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iio: inkern: make a best effort on offset calculation

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commit ca85123354 upstream.

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: 48e44ce0f8 ("iio:inkern: Add function to read the processed value")
Signed-off-by: Liam Beguin <liambeguin@gmail.com>
Reviewed-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220108205319.2046348-4-liambeguin@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Liam Beguin 2022-01-08 15:53:06 -05:00 committed by Greg Kroah-Hartman
parent e264a96834
commit 6b23c33920
1 changed files with 27 additions and 5 deletions
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32
drivers/iio/inkern.c
View file

@ -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 >>= offset_val2;
break;
default:
return -EINVAL;
}
raw64 += offset_val;
}
scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
IIO_CHAN_INFO_SCALE);