ASoC: SOF: sof-pcm: Add pointer callback to sof_ipc_pcm_ops

The IPC specific pointer callback can be used when additional or custom
handling is needed during the pointer calculation, like executing a delay
calculation at the same time to minimize drift between the reported pointer
and the calculated delay.

Cc: stable@vger.kernel.org # 6.8
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://msgid.link/r/20240321130814.4412-15-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/pcm.c

@@ -388,13 +388,21 @@ static snd_pcm_uframes_t sof_pcm_pointer(struct snd_soc_component *component,
 {
 	struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
 	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(component);
+	const struct sof_ipc_pcm_ops *pcm_ops = sof_ipc_get_ops(sdev, pcm);
 	struct snd_sof_pcm *spcm;
 	snd_pcm_uframes_t host, dai;
+	int ret = -EOPNOTSUPP;
 
 	/* nothing to do for BE */
 	if (rtd->dai_link->no_pcm)
 		return 0;
 
+	if (pcm_ops && pcm_ops->pointer)
+		ret = pcm_ops->pointer(component, substream, &host);
+
+	if (ret != -EOPNOTSUPP)
+		return ret ? ret : host;
+
 	/* use dsp ops pointer callback directly if set */
 	if (sof_ops(sdev)->pcm_pointer)
 		return sof_ops(sdev)->pcm_pointer(sdev, substream);

sound/soc/sof/sof-audio.h

@@ -103,7 +103,10 @@ struct snd_sof_dai_config_data {
  *	       additional memory in the SOF PCM stream structure
  * @pcm_free: Function pointer for PCM free that can be used for freeing any
  *	       additional memory in the SOF PCM stream structure
- * @delay: Function pointer for pcm delay calculation
+ * @pointer: Function pointer for pcm pointer
+ *	     Note: the @pointer callback may return -EOPNOTSUPP which should be
+ *		   handled in a same way as if the callback is not provided
+ * @delay: Function pointer for pcm delay reporting
  * @reset_hw_params_during_stop: Flag indicating whether the hw_params should be reset during the
  *				 STOP pcm trigger
  * @ipc_first_on_start: Send IPC before invoking platform trigger during
@@ -124,6 +127,9 @@ struct sof_ipc_pcm_ops {
 	int (*dai_link_fixup)(struct snd_soc_pcm_runtime *rtd, struct snd_pcm_hw_params *params);
 	int (*pcm_setup)(struct snd_sof_dev *sdev, struct snd_sof_pcm *spcm);
 	void (*pcm_free)(struct snd_sof_dev *sdev, struct snd_sof_pcm *spcm);
+	int (*pointer)(struct snd_soc_component *component,
+		       struct snd_pcm_substream *substream,
+		       snd_pcm_uframes_t *pointer);
 	snd_pcm_sframes_t (*delay)(struct snd_soc_component *component,
 				   struct snd_pcm_substream *substream);
 	bool reset_hw_params_during_stop;