ASoC: fsl_sai: Add PDM daifmt support

PDM format is used for 1-bit stream, so clear the FBT and SYWD,
and the each dataline only has one channel data.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1655451877-16382-2-git-send-email-shengjiu.wang@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/fsl_sai.c

@@ -224,6 +224,7 @@ static int fsl_sai_set_dai_fmt_tr(struct snd_soc_dai *cpu_dai,
 	if (!sai->is_lsb_first)
 		val_cr4 |= FSL_SAI_CR4_MF;
 
+	sai->is_pdm_mode = false;
 	/* DAI mode */
 	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
 	case SND_SOC_DAIFMT_I2S:
@@ -262,6 +263,11 @@ static int fsl_sai_set_dai_fmt_tr(struct snd_soc_dai *cpu_dai,
 		val_cr2 |= FSL_SAI_CR2_BCP;
 		sai->is_dsp_mode = true;
 		break;
+	case SND_SOC_DAIFMT_PDM:
+		val_cr2 |= FSL_SAI_CR2_BCP;
+		val_cr4 &= ~FSL_SAI_CR4_MF;
+		sai->is_pdm_mode = true;
+		break;
 	case SND_SOC_DAIFMT_RIGHT_J:
 		/* To be done */
 	default:
@@ -470,6 +476,13 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 
 	pins = DIV_ROUND_UP(channels, slots);
 
+	/*
+	 * PDM mode, channels are independent
+	 * each channels are on one dataline/FIFO.
+	 */
+	if (sai->is_pdm_mode)
+		pins = channels;
+
 	if (!sai->is_consumer_mode) {
 		if (sai->bclk_ratio)
 			ret = fsl_sai_set_bclk(cpu_dai, tx,
@@ -492,13 +505,13 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 		}
 	}
 
-	if (!sai->is_dsp_mode)
+	if (!sai->is_dsp_mode && !sai->is_pdm_mode)
 		val_cr4 |= FSL_SAI_CR4_SYWD(slot_width);
 
 	val_cr5 |= FSL_SAI_CR5_WNW(slot_width);
 	val_cr5 |= FSL_SAI_CR5_W0W(slot_width);
 
-	if (sai->is_lsb_first)
+	if (sai->is_lsb_first || sai->is_pdm_mode)
 		val_cr5 |= FSL_SAI_CR5_FBT(0);
 	else
 		val_cr5 |= FSL_SAI_CR5_FBT(word_width - 1);

sound/soc/fsl/fsl_sai.h

@@ -259,6 +259,7 @@ struct fsl_sai {
 	bool is_consumer_mode;
 	bool is_lsb_first;
 	bool is_dsp_mode;
+	bool is_pdm_mode;
 	bool synchronous[2];
 
 	unsigned int mclk_id[2];