ASoC: tas571x: add input channel mixer for TAS5717/19

Add channel 1 and 2 input mixer registers and the related ALSA mixer
controls for TAS5717/19 chips.

The mixer control coefficients on the chip are linear in the range
-3.99999 to +3.99999, encoded in 3.23 number format.
In this patch the mixer controls are limited to 128 values
from 0.0 to 1.0 in 1/64 steps.
Signed-off-by: Petr Kulhavy <brain@jikos.cz>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/tas571x.c

@@ -64,6 +64,10 @@ static int tas571x_register_size(struct tas571x_private *priv, unsigned int reg)
 	case TAS571X_INPUT_MUX_REG:
 	case TAS571X_CH4_SRC_SELECT_REG:
 	case TAS571X_PWM_MUX_REG:
+	case TAS5717_CH1_RIGHT_CH_MIX_REG:
+	case TAS5717_CH1_LEFT_CH_MIX_REG:
+	case TAS5717_CH2_LEFT_CH_MIX_REG:
+	case TAS5717_CH2_RIGHT_CH_MIX_REG:
 		return 4;
 	default:
 		return 1;
@@ -397,6 +401,16 @@ static const struct snd_kcontrol_new tas5711_controls[] = {
 		   TAS571X_SOFT_MUTE_REG,
 		   TAS571X_SOFT_MUTE_CH1_SHIFT, TAS571X_SOFT_MUTE_CH2_SHIFT,
 		   1, 1),
+
+	SOC_DOUBLE_R_RANGE("CH1 Mixer Volume",
+			   TAS5717_CH1_LEFT_CH_MIX_REG,
+			   TAS5717_CH1_RIGHT_CH_MIX_REG,
+			   16, 0, 0x80, 0),
+
+	SOC_DOUBLE_R_RANGE("CH2 Mixer Volume",
+			   TAS5717_CH2_LEFT_CH_MIX_REG,
+			   TAS5717_CH2_RIGHT_CH_MIX_REG,
+			   16, 0, 0x80, 0),
 };
 
 static const struct regmap_range tas571x_readonly_regs_range[] = {
@@ -520,6 +534,10 @@ static const struct reg_default tas5717_reg_defaults[] = {
 	{ 0x08, 0x00c0 },
 	{ 0x09, 0x00c0 },
 	{ 0x1b, 0x82 },
+	{ TAS5717_CH1_RIGHT_CH_MIX_REG, 0x0 },
+	{ TAS5717_CH1_LEFT_CH_MIX_REG, 0x800000},
+	{ TAS5717_CH2_LEFT_CH_MIX_REG, 0x0 },
+	{ TAS5717_CH2_RIGHT_CH_MIX_REG, 0x800000},
 };
 
 static const struct regmap_config tas5717_regmap_config = {

sound/soc/codecs/tas571x.h

@@ -87,4 +87,9 @@
 #define TAS5717_CH3_BQ0_REG		0x5e
 #define TAS5717_CH3_BQ1_REG		0x5f
 
+#define TAS5717_CH1_RIGHT_CH_MIX_REG	0x72
+#define TAS5717_CH1_LEFT_CH_MIX_REG	0x73
+#define TAS5717_CH2_LEFT_CH_MIX_REG	0x76
+#define TAS5717_CH2_RIGHT_CH_MIX_REG	0x77
+
 #endif /* _TAS571X_H */