staging:iio:ad5933: Report temperature as raw value

We shouldn't be doing the unit conversion in kernel space. Just report the
raw value for the property and the scale. Userspace can do the conversion if
necessary.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/impedance-analyzer/ad5933.c

@@ -113,7 +113,8 @@ static const struct iio_chan_spec ad5933_channels[] = {
 		.type = IIO_TEMP,
 		.indexed = 1,
 		.channel = 0,
-		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE),
 		.address = AD5933_REG_TEMP_DATA,
 		.scan_index = -1,
 		.scan_type = {
@@ -520,12 +521,11 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
 {
 	struct ad5933_state *st = iio_priv(indio_dev);
 	__be16 dat;
-	int ret = -EINVAL;
+	int ret;
 
-	mutex_lock(&indio_dev->mlock);
 	switch (m) {
 	case IIO_CHAN_INFO_RAW:
-	case IIO_CHAN_INFO_PROCESSED:
+		mutex_lock(&indio_dev->mlock);
 		if (iio_buffer_enabled(indio_dev)) {
 			ret = -EBUSY;
 			goto out;
@@ -543,16 +543,16 @@ static int ad5933_read_raw(struct iio_dev *indio_dev,
 		if (ret < 0)
 			goto out;
 		mutex_unlock(&indio_dev->mlock);
-		ret = be16_to_cpu(dat);
-		/* Temp in Milli degrees Celsius */
-		if (ret < 8192)
-			*val = ret * 1000 / 32;
-		else
-			*val = (ret - 16384) * 1000 / 32;
+		*val = sign_extend32(be16_to_cpu(dat), 13);
 
 		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1000;
+		*val2 = 5;
+		return IIO_VAL_FRACTIONAL_LOG2;
 	}
 
+	return -EINVAL;
 out:
 	mutex_unlock(&indio_dev->mlock);
 	return ret;