hwmon: (adc128d818) Use devm_regulator_get_enable_read_voltage()

We can reduce boilerplate code and eliminate the driver remove()
function by using devm_regulator_get_enable_read_voltage().

A new external_vref flag is added since we no longer have the handle
to the regulator to check if it is present.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240429-regulator-get-enable-get-votlage-v2-2-b1f11ab766c1@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: dlech

drivers/hwmon/adc128d818.c

@@ -58,7 +58,6 @@ static const u8 num_inputs[] = { 7, 8, 4, 6 };
 
 struct adc128_data {
 	struct i2c_client *client;
-	struct regulator *regulator;
 	int vref;		/* Reference voltage in mV */
 	struct mutex update_lock;
 	u8 mode;		/* Operation mode */
@@ -389,7 +388,7 @@ static int adc128_detect(struct i2c_client *client, struct i2c_board_info *info)
 	return 0;
 }
 
-static int adc128_init_client(struct adc128_data *data)
+static int adc128_init_client(struct adc128_data *data, bool external_vref)
 {
 	struct i2c_client *client = data->client;
 	int err;
@@ -408,7 +407,7 @@ static int adc128_init_client(struct adc128_data *data)
 		regval |= data->mode << 1;
 
 	/* If external vref is selected, configure the chip to use it */
-	if (data->regulator)
+	if (external_vref)
 		regval |= 0x01;
 
 	/* Write advanced configuration register */
@@ -430,44 +429,38 @@ static int adc128_init_client(struct adc128_data *data)
 static int adc128_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
-	struct regulator *regulator;
 	struct device *hwmon_dev;
 	struct adc128_data *data;
+	bool external_vref;
 	int err, vref;
 
 	data = devm_kzalloc(dev, sizeof(struct adc128_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
 	/* vref is optional. If specified, is used as chip reference voltage */
-	regulator = devm_regulator_get_optional(dev, "vref");
-	if (!IS_ERR(regulator)) {
-		data->regulator = regulator;
-		err = regulator_enable(regulator);
-		if (err < 0)
-			return err;
-		vref = regulator_get_voltage(regulator);
-		if (vref < 0) {
-			err = vref;
-			goto error;
-		}
-		data->vref = DIV_ROUND_CLOSEST(vref, 1000);
-	} else {
+	vref = devm_regulator_get_enable_read_voltage(dev, "vref");
+	if (vref == -ENODEV) {
+		external_vref = false;
 		data->vref = 2560;	/* 2.56V, in mV */
+	} else if (vref < 0) {
+		return vref;
+	} else {
+		external_vref = true;
+		data->vref = DIV_ROUND_CLOSEST(vref, 1000);
 	}
 
 	/* Operation mode is optional. If unspecified, keep current mode */
 	if (of_property_read_u8(dev->of_node, "ti,mode", &data->mode) == 0) {
 		if (data->mode > 3) {
 			dev_err(dev, "invalid operation mode %d\n",
 				data->mode);
-			err = -EINVAL;
-			goto error;
+			return -EINVAL;
 		}
 	} else {
 		err = i2c_smbus_read_byte_data(client, ADC128_REG_CONFIG_ADV);
 		if (err < 0)
-			goto error;
+			return err;
 		data->mode = (err >> 1) & ADC128_REG_MASK;
 	}
 
@@ -476,31 +469,16 @@ static int adc128_probe(struct i2c_client *client)
 	mutex_init(&data->update_lock);
 
 	/* Initialize the chip */
-	err = adc128_init_client(data);
+	err = adc128_init_client(data, external_vref);
 	if (err < 0)
-		goto error;
+		return err;
 
 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 							   data, adc128_groups);
-	if (IS_ERR(hwmon_dev)) {
-		err = PTR_ERR(hwmon_dev);
-		goto error;
-	}
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
 
 	return 0;
-
-error:
-	if (data->regulator)
-		regulator_disable(data->regulator);
-	return err;
-}
-
-static void adc128_remove(struct i2c_client *client)
-{
-	struct adc128_data *data = i2c_get_clientdata(client);
-
-	if (data->regulator)
-		regulator_disable(data->regulator);
 }
 
 static const struct i2c_device_id adc128_id[] = {
@@ -522,7 +500,6 @@ static struct i2c_driver adc128_driver = {
 		.of_match_table = of_match_ptr(adc128_of_match),
 	},
 	.probe		= adc128_probe,
-	.remove		= adc128_remove,
 	.id_table	= adc128_id,
 	.detect		= adc128_detect,
 	.address_list	= normal_i2c,