[PATCH v9 03/14] iio: inkern: make a best effort on offset calculation

Liam Beguin
2021-11-15T03:47:58Z

iio_convert_raw_to_processed_unlocked() assumes the offset is an
integer. Make a best effort to get a valid offset value for fractional
cases without breaking implicit truncations.

Fixes: 48e44ce0f881 ("iio:inkern: Add function to read the processed value")
Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
drivers/iio/inkern.c | 32 +++++++++++++++++++++++++++-----
1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index dbe13fad3cbb..aff6d2d3447c 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -595,13 +595,35 @@ 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:
+ case IIO_VAL_INT_PLUS_NANO:
+ /*
+ * Both IIO_VAL_INT_PLUS_MICRO and IIO_VAL_INT_PLUS_NANO
+ * implicitely truncate the offset to it's integer form.
+ */
+ break;
+ case IIO_VAL_FRACTIONAL:
+ offset_val /= offset_val2;
+ break;
+ case IIO_VAL_FRACTIONAL_LOG2:
+ offset_val /= (1 << offset_val2);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ raw64 += offset_val;
+ }

scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
IIO_CHAN_INFO_SCALE);
--
2.32.0.452.g940fe202adcb