[alsa-devel] [PATCH v2] audio: sgtl5000: Add MicBias resistor support in DT

[Mark Rutland]

On Sun, Oct 12, 2014 at 10:39:11PM +0100, Jean-Michel Hautbois wrote:
> 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.
> 
> v2: modify the default case on DT parsing
> 
> Signed-off-by: Jean-Michel Hautbois <jean-michel.hautbois at vodalys.com>
> ---
>  .../devicetree/bindings/sound/sgtl5000.txt         | 10 ++++
>  sound/soc/codecs/sgtl5000.c                        | 60 ++++++++++++++++++++--
>  2 files changed, 66 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.

The SGTL5000_MICBIAS_* constants aren't in a DT header, so shouldn't be
referenced here.

Why not have mcbias-resistor-k-ohms as 2, 4, 8, or 0?

That would be much easier to read as a human.

Thanks,
Mark.

> +
> +
>  Example:
>  
>  codec: sgtl5000 at 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..a255754 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 +1491,37 @@ 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 0:
> +				sgtl5000->micbias_resistor =
> +					SGTL5000_MICBIAS_OFF;
> +				break;
> +			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_4K;
> +				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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