ASoC: tlv320aic3x: Add TDM support

TDM support is achieved using DSP transfer mode and setting a
programmable offset which specifies where data begins with
respect to the frame sync.

It requires 256-clock mode if CODEC is master (not currently
supported in the driver). No additional dependency if CODEC
is slave.

Signed-off-by: Peter Ujfalusi <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/codecs/tlv320aic3x.c

···
 	struct aic3x_disable_nb disable_nb[AIC3X_NUM_SUPPLIES];
 	struct aic3x_setup_data *setup;
 	unsigned int sysclk;
+	unsigned int dai_fmt;
+	unsigned int tdm_delay;
 	struct list_head list;
 	int master;
 	int gpio_reset;
···
 	return 0;
 }
 
+static int aic3x_prepare(struct snd_pcm_substream *substream,
+			 struct snd_soc_dai *dai)
+{
+	struct snd_soc_codec *codec = dai->codec;
+	struct aic3x_priv *aic3x = snd_soc_codec_get_drvdata(codec);
+	int delay = 0;
+
+	/* TDM slot selection only valid in DSP_A/_B mode */
+	if (aic3x->dai_fmt == SND_SOC_DAIFMT_DSP_A)
+		delay += (aic3x->tdm_delay + 1);
+	else if (aic3x->dai_fmt == SND_SOC_DAIFMT_DSP_B)
+		delay += aic3x->tdm_delay;
+
+	/* Configure data delay */
+	snd_soc_write(codec, AIC3X_ASD_INTF_CTRLC, aic3x->tdm_delay);
+
+	return 0;
+}
+
 static int aic3x_mute(struct snd_soc_dai *dai, int mute)
 {
 	struct snd_soc_codec *codec = dai->codec;
···
 	struct snd_soc_codec *codec = codec_dai->codec;
 	struct aic3x_priv *aic3x = snd_soc_codec_get_drvdata(codec);
 	u8 iface_areg, iface_breg;
-	int delay = 0;
 
 	iface_areg = snd_soc_read(codec, AIC3X_ASD_INTF_CTRLA) & 0x3f;
 	iface_breg = snd_soc_read(codec, AIC3X_ASD_INTF_CTRLB) & 0x3f;
···
 	case (SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF):
 		break;
 	case (SND_SOC_DAIFMT_DSP_A | SND_SOC_DAIFMT_IB_NF):
-		delay = 1;
 	case (SND_SOC_DAIFMT_DSP_B | SND_SOC_DAIFMT_IB_NF):
 		iface_breg |= (0x01 << 6);
 		break;
···
 		return -EINVAL;
 	}
 
+	aic3x->dai_fmt = fmt & SND_SOC_DAIFMT_FORMAT_MASK;
+
 	/* set iface */
 	snd_soc_write(codec, AIC3X_ASD_INTF_CTRLA, iface_areg);
 	snd_soc_write(codec, AIC3X_ASD_INTF_CTRLB, iface_breg);
-	snd_soc_write(codec, AIC3X_ASD_INTF_CTRLC, delay);
+
+	return 0;
+}
+
+static int aic3x_set_dai_tdm_slot(struct snd_soc_dai *codec_dai,
+				  unsigned int tx_mask, unsigned int rx_mask,
+				  int slots, int slot_width)
+{
+	struct snd_soc_codec *codec = codec_dai->codec;
+	struct aic3x_priv *aic3x = snd_soc_codec_get_drvdata(codec);
+	unsigned int lsb;
+
+	if (tx_mask != rx_mask) {
+		dev_err(codec->dev, "tx and rx masks must be symmetric\n");
+		return -EINVAL;
+	}
+
+	if (unlikely(!tx_mask)) {
+		dev_err(codec->dev, "tx and rx masks need to be non 0\n");
+		return -EINVAL;
+	}
+
+	/* TDM based on DSP mode requires slots to be adjacent */
+	lsb = __ffs(tx_mask);
+	if ((lsb + 1) != __fls(tx_mask)) {
+		dev_err(codec->dev, "Invalid mask, slots must be adjacent\n");
+		return -EINVAL;
+	}
+
+	aic3x->tdm_delay = lsb * slot_width;
+
+	/* DOUT in high-impedance on inactive bit clocks */
+	snd_soc_update_bits(codec, AIC3X_ASD_INTF_CTRLA,
+			    DOUT_TRISTATE, DOUT_TRISTATE);
 
 	return 0;
 }
···
 
 static const struct snd_soc_dai_ops aic3x_dai_ops = {
 	.hw_params	= aic3x_hw_params,
+	.prepare	= aic3x_prepare,
 	.digital_mute	= aic3x_mute,
 	.set_sysclk	= aic3x_set_dai_sysclk,
 	.set_fmt	= aic3x_set_dai_fmt,
+	.set_tdm_slot	= aic3x_set_dai_tdm_slot,
 };
 
 static struct snd_soc_dai_driver aic3x_dai = {

sound/soc/codecs/tlv320aic3x.h

···
 /* Audio serial data interface control register A bits */
 #define BIT_CLK_MASTER          0x80
 #define WORD_CLK_MASTER         0x40
+#define DOUT_TRISTATE		0x20
 
 /* Codec Datapath setup register 7 */
 #define FSREF_44100		(1 << 7)