ASoC: OMAP: Add support for mono audio links in McBSP DAI

Patch adds support for mono audio links so that McBSP DAI can operate with
real mono codecs. In I2S, the signalling remains the same but only first
frame (left channel) is transmitting audio data and second frame having null
data. In DSP_A, only first frame is transmitted.

Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/omap/omap-mcbsp.c

@@ -203,7 +203,7 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 	struct omap_mcbsp_data *mcbsp_data = to_mcbsp(cpu_dai->private_data);
 	struct omap_mcbsp_reg_cfg *regs = &mcbsp_data->regs;
 	int dma, bus_id = mcbsp_data->bus_id, id = cpu_dai->id;
-	int wlen;
+	int wlen, channels;
 	unsigned long port;
 
 	if (cpu_class_is_omap1()) {
@@ -232,12 +232,17 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 		return 0;
 	}
 
-	switch (params_channels(params)) {
+	channels = params_channels(params);
+	switch (channels) {
 	case 2:
-		/* Set 1 word per (McBPSP) frame and use dual-phase frames */
-		regs->rcr2	|= RFRLEN2(1 - 1) | RPHASE;
+		/* Use dual-phase frames */
+		regs->rcr2	|= RPHASE;
+		regs->xcr2	|= XPHASE;
+	case 1:
+		/* Set 1 word per (McBSP) frame */
+		regs->rcr2	|= RFRLEN2(1 - 1);
 		regs->rcr1	|= RFRLEN1(1 - 1);
-		regs->xcr2	|= XFRLEN2(1 - 1) | XPHASE;
+		regs->xcr2	|= XFRLEN2(1 - 1);
 		regs->xcr1	|= XFRLEN1(1 - 1);
 		break;
 	default:
@@ -266,8 +271,8 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 		regs->srgr1	|= FWID(wlen - 1);
 		break;
 	case SND_SOC_DAIFMT_DSP_A:
-		regs->srgr2	|= FPER(wlen * 2 - 1);
-		regs->srgr1	|= FWID(wlen * 2 - 2);
+		regs->srgr2	|= FPER(wlen * channels - 1);
+		regs->srgr1	|= FWID(wlen * channels - 2);
 		break;
 	}
 
@@ -457,13 +462,13 @@ static int omap_mcbsp_dai_set_dai_sysclk(struct snd_soc_dai *cpu_dai,
 	.name = "omap-mcbsp-dai-"#link_id,			\
 	.id = (link_id),					\
 	.playback = {						\
-		.channels_min = 2,				\
+		.channels_min = 1,				\
 		.channels_max = 2,				\
 		.rates = OMAP_MCBSP_RATES,			\
 		.formats = SNDRV_PCM_FMTBIT_S16_LE,		\
 	},							\
 	.capture = {						\
-		.channels_min = 2,				\
+		.channels_min = 1,				\
 		.channels_max = 2,				\
 		.rates = OMAP_MCBSP_RATES,			\
 		.formats = SNDRV_PCM_FMTBIT_S16_LE,		\