ALSA: dummy - Support high-res timer mode

Allow snd-dummy driver to use high-res timer as its timing source
instead of the system timer.  The new module option "hrtimer" is added
to turn on/off the high-res timer support.  It can be switched even
dynamically via sysfs.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/dummy.c

@@ -25,6 +25,8 @@
 #include <linux/slab.h>
 #include <linux/time.h>
 #include <linux/wait.h>
+#include <linux/hrtimer.h>
+#include <linux/math64.h>
 #include <linux/moduleparam.h>
 #include <sound/core.h>
 #include <sound/control.h>
@@ -148,6 +150,9 @@ static int enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
 static int pcm_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};
 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
 //static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2};
+#ifdef CONFIG_HIGH_RES_TIMERS
+static int hrtimer = 1;
+#endif
 
 module_param_array(index, int, NULL, 0444);
 MODULE_PARM_DESC(index, "Index value for dummy soundcard.");
@@ -161,6 +166,10 @@ module_param_array(pcm_substreams, int, NULL, 0444);
 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-16) for dummy driver.");
 //module_param_array(midi_devs, int, NULL, 0444);
 //MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for dummy driver.");
+#ifdef CONFIG_HIGH_RES_TIMERS
+module_param(hrtimer, bool, 0644);
+MODULE_PARM_DESC(hrtimer, "Use hrtimer as the timer source.");
+#endif
 
 static struct platform_device *devices[SNDRV_CARDS];
 
@@ -171,16 +180,29 @@ static struct platform_device *devices[SNDRV_CARDS];
 #define MIXER_ADDR_CD		4
 #define MIXER_ADDR_LAST		4
 
+struct dummy_timer_ops {
+	int (*create)(struct snd_pcm_substream *);
+	void (*free)(struct snd_pcm_substream *);
+	int (*prepare)(struct snd_pcm_substream *);
+	int (*start)(struct snd_pcm_substream *);
+	int (*stop)(struct snd_pcm_substream *);
+	snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *);
+};
+
 struct snd_dummy {
 	struct snd_card *card;
 	struct snd_pcm *pcm;
 	spinlock_t mixer_lock;
 	int mixer_volume[MIXER_ADDR_LAST+1][2];
 	int capture_source[MIXER_ADDR_LAST+1][2];
+	const struct dummy_timer_ops *timer_ops;
 };
 
-struct snd_dummy_pcm {
-	struct snd_dummy *dummy;
+/*
+ * system timer interface
+ */
+
+struct dummy_systimer_pcm {
 	spinlock_t lock;
 	struct timer_list timer;
 	unsigned int pcm_buffer_size;
@@ -192,46 +214,29 @@ struct snd_dummy_pcm {
 	struct snd_pcm_substream *substream;
 };
 
-
-static inline void snd_card_dummy_pcm_timer_start(struct snd_dummy_pcm *dpcm)
+static int dummy_systimer_start(struct snd_pcm_substream *substream)
 {
+	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
+	spin_lock(&dpcm->lock);
 	dpcm->timer.expires = 1 + jiffies;
 	add_timer(&dpcm->timer);
+	spin_unlock(&dpcm->lock);
+	return 0;
 }
 
-static inline void snd_card_dummy_pcm_timer_stop(struct snd_dummy_pcm *dpcm)
-{
-	del_timer(&dpcm->timer);
-}
-
-static int snd_card_dummy_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+static int dummy_systimer_stop(struct snd_pcm_substream *substream)
 {
-	struct snd_pcm_runtime *runtime = substream->runtime;
-	struct snd_dummy_pcm *dpcm = runtime->private_data;
-	int err = 0;
-
+	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
 	spin_lock(&dpcm->lock);
-	switch (cmd) {
-	case SNDRV_PCM_TRIGGER_START:
-	case SNDRV_PCM_TRIGGER_RESUME:
-		snd_card_dummy_pcm_timer_start(dpcm);
-		break;
-	case SNDRV_PCM_TRIGGER_STOP:
-	case SNDRV_PCM_TRIGGER_SUSPEND:
-		snd_card_dummy_pcm_timer_stop(dpcm);
-		break;
-	default:
-		err = -EINVAL;
-		break;
-	}
+	del_timer(&dpcm->timer);
 	spin_unlock(&dpcm->lock);
 	return 0;
 }
 
-static int snd_card_dummy_pcm_prepare(struct snd_pcm_substream *substream)
+static int dummy_systimer_prepare(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
-	struct snd_dummy_pcm *dpcm = runtime->private_data;
+	struct dummy_systimer_pcm *dpcm = runtime->private_data;
 	int bps;
 
 	bps = snd_pcm_format_width(runtime->format) * runtime->rate *
@@ -247,15 +252,12 @@ static int snd_card_dummy_pcm_prepare(struct snd_pcm_substream *substream)
 	dpcm->pcm_irq_pos = 0;
 	dpcm->pcm_buf_pos = 0;
 
-	snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
-			bytes_to_samples(runtime, runtime->dma_bytes));
-
 	return 0;
 }
 
-static void snd_card_dummy_pcm_timer_function(unsigned long data)
+static void dummy_systimer_callback(unsigned long data)
 {
-	struct snd_dummy_pcm *dpcm = (struct snd_dummy_pcm *)data;
+	struct dummy_systimer_pcm *dpcm = (struct dummy_systimer_pcm *)data;
 	unsigned long flags;
 	
 	spin_lock_irqsave(&dpcm->lock, flags);
@@ -272,36 +274,212 @@ static void snd_card_dummy_pcm_timer_function(unsigned long data)
 		spin_unlock_irqrestore(&dpcm->lock, flags);
 }
 
-static snd_pcm_uframes_t snd_card_dummy_pcm_pointer(struct snd_pcm_substream *substream)
+static snd_pcm_uframes_t
+dummy_systimer_pointer(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
-	struct snd_dummy_pcm *dpcm = runtime->private_data;
+	struct dummy_systimer_pcm *dpcm = runtime->private_data;
 
 	return bytes_to_frames(runtime, dpcm->pcm_buf_pos / dpcm->pcm_hz);
 }
 
-static struct snd_pcm_hardware snd_card_dummy_playback =
+static int dummy_systimer_create(struct snd_pcm_substream *substream)
 {
-	.info =			(SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
-				 SNDRV_PCM_INFO_RESUME | SNDRV_PCM_INFO_MMAP_VALID),
-	.formats =		USE_FORMATS,
-	.rates =		USE_RATE,
-	.rate_min =		USE_RATE_MIN,
-	.rate_max =		USE_RATE_MAX,
-	.channels_min =		USE_CHANNELS_MIN,
-	.channels_max =		USE_CHANNELS_MAX,
-	.buffer_bytes_max =	MAX_BUFFER_SIZE,
-	.period_bytes_min =	64,
-	.period_bytes_max =	MAX_PERIOD_SIZE,
-	.periods_min =		USE_PERIODS_MIN,
-	.periods_max =		USE_PERIODS_MAX,
-	.fifo_size =		0,
+	struct dummy_systimer_pcm *dpcm;
+
+	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
+	if (!dpcm)
+		return -ENOMEM;
+	substream->runtime->private_data = dpcm;
+	init_timer(&dpcm->timer);
+	dpcm->timer.data = (unsigned long) dpcm;
+	dpcm->timer.function = dummy_systimer_callback;
+	spin_lock_init(&dpcm->lock);
+	dpcm->substream = substream;
+	return 0;
+}
+
+static void dummy_systimer_free(struct snd_pcm_substream *substream)
+{
+	kfree(substream->runtime->private_data);
+}
+
+static struct dummy_timer_ops dummy_systimer_ops = {
+	.create =	dummy_systimer_create,
+	.free =		dummy_systimer_free,
+	.prepare =	dummy_systimer_prepare,
+	.start =	dummy_systimer_start,
+	.stop =		dummy_systimer_stop,
+	.pointer =	dummy_systimer_pointer,
+};
+
+#ifdef CONFIG_HIGH_RES_TIMERS
+/*
+ * hrtimer interface
+ */
+
+struct dummy_hrtimer_pcm {
+	ktime_t base_time;
+	ktime_t period_time;
+	atomic_t running;
+	struct hrtimer timer;
+	struct tasklet_struct tasklet;
+	struct snd_pcm_substream *substream;
+};
+
+static void dummy_hrtimer_pcm_elapsed(unsigned long priv)
+{
+	struct dummy_hrtimer_pcm *dpcm = (struct dummy_hrtimer_pcm *)priv;
+	if (atomic_read(&dpcm->running))
+		snd_pcm_period_elapsed(dpcm->substream);
+}
+
+static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
+{
+	struct dummy_hrtimer_pcm *dpcm;
+
+	dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer);
+	if (!atomic_read(&dpcm->running))
+		return HRTIMER_NORESTART;
+	tasklet_schedule(&dpcm->tasklet);
+	hrtimer_forward_now(timer, dpcm->period_time);
+	return HRTIMER_RESTART;
+}
+
+static int dummy_hrtimer_start(struct snd_pcm_substream *substream)
+{
+	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
+
+	dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
+	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL);
+	atomic_set(&dpcm->running, 1);
+	return 0;
+}
+
+static int dummy_hrtimer_stop(struct snd_pcm_substream *substream)
+{
+	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
+
+	atomic_set(&dpcm->running, 0);
+	hrtimer_cancel(&dpcm->timer);
+	return 0;
+}
+
+static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
+{
+	tasklet_kill(&dpcm->tasklet);
+}
+
+static snd_pcm_uframes_t
+dummy_hrtimer_pointer(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct dummy_hrtimer_pcm *dpcm = runtime->private_data;
+	u64 delta;
+	u32 pos;
+
+	delta = ktime_us_delta(hrtimer_cb_get_time(&dpcm->timer),
+			       dpcm->base_time);
+	delta = div_u64(delta * runtime->rate + 999999, 1000000);
+	div_u64_rem(delta, runtime->buffer_size, &pos);
+	return pos;
+}
+
+static int dummy_hrtimer_prepare(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct dummy_hrtimer_pcm *dpcm = runtime->private_data;
+	unsigned int period, rate;
+	long sec;
+	unsigned long nsecs;
+
+	dummy_hrtimer_sync(dpcm);
+	period = runtime->period_size;
+	rate = runtime->rate;
+	sec = period / rate;
+	period %= rate;
+	nsecs = div_u64((u64)period * 1000000000UL + rate - 1, rate);
+	dpcm->period_time = ktime_set(sec, nsecs);
+
+	return 0;
+}
+
+static int dummy_hrtimer_create(struct snd_pcm_substream *substream)
+{
+	struct dummy_hrtimer_pcm *dpcm;
+
+	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
+	if (!dpcm)
+		return -ENOMEM;
+	substream->runtime->private_data = dpcm;
+	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	dpcm->timer.function = dummy_hrtimer_callback;
+	dpcm->substream = substream;
+	atomic_set(&dpcm->running, 0);
+	tasklet_init(&dpcm->tasklet, dummy_hrtimer_pcm_elapsed,
+		     (unsigned long)dpcm);
+	return 0;
+}
+
+static void dummy_hrtimer_free(struct snd_pcm_substream *substream)
+{
+	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
+	dummy_hrtimer_sync(dpcm);
+	kfree(dpcm);
+}
+
+static struct dummy_timer_ops dummy_hrtimer_ops = {
+	.create =	dummy_hrtimer_create,
+	.free =		dummy_hrtimer_free,
+	.prepare =	dummy_hrtimer_prepare,
+	.start =	dummy_hrtimer_start,
+	.stop =		dummy_hrtimer_stop,
+	.pointer =	dummy_hrtimer_pointer,
 };
 
-static struct snd_pcm_hardware snd_card_dummy_capture =
+#endif /* CONFIG_HIGH_RES_TIMERS */
+
+/*
+ * PCM interface
+ */
+
+static int dummy_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+	struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+		return dummy->timer_ops->start(substream);
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+		return dummy->timer_ops->stop(substream);
+	}
+	return -EINVAL;
+}
+
+static int dummy_pcm_prepare(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
+
+	snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+			bytes_to_samples(runtime, runtime->dma_bytes));
+	return dummy->timer_ops->prepare(substream);
+}
+
+static snd_pcm_uframes_t dummy_pcm_pointer(struct snd_pcm_substream *substream)
 {
-	.info =			(SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
-				 SNDRV_PCM_INFO_RESUME | SNDRV_PCM_INFO_MMAP_VALID),
+	struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
+
+	return dummy->timer_ops->pointer(substream);
+}
+
+static struct snd_pcm_hardware dummy_pcm_hardware = {
+	.info =			(SNDRV_PCM_INFO_MMAP |
+				 SNDRV_PCM_INFO_INTERLEAVED |
+				 SNDRV_PCM_INFO_RESUME |
+				 SNDRV_PCM_INFO_MMAP_VALID),
 	.formats =		USE_FORMATS,
 	.rates =		USE_RATE,
 	.rate_min =		USE_RATE_MIN,
@@ -316,117 +494,70 @@ static struct snd_pcm_hardware snd_card_dummy_capture =
 	.fifo_size =		0,
 };
 
-static void snd_card_dummy_runtime_free(struct snd_pcm_runtime *runtime)
-{
-	kfree(runtime->private_data);
-}
-
-static int snd_card_dummy_hw_params(struct snd_pcm_substream *substream,
-				    struct snd_pcm_hw_params *hw_params)
+static int dummy_pcm_hw_params(struct snd_pcm_substream *substream,
+			       struct snd_pcm_hw_params *hw_params)
 {
-	return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
+	return snd_pcm_lib_malloc_pages(substream,
+					params_buffer_bytes(hw_params));
 }
 
-static int snd_card_dummy_hw_free(struct snd_pcm_substream *substream)
+static int dummy_pcm_hw_free(struct snd_pcm_substream *substream)
 {
 	return snd_pcm_lib_free_pages(substream);
 }
 
-static struct snd_dummy_pcm *new_pcm_stream(struct snd_pcm_substream *substream)
-{
-	struct snd_dummy_pcm *dpcm;
-
-	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
-	if (! dpcm)
-		return dpcm;
-	init_timer(&dpcm->timer);
-	dpcm->timer.data = (unsigned long) dpcm;
-	dpcm->timer.function = snd_card_dummy_pcm_timer_function;
-	spin_lock_init(&dpcm->lock);
-	dpcm->substream = substream;
-	return dpcm;
-}
-
-static int snd_card_dummy_playback_open(struct snd_pcm_substream *substream)
+static int dummy_pcm_open(struct snd_pcm_substream *substream)
 {
+	struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
 	struct snd_pcm_runtime *runtime = substream->runtime;
-	struct snd_dummy_pcm *dpcm;
 	int err;
 
-	if ((dpcm = new_pcm_stream(substream)) == NULL)
-		return -ENOMEM;
-	runtime->private_data = dpcm;
-	/* makes the infrastructure responsible for freeing dpcm */
-	runtime->private_free = snd_card_dummy_runtime_free;
-	runtime->hw = snd_card_dummy_playback;
-	if (substream->pcm->device & 1) {
-		runtime->hw.info &= ~SNDRV_PCM_INFO_INTERLEAVED;
-		runtime->hw.info |= SNDRV_PCM_INFO_NONINTERLEAVED;
-	}
-	if (substream->pcm->device & 2)
-		runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP|SNDRV_PCM_INFO_MMAP_VALID);
-	err = add_playback_constraints(runtime);
+	dummy->timer_ops = &dummy_systimer_ops;
+#ifdef CONFIG_HIGH_RES_TIMERS
+	if (hrtimer)
+		dummy->timer_ops = &dummy_hrtimer_ops;
+#endif
+
+	err = dummy->timer_ops->create(substream);
 	if (err < 0)
 		return err;
 
-	return 0;
-}
-
-static int snd_card_dummy_capture_open(struct snd_pcm_substream *substream)
-{
-	struct snd_pcm_runtime *runtime = substream->runtime;
-	struct snd_dummy_pcm *dpcm;
-	int err;
-
-	if ((dpcm = new_pcm_stream(substream)) == NULL)
-		return -ENOMEM;
-	runtime->private_data = dpcm;
-	/* makes the infrastructure responsible for freeing dpcm */
-	runtime->private_free = snd_card_dummy_runtime_free;
-	runtime->hw = snd_card_dummy_capture;
-	if (substream->pcm->device == 1) {
+	runtime->hw = dummy_pcm_hardware;
+	if (substream->pcm->device & 1) {
 		runtime->hw.info &= ~SNDRV_PCM_INFO_INTERLEAVED;
 		runtime->hw.info |= SNDRV_PCM_INFO_NONINTERLEAVED;
 	}
 	if (substream->pcm->device & 2)
-		runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP|SNDRV_PCM_INFO_MMAP_VALID);
-	err = add_capture_constraints(runtime);
-	if (err < 0)
+		runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP |
+				      SNDRV_PCM_INFO_MMAP_VALID);
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		err = add_playback_constraints(substream->runtime);
+	else
+		err = add_capture_constraints(substream->runtime);
+	if (err < 0) {
+		dummy->timer_ops->free(substream);
 		return err;
-
-	return 0;
-}
-
-static int snd_card_dummy_playback_close(struct snd_pcm_substream *substream)
-{
+	}
 	return 0;
 }
 
-static int snd_card_dummy_capture_close(struct snd_pcm_substream *substream)
+static int dummy_pcm_close(struct snd_pcm_substream *substream)
 {
+	struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
+	dummy->timer_ops->free(substream);
 	return 0;
 }
 
-static struct snd_pcm_ops snd_card_dummy_playback_ops = {
-	.open =			snd_card_dummy_playback_open,
-	.close =		snd_card_dummy_playback_close,
-	.ioctl =		snd_pcm_lib_ioctl,
-	.hw_params =		snd_card_dummy_hw_params,
-	.hw_free =		snd_card_dummy_hw_free,
-	.prepare =		snd_card_dummy_pcm_prepare,
-	.trigger =		snd_card_dummy_pcm_trigger,
-	.pointer =		snd_card_dummy_pcm_pointer,
-};
-
-static struct snd_pcm_ops snd_card_dummy_capture_ops = {
-	.open =			snd_card_dummy_capture_open,
-	.close =		snd_card_dummy_capture_close,
-	.ioctl =		snd_pcm_lib_ioctl,
-	.hw_params =		snd_card_dummy_hw_params,
-	.hw_free =		snd_card_dummy_hw_free,
-	.prepare =		snd_card_dummy_pcm_prepare,
-	.trigger =		snd_card_dummy_pcm_trigger,
-	.pointer =		snd_card_dummy_pcm_pointer,
+static struct snd_pcm_ops dummy_pcm_ops = {
+	.open =		dummy_pcm_open,
+	.close =	dummy_pcm_close,
+	.ioctl =	snd_pcm_lib_ioctl,
+	.hw_params =	dummy_pcm_hw_params,
+	.hw_free =	dummy_pcm_hw_free,
+	.prepare =	dummy_pcm_prepare,
+	.trigger =	dummy_pcm_trigger,
+	.pointer =	dummy_pcm_pointer,
 };
 
 static int __devinit snd_card_dummy_pcm(struct snd_dummy *dummy, int device,
@@ -440,8 +571,8 @@ static int __devinit snd_card_dummy_pcm(struct snd_dummy *dummy, int device,
 	if (err < 0)
 		return err;
 	dummy->pcm = pcm;
-	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_dummy_playback_ops);
-	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_dummy_capture_ops);
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &dummy_pcm_ops);
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &dummy_pcm_ops);
 	pcm->private_data = dummy;
 	pcm->info_flags = 0;
 	strcpy(pcm->name, "Dummy PCM");