ASoC: davinci-mcasp: Add support for I2S format

The FS needs to be inverted in McASP compared to other supported formats.
Use a flag to indicate if the FS needs to be inverted.
At the same time fail when non supported format is asked since the default
case was anyways configuring McASP to a not valid format.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/davinci/davinci-mcasp.c

@@ -273,6 +273,7 @@ static int davinci_mcasp_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 	int ret = 0;
 	u32 data_delay;
 	bool fs_pol_rising;
+	bool inv_fs = false;
 
 	pm_runtime_get_sync(mcasp->dev);
 	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
@@ -291,14 +292,19 @@ static int davinci_mcasp_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 		/* No delay after FS */
 		data_delay = 0;
 		break;
-	default:
+	case SND_SOC_DAIFMT_I2S:
 		/* configure a full-word SYNC pulse (LRCLK) */
 		mcasp_set_bits(mcasp, DAVINCI_MCASP_TXFMCTL_REG, FSXDUR);
 		mcasp_set_bits(mcasp, DAVINCI_MCASP_RXFMCTL_REG, FSRDUR);
 
 		/* 1st data bit occur one ACLK cycle after the frame sync */
 		data_delay = 1;
+		/* FS need to be inverted */
+		inv_fs = true;
 		break;
+	default:
+		ret = -EINVAL;
+		goto out;
 	}
 
 	mcasp_mod_bits(mcasp, DAVINCI_MCASP_TXFMT_REG, FSXDLY(data_delay),
@@ -379,6 +385,9 @@ static int davinci_mcasp_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 		goto out;
 	}
 
+	if (inv_fs)
+		fs_pol_rising = !fs_pol_rising;
+
 	if (fs_pol_rising) {
 		mcasp_clr_bits(mcasp, DAVINCI_MCASP_TXFMCTL_REG, FSXPOL);
 		mcasp_clr_bits(mcasp, DAVINCI_MCASP_RXFMCTL_REG, FSRPOL);