ASoC: ak4458: Add regulator support

"AVDD" is for analog power supply,  "DVDD" is for digital power
supply, they can improve the power management.

As the regulator is enabled in pm runtime resume, which is
behind the component driver probe, so accessing registers in
component driver probe will fail. Fix this issue by enabling
regcache_cache_only after pm_runtime_enable.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1597397561-2426-2-git-send-email-shengjiu.wang@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/ak4458.c

@@ -12,6 +12,7 @@
 #include <linux/of_device.h>
 #include <linux/of_gpio.h>
 #include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 #include <sound/initval.h>
 #include <sound/pcm_params.h>
@@ -21,6 +22,12 @@
 
 #include "ak4458.h"
 
+#define AK4458_NUM_SUPPLIES 2
+static const char *ak4458_supply_names[AK4458_NUM_SUPPLIES] = {
+	"DVDD",
+	"AVDD",
+};
+
 struct ak4458_drvdata {
 	struct snd_soc_dai_driver *dai_drv;
 	const struct snd_soc_component_driver *comp_drv;
@@ -28,6 +35,7 @@ struct ak4458_drvdata {
 
 /* AK4458 Codec Private Data */
 struct ak4458_priv {
+	struct regulator_bulk_data supplies[AK4458_NUM_SUPPLIES];
 	struct device *dev;
 	struct regmap *regmap;
 	struct gpio_desc *reset_gpiod;
@@ -587,12 +595,22 @@ static int __maybe_unused ak4458_runtime_suspend(struct device *dev)
 	if (ak4458->mute_gpiod)
 		gpiod_set_value_cansleep(ak4458->mute_gpiod, 0);
 
+	regulator_bulk_disable(ARRAY_SIZE(ak4458->supplies),
+			       ak4458->supplies);
 	return 0;
 }
 
 static int __maybe_unused ak4458_runtime_resume(struct device *dev)
 {
 	struct ak4458_priv *ak4458 = dev_get_drvdata(dev);
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(ak4458->supplies),
+				    ak4458->supplies);
+	if (ret != 0) {
+		dev_err(ak4458->dev, "Failed to enable supplies: %d\n", ret);
+		return ret;
+	}
 
 	if (ak4458->mute_gpiod)
 		gpiod_set_value_cansleep(ak4458->mute_gpiod, 1);
@@ -667,7 +685,7 @@ static int ak4458_i2c_probe(struct i2c_client *i2c)
 {
 	struct ak4458_priv *ak4458;
 	const struct ak4458_drvdata *drvdata;
-	int ret;
+	int ret, i;
 
 	ak4458 = devm_kzalloc(&i2c->dev, sizeof(*ak4458), GFP_KERNEL);
 	if (!ak4458)
@@ -692,6 +710,16 @@ static int ak4458_i2c_probe(struct i2c_client *i2c)
 	if (IS_ERR(ak4458->mute_gpiod))
 		return PTR_ERR(ak4458->mute_gpiod);
 
+	for (i = 0; i < ARRAY_SIZE(ak4458->supplies); i++)
+		ak4458->supplies[i].supply = ak4458_supply_names[i];
+
+	ret = devm_regulator_bulk_get(ak4458->dev, ARRAY_SIZE(ak4458->supplies),
+				      ak4458->supplies);
+	if (ret != 0) {
+		dev_err(ak4458->dev, "Failed to request supplies: %d\n", ret);
+		return ret;
+	}
+
 	ret = devm_snd_soc_register_component(ak4458->dev, drvdata->comp_drv,
 					      drvdata->dai_drv, 1);
 	if (ret < 0) {
@@ -700,6 +728,7 @@ static int ak4458_i2c_probe(struct i2c_client *i2c)
 	}
 
 	pm_runtime_enable(&i2c->dev);
+	regcache_cache_only(ak4458->regmap, true);
 
 	return 0;
 }