hwmon: (ntc_thermistor) Move and refactor DT parsing

Move the parsing of the DT config right above probe().

Allocate the state container for the driver in probe()
instead of inside the DT config parsing function: as a
result return an int instead of a pointer.

Drop the check for !np: we can only probe from DT right
now so no risk of ending up here.

Cc: Peter Rosin <peda@axentia.se>
Cc: Chris Lesiak <chris.lesiak@licor.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20211206020423.62402-1-linus.walleij@linaro.orgSigned-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/ntc_thermistor.c

@@ -403,49 +403,6 @@ static const struct of_device_id ntc_match[] = {
 };
 MODULE_DEVICE_TABLE(of, ntc_match);
 
-static struct ntc_data *ntc_thermistor_parse_dt(struct device *dev)
-{
-	struct ntc_data *data;
-	struct iio_channel *chan;
-	enum iio_chan_type type;
-	struct device_node *np = dev->of_node;
-	int ret;
-
-	if (!np)
-		return NULL;
-
-	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
-	if (!data)
-		return ERR_PTR(-ENOMEM);
-
-	chan = devm_iio_channel_get(dev, NULL);
-	if (IS_ERR(chan))
-		return ERR_CAST(chan);
-
-	ret = iio_get_channel_type(chan, &type);
-	if (ret < 0)
-		return ERR_PTR(ret);
-
-	if (type != IIO_VOLTAGE)
-		return ERR_PTR(-EINVAL);
-
-	if (of_property_read_u32(np, "pullup-uv", &data->pullup_uv))
-		return ERR_PTR(-ENODEV);
-	if (of_property_read_u32(np, "pullup-ohm", &data->pullup_ohm))
-		return ERR_PTR(-ENODEV);
-	if (of_property_read_u32(np, "pulldown-ohm", &data->pulldown_ohm))
-		return ERR_PTR(-ENODEV);
-
-	if (of_find_property(np, "connected-positive", NULL))
-		data->connect = NTC_CONNECTED_POSITIVE;
-	else /* status change should be possible if not always on. */
-		data->connect = NTC_CONNECTED_GROUND;
-
-	data->chan = chan;
-
-	return data;
-}
-
 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
 {
 	if (divisor == 0 && dividend == 0)
@@ -638,6 +595,42 @@ static const struct hwmon_chip_info ntc_chip_info = {
 	.info = ntc_info,
 };
 
+static int ntc_thermistor_parse_dt(struct device *dev,
+				   struct ntc_data *data)
+{
+	struct iio_channel *chan;
+	enum iio_chan_type type;
+	struct device_node *np = dev->of_node;
+	int ret;
+
+	chan = devm_iio_channel_get(dev, NULL);
+	if (IS_ERR(chan))
+		return PTR_ERR(chan);
+
+	ret = iio_get_channel_type(chan, &type);
+	if (ret < 0)
+		return ret;
+
+	if (type != IIO_VOLTAGE)
+		return -EINVAL;
+
+	if (of_property_read_u32(np, "pullup-uv", &data->pullup_uv))
+		return -ENODEV;
+	if (of_property_read_u32(np, "pullup-ohm", &data->pullup_ohm))
+		return -ENODEV;
+	if (of_property_read_u32(np, "pulldown-ohm", &data->pulldown_ohm))
+		return -ENODEV;
+
+	if (of_find_property(np, "connected-positive", NULL))
+		data->connect = NTC_CONNECTED_POSITIVE;
+	else /* status change should be possible if not always on. */
+		data->connect = NTC_CONNECTED_GROUND;
+
+	data->chan = chan;
+
+	return 0;
+}
+
 static int ntc_thermistor_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -646,15 +639,15 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
 	const struct platform_device_id *pdev_id;
 	struct device *hwmon_dev;
 	struct ntc_data *data;
+	int ret;
 
-	data = ntc_thermistor_parse_dt(dev);
-	if (IS_ERR(data))
-		return PTR_ERR(data);
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
 
-	if (!data) {
-		dev_err(dev, "No platform init data supplied.\n");
-		return -ENODEV;
-	}
+	ret = ntc_thermistor_parse_dt(dev, data);
+	if (ret)
+		return ret;
 
 	if (data->pullup_uv == 0 ||
 	    (data->pullup_ohm == 0 && data->connect ==