iio: adc: stm32: add optional st,min-sample-time-nsecs

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STM32 ADC allows each channel to be sampled with a different sampling time,
by setting SMPR registers. Basically, value depends on local electrical
properties. Selecting correct value for sampling time highly depends on
analog source impedance. There is a manual that may help in this process:
'How to get the best ADC accuracy in STM32...'

This patch allows to configure minimum sampling time via device tree,
either for:
- all channels at once:
  st,min-sample-time-nsecs = <10000>;

- independently for each channel (must match "st,adc-channels" list):
  st,adc-channels = <0 1>;
  st,min-sample-time-nsecs = <5000 10000>;

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

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Fabrice Gasnier 2017-07-24 18:10:40 +02:00 • committed by Jonathan Cameron

parent bc8e1f5b21

commit ee2ac1cdd3

1 changed files with 136 additions and 4 deletions

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drivers/iio/adc/stm32-adc.c

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