iio: adc: stm32: add support for differential channels

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STM32H7 ADC channels can be configured either as single ended or
differential with 'st,adc-channels' or 'st,adc-diff-channels'
(positive and negative input pair: <vinp vinn>, ...).

Differential channels have different offset and scale, from spec:
raw value = (full_scale / 2) * (1 + (vinp - vinn) / vref).
Add offset attribute.

Differential channels are selected by DIFSEL register. Negative
inputs must be added to pre-selected channels as well (PCSEL).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

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Fabrice Gasnier 2017-10-25 11:27:45 +02:00 • committed by Jonathan Cameron

parent 0bae72aa8a

commit 3fb2e24ed7

1 changed files with 103 additions and 20 deletions

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drivers/iio/adc/stm32-adc.c

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