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6250945367
WATCHDOG_RESET is no more. Replace the reference by schedule(). While here, rearrange the sentence a bit so that "cyclic_run()" becomes the object and "the main function responsible for calling all registered cyclic functions" a parenthetical rather than the other way around, which at least to me makes it more readable. Signed-off-by: Rasmus Villemoes <ravi@prevas.dk> Reviewed-by: Simon Glass <sjg@chromium.org> Reviewed-by: Stefan Roese <sr@denx.de>
56 lines
1.9 KiB
ReStructuredText
56 lines
1.9 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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Cyclic functions
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================
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The cyclic function execution infrastruture provides a way to periodically
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execute code, e.g. every 100ms. Examples for such functions might be LED
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blinking etc. The functions that are hooked into this cyclic list should
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be small timewise as otherwise the execution of the other code that relies
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on a high frequent polling (e.g. UART rx char ready check) might be
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delayed too much. To detect cyclic functions with an excessive execution
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time, the Kconfig option `CONFIG_CYCLIC_MAX_CPU_TIME_US` was introduced.
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It defines the maximum allowable execution time for such a cyclic function. The
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first time the execution of a cyclic function exceeds this interval, a warning
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will be displayed indicating the problem to the user.
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Registering a cyclic function
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-----------------------------
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To register a cyclic function, use something like this::
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struct donkey {
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struct cyclic_info cyclic;
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void (*say)(const char *s);
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};
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static void cyclic_demo(struct cyclic_info *c)
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{
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struct donkey *donkey = container_of(c, struct donkey, cyclic);
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donkey->say("Are we there yet?");
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}
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int donkey_init(void)
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{
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struct donkey *donkey;
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/* Initialize donkey ... */
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/* Register demo cyclic function */
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cyclic_register(&donkey->cyclic, cyclic_demo, 10 * 1000, "cyclic_demo");
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return 0;
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}
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This will register the function `cyclic_demo()` to be periodically
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executed all 10ms.
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How is this cyclic functionality integrated / executed?
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--------------------------------------------------------
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The cyclic infrastructure integrates cyclic_run(), the main function
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responsible for calling all registered cyclic functions, into the
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common schedule() function. This guarantees that cyclic_run() is
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executed very often, which is necessary for the cyclic functions to
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get scheduled and executed at their configured periods.
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