[PATCH v2 3/8] iio: inkern: error out on unsupported offset type

[Liam Beguin <liambeguin@gmail.com>]

From: Liam Beguin <lvb@xiphos.com>

iio_convert_raw_to_processed_unlocked() assumes the offset is an
integer.
Make that clear to the consumer by returning an error on unsupported
offset types without breaking valid implicit truncations.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 drivers/iio/inkern.c | 34 +++++++++++++++++++++++++++++-----
 1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index b69027690ed5..0b5667f22b1d 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -578,13 +578,37 @@ EXPORT_SYMBOL_GPL(iio_read_channel_average_raw);
 static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
 	int raw, int *processed, unsigned int scale)
 {
-	int scale_type, scale_val, scale_val2, offset;
+	int scale_type, scale_val, scale_val2;
+	int offset_type, offset_val, offset_val2;
 	s64 raw64 = raw;
-	int ret;
 
-	ret = iio_channel_read(chan, &offset, NULL, IIO_CHAN_INFO_OFFSET);
-	if (ret >= 0)
-		raw64 += offset;
+	offset_type = iio_channel_read(chan, &offset_val, &offset_val2,
+				       IIO_CHAN_INFO_OFFSET);
+	if (offset_type >= 0) {
+		switch (offset_type) {
+		case IIO_VAL_INT:
+			break;
+		case IIO_VAL_INT_PLUS_MICRO:
+			if (offset_val2 > 1000)
+				return -EINVAL;
+			break;
+		case IIO_VAL_INT_PLUS_NANO:
+			if (offset_val2 > 1000000)
+				return -EINVAL;
+		case IIO_VAL_FRACTIONAL:
+			if (offset_val2 != 1)
+				return -EINVAL;
+			break;
+		case IIO_VAL_FRACTIONAL_LOG2:
+			if (offset_val2)
+				return -EINVAL;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		raw64 += offset_val;
+	}
 
 	scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
 					IIO_CHAN_INFO_SCALE);
-- 
2.30.1.489.g328c10930387