sound/core/pcm_dmaengine.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *  Copyright (C) 2012, Analog Devices Inc.
  *	Author: Lars-Peter Clausen <lars@metafoo.de>
  *
  *  Based on:
  *	imx-pcm-dma-mx2.c, Copyright 2009 Sascha Hauer <s.hauer@pengutronix.de>
  *	mxs-pcm.c, Copyright (C) 2011 Freescale Semiconductor, Inc.
  *	ep93xx-pcm.c, Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
  *		      Copyright (C) 2006 Applied Data Systems
  */
 #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 <sound/dmaengine_pcm.h>

 struct dmaengine_pcm_runtime_data {
 	struct dma_chan *dma_chan;
 	dma_cookie_t cookie;

 	unsigned int pos;
 };

 static inline struct dmaengine_pcm_runtime_data *substream_to_prtd(
 	const struct snd_pcm_substream *substream)
 {
 	return substream->runtime->private_data;
 }

 struct dma_chan *snd_dmaengine_pcm_get_chan(struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);

 	return prtd->dma_chan;
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_get_chan);

 /**
  * snd_hwparams_to_dma_slave_config - Convert hw_params to dma_slave_config
  * @substream: PCM substream
  * @params: hw_params
  * @slave_config: DMA slave config
  *
  * This function can be used to initialize a dma_slave_config from a substream
  * and hw_params in a dmaengine based PCM driver implementation.
  *
  * Return: zero if successful, or a negative error code
  */
 int snd_hwparams_to_dma_slave_config(const struct snd_pcm_substream *substream,
 	const struct snd_pcm_hw_params *params,
 	struct dma_slave_config *slave_config)
 {
 	enum dma_slave_buswidth buswidth;
 	int bits;

 	bits = params_physical_width(params);
 	if (bits < 8 || bits > 64)
 		return -EINVAL;
 	else if (bits == 8)
 		buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
 	else if (bits == 16)
 		buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
 	else if (bits == 24)
 		buswidth = DMA_SLAVE_BUSWIDTH_3_BYTES;
 	else if (bits <= 32)
 		buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;
 	else
 		buswidth = DMA_SLAVE_BUSWIDTH_8_BYTES;

 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		slave_config->direction = DMA_MEM_TO_DEV;
 		slave_config->dst_addr_width = buswidth;
 	} else {
 		slave_config->direction = DMA_DEV_TO_MEM;
 		slave_config->src_addr_width = buswidth;
 	}

 	slave_config->device_fc = false;

 	return 0;
 }
 EXPORT_SYMBOL_GPL(snd_hwparams_to_dma_slave_config);

 /**
  * snd_dmaengine_pcm_set_config_from_dai_data() - Initializes a dma slave config
  *  using DAI DMA data.
  * @substream: PCM substream
  * @dma_data: DAI DMA data
  * @slave_config: DMA slave configuration
  *
  * Initializes the {dst,src}_addr, {dst,src}_maxburst, {dst,src}_addr_width
  * fields of the DMA slave config from the same fields of the DAI DMA
  * data struct. The src and dst fields will be initialized depending on the
  * direction of the substream. If the substream is a playback stream the dst
  * fields will be initialized, if it is a capture stream the src fields will be
  * initialized. The {dst,src}_addr_width field will only be initialized if the
  * SND_DMAENGINE_PCM_DAI_FLAG_PACK flag is set or if the addr_width field of
  * the DAI DMA data struct is not equal to DMA_SLAVE_BUSWIDTH_UNDEFINED. If
  * both conditions are met the latter takes priority.
  */
 void snd_dmaengine_pcm_set_config_from_dai_data(
 	const struct snd_pcm_substream *substream,
 	const struct snd_dmaengine_dai_dma_data *dma_data,
 	struct dma_slave_config *slave_config)
 {
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		slave_config->dst_addr = dma_data->addr;
 		slave_config->dst_maxburst = dma_data->maxburst;
 		if (dma_data->flags & SND_DMAENGINE_PCM_DAI_FLAG_PACK)
 			slave_config->dst_addr_width =
 				DMA_SLAVE_BUSWIDTH_UNDEFINED;
 		if (dma_data->addr_width != DMA_SLAVE_BUSWIDTH_UNDEFINED)
 			slave_config->dst_addr_width = dma_data->addr_width;
 	} else {
 		slave_config->src_addr = dma_data->addr;
 		slave_config->src_maxburst = dma_data->maxburst;
 		if (dma_data->flags & SND_DMAENGINE_PCM_DAI_FLAG_PACK)
 			slave_config->src_addr_width =
 				DMA_SLAVE_BUSWIDTH_UNDEFINED;
 		if (dma_data->addr_width != DMA_SLAVE_BUSWIDTH_UNDEFINED)
 			slave_config->src_addr_width = dma_data->addr_width;
 	}

 	slave_config->peripheral_config = dma_data->peripheral_config;
 	slave_config->peripheral_size = dma_data->peripheral_size;
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_set_config_from_dai_data);

 static void dmaengine_pcm_dma_complete(void *arg)
 {
 	struct snd_pcm_substream *substream = arg;
 	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);

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

 	snd_pcm_period_elapsed(substream);
 }

 static int dmaengine_pcm_prepare_and_submit(struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
 	struct dma_chan *chan = prtd->dma_chan;
 	struct dma_async_tx_descriptor *desc;
 	enum dma_transfer_direction direction;
 	unsigned long flags = DMA_CTRL_ACK;

 	direction = snd_pcm_substream_to_dma_direction(substream);

 	if (!substream->runtime->no_period_wakeup)
 		flags |= DMA_PREP_INTERRUPT;

 	prtd->pos = 0;
 	desc = dmaengine_prep_dma_cyclic(chan,
 		substream->runtime->dma_addr,
 		snd_pcm_lib_buffer_bytes(substream),
 		snd_pcm_lib_period_bytes(substream), direction, flags);

 	if (!desc)
 		return -ENOMEM;

 	desc->callback = dmaengine_pcm_dma_complete;
 	desc->callback_param = substream;
 	prtd->cookie = dmaengine_submit(desc);

 	return 0;
 }

 /**
  * snd_dmaengine_pcm_trigger - dmaengine based PCM trigger implementation
  * @substream: PCM substream
  * @cmd: Trigger command
  *
  * This function can be used as the PCM trigger callback for dmaengine based PCM
  * driver implementations.
  *
  * Return: 0 on success, a negative error code otherwise
  */
 int snd_dmaengine_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 {
 	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	int ret;

 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
 		ret = dmaengine_pcm_prepare_and_submit(substream);
 		if (ret)
 			return ret;
 		dma_async_issue_pending(prtd->dma_chan);
 		break;
 	case SNDRV_PCM_TRIGGER_RESUME:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 		dmaengine_resume(prtd->dma_chan);
 		break;
 	case SNDRV_PCM_TRIGGER_SUSPEND:
 		if (runtime->info & SNDRV_PCM_INFO_PAUSE)
 			dmaengine_pause(prtd->dma_chan);
 		else
 			dmaengine_terminate_async(prtd->dma_chan);
 		break;
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 		dmaengine_pause(prtd->dma_chan);
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
 		dmaengine_terminate_async(prtd->dma_chan);
 		break;
 	default:
 		return -EINVAL;
 	}

 	return 0;
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_trigger);

 /**
  * snd_dmaengine_pcm_pointer_no_residue - dmaengine based PCM pointer implementation
  * @substream: PCM substream
  *
  * This function is deprecated and should not be used by new drivers, as its
  * results may be unreliable.
  *
  * Return: PCM position in frames
  */
 snd_pcm_uframes_t snd_dmaengine_pcm_pointer_no_residue(struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
 	return bytes_to_frames(substream->runtime, prtd->pos);
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_pointer_no_residue);

 /**
  * snd_dmaengine_pcm_pointer - dmaengine based PCM pointer implementation
  * @substream: PCM substream
  *
  * This function can be used as the PCM pointer callback for dmaengine based PCM
  * driver implementations.
  *
  * Return: PCM position in frames
  */
 snd_pcm_uframes_t snd_dmaengine_pcm_pointer(struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct dma_tx_state state;
 	enum dma_status status;
 	unsigned int buf_size;
 	unsigned int pos = 0;

 	status = dmaengine_tx_status(prtd->dma_chan, prtd->cookie, &state);
 	if (status == DMA_IN_PROGRESS || status == DMA_PAUSED) {
 		buf_size = snd_pcm_lib_buffer_bytes(substream);
 		if (state.residue > 0 && state.residue <= buf_size)
 			pos = buf_size - state.residue;

 		runtime->delay = bytes_to_frames(runtime,
 						 state.in_flight_bytes);
 	}

 	return bytes_to_frames(runtime, pos);
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_pointer);

 /**
  * snd_dmaengine_pcm_request_channel - Request channel for the dmaengine PCM
  * @filter_fn: Filter function used to request the DMA channel
  * @filter_data: Data passed to the DMA filter function
  *
  * This function request a DMA channel for usage with dmaengine PCM.
  *
  * Return: NULL or the requested DMA channel
  */
 struct dma_chan *snd_dmaengine_pcm_request_channel(dma_filter_fn filter_fn,
 	void *filter_data)
 {
 	dma_cap_mask_t mask;

 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
 	dma_cap_set(DMA_CYCLIC, mask);

 	return dma_request_channel(mask, filter_fn, filter_data);
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_request_channel);

 /**
  * snd_dmaengine_pcm_open - Open a dmaengine based PCM substream
  * @substream: PCM substream
  * @chan: DMA channel to use for data transfers
  *
  * The function should usually be called from the pcm open callback. Note that
  * this function will use private_data field of the substream's runtime. So it
  * is not available to your pcm driver implementation.
  *
  * Return: 0 on success, a negative error code otherwise
  */
 int snd_dmaengine_pcm_open(struct snd_pcm_substream *substream,
 	struct dma_chan *chan)
 {
 	struct dmaengine_pcm_runtime_data *prtd;
 	int ret;

 	if (!chan)
 		return -ENXIO;

 	ret = snd_pcm_hw_constraint_integer(substream->runtime,
 					    SNDRV_PCM_HW_PARAM_PERIODS);
 	if (ret < 0)
 		return ret;

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

 	prtd->dma_chan = chan;

 	substream->runtime->private_data = prtd;

 	return 0;
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_open);

 /**
  * snd_dmaengine_pcm_open_request_chan - Open a dmaengine based PCM substream and request channel
  * @substream: PCM substream
  * @filter_fn: Filter function used to request the DMA channel
  * @filter_data: Data passed to the DMA filter function
  *
  * This function will request a DMA channel using the passed filter function and
  * data. The function should usually be called from the pcm open callback. Note
  * that this function will use private_data field of the substream's runtime. So
  * it is not available to your pcm driver implementation.
  *
  * Return: 0 on success, a negative error code otherwise
  */
 int snd_dmaengine_pcm_open_request_chan(struct snd_pcm_substream *substream,
 	dma_filter_fn filter_fn, void *filter_data)
 {
 	return snd_dmaengine_pcm_open(substream,
 		    snd_dmaengine_pcm_request_channel(filter_fn, filter_data));
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_open_request_chan);

 /**
  * snd_dmaengine_pcm_close - Close a dmaengine based PCM substream
  * @substream: PCM substream
  *
  * Return: 0 on success, a negative error code otherwise
  */
 int snd_dmaengine_pcm_close(struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);

 	dmaengine_synchronize(prtd->dma_chan);
 	kfree(prtd);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_close);

 /**
  * snd_dmaengine_pcm_close_release_chan - Close a dmaengine based PCM
  *					  substream and release channel
  * @substream: PCM substream
  *
  * Releases the DMA channel associated with the PCM substream.
  *
  * Return: zero if successful, or a negative error code
  */
 int snd_dmaengine_pcm_close_release_chan(struct snd_pcm_substream *substream)
 {
 	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);

 	dmaengine_synchronize(prtd->dma_chan);
 	dma_release_channel(prtd->dma_chan);
 	kfree(prtd);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_close_release_chan);

 /**
  * snd_dmaengine_pcm_refine_runtime_hwparams - Refine runtime hw params
  * @substream: PCM substream
  * @dma_data: DAI DMA data
  * @hw: PCM hw params
  * @chan: DMA channel to use for data transfers
  *
  * This function will query DMA capability, then refine the pcm hardware
  * parameters.
  *
  * Return: 0 on success, a negative error code otherwise
  */
 int snd_dmaengine_pcm_refine_runtime_hwparams(
 	struct snd_pcm_substream *substream,
 	struct snd_dmaengine_dai_dma_data *dma_data,
 	struct snd_pcm_hardware *hw,
 	struct dma_chan *chan)
 {
 	struct dma_slave_caps dma_caps;
 	u32 addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
 			  BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
 			  BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
 	snd_pcm_format_t i;
 	int ret = 0;

 	if (!hw || !chan || !dma_data)
 		return -EINVAL;

 	ret = dma_get_slave_caps(chan, &dma_caps);
 	if (ret == 0) {
 		if (dma_caps.cmd_pause && dma_caps.cmd_resume)
 			hw->info |= SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME;
 		if (dma_caps.residue_granularity <= DMA_RESIDUE_GRANULARITY_SEGMENT)
 			hw->info |= SNDRV_PCM_INFO_BATCH;

 		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 			addr_widths = dma_caps.dst_addr_widths;
 		else
 			addr_widths = dma_caps.src_addr_widths;
 	}

 	/*
 	 * If SND_DMAENGINE_PCM_DAI_FLAG_PACK is set keep
 	 * hw.formats set to 0, meaning no restrictions are in place.
 	 * In this case it's the responsibility of the DAI driver to
 	 * provide the supported format information.
 	 */
 	if (!(dma_data->flags & SND_DMAENGINE_PCM_DAI_FLAG_PACK))
 		/*
 		 * Prepare formats mask for valid/allowed sample types. If the
 		 * dma does not have support for the given physical word size,
 		 * it needs to be masked out so user space can not use the
 		 * format which produces corrupted audio.
 		 * In case the dma driver does not implement the slave_caps the
 		 * default assumption is that it supports 1, 2 and 4 bytes
 		 * widths.
 		 */
 		pcm_for_each_format(i) {
 			int bits = snd_pcm_format_physical_width(i);

 			/*
 			 * Enable only samples with DMA supported physical
 			 * widths
 			 */
 			switch (bits) {
 			case 8:
 			case 16:
 			case 24:
 			case 32:
 			case 64:
 				if (addr_widths & (1 << (bits / 8)))
 					hw->formats |= pcm_format_to_bits(i);
 				break;
 			default:
 				/* Unsupported types */
 				break;
 			}
 		}

 	return ret;
 }
 EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_refine_runtime_hwparams);

 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Copyright (C) 2012, Analog Devices Inc.
	* Author: Lars-Peter Clausen <lars@metafoo.de>
	*
	* Based on:
	* imx-pcm-dma-mx2.c, Copyright 2009 Sascha Hauer <s.hauer@pengutronix.de>
	* mxs-pcm.c, Copyright (C) 2011 Freescale Semiconductor, Inc.
	* ep93xx-pcm.c, Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
	* Copyright (C) 2006 Applied Data Systems
	*/
	#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 <sound/dmaengine_pcm.h>

	struct dmaengine_pcm_runtime_data {
	struct dma_chan *dma_chan;
	dma_cookie_t cookie;

	unsigned int pos;
	};

	static inline struct dmaengine_pcm_runtime_data *substream_to_prtd(
	const struct snd_pcm_substream *substream)
	{
	return substream->runtime->private_data;
	}

	struct dma_chan snd_dmaengine_pcm_get_chan(struct snd_pcm_substream substream)
	{
	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);

	return prtd->dma_chan;
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_get_chan);

	/**
	* snd_hwparams_to_dma_slave_config - Convert hw_params to dma_slave_config
	* @substream: PCM substream
	* @params: hw_params
	* @slave_config: DMA slave config
	*
	* This function can be used to initialize a dma_slave_config from a substream
	* and hw_params in a dmaengine based PCM driver implementation.
	*
	* Return: zero if successful, or a negative error code
	*/
	int snd_hwparams_to_dma_slave_config(const struct snd_pcm_substream *substream,
	const struct snd_pcm_hw_params *params,
	struct dma_slave_config *slave_config)
	{
	enum dma_slave_buswidth buswidth;
	int bits;

	bits = params_physical_width(params);
	if (bits < 8 \|\| bits > 64)
	return -EINVAL;
	else if (bits == 8)
	buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
	else if (bits == 16)
	buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
	else if (bits == 24)
	buswidth = DMA_SLAVE_BUSWIDTH_3_BYTES;
	else if (bits <= 32)
	buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;
	else
	buswidth = DMA_SLAVE_BUSWIDTH_8_BYTES;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
	slave_config->direction = DMA_MEM_TO_DEV;
	slave_config->dst_addr_width = buswidth;
	} else {
	slave_config->direction = DMA_DEV_TO_MEM;
	slave_config->src_addr_width = buswidth;
	}

	slave_config->device_fc = false;

	return 0;
	}
	EXPORT_SYMBOL_GPL(snd_hwparams_to_dma_slave_config);

	/**
	* snd_dmaengine_pcm_set_config_from_dai_data() - Initializes a dma slave config
	* using DAI DMA data.
	* @substream: PCM substream
	* @dma_data: DAI DMA data
	* @slave_config: DMA slave configuration
	*
	* Initializes the {dst,src}_addr, {dst,src}_maxburst, {dst,src}_addr_width
	* fields of the DMA slave config from the same fields of the DAI DMA
	* data struct. The src and dst fields will be initialized depending on the
	* direction of the substream. If the substream is a playback stream the dst
	* fields will be initialized, if it is a capture stream the src fields will be
	* initialized. The {dst,src}_addr_width field will only be initialized if the
	* SND_DMAENGINE_PCM_DAI_FLAG_PACK flag is set or if the addr_width field of
	* the DAI DMA data struct is not equal to DMA_SLAVE_BUSWIDTH_UNDEFINED. If
	* both conditions are met the latter takes priority.
	*/
	void snd_dmaengine_pcm_set_config_from_dai_data(
	const struct snd_pcm_substream *substream,
	const struct snd_dmaengine_dai_dma_data *dma_data,
	struct dma_slave_config *slave_config)
	{
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
	slave_config->dst_addr = dma_data->addr;
	slave_config->dst_maxburst = dma_data->maxburst;
	if (dma_data->flags & SND_DMAENGINE_PCM_DAI_FLAG_PACK)
	slave_config->dst_addr_width =
	DMA_SLAVE_BUSWIDTH_UNDEFINED;
	if (dma_data->addr_width != DMA_SLAVE_BUSWIDTH_UNDEFINED)
	slave_config->dst_addr_width = dma_data->addr_width;
	} else {
	slave_config->src_addr = dma_data->addr;
	slave_config->src_maxburst = dma_data->maxburst;
	if (dma_data->flags & SND_DMAENGINE_PCM_DAI_FLAG_PACK)
	slave_config->src_addr_width =
	DMA_SLAVE_BUSWIDTH_UNDEFINED;
	if (dma_data->addr_width != DMA_SLAVE_BUSWIDTH_UNDEFINED)
	slave_config->src_addr_width = dma_data->addr_width;
	}

	slave_config->peripheral_config = dma_data->peripheral_config;
	slave_config->peripheral_size = dma_data->peripheral_size;
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_set_config_from_dai_data);

	static void dmaengine_pcm_dma_complete(void *arg)
	{
	struct snd_pcm_substream *substream = arg;
	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);

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

	snd_pcm_period_elapsed(substream);
	}

	static int dmaengine_pcm_prepare_and_submit(struct snd_pcm_substream *substream)
	{
	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
	struct dma_chan *chan = prtd->dma_chan;
	struct dma_async_tx_descriptor *desc;
	enum dma_transfer_direction direction;
	unsigned long flags = DMA_CTRL_ACK;

	direction = snd_pcm_substream_to_dma_direction(substream);

	if (!substream->runtime->no_period_wakeup)
	flags \|= DMA_PREP_INTERRUPT;

	prtd->pos = 0;
	desc = dmaengine_prep_dma_cyclic(chan,
	substream->runtime->dma_addr,
	snd_pcm_lib_buffer_bytes(substream),
	snd_pcm_lib_period_bytes(substream), direction, flags);

	if (!desc)
	return -ENOMEM;

	desc->callback = dmaengine_pcm_dma_complete;
	desc->callback_param = substream;
	prtd->cookie = dmaengine_submit(desc);

	return 0;
	}

	/**
	* snd_dmaengine_pcm_trigger - dmaengine based PCM trigger implementation
	* @substream: PCM substream
	* @cmd: Trigger command
	*
	* This function can be used as the PCM trigger callback for dmaengine based PCM
	* driver implementations.
	*
	* Return: 0 on success, a negative error code otherwise
	*/
	int snd_dmaengine_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
	{
	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;
	int ret;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	ret = dmaengine_pcm_prepare_and_submit(substream);
	if (ret)
	return ret;
	dma_async_issue_pending(prtd->dma_chan);
	break;
	case SNDRV_PCM_TRIGGER_RESUME:
	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
	dmaengine_resume(prtd->dma_chan);
	break;
	case SNDRV_PCM_TRIGGER_SUSPEND:
	if (runtime->info & SNDRV_PCM_INFO_PAUSE)
	dmaengine_pause(prtd->dma_chan);
	else
	dmaengine_terminate_async(prtd->dma_chan);
	break;
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
	dmaengine_pause(prtd->dma_chan);
	break;
	case SNDRV_PCM_TRIGGER_STOP:
	dmaengine_terminate_async(prtd->dma_chan);
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_trigger);

	/**
	* snd_dmaengine_pcm_pointer_no_residue - dmaengine based PCM pointer implementation
	* @substream: PCM substream
	*
	* This function is deprecated and should not be used by new drivers, as its
	* results may be unreliable.
	*
	* Return: PCM position in frames
	*/
	snd_pcm_uframes_t snd_dmaengine_pcm_pointer_no_residue(struct snd_pcm_substream *substream)
	{
	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
	return bytes_to_frames(substream->runtime, prtd->pos);
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_pointer_no_residue);

	/**
	* snd_dmaengine_pcm_pointer - dmaengine based PCM pointer implementation
	* @substream: PCM substream
	*
	* This function can be used as the PCM pointer callback for dmaengine based PCM
	* driver implementations.
	*
	* Return: PCM position in frames
	*/
	snd_pcm_uframes_t snd_dmaengine_pcm_pointer(struct snd_pcm_substream *substream)
	{
	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct dma_tx_state state;
	enum dma_status status;
	unsigned int buf_size;
	unsigned int pos = 0;

	status = dmaengine_tx_status(prtd->dma_chan, prtd->cookie, &state);
	if (status == DMA_IN_PROGRESS \|\| status == DMA_PAUSED) {
	buf_size = snd_pcm_lib_buffer_bytes(substream);
	if (state.residue > 0 && state.residue <= buf_size)
	pos = buf_size - state.residue;

	runtime->delay = bytes_to_frames(runtime,
	state.in_flight_bytes);
	}

	return bytes_to_frames(runtime, pos);
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_pointer);

	/**
	* snd_dmaengine_pcm_request_channel - Request channel for the dmaengine PCM
	* @filter_fn: Filter function used to request the DMA channel
	* @filter_data: Data passed to the DMA filter function
	*
	* This function request a DMA channel for usage with dmaengine PCM.
	*
	* Return: NULL or the requested DMA channel
	*/
	struct dma_chan *snd_dmaengine_pcm_request_channel(dma_filter_fn filter_fn,
	void *filter_data)
	{
	dma_cap_mask_t mask;

	dma_cap_zero(mask);
	dma_cap_set(DMA_SLAVE, mask);
	dma_cap_set(DMA_CYCLIC, mask);

	return dma_request_channel(mask, filter_fn, filter_data);
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_request_channel);

	/**
	* snd_dmaengine_pcm_open - Open a dmaengine based PCM substream
	* @substream: PCM substream
	* @chan: DMA channel to use for data transfers
	*
	* The function should usually be called from the pcm open callback. Note that
	* this function will use private_data field of the substream's runtime. So it
	* is not available to your pcm driver implementation.
	*
	* Return: 0 on success, a negative error code otherwise
	*/
	int snd_dmaengine_pcm_open(struct snd_pcm_substream *substream,
	struct dma_chan *chan)
	{
	struct dmaengine_pcm_runtime_data *prtd;
	int ret;

	if (!chan)
	return -ENXIO;

	ret = snd_pcm_hw_constraint_integer(substream->runtime,
	SNDRV_PCM_HW_PARAM_PERIODS);
	if (ret < 0)
	return ret;

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

	prtd->dma_chan = chan;

	substream->runtime->private_data = prtd;

	return 0;
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_open);

	/**
	* snd_dmaengine_pcm_open_request_chan - Open a dmaengine based PCM substream and request channel
	* @substream: PCM substream
	* @filter_fn: Filter function used to request the DMA channel
	* @filter_data: Data passed to the DMA filter function
	*
	* This function will request a DMA channel using the passed filter function and
	* data. The function should usually be called from the pcm open callback. Note
	* that this function will use private_data field of the substream's runtime. So
	* it is not available to your pcm driver implementation.
	*
	* Return: 0 on success, a negative error code otherwise
	*/
	int snd_dmaengine_pcm_open_request_chan(struct snd_pcm_substream *substream,
	dma_filter_fn filter_fn, void *filter_data)
	{
	return snd_dmaengine_pcm_open(substream,
	snd_dmaengine_pcm_request_channel(filter_fn, filter_data));
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_open_request_chan);

	/**
	* snd_dmaengine_pcm_close - Close a dmaengine based PCM substream
	* @substream: PCM substream
	*
	* Return: 0 on success, a negative error code otherwise
	*/
	int snd_dmaengine_pcm_close(struct snd_pcm_substream *substream)
	{
	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);

	dmaengine_synchronize(prtd->dma_chan);
	kfree(prtd);

	return 0;
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_close);

	/**
	* snd_dmaengine_pcm_close_release_chan - Close a dmaengine based PCM
	* substream and release channel
	* @substream: PCM substream
	*
	* Releases the DMA channel associated with the PCM substream.
	*
	* Return: zero if successful, or a negative error code
	*/
	int snd_dmaengine_pcm_close_release_chan(struct snd_pcm_substream *substream)
	{
	struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);

	dmaengine_synchronize(prtd->dma_chan);
	dma_release_channel(prtd->dma_chan);
	kfree(prtd);

	return 0;
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_close_release_chan);

	/**
	* snd_dmaengine_pcm_refine_runtime_hwparams - Refine runtime hw params
	* @substream: PCM substream
	* @dma_data: DAI DMA data
	* @hw: PCM hw params
	* @chan: DMA channel to use for data transfers
	*
	* This function will query DMA capability, then refine the pcm hardware
	* parameters.
	*
	* Return: 0 on success, a negative error code otherwise
	*/
	int snd_dmaengine_pcm_refine_runtime_hwparams(
	struct snd_pcm_substream *substream,
	struct snd_dmaengine_dai_dma_data *dma_data,
	struct snd_pcm_hardware *hw,
	struct dma_chan *chan)
	{
	struct dma_slave_caps dma_caps;
	u32 addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) \|
	BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) \|
	BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
	snd_pcm_format_t i;
	int ret = 0;

	if (!hw \|\| !chan \|\| !dma_data)
	return -EINVAL;

	ret = dma_get_slave_caps(chan, &dma_caps);
	if (ret == 0) {
	if (dma_caps.cmd_pause && dma_caps.cmd_resume)
	hw->info \|= SNDRV_PCM_INFO_PAUSE \| SNDRV_PCM_INFO_RESUME;
	if (dma_caps.residue_granularity <= DMA_RESIDUE_GRANULARITY_SEGMENT)
	hw->info \|= SNDRV_PCM_INFO_BATCH;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
	addr_widths = dma_caps.dst_addr_widths;
	else
	addr_widths = dma_caps.src_addr_widths;
	}

	/*
	* If SND_DMAENGINE_PCM_DAI_FLAG_PACK is set keep
	* hw.formats set to 0, meaning no restrictions are in place.
	* In this case it's the responsibility of the DAI driver to
	* provide the supported format information.
	*/
	if (!(dma_data->flags & SND_DMAENGINE_PCM_DAI_FLAG_PACK))
	/*
	* Prepare formats mask for valid/allowed sample types. If the
	* dma does not have support for the given physical word size,
	* it needs to be masked out so user space can not use the
	* format which produces corrupted audio.
	* In case the dma driver does not implement the slave_caps the
	* default assumption is that it supports 1, 2 and 4 bytes
	* widths.
	*/
	pcm_for_each_format(i) {
	int bits = snd_pcm_format_physical_width(i);

	/*
	* Enable only samples with DMA supported physical
	* widths
	*/
	switch (bits) {
	case 8:
	case 16:
	case 24:
	case 32:
	case 64:
	if (addr_widths & (1 << (bits / 8)))
	hw->formats \|= pcm_format_to_bits(i);
	break;
	default:
	/* Unsupported types */
	break;
	}
	}

	return ret;
	}
	EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_refine_runtime_hwparams);

	MODULE_LICENSE("GPL");