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

#if 0
#define PLUGIN_DEBUG
#endif
#if 0
#define OSS_DEBUG
#endif

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/time.h>
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/math64.h>
#include <linux/string.h>
#include <linux/compat.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include "pcm_plugin.h"
#include <sound/info.h>
#include <linux/soundcard.h>
#include <sound/initval.h>
#include <sound/mixer_oss.h>

#define OSS_ALSAEMULVER         _SIOR ('M', 249, int)

static int dsp_map[SNDRV_CARDS];
static int adsp_map[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS-1)] = 1};
static bool nonblock_open = 1;

MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>, Abramo Bagnara <abramo@alsa-project.org>");
MODULE_DESCRIPTION("PCM OSS emulation for ALSA.");
MODULE_LICENSE("GPL");
module_param_array(dsp_map, int, NULL, 0444);
MODULE_PARM_DESC(dsp_map, "PCM device number assigned to 1st OSS device.");
module_param_array(adsp_map, int, NULL, 0444);
MODULE_PARM_DESC(adsp_map, "PCM device number assigned to 2nd OSS device.");
module_param(nonblock_open, bool, 0644);
MODULE_PARM_DESC(nonblock_open, "Don't block opening busy PCM devices.");
MODULE_ALIAS_SNDRV_MINOR(SNDRV_MINOR_OSS_PCM);
MODULE_ALIAS_SNDRV_MINOR(SNDRV_MINOR_OSS_PCM1);

static int snd_pcm_oss_get_rate(struct snd_pcm_oss_file *pcm_oss_file);
static int snd_pcm_oss_get_channels(struct snd_pcm_oss_file *pcm_oss_file);
static int snd_pcm_oss_get_format(struct snd_pcm_oss_file *pcm_oss_file);

/*
 * helper functions to process hw_params
 */
static int snd_interval_refine_min(struct snd_interval *i, unsigned int min, int openmin)
{
        int changed = 0;
        if (i->min < min) {
                i->min = min;
                i->openmin = openmin;
                changed = 1;
        } else if (i->min == min && !i->openmin && openmin) {
                i->openmin = 1;
                changed = 1;
        }
        if (i->integer) {
                if (i->openmin) {
                        i->min++;
                        i->openmin = 0;
                }
        }
        if (snd_interval_checkempty(i)) {
                snd_interval_none(i);
                return -EINVAL;
        }
        return changed;
}

static int snd_interval_refine_max(struct snd_interval *i, unsigned int max, int openmax)
{
        int changed = 0;
        if (i->max > max) {
                i->max = max;
                i->openmax = openmax;
                changed = 1;
        } else if (i->max == max && !i->openmax && openmax) {
                i->openmax = 1;
                changed = 1;
        }
        if (i->integer) {
                if (i->openmax) {
                        i->max--;
                        i->openmax = 0;
                }
        }
        if (snd_interval_checkempty(i)) {
                snd_interval_none(i);
                return -EINVAL;
        }
        return changed;
}

static int snd_interval_refine_set(struct snd_interval *i, unsigned int val)
{
        struct snd_interval t;
        t.empty = 0;
        t.min = t.max = val;
        t.openmin = t.openmax = 0;
        t.integer = 1;
        return snd_interval_refine(i, &t);
}

/**
 * snd_pcm_hw_param_value_min
 * @params: the hw_params instance
 * @var: parameter to retrieve
 * @dir: pointer to the direction (-1,0,1) or NULL
 *
 * Return the minimum value for field PAR.
 */
static unsigned int
snd_pcm_hw_param_value_min(const struct snd_pcm_hw_params *params,
                           snd_pcm_hw_param_t var, int *dir)
{
        if (hw_is_mask(var)) {
                if (dir)
                        *dir = 0;
                return snd_mask_min(hw_param_mask_c(params, var));
        }
        if (hw_is_interval(var)) {
                const struct snd_interval *i = hw_param_interval_c(params, var);
                if (dir)
                        *dir = i->openmin;
                return snd_interval_min(i);
        }
        return -EINVAL;
}

/**
 * snd_pcm_hw_param_value_max
 * @params: the hw_params instance
 * @var: parameter to retrieve
 * @dir: pointer to the direction (-1,0,1) or NULL
 *
 * Return the maximum value for field PAR.
 */
static int
snd_pcm_hw_param_value_max(const struct snd_pcm_hw_params *params,
                           snd_pcm_hw_param_t var, int *dir)
{
        if (hw_is_mask(var)) {
                if (dir)
                        *dir = 0;
                return snd_mask_max(hw_param_mask_c(params, var));
        }
        if (hw_is_interval(var)) {
                const struct snd_interval *i = hw_param_interval_c(params, var);
                if (dir)
                        *dir = - (int) i->openmax;
                return snd_interval_max(i);
        }
        return -EINVAL;
}

static int _snd_pcm_hw_param_mask(struct snd_pcm_hw_params *params,
                                  snd_pcm_hw_param_t var,
                                  const struct snd_mask *val)
{
        int changed;
        changed = snd_mask_refine(hw_param_mask(params, var), val);
        if (changed > 0) {
                params->cmask |= 1 << var;
                params->rmask |= 1 << var;
        }
        return changed;
}

static int snd_pcm_hw_param_mask(struct snd_pcm_substream *pcm,
                                 struct snd_pcm_hw_params *params,
                                 snd_pcm_hw_param_t var,
                                 const struct snd_mask *val)
{
        int changed = _snd_pcm_hw_param_mask(params, var, val);
        if (changed < 0)
                return changed;
        if (params->rmask) {
                int err = snd_pcm_hw_refine(pcm, params);
                if (err < 0)
                        return err;
        }
        return 0;
}

static int _snd_pcm_hw_param_min(struct snd_pcm_hw_params *params,
                                 snd_pcm_hw_param_t var, unsigned int val,
                                 int dir)
{
        int changed;
        int open = 0;
        if (dir) {
                if (dir > 0) {
                        open = 1;
                } else if (dir < 0) {
                        if (val > 0) {
                                open = 1;
                                val--;
                        }
                }
        }
        if (hw_is_mask(var))
                changed = snd_mask_refine_min(hw_param_mask(params, var),
                                              val + !!open);
        else if (hw_is_interval(var))
                changed = snd_interval_refine_min(hw_param_interval(params, var),
                                                  val, open);
        else
                return -EINVAL;
        if (changed > 0) {
                params->cmask |= 1 << var;
                params->rmask |= 1 << var;
        }
        return changed;
}

/**
 * snd_pcm_hw_param_min
 * @pcm: PCM instance
 * @params: the hw_params instance
 * @var: parameter to retrieve
 * @val: minimal value
 * @dir: pointer to the direction (-1,0,1) or NULL
 *
 * Inside configuration space defined by PARAMS remove from PAR all 
 * values < VAL. Reduce configuration space accordingly.
 * Return new minimum or -EINVAL if the configuration space is empty
 */
static int snd_pcm_hw_param_min(struct snd_pcm_substream *pcm,
                                struct snd_pcm_hw_params *params,
                                snd_pcm_hw_param_t var, unsigned int val,
                                int *dir)
{
        int changed = _snd_pcm_hw_param_min(params, var, val, dir ? *dir : 0);
        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_min(params, var, dir);
}

static int _snd_pcm_hw_param_max(struct snd_pcm_hw_params *params,
                                 snd_pcm_hw_param_t var, unsigned int val,
                                 int dir)
{
        int changed;
        int open = 0;
        if (dir) {
                if (dir < 0) {
                        open = 1;
                } else if (dir > 0) {
                        open = 1;
                        val++;
                }
        }
        if (hw_is_mask(var)) {
                if (val == 0 && open) {
                        snd_mask_none(hw_param_mask(params, var));
                        changed = -EINVAL;
                } else
                        changed = snd_mask_refine_max(hw_param_mask(params, var),
                                                      val - !!open);
        } else if (hw_is_interval(var))
                changed = snd_interval_refine_max(hw_param_interval(params, var),
                                                  val, open);
        else
                return -EINVAL;
        if (changed > 0) {
                params->cmask |= 1 << var;
                params->rmask |= 1 << var;
        }
        return changed;
}

/**
 * snd_pcm_hw_param_max
 * @pcm: PCM instance
 * @params: the hw_params instance
 * @var: parameter to retrieve
 * @val: maximal value
 * @dir: pointer to the direction (-1,0,1) or NULL
 *
 * Inside configuration space defined by PARAMS remove from PAR all 
 *  values >= VAL + 1. Reduce configuration space accordingly.
 *  Return new maximum or -EINVAL if the configuration space is empty
 */
static int snd_pcm_hw_param_max(struct snd_pcm_substream *pcm,
                                struct snd_pcm_hw_params *params,
                                snd_pcm_hw_param_t var, unsigned int val,
                                int *dir)
{
        int changed = _snd_pcm_hw_param_max(params, var, val, dir ? *dir : 0);
        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_max(params, var, dir);
}

static int boundary_sub(int a, int adir,
                        int b, int bdir,
                        int *c, int *cdir)
{
        adir = adir < 0 ? -1 : (adir > 0 ? 1 : 0);
        bdir = bdir < 0 ? -1 : (bdir > 0 ? 1 : 0);
        *c = a - b;
        *cdir = adir - bdir;
        if (*cdir == -2) {
                (*c)--;
        } else if (*cdir == 2) {
                (*c)++;
        }
        return 0;
}

static int boundary_lt(unsigned int a, int adir,
                       unsigned int b, int bdir)
{
        if (adir < 0) {
                a--;
                adir = 1;
        } else if (adir > 0)
                adir = 1;
        if (bdir < 0) {
                b--;
                bdir = 1;
        } else if (bdir > 0)
                bdir = 1;
        return a < b || (a == b && adir < bdir);
}

/* Return 1 if min is nearer to best than max */
static int boundary_nearer(int min, int mindir,
                           int best, int bestdir,
                           int max, int maxdir)
{
        int dmin, dmindir;
        int dmax, dmaxdir;
        boundary_sub(best, bestdir, min, mindir, &dmin, &dmindir);
        boundary_sub(max, maxdir, best, bestdir, &dmax, &dmaxdir);
        return boundary_lt(dmin, dmindir, dmax, dmaxdir);
}

/**
 * snd_pcm_hw_param_near
 * @pcm: PCM instance
 * @params: the hw_params instance
 * @var: parameter to retrieve
 * @best: value to set
 * @dir: pointer to the direction (-1,0,1) or NULL
 *
 * Inside configuration space defined by PARAMS set PAR to the available value
 * nearest to VAL. Reduce configuration space accordingly.
 * This function cannot be called for SNDRV_PCM_HW_PARAM_ACCESS,
 * SNDRV_PCM_HW_PARAM_FORMAT, SNDRV_PCM_HW_PARAM_SUBFORMAT.
 * Return the value found.
  */
static int snd_pcm_hw_param_near(struct snd_pcm_substream *pcm,
                                 struct snd_pcm_hw_params *params,
                                 snd_pcm_hw_param_t var, unsigned int best,
                                 int *dir)
{
        struct snd_pcm_hw_params *save = NULL;
        int v;
        unsigned int saved_min;
        int last = 0;
        int min, max;
        int mindir, maxdir;
        int valdir = dir ? *dir : 0;
        /* FIXME */
        if (best > INT_MAX)
                best = INT_MAX;
        min = max = best;
        mindir = maxdir = valdir;
        if (maxdir > 0)
                maxdir = 0;
        else if (maxdir == 0)
                maxdir = -1;
        else {
                maxdir = 1;
                max--;
        }
        save = kmalloc(sizeof(*save), GFP_KERNEL);
        if (save == NULL)
                return -ENOMEM;
        *save = *params;
        saved_min = min;
        min = snd_pcm_hw_param_min(pcm, params, var, min, &mindir);
        if (min >= 0) {
                struct snd_pcm_hw_params *params1;
                if (max < 0)
                        goto _end;
                if ((unsigned int)min == saved_min && mindir == valdir)
                        goto _end;
                params1 = kmalloc(sizeof(*params1), GFP_KERNEL);
                if (params1 == NULL) {
                        kfree(save);
                        return -ENOMEM;
                }
                *params1 = *save;
                max = snd_pcm_hw_param_max(pcm, params1, var, max, &maxdir);
                if (max < 0) {
                        kfree(params1);
                        goto _end;
                }
                if (boundary_nearer(max, maxdir, best, valdir, min, mindir)) {
                        *params = *params1;
                        last = 1;
                }
                kfree(params1);
        } else {
                *params = *save;
                max = snd_pcm_hw_param_max(pcm, params, var, max, &maxdir);
                if (max < 0) {
                        kfree(save);
                        return max;
                }
                last = 1;
        }
 _end:
        kfree(save);
        if (last)
                v = snd_pcm_hw_param_last(pcm, params, var, dir);
        else
                v = snd_pcm_hw_param_first(pcm, params, var, dir);
        return v;
}

static int _snd_pcm_hw_param_set(struct snd_pcm_hw_params *params,
                                 snd_pcm_hw_param_t var, unsigned int val,
                                 int dir)
{
        int changed;
        if (hw_is_mask(var)) {
                struct snd_mask *m = hw_param_mask(params, var);
                if (val == 0 && dir < 0) {
                        changed = -EINVAL;
                        snd_mask_none(m);
                } else {
                        if (dir > 0)
                                val++;
                        else if (dir < 0)
                                val--;
                        changed = snd_mask_refine_set(hw_param_mask(params, var), val);
                }
        } else if (hw_is_interval(var)) {
                struct snd_interval *i = hw_param_interval(params, var);
                if (val == 0 && dir < 0) {
                        changed = -EINVAL;
                        snd_interval_none(i);
                } else if (dir == 0)
                        changed = snd_interval_refine_set(i, val);
                else {
                        struct snd_interval t;
                        t.openmin = 1;
                        t.openmax = 1;
                        t.empty = 0;
                        t.integer = 0;
                        if (dir < 0) {
                                t.min = val - 1;
                                t.max = val;
                        } else {
                                t.min = val;
                                t.max = val+1;
                        }
                        changed = snd_interval_refine(i, &t);
                }
        } else
                return -EINVAL;
        if (changed > 0) {
                params->cmask |= 1 << var;
                params->rmask |= 1 << var;
        }
        return changed;
}

/**
 * snd_pcm_hw_param_set
 * @pcm: PCM instance
 * @params: the hw_params instance
 * @var: parameter to retrieve
 * @val: value to set
 * @dir: pointer to the direction (-1,0,1) or NULL
 *
 * Inside configuration space defined by PARAMS remove from PAR all 
 * values != VAL. Reduce configuration space accordingly.
 *  Return VAL or -EINVAL if the configuration space is empty
 */
static int snd_pcm_hw_param_set(struct snd_pcm_substream *pcm,
                                struct snd_pcm_hw_params *params,
                                snd_pcm_hw_param_t var, unsigned int val,
                                int dir)
{
        int changed = _snd_pcm_hw_param_set(params, var, val, dir);
        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, NULL);
}

static int _snd_pcm_hw_param_setinteger(struct snd_pcm_hw_params *params,
                                        snd_pcm_hw_param_t var)
{
        int changed;
        changed = snd_interval_setinteger(hw_param_interval(params, var));
        if (changed > 0) {
                params->cmask |= 1 << var;
                params->rmask |= 1 << var;
        }
        return changed;
}
        
/*
 * plugin
 */

#ifdef CONFIG_SND_PCM_OSS_PLUGINS
static int snd_pcm_oss_plugin_clear(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct snd_pcm_plugin *plugin, *next;
        
        plugin = runtime->oss.plugin_first;
        while (plugin) {
                next = plugin->next;
                snd_pcm_plugin_free(plugin);
                plugin = next;
        }
        runtime->oss.plugin_first = runtime->oss.plugin_last = NULL;
        return 0;
}

static int snd_pcm_plugin_insert(struct snd_pcm_plugin *plugin)
{
        struct snd_pcm_runtime *runtime = plugin->plug->runtime;
        plugin->next = runtime->oss.plugin_first;
        plugin->prev = NULL;
        if (runtime->oss.plugin_first) {
                runtime->oss.plugin_first->prev = plugin;
                runtime->oss.plugin_first = plugin;
        } else {
                runtime->oss.plugin_last =
                runtime->oss.plugin_first = plugin;
        }
        return 0;
}

int snd_pcm_plugin_append(struct snd_pcm_plugin *plugin)
{
        struct snd_pcm_runtime *runtime = plugin->plug->runtime;
        plugin->next = NULL;
        plugin->prev = runtime->oss.plugin_last;
        if (runtime->oss.plugin_last) {
                runtime->oss.plugin_last->next = plugin;
                runtime->oss.plugin_last = plugin;
        } else {
                runtime->oss.plugin_last =
                runtime->oss.plugin_first = plugin;
        }
        return 0;
}
#endif /* CONFIG_SND_PCM_OSS_PLUGINS */

static long snd_pcm_oss_bytes(struct snd_pcm_substream *substream, long frames)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        long buffer_size = snd_pcm_lib_buffer_bytes(substream);
        long bytes = frames_to_bytes(runtime, frames);
        if (buffer_size == runtime->oss.buffer_bytes)
                return bytes;
#if BITS_PER_LONG >= 64
        return runtime->oss.buffer_bytes * bytes / buffer_size;
#else
        {
                u64 bsize = (u64)runtime->oss.buffer_bytes * (u64)bytes;
                return div_u64(bsize, buffer_size);
        }
#endif
}

static long snd_pcm_alsa_frames(struct snd_pcm_substream *substream, long bytes)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        long buffer_size = snd_pcm_lib_buffer_bytes(substream);
        if (buffer_size == runtime->oss.buffer_bytes)
                return bytes_to_frames(runtime, bytes);
        return bytes_to_frames(runtime, (buffer_size * bytes) / runtime->oss.buffer_bytes);
}

static inline
snd_pcm_uframes_t get_hw_ptr_period(struct snd_pcm_runtime *runtime)
{
        return runtime->hw_ptr_interrupt;
}

/* define extended formats in the recent OSS versions (if any) */
/* linear formats */
#define AFMT_S32_LE      0x00001000
#define AFMT_S32_BE      0x00002000
#define AFMT_S24_LE      0x00008000
#define AFMT_S24_BE      0x00010000
#define AFMT_S24_PACKED  0x00040000

/* other supported formats */
#define AFMT_FLOAT       0x00004000
#define AFMT_SPDIF_RAW   0x00020000

/* unsupported formats */
#define AFMT_AC3         0x00000400
#define AFMT_VORBIS      0x00000800

static snd_pcm_format_t snd_pcm_oss_format_from(int format)
{
        switch (format) {
        case AFMT_MU_LAW:       return SNDRV_PCM_FORMAT_MU_LAW;
        case AFMT_A_LAW:        return SNDRV_PCM_FORMAT_A_LAW;
        case AFMT_IMA_ADPCM:    return SNDRV_PCM_FORMAT_IMA_ADPCM;
        case AFMT_U8:           return SNDRV_PCM_FORMAT_U8;
        case AFMT_S16_LE:       return SNDRV_PCM_FORMAT_S16_LE;
        case AFMT_S16_BE:       return SNDRV_PCM_FORMAT_S16_BE;
        case AFMT_S8:           return SNDRV_PCM_FORMAT_S8;
        case AFMT_U16_LE:       return SNDRV_PCM_FORMAT_U16_LE;
        case AFMT_U16_BE:       return SNDRV_PCM_FORMAT_U16_BE;
        case AFMT_MPEG:         return SNDRV_PCM_FORMAT_MPEG;
        case AFMT_S32_LE:       return SNDRV_PCM_FORMAT_S32_LE;
        case AFMT_S32_BE:       return SNDRV_PCM_FORMAT_S32_BE;
        case AFMT_S24_LE:       return SNDRV_PCM_FORMAT_S24_LE;
        case AFMT_S24_BE:       return SNDRV_PCM_FORMAT_S24_BE;
        case AFMT_S24_PACKED:   return SNDRV_PCM_FORMAT_S24_3LE;
        case AFMT_FLOAT:        return SNDRV_PCM_FORMAT_FLOAT;
        case AFMT_SPDIF_RAW:    return SNDRV_PCM_FORMAT_IEC958_SUBFRAME;
        default:                return SNDRV_PCM_FORMAT_U8;
        }
}

static int snd_pcm_oss_format_to(snd_pcm_format_t format)
{
        switch (format) {
        case SNDRV_PCM_FORMAT_MU_LAW:   return AFMT_MU_LAW;
        case SNDRV_PCM_FORMAT_A_LAW:    return AFMT_A_LAW;
        case SNDRV_PCM_FORMAT_IMA_ADPCM:        return AFMT_IMA_ADPCM;
        case SNDRV_PCM_FORMAT_U8:               return AFMT_U8;
        case SNDRV_PCM_FORMAT_S16_LE:   return AFMT_S16_LE;
        case SNDRV_PCM_FORMAT_S16_BE:   return AFMT_S16_BE;
        case SNDRV_PCM_FORMAT_S8:               return AFMT_S8;
        case SNDRV_PCM_FORMAT_U16_LE:   return AFMT_U16_LE;
        case SNDRV_PCM_FORMAT_U16_BE:   return AFMT_U16_BE;
        case SNDRV_PCM_FORMAT_MPEG:             return AFMT_MPEG;
        case SNDRV_PCM_FORMAT_S32_LE:   return AFMT_S32_LE;
        case SNDRV_PCM_FORMAT_S32_BE:   return AFMT_S32_BE;
        case SNDRV_PCM_FORMAT_S24_LE:   return AFMT_S24_LE;
        case SNDRV_PCM_FORMAT_S24_BE:   return AFMT_S24_BE;
        case SNDRV_PCM_FORMAT_S24_3LE:  return AFMT_S24_PACKED;
        case SNDRV_PCM_FORMAT_FLOAT:    return AFMT_FLOAT;
        case SNDRV_PCM_FORMAT_IEC958_SUBFRAME: return AFMT_SPDIF_RAW;
        default:                        return -EINVAL;
        }
}

static int snd_pcm_oss_period_size(struct snd_pcm_substream *substream, 
                                   struct snd_pcm_hw_params *oss_params,
                                   struct snd_pcm_hw_params *slave_params)
{
        ssize_t s;
        ssize_t oss_buffer_size;
        ssize_t oss_period_size, oss_periods;
        ssize_t min_period_size, max_period_size;
        struct snd_pcm_runtime *runtime = substream->runtime;
        size_t oss_frame_size;

        oss_frame_size = snd_pcm_format_physical_width(params_format(oss_params)) *
                         params_channels(oss_params) / 8;

        oss_buffer_size = snd_pcm_hw_param_value_max(slave_params,
                                                     SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
                                                     NULL);
        if (oss_buffer_size <= 0)
                return -EINVAL;
        oss_buffer_size = snd_pcm_plug_client_size(substream,
                                                   oss_buffer_size * oss_frame_size);
        if (oss_buffer_size <= 0)
                return -EINVAL;
        oss_buffer_size = rounddown_pow_of_two(oss_buffer_size);
        if (atomic_read(&substream->mmap_count)) {
                if (oss_buffer_size > runtime->oss.mmap_bytes)
                        oss_buffer_size = runtime->oss.mmap_bytes;
        }

        if (substream->oss.setup.period_size > 16)
                oss_period_size = substream->oss.setup.period_size;
        else if (runtime->oss.fragshift) {
                oss_period_size = 1 << runtime->oss.fragshift;
                if (oss_period_size > oss_buffer_size / 2)
                        oss_period_size = oss_buffer_size / 2;
        } else {
                int sd;
                size_t bytes_per_sec = params_rate(oss_params) * snd_pcm_format_physical_width(params_format(oss_params)) * params_channels(oss_params) / 8;

                oss_period_size = oss_buffer_size;
                do {
                        oss_period_size /= 2;
                } while (oss_period_size > bytes_per_sec);
                if (runtime->oss.subdivision == 0) {
                        sd = 4;
                        if (oss_period_size / sd > 4096)
                                sd *= 2;
                        if (oss_period_size / sd < 4096)
                                sd = 1;
                } else
                        sd = runtime->oss.subdivision;
                oss_period_size /= sd;
                if (oss_period_size < 16)
                        oss_period_size = 16;
        }

        min_period_size = snd_pcm_plug_client_size(substream,
                                                   snd_pcm_hw_param_value_min(slave_params, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, NULL));
        if (min_period_size > 0) {
                min_period_size *= oss_frame_size;
                min_period_size = roundup_pow_of_two(min_period_size);
                if (oss_period_size < min_period_size)
                        oss_period_size = min_period_size;
        }

        max_period_size = snd_pcm_plug_client_size(substream,
                                                   snd_pcm_hw_param_value_max(slave_params, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, NULL));
        if (max_period_size > 0) {
                max_period_size *= oss_frame_size;
                max_period_size = rounddown_pow_of_two(max_period_size);
                if (oss_period_size > max_period_size)
                        oss_period_size = max_period_size;
        }

        oss_periods = oss_buffer_size / oss_period_size;

        if (substream->oss.setup.periods > 1)
                oss_periods = substream->oss.setup.periods;

        s = snd_pcm_hw_param_value_max(slave_params, SNDRV_PCM_HW_PARAM_PERIODS, NULL);
        if (s > 0 && runtime->oss.maxfrags && s > runtime->oss.maxfrags)
                s = runtime->oss.maxfrags;
        if (oss_periods > s)
                oss_periods = s;

        s = snd_pcm_hw_param_value_min(slave_params, SNDRV_PCM_HW_PARAM_PERIODS, NULL);
        if (s < 2)
                s = 2;
        if (oss_periods < s)
                oss_periods = s;

        while (oss_period_size * oss_periods > oss_buffer_size)
                oss_period_size /= 2;

        if (oss_period_size < 16)
                return -EINVAL;

        /* don't allocate too large period; 1MB period must be enough */
        if (oss_period_size > 1024 * 1024)
                return -ENOMEM;

        runtime->oss.period_bytes = oss_period_size;
        runtime->oss.period_frames = 1;
        runtime->oss.periods = oss_periods;
        return 0;
}

static int choose_rate(struct snd_pcm_substream *substream,
                       struct snd_pcm_hw_params *params, unsigned int best_rate)
{
        const struct snd_interval *it;
        struct snd_pcm_hw_params *save;
        unsigned int rate, prev;

        save = kmalloc(sizeof(*save), GFP_KERNEL);
        if (save == NULL)
                return -ENOMEM;
        *save = *params;
        it = hw_param_interval_c(save, SNDRV_PCM_HW_PARAM_RATE);

        /* try multiples of the best rate */
        rate = best_rate;
        for (;;) {
                if (it->max < rate || (it->max == rate && it->openmax))
                        break;
                if (it->min < rate || (it->min == rate && !it->openmin)) {
                        int ret;
                        ret = snd_pcm_hw_param_set(substream, params,
                                                   SNDRV_PCM_HW_PARAM_RATE,
                                                   rate, 0);
                        if (ret == (int)rate) {
                                kfree(save);
                                return rate;
                        }
                        *params = *save;
                }
                prev = rate;
                rate += best_rate;
                if (rate <= prev)
                        break;
        }

        /* not found, use the nearest rate */
        kfree(save);
        return snd_pcm_hw_param_near(substream, params, SNDRV_PCM_HW_PARAM_RATE, best_rate, NULL);
}

/* parameter locking: returns immediately if tried during streaming */
static int lock_params(struct snd_pcm_runtime *runtime)
{
        if (mutex_lock_interruptible(&runtime->oss.params_lock))
                return -ERESTARTSYS;
        if (atomic_read(&runtime->oss.rw_ref)) {
                mutex_unlock(&runtime->oss.params_lock);
                return -EBUSY;
        }
        return 0;
}

static void unlock_params(struct snd_pcm_runtime *runtime)
{
        mutex_unlock(&runtime->oss.params_lock);
}

static void snd_pcm_oss_release_buffers(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;

        kvfree(runtime->oss.buffer);
        runtime->oss.buffer = NULL;
#ifdef CONFIG_SND_PCM_OSS_PLUGINS
        snd_pcm_oss_plugin_clear(substream);
#endif
}

/* call with params_lock held */
static int snd_pcm_oss_change_params_locked(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct snd_pcm_hw_params *params, *sparams;
        struct snd_pcm_sw_params *sw_params;
        ssize_t oss_buffer_size, oss_period_size;
        size_t oss_frame_size;
        int err;
        int direct;
        snd_pcm_format_t format, sformat;
        int n;
        const struct snd_mask *sformat_mask;
        struct snd_mask mask;

        if (!runtime->oss.params)
                return 0;
        sw_params = kzalloc(sizeof(*sw_params), GFP_KERNEL);
        params = kmalloc(sizeof(*params), GFP_KERNEL);
        sparams = kmalloc(sizeof(*sparams), GFP_KERNEL);
        if (!sw_params || !params || !sparams) {
                err = -ENOMEM;
                goto failure;
        }

        if (atomic_read(&substream->mmap_count))
                direct = 1;
        else
                direct = substream->oss.setup.direct;

        _snd_pcm_hw_params_any(sparams);
        _snd_pcm_hw_param_setinteger(sparams, SNDRV_PCM_HW_PARAM_PERIODS);
        _snd_pcm_hw_param_min(sparams, SNDRV_PCM_HW_PARAM_PERIODS, 2, 0);
        snd_mask_none(&mask);
        if (atomic_read(&substream->mmap_count))
                snd_mask_set(&mask, (__force int)SNDRV_PCM_ACCESS_MMAP_INTERLEAVED);
        else {
                snd_mask_set(&mask, (__force int)SNDRV_PCM_ACCESS_RW_INTERLEAVED);
                if (!direct)
                        snd_mask_set(&mask, (__force int)SNDRV_PCM_ACCESS_RW_NONINTERLEAVED);
        }
        err = snd_pcm_hw_param_mask(substream, sparams, SNDRV_PCM_HW_PARAM_ACCESS, &mask);
        if (err < 0) {
                pcm_dbg(substream->pcm, "No usable accesses\n");
                err = -EINVAL;
                goto failure;
        }

        err = choose_rate(substream, sparams, runtime->oss.rate);
        if (err < 0)
                goto failure;
        err = snd_pcm_hw_param_near(substream, sparams,
                                    SNDRV_PCM_HW_PARAM_CHANNELS,
                                    runtime->oss.channels, NULL);
        if (err < 0)
                goto failure;

        format = snd_pcm_oss_format_from(runtime->oss.format);

        sformat_mask = hw_param_mask_c(sparams, SNDRV_PCM_HW_PARAM_FORMAT);
        if (direct)
                sformat = format;
        else
                sformat = snd_pcm_plug_slave_format(format, sformat_mask);

        if ((__force int)sformat < 0 ||
            !snd_mask_test_format(sformat_mask, sformat)) {
                pcm_for_each_format(sformat) {
                        if (snd_mask_test_format(sformat_mask, sformat) &&
                            snd_pcm_oss_format_to(sformat) >= 0)
                                goto format_found;
                }
                pcm_dbg(substream->pcm, "Cannot find a format!!!\n");
                err = -EINVAL;
                goto failure;
        }
 format_found:
        err = _snd_pcm_hw_param_set(sparams, SNDRV_PCM_HW_PARAM_FORMAT, (__force int)sformat, 0);
        if (err < 0)
                goto failure;

        if (direct) {
                memcpy(params, sparams, sizeof(*params));
        } else {
                _snd_pcm_hw_params_any(params);
                _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_ACCESS,
                                      (__force int)SNDRV_PCM_ACCESS_RW_INTERLEAVED, 0);
                _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_FORMAT,
                                      (__force int)snd_pcm_oss_format_from(runtime->oss.format), 0);
                _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_CHANNELS,
                                      runtime->oss.channels, 0);
                _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_RATE,
                                      runtime->oss.rate, 0);
                pdprintf("client: access = %i, format = %i, channels = %i, rate = %i\n",
                         params_access(params), params_format(params),
                         params_channels(params), params_rate(params));
        }
        pdprintf("slave: access = %i, format = %i, channels = %i, rate = %i\n",
                 params_access(sparams), params_format(sparams),
                 params_channels(sparams), params_rate(sparams));

        oss_frame_size = snd_pcm_format_physical_width(params_format(params)) *
                         params_channels(params) / 8;

        err = snd_pcm_oss_period_size(substream, params, sparams);
        if (err < 0)
                goto failure;

        n = snd_pcm_plug_slave_size(substream, runtime->oss.period_bytes / oss_frame_size);
        err = snd_pcm_hw_param_near(substream, sparams, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, n, NULL);
        if (err < 0)
                goto failure;

        err = snd_pcm_hw_param_near(substream, sparams, SNDRV_PCM_HW_PARAM_PERIODS,
                                     runtime->oss.periods, NULL);
        if (err < 0)
                goto failure;

        snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);

        err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_HW_PARAMS, sparams);
        if (err < 0) {
                pcm_dbg(substream->pcm, "HW_PARAMS failed: %i\n", err);
                goto failure;
        }

#ifdef CONFIG_SND_PCM_OSS_PLUGINS
        snd_pcm_oss_plugin_clear(substream);
        if (!direct) {
                /* add necessary plugins */
                err = snd_pcm_plug_format_plugins(substream, params, sparams);
                if (err < 0) {
                        pcm_dbg(substream->pcm,
                                "snd_pcm_plug_format_plugins failed: %i\n", err);
                        goto failure;
                }
                if (runtime->oss.plugin_first) {
                        struct snd_pcm_plugin *plugin;
                        err = snd_pcm_plugin_build_io(substream, sparams, &plugin);
                        if (err < 0) {
                                pcm_dbg(substream->pcm,
                                        "snd_pcm_plugin_build_io failed: %i\n", err);
                                goto failure;
                        }
                        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {

                                err = snd_pcm_plugin_append(plugin);
                        } else {
                                err = snd_pcm_plugin_insert(plugin);
                        }
                        if (err < 0)
                                goto failure;
                }
        }
#endif

        if (runtime->oss.trigger) {
                sw_params->start_threshold = 1;
        } else {
                sw_params->start_threshold = runtime->boundary;
        }
        if (atomic_read(&substream->mmap_count) ||
            substream->stream == SNDRV_PCM_STREAM_CAPTURE)
                sw_params->stop_threshold = runtime->boundary;
        else
                sw_params->stop_threshold = runtime->buffer_size;
        sw_params->tstamp_mode = SNDRV_PCM_TSTAMP_NONE;
        sw_params->period_step = 1;
        sw_params->avail_min = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ?
                1 : runtime->period_size;
        if (atomic_read(&substream->mmap_count) ||
            substream->oss.setup.nosilence) {
                sw_params->silence_threshold = 0;
                sw_params->silence_size = 0;
        } else {
                snd_pcm_uframes_t frames;
                frames = runtime->period_size + 16;
                if (frames > runtime->buffer_size)
                        frames = runtime->buffer_size;
                sw_params->silence_threshold = frames;
                sw_params->silence_size = frames;
        }

        err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_SW_PARAMS, sw_params);
        if (err < 0) {
                pcm_dbg(substream->pcm, "SW_PARAMS failed: %i\n", err);
                goto failure;
        }

        runtime->oss.periods = params_periods(sparams);
        oss_period_size = snd_pcm_plug_client_size(substream, params_period_size(sparams));
        if (oss_period_size < 0) {
                err = -EINVAL;
                goto failure;
        }
#ifdef CONFIG_SND_PCM_OSS_PLUGINS
        if (runtime->oss.plugin_first) {
                err = snd_pcm_plug_alloc(substream, oss_period_size);
                if (err < 0)
                        goto failure;
        }
#endif
        oss_period_size = array_size(oss_period_size, oss_frame_size);
        oss_buffer_size = array_size(oss_period_size, runtime->oss.periods);
        if (oss_buffer_size <= 0) {
                err = -EINVAL;
                goto failure;
        }

        runtime->oss.period_bytes = oss_period_size;
        runtime->oss.buffer_bytes = oss_buffer_size;

        pdprintf("oss: period bytes = %i, buffer bytes = %i\n",
                 runtime->oss.period_bytes,
                 runtime->oss.buffer_bytes);
        pdprintf("slave: period_size = %i, buffer_size = %i\n",
                 params_period_size(sparams),
                 params_buffer_size(sparams));

        runtime->oss.format = snd_pcm_oss_format_to(params_format(params));
        runtime->oss.channels = params_channels(params);
        runtime->oss.rate = params_rate(params);

        kvfree(runtime->oss.buffer);
        runtime->oss.buffer = kvzalloc(runtime->oss.period_bytes, GFP_KERNEL);
        if (!runtime->oss.buffer) {
                err = -ENOMEM;
                goto failure;
        }

        runtime->oss.params = 0;
        runtime->oss.prepare = 1;
        runtime->oss.buffer_used = 0;
        if (runtime->dma_area)
                snd_pcm_format_set_silence(runtime->format, runtime->dma_area, bytes_to_samples(runtime, runtime->dma_bytes));

        runtime->oss.period_frames = snd_pcm_alsa_frames(substream, oss_period_size);

        err = 0;
failure:
        if (err)
                snd_pcm_oss_release_buffers(substream);
        kfree(sw_params);
        kfree(params);
        kfree(sparams);
        return err;
}

/* this one takes the lock by itself */
static int snd_pcm_oss_change_params(struct snd_pcm_substream *substream,
                                     bool trylock)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        int err;

        if (trylock) {
                if (!(mutex_trylock(&runtime->oss.params_lock)))
                        return -EAGAIN;
        } else if (mutex_lock_interruptible(&runtime->oss.params_lock))
                return -ERESTARTSYS;

        err = snd_pcm_oss_change_params_locked(substream);
        mutex_unlock(&runtime->oss.params_lock);
        return err;
}

static int snd_pcm_oss_get_active_substream(struct snd_pcm_oss_file *pcm_oss_file, struct snd_pcm_substream **r_substream)
{
        int idx, err;
        struct snd_pcm_substream *asubstream = NULL, *substream;

        for (idx = 0; idx < 2; idx++) {
                substream = pcm_oss_file->streams[idx];
                if (substream == NULL)
                        continue;
                if (asubstream == NULL)
                        asubstream = substream;
                if (substream->runtime->oss.params) {
                        err = snd_pcm_oss_change_params(substream, false);
                        if (err < 0)
                                return err;
                }
        }
        if (!asubstream)
                return -EIO;
        if (r_substream)
                *r_substream = asubstream;
        return 0;
}

/* call with params_lock held */
/* NOTE: this always call PREPARE unconditionally no matter whether
 * runtime->oss.prepare is set or not
 */
static int snd_pcm_oss_prepare(struct snd_pcm_substream *substream)
{
        int err;
        struct snd_pcm_runtime *runtime = substream->runtime;

        err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_PREPARE, NULL);
        if (err < 0) {
                pcm_dbg(substream->pcm,
                        "snd_pcm_oss_prepare: SNDRV_PCM_IOCTL_PREPARE failed\n");
                return err;
        }
        runtime->oss.prepare = 0;
        runtime->oss.prev_hw_ptr_period = 0;
        runtime->oss.period_ptr = 0;
        runtime->oss.buffer_used = 0;

        return 0;
}

static int snd_pcm_oss_make_ready(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime;
        int err;

        runtime = substream->runtime;
        if (runtime->oss.params) {
                err = snd_pcm_oss_change_params(substream, false);
                if (err < 0)
                        return err;
        }
        if (runtime->oss.prepare) {
                if (mutex_lock_interruptible(&runtime->oss.params_lock))
                        return -ERESTARTSYS;
                err = snd_pcm_oss_prepare(substream);
                mutex_unlock(&runtime->oss.params_lock);
                if (err < 0)
                        return err;
        }
        return 0;
}

/* call with params_lock held */
static int snd_pcm_oss_make_ready_locked(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime;
        int err;

        runtime = substream->runtime;
        if (runtime->oss.params) {
                err = snd_pcm_oss_change_params_locked(substream);
                if (err < 0)
                        return err;
        }
        if (runtime->oss.prepare) {
                err = snd_pcm_oss_prepare(substream);
                if (err < 0)
                        return err;
        }
        return 0;
}

static int snd_pcm_oss_capture_position_fixup(struct snd_pcm_substream *substream, snd_pcm_sframes_t *delay)
{
        struct snd_pcm_runtime *runtime;
        snd_pcm_uframes_t frames;
        int err = 0;

        while (1) {
                err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DELAY, delay);
                if (err < 0)
                        break;
                runtime = substream->runtime;
                if (*delay <= (snd_pcm_sframes_t)runtime->buffer_size)
                        break;
                /* in case of overrun, skip whole periods like OSS/Linux driver does */
                /* until avail(delay) <= buffer_size */
                frames = (*delay - runtime->buffer_size) + runtime->period_size - 1;
                frames /= runtime->period_size;
                frames *= runtime->period_size;
                err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_FORWARD, &frames);
                if (err < 0)
                        break;
        }
        return err;
}

snd_pcm_sframes_t snd_pcm_oss_write3(struct snd_pcm_substream *substream, const char *ptr, snd_pcm_uframes_t frames, int in_kernel)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        int ret;
        while (1) {
                if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
                    runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
#ifdef OSS_DEBUG
                        pcm_dbg(substream->pcm,
                                "pcm_oss: write: recovering from %s\n",
                                runtime->status->state == SNDRV_PCM_STATE_XRUN ?
                                "XRUN" : "SUSPEND");
#endif
                        ret = snd_pcm_oss_prepare(substream);
                        if (ret < 0)
                                break;
                }
                mutex_unlock(&runtime->oss.params_lock);
                ret = __snd_pcm_lib_xfer(substream, (void *)ptr, true,
                                         frames, in_kernel);
                mutex_lock(&runtime->oss.params_lock);
                if (ret != -EPIPE && ret != -ESTRPIPE)
                        break;
                /* test, if we can't store new data, because the stream */
                /* has not been started */
                if (runtime->status->state == SNDRV_PCM_STATE_PREPARED)
                        return -EAGAIN;
        }
        return ret;
}

snd_pcm_sframes_t snd_pcm_oss_read3(struct snd_pcm_substream *substream, char *ptr, snd_pcm_uframes_t frames, int in_kernel)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        snd_pcm_sframes_t delay;
        int ret;
        while (1) {
                if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
                    runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
#ifdef OSS_DEBUG
                        pcm_dbg(substream->pcm,
                                "pcm_oss: read: recovering from %s\n",
                                runtime->status->state == SNDRV_PCM_STATE_XRUN ?
                                "XRUN" : "SUSPEND");
#endif
                        ret = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DRAIN, NULL);
                        if (ret < 0)
                                break;
                } else if (runtime->status->state == SNDRV_PCM_STATE_SETUP) {
                        ret = snd_pcm_oss_prepare(substream);
                        if (ret < 0)
                                break;
                }
                ret = snd_pcm_oss_capture_position_fixup(substream, &delay);
                if (ret < 0)
                        break;
                mutex_unlock(&runtime->oss.params_lock);
                ret = __snd_pcm_lib_xfer(substream, (void *)ptr, true,
                                         frames, in_kernel);
                mutex_lock(&runtime->oss.params_lock);
                if (ret == -EPIPE) {
                        if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
                                ret = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
                                if (ret < 0)
                                        break;
                        }
                        continue;
                }
                if (ret != -ESTRPIPE)
                        break;
        }
        return ret;
}

#ifdef CONFIG_SND_PCM_OSS_PLUGINS
snd_pcm_sframes_t snd_pcm_oss_writev3(struct snd_pcm_substream *substream, void **bufs, snd_pcm_uframes_t frames)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        int ret;
        while (1) {
                if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
                    runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
#ifdef OSS_DEBUG
                        pcm_dbg(substream->pcm,
                                "pcm_oss: writev: recovering from %s\n",
                                runtime->status->state == SNDRV_PCM_STATE_XRUN ?
                                "XRUN" : "SUSPEND");
#endif
                        ret = snd_pcm_oss_prepare(substream);
                        if (ret < 0)
                                break;
                }
                ret = snd_pcm_kernel_writev(substream, bufs, frames);
                if (ret != -EPIPE && ret != -ESTRPIPE)
                        break;

                /* test, if we can't store new data, because the stream */
                /* has not been started */
                if (runtime->status->state == SNDRV_PCM_STATE_PREPARED)
                        return -EAGAIN;
        }
        return ret;
}
        
snd_pcm_sframes_t snd_pcm_oss_readv3(struct snd_pcm_substream *substream, void **bufs, snd_pcm_uframes_t frames)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        int ret;
        while (1) {
                if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
                    runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
#ifdef OSS_DEBUG
                        pcm_dbg(substream->pcm,
                                "pcm_oss: readv: recovering from %s\n",
                                runtime->status->state == SNDRV_PCM_STATE_XRUN ?
                                "XRUN" : "SUSPEND");
#endif
                        ret = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DRAIN, NULL);
                        if (ret < 0)
                                break;
                } else if (runtime->status->state == SNDRV_PCM_STATE_SETUP) {
                        ret = snd_pcm_oss_prepare(substream);
                        if (ret < 0)
                                break;
                }
                ret = snd_pcm_kernel_readv(substream, bufs, frames);
                if (ret != -EPIPE && ret != -ESTRPIPE)
                        break;
        }
        return ret;
}
#endif /* CONFIG_SND_PCM_OSS_PLUGINS */

static ssize_t snd_pcm_oss_write2(struct snd_pcm_substream *substream, const char *buf, size_t bytes, int in_kernel)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        snd_pcm_sframes_t frames, frames1;
#ifdef CONFIG_SND_PCM_OSS_PLUGINS
        if (runtime->oss.plugin_first) {
                struct snd_pcm_plugin_channel *channels;
                size_t oss_frame_bytes = (runtime->oss.plugin_first->src_width * runtime->oss.plugin_first->src_format.channels) / 8;
                if (!in_kernel) {
                        if (copy_from_user(runtime->oss.buffer, (const char __force __user *)buf, bytes))
                                return -EFAULT;
                        buf = runtime->oss.buffer;
                }
                frames = bytes / oss_frame_bytes;
                frames1 = snd_pcm_plug_client_channels_buf(substream, (char *)buf, frames, &channels);
                if (frames1 < 0)
                        return frames1;
                frames1 = snd_pcm_plug_write_transfer(substream, channels, frames1);
                if (frames1 <= 0)
                        return frames1;
                bytes = frames1 * oss_frame_bytes;
        } else
#endif
        {
                frames = bytes_to_frames(runtime, bytes);
                frames1 = snd_pcm_oss_write3(substream, buf, frames, in_kernel);
                if (frames1 <= 0)
                        return frames1;
                bytes = frames_to_bytes(runtime, frames1);
        }
        return bytes;
}

static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const char __user *buf, size_t bytes)
{
        size_t xfer = 0;
        ssize_t tmp = 0;
        struct snd_pcm_runtime *runtime = substream->runtime;

        if (atomic_read(&substream->mmap_count))
                return -ENXIO;

        atomic_inc(&runtime->oss.rw_ref);
        while (bytes > 0) {
                if (mutex_lock_interruptible(&runtime->oss.params_lock)) {
                        tmp = -ERESTARTSYS;
                        break;
                }
                tmp = snd_pcm_oss_make_ready_locked(substream);
                if (tmp < 0)
                        goto err;
                if (bytes < runtime->oss.period_bytes || runtime->oss.buffer_used > 0) {
                        tmp = bytes;
                        if (tmp + runtime->oss.buffer_used > runtime->oss.period_bytes)
                                tmp = runtime->oss.period_bytes - runtime->oss.buffer_used;
                        if (tmp > 0) {
                                if (copy_from_user(runtime->oss.buffer + runtime->oss.buffer_used, buf, tmp)) {
                                        tmp = -EFAULT;
                                        goto err;
                                }
                        }
                        runtime->oss.buffer_used += tmp;
                        buf += tmp;
                        bytes -= tmp;
                        xfer += tmp;
                        if (substream->oss.setup.partialfrag ||
                            runtime->oss.buffer_used == runtime->oss.period_bytes) {
                                tmp = snd_pcm_oss_write2(substream, runtime->oss.buffer + runtime->oss.period_ptr, 
                                                         runtime->oss.buffer_used - runtime->oss.period_ptr, 1);
                                if (tmp <= 0)
                                        goto err;
                                runtime->oss.bytes += tmp;
                                runtime->oss.period_ptr += tmp;
                                runtime->oss.period_ptr %= runtime->oss.period_bytes;
                                if (runtime->oss.period_ptr == 0 ||
                                    runtime->oss.period_ptr == runtime->oss.buffer_used)
                                        runtime->oss.buffer_used = 0;
                                else if ((substream->f_flags & O_NONBLOCK) != 0) {
                                        tmp = -EAGAIN;
                                        goto err;
                                }
                        }
                } else {
                        tmp = snd_pcm_oss_write2(substream,
                                                 (const char __force *)buf,
                                                 runtime->oss.period_bytes, 0);
                        if (tmp <= 0)
                                goto err;
                        runtime->oss.bytes += tmp;
                        buf += tmp;
                        bytes -= tmp;
                        xfer += tmp;
                        if ((substream->f_flags & O_NONBLOCK) != 0 &&
                            tmp != runtime->oss.period_bytes)
                                tmp = -EAGAIN;
                }
 err:
                mutex_unlock(&runtime->oss.params_lock);
                if (tmp < 0)
                        break;
                if (signal_pending(current)) {
                        tmp = -ERESTARTSYS;
                        break;
                }
                tmp = 0;
        }
        atomic_dec(&runtime->oss.rw_ref);
        return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
}

static ssize_t snd_pcm_oss_read2(struct snd_pcm_substream *substream, char *buf, size_t bytes, int in_kernel)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        snd_pcm_sframes_t frames, frames1;
#ifdef CONFIG_SND_PCM_OSS_PLUGINS
        char __user *final_dst = (char __force __user *)buf;
        if (runtime->oss.plugin_first) {
                struct snd_pcm_plugin_channel *channels;
                size_t oss_frame_bytes = (runtime->oss.plugin_last->dst_width * runtime->oss.plugin_last->dst_format.channels) / 8;
                if (!in_kernel)
                        buf = runtime->oss.buffer;
                frames = bytes / oss_frame_bytes;
                frames1 = snd_pcm_plug_client_channels_buf(substream, buf, frames, &channels);
                if (frames1 < 0)
                        return frames1;
                frames1 = snd_pcm_plug_read_transfer(substream, channels, frames1);
                if (frames1 <= 0)
                        return frames1;
                bytes = frames1 * oss_frame_bytes;
                if (!in_kernel && copy_to_user(final_dst, buf, bytes))
                        return -EFAULT;
        } else
#endif
        {
                frames = bytes_to_frames(runtime, bytes);
                frames1 = snd_pcm_oss_read3(substream, buf, frames, in_kernel);
                if (frames1 <= 0)
                        return frames1;
                bytes = frames_to_bytes(runtime, frames1);
        }
        return bytes;
}

static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __user *buf, size_t bytes)
{
        size_t xfer = 0;
        ssize_t tmp = 0;
        struct snd_pcm_runtime *runtime = substream->runtime;

        if (atomic_read(&substream->mmap_count))
                return -ENXIO;

        atomic_inc(&runtime->oss.rw_ref);
        while (bytes > 0) {
                if (mutex_lock_interruptible(&runtime->oss.params_lock)) {
                        tmp = -ERESTARTSYS;
                        break;
                }
                tmp = snd_pcm_oss_make_ready_locked(substream);
                if (tmp < 0)
                        goto err;
                if (bytes < runtime->oss.period_bytes || runtime->oss.buffer_used > 0) {
                        if (runtime->oss.buffer_used == 0) {
                                tmp = snd_pcm_oss_read2(substream, runtime->oss.buffer, runtime->oss.period_bytes, 1);
                                if (tmp <= 0)
                                        goto err;
                                runtime->oss.bytes += tmp;
                                runtime->oss.period_ptr = tmp;
                                runtime->oss.buffer_used = tmp;
                        }
                        tmp = bytes;
                        if ((size_t) tmp > runtime->oss.buffer_used)
                                tmp = runtime->oss.buffer_used;
                        if (copy_to_user(buf, runtime->oss.buffer + (runtime->oss.period_ptr - runtime->oss.buffer_used), tmp)) {
                                tmp = -EFAULT;
                                goto err;
                        }
                        buf += tmp;
                        bytes -= tmp;
                        xfer += tmp;
                        runtime->oss.buffer_used -= tmp;
                } else {
                        tmp = snd_pcm_oss_read2(substream, (char __force *)buf,
                                                runtime->oss.period_bytes, 0);
                        if (tmp <= 0)
                                goto err;
                        runtime->oss.bytes += tmp;
                        buf += tmp;
                        bytes -= tmp;
                        xfer += tmp;
                }
 err:
                mutex_unlock(&runtime->oss.params_lock);
                if (tmp < 0)
                        break;
                if (signal_pending(current)) {
                        tmp = -ERESTARTSYS;
                        break;
                }
                tmp = 0;
        }
        atomic_dec(&runtime->oss.rw_ref);
        return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp;
}

static int snd_pcm_oss_reset(struct snd_pcm_oss_file *pcm_oss_file)
{
        struct snd_pcm_substream *substream;
        struct snd_pcm_runtime *runtime;
        int i;

        for (i = 0; i < 2; i++) { 
                substream = pcm_oss_file->streams[i];
                if (!substream)
                        continue;
                runtime = substream->runtime;
                snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
                mutex_lock(&runtime->oss.params_lock);
                runtime->oss.prepare = 1;
                runtime->oss.buffer_used = 0;
                runtime->oss.prev_hw_ptr_period = 0;
                runtime->oss.period_ptr = 0;
                mutex_unlock(&runtime->oss.params_lock);
        }
        return 0;
}

static int snd_pcm_oss_post(struct snd_pcm_oss_file *pcm_oss_file)
{
        struct snd_pcm_substream *substream;
        int err;

        substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
        if (substream != NULL) {
                err = snd_pcm_oss_make_ready(substream);
                if (err < 0)
                        return err;
                snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_START, NULL);
        }
        /* note: all errors from the start action are ignored */
        /* OSS apps do not know, how to handle them */
        return 0;
}

static int snd_pcm_oss_sync1(struct snd_pcm_substream *substream, size_t size)
{
        struct snd_pcm_runtime *runtime;
        ssize_t result = 0;
        snd_pcm_state_t state;
        long res;
        wait_queue_entry_t wait;

        runtime = substream->runtime;
        init_waitqueue_entry(&wait, current);
        add_wait_queue(&runtime->sleep, &wait);
#ifdef OSS_DEBUG
        pcm_dbg(substream->pcm, "sync1: size = %li\n", size);
#endif
        while (1) {
                result = snd_pcm_oss_write2(substream, runtime->oss.buffer, size, 1);
                if (result > 0) {
                        runtime->oss.buffer_used = 0;
                        result = 0;
                        break;
                }
                if (result != 0 && result != -EAGAIN)
                        break;
                result = 0;
                set_current_state(TASK_INTERRUPTIBLE);
                snd_pcm_stream_lock_irq(substream);
                state = runtime->status->state;
                snd_pcm_stream_unlock_irq(substream);
                if (state != SNDRV_PCM_STATE_RUNNING) {
                        set_current_state(TASK_RUNNING);
                        break;
                }
                res = schedule_timeout(10 * HZ);
                if (signal_pending(current)) {
                        result = -ERESTARTSYS;
                        break;
                }
                if (res == 0) {
                        pcm_err(substream->pcm,
                                "OSS sync error - DMA timeout\n");
                        result = -EIO;
                        break;
                }
        }
        remove_wait_queue(&runtime->sleep, &wait);
        return result;
}

static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file)
{
        int err = 0;
        unsigned int saved_f_flags;
        struct snd_pcm_substream *substream;
        struct snd_pcm_runtime *runtime;
        snd_pcm_format_t format;
        unsigned long width;
        size_t size;

        substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
        if (substream != NULL) {
                runtime = substream->runtime;
                if (atomic_read(&substream->mmap_count))
                        goto __direct;
                err = snd_pcm_oss_make_ready(substream);
                if (err < 0)
                        return err;
                atomic_inc(&runtime->oss.rw_ref);
                if (mutex_lock_interruptible(&runtime->oss.params_lock)) {
                        atomic_dec(&runtime->oss.rw_ref);
                        return -ERESTARTSYS;
                }
                format = snd_pcm_oss_format_from(runtime->oss.format);
                width = snd_pcm_format_physical_width(format);
                if (runtime->oss.buffer_used > 0) {
#ifdef OSS_DEBUG
                        pcm_dbg(substream->pcm, "sync: buffer_used\n");
#endif
                        size = (8 * (runtime->oss.period_bytes - runtime->oss.buffer_used) + 7) / width;
                        snd_pcm_format_set_silence(format,
                                                   runtime->oss.buffer + runtime->oss.buffer_used,
                                                   size);
                        err = snd_pcm_oss_sync1(substream, runtime->oss.period_bytes);
                        if (err < 0)
                                goto unlock;
                } else if (runtime->oss.period_ptr > 0) {
#ifdef OSS_DEBUG
                        pcm_dbg(substream->pcm, "sync: period_ptr\n");
#endif
                        size = runtime->oss.period_bytes - runtime->oss.period_ptr;
                        snd_pcm_format_set_silence(format,
                                                   runtime->oss.buffer,
                                                   size * 8 / width);
                        err = snd_pcm_oss_sync1(substream, size);
                        if (err < 0)
                                goto unlock;
                }
                /*
                 * The ALSA's period might be a bit large than OSS one.
                 * Fill the remain portion of ALSA period with zeros.
                 */
                size = runtime->control->appl_ptr % runtime->period_size;
                if (size > 0) {
                        size = runtime->period_size - size;
                        if (runtime->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED)
                                snd_pcm_lib_write(substream, NULL, size);
                        else if (runtime->access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED)
                                snd_pcm_lib_writev(substream, NULL, size);
                }
unlock:
                mutex_unlock(&runtime->oss.params_lock);
                atomic_dec(&runtime->oss.rw_ref);
                if (err < 0)
                        return err;
                /*
                 * finish sync: drain the buffer
                 */
              __direct:
                saved_f_flags = substream->f_flags;
                substream->f_flags &= ~O_NONBLOCK;
                err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DRAIN, NULL);
                substream->f_flags = saved_f_flags;
                if (err < 0)
                        return err;
                mutex_lock(&runtime->oss.params_lock);
                runtime->oss.prepare = 1;
                mutex_unlock(&runtime->oss.params_lock);
        }

        substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
        if (substream != NULL) {
                err = snd_pcm_oss_make_ready(substream);
                if (err < 0)
                        return err;
                runtime = substream->runtime;
                err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
                if (err < 0)
                        return err;
                mutex_lock(&runtime->oss.params_lock);
                runtime->oss.buffer_used = 0;
                runtime->oss.prepare = 1;
                mutex_unlock(&runtime->oss.params_lock);
        }
        return 0;
}

static int snd_pcm_oss_set_rate(struct snd_pcm_oss_file *pcm_oss_file, int rate)
{
        int idx;

        for (idx = 1; idx >= 0; --idx) {
                struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];
                struct snd_pcm_runtime *runtime;
                int err;

                if (substream == NULL)
                        continue;
                runtime = substream->runtime;
                if (rate < 1000)
                        rate = 1000;
                else if (rate > 192000)
                        rate = 192000;
                err = lock_params(runtime);
                if (err < 0)
                        return err;
                if (runtime->oss.rate != rate) {
                        runtime->oss.params = 1;
                        runtime->oss.rate = rate;
                }
                unlock_params(runtime);
        }
        return snd_pcm_oss_get_rate(pcm_oss_file);
}

static int snd_pcm_oss_get_rate(struct snd_pcm_oss_file *pcm_oss_file)
{
        struct snd_pcm_substream *substream;
        int err;
        
        err = snd_pcm_oss_get_active_substream(pcm_oss_file, &substream);
        if (err < 0)
                return err;
        return substream->runtime->oss.rate;
}

static int snd_pcm_oss_set_channels(struct snd_pcm_oss_file *pcm_oss_file, unsigned int channels)
{
        int idx;
        if (channels < 1)
                channels = 1;
        if (channels > 128)
                return -EINVAL;
        for (idx = 1; idx >= 0; --idx) {
                struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];
                struct snd_pcm_runtime *runtime;
                int err;

                if (substream == NULL)
                        continue;
                runtime = substream->runtime;
                err = lock_params(runtime);
                if (err < 0)
                        return err;
                if (runtime->oss.channels != channels) {
                        runtime->oss.params = 1;
                        runtime->oss.channels = channels;
                }
                unlock_params(runtime);
        }
        return snd_pcm_oss_get_channels(pcm_oss_file);
}

static int snd_pcm_oss_get_channels(struct snd_pcm_oss_file *pcm_oss_file)
{
        struct snd_pcm_substream *substream;
        int err;
        
        err = snd_pcm_oss_get_active_substream(pcm_oss_file, &substream);
        if (err < 0)
                return err;
        return substream->runtime->oss.channels;
}

static int snd_pcm_oss_get_block_size(struct snd_pcm_oss_file *pcm_oss_file)
{
        struct snd_pcm_substream *substream;
        int err;
        
        err = snd_pcm_oss_get_active_substream(pcm_oss_file, &substream);
        if (err < 0)
                return err;
        return substream->runtime->oss.period_bytes;
}

static int snd_pcm_oss_get_formats(struct snd_pcm_oss_file *pcm_oss_file)
{
        struct snd_pcm_substream *substream;
        int err;
        int direct;
        struct snd_pcm_hw_params *params;
        unsigned int formats = 0;
        const struct snd_mask *format_mask;
        int fmt;

        err = snd_pcm_oss_get_active_substream(pcm_oss_file, &substream);
        if (err < 0)
                return err;
        if (atomic_read(&substream->mmap_count))
                direct = 1;
        else
                direct = substream->oss.setup.direct;
        if (!direct)
                return AFMT_MU_LAW | AFMT_U8 |
                       AFMT_S16_LE | AFMT_S16_BE |
                       AFMT_S8 | AFMT_U16_LE |
                       AFMT_U16_BE |
                        AFMT_S32_LE | AFMT_S32_BE |
                        AFMT_S24_LE | AFMT_S24_BE |
                        AFMT_S24_PACKED;
        params = kmalloc(sizeof(*params), GFP_KERNEL);
        if (!params)
                return -ENOMEM;
        _snd_pcm_hw_params_any(params);
        err = snd_pcm_hw_refine(substream, params);
        if (err < 0)
                goto error;
        format_mask = hw_param_mask_c(params, SNDRV_PCM_HW_PARAM_FORMAT);
        for (fmt = 0; fmt < 32; ++fmt) {
                if (snd_mask_test(format_mask, fmt)) {
                        int f = snd_pcm_oss_format_to((__force snd_pcm_format_t)fmt);
                        if (f >= 0)
                                formats |= f;
                }
        }

 error:
        kfree(params);
        return err < 0 ? err : formats;
}

static int snd_pcm_oss_set_format(struct snd_pcm_oss_file *pcm_oss_file, int format)
{
        int formats, idx;
        int err;
        
        if (format != AFMT_QUERY) {
                formats = snd_pcm_oss_get_formats(pcm_oss_file);
                if (formats < 0)
                        return formats;
                if (!(formats & format))
                        format = AFMT_U8;
                for (idx = 1; idx >= 0; --idx) {
                        struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];
                        struct snd_pcm_runtime *runtime;
                        if (substream == NULL)
                                continue;
                        runtime = substream->runtime;
                        err = lock_params(runtime);
                        if (err < 0)
                                return err;
                        if (runtime->oss.format != format) {
                                runtime->oss.params = 1;
                                runtime->oss.format = format;
                        }
                        unlock_params(runtime);
                }
        }
        return snd_pcm_oss_get_format(pcm_oss_file);
}

static int snd_pcm_oss_get_format(struct snd_pcm_oss_file *pcm_oss_file)
{
        struct snd_pcm_substream *substream;
        int err;
        
        err = snd_pcm_oss_get_active_substream(pcm_oss_file, &substream);
        if (err < 0)
                return err;
        return substream->runtime->oss.format;
}

static int snd_pcm_oss_set_subdivide1(struct snd_pcm_substream *substream, int subdivide)
{
        struct snd_pcm_runtime *runtime;

        runtime = substream->runtime;
        if (subdivide == 0) {
                subdivide = runtime->oss.subdivision;
                if (subdivide == 0)
                        subdivide = 1;
                return subdivide;
        }
        if (runtime->oss.subdivision || runtime->oss.fragshift)
                return -EINVAL;
        if (subdivide != 1 && subdivide != 2 && subdivide != 4 &&
            subdivide != 8 && subdivide != 16)
                return -EINVAL;
        runtime->oss.subdivision = subdivide;
        runtime->oss.params = 1;
        return subdivide;
}

static int snd_pcm_oss_set_subdivide(struct snd_pcm_oss_file *pcm_oss_file, int subdivide)
{
        int err = -EINVAL, idx;

        for (idx = 1; idx >= 0; --idx) {
                struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];
                struct snd_pcm_runtime *runtime;

                if (substream == NULL)
                        continue;
                runtime = substream->runtime;
                err = lock_params(runtime);
                if (err < 0)
                        return err;
                err = snd_pcm_oss_set_subdivide1(substream, subdivide);
                unlock_params(runtime);
                if (err < 0)
                        return err;
        }
        return err;
}

static int snd_pcm_oss_set_fragment1(struct snd_pcm_substream *substream, unsigned int val)
{
        struct snd_pcm_runtime *runtime;
        int fragshift;

        runtime = substream->runtime;
        if (runtime->oss.subdivision || runtime->oss.fragshift)
                return -EINVAL;
        fragshift = val & 0xffff;
        if (fragshift >= 25) /* should be large enough */
                return -EINVAL;
        runtime->oss.fragshift = fragshift;
        runtime->oss.maxfrags = (val >> 16) & 0xffff;
        if (runtime->oss.fragshift < 4)         /* < 16 */
                runtime->oss.fragshift = 4;
        if (runtime->oss.maxfrags < 2)
                runtime->oss.maxfrags = 2;
        runtime->oss.params = 1;
        return 0;
}

static int snd_pcm_oss_set_fragment(struct snd_pcm_oss_file *pcm_oss_file, unsigned int val)
{
        int err = -EINVAL, idx;

        for (idx = 1; idx >= 0; --idx) {

                struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];
                struct snd_pcm_runtime *runtime;

                if (substream == NULL)
                        continue;
                runtime = substream->runtime;
                err = lock_params(runtime);
                if (err < 0)
                        return err;
                err = snd_pcm_oss_set_fragment1(substream, val);
                unlock_params(runtime);
                if (err < 0)
                        return err;
        }
        return err;
}

static int snd_pcm_oss_nonblock(struct file * file)
{
        spin_lock(&file->f_lock);
        file->f_flags |= O_NONBLOCK;
        spin_unlock(&file->f_lock);
        return 0;
}

static int snd_pcm_oss_get_caps1(struct snd_pcm_substream *substream, int res)
{

        if (substream == NULL) {
                res &= ~DSP_CAP_DUPLEX;
                return res;
        }
#ifdef DSP_CAP_MULTI
        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
                if (substream->pstr->substream_count > 1)
                        res |= DSP_CAP_MULTI;
#endif
        /* DSP_CAP_REALTIME is set all times: */
        /* all ALSA drivers can return actual pointer in ring buffer */
#if defined(DSP_CAP_REALTIME) && 0
        {
                struct snd_pcm_runtime *runtime = substream->runtime;
                if (runtime->info & (SNDRV_PCM_INFO_BLOCK_TRANSFER|SNDRV_PCM_INFO_BATCH))
                        res &= ~DSP_CAP_REALTIME;
        }
#endif
        return res;
}

static int snd_pcm_oss_get_caps(struct snd_pcm_oss_file *pcm_oss_file)
{
        int result, idx;
        
        result = DSP_CAP_TRIGGER | DSP_CAP_MMAP | DSP_CAP_DUPLEX | DSP_CAP_REALTIME;
        for (idx = 0; idx < 2; idx++) {
                struct snd_pcm_substream *substream = pcm_oss_file->streams[idx];
                result = snd_pcm_oss_get_caps1(substream, result);
        }
        result |= 0x0001;       /* revision - same as SB AWE 64 */
        return result;
}

static void snd_pcm_oss_simulate_fill(struct snd_pcm_substream *substream,
                                      snd_pcm_uframes_t hw_ptr)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        snd_pcm_uframes_t appl_ptr;
        appl_ptr = hw_ptr + runtime->buffer_size;
        appl_ptr %= runtime->boundary;
        runtime->control->appl_ptr = appl_ptr;
}

static int snd_pcm_oss_set_trigger(struct snd_pcm_oss_file *pcm_oss_file, int trigger)
{
        struct snd_pcm_runtime *runtime;
        struct snd_pcm_substream *psubstream = NULL, *csubstream = NULL;
        int err, cmd;

#ifdef OSS_DEBUG
        pr_debug("pcm_oss: trigger = 0x%x\n", trigger);
#endif
        
        psubstream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
        csubstream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];

        if (psubstream) {
                err = snd_pcm_oss_make_ready(psubstream);
                if (err < 0)
                        return err;
        }
        if (csubstream) {
                err = snd_pcm_oss_make_ready(csubstream);
                if (err < 0)
                        return err;
        }
        if (psubstream) {
                runtime = psubstream->runtime;
                cmd = 0;
                if (mutex_lock_interruptible(&runtime->oss.params_lock))
                        return -ERESTARTSYS;
                if (trigger & PCM_ENABLE_OUTPUT) {
                        if (runtime->oss.trigger)
                                goto _skip1;
                        if (atomic_read(&psubstream->mmap_count))
                                snd_pcm_oss_simulate_fill(psubstream,
                                                get_hw_ptr_period(runtime));
                        runtime->oss.trigger = 1;
                        runtime->start_threshold = 1;
                        cmd = SNDRV_PCM_IOCTL_START;
                } else {
                        if (!runtime->oss.trigger)
                                goto _skip1;
                        runtime->oss.trigger = 0;
                        runtime->start_threshold = runtime->boundary;
                        cmd = SNDRV_PCM_IOCTL_DROP;
                        runtime->oss.prepare = 1;
                }
 _skip1:
                mutex_unlock(&runtime->oss.params_lock);
                if (cmd) {
                        err = snd_pcm_kernel_ioctl(psubstream, cmd, NULL);
                        if (err < 0)
                                return err;
                }
        }
        if (csubstream) {
                runtime = csubstream->runtime;
                cmd = 0;
                if (mutex_lock_interruptible(&runtime->oss.params_lock))
                        return -ERESTARTSYS;
                if (trigger & PCM_ENABLE_INPUT) {
                        if (runtime->oss.trigger)
                                goto _skip2;
                        runtime->oss.trigger = 1;
                        runtime->start_threshold = 1;
                        cmd = SNDRV_PCM_IOCTL_START;
                } else {
                        if (!runtime->oss.trigger)
                                goto _skip2;
                        runtime->oss.trigger = 0;
                        runtime->start_threshold = runtime->boundary;
                        cmd = SNDRV_PCM_IOCTL_DROP;
                        runtime->oss.prepare = 1;
                }
 _skip2:
                mutex_unlock(&runtime->oss.params_lock);
                if (cmd) {
                        err = snd_pcm_kernel_ioctl(csubstream, cmd, NULL);
                        if (err < 0)
                                return err;
                }
        }
        return 0;
}

static int snd_pcm_oss_get_trigger(struct snd_pcm_oss_file *pcm_oss_file)
{
        struct snd_pcm_substream *psubstream = NULL, *csubstream = NULL;
        int result = 0;

        psubstream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
        csubstream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
        if (psubstream && psubstream->runtime && psubstream->runtime->oss.trigger)
                result |= PCM_ENABLE_OUTPUT;
        if (csubstream && csubstream->runtime && csubstream->runtime->oss.trigger)
                result |= PCM_ENABLE_INPUT;
        return result;
}

static int snd_pcm_oss_get_odelay(struct snd_pcm_oss_file *pcm_oss_file)
{
        struct snd_pcm_substream *substream;
        struct snd_pcm_runtime *runtime;
        snd_pcm_sframes_t delay;
        int err;

        substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
        if (substream == NULL)
                return -EINVAL;
        err = snd_pcm_oss_make_ready(substream);
        if (err < 0)
                return err;
        runtime = substream->runtime;
        if (runtime->oss.params || runtime->oss.prepare)
                return 0;
        err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DELAY, &delay);
        if (err == -EPIPE)
                delay = 0;      /* hack for broken OSS applications */
        else if (err < 0)
                return err;
        return snd_pcm_oss_bytes(substream, delay);
}

static int snd_pcm_oss_get_ptr(struct snd_pcm_oss_file *pcm_oss_file, int stream, struct count_info __user * _info)
{       
        struct snd_pcm_substream *substream;
        struct snd_pcm_runtime *runtime;
        snd_pcm_sframes_t delay;
        int fixup;
        struct count_info info;
        int err;

        if (_info == NULL)
                return -EFAULT;
        substream = pcm_oss_file->streams[stream];
        if (substream == NULL)
                return -EINVAL;
        err = snd_pcm_oss_make_ready(substream);
        if (err < 0)
                return err;
        runtime = substream->runtime;
        if (runtime->oss.params || runtime->oss.prepare) {
                memset(&info, 0, sizeof(info));
                if (copy_to_user(_info, &info, sizeof(info)))
                        return -EFAULT;
                return 0;
        }
        if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
                err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DELAY, &delay);
                if (err == -EPIPE || err == -ESTRPIPE || (! err && delay < 0)) {
                        err = 0;
                        delay = 0;
                        fixup = 0;
                } else {
                        fixup = runtime->oss.buffer_used;
                }
        } else {
                err = snd_pcm_oss_capture_position_fixup(substream, &delay);
                fixup = -runtime->oss.buffer_used;
        }
        if (err < 0)
                return err;
        info.ptr = snd_pcm_oss_bytes(substream, runtime->status->hw_ptr % runtime->buffer_size);
        if (atomic_read(&substream->mmap_count)) {
                snd_pcm_sframes_t n;
                delay = get_hw_ptr_period(runtime);
                n = delay - runtime->oss.prev_hw_ptr_period;
                if (n < 0)
                        n += runtime->boundary;
                info.blocks = n / runtime->period_size;
                runtime->oss.prev_hw_ptr_period = delay;
                if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
                        snd_pcm_oss_simulate_fill(substream, delay);
                info.bytes = snd_pcm_oss_bytes(substream, runtime->status->hw_ptr) & INT_MAX;
        } else {
                delay = snd_pcm_oss_bytes(substream, delay);
                if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
                        if (substream->oss.setup.buggyptr)
                                info.blocks = (runtime->oss.buffer_bytes - delay - fixup) / runtime->oss.period_bytes;
                        else
                                info.blocks = (delay + fixup) / runtime->oss.period_bytes;
                        info.bytes = (runtime->oss.bytes - delay) & INT_MAX;
                } else {
                        delay += fixup;
                        info.blocks = delay / runtime->oss.period_bytes;
                        info.bytes = (runtime->oss.bytes + delay) & INT_MAX;
                }
        }
        if (copy_to_user(_info, &info, sizeof(info)))
                return -EFAULT;
        return 0;
}

static int snd_pcm_oss_get_space(struct snd_pcm_oss_file *pcm_oss_file, int stream, struct audio_buf_info __user *_info)
{
        struct snd_pcm_substream *substream;
        struct snd_pcm_runtime *runtime;
        snd_pcm_sframes_t avail;
        int fixup;
        struct audio_buf_info info;
        int err;

        if (_info == NULL)
                return -EFAULT;
        substream = pcm_oss_file->streams[stream];
        if (substream == NULL)
                return -EINVAL;
        runtime = substream->runtime;

        if (runtime->oss.params) {
                err = snd_pcm_oss_change_params(substream, false);
                if (err < 0)
                        return err;
        }

        info.fragsize = runtime->oss.period_bytes;
        info.fragstotal = runtime->periods;
        if (runtime->oss.prepare) {
                if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
                        info.bytes = runtime->oss.period_bytes * runtime->oss.periods;
                        info.fragments = runtime->oss.periods;
                } else {
                        info.bytes = 0;
                        info.fragments = 0;
                }
        } else {
                if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
                        err = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DELAY, &avail);
                        if (err == -EPIPE || err == -ESTRPIPE || (! err && avail < 0)) {
                                avail = runtime->buffer_size;
                                err = 0;
                                fixup = 0;
                        } else {
                                avail = runtime->buffer_size - avail;
                                fixup = -runtime->oss.buffer_used;
                        }
                } else {
                        err = snd_pcm_oss_capture_position_fixup(substream, &avail);
                        fixup = runtime->oss.buffer_used;
                }
                if (err < 0)
                        return err;
                info.bytes = snd_pcm_oss_bytes(substream, avail) + fixup;
                info.fragments = info.bytes / runtime->oss.period_bytes;
        }

#ifdef OSS_DEBUG
        pcm_dbg(substream->pcm,
                "pcm_oss: space: bytes = %i, fragments = %i, fragstotal = %i, fragsize = %i\n",
                info.bytes, info.fragments, info.fragstotal, info.fragsize);
#endif
        if (copy_to_user(_info, &info, sizeof(info)))
                return -EFAULT;
        return 0;
}

static int snd_pcm_oss_get_mapbuf(struct snd_pcm_oss_file *pcm_oss_file, int stream, struct buffmem_desc __user * _info)
{
        // it won't be probably implemented
        // pr_debug("TODO: snd_pcm_oss_get_mapbuf\n");
        return -EINVAL;
}

static const char *strip_task_path(const char *path)
{
        const char *ptr, *ptrl = NULL;
        for (ptr = path; *ptr; ptr++) {
                if (*ptr == '/')
                        ptrl = ptr + 1;
        }
        return ptrl;
}

static void snd_pcm_oss_look_for_setup(struct snd_pcm *pcm, int stream,
                                      const char *task_name,
                                      struct snd_pcm_oss_setup *rsetup)
{
        struct snd_pcm_oss_setup *setup;

        mutex_lock(&pcm->streams[stream].oss.setup_mutex);
        do {
                for (setup = pcm->streams[stream].oss.setup_list; setup;
                     setup = setup->next) {
                        if (!strcmp(setup->task_name, task_name))
                                goto out;
                }
        } while ((task_name = strip_task_path(task_name)) != NULL);
 out:
        if (setup)
                *rsetup = *setup;
        mutex_unlock(&pcm->streams[stream].oss.setup_mutex);
}

static void snd_pcm_oss_release_substream(struct snd_pcm_substream *substream)
{
        snd_pcm_oss_release_buffers(substream);
        substream->oss.oss = 0;
}

static void snd_pcm_oss_init_substream(struct snd_pcm_substream *substream,
                                       struct snd_pcm_oss_setup *setup,
                                       int minor)
{
        struct snd_pcm_runtime *runtime;

        substream->oss.oss = 1;
        substream->oss.setup = *setup;
        if (setup->nonblock)
                substream->f_flags |= O_NONBLOCK;
        else if (setup->block)
                substream->f_flags &= ~O_NONBLOCK;
        runtime = substream->runtime;
        runtime->oss.params = 1;
        runtime->oss.trigger = 1;
        runtime->oss.rate = 8000;
        mutex_init(&runtime->oss.params_lock);
        switch (SNDRV_MINOR_OSS_DEVICE(minor)) {
        case SNDRV_MINOR_OSS_PCM_8:
                runtime->oss.format = AFMT_U8;
                break;
        case SNDRV_MINOR_OSS_PCM_16:
                runtime->oss.format = AFMT_S16_LE;
                break;
        default:
                runtime->oss.format = AFMT_MU_LAW;
        }
        runtime->oss.channels = 1;
        runtime->oss.fragshift = 0;
        runtime->oss.maxfrags = 0;
        runtime->oss.subdivision = 0;
        substream->pcm_release = snd_pcm_oss_release_substream;
        atomic_set(&runtime->oss.rw_ref, 0);
}

static int snd_pcm_oss_release_file(struct snd_pcm_oss_file *pcm_oss_file)
{
        int cidx;
        if (!pcm_oss_file)
                return 0;
        for (cidx = 0; cidx < 2; ++cidx) {
                struct snd_pcm_substream *substream = pcm_oss_file->streams[cidx];
                if (substream)
                        snd_pcm_release_substream(substream);
        }
        kfree(pcm_oss_file);
        return 0;
}

static int snd_pcm_oss_open_file(struct file *file,
                                 struct snd_pcm *pcm,
                                 struct snd_pcm_oss_file **rpcm_oss_file,
                                 int minor,
                                 struct snd_pcm_oss_setup *setup)
{
        int idx, err;
        struct snd_pcm_oss_file *pcm_oss_file;
        struct snd_pcm_substream *substream;
        fmode_t f_mode = file->f_mode;

        if (rpcm_oss_file)
                *rpcm_oss_file = NULL;

        pcm_oss_file = kzalloc(sizeof(*pcm_oss_file), GFP_KERNEL);
        if (pcm_oss_file == NULL)
                return -ENOMEM;

        if ((f_mode & (FMODE_WRITE|FMODE_READ)) == (FMODE_WRITE|FMODE_READ) &&
            (pcm->info_flags & SNDRV_PCM_INFO_HALF_DUPLEX))
                f_mode = FMODE_WRITE;

        file->f_flags &= ~O_APPEND;
        for (idx = 0; idx < 2; idx++) {
                if (setup[idx].disable)
                        continue;
                if (! pcm->streams[idx].substream_count)
                        continue; /* no matching substream */
                if (idx == SNDRV_PCM_STREAM_PLAYBACK) {
                        if (! (f_mode & FMODE_WRITE))
                                continue;
                } else {
                        if (! (f_mode & FMODE_READ))
                                continue;
                }
                err = snd_pcm_open_substream(pcm, idx, file, &substream);
                if (err < 0) {
                        snd_pcm_oss_release_file(pcm_oss_file);
                        return err;
                }

                pcm_oss_file->streams[idx] = substream;
                snd_pcm_oss_init_substream(substream, &setup[idx], minor);
        }
        
        if (!pcm_oss_file->streams[0] && !pcm_oss_file->streams[1]) {
                snd_pcm_oss_release_file(pcm_oss_file);
                return -EINVAL;
        }

        file->private_data = pcm_oss_file;
        if (rpcm_oss_file)
                *rpcm_oss_file = pcm_oss_file;
        return 0;
}


static int snd_task_name(struct task_struct *task, char *name, size_t size)
{
        unsigned int idx;

        if (snd_BUG_ON(!task || !name || size < 2))
                return -EINVAL;
        for (idx = 0; idx < sizeof(task->comm) && idx + 1 < size; idx++)
                name[idx] = task->comm[idx];
        name[idx] = '\0';
        return 0;
}

static int snd_pcm_oss_open(struct inode *inode, struct file *file)
{
        int err;
        char task_name[32];
        struct snd_pcm *pcm;
        struct snd_pcm_oss_file *pcm_oss_file;
        struct snd_pcm_oss_setup setup[2];
        int nonblock;
        wait_queue_entry_t wait;

        err = nonseekable_open(inode, file);
        if (err < 0)
                return err;

        pcm = snd_lookup_oss_minor_data(iminor(inode),
                                        SNDRV_OSS_DEVICE_TYPE_PCM);
        if (pcm == NULL) {
                err = -ENODEV;
                goto __error1;
        }
        err = snd_card_file_add(pcm->card, file);
        if (err < 0)
                goto __error1;
        if (!try_module_get(pcm->card->module)) {
                err = -EFAULT;
                goto __error2;
        }
        if (snd_task_name(current, task_name, sizeof(task_name)) < 0) {
                err = -EFAULT;
                goto __error;
        }
        memset(setup, 0, sizeof(setup));
        if (file->f_mode & FMODE_WRITE)
                snd_pcm_oss_look_for_setup(pcm, SNDRV_PCM_STREAM_PLAYBACK,
                                           task_name, &setup[0]);
        if (file->f_mode & FMODE_READ)
                snd_pcm_oss_look_for_setup(pcm, SNDRV_PCM_STREAM_CAPTURE,
                                           task_name, &setup[1]);

        nonblock = !!(file->f_flags & O_NONBLOCK);
        if (!nonblock)
                nonblock = nonblock_open;

        init_waitqueue_entry(&wait, current);
        add_wait_queue(&pcm->open_wait, &wait);
        mutex_lock(&pcm->open_mutex);
        while (1) {
                err = snd_pcm_oss_open_file(file, pcm, &pcm_oss_file,
                                            iminor(inode), setup);
                if (err >= 0)
                        break;
                if (err == -EAGAIN) {
                        if (nonblock) {
                                err = -EBUSY;
                                break;
                        }
                } else
                        break;
                set_current_state(TASK_INTERRUPTIBLE);
                mutex_unlock(&pcm->open_mutex);
                schedule();
                mutex_lock(&pcm->open_mutex);
                if (pcm->card->shutdown) {
                        err = -ENODEV;
                        break;
                }
                if (signal_pending(current)) {
                        err = -ERESTARTSYS;
                        break;
                }
        }
        remove_wait_queue(&pcm->open_wait, &wait);
        mutex_unlock(&pcm->open_mutex);
        if (err < 0)
                goto __error;
        snd_card_unref(pcm->card);
        return err;

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

static int snd_pcm_oss_release(struct inode *inode, struct file *file)
{
        struct snd_pcm *pcm;
        struct snd_pcm_substream *substream;
        struct snd_pcm_oss_file *pcm_oss_file;

        pcm_oss_file = file->private_data;
        substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
        if (substream == NULL)
                substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
        if (snd_BUG_ON(!substream))
                return -ENXIO;
        pcm = substream->pcm;
        if (!pcm->card->shutdown)
                snd_pcm_oss_sync(pcm_oss_file);
        mutex_lock(&pcm->open_mutex);
        snd_pcm_oss_release_file(pcm_oss_file);
        mutex_unlock(&pcm->open_mutex);
        wake_up(&pcm->open_wait);
        module_put(pcm->card->module);
        snd_card_file_remove(pcm->card, file);
        return 0;
}

static long snd_pcm_oss_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        struct snd_pcm_oss_file *pcm_oss_file;
        int __user *p = (int __user *)arg;
        int res;

        pcm_oss_file = file->private_data;
        if (cmd == OSS_GETVERSION)
                return put_user(SNDRV_OSS_VERSION, p);
        if (cmd == OSS_ALSAEMULVER)
                return put_user(1, p);
#if IS_REACHABLE(CONFIG_SND_MIXER_OSS)
        if (((cmd >> 8) & 0xff) == 'M') {       /* mixer ioctl - for OSS compatibility */
                struct snd_pcm_substream *substream;
                int idx;
                for (idx = 0; idx < 2; ++idx) {
                        substream = pcm_oss_file->streams[idx];
                        if (substream != NULL)
                                break;
                }
                if (snd_BUG_ON(idx >= 2))
                        return -ENXIO;
                return snd_mixer_oss_ioctl_card(substream->pcm->card, cmd, arg);
        }
#endif
        if (((cmd >> 8) & 0xff) != 'P')
                return -EINVAL;
#ifdef OSS_DEBUG
        pr_debug("pcm_oss: ioctl = 0x%x\n", cmd);
#endif
        switch (cmd) {
        case SNDCTL_DSP_RESET:
                return snd_pcm_oss_reset(pcm_oss_file);
        case SNDCTL_DSP_SYNC:
                return snd_pcm_oss_sync(pcm_oss_file);
        case SNDCTL_DSP_SPEED:
                if (get_user(res, p))
                        return -EFAULT;
                res = snd_pcm_oss_set_rate(pcm_oss_file, res);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SOUND_PCM_READ_RATE:
                res = snd_pcm_oss_get_rate(pcm_oss_file);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SNDCTL_DSP_STEREO:
                if (get_user(res, p))
                        return -EFAULT;
                res = res > 0 ? 2 : 1;
                res = snd_pcm_oss_set_channels(pcm_oss_file, res);
                if (res < 0)
                        return res;
                return put_user(--res, p);
        case SNDCTL_DSP_GETBLKSIZE:
                res = snd_pcm_oss_get_block_size(pcm_oss_file);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SNDCTL_DSP_SETFMT:
                if (get_user(res, p))
                        return -EFAULT;
                res = snd_pcm_oss_set_format(pcm_oss_file, res);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SOUND_PCM_READ_BITS:
                res = snd_pcm_oss_get_format(pcm_oss_file);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SNDCTL_DSP_CHANNELS:
                if (get_user(res, p))
                        return -EFAULT;
                res = snd_pcm_oss_set_channels(pcm_oss_file, res);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SOUND_PCM_READ_CHANNELS:
                res = snd_pcm_oss_get_channels(pcm_oss_file);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SOUND_PCM_WRITE_FILTER:
        case SOUND_PCM_READ_FILTER:
                return -EIO;
        case SNDCTL_DSP_POST:
                return snd_pcm_oss_post(pcm_oss_file);
        case SNDCTL_DSP_SUBDIVIDE:
                if (get_user(res, p))
                        return -EFAULT;
                res = snd_pcm_oss_set_subdivide(pcm_oss_file, res);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SNDCTL_DSP_SETFRAGMENT:
                if (get_user(res, p))
                        return -EFAULT;
                return snd_pcm_oss_set_fragment(pcm_oss_file, res);
        case SNDCTL_DSP_GETFMTS:
                res = snd_pcm_oss_get_formats(pcm_oss_file);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SNDCTL_DSP_GETOSPACE:
        case SNDCTL_DSP_GETISPACE:
                return snd_pcm_oss_get_space(pcm_oss_file,
                        cmd == SNDCTL_DSP_GETISPACE ?
                                SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK,
                        (struct audio_buf_info __user *) arg);
        case SNDCTL_DSP_NONBLOCK:
                return snd_pcm_oss_nonblock(file);
        case SNDCTL_DSP_GETCAPS:
                res = snd_pcm_oss_get_caps(pcm_oss_file);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SNDCTL_DSP_GETTRIGGER:
                res = snd_pcm_oss_get_trigger(pcm_oss_file);
                if (res < 0)
                        return res;
                return put_user(res, p);
        case SNDCTL_DSP_SETTRIGGER:
                if (get_user(res, p))
                        return -EFAULT;
                return snd_pcm_oss_set_trigger(pcm_oss_file, res);
        case SNDCTL_DSP_GETIPTR:
        case SNDCTL_DSP_GETOPTR:
                return snd_pcm_oss_get_ptr(pcm_oss_file,
                        cmd == SNDCTL_DSP_GETIPTR ?
                                SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK,
                        (struct count_info __user *) arg);
        case SNDCTL_DSP_MAPINBUF:
        case SNDCTL_DSP_MAPOUTBUF:
                return snd_pcm_oss_get_mapbuf(pcm_oss_file,
                        cmd == SNDCTL_DSP_MAPINBUF ?
                                SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK,
                        (struct buffmem_desc __user *) arg);
        case SNDCTL_DSP_SETSYNCRO:
                /* stop DMA now.. */
                return 0;
        case SNDCTL_DSP_SETDUPLEX:
                if (snd_pcm_oss_get_caps(pcm_oss_file) & DSP_CAP_DUPLEX)
                        return 0;
                return -EIO;
        case SNDCTL_DSP_GETODELAY:
                res = snd_pcm_oss_get_odelay(pcm_oss_file);
                if (res < 0) {
                        /* it's for sure, some broken apps don't check for error codes */
                        put_user(0, p);
                        return res;
                }
                return put_user(res, p);
        case SNDCTL_DSP_PROFILE:
                return 0;       /* silently ignore */
        default:
                pr_debug("pcm_oss: unknown command = 0x%x\n", cmd);
        }
        return -EINVAL;
}

#ifdef CONFIG_COMPAT
/* all compatible */
static long snd_pcm_oss_ioctl_compat(struct file *file, unsigned int cmd,
                                     unsigned long arg)
{
        /*
         * Everything is compatbile except SNDCTL_DSP_MAPINBUF/SNDCTL_DSP_MAPOUTBUF,
         * which are not implemented for the native case either
         */
        return snd_pcm_oss_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
}
#else
#define snd_pcm_oss_ioctl_compat        NULL
#endif

static ssize_t snd_pcm_oss_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
        struct snd_pcm_oss_file *pcm_oss_file;
        struct snd_pcm_substream *substream;

        pcm_oss_file = file->private_data;
        substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
        if (substream == NULL)
                return -ENXIO;
        substream->f_flags = file->f_flags & O_NONBLOCK;
#ifndef OSS_DEBUG
        return snd_pcm_oss_read1(substream, buf, count);
#else
        {
                ssize_t res = snd_pcm_oss_read1(substream, buf, count);
                pcm_dbg(substream->pcm,
                        "pcm_oss: read %li bytes (returned %li bytes)\n",
                        (long)count, (long)res);
                return res;
        }
#endif
}

static ssize_t snd_pcm_oss_write(struct file *file, const char __user *buf, size_t count, loff_t *offset)
{
        struct snd_pcm_oss_file *pcm_oss_file;
        struct snd_pcm_substream *substream;
        long result;

        pcm_oss_file = file->private_data;
        substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
        if (substream == NULL)
                return -ENXIO;
        substream->f_flags = file->f_flags & O_NONBLOCK;
        result = snd_pcm_oss_write1(substream, buf, count);
#ifdef OSS_DEBUG
        pcm_dbg(substream->pcm, "pcm_oss: write %li bytes (wrote %li bytes)\n",
               (long)count, (long)result);
#endif
        return result;
}

static int snd_pcm_oss_playback_ready(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        if (atomic_read(&substream->mmap_count))
                return runtime->oss.prev_hw_ptr_period !=
                                                get_hw_ptr_period(runtime);
        else
                return snd_pcm_playback_avail(runtime) >=
                                                runtime->oss.period_frames;
}

static int snd_pcm_oss_capture_ready(struct snd_pcm_substream *substream)
{
        struct snd_pcm_runtime *runtime = substream->runtime;
        if (atomic_read(&substream->mmap_count))
                return runtime->oss.prev_hw_ptr_period !=
                                                get_hw_ptr_period(runtime);
        else
                return snd_pcm_capture_avail(runtime) >=
                                                runtime->oss.period_frames;
}

static __poll_t snd_pcm_oss_poll(struct file *file, poll_table * wait)
{
        struct snd_pcm_oss_file *pcm_oss_file;
        __poll_t mask;
        struct snd_pcm_substream *psubstream = NULL, *csubstream = NULL;
        
        pcm_oss_file = file->private_data;

        psubstream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
        csubstream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];

        mask = 0;
        if (psubstream != NULL) {
                struct snd_pcm_runtime *runtime = psubstream->runtime;
                poll_wait(file, &runtime->sleep, wait);
                snd_pcm_stream_lock_irq(psubstream);
                if (runtime->status->state != SNDRV_PCM_STATE_DRAINING &&
                    (runtime->status->state != SNDRV_PCM_STATE_RUNNING ||
                     snd_pcm_oss_playback_ready(psubstream)))
                        mask |= EPOLLOUT | EPOLLWRNORM;
                snd_pcm_stream_unlock_irq(psubstream);
        }
        if (csubstream != NULL) {
                struct snd_pcm_runtime *runtime = csubstream->runtime;
                snd_pcm_state_t ostate;
                poll_wait(file, &runtime->sleep, wait);
                snd_pcm_stream_lock_irq(csubstream);
                ostate = runtime->status->state;
                if (ostate != SNDRV_PCM_STATE_RUNNING ||
                    snd_pcm_oss_capture_ready(csubstream))
                        mask |= EPOLLIN | EPOLLRDNORM;
                snd_pcm_stream_unlock_irq(csubstream);
                if (ostate != SNDRV_PCM_STATE_RUNNING && runtime->oss.trigger) {
                        struct snd_pcm_oss_file ofile;
                        memset(&ofile, 0, sizeof(ofile));
                        ofile.streams[SNDRV_PCM_STREAM_CAPTURE] = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
                        runtime->oss.trigger = 0;
                        snd_pcm_oss_set_trigger(&ofile, PCM_ENABLE_INPUT);
                }
        }

        return mask;
}

static int snd_pcm_oss_mmap(struct file *file, struct vm_area_struct *area)
{
        struct snd_pcm_oss_file *pcm_oss_file;
        struct snd_pcm_substream *substream = NULL;
        struct snd_pcm_runtime *runtime;
        int err;

#ifdef OSS_DEBUG
        pr_debug("pcm_oss: mmap begin\n");
#endif
        pcm_oss_file = file->private_data;
        switch ((area->vm_flags & (VM_READ | VM_WRITE))) {
        case VM_READ | VM_WRITE:
                substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
                if (substream)
                        break;
                fallthrough;
        case VM_READ:
                substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
                break;
        case VM_WRITE:
                substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
                break;
        default:
                return -EINVAL;
        }
        /* set VM_READ access as well to fix memset() routines that do
           reads before writes (to improve performance) */
        area->vm_flags |= VM_READ;
        if (substream == NULL)
                return -ENXIO;
        runtime = substream->runtime;
        if (!(runtime->info & SNDRV_PCM_INFO_MMAP_VALID))
                return -EIO;
        if (runtime->info & SNDRV_PCM_INFO_INTERLEAVED)
                runtime->access = SNDRV_PCM_ACCESS_MMAP_INTERLEAVED;
        else
                return -EIO;
        
        if (runtime->oss.params) {
                /* use mutex_trylock() for params_lock for avoiding a deadlock
                 * between mmap_lock and params_lock taken by
                 * copy_from/to_user() in snd_pcm_oss_write/read()
                 */
                err = snd_pcm_oss_change_params(substream, true);
                if (err < 0)
                        return err;
        }
#ifdef CONFIG_SND_PCM_OSS_PLUGINS
        if (runtime->oss.plugin_first != NULL)
                return -EIO;
#endif

        if (area->vm_pgoff != 0)
                return -EINVAL;

        err = snd_pcm_mmap_data(substream, file, area);
        if (err < 0)
                return err;
        runtime->oss.mmap_bytes = area->vm_end - area->vm_start;
        runtime->silence_threshold = 0;
        runtime->silence_size = 0;
#ifdef OSS_DEBUG
        pr_debug("pcm_oss: mmap ok, bytes = 0x%x\n",
               runtime->oss.mmap_bytes);
#endif
        /* In mmap mode we never stop */
        runtime->stop_threshold = runtime->boundary;

        return 0;
}

#ifdef CONFIG_SND_VERBOSE_PROCFS
/*
 *  /proc interface
 */

static void snd_pcm_oss_proc_read(struct snd_info_entry *entry,
                                  struct snd_info_buffer *buffer)
{
        struct snd_pcm_str *pstr = entry->private_data;
        struct snd_pcm_oss_setup *setup = pstr->oss.setup_list;
        mutex_lock(&pstr->oss.setup_mutex);
        while (setup) {
                snd_iprintf(buffer, "%s %u %u%s%s%s%s%s%s\n",
                            setup->task_name,
                            setup->periods,
                            setup->period_size,
                            setup->disable ? " disable" : "",
                            setup->direct ? " direct" : "",
                            setup->block ? " block" : "",
                            setup->nonblock ? " non-block" : "",
                            setup->partialfrag ? " partial-frag" : "",
                            setup->nosilence ? " no-silence" : "");
                setup = setup->next;
        }
        mutex_unlock(&pstr->oss.setup_mutex);
}

static void snd_pcm_oss_proc_free_setup_list(struct snd_pcm_str * pstr)
{
        struct snd_pcm_oss_setup *setup, *setupn;

        for (setup = pstr->oss.setup_list, pstr->oss.setup_list = NULL;
             setup; setup = setupn) {
                setupn = setup->next;
                kfree(setup->task_name);
                kfree(setup);
        }
        pstr->oss.setup_list = NULL;
}

static void snd_pcm_oss_proc_write(struct snd_info_entry *entry,
                                   struct snd_info_buffer *buffer)
{
        struct snd_pcm_str *pstr = entry->private_data;