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aloop.c
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aloop.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Loopback soundcard
*
* Original code:
* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
*
* More accurate positioning and full-duplex support:
* Copyright (c) Ahmet İnan <ainan at mathematik.uni-freiburg.de>
*
* Major (almost complete) rewrite:
* Copyright (c) by Takashi Iwai <tiwai@suse.de>
*
* A next major update in 2010 (separate timers for playback and capture):
* Copyright (c) Jaroslav Kysela <perex@perex.cz>
*/
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/wait.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/info.h>
#include <sound/initval.h>
#include <sound/timer.h>
MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
MODULE_DESCRIPTION("A loopback soundcard");
MODULE_LICENSE("GPL");
#define MAX_PCM_SUBSTREAMS 8
static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX; /* Index 0-MAX */
static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR; /* ID for this card */
static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
static int pcm_notify[SNDRV_CARDS];
static char *timer_source[SNDRV_CARDS];
module_param_array(index, int, NULL, 0444);
MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
module_param_array(id, charp, NULL, 0444);
MODULE_PARM_DESC(id, "ID string for loopback soundcard.");
module_param_array(enable, bool, NULL, 0444);
MODULE_PARM_DESC(enable, "Enable this loopback soundcard.");
module_param_array(pcm_substreams, int, NULL, 0444);
MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
module_param_array(pcm_notify, int, NULL, 0444);
MODULE_PARM_DESC(pcm_notify, "Break capture when PCM format/rate/channels changes.");
module_param_array(timer_source, charp, NULL, 0444);
MODULE_PARM_DESC(timer_source, "Sound card name or number and device/subdevice number of timer to be used. Empty string for jiffies timer [default].");
#define NO_PITCH 100000
#define CABLE_VALID_PLAYBACK BIT(SNDRV_PCM_STREAM_PLAYBACK)
#define CABLE_VALID_CAPTURE BIT(SNDRV_PCM_STREAM_CAPTURE)
#define CABLE_VALID_BOTH (CABLE_VALID_PLAYBACK | CABLE_VALID_CAPTURE)
struct loopback_cable;
struct loopback_pcm;
struct loopback_ops {
/* optional
* call in loopback->cable_lock
*/
int (*open)(struct loopback_pcm *dpcm);
/* required
* call in cable->lock
*/
int (*start)(struct loopback_pcm *dpcm);
/* required
* call in cable->lock
*/
int (*stop)(struct loopback_pcm *dpcm);
/* optional */
int (*stop_sync)(struct loopback_pcm *dpcm);
/* optional */
int (*close_substream)(struct loopback_pcm *dpcm);
/* optional
* call in loopback->cable_lock
*/
int (*close_cable)(struct loopback_pcm *dpcm);
/* optional
* call in cable->lock
*/
unsigned int (*pos_update)(struct loopback_cable *cable);
/* optional */
void (*dpcm_info)(struct loopback_pcm *dpcm,
struct snd_info_buffer *buffer);
};
struct loopback_cable {
spinlock_t lock;
struct loopback_pcm *streams[2];
struct snd_pcm_hardware hw;
/* flags */
unsigned int valid;
unsigned int running;
unsigned int pause;
/* timer specific */
const struct loopback_ops *ops;
/* If sound timer is used */
struct {
int stream;
struct snd_timer_id id;
struct work_struct event_work;
struct snd_timer_instance *instance;
} snd_timer;
};
struct loopback_setup {
unsigned int notify: 1;
unsigned int rate_shift;
snd_pcm_format_t format;
unsigned int rate;
snd_pcm_access_t access;
unsigned int channels;
struct snd_ctl_elem_id active_id;
struct snd_ctl_elem_id format_id;
struct snd_ctl_elem_id rate_id;
struct snd_ctl_elem_id channels_id;
struct snd_ctl_elem_id access_id;
};
struct loopback {
struct snd_card *card;
struct mutex cable_lock;
struct loopback_cable *cables[MAX_PCM_SUBSTREAMS][2];
struct snd_pcm *pcm[2];
struct loopback_setup setup[MAX_PCM_SUBSTREAMS][2];
const char *timer_source;
};
struct loopback_pcm {
struct loopback *loopback;
struct snd_pcm_substream *substream;
struct loopback_cable *cable;
unsigned int pcm_buffer_size;
unsigned int buf_pos; /* position in buffer */
unsigned int silent_size;
/* PCM parameters */
unsigned int pcm_period_size;
unsigned int pcm_bps; /* bytes per second */
unsigned int pcm_salign; /* bytes per sample * channels */
unsigned int pcm_rate_shift; /* rate shift value */
/* flags */
unsigned int period_update_pending :1;
/* timer stuff */
unsigned int irq_pos; /* fractional IRQ position in jiffies
* ticks
*/
unsigned int period_size_frac; /* period size in jiffies ticks */
unsigned int last_drift;
unsigned long last_jiffies;
/* If jiffies timer is used */
struct timer_list timer;
/* size of per channel buffer in case of non-interleaved access */
unsigned int channel_buf_n;
};
static struct platform_device *devices[SNDRV_CARDS];
static inline unsigned int byte_pos(struct loopback_pcm *dpcm, unsigned int x)
{
if (dpcm->pcm_rate_shift == NO_PITCH) {
x /= HZ;
} else {
x = div_u64(NO_PITCH * (unsigned long long)x,
HZ * (unsigned long long)dpcm->pcm_rate_shift);
}
return x - (x % dpcm->pcm_salign);
}
static inline unsigned int frac_pos(struct loopback_pcm *dpcm, unsigned int x)
{
if (dpcm->pcm_rate_shift == NO_PITCH) { /* no pitch */
return x * HZ;
} else {
x = div_u64(dpcm->pcm_rate_shift * (unsigned long long)x * HZ,
NO_PITCH);
}
return x;
}
static inline struct loopback_setup *get_setup(struct loopback_pcm *dpcm)
{
int device = dpcm->substream->pstr->pcm->device;
if (dpcm->substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
device ^= 1;
return &dpcm->loopback->setup[dpcm->substream->number][device];
}
static inline unsigned int get_notify(struct loopback_pcm *dpcm)
{
return get_setup(dpcm)->notify;
}
static inline unsigned int get_rate_shift(struct loopback_pcm *dpcm)
{
return get_setup(dpcm)->rate_shift;
}
/* call in cable->lock */
static int loopback_jiffies_timer_start(struct loopback_pcm *dpcm)
{
unsigned long tick;
unsigned int rate_shift = get_rate_shift(dpcm);
if (rate_shift != dpcm->pcm_rate_shift) {
dpcm->pcm_rate_shift = rate_shift;
dpcm->period_size_frac = frac_pos(dpcm, dpcm->pcm_period_size);
}
if (dpcm->period_size_frac <= dpcm->irq_pos) {
dpcm->irq_pos %= dpcm->period_size_frac;
dpcm->period_update_pending = 1;
}
tick = dpcm->period_size_frac - dpcm->irq_pos;
tick = DIV_ROUND_UP(tick, dpcm->pcm_bps);
mod_timer(&dpcm->timer, jiffies + tick);
return 0;
}
/* call in cable->lock */
static int loopback_snd_timer_start(struct loopback_pcm *dpcm)
{
struct loopback_cable *cable = dpcm->cable;
int err;
/* Loopback device has to use same period as timer card. Therefore
* wake up for each snd_pcm_period_elapsed() call of timer card.
*/
err = snd_timer_start(cable->snd_timer.instance, 1);
if (err < 0) {
/* do not report error if trying to start but already
* running. For example called by opposite substream
* of the same cable
*/
if (err == -EBUSY)
return 0;
pcm_err(dpcm->substream->pcm,
"snd_timer_start(%d,%d,%d) failed with %d",
cable->snd_timer.id.card,
cable->snd_timer.id.device,
cable->snd_timer.id.subdevice,
err);
}
return err;
}
/* call in cable->lock */
static inline int loopback_jiffies_timer_stop(struct loopback_pcm *dpcm)
{
del_timer(&dpcm->timer);
dpcm->timer.expires = 0;
return 0;
}
/* call in cable->lock */
static int loopback_snd_timer_stop(struct loopback_pcm *dpcm)
{
struct loopback_cable *cable = dpcm->cable;
int err;
/* only stop if both devices (playback and capture) are not running */
if (cable->running ^ cable->pause)
return 0;
err = snd_timer_stop(cable->snd_timer.instance);
if (err < 0) {
pcm_err(dpcm->substream->pcm,
"snd_timer_stop(%d,%d,%d) failed with %d",
cable->snd_timer.id.card,
cable->snd_timer.id.device,
cable->snd_timer.id.subdevice,
err);
}
return err;
}
static inline int loopback_jiffies_timer_stop_sync(struct loopback_pcm *dpcm)
{
del_timer_sync(&dpcm->timer);
return 0;
}
/* call in loopback->cable_lock */
static int loopback_snd_timer_close_cable(struct loopback_pcm *dpcm)
{
struct loopback_cable *cable = dpcm->cable;
/* snd_timer was not opened */
if (!cable->snd_timer.instance)
return 0;
/* will only be called from free_cable() when other stream was
* already closed. Other stream cannot be reopened as long as
* loopback->cable_lock is locked. Therefore no need to lock
* cable->lock;
*/
snd_timer_close(cable->snd_timer.instance);
/* wait till drain work has finished if requested */
cancel_work_sync(&cable->snd_timer.event_work);
snd_timer_instance_free(cable->snd_timer.instance);
memset(&cable->snd_timer, 0, sizeof(cable->snd_timer));
return 0;
}
static bool is_access_interleaved(snd_pcm_access_t access)
{
switch (access) {
case SNDRV_PCM_ACCESS_MMAP_INTERLEAVED:
case SNDRV_PCM_ACCESS_RW_INTERLEAVED:
return true;
default:
return false;
}
};
static int loopback_check_format(struct loopback_cable *cable, int stream)
{
struct snd_pcm_runtime *runtime, *cruntime;
struct loopback_setup *setup;
struct snd_card *card;
int check;
if (cable->valid != CABLE_VALID_BOTH) {
if (stream == SNDRV_PCM_STREAM_PLAYBACK)
goto __notify;
return 0;
}
runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
substream->runtime;
cruntime = cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
substream->runtime;
check = runtime->format != cruntime->format ||
runtime->rate != cruntime->rate ||
runtime->channels != cruntime->channels ||
is_access_interleaved(runtime->access) !=
is_access_interleaved(cruntime->access);
if (!check)
return 0;
if (stream == SNDRV_PCM_STREAM_CAPTURE) {
return -EIO;
} else {
snd_pcm_stop(cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
substream, SNDRV_PCM_STATE_DRAINING);
__notify:
runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
substream->runtime;
setup = get_setup(cable->streams[SNDRV_PCM_STREAM_PLAYBACK]);
card = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->loopback->card;
if (setup->format != runtime->format) {
snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
&setup->format_id);
setup->format = runtime->format;
}
if (setup->rate != runtime->rate) {
snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
&setup->rate_id);
setup->rate = runtime->rate;
}
if (setup->channels != runtime->channels) {
snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
&setup->channels_id);
setup->channels = runtime->channels;
}
if (is_access_interleaved(setup->access) !=
is_access_interleaved(runtime->access)) {
snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
&setup->access_id);
setup->access = runtime->access;
}
}
return 0;
}
static void loopback_active_notify(struct loopback_pcm *dpcm)
{
snd_ctl_notify(dpcm->loopback->card,
SNDRV_CTL_EVENT_MASK_VALUE,
&get_setup(dpcm)->active_id);
}
static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct loopback_pcm *dpcm = runtime->private_data;
struct loopback_cable *cable = dpcm->cable;
int err = 0, stream = 1 << substream->stream;
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
err = loopback_check_format(cable, substream->stream);
if (err < 0)
return err;
dpcm->last_jiffies = jiffies;
dpcm->pcm_rate_shift = 0;
dpcm->last_drift = 0;
spin_lock(&cable->lock);
cable->running |= stream;
cable->pause &= ~stream;
err = cable->ops->start(dpcm);
spin_unlock(&cable->lock);
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
loopback_active_notify(dpcm);
break;
case SNDRV_PCM_TRIGGER_STOP:
spin_lock(&cable->lock);
cable->running &= ~stream;
cable->pause &= ~stream;
err = cable->ops->stop(dpcm);
spin_unlock(&cable->lock);
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
loopback_active_notify(dpcm);
break;
case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
case SNDRV_PCM_TRIGGER_SUSPEND:
spin_lock(&cable->lock);
cable->pause |= stream;
err = cable->ops->stop(dpcm);
spin_unlock(&cable->lock);
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
loopback_active_notify(dpcm);
break;
case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
case SNDRV_PCM_TRIGGER_RESUME:
spin_lock(&cable->lock);
dpcm->last_jiffies = jiffies;
cable->pause &= ~stream;
err = cable->ops->start(dpcm);
spin_unlock(&cable->lock);
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
loopback_active_notify(dpcm);
break;
default:
return -EINVAL;
}
return err;
}
static void params_change(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct loopback_pcm *dpcm = runtime->private_data;
struct loopback_cable *cable = dpcm->cable;
cable->hw.formats = pcm_format_to_bits(runtime->format);
cable->hw.rate_min = runtime->rate;
cable->hw.rate_max = runtime->rate;
cable->hw.channels_min = runtime->channels;
cable->hw.channels_max = runtime->channels;
if (cable->snd_timer.instance) {
cable->hw.period_bytes_min =
frames_to_bytes(runtime, runtime->period_size);
cable->hw.period_bytes_max = cable->hw.period_bytes_min;
}
}
static int loopback_prepare(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct loopback_pcm *dpcm = runtime->private_data;
struct loopback_cable *cable = dpcm->cable;
int err, bps, salign;
if (cable->ops->stop_sync) {
err = cable->ops->stop_sync(dpcm);
if (err < 0)
return err;
}
salign = (snd_pcm_format_physical_width(runtime->format) *
runtime->channels) / 8;
bps = salign * runtime->rate;
if (bps <= 0 || salign <= 0)
return -EINVAL;
dpcm->buf_pos = 0;
dpcm->pcm_buffer_size = frames_to_bytes(runtime, runtime->buffer_size);
dpcm->channel_buf_n = dpcm->pcm_buffer_size / runtime->channels;
if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
/* clear capture buffer */
dpcm->silent_size = dpcm->pcm_buffer_size;
snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
runtime->buffer_size * runtime->channels);
}
dpcm->irq_pos = 0;
dpcm->period_update_pending = 0;
dpcm->pcm_bps = bps;
dpcm->pcm_salign = salign;
dpcm->pcm_period_size = frames_to_bytes(runtime, runtime->period_size);
mutex_lock(&dpcm->loopback->cable_lock);
if (!(cable->valid & ~(1 << substream->stream)) ||
(get_setup(dpcm)->notify &&
substream->stream == SNDRV_PCM_STREAM_PLAYBACK))
params_change(substream);
cable->valid |= 1 << substream->stream;
mutex_unlock(&dpcm->loopback->cable_lock);
return 0;
}
static void clear_capture_buf(struct loopback_pcm *dpcm, unsigned int bytes)
{
struct snd_pcm_runtime *runtime = dpcm->substream->runtime;
char *dst = runtime->dma_area;
unsigned int dst_off = dpcm->buf_pos;
if (dpcm->silent_size >= dpcm->pcm_buffer_size)
return;
if (dpcm->silent_size + bytes > dpcm->pcm_buffer_size)
bytes = dpcm->pcm_buffer_size - dpcm->silent_size;
for (;;) {
unsigned int size = bytes;
if (dst_off + size > dpcm->pcm_buffer_size)
size = dpcm->pcm_buffer_size - dst_off;
snd_pcm_format_set_silence(runtime->format, dst + dst_off,
bytes_to_frames(runtime, size) *
runtime->channels);
dpcm->silent_size += size;
bytes -= size;
if (!bytes)
break;
dst_off = 0;
}
}
static void copy_play_buf_part_n(struct loopback_pcm *play, struct loopback_pcm *capt,
unsigned int size, unsigned int src_off, unsigned int dst_off)
{
unsigned int channels = capt->substream->runtime->channels;
unsigned int size_p_ch = size / channels;
unsigned int src_off_ch = src_off / channels;
unsigned int dst_off_ch = dst_off / channels;
int i;
for (i = 0; i < channels; i++) {
memcpy(capt->substream->runtime->dma_area + capt->channel_buf_n * i + dst_off_ch,
play->substream->runtime->dma_area + play->channel_buf_n * i + src_off_ch,
size_p_ch);
}
}
static void copy_play_buf(struct loopback_pcm *play,
struct loopback_pcm *capt,
unsigned int bytes)
{
struct snd_pcm_runtime *runtime = play->substream->runtime;
char *src = runtime->dma_area;
char *dst = capt->substream->runtime->dma_area;
unsigned int src_off = play->buf_pos;
unsigned int dst_off = capt->buf_pos;
unsigned int clear_bytes = 0;
/* check if playback is draining, trim the capture copy size
* when our pointer is at the end of playback ring buffer */
if (runtime->state == SNDRV_PCM_STATE_DRAINING &&
snd_pcm_playback_hw_avail(runtime) < runtime->buffer_size) {
snd_pcm_uframes_t appl_ptr, appl_ptr1, diff;
appl_ptr = appl_ptr1 = runtime->control->appl_ptr;
appl_ptr1 -= appl_ptr1 % runtime->buffer_size;
appl_ptr1 += play->buf_pos / play->pcm_salign;
if (appl_ptr < appl_ptr1)
appl_ptr1 -= runtime->buffer_size;
diff = (appl_ptr - appl_ptr1) * play->pcm_salign;
if (diff < bytes) {
clear_bytes = bytes - diff;
bytes = diff;
}
}
for (;;) {
unsigned int size = bytes;
if (src_off + size > play->pcm_buffer_size)
size = play->pcm_buffer_size - src_off;
if (dst_off + size > capt->pcm_buffer_size)
size = capt->pcm_buffer_size - dst_off;
if (!is_access_interleaved(runtime->access))
copy_play_buf_part_n(play, capt, size, src_off, dst_off);
else
memcpy(dst + dst_off, src + src_off, size);
capt->silent_size = 0;
bytes -= size;
if (!bytes)
break;
src_off = (src_off + size) % play->pcm_buffer_size;
dst_off = (dst_off + size) % capt->pcm_buffer_size;
}
if (clear_bytes > 0) {
clear_capture_buf(capt, clear_bytes);
capt->silent_size = 0;
}
}
static inline unsigned int bytepos_delta(struct loopback_pcm *dpcm,
unsigned int jiffies_delta)
{
unsigned long last_pos;
unsigned int delta;
last_pos = byte_pos(dpcm, dpcm->irq_pos);
dpcm->irq_pos += jiffies_delta * dpcm->pcm_bps;
delta = byte_pos(dpcm, dpcm->irq_pos) - last_pos;
if (delta >= dpcm->last_drift)
delta -= dpcm->last_drift;
dpcm->last_drift = 0;
if (dpcm->irq_pos >= dpcm->period_size_frac) {
dpcm->irq_pos %= dpcm->period_size_frac;
dpcm->period_update_pending = 1;
}
return delta;
}
static inline void bytepos_finish(struct loopback_pcm *dpcm,
unsigned int delta)
{
dpcm->buf_pos += delta;
dpcm->buf_pos %= dpcm->pcm_buffer_size;
}
/* call in cable->lock */
static unsigned int loopback_jiffies_timer_pos_update
(struct loopback_cable *cable)
{
struct loopback_pcm *dpcm_play =
cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
struct loopback_pcm *dpcm_capt =
cable->streams[SNDRV_PCM_STREAM_CAPTURE];
unsigned long delta_play = 0, delta_capt = 0, cur_jiffies;
unsigned int running, count1, count2;
cur_jiffies = jiffies;
running = cable->running ^ cable->pause;
if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
delta_play = cur_jiffies - dpcm_play->last_jiffies;
dpcm_play->last_jiffies += delta_play;
}
if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
delta_capt = cur_jiffies - dpcm_capt->last_jiffies;
dpcm_capt->last_jiffies += delta_capt;
}
if (delta_play == 0 && delta_capt == 0)
goto unlock;
if (delta_play > delta_capt) {
count1 = bytepos_delta(dpcm_play, delta_play - delta_capt);
bytepos_finish(dpcm_play, count1);
delta_play = delta_capt;
} else if (delta_play < delta_capt) {
count1 = bytepos_delta(dpcm_capt, delta_capt - delta_play);
clear_capture_buf(dpcm_capt, count1);
bytepos_finish(dpcm_capt, count1);
delta_capt = delta_play;
}
if (delta_play == 0 && delta_capt == 0)
goto unlock;
/* note delta_capt == delta_play at this moment */
count1 = bytepos_delta(dpcm_play, delta_play);
count2 = bytepos_delta(dpcm_capt, delta_capt);
if (count1 < count2) {
dpcm_capt->last_drift = count2 - count1;
count1 = count2;
} else if (count1 > count2) {
dpcm_play->last_drift = count1 - count2;
}
copy_play_buf(dpcm_play, dpcm_capt, count1);
bytepos_finish(dpcm_play, count1);
bytepos_finish(dpcm_capt, count1);
unlock:
return running;
}
static void loopback_jiffies_timer_function(struct timer_list *t)
{
struct loopback_pcm *dpcm = from_timer(dpcm, t, timer);
unsigned long flags;
spin_lock_irqsave(&dpcm->cable->lock, flags);
if (loopback_jiffies_timer_pos_update(dpcm->cable) &
(1 << dpcm->substream->stream)) {
loopback_jiffies_timer_start(dpcm);
if (dpcm->period_update_pending) {
dpcm->period_update_pending = 0;
spin_unlock_irqrestore(&dpcm->cable->lock, flags);
/* need to unlock before calling below */
snd_pcm_period_elapsed(dpcm->substream);
return;
}
}
spin_unlock_irqrestore(&dpcm->cable->lock, flags);
}
/* call in cable->lock */
static int loopback_snd_timer_check_resolution(struct snd_pcm_runtime *runtime,
unsigned long resolution)
{
if (resolution != runtime->timer_resolution) {
struct loopback_pcm *dpcm = runtime->private_data;
struct loopback_cable *cable = dpcm->cable;
/* Worst case estimation of possible values for resolution
* resolution <= (512 * 1024) frames / 8kHz in nsec
* resolution <= 65.536.000.000 nsec
*
* period_size <= 65.536.000.000 nsec / 1000nsec/usec * 192kHz +
* 500.000
* period_size <= 12.582.912.000.000 <64bit
* / 1.000.000 usec/sec
*/
snd_pcm_uframes_t period_size_usec =
resolution / 1000 * runtime->rate;
/* round to nearest sample rate */
snd_pcm_uframes_t period_size =
(period_size_usec + 500 * 1000) / (1000 * 1000);
pcm_err(dpcm->substream->pcm,
"Period size (%lu frames) of loopback device is not corresponding to timer resolution (%lu nsec = %lu frames) of card timer %d,%d,%d. Use period size of %lu frames for loopback device.",
runtime->period_size, resolution, period_size,
cable->snd_timer.id.card,
cable->snd_timer.id.device,
cable->snd_timer.id.subdevice,
period_size);
return -EINVAL;
}
return 0;
}
static void loopback_snd_timer_period_elapsed(struct loopback_cable *cable,
int event,
unsigned long resolution)
{
struct loopback_pcm *dpcm_play, *dpcm_capt;
struct snd_pcm_substream *substream_play, *substream_capt;
struct snd_pcm_runtime *valid_runtime;
unsigned int running, elapsed_bytes;
unsigned long flags;
spin_lock_irqsave(&cable->lock, flags);
running = cable->running ^ cable->pause;
/* no need to do anything if no stream is running */
if (!running) {
spin_unlock_irqrestore(&cable->lock, flags);
return;
}
dpcm_play = cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
dpcm_capt = cable->streams[SNDRV_PCM_STREAM_CAPTURE];
if (event == SNDRV_TIMER_EVENT_MSTOP) {
if (!dpcm_play ||
dpcm_play->substream->runtime->state !=
SNDRV_PCM_STATE_DRAINING) {
spin_unlock_irqrestore(&cable->lock, flags);
return;
}
}
substream_play = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
dpcm_play->substream : NULL;
substream_capt = (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) ?
dpcm_capt->substream : NULL;
valid_runtime = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
dpcm_play->substream->runtime :
dpcm_capt->substream->runtime;
/* resolution is only valid for SNDRV_TIMER_EVENT_TICK events */
if (event == SNDRV_TIMER_EVENT_TICK) {
/* The hardware rules guarantee that playback and capture period
* are the same. Therefore only one device has to be checked
* here.
*/
if (loopback_snd_timer_check_resolution(valid_runtime,
resolution) < 0) {
spin_unlock_irqrestore(&cable->lock, flags);
if (substream_play)
snd_pcm_stop_xrun(substream_play);
if (substream_capt)
snd_pcm_stop_xrun(substream_capt);
return;
}
}
elapsed_bytes = frames_to_bytes(valid_runtime,
valid_runtime->period_size);
/* The same timer interrupt is used for playback and capture device */
if ((running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) &&
(running & (1 << SNDRV_PCM_STREAM_CAPTURE))) {
copy_play_buf(dpcm_play, dpcm_capt, elapsed_bytes);
bytepos_finish(dpcm_play, elapsed_bytes);
bytepos_finish(dpcm_capt, elapsed_bytes);
} else if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
bytepos_finish(dpcm_play, elapsed_bytes);
} else if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
clear_capture_buf(dpcm_capt, elapsed_bytes);
bytepos_finish(dpcm_capt, elapsed_bytes);
}
spin_unlock_irqrestore(&cable->lock, flags);
if (substream_play)
snd_pcm_period_elapsed(substream_play);
if (substream_capt)
snd_pcm_period_elapsed(substream_capt);
}
static void loopback_snd_timer_function(struct snd_timer_instance *timeri,
unsigned long resolution,
unsigned long ticks)
{
struct loopback_cable *cable = timeri->callback_data;
loopback_snd_timer_period_elapsed(cable, SNDRV_TIMER_EVENT_TICK,
resolution);
}
static void loopback_snd_timer_work(struct work_struct *work)
{
struct loopback_cable *cable;
cable = container_of(work, struct loopback_cable, snd_timer.event_work);
loopback_snd_timer_period_elapsed(cable, SNDRV_TIMER_EVENT_MSTOP, 0);
}
static void loopback_snd_timer_event(struct snd_timer_instance *timeri,
int event,
struct timespec64 *tstamp,
unsigned long resolution)
{
/* Do not lock cable->lock here because timer->lock is already hold.
* There are other functions which first lock cable->lock and than
* timer->lock e.g.
* loopback_trigger()
* spin_lock(&cable->lock)
* loopback_snd_timer_start()
* snd_timer_start()
* spin_lock(&timer->lock)
* Therefore when using the oposit order of locks here it could result
* in a deadlock.
*/
if (event == SNDRV_TIMER_EVENT_MSTOP) {
struct loopback_cable *cable = timeri->callback_data;
/* sound card of the timer was stopped. Therefore there will not
* be any further timer callbacks. Due to this forward audio
* data from here if in draining state. When still in running
* state the streaming will be aborted by the usual timeout. It
* should not be aborted here because may be the timer sound
* card does only a recovery and the timer is back soon.
* This work triggers loopback_snd_timer_work()
*/
schedule_work(&cable->snd_timer.event_work);
}
}
static void loopback_jiffies_timer_dpcm_info(struct loopback_pcm *dpcm,
struct snd_info_buffer *buffer)
{
snd_iprintf(buffer, " update_pending:\t%u\n",
dpcm->period_update_pending);
snd_iprintf(buffer, " irq_pos:\t\t%u\n", dpcm->irq_pos);
snd_iprintf(buffer, " period_frac:\t%u\n", dpcm->period_size_frac);
snd_iprintf(buffer, " last_jiffies:\t%lu (%lu)\n",
dpcm->last_jiffies, jiffies);
snd_iprintf(buffer, " timer_expires:\t%lu\n", dpcm->timer.expires);
}
static void loopback_snd_timer_dpcm_info(struct loopback_pcm *dpcm,
struct snd_info_buffer *buffer)
{
struct loopback_cable *cable = dpcm->cable;
snd_iprintf(buffer, " sound timer:\thw:%d,%d,%d\n",
cable->snd_timer.id.card,
cable->snd_timer.id.device,
cable->snd_timer.id.subdevice);
snd_iprintf(buffer, " timer open:\t\t%s\n",
(cable->snd_timer.stream == SNDRV_PCM_STREAM_CAPTURE) ?
"capture" : "playback");
}
static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct loopback_pcm *dpcm = runtime->private_data;
snd_pcm_uframes_t pos;
spin_lock(&dpcm->cable->lock);
if (dpcm->cable->ops->pos_update)
dpcm->cable->ops->pos_update(dpcm->cable);
pos = dpcm->buf_pos;
spin_unlock(&dpcm->cable->lock);
return bytes_to_frames(runtime, pos);
}
static const struct snd_pcm_hardware loopback_pcm_hardware =
{
.info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP |
SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_PAUSE |
SNDRV_PCM_INFO_RESUME | SNDRV_PCM_INFO_NONINTERLEAVED),
.formats = (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |
SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE |
SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE |
SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE |
SNDRV_PCM_FMTBIT_FLOAT_LE | SNDRV_PCM_FMTBIT_FLOAT_BE),
.rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,
.rate_min = 8000,
.rate_max = 192000,
.channels_min = 1,
.channels_max = 32,
.buffer_bytes_max = 2 * 1024 * 1024,
.period_bytes_min = 64,
/* note check overflow in frac_pos() using pcm_rate_shift before
changing period_bytes_max value */
.period_bytes_max = 1024 * 1024,
.periods_min = 1,
.periods_max = 1024,
.fifo_size = 0,
};
static void loopback_runtime_free(struct snd_pcm_runtime *runtime)
{
struct loopback_pcm *dpcm = runtime->private_data;
kfree(dpcm);
}
static int loopback_hw_free(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct loopback_pcm *dpcm = runtime->private_data;
struct loopback_cable *cable = dpcm->cable;
mutex_lock(&dpcm->loopback->cable_lock);
cable->valid &= ~(1 << substream->stream);
mutex_unlock(&dpcm->loopback->cable_lock);
return 0;
}
static unsigned int get_cable_index(struct snd_pcm_substream *substream)
{
if (!substream->pcm->device)
return substream->stream;
else
return !substream->stream;
}
static int rule_format(struct snd_pcm_hw_params *params,
struct snd_pcm_hw_rule *rule)
{
struct loopback_pcm *dpcm = rule->private;
struct loopback_cable *cable = dpcm->cable;
struct snd_mask m;
snd_mask_none(&m);
mutex_lock(&dpcm->loopback->cable_lock);
m.bits[0] = (u_int32_t)cable->hw.formats;
m.bits[1] = (u_int32_t)(cable->hw.formats >> 32);
mutex_unlock(&dpcm->loopback->cable_lock);
return snd_mask_refine(hw_param_mask(params, rule->var), &m);
}
static int rule_rate(struct snd_pcm_hw_params *params,
struct snd_pcm_hw_rule *rule)
{
struct loopback_pcm *dpcm = rule->private;
struct loopback_cable *cable = dpcm->cable;
struct snd_interval t;
mutex_lock(&dpcm->loopback->cable_lock);
t.min = cable->hw.rate_min;
t.max = cable->hw.rate_max;
mutex_unlock(&dpcm->loopback->cable_lock);
t.openmin = t.openmax = 0;
t.integer = 0;
return snd_interval_refine(hw_param_interval(params, rule->var), &t);