ASoC: max98090: read micbias from device property

This patch reads max98090 micbias from acpi or dt

Signed-off-by: Fang, Yang A <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/sound/max98090.txt

···
 
 - maxim,dmic-freq: Frequency at which to clock DMIC
 
+- maxim,micbias: Micbias voltage applies to the analog mic, valid voltages value are:
+	0 - 2.2v
+	1 - 2.55v
+	2 - 2.4v
+	3 - 2.8v
+
 Pins on the device (for linking into audio routes):
 
   * MIC1

sound/soc/codecs/max98090.c

···
 	struct max98090_cdata *cdata;
 	enum max98090_type devtype;
 	int ret = 0;
+	int err;
+	unsigned int micbias;
 
 	dev_dbg(codec->dev, "max98090_probe\n");
 
···
 	snd_soc_write(codec, M98090_REG_BIAS_CONTROL,
 		M98090_VCM_MODE_MASK);
 
+	err = device_property_read_u32(codec->dev, "maxim,micbias", &micbias);
+	if (err) {
+		micbias = M98090_MBVSEL_2V8;
+		dev_info(codec->dev, "use default 2.8v micbias\n");
+	} else if (micbias < M98090_MBVSEL_2V2 || micbias > M98090_MBVSEL_2V8) {
+		dev_err(codec->dev, "micbias out of range 0x%x\n", micbias);
+		micbias = M98090_MBVSEL_2V8;
+	}
+
 	snd_soc_update_bits(codec, M98090_REG_MIC_BIAS_VOLTAGE,
-		M98090_MBVSEL_MASK, M98090_MBVSEL_2V8);
+		M98090_MBVSEL_MASK, micbias);
 
 	max98090_add_widgets(codec);