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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *  Digital Audio (PCM) abstract layer
  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
  *                   Abramo Bagnara <abramo@alsa-project.org>
  */
 
 #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;
     }
     snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_DEVICE);
 }
 
 #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) {
         struct timespec64 tstamp;
 
         snd_pcm_gettime(runtime, &tstamp);
         runtime->status->tstamp.tv_sec = tstamp.tv_sec;
         runtime->status->tstamp.tv_nsec = tstamp.tv_nsec;
     }
     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 timespec64 *curr_tstamp,
                 struct timespec64 *audio_tstamp)
 {
     struct snd_pcm_runtime *runtime = substream->runtime;
     u64 audio_frames, audio_nsecs;
     struct timespec64 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_timespec64(audio_nsecs);
     }
 
     if (runtime->status->audio_tstamp.tv_sec != audio_tstamp->tv_sec ||
         runtime->status->audio_tstamp.tv_nsec != audio_tstamp->tv_nsec) {
         runtime->status->audio_tstamp.tv_sec = audio_tstamp->tv_sec;
         runtime->status->audio_tstamp.tv_nsec = audio_tstamp->tv_nsec;
         runtime->status->tstamp.tv_sec = curr_tstamp->tv_sec;
         runtime->status->tstamp.tv_nsec = curr_tstamp->tv_nsec;
     }
 
 
     /*
      * 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, &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 timespec64 curr_tstamp;
     struct timespec64 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, &curr_tstamp);
         } else
             snd_pcm_gettime(runtime, &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_set_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_array(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 const 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_under_stream_lock() - update the status of runtime for the next period
  *                      under acquired lock of PCM substream.
  * @substream: the instance of pcm substream.
  *
  * This function is called when the batch of audio data frames as the same size as the period of
  * buffer is already processed in audio data transmission.
  *
  * The call of function updates the status of runtime with the latest position of audio data
  * transmission, checks overrun and underrun over buffer, awaken user processes from waiting for
  * available audio data frames, sampling audio timestamp, and performs stop or drain the PCM
  * substream according to configured threshold.
  *
  * The function is intended to use for the case that PCM driver operates audio data frames under
  * acquired lock of PCM substream; e.g. in callback of any operation of &snd_pcm_ops in process
  * context. In any interrupt context, it's preferrable to use ``snd_pcm_period_elapsed()`` instead
  * since lock of PCM substream should be acquired in advance.
  *
  * Developer should pay enough attention that some callbacks in &snd_pcm_ops are done by the call of
  * function:
  *
  * - .pointer - to retrieve current position of audio data transmission by frame count or XRUN state.
  * - .trigger - with SNDRV_PCM_TRIGGER_STOP at XRUN or DRAINING state.
  * - .get_time_info - to retrieve audio time stamp if needed.
  *
  * Even if more than one periods have elapsed since the last call, you have to call this only once.
  */
 void snd_pcm_period_elapsed_under_stream_lock(struct snd_pcm_substream *substream)
 {
     struct snd_pcm_runtime *runtime;
 
     if (PCM_RUNTIME_CHECK(substream))
         return;
     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:
     snd_kill_fasync(runtime->fasync, SIGIO, POLL_IN);
 }
 EXPORT_SYMBOL(snd_pcm_period_elapsed_under_stream_lock);
 
 /**
  * snd_pcm_period_elapsed() - update the status of runtime for the next period by acquiring lock of
  *                PCM substream.
  * @substream: the instance of PCM substream.
  *
  * This function is mostly similar to ``snd_pcm_period_elapsed_under_stream_lock()`` except for
  * acquiring lock of PCM substream voluntarily.
  *
  * It's typically called by any type of IRQ handler when hardware IRQ occurs to notify event that
  * the batch of audio data frames as the same size as the period of buffer is already processed in
  * audio data transmission.
  */
 void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
 {
     unsigned long flags;
 
     if (snd_BUG_ON(!substream))
         return;
 
     snd_pcm_stream_lock_irqsave(substream, flags);
     snd_pcm_period_elapsed_under_stream_lock(substream);
     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;
     snd_pcm_sframes_t diff;
     int ret;
 
     if (old_appl_ptr == appl_ptr)
         return 0;
 
     if (appl_ptr >= runtime->boundary)
         return -EINVAL;
     /*
      * check if a rewind is requested by the application
      */
     if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) {
         diff = appl_ptr - old_appl_ptr;
         if (diff >= 0) {
             if (diff > runtime->buffer_size)
                 return -EINVAL;
         } else {
             if (runtime->boundary + diff > runtime->buffer_size)
                 return -EINVAL;
         }
     }
 
     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;
 
     runtime->twake = runtime->control->avail_min ? : 1;
     if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)
         snd_pcm_update_hw_ptr(substream);
 
     /*
      * If size < start_threshold, wait indefinitely. Another
      * thread may start capture
      */
     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;
     }
 
     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)) {
             err = -EINVAL;
             goto _end_unlock;
         }
         if (!atomic_inc_unless_negative(&runtime->buffer_accessing)) {
             err = -EBUSY;
             goto _end_unlock;
         }
         snd_pcm_stream_unlock_irq(substream);
         if (!is_playback)
             snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_CPU);
         err = writer(substream, appl_ofs, data, offset, frames,
                  transfer);
         if (is_playback)
             snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_DEVICE);
         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 = 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(long) * info->max_channels);
     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);