sound/soc/soc-generic-dmaengine-pcm.c - kernel/msm-4.19 - Gitiles

 /*
  *  Copyright (C) 2013, Analog Devices Inc.
  *	Author: Lars-Peter Clausen <lars@metafoo.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.
  *
  *  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.,
  *  675 Mass Ave, Cambridge, MA 02139, USA.
  *
  */
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/dmaengine.h>
 #include <linux/slab.h>
 #include <sound/pcm.h>
 #include <sound/pcm_params.h>
 #include <sound/soc.h>
 #include <linux/dma-mapping.h>
 #include <linux/of.h>

 #include <sound/dmaengine_pcm.h>

 struct dmaengine_pcm {
 	struct dma_chan *chan[SNDRV_PCM_STREAM_LAST + 1];
 	const struct snd_dmaengine_pcm_config *config;
 	struct snd_soc_platform platform;
 	unsigned int flags;
 };

 static struct dmaengine_pcm *soc_platform_to_pcm(struct snd_soc_platform *p)
 {
 	return container_of(p, struct dmaengine_pcm, platform);
 }

 static struct device *dmaengine_dma_dev(struct dmaengine_pcm *pcm,
 	struct snd_pcm_substream *substream)
 {
 	if (!pcm->chan[substream->stream])
 		return NULL;

 	return pcm->chan[substream->stream]->device->dev;
 }

 /**
  * snd_dmaengine_pcm_prepare_slave_config() - Generic prepare_slave_config callback
  * @substream: PCM substream
  * @params: hw_params
  * @slave_config: DMA slave config to prepare
  *
  * This function can be used as a generic prepare_slave_config callback for
  * platforms which make use of the snd_dmaengine_dai_dma_data struct for their
  * DAI DMA data. Internally the function will first call
  * snd_hwparams_to_dma_slave_config to fill in the slave config based on the
  * hw_params, followed by snd_dmaengine_set_config_from_dai_data to fill in the
  * remaining fields based on the DAI DMA data.
  */
 int snd_dmaengine_pcm_prepare_slave_config(struct snd_pcm_substream *substream,
 	struct snd_pcm_hw_params *params, struct dma_slave_config *slave_config)
 {
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct snd_dmaengine_dai_dma_data *dma_data;
 	int ret;

 	dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);

 	ret = snd_hwparams_to_dma_slave_config(substream, params, slave_config);
 	if (ret)
 		return ret;

 	snd_dmaengine_pcm_set_config_from_dai_data(substream, dma_data,
 		slave_config);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_prepare_slave_config);

 static int dmaengine_pcm_hw_params(struct snd_pcm_substream *substream,
 	struct snd_pcm_hw_params *params)
 {
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
 	struct dma_chan *chan = snd_dmaengine_pcm_get_chan(substream);
 	int (*prepare_slave_config)(struct snd_pcm_substream *substream,
 			struct snd_pcm_hw_params *params,
 			struct dma_slave_config *slave_config);
 	struct dma_slave_config slave_config;
 	int ret;

 	memset(&slave_config, 0, sizeof(slave_config));

 	if (!pcm->config)
 		prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config;
 	else
 		prepare_slave_config = pcm->config->prepare_slave_config;

 	if (prepare_slave_config) {
 		ret = prepare_slave_config(substream, params, &slave_config);
 		if (ret)
 			return ret;

 		ret = dmaengine_slave_config(chan, &slave_config);
 		if (ret)
 			return ret;
 	}

 	return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(params));
 }

 static int dmaengine_pcm_set_runtime_hwparams(struct snd_pcm_substream *substream)
 {
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
 	struct device *dma_dev = dmaengine_dma_dev(pcm, substream);
 	struct dma_chan *chan = pcm->chan[substream->stream];
 	struct snd_dmaengine_dai_dma_data *dma_data;
 	struct dma_slave_caps dma_caps;
 	struct snd_pcm_hardware hw;
 	int ret;

 	if (pcm->config && pcm->config->pcm_hardware)
 		return snd_soc_set_runtime_hwparams(substream,
 				pcm->config->pcm_hardware);

 	dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);

 	memset(&hw, 0, sizeof(hw));
 	hw.info = SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID |
 			SNDRV_PCM_INFO_INTERLEAVED;
 	hw.periods_min = 2;
 	hw.periods_max = UINT_MAX;
 	hw.period_bytes_min = 256;
 	hw.period_bytes_max = dma_get_max_seg_size(dma_dev);
 	hw.buffer_bytes_max = SIZE_MAX;
 	hw.fifo_size = dma_data->fifo_size;

 	ret = dma_get_slave_caps(chan, &dma_caps);
 	if (ret == 0) {
 		if (dma_caps.cmd_pause)
 			hw.info |= SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME;
 	}

 	return snd_soc_set_runtime_hwparams(substream, &hw);
 }

 static int dmaengine_pcm_open(struct snd_pcm_substream *substream)
 {
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
 	struct dma_chan *chan = pcm->chan[substream->stream];
 	int ret;

 	ret = dmaengine_pcm_set_runtime_hwparams(substream);
 	if (ret)
 		return ret;

 	return snd_dmaengine_pcm_open(substream, chan);
 }

 static void dmaengine_pcm_free(struct snd_pcm *pcm)
 {
 	snd_pcm_lib_preallocate_free_for_all(pcm);
 }

 static struct dma_chan *dmaengine_pcm_compat_request_channel(
 	struct snd_soc_pcm_runtime *rtd,
 	struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
 	struct snd_dmaengine_dai_dma_data *dma_data;

 	dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);

 	if ((pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX) && pcm->chan[0])
 		return pcm->chan[0];

 	if (pcm->config->compat_request_channel)
 		return pcm->config->compat_request_channel(rtd, substream);

 	return snd_dmaengine_pcm_request_channel(pcm->config->compat_filter_fn,
 						 dma_data->filter_data);
 }

 static int dmaengine_pcm_new(struct snd_soc_pcm_runtime *rtd)
 {
 	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
 	const struct snd_dmaengine_pcm_config *config = pcm->config;
 	struct device *dev = rtd->platform->dev;
 	struct snd_dmaengine_dai_dma_data *dma_data;
 	struct snd_pcm_substream *substream;
 	size_t prealloc_buffer_size;
 	size_t max_buffer_size;
 	unsigned int i;
 	int ret;

 	if (config && config->prealloc_buffer_size) {
 		prealloc_buffer_size = config->prealloc_buffer_size;
 		max_buffer_size = config->pcm_hardware->buffer_bytes_max;
 	} else {
 		prealloc_buffer_size = 512 * 1024;
 		max_buffer_size = SIZE_MAX;
 	}


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

 		dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);

 		if (!pcm->chan[i] &&
 		    (pcm->flags & SND_DMAENGINE_PCM_FLAG_CUSTOM_CHANNEL_NAME))
 			pcm->chan[i] = dma_request_slave_channel(dev,
 				dma_data->chan_name);

 		if (!pcm->chan[i] && (pcm->flags & SND_DMAENGINE_PCM_FLAG_COMPAT)) {
 			pcm->chan[i] = dmaengine_pcm_compat_request_channel(rtd,
 				substream);
 		}

 		if (!pcm->chan[i]) {
 			dev_err(rtd->platform->dev,
 				"Missing dma channel for stream: %d\n", i);
 			ret = -EINVAL;
 			goto err_free;
 		}

 		ret = snd_pcm_lib_preallocate_pages(substream,
 				SNDRV_DMA_TYPE_DEV,
 				dmaengine_dma_dev(pcm, substream),
 				prealloc_buffer_size,
 				max_buffer_size);
 		if (ret)
 			goto err_free;
 	}

 	return 0;

 err_free:
 	dmaengine_pcm_free(rtd->pcm);
 	return ret;
 }

 static const struct snd_pcm_ops dmaengine_pcm_ops = {
 	.open		= dmaengine_pcm_open,
 	.close		= snd_dmaengine_pcm_close,
 	.ioctl		= snd_pcm_lib_ioctl,
 	.hw_params	= dmaengine_pcm_hw_params,
 	.hw_free	= snd_pcm_lib_free_pages,
 	.trigger	= snd_dmaengine_pcm_trigger,
 	.pointer	= snd_dmaengine_pcm_pointer,
 };

 static const struct snd_soc_platform_driver dmaengine_pcm_platform = {
 	.ops		= &dmaengine_pcm_ops,
 	.pcm_new	= dmaengine_pcm_new,
 	.pcm_free	= dmaengine_pcm_free,
 	.probe_order	= SND_SOC_COMP_ORDER_LATE,
 };

 static const struct snd_pcm_ops dmaengine_no_residue_pcm_ops = {
 	.open		= dmaengine_pcm_open,
 	.close		= snd_dmaengine_pcm_close,
 	.ioctl		= snd_pcm_lib_ioctl,
 	.hw_params	= dmaengine_pcm_hw_params,
 	.hw_free	= snd_pcm_lib_free_pages,
 	.trigger	= snd_dmaengine_pcm_trigger,
 	.pointer	= snd_dmaengine_pcm_pointer_no_residue,
 };

 static const struct snd_soc_platform_driver dmaengine_no_residue_pcm_platform = {
 	.ops		= &dmaengine_no_residue_pcm_ops,
 	.pcm_new	= dmaengine_pcm_new,
 	.pcm_free	= dmaengine_pcm_free,
 	.probe_order	= SND_SOC_COMP_ORDER_LATE,
 };

 static const char * const dmaengine_pcm_dma_channel_names[] = {
 	[SNDRV_PCM_STREAM_PLAYBACK] = "tx",
 	[SNDRV_PCM_STREAM_CAPTURE] = "rx",
 };

 static void dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
 	struct device *dev)
 {
 	unsigned int i;

 	if ((pcm->flags & (SND_DMAENGINE_PCM_FLAG_NO_DT |
 			   SND_DMAENGINE_PCM_FLAG_CUSTOM_CHANNEL_NAME)) ||
 	    !dev->of_node)
 		return;

 	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX) {
 		pcm->chan[0] = dma_request_slave_channel(dev, "rx-tx");
 		pcm->chan[1] = pcm->chan[0];
 	} else {
 		for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
 			pcm->chan[i] = dma_request_slave_channel(dev,
 					dmaengine_pcm_dma_channel_names[i]);
 		}
 	}
 }

 /**
  * snd_dmaengine_pcm_register - Register a dmaengine based PCM device
  * @dev: The parent device for the PCM device
  * @config: Platform specific PCM configuration
  * @flags: Platform specific quirks
  */
 int snd_dmaengine_pcm_register(struct device *dev,
 	const struct snd_dmaengine_pcm_config *config, unsigned int flags)
 {
 	struct dmaengine_pcm *pcm;

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

 	pcm->config = config;
 	pcm->flags = flags;

 	dmaengine_pcm_request_chan_of(pcm, dev);

 	if (flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE)
 		return snd_soc_add_platform(dev, &pcm->platform,
 				&dmaengine_no_residue_pcm_platform);
 	else
 		return snd_soc_add_platform(dev, &pcm->platform,
 				&dmaengine_pcm_platform);
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_register);

 /**
  * snd_dmaengine_pcm_unregister - Removes a dmaengine based PCM device
  * @dev: Parent device the PCM was register with
  *
  * Removes a dmaengine based PCM device previously registered with
  * snd_dmaengine_pcm_register.
  */
 void snd_dmaengine_pcm_unregister(struct device *dev)
 {
 	struct snd_soc_platform *platform;
 	struct dmaengine_pcm *pcm;
 	unsigned int i;

 	platform = snd_soc_lookup_platform(dev);
 	if (!platform)
 		return;

 	pcm = soc_platform_to_pcm(platform);

 	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
 		if (pcm->chan[i]) {
 			dma_release_channel(pcm->chan[i]);
 			if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
 				break;
 		}
 	}

 	snd_soc_remove_platform(platform);
 	kfree(pcm);
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_unregister);

 MODULE_LICENSE("GPL");
	/*
	* Copyright (C) 2013, Analog Devices Inc.
	* Author: Lars-Peter Clausen <lars@metafoo.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.
	*
	* 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.,
	* 675 Mass Ave, Cambridge, MA 02139, USA.
	*
	*/
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/dmaengine.h>
	#include <linux/slab.h>
	#include <sound/pcm.h>
	#include <sound/pcm_params.h>
	#include <sound/soc.h>
	#include <linux/dma-mapping.h>
	#include <linux/of.h>

	#include <sound/dmaengine_pcm.h>

	struct dmaengine_pcm {
	struct dma_chan *chan[SNDRV_PCM_STREAM_LAST + 1];
	const struct snd_dmaengine_pcm_config *config;
	struct snd_soc_platform platform;
	unsigned int flags;
	};

	static struct dmaengine_pcm soc_platform_to_pcm(struct snd_soc_platform p)
	{
	return container_of(p, struct dmaengine_pcm, platform);
	}

	static struct device dmaengine_dma_dev(struct dmaengine_pcm pcm,
	struct snd_pcm_substream *substream)
	{
	if (!pcm->chan[substream->stream])
	return NULL;

	return pcm->chan[substream->stream]->device->dev;
	}

	/**
	* snd_dmaengine_pcm_prepare_slave_config() - Generic prepare_slave_config callback
	* @substream: PCM substream
	* @params: hw_params
	* @slave_config: DMA slave config to prepare
	*
	* This function can be used as a generic prepare_slave_config callback for
	* platforms which make use of the snd_dmaengine_dai_dma_data struct for their
	* DAI DMA data. Internally the function will first call
	* snd_hwparams_to_dma_slave_config to fill in the slave config based on the
	* hw_params, followed by snd_dmaengine_set_config_from_dai_data to fill in the
	* remaining fields based on the DAI DMA data.
	*/
	int snd_dmaengine_pcm_prepare_slave_config(struct snd_pcm_substream *substream,
	struct snd_pcm_hw_params params, struct dma_slave_config slave_config)
	{
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct snd_dmaengine_dai_dma_data *dma_data;
	int ret;

	dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);

	ret = snd_hwparams_to_dma_slave_config(substream, params, slave_config);
	if (ret)
	return ret;

	snd_dmaengine_pcm_set_config_from_dai_data(substream, dma_data,
	slave_config);

	return 0;
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_prepare_slave_config);

	static int dmaengine_pcm_hw_params(struct snd_pcm_substream *substream,
	struct snd_pcm_hw_params *params)
	{
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
	struct dma_chan *chan = snd_dmaengine_pcm_get_chan(substream);
	int (prepare_slave_config)(struct snd_pcm_substream substream,
	struct snd_pcm_hw_params *params,
	struct dma_slave_config *slave_config);
	struct dma_slave_config slave_config;
	int ret;

	memset(&slave_config, 0, sizeof(slave_config));

	if (!pcm->config)
	prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config;
	else
	prepare_slave_config = pcm->config->prepare_slave_config;

	if (prepare_slave_config) {
	ret = prepare_slave_config(substream, params, &slave_config);
	if (ret)
	return ret;

	ret = dmaengine_slave_config(chan, &slave_config);
	if (ret)
	return ret;
	}

	return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(params));
	}

	static int dmaengine_pcm_set_runtime_hwparams(struct snd_pcm_substream *substream)
	{
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
	struct device *dma_dev = dmaengine_dma_dev(pcm, substream);
	struct dma_chan *chan = pcm->chan[substream->stream];
	struct snd_dmaengine_dai_dma_data *dma_data;
	struct dma_slave_caps dma_caps;
	struct snd_pcm_hardware hw;
	int ret;

	if (pcm->config && pcm->config->pcm_hardware)
	return snd_soc_set_runtime_hwparams(substream,
	pcm->config->pcm_hardware);

	dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);

	memset(&hw, 0, sizeof(hw));
	hw.info = SNDRV_PCM_INFO_MMAP \| SNDRV_PCM_INFO_MMAP_VALID \|
	SNDRV_PCM_INFO_INTERLEAVED;
	hw.periods_min = 2;
	hw.periods_max = UINT_MAX;
	hw.period_bytes_min = 256;
	hw.period_bytes_max = dma_get_max_seg_size(dma_dev);
	hw.buffer_bytes_max = SIZE_MAX;
	hw.fifo_size = dma_data->fifo_size;

	ret = dma_get_slave_caps(chan, &dma_caps);
	if (ret == 0) {
	if (dma_caps.cmd_pause)
	hw.info \|= SNDRV_PCM_INFO_PAUSE \| SNDRV_PCM_INFO_RESUME;
	}

	return snd_soc_set_runtime_hwparams(substream, &hw);
	}

	static int dmaengine_pcm_open(struct snd_pcm_substream *substream)
	{
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
	struct dma_chan *chan = pcm->chan[substream->stream];
	int ret;

	ret = dmaengine_pcm_set_runtime_hwparams(substream);
	if (ret)
	return ret;

	return snd_dmaengine_pcm_open(substream, chan);
	}

	static void dmaengine_pcm_free(struct snd_pcm *pcm)
	{
	snd_pcm_lib_preallocate_free_for_all(pcm);
	}

	static struct dma_chan *dmaengine_pcm_compat_request_channel(
	struct snd_soc_pcm_runtime *rtd,
	struct snd_pcm_substream *substream)
	{
	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
	struct snd_dmaengine_dai_dma_data *dma_data;

	dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);

	if ((pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX) && pcm->chan[0])
	return pcm->chan[0];

	if (pcm->config->compat_request_channel)
	return pcm->config->compat_request_channel(rtd, substream);

	return snd_dmaengine_pcm_request_channel(pcm->config->compat_filter_fn,
	dma_data->filter_data);
	}

	static int dmaengine_pcm_new(struct snd_soc_pcm_runtime *rtd)
	{
	struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
	const struct snd_dmaengine_pcm_config *config = pcm->config;
	struct device *dev = rtd->platform->dev;
	struct snd_dmaengine_dai_dma_data *dma_data;
	struct snd_pcm_substream *substream;
	size_t prealloc_buffer_size;
	size_t max_buffer_size;
	unsigned int i;
	int ret;

	if (config && config->prealloc_buffer_size) {
	prealloc_buffer_size = config->prealloc_buffer_size;
	max_buffer_size = config->pcm_hardware->buffer_bytes_max;
	} else {
	prealloc_buffer_size = 512 * 1024;
	max_buffer_size = SIZE_MAX;
	}


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

	dma_data = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);

	if (!pcm->chan[i] &&
	(pcm->flags & SND_DMAENGINE_PCM_FLAG_CUSTOM_CHANNEL_NAME))
	pcm->chan[i] = dma_request_slave_channel(dev,
	dma_data->chan_name);

	if (!pcm->chan[i] && (pcm->flags & SND_DMAENGINE_PCM_FLAG_COMPAT)) {
	pcm->chan[i] = dmaengine_pcm_compat_request_channel(rtd,
	substream);
	}

	if (!pcm->chan[i]) {
	dev_err(rtd->platform->dev,
	"Missing dma channel for stream: %d\n", i);
	ret = -EINVAL;
	goto err_free;
	}

	ret = snd_pcm_lib_preallocate_pages(substream,
	SNDRV_DMA_TYPE_DEV,
	dmaengine_dma_dev(pcm, substream),
	prealloc_buffer_size,
	max_buffer_size);
	if (ret)
	goto err_free;
	}

	return 0;

	err_free:
	dmaengine_pcm_free(rtd->pcm);
	return ret;
	}

	static const struct snd_pcm_ops dmaengine_pcm_ops = {
	.open = dmaengine_pcm_open,
	.close = snd_dmaengine_pcm_close,
	.ioctl = snd_pcm_lib_ioctl,
	.hw_params = dmaengine_pcm_hw_params,
	.hw_free = snd_pcm_lib_free_pages,
	.trigger = snd_dmaengine_pcm_trigger,
	.pointer = snd_dmaengine_pcm_pointer,
	};

	static const struct snd_soc_platform_driver dmaengine_pcm_platform = {
	.ops = &dmaengine_pcm_ops,
	.pcm_new = dmaengine_pcm_new,
	.pcm_free = dmaengine_pcm_free,
	.probe_order = SND_SOC_COMP_ORDER_LATE,
	};

	static const struct snd_pcm_ops dmaengine_no_residue_pcm_ops = {
	.open = dmaengine_pcm_open,
	.close = snd_dmaengine_pcm_close,
	.ioctl = snd_pcm_lib_ioctl,
	.hw_params = dmaengine_pcm_hw_params,
	.hw_free = snd_pcm_lib_free_pages,
	.trigger = snd_dmaengine_pcm_trigger,
	.pointer = snd_dmaengine_pcm_pointer_no_residue,
	};

	static const struct snd_soc_platform_driver dmaengine_no_residue_pcm_platform = {
	.ops = &dmaengine_no_residue_pcm_ops,
	.pcm_new = dmaengine_pcm_new,
	.pcm_free = dmaengine_pcm_free,
	.probe_order = SND_SOC_COMP_ORDER_LATE,
	};

	static const char * const dmaengine_pcm_dma_channel_names[] = {
	[SNDRV_PCM_STREAM_PLAYBACK] = "tx",
	[SNDRV_PCM_STREAM_CAPTURE] = "rx",
	};

	static void dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
	struct device *dev)
	{
	unsigned int i;

	if ((pcm->flags & (SND_DMAENGINE_PCM_FLAG_NO_DT \|
	SND_DMAENGINE_PCM_FLAG_CUSTOM_CHANNEL_NAME)) \|\|
	!dev->of_node)
	return;

	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX) {
	pcm->chan[0] = dma_request_slave_channel(dev, "rx-tx");
	pcm->chan[1] = pcm->chan[0];
	} else {
	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
	pcm->chan[i] = dma_request_slave_channel(dev,
	dmaengine_pcm_dma_channel_names[i]);
	}
	}
	}

	/**
	* snd_dmaengine_pcm_register - Register a dmaengine based PCM device
	* @dev: The parent device for the PCM device
	* @config: Platform specific PCM configuration
	* @flags: Platform specific quirks
	*/
	int snd_dmaengine_pcm_register(struct device *dev,
	const struct snd_dmaengine_pcm_config *config, unsigned int flags)
	{
	struct dmaengine_pcm *pcm;

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

	pcm->config = config;
	pcm->flags = flags;

	dmaengine_pcm_request_chan_of(pcm, dev);

	if (flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE)
	return snd_soc_add_platform(dev, &pcm->platform,
	&dmaengine_no_residue_pcm_platform);
	else
	return snd_soc_add_platform(dev, &pcm->platform,
	&dmaengine_pcm_platform);
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_register);

	/**
	* snd_dmaengine_pcm_unregister - Removes a dmaengine based PCM device
	* @dev: Parent device the PCM was register with
	*
	* Removes a dmaengine based PCM device previously registered with
	* snd_dmaengine_pcm_register.
	*/
	void snd_dmaengine_pcm_unregister(struct device *dev)
	{
	struct snd_soc_platform *platform;
	struct dmaengine_pcm *pcm;
	unsigned int i;

	platform = snd_soc_lookup_platform(dev);
	if (!platform)
	return;

	pcm = soc_platform_to_pcm(platform);

	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
	if (pcm->chan[i]) {
	dma_release_channel(pcm->chan[i]);
	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
	break;
	}
	}

	snd_soc_remove_platform(platform);
	kfree(pcm);
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_unregister);

	MODULE_LICENSE("GPL");