ASoC: max98090: Add master clock handling

If master clock is provided through device tree, then update
the master clock frequency during set_sysclk.

Documentation has been updated to reflect the change.
Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/sound/max98090.txt

@@ -10,6 +10,12 @@ Required properties:
 
 - interrupts : The CODEC's interrupt output.
 
+Optional properties:
+
+- clocks: The phandle of the master clock to the CODEC
+
+- clock-names: Should be "mclk"
+
 Pins on the device (for linking into audio routes):
 
   * MIC1

sound/soc/codecs/max98090.c

@@ -16,6 +16,7 @@
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
+#include <linux/clk.h>
 #include <sound/jack.h>
 #include <sound/pcm.h>
 #include <sound/pcm_params.h>
@@ -1798,6 +1799,19 @@ static int max98090_set_bias_level(struct snd_soc_codec *codec,
 		break;
 
 	case SND_SOC_BIAS_PREPARE:
+		/*
+		 * SND_SOC_BIAS_PREPARE is called while preparing for a
+		 * transition to ON or away from ON. If current bias_level
+		 * is SND_SOC_BIAS_ON, then it is preparing for a transition
+		 * away from ON. Disable the clock in that case, otherwise
+		 * enable it.
+		 */
+		if (!IS_ERR(max98090->mclk)) {
+			if (codec->dapm.bias_level == SND_SOC_BIAS_ON)
+				clk_disable_unprepare(max98090->mclk);
+			else
+				clk_prepare_enable(max98090->mclk);
+		}
 		break;
 
 	case SND_SOC_BIAS_STANDBY:
@@ -1927,6 +1941,11 @@ static int max98090_dai_set_sysclk(struct snd_soc_dai *dai,
 	if (freq == max98090->sysclk)
 		return 0;
 
+	if (!IS_ERR(max98090->mclk)) {
+		freq = clk_round_rate(max98090->mclk, freq);
+		clk_set_rate(max98090->mclk, freq);
+	}
+
 	/* Setup clocks for slave mode, and using the PLL
 	 * PSCLK = 0x01 (when master clk is 10MHz to 20MHz)
 	 *		 0x02 (when master clk is 20MHz to 40MHz)..
@@ -2211,6 +2230,10 @@ static int max98090_probe(struct snd_soc_codec *codec)
 
 	dev_dbg(codec->dev, "max98090_probe\n");
 
+	max98090->mclk = devm_clk_get(codec->dev, "mclk");
+	if (PTR_ERR(max98090->mclk) == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+
 	max98090->codec = codec;
 
 	/* Reset the codec, the DSP core, and disable all interrupts */

sound/soc/codecs/max98090.h

@@ -1524,6 +1524,7 @@ struct max98090_priv {
 	struct snd_soc_codec *codec;
 	enum max98090_type devtype;
 	struct max98090_pdata *pdata;
+	struct clk *mclk;
 	unsigned int sysclk;
 	unsigned int bclk;
 	unsigned int lrclk;