	static int fsl_asrc_dma_hw_free(struct snd_pcm_substream *substream)
	{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct fsl_asrc_pair *pair = runtime->private_data;

	snd_pcm_set_runtime_buffer(substream, NULL);

	if (pair->dma_chan[IN])
	dma_release_channel(pair->dma_chan[IN]);

	if (pair->dma_chan[OUT])
	dma_release_channel(pair->dma_chan[OUT]);

	pair->dma_chan[IN] = NULL;
	pair->dma_chan[OUT] = NULL;

	return 0;
	}

	static int fsl_asrc_dma_startup(struct snd_pcm_substream *substream)
	{
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct device *dev = rtd->platform->dev;
	struct fsl_asrc *asrc_priv = dev_get_drvdata(dev);
	struct fsl_asrc_pair *pair;

	pair = kzalloc(sizeof(struct fsl_asrc_pair), GFP_KERNEL);
	if (!pair) {
	dev_err(dev, "failed to allocate pair\n");
	return -ENOMEM;
	}

	pair->asrc_priv = asrc_priv;

	runtime->private_data = pair;

	snd_pcm_hw_constraint_integer(substream->runtime,
	SNDRV_PCM_HW_PARAM_PERIODS);
	snd_soc_set_runtime_hwparams(substream, &snd_imx_hardware);

	return 0;
	}

	static int fsl_asrc_dma_shutdown(struct snd_pcm_substream *substream)
	{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct fsl_asrc_pair *pair = runtime->private_data;
	struct fsl_asrc *asrc_priv;

	if (!pair)
	return 0;

	asrc_priv = pair->asrc_priv;

	if (asrc_priv->pair[pair->index] == pair)
	asrc_priv->pair[pair->index] = NULL;

	kfree(pair);

	return 0;
	}

	static snd_pcm_uframes_t fsl_asrc_dma_pcm_pointer(struct snd_pcm_substream *substream)
	{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct fsl_asrc_pair *pair = runtime->private_data;

	return bytes_to_frames(substream->runtime, pair->pos);
	}

	static struct snd_pcm_ops fsl_asrc_dma_pcm_ops = {
	.ioctl = snd_pcm_lib_ioctl,
	.hw_params = fsl_asrc_dma_hw_params,
	.hw_free = fsl_asrc_dma_hw_free,
	.trigger = fsl_asrc_dma_trigger,
	.open = fsl_asrc_dma_startup,
	.close = fsl_asrc_dma_shutdown,
	.pointer = fsl_asrc_dma_pcm_pointer,
	};

	static int fsl_asrc_dma_pcm_new(struct snd_soc_pcm_runtime *rtd)
	{
	struct snd_card *card = rtd->card->snd_card;
	struct snd_pcm_substream *substream;
	struct snd_pcm *pcm = rtd->pcm;
	int ret, i;

	ret = dma_coerce_mask_and_coherent(card->dev, DMA_BIT_MASK(32));
	if (ret) {
	dev_err(card->dev, "failed to set DMA mask\n");
	return ret;
	}

	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_LAST; i++) {
	substream = pcm->streams[i].substream;
	if (!substream)
	continue;

	ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, pcm->card->dev,
	FSL_ASRC_DMABUF_SIZE, &substream->dma_buffer);
	if (ret) {
	dev_err(card->dev, "failed to allocate DMA buffer\n");
	goto err;
	}
	}

	return 0;

	err:
	if (--i == 0 && pcm->streams[i].substream)
	snd_dma_free_pages(&pcm->streams[i].substream->dma_buffer);

	return ret;
	}

	static void fsl_asrc_dma_pcm_free(struct snd_pcm *pcm)
	{
	struct snd_pcm_substream *substream;
	int i;

	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_LAST; i++) {
	substream = pcm->streams[i].substream;
	if (!substream)
	continue;

	snd_dma_free_pages(&substream->dma_buffer);
	substream->dma_buffer.area = NULL;
	substream->dma_buffer.addr = 0;
	}
	}

	struct snd_soc_platform_driver fsl_asrc_platform = {
	.ops = &fsl_asrc_dma_pcm_ops,
	.pcm_new = fsl_asrc_dma_pcm_new,
	.pcm_free = fsl_asrc_dma_pcm_free,
	};
	EXPORT_SYMBOL_GPL(fsl_asrc_platform);