sound/core/pcm_native.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Digital Audio (PCM) abstract layer
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

#include <linux/compat.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/time.h>
#include <linux/pm_qos.h>
#include <linux/io.h>
#include <linux/dma-mapping.h>
#include <linux/vmalloc.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/info.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/timer.h>
#include <sound/minors.h>
#include <linux/uio.h>
#include <linux/delay.h>

#include "pcm_local.h"

#ifdef CONFIG_SND_DEBUG
#define CREATE_TRACE_POINTS
#include "pcm_param_trace.h"
#else
#define trace_hw_mask_param_enabled()		0
#define trace_hw_interval_param_enabled()	0
#define trace_hw_mask_param(substream, type, index, prev, curr)
#define trace_hw_interval_param(substream, type, index, prev, curr)
#endif

/*
 *  Compatibility
 */

struct snd_pcm_hw_params_old {
	unsigned int flags;
	unsigned int masks[SNDRV_PCM_HW_PARAM_SUBFORMAT -
			   SNDRV_PCM_HW_PARAM_ACCESS + 1];
	struct snd_interval intervals[SNDRV_PCM_HW_PARAM_TICK_TIME -
					SNDRV_PCM_HW_PARAM_SAMPLE_BITS + 1];
	unsigned int rmask;
	unsigned int cmask;
	unsigned int info;
	unsigned int msbits;
	unsigned int rate_num;
	unsigned int rate_den;
	snd_pcm_uframes_t fifo_size;
	unsigned char reserved[64];
};

#ifdef CONFIG_SND_SUPPORT_OLD_API
#define SNDRV_PCM_IOCTL_HW_REFINE_OLD _IOWR('A', 0x10, struct snd_pcm_hw_params_old)
#define SNDRV_PCM_IOCTL_HW_PARAMS_OLD _IOWR('A', 0x11, struct snd_pcm_hw_params_old)

static int snd_pcm_hw_refine_old_user(struct snd_pcm_substream *substream,
				      struct snd_pcm_hw_params_old __user * _oparams);
static int snd_pcm_hw_params_old_user(struct snd_pcm_substream *substream,
				      struct snd_pcm_hw_params_old __user * _oparams);
#endif
static int snd_pcm_open(struct file *file, struct snd_pcm *pcm, int stream);

/*
 *
 */

static DECLARE_RWSEM(snd_pcm_link_rwsem);

void snd_pcm_group_init(struct snd_pcm_group *group)
{
	spin_lock_init(&group->lock);
	mutex_init(&group->mutex);
	INIT_LIST_HEAD(&group->substreams);
	refcount_set(&group->refs, 1);
}

/* define group lock helpers */
#define DEFINE_PCM_GROUP_LOCK(action, mutex_action) \
static void snd_pcm_group_ ## action(struct snd_pcm_group *group, bool nonatomic) \
{ \
	if (nonatomic) \
		mutex_ ## mutex_action(&group->mutex); \
	else \
		spin_ ## action(&group->lock); \
}

DEFINE_PCM_GROUP_LOCK(lock, lock);
DEFINE_PCM_GROUP_LOCK(unlock, unlock);
DEFINE_PCM_GROUP_LOCK(lock_irq, lock);
DEFINE_PCM_GROUP_LOCK(unlock_irq, unlock);

/**
 * snd_pcm_stream_lock - Lock the PCM stream
 * @substream: PCM substream
 *
 * This locks the PCM stream's spinlock or mutex depending on the nonatomic
 * flag of the given substream.  This also takes the global link rw lock
 * (or rw sem), too, for avoiding the race with linked streams.
 */
void snd_pcm_stream_lock(struct snd_pcm_substream *substream)
{
	snd_pcm_group_lock(&substream->self_group, substream->pcm->nonatomic);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_lock);

/**
 * snd_pcm_stream_unlock - Unlock the PCM stream
 * @substream: PCM substream
 *
 * This unlocks the PCM stream that has been locked via snd_pcm_stream_lock().
 */
void snd_pcm_stream_unlock(struct snd_pcm_substream *substream)
{
	snd_pcm_group_unlock(&substream->self_group, substream->pcm->nonatomic);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock);

/**
 * snd_pcm_stream_lock_irq - Lock the PCM stream
 * @substream: PCM substream
 *
 * This locks the PCM stream like snd_pcm_stream_lock() and disables the local
 * IRQ (only when nonatomic is false).  In nonatomic case, this is identical
 * as snd_pcm_stream_lock().
 */
void snd_pcm_stream_lock_irq(struct snd_pcm_substream *substream)
{
	snd_pcm_group_lock_irq(&substream->self_group,
			       substream->pcm->nonatomic);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_lock_irq);

static void snd_pcm_stream_lock_nested(struct snd_pcm_substream *substream)
{
	struct snd_pcm_group *group = &substream->self_group;

	if (substream->pcm->nonatomic)
		mutex_lock_nested(&group->mutex, SINGLE_DEPTH_NESTING);
	else
		spin_lock_nested(&group->lock, SINGLE_DEPTH_NESTING);
}

/**
 * snd_pcm_stream_unlock_irq - Unlock the PCM stream
 * @substream: PCM substream
 *
 * This is a counter-part of snd_pcm_stream_lock_irq().
 */
void snd_pcm_stream_unlock_irq(struct snd_pcm_substream *substream)
{
	snd_pcm_group_unlock_irq(&substream->self_group,
				 substream->pcm->nonatomic);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock_irq);

unsigned long _snd_pcm_stream_lock_irqsave(struct snd_pcm_substream *substream)
{
	unsigned long flags = 0;
	if (substream->pcm->nonatomic)
		mutex_lock(&substream->self_group.mutex);
	else
		spin_lock_irqsave(&substream->self_group.lock, flags);
	return flags;
}
EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave);

unsigned long _snd_pcm_stream_lock_irqsave_nested(struct snd_pcm_substream *substream)
{
	unsigned long flags = 0;
	if (substream->pcm->nonatomic)
		mutex_lock_nested(&substream->self_group.mutex,
				  SINGLE_DEPTH_NESTING);
	else
		spin_lock_irqsave_nested(&substream->self_group.lock, flags,
					 SINGLE_DEPTH_NESTING);
	return flags;
}
EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave_nested);

/**
 * snd_pcm_stream_unlock_irqrestore - Unlock the PCM stream
 * @substream: PCM substream
 * @flags: irq flags
 *
 * This is a counter-part of snd_pcm_stream_lock_irqsave().
 */
void snd_pcm_stream_unlock_irqrestore(struct snd_pcm_substream *substream,
				      unsigned long flags)
{
	if (substream->pcm->nonatomic)
		mutex_unlock(&substream->self_group.mutex);
	else
		spin_unlock_irqrestore(&substream->self_group.lock, flags);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock_irqrestore);

/* Run PCM ioctl ops */
static int snd_pcm_ops_ioctl(struct snd_pcm_substream *substream,
			     unsigned cmd, void *arg)
{
	if (substream->ops->ioctl)
		return substream->ops->ioctl(substream, cmd, arg);
	else
		return snd_pcm_lib_ioctl(substream, cmd, arg);
}

int snd_pcm_info(struct snd_pcm_substream *substream, struct snd_pcm_info *info)
{
	struct snd_pcm *pcm = substream->pcm;
	struct snd_pcm_str *pstr = substream->pstr;

	memset(info, 0, sizeof(*info));
	info->card = pcm->card->number;
	info->device = pcm->device;
	info->stream = substream->stream;
	info->subdevice = substream->number;
	strscpy(info->id, pcm->id, sizeof(info->id));
	strscpy(info->name, pcm->name, sizeof(info->name));
	info->dev_class = pcm->dev_class;
	info->dev_subclass = pcm->dev_subclass;
	info->subdevices_count = pstr->substream_count;
	info->subdevices_avail = pstr->substream_count - pstr->substream_opened;
	strscpy(info->subname, substream->name, sizeof(info->subname));

	return 0;
}

int snd_pcm_info_user(struct snd_pcm_substream *substream,
		      struct snd_pcm_info __user * _info)
{
	struct snd_pcm_info *info;
	int err;

	info = kmalloc(sizeof(*info), GFP_KERNEL);
	if (! info)
		return -ENOMEM;
	err = snd_pcm_info(substream, info);
	if (err >= 0) {
		if (copy_to_user(_info, info, sizeof(*info)))
			err = -EFAULT;
	}
	kfree(info);
	return err;
}

/* macro for simplified cast */
#define PARAM_MASK_BIT(b)	(1U << (__force int)(b))

static bool hw_support_mmap(struct snd_pcm_substream *substream)
{
	struct snd_dma_buffer *dmabuf;

	if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_MMAP))
		return false;

	if (substream->ops->mmap || substream->ops->page)
		return true;

	dmabuf = snd_pcm_get_dma_buf(substream);
	if (!dmabuf)
		dmabuf = &substream->dma_buffer;
	switch (dmabuf->dev.type) {
	case SNDRV_DMA_TYPE_UNKNOWN:
		/* we can't know the device, so just assume that the driver does
		 * everything right
		 */
		return true;
	case SNDRV_DMA_TYPE_CONTINUOUS:
	case SNDRV_DMA_TYPE_VMALLOC:
		return true;
	default:
		return dma_can_mmap(dmabuf->dev.dev);
	}
}

static int constrain_mask_params(struct snd_pcm_substream *substream,
				 struct snd_pcm_hw_params *params)
{
	struct snd_pcm_hw_constraints *constrs =
					&substream->runtime->hw_constraints;
	struct snd_mask *m;
	unsigned int k;
	struct snd_mask old_mask __maybe_unused;
	int changed;

	for (k = SNDRV_PCM_HW_PARAM_FIRST_MASK; k <= SNDRV_PCM_HW_PARAM_LAST_MASK; k++) {
		m = hw_param_mask(params, k);
		if (snd_mask_empty(m))
			return -EINVAL;

		/* This parameter is not requested to change by a caller. */
		if (!(params->rmask & PARAM_MASK_BIT(k)))
			continue;

		if (trace_hw_mask_param_enabled())
			old_mask = *m;

		changed = snd_mask_refine(m, constrs_mask(constrs, k));
		if (changed < 0)
			return changed;
		if (changed == 0)
			continue;

		/* Set corresponding flag so that the caller gets it. */
		trace_hw_mask_param(substream, k, 0, &old_mask, m);
		params->cmask |= PARAM_MASK_BIT(k);
	}

	return 0;
}

static int constrain_interval_params(struct snd_pcm_substream *substream,
				     struct snd_pcm_hw_params *params)
{
	struct snd_pcm_hw_constraints *constrs =
					&substream->runtime->hw_constraints;
	struct snd_interval *i;
	unsigned int k;
	struct snd_interval old_interval __maybe_unused;
	int changed;

	for (k = SNDRV_PCM_HW_PARAM_FIRST_INTERVAL; k <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; k++) {
		i = hw_param_interval(params, k);
		if (snd_interval_empty(i))
			return -EINVAL;

		/* This parameter is not requested to change by a caller. */
		if (!(params->rmask & PARAM_MASK_BIT(k)))
			continue;

		if (trace_hw_interval_param_enabled())
			old_interval = *i;

		changed = snd_interval_refine(i, constrs_interval(constrs, k));
		if (changed < 0)
			return changed;
		if (changed == 0)
			continue;

		/* Set corresponding flag so that the caller gets it. */
		trace_hw_interval_param(substream, k, 0, &old_interval, i);
		params->cmask |= PARAM_MASK_BIT(k);
	}

	return 0;
}

static int constrain_params_by_rules(struct snd_pcm_substream *substream,
				     struct snd_pcm_hw_params *params)
{
	struct snd_pcm_hw_constraints *constrs =
					&substream->runtime->hw_constraints;
	unsigned int k;
	unsigned int *rstamps;
	unsigned int vstamps[SNDRV_PCM_HW_PARAM_LAST_INTERVAL + 1];
	unsigned int stamp;
	struct snd_pcm_hw_rule *r;
	unsigned int d;
	struct snd_mask old_mask __maybe_unused;
	struct snd_interval old_interval __maybe_unused;
	bool again;
	int changed, err = 0;

	/*
	 * Each application of rule has own sequence number.
	 *
	 * Each member of 'rstamps' array represents the sequence number of
	 * recent application of corresponding rule.
	 */
	rstamps = kcalloc(constrs->rules_num, sizeof(unsigned int), GFP_KERNEL);
	if (!rstamps)
		return -ENOMEM;

	/*
	 * Each member of 'vstamps' array represents the sequence number of
	 * recent application of rule in which corresponding parameters were
	 * changed.
	 *
	 * In initial state, elements corresponding to parameters requested by
	 * a caller is 1. For unrequested parameters, corresponding members
	 * have 0 so that the parameters are never changed anymore.
	 */
	for (k = 0; k <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; k++)
		vstamps[k] = (params->rmask & PARAM_MASK_BIT(k)) ? 1 : 0;

	/* Due to the above design, actual sequence number starts at 2. */
	stamp = 2;
retry:
	/* Apply all rules in order. */
	again = false;
	for (k = 0; k < constrs->rules_num; k++) {
		r = &constrs->rules[k];

		/*
		 * Check condition bits of this rule. When the rule has
		 * some condition bits, parameter without the bits is
		 * never processed. SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP
		 * is an example of the condition bits.
		 */
		if (r->cond && !(r->cond & params->flags))
			continue;

		/*
		 * The 'deps' array includes maximum four dependencies
		 * to SNDRV_PCM_HW_PARAM_XXXs for this rule. The fifth
		 * member of this array is a sentinel and should be
		 * negative value.
		 *
		 * This rule should be processed in this time when dependent
		 * parameters were changed at former applications of the other
		 * rules.
		 */
		for (d = 0; r->deps[d] >= 0; d++) {
			if (vstamps[r->deps[d]] > rstamps[k])
				break;
		}
		if (r->deps[d] < 0)
			continue;

		if (trace_hw_mask_param_enabled()) {
			if (hw_is_mask(r->var))
				old_mask = *hw_param_mask(params, r->var);
		}
		if (trace_hw_interval_param_enabled()) {
			if (hw_is_interval(r->var))
				old_interval = *hw_param_interval(params, r->var);
		}

		changed = r->func(params, r);
		if (changed < 0) {
			err = changed;
			goto out;
		}

		/*
		 * When the parameter is changed, notify it to the caller
		 * by corresponding returned bit, then preparing for next
		 * iteration.
		 */
		if (changed && r->var >= 0) {
			if (hw_is_mask(r->var)) {
				trace_hw_mask_param(substream, r->var,
					k + 1, &old_mask,
					hw_param_mask(params, r->var));
			}
			if (hw_is_interval(r->var)) {
				trace_hw_interval_param(substream, r->var,
					k + 1, &old_interval,
					hw_param_interval(params, r->var));
			}

			params->cmask |= PARAM_MASK_BIT(r->var);
			vstamps[r->var] = stamp;
			again = true;
		}

		rstamps[k] = stamp++;
	}

	/* Iterate to evaluate all rules till no parameters are changed. */
	if (again)
		goto retry;

 out:
	kfree(rstamps);
	return err;
}

static int fixup_unreferenced_params(struct snd_pcm_substream *substream,
				     struct snd_pcm_hw_params *params)
{
	const struct snd_interval *i;
	const struct snd_mask *m;
	int err;

	if (!params->msbits) {
		i = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_SAMPLE_BITS);
		if (snd_interval_single(i))
			params->msbits = snd_interval_value(i);
	}

	if (!params->rate_den) {
		i = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_RATE);
		if (snd_interval_single(i)) {
			params->rate_num = snd_interval_value(i);
			params->rate_den = 1;
		}
	}

	if (!params->fifo_size) {
		m = hw_param_mask_c(params, SNDRV_PCM_HW_PARAM_FORMAT);
		i = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_CHANNELS);
		if (snd_mask_single(m) && snd_interval_single(i)) {
			err = snd_pcm_ops_ioctl(substream,
						SNDRV_PCM_IOCTL1_FIFO_SIZE,
						params);
			if (err < 0)
				return err;
		}
	}

	if (!params->info) {
		params->info = substream->runtime->hw.info;
		params->info &= ~(SNDRV_PCM_INFO_FIFO_IN_FRAMES |
				  SNDRV_PCM_INFO_DRAIN_TRIGGER);
		if (!hw_support_mmap(substream))
			params->info &= ~(SNDRV_PCM_INFO_MMAP |
					  SNDRV_PCM_INFO_MMAP_VALID);
	}

	return 0;
}

int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
		      struct snd_pcm_hw_params *params)
{
	int err;

	params->info = 0;
	params->fifo_size = 0;
	if (params->rmask & PARAM_MASK_BIT(SNDRV_PCM_HW_PARAM_SAMPLE_BITS))
		params->msbits = 0;
	if (params->rmask & PARAM_MASK_BIT(SNDRV_PCM_HW_PARAM_RATE)) {
		params->rate_num = 0;
		params->rate_den = 0;
	}

	err = constrain_mask_params(substream, params);
	if (err < 0)
		return err;

	err = constrain_interval_params(substream, params);
	if (err < 0)
		return err;

	err = constrain_params_by_rules(substream, params);
	if (err < 0)
		return err;

	params->rmask = 0;

	return 0;
}
EXPORT_SYMBOL(snd_pcm_hw_refine);

static int snd_pcm_hw_refine_user(struct snd_pcm_substream *substream,
				  struct snd_pcm_hw_params __user * _params)
{
	struct snd_pcm_hw_params *params;
	int err;

	params = memdup_user(_params, sizeof(*params));
	if (IS_ERR(params))
		return PTR_ERR(params);

	err = snd_pcm_hw_refine(substream, params);
	if (err < 0)
		goto end;

	err = fixup_unreferenced_params(substream, params);
	if (err < 0)
		goto end;

	if (copy_to_user(_params, params, sizeof(*params)))
		err = -EFAULT;
end:
	kfree(params);
	return err;
}

static int period_to_usecs(struct snd_pcm_runtime *runtime)
{
	int usecs;

	if (! runtime->rate)
		return -1; /* invalid */

	/* take 75% of period time as the deadline */
	usecs = (750000 / runtime->rate) * runtime->period_size;
	usecs += ((750000 % runtime->rate) * runtime->period_size) /
		runtime->rate;

	return usecs;
}

static void snd_pcm_set_state(struct snd_pcm_substream *substream,
			      snd_pcm_state_t state)
{
	snd_pcm_stream_lock_irq(substream);
	if (substream->runtime->state != SNDRV_PCM_STATE_DISCONNECTED)
		__snd_pcm_set_state(substream->runtime, state);
	snd_pcm_stream_unlock_irq(substream);
}

static inline void snd_pcm_timer_notify(struct snd_pcm_substream *substream,
					int event)
{
#ifdef CONFIG_SND_PCM_TIMER
	if (substream->timer)
		snd_timer_notify(substream->timer, event,
					&substream->runtime->trigger_tstamp);
#endif
}

void snd_pcm_sync_stop(struct snd_pcm_substream *substream, bool sync_irq)
{
	if (substream->runtime && substream->runtime->stop_operating) {
		substream->runtime->stop_operating = false;
		if (substream->ops && substream->ops->sync_stop)
			substream->ops->sync_stop(substream);
		else if (sync_irq && substream->pcm->card->sync_irq > 0)
			synchronize_irq(substream->pcm->card->sync_irq);
	}
}

/**
 * snd_pcm_hw_params_choose - choose a configuration defined by @params
 * @pcm: PCM instance
 * @params: the hw_params instance
 *
 * Choose one configuration from configuration space defined by @params.
 * The configuration chosen is that obtained fixing in this order:
 * first access, first format, first subformat, min channels,
 * min rate, min period time, max buffer size, min tick time
 *
 * Return: Zero if successful, or a negative error code on failure.
 */
static int snd_pcm_hw_params_choose(struct snd_pcm_substream *pcm,
				    struct snd_pcm_hw_params *params)
{
	static const int vars[] = {
		SNDRV_PCM_HW_PARAM_ACCESS,
		SNDRV_PCM_HW_PARAM_FORMAT,
		SNDRV_PCM_HW_PARAM_SUBFORMAT,
		SNDRV_PCM_HW_PARAM_CHANNELS,
		SNDRV_PCM_HW_PARAM_RATE,
		SNDRV_PCM_HW_PARAM_PERIOD_TIME,
		SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
		SNDRV_PCM_HW_PARAM_TICK_TIME,
		-1
	};
	const int *v;
	struct snd_mask old_mask __maybe_unused;
	struct snd_interval old_interval __maybe_unused;
	int changed;

	for (v = vars; *v != -1; v++) {
		/* Keep old parameter to trace. */
		if (trace_hw_mask_param_enabled()) {
			if (hw_is_mask(*v))
				old_mask = *hw_param_mask(params, *v);
		}
		if (trace_hw_interval_param_enabled()) {
			if (hw_is_interval(*v))
				old_interval = *hw_param_interval(params, *v);
		}
		if (*v != SNDRV_PCM_HW_PARAM_BUFFER_SIZE)
			changed = snd_pcm_hw_param_first(pcm, params, *v, NULL);
		else
			changed = snd_pcm_hw_param_last(pcm, params, *v, NULL);
		if (changed < 0)
			return changed;
		if (changed == 0)
			continue;

		/* Trace the changed parameter. */
		if (hw_is_mask(*v)) {
			trace_hw_mask_param(pcm, *v, 0, &old_mask,
					    hw_param_mask(params, *v));
		}
		if (hw_is_interval(*v)) {
			trace_hw_interval_param(pcm, *v, 0, &old_interval,
						hw_param_interval(params, *v));
		}
	}

	return 0;
}

/* acquire buffer_mutex; if it's in r/w operation, return -EBUSY, otherwise
 * block the further r/w operations
 */
static int snd_pcm_buffer_access_lock(struct snd_pcm_runtime *runtime)
{
	if (!atomic_dec_unless_positive(&runtime->buffer_accessing))
		return -EBUSY;
	mutex_lock(&runtime->buffer_mutex);
	return 0; /* keep buffer_mutex, unlocked by below */
}

/* release buffer_mutex and clear r/w access flag */
static void snd_pcm_buffer_access_unlock(struct snd_pcm_runtime *runtime)
{
	mutex_unlock(&runtime->buffer_mutex);
	atomic_inc(&runtime->buffer_accessing);
}

#if IS_ENABLED(CONFIG_SND_PCM_OSS)
#define is_oss_stream(substream)	((substream)->oss.oss)
#else
#define is_oss_stream(substream)	false
#endif

static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
			     struct snd_pcm_hw_params *params)
{
	struct snd_pcm_runtime *runtime;
	int err, usecs;
	unsigned int bits;
	snd_pcm_uframes_t frames;

	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	runtime = substream->runtime;
	err = snd_pcm_buffer_access_lock(runtime);
	if (err < 0)
		return err;
	snd_pcm_stream_lock_irq(substream);
	switch (runtime->state) {
	case SNDRV_PCM_STATE_OPEN:
	case SNDRV_PCM_STATE_SETUP:
	case SNDRV_PCM_STATE_PREPARED:
		if (!is_oss_stream(substream) &&
		    atomic_read(&substream->mmap_count))
			err = -EBADFD;
		break;
	default:
		err = -EBADFD;
		break;
	}
	snd_pcm_stream_unlock_irq(substream);
	if (err)
		goto unlock;

	snd_pcm_sync_stop(substream, true);

	params->rmask = ~0U;
	err = snd_pcm_hw_refine(substream, params);
	if (err < 0)
		goto _error;

	err = snd_pcm_hw_params_choose(substream, params);
	if (err < 0)
		goto _error;

	err = fixup_unreferenced_params(substream, params);
	if (err < 0)
		goto _error;

	if (substream->managed_buffer_alloc) {
		err = snd_pcm_lib_malloc_pages(substream,
					       params_buffer_bytes(params));
		if (err < 0)
			goto _error;
		runtime->buffer_changed = err > 0;
	}

	if (substream->ops->hw_params != NULL) {
		err = substream->ops->hw_params(substream, params);
		if (err < 0)
			goto _error;
	}

	runtime->access = params_access(params);
	runtime->format = params_format(params);
	runtime->subformat = params_subformat(params);
	runtime->channels = params_channels(params);
	runtime->rate = params_rate(params);
	runtime->period_size = params_period_size(params);
	runtime->periods = params_periods(params);
	runtime->buffer_size = params_buffer_size(params);
	runtime->info = params->info;
	runtime->rate_num = params->rate_num;
	runtime->rate_den = params->rate_den;
	runtime->no_period_wakeup =
			(params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP) &&
			(params->flags & SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP);

	bits = snd_pcm_format_physical_width(runtime->format);
	runtime->sample_bits = bits;
	bits *= runtime->channels;
	runtime->frame_bits = bits;
	frames = 1;
	while (bits % 8 != 0) {
		bits *= 2;
		frames *= 2;
	}
	runtime->byte_align = bits / 8;
	runtime->min_align = frames;

	/* Default sw params */
	runtime->tstamp_mode = SNDRV_PCM_TSTAMP_NONE;
	runtime->period_step = 1;
	runtime->control->avail_min = runtime->period_size;
	runtime->start_threshold = 1;
	runtime->stop_threshold = runtime->buffer_size;
	runtime->silence_threshold = 0;
	runtime->silence_size = 0;
	runtime->boundary = runtime->buffer_size;
	while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size)
		runtime->boundary *= 2;

	/* clear the buffer for avoiding possible kernel info leaks */
	if (runtime->dma_area && !substream->ops->copy_user) {
		size_t size = runtime->dma_bytes;

		if (runtime->info & SNDRV_PCM_INFO_MMAP)
			size = PAGE_ALIGN(size);
		memset(runtime->dma_area, 0, size);
	}

	snd_pcm_timer_resolution_change(substream);
	snd_pcm_set_state(substream, SNDRV_PCM_STATE_SETUP);

	if (cpu_latency_qos_request_active(&substream->latency_pm_qos_req))
		cpu_latency_qos_remove_request(&substream->latency_pm_qos_req);
	usecs = period_to_usecs(runtime);
	if (usecs >= 0)
		cpu_latency_qos_add_request(&substream->latency_pm_qos_req,
					    usecs);
	err = 0;
 _error:
	if (err) {
		/* hardware might be unusable from this time,
		 * so we force application to retry to set
		 * the correct hardware parameter settings
		 */
		snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
		if (substream->ops->hw_free != NULL)
			substream->ops->hw_free(substream);
		if (substream->managed_buffer_alloc)
			snd_pcm_lib_free_pages(substream);
	}
 unlock:
	snd_pcm_buffer_access_unlock(runtime);
	return err;
}

static int snd_pcm_hw_params_user(struct snd_pcm_substream *substream,
				  struct snd_pcm_hw_params __user * _params)
{
	struct snd_pcm_hw_params *params;
	int err;

	params = memdup_user(_params, sizeof(*params));
	if (IS_ERR(params))
		return PTR_ERR(params);

	err = snd_pcm_hw_params(substream, params);
	if (err < 0)
		goto end;

	if (copy_to_user(_params, params, sizeof(*params)))
		err = -EFAULT;
end:
	kfree(params);
	return err;
}

static int do_hw_free(struct snd_pcm_substream *substream)
{
	int result = 0;

	snd_pcm_sync_stop(substream, true);
	if (substream->ops->hw_free)
		result = substream->ops->hw_free(substream);
	if (substream->managed_buffer_alloc)
		snd_pcm_lib_free_pages(substream);
	return result;
}

static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime;
	int result = 0;

	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	runtime = substream->runtime;
	result = snd_pcm_buffer_access_lock(runtime);
	if (result < 0)
		return result;
	snd_pcm_stream_lock_irq(substream);
	switch (runtime->state) {
	case SNDRV_PCM_STATE_SETUP:
	case SNDRV_PCM_STATE_PREPARED:
		if (atomic_read(&substream->mmap_count))
			result = -EBADFD;
		break;
	default:
		result = -EBADFD;
		break;
	}
	snd_pcm_stream_unlock_irq(substream);
	if (result)
		goto unlock;
	result = do_hw_free(substream);
	snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
	cpu_latency_qos_remove_request(&substream->latency_pm_qos_req);
 unlock:
	snd_pcm_buffer_access_unlock(runtime);
	return result;
}

static int snd_pcm_sw_params(struct snd_pcm_substream *substream,
			     struct snd_pcm_sw_params *params)
{
	struct snd_pcm_runtime *runtime;
	int err;

	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	runtime = substream->runtime;
	snd_pcm_stream_lock_irq(substream);
	if (runtime->state == SNDRV_PCM_STATE_OPEN) {
		snd_pcm_stream_unlock_irq(substream);
		return -EBADFD;
	}
	snd_pcm_stream_unlock_irq(substream);

	if (params->tstamp_mode < 0 ||
	    params->tstamp_mode > SNDRV_PCM_TSTAMP_LAST)
		return -EINVAL;
	if (params->proto >= SNDRV_PROTOCOL_VERSION(2, 0, 12) &&
	    params->tstamp_type > SNDRV_PCM_TSTAMP_TYPE_LAST)
		return -EINVAL;
	if (params->avail_min == 0)
		return -EINVAL;
	if (params->silence_size >= runtime->boundary) {
		if (params->silence_threshold != 0)
			return -EINVAL;
	} else {
		if (params->silence_size > params->silence_threshold)
			return -EINVAL;
		if (params->silence_threshold > runtime->buffer_size)
			return -EINVAL;
	}
	err = 0;
	snd_pcm_stream_lock_irq(substream);
	runtime->tstamp_mode = params->tstamp_mode;
	if (params->proto >= SNDRV_PROTOCOL_VERSION(2, 0, 12))
		runtime->tstamp_type = params->tstamp_type;
	runtime->period_step = params->period_step;
	runtime->control->avail_min = params->avail_min;
	runtime->start_threshold = params->start_threshold;
	runtime->stop_threshold = params->stop_threshold;
	runtime->silence_threshold = params->silence_threshold;
	runtime->silence_size = params->silence_size;
        params->boundary = runtime->boundary;
	if (snd_pcm_running(substream)) {
		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
		    runtime->silence_size > 0)
			snd_pcm_playback_silence(substream, ULONG_MAX);
		err = snd_pcm_update_state(substream, runtime);
	}
	snd_pcm_stream_unlock_irq(substream);
	return err;
}

static int snd_pcm_sw_params_user(struct snd_pcm_substream *substream,
				  struct snd_pcm_sw_params __user * _params)
{
	struct snd_pcm_sw_params params;
	int err;
	if (copy_from_user(&params, _params, sizeof(params)))
		return -EFAULT;
	err = snd_pcm_sw_params(substream, &params);
	if (copy_to_user(_params, &params, sizeof(params)))
		return -EFAULT;
	return err;
}

static inline snd_pcm_uframes_t
snd_pcm_calc_delay(struct snd_pcm_substream *substream)
{
	snd_pcm_uframes_t delay;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
		delay = snd_pcm_playback_hw_avail(substream->runtime);
	else
		delay = snd_pcm_capture_avail(substream->runtime);
	return delay + substream->runtime->delay;
}

int snd_pcm_status64(struct snd_pcm_substream *substream,
		     struct snd_pcm_status64 *status)
{
	struct snd_pcm_runtime *runtime = substream->runtime;

	snd_pcm_stream_lock_irq(substream);

	snd_pcm_unpack_audio_tstamp_config(status->audio_tstamp_data,
					&runtime->audio_tstamp_config);

	/* backwards compatible behavior */
	if (runtime->audio_tstamp_config.type_requested ==
		SNDRV_PCM_AUDIO_TSTAMP_TYPE_COMPAT) {
		if (runtime->hw.info & SNDRV_PCM_INFO_HAS_WALL_CLOCK)
			runtime->audio_tstamp_config.type_requested =
				SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK;
		else
			runtime->audio_tstamp_config.type_requested =
				SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT;
		runtime->audio_tstamp_report.valid = 0;
	} else
		runtime->audio_tstamp_report.valid = 1;

	status->state = runtime->state;
	status->suspended_state = runtime->suspended_state;
	if (status->state == SNDRV_PCM_STATE_OPEN)
		goto _end;
	status->trigger_tstamp_sec = runtime->trigger_tstamp.tv_sec;
	status->trigger_tstamp_nsec = runtime->trigger_tstamp.tv_nsec;
	if (snd_pcm_running(substream)) {
		snd_pcm_update_hw_ptr(substream);
		if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) {
			status->tstamp_sec = runtime->status->tstamp.tv_sec;
			status->tstamp_nsec =
				runtime->status->tstamp.tv_nsec;
			status->driver_tstamp_sec =
				runtime->driver_tstamp.tv_sec;
			status->driver_tstamp_nsec =
				runtime->driver_tstamp.tv_nsec;
			status->audio_tstamp_sec =
				runtime->status->audio_tstamp.tv_sec;
			status->audio_tstamp_nsec =
				runtime->status->audio_tstamp.tv_nsec;
			if (runtime->audio_tstamp_report.valid == 1)
				/* backwards compatibility, no report provided in COMPAT mode */
				snd_pcm_pack_audio_tstamp_report(&status->audio_tstamp_data,
								&status->audio_tstamp_accuracy,
								&runtime->audio_tstamp_report);

			goto _tstamp_end;
		}
	} else {
		/* get tstamp only in fallback mode and only if enabled */
		if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) {
			struct timespec64 tstamp;

			snd_pcm_gettime(runtime, &tstamp);
			status->tstamp_sec = tstamp.tv_sec;
			status->tstamp_nsec = tstamp.tv_nsec;
		}
	}
 _tstamp_end:
	status->appl_ptr = runtime->control->appl_ptr;
	status->hw_ptr = runtime->status->hw_ptr;
	status->avail = snd_pcm_avail(substream);
	status->delay = snd_pcm_running(substream) ?
		snd_pcm_calc_delay(substream) : 0;
	status->avail_max = runtime->avail_max;
	status->overrange = runtime->overrange;
	runtime->avail_max = 0;
	runtime->overrange = 0;
 _end:
 	snd_pcm_stream_unlock_irq(substream);
	return 0;
}

static int snd_pcm_status_user64(struct snd_pcm_substream *substream,
				 struct snd_pcm_status64 __user * _status,
				 bool ext)
{
	struct snd_pcm_status64 status;
	int res;

	memset(&status, 0, sizeof(status));
	/*
	 * with extension, parameters are read/write,
	 * get audio_tstamp_data from user,
	 * ignore rest of status structure
	 */
	if (ext && get_user(status.audio_tstamp_data,
				(u32 __user *)(&_status->audio_tstamp_data)))
		return -EFAULT;
	res = snd_pcm_status64(substream, &status);
	if (res < 0)
		return res;
	if (copy_to_user(_status, &status, sizeof(status)))
		return -EFAULT;
	return 0;
}

static int snd_pcm_status_user32(struct snd_pcm_substream *substream,
				 struct snd_pcm_status32 __user * _status,
				 bool ext)
{
	struct snd_pcm_status64 status64;
	struct snd_pcm_status32 status32;
	int res;

	memset(&status64, 0, sizeof(status64));
	memset(&status32, 0, sizeof(status32));
	/*
	 * with extension, parameters are read/write,
	 * get audio_tstamp_data from user,
	 * ignore rest of status structure
	 */
	if (ext && get_user(status64.audio_tstamp_data,
			    (u32 __user *)(&_status->audio_tstamp_data)))
		return -EFAULT;
	res = snd_pcm_status64(substream, &status64);
	if (res < 0)
		return res;

	status32 = (struct snd_pcm_status32) {
		.state = status64.state,
		.trigger_tstamp_sec = status64.trigger_tstamp_sec,
		.trigger_tstamp_nsec = status64.trigger_tstamp_nsec,
		.tstamp_sec = status64.tstamp_sec,
		.tstamp_nsec = status64.tstamp_nsec,
		.appl_ptr = status64.appl_ptr,
		.hw_ptr = status64.hw_ptr,
		.delay = status64.delay,
		.avail = status64.avail,
		.avail_max = status64.avail_max,
		.overrange = status64.overrange,
		.suspended_state = status64.suspended_state,
		.audio_tstamp_data = status64.audio_tstamp_data,
		.audio_tstamp_sec = status64.audio_tstamp_sec,
		.audio_tstamp_nsec = status64.audio_tstamp_nsec,
		.driver_tstamp_sec = status64.audio_tstamp_sec,
		.driver_tstamp_nsec = status64.audio_tstamp_nsec,
		.audio_tstamp_accuracy = status64.audio_tstamp_accuracy,
	};

	if (copy_to_user(_status, &status32, sizeof(status32)))
		return -EFAULT;

	return 0;
}

static int snd_pcm_channel_info(struct snd_pcm_substream *substream,
				struct snd_pcm_channel_info * info)
{
	struct snd_pcm_runtime *runtime;
	unsigned int channel;
	
	channel = info->channel;
	runtime = substream->runtime;
	snd_pcm_stream_lock_irq(substream);
	if (runtime->state == SNDRV_PCM_STATE_OPEN) {
		snd_pcm_stream_unlock_irq(substream);
		return -EBADFD;
	}
	snd_pcm_stream_unlock_irq(substream);
	if (channel >= runtime->channels)
		return -EINVAL;
	memset(info, 0, sizeof(*info));
	info->channel = channel;
	return snd_pcm_ops_ioctl(substream, SNDRV_PCM_IOCTL1_CHANNEL_INFO, info);
}

static int snd_pcm_channel_info_user(struct snd_pcm_substream *substream,
				     struct snd_pcm_channel_info __user * _info)
{
	struct snd_pcm_channel_info info;
	int res;
	
	if (copy_from_user(&info, _info, sizeof(info)))
		return -EFAULT;
	res = snd_pcm_channel_info(substream, &info);
	if (res < 0)
		return res;
	if (copy_to_user(_info, &info, sizeof(info)))
		return -EFAULT;
	return 0;
}

static void snd_pcm_trigger_tstamp(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	if (runtime->trigger_master == NULL)
		return;
	if (runtime->trigger_master == substream) {
		if (!runtime->trigger_tstamp_latched)
			snd_pcm_gettime(runtime, &runtime->trigger_tstamp);
	} else {
		snd_pcm_trigger_tstamp(runtime->trigger_master);
		runtime->trigger_tstamp = runtime->trigger_master->runtime->trigger_tstamp;
	}
	runtime->trigger_master = NULL;
}

#define ACTION_ARG_IGNORE	(__force snd_pcm_state_t)0

struct action_ops {
	int (*pre_action)(struct snd_pcm_substream *substream,
			  snd_pcm_state_t state);
	int (*do_action)(struct snd_pcm_substream *substream,
			 snd_pcm_state_t state);
	void (*undo_action)(struct snd_pcm_substream *substream,
			    snd_pcm_state_t state);
	void (*post_action)(struct snd_pcm_substream *substream,
			    snd_pcm_state_t state);
};

/*
 *  this functions is core for handling of linked stream
 *  Note: the stream state might be changed also on failure
 *  Note2: call with calling stream lock + link lock
 */
static int snd_pcm_action_group(const struct action_ops *ops,
				struct snd_pcm_substream *substream,
				snd_pcm_state_t state,
				bool stream_lock)
{
	struct snd_pcm_substream *s = NULL;
	struct snd_pcm_substream *s1;
	int res = 0, depth = 1;

	snd_pcm_group_for_each_entry(s, substream) {
		if (s != substream) {
			if (!stream_lock)
				mutex_lock_nested(&s->runtime->buffer_mutex, depth);
			else if (s->pcm->nonatomic)
				mutex_lock_nested(&s->self_group.mutex, depth);
			else
				spin_lock_nested(&s->self_group.lock, depth);
			depth++;
		}
		res = ops->pre_action(s, state);
		if (res < 0)
			goto _unlock;
	}
	snd_pcm_group_for_each_entry(s, substream) {
		res = ops->do_action(s, state);
		if (res < 0) {
			if (ops->undo_action) {
				snd_pcm_group_for_each_entry(s1, substream) {
					if (s1 == s) /* failed stream */
						break;
					ops->undo_action(s1, state);
				}
			}
			s = NULL; /* unlock all */
			goto _unlock;
		}
	}
	snd_pcm_group_for_each_entry(s, substream) {
		ops->post_action(s, state);
	}
 _unlock:
	/* unlock streams */
	snd_pcm_group_for_each_entry(s1, substream) {
		if (s1 != substream) {
			if (!stream_lock)
				mutex_unlock(&s1->runtime->buffer_mutex);
			else if (s1->pcm->nonatomic)
				mutex_unlock(&s1->self_group.mutex);
			else
				spin_unlock(&s1->self_group.lock);
		}
		if (s1 == s)	/* end */
			break;
	}
	return res;
}

/*
 *  Note: call with stream lock
 */
static int snd_pcm_action_single(const struct action_ops *ops,
				 struct snd_pcm_substream *substream,
				 snd_pcm_state_t state)
{
	int res;
	
	res = ops->pre_action(substream, state);
	if (res < 0)
		return res;
	res = ops->do_action(substream, state);
	if (res == 0)
		ops->post_action(substream, state);
	else if (ops->undo_action)
		ops->undo_action(substream, state);
	return res;
}

static void snd_pcm_group_assign(struct snd_pcm_substream *substream,
				 struct snd_pcm_group *new_group)
{
	substream->group = new_group;
	list_move(&substream->link_list, &new_group->substreams);
}

/*
 * Unref and unlock the group, but keep the stream lock;
 * when the group becomes empty and no longer referred, destroy itself
 */
static void snd_pcm_group_unref(struct snd_pcm_group *group,
				struct snd_pcm_substream *substream)
{
	bool do_free;

	if (!group)
		return;
	do_free = refcount_dec_and_test(&group->refs);
	snd_pcm_group_unlock(group, substream->pcm->nonatomic);
	if (do_free)
		kfree(group);
}

/*
 * Lock the group inside a stream lock and reference it;
 * return the locked group object, or NULL if not linked
 */
static struct snd_pcm_group *
snd_pcm_stream_group_ref(struct snd_pcm_substream *substream)
{
	bool nonatomic = substream->pcm->nonatomic;
	struct snd_pcm_group *group;
	bool trylock;

	for (;;) {
		if (!snd_pcm_stream_linked(substream))
			return NULL;
		group = substream->group;
		/* block freeing the group object */
		refcount_inc(&group->refs);

		trylock = nonatomic ? mutex_trylock(&group->mutex) :
			spin_trylock(&group->lock);
		if (trylock)
			break; /* OK */

		/* re-lock for avoiding ABBA deadlock */
		snd_pcm_stream_unlock(substream);
		snd_pcm_group_lock(group, nonatomic);
		snd_pcm_stream_lock(substream);

		/* check the group again; the above opens a small race window */
		if (substream->group == group)
			break; /* OK */
		/* group changed, try again */
		snd_pcm_group_unref(group, substream);
	}
	return group;
}

/*
 *  Note: call with stream lock
 */
static int snd_pcm_action(const struct action_ops *ops,
			  struct snd_pcm_substream *substream,
			  snd_pcm_state_t state)
{
	struct snd_pcm_group *group;
	int res;

	group = snd_pcm_stream_group_ref(substream);
	if (group)
		res = snd_pcm_action_group(ops, substream, state, true);
	else
		res = snd_pcm_action_single(ops, substream, state);
	snd_pcm_group_unref(group, substream);
	return res;
}

/*
 *  Note: don't use any locks before
 */
static int snd_pcm_action_lock_irq(const struct action_ops *ops,
				   struct snd_pcm_substream *substream,
				   snd_pcm_state_t state)
{
	int res;

	snd_pcm_stream_lock_irq(substream);
	res = snd_pcm_action(ops, substream, state);
	snd_pcm_stream_unlock_irq(substream);
	return res;
}

/*
 */
static int snd_pcm_action_nonatomic(const struct action_ops *ops,
				    struct snd_pcm_substream *substream,
				    snd_pcm_state_t state)
{
	int res;

	/* Guarantee the group members won't change during non-atomic action */
	down_read(&snd_pcm_link_rwsem);
	res = snd_pcm_buffer_access_lock(substream->runtime);
	if (res < 0)
		goto unlock;
	if (snd_pcm_stream_linked(substream))
		res = snd_pcm_action_group(ops, substream, state, false);
	else
		res = snd_pcm_action_single(ops, substream, state);
	snd_pcm_buffer_access_unlock(substream->runtime);
 unlock:
	up_read(&snd_pcm_link_rwsem);
	return res;
}

/*
 * start callbacks
 */
static int snd_pcm_pre_start(struct snd_pcm_substream *substream,
			     snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	if (runtime->state != SNDRV_PCM_STATE_PREPARED)
		return -EBADFD;
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
	    !snd_pcm_playback_data(substream))
		return -EPIPE;
	runtime->trigger_tstamp_latched = false;
	runtime->trigger_master = substream;
	return 0;
}

static int snd_pcm_do_start(struct snd_pcm_substream *substream,
			    snd_pcm_state_t state)
{
	int err;

	if (substream->runtime->trigger_master != substream)
		return 0;
	err = substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_START);
	/* XRUN happened during the start */
	if (err == -EPIPE)
		__snd_pcm_set_state(substream->runtime, SNDRV_PCM_STATE_XRUN);
	return err;
}

static void snd_pcm_undo_start(struct snd_pcm_substream *substream,
			       snd_pcm_state_t state)
{
	if (substream->runtime->trigger_master == substream) {
		substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_STOP);
		substream->runtime->stop_operating = true;
	}
}

static void snd_pcm_post_start(struct snd_pcm_substream *substream,
			       snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	snd_pcm_trigger_tstamp(substream);
	runtime->hw_ptr_jiffies = jiffies;
	runtime->hw_ptr_buffer_jiffies = (runtime->buffer_size * HZ) / 
							    runtime->rate;
	__snd_pcm_set_state(runtime, state);
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
	    runtime->silence_size > 0)
		snd_pcm_playback_silence(substream, ULONG_MAX);
	snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTART);
}

static const struct action_ops snd_pcm_action_start = {
	.pre_action = snd_pcm_pre_start,
	.do_action = snd_pcm_do_start,
	.undo_action = snd_pcm_undo_start,
	.post_action = snd_pcm_post_start
};

/**
 * snd_pcm_start - start all linked streams
 * @substream: the PCM substream instance
 *
 * Return: Zero if successful, or a negative error code.
 * The stream lock must be acquired before calling this function.
 */
int snd_pcm_start(struct snd_pcm_substream *substream)
{
	return snd_pcm_action(&snd_pcm_action_start, substream,
			      SNDRV_PCM_STATE_RUNNING);
}

/* take the stream lock and start the streams */
static int snd_pcm_start_lock_irq(struct snd_pcm_substream *substream)
{
	return snd_pcm_action_lock_irq(&snd_pcm_action_start, substream,
				       SNDRV_PCM_STATE_RUNNING);
}

/*
 * stop callbacks
 */
static int snd_pcm_pre_stop(struct snd_pcm_substream *substream,
			    snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	if (runtime->state == SNDRV_PCM_STATE_OPEN)
		return -EBADFD;
	runtime->trigger_master = substream;
	return 0;
}

static int snd_pcm_do_stop(struct snd_pcm_substream *substream,
			   snd_pcm_state_t state)
{
	if (substream->runtime->trigger_master == substream &&
	    snd_pcm_running(substream)) {
		substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_STOP);
		substream->runtime->stop_operating = true;
	}
	return 0; /* unconditionally stop all substreams */
}

static void snd_pcm_post_stop(struct snd_pcm_substream *substream,
			      snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	if (runtime->state != state) {
		snd_pcm_trigger_tstamp(substream);
		__snd_pcm_set_state(runtime, state);
		snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTOP);
	}
	wake_up(&runtime->sleep);
	wake_up(&runtime->tsleep);
}

static const struct action_ops snd_pcm_action_stop = {
	.pre_action = snd_pcm_pre_stop,
	.do_action = snd_pcm_do_stop,
	.post_action = snd_pcm_post_stop
};

/**
 * snd_pcm_stop - try to stop all running streams in the substream group
 * @substream: the PCM substream instance
 * @state: PCM state after stopping the stream
 *
 * The state of each stream is then changed to the given state unconditionally.
 *
 * Return: Zero if successful, or a negative error code.
 */
int snd_pcm_stop(struct snd_pcm_substream *substream, snd_pcm_state_t state)
{
	return snd_pcm_action(&snd_pcm_action_stop, substream, state);
}
EXPORT_SYMBOL(snd_pcm_stop);

/**
 * snd_pcm_drain_done - stop the DMA only when the given stream is playback
 * @substream: the PCM substream
 *
 * After stopping, the state is changed to SETUP.
 * Unlike snd_pcm_stop(), this affects only the given stream.
 *
 * Return: Zero if successful, or a negative error code.
 */
int snd_pcm_drain_done(struct snd_pcm_substream *substream)
{
	return snd_pcm_action_single(&snd_pcm_action_stop, substream,
				     SNDRV_PCM_STATE_SETUP);
}

/**
 * snd_pcm_stop_xrun - stop the running streams as XRUN
 * @substream: the PCM substream instance
 *
 * This stops the given running substream (and all linked substreams) as XRUN.
 * Unlike snd_pcm_stop(), this function takes the substream lock by itself.
 *
 * Return: Zero if successful, or a negative error code.
 */
int snd_pcm_stop_xrun(struct snd_pcm_substream *substream)
{
	unsigned long flags;

	snd_pcm_stream_lock_irqsave(substream, flags);
	if (substream->runtime && snd_pcm_running(substream))
		__snd_pcm_xrun(substream);
	snd_pcm_stream_unlock_irqrestore(substream, flags);
	return 0;
}
EXPORT_SYMBOL_GPL(snd_pcm_stop_xrun);

/*
 * pause callbacks: pass boolean (to start pause or resume) as state argument
 */
#define pause_pushed(state)	(__force bool)(state)

static int snd_pcm_pre_pause(struct snd_pcm_substream *substream,
			     snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	if (!(runtime->info & SNDRV_PCM_INFO_PAUSE))
		return -ENOSYS;
	if (pause_pushed(state)) {
		if (runtime->state != SNDRV_PCM_STATE_RUNNING)
			return -EBADFD;
	} else if (runtime->state != SNDRV_PCM_STATE_PAUSED)
		return -EBADFD;
	runtime->trigger_master = substream;
	return 0;
}

static int snd_pcm_do_pause(struct snd_pcm_substream *substream,
			    snd_pcm_state_t state)
{
	if (substream->runtime->trigger_master != substream)
		return 0;
	/* some drivers might use hw_ptr to recover from the pause -
	   update the hw_ptr now */
	if (pause_pushed(state))
		snd_pcm_update_hw_ptr(substream);
	/* The jiffies check in snd_pcm_update_hw_ptr*() is done by
	 * a delta between the current jiffies, this gives a large enough
	 * delta, effectively to skip the check once.
	 */
	substream->runtime->hw_ptr_jiffies = jiffies - HZ * 1000;
	return substream->ops->trigger(substream,
				       pause_pushed(state) ?
				       SNDRV_PCM_TRIGGER_PAUSE_PUSH :
				       SNDRV_PCM_TRIGGER_PAUSE_RELEASE);
}

static void snd_pcm_undo_pause(struct snd_pcm_substream *substream,
			       snd_pcm_state_t state)
{
	if (substream->runtime->trigger_master == substream)
		substream->ops->trigger(substream,
					pause_pushed(state) ?
					SNDRV_PCM_TRIGGER_PAUSE_RELEASE :
					SNDRV_PCM_TRIGGER_PAUSE_PUSH);
}

static void snd_pcm_post_pause(struct snd_pcm_substream *substream,
			       snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	snd_pcm_trigger_tstamp(substream);
	if (pause_pushed(state)) {
		__snd_pcm_set_state(runtime, SNDRV_PCM_STATE_PAUSED);
		snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MPAUSE);
		wake_up(&runtime->sleep);
		wake_up(&runtime->tsleep);
	} else {
		__snd_pcm_set_state(runtime, SNDRV_PCM_STATE_RUNNING);
		snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MCONTINUE);
	}
}

static const struct action_ops snd_pcm_action_pause = {
	.pre_action = snd_pcm_pre_pause,
	.do_action = snd_pcm_do_pause,
	.undo_action = snd_pcm_undo_pause,
	.post_action = snd_pcm_post_pause
};

/*
 * Push/release the pause for all linked streams.
 */
static int snd_pcm_pause(struct snd_pcm_substream *substream, bool push)
{
	return snd_pcm_action(&snd_pcm_action_pause, substream,
			      (__force snd_pcm_state_t)push);
}

static int snd_pcm_pause_lock_irq(struct snd_pcm_substream *substream,
				  bool push)
{
	return snd_pcm_action_lock_irq(&snd_pcm_action_pause, substream,
				       (__force snd_pcm_state_t)push);
}

#ifdef CONFIG_PM
/* suspend callback: state argument ignored */

static int snd_pcm_pre_suspend(struct snd_pcm_substream *substream,
			       snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	switch (runtime->state) {
	case SNDRV_PCM_STATE_SUSPENDED:
		return -EBUSY;
	/* unresumable PCM state; return -EBUSY for skipping suspend */
	case SNDRV_PCM_STATE_OPEN:
	case SNDRV_PCM_STATE_SETUP:
	case SNDRV_PCM_STATE_DISCONNECTED:
		return -EBUSY;
	}
	runtime->trigger_master = substream;
	return 0;
}

static int snd_pcm_do_suspend(struct snd_pcm_substream *substream,
			      snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	if (runtime->trigger_master != substream)
		return 0;
	if (! snd_pcm_running(substream))
		return 0;
	substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_SUSPEND);
	runtime->stop_operating = true;
	return 0; /* suspend unconditionally */
}

static void snd_pcm_post_suspend(struct snd_pcm_substream *substream,
				 snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	snd_pcm_trigger_tstamp(substream);
	runtime->suspended_state = runtime->state;
	runtime->status->suspended_state = runtime->suspended_state;
	__snd_pcm_set_state(runtime, SNDRV_PCM_STATE_SUSPENDED);
	snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSUSPEND);
	wake_up(&runtime->sleep);
	wake_up(&runtime->tsleep);
}

static const struct action_ops snd_pcm_action_suspend = {
	.pre_action = snd_pcm_pre_suspend,
	.do_action = snd_pcm_do_suspend,
	.post_action = snd_pcm_post_suspend
};

/*
 * snd_pcm_suspend - trigger SUSPEND to all linked streams
 * @substream: the PCM substream
 *
 * After this call, all streams are changed to SUSPENDED state.
 *
 * Return: Zero if successful, or a negative error code.
 */
static int snd_pcm_suspend(struct snd_pcm_substream *substream)
{
	int err;
	unsigned long flags;

	snd_pcm_stream_lock_irqsave(substream, flags);
	err = snd_pcm_action(&snd_pcm_action_suspend, substream,
			     ACTION_ARG_IGNORE);
	snd_pcm_stream_unlock_irqrestore(substream, flags);
	return err;
}

/**
 * snd_pcm_suspend_all - trigger SUSPEND to all substreams in the given pcm
 * @pcm: the PCM instance
 *
 * After this call, all streams are changed to SUSPENDED state.
 *
 * Return: Zero if successful (or @pcm is %NULL), or a negative error code.
 */
int snd_pcm_suspend_all(struct snd_pcm *pcm)
{
	struct snd_pcm_substream *substream;
	int stream, err = 0;

	if (! pcm)
		return 0;

	for_each_pcm_substream(pcm, stream, substream) {
		/* FIXME: the open/close code should lock this as well */
		if (!substream->runtime)
			continue;

		/*
		 * Skip BE dai link PCM's that are internal and may
		 * not have their substream ops set.
		 */
		if (!substream->ops)
			continue;

		err = snd_pcm_suspend(substream);
		if (err < 0 && err != -EBUSY)
			return err;
	}

	for_each_pcm_substream(pcm, stream, substream)
		snd_pcm_sync_stop(substream, false);

	return 0;
}
EXPORT_SYMBOL(snd_pcm_suspend_all);

/* resume callbacks: state argument ignored */

static int snd_pcm_pre_resume(struct snd_pcm_substream *substream,
			      snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	if (!(runtime->info & SNDRV_PCM_INFO_RESUME))
		return -ENOSYS;
	runtime->trigger_master = substream;
	return 0;
}

static int snd_pcm_do_resume(struct snd_pcm_substream *substream,
			     snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	if (runtime->trigger_master != substream)
		return 0;
	/* DMA not running previously? */
	if (runtime->suspended_state != SNDRV_PCM_STATE_RUNNING &&
	    (runtime->suspended_state != SNDRV_PCM_STATE_DRAINING ||
	     substream->stream != SNDRV_PCM_STREAM_PLAYBACK))
		return 0;
	return substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_RESUME);
}

static void snd_pcm_undo_resume(struct snd_pcm_substream *substream,
				snd_pcm_state_t state)
{
	if (substream->runtime->trigger_master == substream &&
	    snd_pcm_running(substream))
		substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_SUSPEND);
}

static void snd_pcm_post_resume(struct snd_pcm_substream *substream,
				snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	snd_pcm_trigger_tstamp(substream);
	__snd_pcm_set_state(runtime, runtime->suspended_state);
	snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MRESUME);
}

static const struct action_ops snd_pcm_action_resume = {
	.pre_action = snd_pcm_pre_resume,
	.do_action = snd_pcm_do_resume,
	.undo_action = snd_pcm_undo_resume,
	.post_action = snd_pcm_post_resume
};

static int snd_pcm_resume(struct snd_pcm_substream *substream)
{
	return snd_pcm_action_lock_irq(&snd_pcm_action_resume, substream,
				       ACTION_ARG_IGNORE);
}

#else

static int snd_pcm_resume(struct snd_pcm_substream *substream)
{
	return -ENOSYS;
}

#endif /* CONFIG_PM */

/*
 * xrun ioctl
 *
 * Change the RUNNING stream(s) to XRUN state.
 */
static int snd_pcm_xrun(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	int result;

	snd_pcm_stream_lock_irq(substream);
	switch (runtime->state) {
	case SNDRV_PCM_STATE_XRUN:
		result = 0;	/* already there */
		break;
	case SNDRV_PCM_STATE_RUNNING:
		__snd_pcm_xrun(substream);
		result = 0;
		break;
	default:
		result = -EBADFD;
	}
	snd_pcm_stream_unlock_irq(substream);
	return result;
}

/*
 * reset ioctl
 */
/* reset callbacks:  state argument ignored */
static int snd_pcm_pre_reset(struct snd_pcm_substream *substream,
			     snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	switch (runtime->state) {
	case SNDRV_PCM_STATE_RUNNING:
	case SNDRV_PCM_STATE_PREPARED:
	case SNDRV_PCM_STATE_PAUSED:
	case SNDRV_PCM_STATE_SUSPENDED:
		return 0;
	default:
		return -EBADFD;
	}
}

static int snd_pcm_do_reset(struct snd_pcm_substream *substream,
			    snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	int err = snd_pcm_ops_ioctl(substream, SNDRV_PCM_IOCTL1_RESET, NULL);
	if (err < 0)
		return err;
	snd_pcm_stream_lock_irq(substream);
	runtime->hw_ptr_base = 0;
	runtime->hw_ptr_interrupt = runtime->status->hw_ptr -
		runtime->status->hw_ptr % runtime->period_size;
	runtime->silence_start = runtime->status->hw_ptr;
	runtime->silence_filled = 0;
	snd_pcm_stream_unlock_irq(substream);
	return 0;
}

static void snd_pcm_post_reset(struct snd_pcm_substream *substream,
			       snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	snd_pcm_stream_lock_irq(substream);
	runtime->control->appl_ptr = runtime->status->hw_ptr;
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
	    runtime->silence_size > 0)
		snd_pcm_playback_silence(substream, ULONG_MAX);
	snd_pcm_stream_unlock_irq(substream);
}

static const struct action_ops snd_pcm_action_reset = {
	.pre_action = snd_pcm_pre_reset,
	.do_action = snd_pcm_do_reset,
	.post_action = snd_pcm_post_reset
};

static int snd_pcm_reset(struct snd_pcm_substream *substream)
{
	return snd_pcm_action_nonatomic(&snd_pcm_action_reset, substream,
					ACTION_ARG_IGNORE);
}

/*
 * prepare ioctl
 */
/* pass f_flags as state argument */
static int snd_pcm_pre_prepare(struct snd_pcm_substream *substream,
			       snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	int f_flags = (__force int)state;

	if (runtime->state == SNDRV_PCM_STATE_OPEN ||
	    runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;
	if (snd_pcm_running(substream))
		return -EBUSY;
	substream->f_flags = f_flags;
	return 0;
}

static int snd_pcm_do_prepare(struct snd_pcm_substream *substream,
			      snd_pcm_state_t state)
{
	int err;
	snd_pcm_sync_stop(substream, true);
	err = substream->ops->prepare(substream);
	if (err < 0)
		return err;
	return snd_pcm_do_reset(substream, state);
}

static void snd_pcm_post_prepare(struct snd_pcm_substream *substream,
				 snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	runtime->control->appl_ptr = runtime->status->hw_ptr;
	snd_pcm_set_state(substream, SNDRV_PCM_STATE_PREPARED);
}

static const struct action_ops snd_pcm_action_prepare = {
	.pre_action = snd_pcm_pre_prepare,
	.do_action = snd_pcm_do_prepare,
	.post_action = snd_pcm_post_prepare
};

/**
 * snd_pcm_prepare - prepare the PCM substream to be triggerable
 * @substream: the PCM substream instance
 * @file: file to refer f_flags
 *
 * Return: Zero if successful, or a negative error code.
 */
static int snd_pcm_prepare(struct snd_pcm_substream *substream,
			   struct file *file)
{
	int f_flags;

	if (file)
		f_flags = file->f_flags;
	else
		f_flags = substream->f_flags;

	snd_pcm_stream_lock_irq(substream);
	switch (substream->runtime->state) {
	case SNDRV_PCM_STATE_PAUSED:
		snd_pcm_pause(substream, false);
		fallthrough;
	case SNDRV_PCM_STATE_SUSPENDED:
		snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
		break;
	}
	snd_pcm_stream_unlock_irq(substream);

	return snd_pcm_action_nonatomic(&snd_pcm_action_prepare,
					substream,
					(__force snd_pcm_state_t)f_flags);
}

/*
 * drain ioctl
 */

/* drain init callbacks: state argument ignored */
static int snd_pcm_pre_drain_init(struct snd_pcm_substream *substream,
				  snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	switch (runtime->state) {
	case SNDRV_PCM_STATE_OPEN:
	case SNDRV_PCM_STATE_DISCONNECTED:
	case SNDRV_PCM_STATE_SUSPENDED:
		return -EBADFD;
	}
	runtime->trigger_master = substream;
	return 0;
}

static int snd_pcm_do_drain_init(struct snd_pcm_substream *substream,
				 snd_pcm_state_t state)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
		switch (runtime->state) {
		case SNDRV_PCM_STATE_PREPARED:
			/* start playback stream if possible */
			if (! snd_pcm_playback_empty(substream)) {
				snd_pcm_do_start(substream, SNDRV_PCM_STATE_DRAINING);
				snd_pcm_post_start(substream, SNDRV_PCM_STATE_DRAINING);
			} else {
				__snd_pcm_set_state(runtime, SNDRV_PCM_STATE_SETUP);
			}
			break;
		case SNDRV_PCM_STATE_RUNNING:
			__snd_pcm_set_state(runtime, SNDRV_PCM_STATE_DRAINING);
			break;
		case SNDRV_PCM_STATE_XRUN:
			__snd_pcm_set_state(runtime, SNDRV_PCM_STATE_SETUP);
			break;
		default:
			break;
		}
	} else {
		/* stop running stream */
		if (runtime->state == SNDRV_PCM_STATE_RUNNING) {
			snd_pcm_state_t new_state;

			new_state = snd_pcm_capture_avail(runtime) > 0 ?
				SNDRV_PCM_STATE_DRAINING : SNDRV_PCM_STATE_SETUP;
			snd_pcm_do_stop(substream, new_state);
			snd_pcm_post_stop(substream, new_state);
		}
	}

	if (runtime->state == SNDRV_PCM_STATE_DRAINING &&
	    runtime->trigger_master == substream &&
	    (runtime->hw.info & SNDRV_PCM_INFO_DRAIN_TRIGGER))
		return substream->ops->trigger(substream,
					       SNDRV_PCM_TRIGGER_DRAIN);

	return 0;
}

static void snd_pcm_post_drain_init(struct snd_pcm_substream *substream,
				    snd_pcm_state_t state)
{
}

static const struct action_ops snd_pcm_action_drain_init = {
	.pre_action = snd_pcm_pre_drain_init,
	.do_action = snd_pcm_do_drain_init,
	.post_action = snd_pcm_post_drain_init
};

/*
 * Drain the stream(s).
 * When the substream is linked, sync until the draining of all playback streams
 * is finished.
 * After this call, all streams are supposed to be either SETUP or DRAINING
 * (capture only) state.
 */
static int snd_pcm_drain(struct snd_pcm_substream *substream,
			 struct file *file)
{
	struct snd_card *card;
	struct snd_pcm_runtime *runtime;
	struct snd_pcm_substream *s;
	struct snd_pcm_group *group;
	wait_queue_entry_t wait;
	int result = 0;
	int nonblock = 0;

	card = substream->pcm->card;
	runtime = substream->runtime;

	if (runtime->state == SNDRV_PCM_STATE_OPEN)
		return -EBADFD;

	if (file) {
		if (file->f_flags & O_NONBLOCK)
			nonblock = 1;
	} else if (substream->f_flags & O_NONBLOCK)
		nonblock = 1;

	snd_pcm_stream_lock_irq(substream);
	/* resume pause */
	if (runtime->state == SNDRV_PCM_STATE_PAUSED)
		snd_pcm_pause(substream, false);

	/* pre-start/stop - all running streams are changed to DRAINING state */
	result = snd_pcm_action(&snd_pcm_action_drain_init, substream,
				ACTION_ARG_IGNORE);
	if (result < 0)
		goto unlock;
	/* in non-blocking, we don't wait in ioctl but let caller poll */
	if (nonblock) {
		result = -EAGAIN;
		goto unlock;
	}

	for (;;) {
		long tout;
		struct snd_pcm_runtime *to_check;
		if (signal_pending(current)) {
			result = -ERESTARTSYS;
			break;
		}
		/* find a substream to drain */
		to_check = NULL;
		group = snd_pcm_stream_group_ref(substream);
		snd_pcm_group_for_each_entry(s, substream) {
			if (s->stream != SNDRV_PCM_STREAM_PLAYBACK)
				continue;
			runtime = s->runtime;
			if (runtime->state == SNDRV_PCM_STATE_DRAINING) {
				to_check = runtime;
				break;
			}
		}
		snd_pcm_group_unref(group, substream);
		if (!to_check)
			break; /* all drained */
		init_waitqueue_entry(&wait, current);
		set_current_state(TASK_INTERRUPTIBLE);
		add_wait_queue(&to_check->sleep, &wait);
		snd_pcm_stream_unlock_irq(substream);
		if (runtime->no_period_wakeup)
			tout = MAX_SCHEDULE_TIMEOUT;
		else {
			tout = 10;
			if (runtime->rate) {
				long t = runtime->period_size * 2 / runtime->rate;
				tout = max(t, tout);
			}
			tout = msecs_to_jiffies(tout * 1000);
		}
		tout = schedule_timeout(tout);

		snd_pcm_stream_lock_irq(substream);
		group = snd_pcm_stream_group_ref(substream);
		snd_pcm_group_for_each_entry(s, substream) {
			if (s->runtime == to_check) {
				remove_wait_queue(&to_check->sleep, &wait);
				break;
			}
		}
		snd_pcm_group_unref(group, substream);

		if (card->shutdown) {
			result = -ENODEV;
			break;
		}
		if (tout == 0) {
			if (substream->runtime->state == SNDRV_PCM_STATE_SUSPENDED)
				result = -ESTRPIPE;
			else {
				dev_dbg(substream->pcm->card->dev,
					"playback drain error (DMA or IRQ trouble?)\n");
				snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
				result = -EIO;
			}
			break;
		}
	}

 unlock:
	snd_pcm_stream_unlock_irq(substream);

	return result;
}

/*
 * drop ioctl
 *
 * Immediately put all linked substreams into SETUP state.
 */
static int snd_pcm_drop(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime;
	int result = 0;
	
	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	runtime = substream->runtime;

	if (runtime->state == SNDRV_PCM_STATE_OPEN ||
	    runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;

	snd_pcm_stream_lock_irq(substream);
	/* resume pause */
	if (runtime->state == SNDRV_PCM_STATE_PAUSED)
		snd_pcm_pause(substream, false);

	snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
	/* runtime->control->appl_ptr = runtime->status->hw_ptr; */
	snd_pcm_stream_unlock_irq(substream);

	return result;
}


static bool is_pcm_file(struct file *file)
{
	struct inode *inode = file_inode(file);
	struct snd_pcm *pcm;
	unsigned int minor;

	if (!S_ISCHR(inode->i_mode) || imajor(inode) != snd_major)
		return false;
	minor = iminor(inode);
	pcm = snd_lookup_minor_data(minor, SNDRV_DEVICE_TYPE_PCM_PLAYBACK);
	if (!pcm)
		pcm = snd_lookup_minor_data(minor, SNDRV_DEVICE_TYPE_PCM_CAPTURE);
	if (!pcm)
		return false;
	snd_card_unref(pcm->card);
	return true;
}

/*
 * PCM link handling
 */
static int snd_pcm_link(struct snd_pcm_substream *substream, int fd)
{
	int res = 0;
	struct snd_pcm_file *pcm_file;
	struct snd_pcm_substream *substream1;
	struct snd_pcm_group *group, *target_group;
	bool nonatomic = substream->pcm->nonatomic;
	struct fd f = fdget(fd);

	if (!f.file)
		return -EBADFD;
	if (!is_pcm_file(f.file)) {
		res = -EBADFD;
		goto _badf;
	}
	pcm_file = f.file->private_data;
	substream1 = pcm_file->substream;

	if (substream == substream1) {
		res = -EINVAL;
		goto _badf;
	}

	group = kzalloc(sizeof(*group), GFP_KERNEL);
	if (!group) {
		res = -ENOMEM;
		goto _nolock;
	}
	snd_pcm_group_init(group);

	down_write(&snd_pcm_link_rwsem);
	if (substream->runtime->state == SNDRV_PCM_STATE_OPEN ||
	    substream->runtime->state != substream1->runtime->state ||
	    substream->pcm->nonatomic != substream1->pcm->nonatomic) {
		res = -EBADFD;
		goto _end;
	}
	if (snd_pcm_stream_linked(substream1)) {
		res = -EALREADY;
		goto _end;
	}

	snd_pcm_stream_lock_irq(substream);
	if (!snd_pcm_stream_linked(substream)) {
		snd_pcm_group_assign(substream, group);
		group = NULL; /* assigned, don't free this one below */
	}
	target_group = substream->group;
	snd_pcm_stream_unlock_irq(substream);

	snd_pcm_group_lock_irq(target_group, nonatomic);
	snd_pcm_stream_lock_nested(substream1);
	snd_pcm_group_assign(substream1, target_group);
	refcount_inc(&target_group->refs);
	snd_pcm_stream_unlock(substream1);
	snd_pcm_group_unlock_irq(target_group, nonatomic);
 _end:
	up_write(&snd_pcm_link_rwsem);
 _nolock:
	kfree(group);
 _badf:
	fdput(f);
	return res;
}

static void relink_to_local(struct snd_pcm_substream *substream)
{
	snd_pcm_stream_lock_nested(substream);
	snd_pcm_group_assign(substream, &substream->self_group);
	snd_pcm_stream_unlock(substream);
}

static int snd_pcm_unlink(struct snd_pcm_substream *substream)
{
	struct snd_pcm_group *group;
	bool nonatomic = substream->pcm->nonatomic;
	bool do_free = false;
	int res = 0;

	down_write(&snd_pcm_link_rwsem);

	if (!snd_pcm_stream_linked(substream)) {
		res = -EALREADY;
		goto _end;
	}

	group = substream->group;
	snd_pcm_group_lock_irq(group, nonatomic);

	relink_to_local(substream);
	refcount_dec(&group->refs);

	/* detach the last stream, too */
	if (list_is_singular(&group->substreams)) {
		relink_to_local(list_first_entry(&group->substreams,
						 struct snd_pcm_substream,
						 link_list));
		do_free = refcount_dec_and_test(&group->refs);
	}

	snd_pcm_group_unlock_irq(group, nonatomic);
	if (do_free)
		kfree(group);

       _end:
	up_write(&snd_pcm_link_rwsem);
	return res;
}

/*
 * hw configurator
 */
static int snd_pcm_hw_rule_mul(struct snd_pcm_hw_params *params,
			       struct snd_pcm_hw_rule *rule)
{
	struct snd_interval t;
	snd_interval_mul(hw_param_interval_c(params, rule->deps[0]),
		     hw_param_interval_c(params, rule->deps[1]), &t);
	return snd_interval_refine(hw_param_interval(params, rule->var), &t);
}

static int snd_pcm_hw_rule_div(struct snd_pcm_hw_params *params,
			       struct snd_pcm_hw_rule *rule)
{
	struct snd_interval t;
	snd_interval_div(hw_param_interval_c(params, rule->deps[0]),
		     hw_param_interval_c(params, rule->deps[1]), &t);
	return snd_interval_refine(hw_param_interval(params, rule->var), &t);
}

static int snd_pcm_hw_rule_muldivk(struct snd_pcm_hw_params *params,
				   struct snd_pcm_hw_rule *rule)
{
	struct snd_interval t;
	snd_interval_muldivk(hw_param_interval_c(params, rule->deps[0]),
			 hw_param_interval_c(params, rule->deps[1]),
			 (unsigned long) rule->private, &t);
	return snd_interval_refine(hw_param_interval(params, rule->var), &t);
}

static int snd_pcm_hw_rule_mulkdiv(struct snd_pcm_hw_params *params,
				   struct snd_pcm_hw_rule *rule)
{
	struct snd_interval t;
	snd_interval_mulkdiv(hw_param_interval_c(params, rule->deps[0]),
			 (unsigned long) rule->private,
			 hw_param_interval_c(params, rule->deps[1]), &t);
	return snd_interval_refine(hw_param_interval(params, rule->var), &t);
}

static int snd_pcm_hw_rule_format(struct snd_pcm_hw_params *params,
				  struct snd_pcm_hw_rule *rule)
{
	snd_pcm_format_t k;
	const struct snd_interval *i =
				hw_param_interval_c(params, rule->deps[0]);
	struct snd_mask m;
	struct snd_mask *mask = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
	snd_mask_any(&m);
	pcm_for_each_format(k) {
		int bits;
		if (!snd_mask_test_format(mask, k))
			continue;
		bits = snd_pcm_format_physical_width(k);
		if (bits <= 0)
			continue; /* ignore invalid formats */
		if ((unsigned)bits < i->min || (unsigned)bits > i->max)
			snd_mask_reset(&m, (__force unsigned)k);
	}
	return snd_mask_refine(mask, &m);
}

static int snd_pcm_hw_rule_sample_bits(struct snd_pcm_hw_params *params,
				       struct snd_pcm_hw_rule *rule)
{
	struct snd_interval t;
	snd_pcm_format_t k;

	t.min = UINT_MAX;
	t.max = 0;
	t.openmin = 0;
	t.openmax = 0;
	pcm_for_each_format(k) {
		int bits;
		if (!snd_mask_test_format(hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT), k))
			continue;
		bits = snd_pcm_format_physical_width(k);
		if (bits <= 0)
			continue; /* ignore invalid formats */
		if (t.min > (unsigned)bits)
			t.min = bits;
		if (t.max < (unsigned)bits)
			t.max = bits;
	}
	t.integer = 1;
	return snd_interval_refine(hw_param_interval(params, rule->var), &t);
}

#if SNDRV_PCM_RATE_5512 != 1 << 0 || SNDRV_PCM_RATE_192000 != 1 << 12
#error "Change this table"
#endif

static const unsigned int rates[] = {
	5512, 8000, 11025, 16000, 22050, 32000, 44100,
	48000, 64000, 88200, 96000, 176400, 192000, 352800, 384000
};

const struct snd_pcm_hw_constraint_list snd_pcm_known_rates = {
	.count = ARRAY_SIZE(rates),
	.list = rates,
};

static int snd_pcm_hw_rule_rate(struct snd_pcm_hw_params *params,
				struct snd_pcm_hw_rule *rule)
{
	struct snd_pcm_hardware *hw = rule->private;
	return snd_interval_list(hw_param_interval(params, rule->var),
				 snd_pcm_known_rates.count,
				 snd_pcm_known_rates.list, hw->rates);
}		

static int snd_pcm_hw_rule_buffer_bytes_max(struct snd_pcm_hw_params *params,
					    struct snd_pcm_hw_rule *rule)
{
	struct snd_interval t;
	struct snd_pcm_substream *substream = rule->private;
	t.min = 0;
	t.max = substream->buffer_bytes_max;
	t.openmin = 0;
	t.openmax = 0;
	t.integer = 1;
	return snd_interval_refine(hw_param_interval(params, rule->var), &t);
}		

static int snd_pcm_hw_constraints_init(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
	int k, err;

	for (k = SNDRV_PCM_HW_PARAM_FIRST_MASK; k <= SNDRV_PCM_HW_PARAM_LAST_MASK; k++) {
		snd_mask_any(constrs_mask(constrs, k));
	}

	for (k = SNDRV_PCM_HW_PARAM_FIRST_INTERVAL; k <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; k++) {
		snd_interval_any(constrs_interval(constrs, k));
	}

	snd_interval_setinteger(constrs_interval(constrs, SNDRV_PCM_HW_PARAM_CHANNELS));
	snd_interval_setinteger(constrs_interval(constrs, SNDRV_PCM_HW_PARAM_BUFFER_SIZE));
	snd_interval_setinteger(constrs_interval(constrs, SNDRV_PCM_HW_PARAM_BUFFER_BYTES));
	snd_interval_setinteger(constrs_interval(constrs, SNDRV_PCM_HW_PARAM_SAMPLE_BITS));
	snd_interval_setinteger(constrs_interval(constrs, SNDRV_PCM_HW_PARAM_FRAME_BITS));

	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_FORMAT,
				   snd_pcm_hw_rule_format, NULL,
				   SNDRV_PCM_HW_PARAM_SAMPLE_BITS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_SAMPLE_BITS, 
				  snd_pcm_hw_rule_sample_bits, NULL,
				  SNDRV_PCM_HW_PARAM_FORMAT, 
				  SNDRV_PCM_HW_PARAM_SAMPLE_BITS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_SAMPLE_BITS, 
				  snd_pcm_hw_rule_div, NULL,
				  SNDRV_PCM_HW_PARAM_FRAME_BITS, SNDRV_PCM_HW_PARAM_CHANNELS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_FRAME_BITS, 
				  snd_pcm_hw_rule_mul, NULL,
				  SNDRV_PCM_HW_PARAM_SAMPLE_BITS, SNDRV_PCM_HW_PARAM_CHANNELS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_FRAME_BITS, 
				  snd_pcm_hw_rule_mulkdiv, (void*) 8,
				  SNDRV_PCM_HW_PARAM_PERIOD_BYTES, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_FRAME_BITS, 
				  snd_pcm_hw_rule_mulkdiv, (void*) 8,
				  SNDRV_PCM_HW_PARAM_BUFFER_BYTES, SNDRV_PCM_HW_PARAM_BUFFER_SIZE, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS, 
				  snd_pcm_hw_rule_div, NULL,
				  SNDRV_PCM_HW_PARAM_FRAME_BITS, SNDRV_PCM_HW_PARAM_SAMPLE_BITS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE, 
				  snd_pcm_hw_rule_mulkdiv, (void*) 1000000,
				  SNDRV_PCM_HW_PARAM_PERIOD_SIZE, SNDRV_PCM_HW_PARAM_PERIOD_TIME, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE, 
				  snd_pcm_hw_rule_mulkdiv, (void*) 1000000,
				  SNDRV_PCM_HW_PARAM_BUFFER_SIZE, SNDRV_PCM_HW_PARAM_BUFFER_TIME, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIODS, 
				  snd_pcm_hw_rule_div, NULL,
				  SNDRV_PCM_HW_PARAM_BUFFER_SIZE, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 
				  snd_pcm_hw_rule_div, NULL,
				  SNDRV_PCM_HW_PARAM_BUFFER_SIZE, SNDRV_PCM_HW_PARAM_PERIODS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 
				  snd_pcm_hw_rule_mulkdiv, (void*) 8,
				  SNDRV_PCM_HW_PARAM_PERIOD_BYTES, SNDRV_PCM_HW_PARAM_FRAME_BITS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 
				  snd_pcm_hw_rule_muldivk, (void*) 1000000,
				  SNDRV_PCM_HW_PARAM_PERIOD_TIME, SNDRV_PCM_HW_PARAM_RATE, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 
				  snd_pcm_hw_rule_mul, NULL,
				  SNDRV_PCM_HW_PARAM_PERIOD_SIZE, SNDRV_PCM_HW_PARAM_PERIODS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 
				  snd_pcm_hw_rule_mulkdiv, (void*) 8,
				  SNDRV_PCM_HW_PARAM_BUFFER_BYTES, SNDRV_PCM_HW_PARAM_FRAME_BITS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 
				  snd_pcm_hw_rule_muldivk, (void*) 1000000,
				  SNDRV_PCM_HW_PARAM_BUFFER_TIME, SNDRV_PCM_HW_PARAM_RATE, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 
				  snd_pcm_hw_rule_muldivk, (void*) 8,
				  SNDRV_PCM_HW_PARAM_PERIOD_SIZE, SNDRV_PCM_HW_PARAM_FRAME_BITS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 
				  snd_pcm_hw_rule_muldivk, (void*) 8,
				  SNDRV_PCM_HW_PARAM_BUFFER_SIZE, SNDRV_PCM_HW_PARAM_FRAME_BITS, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_TIME, 
				  snd_pcm_hw_rule_mulkdiv, (void*) 1000000,
				  SNDRV_PCM_HW_PARAM_PERIOD_SIZE, SNDRV_PCM_HW_PARAM_RATE, -1);
	if (err < 0)
		return err;
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_TIME, 
				  snd_pcm_hw_rule_mulkdiv, (void*) 1000000,
				  SNDRV_PCM_HW_PARAM_BUFFER_SIZE, SNDRV_PCM_HW_PARAM_RATE, -1);
	if (err < 0)
		return err;
	return 0;
}

static int snd_pcm_hw_constraints_complete(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct snd_pcm_hardware *hw = &runtime->hw;
	int err;
	unsigned int mask = 0;

        if (hw->info & SNDRV_PCM_INFO_INTERLEAVED)
		mask |= PARAM_MASK_BIT(SNDRV_PCM_ACCESS_RW_INTERLEAVED);
        if (hw->info & SNDRV_PCM_INFO_NONINTERLEAVED)
		mask |= PARAM_MASK_BIT(SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
	if (hw_support_mmap(substream)) {
		if (hw->info & SNDRV_PCM_INFO_INTERLEAVED)
			mask |= PARAM_MASK_BIT(SNDRV_PCM_ACCESS_MMAP_INTERLEAVED);
		if (hw->info & SNDRV_PCM_INFO_NONINTERLEAVED)
			mask |= PARAM_MASK_BIT(SNDRV_PCM_ACCESS_MMAP_NONINTERLEAVED);
		if (hw->info & SNDRV_PCM_INFO_COMPLEX)
			mask |= PARAM_MASK_BIT(SNDRV_PCM_ACCESS_MMAP_COMPLEX);
	}
	err = snd_pcm_hw_constraint_mask(runtime, SNDRV_PCM_HW_PARAM_ACCESS, mask);
	if (err < 0)
		return err;

	err = snd_pcm_hw_constraint_mask64(runtime, SNDRV_PCM_HW_PARAM_FORMAT, hw->formats);
	if (err < 0)
		return err;

	err = snd_pcm_hw_constraint_mask(runtime, SNDRV_PCM_HW_PARAM_SUBFORMAT,
					 PARAM_MASK_BIT(SNDRV_PCM_SUBFORMAT_STD));
	if (err < 0)
		return err;

	err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_CHANNELS,
					   hw->channels_min, hw->channels_max);
	if (err < 0)
		return err;

	err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_RATE,
					   hw->rate_min, hw->rate_max);
	if (err < 0)
		return err;

	err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
					   hw->period_bytes_min, hw->period_bytes_max);
	if (err < 0)
		return err;

	err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIODS,
					   hw->periods_min, hw->periods_max);
	if (err < 0)
		return err;

	err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES,
					   hw->period_bytes_min, hw->buffer_bytes_max);
	if (err < 0)
		return err;

	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 
				  snd_pcm_hw_rule_buffer_bytes_max, substream,
				  SNDRV_PCM_HW_PARAM_BUFFER_BYTES, -1);
	if (err < 0)
		return err;

	/* FIXME: remove */
	if (runtime->dma_bytes) {
		err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 0, runtime->dma_bytes);
		if (err < 0)
			return err;
	}

	if (!(hw->rates & (SNDRV_PCM_RATE_KNOT | SNDRV_PCM_RATE_CONTINUOUS))) {
		err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE, 
					  snd_pcm_hw_rule_rate, hw,
					  SNDRV_PCM_HW_PARAM_RATE, -1);
		if (err < 0)
			return err;
	}

	/* FIXME: this belong to lowlevel */
	snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIOD_SIZE);

	return 0;
}

static void pcm_release_private(struct snd_pcm_substream *substream)
{
	if (snd_pcm_stream_linked(substream))
		snd_pcm_unlink(substream);
}

void snd_pcm_release_substream(struct snd_pcm_substream *substream)
{
	substream->ref_count--;
	if (substream->ref_count > 0)
		return;

	snd_pcm_drop(substream);
	if (substream->hw_opened) {
		if (substream->runtime->state != SNDRV_PCM_STATE_OPEN)
			do_hw_free(substream);
		substream->ops->close(substream);
		substream->hw_opened = 0;
	}
	if (cpu_latency_qos_request_active(&substream->latency_pm_qos_req))
		cpu_latency_qos_remove_request(&substream->latency_pm_qos_req);
	if (substream->pcm_release) {
		substream->pcm_release(substream);
		substream->pcm_release = NULL;
	}
	snd_pcm_detach_substream(substream);
}
EXPORT_SYMBOL(snd_pcm_release_substream);

int snd_pcm_open_substream(struct snd_pcm *pcm, int stream,
			   struct file *file,
			   struct snd_pcm_substream **rsubstream)
{
	struct snd_pcm_substream *substream;
	int err;

	err = snd_pcm_attach_substream(pcm, stream, file, &substream);
	if (err < 0)
		return err;
	if (substream->ref_count > 1) {
		*rsubstream = substream;
		return 0;
	}

	err = snd_pcm_hw_constraints_init(substream);
	if (err < 0) {
		pcm_dbg(pcm, "snd_pcm_hw_constraints_init failed\n");
		goto error;
	}

	err = substream->ops->open(substream);
	if (err < 0)
		goto error;

	substream->hw_opened = 1;

	err = snd_pcm_hw_constraints_complete(substream);
	if (err < 0) {
		pcm_dbg(pcm, "snd_pcm_hw_constraints_complete failed\n");
		goto error;
	}

	/* automatically set EXPLICIT_SYNC flag in the managed mode whenever
	 * the DMA buffer requires it
	 */
	if (substream->managed_buffer_alloc &&
	    substream->dma_buffer.dev.need_sync)
		substream->runtime->hw.info |= SNDRV_PCM_INFO_EXPLICIT_SYNC;

	*rsubstream = substream;
	return 0;

 error:
	snd_pcm_release_substream(substream);
	return err;
}
EXPORT_SYMBOL(snd_pcm_open_substream);

static int snd_pcm_open_file(struct file *file,
			     struct snd_pcm *pcm,
			     int stream)
{
	struct snd_pcm_file *pcm_file;
	struct snd_pcm_substream *substream;
	int err;

	err = snd_pcm_open_substream(pcm, stream, file, &substream);
	if (err < 0)
		return err;

	pcm_file = kzalloc(sizeof(*pcm_file), GFP_KERNEL);
	if (pcm_file == NULL) {
		snd_pcm_release_substream(substream);
		return -ENOMEM;
	}
	pcm_file->substream = substream;
	if (substream->ref_count == 1)
		substream->pcm_release = pcm_release_private;
	file->private_data = pcm_file;

	return 0;
}

static int snd_pcm_playback_open(struct inode *inode, struct file *file)
{
	struct snd_pcm *pcm;
	int err = nonseekable_open(inode, file);
	if (err < 0)
		return err;
	pcm = snd_lookup_minor_data(iminor(inode),
				    SNDRV_DEVICE_TYPE_PCM_PLAYBACK);
	err = snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_PLAYBACK);
	if (pcm)
		snd_card_unref(pcm->card);
	return err;
}

static int snd_pcm_capture_open(struct inode *inode, struct file *file)
{
	struct snd_pcm *pcm;
	int err = nonseekable_open(inode, file);
	if (err < 0)
		return err;
	pcm = snd_lookup_minor_data(iminor(inode),
				    SNDRV_DEVICE_TYPE_PCM_CAPTURE);
	err = snd_pcm_open(file, pcm, SNDRV_PCM_STREAM_CAPTURE);
	if (pcm)
		snd_card_unref(pcm->card);
	return err;
}

static int snd_pcm_open(struct file *file, struct snd_pcm *pcm, int stream)
{
	int err;
	wait_queue_entry_t wait;

	if (pcm == NULL) {
		err = -ENODEV;
		goto __error1;
	}
	err = snd_card_file_add(pcm->card, file);
	if (err < 0)
		goto __error1;
	if (!try_module_get(pcm->card->module)) {
		err = -EFAULT;
		goto __error2;
	}
	init_waitqueue_entry(&wait, current);
	add_wait_queue(&pcm->open_wait, &wait);
	mutex_lock(&pcm->open_mutex);
	while (1) {
		err = snd_pcm_open_file(file, pcm, stream);
		if (err >= 0)
			break;
		if (err == -EAGAIN) {
			if (file->f_flags & O_NONBLOCK) {
				err = -EBUSY;
				break;
			}
		} else
			break;
		set_current_state(TASK_INTERRUPTIBLE);
		mutex_unlock(&pcm->open_mutex);
		schedule();
		mutex_lock(&pcm->open_mutex);
		if (pcm->card->shutdown) {
			err = -ENODEV;
			break;
		}
		if (signal_pending(current)) {
			err = -ERESTARTSYS;
			break;
		}
	}
	remove_wait_queue(&pcm->open_wait, &wait);
	mutex_unlock(&pcm->open_mutex);
	if (err < 0)
		goto __error;
	return err;

      __error:
	module_put(pcm->card->module);
      __error2:
      	snd_card_file_remove(pcm->card, file);
      __error1:
      	return err;
}

static int snd_pcm_release(struct inode *inode, struct file *file)
{
	struct snd_pcm *pcm;
	struct snd_pcm_substream *substream;
	struct snd_pcm_file *pcm_file;

	pcm_file = file->private_data;
	substream = pcm_file->substream;
	if (snd_BUG_ON(!substream))
		return -ENXIO;
	pcm = substream->pcm;

	/* block until the device gets woken up as it may touch the hardware */
	snd_power_wait(pcm->card);

	mutex_lock(&pcm->open_mutex);
	snd_pcm_release_substream(substream);
	kfree(pcm_file);
	mutex_unlock(&pcm->open_mutex);
	wake_up(&pcm->open_wait);
	module_put(pcm->card->module);
	snd_card_file_remove(pcm->card, file);
	return 0;
}

/* check and update PCM state; return 0 or a negative error
 * call this inside PCM lock
 */
static int do_pcm_hwsync(struct snd_pcm_substream *substream)
{
	switch (substream->runtime->state) {
	case SNDRV_PCM_STATE_DRAINING:
		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
			return -EBADFD;
		fallthrough;
	case SNDRV_PCM_STATE_RUNNING:
		return snd_pcm_update_hw_ptr(substream);
	case SNDRV_PCM_STATE_PREPARED:
	case SNDRV_PCM_STATE_PAUSED:
		return 0;
	case SNDRV_PCM_STATE_SUSPENDED:
		return -ESTRPIPE;
	case SNDRV_PCM_STATE_XRUN:
		return -EPIPE;
	default:
		return -EBADFD;
	}
}

/* increase the appl_ptr; returns the processed frames or a negative error */
static snd_pcm_sframes_t forward_appl_ptr(struct snd_pcm_substream *substream,
					  snd_pcm_uframes_t frames,
					   snd_pcm_sframes_t avail)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	snd_pcm_sframes_t appl_ptr;
	int ret;

	if (avail <= 0)
		return 0;
	if (frames > (snd_pcm_uframes_t)avail)
		frames = avail;
	appl_ptr = runtime->control->appl_ptr + frames;
	if (appl_ptr >= (snd_pcm_sframes_t)runtime->boundary)
		appl_ptr -= runtime->boundary;
	ret = pcm_lib_apply_appl_ptr(substream, appl_ptr);
	return ret < 0 ? ret : frames;
}

/* decrease the appl_ptr; returns the processed frames or zero for error */
static snd_pcm_sframes_t rewind_appl_ptr(struct snd_pcm_substream *substream,
					 snd_pcm_uframes_t frames,
					 snd_pcm_sframes_t avail)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	snd_pcm_sframes_t appl_ptr;
	int ret;

	if (avail <= 0)
		return 0;
	if (frames > (snd_pcm_uframes_t)avail)
		frames = avail;
	appl_ptr = runtime->control->appl_ptr - frames;
	if (appl_ptr < 0)
		appl_ptr += runtime->boundary;
	ret = pcm_lib_apply_appl_ptr(substream, appl_ptr);
	/* NOTE: we return zero for errors because PulseAudio gets depressed
	 * upon receiving an error from rewind ioctl and stops processing
	 * any longer.  Returning zero means that no rewind is done, so
	 * it's not absolutely wrong to answer like that.
	 */
	return ret < 0 ? 0 : frames;
}

static snd_pcm_sframes_t snd_pcm_rewind(struct snd_pcm_substream *substream,
					snd_pcm_uframes_t frames)
{
	snd_pcm_sframes_t ret;

	if (frames == 0)
		return 0;

	snd_pcm_stream_lock_irq(substream);
	ret = do_pcm_hwsync(substream);
	if (!ret)
		ret = rewind_appl_ptr(substream, frames,
				      snd_pcm_hw_avail(substream));
	snd_pcm_stream_unlock_irq(substream);
	if (ret >= 0)
		snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_DEVICE);
	return ret;
}

static snd_pcm_sframes_t snd_pcm_forward(struct snd_pcm_substream *substream,
					 snd_pcm_uframes_t frames)
{
	snd_pcm_sframes_t ret;

	if (frames == 0)
		return 0;

	snd_pcm_stream_lock_irq(substream);
	ret = do_pcm_hwsync(substream);
	if (!ret)
		ret = forward_appl_ptr(substream, frames,
				       snd_pcm_avail(substream));
	snd_pcm_stream_unlock_irq(substream);
	if (ret >= 0)
		snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_DEVICE);
	return ret;
}

static int snd_pcm_delay(struct snd_pcm_substream *substream,
			 snd_pcm_sframes_t *delay)
{
	int err;

	snd_pcm_stream_lock_irq(substream);
	err = do_pcm_hwsync(substream);
	if (delay && !err)
		*delay = snd_pcm_calc_delay(substream);
	snd_pcm_stream_unlock_irq(substream);
	snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_CPU);

	return err;
}
		
static inline int snd_pcm_hwsync(struct snd_pcm_substream *substream)
{
	return snd_pcm_delay(substream, NULL);
}

static int snd_pcm_sync_ptr(struct snd_pcm_substream *substream,
			    struct snd_pcm_sync_ptr __user *_sync_ptr)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct snd_pcm_sync_ptr sync_ptr;
	volatile struct snd_pcm_mmap_status *status;
	volatile struct snd_pcm_mmap_control *control;
	int err;

	memset(&sync_ptr, 0, sizeof(sync_ptr));
	if (get_user(sync_ptr.flags, (unsigned __user *)&(_sync_ptr->flags)))
		return -EFAULT;
	if (copy_from_user(&sync_ptr.c.control, &(_sync_ptr->c.control), sizeof(struct snd_pcm_mmap_control)))
		return -EFAULT;	
	status = runtime->status;
	control = runtime->control;
	if (sync_ptr.flags & SNDRV_PCM_SYNC_PTR_HWSYNC) {
		err = snd_pcm_hwsync(substream);
		if (err < 0)
			return err;
	}
	snd_pcm_stream_lock_irq(substream);
	if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL)) {
		err = pcm_lib_apply_appl_ptr(substream,
					     sync_ptr.c.control.appl_ptr);
		if (err < 0) {
			snd_pcm_stream_unlock_irq(substream);
			return err;
		}
	} else {
		sync_ptr.c.control.appl_ptr = control->appl_ptr;
	}
	if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_AVAIL_MIN))
		control->avail_min = sync_ptr.c.control.avail_min;
	else
		sync_ptr.c.control.avail_min = control->avail_min;
	sync_ptr.s.status.state = status->state;
	sync_ptr.s.status.hw_ptr = status->hw_ptr;
	sync_ptr.s.status.tstamp = status->tstamp;
	sync_ptr.s.status.suspended_state = status->suspended_state;
	sync_ptr.s.status.audio_tstamp = status->audio_tstamp;
	snd_pcm_stream_unlock_irq(substream);
	if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL))
		snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_DEVICE);
	if (copy_to_user(_sync_ptr, &sync_ptr, sizeof(sync_ptr)))
		return -EFAULT;
	return 0;
}

struct snd_pcm_mmap_status32 {
	snd_pcm_state_t state;
	s32 pad1;
	u32 hw_ptr;
	s32 tstamp_sec;
	s32 tstamp_nsec;
	snd_pcm_state_t suspended_state;
	s32 audio_tstamp_sec;
	s32 audio_tstamp_nsec;
} __attribute__((packed));

struct snd_pcm_mmap_control32 {
	u32 appl_ptr;
	u32 avail_min;
};

struct snd_pcm_sync_ptr32 {
	u32 flags;
	union {
		struct snd_pcm_mmap_status32 status;
		unsigned char reserved[64];
	} s;
	union {
		struct snd_pcm_mmap_control32 control;
		unsigned char reserved[64];
	} c;
} __attribute__((packed));

/* recalcuate the boundary within 32bit */
static snd_pcm_uframes_t recalculate_boundary(struct snd_pcm_runtime *runtime)
{
	snd_pcm_uframes_t boundary;

	if (! runtime->buffer_size)
		return 0;
	boundary = runtime->buffer_size;
	while (boundary * 2 <= 0x7fffffffUL - runtime->buffer_size)
		boundary *= 2;
	return boundary;
}

static int snd_pcm_ioctl_sync_ptr_compat(struct snd_pcm_substream *substream,
					 struct snd_pcm_sync_ptr32 __user *src)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	volatile struct snd_pcm_mmap_status *status;
	volatile struct snd_pcm_mmap_control *control;
	u32 sflags;
	struct snd_pcm_mmap_control scontrol;
	struct snd_pcm_mmap_status sstatus;
	snd_pcm_uframes_t boundary;
	int err;

	if (snd_BUG_ON(!runtime))
		return -EINVAL;

	if (get_user(sflags, &src->flags) ||
	    get_user(scontrol.appl_ptr, &src->c.control.appl_ptr) ||
	    get_user(scontrol.avail_min, &src->c.control.avail_min))
		return -EFAULT;
	if (sflags & SNDRV_PCM_SYNC_PTR_HWSYNC) {
		err = snd_pcm_hwsync(substream);
		if (err < 0)
			return err;
	}
	status = runtime->status;
	control = runtime->control;
	boundary = recalculate_boundary(runtime);
	if (! boundary)
		boundary = 0x7fffffff;
	snd_pcm_stream_lock_irq(substream);
	/* FIXME: we should consider the boundary for the sync from app */
	if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL)) {
		err = pcm_lib_apply_appl_ptr(substream,
				scontrol.appl_ptr);
		if (err < 0) {
			snd_pcm_stream_unlock_irq(substream);
			return err;
		}
	} else
		scontrol.appl_ptr = control->appl_ptr % boundary;
	if (!(sflags & SNDRV_PCM_SYNC_PTR_AVAIL_MIN))
		control->avail_min = scontrol.avail_min;
	else
		scontrol.avail_min = control->avail_min;
	sstatus.state = status->state;
	sstatus.hw_ptr = status->hw_ptr % boundary;
	sstatus.tstamp = status->tstamp;
	sstatus.suspended_state = status->suspended_state;
	sstatus.audio_tstamp = status->audio_tstamp;
	snd_pcm_stream_unlock_irq(substream);
	if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL))
		snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_DEVICE);
	if (put_user(sstatus.state, &src->s.status.state) ||
	    put_user(sstatus.hw_ptr, &src->s.status.hw_ptr) ||
	    put_user(sstatus.tstamp.tv_sec, &src->s.status.tstamp_sec) ||
	    put_user(sstatus.tstamp.tv_nsec, &src->s.status.tstamp_nsec) ||
	    put_user(sstatus.suspended_state, &src->s.status.suspended_state) ||
	    put_user(sstatus.audio_tstamp.tv_sec, &src->s.status.audio_tstamp_sec) ||
	    put_user(sstatus.audio_tstamp.tv_nsec, &src->s.status.audio_tstamp_nsec) ||
	    put_user(scontrol.appl_ptr, &src->c.control.appl_ptr) ||
	    put_user(scontrol.avail_min, &src->c.control.avail_min))
		return -EFAULT;

	return 0;
}
#define __SNDRV_PCM_IOCTL_SYNC_PTR32 _IOWR('A', 0x23, struct snd_pcm_sync_ptr32)

static int snd_pcm_tstamp(struct snd_pcm_substream *substream, int __user *_arg)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	int arg;
	
	if (get_user(arg, _arg))
		return -EFAULT;
	if (arg < 0 || arg > SNDRV_PCM_TSTAMP_TYPE_LAST)
		return -EINVAL;
	runtime->tstamp_type = arg;
	return 0;
}

static int snd_pcm_xferi_frames_ioctl(struct snd_pcm_substream *substream,
				      struct snd_xferi __user *_xferi)
{
	struct snd_xferi xferi;
	struct snd_pcm_runtime *runtime = substream->runtime;
	snd_pcm_sframes_t result;

	if (runtime->state == SNDRV_PCM_STATE_OPEN)
		return -EBADFD;
	if (put_user(0, &_xferi->result))
		return -EFAULT;
	if (copy_from_user(&xferi, _xferi, sizeof(xferi)))
		return -EFAULT;
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
		result = snd_pcm_lib_write(substream, xferi.buf, xferi.frames);
	else
		result = snd_pcm_lib_read(substream, xferi.buf, xferi.frames);
	if (put_user(result, &_xferi->result))
		return -EFAULT;
	return result < 0 ? result : 0;
}

static int snd_pcm_xfern_frames_ioctl(struct snd_pcm_substream *substream,
				      struct snd_xfern __user *_xfern)
{
	struct snd_xfern xfern;
	struct snd_pcm_runtime *runtime = substream->runtime;
	void *bufs;
	snd_pcm_sframes_t result;

	if (runtime->state == SNDRV_PCM_STATE_OPEN)
		return -EBADFD;
	if (runtime->channels > 128)
		return -EINVAL;
	if (put_user(0, &_xfern->result))
		return -EFAULT;
	if (copy_from_user(&xfern, _xfern, sizeof(xfern)))
		return -EFAULT;

	bufs = memdup_user(xfern.bufs, sizeof(void *) * runtime->channels);
	if (IS_ERR(bufs))
		return PTR_ERR(bufs);
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
		result = snd_pcm_lib_writev(substream, bufs, xfern.frames);
	else
		result = snd_pcm_lib_readv(substream, bufs, xfern.frames);
	kfree(bufs);
	if (put_user(result, &_xfern->result))
		return -EFAULT;
	return result < 0 ? result : 0;
}

static int snd_pcm_rewind_ioctl(struct snd_pcm_substream *substream,
				snd_pcm_uframes_t __user *_frames)
{
	snd_pcm_uframes_t frames;
	snd_pcm_sframes_t result;

	if (get_user(frames, _frames))
		return -EFAULT;
	if (put_user(0, _frames))
		return -EFAULT;
	result = snd_pcm_rewind(substream, frames);
	if (put_user(result, _frames))
		return -EFAULT;
	return result < 0 ? result : 0;
}

static int snd_pcm_forward_ioctl(struct snd_pcm_substream *substream,
				 snd_pcm_uframes_t __user *_frames)
{
	snd_pcm_uframes_t frames;
	snd_pcm_sframes_t result;

	if (get_user(frames, _frames))
		return -EFAULT;
	if (put_user(0, _frames))
		return -EFAULT;
	result = snd_pcm_forward(substream, frames);
	if (put_user(result, _frames))
		return -EFAULT;
	return result < 0 ? result : 0;
}

static int snd_pcm_common_ioctl(struct file *file,
				 struct snd_pcm_substream *substream,
				 unsigned int cmd, void __user *arg)
{
	struct snd_pcm_file *pcm_file = file->private_data;
	int res;

	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;

	if (substream->runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;

	res = snd_power_wait(substream->pcm->card);
	if (res < 0)
		return res;

	switch (cmd) {
	case SNDRV_PCM_IOCTL_PVERSION:
		return put_user(SNDRV_PCM_VERSION, (int __user *)arg) ? -EFAULT : 0;
	case SNDRV_PCM_IOCTL_INFO:
		return snd_pcm_info_user(substream, arg);
	case SNDRV_PCM_IOCTL_TSTAMP:	/* just for compatibility */
		return 0;
	case SNDRV_PCM_IOCTL_TTSTAMP:
		return snd_pcm_tstamp(substream, arg);
	case SNDRV_PCM_IOCTL_USER_PVERSION:
		if (get_user(pcm_file->user_pversion,
			     (unsigned int __user *)arg))
			return -EFAULT;
		return 0;
	case SNDRV_PCM_IOCTL_HW_REFINE:
		return snd_pcm_hw_refine_user(substream, arg);
	case SNDRV_PCM_IOCTL_HW_PARAMS:
		return snd_pcm_hw_params_user(substream, arg);
	case SNDRV_PCM_IOCTL_HW_FREE:
		return snd_pcm_hw_free(substream);
	case SNDRV_PCM_IOCTL_SW_PARAMS:
		return snd_pcm_sw_params_user(substream, arg);
	case SNDRV_PCM_IOCTL_STATUS32:
		return snd_pcm_status_user32(substream, arg, false);
	case SNDRV_PCM_IOCTL_STATUS_EXT32:
		return snd_pcm_status_user32(substream, arg, true);
	case SNDRV_PCM_IOCTL_STATUS64:
		return snd_pcm_status_user64(substream, arg, false);
	case SNDRV_PCM_IOCTL_STATUS_EXT64:
		return snd_pcm_status_user64(substream, arg, true);
	case SNDRV_PCM_IOCTL_CHANNEL_INFO:
		return snd_pcm_channel_info_user(substream, arg);
	case SNDRV_PCM_IOCTL_PREPARE:
		return snd_pcm_prepare(substream, file);
	case SNDRV_PCM_IOCTL_RESET:
		return snd_pcm_reset(substream);
	case SNDRV_PCM_IOCTL_START:
		return snd_pcm_start_lock_irq(substream);
	case SNDRV_PCM_IOCTL_LINK:
		return snd_pcm_link(substream, (int)(unsigned long) arg);
	case SNDRV_PCM_IOCTL_UNLINK:
		return snd_pcm_unlink(substream);
	case SNDRV_PCM_IOCTL_RESUME:
		return snd_pcm_resume(substream);
	case SNDRV_PCM_IOCTL_XRUN:
		return snd_pcm_xrun(substream);
	case SNDRV_PCM_IOCTL_HWSYNC:
		return snd_pcm_hwsync(substream);
	case SNDRV_PCM_IOCTL_DELAY:
	{
		snd_pcm_sframes_t delay = 0;
		snd_pcm_sframes_t __user *res = arg;
		int err;

		err = snd_pcm_delay(substream, &delay);
		if (err)
			return err;
		if (put_user(delay, res))
			return -EFAULT;
		return 0;
	}
	case __SNDRV_PCM_IOCTL_SYNC_PTR32:
		return snd_pcm_ioctl_sync_ptr_compat(substream, arg);
	case __SNDRV_PCM_IOCTL_SYNC_PTR64:
		return snd_pcm_sync_ptr(substream, arg);
#ifdef CONFIG_SND_SUPPORT_OLD_API
	case SNDRV_PCM_IOCTL_HW_REFINE_OLD:
		return snd_pcm_hw_refine_old_user(substream, arg);
	case SNDRV_PCM_IOCTL_HW_PARAMS_OLD:
		return snd_pcm_hw_params_old_user(substream, arg);
#endif
	case SNDRV_PCM_IOCTL_DRAIN:
		return snd_pcm_drain(substream, file);
	case SNDRV_PCM_IOCTL_DROP:
		return snd_pcm_drop(substream);
	case SNDRV_PCM_IOCTL_PAUSE:
		return snd_pcm_pause_lock_irq(substream, (unsigned long)arg);
	case SNDRV_PCM_IOCTL_WRITEI_FRAMES:
	case SNDRV_PCM_IOCTL_READI_FRAMES:
		return snd_pcm_xferi_frames_ioctl(substream, arg);
	case SNDRV_PCM_IOCTL_WRITEN_FRAMES:
	case SNDRV_PCM_IOCTL_READN_FRAMES:
		return snd_pcm_xfern_frames_ioctl(substream, arg);
	case SNDRV_PCM_IOCTL_REWIND:
		return snd_pcm_rewind_ioctl(substream, arg);
	case SNDRV_PCM_IOCTL_FORWARD:
		return snd_pcm_forward_ioctl(substream, arg);
	}
	pcm_dbg(substream->pcm, "unknown ioctl = 0x%x\n", cmd);
	return -ENOTTY;
}

static long snd_pcm_ioctl(struct file *file, unsigned int cmd,
			  unsigned long arg)
{
	struct snd_pcm_file *pcm_file;

	pcm_file = file->private_data;

	if (((cmd >> 8) & 0xff) != 'A')
		return -ENOTTY;

	return snd_pcm_common_ioctl(file, pcm_file->substream, cmd,
				     (void __user *)arg);
}

/**
 * snd_pcm_kernel_ioctl - Execute PCM ioctl in the kernel-space
 * @substream: PCM substream
 * @cmd: IOCTL cmd
 * @arg: IOCTL argument
 *
 * The function is provided primarily for OSS layer and USB gadget drivers,
 * and it allows only the limited set of ioctls (hw_params, sw_params,
 * prepare, start, drain, drop, forward).
 *
 * Return: zero if successful, or a negative error code
 */
int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream,
			 unsigned int cmd, void *arg)
{
	snd_pcm_uframes_t *frames = arg;
	snd_pcm_sframes_t result;
	
	if (substream->runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;

	switch (cmd) {
	case SNDRV_PCM_IOCTL_FORWARD:
	{
		/* provided only for OSS; capture-only and no value returned */
		if (substream->stream != SNDRV_PCM_STREAM_CAPTURE)
			return -EINVAL;
		result = snd_pcm_forward(substream, *frames);
		return result < 0 ? result : 0;
	}
	case SNDRV_PCM_IOCTL_HW_PARAMS:
		return snd_pcm_hw_params(substream, arg);
	case SNDRV_PCM_IOCTL_SW_PARAMS:
		return snd_pcm_sw_params(substream, arg);
	case SNDRV_PCM_IOCTL_PREPARE:
		return snd_pcm_prepare(substream, NULL);
	case SNDRV_PCM_IOCTL_START:
		return snd_pcm_start_lock_irq(substream);
	case SNDRV_PCM_IOCTL_DRAIN:
		return snd_pcm_drain(substream, NULL);
	case SNDRV_PCM_IOCTL_DROP:
		return snd_pcm_drop(substream);
	case SNDRV_PCM_IOCTL_DELAY:
		return snd_pcm_delay(substream, frames);
	default:
		return -EINVAL;
	}
}
EXPORT_SYMBOL(snd_pcm_kernel_ioctl);

static ssize_t snd_pcm_read(struct file *file, char __user *buf, size_t count,
			    loff_t * offset)
{
	struct snd_pcm_file *pcm_file;
	struct snd_pcm_substream *substream;
	struct snd_pcm_runtime *runtime;
	snd_pcm_sframes_t result;

	pcm_file = file->private_data;
	substream = pcm_file->substream;
	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	runtime = substream->runtime;
	if (runtime->state == SNDRV_PCM_STATE_OPEN ||
	    runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;
	if (!frame_aligned(runtime, count))
		return -EINVAL;
	count = bytes_to_frames(runtime, count);
	result = snd_pcm_lib_read(substream, buf, count);
	if (result > 0)
		result = frames_to_bytes(runtime, result);
	return result;
}

static ssize_t snd_pcm_write(struct file *file, const char __user *buf,
			     size_t count, loff_t * offset)
{
	struct snd_pcm_file *pcm_file;
	struct snd_pcm_substream *substream;
	struct snd_pcm_runtime *runtime;
	snd_pcm_sframes_t result;

	pcm_file = file->private_data;
	substream = pcm_file->substream;
	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	runtime = substream->runtime;
	if (runtime->state == SNDRV_PCM_STATE_OPEN ||
	    runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;
	if (!frame_aligned(runtime, count))
		return -EINVAL;
	count = bytes_to_frames(runtime, count);
	result = snd_pcm_lib_write(substream, buf, count);
	if (result > 0)
		result = frames_to_bytes(runtime, result);
	return result;
}

static ssize_t snd_pcm_readv(struct kiocb *iocb, struct iov_iter *to)
{
	struct snd_pcm_file *pcm_file;
	struct snd_pcm_substream *substream;
	struct snd_pcm_runtime *runtime;
	snd_pcm_sframes_t result;
	unsigned long i;
	void __user **bufs;
	snd_pcm_uframes_t frames;

	pcm_file = iocb->ki_filp->private_data;
	substream = pcm_file->substream;
	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	runtime = substream->runtime;
	if (runtime->state == SNDRV_PCM_STATE_OPEN ||
	    runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;
	if (!iter_is_iovec(to))
		return -EINVAL;
	if (to->nr_segs > 1024 || to->nr_segs != runtime->channels)
		return -EINVAL;
	if (!frame_aligned(runtime, to->iov->iov_len))
		return -EINVAL;
	frames = bytes_to_samples(runtime, to->iov->iov_len);
	bufs = kmalloc_array(to->nr_segs, sizeof(void *), GFP_KERNEL);
	if (bufs == NULL)
		return -ENOMEM;
	for (i = 0; i < to->nr_segs; ++i)
		bufs[i] = to->iov[i].iov_base;
	result = snd_pcm_lib_readv(substream, bufs, frames);
	if (result > 0)
		result = frames_to_bytes(runtime, result);
	kfree(bufs);
	return result;
}

static ssize_t snd_pcm_writev(struct kiocb *iocb, struct iov_iter *from)
{
	struct snd_pcm_file *pcm_file;
	struct snd_pcm_substream *substream;
	struct snd_pcm_runtime *runtime;
	snd_pcm_sframes_t result;
	unsigned long i;
	void __user **bufs;
	snd_pcm_uframes_t frames;

	pcm_file = iocb->ki_filp->private_data;
	substream = pcm_file->substream;
	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	runtime = substream->runtime;
	if (runtime->state == SNDRV_PCM_STATE_OPEN ||
	    runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;
	if (!iter_is_iovec(from))
		return -EINVAL;
	if (from->nr_segs > 128 || from->nr_segs != runtime->channels ||
	    !frame_aligned(runtime, from->iov->iov_len))
		return -EINVAL;
	frames = bytes_to_samples(runtime, from->iov->iov_len);
	bufs = kmalloc_array(from->nr_segs, sizeof(void *), GFP_KERNEL);
	if (bufs == NULL)
		return -ENOMEM;
	for (i = 0; i < from->nr_segs; ++i)
		bufs[i] = from->iov[i].iov_base;
	result = snd_pcm_lib_writev(substream, bufs, frames);
	if (result > 0)
		result = frames_to_bytes(runtime, result);
	kfree(bufs);
	return result;
}

static __poll_t snd_pcm_poll(struct file *file, poll_table *wait)
{
	struct snd_pcm_file *pcm_file;
	struct snd_pcm_substream *substream;
	struct snd_pcm_runtime *runtime;
	__poll_t mask, ok;
	snd_pcm_uframes_t avail;

	pcm_file = file->private_data;

	substream = pcm_file->substream;
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
		ok = EPOLLOUT | EPOLLWRNORM;
	else
		ok = EPOLLIN | EPOLLRDNORM;
	if (PCM_RUNTIME_CHECK(substream))
		return ok | EPOLLERR;

	runtime = substream->runtime;
	if (runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return ok | EPOLLERR;

	poll_wait(file, &runtime->sleep, wait);

	mask = 0;
	snd_pcm_stream_lock_irq(substream);
	avail = snd_pcm_avail(substream);
	switch (runtime->state) {
	case SNDRV_PCM_STATE_RUNNING:
	case SNDRV_PCM_STATE_PREPARED:
	case SNDRV_PCM_STATE_PAUSED:
		if (avail >= runtime->control->avail_min)
			mask = ok;
		break;
	case SNDRV_PCM_STATE_DRAINING:
		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
			mask = ok;
			if (!avail)
				mask |= EPOLLERR;
		}
		break;
	default:
		mask = ok | EPOLLERR;
		break;
	}
	snd_pcm_stream_unlock_irq(substream);
	return mask;
}

/*
 * mmap support
 */

/*
 * Only on coherent architectures, we can mmap the status and the control records
 * for effcient data transfer.  On others, we have to use HWSYNC ioctl...
 */
#if defined(CONFIG_X86) || defined(CONFIG_PPC) || defined(CONFIG_ALPHA)
/*
 * mmap status record
 */
static vm_fault_t snd_pcm_mmap_status_fault(struct vm_fault *vmf)
{
	struct snd_pcm_substream *substream = vmf->vma->vm_private_data;
	struct snd_pcm_runtime *runtime;
	
	if (substream == NULL)
		return VM_FAULT_SIGBUS;
	runtime = substream->runtime;
	vmf->page = virt_to_page(runtime->status);
	get_page(vmf->page);
	return 0;
}

static const struct vm_operations_struct snd_pcm_vm_ops_status =
{
	.fault =	snd_pcm_mmap_status_fault,
};

static int snd_pcm_mmap_status(struct snd_pcm_substream *substream, struct file *file,
			       struct vm_area_struct *area)
{
	long size;
	if (!(area->vm_flags & VM_READ))
		return -EINVAL;
	size = area->vm_end - area->vm_start;
	if (size != PAGE_ALIGN(sizeof(struct snd_pcm_mmap_status)))
		return -EINVAL;
	area->vm_ops = &snd_pcm_vm_ops_status;
	area->vm_private_data = substream;
	vm_flags_mod(area, VM_DONTEXPAND | VM_DONTDUMP,
		     VM_WRITE | VM_MAYWRITE);

	return 0;
}

/*
 * mmap control record
 */
static vm_fault_t snd_pcm_mmap_control_fault(struct vm_fault *vmf)
{
	struct snd_pcm_substream *substream = vmf->vma->vm_private_data;
	struct snd_pcm_runtime *runtime;
	
	if (substream == NULL)
		return VM_FAULT_SIGBUS;
	runtime = substream->runtime;
	vmf->page = virt_to_page(runtime->control);
	get_page(vmf->page);
	return 0;
}

static const struct vm_operations_struct snd_pcm_vm_ops_control =
{
	.fault =	snd_pcm_mmap_control_fault,
};

static int snd_pcm_mmap_control(struct snd_pcm_substream *substream, struct file *file,
				struct vm_area_struct *area)
{
	long size;
	if (!(area->vm_flags & VM_READ))
		return -EINVAL;
	size = area->vm_end - area->vm_start;
	if (size != PAGE_ALIGN(sizeof(struct snd_pcm_mmap_control)))
		return -EINVAL;
	area->vm_ops = &snd_pcm_vm_ops_control;
	area->vm_private_data = substream;
	vm_flags_set(area, VM_DONTEXPAND | VM_DONTDUMP);
	return 0;
}

static bool pcm_status_mmap_allowed(struct snd_pcm_file *pcm_file)
{
	/* If drivers require the explicit sync (typically for non-coherent
	 * pages), we have to disable the mmap of status and control data
	 * to enforce the control via SYNC_PTR ioctl.
	 */
	if (pcm_file->substream->runtime->hw.info & SNDRV_PCM_INFO_EXPLICIT_SYNC)
		return false;
	/* See pcm_control_mmap_allowed() below.
	 * Since older alsa-lib requires both status and control mmaps to be
	 * coupled, we have to disable the status mmap for old alsa-lib, too.
	 */
	if (pcm_file->user_pversion < SNDRV_PROTOCOL_VERSION(2, 0, 14) &&
	    (pcm_file->substream->runtime->hw.info & SNDRV_PCM_INFO_SYNC_APPLPTR))
		return false;
	return true;
}

static bool pcm_control_mmap_allowed(struct snd_pcm_file *pcm_file)
{
	if (pcm_file->no_compat_mmap)
		return false;
	/* see above */
	if (pcm_file->substream->runtime->hw.info & SNDRV_PCM_INFO_EXPLICIT_SYNC)
		return false;
	/* Disallow the control mmap when SYNC_APPLPTR flag is set;
	 * it enforces the user-space to fall back to snd_pcm_sync_ptr(),
	 * thus it effectively assures the manual update of appl_ptr.
	 */
	if (pcm_file->substream->runtime->hw.info & SNDRV_PCM_INFO_SYNC_APPLPTR)
		return false;
	return true;
}

#else /* ! coherent mmap */
/*
 * don't support mmap for status and control records.
 */
#define pcm_status_mmap_allowed(pcm_file)	false
#define pcm_control_mmap_allowed(pcm_file)	false

static int snd_pcm_mmap_status(struct snd_pcm_substream *substream, struct file *file,
			       struct vm_area_struct *area)
{
	return -ENXIO;
}
static int snd_pcm_mmap_control(struct snd_pcm_substream *substream, struct file *file,
				struct vm_area_struct *area)
{
	return -ENXIO;
}
#endif /* coherent mmap */

/*
 * fault callback for mmapping a RAM page
 */
static vm_fault_t snd_pcm_mmap_data_fault(struct vm_fault *vmf)
{
	struct snd_pcm_substream *substream = vmf->vma->vm_private_data;
	struct snd_pcm_runtime *runtime;
	unsigned long offset;
	struct page * page;
	size_t dma_bytes;
	
	if (substream == NULL)
		return VM_FAULT_SIGBUS;
	runtime = substream->runtime;
	offset = vmf->pgoff << PAGE_SHIFT;
	dma_bytes = PAGE_ALIGN(runtime->dma_bytes);
	if (offset > dma_bytes - PAGE_SIZE)
		return VM_FAULT_SIGBUS;
	if (substream->ops->page)
		page = substream->ops->page(substream, offset);
	else if (!snd_pcm_get_dma_buf(substream))
		page = virt_to_page(runtime->dma_area + offset);
	else
		page = snd_sgbuf_get_page(snd_pcm_get_dma_buf(substream), offset);
	if (!page)
		return VM_FAULT_SIGBUS;
	get_page(page);
	vmf->page = page;
	return 0;
}

static const struct vm_operations_struct snd_pcm_vm_ops_data = {
	.open =		snd_pcm_mmap_data_open,
	.close =	snd_pcm_mmap_data_close,
};

static const struct vm_operations_struct snd_pcm_vm_ops_data_fault = {
	.open =		snd_pcm_mmap_data_open,
	.close =	snd_pcm_mmap_data_close,
	.fault =	snd_pcm_mmap_data_fault,
};

/*
 * mmap the DMA buffer on RAM
 */

/**
 * snd_pcm_lib_default_mmap - Default PCM data mmap function
 * @substream: PCM substream
 * @area: VMA
 *
 * This is the default mmap handler for PCM data.  When mmap pcm_ops is NULL,
 * this function is invoked implicitly.
 *
 * Return: zero if successful, or a negative error code
 */
int snd_pcm_lib_default_mmap(struct snd_pcm_substream *substream,
			     struct vm_area_struct *area)
{
	vm_flags_set(area, VM_DONTEXPAND | VM_DONTDUMP);
	if (!substream->ops->page &&
	    !snd_dma_buffer_mmap(snd_pcm_get_dma_buf(substream), area))
		return 0;
	/* mmap with fault handler */
	area->vm_ops = &snd_pcm_vm_ops_data_fault;
	return 0;
}
EXPORT_SYMBOL_GPL(snd_pcm_lib_default_mmap);

/*
 * mmap the DMA buffer on I/O memory area
 */
#if SNDRV_PCM_INFO_MMAP_IOMEM
/**
 * snd_pcm_lib_mmap_iomem - Default PCM data mmap function for I/O mem
 * @substream: PCM substream
 * @area: VMA
 *
 * When your hardware uses the iomapped pages as the hardware buffer and
 * wants to mmap it, pass this function as mmap pcm_ops.  Note that this
 * is supposed to work only on limited architectures.
 *
 * Return: zero if successful, or a negative error code
 */
int snd_pcm_lib_mmap_iomem(struct snd_pcm_substream *substream,
			   struct vm_area_struct *area)
{
	struct snd_pcm_runtime *runtime = substream->runtime;

	area->vm_page_prot = pgprot_noncached(area->vm_page_prot);
	return vm_iomap_memory(area, runtime->dma_addr, runtime->dma_bytes);
}
EXPORT_SYMBOL(snd_pcm_lib_mmap_iomem);
#endif /* SNDRV_PCM_INFO_MMAP */

/*
 * mmap DMA buffer
 */
int snd_pcm_mmap_data(struct snd_pcm_substream *substream, struct file *file,
		      struct vm_area_struct *area)
{
	struct snd_pcm_runtime *runtime;
	long size;
	unsigned long offset;
	size_t dma_bytes;
	int err;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
		if (!(area->vm_flags & (VM_WRITE|VM_READ)))
			return -EINVAL;
	} else {
		if (!(area->vm_flags & VM_READ))
			return -EINVAL;
	}
	runtime = substream->runtime;
	if (runtime->state == SNDRV_PCM_STATE_OPEN)
		return -EBADFD;
	if (!(runtime->info & SNDRV_PCM_INFO_MMAP))
		return -ENXIO;
	if (runtime->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED ||
	    runtime->access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED)
		return -EINVAL;
	size = area->vm_end - area->vm_start;
	offset = area->vm_pgoff << PAGE_SHIFT;
	dma_bytes = PAGE_ALIGN(runtime->dma_bytes);
	if ((size_t)size > dma_bytes)
		return -EINVAL;
	if (offset > dma_bytes - size)
		return -EINVAL;

	area->vm_ops = &snd_pcm_vm_ops_data;
	area->vm_private_data = substream;
	if (substream->ops->mmap)
		err = substream->ops->mmap(substream, area);
	else
		err = snd_pcm_lib_default_mmap(substream, area);
	if (!err)
		atomic_inc(&substream->mmap_count);
	return err;
}
EXPORT_SYMBOL(snd_pcm_mmap_data);

static int snd_pcm_mmap(struct file *file, struct vm_area_struct *area)
{
	struct snd_pcm_file * pcm_file;
	struct snd_pcm_substream *substream;	
	unsigned long offset;
	
	pcm_file = file->private_data;
	substream = pcm_file->substream;
	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	if (substream->runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;

	offset = area->vm_pgoff << PAGE_SHIFT;
	switch (offset) {
	case SNDRV_PCM_MMAP_OFFSET_STATUS_OLD:
		if (pcm_file->no_compat_mmap || !IS_ENABLED(CONFIG_64BIT))
			return -ENXIO;
		fallthrough;
	case SNDRV_PCM_MMAP_OFFSET_STATUS_NEW:
		if (!pcm_status_mmap_allowed(pcm_file))
			return -ENXIO;
		return snd_pcm_mmap_status(substream, file, area);
	case SNDRV_PCM_MMAP_OFFSET_CONTROL_OLD:
		if (pcm_file->no_compat_mmap || !IS_ENABLED(CONFIG_64BIT))
			return -ENXIO;
		fallthrough;
	case SNDRV_PCM_MMAP_OFFSET_CONTROL_NEW:
		if (!pcm_control_mmap_allowed(pcm_file))
			return -ENXIO;
		return snd_pcm_mmap_control(substream, file, area);
	default:
		return snd_pcm_mmap_data(substream, file, area);
	}
	return 0;
}

static int snd_pcm_fasync(int fd, struct file * file, int on)
{
	struct snd_pcm_file * pcm_file;
	struct snd_pcm_substream *substream;
	struct snd_pcm_runtime *runtime;

	pcm_file = file->private_data;
	substream = pcm_file->substream;
	if (PCM_RUNTIME_CHECK(substream))
		return -ENXIO;
	runtime = substream->runtime;
	if (runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
		return -EBADFD;
	return snd_fasync_helper(fd, file, on, &runtime->fasync);
}

/*
 * ioctl32 compat
 */
#ifdef CONFIG_COMPAT
#include "pcm_compat.c"
#else
#define snd_pcm_ioctl_compat	NULL
#endif

/*
 *  To be removed helpers to keep binary compatibility
 */

#ifdef CONFIG_SND_SUPPORT_OLD_API
#define __OLD_TO_NEW_MASK(x) ((x&7)|((x&0x07fffff8)<<5))
#define __NEW_TO_OLD_MASK(x) ((x&7)|((x&0xffffff00)>>5))

static void snd_pcm_hw_convert_from_old_params(struct snd_pcm_hw_params *params,
					       struct snd_pcm_hw_params_old *oparams)
{
	unsigned int i;

	memset(params, 0, sizeof(*params));
	params->flags = oparams->flags;
	for (i = 0; i < ARRAY_SIZE(oparams->masks); i++)
		params->masks[i].bits[0] = oparams->masks[i];
	memcpy(params->intervals, oparams->intervals, sizeof(oparams->intervals));
	params->rmask = __OLD_TO_NEW_MASK(oparams->rmask);
	params->cmask = __OLD_TO_NEW_MASK(oparams->cmask);
	params->info = oparams->info;
	params->msbits = oparams->msbits;
	params->rate_num = oparams->rate_num;
	params->rate_den = oparams->rate_den;
	params->fifo_size = oparams->fifo_size;
}

static void snd_pcm_hw_convert_to_old_params(struct snd_pcm_hw_params_old *oparams,
					     struct snd_pcm_hw_params *params)
{
	unsigned int i;

	memset(oparams, 0, sizeof(*oparams));
	oparams->flags = params->flags;
	for (i = 0; i < ARRAY_SIZE(oparams->masks); i++)
		oparams->masks[i] = params->masks[i].bits[0];
	memcpy(oparams->intervals, params->intervals, sizeof(oparams->intervals));
	oparams->rmask = __NEW_TO_OLD_MASK(params->rmask);
	oparams->cmask = __NEW_TO_OLD_MASK(params->cmask);
	oparams->info = params->info;
	oparams->msbits = params->msbits;
	oparams->rate_num = params->rate_num;
	oparams->rate_den = params->rate_den;
	oparams->fifo_size = params->fifo_size;
}

static int snd_pcm_hw_refine_old_user(struct snd_pcm_substream *substream,
				      struct snd_pcm_hw_params_old __user * _oparams)
{
	struct snd_pcm_hw_params *params;
	struct snd_pcm_hw_params_old *oparams = NULL;
	int err;

	params = kmalloc(sizeof(*params), GFP_KERNEL);
	if (!params)
		return -ENOMEM;

	oparams = memdup_user(_oparams, sizeof(*oparams));
	if (IS_ERR(oparams)) {
		err = PTR_ERR(oparams);
		goto out;
	}
	snd_pcm_hw_convert_from_old_params(params, oparams);
	err = snd_pcm_hw_refine(substream, params);
	if (err < 0)
		goto out_old;

	err = fixup_unreferenced_params(substream, params);
	if (err < 0)
		goto out_old;

	snd_pcm_hw_convert_to_old_params(oparams, params);
	if (copy_to_user(_oparams, oparams, sizeof(*oparams)))
		err = -EFAULT;
out_old:
	kfree(oparams);
out:
	kfree(params);
	return err;
}

static int snd_pcm_hw_params_old_user(struct snd_pcm_substream *substream,
				      struct snd_pcm_hw_params_old __user * _oparams)
{
	struct snd_pcm_hw_params *params;
	struct snd_pcm_hw_params_old *oparams = NULL;
	int err;

	params = kmalloc(sizeof(*params), GFP_KERNEL);
	if (!params)
		return -ENOMEM;

	oparams = memdup_user(_oparams, sizeof(*oparams));
	if (IS_ERR(oparams)) {
		err = PTR_ERR(oparams);
		goto out;
	}

	snd_pcm_hw_convert_from_old_params(params, oparams);
	err = snd_pcm_hw_params(substream, params);
	if (err < 0)
		goto out_old;

	snd_pcm_hw_convert_to_old_params(oparams, params);
	if (copy_to_user(_oparams, oparams, sizeof(*oparams)))
		err = -EFAULT;
out_old:
	kfree(oparams);
out:
	kfree(params);
	return err;
}
#endif /* CONFIG_SND_SUPPORT_OLD_API */

#ifndef CONFIG_MMU
static unsigned long snd_pcm_get_unmapped_area(struct file *file,
					       unsigned long addr,
					       unsigned long len,
					       unsigned long pgoff,
					       unsigned long flags)
{
	struct snd_pcm_file *pcm_file = file->private_data;
	struct snd_pcm_substream *substream = pcm_file->substream;
	struct snd_pcm_runtime *runtime = substream->runtime;
	unsigned long offset = pgoff << PAGE_SHIFT;

	switch (offset) {
	case SNDRV_PCM_MMAP_OFFSET_STATUS_NEW:
		return (unsigned long)runtime->status;
	case SNDRV_PCM_MMAP_OFFSET_CONTROL_NEW:
		return (unsigned long)runtime->control;
	default:
		return (unsigned long)runtime->dma_area + offset;
	}
}
#else
# define snd_pcm_get_unmapped_area NULL
#endif

/*
 *  Register section
 */

const struct file_operations snd_pcm_f_ops[2] = {
	{
		.owner =		THIS_MODULE,
		.write =		snd_pcm_write,
		.write_iter =		snd_pcm_writev,
		.open =			snd_pcm_playback_open,
		.release =		snd_pcm_release,
		.llseek =		no_llseek,
		.poll =			snd_pcm_poll,
		.unlocked_ioctl =	snd_pcm_ioctl,
		.compat_ioctl = 	snd_pcm_ioctl_compat,
		.mmap =			snd_pcm_mmap,
		.fasync =		snd_pcm_fasync,
		.get_unmapped_area =	snd_pcm_get_unmapped_area,
	},
	{
		.owner =		THIS_MODULE,
		.read =			snd_pcm_read,
		.read_iter =		snd_pcm_readv,
		.open =			snd_pcm_capture_open,
		.release =		snd_pcm_release,
		.llseek =		no_llseek,
		.poll =			snd_pcm_poll,
		.unlocked_ioctl =	snd_pcm_ioctl,
		.compat_ioctl = 	snd_pcm_ioctl_compat,
		.mmap =			snd_pcm_mmap,
		.fasync =		snd_pcm_fasync,
		.get_unmapped_area =	snd_pcm_get_unmapped_area,
	}
};