iio: adc: ad7606: use realbits for sign-extending in scan_direct

Currently the 'ad7606' driver supports parts with 18 and 16 bits
resolutions.
But when adding support for AD7607 (which has a 14-bit resolution) we
should check for the 'realbits' field, to be able to sign-extend correctly.

Signed-off-by: Alexandru Ardelean <aardelean@baylibre.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20241025095939.271811-3-aardelean@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index ae49f4b..effb98b 100644 (file)
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -568,7 +568,7 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
                              int *val)
 {
        struct ad7606_state *st = iio_priv(indio_dev);
-       unsigned int storagebits = st->chip_info->channels[1].scan_type.storagebits;
+       unsigned int realbits = st->chip_info->channels[1].scan_type.realbits;
        const struct iio_chan_spec *chan;
        int ret;
 
@@ -603,15 +603,15 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
 
        chan = &indio_dev->channels[ch + 1];
        if (chan->scan_type.sign == 'u') {
-               if (storagebits > 16)
+               if (realbits > 16)
                        *val = st->data.buf32[ch];
                else
                        *val = st->data.buf16[ch];
        } else {
-               if (storagebits > 16)
-                       *val = sign_extend32(st->data.buf32[ch], 17);
+               if (realbits > 16)
+                       *val = sign_extend32(st->data.buf32[ch], realbits - 1);
                else
-                       *val = sign_extend32(st->data.buf16[ch], 15);
+                       *val = sign_extend32(st->data.buf16[ch], realbits - 1);
        }
 
 error_ret: