diff options
| -rw-r--r-- | loopback/loopback.c | 168 |
1 files changed, 163 insertions, 5 deletions
diff --git a/loopback/loopback.c b/loopback/loopback.c index 57f3c34..6f2a5d9 100644 --- a/loopback/loopback.c +++ b/loopback/loopback.c @@ -18,23 +18,177 @@ MODULE_LICENSE("GPL v2"); static struct avirt_coreinfo *coreinfo; +struct loopback_pcm { + struct snd_pcm_substream *substream; + spinlock_t lock; + struct timer_list timer; + unsigned long base_time; + unsigned int frac_pos; /* fractional sample position (based HZ) */ + unsigned int frac_period_rest; + unsigned int frac_buffer_size; /* buffer_size * HZ */ + unsigned int frac_period_size; /* period_size * HZ */ + unsigned int rate; + int elapsed; +}; + +int systimer_create(struct snd_pcm_substream *substream); +void systimer_free(struct snd_pcm_substream *substream); +int systimer_start(struct snd_pcm_substream *substream); +int systimer_stop(struct snd_pcm_substream *substream); +snd_pcm_uframes_t systimer_pointer(struct snd_pcm_substream *substream); +int systimer_prepare(struct snd_pcm_substream *substream); +void systimer_rearm(struct loopback_pcm *dpcm); +void systimer_update(struct loopback_pcm *dpcm); + +void loopback_callback(struct timer_list *tlist); + +/******************************** + * Loopback Timer Functions + ********************************/ + +int systimer_create(struct snd_pcm_substream *substream) +{ + struct snd_pcm_runtime *runtime = substream->runtime; + + struct loopback_pcm *dpcm; + dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL); + if (!dpcm) + return -ENOMEM; + + timer_setup(&dpcm->timer, loopback_callback, 0); + spin_lock_init(&dpcm->lock); + dpcm->substream = substream; + + runtime->private_data = dpcm; + return 0; +} + +void systimer_free(struct snd_pcm_substream *substream) +{ + struct snd_pcm_runtime *runtime = substream->runtime; + kfree(runtime->private_data); +} + +int systimer_start(struct snd_pcm_substream *substream) +{ + struct snd_pcm_runtime *runtime = substream->runtime; + struct loopback_pcm *dpcm = runtime->private_data; + spin_lock(&dpcm->lock); + dpcm->base_time = jiffies; + systimer_rearm(dpcm); + spin_unlock(&dpcm->lock); + return 0; +} + +int systimer_stop(struct snd_pcm_substream *substream) +{ + struct snd_pcm_runtime *runtime = substream->runtime; + struct loopback_pcm *dpcm = runtime->private_data; + spin_lock(&dpcm->lock); + del_timer(&dpcm->timer); + spin_unlock(&dpcm->lock); + return 0; +} + +snd_pcm_uframes_t systimer_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->lock); + systimer_update(dpcm); + pos = dpcm->frac_pos / HZ; + spin_unlock(&dpcm->lock); + return pos; +} + +int systimer_prepare(struct snd_pcm_substream *substream) +{ + struct snd_pcm_runtime *runtime = substream->runtime; + struct loopback_pcm *dpcm = runtime->private_data; + + dpcm->frac_pos = 0; + dpcm->rate = runtime->rate; + dpcm->frac_buffer_size = runtime->buffer_size * HZ; + dpcm->frac_period_size = runtime->period_size * HZ; + dpcm->frac_period_rest = dpcm->frac_period_size; + dpcm->elapsed = 0; + + return 0; +} + +void systimer_rearm(struct loopback_pcm *dpcm) +{ + mod_timer(&dpcm->timer, jiffies + (dpcm->frac_period_rest + dpcm->rate - + 1) / dpcm->rate); +} + +void systimer_update(struct loopback_pcm *dpcm) +{ + unsigned long delta; + + delta = jiffies - dpcm->base_time; + if (!delta) + return; + dpcm->base_time += delta; + delta *= dpcm->rate; + dpcm->frac_pos += delta; + while (dpcm->frac_pos >= dpcm->frac_buffer_size) + dpcm->frac_pos -= dpcm->frac_buffer_size; + while (dpcm->frac_period_rest <= delta) { + dpcm->elapsed++; + dpcm->frac_period_rest += dpcm->frac_period_size; + } + dpcm->frac_period_rest -= delta; +} + +/******* + * Loopback Timer Callback + *******/ + +void loopback_callback(struct timer_list *tlist) +{ + struct loopback_pcm *dpcm = from_timer(dpcm, tlist, timer); + + unsigned long flags; + int elapsed = 0; + + spin_lock_irqsave(&dpcm->lock, flags); + + // Perform copy from playback to capture + systimer_update(dpcm); + systimer_rearm(dpcm); + elapsed = dpcm->elapsed; + dpcm->elapsed = 0; + spin_unlock_irqrestore(&dpcm->lock, flags); + if (elapsed) + coreinfo->pcm_buff_complete(dpcm->substream); +} + /******************************************************************************* * Audio Path ALSA PCM Callbacks ******************************************************************************/ static int loopback_pcm_open(struct snd_pcm_substream *substream) { + int err = systimer_create(substream); + if (err < 0) + return err; + return 0; } static int loopback_pcm_close(struct snd_pcm_substream *substream) { + systimer_free(substream); return 0; } static snd_pcm_uframes_t loopback_pcm_pointer(struct snd_pcm_substream *substream) { - return 0; + return systimer_pointer(substream); } static int loopback_pcm_trigger(struct snd_pcm_substream *substream, int cmd) @@ -42,16 +196,17 @@ static int loopback_pcm_trigger(struct snd_pcm_substream *substream, int cmd) switch (cmd) { case SNDRV_PCM_TRIGGER_START: case SNDRV_PCM_TRIGGER_RESUME: + return systimer_start(substream); case SNDRV_PCM_TRIGGER_STOP: case SNDRV_PCM_TRIGGER_SUSPEND: - return 0; + return systimer_stop(substream); } return -EINVAL; } static int loopback_pcm_prepare(struct snd_pcm_substream *substream) { - return 0; + return systimer_prepare(substream); } static struct snd_pcm_ops loopbackap_pcm_ops = { @@ -71,10 +226,13 @@ static struct snd_pcm_hardware loopbackap_hw = { | SNDRV_PCM_INFO_BLOCK_TRANSFER | SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID), .rates = SNDRV_PCM_RATE_48000, - .rate_min = 48000, + .rate_min = 2000, .rate_max = 48000, + .channels_min = 1, + .channels_max = 8, + .buffer_bytes_max = 32768, .periods_min = 1, - .periods_max = 8, + .periods_max = 1024, }; static struct avirt_audiopath loopbackap_module = { |