Some systems may require a different resistor than the default one (4K).
This adds a property in sgtl5000 codec.
It keeps the default of 4K when nothing is specified so it does not break
existing code.

Signed-off-by: Jean-Michel Hautbois <jean-michel.hautb...@vodalys.com>
---
 .../devicetree/bindings/sound/sgtl5000.txt         | 10 ++++
 sound/soc/codecs/sgtl5000.c                        | 56 ++++++++++++++++++++--
 2 files changed, 62 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/sound/sgtl5000.txt 
b/Documentation/devicetree/bindings/sound/sgtl5000.txt
index 955df60..dd38f84 100644
--- a/Documentation/devicetree/bindings/sound/sgtl5000.txt
+++ b/Documentation/devicetree/bindings/sound/sgtl5000.txt
@@ -7,10 +7,20 @@ Required properties:
 
 - clocks : the clock provider of SYS_MCLK
 
+- sgtl5000-micbias-resistor : the bias resistor to be used
+        1 or SGTL5000_MICBIAS_2K - MICBIAS resistor is set to 2K
+        2 or SGTL5000_MICBIAS_4K - MICBIAS resistor is set to 4K
+        3 or SGTL5000_MICBIAS_8K - MICBIAS resistor is set to 8K
+        0 or SGTL5000_MICBIAS_OFF - MICBIAS resistor is not used
+       If this node is not mentioned or if the value is unknown, then
+       micbias resistor is set to 4K.
+
+
 Example:
 
 codec: sgtl5000@0a {
        compatible = "fsl,sgtl5000";
        reg = <0x0a>;
        clocks = <&clks 150>;
+       sgtl5000-micbias-resistor = <1>;
 };
diff --git a/sound/soc/codecs/sgtl5000.c b/sound/soc/codecs/sgtl5000.c
index 6bb77d7..f538957 100644
--- a/sound/soc/codecs/sgtl5000.c
+++ b/sound/soc/codecs/sgtl5000.c
@@ -121,6 +121,13 @@ struct ldo_regulator {
        bool enabled;
 };
 
+enum sgtl5000_micbias_resistor {
+       SGTL5000_MICBIAS_OFF = 0,
+       SGTL5000_MICBIAS_2K = 1,
+       SGTL5000_MICBIAS_4K = 2,
+       SGTL5000_MICBIAS_8K = 3,
+};
+
 /* sgtl5000 private structure in codec */
 struct sgtl5000_priv {
        int sysclk;     /* sysclk rate */
@@ -131,6 +138,7 @@ struct sgtl5000_priv {
        struct regmap *regmap;
        struct clk *mclk;
        int revision;
+       enum sgtl5000_micbias_resistor micbias_resistor;
 };
 
 /*
@@ -145,12 +153,14 @@ struct sgtl5000_priv {
 static int mic_bias_event(struct snd_soc_dapm_widget *w,
        struct snd_kcontrol *kcontrol, int event)
 {
+       struct sgtl5000_priv *sgtl5000 = snd_soc_codec_get_drvdata(w->codec);
+
        switch (event) {
        case SND_SOC_DAPM_POST_PMU:
-               /* change mic bias resistor to 4Kohm */
+               /* change mic bias resistor */
                snd_soc_update_bits(w->codec, SGTL5000_CHIP_MIC_CTRL,
-                               SGTL5000_BIAS_R_MASK,
-                               SGTL5000_BIAS_R_4k << SGTL5000_BIAS_R_SHIFT);
+                       SGTL5000_BIAS_R_MASK,
+                       sgtl5000->micbias_resistor << SGTL5000_BIAS_R_SHIFT);
                break;
 
        case SND_SOC_DAPM_PRE_PMD:
@@ -1326,7 +1336,16 @@ static int sgtl5000_probe(struct snd_soc_codec *codec)
                        SGTL5000_HP_ZCD_EN |
                        SGTL5000_ADC_ZCD_EN);
 
-       snd_soc_write(codec, SGTL5000_CHIP_MIC_CTRL, 2);
+       switch (sgtl5000->micbias_resistor) {
+       case SGTL5000_MICBIAS_2K:
+       case SGTL5000_MICBIAS_4K:
+       case SGTL5000_MICBIAS_8K:
+               snd_soc_update_bits(codec, SGTL5000_CHIP_MIC_CTRL,
+                       SGTL5000_BIAS_R_MASK,
+                       sgtl5000->micbias_resistor << SGTL5000_BIAS_R_SHIFT);
+       default:
+               break;
+       }
 
        /*
         * disable DAP
@@ -1418,6 +1437,8 @@ static int sgtl5000_i2c_probe(struct i2c_client *client,
        struct sgtl5000_priv *sgtl5000;
        int ret, reg, rev;
        unsigned int mclk;
+       struct device_node *np = client->dev.of_node;
+       u32 value;
 
        sgtl5000 = devm_kzalloc(&client->dev, sizeof(struct sgtl5000_priv),
                                                                GFP_KERNEL);
@@ -1470,6 +1491,33 @@ static int sgtl5000_i2c_probe(struct i2c_client *client,
        dev_info(&client->dev, "sgtl5000 revision 0x%x\n", rev);
        sgtl5000->revision = rev;
 
+       if (np) {
+               if (!of_property_read_u32(np,
+                       "sgtl5000-micbias-resistor", &value)) {
+                       switch (value) {
+                       case 1:
+                               sgtl5000->micbias_resistor =
+                                       SGTL5000_MICBIAS_2K;
+                               break;
+                       case 2:
+                               sgtl5000->micbias_resistor =
+                                       SGTL5000_MICBIAS_4K;
+                               break;
+                       case 3:
+                               sgtl5000->micbias_resistor =
+                                       SGTL5000_MICBIAS_8K;
+                               break;
+                       default:
+                               sgtl5000->micbias_resistor =
+                                       SGTL5000_MICBIAS_OFF;
+                               dev_err(&client->dev,
+                                       "Unsuitable MicBias resistor\n");
+                       }
+               } else {
+                       sgtl5000->micbias_resistor = SGTL5000_MICBIAS_4K;
+               }
+       }
+
        i2c_set_clientdata(client, sgtl5000);
 
        /* Ensure sgtl5000 will start with sane register values */
-- 
2.1.1

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