ASoC: arizona: Export functions to control subsystem DVFS

The WM5102 and WM8997 codecs have an internal dynamic clock booster.
When this booster is active, the DCVDD voltage must be increased.
If all the currently active audio paths can run with the root SYSCLK
we can disable the booster, allowing us to turn down DCVDD voltage
to save power.

Previously this was being done by having the booster enable bit set
as a side-effect of the LDO1 regulator driver, which is unexpected
behaviour of a regulator and not compatible with using an external
regulator.  [Originally this was documented as a feature of the internal
LDO -- broonie]

This patch exports functions to handle the booster enable and
DCVDD voltage, with each relevant subsystem flagging whether it can
currently run without the booster. Note that these subsystems are
stateless and none of them are nestable, so there's no need for
reference counting, we only need a simple boolean for each subsystem
of whether their current condition could require the booster or will
allow us to turn the codec down to lower operating power.

Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 128 insertions, 0 deletions

diff --git a/sound/soc/codecs/arizona.c b/sound/soc/codecs/arizona.c
index eff4b4d..b2d8b04 100644
--- a/sound/soc/codecs/arizona.c
+++ b/sound/soc/codecs/arizona.c
@@ -851,6 +851,134 @@ int arizona_hp_ev(struct snd_soc_dapm_widget *w,
 }
 EXPORT_SYMBOL_GPL(arizona_hp_ev);
 
+static int arizona_dvfs_enable(struct snd_soc_codec *codec)
+{
+	const struct arizona_priv *priv = snd_soc_codec_get_drvdata(codec);
+	struct arizona *arizona = priv->arizona;
+	int ret;
+
+	ret = regulator_set_voltage(arizona->dcvdd, 1800000, 1800000);
+	if (ret) {
+		dev_err(codec->dev, "Failed to boost DCVDD: %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_update_bits(arizona->regmap,
+				 ARIZONA_DYNAMIC_FREQUENCY_SCALING_1,
+				 ARIZONA_SUBSYS_MAX_FREQ,
+				 ARIZONA_SUBSYS_MAX_FREQ);
+	if (ret) {
+		dev_err(codec->dev, "Failed to enable subsys max: %d\n", ret);
+		regulator_set_voltage(arizona->dcvdd, 1200000, 1800000);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int arizona_dvfs_disable(struct snd_soc_codec *codec)
+{
+	const struct arizona_priv *priv = snd_soc_codec_get_drvdata(codec);
+	struct arizona *arizona = priv->arizona;
+	int ret;
+
+	ret = regmap_update_bits(arizona->regmap,
+				 ARIZONA_DYNAMIC_FREQUENCY_SCALING_1,
+				 ARIZONA_SUBSYS_MAX_FREQ, 0);
+	if (ret) {
+		dev_err(codec->dev, "Failed to disable subsys max: %d\n", ret);
+		return ret;
+	}
+
+	ret = regulator_set_voltage(arizona->dcvdd, 1200000, 1800000);
+	if (ret) {
+		dev_err(codec->dev, "Failed to unboost DCVDD: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+int arizona_dvfs_up(struct snd_soc_codec *codec, unsigned int flags)
+{
+	struct arizona_priv *priv = snd_soc_codec_get_drvdata(codec);
+	int ret = 0;
+
+	mutex_lock(&priv->dvfs_lock);
+
+	if (!priv->dvfs_cached && !priv->dvfs_reqs) {
+		ret = arizona_dvfs_enable(codec);
+		if (ret)
+			goto err;
+	}
+
+	priv->dvfs_reqs |= flags;
+err:
+	mutex_unlock(&priv->dvfs_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(arizona_dvfs_up);
+
+int arizona_dvfs_down(struct snd_soc_codec *codec, unsigned int flags)
+{
+	struct arizona_priv *priv = snd_soc_codec_get_drvdata(codec);
+	unsigned int old_reqs;
+	int ret = 0;
+
+	mutex_lock(&priv->dvfs_lock);
+
+	old_reqs = priv->dvfs_reqs;
+	priv->dvfs_reqs &= ~flags;
+
+	if (!priv->dvfs_cached && old_reqs && !priv->dvfs_reqs)
+		ret = arizona_dvfs_disable(codec);
+
+	mutex_unlock(&priv->dvfs_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(arizona_dvfs_down);
+
+int arizona_dvfs_sysclk_ev(struct snd_soc_dapm_widget *w,
+			   struct snd_kcontrol *kcontrol, int event)
+{
+	struct snd_soc_codec *codec = snd_soc_dapm_to_codec(w->dapm);
+	struct arizona_priv *priv = snd_soc_codec_get_drvdata(codec);
+	int ret = 0;
+
+	mutex_lock(&priv->dvfs_lock);
+
+	switch (event) {
+	case SND_SOC_DAPM_POST_PMU:
+		if (priv->dvfs_reqs)
+			ret = arizona_dvfs_enable(codec);
+
+		priv->dvfs_cached = false;
+		break;
+	case SND_SOC_DAPM_PRE_PMD:
+		/* We must ensure DVFS is disabled before the codec goes into
+		 * suspend so that we are never in an illegal state of DVFS
+		 * enabled without enough DCVDD
+		 */
+		priv->dvfs_cached = true;
+
+		if (priv->dvfs_reqs)
+			ret = arizona_dvfs_disable(codec);
+		break;
+	default:
+		break;
+	}
+
+	mutex_unlock(&priv->dvfs_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(arizona_dvfs_sysclk_ev);
+
+void arizona_init_dvfs(struct arizona_priv *priv)
+{
+	mutex_init(&priv->dvfs_lock);
+}
+EXPORT_SYMBOL_GPL(arizona_init_dvfs);
+
 static unsigned int arizona_sysclk_48k_rates[] = {
 	6144000,
 	12288000,