ASoC: Support non-crystal master clocks for WM8731

Instead of unconditionally enabling the crystal oscillator on the WM8731
only enable it when explicitly selected via set_sysclk(), allowing machine
drivers to specify that they drive a clock into MCLK alone. This avoids
any conflicts between the oscillator and the external MCLK source and saves
power for systems which do not need the oscillator.

This should also deliver a small power saving on systems using the crystal
since the oscillator will only be enabled when the ADC or DAC is active.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

2 files changed, 32 insertions, 3 deletions

diff --git a/sound/soc/codecs/wm8731.c b/sound/soc/codecs/wm8731.c
index 19844fc8cb1d..56f540838745 100644
--- a/sound/soc/codecs/wm8731.c
+++ b/sound/soc/codecs/wm8731.c
@@ -46,6 +46,7 @@ struct wm8731_priv {
 	struct regulator_bulk_data supplies[WM8731_NUM_SUPPLIES];
 	u16 reg_cache[WM8731_CACHEREGNUM];
 	unsigned int sysclk;
+	int sysclk_type;
 };
 
 
@@ -110,6 +111,7 @@ static const struct snd_kcontrol_new wm8731_input_mux_controls =
 SOC_DAPM_ENUM("Input Select", wm8731_enum[0]);
 
 static const struct snd_soc_dapm_widget wm8731_dapm_widgets[] = {
+SND_SOC_DAPM_SUPPLY("OSC", WM8731_PWR, 5, 1, NULL, 0),
 SND_SOC_DAPM_MIXER("Output Mixer", WM8731_PWR, 4, 1,
 	&wm8731_output_mixer_controls[0],
 	ARRAY_SIZE(wm8731_output_mixer_controls)),
@@ -127,7 +129,18 @@ SND_SOC_DAPM_INPUT("RLINEIN"),
 SND_SOC_DAPM_INPUT("LLINEIN"),
 };
 
+static int wm8731_check_osc(struct snd_soc_dapm_widget *source,
+			    struct snd_soc_dapm_widget *sink)
+{
+	struct wm8731_priv *wm8731 = snd_soc_codec_get_drvdata(source->codec);
+
+	return wm8731->sysclk_type == WM8731_SYSCLK_MCLK;
+}
+
 static const struct snd_soc_dapm_route intercon[] = {
+	{"DAC", NULL, "OSC", wm8731_check_osc},
+	{"ADC", NULL, "OSC", wm8731_check_osc},
+
 	/* output mixer */
 	{"Output Mixer", "Line Bypass Switch", "Line Input"},
 	{"Output Mixer", "HiFi Playback Switch", "DAC"},
@@ -285,6 +298,15 @@ static int wm8731_set_dai_sysclk(struct snd_soc_dai *codec_dai,
 	struct snd_soc_codec *codec = codec_dai->codec;
 	struct wm8731_priv *wm8731 = snd_soc_codec_get_drvdata(codec);
 
+	switch (clk_id) {
+	case WM8731_SYSCLK_XTAL:
+	case WM8731_SYSCLK_MCLK:
+		wm8731->sysclk_type = clk_id;
+		break;
+	default:
+		return -EINVAL;
+	}
+
 	switch (freq) {
 	case 11289600:
 	case 12000000:
@@ -292,9 +314,14 @@ static int wm8731_set_dai_sysclk(struct snd_soc_dai *codec_dai,
 	case 16934400:
 	case 18432000:
 		wm8731->sysclk = freq;
-		return 0;
+		break;
+	default:
+		return -EINVAL;
 	}
-	return -EINVAL;
+
+	snd_soc_dapm_sync(codec);
+
+	return 0;
 }
 
 
diff --git a/sound/soc/codecs/wm8731.h b/sound/soc/codecs/wm8731.h
index 73a70e206ba9..e9c0c76ab73b 100644
--- a/sound/soc/codecs/wm8731.h
+++ b/sound/soc/codecs/wm8731.h
@@ -31,7 +31,9 @@
 
 #define WM8731_CACHEREGNUM 	10
 
-#define WM8731_SYSCLK	0
+#define WM8731_SYSCLK_XTAL 1
+#define WM8731_SYSCLK_MCLK 2
+
 #define WM8731_DAI		0
 
 #endif