[PATCH 7/7] hwmon: (lm90) Read the channel's temperature offset from device-tree

[Slawomir Stepien <sst@xxxxxxxxx>]

From: Slawomir Stepien <slawomir.stepien@xxxxxxxxx>

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@xxxxxxxxx>
---
 drivers/hwmon/lm90.c | 48 ++++++++++++++++++++++++++++++++------------
 1 file changed, 35 insertions(+), 13 deletions(-)

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 3837c4ab5833..12e8e874f1b9 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -1440,6 +1440,24 @@ static int lm90_set_temphyst(struct lm90_data *data, long val)
 	return lm90_write_reg(data->client, LM90_REG_TCRIT_HYST, data->temp_hyst);
 }
 
+static int lm90_set_temp_offset(struct lm90_data *data, int channel, long val)
+{
+	/* Both offset registers have the same resolution */
+	int res = lm90_temp_get_resolution(data, REMOTE_OFFSET);
+
+	val = lm90_temp_to_reg(0, val, res);
+
+	if (channel == 1) {
+		data->temp[REMOTE_OFFSET] = val;
+		return lm90_write16(data->client, LM90_REG_REMOTE_OFFSH,
+				    LM90_REG_REMOTE_OFFSL, val);
+	}
+
+	data->temp[REMOTE2_OFFSET] = val;
+	return lm90_write16(data->client, LM90_REG_REMOTE2_OFFSH,
+			    LM90_REG_REMOTE2_OFFSL, val);
+}
+
 static const u8 lm90_temp_index[MAX_CHANNELS] = {
 	LOCAL_TEMP, REMOTE_TEMP, REMOTE2_TEMP
 };
@@ -1577,19 +1595,7 @@ static int lm90_temp_write(struct device *dev, u32 attr, int channel, long val)
 				    channel, val);
 		break;
 	case hwmon_temp_offset:
-		/* Both offset registers have the same resolution */
-		val = lm90_temp_to_reg(0, val,
-				       lm90_temp_get_resolution(data, REMOTE_OFFSET));
-
-		if (channel == 1) {
-			data->temp[REMOTE_OFFSET] = val;
-			err = lm90_write16(data->client, LM90_REG_REMOTE_OFFSH,
-					   LM90_REG_REMOTE_OFFSL, val);
-		} else {
-			data->temp[REMOTE2_OFFSET] = val;
-			err = lm90_write16(data->client, LM90_REG_REMOTE2_OFFSH,
-					   LM90_REG_REMOTE2_OFFSL, val);
-		}
+		err = lm90_set_temp_offset(data, channel, val);
 		break;
 	default:
 		err = -EOPNOTSUPP;
@@ -2651,6 +2657,7 @@ 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;
 
@@ -2674,6 +2681,21 @@ 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, "offset can't be set for internal channel\n");
+			return -EINVAL;
+		}
+
+		err = lm90_set_temp_offset(data, id, val);
+		if (err) {
+			dev_err(dev, "can't set offset %d for channel %d (%d)\n",
+				val, id, err);
+			return err;
+		}
+	}
+
 	return 0;
 }
 
-- 
2.36.1