Messages in this thread | | | From | Julien Panis <> | Subject | [PATCH v7 0/4] ECAP support on TI AM62x SoC | Date | Wed, 21 Sep 2022 12:06:23 +0200 |
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The Enhanced Capture (ECAP) module can be used to timestamp events detected on signal input pin. It can be used for time measurements of pulse train signals.
ECAP module includes 4 timestamp capture registers. For all 4 sequenced timestamp capture events (0->1->2->3->0->...), edge polarity (falling/rising edge) can be selected.
This driver leverages counter subsystem to : - select edge polarity for all 4 capture events (event mode) - log timestamps for each capture event Event polarity, and CAP0/1/2/3 timestamps give all the information about the input pulse train. Further information can easily be computed : period and/or duty cycle if frequency is constant, elapsed time between pulses, etc...
Modifications since v6: - Leverage counter array components (RFC PATCH v5) - Remove the redundant doc of 'capture' items in sysfs-bus-counter ABI file - Add driver info to MAINTAINERS file
Userspace commands : ### CLOCK SIGNAL ### cd /sys/bus/counter/devices/counter0/signal0
# Get frequency cat frequency
### INPUT SIGNAL ### cd /sys/bus/counter/devices/counter0/signal1
# Get polarity for each capture event cat polarity0 cat polarity1 cat polarity2 cat polarity3
# Set polarity for each capture event echo positive > polarity0 echo negative > polarity1 echo positive > polarity2 echo negative > polarity3
### COUNT ### cd /sys/bus/counter/devices/counter0/count0
# Get ceiling (counter max value) cat ceiling
# Reset number of overflows & current timebase counter value echo 0 > num_overflows echo 0 > count
# Run ECAP echo 1 > enable
# Get number of overflows & current timebase counter value cat num_overflows cat count
# Get captured timestamps cat capture0 cat capture1 cat capture2 cat capture3
# Note that counter watches can also be used to get # data from userspace application # -> see tools/counter/counter_example.c
# Pause ECAP echo 0 > enable
Julien Panis (4): dt-bindings: counter: add ti,am62-ecap-capture.yaml Documentation: ABI: sysfs-bus-counter: add frequency & num_overflows items counter: ti-ecap-capture: capture driver support for ECAP MAINTAINERS: add TI ECAP driver info
Documentation/ABI/testing/sysfs-bus-counter | 14 + .../counter/ti,am62-ecap-capture.yaml | 61 ++ MAINTAINERS | 6 + drivers/counter/Kconfig | 15 + drivers/counter/Makefile | 1 + drivers/counter/ti-ecap-capture.c | 614 ++++++++++++++++++ 6 files changed, 711 insertions(+) create mode 100644 Documentation/devicetree/bindings/counter/ti,am62-ecap-capture.yaml create mode 100644 drivers/counter/ti-ecap-capture.c
-- 2.37.3
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