[PATCH 1/3] iio: adc: ad7923: fix channel readings for some variants

[Nuno Sá <nuno.sa@xxxxxxxxxx>]

Some of the supported devices have 4 or 2 LSB trailing bits that should
not be taken into account. Hence we need to shift these bits out which
fits perfectly on the scan type shift property. This change fixes both
raw and buffered reads.

Fixes: f2f7a449707e ("iio:adc:ad7923: Add support for the ad7904/ad7914/ad7924")
Fixes: 851644a60d20 ("iio: adc: ad7923: Add support for the ad7908/ad7918/ad7928")
Signed-off-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
---
 drivers/iio/adc/ad7923.c | 46 +++++++++++++++++++++-------------------
 1 file changed, 24 insertions(+), 22 deletions(-)

diff --git a/drivers/iio/adc/ad7923.c b/drivers/iio/adc/ad7923.c
index edad1f30121d..910cf05e75cd 100644
--- a/drivers/iio/adc/ad7923.c
+++ b/drivers/iio/adc/ad7923.c
@@ -80,7 +80,7 @@ enum ad7923_id {
 	AD7928
 };
 
-#define AD7923_V_CHAN(index, bits)					\
+#define AD7923_V_CHAN(index, bits, _shift)				\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.indexed = 1,						\
@@ -93,38 +93,39 @@ enum ad7923_id {
 			.sign = 'u',					\
 			.realbits = (bits),				\
 			.storagebits = 16,				\
+			.shift = (_shift),				\
 			.endianness = IIO_BE,				\
 		},							\
 	}
 
-#define DECLARE_AD7923_CHANNELS(name, bits) \
+#define DECLARE_AD7923_CHANNELS(name, bits, shift) \
 const struct iio_chan_spec name ## _channels[] = { \
-	AD7923_V_CHAN(0, bits), \
-	AD7923_V_CHAN(1, bits), \
-	AD7923_V_CHAN(2, bits), \
-	AD7923_V_CHAN(3, bits), \
+	AD7923_V_CHAN(0, bits, shift), \
+	AD7923_V_CHAN(1, bits, shift), \
+	AD7923_V_CHAN(2, bits, shift), \
+	AD7923_V_CHAN(3, bits, shift), \
 	IIO_CHAN_SOFT_TIMESTAMP(4), \
 }
 
-#define DECLARE_AD7908_CHANNELS(name, bits) \
+#define DECLARE_AD7908_CHANNELS(name, bits, shift) \
 const struct iio_chan_spec name ## _channels[] = { \
-	AD7923_V_CHAN(0, bits), \
-	AD7923_V_CHAN(1, bits), \
-	AD7923_V_CHAN(2, bits), \
-	AD7923_V_CHAN(3, bits), \
-	AD7923_V_CHAN(4, bits), \
-	AD7923_V_CHAN(5, bits), \
-	AD7923_V_CHAN(6, bits), \
-	AD7923_V_CHAN(7, bits), \
+	AD7923_V_CHAN(0, bits, shift), \
+	AD7923_V_CHAN(1, bits, shift), \
+	AD7923_V_CHAN(2, bits, shift), \
+	AD7923_V_CHAN(3, bits, shift), \
+	AD7923_V_CHAN(4, bits, shift), \
+	AD7923_V_CHAN(5, bits, shift), \
+	AD7923_V_CHAN(6, bits, shift), \
+	AD7923_V_CHAN(7, bits, shift), \
 	IIO_CHAN_SOFT_TIMESTAMP(8), \
 }
 
-static DECLARE_AD7923_CHANNELS(ad7904, 8);
-static DECLARE_AD7923_CHANNELS(ad7914, 10);
-static DECLARE_AD7923_CHANNELS(ad7924, 12);
-static DECLARE_AD7908_CHANNELS(ad7908, 8);
-static DECLARE_AD7908_CHANNELS(ad7918, 10);
-static DECLARE_AD7908_CHANNELS(ad7928, 12);
+static DECLARE_AD7923_CHANNELS(ad7904, 8, 4);
+static DECLARE_AD7923_CHANNELS(ad7914, 10, 2);
+static DECLARE_AD7923_CHANNELS(ad7924, 12, 0);
+static DECLARE_AD7908_CHANNELS(ad7908, 8, 4);
+static DECLARE_AD7908_CHANNELS(ad7918, 10, 2);
+static DECLARE_AD7908_CHANNELS(ad7928, 12, 0);
 
 static const struct ad7923_chip_info ad7923_chip_info[] = {
 	[AD7904] = {
@@ -268,7 +269,8 @@ static int ad7923_read_raw(struct iio_dev *indio_dev,
 			return ret;
 
 		if (chan->address == EXTRACT(ret, 12, 4))
-			*val = EXTRACT(ret, 0, 12);
+			*val = EXTRACT(ret, chan->scan_type.shift,
+				       chan->scan_type.realbits);
 		else
 			return -EIO;
 
-- 
2.37.3