diff options
| author | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2022-06-26 13:29:32 +0100 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2022-08-15 22:30:01 +0100 |
| commit | 5c64990b99aa91622cf044a9a2f7a78de8f770a2 (patch) | |
| tree | 7dd6a06389ed9d6bfc41acb2b65d5abf46b919e9 /include/linux/iio | |
| parent | 431e9147b4667d67399fe5db4f8203d55811951b (diff) | |
iio: core: Introduce _zeropoint for differential channels
Address an ABI gap for device where the offset of both lines in a
differential pair may be controlled so as to allow a wider range of
inputs, but without having any direct effect of the differential
measurement.
_offset cannot be used as to remain in line with existing usage,
userspace would be expected to apply it as (_raw + _offset) * _scale
whereas _zeropoint is not. i.e. If we were computing the differential
in software it would be.
((postive_raw + _zeropoint) - (negative_raw + zeropoint) + _offset) * _scale
= ((postive_raw - negative_raw) + _offset) * _scale
= (differential_raw + _offset) * _scale
Similarly calibbias is expected to tweak the measurement seen, not
the adjust the two lines of the differential pair.
Needed for in_capacitanceX-capacitanceY_zeropoint for the
AD7746 CDC driver.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220626122938.582107-12-jic23@kernel.org
Diffstat (limited to 'include/linux/iio')
| -rw-r--r-- | include/linux/iio/types.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h index a7aa91f3a8dc..27143b03909d 100644 --- a/include/linux/iio/types.h +++ b/include/linux/iio/types.h @@ -63,6 +63,7 @@ enum iio_chan_info_enum { IIO_CHAN_INFO_OVERSAMPLING_RATIO, IIO_CHAN_INFO_THERMOCOUPLE_TYPE, IIO_CHAN_INFO_CALIBAMBIENT, + IIO_CHAN_INFO_ZEROPOINT, }; #endif /* _IIO_TYPES_H_ */ |