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| author | Benjamin Gaignard <benjamin.gaignard@linaro.org> | 2017-04-04 09:47:51 +0200 |
|---|---|---|
| committer | Jonathan Cameron <jic23@kernel.org> | 2017-04-14 15:08:31 +0100 |
| commit | 4adec7da0536a345d901d7ba55b6c93a14eeeaff (patch) | |
| tree | f8eb05106b3e15c05e3241569aceebacf629bedc /Documentation | |
| parent | 510c01063085b5dc7788d9953f9bf58e16b631e8 (diff) | |
| download | linux-4adec7da0536a345d901d7ba55b6c93a14eeeaff.tar.gz linux-4adec7da0536a345d901d7ba55b6c93a14eeeaff.tar.bz2 linux-4adec7da0536a345d901d7ba55b6c93a14eeeaff.zip | |
iio: stm32 trigger: Add quadrature encoder device
One of the features of STM32 trigger hardware block is a quadrature
encoder that can counts up/down depending of the levels and edges
of the selected external pins.
This patch allow to read/write the counter, get it direction,
set/get quadrature modes and get scale factor.
When counting up preset value is the limit of the counter.
When counting down the counter start from preset value down to 0.
This preset value could be set/get by using
/sys/bus/iio/devices/iio:deviceX/in_count0_preset attribute.
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Reviewed-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 | 46 |
1 files changed, 42 insertions, 4 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 index 6534a60037ff..a55ad44446c5 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 @@ -3,11 +3,15 @@ KernelVersion: 4.11 Contact: benjamin.gaignard@st.com Description: Reading returns the list possible master modes which are: - - "reset" : The UG bit from the TIMx_EGR register is used as trigger output (TRGO). - - "enable" : The Counter Enable signal CNT_EN is used as trigger output. + - "reset" : The UG bit from the TIMx_EGR register is + used as trigger output (TRGO). + - "enable" : The Counter Enable signal CNT_EN is used + as trigger output. - "update" : The update event is selected as trigger output. - For instance a master timer can then be used as a prescaler for a slave timer. - - "compare_pulse" : The trigger output send a positive pulse when the CC1IF flag is to be set. + For instance a master timer can then be used + as a prescaler for a slave timer. + - "compare_pulse" : The trigger output send a positive pulse + when the CC1IF flag is to be set. - "OC1REF" : OC1REF signal is used as trigger output. - "OC2REF" : OC2REF signal is used as trigger output. - "OC3REF" : OC3REF signal is used as trigger output. @@ -27,3 +31,37 @@ Description: Reading returns the current sampling frequency. Writing an value different of 0 set and start sampling. Writing 0 stop sampling. + +What: /sys/bus/iio/devices/iio:deviceX/in_count0_preset +KernelVersion: 4.12 +Contact: benjamin.gaignard@st.com +Description: + Reading returns the current preset value. + Writing sets the preset value. + When counting up the counter starts from 0 and fires an + event when reach preset value. + When counting down the counter start from preset value + and fire event when reach 0. + +What: /sys/bus/iio/devices/iio:deviceX/in_count_quadrature_mode_available +KernelVersion: 4.12 +Contact: benjamin.gaignard@st.com +Description: + Reading returns the list possible quadrature modes. + +What: /sys/bus/iio/devices/iio:deviceX/in_count0_quadrature_mode +KernelVersion: 4.12 +Contact: benjamin.gaignard@st.com +Description: + Configure the device counter quadrature modes: + channel_A: + Encoder A input servers as the count input and B as + the UP/DOWN direction control input. + + channel_B: + Encoder B input serves as the count input and A as + the UP/DOWN direction control input. + + quadrature: + Encoder A and B inputs are mixed to get direction + and count with a scale of 0.25. |