From 008c4b3c3115f7f95467773f12bad0db7649e786 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Tue, 21 May 2024 10:46:52 +0200 Subject: cyclic: make clients embed a struct cyclic_info in their own data structure There are of course not a whole lot of examples in-tree yet, but before they appear, let's make this API change: Instead of separately allocating a 'struct cyclic_info', make the users embed such an instance in their own structure, and make the convention that the callback simply receives the 'struct cyclic_info *', from which the clients can get their own data using the container_of() macro. This has a number of advantages. First, it means cyclic_register() simply cannot fail, simplifying the code. The necessary storage will simply be allocated automatically when the client's own structure is allocated (often via uclass_priv_auto or similar). Second, code for which CONFIG_CYCLIC is just an option can more easily be written without #ifdefs, if we just provide an empty struct cyclic_info {}. For example, the nested CONFIG_IS_ENABLED()s in https://lore.kernel.org/u-boot/20240316201416.211480-1-marek.vasut+renesas@mailbox.org/ are mostly due to the existence of the 'struct cyclic_info *' member being guarded by #ifdef CONFIG_CYCLIC. And we do probably want to avoid the extra memory overhead of that member when !CONFIG_CYCLIC. But that is automatic if, instead of a 'struct cyclic_info *', one simply embeds a 'struct cyclic_info', which will have size 0 when !CONFIG_CYCLIC. Also, the no-op cyclic_register() function can just unconditionally be called, and the compiler will see that (1) the callback is referenced, so not emit a warning for a maybe-unused function and (2) see that it can actually never be reached, so not emit any code for it. Reviewed-by: Stefan Roese Signed-off-by: Rasmus Villemoes --- doc/develop/cyclic.rst | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) (limited to 'doc/develop') diff --git a/doc/develop/cyclic.rst b/doc/develop/cyclic.rst index 67831496a70..893c269099a 100644 --- a/doc/develop/cyclic.rst +++ b/doc/develop/cyclic.rst @@ -19,20 +19,26 @@ Registering a cyclic function To register a cyclic function, use something like this:: - static void cyclic_demo(void *ctx) + struct donkey { + struct cyclic_info cyclic; + void (*say)(const char *s); + }; + + static void cyclic_demo(struct cyclic_info *c) { - /* Just a small dummy delay here */ - udelay(10); + struct donkey *donkey = container_of(c, struct donkey, cyclic); + + donkey->say("Are we there yet?"); } - - int board_init(void) + + int donkey_init(void) { - struct cyclic_info *cyclic; - + struct donkey *donkey; + + /* Initialize donkey ... */ + /* Register demo cyclic function */ - cyclic = cyclic_register(cyclic_demo, 10 * 1000, "cyclic_demo", NULL); - if (!cyclic) - printf("Registering of cyclic_demo failed\n"); + cyclic_register(&donkey->cyclic, cyclic_demo, 10 * 1000, "cyclic_demo"); return 0; } -- cgit v1.2.3