ASoC: ops: Replace snd_soc_read_signed() with new helper

The current snd_soc_read_signed() helper is only used from
snd_soc_get_volsw() and can be implemented more simply with
sign_extend. Remove snd_soc_read_signed() and add a new
soc_mixer_reg_to_ctl() helper. This new helper does not
include the reading of the register, but does include min and
max handling. This allows the helper to replace more of the
duplicated code and makes it easier to process the differences
between single, double register and double shift style controls.

It is worth noting this adds support for sign_bit into the _range
and sx callbacks and the invert option to sx callbacks.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20250318171459.3203730-7-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: charleskeepax

sound/soc/soc-ops.c

@@ -110,52 +110,20 @@ int snd_soc_put_enum_double(struct snd_kcontrol *kcontrol,
 }
 EXPORT_SYMBOL_GPL(snd_soc_put_enum_double);
 
-/**
- * snd_soc_read_signed - Read a codec register and interpret as signed value
- * @component: component
- * @reg: Register to read
- * @mask: Mask to use after shifting the register value
- * @shift: Right shift of register value
- * @sign_bit: Bit that describes if a number is negative or not.
- * @signed_val: Pointer to where the read value should be stored
- *
- * This functions reads a codec register. The register value is shifted right
- * by 'shift' bits and masked with the given 'mask'. Afterwards it translates
- * the given registervalue into a signed integer if sign_bit is non-zero.
- */
-static void snd_soc_read_signed(struct snd_soc_component *component,
-				unsigned int reg, unsigned int mask,
-				unsigned int shift, unsigned int sign_bit,
-				int *signed_val)
+static int soc_mixer_reg_to_ctl(struct soc_mixer_control *mc, unsigned int reg_val,
+				unsigned int mask, unsigned int shift, int max)
 {
-	int ret;
-	unsigned int val;
-
-	val = snd_soc_component_read(component, reg);
-	val = (val >> shift) & mask;
+	int val = (reg_val >> shift) & mask;
 
-	if (!sign_bit) {
-		*signed_val = val;
-		return;
-	}
-
-	/* non-negative number */
-	if (!(val & BIT(sign_bit))) {
-		*signed_val = val;
-		return;
-	}
+	if (mc->sign_bit)
+		val = sign_extend32(val, mc->sign_bit);
 
-	ret = val;
+	val -= mc->min;
 
-	/*
-	 * The register most probably does not contain a full-sized int.
-	 * Instead we have an arbitrary number of bits in a signed
-	 * representation which has to be translated into a full-sized int.
-	 * This is done by filling up all bits above the sign-bit.
-	 */
-	ret |= ~((int)(BIT(sign_bit) - 1));
+	if (mc->invert)
+		val = max - val;
 
-	*signed_val = ret;
+	return val & mask;
 }
 
 static int soc_mixer_valid_ctl(struct soc_mixer_control *mc, long val, int max)
@@ -281,34 +249,25 @@ int snd_soc_get_volsw(struct snd_kcontrol *kcontrol,
 	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
 	struct soc_mixer_control *mc =
 		(struct soc_mixer_control *)kcontrol->private_value;
-	unsigned int reg = mc->reg;
-	unsigned int reg2 = mc->rreg;
-	unsigned int shift = mc->shift;
-	unsigned int rshift = mc->rshift;
-	int max = mc->max;
-	int min = mc->min;
-	int sign_bit = mc->sign_bit;
+	int max = mc->max - mc->min;
 	unsigned int mask = soc_mixer_mask(mc);
-	unsigned int invert = mc->invert;
+	unsigned int reg_val;
 	int val;
 
-	snd_soc_read_signed(component, reg, mask, shift, sign_bit, &val);
+	reg_val = snd_soc_component_read(component, mc->reg);
+	val = soc_mixer_reg_to_ctl(mc, reg_val, mask, mc->shift, max);
 
-	ucontrol->value.integer.value[0] = val - min;
-	if (invert)
-		ucontrol->value.integer.value[0] =
-			max - ucontrol->value.integer.value[0];
+	ucontrol->value.integer.value[0] = val;
 
 	if (snd_soc_volsw_is_stereo(mc)) {
-		if (reg == reg2)
-			snd_soc_read_signed(component, reg, mask, rshift, sign_bit, &val);
-		else
-			snd_soc_read_signed(component, reg2, mask, shift, sign_bit, &val);
+		if (mc->reg == mc->rreg) {
+			val = soc_mixer_reg_to_ctl(mc, reg_val, mask, mc->rshift, max);
+		} else {
+			reg_val = snd_soc_component_read(component, mc->rreg);
+			val = soc_mixer_reg_to_ctl(mc, reg_val, mask, mc->shift, max);
+		}
 
-		ucontrol->value.integer.value[1] = val - min;
-		if (invert)
-			ucontrol->value.integer.value[1] =
-				max - ucontrol->value.integer.value[1];
+		ucontrol->value.integer.value[1] = val;
 	}
 
 	return 0;
@@ -408,18 +367,19 @@ int snd_soc_get_volsw_sx(struct snd_kcontrol *kcontrol,
 		(struct soc_mixer_control *)kcontrol->private_value;
 	unsigned int reg = mc->reg;
 	unsigned int reg2 = mc->rreg;
-	unsigned int shift = mc->shift;
-	unsigned int rshift = mc->rshift;
-	int min = mc->min;
 	unsigned int mask = soc_mixer_sx_mask(mc);
-	unsigned int val;
+	unsigned int reg_val;
+	int val;
 
-	val = snd_soc_component_read(component, reg);
-	ucontrol->value.integer.value[0] = ((val >> shift) - min) & mask;
+	reg_val = snd_soc_component_read(component, reg);
+	val = soc_mixer_reg_to_ctl(mc, reg_val, mask, mc->shift, mc->max);
+
+	ucontrol->value.integer.value[0] = val;
 
 	if (snd_soc_volsw_is_stereo(mc)) {
-		val = snd_soc_component_read(component, reg2);
-		val = ((val >> rshift) - min) & mask;
+		reg_val = snd_soc_component_read(component, reg2);
+		val = soc_mixer_reg_to_ctl(mc, reg_val, mask, mc->rshift, mc->max);
+
 		ucontrol->value.integer.value[1] = val;
 	}
 
@@ -602,33 +562,21 @@ int snd_soc_get_volsw_range(struct snd_kcontrol *kcontrol,
 	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
 	struct soc_mixer_control *mc =
 		(struct soc_mixer_control *)kcontrol->private_value;
-	unsigned int reg = mc->reg;
-	unsigned int rreg = mc->rreg;
-	unsigned int shift = mc->shift;
-	int min = mc->min;
-	int max = mc->max;
+	int max = mc->max - mc->min;
 	unsigned int mask = soc_mixer_mask(mc);
-	unsigned int invert = mc->invert;
-	unsigned int val;
+	unsigned int reg_val;
+	int val;
 
-	val = snd_soc_component_read(component, reg);
-	ucontrol->value.integer.value[0] = (val >> shift) & mask;
-	if (invert)
-		ucontrol->value.integer.value[0] =
-			max - ucontrol->value.integer.value[0];
-	else
-		ucontrol->value.integer.value[0] =
-			ucontrol->value.integer.value[0] - min;
+	reg_val = snd_soc_component_read(component, mc->reg);
+	val = soc_mixer_reg_to_ctl(mc, reg_val, mask, mc->shift, max);
+
+	ucontrol->value.integer.value[0] = val;
 
 	if (snd_soc_volsw_is_stereo(mc)) {
-		val = snd_soc_component_read(component, rreg);
-		ucontrol->value.integer.value[1] = (val >> shift) & mask;
-		if (invert)
-			ucontrol->value.integer.value[1] =
-				max - ucontrol->value.integer.value[1];
-		else
-			ucontrol->value.integer.value[1] =
-				ucontrol->value.integer.value[1] - min;
+		reg_val = snd_soc_component_read(component, mc->rreg);
+		val = soc_mixer_reg_to_ctl(mc, reg_val, mask, mc->shift, max);
+
+		ucontrol->value.integer.value[1] = val;
 	}
 
 	return 0;