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... This patchset must be applied on top of the following counter subsystem patchset : https://lore.kernel.org/all/cover.1663693757.git.william.gray@xxxxxxxxxx/ Modifications since v7 : - Simplify ecap_cnt_capture_get/set_evmode() functions - Modify ecap_cnt_count_write() callback - Modify ecap_cnt_watch_validate() callback - Modify ecap_cnt_pol_read() callback - Add ecap_cnt_cap_write() callback - Modify ecap_cnt_nb_ovf_write() callback - Use DEFINE_COUNTER_ARRAY_CAPTURE() and COUNTER_COMP_ARRAY_CAPTURE() macros - Push COUNTER_EVENT_OVERFLOW to all 4 channels in ISR - Redefine time_cntr and related functions as u32 - Remove ecap_cnt_capture_set_evmode() function call in probe function 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 | 7 + drivers/counter/Kconfig | 15 + drivers/counter/Makefile | 1 + drivers/counter/ti-ecap-capture.c | 621 ++++++++++++++++++ 6 files changed, 719 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
