[PATCH 6/6] ASoC: codecs: aw88166: make volume control usable

[Aaron Kling via B4 Relay <devnull+webgeek1234.gmail.com@kernel.org>]

From: Aaron Kling <webgeek1234@gmail.com>

- Invert the value to match userspace expectations (in the hardware,
  positive numbers represent negative dB attenuation)
- Provide TLV metadata for the dB scale (and divide the raw values by 2
  as the excessive precision used by HW is not representable in TLV)
- Do not unnecessarily reset the volume while switching profiles
- Simplify aw88166_dev_set_volume using regmap_update_bits
- Do not add the initial volume from the profile to the requested volume
  as that would throw off the dB mapping (if a lower max limit is
  desired, it can be set in the UCM profile in userspace)

With this change, it's actually possible to use this hardware volume
control as PlaybackVolume in an ALSA UCM profile.

Fixes: 94e412c28e61 ("ASoC: codecs: Add aw88166 amplifier driver")
Signed-off-by: Aaron Kling <webgeek1234@gmail.com>
---
 sound/soc/codecs/aw88166.c | 47 ++++++++++++++++++++++------------------------
 sound/soc/codecs/aw88166.h | 15 ++++++++++++++-
 2 files changed, 36 insertions(+), 26 deletions(-)

diff --git a/sound/soc/codecs/aw88166.c b/sound/soc/codecs/aw88166.c
index 6b98864de81a9..3e87be33f4908 100644
--- a/sound/soc/codecs/aw88166.c
+++ b/sound/soc/codecs/aw88166.c
@@ -17,6 +17,7 @@
 #include <linux/regmap.h>
 #include <sound/soc.h>
 #include <sound/pcm_params.h>
+#include <sound/tlv.h>
 #include "aw88166.h"
 #include "aw88395/aw88395_device.h"
 
@@ -645,26 +646,12 @@ static int aw_dev_dsp_check(struct aw_device *aw_dev)
 	return ret;
 }
 
-static int aw_dev_set_volume(struct aw_device *aw_dev, unsigned int value)
+static void aw_dev_set_volume(struct aw_device *aw_dev, unsigned int value)
 {
-	struct aw_volume_desc *vol_desc = &aw_dev->volume_desc;
-	unsigned int reg_value;
-	u16 real_value;
-	int ret;
-
-	real_value = min((value + vol_desc->init_volume), (unsigned int)AW88166_MUTE_VOL);
-
-	ret = regmap_read(aw_dev->regmap, AW88166_SYSCTRL2_REG, &reg_value);
-	if (ret)
-		return ret;
-
-	dev_dbg(aw_dev->dev, "value 0x%x , reg:0x%x", value, real_value);
+	unsigned int volume = min(value, (unsigned int)AW88166_MUTE_VOL);
 
-	real_value = (real_value << AW88166_VOL_START_BIT) | (reg_value & AW88166_VOL_MASK);
-
-	ret = regmap_write(aw_dev->regmap, AW88166_SYSCTRL2_REG, real_value);
-
-	return ret;
+	regmap_update_bits(aw_dev->regmap, AW88166_SYSCTRL2_REG,
+		~AW88166_VOL_MASK, DB_TO_REG_VAL(volume));
 }
 
 static void aw88166_dev_mute(struct aw_device *aw_dev, bool is_mute)
@@ -1548,7 +1535,8 @@ static int aw88166_volume_get(struct snd_kcontrol *kcontrol,
 	struct aw88166 *aw88166 = snd_soc_component_get_drvdata(codec);
 	struct aw_volume_desc *vol_desc = &aw88166->aw_pa->volume_desc;
 
-	ucontrol->value.integer.value[0] = vol_desc->ctl_volume;
+	ucontrol->value.integer.value[0] =
+		(AW88166_MUTE_VOL - vol_desc->ctl_volume) / 2;
 
 	return 0;
 }
@@ -1561,12 +1549,13 @@ static int aw88166_volume_set(struct snd_kcontrol *kcontrol,
 	struct aw_volume_desc *vol_desc = &aw88166->aw_pa->volume_desc;
 	struct soc_mixer_control *mc =
 		(struct soc_mixer_control *)kcontrol->private_value;
-	int value;
+	int value = ucontrol->value.integer.value[0];
 
-	value = ucontrol->value.integer.value[0];
 	if (value < mc->min || value > mc->max)
 		return -EINVAL;
 
+	value = AW88166_MUTE_VOL - (value * 2);
+
 	if (vol_desc->ctl_volume != value) {
 		vol_desc->ctl_volume = value;
 		aw_dev_set_volume(aw88166->aw_pa, vol_desc->ctl_volume);
@@ -1691,10 +1680,18 @@ static int aw88166_request_firmware_file(struct aw88166 *aw88166)
 	return ret;
 }
 
+/*
+ * The field contains 4 bits in units of 6dB + 6 bits in units of 0.125dB
+ * which is too precise for TLV (!) so we have to multiply the scale by 2.
+ *
+ * The range is clamped at -90dB to prevent overflowing the 4-bit part.
+ */
+static const DECLARE_TLV_DB_SCALE(volume_tlv, -9000, 25, 0);
+
 static const struct snd_kcontrol_new aw88166_controls[] = {
-	SOC_SINGLE_EXT("PCM Playback Volume", AW88166_SYSCTRL2_REG,
-		6, AW88166_MUTE_VOL, 0, aw88166_volume_get,
-		aw88166_volume_set),
+	SOC_SINGLE_EXT_TLV("PCM Playback Volume", AW88166_SYSCTRL2_REG,
+		6, AW88166_CTL_MAX_VOL, 1,
+		aw88166_volume_get, aw88166_volume_set, volume_tlv),
 	SOC_SINGLE_EXT("Calib", 0, 0, AW88166_CALI_RE_MAX, 0,
 		aw88166_re_get, aw88166_re_set),
 	AW88166_PROFILE_EXT("AW88166 Profile Set", aw88166_profile_info,
@@ -1812,7 +1809,7 @@ static int aw88166_init(struct aw88166 *aw88166, struct i2c_client *i2c, struct
 	aw_dev->channel = AW88166_DEV_DEFAULT_CH;
 	aw_dev->fw_status = AW88166_DEV_FW_FAILED;
 
-	aw_dev->volume_desc.ctl_volume = AW88166_VOL_DEFAULT_VALUE;
+	aw_dev->volume_desc.ctl_volume = AW88166_CTL_DEFAULT_VOL;
 
 	aw88166_parse_channel_dt(aw88166);
 
diff --git a/sound/soc/codecs/aw88166.h b/sound/soc/codecs/aw88166.h
index b8dbfe0f307c4..c0303340812cf 100644
--- a/sound/soc/codecs/aw88166.h
+++ b/sound/soc/codecs/aw88166.h
@@ -112,6 +112,9 @@
 #define AW88166_REG_MAX		(0x7E)
 #define AW88166_MUTE_VOL		(1023)
 
+#define AW88166_VOL_6DB_START		(6)
+
+
 #define AW88166_DSP_CFG_ADDR		(0x9B00)
 #define AW88166_DSP_REG_CFG_ADPZ_RA	(0x9B68)
 #define AW88166_DSP_FW_ADDR		(0x8980)
@@ -590,7 +593,8 @@
 #define AW88166_CALI_RE_MAX			(15000)
 #define AW88166_CALI_RE_MIN			(4000)
 #define AW88166_VOLUME_STEP_DB			(64)
-#define AW88166_VOL_DEFAULT_VALUE		(0)
+#define AW88166_CTL_MAX_VOL			(AW88166_MUTE_VOL / 2)
+#define AW88166_CTL_DEFAULT_VOL			(AW88166_CTL_MAX_VOL / 2)
 #define AW88166_DSP_RE_TO_SHOW_RE(re, shift)	(((re) * (1000)) >> (shift))
 #define AW88166_SHOW_RE_TO_DSP_RE(re, shift)	(((re) << shift) / (1000))
 
@@ -619,6 +623,15 @@
 			SNDRV_PCM_FMTBIT_S24_LE | \
 			SNDRV_PCM_FMTBIT_S32_LE)
 
+#define AW88166_REG_TO_DB		(0x3f)
+
+#define REG_VAL_TO_DB(value)		((((value) >> AW88166_VOL_6DB_START) * \
+					AW88166_VOLUME_STEP_DB) + \
+					((value) & AW88166_REG_TO_DB))
+#define DB_TO_REG_VAL(value)		((((value) / AW88166_VOLUME_STEP_DB) << \
+					AW88166_VOL_6DB_START) + \
+					((value) % AW88166_VOLUME_STEP_DB))
+
 #define AW88166_PROFILE_EXT(xname, profile_info, profile_get, profile_set) \
 { \
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER, \

-- 
2.54.0