sound/xen/xen_snd_front_cfg.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0 OR MIT

 /*
  * Xen para-virtual sound device
  *
  * Copyright (C) 2016-2018 EPAM Systems Inc.
  *
  * Author: Oleksandr Andrushchenko <[email protected]>
  */

 #include <xen/xenbus.h>

 #include <xen/interface/io/sndif.h>

 #include "xen_snd_front.h"
 #include "xen_snd_front_cfg.h"

 /* Maximum number of supported streams. */
 #define VSND_MAX_STREAM		8

 struct cfg_hw_sample_rate {
 	const char *name;
 	unsigned int mask;
 	unsigned int value;
 };

 static const struct cfg_hw_sample_rate CFG_HW_SUPPORTED_RATES[] = {
 	{ .name = "5512",   .mask = SNDRV_PCM_RATE_5512,   .value = 5512 },
 	{ .name = "8000",   .mask = SNDRV_PCM_RATE_8000,   .value = 8000 },
 	{ .name = "11025",  .mask = SNDRV_PCM_RATE_11025,  .value = 11025 },
 	{ .name = "16000",  .mask = SNDRV_PCM_RATE_16000,  .value = 16000 },
 	{ .name = "22050",  .mask = SNDRV_PCM_RATE_22050,  .value = 22050 },
 	{ .name = "32000",  .mask = SNDRV_PCM_RATE_32000,  .value = 32000 },
 	{ .name = "44100",  .mask = SNDRV_PCM_RATE_44100,  .value = 44100 },
 	{ .name = "48000",  .mask = SNDRV_PCM_RATE_48000,  .value = 48000 },
 	{ .name = "64000",  .mask = SNDRV_PCM_RATE_64000,  .value = 64000 },
 	{ .name = "96000",  .mask = SNDRV_PCM_RATE_96000,  .value = 96000 },
 	{ .name = "176400", .mask = SNDRV_PCM_RATE_176400, .value = 176400 },
 	{ .name = "192000", .mask = SNDRV_PCM_RATE_192000, .value = 192000 },
 };

 struct cfg_hw_sample_format {
 	const char *name;
 	u64 mask;
 };

 static const struct cfg_hw_sample_format CFG_HW_SUPPORTED_FORMATS[] = {
 	{
 		.name = XENSND_PCM_FORMAT_U8_STR,
 		.mask = SNDRV_PCM_FMTBIT_U8
 	},
 	{
 		.name = XENSND_PCM_FORMAT_S8_STR,
 		.mask = SNDRV_PCM_FMTBIT_S8
 	},
 	{
 		.name = XENSND_PCM_FORMAT_U16_LE_STR,
 		.mask = SNDRV_PCM_FMTBIT_U16_LE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_U16_BE_STR,
 		.mask = SNDRV_PCM_FMTBIT_U16_BE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_S16_LE_STR,
 		.mask = SNDRV_PCM_FMTBIT_S16_LE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_S16_BE_STR,
 		.mask = SNDRV_PCM_FMTBIT_S16_BE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_U24_LE_STR,
 		.mask = SNDRV_PCM_FMTBIT_U24_LE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_U24_BE_STR,
 		.mask = SNDRV_PCM_FMTBIT_U24_BE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_S24_LE_STR,
 		.mask = SNDRV_PCM_FMTBIT_S24_LE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_S24_BE_STR,
 		.mask = SNDRV_PCM_FMTBIT_S24_BE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_U32_LE_STR,
 		.mask = SNDRV_PCM_FMTBIT_U32_LE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_U32_BE_STR,
 		.mask = SNDRV_PCM_FMTBIT_U32_BE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_S32_LE_STR,
 		.mask = SNDRV_PCM_FMTBIT_S32_LE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_S32_BE_STR,
 		.mask = SNDRV_PCM_FMTBIT_S32_BE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_A_LAW_STR,
 		.mask = SNDRV_PCM_FMTBIT_A_LAW
 	},
 	{
 		.name = XENSND_PCM_FORMAT_MU_LAW_STR,
 		.mask = SNDRV_PCM_FMTBIT_MU_LAW
 	},
 	{
 		.name = XENSND_PCM_FORMAT_F32_LE_STR,
 		.mask = SNDRV_PCM_FMTBIT_FLOAT_LE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_F32_BE_STR,
 		.mask = SNDRV_PCM_FMTBIT_FLOAT_BE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_F64_LE_STR,
 		.mask = SNDRV_PCM_FMTBIT_FLOAT64_LE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_F64_BE_STR,
 		.mask = SNDRV_PCM_FMTBIT_FLOAT64_BE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_IEC958_SUBFRAME_LE_STR,
 		.mask = SNDRV_PCM_FMTBIT_IEC958_SUBFRAME_LE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_IEC958_SUBFRAME_BE_STR,
 		.mask = SNDRV_PCM_FMTBIT_IEC958_SUBFRAME_BE
 	},
 	{
 		.name = XENSND_PCM_FORMAT_IMA_ADPCM_STR,
 		.mask = SNDRV_PCM_FMTBIT_IMA_ADPCM
 	},
 	{
 		.name = XENSND_PCM_FORMAT_MPEG_STR,
 		.mask = SNDRV_PCM_FMTBIT_MPEG
 	},
 	{
 		.name = XENSND_PCM_FORMAT_GSM_STR,
 		.mask = SNDRV_PCM_FMTBIT_GSM
 	},
 };

 static void cfg_hw_rates(char *list, unsigned int len,
 			 const char *path, struct snd_pcm_hardware *pcm_hw)
 {
 	char *cur_rate;
 	unsigned int cur_mask;
 	unsigned int cur_value;
 	unsigned int rates;
 	unsigned int rate_min;
 	unsigned int rate_max;
 	int i;

 	rates = 0;
 	rate_min = -1;
 	rate_max = 0;
 	while ((cur_rate = strsep(&list, XENSND_LIST_SEPARATOR))) {
 		for (i = 0; i < ARRAY_SIZE(CFG_HW_SUPPORTED_RATES); i++)
 			if (!strncasecmp(cur_rate,
 					 CFG_HW_SUPPORTED_RATES[i].name,
 					 XENSND_SAMPLE_RATE_MAX_LEN)) {
 				cur_mask = CFG_HW_SUPPORTED_RATES[i].mask;
 				cur_value = CFG_HW_SUPPORTED_RATES[i].value;
 				rates |= cur_mask;
 				if (rate_min > cur_value)
 					rate_min = cur_value;
 				if (rate_max < cur_value)
 					rate_max = cur_value;
 			}
 	}

 	if (rates) {
 		pcm_hw->rates = rates;
 		pcm_hw->rate_min = rate_min;
 		pcm_hw->rate_max = rate_max;
 	}
 }

 static void cfg_formats(char *list, unsigned int len,
 			const char *path, struct snd_pcm_hardware *pcm_hw)
 {
 	u64 formats;
 	char *cur_format;
 	int i;

 	formats = 0;
 	while ((cur_format = strsep(&list, XENSND_LIST_SEPARATOR))) {
 		for (i = 0; i < ARRAY_SIZE(CFG_HW_SUPPORTED_FORMATS); i++)
 			if (!strncasecmp(cur_format,
 					 CFG_HW_SUPPORTED_FORMATS[i].name,
 					 XENSND_SAMPLE_FORMAT_MAX_LEN))
 				formats |= CFG_HW_SUPPORTED_FORMATS[i].mask;
 	}

 	if (formats)
 		pcm_hw->formats = formats;
 }

 #define MAX_BUFFER_SIZE		(64 * 1024)
 #define MIN_PERIOD_SIZE		64
 #define MAX_PERIOD_SIZE		MAX_BUFFER_SIZE
 #define USE_FORMATS		(SNDRV_PCM_FMTBIT_U8 | \
 				 SNDRV_PCM_FMTBIT_S16_LE)
 #define USE_RATE		(SNDRV_PCM_RATE_CONTINUOUS | \
 				 SNDRV_PCM_RATE_8000_48000)
 #define USE_RATE_MIN		5512
 #define USE_RATE_MAX		48000
 #define USE_CHANNELS_MIN	1
 #define USE_CHANNELS_MAX	2
 #define USE_PERIODS_MIN		2
 #define USE_PERIODS_MAX		(MAX_BUFFER_SIZE / MIN_PERIOD_SIZE)

 static const struct snd_pcm_hardware SND_DRV_PCM_HW_DEFAULT = {
 	.info = (SNDRV_PCM_INFO_MMAP |
 		 SNDRV_PCM_INFO_INTERLEAVED |
 		 SNDRV_PCM_INFO_RESUME |
 		 SNDRV_PCM_INFO_MMAP_VALID),
 	.formats = USE_FORMATS,
 	.rates = USE_RATE,
 	.rate_min = USE_RATE_MIN,
 	.rate_max = USE_RATE_MAX,
 	.channels_min = USE_CHANNELS_MIN,
 	.channels_max = USE_CHANNELS_MAX,
 	.buffer_bytes_max = MAX_BUFFER_SIZE,
 	.period_bytes_min = MIN_PERIOD_SIZE,
 	.period_bytes_max = MAX_PERIOD_SIZE,
 	.periods_min = USE_PERIODS_MIN,
 	.periods_max = USE_PERIODS_MAX,
 	.fifo_size = 0,
 };

 static void cfg_read_pcm_hw(const char *path,
 			    struct snd_pcm_hardware *parent_pcm_hw,
 			    struct snd_pcm_hardware *pcm_hw)
 {
 	char *list;
 	int val;
 	size_t buf_sz;
 	unsigned int len;

 	/* Inherit parent's PCM HW and read overrides from XenStore. */
 	if (parent_pcm_hw)
 		*pcm_hw = *parent_pcm_hw;
 	else
 		*pcm_hw = SND_DRV_PCM_HW_DEFAULT;

 	val = xenbus_read_unsigned(path, XENSND_FIELD_CHANNELS_MIN, 0);
 	if (val)
 		pcm_hw->channels_min = val;

 	val = xenbus_read_unsigned(path, XENSND_FIELD_CHANNELS_MAX, 0);
 	if (val)
 		pcm_hw->channels_max = val;

 	list = xenbus_read(XBT_NIL, path, XENSND_FIELD_SAMPLE_RATES, &len);
 	if (!IS_ERR(list)) {
 		cfg_hw_rates(list, len, path, pcm_hw);
 		kfree(list);
 	}

 	list = xenbus_read(XBT_NIL, path, XENSND_FIELD_SAMPLE_FORMATS, &len);
 	if (!IS_ERR(list)) {
 		cfg_formats(list, len, path, pcm_hw);
 		kfree(list);
 	}

 	buf_sz = xenbus_read_unsigned(path, XENSND_FIELD_BUFFER_SIZE, 0);
 	if (buf_sz)
 		pcm_hw->buffer_bytes_max = buf_sz;

 	/* Update configuration to match new values. */
 	if (pcm_hw->channels_min > pcm_hw->channels_max)
 		pcm_hw->channels_min = pcm_hw->channels_max;

 	if (pcm_hw->rate_min > pcm_hw->rate_max)
 		pcm_hw->rate_min = pcm_hw->rate_max;

 	pcm_hw->period_bytes_max = pcm_hw->buffer_bytes_max;

 	pcm_hw->periods_max = pcm_hw->period_bytes_max /
 		pcm_hw->period_bytes_min;
 }

 static int cfg_get_stream_type(const char *path, int index,
 			       int *num_pb, int *num_cap)
 {
 	char *str = NULL;
 	char *stream_path;
 	int ret;

 	*num_pb = 0;
 	*num_cap = 0;
 	stream_path = kasprintf(GFP_KERNEL, "%s/%d", path, index);
 	if (!stream_path) {
 		ret = -ENOMEM;
 		goto fail;
 	}

 	str = xenbus_read(XBT_NIL, stream_path, XENSND_FIELD_TYPE, NULL);
 	if (IS_ERR(str)) {
 		ret = PTR_ERR(str);
 		str = NULL;
 		goto fail;
 	}

 	if (!strncasecmp(str, XENSND_STREAM_TYPE_PLAYBACK,
 			 sizeof(XENSND_STREAM_TYPE_PLAYBACK))) {
 		(*num_pb)++;
 	} else if (!strncasecmp(str, XENSND_STREAM_TYPE_CAPTURE,
 			      sizeof(XENSND_STREAM_TYPE_CAPTURE))) {
 		(*num_cap)++;
 	} else {
 		ret = -EINVAL;
 		goto fail;
 	}
 	ret = 0;

 fail:
 	kfree(stream_path);
 	kfree(str);
 	return ret;
 }

 static int cfg_stream(struct xen_snd_front_info *front_info,
 		      struct xen_front_cfg_pcm_instance *pcm_instance,
 		      const char *path, int index, int *cur_pb, int *cur_cap,
 		      int *stream_cnt)
 {
 	char *str = NULL;
 	char *stream_path;
 	struct xen_front_cfg_stream *stream;
 	int ret;

 	stream_path = devm_kasprintf(&front_info->xb_dev->dev,
 				     GFP_KERNEL, "%s/%d", path, index);
 	if (!stream_path) {
 		ret = -ENOMEM;
 		goto fail;
 	}

 	str = xenbus_read(XBT_NIL, stream_path, XENSND_FIELD_TYPE, NULL);
 	if (IS_ERR(str)) {
 		ret = PTR_ERR(str);
 		str = NULL;
 		goto fail;
 	}

 	if (!strncasecmp(str, XENSND_STREAM_TYPE_PLAYBACK,
 			 sizeof(XENSND_STREAM_TYPE_PLAYBACK))) {
 		stream = &pcm_instance->streams_pb[(*cur_pb)++];
 	} else if (!strncasecmp(str, XENSND_STREAM_TYPE_CAPTURE,
 			      sizeof(XENSND_STREAM_TYPE_CAPTURE))) {
 		stream = &pcm_instance->streams_cap[(*cur_cap)++];
 	} else {
 		ret = -EINVAL;
 		goto fail;
 	}

 	/* Get next stream index. */
 	stream->index = (*stream_cnt)++;
 	stream->xenstore_path = stream_path;
 	/*
 	 * Check XenStore if PCM HW configuration exists for this stream
 	 * and update if so, e.g. we inherit all values from device's PCM HW,
 	 * but can still override some of the values for the stream.
 	 */
 	cfg_read_pcm_hw(stream->xenstore_path,
 			&pcm_instance->pcm_hw, &stream->pcm_hw);
 	ret = 0;

 fail:
 	kfree(str);
 	return ret;
 }

 static int cfg_device(struct xen_snd_front_info *front_info,
 		      struct xen_front_cfg_pcm_instance *pcm_instance,
 		      struct snd_pcm_hardware *parent_pcm_hw,
 		      const char *path, int node_index, int *stream_cnt)
 {
 	char *str;
 	char *device_path;
 	int ret, i, num_streams;
 	int num_pb, num_cap;
 	int cur_pb, cur_cap;
 	char node[3];

 	device_path = kasprintf(GFP_KERNEL, "%s/%d", path, node_index);
 	if (!device_path)
 		return -ENOMEM;

 	str = xenbus_read(XBT_NIL, device_path, XENSND_FIELD_DEVICE_NAME, NULL);
 	if (!IS_ERR(str)) {
 		strlcpy(pcm_instance->name, str, sizeof(pcm_instance->name));
 		kfree(str);
 	}

 	pcm_instance->device_id = node_index;

 	/*
 	 * Check XenStore if PCM HW configuration exists for this device
 	 * and update if so, e.g. we inherit all values from card's PCM HW,
 	 * but can still override some of the values for the device.
 	 */
 	cfg_read_pcm_hw(device_path, parent_pcm_hw, &pcm_instance->pcm_hw);

 	/* Find out how many streams were configured in Xen store. */
 	num_streams = 0;
 	do {
 		snprintf(node, sizeof(node), "%d", num_streams);
 		if (!xenbus_exists(XBT_NIL, device_path, node))
 			break;

 		num_streams++;
 	} while (num_streams < VSND_MAX_STREAM);

 	pcm_instance->num_streams_pb = 0;
 	pcm_instance->num_streams_cap = 0;
 	/* Get number of playback and capture streams. */
 	for (i = 0; i < num_streams; i++) {
 		ret = cfg_get_stream_type(device_path, i, &num_pb, &num_cap);
 		if (ret < 0)
 			goto fail;

 		pcm_instance->num_streams_pb += num_pb;
 		pcm_instance->num_streams_cap += num_cap;
 	}

 	if (pcm_instance->num_streams_pb) {
 		pcm_instance->streams_pb =
 				devm_kcalloc(&front_info->xb_dev->dev,
 					     pcm_instance->num_streams_pb,
 					     sizeof(struct xen_front_cfg_stream),
 					     GFP_KERNEL);
 		if (!pcm_instance->streams_pb) {
 			ret = -ENOMEM;
 			goto fail;
 		}
 	}

 	if (pcm_instance->num_streams_cap) {
 		pcm_instance->streams_cap =
 				devm_kcalloc(&front_info->xb_dev->dev,
 					     pcm_instance->num_streams_cap,
 					     sizeof(struct xen_front_cfg_stream),
 					     GFP_KERNEL);
 		if (!pcm_instance->streams_cap) {
 			ret = -ENOMEM;
 			goto fail;
 		}
 	}

 	cur_pb = 0;
 	cur_cap = 0;
 	for (i = 0; i < num_streams; i++) {
 		ret = cfg_stream(front_info, pcm_instance, device_path, i,
 				 &cur_pb, &cur_cap, stream_cnt);
 		if (ret < 0)
 			goto fail;
 	}
 	ret = 0;

 fail:
 	kfree(device_path);
 	return ret;
 }

 int xen_snd_front_cfg_card(struct xen_snd_front_info *front_info,
 			   int *stream_cnt)
 {
 	struct xenbus_device *xb_dev = front_info->xb_dev;
 	struct xen_front_cfg_card *cfg = &front_info->cfg;
 	int ret, num_devices, i;
 	char node[3];

 	*stream_cnt = 0;
 	num_devices = 0;
 	do {
 		snprintf(node, sizeof(node), "%d", num_devices);
 		if (!xenbus_exists(XBT_NIL, xb_dev->nodename, node))
 			break;

 		num_devices++;
 	} while (num_devices < SNDRV_PCM_DEVICES);

 	if (!num_devices) {
 		dev_warn(&xb_dev->dev,
 			 "No devices configured for sound card at %s\n",
 			 xb_dev->nodename);
 		return -ENODEV;
 	}

 	/* Start from default PCM HW configuration for the card. */
 	cfg_read_pcm_hw(xb_dev->nodename, NULL, &cfg->pcm_hw);

 	cfg->pcm_instances =
 			devm_kcalloc(&front_info->xb_dev->dev, num_devices,
 				     sizeof(struct xen_front_cfg_pcm_instance),
 				     GFP_KERNEL);
 	if (!cfg->pcm_instances)
 		return -ENOMEM;

 	for (i = 0; i < num_devices; i++) {
 		ret = cfg_device(front_info, &cfg->pcm_instances[i],
 				 &cfg->pcm_hw, xb_dev->nodename, i, stream_cnt);
 		if (ret < 0)
 			return ret;
 	}
 	cfg->num_pcm_instances = num_devices;
 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0 OR MIT

	/*
	* Xen para-virtual sound device
	*
	* Copyright (C) 2016-2018 EPAM Systems Inc.
	*
	* Author: Oleksandr Andrushchenko <[email protected]>
	*/

	#include <xen/xenbus.h>

	#include <xen/interface/io/sndif.h>

	#include "xen_snd_front.h"
	#include "xen_snd_front_cfg.h"

	/* Maximum number of supported streams. */
	#define VSND_MAX_STREAM 8

	struct cfg_hw_sample_rate {
	const char *name;
	unsigned int mask;
	unsigned int value;
	};

	static const struct cfg_hw_sample_rate CFG_HW_SUPPORTED_RATES[] = {
	{ .name = "5512", .mask = SNDRV_PCM_RATE_5512, .value = 5512 },
	{ .name = "8000", .mask = SNDRV_PCM_RATE_8000, .value = 8000 },
	{ .name = "11025", .mask = SNDRV_PCM_RATE_11025, .value = 11025 },
	{ .name = "16000", .mask = SNDRV_PCM_RATE_16000, .value = 16000 },
	{ .name = "22050", .mask = SNDRV_PCM_RATE_22050, .value = 22050 },
	{ .name = "32000", .mask = SNDRV_PCM_RATE_32000, .value = 32000 },
	{ .name = "44100", .mask = SNDRV_PCM_RATE_44100, .value = 44100 },
	{ .name = "48000", .mask = SNDRV_PCM_RATE_48000, .value = 48000 },
	{ .name = "64000", .mask = SNDRV_PCM_RATE_64000, .value = 64000 },
	{ .name = "96000", .mask = SNDRV_PCM_RATE_96000, .value = 96000 },
	{ .name = "176400", .mask = SNDRV_PCM_RATE_176400, .value = 176400 },
	{ .name = "192000", .mask = SNDRV_PCM_RATE_192000, .value = 192000 },
	};

	struct cfg_hw_sample_format {
	const char *name;
	u64 mask;
	};

	static const struct cfg_hw_sample_format CFG_HW_SUPPORTED_FORMATS[] = {
	{
	.name = XENSND_PCM_FORMAT_U8_STR,
	.mask = SNDRV_PCM_FMTBIT_U8
	},
	{
	.name = XENSND_PCM_FORMAT_S8_STR,
	.mask = SNDRV_PCM_FMTBIT_S8
	},
	{
	.name = XENSND_PCM_FORMAT_U16_LE_STR,
	.mask = SNDRV_PCM_FMTBIT_U16_LE
	},
	{
	.name = XENSND_PCM_FORMAT_U16_BE_STR,
	.mask = SNDRV_PCM_FMTBIT_U16_BE
	},
	{
	.name = XENSND_PCM_FORMAT_S16_LE_STR,
	.mask = SNDRV_PCM_FMTBIT_S16_LE
	},
	{
	.name = XENSND_PCM_FORMAT_S16_BE_STR,
	.mask = SNDRV_PCM_FMTBIT_S16_BE
	},
	{
	.name = XENSND_PCM_FORMAT_U24_LE_STR,
	.mask = SNDRV_PCM_FMTBIT_U24_LE
	},
	{
	.name = XENSND_PCM_FORMAT_U24_BE_STR,
	.mask = SNDRV_PCM_FMTBIT_U24_BE
	},
	{
	.name = XENSND_PCM_FORMAT_S24_LE_STR,
	.mask = SNDRV_PCM_FMTBIT_S24_LE
	},
	{
	.name = XENSND_PCM_FORMAT_S24_BE_STR,
	.mask = SNDRV_PCM_FMTBIT_S24_BE
	},
	{
	.name = XENSND_PCM_FORMAT_U32_LE_STR,
	.mask = SNDRV_PCM_FMTBIT_U32_LE
	},
	{
	.name = XENSND_PCM_FORMAT_U32_BE_STR,
	.mask = SNDRV_PCM_FMTBIT_U32_BE
	},
	{
	.name = XENSND_PCM_FORMAT_S32_LE_STR,
	.mask = SNDRV_PCM_FMTBIT_S32_LE
	},
	{
	.name = XENSND_PCM_FORMAT_S32_BE_STR,
	.mask = SNDRV_PCM_FMTBIT_S32_BE
	},
	{
	.name = XENSND_PCM_FORMAT_A_LAW_STR,
	.mask = SNDRV_PCM_FMTBIT_A_LAW
	},
	{
	.name = XENSND_PCM_FORMAT_MU_LAW_STR,
	.mask = SNDRV_PCM_FMTBIT_MU_LAW
	},
	{
	.name = XENSND_PCM_FORMAT_F32_LE_STR,
	.mask = SNDRV_PCM_FMTBIT_FLOAT_LE
	},
	{
	.name = XENSND_PCM_FORMAT_F32_BE_STR,
	.mask = SNDRV_PCM_FMTBIT_FLOAT_BE
	},
	{
	.name = XENSND_PCM_FORMAT_F64_LE_STR,
	.mask = SNDRV_PCM_FMTBIT_FLOAT64_LE
	},
	{
	.name = XENSND_PCM_FORMAT_F64_BE_STR,
	.mask = SNDRV_PCM_FMTBIT_FLOAT64_BE
	},
	{
	.name = XENSND_PCM_FORMAT_IEC958_SUBFRAME_LE_STR,
	.mask = SNDRV_PCM_FMTBIT_IEC958_SUBFRAME_LE
	},
	{
	.name = XENSND_PCM_FORMAT_IEC958_SUBFRAME_BE_STR,
	.mask = SNDRV_PCM_FMTBIT_IEC958_SUBFRAME_BE
	},
	{
	.name = XENSND_PCM_FORMAT_IMA_ADPCM_STR,
	.mask = SNDRV_PCM_FMTBIT_IMA_ADPCM
	},
	{
	.name = XENSND_PCM_FORMAT_MPEG_STR,
	.mask = SNDRV_PCM_FMTBIT_MPEG
	},
	{
	.name = XENSND_PCM_FORMAT_GSM_STR,
	.mask = SNDRV_PCM_FMTBIT_GSM
	},
	};

	static void cfg_hw_rates(char *list, unsigned int len,
	const char path, struct snd_pcm_hardware pcm_hw)
	{
	char *cur_rate;
	unsigned int cur_mask;
	unsigned int cur_value;
	unsigned int rates;
	unsigned int rate_min;
	unsigned int rate_max;
	int i;

	rates = 0;
	rate_min = -1;
	rate_max = 0;
	while ((cur_rate = strsep(&list, XENSND_LIST_SEPARATOR))) {
	for (i = 0; i < ARRAY_SIZE(CFG_HW_SUPPORTED_RATES); i++)
	if (!strncasecmp(cur_rate,
	CFG_HW_SUPPORTED_RATES[i].name,
	XENSND_SAMPLE_RATE_MAX_LEN)) {
	cur_mask = CFG_HW_SUPPORTED_RATES[i].mask;
	cur_value = CFG_HW_SUPPORTED_RATES[i].value;
	rates \|= cur_mask;
	if (rate_min > cur_value)
	rate_min = cur_value;
	if (rate_max < cur_value)
	rate_max = cur_value;
	}
	}

	if (rates) {
	pcm_hw->rates = rates;
	pcm_hw->rate_min = rate_min;
	pcm_hw->rate_max = rate_max;
	}
	}

	static void cfg_formats(char *list, unsigned int len,
	const char path, struct snd_pcm_hardware pcm_hw)
	{
	u64 formats;
	char *cur_format;
	int i;

	formats = 0;
	while ((cur_format = strsep(&list, XENSND_LIST_SEPARATOR))) {
	for (i = 0; i < ARRAY_SIZE(CFG_HW_SUPPORTED_FORMATS); i++)
	if (!strncasecmp(cur_format,
	CFG_HW_SUPPORTED_FORMATS[i].name,
	XENSND_SAMPLE_FORMAT_MAX_LEN))
	formats \|= CFG_HW_SUPPORTED_FORMATS[i].mask;
	}

	if (formats)
	pcm_hw->formats = formats;
	}

	#define MAX_BUFFER_SIZE (64 * 1024)
	#define MIN_PERIOD_SIZE 64
	#define MAX_PERIOD_SIZE MAX_BUFFER_SIZE
	#define USE_FORMATS (SNDRV_PCM_FMTBIT_U8 \| \
	SNDRV_PCM_FMTBIT_S16_LE)
	#define USE_RATE (SNDRV_PCM_RATE_CONTINUOUS \| \
	SNDRV_PCM_RATE_8000_48000)
	#define USE_RATE_MIN 5512
	#define USE_RATE_MAX 48000
	#define USE_CHANNELS_MIN 1
	#define USE_CHANNELS_MAX 2
	#define USE_PERIODS_MIN 2
	#define USE_PERIODS_MAX (MAX_BUFFER_SIZE / MIN_PERIOD_SIZE)

	static const struct snd_pcm_hardware SND_DRV_PCM_HW_DEFAULT = {
	.info = (SNDRV_PCM_INFO_MMAP \|
	SNDRV_PCM_INFO_INTERLEAVED \|
	SNDRV_PCM_INFO_RESUME \|
	SNDRV_PCM_INFO_MMAP_VALID),
	.formats = USE_FORMATS,
	.rates = USE_RATE,
	.rate_min = USE_RATE_MIN,
	.rate_max = USE_RATE_MAX,
	.channels_min = USE_CHANNELS_MIN,
	.channels_max = USE_CHANNELS_MAX,
	.buffer_bytes_max = MAX_BUFFER_SIZE,
	.period_bytes_min = MIN_PERIOD_SIZE,
	.period_bytes_max = MAX_PERIOD_SIZE,
	.periods_min = USE_PERIODS_MIN,
	.periods_max = USE_PERIODS_MAX,
	.fifo_size = 0,
	};

	static void cfg_read_pcm_hw(const char *path,
	struct snd_pcm_hardware *parent_pcm_hw,
	struct snd_pcm_hardware *pcm_hw)
	{
	char *list;
	int val;
	size_t buf_sz;
	unsigned int len;

	/* Inherit parent's PCM HW and read overrides from XenStore. */
	if (parent_pcm_hw)
	pcm_hw = parent_pcm_hw;
	else
	*pcm_hw = SND_DRV_PCM_HW_DEFAULT;

	val = xenbus_read_unsigned(path, XENSND_FIELD_CHANNELS_MIN, 0);
	if (val)
	pcm_hw->channels_min = val;

	val = xenbus_read_unsigned(path, XENSND_FIELD_CHANNELS_MAX, 0);
	if (val)
	pcm_hw->channels_max = val;

	list = xenbus_read(XBT_NIL, path, XENSND_FIELD_SAMPLE_RATES, &len);
	if (!IS_ERR(list)) {
	cfg_hw_rates(list, len, path, pcm_hw);
	kfree(list);
	}

	list = xenbus_read(XBT_NIL, path, XENSND_FIELD_SAMPLE_FORMATS, &len);
	if (!IS_ERR(list)) {
	cfg_formats(list, len, path, pcm_hw);
	kfree(list);
	}

	buf_sz = xenbus_read_unsigned(path, XENSND_FIELD_BUFFER_SIZE, 0);
	if (buf_sz)
	pcm_hw->buffer_bytes_max = buf_sz;

	/* Update configuration to match new values. */
	if (pcm_hw->channels_min > pcm_hw->channels_max)
	pcm_hw->channels_min = pcm_hw->channels_max;

	if (pcm_hw->rate_min > pcm_hw->rate_max)
	pcm_hw->rate_min = pcm_hw->rate_max;

	pcm_hw->period_bytes_max = pcm_hw->buffer_bytes_max;

	pcm_hw->periods_max = pcm_hw->period_bytes_max /
	pcm_hw->period_bytes_min;
	}

	static int cfg_get_stream_type(const char *path, int index,
	int num_pb, int num_cap)
	{
	char *str = NULL;
	char *stream_path;
	int ret;

	*num_pb = 0;
	*num_cap = 0;
	stream_path = kasprintf(GFP_KERNEL, "%s/%d", path, index);
	if (!stream_path) {
	ret = -ENOMEM;
	goto fail;
	}

	str = xenbus_read(XBT_NIL, stream_path, XENSND_FIELD_TYPE, NULL);
	if (IS_ERR(str)) {
	ret = PTR_ERR(str);
	str = NULL;
	goto fail;
	}

	if (!strncasecmp(str, XENSND_STREAM_TYPE_PLAYBACK,
	sizeof(XENSND_STREAM_TYPE_PLAYBACK))) {
	(*num_pb)++;
	} else if (!strncasecmp(str, XENSND_STREAM_TYPE_CAPTURE,
	sizeof(XENSND_STREAM_TYPE_CAPTURE))) {
	(*num_cap)++;
	} else {
	ret = -EINVAL;
	goto fail;
	}
	ret = 0;

	fail:
	kfree(stream_path);
	kfree(str);
	return ret;
	}

	static int cfg_stream(struct xen_snd_front_info *front_info,
	struct xen_front_cfg_pcm_instance *pcm_instance,
	const char path, int index, int cur_pb, int *cur_cap,
	int *stream_cnt)
	{
	char *str = NULL;
	char *stream_path;
	struct xen_front_cfg_stream *stream;
	int ret;

	stream_path = devm_kasprintf(&front_info->xb_dev->dev,
	GFP_KERNEL, "%s/%d", path, index);
	if (!stream_path) {
	ret = -ENOMEM;
	goto fail;
	}

	str = xenbus_read(XBT_NIL, stream_path, XENSND_FIELD_TYPE, NULL);
	if (IS_ERR(str)) {
	ret = PTR_ERR(str);
	str = NULL;
	goto fail;
	}

	if (!strncasecmp(str, XENSND_STREAM_TYPE_PLAYBACK,
	sizeof(XENSND_STREAM_TYPE_PLAYBACK))) {
	stream = &pcm_instance->streams_pb[(*cur_pb)++];
	} else if (!strncasecmp(str, XENSND_STREAM_TYPE_CAPTURE,
	sizeof(XENSND_STREAM_TYPE_CAPTURE))) {
	stream = &pcm_instance->streams_cap[(*cur_cap)++];
	} else {
	ret = -EINVAL;
	goto fail;
	}

	/* Get next stream index. */
	stream->index = (*stream_cnt)++;
	stream->xenstore_path = stream_path;
	/*
	* Check XenStore if PCM HW configuration exists for this stream
	* and update if so, e.g. we inherit all values from device's PCM HW,
	* but can still override some of the values for the stream.
	*/
	cfg_read_pcm_hw(stream->xenstore_path,
	&pcm_instance->pcm_hw, &stream->pcm_hw);
	ret = 0;

	fail:
	kfree(str);
	return ret;
	}

	static int cfg_device(struct xen_snd_front_info *front_info,
	struct xen_front_cfg_pcm_instance *pcm_instance,
	struct snd_pcm_hardware *parent_pcm_hw,
	const char path, int node_index, int stream_cnt)
	{
	char *str;
	char *device_path;
	int ret, i, num_streams;
	int num_pb, num_cap;
	int cur_pb, cur_cap;
	char node[3];

	device_path = kasprintf(GFP_KERNEL, "%s/%d", path, node_index);
	if (!device_path)
	return -ENOMEM;

	str = xenbus_read(XBT_NIL, device_path, XENSND_FIELD_DEVICE_NAME, NULL);
	if (!IS_ERR(str)) {
	strlcpy(pcm_instance->name, str, sizeof(pcm_instance->name));
	kfree(str);
	}

	pcm_instance->device_id = node_index;

	/*
	* Check XenStore if PCM HW configuration exists for this device
	* and update if so, e.g. we inherit all values from card's PCM HW,
	* but can still override some of the values for the device.
	*/
	cfg_read_pcm_hw(device_path, parent_pcm_hw, &pcm_instance->pcm_hw);

	/* Find out how many streams were configured in Xen store. */
	num_streams = 0;
	do {
	snprintf(node, sizeof(node), "%d", num_streams);
	if (!xenbus_exists(XBT_NIL, device_path, node))
	break;

	num_streams++;
	} while (num_streams < VSND_MAX_STREAM);

	pcm_instance->num_streams_pb = 0;
	pcm_instance->num_streams_cap = 0;
	/* Get number of playback and capture streams. */
	for (i = 0; i < num_streams; i++) {
	ret = cfg_get_stream_type(device_path, i, &num_pb, &num_cap);
	if (ret < 0)
	goto fail;

	pcm_instance->num_streams_pb += num_pb;
	pcm_instance->num_streams_cap += num_cap;
	}

	if (pcm_instance->num_streams_pb) {
	pcm_instance->streams_pb =
	devm_kcalloc(&front_info->xb_dev->dev,
	pcm_instance->num_streams_pb,
	sizeof(struct xen_front_cfg_stream),
	GFP_KERNEL);
	if (!pcm_instance->streams_pb) {
	ret = -ENOMEM;
	goto fail;
	}
	}

	if (pcm_instance->num_streams_cap) {
	pcm_instance->streams_cap =
	devm_kcalloc(&front_info->xb_dev->dev,
	pcm_instance->num_streams_cap,
	sizeof(struct xen_front_cfg_stream),
	GFP_KERNEL);
	if (!pcm_instance->streams_cap) {
	ret = -ENOMEM;
	goto fail;
	}
	}

	cur_pb = 0;
	cur_cap = 0;
	for (i = 0; i < num_streams; i++) {
	ret = cfg_stream(front_info, pcm_instance, device_path, i,
	&cur_pb, &cur_cap, stream_cnt);
	if (ret < 0)
	goto fail;
	}
	ret = 0;

	fail:
	kfree(device_path);
	return ret;
	}

	int xen_snd_front_cfg_card(struct xen_snd_front_info *front_info,
	int *stream_cnt)
	{
	struct xenbus_device *xb_dev = front_info->xb_dev;
	struct xen_front_cfg_card *cfg = &front_info->cfg;
	int ret, num_devices, i;
	char node[3];

	*stream_cnt = 0;
	num_devices = 0;
	do {
	snprintf(node, sizeof(node), "%d", num_devices);
	if (!xenbus_exists(XBT_NIL, xb_dev->nodename, node))
	break;

	num_devices++;
	} while (num_devices < SNDRV_PCM_DEVICES);

	if (!num_devices) {
	dev_warn(&xb_dev->dev,
	"No devices configured for sound card at %s\n",
	xb_dev->nodename);
	return -ENODEV;
	}

	/* Start from default PCM HW configuration for the card. */
	cfg_read_pcm_hw(xb_dev->nodename, NULL, &cfg->pcm_hw);

	cfg->pcm_instances =
	devm_kcalloc(&front_info->xb_dev->dev, num_devices,
	sizeof(struct xen_front_cfg_pcm_instance),
	GFP_KERNEL);
	if (!cfg->pcm_instances)
	return -ENOMEM;

	for (i = 0; i < num_devices; i++) {
	ret = cfg_device(front_info, &cfg->pcm_instances[i],
	&cfg->pcm_hw, xb_dev->nodename, i, stream_cnt);
	if (ret < 0)
	return ret;
	}
	cfg->num_pcm_instances = num_devices;
	return 0;
	}