[PATCH v2 3/3] hwmon: (lm75) Add regulator support

[Alban Bedel <alban.bedel@aerq.com>]

Add regulator support for boards where the sensor first need to be
powered up before it can be used.

Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
---
v2: Rely on dummy regulators instead of explicitly handling missing
    regulator
---
 drivers/hwmon/lm75.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index ba0be48aeadd..e394df648c26 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -17,6 +17,7 @@
 #include <linux/of.h>
 #include <linux/regmap.h>
 #include <linux/util_macros.h>
+#include <linux/regulator/consumer.h>
 #include "lm75.h"
 
 /*
@@ -101,6 +102,7 @@ static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
 struct lm75_data {
 	struct i2c_client		*client;
 	struct regmap			*regmap;
+	struct regulator		*vs;
 	u8				orig_conf;
 	u8				current_conf;
 	u8				resolution;	/* In bits, 9 to 16 */
@@ -540,6 +542,7 @@ static void lm75_remove(void *data)
 	struct i2c_client *client = lm75->client;
 
 	i2c_smbus_write_byte_data(client, LM75_REG_CONF, lm75->orig_conf);
+	regulator_disable(lm75->vs);
 }
 
 static int
@@ -567,6 +570,10 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	data->client = client;
 	data->kind = kind;
 
+	data->vs = devm_regulator_get(dev, "vs");
+	if (IS_ERR(data->vs))
+		return PTR_ERR(data->vs);
+
 	data->regmap = devm_regmap_init_i2c(client, &lm75_regmap_config);
 	if (IS_ERR(data->regmap))
 		return PTR_ERR(data->regmap);
@@ -581,11 +588,19 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	data->sample_time = data->params->default_sample_time;
 	data->resolution = data->params->default_resolution;
 
+	/* Enable the power */
+	err = regulator_enable(data->vs);
+	if (err) {
+		dev_err(dev, "failed to enable regulator: %d\n", err);
+		return err;
+	}
+
 	/* Cache original configuration */
 	status = i2c_smbus_read_byte_data(client, LM75_REG_CONF);
 	if (status < 0) {
 		dev_dbg(dev, "Can't read config? %d\n", status);
-		return status;
+		err = status;
+		goto disable_regulator;
 	}
 	data->orig_conf = status;
 	data->current_conf = status;
@@ -593,7 +608,7 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	err = lm75_write_config(data, data->params->set_mask,
 				data->params->clr_mask);
 	if (err)
-		return err;
+		goto disable_regulator;
 
 	err = devm_add_action_or_reset(dev, lm75_remove, data);
 	if (err)
@@ -608,6 +623,10 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	dev_info(dev, "%s: sensor '%s'\n", dev_name(hwmon_dev), client->name);
 
 	return 0;
+
+disable_regulator:
+	regulator_disable(data->vs);
+	return err;
 }
 
 static const struct i2c_device_id lm75_ids[] = {
-- 
2.25.1