ASoC: es8328: Let device auto detect ratios in slave mode

In master mode, SCLK and LRCLK signals are generated by the CODEC when
any of the ADC/DAC are enabled. SCLK is derived from MCLK via a
programmable division set by BLK_DIV, LRCLK is derived from MCLK via
another programmable division set by ADCFsRatio/DACFsRatio.

In slave mode, SCLK and LRCLK signals are received as inputs and
supplied externally. LRCLK and SCLK must be synchronously derived from
MCLK with specific rates. The device can auto detect MCLK/LRCLK ratio
according to a predefined table. LRCLK/SCLK ratio is usually 64 (SCLK =
64 * LRCLK)

This commits adds support to let to device auto detect and decide which
ratio to use. The mclkdiv2 and BCLK_DIV ratio and put to zero.
Signed-off-by: Romain Perier <romain.perier@collabora.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/es8328.c

@@ -91,6 +91,7 @@ struct es8328_priv {
 	int mclkdiv2;
 	const struct snd_pcm_hw_constraint_list *sysclk_constraints;
 	const int *mclk_ratios;
+	bool master;
 	struct regulator_bulk_data supplies[ES8328_SUPPLY_NUM];
 };
 
@@ -469,7 +470,7 @@ static int es8328_startup(struct snd_pcm_substream *substream,
 	struct snd_soc_codec *codec = dai->codec;
 	struct es8328_priv *es8328 = snd_soc_codec_get_drvdata(codec);
 
-	if (es8328->sysclk_constraints)
+	if (es8328->master && es8328->sysclk_constraints)
 		snd_pcm_hw_constraint_list(substream->runtime, 0,
 				SNDRV_PCM_HW_PARAM_RATE,
 				es8328->sysclk_constraints);
@@ -488,27 +489,34 @@ static int es8328_hw_params(struct snd_pcm_substream *substream,
 	int wl;
 	int ratio;
 
-	if (!es8328->sysclk_constraints) {
-		dev_err(codec->dev, "No MCLK configured\n");
-		return -EINVAL;
-	}
-
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 		reg = ES8328_DACCONTROL2;
 	else
 		reg = ES8328_ADCCONTROL5;
 
-	for (i = 0; i < es8328->sysclk_constraints->count; i++)
-		if (es8328->sysclk_constraints->list[i] == params_rate(params))
-			break;
+	if (es8328->master) {
+		if (!es8328->sysclk_constraints) {
+			dev_err(codec->dev, "No MCLK configured\n");
+			return -EINVAL;
+		}
 
-	if (i == es8328->sysclk_constraints->count) {
-		dev_err(codec->dev, "LRCLK %d unsupported with current clock\n",
-			params_rate(params));
-		return -EINVAL;
+		for (i = 0; i < es8328->sysclk_constraints->count; i++)
+			if (es8328->sysclk_constraints->list[i] ==
+			    params_rate(params))
+				break;
+
+		if (i == es8328->sysclk_constraints->count) {
+			dev_err(codec->dev,
+				"LRCLK %d unsupported with current clock\n",
+				params_rate(params));
+			return -EINVAL;
+		}
+		ratio = es8328->mclk_ratios[i];
+	} else {
+		ratio = 0;
+		es8328->mclkdiv2 = 0;
 	}
 
-	ratio = es8328->mclk_ratios[i];
 	snd_soc_update_bits(codec, ES8328_MASTERMODE,
 			ES8328_MASTERMODE_MCLKDIV2,
 			es8328->mclkdiv2 ? ES8328_MASTERMODE_MCLKDIV2 : 0);
@@ -586,6 +594,7 @@ static int es8328_set_dai_fmt(struct snd_soc_dai *codec_dai,
 		unsigned int fmt)
 {
 	struct snd_soc_codec *codec = codec_dai->codec;
+	struct es8328_priv *es8328 = snd_soc_codec_get_drvdata(codec);
 	u8 dac_mode = 0;
 	u8 adc_mode = 0;
 
@@ -595,11 +604,13 @@ static int es8328_set_dai_fmt(struct snd_soc_dai *codec_dai,
 		snd_soc_update_bits(codec, ES8328_MASTERMODE,
 				    ES8328_MASTERMODE_MSC,
 				    ES8328_MASTERMODE_MSC);
+		es8328->master = true;
 		break;
 	case SND_SOC_DAIFMT_CBS_CFS:
 		/* Slave serial port mode */
 		snd_soc_update_bits(codec, ES8328_MASTERMODE,
 				    ES8328_MASTERMODE_MSC, 0);
+		es8328->master = false;
 		break;
 	default:
 		return -EINVAL;