ASoC: SOF: add a helper to get topology configured mclk

Add helper sof_dai_ssp_mclk to get the topology configured MCLK from a
pcm_runtime, return 0 if it is not available, and error if the dai type
is not SSP at the moment.

Export the helper for external use, e.g. from machine drivers.

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@gmail.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20210319124950.3853994-1-kai.vehmanen@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/sof.h

@@ -103,5 +103,6 @@ struct sof_dev_desc {
 int sof_nocodec_setup(struct device *dev, const struct snd_sof_dsp_ops *ops,
 		      int (*pcm_dai_link_fixup)(struct snd_soc_pcm_runtime *rtd,
 						struct snd_pcm_hw_params *params));
+int sof_dai_get_mclk(struct snd_soc_pcm_runtime *rtd);
 
 #endif

sound/soc/sof/sof-audio.c

@@ -433,6 +433,33 @@ struct snd_sof_dai *snd_sof_find_dai(struct snd_soc_component *scomp,
 	return NULL;
 }
 
+/*
+ * Helper to get SSP MCLK from a pcm_runtime.
+ * Return 0 if not exist.
+ */
+int sof_dai_get_mclk(struct snd_soc_pcm_runtime *rtd)
+{
+	struct snd_soc_component *component =
+		snd_soc_rtdcom_lookup(rtd, SOF_AUDIO_PCM_DRV_NAME);
+	struct snd_sof_dai *dai =
+		snd_sof_find_dai(component, (char *)rtd->dai_link->name);
+
+	/* use the tplg configured mclk if existed */
+	if (!dai || !dai->dai_config)
+		return 0;
+
+	switch (dai->dai_config->type) {
+	case SOF_DAI_INTEL_SSP:
+		return dai->dai_config->ssp.mclk_rate;
+	default:
+		/* not yet implemented for platforms other than the above */
+		dev_err(rtd->dev, "mclk for dai_config->type %d not supported yet!\n",
+			dai->dai_config->type);
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL(sof_dai_get_mclk);
+
 /*
  * SOF Driver enumeration.
  */