[PATCH V3] iio: magnetometer: mag3110: add optional vdd/vddio regulator operation support

[Anson Huang <anson.huang@xxxxxxx>]

The magnetometer's power supply could be controlled by regulator
on some platforms, such as i.MX6Q-SABRESD board, the mag3110's
power supply is controlled by a GPIO fixed regulator, need to make
sure the regulator is enabled before any communication with mag3110,
this patch adds optional vdd/vddio regulator operation support.

Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
---
ChangeLog since V2:
	- improve the error handling of devm_regulator_get_optional;
	- make sure regulators are disabled in error path.
---
 drivers/iio/magnetometer/mag3110.c | 97 ++++++++++++++++++++++++++++++++++----
 1 file changed, 89 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/magnetometer/mag3110.c b/drivers/iio/magnetometer/mag3110.c
index f063355..120f383 100644
--- a/drivers/iio/magnetometer/mag3110.c
+++ b/drivers/iio/magnetometer/mag3110.c
@@ -20,6 +20,7 @@
 #include <linux/iio/buffer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/delay.h>
+#include <linux/regulator/consumer.h>
 
 #define MAG3110_STATUS 0x00
 #define MAG3110_OUT_X 0x01 /* MSB first */
@@ -56,6 +57,8 @@ struct mag3110_data {
 	struct mutex lock;
 	u8 ctrl_reg1;
 	int sleep_val;
+	struct regulator *vdd_reg;
+	struct regulator *vddio_reg;
 };
 
 static int mag3110_request(struct mag3110_data *data)
@@ -469,17 +472,48 @@ static int mag3110_probe(struct i2c_client *client,
 	struct iio_dev *indio_dev;
 	int ret;
 
-	ret = i2c_smbus_read_byte_data(client, MAG3110_WHO_AM_I);
-	if (ret < 0)
-		return ret;
-	if (ret != MAG3110_DEVICE_ID)
-		return -ENODEV;
-
 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
 		return -ENOMEM;
 
 	data = iio_priv(indio_dev);
+
+	data->vdd_reg = devm_regulator_get_optional(&client->dev, "vdd");
+	if (!IS_ERR(data->vdd_reg)) {
+		ret = regulator_enable(data->vdd_reg);
+		if (ret) {
+			dev_err(&client->dev, "failed to enable VDD regulator\n");
+			return ret;
+		}
+	} else {
+		ret = PTR_ERR(data->vdd_reg);
+		if (ret != -ENODEV)
+			return ret;
+	}
+
+	data->vddio_reg = devm_regulator_get_optional(&client->dev, "vddio");
+	if (!IS_ERR(data->vddio_reg)) {
+		ret = regulator_enable(data->vddio_reg);
+		if (ret) {
+			dev_err(&client->dev, "failed to enable VDDIO regulator\n");
+			if (!IS_ERR(data->vdd_reg))
+				regulator_disable(data->vdd_reg);
+			return ret;
+		}
+	} else {
+		ret = PTR_ERR(data->vddio_reg);
+		if (ret != -ENODEV)
+			return ret;
+	}
+
+	ret = i2c_smbus_read_byte_data(client, MAG3110_WHO_AM_I);
+	if (ret < 0)
+		goto disable_regulators;
+	if (ret != MAG3110_DEVICE_ID) {
+		ret = -ENODEV;
+		goto disable_regulators;
+	}
+
 	data->client = client;
 	mutex_init(&data->lock);
 
@@ -499,7 +533,7 @@ static int mag3110_probe(struct i2c_client *client,
 
 	ret = mag3110_change_config(data, MAG3110_CTRL_REG1, data->ctrl_reg1);
 	if (ret < 0)
-		return ret;
+		goto disable_regulators;
 
 	ret = i2c_smbus_write_byte_data(client, MAG3110_CTRL_REG2,
 		MAG3110_CTRL_AUTO_MRST_EN);
@@ -520,6 +554,12 @@ static int mag3110_probe(struct i2c_client *client,
 	iio_triggered_buffer_cleanup(indio_dev);
 standby_on_error:
 	mag3110_standby(iio_priv(indio_dev));
+disable_regulators:
+	if (!IS_ERR(data->vdd_reg))
+		regulator_disable(data->vdd_reg);
+	if (!IS_ERR(data->vddio_reg))
+		regulator_disable(data->vddio_reg);
+
 	return ret;
 }
 
@@ -537,14 +577,55 @@ static int mag3110_remove(struct i2c_client *client)
 #ifdef CONFIG_PM_SLEEP
 static int mag3110_suspend(struct device *dev)
 {
-	return mag3110_standby(iio_priv(i2c_get_clientdata(
+	struct mag3110_data *data = iio_priv(i2c_get_clientdata(
+		to_i2c_client(dev)));
+	int ret;
+
+	ret = mag3110_standby(iio_priv(i2c_get_clientdata(
 		to_i2c_client(dev))));
+	if (ret)
+		return ret;
+
+	if (!IS_ERR(data->vdd_reg)) {
+		ret = regulator_disable(data->vdd_reg);
+		if (ret) {
+			dev_err(dev, "failed to disable VDD regulator\n");
+			return ret;
+		}
+	}
+	if (!IS_ERR(data->vddio_reg)) {
+		ret = regulator_disable(data->vddio_reg);
+		if (ret) {
+			dev_err(dev, "failed to disable VDDIO regulator\n");
+			return ret;
+		}
+	}
+
+	return 0;
 }
 
 static int mag3110_resume(struct device *dev)
 {
 	struct mag3110_data *data = iio_priv(i2c_get_clientdata(
 		to_i2c_client(dev)));
+	int ret;
+
+	if (!IS_ERR(data->vdd_reg)) {
+		ret = regulator_enable(data->vdd_reg);
+		if (ret) {
+			dev_err(dev, "failed to enable VDD regulator\n");
+			return ret;
+		}
+	}
+	if (!IS_ERR(data->vddio_reg)) {
+		ret = regulator_enable(data->vddio_reg);
+		if (ret) {
+			dev_err(dev, "failed to enable VDDIO regulator\n");
+			if (!IS_ERR(data->vdd_reg))
+				regulator_disable(data->vdd_reg);
+			return ret;
+		}
+	}
 
 	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
 		data->ctrl_reg1);
-- 
2.7.4