ASoC: cs4271: add support for AMUTEB=BMUTEC feature

The CS4271 has a feature to sync its analog mute flags, so one mute
circuitry can be used for both channels.

Give users access to this feature with a new DT property and a flag in
the platform data.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Documentation/devicetree/bindings/sound/cs4271.txt

@@ -18,6 +18,8 @@ Optional properties:
 
  - reset-gpio: 	a GPIO spec to define which pin is connected to the chip's
 		!RESET pin
+ - cirrus,amuteb-eq-bmutec:	When given, the Codec's AMUTEB=BMUTEC flag
+				is enabled.
 
 Examples:
 

include/sound/cs4271.h

@@ -19,6 +19,7 @@
 
 struct cs4271_platform_data {
 	int gpio_nreset;	/* GPIO driving Reset pin, if any */
+	int amutec_eq_bmutec:1;	/* flag to enable AMUTEC=BMUTEC */
 };
 
 #endif /* __CS4271_H */

sound/soc/codecs/cs4271.c

@@ -474,15 +474,25 @@ static int cs4271_probe(struct snd_soc_codec *codec)
 	struct cs4271_platform_data *cs4271plat = codec->dev->platform_data;
 	int ret;
 	int gpio_nreset = -EINVAL;
+	int amutec_eq_bmutec = 0;
 
 #ifdef CONFIG_OF
-	if (of_match_device(cs4271_dt_ids, codec->dev))
+	if (of_match_device(cs4271_dt_ids, codec->dev)) {
 		gpio_nreset = of_get_named_gpio(codec->dev->of_node,
 						"reset-gpio", 0);
+
+		if (!of_get_property(codec->dev->of_node,
+				     "cirrus,amutec-eq-bmutec", NULL))
+			amutec_eq_bmutec = 1;
+	}
 #endif
 
-	if (cs4271plat && gpio_is_valid(cs4271plat->gpio_nreset))
-		gpio_nreset = cs4271plat->gpio_nreset;
+	if (cs4271plat) {
+		if (gpio_is_valid(cs4271plat->gpio_nreset))
+			gpio_nreset = cs4271plat->gpio_nreset;
+
+		amutec_eq_bmutec = cs4271plat->amutec_eq_bmutec;
+	}
 
 	if (gpio_nreset >= 0)
 		if (gpio_request(gpio_nreset, "CS4271 Reset"))
@@ -528,6 +538,11 @@ static int cs4271_probe(struct snd_soc_codec *codec)
 	/* Power-up sequence requires 85 uS */
 	udelay(85);
 
+	if (amutec_eq_bmutec)
+		snd_soc_update_bits(codec, CS4271_MODE2,
+				    CS4271_MODE2_MUTECAEQUB,
+				    CS4271_MODE2_MUTECAEQUB);
+
 	return snd_soc_add_codec_controls(codec, cs4271_snd_controls,
 		ARRAY_SIZE(cs4271_snd_controls));
 }