[PATCH] audio: sgtl5000: Add MicBias resistor support in DT

[Jean-Michel Hautbois]

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.hautbois-B+***@public.gmane.org>
---
.../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: ***@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 */

[Fabio Estevam]

On Sun, Oct 12, 2014 at 3:39 PM, Jean-Michel Hautbois

+ if (np) {
+ if (!of_property_read_u32(np,
+ "sgtl5000-micbias-resistor", &value)) {
+ switch (value) {
+ sgtl5000->micbias_resistor =
+ SGTL5000_MICBIAS_2K;
+ break;
+ sgtl5000->micbias_resistor =
+ SGTL5000_MICBIAS_4K;
+ break;
+ sgtl5000->micbias_resistor =
+ SGTL5000_MICBIAS_8K;
+ break;
+ sgtl5000->micbias_resistor =
+ SGTL5000_MICBIAS_OFF;
+ dev_err(&client->dev,
+ "Unsuitable MicBias resistor\n");

The case 0 should SGTL5000_MICBIAS_OFF and the default should be
SGTL5000_MICBIAS_4K.
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[Jean-Michel Hautbois]

Hi Fabio,

Post by Fabio Estevam
On Sun, Oct 12, 2014 at 3:39 PM, Jean-Michel Hautbois

+ if (np) {
+ if (!of_property_read_u32(np,
+ "sgtl5000-micbias-resistor", &value)) {
+ switch (value) {
+ sgtl5000->micbias_resistor =
+ SGTL5000_MICBIAS_2K;
+ break;
+ sgtl5000->micbias_resistor =
+ SGTL5000_MICBIAS_4K;
+ break;
+ sgtl5000->micbias_resistor =
+ SGTL5000_MICBIAS_8K;
+ break;
+ sgtl5000->micbias_resistor =
+ SGTL5000_MICBIAS_OFF;
+ dev_err(&client->dev,
+ "Unsuitable MicBias resistor\n");

The case 0 should SGTL5000_MICBIAS_OFF and the default should be
SGTL5000_MICBIAS_4K.

You are right of course, second version sent. I have a patch wich adds
MicBias voltage support too, but it will be on top of this one, is
this a problem ?

Thanks,
JM
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[Fabio Estevam]

Hi Jean-Michel,

On Sun, Oct 12, 2014 at 6:42 PM, Jean-Michel Hautbois

Post by Jean-Michel Hautbois
You are right of course, second version sent. I have a patch wich adds
MicBias voltage support too, but it will be on top of this one, is
this a problem ?

In this case you could send a series of two patches: PATCH v3 1/2 and
PATCH v3 2/2
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[Jean-Michel Hautbois]

Post by Fabio Estevam
Hi Jean-Michel,
On Sun, Oct 12, 2014 at 6:42 PM, Jean-Michel Hautbois

Post by Jean-Michel Hautbois
You are right of course, second version sent. I have a patch wich adds
MicBias voltage support too, but it will be on top of this one, is
this a problem ?

In this case you could send a series of two patches: PATCH v3 1/2 and
PATCH v3 2/2

I am using a "big" enum of 8 values, but there may be a nicer way to do it.
In the datasheet it is said that MICBIAS_VOLT is set in 250mV steps,
from 1.25V when register is 0 to 3.00V when register is 7.

Thanks,
JM
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