Add documentation for the cyclic function infrastructure, including the cyclic command.
Signed-off-by: Stefan Roese sr@denx.de Reviewed-by: Simon Glass sjg@chromium.org --- v4: - Minor spelling fix - Added Simon's RB tag
v3: - New patch
doc/develop/cyclic.rst | 50 ++++++++++++++++++++++++++++++++++++++++ doc/develop/index.rst | 1 + doc/usage/cmd/cyclic.rst | 45 ++++++++++++++++++++++++++++++++++++ doc/usage/index.rst | 1 + 4 files changed, 97 insertions(+) create mode 100644 doc/develop/cyclic.rst create mode 100644 doc/usage/cmd/cyclic.rst
diff --git a/doc/develop/cyclic.rst b/doc/develop/cyclic.rst new file mode 100644 index 000000000000..43bedacb9f88 --- /dev/null +++ b/doc/develop/cyclic.rst @@ -0,0 +1,50 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +Cyclic functions +================ + +The cyclic function execution infrastruture provides a way to periodically +execute code, e.g. every 100ms. Examples for such functions might be LED +blinking etc. The functions that are hooked into this cyclic list should +be small timewise as otherwise the execution of the other code that relies +on a high frequent polling (e.g. UART rx char ready check) might be +delayed too much. To detect cyclic functions with a too long execution +time, the Kconfig option `CONFIG_CYCLIC_MAX_CPU_TIME_US` is introduced, +which configures the max allowed time for such a cyclic function. If it's +execution time exceeds this time, this cyclic function will get removed +from the cyclic list. + +Registering a cyclic function +----------------------------- + +To register a cyclic function, use something like this:: + + static void cyclic_demo(void *ctx) + { + /* Just a small dummy delay here */ + udelay(10); + } + + int board_init(void) + { + struct cyclic_info *cyclic; + + /* Register demo cyclic function */ + cyclic = cyclic_register(cyclic_demo, 10 * 1000, "cyclic_demo", NULL); + if (!cyclic) + printf("Registering of cyclic_demo failed\n"); + + return 0; + } + +This will register the function `cyclic_demo()` to be periodically +executed all 10ms. + +How is this cyclic functionality integrated / executed? +-------------------------------------------------------- + +The cyclic infrastructure integrates the main function responsible for +calling all registered cyclic functions cyclic_run() into the common +WATCHDOG_RESET macro. This guarantees that cyclic_run() is executed +very often, which is necessary for the cyclic functions to get scheduled +and executed at their configured periods. diff --git a/doc/develop/index.rst b/doc/develop/index.rst index f7ee09db2467..ce6b38e57629 100644 --- a/doc/develop/index.rst +++ b/doc/develop/index.rst @@ -27,6 +27,7 @@ Implementation ci_testing commands config_binding + cyclic devicetree/index distro driver-model/index diff --git a/doc/usage/cmd/cyclic.rst b/doc/usage/cmd/cyclic.rst new file mode 100644 index 000000000000..3085cc7204c0 --- /dev/null +++ b/doc/usage/cmd/cyclic.rst @@ -0,0 +1,45 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +cyclic command +============== + +Synopsis +-------- + +:: + + cyclic list + +Description +----------- + +The cyclic list command provides a list of the currently registered +cyclic functions. + +This shows the following information: + +Function + Function name + +cpu-time + Total time spent in this cyclic function. + +Frequency + Frequency of execution of this function, e.g. 100 times/s for a + pediod of 10ms. + + +See :doc:`../../develop/cyclic` for more information on cyclic functions. + +Example +------- + +:: + + => cyclic list + function: cyclic_demo, cpu-time: 52906 us, frequency: 99.20 times/s + +Configuration +------------- + +The cyclic command is only available if CONFIG_CMD_CYCLIC=y. diff --git a/doc/usage/index.rst b/doc/usage/index.rst index 28f9683a3e6f..1a0665ec1b78 100644 --- a/doc/usage/index.rst +++ b/doc/usage/index.rst @@ -33,6 +33,7 @@ Shell commands cmd/bootz cmd/cbsysinfo cmd/conitrace + cmd/cyclic cmd/dm cmd/echo cmd/env