hwmon: (ntc_thermistor) Ensure iio channel is of type IIO_VOLTAGE

When configured via device tree, the associated iio device needs to be
measuring voltage for the conversion to resistance to be correct.
Return -EINVAL if that is not the case.

Signed-off-by: Chris Lesiak <chris.lesiak@licor.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index 112e4d45e4a0..68800115876b 100644
--- a/drivers/hwmon/ntc_thermistor.c
+++ b/drivers/hwmon/ntc_thermistor.c
@@ -239,8 +239,10 @@ static struct ntc_thermistor_platform_data *
 ntc_thermistor_parse_dt(struct platform_device *pdev)
 {
         struct iio_channel *chan;
+        enum iio_chan_type type;
         struct device_node *np = pdev->dev.of_node;
         struct ntc_thermistor_platform_data *pdata;
+        int ret;
 
         if (!np)
                 return NULL;
@@ -253,6 +255,13 @@ ntc_thermistor_parse_dt(struct platform_device *pdev)
         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", &pdata->pullup_uv))
                 return ERR_PTR(-ENODEV);
         if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm))