iio: adc: stm32: add trigger polarity extended attribute

Define extended attribute so that user may choose rising, falling or both
edges for external trigger sources.
Default to rising edge in case it isn't set.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Fabrice Gasnier
2017-01-26 15:28:31 +01:00
committed by Jonathan Cameron
parent f24a33b3e2
commit 732f2dc468
2 changed files with 63 additions and 1 deletions

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What: /sys/bus/iio/devices/triggerX/trigger_polarity
KernelVersion: 4.11
Contact: fabrice.gasnier@st.com
Description:
The STM32 ADC can be configured to use external trigger sources
(e.g. timers, pwm or exti gpio). Then, it can be tuned to start
conversions on external trigger by either:
- "rising-edge"
- "falling-edge"
- "both-edges".
Reading returns current trigger polarity.
Writing value before enabling conversions sets trigger polarity.
What: /sys/bus/iio/devices/triggerX/trigger_polarity_available
KernelVersion: 4.11
Contact: fabrice.gasnier@st.com
Description:
List all available trigger_polarity settings.