ASoC: ak5558: 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/1598190877-9213-2-git-send-email-shengjiu.wang@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/ak5558.c

@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 
 #include <sound/initval.h>
@@ -22,8 +23,15 @@
 
 #include "ak5558.h"
 
+#define AK5558_NUM_SUPPLIES 2
+static const char *ak5558_supply_names[AK5558_NUM_SUPPLIES] = {
+	"DVDD",
+	"AVDD",
+};
+
 /* AK5558 Codec Private Data */
 struct ak5558_priv {
+	struct regulator_bulk_data supplies[AK5558_NUM_SUPPLIES];
 	struct snd_soc_component component;
 	struct regmap *regmap;
 	struct i2c_client *i2c;
@@ -299,12 +307,22 @@ static int __maybe_unused ak5558_runtime_suspend(struct device *dev)
 	regcache_cache_only(ak5558->regmap, true);
 	ak5558_power_off(ak5558);
 
+	regulator_bulk_disable(ARRAY_SIZE(ak5558->supplies),
+			       ak5558->supplies);
 	return 0;
 }
 
 static int __maybe_unused ak5558_runtime_resume(struct device *dev)
 {
 	struct ak5558_priv *ak5558 = dev_get_drvdata(dev);
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(ak5558->supplies),
+				    ak5558->supplies);
+	if (ret != 0) {
+		dev_err(dev, "Failed to enable supplies: %d\n", ret);
+		return ret;
+	}
 
 	ak5558_power_off(ak5558);
 	ak5558_power_on(ak5558);
@@ -350,6 +368,7 @@ static int ak5558_i2c_probe(struct i2c_client *i2c)
 {
 	struct ak5558_priv *ak5558;
 	int ret = 0;
+	int i;
 
 	ak5558 = devm_kzalloc(&i2c->dev, sizeof(*ak5558), GFP_KERNEL);
 	if (!ak5558)
@@ -367,6 +386,16 @@ static int ak5558_i2c_probe(struct i2c_client *i2c)
 	if (IS_ERR(ak5558->reset_gpiod))
 		return PTR_ERR(ak5558->reset_gpiod);
 
+	for (i = 0; i < ARRAY_SIZE(ak5558->supplies); i++)
+		ak5558->supplies[i].supply = ak5558_supply_names[i];
+
+	ret = devm_regulator_bulk_get(&i2c->dev, ARRAY_SIZE(ak5558->supplies),
+				      ak5558->supplies);
+	if (ret != 0) {
+		dev_err(&i2c->dev, "Failed to request supplies: %d\n", ret);
+		return ret;
+	}
+
 	ret = devm_snd_soc_register_component(&i2c->dev,
 				     &soc_codec_dev_ak5558,
 				     &ak5558_dai, 1);
@@ -374,6 +403,7 @@ static int ak5558_i2c_probe(struct i2c_client *i2c)
 		return ret;
 
 	pm_runtime_enable(&i2c->dev);
+	regcache_cache_only(ak5558->regmap, true);
 
 	return 0;
 }