Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2479 insertions, 0 deletions

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
new file mode 100644
index 000000000..c376471cf
--- /dev/null
+++ b/sound/core/pcm_lib.c
@@ -0,0 +1,2479 @@
+/*
+ *  Digital Audio (PCM) abstract layer
+ *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
+ *                   Abramo Bagnara <abramo@alsa-project.org>
+ *
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ */
+
+#include <linux/slab.h>
+#include <linux/sched/signal.h>
+#include <linux/time.h>
+#include <linux/math64.h>
+#include <linux/export.h>
+#include <sound/core.h>
+#include <sound/control.h>
+#include <sound/tlv.h>
+#include <sound/info.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/timer.h>
+
+#include "pcm_local.h"
+
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
+#define CREATE_TRACE_POINTS
+#include "pcm_trace.h"
+#else
+#define trace_hwptr(substream, pos, in_interrupt)
+#define trace_xrun(substream)
+#define trace_hw_ptr_error(substream, reason)
+#define trace_applptr(substream, prev, curr)
+#endif
+
+static int fill_silence_frames(struct snd_pcm_substream *substream,
+			       snd_pcm_uframes_t off, snd_pcm_uframes_t frames);
+
+/*
+ * fill ring buffer with silence
+ * runtime->silence_start: starting pointer to silence area
+ * runtime->silence_filled: size filled with silence
+ * runtime->silence_threshold: threshold from application
+ * runtime->silence_size: maximal size from application
+ *
+ * when runtime->silence_size >= runtime->boundary - fill processed area with silence immediately
+ */
+void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_uframes_t new_hw_ptr)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_pcm_uframes_t frames, ofs, transfer;
+	int err;
+
+	if (runtime->silence_size < runtime->boundary) {
+		snd_pcm_sframes_t noise_dist, n;
+		snd_pcm_uframes_t appl_ptr = READ_ONCE(runtime->control->appl_ptr);
+		if (runtime->silence_start != appl_ptr) {
+			n = appl_ptr - runtime->silence_start;
+			if (n < 0)
+				n += runtime->boundary;
+			if ((snd_pcm_uframes_t)n < runtime->silence_filled)
+				runtime->silence_filled -= n;
+			else
+				runtime->silence_filled = 0;
+			runtime->silence_start = appl_ptr;
+		}
+		if (runtime->silence_filled >= runtime->buffer_size)
+			return;
+		noise_dist = snd_pcm_playback_hw_avail(runtime) + runtime->silence_filled;
+		if (noise_dist >= (snd_pcm_sframes_t) runtime->silence_threshold)
+			return;
+		frames = runtime->silence_threshold - noise_dist;
+		if (frames > runtime->silence_size)
+			frames = runtime->silence_size;
+	} else {
+		if (new_hw_ptr == ULONG_MAX) {	/* initialization */
+			snd_pcm_sframes_t avail = snd_pcm_playback_hw_avail(runtime);
+			if (avail > runtime->buffer_size)
+				avail = runtime->buffer_size;
+			runtime->silence_filled = avail > 0 ? avail : 0;
+			runtime->silence_start = (runtime->status->hw_ptr +
+						  runtime->silence_filled) %
+						 runtime->boundary;
+		} else {
+			ofs = runtime->status->hw_ptr;
+			frames = new_hw_ptr - ofs;
+			if ((snd_pcm_sframes_t)frames < 0)
+				frames += runtime->boundary;
+			runtime->silence_filled -= frames;
+			if ((snd_pcm_sframes_t)runtime->silence_filled < 0) {
+				runtime->silence_filled = 0;
+				runtime->silence_start = new_hw_ptr;
+			} else {
+				runtime->silence_start = ofs;
+			}
+		}
+		frames = runtime->buffer_size - runtime->silence_filled;
+	}
+	if (snd_BUG_ON(frames > runtime->buffer_size))
+		return;
+	if (frames == 0)
+		return;
+	ofs = runtime->silence_start % runtime->buffer_size;
+	while (frames > 0) {
+		transfer = ofs + frames > runtime->buffer_size ? runtime->buffer_size - ofs : frames;
+		err = fill_silence_frames(substream, ofs, transfer);
+		snd_BUG_ON(err < 0);
+		runtime->silence_filled += transfer;
+		frames -= transfer;
+		ofs = 0;
+	}
+}
+
+#ifdef CONFIG_SND_DEBUG
+void snd_pcm_debug_name(struct snd_pcm_substream *substream,
+			   char *name, size_t len)
+{
+	snprintf(name, len, "pcmC%dD%d%c:%d",
+		 substream->pcm->card->number,
+		 substream->pcm->device,
+		 substream->stream ? 'c' : 'p',
+		 substream->number);
+}
+EXPORT_SYMBOL(snd_pcm_debug_name);
+#endif
+
+#define XRUN_DEBUG_BASIC	(1<<0)
+#define XRUN_DEBUG_STACK	(1<<1)	/* dump also stack */
+#define XRUN_DEBUG_JIFFIESCHECK	(1<<2)	/* do jiffies check */
+
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
+
+#define xrun_debug(substream, mask) \
+			((substream)->pstr->xrun_debug & (mask))
+#else
+#define xrun_debug(substream, mask)	0
+#endif
+
+#define dump_stack_on_xrun(substream) do {			\
+		if (xrun_debug(substream, XRUN_DEBUG_STACK))	\
+			dump_stack();				\
+	} while (0)
+
+/* call with stream lock held */
+void __snd_pcm_xrun(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+
+	trace_xrun(substream);
+	if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE)
+		snd_pcm_gettime(runtime, (struct timespec *)&runtime->status->tstamp);
+	snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
+	if (xrun_debug(substream, XRUN_DEBUG_BASIC)) {
+		char name[16];
+		snd_pcm_debug_name(substream, name, sizeof(name));
+		pcm_warn(substream->pcm, "XRUN: %s\n", name);
+		dump_stack_on_xrun(substream);
+	}
+}
+
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
+#define hw_ptr_error(substream, in_interrupt, reason, fmt, args...)	\
+	do {								\
+		trace_hw_ptr_error(substream, reason);	\
+		if (xrun_debug(substream, XRUN_DEBUG_BASIC)) {		\
+			pr_err_ratelimited("ALSA: PCM: [%c] " reason ": " fmt, \
+					   (in_interrupt) ? 'Q' : 'P', ##args);	\
+			dump_stack_on_xrun(substream);			\
+		}							\
+	} while (0)
+
+#else /* ! CONFIG_SND_PCM_XRUN_DEBUG */
+
+#define hw_ptr_error(substream, fmt, args...) do { } while (0)
+
+#endif
+
+int snd_pcm_update_state(struct snd_pcm_substream *substream,
+			 struct snd_pcm_runtime *runtime)
+{
+	snd_pcm_uframes_t avail;
+
+	avail = snd_pcm_avail(substream);
+	if (avail > runtime->avail_max)
+		runtime->avail_max = avail;
+	if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
+		if (avail >= runtime->buffer_size) {
+			snd_pcm_drain_done(substream);
+			return -EPIPE;
+		}
+	} else {
+		if (avail >= runtime->stop_threshold) {
+			__snd_pcm_xrun(substream);
+			return -EPIPE;
+		}
+	}
+	if (runtime->twake) {
+		if (avail >= runtime->twake)
+			wake_up(&runtime->tsleep);
+	} else if (avail >= runtime->control->avail_min)
+		wake_up(&runtime->sleep);
+	return 0;
+}
+
+static void update_audio_tstamp(struct snd_pcm_substream *substream,
+				struct timespec *curr_tstamp,
+				struct timespec *audio_tstamp)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	u64 audio_frames, audio_nsecs;
+	struct timespec driver_tstamp;
+
+	if (runtime->tstamp_mode != SNDRV_PCM_TSTAMP_ENABLE)
+		return;
+
+	if (!(substream->ops->get_time_info) ||
+		(runtime->audio_tstamp_report.actual_type ==
+			SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) {
+
+		/*
+		 * provide audio timestamp derived from pointer position
+		 * add delay only if requested
+		 */
+
+		audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr;
+
+		if (runtime->audio_tstamp_config.report_delay) {
+			if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+				audio_frames -=  runtime->delay;
+			else
+				audio_frames +=  runtime->delay;
+		}
+		audio_nsecs = div_u64(audio_frames * 1000000000LL,
+				runtime->rate);
+		*audio_tstamp = ns_to_timespec(audio_nsecs);
+	}
+	if (!timespec_equal(&runtime->status->audio_tstamp, audio_tstamp)) {
+		runtime->status->audio_tstamp = *audio_tstamp;
+		runtime->status->tstamp = *curr_tstamp;
+	}
+
+	/*
+	 * re-take a driver timestamp to let apps detect if the reference tstamp
+	 * read by low-level hardware was provided with a delay
+	 */
+	snd_pcm_gettime(substream->runtime, (struct timespec *)&driver_tstamp);
+	runtime->driver_tstamp = driver_tstamp;
+}
+
+static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
+				  unsigned int in_interrupt)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_pcm_uframes_t pos;
+	snd_pcm_uframes_t old_hw_ptr, new_hw_ptr, hw_base;
+	snd_pcm_sframes_t hdelta, delta;
+	unsigned long jdelta;
+	unsigned long curr_jiffies;
+	struct timespec curr_tstamp;
+	struct timespec audio_tstamp;
+	int crossed_boundary = 0;
+
+	old_hw_ptr = runtime->status->hw_ptr;
+
+	/*
+	 * group pointer, time and jiffies reads to allow for more
+	 * accurate correlations/corrections.
+	 * The values are stored at the end of this routine after
+	 * corrections for hw_ptr position
+	 */
+	pos = substream->ops->pointer(substream);
+	curr_jiffies = jiffies;
+	if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) {
+		if ((substream->ops->get_time_info) &&
+			(runtime->audio_tstamp_config.type_requested != SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) {
+			substream->ops->get_time_info(substream, &curr_tstamp,
+						&audio_tstamp,
+						&runtime->audio_tstamp_config,
+						&runtime->audio_tstamp_report);
+
+			/* re-test in case tstamp type is not supported in hardware and was demoted to DEFAULT */
+			if (runtime->audio_tstamp_report.actual_type == SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)
+				snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp);
+		} else
+			snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp);
+	}
+
+	if (pos == SNDRV_PCM_POS_XRUN) {
+		__snd_pcm_xrun(substream);
+		return -EPIPE;
+	}
+	if (pos >= runtime->buffer_size) {
+		if (printk_ratelimit()) {
+			char name[16];
+			snd_pcm_debug_name(substream, name, sizeof(name));
+			pcm_err(substream->pcm,
+				"invalid position: %s, pos = %ld, buffer size = %ld, period size = %ld\n",
+				name, pos, runtime->buffer_size,
+				runtime->period_size);
+		}
+		pos = 0;
+	}
+	pos -= pos % runtime->min_align;
+	trace_hwptr(substream, pos, in_interrupt);
+	hw_base = runtime->hw_ptr_base;
+	new_hw_ptr = hw_base + pos;
+	if (in_interrupt) {
+		/* we know that one period was processed */
+		/* delta = "expected next hw_ptr" for in_interrupt != 0 */
+		delta = runtime->hw_ptr_interrupt + runtime->period_size;
+		if (delta > new_hw_ptr) {
+			/* check for double acknowledged interrupts */
+			hdelta = curr_jiffies - runtime->hw_ptr_jiffies;
+			if (hdelta > runtime->hw_ptr_buffer_jiffies/2 + 1) {
+				hw_base += runtime->buffer_size;
+				if (hw_base >= runtime->boundary) {
+					hw_base = 0;
+					crossed_boundary++;
+				}
+				new_hw_ptr = hw_base + pos;
+				goto __delta;
+			}
+		}
+	}
+	/* new_hw_ptr might be lower than old_hw_ptr in case when */
+	/* pointer crosses the end of the ring buffer */
+	if (new_hw_ptr < old_hw_ptr) {
+		hw_base += runtime->buffer_size;
+		if (hw_base >= runtime->boundary) {
+			hw_base = 0;
+			crossed_boundary++;
+		}
+		new_hw_ptr = hw_base + pos;
+	}
+      __delta:
+	delta = new_hw_ptr - old_hw_ptr;
+	if (delta < 0)
+		delta += runtime->boundary;
+
+	if (runtime->no_period_wakeup) {
+		snd_pcm_sframes_t xrun_threshold;
+		/*
+		 * Without regular period interrupts, we have to check
+		 * the elapsed time to detect xruns.
+		 */
+		jdelta = curr_jiffies - runtime->hw_ptr_jiffies;
+		if (jdelta < runtime->hw_ptr_buffer_jiffies / 2)
+			goto no_delta_check;
+		hdelta = jdelta - delta * HZ / runtime->rate;
+		xrun_threshold = runtime->hw_ptr_buffer_jiffies / 2 + 1;
+		while (hdelta > xrun_threshold) {
+			delta += runtime->buffer_size;
+			hw_base += runtime->buffer_size;
+			if (hw_base >= runtime->boundary) {
+				hw_base = 0;
+				crossed_boundary++;
+			}
+			new_hw_ptr = hw_base + pos;
+			hdelta -= runtime->hw_ptr_buffer_jiffies;
+		}
+		goto no_delta_check;
+	}
+
+	/* something must be really wrong */
+	if (delta >= runtime->buffer_size + runtime->period_size) {
+		hw_ptr_error(substream, in_interrupt, "Unexpected hw_ptr",
+			     "(stream=%i, pos=%ld, new_hw_ptr=%ld, old_hw_ptr=%ld)\n",
+			     substream->stream, (long)pos,
+			     (long)new_hw_ptr, (long)old_hw_ptr);
+		return 0;
+	}
+
+	/* Do jiffies check only in xrun_debug mode */
+	if (!xrun_debug(substream, XRUN_DEBUG_JIFFIESCHECK))
+		goto no_jiffies_check;
+
+	/* Skip the jiffies check for hardwares with BATCH flag.
+	 * Such hardware usually just increases the position at each IRQ,
+	 * thus it can't give any strange position.
+	 */
+	if (runtime->hw.info & SNDRV_PCM_INFO_BATCH)
+		goto no_jiffies_check;
+	hdelta = delta;
+	if (hdelta < runtime->delay)
+		goto no_jiffies_check;
+	hdelta -= runtime->delay;
+	jdelta = curr_jiffies - runtime->hw_ptr_jiffies;
+	if (((hdelta * HZ) / runtime->rate) > jdelta + HZ/100) {
+		delta = jdelta /
+			(((runtime->period_size * HZ) / runtime->rate)
+								+ HZ/100);
+		/* move new_hw_ptr according jiffies not pos variable */
+		new_hw_ptr = old_hw_ptr;
+		hw_base = delta;
+		/* use loop to avoid checks for delta overflows */
+		/* the delta value is small or zero in most cases */
+		while (delta > 0) {
+			new_hw_ptr += runtime->period_size;
+			if (new_hw_ptr >= runtime->boundary) {
+				new_hw_ptr -= runtime->boundary;
+				crossed_boundary--;
+			}
+			delta--;
+		}
+		/* align hw_base to buffer_size */
+		hw_ptr_error(substream, in_interrupt, "hw_ptr skipping",
+			     "(pos=%ld, delta=%ld, period=%ld, jdelta=%lu/%lu/%lu, hw_ptr=%ld/%ld)\n",
+			     (long)pos, (long)hdelta,
+			     (long)runtime->period_size, jdelta,
+			     ((hdelta * HZ) / runtime->rate), hw_base,
+			     (unsigned long)old_hw_ptr,
+			     (unsigned long)new_hw_ptr);
+		/* reset values to proper state */
+		delta = 0;
+		hw_base = new_hw_ptr - (new_hw_ptr % runtime->buffer_size);
+	}
+ no_jiffies_check:
+	if (delta > runtime->period_size + runtime->period_size / 2) {
+		hw_ptr_error(substream, in_interrupt,
+			     "Lost interrupts?",
+			     "(stream=%i, delta=%ld, new_hw_ptr=%ld, old_hw_ptr=%ld)\n",
+			     substream->stream, (long)delta,
+			     (long)new_hw_ptr,
+			     (long)old_hw_ptr);
+	}
+
+ no_delta_check:
+	if (runtime->status->hw_ptr == new_hw_ptr) {
+		runtime->hw_ptr_jiffies = curr_jiffies;
+		update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp);
+		return 0;
+	}
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
+	    runtime->silence_size > 0)
+		snd_pcm_playback_silence(substream, new_hw_ptr);
+
+	if (in_interrupt) {
+		delta = new_hw_ptr - runtime->hw_ptr_interrupt;
+		if (delta < 0)
+			delta += runtime->boundary;
+		delta -= (snd_pcm_uframes_t)delta % runtime->period_size;
+		runtime->hw_ptr_interrupt += delta;
+		if (runtime->hw_ptr_interrupt >= runtime->boundary)
+			runtime->hw_ptr_interrupt -= runtime->boundary;
+	}
+	runtime->hw_ptr_base = hw_base;
+	runtime->status->hw_ptr = new_hw_ptr;
+	runtime->hw_ptr_jiffies = curr_jiffies;
+	if (crossed_boundary) {
+		snd_BUG_ON(crossed_boundary != 1);
+		runtime->hw_ptr_wrap += runtime->boundary;
+	}
+
+	update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp);
+
+	return snd_pcm_update_state(substream, runtime);
+}
+
+/* CAUTION: call it with irq disabled */
+int snd_pcm_update_hw_ptr(struct snd_pcm_substream *substream)
+{
+	return snd_pcm_update_hw_ptr0(substream, 0);
+}
+
+/**
+ * snd_pcm_set_ops - set the PCM operators
+ * @pcm: the pcm instance
+ * @direction: stream direction, SNDRV_PCM_STREAM_XXX
+ * @ops: the operator table
+ *
+ * Sets the given PCM operators to the pcm instance.
+ */
+void snd_pcm_set_ops(struct snd_pcm *pcm, int direction,
+		     const struct snd_pcm_ops *ops)
+{
+	struct snd_pcm_str *stream = &pcm->streams[direction];
+	struct snd_pcm_substream *substream;
+	
+	for (substream = stream->substream; substream != NULL; substream = substream->next)
+		substream->ops = ops;
+}
+EXPORT_SYMBOL(snd_pcm_set_ops);
+
+/**
+ * snd_pcm_sync - set the PCM sync id
+ * @substream: the pcm substream
+ *
+ * Sets the PCM sync identifier for the card.
+ */
+void snd_pcm_set_sync(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	
+	runtime->sync.id32[0] = substream->pcm->card->number;
+	runtime->sync.id32[1] = -1;
+	runtime->sync.id32[2] = -1;
+	runtime->sync.id32[3] = -1;
+}
+EXPORT_SYMBOL(snd_pcm_set_sync);
+
+/*
+ *  Standard ioctl routine
+ */
+
+static inline unsigned int div32(unsigned int a, unsigned int b, 
+				 unsigned int *r)
+{
+	if (b == 0) {
+		*r = 0;
+		return UINT_MAX;
+	}
+	*r = a % b;
+	return a / b;
+}
+
+static inline unsigned int div_down(unsigned int a, unsigned int b)
+{
+	if (b == 0)
+		return UINT_MAX;
+	return a / b;
+}
+
+static inline unsigned int div_up(unsigned int a, unsigned int b)
+{
+	unsigned int r;
+	unsigned int q;
+	if (b == 0)
+		return UINT_MAX;
+	q = div32(a, b, &r);
+	if (r)
+		++q;
+	return q;
+}
+
+static inline unsigned int mul(unsigned int a, unsigned int b)
+{
+	if (a == 0)
+		return 0;
+	if (div_down(UINT_MAX, a) < b)
+		return UINT_MAX;
+	return a * b;
+}
+
+static inline unsigned int muldiv32(unsigned int a, unsigned int b,
+				    unsigned int c, unsigned int *r)
+{
+	u_int64_t n = (u_int64_t) a * b;
+	if (c == 0) {
+		*r = 0;
+		return UINT_MAX;
+	}
+	n = div_u64_rem(n, c, r);
+	if (n >= UINT_MAX) {
+		*r = 0;
+		return UINT_MAX;
+	}
+	return n;
+}
+
+/**
+ * snd_interval_refine - refine the interval value of configurator
+ * @i: the interval value to refine
+ * @v: the interval value to refer to
+ *
+ * Refines the interval value with the reference value.
+ * The interval is changed to the range satisfying both intervals.
+ * The interval status (min, max, integer, etc.) are evaluated.
+ *
+ * Return: Positive if the value is changed, zero if it's not changed, or a
+ * negative error code.
+ */
+int snd_interval_refine(struct snd_interval *i, const struct snd_interval *v)
+{
+	int changed = 0;
+	if (snd_BUG_ON(snd_interval_empty(i)))
+		return -EINVAL;
+	if (i->min < v->min) {
+		i->min = v->min;
+		i->openmin = v->openmin;
+		changed = 1;
+	} else if (i->min == v->min && !i->openmin && v->openmin) {
+		i->openmin = 1;
+		changed = 1;
+	}
+	if (i->max > v->max) {
+		i->max = v->max;
+		i->openmax = v->openmax;
+		changed = 1;
+	} else if (i->max == v->max && !i->openmax && v->openmax) {
+		i->openmax = 1;
+		changed = 1;
+	}
+	if (!i->integer && v->integer) {
+		i->integer = 1;
+		changed = 1;
+	}
+	if (i->integer) {
+		if (i->openmin) {
+			i->min++;
+			i->openmin = 0;
+		}
+		if (i->openmax) {
+			i->max--;
+			i->openmax = 0;
+		}
+	} else if (!i->openmin && !i->openmax && i->min == i->max)
+		i->integer = 1;
+	if (snd_interval_checkempty(i)) {
+		snd_interval_none(i);
+		return -EINVAL;
+	}
+	return changed;
+}
+EXPORT_SYMBOL(snd_interval_refine);
+
+static int snd_interval_refine_first(struct snd_interval *i)
+{
+	const unsigned int last_max = i->max;
+
+	if (snd_BUG_ON(snd_interval_empty(i)))
+		return -EINVAL;
+	if (snd_interval_single(i))
+		return 0;
+	i->max = i->min;
+	if (i->openmin)
+		i->max++;
+	/* only exclude max value if also excluded before refine */
+	i->openmax = (i->openmax && i->max >= last_max);
+	return 1;
+}
+
+static int snd_interval_refine_last(struct snd_interval *i)
+{
+	const unsigned int last_min = i->min;
+
+	if (snd_BUG_ON(snd_interval_empty(i)))
+		return -EINVAL;
+	if (snd_interval_single(i))
+		return 0;
+	i->min = i->max;
+	if (i->openmax)
+		i->min--;
+	/* only exclude min value if also excluded before refine */
+	i->openmin = (i->openmin && i->min <= last_min);
+	return 1;
+}
+
+void snd_interval_mul(const struct snd_interval *a, const struct snd_interval *b, struct snd_interval *c)
+{
+	if (a->empty || b->empty) {
+		snd_interval_none(c);
+		return;
+	}
+	c->empty = 0;
+	c->min = mul(a->min, b->min);
+	c->openmin = (a->openmin || b->openmin);
+	c->max = mul(a->max,  b->max);
+	c->openmax = (a->openmax || b->openmax);
+	c->integer = (a->integer && b->integer);
+}
+
+/**
+ * snd_interval_div - refine the interval value with division
+ * @a: dividend
+ * @b: divisor
+ * @c: quotient
+ *
+ * c = a / b
+ *
+ * Returns non-zero if the value is changed, zero if not changed.
+ */
+void snd_interval_div(const struct snd_interval *a, const struct snd_interval *b, struct snd_interval *c)
+{
+	unsigned int r;
+	if (a->empty || b->empty) {
+		snd_interval_none(c);
+		return;
+	}
+	c->empty = 0;
+	c->min = div32(a->min, b->max, &r);
+	c->openmin = (r || a->openmin || b->openmax);
+	if (b->min > 0) {
+		c->max = div32(a->max, b->min, &r);
+		if (r) {
+			c->max++;
+			c->openmax = 1;
+		} else
+			c->openmax = (a->openmax || b->openmin);
+	} else {
+		c->max = UINT_MAX;
+		c->openmax = 0;
+	}
+	c->integer = 0;
+}
+
+/**
+ * snd_interval_muldivk - refine the interval value
+ * @a: dividend 1
+ * @b: dividend 2
+ * @k: divisor (as integer)
+ * @c: result
+  *
+ * c = a * b / k
+ *
+ * Returns non-zero if the value is changed, zero if not changed.
+ */
+void snd_interval_muldivk(const struct snd_interval *a, const struct snd_interval *b,
+		      unsigned int k, struct snd_interval *c)
+{
+	unsigned int r;
+	if (a->empty || b->empty) {
+		snd_interval_none(c);
+		return;
+	}
+	c->empty = 0;
+	c->min = muldiv32(a->min, b->min, k, &r);
+	c->openmin = (r || a->openmin || b->openmin);
+	c->max = muldiv32(a->max, b->max, k, &r);
+	if (r) {
+		c->max++;
+		c->openmax = 1;
+	} else
+		c->openmax = (a->openmax || b->openmax);
+	c->integer = 0;
+}
+
+/**
+ * snd_interval_mulkdiv - refine the interval value
+ * @a: dividend 1
+ * @k: dividend 2 (as integer)
+ * @b: divisor
+ * @c: result
+ *
+ * c = a * k / b
+ *
+ * Returns non-zero if the value is changed, zero if not changed.
+ */
+void snd_interval_mulkdiv(const struct snd_interval *a, unsigned int k,
+		      const struct snd_interval *b, struct snd_interval *c)
+{
+	unsigned int r;
+	if (a->empty || b->empty) {
+		snd_interval_none(c);
+		return;
+	}
+	c->empty = 0;
+	c->min = muldiv32(a->min, k, b->max, &r);
+	c->openmin = (r || a->openmin || b->openmax);
+	if (b->min > 0) {
+		c->max = muldiv32(a->max, k, b->min, &r);
+		if (r) {
+			c->max++;
+			c->openmax = 1;
+		} else
+			c->openmax = (a->openmax || b->openmin);
+	} else {
+		c->max = UINT_MAX;
+		c->openmax = 0;
+	}
+	c->integer = 0;
+}
+
+/* ---- */
+
+
+/**
+ * snd_interval_ratnum - refine the interval value
+ * @i: interval to refine
+ * @rats_count: number of ratnum_t 
+ * @rats: ratnum_t array
+ * @nump: pointer to store the resultant numerator
+ * @denp: pointer to store the resultant denominator
+ *
+ * Return: Positive if the value is changed, zero if it's not changed, or a
+ * negative error code.
+ */
+int snd_interval_ratnum(struct snd_interval *i,
+			unsigned int rats_count, const struct snd_ratnum *rats,
+			unsigned int *nump, unsigned int *denp)
+{
+	unsigned int best_num, best_den;
+	int best_diff;
+	unsigned int k;
+	struct snd_interval t;
+	int err;
+	unsigned int result_num, result_den;
+	int result_diff;
+
+	best_num = best_den = best_diff = 0;
+	for (k = 0; k < rats_count; ++k) {
+		unsigned int num = rats[k].num;
+		unsigned int den;
+		unsigned int q = i->min;
+		int diff;
+		if (q == 0)
+			q = 1;
+		den = div_up(num, q);
+		if (den < rats[k].den_min)
+			continue;
+		if (den > rats[k].den_max)
+			den = rats[k].den_max;
+		else {
+			unsigned int r;
+			r = (den - rats[k].den_min) % rats[k].den_step;
+			if (r != 0)
+				den -= r;
+		}
+		diff = num - q * den;
+		if (diff < 0)
+			diff = -diff;
+		if (best_num == 0 ||
+		    diff * best_den < best_diff * den) {
+			best_diff = diff;
+			best_den = den;
+			best_num = num;
+		}
+	}
+	if (best_den == 0) {
+		i->empty = 1;
+		return -EINVAL;
+	}
+	t.min = div_down(best_num, best_den);
+	t.openmin = !!(best_num % best_den);
+	
+	result_num = best_num;
+	result_diff = best_diff;
+	result_den = best_den;
+	best_num = best_den = best_diff = 0;
+	for (k = 0; k < rats_count; ++k) {
+		unsigned int num = rats[k].num;
+		unsigned int den;
+		unsigned int q = i->max;
+		int diff;
+		if (q == 0) {
+			i->empty = 1;
+			return -EINVAL;
+		}
+		den = div_down(num, q);
+		if (den > rats[k].den_max)
+			continue;
+		if (den < rats[k].den_min)
+			den = rats[k].den_min;
+		else {
+			unsigned int r;
+			r = (den - rats[k].den_min) % rats[k].den_step;
+			if (r != 0)
+				den += rats[k].den_step - r;
+		}
+		diff = q * den - num;
+		if (diff < 0)
+			diff = -diff;
+		if (best_num == 0 ||
+		    diff * best_den < best_diff * den) {
+			best_diff = diff;
+			best_den = den;
+			best_num = num;
+		}
+	}
+	if (best_den == 0) {
+		i->empty = 1;
+		return -EINVAL;
+	}
+	t.max = div_up(best_num, best_den);
+	t.openmax = !!(best_num % best_den);
+	t.integer = 0;
+	err = snd_interval_refine(i, &t);
+	if (err < 0)
+		return err;
+
+	if (snd_interval_single(i)) {
+		if (best_diff * result_den < result_diff * best_den) {
+			result_num = best_num;
+			result_den = best_den;
+		}
+		if (nump)
+			*nump = result_num;
+		if (denp)
+			*denp = result_den;
+	}
+	return err;
+}
+EXPORT_SYMBOL(snd_interval_ratnum);
+
+/**
+ * snd_interval_ratden - refine the interval value
+ * @i: interval to refine
+ * @rats_count: number of struct ratden
+ * @rats: struct ratden array
+ * @nump: pointer to store the resultant numerator
+ * @denp: pointer to store the resultant denominator
+ *
+ * Return: Positive if the value is changed, zero if it's not changed, or a
+ * negative error code.
+ */
+static int snd_interval_ratden(struct snd_interval *i,
+			       unsigned int rats_count,
+			       const struct snd_ratden *rats,
+			       unsigned int *nump, unsigned int *denp)
+{
+	unsigned int best_num, best_diff, best_den;
+	unsigned int k;
+	struct snd_interval t;
+	int err;
+
+	best_num = best_den = best_diff = 0;
+	for (k = 0; k < rats_count; ++k) {
+		unsigned int num;
+		unsigned int den = rats[k].den;
+		unsigned int q = i->min;
+		int diff;
+		num = mul(q, den);
+		if (num > rats[k].num_max)
+			continue;
+		if (num < rats[k].num_min)
+			num = rats[k].num_max;
+		else {
+			unsigned int r;
+			r = (num - rats[k].num_min) % rats[k].num_step;
+			if (r != 0)
+				num += rats[k].num_step - r;
+		}
+		diff = num - q * den;
+		if (best_num == 0 ||
+		    diff * best_den < best_diff * den) {
+			best_diff = diff;
+			best_den = den;
+			best_num = num;
+		}
+	}
+	if (best_den == 0) {
+		i->empty = 1;
+		return -EINVAL;
+	}
+	t.min = div_down(best_num, best_den);
+	t.openmin = !!(best_num % best_den);
+	
+	best_num = best_den = best_diff = 0;
+	for (k = 0; k < rats_count; ++k) {
+		unsigned int num;
+		unsigned int den = rats[k].den;
+		unsigned int q = i->max;
+		int diff;
+		num = mul(q, den);
+		if (num < rats[k].num_min)
+			continue;
+		if (num > rats[k].num_max)
+			num = rats[k].num_max;
+		else {
+			unsigned int r;
+			r = (num - rats[k].num_min) % rats[k].num_step;
+			if (r != 0)
+				num -= r;
+		}
+		diff = q * den - num;
+		if (best_num == 0 ||
+		    diff * best_den < best_diff * den) {
+			best_diff = diff;
+			best_den = den;
+			best_num = num;
+		}
+	}
+	if (best_den == 0) {
+		i->empty = 1;
+		return -EINVAL;
+	}
+	t.max = div_up(best_num, best_den);
+	t.openmax = !!(best_num % best_den);
+	t.integer = 0;
+	err = snd_interval_refine(i, &t);
+	if (err < 0)
+		return err;
+
+	if (snd_interval_single(i)) {
+		if (nump)
+			*nump = best_num;
+		if (denp)
+			*denp = best_den;
+	}
+	return err;
+}
+
+/**
+ * snd_interval_list - refine the interval value from the list
+ * @i: the interval value to refine
+ * @count: the number of elements in the list
+ * @list: the value list
+ * @mask: the bit-mask to evaluate
+ *
+ * Refines the interval value from the list.
+ * When mask is non-zero, only the elements corresponding to bit 1 are
+ * evaluated.
+ *
+ * Return: Positive if the value is changed, zero if it's not changed, or a
+ * negative error code.
+ */
+int snd_interval_list(struct snd_interval *i, unsigned int count,
+		      const unsigned int *list, unsigned int mask)
+{
+        unsigned int k;
+	struct snd_interval list_range;
+
+	if (!count) {
+		i->empty = 1;
+		return -EINVAL;
+	}
+	snd_interval_any(&list_range);
+	list_range.min = UINT_MAX;
+	list_range.max = 0;
+        for (k = 0; k < count; k++) {
+		if (mask && !(mask & (1 << k)))
+			continue;
+		if (!snd_interval_test(i, list[k]))
+			continue;
+		list_range.min = min(list_range.min, list[k]);
+		list_range.max = max(list_range.max, list[k]);
+        }
+	return snd_interval_refine(i, &list_range);
+}
+EXPORT_SYMBOL(snd_interval_list);
+
+/**
+ * snd_interval_ranges - refine the interval value from the list of ranges
+ * @i: the interval value to refine
+ * @count: the number of elements in the list of ranges
+ * @ranges: the ranges list
+ * @mask: the bit-mask to evaluate
+ *
+ * Refines the interval value from the list of ranges.
+ * When mask is non-zero, only the elements corresponding to bit 1 are
+ * evaluated.
+ *
+ * Return: Positive if the value is changed, zero if it's not changed, or a
+ * negative error code.
+ */
+int snd_interval_ranges(struct snd_interval *i, unsigned int count,
+			const struct snd_interval *ranges, unsigned int mask)
+{
+	unsigned int k;
+	struct snd_interval range_union;
+	struct snd_interval range;
+
+	if (!count) {
+		snd_interval_none(i);
+		return -EINVAL;
+	}
+	snd_interval_any(&range_union);
+	range_union.min = UINT_MAX;
+	range_union.max = 0;
+	for (k = 0; k < count; k++) {
+		if (mask && !(mask & (1 << k)))
+			continue;
+		snd_interval_copy(&range, &ranges[k]);
+		if (snd_interval_refine(&range, i) < 0)
+			continue;
+		if (snd_interval_empty(&range))
+			continue;
+
+		if (range.min < range_union.min) {
+			range_union.min = range.min;
+			range_union.openmin = 1;
+		}
+		if (range.min == range_union.min && !range.openmin)
+			range_union.openmin = 0;
+		if (range.max > range_union.max) {
+			range_union.max = range.max;
+			range_union.openmax = 1;
+		}
+		if (range.max == range_union.max && !range.openmax)
+			range_union.openmax = 0;
+	}
+	return snd_interval_refine(i, &range_union);
+}
+EXPORT_SYMBOL(snd_interval_ranges);
+
+static int snd_interval_step(struct snd_interval *i, unsigned int step)
+{
+	unsigned int n;
+	int changed = 0;
+	n = i->min % step;
+	if (n != 0 || i->openmin) {
+		i->min += step - n;
+		i->openmin = 0;
+		changed = 1;
+	}
+	n = i->max % step;
+	if (n != 0 || i->openmax) {
+		i->max -= n;
+		i->openmax = 0;
+		changed = 1;
+	}
+	if (snd_interval_checkempty(i)) {
+		i->empty = 1;
+		return -EINVAL;
+	}
+	return changed;
+}
+
+/* Info constraints helpers */
+
+/**
+ * snd_pcm_hw_rule_add - add the hw-constraint rule
+ * @runtime: the pcm runtime instance
+ * @cond: condition bits
+ * @var: the variable to evaluate
+ * @func: the evaluation function
+ * @private: the private data pointer passed to function
+ * @dep: the dependent variables
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_rule_add(struct snd_pcm_runtime *runtime, unsigned int cond,
+			int var,
+			snd_pcm_hw_rule_func_t func, void *private,
+			int dep, ...)
+{
+	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
+	struct snd_pcm_hw_rule *c;
+	unsigned int k;
+	va_list args;
+	va_start(args, dep);
+	if (constrs->rules_num >= constrs->rules_all) {
+		struct snd_pcm_hw_rule *new;
+		unsigned int new_rules = constrs->rules_all + 16;
+		new = krealloc(constrs->rules, new_rules * sizeof(*c),
+			       GFP_KERNEL);
+		if (!new) {
+			va_end(args);
+			return -ENOMEM;
+		}
+		constrs->rules = new;
+		constrs->rules_all = new_rules;
+	}
+	c = &constrs->rules[constrs->rules_num];
+	c->cond = cond;
+	c->func = func;
+	c->var = var;
+	c->private = private;
+	k = 0;
+	while (1) {
+		if (snd_BUG_ON(k >= ARRAY_SIZE(c->deps))) {
+			va_end(args);
+			return -EINVAL;
+		}
+		c->deps[k++] = dep;
+		if (dep < 0)
+			break;
+		dep = va_arg(args, int);
+	}
+	constrs->rules_num++;
+	va_end(args);
+	return 0;
+}
+EXPORT_SYMBOL(snd_pcm_hw_rule_add);
+
+/**
+ * snd_pcm_hw_constraint_mask - apply the given bitmap mask constraint
+ * @runtime: PCM runtime instance
+ * @var: hw_params variable to apply the mask
+ * @mask: the bitmap mask
+ *
+ * Apply the constraint of the given bitmap mask to a 32-bit mask parameter.
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_constraint_mask(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,
+			       u_int32_t mask)
+{
+	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
+	struct snd_mask *maskp = constrs_mask(constrs, var);
+	*maskp->bits &= mask;
+	memset(maskp->bits + 1, 0, (SNDRV_MASK_MAX-32) / 8); /* clear rest */
+	if (*maskp->bits == 0)
+		return -EINVAL;
+	return 0;
+}
+
+/**
+ * snd_pcm_hw_constraint_mask64 - apply the given bitmap mask constraint
+ * @runtime: PCM runtime instance
+ * @var: hw_params variable to apply the mask
+ * @mask: the 64bit bitmap mask
+ *
+ * Apply the constraint of the given bitmap mask to a 64-bit mask parameter.
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_constraint_mask64(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,
+				 u_int64_t mask)
+{
+	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
+	struct snd_mask *maskp = constrs_mask(constrs, var);
+	maskp->bits[0] &= (u_int32_t)mask;
+	maskp->bits[1] &= (u_int32_t)(mask >> 32);
+	memset(maskp->bits + 2, 0, (SNDRV_MASK_MAX-64) / 8); /* clear rest */
+	if (! maskp->bits[0] && ! maskp->bits[1])
+		return -EINVAL;
+	return 0;
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_mask64);
+
+/**
+ * snd_pcm_hw_constraint_integer - apply an integer constraint to an interval
+ * @runtime: PCM runtime instance
+ * @var: hw_params variable to apply the integer constraint
+ *
+ * Apply the constraint of integer to an interval parameter.
+ *
+ * Return: Positive if the value is changed, zero if it's not changed, or a
+ * negative error code.
+ */
+int snd_pcm_hw_constraint_integer(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var)
+{
+	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
+	return snd_interval_setinteger(constrs_interval(constrs, var));
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_integer);
+
+/**
+ * snd_pcm_hw_constraint_minmax - apply a min/max range constraint to an interval
+ * @runtime: PCM runtime instance
+ * @var: hw_params variable to apply the range
+ * @min: the minimal value
+ * @max: the maximal value
+ * 
+ * Apply the min/max range constraint to an interval parameter.
+ *
+ * Return: Positive if the value is changed, zero if it's not changed, or a
+ * negative error code.
+ */
+int snd_pcm_hw_constraint_minmax(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,
+				 unsigned int min, unsigned int max)
+{
+	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
+	struct snd_interval t;
+	t.min = min;
+	t.max = max;
+	t.openmin = t.openmax = 0;
+	t.integer = 0;
+	return snd_interval_refine(constrs_interval(constrs, var), &t);
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_minmax);
+
+static int snd_pcm_hw_rule_list(struct snd_pcm_hw_params *params,
+				struct snd_pcm_hw_rule *rule)
+{
+	struct snd_pcm_hw_constraint_list *list = rule->private;
+	return snd_interval_list(hw_param_interval(params, rule->var), list->count, list->list, list->mask);
+}		
+
+
+/**
+ * snd_pcm_hw_constraint_list - apply a list of constraints to a parameter
+ * @runtime: PCM runtime instance
+ * @cond: condition bits
+ * @var: hw_params variable to apply the list constraint
+ * @l: list
+ * 
+ * Apply the list of constraints to an interval parameter.
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_constraint_list(struct snd_pcm_runtime *runtime,
+			       unsigned int cond,
+			       snd_pcm_hw_param_t var,
+			       const struct snd_pcm_hw_constraint_list *l)
+{
+	return snd_pcm_hw_rule_add(runtime, cond, var,
+				   snd_pcm_hw_rule_list, (void *)l,
+				   var, -1);
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_list);
+
+static int snd_pcm_hw_rule_ranges(struct snd_pcm_hw_params *params,
+				  struct snd_pcm_hw_rule *rule)
+{
+	struct snd_pcm_hw_constraint_ranges *r = rule->private;
+	return snd_interval_ranges(hw_param_interval(params, rule->var),
+				   r->count, r->ranges, r->mask);
+}
+
+
+/**
+ * snd_pcm_hw_constraint_ranges - apply list of range constraints to a parameter
+ * @runtime: PCM runtime instance
+ * @cond: condition bits
+ * @var: hw_params variable to apply the list of range constraints
+ * @r: ranges
+ *
+ * Apply the list of range constraints to an interval parameter.
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_constraint_ranges(struct snd_pcm_runtime *runtime,
+				 unsigned int cond,
+				 snd_pcm_hw_param_t var,
+				 const struct snd_pcm_hw_constraint_ranges *r)
+{
+	return snd_pcm_hw_rule_add(runtime, cond, var,
+				   snd_pcm_hw_rule_ranges, (void *)r,
+				   var, -1);
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_ranges);
+
+static int snd_pcm_hw_rule_ratnums(struct snd_pcm_hw_params *params,
+				   struct snd_pcm_hw_rule *rule)
+{
+	const struct snd_pcm_hw_constraint_ratnums *r = rule->private;
+	unsigned int num = 0, den = 0;
+	int err;
+	err = snd_interval_ratnum(hw_param_interval(params, rule->var),
+				  r->nrats, r->rats, &num, &den);
+	if (err >= 0 && den && rule->var == SNDRV_PCM_HW_PARAM_RATE) {
+		params->rate_num = num;
+		params->rate_den = den;
+	}
+	return err;
+}
+
+/**
+ * snd_pcm_hw_constraint_ratnums - apply ratnums constraint to a parameter
+ * @runtime: PCM runtime instance
+ * @cond: condition bits
+ * @var: hw_params variable to apply the ratnums constraint
+ * @r: struct snd_ratnums constriants
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_constraint_ratnums(struct snd_pcm_runtime *runtime, 
+				  unsigned int cond,
+				  snd_pcm_hw_param_t var,
+				  const struct snd_pcm_hw_constraint_ratnums *r)
+{
+	return snd_pcm_hw_rule_add(runtime, cond, var,
+				   snd_pcm_hw_rule_ratnums, (void *)r,
+				   var, -1);
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_ratnums);
+
+static int snd_pcm_hw_rule_ratdens(struct snd_pcm_hw_params *params,
+				   struct snd_pcm_hw_rule *rule)
+{
+	const struct snd_pcm_hw_constraint_ratdens *r = rule->private;
+	unsigned int num = 0, den = 0;
+	int err = snd_interval_ratden(hw_param_interval(params, rule->var),
+				  r->nrats, r->rats, &num, &den);
+	if (err >= 0 && den && rule->var == SNDRV_PCM_HW_PARAM_RATE) {
+		params->rate_num = num;
+		params->rate_den = den;
+	}
+	return err;
+}
+
+/**
+ * snd_pcm_hw_constraint_ratdens - apply ratdens constraint to a parameter
+ * @runtime: PCM runtime instance
+ * @cond: condition bits
+ * @var: hw_params variable to apply the ratdens constraint
+ * @r: struct snd_ratdens constriants
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_constraint_ratdens(struct snd_pcm_runtime *runtime, 
+				  unsigned int cond,
+				  snd_pcm_hw_param_t var,
+				  const struct snd_pcm_hw_constraint_ratdens *r)
+{
+	return snd_pcm_hw_rule_add(runtime, cond, var,
+				   snd_pcm_hw_rule_ratdens, (void *)r,
+				   var, -1);
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_ratdens);
+
+static int snd_pcm_hw_rule_msbits(struct snd_pcm_hw_params *params,
+				  struct snd_pcm_hw_rule *rule)
+{
+	unsigned int l = (unsigned long) rule->private;
+	int width = l & 0xffff;
+	unsigned int msbits = l >> 16;
+	const struct snd_interval *i =
+		hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_SAMPLE_BITS);
+
+	if (!snd_interval_single(i))
+		return 0;
+
+	if ((snd_interval_value(i) == width) ||
+	    (width == 0 && snd_interval_value(i) > msbits))
+		params->msbits = min_not_zero(params->msbits, msbits);
+
+	return 0;
+}
+
+/**
+ * snd_pcm_hw_constraint_msbits - add a hw constraint msbits rule
+ * @runtime: PCM runtime instance
+ * @cond: condition bits
+ * @width: sample bits width
+ * @msbits: msbits width
+ *
+ * This constraint will set the number of most significant bits (msbits) if a
+ * sample format with the specified width has been select. If width is set to 0
+ * the msbits will be set for any sample format with a width larger than the
+ * specified msbits.
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_constraint_msbits(struct snd_pcm_runtime *runtime, 
+				 unsigned int cond,
+				 unsigned int width,
+				 unsigned int msbits)
+{
+	unsigned long l = (msbits << 16) | width;
+	return snd_pcm_hw_rule_add(runtime, cond, -1,
+				    snd_pcm_hw_rule_msbits,
+				    (void*) l,
+				    SNDRV_PCM_HW_PARAM_SAMPLE_BITS, -1);
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_msbits);
+
+static int snd_pcm_hw_rule_step(struct snd_pcm_hw_params *params,
+				struct snd_pcm_hw_rule *rule)
+{
+	unsigned long step = (unsigned long) rule->private;
+	return snd_interval_step(hw_param_interval(params, rule->var), step);
+}
+
+/**
+ * snd_pcm_hw_constraint_step - add a hw constraint step rule
+ * @runtime: PCM runtime instance
+ * @cond: condition bits
+ * @var: hw_params variable to apply the step constraint
+ * @step: step size
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_constraint_step(struct snd_pcm_runtime *runtime,
+			       unsigned int cond,
+			       snd_pcm_hw_param_t var,
+			       unsigned long step)
+{
+	return snd_pcm_hw_rule_add(runtime, cond, var, 
+				   snd_pcm_hw_rule_step, (void *) step,
+				   var, -1);
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_step);
+
+static int snd_pcm_hw_rule_pow2(struct snd_pcm_hw_params *params, struct snd_pcm_hw_rule *rule)
+{
+	static unsigned int pow2_sizes[] = {
+		1<<0, 1<<1, 1<<2, 1<<3, 1<<4, 1<<5, 1<<6, 1<<7,
+		1<<8, 1<<9, 1<<10, 1<<11, 1<<12, 1<<13, 1<<14, 1<<15,
+		1<<16, 1<<17, 1<<18, 1<<19, 1<<20, 1<<21, 1<<22, 1<<23,
+		1<<24, 1<<25, 1<<26, 1<<27, 1<<28, 1<<29, 1<<30
+	};
+	return snd_interval_list(hw_param_interval(params, rule->var),
+				 ARRAY_SIZE(pow2_sizes), pow2_sizes, 0);
+}		
+
+/**
+ * snd_pcm_hw_constraint_pow2 - add a hw constraint power-of-2 rule
+ * @runtime: PCM runtime instance
+ * @cond: condition bits
+ * @var: hw_params variable to apply the power-of-2 constraint
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_constraint_pow2(struct snd_pcm_runtime *runtime,
+			       unsigned int cond,
+			       snd_pcm_hw_param_t var)
+{
+	return snd_pcm_hw_rule_add(runtime, cond, var, 
+				   snd_pcm_hw_rule_pow2, NULL,
+				   var, -1);
+}
+EXPORT_SYMBOL(snd_pcm_hw_constraint_pow2);
+
+static int snd_pcm_hw_rule_noresample_func(struct snd_pcm_hw_params *params,
+					   struct snd_pcm_hw_rule *rule)
+{
+	unsigned int base_rate = (unsigned int)(uintptr_t)rule->private;
+	struct snd_interval *rate;
+
+	rate = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
+	return snd_interval_list(rate, 1, &base_rate, 0);
+}
+
+/**
+ * snd_pcm_hw_rule_noresample - add a rule to allow disabling hw resampling
+ * @runtime: PCM runtime instance
+ * @base_rate: the rate at which the hardware does not resample
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_hw_rule_noresample(struct snd_pcm_runtime *runtime,
+			       unsigned int base_rate)
+{
+	return snd_pcm_hw_rule_add(runtime, SNDRV_PCM_HW_PARAMS_NORESAMPLE,
+				   SNDRV_PCM_HW_PARAM_RATE,
+				   snd_pcm_hw_rule_noresample_func,
+				   (void *)(uintptr_t)base_rate,
+				   SNDRV_PCM_HW_PARAM_RATE, -1);
+}
+EXPORT_SYMBOL(snd_pcm_hw_rule_noresample);
+
+static void _snd_pcm_hw_param_any(struct snd_pcm_hw_params *params,
+				  snd_pcm_hw_param_t var)
+{
+	if (hw_is_mask(var)) {
+		snd_mask_any(hw_param_mask(params, var));
+		params->cmask |= 1 << var;
+		params->rmask |= 1 << var;
+		return;
+	}
+	if (hw_is_interval(var)) {
+		snd_interval_any(hw_param_interval(params, var));
+		params->cmask |= 1 << var;
+		params->rmask |= 1 << var;
+		return;
+	}
+	snd_BUG();
+}
+
+void _snd_pcm_hw_params_any(struct snd_pcm_hw_params *params)
+{
+	unsigned int k;
+	memset(params, 0, sizeof(*params));
+	for (k = SNDRV_PCM_HW_PARAM_FIRST_MASK; k <= SNDRV_PCM_HW_PARAM_LAST_MASK; k++)
+		_snd_pcm_hw_param_any(params, k);
+	for (k = SNDRV_PCM_HW_PARAM_FIRST_INTERVAL; k <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; k++)
+		_snd_pcm_hw_param_any(params, k);
+	params->info = ~0U;
+}
+EXPORT_SYMBOL(_snd_pcm_hw_params_any);
+
+/**
+ * snd_pcm_hw_param_value - return @params field @var value
+ * @params: the hw_params instance
+ * @var: parameter to retrieve
+ * @dir: pointer to the direction (-1,0,1) or %NULL
+ *
+ * Return: The value for field @var if it's fixed in configuration space
+ * defined by @params. -%EINVAL otherwise.
+ */
+int snd_pcm_hw_param_value(const struct snd_pcm_hw_params *params,
+			   snd_pcm_hw_param_t var, int *dir)
+{
+	if (hw_is_mask(var)) {
+		const struct snd_mask *mask = hw_param_mask_c(params, var);
+		if (!snd_mask_single(mask))
+			return -EINVAL;
+		if (dir)
+			*dir = 0;
+		return snd_mask_value(mask);
+	}
+	if (hw_is_interval(var)) {
+		const struct snd_interval *i = hw_param_interval_c(params, var);
+		if (!snd_interval_single(i))
+			return -EINVAL;
+		if (dir)
+			*dir = i->openmin;
+		return snd_interval_value(i);
+	}
+	return -EINVAL;
+}
+EXPORT_SYMBOL(snd_pcm_hw_param_value);
+
+void _snd_pcm_hw_param_setempty(struct snd_pcm_hw_params *params,
+				snd_pcm_hw_param_t var)
+{
+	if (hw_is_mask(var)) {
+		snd_mask_none(hw_param_mask(params, var));
+		params->cmask |= 1 << var;
+		params->rmask |= 1 << var;
+	} else if (hw_is_interval(var)) {
+		snd_interval_none(hw_param_interval(params, var));
+		params->cmask |= 1 << var;
+		params->rmask |= 1 << var;
+	} else {
+		snd_BUG();
+	}
+}
+EXPORT_SYMBOL(_snd_pcm_hw_param_setempty);
+
+static int _snd_pcm_hw_param_first(struct snd_pcm_hw_params *params,
+				   snd_pcm_hw_param_t var)
+{
+	int changed;
+	if (hw_is_mask(var))
+		changed = snd_mask_refine_first(hw_param_mask(params, var));
+	else if (hw_is_interval(var))
+		changed = snd_interval_refine_first(hw_param_interval(params, var));
+	else
+		return -EINVAL;
+	if (changed > 0) {
+		params->cmask |= 1 << var;
+		params->rmask |= 1 << var;
+	}
+	return changed;
+}
+
+
+/**
+ * snd_pcm_hw_param_first - refine config space and return minimum value
+ * @pcm: PCM instance
+ * @params: the hw_params instance
+ * @var: parameter to retrieve
+ * @dir: pointer to the direction (-1,0,1) or %NULL
+ *
+ * Inside configuration space defined by @params remove from @var all
+ * values > minimum. Reduce configuration space accordingly.
+ *
+ * Return: The minimum, or a negative error code on failure.
+ */
+int snd_pcm_hw_param_first(struct snd_pcm_substream *pcm, 
+			   struct snd_pcm_hw_params *params, 
+			   snd_pcm_hw_param_t var, int *dir)
+{
+	int changed = _snd_pcm_hw_param_first(params, var);
+	if (changed < 0)
+		return changed;
+	if (params->rmask) {
+		int err = snd_pcm_hw_refine(pcm, params);
+		if (err < 0)
+			return err;
+	}
+	return snd_pcm_hw_param_value(params, var, dir);
+}
+EXPORT_SYMBOL(snd_pcm_hw_param_first);
+
+static int _snd_pcm_hw_param_last(struct snd_pcm_hw_params *params,
+				  snd_pcm_hw_param_t var)
+{
+	int changed;
+	if (hw_is_mask(var))
+		changed = snd_mask_refine_last(hw_param_mask(params, var));
+	else if (hw_is_interval(var))
+		changed = snd_interval_refine_last(hw_param_interval(params, var));
+	else
+		return -EINVAL;
+	if (changed > 0) {
+		params->cmask |= 1 << var;
+		params->rmask |= 1 << var;
+	}
+	return changed;
+}
+
+
+/**
+ * snd_pcm_hw_param_last - refine config space and return maximum value
+ * @pcm: PCM instance
+ * @params: the hw_params instance
+ * @var: parameter to retrieve
+ * @dir: pointer to the direction (-1,0,1) or %NULL
+ *
+ * Inside configuration space defined by @params remove from @var all
+ * values < maximum. Reduce configuration space accordingly.
+ *
+ * Return: The maximum, or a negative error code on failure.
+ */
+int snd_pcm_hw_param_last(struct snd_pcm_substream *pcm, 
+			  struct snd_pcm_hw_params *params,
+			  snd_pcm_hw_param_t var, int *dir)
+{
+	int changed = _snd_pcm_hw_param_last(params, var);
+	if (changed < 0)
+		return changed;
+	if (params->rmask) {
+		int err = snd_pcm_hw_refine(pcm, params);
+		if (err < 0)
+			return err;
+	}
+	return snd_pcm_hw_param_value(params, var, dir);
+}
+EXPORT_SYMBOL(snd_pcm_hw_param_last);
+
+static int snd_pcm_lib_ioctl_reset(struct snd_pcm_substream *substream,
+				   void *arg)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	unsigned long flags;
+	snd_pcm_stream_lock_irqsave(substream, flags);
+	if (snd_pcm_running(substream) &&
+	    snd_pcm_update_hw_ptr(substream) >= 0)
+		runtime->status->hw_ptr %= runtime->buffer_size;
+	else {
+		runtime->status->hw_ptr = 0;
+		runtime->hw_ptr_wrap = 0;
+	}
+	snd_pcm_stream_unlock_irqrestore(substream, flags);
+	return 0;
+}
+
+static int snd_pcm_lib_ioctl_channel_info(struct snd_pcm_substream *substream,
+					  void *arg)
+{
+	struct snd_pcm_channel_info *info = arg;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	int width;
+	if (!(runtime->info & SNDRV_PCM_INFO_MMAP)) {
+		info->offset = -1;
+		return 0;
+	}
+	width = snd_pcm_format_physical_width(runtime->format);
+	if (width < 0)
+		return width;
+	info->offset = 0;
+	switch (runtime->access) {
+	case SNDRV_PCM_ACCESS_MMAP_INTERLEAVED:
+	case SNDRV_PCM_ACCESS_RW_INTERLEAVED:
+		info->first = info->channel * width;
+		info->step = runtime->channels * width;
+		break;
+	case SNDRV_PCM_ACCESS_MMAP_NONINTERLEAVED:
+	case SNDRV_PCM_ACCESS_RW_NONINTERLEAVED:
+	{
+		size_t size = runtime->dma_bytes / runtime->channels;
+		info->first = info->channel * size * 8;
+		info->step = width;
+		break;
+	}
+	default:
+		snd_BUG();
+		break;
+	}
+	return 0;
+}
+
+static int snd_pcm_lib_ioctl_fifo_size(struct snd_pcm_substream *substream,
+				       void *arg)
+{
+	struct snd_pcm_hw_params *params = arg;
+	snd_pcm_format_t format;
+	int channels;
+	ssize_t frame_size;
+
+	params->fifo_size = substream->runtime->hw.fifo_size;
+	if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_FIFO_IN_FRAMES)) {
+		format = params_format(params);
+		channels = params_channels(params);
+		frame_size = snd_pcm_format_size(format, channels);
+		if (frame_size > 0)
+			params->fifo_size /= frame_size;
+	}
+	return 0;
+}
+
+/**
+ * snd_pcm_lib_ioctl - a generic PCM ioctl callback
+ * @substream: the pcm substream instance
+ * @cmd: ioctl command
+ * @arg: ioctl argument
+ *
+ * Processes the generic ioctl commands for PCM.
+ * Can be passed as the ioctl callback for PCM ops.
+ *
+ * Return: Zero if successful, or a negative error code on failure.
+ */
+int snd_pcm_lib_ioctl(struct snd_pcm_substream *substream,
+		      unsigned int cmd, void *arg)
+{
+	switch (cmd) {
+	case SNDRV_PCM_IOCTL1_RESET:
+		return snd_pcm_lib_ioctl_reset(substream, arg);
+	case SNDRV_PCM_IOCTL1_CHANNEL_INFO:
+		return snd_pcm_lib_ioctl_channel_info(substream, arg);
+	case SNDRV_PCM_IOCTL1_FIFO_SIZE:
+		return snd_pcm_lib_ioctl_fifo_size(substream, arg);
+	}
+	return -ENXIO;
+}
+EXPORT_SYMBOL(snd_pcm_lib_ioctl);
+
+/**
+ * snd_pcm_period_elapsed - update the pcm status for the next period
+ * @substream: the pcm substream instance
+ *
+ * This function is called from the interrupt handler when the
+ * PCM has processed the period size.  It will update the current
+ * pointer, wake up sleepers, etc.
+ *
+ * Even if more than one periods have elapsed since the last call, you
+ * have to call this only once.
+ */
+void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime;
+	unsigned long flags;
+
+	if (snd_BUG_ON(!substream))
+		return;
+
+	snd_pcm_stream_lock_irqsave(substream, flags);
+	if (PCM_RUNTIME_CHECK(substream))
+		goto _unlock;
+	runtime = substream->runtime;
+
+	if (!snd_pcm_running(substream) ||
+	    snd_pcm_update_hw_ptr0(substream, 1) < 0)
+		goto _end;
+
+#ifdef CONFIG_SND_PCM_TIMER
+	if (substream->timer_running)
+		snd_timer_interrupt(substream->timer, 1);
+#endif
+ _end:
+	kill_fasync(&runtime->fasync, SIGIO, POLL_IN);
+ _unlock:
+	snd_pcm_stream_unlock_irqrestore(substream, flags);
+}
+EXPORT_SYMBOL(snd_pcm_period_elapsed);
+
+/*
+ * Wait until avail_min data becomes available
+ * Returns a negative error code if any error occurs during operation.
+ * The available space is stored on availp.  When err = 0 and avail = 0
+ * on the capture stream, it indicates the stream is in DRAINING state.
+ */
+static int wait_for_avail(struct snd_pcm_substream *substream,
+			      snd_pcm_uframes_t *availp)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	int is_playback = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
+	wait_queue_entry_t wait;
+	int err = 0;
+	snd_pcm_uframes_t avail = 0;
+	long wait_time, tout;
+
+	init_waitqueue_entry(&wait, current);
+	set_current_state(TASK_INTERRUPTIBLE);
+	add_wait_queue(&runtime->tsleep, &wait);
+
+	if (runtime->no_period_wakeup)
+		wait_time = MAX_SCHEDULE_TIMEOUT;
+	else {
+		/* use wait time from substream if available */
+		if (substream->wait_time) {
+			wait_time = substream->wait_time;
+		} else {
+			wait_time = 10;
+
+			if (runtime->rate) {
+				long t = runtime->period_size * 2 /
+					 runtime->rate;
+				wait_time = max(t, wait_time);
+			}
+			wait_time = msecs_to_jiffies(wait_time * 1000);
+		}
+	}
+
+	for (;;) {
+		if (signal_pending(current)) {
+			err = -ERESTARTSYS;
+			break;
+		}
+
+		/*
+		 * We need to check if space became available already
+		 * (and thus the wakeup happened already) first to close
+		 * the race of space already having become available.
+		 * This check must happen after been added to the waitqueue
+		 * and having current state be INTERRUPTIBLE.
+		 */
+		avail = snd_pcm_avail(substream);
+		if (avail >= runtime->twake)
+			break;
+		snd_pcm_stream_unlock_irq(substream);
+
+		tout = schedule_timeout(wait_time);
+
+		snd_pcm_stream_lock_irq(substream);
+		set_current_state(TASK_INTERRUPTIBLE);
+		switch (runtime->status->state) {
+		case SNDRV_PCM_STATE_SUSPENDED:
+			err = -ESTRPIPE;
+			goto _endloop;
+		case SNDRV_PCM_STATE_XRUN:
+			err = -EPIPE;
+			goto _endloop;
+		case SNDRV_PCM_STATE_DRAINING:
+			if (is_playback)
+				err = -EPIPE;
+			else 
+				avail = 0; /* indicate draining */
+			goto _endloop;
+		case SNDRV_PCM_STATE_OPEN:
+		case SNDRV_PCM_STATE_SETUP:
+		case SNDRV_PCM_STATE_DISCONNECTED:
+			err = -EBADFD;
+			goto _endloop;
+		case SNDRV_PCM_STATE_PAUSED:
+			continue;
+		}
+		if (!tout) {
+			pcm_dbg(substream->pcm,
+				"%s write error (DMA or IRQ trouble?)\n",
+				is_playback ? "playback" : "capture");
+			err = -EIO;
+			break;
+		}
+	}
+ _endloop:
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&runtime->tsleep, &wait);
+	*availp = avail;
+	return err;
+}
+	
+typedef int (*pcm_transfer_f)(struct snd_pcm_substream *substream,
+			      int channel, unsigned long hwoff,
+			      void *buf, unsigned long bytes);
+
+typedef int (*pcm_copy_f)(struct snd_pcm_substream *, snd_pcm_uframes_t, void *,
+			  snd_pcm_uframes_t, snd_pcm_uframes_t, pcm_transfer_f);
+
+/* calculate the target DMA-buffer position to be written/read */
+static void *get_dma_ptr(struct snd_pcm_runtime *runtime,
+			   int channel, unsigned long hwoff)
+{
+	return runtime->dma_area + hwoff +
+		channel * (runtime->dma_bytes / runtime->channels);
+}
+
+/* default copy_user ops for write; used for both interleaved and non- modes */
+static int default_write_copy(struct snd_pcm_substream *substream,
+			      int channel, unsigned long hwoff,
+			      void *buf, unsigned long bytes)
+{
+	if (copy_from_user(get_dma_ptr(substream->runtime, channel, hwoff),
+			   (void __user *)buf, bytes))
+		return -EFAULT;
+	return 0;
+}
+
+/* default copy_kernel ops for write */
+static int default_write_copy_kernel(struct snd_pcm_substream *substream,
+				     int channel, unsigned long hwoff,
+				     void *buf, unsigned long bytes)
+{
+	memcpy(get_dma_ptr(substream->runtime, channel, hwoff), buf, bytes);
+	return 0;
+}
+
+/* fill silence instead of copy data; called as a transfer helper
+ * from __snd_pcm_lib_write() or directly from noninterleaved_copy() when
+ * a NULL buffer is passed
+ */
+static int fill_silence(struct snd_pcm_substream *substream, int channel,
+			unsigned long hwoff, void *buf, unsigned long bytes)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+
+	if (substream->stream != SNDRV_PCM_STREAM_PLAYBACK)
+		return 0;
+	if (substream->ops->fill_silence)
+		return substream->ops->fill_silence(substream, channel,
+						    hwoff, bytes);
+
+	snd_pcm_format_set_silence(runtime->format,
+				   get_dma_ptr(runtime, channel, hwoff),
+				   bytes_to_samples(runtime, bytes));
+	return 0;
+}
+
+/* default copy_user ops for read; used for both interleaved and non- modes */
+static int default_read_copy(struct snd_pcm_substream *substream,
+			     int channel, unsigned long hwoff,
+			     void *buf, unsigned long bytes)
+{
+	if (copy_to_user((void __user *)buf,
+			 get_dma_ptr(substream->runtime, channel, hwoff),
+			 bytes))
+		return -EFAULT;
+	return 0;
+}
+
+/* default copy_kernel ops for read */
+static int default_read_copy_kernel(struct snd_pcm_substream *substream,
+				    int channel, unsigned long hwoff,
+				    void *buf, unsigned long bytes)
+{
+	memcpy(buf, get_dma_ptr(substream->runtime, channel, hwoff), bytes);
+	return 0;
+}
+
+/* call transfer function with the converted pointers and sizes;
+ * for interleaved mode, it's one shot for all samples
+ */
+static int interleaved_copy(struct snd_pcm_substream *substream,
+			    snd_pcm_uframes_t hwoff, void *data,
+			    snd_pcm_uframes_t off,
+			    snd_pcm_uframes_t frames,
+			    pcm_transfer_f transfer)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+
+	/* convert to bytes */
+	hwoff = frames_to_bytes(runtime, hwoff);
+	off = frames_to_bytes(runtime, off);
+	frames = frames_to_bytes(runtime, frames);
+	return transfer(substream, 0, hwoff, data + off, frames);
+}
+
+/* call transfer function with the converted pointers and sizes for each
+ * non-interleaved channel; when buffer is NULL, silencing instead of copying
+ */
+static int noninterleaved_copy(struct snd_pcm_substream *substream,
+			       snd_pcm_uframes_t hwoff, void *data,
+			       snd_pcm_uframes_t off,
+			       snd_pcm_uframes_t frames,
+			       pcm_transfer_f transfer)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	int channels = runtime->channels;
+	void **bufs = data;
+	int c, err;
+
+	/* convert to bytes; note that it's not frames_to_bytes() here.
+	 * in non-interleaved mode, we copy for each channel, thus
+	 * each copy is n_samples bytes x channels = whole frames.
+	 */
+	off = samples_to_bytes(runtime, off);
+	frames = samples_to_bytes(runtime, frames);
+	hwoff = samples_to_bytes(runtime, hwoff);
+	for (c = 0; c < channels; ++c, ++bufs) {
+		if (!data || !*bufs)
+			err = fill_silence(substream, c, hwoff, NULL, frames);
+		else
+			err = transfer(substream, c, hwoff, *bufs + off,
+				       frames);
+		if (err < 0)
+			return err;
+	}
+	return 0;
+}
+
+/* fill silence on the given buffer position;
+ * called from snd_pcm_playback_silence()
+ */
+static int fill_silence_frames(struct snd_pcm_substream *substream,
+			       snd_pcm_uframes_t off, snd_pcm_uframes_t frames)
+{
+	if (substream->runtime->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED ||
+	    substream->runtime->access == SNDRV_PCM_ACCESS_MMAP_INTERLEAVED)
+		return interleaved_copy(substream, off, NULL, 0, frames,
+					fill_silence);
+	else
+		return noninterleaved_copy(substream, off, NULL, 0, frames,
+					   fill_silence);
+}
+
+/* sanity-check for read/write methods */
+static int pcm_sanity_check(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime;
+	if (PCM_RUNTIME_CHECK(substream))
+		return -ENXIO;
+	runtime = substream->runtime;
+	if (snd_BUG_ON(!substream->ops->copy_user && !runtime->dma_area))
+		return -EINVAL;
+	if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
+		return -EBADFD;
+	return 0;
+}
+
+static int pcm_accessible_state(struct snd_pcm_runtime *runtime)
+{
+	switch (runtime->status->state) {
+	case SNDRV_PCM_STATE_PREPARED:
+	case SNDRV_PCM_STATE_RUNNING:
+	case SNDRV_PCM_STATE_PAUSED:
+		return 0;
+	case SNDRV_PCM_STATE_XRUN:
+		return -EPIPE;
+	case SNDRV_PCM_STATE_SUSPENDED:
+		return -ESTRPIPE;
+	default:
+		return -EBADFD;
+	}
+}
+
+/* update to the given appl_ptr and call ack callback if needed;
+ * when an error is returned, take back to the original value
+ */
+int pcm_lib_apply_appl_ptr(struct snd_pcm_substream *substream,
+			   snd_pcm_uframes_t appl_ptr)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_pcm_uframes_t old_appl_ptr = runtime->control->appl_ptr;
+	int ret;
+
+	if (old_appl_ptr == appl_ptr)
+		return 0;
+
+	runtime->control->appl_ptr = appl_ptr;
+	if (substream->ops->ack) {
+		ret = substream->ops->ack(substream);
+		if (ret < 0) {
+			runtime->control->appl_ptr = old_appl_ptr;
+			return ret;
+		}
+	}
+
+	trace_applptr(substream, old_appl_ptr, appl_ptr);
+
+	return 0;
+}
+
+/* the common loop for read/write data */
+snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
+				     void *data, bool interleaved,
+				     snd_pcm_uframes_t size, bool in_kernel)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_pcm_uframes_t xfer = 0;
+	snd_pcm_uframes_t offset = 0;
+	snd_pcm_uframes_t avail;
+	pcm_copy_f writer;
+	pcm_transfer_f transfer;
+	bool nonblock;
+	bool is_playback;
+	int err;
+
+	err = pcm_sanity_check(substream);
+	if (err < 0)
+		return err;
+
+	is_playback = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
+	if (interleaved) {
+		if (runtime->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED &&
+		    runtime->channels > 1)
+			return -EINVAL;
+		writer = interleaved_copy;
+	} else {
+		if (runtime->access != SNDRV_PCM_ACCESS_RW_NONINTERLEAVED)
+			return -EINVAL;
+		writer = noninterleaved_copy;
+	}
+
+	if (!data) {
+		if (is_playback)
+			transfer = fill_silence;
+		else
+			return -EINVAL;
+	} else if (in_kernel) {
+		if (substream->ops->copy_kernel)
+			transfer = substream->ops->copy_kernel;
+		else
+			transfer = is_playback ?
+				default_write_copy_kernel : default_read_copy_kernel;
+	} else {
+		if (substream->ops->copy_user)
+			transfer = (pcm_transfer_f)substream->ops->copy_user;
+		else
+			transfer = is_playback ?
+				default_write_copy : default_read_copy;
+	}
+
+	if (size == 0)
+		return 0;
+
+	nonblock = !!(substream->f_flags & O_NONBLOCK);
+
+	snd_pcm_stream_lock_irq(substream);
+	err = pcm_accessible_state(runtime);
+	if (err < 0)
+		goto _end_unlock;
+
+	if (!is_playback &&
+	    runtime->status->state == SNDRV_PCM_STATE_PREPARED &&
+	    size >= runtime->start_threshold) {
+		err = snd_pcm_start(substream);
+		if (err < 0)
+			goto _end_unlock;
+	}
+
+	runtime->twake = runtime->control->avail_min ? : 1;
+	if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)
+		snd_pcm_update_hw_ptr(substream);
+	avail = snd_pcm_avail(substream);
+	while (size > 0) {
+		snd_pcm_uframes_t frames, appl_ptr, appl_ofs;
+		snd_pcm_uframes_t cont;
+		if (!avail) {
+			if (!is_playback &&
+			    runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
+				snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
+				goto _end_unlock;
+			}
+			if (nonblock) {
+				err = -EAGAIN;
+				goto _end_unlock;
+			}
+			runtime->twake = min_t(snd_pcm_uframes_t, size,
+					runtime->control->avail_min ? : 1);
+			err = wait_for_avail(substream, &avail);
+			if (err < 0)
+				goto _end_unlock;
+			if (!avail)
+				continue; /* draining */
+		}
+		frames = size > avail ? avail : size;
+		appl_ptr = READ_ONCE(runtime->control->appl_ptr);
+		appl_ofs = appl_ptr % runtime->buffer_size;
+		cont = runtime->buffer_size - appl_ofs;
+		if (frames > cont)
+			frames = cont;
+		if (snd_BUG_ON(!frames)) {
+			runtime->twake = 0;
+			snd_pcm_stream_unlock_irq(substream);
+			return -EINVAL;
+		}
+		if (!atomic_inc_unless_negative(&runtime->buffer_accessing)) {
+			err = -EBUSY;
+			goto _end_unlock;
+		}
+		snd_pcm_stream_unlock_irq(substream);
+		err = writer(substream, appl_ofs, data, offset, frames,
+			     transfer);
+		snd_pcm_stream_lock_irq(substream);
+		atomic_dec(&runtime->buffer_accessing);
+		if (err < 0)
+			goto _end_unlock;
+		err = pcm_accessible_state(runtime);
+		if (err < 0)
+			goto _end_unlock;
+		appl_ptr += frames;
+		if (appl_ptr >= runtime->boundary)
+			appl_ptr -= runtime->boundary;
+		err = pcm_lib_apply_appl_ptr(substream, appl_ptr);
+		if (err < 0)
+			goto _end_unlock;
+
+		offset += frames;
+		size -= frames;
+		xfer += frames;
+		avail -= frames;
+		if (is_playback &&
+		    runtime->status->state == SNDRV_PCM_STATE_PREPARED &&
+		    snd_pcm_playback_hw_avail(runtime) >= (snd_pcm_sframes_t)runtime->start_threshold) {
+			err = snd_pcm_start(substream);
+			if (err < 0)
+				goto _end_unlock;
+		}
+	}
+ _end_unlock:
+	runtime->twake = 0;
+	if (xfer > 0 && err >= 0)
+		snd_pcm_update_state(substream, runtime);
+	snd_pcm_stream_unlock_irq(substream);
+	return xfer > 0 ? (snd_pcm_sframes_t)xfer : err;
+}
+EXPORT_SYMBOL(__snd_pcm_lib_xfer);
+
+/*
+ * standard channel mapping helpers
+ */
+
+/* default channel maps for multi-channel playbacks, up to 8 channels */
+const struct snd_pcm_chmap_elem snd_pcm_std_chmaps[] = {
+	{ .channels = 1,
+	  .map = { SNDRV_CHMAP_MONO } },
+	{ .channels = 2,
+	  .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR } },
+	{ .channels = 4,
+	  .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+		   SNDRV_CHMAP_RL, SNDRV_CHMAP_RR } },
+	{ .channels = 6,
+	  .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+		   SNDRV_CHMAP_RL, SNDRV_CHMAP_RR,
+		   SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE } },
+	{ .channels = 8,
+	  .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+		   SNDRV_CHMAP_RL, SNDRV_CHMAP_RR,
+		   SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE,
+		   SNDRV_CHMAP_SL, SNDRV_CHMAP_SR } },
+	{ }
+};
+EXPORT_SYMBOL_GPL(snd_pcm_std_chmaps);
+
+/* alternative channel maps with CLFE <-> surround swapped for 6/8 channels */
+const struct snd_pcm_chmap_elem snd_pcm_alt_chmaps[] = {
+	{ .channels = 1,
+	  .map = { SNDRV_CHMAP_MONO } },
+	{ .channels = 2,
+	  .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR } },
+	{ .channels = 4,
+	  .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+		   SNDRV_CHMAP_RL, SNDRV_CHMAP_RR } },
+	{ .channels = 6,
+	  .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+		   SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE,
+		   SNDRV_CHMAP_RL, SNDRV_CHMAP_RR } },
+	{ .channels = 8,
+	  .map = { SNDRV_CHMAP_FL, SNDRV_CHMAP_FR,
+		   SNDRV_CHMAP_FC, SNDRV_CHMAP_LFE,
+		   SNDRV_CHMAP_RL, SNDRV_CHMAP_RR,
+		   SNDRV_CHMAP_SL, SNDRV_CHMAP_SR } },
+	{ }
+};
+EXPORT_SYMBOL_GPL(snd_pcm_alt_chmaps);
+
+static bool valid_chmap_channels(const struct snd_pcm_chmap *info, int ch)
+{
+	if (ch > info->max_channels)
+		return false;
+	return !info->channel_mask || (info->channel_mask & (1U << ch));
+}
+
+static int pcm_chmap_ctl_info(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
+
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 0;
+	uinfo->count = info->max_channels;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = SNDRV_CHMAP_LAST;
+	return 0;
+}
+
+/* get callback for channel map ctl element
+ * stores the channel position firstly matching with the current channels
+ */
+static int pcm_chmap_ctl_get(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
+	unsigned int idx = snd_ctl_get_ioffidx(kcontrol, &ucontrol->id);
+	struct snd_pcm_substream *substream;
+	const struct snd_pcm_chmap_elem *map;
+
+	if (!info->chmap)
+		return -EINVAL;
+	substream = snd_pcm_chmap_substream(info, idx);
+	if (!substream)
+		return -ENODEV;
+	memset(ucontrol->value.integer.value, 0,
+	       sizeof(ucontrol->value.integer.value));
+	if (!substream->runtime)
+		return 0; /* no channels set */
+	for (map = info->chmap; map->channels; map++) {
+		int i;
+		if (map->channels == substream->runtime->channels &&
+		    valid_chmap_channels(info, map->channels)) {
+			for (i = 0; i < map->channels; i++)
+				ucontrol->value.integer.value[i] = map->map[i];
+			return 0;
+		}
+	}
+	return -EINVAL;
+}
+
+/* tlv callback for channel map ctl element
+ * expands the pre-defined channel maps in a form of TLV
+ */
+static int pcm_chmap_ctl_tlv(struct snd_kcontrol *kcontrol, int op_flag,
+			     unsigned int size, unsigned int __user *tlv)
+{
+	struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
+	const struct snd_pcm_chmap_elem *map;
+	unsigned int __user *dst;
+	int c, count = 0;
+
+	if (!info->chmap)
+		return -EINVAL;
+	if (size < 8)
+		return -ENOMEM;
+	if (put_user(SNDRV_CTL_TLVT_CONTAINER, tlv))
+		return -EFAULT;
+	size -= 8;
+	dst = tlv + 2;
+	for (map = info->chmap; map->channels; map++) {
+		int chs_bytes = map->channels * 4;
+		if (!valid_chmap_channels(info, map->channels))
+			continue;
+		if (size < 8)
+			return -ENOMEM;
+		if (put_user(SNDRV_CTL_TLVT_CHMAP_FIXED, dst) ||
+		    put_user(chs_bytes, dst + 1))
+			return -EFAULT;
+		dst += 2;
+		size -= 8;
+		count += 8;
+		if (size < chs_bytes)
+			return -ENOMEM;
+		size -= chs_bytes;
+		count += chs_bytes;
+		for (c = 0; c < map->channels; c++) {
+			if (put_user(map->map[c], dst))
+				return -EFAULT;
+			dst++;
+		}
+	}
+	if (put_user(count, tlv + 1))
+		return -EFAULT;
+	return 0;
+}
+
+static void pcm_chmap_ctl_private_free(struct snd_kcontrol *kcontrol)
+{
+	struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
+	info->pcm->streams[info->stream].chmap_kctl = NULL;
+	kfree(info);
+}
+
+/**
+ * snd_pcm_add_chmap_ctls - create channel-mapping control elements
+ * @pcm: the assigned PCM instance
+ * @stream: stream direction
+ * @chmap: channel map elements (for query)
+ * @max_channels: the max number of channels for the stream
+ * @private_value: the value passed to each kcontrol's private_value field
+ * @info_ret: store struct snd_pcm_chmap instance if non-NULL
+ *
+ * Create channel-mapping control elements assigned to the given PCM stream(s).
+ * Return: Zero if successful, or a negative error value.
+ */
+int snd_pcm_add_chmap_ctls(struct snd_pcm *pcm, int stream,
+			   const struct snd_pcm_chmap_elem *chmap,
+			   int max_channels,
+			   unsigned long private_value,
+			   struct snd_pcm_chmap **info_ret)
+{
+	struct snd_pcm_chmap *info;
+	struct snd_kcontrol_new knew = {
+		.iface = SNDRV_CTL_ELEM_IFACE_PCM,
+		.access = SNDRV_CTL_ELEM_ACCESS_READ |
+			SNDRV_CTL_ELEM_ACCESS_TLV_READ |
+			SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK,
+		.info = pcm_chmap_ctl_info,
+		.get = pcm_chmap_ctl_get,
+		.tlv.c = pcm_chmap_ctl_tlv,
+	};
+	int err;
+
+	if (WARN_ON(pcm->streams[stream].chmap_kctl))
+		return -EBUSY;
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+	info->pcm = pcm;
+	info->stream = stream;
+	info->chmap = chmap;
+	info->max_channels = max_channels;
+	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
+		knew.name = "Playback Channel Map";
+	else
+		knew.name = "Capture Channel Map";
+	knew.device = pcm->device;
+	knew.count = pcm->streams[stream].substream_count;
+	knew.private_value = private_value;
+	info->kctl = snd_ctl_new1(&knew, info);
+	if (!info->kctl) {
+		kfree(info);
+		return -ENOMEM;
+	}
+	info->kctl->private_free = pcm_chmap_ctl_private_free;
+	err = snd_ctl_add(pcm->card, info->kctl);
+	if (err < 0)
+		return err;
+	pcm->streams[stream].chmap_kctl = info->kctl;
+	if (info_ret)
+		*info_ret = info;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_pcm_add_chmap_ctls);