iio: at91-sama5d2: Fix incorrect sign extension

Use scan_type when processing raw data which also fixes that the sign
extension was from the wrong bit.

Use channel definition as root of trust and replace constant
when reading elements directly using the raw sysfs attributes.

Fixes: 6794e23fa3fe ("iio: adc: at91-sama5d2_adc: add support for oversampling resolution")
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Eugen Hristev <eugen.hristev@microchip.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20211104082413.3681212-9-gwendal@chromium.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 4c922ef634f8e81b5c45ce4dfcdf4f31722f03ca..92a57cf10fba4a05d797b7308404a66255263824 100644 (file)
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -1586,7 +1586,8 @@ static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
                *val = st->conversion_value;
                ret = at91_adc_adjust_val_osr(st, val);
                if (chan->scan_type.sign == 's')
-                       *val = sign_extend32(*val, 11);
+                       *val = sign_extend32(*val,
+                                            chan->scan_type.realbits - 1);
                st->conversion_done = false;
        }