ASoC: es8328: Add support for slave mode

Currently, the function that changes the DAI format only supports master
mode. Trying to use a slave mode exits the function with -EINVAL and
leave the codec misconfigured. This commits adds support for enabling
the slave mode.

Signed-off-by: Romain Perier <romain.perier@collabora.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/sound/soc/codecs/es8328.c b/sound/soc/codecs/es8328.c
index 37722194..3f84fbd 100644
--- a/sound/soc/codecs/es8328.c
+++ b/sound/soc/codecs/es8328.c
@@ -589,9 +589,21 @@ static int es8328_set_dai_fmt(struct snd_soc_dai *codec_dai,
 	u8 dac_mode = 0;
 	u8 adc_mode = 0;
 
-	/* set master/slave audio interface */
-	if ((fmt & SND_SOC_DAIFMT_MASTER_MASK) != SND_SOC_DAIFMT_CBM_CFM)
+	switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
+	case SND_SOC_DAIFMT_CBM_CFM:
+		/* Master serial port mode, with BCLK generated automatically */
+		snd_soc_update_bits(codec, ES8328_MASTERMODE,
+				    ES8328_MASTERMODE_MSC,
+				    ES8328_MASTERMODE_MSC);
+		break;
+	case SND_SOC_DAIFMT_CBS_CFS:
+		/* Slave serial port mode */
+		snd_soc_update_bits(codec, ES8328_MASTERMODE,
+				    ES8328_MASTERMODE_MSC, 0);
+		break;
+	default:
 		return -EINVAL;
+	}
 
 	/* interface format */
 	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
@@ -620,10 +632,6 @@ static int es8328_set_dai_fmt(struct snd_soc_dai *codec_dai,
 	snd_soc_update_bits(codec, ES8328_ADCCONTROL4,
 			ES8328_ADCCONTROL4_ADCFORMAT_MASK, adc_mode);
 
-	/* Master serial port mode, with BCLK generated automatically */
-	snd_soc_update_bits(codec, ES8328_MASTERMODE,
-			ES8328_MASTERMODE_MSC, ES8328_MASTERMODE_MSC);
-
 	return 0;
 }