hwmon: (lm90) Read the channel's temperature offset from device-tree

Try to read the channel's temperature offset from device-tree. Having
offset in device-tree node is not mandatory. The offset can only be set
for remote channels.
Signed-off-by: Slawomir Stepien <slawomir.stepien@nokia.com>
Link: https://lore.kernel.org/r/20220607063504.1287855-3-sst@poczta.fmSigned-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/lm90.c

@@ -2666,6 +2666,7 @@ static int lm90_probe_channel_from_dt(struct i2c_client *client,
 				      struct lm90_data *data)
 {
 	u32 id;
+	s32 val;
 	int err;
 	struct device *dev = &client->dev;
 
@@ -2689,6 +2690,21 @@ static int lm90_probe_channel_from_dt(struct i2c_client *client,
 	if (data->channel_label[id])
 		data->channel_config[id] |= HWMON_T_LABEL;
 
+	err = of_property_read_s32(child, "temperature-offset-millicelsius", &val);
+	if (!err) {
+		if (id == 0) {
+			dev_err(dev, "temperature-offset-millicelsius can't be set for internal channel\n");
+			return -EINVAL;
+		}
+
+		err = lm90_set_temp_offset(data, lm90_temp_offset_index[id], id, val);
+		if (err) {
+			dev_err(dev, "can't set temperature offset %d for channel %d (%d)\n",
+				val, id, err);
+			return err;
+		}
+	}
+
 	return 0;
 }