misc: eeprom: at24: support pm_runtime control

Although in the most platforms, the power of eeprom are alway
on, some platforms disable the eeprom power in order to meet
low power request. This patch add the pm_runtime ops to control
power to support all platforms.
Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
[Bartosz: rebased on top of current at24/for-next]
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

drivers/misc/eeprom/at24.c

@@ -21,6 +21,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/property.h>
 #include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 
 /* Address pointer is 16 bit. */
@@ -87,6 +88,7 @@ struct at24_data {
 	u8 flags;
 
 	struct nvmem_device *nvmem;
+	struct regulator *vcc_reg;
 
 	/*
 	 * Some chips tie up multiple I2C addresses; dummy devices reserve
@@ -656,6 +658,9 @@ static int at24_probe(struct i2c_client *client)
 	at24->client[0].client = client;
 	at24->client[0].regmap = regmap;
 
+	at24->vcc_reg = devm_regulator_get(dev, "vcc");
+	if (IS_ERR(at24->vcc_reg))
+		return PTR_ERR(at24->vcc_reg);
 
 	writable = !(flags & AT24_FLAG_READONLY);
 	if (writable) {
@@ -692,6 +697,12 @@ static int at24_probe(struct i2c_client *client)
 
 	i2c_set_clientdata(client, at24);
 
+	err = regulator_enable(at24->vcc_reg);
+	if (err) {
+		dev_err(dev, "Failed to enable vcc regulator\n");
+		return err;
+	}
+
 	/* enable runtime pm */
 	pm_runtime_set_active(dev);
 	pm_runtime_enable(dev);
@@ -704,6 +715,7 @@ static int at24_probe(struct i2c_client *client)
 	pm_runtime_idle(dev);
 	if (err) {
 		pm_runtime_disable(dev);
+		regulator_disable(at24->vcc_reg);
 		return -ENODEV;
 	}
 
@@ -719,15 +731,42 @@ static int at24_probe(struct i2c_client *client)
 
 static int at24_remove(struct i2c_client *client)
 {
+	struct at24_data *at24 = i2c_get_clientdata(client);
+
 	pm_runtime_disable(&client->dev);
+	if (!pm_runtime_status_suspended(&client->dev))
+		regulator_disable(at24->vcc_reg);
 	pm_runtime_set_suspended(&client->dev);
 
 	return 0;
 }
 
+static int __maybe_unused at24_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct at24_data *at24 = i2c_get_clientdata(client);
+
+	return regulator_disable(at24->vcc_reg);
+}
+
+static int __maybe_unused at24_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct at24_data *at24 = i2c_get_clientdata(client);
+
+	return regulator_enable(at24->vcc_reg);
+}
+
+static const struct dev_pm_ops at24_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+	SET_RUNTIME_PM_OPS(at24_suspend, at24_resume, NULL)
+};
+
 static struct i2c_driver at24_driver = {
 	.driver = {
 		.name = "at24",
+		.pm = &at24_pm_ops,
 		.of_match_table = at24_of_match,
 		.acpi_match_table = ACPI_PTR(at24_acpi_ids),
 	},