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| author |   Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2022-06-26 13:29:33 +0100 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2022-08-15 22:30:01 +0100 |
| commit | 2d72ead25abb72996a7e92608224d2503a3bac9c (patch) | |
| tree | 23c2a006bd3b6d05fa31ab2e5a20aee5ac3f5ee6 /drivers/staging/iio | |
| parent | iio: core: Introduce _zeropoint for differential channels (diff) | |
| download | linux-dev-2d72ead25abb72996a7e92608224d2503a3bac9c.tar.xz linux-dev-2d72ead25abb72996a7e92608224d2503a3bac9c.zip | |
staging: iio: cdc: ad7746: Switch from _offset to _zeropoint for differential channels.
As this offset is applied equally to both lines of the differential
pair, _ofset should not be used. Use the new ABI _zeropoint instead
to avoid userspace software applying this value when calculating
real value = (_raw + _offset) * _scale
Also add a comment to explain why an offset of 0x800000 is applied
within the driver rather than exposed to userspace.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220626122938.582107-13-jic23@kernel.org
Diffstat (limited to 'drivers/staging/iio')
| -rw-r--r-- | drivers/staging/iio/cdc/ad7746.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c index 3e8e7836a583..d323ae4d9992 100644 --- a/drivers/staging/iio/cdc/ad7746.c +++ b/drivers/staging/iio/cdc/ad7746.c @@ -207,7 +207,7 @@ static const struct iio_chan_spec ad7746_channels[] = { .channel = 0, .channel2 = 2, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | - BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET), + BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_ZEROPOINT), .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) | BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ), .address = CIN1_DIFF, @@ -229,7 +229,7 @@ static const struct iio_chan_spec ad7746_channels[] = { .channel = 1, .channel2 = 3, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | - BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_OFFSET), + BIT(IIO_CHAN_INFO_CALIBSCALE) | BIT(IIO_CHAN_INFO_ZEROPOINT), .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_CALIBBIAS) | BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ), .address = CIN2_DIFF, @@ -506,6 +506,7 @@ static int ad7746_write_raw(struct iio_dev *indio_dev, return 0; case IIO_CHAN_INFO_OFFSET: + case IIO_CHAN_INFO_ZEROPOINT: if (val < 0 || val > 43008000) /* 21pF */ return -EINVAL; @@ -581,6 +582,10 @@ static int ad7746_read_channel(struct iio_dev *indio_dev, if (ret < 0) return ret; + /* + * Offset applied internally becaue the _offset userspace interface is + * needed for the CAP DACs which apply a controllable offset. + */ *val = get_unaligned_be24(data) - 0x800000; return 0; @@ -637,6 +642,7 @@ static int ad7746_read_raw(struct iio_dev *indio_dev, return IIO_VAL_INT; case IIO_CHAN_INFO_OFFSET: + case IIO_CHAN_INFO_ZEROPOINT: *val = FIELD_GET(AD7746_CAPDAC_DACP_MASK, chip->capdac[chan->channel][chan->differential]) * 338646; |