#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");
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_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
unsigned int pause;
/* timer specific */
struct loopback_ops *ops;
+ /* If sound timer is used */
+ struct {
+ int stream;
+ struct snd_timer_id id;
+ struct tasklet_struct event_tasklet;
+ struct snd_timer_instance *instance;
+ } snd_timer;
};
struct loopback_setup {
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 {
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;
};
}
/* 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);
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;
+
+ /* wait till drain tasklet has finished if requested */
+ tasklet_kill(&cable->snd_timer.event_tasklet);
+
+ /* 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);
+ snd_timer_instance_free(cable->snd_timer.instance);
+ memset(&cable->snd_timer, 0, sizeof(cable->snd_timer));
+
+ return 0;
+}
+
static int loopback_check_format(struct loopback_cable *cable, int stream)
{
struct snd_pcm_runtime *runtime, *cruntime;
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)
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];
+ substream_play = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
+ dpcm_play->substream : NULL;
+ substream_capt = (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) ?
+ dpcm_capt->substream : NULL;
+
+ if (event == SNDRV_TIMER_EVENT_MSTOP) {
+ if (!dpcm_play ||
+ dpcm_play->substream->runtime->status->state !=
+ SNDRV_PCM_STATE_DRAINING) {
+ spin_unlock_irqrestore(&cable->lock, flags);
+ return;
+ }
+ }
+
+ 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_tasklet(unsigned long arg)
+{
+ struct snd_timer_instance *timeri = (struct snd_timer_instance *)arg;
+ struct loopback_cable *cable = timeri->callback_data;
+
+ 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 timespec *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 tasklet triggers loopback_snd_timer_tasklet()
+ */
+ tasklet_schedule(&cable->snd_timer.event_tasklet);
+ }
+}
+
static void loopback_jiffies_timer_dpcm_info(struct loopback_pcm *dpcm,
struct snd_info_buffer *buffer)
{
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;
return snd_interval_refine(hw_param_interval(params, rule->var), &t);
}
+static int rule_period_bytes(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.period_bytes_min;
+ t.max = cable->hw.period_bytes_max;
+ mutex_unlock(&dpcm->loopback->cable_lock);
+ t.openmin = 0;
+ t.openmax = 0;
+ t.integer = 0;
+ return snd_interval_refine(hw_param_interval(params, rule->var), &t);
+}
+
static void free_cable(struct snd_pcm_substream *substream)
{
struct loopback *loopback = substream->private_data;
.dpcm_info = loopback_jiffies_timer_dpcm_info,
};
+static int loopback_parse_timer_id(const char *str,
+ struct snd_timer_id *tid)
+{
+ /* [<pref>:](<card name>|<card idx>)[{.,}<dev idx>[{.,}<subdev idx>]] */
+ const char * const sep_dev = ".,";
+ const char * const sep_pref = ":";
+ const char *name = str;
+ char *sep, save = '\0';
+ int card_idx = 0, dev = 0, subdev = 0;
+ int err;
+
+ sep = strpbrk(str, sep_pref);
+ if (sep)
+ name = sep + 1;
+ sep = strpbrk(name, sep_dev);
+ if (sep) {
+ save = *sep;
+ *sep = '\0';
+ }
+ err = kstrtoint(name, 0, &card_idx);
+ if (err == -EINVAL) {
+ /* Must be the name, not number */
+ for (card_idx = 0; card_idx < snd_ecards_limit; card_idx++) {
+ struct snd_card *card = snd_card_ref(card_idx);
+
+ if (card) {
+ if (!strcmp(card->id, name))
+ err = 0;
+ snd_card_unref(card);
+ }
+ if (!err)
+ break;
+ }
+ }
+ if (sep) {
+ *sep = save;
+ if (!err) {
+ char *sep2, save2 = '\0';
+
+ sep2 = strpbrk(sep + 1, sep_dev);
+ if (sep2) {
+ save2 = *sep2;
+ *sep2 = '\0';
+ }
+ err = kstrtoint(sep + 1, 0, &dev);
+ if (sep2) {
+ *sep2 = save2;
+ if (!err)
+ err = kstrtoint(sep2 + 1, 0, &subdev);
+ }
+ }
+ }
+ if (!err && tid) {
+ tid->card = card_idx;
+ tid->device = dev;
+ tid->subdevice = subdev;
+ }
+ return err;
+}
+
+/* call in loopback->cable_lock */
+static int loopback_snd_timer_open(struct loopback_pcm *dpcm)
+{
+ int err = 0;
+ struct snd_timer_id tid = {
+ .dev_class = SNDRV_TIMER_CLASS_PCM,
+ .dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION,
+ };
+ struct snd_timer_instance *timeri;
+ struct loopback_cable *cable = dpcm->cable;
+
+ spin_lock_irq(&cable->lock);
+
+ /* check if timer was already opened. It is only opened once
+ * per playback and capture subdevice (aka cable).
+ */
+ if (cable->snd_timer.instance)
+ goto unlock;
+
+ err = loopback_parse_timer_id(dpcm->loopback->timer_source, &tid);
+ if (err < 0) {
+ pcm_err(dpcm->substream->pcm,
+ "Parsing timer source \'%s\' failed with %d",
+ dpcm->loopback->timer_source, err);
+ goto unlock;
+ }
+
+ cable->snd_timer.stream = dpcm->substream->stream;
+ cable->snd_timer.id = tid;
+
+ timeri = snd_timer_instance_new(dpcm->loopback->card->id);
+ if (!timeri) {
+ err = -ENOMEM;
+ goto unlock;
+ }
+ /* The callback has to be called from another tasklet. If
+ * SNDRV_TIMER_IFLG_FAST is specified it will be called from the
+ * snd_pcm_period_elapsed() call of the selected sound card.
+ * snd_pcm_period_elapsed() helds snd_pcm_stream_lock_irqsave().
+ * Due to our callback loopback_snd_timer_function() also calls
+ * snd_pcm_period_elapsed() which calls snd_pcm_stream_lock_irqsave().
+ * This would end up in a dead lock.
+ */
+ timeri->flags |= SNDRV_TIMER_IFLG_AUTO;
+ timeri->callback = loopback_snd_timer_function;
+ timeri->callback_data = (void *)cable;
+ timeri->ccallback = loopback_snd_timer_event;
+
+ /* initialise a tasklet used for draining */
+ tasklet_init(&cable->snd_timer.event_tasklet,
+ loopback_snd_timer_tasklet, (unsigned long)timeri);
+
+ /* snd_timer_close() and snd_timer_open() should not be called with
+ * locked spinlock because both functions can block on a mutex. The
+ * mutex loopback->cable_lock is kept locked. Therefore snd_timer_open()
+ * cannot be called a second time by the other device of the same cable.
+ * Therefore the following issue cannot happen:
+ * [proc1] Call loopback_timer_open() ->
+ * Unlock cable->lock for snd_timer_close/open() call
+ * [proc2] Call loopback_timer_open() -> snd_timer_open(),
+ * snd_timer_start()
+ * [proc1] Call snd_timer_open() and overwrite running timer
+ * instance
+ */
+ spin_unlock_irq(&cable->lock);
+ err = snd_timer_open(timeri, &cable->snd_timer.id, current->pid);
+ spin_lock_irq(&cable->lock);
+ if (err < 0) {
+ pcm_err(dpcm->substream->pcm,
+ "snd_timer_open (%d,%d,%d) failed with %d",
+ cable->snd_timer.id.card,
+ cable->snd_timer.id.device,
+ cable->snd_timer.id.subdevice,
+ err);
+ snd_timer_instance_free(timeri);
+ goto unlock;
+ }
+
+ cable->snd_timer.instance = timeri;
+
+unlock:
+ spin_unlock_irq(&cable->lock);
+
+ return err;
+}
+
+/* stop_sync() is not required for sound timer because it does not need to be
+ * restarted in loopback_prepare() on Xrun recovery
+ */
+static struct loopback_ops loopback_snd_timer_ops = {
+ .open = loopback_snd_timer_open,
+ .start = loopback_snd_timer_start,
+ .stop = loopback_snd_timer_stop,
+ .close_cable = loopback_snd_timer_close_cable,
+ .dpcm_info = loopback_snd_timer_dpcm_info,
+};
+
static int loopback_open(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
}
spin_lock_init(&cable->lock);
cable->hw = loopback_pcm_hardware;
- cable->ops = &loopback_jiffies_timer_ops;
+ if (loopback->timer_source)
+ cable->ops = &loopback_snd_timer_ops;
+ else
+ cable->ops = &loopback_jiffies_timer_ops;
loopback->cables[substream->number][dev] = cable;
}
dpcm->cable = cable;
if (err < 0)
goto unlock;
+ /* In case of sound timer the period time of both devices of the same
+ * loop has to be the same.
+ * This rule only takes effect if a sound timer was chosen
+ */
+ if (cable->snd_timer.instance) {
+ err = snd_pcm_hw_rule_add(runtime, 0,
+ SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
+ rule_period_bytes, dpcm,
+ SNDRV_PCM_HW_PARAM_PERIOD_BYTES, -1);
+ if (err < 0)
+ goto unlock;
+ }
+
/* loopback_runtime_free() has not to be called if kfree(dpcm) was
* already called here. Otherwise it will end up with a double free.
*/
print_cable_info);
}
+static void loopback_set_timer_source(struct loopback *loopback,
+ const char *value)
+{
+ if (loopback->timer_source) {
+ devm_kfree(loopback->card->dev, loopback->timer_source);
+ loopback->timer_source = NULL;
+ }
+ if (value && *value)
+ loopback->timer_source = devm_kstrdup(loopback->card->dev,
+ value, GFP_KERNEL);
+}
+
static int loopback_probe(struct platform_device *devptr)
{
struct snd_card *card;
pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
loopback->card = card;
+ loopback_set_timer_source(loopback, timer_source[dev]);
+
mutex_init(&loopback->cable_lock);
err = loopback_pcm_new(loopback, 0, pcm_substreams[dev]);