[PATCH v3 8/9] staging: iio: ad2s1200: Add scaling factor for angle channel

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A scaling factor of approximately 2 * Pi / (2^12 -1) is added,
to scale the 12-bits angular position to radians.

A return type of IIO_VAL_INT_PLUS_NANO is used, so that the scale of
both the angle channel and angular velocity channel has 7 significant
digits.

Signed-off-by: David Veenstra <davidjulianveenstra@xxxxxxxxx>
---
Changes in v3:
 - A decimal approximation of the scale is used, instead
   of a fractional approximation.
 - Remove unneeded explanation of iio_convert_raw_to_processed.

 drivers/staging/iio/resolver/ad2s1200.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/staging/iio/resolver/ad2s1200.c b/drivers/staging/iio/resolver/ad2s1200.c
index 3e1696e52c38..d2b62308b31d 100644
--- a/drivers/staging/iio/resolver/ad2s1200.c
+++ b/drivers/staging/iio/resolver/ad2s1200.c
@@ -60,6 +60,11 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev,
 	switch (m) {
 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
+		case IIO_ANGL:
+			/* 2 * Pi / (2^12 - 1) ~= 0.001534355 */
+			*val = 0;
+			*val2 = 1534355;
+			return IIO_VAL_INT_PLUS_NANO;
 		case IIO_ANGL_VEL:
 			/* 2 * Pi ~= 6.283185 */
 			*val = 6;
@@ -114,6 +119,7 @@ static const struct iio_chan_spec ad2s1200_channels[] = {
 		.indexed = 1,
 		.channel = 0,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
 	}, {
 		.type = IIO_ANGL_VEL,
 		.indexed = 1,
-- 
2.16.2

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