[PATCH 3/6] iio: adc: ad7606: use realbits for sign-extending in scan_direct

[Alexandru Ardelean <aardelean@baylibre.com>]

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>
---
 drivers/iio/adc/ad7606.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index d0fe9fd65f3f..a1f0c2feb04a 100644
--- 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 +603,29 @@ 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)
+		switch (realbits) {
+		case 18:
 			*val = st->data.buf32[ch];
-		else
+			break;
+		case 16:
 			*val = st->data.buf16[ch];
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
 	} else {
-		if (storagebits > 16)
+		switch (realbits) {
+		case 18:
 			*val = sign_extend32(st->data.buf32[ch], 17);
-		else
+			break;
+		case 16:
 			*val = sign_extend32(st->data.buf16[ch], 15);
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
 	}
 
 error_ret:
-- 
2.46.1