ASoC: pcm3168a: Add support for multi DIN/DOUT with TDM slots parameter

The driver was wired to be only usable in DIN1/DOUT1 mode, switching
between TDM and non TDM modes based on the number of channels.

While keeping this functionality for compatibility add support for using
all DIN1/2/3/4 and DOUT1/2/3 if it is needed by setting the TDM slots to
2.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/pcm3168a.c

@@ -411,9 +411,11 @@ static int pcm3168a_set_tdm_slot(struct snd_soc_dai *dai, unsigned int tx_mask,
 		return -EINVAL;
 	}
 
-	pcm3168a->tdm_slots = slots;
-	pcm3168a->tdm_mask[SNDRV_PCM_STREAM_PLAYBACK] = tx_mask;
-	pcm3168a->tdm_mask[SNDRV_PCM_STREAM_CAPTURE] = rx_mask;
+	if (pcm3168a->tdm_slots && pcm3168a->tdm_slots != slots) {
+		dev_err(component->dev, "Not matching slots %d vs %d\n",
+			pcm3168a->tdm_slots, slots);
+		return -EINVAL;
+	}
 
 	if (pcm3168a->slot_width && pcm3168a->slot_width != slot_width) {
 		dev_err(component->dev, "Not matching slot_width %d vs %d\n",
@@ -421,7 +423,11 @@ static int pcm3168a_set_tdm_slot(struct snd_soc_dai *dai, unsigned int tx_mask,
 		return -EINVAL;
 	}
 
+	pcm3168a->tdm_slots = slots;
 	pcm3168a->slot_width = slot_width;
+	pcm3168a->tdm_mask[SNDRV_PCM_STREAM_PLAYBACK] = tx_mask;
+	pcm3168a->tdm_mask[SNDRV_PCM_STREAM_CAPTURE] = rx_mask;
+
 	return 0;
 }
 
@@ -434,11 +440,10 @@ static int pcm3168a_hw_params(struct snd_pcm_substream *substream,
 	bool tx, master_mode;
 	u32 val, mask, shift, reg;
 	unsigned int rate, fmt, ratio, max_ratio;
-	unsigned int chan;
+	unsigned int tdm_slots;
 	int i, slot_width;
 
 	rate = params_rate(params);
-	chan = params_channels(params);
 
 	ratio = pcm3168a->sysclk / rate;
 
@@ -495,8 +500,20 @@ static int pcm3168a_hw_params(struct snd_pcm_substream *substream,
 		return -EINVAL;
 	}
 
-	/* for TDM */
-	if (chan > 2) {
+	if (pcm3168a->tdm_slots)
+		tdm_slots = pcm3168a->tdm_slots;
+	else
+		tdm_slots = params_channels(params);
+
+	/*
+	 * Switch the codec to TDM mode when more than 2 TDM slots are needed
+	 * for the stream.
+	 * If pcm3168a->tdm_slots is not set or set to more than 2 (8/6 usually)
+	 * then DIN1/DOUT1 is used in TDM mode.
+	 * If pcm3168a->tdm_slots is set to 2 then DIN1/2/3/4 and DOUT1/2/3 is
+	 * used in normal mode, no need to switch to TDM modes.
+	 */
+	if (tdm_slots > 2) {
 		switch (fmt) {
 		case PCM3168A_FMT_I2S:
 		case PCM3168A_FMT_DSP_A: