ASoC: adau1761: Add PGA Slew time control

The PGA Slew Time control allows to configure the rate with which the PGA
gain control ramps up/down to the target setting.

The PGA slew control is done via the ALC Control 0 register. There are 2
bits on that reg, that control PGA slew time, while the other bits control
parts of the ALC (automatic level control) block.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926115012.24049-1-alexandru.ardelean@analog.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/adau1761.c

@@ -28,6 +28,7 @@
 #define ADAU1761_REC_MIXER_RIGHT1	0x400d
 #define ADAU1761_LEFT_DIFF_INPUT_VOL	0x400e
 #define ADAU1761_RIGHT_DIFF_INPUT_VOL	0x400f
+#define ADAU1761_ALC_CTRL0		0x4011
 #define ADAU1761_PLAY_LR_MIXER_LEFT	0x4020
 #define ADAU1761_PLAY_MIXER_LEFT0	0x401c
 #define ADAU1761_PLAY_MIXER_LEFT1	0x401d
@@ -71,6 +72,7 @@ static const struct reg_default adau1761_reg_defaults[] = {
 	{ ADAU1761_REC_MIXER_RIGHT0,		0x00 },
 	{ ADAU1761_REC_MIXER_RIGHT1,		0x00 },
 	{ ADAU1761_LEFT_DIFF_INPUT_VOL,		0x00 },
+	{ ADAU1761_ALC_CTRL0,			0x00 },
 	{ ADAU1761_RIGHT_DIFF_INPUT_VOL,	0x00 },
 	{ ADAU1761_PLAY_LR_MIXER_LEFT,		0x00 },
 	{ ADAU1761_PLAY_MIXER_LEFT0,		0x00 },
@@ -147,6 +149,21 @@ static SOC_VALUE_ENUM_SINGLE_DECL(adau1761_capture_bias_enum,
 		ADAU17X1_REC_POWER_MGMT, 1, 0x3, adau1761_bias_select_text,
 		adau1761_bias_select_values);
 
+static const unsigned int adau1761_pga_slew_time_values[] = {
+	3, 0, 1, 2,
+};
+
+static const char * const adau1761_pga_slew_time_text[] = {
+	"Off",
+	"24 ms",
+	"48 ms",
+	"96 ms",
+};
+
+static SOC_VALUE_ENUM_SINGLE_DECL(adau1761_pga_slew_time_enum,
+		ADAU1761_ALC_CTRL0, 6, 0x3, adau1761_pga_slew_time_text,
+		adau1761_pga_slew_time_values);
+
 static const struct snd_kcontrol_new adau1761_jack_detect_controls[] = {
 	SOC_SINGLE("Speaker Auto-mute Switch", ADAU1761_DIGMIC_JACKDETECT,
 		4, 1, 0),
@@ -161,6 +178,8 @@ static const struct snd_kcontrol_new adau1761_differential_mode_controls[] = {
 
 	SOC_DOUBLE_R_TLV("PGA Boost Capture Volume", ADAU1761_REC_MIXER_LEFT1,
 		ADAU1761_REC_MIXER_RIGHT1, 3, 2, 0, adau1761_pga_boost_tlv),
+
+	SOC_ENUM("PGA Capture Slew Time", adau1761_pga_slew_time_enum),
 };
 
 static const struct snd_kcontrol_new adau1761_single_mode_controls[] = {
@@ -632,6 +651,7 @@ static bool adau1761_readable_register(struct device *dev, unsigned int reg)
 	case ADAU1761_DEJITTER:
 	case ADAU1761_CLK_ENABLE0:
 	case ADAU1761_CLK_ENABLE1:
+	case ADAU1761_ALC_CTRL0:
 		return true;
 	default:
 		break;