Add gain, offset and phase (as a delay) calibration support, for
ad7606b, ad7606c16 and ad7606c18.

Calibration is available for devices with software mode capability. 

Offset and phase calibration is configurable by sysfs attributes, while
gain calibration value in ohms must match the external RFilter value,
when an external RFilter is available, so implemented through a specific
devicetree "adi,rfilter-ohms" property.

Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
---
Angelo Dureghello (5):
      Documentation: ABI: IIO: add calibphase_delay documentation
      iio: core: add ADC phase calibration definition
      iio: adc: ad7606: add offset and phase calibration support
      dt-bindings: iio: adc: adi,ad7606: add gain calibration support
      iio: adc: ad7606: add gain calibration support

 Documentation/ABI/testing/sysfs-bus-iio            |  20 ++
 .../devicetree/bindings/iio/adc/adi,ad7606.yaml    |  14 ++
 drivers/iio/adc/ad7606.c                           | 213 +++++++++++++++++++++
 drivers/iio/adc/ad7606.h                           |  13 ++
 drivers/iio/industrialio-core.c                    |   1 +
 include/linux/iio/types.h                          |   1 +
 6 files changed, 262 insertions(+)
---
base-commit: e22e3d5089987cb4250801623026992b2ba4645d
change-id: 20250429-wip-bl-ad7606-calibration-20a396a60352

Best regards,
-- 
Angelo Dureghello <adureghello@baylibre.com>