ASoC: core: Add signed register volume control logic
Some codecs use signed volume control representation with non standard
register sizes, e.g. 6 or 7 bit signed integers.
This patch adds generic signed register volume control logic to
soc-core. Instead of a fixed width signed register control, this
implementation uses a 'min' value and the signed bit location to translate
it to an absolute volume. Using the 'sign_bit' we can calculate a
correct mask for the register values and translate it back into signed
integers of standard size.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index fe1df50..c1d9d85 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -2716,6 +2716,48 @@
EXPORT_SYMBOL_GPL(snd_soc_put_value_enum_double);
/**
+ * snd_soc_read_signed - Read a codec register and interprete as signed value
+ * @codec: codec
+ * @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.
+ *
+ * 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.
+ *
+ * Returns the register value as signed int.
+ */
+static int snd_soc_read_signed(struct snd_soc_codec *codec, unsigned int reg,
+ unsigned int mask, unsigned int shift, unsigned int sign_bit)
+{
+ int ret;
+ unsigned int val;
+
+ val = (snd_soc_read(codec, reg) >> shift) & mask;
+
+ if (!sign_bit)
+ return val;
+
+ /* non-negative number */
+ if (!(val & BIT(sign_bit)))
+ return val;
+
+ ret = val;
+
+ /*
+ * 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));
+
+ return ret;
+}
+
+/**
* snd_soc_info_volsw - single mixer info callback
* @kcontrol: mixer control
* @uinfo: control element information
@@ -2743,7 +2785,7 @@
uinfo->count = snd_soc_volsw_is_stereo(mc) ? 2 : 1;
uinfo->value.integer.min = 0;
- uinfo->value.integer.max = platform_max;
+ uinfo->value.integer.max = platform_max - mc->min;
return 0;
}
EXPORT_SYMBOL_GPL(snd_soc_info_volsw);
@@ -2769,11 +2811,16 @@
unsigned int shift = mc->shift;
unsigned int rshift = mc->rshift;
int max = mc->max;
+ int min = mc->min;
+ int sign_bit = mc->sign_bit;
unsigned int mask = (1 << fls(max)) - 1;
unsigned int invert = mc->invert;
- ucontrol->value.integer.value[0] =
- (snd_soc_read(codec, reg) >> shift) & mask;
+ if (sign_bit)
+ mask = BIT(sign_bit + 1) - 1;
+
+ ucontrol->value.integer.value[0] = snd_soc_read_signed(codec, reg, mask,
+ shift, sign_bit) - min;
if (invert)
ucontrol->value.integer.value[0] =
max - ucontrol->value.integer.value[0];
@@ -2781,10 +2828,12 @@
if (snd_soc_volsw_is_stereo(mc)) {
if (reg == reg2)
ucontrol->value.integer.value[1] =
- (snd_soc_read(codec, reg) >> rshift) & mask;
+ snd_soc_read_signed(codec, reg, mask, rshift,
+ sign_bit) - min;
else
ucontrol->value.integer.value[1] =
- (snd_soc_read(codec, reg2) >> shift) & mask;
+ snd_soc_read_signed(codec, reg2, mask, shift,
+ sign_bit) - min;
if (invert)
ucontrol->value.integer.value[1] =
max - ucontrol->value.integer.value[1];
@@ -2815,6 +2864,8 @@
unsigned int shift = mc->shift;
unsigned int rshift = mc->rshift;
int max = mc->max;
+ int min = mc->min;
+ unsigned int sign_bit = mc->sign_bit;
unsigned int mask = (1 << fls(max)) - 1;
unsigned int invert = mc->invert;
int err;
@@ -2822,13 +2873,16 @@
unsigned int val2 = 0;
unsigned int val, val_mask;
- val = (ucontrol->value.integer.value[0] & mask);
+ if (sign_bit)
+ mask = BIT(sign_bit + 1) - 1;
+
+ val = ((ucontrol->value.integer.value[0] + min) & mask);
if (invert)
val = max - val;
val_mask = mask << shift;
val = val << shift;
if (snd_soc_volsw_is_stereo(mc)) {
- val2 = (ucontrol->value.integer.value[1] & mask);
+ val2 = ((ucontrol->value.integer.value[1] + min) & mask);
if (invert)
val2 = max - val2;
if (reg == reg2) {