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| 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 /drivers/iio/industrialio-core.c | |
| parent | staging: iio: cdc: ad7746: Use _raw and _scale for temperature channels. (diff) | |
| download | linux-5c64990b99aa91622cf044a9a2f7a78de8f770a2.tar.gz linux-5c64990b99aa91622cf044a9a2f7a78de8f770a2.tar.bz2 linux-5c64990b99aa91622cf044a9a2f7a78de8f770a2.zip | |
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 'drivers/iio/industrialio-core.c')
| -rw-r--r-- | drivers/iio/industrialio-core.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 40ebc63b7919..67d3d01d2dac 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -168,6 +168,7 @@ static const char * const iio_chan_info_postfix[] = { [IIO_CHAN_INFO_OVERSAMPLING_RATIO] = "oversampling_ratio", [IIO_CHAN_INFO_THERMOCOUPLE_TYPE] = "thermocouple_type", [IIO_CHAN_INFO_CALIBAMBIENT] = "calibambient", + [IIO_CHAN_INFO_ZEROPOINT] = "zeropoint", }; /** * iio_device_id() - query the unique ID for the device |