[PATCH v4 3/9] ASoC: sun4i-i2s: Add regmap field to sign extend sample

[codekipper@gmail.com]

From: Marcus Cooper <codekipper@gmail.com>

On the newer SoCs this is set by default to transfer a 0 after
each sample in each slot. However the platform that this driver
was developed on had the default setting where it padded the
audio gain with zeros. This isn't a problem whilst we have only
support for 16bit audio but with larger sample resolution rates
in the pipeline then it should be fixed to also pad. Without this
the audio gets distorted.

Signed-off-by: Marcus Cooper <codekipper@gmail.com>
---
 sound/soc/sunxi/sun4i-i2s.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
index fd7c37596f21..e2961d8f6e8c 100644
--- a/sound/soc/sunxi/sun4i-i2s.c
+++ b/sound/soc/sunxi/sun4i-i2s.c
@@ -134,6 +134,7 @@
  * @field_fmt_bclk: regmap field to set clk polarity.
  * @field_fmt_lrclk: regmap field to set frame polarity.
  * @field_fmt_mode: regmap field to set the operational mode.
+ * @field_fmt_sext: regmap field to set the sign extension.
  * @field_txchanmap: location of the tx channel mapping register.
  * @field_rxchanmap: location of the rx channel mapping register.
  * @field_txchansel: location of the tx channel select bit fields.
@@ -159,6 +160,7 @@ struct sun4i_i2s_quirks {
 	struct reg_field		field_fmt_bclk;
 	struct reg_field		field_fmt_lrclk;
 	struct reg_field		field_fmt_mode;
+	struct reg_field		field_fmt_sext;
 	struct reg_field		field_txchanmap;
 	struct reg_field		field_rxchanmap;
 	struct reg_field		field_txchansel;
@@ -183,6 +185,7 @@ struct sun4i_i2s {
 	struct regmap_field	*field_fmt_bclk;
 	struct regmap_field	*field_fmt_lrclk;
 	struct regmap_field	*field_fmt_mode;
+	struct regmap_field	*field_fmt_sext;
 	struct regmap_field	*field_txchanmap;
 	struct regmap_field	*field_rxchanmap;
 	struct regmap_field	*field_txchansel;
@@ -342,6 +345,9 @@ static int sun4i_i2s_set_clk_rate(struct snd_soc_dai *dai,
 				   SUN8I_I2S_FMT0_LRCK_PERIOD_MASK,
 				   SUN8I_I2S_FMT0_LRCK_PERIOD(32));
 
+	/* Set sign extension to pad out LSB with 0 */
+	regmap_field_write(i2s->field_fmt_sext, 0);
+
 	return 0;
 }
 
@@ -887,6 +893,7 @@ static const struct sun4i_i2s_quirks sun4i_a10_i2s_quirks = {
 	.field_fmt_lrclk	= REG_FIELD(SUN4I_I2S_FMT0_REG, 7, 7),
 	.has_slave_select_bit	= true,
 	.field_fmt_mode		= REG_FIELD(SUN4I_I2S_FMT0_REG, 0, 1),
+	.field_fmt_sext		= REG_FIELD(SUN4I_I2S_FMT1_REG, 8, 8),
 	.field_txchanmap	= REG_FIELD(SUN4I_I2S_TX_CHAN_MAP_REG, 0, 31),
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
@@ -904,6 +911,7 @@ static const struct sun4i_i2s_quirks sun6i_a31_i2s_quirks = {
 	.field_fmt_lrclk	= REG_FIELD(SUN4I_I2S_FMT0_REG, 7, 7),
 	.has_slave_select_bit	= true,
 	.field_fmt_mode		= REG_FIELD(SUN4I_I2S_FMT0_REG, 0, 1),
+	.field_fmt_sext		= REG_FIELD(SUN4I_I2S_FMT1_REG, 8, 8),
 	.field_txchanmap	= REG_FIELD(SUN4I_I2S_TX_CHAN_MAP_REG, 0, 31),
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
@@ -944,6 +952,7 @@ static const struct sun4i_i2s_quirks sun8i_h3_i2s_quirks = {
 	.field_fmt_bclk		= REG_FIELD(SUN4I_I2S_FMT0_REG, 7, 7),
 	.field_fmt_lrclk	= REG_FIELD(SUN4I_I2S_FMT0_REG, 19, 19),
 	.field_fmt_mode		= REG_FIELD(SUN4I_I2S_CTRL_REG, 4, 5),
+	.field_fmt_sext		= REG_FIELD(SUN4I_I2S_FMT1_REG, 4, 5),
 	.field_txchanmap	= REG_FIELD(SUN8I_I2S_TX_CHAN_MAP_REG, 0, 31),
 	.field_rxchanmap	= REG_FIELD(SUN8I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN8I_I2S_TX_CHAN_SEL_REG, 0, 2),
@@ -1006,6 +1015,12 @@ static int sun4i_i2s_init_regmap_fields(struct device *dev,
 	if (IS_ERR(i2s->field_fmt_mode))
 		return PTR_ERR(i2s->field_fmt_mode);
 
+	i2s->field_fmt_sext =
+			devm_regmap_field_alloc(dev, i2s->regmap,
+						i2s->variant->field_fmt_sext);
+	if (IS_ERR(i2s->field_fmt_sext))
+		return PTR_ERR(i2s->field_fmt_sext);
+
 	i2s->field_txchanmap =
 			devm_regmap_field_alloc(dev, i2s->regmap,
 						i2s->variant->field_txchanmap);
-- 
2.21.0