ASoC: rt1308-sdw: add set_tdm_slot() support

Add ability to select which of the channels is used, or both, in case
two RT1308 amplifiers are located on the same link.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200325212905.28145-2-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/rt1308-sdw.c

@@ -507,6 +507,28 @@ static void rt1308_sdw_shutdown(struct snd_pcm_substream *substream,
 	kfree(stream);
 }
 
+static int rt1308_sdw_set_tdm_slot(struct snd_soc_dai *dai,
+				   unsigned int tx_mask,
+				   unsigned int rx_mask,
+				   int slots, int slot_width)
+{
+	struct snd_soc_component *component = dai->component;
+	struct rt1308_sdw_priv *rt1308 =
+		snd_soc_component_get_drvdata(component);
+
+	if (tx_mask)
+		return -EINVAL;
+
+	if (slots > 2)
+		return -EINVAL;
+
+	rt1308->rx_mask = rx_mask;
+	rt1308->slots = slots;
+	/* slot_width is not used since it's irrelevant for SoundWire */
+
+	return 0;
+}
+
 static int rt1308_sdw_hw_params(struct snd_pcm_substream *substream,
 	struct snd_pcm_hw_params *params, struct snd_soc_dai *dai)
 {
@@ -597,6 +619,7 @@ static const struct snd_soc_dai_ops rt1308_aif_dai_ops = {
 	.hw_free	= rt1308_sdw_pcm_hw_free,
 	.set_sdw_stream	= rt1308_set_sdw_stream,
 	.shutdown	= rt1308_sdw_shutdown,
+	.set_tdm_slot	= rt1308_sdw_set_tdm_slot,
 };
 
 #define RT1308_STEREO_RATES SNDRV_PCM_RATE_48000

sound/soc/codecs/rt1308-sdw.h

@@ -160,6 +160,8 @@ struct rt1308_sdw_priv {
 	struct sdw_bus_params params;
 	bool hw_init;
 	bool first_hw_init;
+	int rx_mask;
+	int slots;
 };
 
 struct sdw_stream_data {