On Fri, Sep 23, 2022 at 04:24:33PM +0200, Julien Panis wrote: > 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 v8 : > - Add documentation to private driver structure > - Add mutex to prevent IO race conditions > - Stop counter before disabling interrupts in ecap_cnt_capture_disable() function > - Remove returning of status in ecap_cnt_count_get/set_val() functions > - Remove unnecessary 'return -EBUSY' in all callbacks > - Remove unnecessary '.id = 0' in ecap_cnt_counts[] > - Modify driver info in MAINTAINER 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 | 9 + > drivers/counter/Kconfig | 15 + > drivers/counter/Makefile | 1 + > drivers/counter/ti-ecap-capture.c | 614 ++++++++++++++++++ > 6 files changed, 714 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 Queued for counter-next with a minor context adjustment for sysfs-bus-counter changes. Thanks, William Breathitt Gray
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