From 5c64990b99aa91622cf044a9a2f7a78de8f770a2 Mon Sep 17 00:00:00 2001 From: Jonathan Cameron Date: Sun, 26 Jun 2022 13:29:32 +0100 Subject: 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 Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20220626122938.582107-12-jic23@kernel.org --- include/linux/iio/types.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') 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_ */ -- cgit v1.2.3-59-g8ed1b