sound/soc/soc-generic-dmaengine-pcm.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 //
 //  Copyright (C) 2013, Analog Devices Inc.
 //	Author: Lars-Peter Clausen <lars@metafoo.de>

 #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>

 /*
  * The platforms dmaengine driver does not support reporting the amount of
  * bytes that are still left to transfer.
  */
 #define SND_DMAENGINE_PCM_FLAG_NO_RESIDUE BIT(31)

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

 static struct dmaengine_pcm *soc_component_to_pcm(struct snd_soc_component *p)
 {
 	return container_of(p, struct dmaengine_pcm, component);
 }

 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_soc_component *component,
 				   struct snd_pcm_substream *substream,
 				   struct snd_pcm_hw_params *params)
 {
 	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
 	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 0;
 }

 static int
 dmaengine_pcm_set_runtime_hwparams(struct snd_soc_component *component,
 				   struct snd_pcm_substream *substream)
 {
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
 	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 snd_pcm_hardware hw;

 	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;

 	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE)
 		hw.info |= SNDRV_PCM_INFO_BATCH;

 	/**
 	 * FIXME: Remove the return value check to align with the code
 	 * before adding snd_dmaengine_pcm_refine_runtime_hwparams
 	 * function.
 	 */
 	snd_dmaengine_pcm_refine_runtime_hwparams(substream,
 						  dma_data,
 						  &hw,
 						  chan);

 	return snd_soc_set_runtime_hwparams(substream, &hw);
 }

 static int dmaengine_pcm_open(struct snd_soc_component *component,
 			      struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
 	struct dma_chan *chan = pcm->chan[substream->stream];
 	int ret;

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

 	return snd_dmaengine_pcm_open(substream, chan);
 }

 static int dmaengine_pcm_close(struct snd_soc_component *component,
 			       struct snd_pcm_substream *substream)
 {
 	return snd_dmaengine_pcm_close(substream);
 }

 static int dmaengine_pcm_trigger(struct snd_soc_component *component,
 				 struct snd_pcm_substream *substream, int cmd)
 {
 	return snd_dmaengine_pcm_trigger(substream, cmd);
 }

 static struct dma_chan *dmaengine_pcm_compat_request_channel(
 	struct snd_soc_component *component,
 	struct snd_soc_pcm_runtime *rtd,
 	struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
 	struct snd_dmaengine_dai_dma_data *dma_data;
 	dma_filter_fn fn = NULL;

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

 	if (pcm->config)
 		fn = pcm->config->compat_filter_fn;

 	return snd_dmaengine_pcm_request_channel(fn, dma_data->filter_data);
 }

 static bool dmaengine_pcm_can_report_residue(struct device *dev,
 	struct dma_chan *chan)
 {
 	struct dma_slave_caps dma_caps;
 	int ret;

 	ret = dma_get_slave_caps(chan, &dma_caps);
 	if (ret != 0) {
 		dev_warn(dev, "Failed to get DMA channel capabilities, falling back to period counting: %d\n",
 			 ret);
 		return false;
 	}

 	if (dma_caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR)
 		return false;

 	return true;
 }

 static int dmaengine_pcm_new(struct snd_soc_component *component,
 			     struct snd_soc_pcm_runtime *rtd)
 {
 	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
 	const struct snd_dmaengine_pcm_config *config = pcm->config;
 	struct device *dev = component->dev;
 	struct snd_pcm_substream *substream;
 	size_t prealloc_buffer_size;
 	size_t max_buffer_size;
 	unsigned int i;

 	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;

 		if (!pcm->chan[i] && config && config->chan_names[i])
 			pcm->chan[i] = dma_request_slave_channel(dev,
 				config->chan_names[i]);

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

 		if (!pcm->chan[i]) {
 			dev_err(component->dev,
 				"Missing dma channel for stream: %d\n", i);
 			return -EINVAL;
 		}

 		snd_pcm_set_managed_buffer(substream,
 				SNDRV_DMA_TYPE_DEV_IRAM,
 				dmaengine_dma_dev(pcm, substream),
 				prealloc_buffer_size,
 				max_buffer_size);

 		if (!dmaengine_pcm_can_report_residue(dev, pcm->chan[i]))
 			pcm->flags |= SND_DMAENGINE_PCM_FLAG_NO_RESIDUE;

 		if (rtd->pcm->streams[i].pcm->name[0] == '\0') {
 			strscpy_pad(rtd->pcm->streams[i].pcm->name,
 				    rtd->pcm->streams[i].pcm->id,
 				    sizeof(rtd->pcm->streams[i].pcm->name));
 		}
 	}

 	return 0;
 }

 static snd_pcm_uframes_t dmaengine_pcm_pointer(
 	struct snd_soc_component *component,
 	struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);

 	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE)
 		return snd_dmaengine_pcm_pointer_no_residue(substream);
 	else
 		return snd_dmaengine_pcm_pointer(substream);
 }

 static int dmaengine_copy_user(struct snd_soc_component *component,
 			       struct snd_pcm_substream *substream,
 			       int channel, unsigned long hwoff,
 			       void __user *buf, unsigned long bytes)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
 	int (*process)(struct snd_pcm_substream *substream,
 		       int channel, unsigned long hwoff,
 		       void *buf, unsigned long bytes) = pcm->config->process;
 	bool is_playback = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
 	void *dma_ptr = runtime->dma_area + hwoff +
 			channel * (runtime->dma_bytes / runtime->channels);
 	int ret;

 	if (is_playback)
 		if (copy_from_user(dma_ptr, buf, bytes))
 			return -EFAULT;

 	if (process) {
 		ret = process(substream, channel, hwoff, (__force void *)buf, bytes);
 		if (ret < 0)
 			return ret;
 	}

 	if (!is_playback)
 		if (copy_to_user(buf, dma_ptr, bytes))
 			return -EFAULT;

 	return 0;
 }

 static const struct snd_soc_component_driver dmaengine_pcm_component = {
 	.name		= SND_DMAENGINE_PCM_DRV_NAME,
 	.probe_order	= SND_SOC_COMP_ORDER_LATE,
 	.open		= dmaengine_pcm_open,
 	.close		= dmaengine_pcm_close,
 	.hw_params	= dmaengine_pcm_hw_params,
 	.trigger	= dmaengine_pcm_trigger,
 	.pointer	= dmaengine_pcm_pointer,
 	.pcm_construct	= dmaengine_pcm_new,
 };

 static const struct snd_soc_component_driver dmaengine_pcm_component_process = {
 	.name		= SND_DMAENGINE_PCM_DRV_NAME,
 	.probe_order	= SND_SOC_COMP_ORDER_LATE,
 	.open		= dmaengine_pcm_open,
 	.close		= dmaengine_pcm_close,
 	.hw_params	= dmaengine_pcm_hw_params,
 	.trigger	= dmaengine_pcm_trigger,
 	.pointer	= dmaengine_pcm_pointer,
 	.copy_user	= dmaengine_copy_user,
 	.pcm_construct	= dmaengine_pcm_new,
 };

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

 static int dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
 	struct device *dev, const struct snd_dmaengine_pcm_config *config)
 {
 	unsigned int i;
 	const char *name;
 	struct dma_chan *chan;

 	if ((pcm->flags & SND_DMAENGINE_PCM_FLAG_NO_DT) || (!dev->of_node &&
 	    !(config && config->dma_dev && config->dma_dev->of_node)))
 		return 0;

 	if (config && config->dma_dev) {
 		/*
 		 * If this warning is seen, it probably means that your Linux
 		 * device structure does not match your HW device structure.
 		 * It would be best to refactor the Linux device structure to
 		 * correctly match the HW structure.
 		 */
 		dev_warn(dev, "DMA channels sourced from device %s",
 			 dev_name(config->dma_dev));
 		dev = config->dma_dev;
 	}

 	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE;
 	     i++) {
 		if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
 			name = "rx-tx";
 		else
 			name = dmaengine_pcm_dma_channel_names[i];
 		if (config && config->chan_names[i])
 			name = config->chan_names[i];
 		chan = dma_request_chan(dev, name);
 		if (IS_ERR(chan)) {
 			if (PTR_ERR(chan) == -EPROBE_DEFER)
 				return -EPROBE_DEFER;
 			pcm->chan[i] = NULL;
 		} else {
 			pcm->chan[i] = chan;
 		}
 		if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
 			break;
 	}

 	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
 		pcm->chan[1] = pcm->chan[0];

 	return 0;
 }

 static void dmaengine_pcm_release_chan(struct dmaengine_pcm *pcm)
 {
 	unsigned int i;

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

 /**
  * 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;
 	int ret;

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

 #ifdef CONFIG_DEBUG_FS
 	pcm->component.debugfs_prefix = "dma";
 #endif
 	pcm->config = config;
 	pcm->flags = flags;

 	ret = dmaengine_pcm_request_chan_of(pcm, dev, config);
 	if (ret)
 		goto err_free_dma;

 	if (config && config->process)
 		ret = snd_soc_add_component(dev, &pcm->component,
 					    &dmaengine_pcm_component_process,
 					    NULL, 0);
 	else
 		ret = snd_soc_add_component(dev, &pcm->component,
 					    &dmaengine_pcm_component, NULL, 0);
 	if (ret)
 		goto err_free_dma;

 	return 0;

 err_free_dma:
 	dmaengine_pcm_release_chan(pcm);
 	kfree(pcm);
 	return ret;
 }
 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_component *component;
 	struct dmaengine_pcm *pcm;

 	component = snd_soc_lookup_component(dev, SND_DMAENGINE_PCM_DRV_NAME);
 	if (!component)
 		return;

 	pcm = soc_component_to_pcm(component);

 	snd_soc_unregister_component(dev);
 	dmaengine_pcm_release_chan(pcm);
 	kfree(pcm);
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_unregister);

 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	//
	// Copyright (C) 2013, Analog Devices Inc.
	// Author: Lars-Peter Clausen <lars@metafoo.de>

	#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>

	/*
	* The platforms dmaengine driver does not support reporting the amount of
	* bytes that are still left to transfer.
	*/
	#define SND_DMAENGINE_PCM_FLAG_NO_RESIDUE BIT(31)

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

	static struct dmaengine_pcm soc_component_to_pcm(struct snd_soc_component p)
	{
	return container_of(p, struct dmaengine_pcm, component);
	}

	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_soc_component *component,
	struct snd_pcm_substream *substream,
	struct snd_pcm_hw_params *params)
	{
	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
	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 0;
	}

	static int
	dmaengine_pcm_set_runtime_hwparams(struct snd_soc_component *component,
	struct snd_pcm_substream *substream)
	{
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
	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 snd_pcm_hardware hw;

	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;

	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE)
	hw.info \|= SNDRV_PCM_INFO_BATCH;

	/**
	* FIXME: Remove the return value check to align with the code
	* before adding snd_dmaengine_pcm_refine_runtime_hwparams
	* function.
	*/
	snd_dmaengine_pcm_refine_runtime_hwparams(substream,
	dma_data,
	&hw,
	chan);

	return snd_soc_set_runtime_hwparams(substream, &hw);
	}

	static int dmaengine_pcm_open(struct snd_soc_component *component,
	struct snd_pcm_substream *substream)
	{
	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
	struct dma_chan *chan = pcm->chan[substream->stream];
	int ret;

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

	return snd_dmaengine_pcm_open(substream, chan);
	}

	static int dmaengine_pcm_close(struct snd_soc_component *component,
	struct snd_pcm_substream *substream)
	{
	return snd_dmaengine_pcm_close(substream);
	}

	static int dmaengine_pcm_trigger(struct snd_soc_component *component,
	struct snd_pcm_substream *substream, int cmd)
	{
	return snd_dmaengine_pcm_trigger(substream, cmd);
	}

	static struct dma_chan *dmaengine_pcm_compat_request_channel(
	struct snd_soc_component *component,
	struct snd_soc_pcm_runtime *rtd,
	struct snd_pcm_substream *substream)
	{
	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
	struct snd_dmaengine_dai_dma_data *dma_data;
	dma_filter_fn fn = NULL;

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

	if (pcm->config)
	fn = pcm->config->compat_filter_fn;

	return snd_dmaengine_pcm_request_channel(fn, dma_data->filter_data);
	}

	static bool dmaengine_pcm_can_report_residue(struct device *dev,
	struct dma_chan *chan)
	{
	struct dma_slave_caps dma_caps;
	int ret;

	ret = dma_get_slave_caps(chan, &dma_caps);
	if (ret != 0) {
	dev_warn(dev, "Failed to get DMA channel capabilities, falling back to period counting: %d\n",
	ret);
	return false;
	}

	if (dma_caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR)
	return false;

	return true;
	}

	static int dmaengine_pcm_new(struct snd_soc_component *component,
	struct snd_soc_pcm_runtime *rtd)
	{
	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
	const struct snd_dmaengine_pcm_config *config = pcm->config;
	struct device *dev = component->dev;
	struct snd_pcm_substream *substream;
	size_t prealloc_buffer_size;
	size_t max_buffer_size;
	unsigned int i;

	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;

	if (!pcm->chan[i] && config && config->chan_names[i])
	pcm->chan[i] = dma_request_slave_channel(dev,
	config->chan_names[i]);

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

	if (!pcm->chan[i]) {
	dev_err(component->dev,
	"Missing dma channel for stream: %d\n", i);
	return -EINVAL;
	}

	snd_pcm_set_managed_buffer(substream,
	SNDRV_DMA_TYPE_DEV_IRAM,
	dmaengine_dma_dev(pcm, substream),
	prealloc_buffer_size,
	max_buffer_size);

	if (!dmaengine_pcm_can_report_residue(dev, pcm->chan[i]))
	pcm->flags \|= SND_DMAENGINE_PCM_FLAG_NO_RESIDUE;

	if (rtd->pcm->streams[i].pcm->name[0] == '\0') {
	strscpy_pad(rtd->pcm->streams[i].pcm->name,
	rtd->pcm->streams[i].pcm->id,
	sizeof(rtd->pcm->streams[i].pcm->name));
	}
	}

	return 0;
	}

	static snd_pcm_uframes_t dmaengine_pcm_pointer(
	struct snd_soc_component *component,
	struct snd_pcm_substream *substream)
	{
	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);

	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE)
	return snd_dmaengine_pcm_pointer_no_residue(substream);
	else
	return snd_dmaengine_pcm_pointer(substream);
	}

	static int dmaengine_copy_user(struct snd_soc_component *component,
	struct snd_pcm_substream *substream,
	int channel, unsigned long hwoff,
	void __user *buf, unsigned long bytes)
	{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
	int (process)(struct snd_pcm_substream substream,
	int channel, unsigned long hwoff,
	void *buf, unsigned long bytes) = pcm->config->process;
	bool is_playback = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
	void *dma_ptr = runtime->dma_area + hwoff +
	channel * (runtime->dma_bytes / runtime->channels);
	int ret;

	if (is_playback)
	if (copy_from_user(dma_ptr, buf, bytes))
	return -EFAULT;

	if (process) {
	ret = process(substream, channel, hwoff, (__force void *)buf, bytes);
	if (ret < 0)
	return ret;
	}

	if (!is_playback)
	if (copy_to_user(buf, dma_ptr, bytes))
	return -EFAULT;

	return 0;
	}

	static const struct snd_soc_component_driver dmaengine_pcm_component = {
	.name = SND_DMAENGINE_PCM_DRV_NAME,
	.probe_order = SND_SOC_COMP_ORDER_LATE,
	.open = dmaengine_pcm_open,
	.close = dmaengine_pcm_close,
	.hw_params = dmaengine_pcm_hw_params,
	.trigger = dmaengine_pcm_trigger,
	.pointer = dmaengine_pcm_pointer,
	.pcm_construct = dmaengine_pcm_new,
	};

	static const struct snd_soc_component_driver dmaengine_pcm_component_process = {
	.name = SND_DMAENGINE_PCM_DRV_NAME,
	.probe_order = SND_SOC_COMP_ORDER_LATE,
	.open = dmaengine_pcm_open,
	.close = dmaengine_pcm_close,
	.hw_params = dmaengine_pcm_hw_params,
	.trigger = dmaengine_pcm_trigger,
	.pointer = dmaengine_pcm_pointer,
	.copy_user = dmaengine_copy_user,
	.pcm_construct = dmaengine_pcm_new,
	};

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

	static int dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
	struct device dev, const struct snd_dmaengine_pcm_config config)
	{
	unsigned int i;
	const char *name;
	struct dma_chan *chan;

	if ((pcm->flags & SND_DMAENGINE_PCM_FLAG_NO_DT) \|\| (!dev->of_node &&
	!(config && config->dma_dev && config->dma_dev->of_node)))
	return 0;

	if (config && config->dma_dev) {
	/*
	* If this warning is seen, it probably means that your Linux
	* device structure does not match your HW device structure.
	* It would be best to refactor the Linux device structure to
	* correctly match the HW structure.
	*/
	dev_warn(dev, "DMA channels sourced from device %s",
	dev_name(config->dma_dev));
	dev = config->dma_dev;
	}

	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE;
	i++) {
	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
	name = "rx-tx";
	else
	name = dmaengine_pcm_dma_channel_names[i];
	if (config && config->chan_names[i])
	name = config->chan_names[i];
	chan = dma_request_chan(dev, name);
	if (IS_ERR(chan)) {
	if (PTR_ERR(chan) == -EPROBE_DEFER)
	return -EPROBE_DEFER;
	pcm->chan[i] = NULL;
	} else {
	pcm->chan[i] = chan;
	}
	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
	break;
	}

	if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
	pcm->chan[1] = pcm->chan[0];

	return 0;
	}

	static void dmaengine_pcm_release_chan(struct dmaengine_pcm *pcm)
	{
	unsigned int i;

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

	/**
	* 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;
	int ret;

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

	#ifdef CONFIG_DEBUG_FS
	pcm->component.debugfs_prefix = "dma";
	#endif
	pcm->config = config;
	pcm->flags = flags;

	ret = dmaengine_pcm_request_chan_of(pcm, dev, config);
	if (ret)
	goto err_free_dma;

	if (config && config->process)
	ret = snd_soc_add_component(dev, &pcm->component,
	&dmaengine_pcm_component_process,
	NULL, 0);
	else
	ret = snd_soc_add_component(dev, &pcm->component,
	&dmaengine_pcm_component, NULL, 0);
	if (ret)
	goto err_free_dma;

	return 0;

	err_free_dma:
	dmaengine_pcm_release_chan(pcm);
	kfree(pcm);
	return ret;
	}
	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_component *component;
	struct dmaengine_pcm *pcm;

	component = snd_soc_lookup_component(dev, SND_DMAENGINE_PCM_DRV_NAME);
	if (!component)
	return;

	pcm = soc_component_to_pcm(component);

	snd_soc_unregister_component(dev);
	dmaengine_pcm_release_chan(pcm);
	kfree(pcm);
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_unregister);

	MODULE_LICENSE("GPL");