iio: at91-sama5d2: Fix incorrect sign extension

commit 652e7df485c6884d552085ae2c73efa6cfea3547 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index c485ff6f408bf11db0ba023ec120246d58f04323..129c3adad4c05c1564631082494d059b37a67620 100644 (file)
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -1375,7 +1375,8 @@ 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;
        }