ASoC: SDCA: support Q7.8 volume format

The SDCA specification uses Q7.8 volume format.
This patch adds a field to indicate whether it is SDCA volume control
and supports the volume settings.

Signed-off-by: Shuming Fan <shumingf@realtek.com>

Author: shumingfan

include/sound/soc.h

@@ -1220,6 +1220,7 @@ struct soc_mixer_control {
 	/* Limited maximum value specified as presented through the control */
 	int platform_max;
 	int reg, rreg;
+	int step;
 	unsigned int shift, rshift;
 	u32 num_channels;
 	unsigned int sign_bit;

sound/soc/sdca/sdca_asoc.c

@@ -786,6 +786,126 @@ int sdca_asoc_populate_dapm(struct device *dev, struct sdca_function_data *funct
 }
 EXPORT_SYMBOL_NS(sdca_asoc_populate_dapm, "SND_SOC_SDCA");
 
+static int sdca_soc_vol_reg_to_ctl(struct soc_mixer_control *mc, unsigned int reg_val,
+				unsigned int mask, int max)
+{
+	int val = reg_val;
+
+	if (WARN_ON(!mc->step))
+		return -EINVAL;
+
+	if (mc->sign_bit)
+		val = sign_extend32(val, mc->sign_bit);
+
+	val = (((val * 100) >> 8) / mc->step);
+
+	val -= mc->min;
+
+	if (mc->invert)
+		val = max - val;
+
+	return val & mask;
+}
+
+static unsigned int sdca_soc_vol_ctl_to_reg(struct soc_mixer_control *mc, int val,
+					 unsigned int mask, int max)
+{
+	unsigned int reg_val, ret_val;
+
+	if (WARN_ON(!mc->step))
+		return -EINVAL;
+
+	if (mc->invert)
+		val = max - val;
+
+	reg_val = val + mc->min;
+
+	ret_val = (((int)(((int)reg_val * mc->step) << 8)) / 100);
+
+	return ret_val & mask;
+}
+
+static int sdca_soc_put_volsw(struct snd_kcontrol *kcontrol,
+		      struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_mixer_control *mc =
+		(struct soc_mixer_control *)kcontrol->private_value;
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	int max = mc->max - mc->min;
+	unsigned int val1, val2;
+	bool double_r = false;
+	unsigned int mask;
+	int ret;
+
+	if (mc->sign_bit)
+		mask = GENMASK(mc->sign_bit, 0);
+	else
+		mask = GENMASK(fls(mc->max) - 1, 0);
+
+	val1 = sdca_soc_vol_ctl_to_reg(mc, ucontrol->value.integer.value[0], mask, max);
+
+	if (snd_soc_volsw_is_stereo(mc)) {
+		if (mc->reg == mc->rreg) {
+			val1 |= sdca_soc_vol_ctl_to_reg(mc,
+						     ucontrol->value.integer.value[1],
+						     mask, max);
+		} else {
+			val2 = sdca_soc_vol_ctl_to_reg(mc,
+						    ucontrol->value.integer.value[1],
+						    mask, max);
+			double_r = true;
+		}
+	}
+
+	ret = snd_soc_component_update_bits(component, mc->reg, mask, val1);
+	if (ret < 0)
+		return ret;
+
+	if (double_r) {
+		int err = snd_soc_component_update_bits(component, mc->rreg,
+							mask, val2);
+		if (err)
+			return err;
+	}
+
+	return ret;
+}
+
+static int sdca_soc_get_volsw(struct snd_kcontrol *kcontrol,
+		      struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_mixer_control *mc =
+		(struct soc_mixer_control *)kcontrol->private_value;
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	int max = mc->max - mc->min;
+	unsigned int reg_val;
+	unsigned int mask;
+	int val;
+
+	if (mc->sign_bit)
+		mask = GENMASK(mc->sign_bit, 0);
+	else
+		mask = GENMASK(fls(mc->max) - 1, 0);
+
+	reg_val = snd_soc_component_read(component, mc->reg);
+	val = sdca_soc_vol_reg_to_ctl(mc, reg_val, mask, max);
+
+	ucontrol->value.integer.value[0] = val;
+
+	if (snd_soc_volsw_is_stereo(mc)) {
+		if (mc->reg == mc->rreg) {
+			val = sdca_soc_vol_reg_to_ctl(mc, reg_val, mask, max);
+		} else {
+			reg_val = snd_soc_component_read(component, mc->rreg);
+			val = sdca_soc_vol_reg_to_ctl(mc, reg_val, mask, max);
+		}
+
+		ucontrol->value.integer.value[1] = val;
+	}
+
+	return 0;
+}
+
 static int control_limit_kctl(struct device *dev,
 			      struct sdca_entity *entity,
 			      struct sdca_control *control,
@@ -795,7 +915,6 @@ static int control_limit_kctl(struct device *dev,
 	struct sdca_control_range *range;
 	int min, max, step;
 	unsigned int *tlv;
-	int shift;
 
 	if (control->type != SDCA_CTL_DATATYPE_Q7P8DB)
 		return 0;
@@ -814,41 +933,29 @@ static int control_limit_kctl(struct device *dev,
 	min = sign_extend32(min, control->nbits - 1);
 	max = sign_extend32(max, control->nbits - 1);
 
-	/*
-	 * FIXME: Only support power of 2 step sizes as this can be supported
-	 * by a simple shift.
-	 */
-	if (hweight32(step) != 1) {
-		dev_err(dev, "%s: %s: currently unsupported step size\n",
-			entity->label, control->label);
-		return -EINVAL;
-	}
-
-	/*
-	 * The SDCA volumes are in steps of 1/256th of a dB, a step down of
-	 * 64 (shift of 6) gives 1/4dB. 1/4dB is the smallest unit that is also
-	 * representable in the ALSA TLVs which are in 1/100ths of a dB.
-	 */
-	shift = max(ffs(step) - 1, 6);
-
 	tlv = devm_kcalloc(dev, 4, sizeof(*tlv), GFP_KERNEL);
 	if (!tlv)
 		return -ENOMEM;
 
-	tlv[0] = SNDRV_CTL_TLVT_DB_SCALE;
+	tlv[0] = SNDRV_CTL_TLVT_DB_MINMAX;
 	tlv[1] = 2 * sizeof(*tlv);
 	tlv[2] = (min * 100) >> 8;
-	tlv[3] = ((1 << shift) * 100) >> 8;
+	tlv[3] = (max * 100) >> 8;
+
+	step = (step * 100) >> 8;
 
-	mc->min = min >> shift;
-	mc->max = max >> shift;
-	mc->shift = shift;
-	mc->rshift = shift;
-	mc->sign_bit = 15 - shift;
+	mc->min = ((int)tlv[2] / step);
+	mc->max = ((int)tlv[3] / step);
+	mc->shift =  mc->rshift = 0;
+	mc->sign_bit = 15;
+	mc->step = step;
 
 	kctl->tlv.p = tlv;
 	kctl->access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
 
+	kctl->get = sdca_soc_get_volsw;
+	kctl->put = sdca_soc_put_volsw;
+
 	return 0;
 }