[PATCH] ASoC: samsung: Add 'mclk' handling for Snow sound-card driver

[PATCH] ASoC: samsung: Add 'mclk' handling for Snow sound-card driver

[Tushar Behera]

For audio to work on Snow board, we need the codec master clock 'mclk'
to be properly configured.

Currently XCLKOUT is configured as 'mclk' for codec chip and it is
required to be clocked at 24MHz for the codec to work properly.

Add appropriate clock handling within Snow sound-card driver to set
'mclk' to operate at 24MHz.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
---
 Documentation/devicetree/bindings/sound/snow.txt |    7 ++++++
 sound/soc/samsung/snow.c                         |   26 +++++++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/sound/snow.txt b/Documentation/devicetree/bindings/sound/snow.txt
index 678b191..94dd29c 100644
--- a/Documentation/devicetree/bindings/sound/snow.txt
+++ b/Documentation/devicetree/bindings/sound/snow.txt
@@ -7,6 +7,10 @@ Required properties:
 - samsung,i2s-controller: The phandle of the Samsung I2S controller
 - samsung,audio-codec: The phandle of the audio codec
 
+Optional properties:
+- clocks: The phandle of the master clock to audio codec
+- clock-names: Should be "mclk"
+
 Example:
 
 sound {
@@ -14,4 +18,7 @@ sound {
 
 		samsung,i2s-controller = <&i2s0>;
 		samsung,audio-codec = <&max98095>;
+
+		clocks = <&pmu_system_controller>;
+		clock-names = "mclk";
 };
diff --git a/sound/soc/samsung/snow.c b/sound/soc/samsung/snow.c
index 014c177..c910739 100644
--- a/sound/soc/samsung/snow.c
+++ b/sound/soc/samsung/snow.c
@@ -15,13 +15,18 @@
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/clk.h>
 
 #include <sound/soc.h>
 
 #include "i2s.h"
 
+/* Desired clock rate for codec mclk */
 #define FIN_PLL_RATE		24000000
 
+static struct clk *mclk;
+static unsigned long mclk_rate;
+
 static struct snd_soc_dai_link snow_dai[] = {
 	{
 		.name = "Primary",
@@ -41,7 +46,7 @@ static int snow_late_probe(struct snd_soc_card *card)
 
 	/* Set the MCLK rate for the codec */
 	ret = snd_soc_dai_set_sysclk(codec_dai, 0,
-					FIN_PLL_RATE, SND_SOC_CLOCK_IN);
+					mclk_rate, SND_SOC_CLOCK_IN);
 	if (ret < 0)
 		return ret;
 
@@ -68,6 +73,16 @@ static int snow_probe(struct platform_device *pdev)
 	struct device_node *i2s_node, *codec_node;
 	int i, ret;
 
+	/* The codec MCLK should be clocked at 24MHz */
+	mclk = devm_clk_get(&pdev->dev, "mclk");
+	if (!IS_ERR(mclk)) {
+		clk_prepare_enable(mclk);
+		clk_set_rate(mclk, FIN_PLL_RATE);
+		mclk_rate = clk_get_rate(mclk);
+	} else {
+		mclk_rate = FIN_PLL_RATE;
+	}
+
 	i2s_node = of_parse_phandle(pdev->dev.of_node,
 				    "samsung,i2s-controller", 0);
 	if (!i2s_node) {
@@ -101,6 +116,14 @@ static int snow_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static int snow_remove(struct platform_device *pdev)
+{
+	if (!IS_ERR(mclk))
+		clk_disable_unprepare(mclk);
+
+	return 0;
+}
+
 static const struct of_device_id snow_of_match[] = {
 	{ .compatible = "google,snow-audio-max98090", },
 	{ .compatible = "google,snow-audio-max98095", },
@@ -115,6 +138,7 @@ static struct platform_driver snow_driver = {
 		.of_match_table = snow_of_match,
 	},
 	.probe = snow_probe,
+	.remove = snow_remove,
 };
 
 module_platform_driver(snow_driver);
-- 
1.7.9.5

Re: [PATCH] ASoC: samsung: Add 'mclk' handling for Snow sound-card driver

[Mark Brown]

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On Tue, May 20, 2014 at 09:55:42AM +0530, Tushar Behera wrote:
> For audio to work on Snow board, we need the codec master clock 'mclk'
> to be properly configured.
> 
> Currently XCLKOUT is configured as 'mclk' for codec chip and it is
> required to be clocked at 24MHz for the codec to work properly.
> 
> Add appropriate clock handling within Snow sound-card driver to set
> 'mclk' to operate at 24MHz.

The clock here is connected to the CODEC on the board so it should be
connected to the CODEC in the device tree too.

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Re: [PATCH] ASoC: samsung: Add 'mclk' handling for Snow sound-card driver

[Tushar Behera]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 05/20/2014 04:46 PM, Mark Brown wrote:
> On Tue, May 20, 2014 at 09:55:42AM +0530, Tushar Behera wrote:
>> For audio to work on Snow board, we need the codec master clock
>> 'mclk' to be properly configured.
>> 
>> Currently XCLKOUT is configured as 'mclk' for codec chip and it
>> is required to be clocked at 24MHz for the codec to work
>> properly.
>> 
>> Add appropriate clock handling within Snow sound-card driver to
>> set 'mclk' to operate at 24MHz.
> 
> The clock here is connected to the CODEC on the board so it should
> be connected to the CODEC in the device tree too.
> 

Ok. I will move 'mclk' clock handling to respective CODEC drivers.

- -- 
Tushar Behera
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