[alsa-devel] [PATCH v3 kernel 2/3] Extend snd_pcm_ops and snd_pcm_runtime

[Tim Cussins]

snd_pcm_ops picks up methods for:

- start_at
- start_at_abort
- start_at_gettime

For startat requests involving audio hardware clocks, ALSA core
delegates to the driver using these methods, should they exist.

snd_pcm_runtime gains fields that contain the current state of
the startat timer, if any. This allows cancellation and querying.

Signed-off-by: Tim Cussins <timcussins at eml.cc>

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 07299b2..a414fec 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -73,6 +73,9 @@ struct snd_pcm_ops {
 	snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *substream);
 	int (*wall_clock)(struct snd_pcm_substream *substream,
 			  struct timespec *audio_ts);
+	int (*start_at)(struct snd_pcm_substream *substream, int startat_clock_type, const struct timespec *ts);
+	int (*start_at_abort)(struct snd_pcm_substream *substream);
+	int (*start_at_gettime)(struct snd_pcm_substream *substream, int startat_clock_type, struct timespec *current_time);
 	int (*copy)(struct snd_pcm_substream *substream, int channel,
 		    snd_pcm_uframes_t pos,
 		    void __user *buf, snd_pcm_uframes_t count);
@@ -368,6 +371,12 @@ struct snd_pcm_runtime {
 #ifdef CONFIG_SND_PCM_XRUN_DEBUG
 	struct snd_pcm_hwptr_log *hwptr_log;
 #endif
+
+	bool startat_timer_running;
+	/* The following values are valid if startat_timer_running == true */
+	int startat_clock_type;			/* startat clock type of current timer */
+	struct timespec startat_start_time;	/* start time of current timer */
+	void* startat_timer_data;		/* data associated with current timer */
 };
 
 struct snd_pcm_group {		/* keep linked substreams */
-- 
1.9.1