iio: light: isl29018: add vcc regulator operation support

The light sensor's power supply could be controllable by regulator
on some platforms, such as i.MX6Q-SABRESD board, the light sensor
isl29023's power supply is controlled by a GPIO fixed regulator,
need to make sure the regulator is enabled before any operation of
sensor, this patch adds vcc regulator operation support.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/isl29018.c

@@ -23,6 +23,7 @@
 #include <linux/mutex.h>
 #include <linux/delay.h>
 #include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -95,6 +96,7 @@ struct isl29018_chip {
 	struct isl29018_scale	scale;
 	int			prox_scheme;
 	bool			suspended;
+	struct regulator	*vcc_reg;
 };
 
 static int isl29018_set_integration_time(struct isl29018_chip *chip,
@@ -708,6 +710,16 @@ static const char *isl29018_match_acpi_device(struct device *dev, int *data)
 	return dev_name(dev);
 }
 
+static void isl29018_disable_regulator_action(void *_data)
+{
+	struct isl29018_chip *chip = _data;
+	int err;
+
+	err = regulator_disable(chip->vcc_reg);
+	if (err)
+		pr_err("failed to disable isl29018's VCC regulator!\n");
+}
+
 static int isl29018_probe(struct i2c_client *client,
 			  const struct i2c_device_id *id)
 {
@@ -742,6 +754,27 @@ static int isl29018_probe(struct i2c_client *client,
 	chip->scale = isl29018_scales[chip->int_time][0];
 	chip->suspended = false;
 
+	chip->vcc_reg = devm_regulator_get(&client->dev, "vcc");
+	if (IS_ERR(chip->vcc_reg)) {
+		err = PTR_ERR(chip->vcc_reg);
+		if (err != -EPROBE_DEFER)
+			dev_err(&client->dev, "failed to get VCC regulator!\n");
+		return err;
+	}
+
+	err = regulator_enable(chip->vcc_reg);
+	if (err) {
+		dev_err(&client->dev, "failed to enable VCC regulator!\n");
+		return err;
+	}
+
+	err = devm_add_action_or_reset(&client->dev, isl29018_disable_regulator_action,
+				 chip);
+	if (err) {
+		dev_err(&client->dev, "failed to setup regulator cleanup action!\n");
+		return err;
+	}
+
 	chip->regmap = devm_regmap_init_i2c(client,
 				isl29018_chip_info_tbl[dev_id].regmap_cfg);
 	if (IS_ERR(chip->regmap)) {
@@ -768,6 +801,7 @@ static int isl29018_probe(struct i2c_client *client,
 static int isl29018_suspend(struct device *dev)
 {
 	struct isl29018_chip *chip = iio_priv(dev_get_drvdata(dev));
+	int ret;
 
 	mutex_lock(&chip->lock);
 
@@ -777,10 +811,13 @@ static int isl29018_suspend(struct device *dev)
 	 * So we do not have much to do here.
 	 */
 	chip->suspended = true;
+	ret = regulator_disable(chip->vcc_reg);
+	if (ret)
+		dev_err(dev, "failed to disable VCC regulator\n");
 
 	mutex_unlock(&chip->lock);
 
-	return 0;
+	return ret;
 }
 
 static int isl29018_resume(struct device *dev)
@@ -790,6 +827,13 @@ static int isl29018_resume(struct device *dev)
 
 	mutex_lock(&chip->lock);
 
+	err = regulator_enable(chip->vcc_reg);
+	if (err) {
+		dev_err(dev, "failed to enable VCC regulator\n");
+		mutex_unlock(&chip->lock);
+		return err;
+	}
+
 	err = isl29018_chip_init(chip);
 	if (!err)
 		chip->suspended = false;