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/include/sound/soc.h b/include/sound/soc.h
index 9a001472b96a4bf8a11c8c129543060fdb75c869..a25f3ccb3fde971a67b4bb473d4eddb2014e4919 100644 (file)
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -1067,6 +1067,7 @@ struct soc_mixer_control {
        int min, max, platform_max;
        int reg, rreg;
        unsigned int shift, rshift;
+       unsigned int sign_bit;
        unsigned int invert:1;
        unsigned int autodisable:1;
 };

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index fe1df50805a3035ea455d40771c55d4cb4f6585d..c1d9d8539ee91c292405d1b94fb4bc8226c7fd74 100644 (file)
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -2715,6 +2715,48 @@ int snd_soc_put_value_enum_double(struct snd_kcontrol *kcontrol,
 }
 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
@@ -2743,7 +2785,7 @@ int snd_soc_info_volsw(struct snd_kcontrol *kcontrol,
 
        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 @@ int snd_soc_get_volsw(struct snd_kcontrol *kcontrol,
        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 @@ int snd_soc_get_volsw(struct snd_kcontrol *kcontrol,
        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 @@ int snd_soc_put_volsw(struct snd_kcontrol *kcontrol,
        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 @@ int snd_soc_put_volsw(struct snd_kcontrol *kcontrol,
        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) {