iio: light: ltr501: Add rudimentary regulator support

On some platforms the supply regulators must be enabled before the
sensor can work. Add vdd and vddio regulators for the sensor and IO bus
power respectively.
Signed-off-by: Nikita Travkin <nikita@trvn.ru>
Link: https://lore.kernel.org/r/20211006163058.145842-3-nikita@trvn.ruSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/ltr501.c

@@ -15,6 +15,7 @@
 #include <linux/delay.h>
 #include <linux/regmap.h>
 #include <linux/acpi.h>
+#include <linux/regulator/consumer.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/events.h>
@@ -151,6 +152,7 @@ struct ltr501_chip_info {
 
 struct ltr501_data {
 	struct i2c_client *client;
+	struct regulator_bulk_data regulators[2];
 	struct mutex lock_als, lock_ps;
 	const struct ltr501_chip_info *chip_info;
 	u8 als_contr, ps_contr;
@@ -1379,6 +1381,13 @@ static const struct regmap_config ltr501_regmap_config = {
 	.volatile_reg = ltr501_is_volatile_reg,
 };
 
+static void ltr501_disable_regulators(void *d)
+{
+	struct ltr501_data *data = d;
+
+	regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
+}
+
 static int ltr501_powerdown(struct ltr501_data *data)
 {
 	return ltr501_write_contr(data, data->als_contr &
@@ -1423,6 +1432,25 @@ static int ltr501_probe(struct i2c_client *client,
 	mutex_init(&data->lock_als);
 	mutex_init(&data->lock_ps);
 
+	data->regulators[0].supply = "vdd";
+	data->regulators[1].supply = "vddio";
+	ret = devm_regulator_bulk_get(&client->dev,
+				      ARRAY_SIZE(data->regulators),
+				      data->regulators);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "Failed to get regulators\n");
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(data->regulators),
+				    data->regulators);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(&client->dev,
+				       ltr501_disable_regulators, data);
+	if (ret)
+		return ret;
+
 	data->reg_it = devm_regmap_field_alloc(&client->dev, regmap,
 					       reg_field_it);
 	if (IS_ERR(data->reg_it)) {