[ALSA] Use posix clock monotonic for PCM and timer timestamps

We need an accurate and continuous (monotonic) time sources to do
accurate synchronization among more timing sources. This patch allows
to enable monotonic timestamps for ALSA PCM devices and enables monotonic
timestamps for ALSA timer devices.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

1 files changed, 20 insertions, 5 deletions

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 6245bdaffa68..cdeae7c46e3b 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -598,9 +598,9 @@ int snd_pcm_status(struct snd_pcm_substream *substream,
                 if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_MMAP)
                         status->tstamp = runtime->status->tstamp;
                 else
-                        getnstimeofday(&status->tstamp);
+                        snd_pcm_gettime(runtime, &status->tstamp);
         } else
-                getnstimeofday(&status->tstamp);
+                snd_pcm_gettime(runtime, &status->tstamp);
         status->appl_ptr = runtime->control->appl_ptr;
         status->hw_ptr = runtime->status->hw_ptr;
         if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
@@ -688,7 +688,7 @@ static void snd_pcm_trigger_tstamp(struct snd_pcm_substream *substream)
         if (runtime->trigger_master == NULL)
                 return;
         if (runtime->trigger_master == substream) {
-                getnstimeofday(&runtime->trigger_tstamp);
+                snd_pcm_gettime(runtime, &runtime->trigger_tstamp);
         } else {
                 snd_pcm_trigger_tstamp(runtime->trigger_master);
                 runtime->trigger_tstamp = runtime->trigger_master->runtime->trigger_tstamp;
@@ -2519,6 +2519,21 @@ static int snd_pcm_sync_ptr(struct snd_pcm_substream *substream,
                 return -EFAULT;
         return 0;
 }
+
+static int snd_pcm_tstamp(struct snd_pcm_substream *substream, int __user *_arg)
+{
+        struct snd_pcm_runtime *runtime = substream->runtime;
+        int arg;
+        
+        if (get_user(arg, _arg))
+                return -EFAULT;
+        if (arg < 0 || arg > SNDRV_PCM_TSTAMP_TYPE_LAST)
+                return -EINVAL;
+        runtime->tstamp_type = SNDRV_PCM_TSTAMP_TYPE_GETTIMEOFDAY;
+        if (arg == SNDRV_PCM_TSTAMP_TYPE_MONOTONIC)
+                runtime->tstamp_type = SNDRV_PCM_TSTAMP_TYPE_MONOTONIC;
+        return 0;
+}
                 
 static int snd_pcm_common_ioctl1(struct file *file,
                                  struct snd_pcm_substream *substream,
@@ -2531,8 +2546,8 @@ static int snd_pcm_common_ioctl1(struct file *file,
                 return put_user(SNDRV_PCM_VERSION, (int __user *)arg) ? -EFAULT : 0;
         case SNDRV_PCM_IOCTL_INFO:
                 return snd_pcm_info_user(substream, arg);
-        case SNDRV_PCM_IOCTL_TSTAMP: /* just for compatibility */
-                return 0;
+        case SNDRV_PCM_IOCTL_TTSTAMP:
+                return snd_pcm_tstamp(substream, arg);
         case SNDRV_PCM_IOCTL_HW_REFINE:
                 return snd_pcm_hw_refine_user(substream, arg);
         case SNDRV_PCM_IOCTL_HW_PARAMS: