iio: inkern: make a best effort on offset calculation

commit ca85123354e1a65a22170286387b4791997fe864 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: 48e44ce0f881 ("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>

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index b690276..b596636 100644 (file)
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -578,13 +578,35 @@ 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);