From 3c46c02c5423fe8799f5ebcd2a07cf995b620a48 Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Thu, 12 Dec 2013 17:17:06 +0100 Subject: poller: Allow to call functions asynchronously Sometimes execution of a function has to be delayed, for example when a backlight can only be turned on when the picture has stabilized. To help in such situations add a convenience function around the poller stuff to call a function after a delay. Signed-off-by: Sascha Hauer --- common/poller.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) (limited to 'common') diff --git a/common/poller.c b/common/poller.c index 0583a532cf..496636d1d7 100644 --- a/common/poller.c +++ b/common/poller.c @@ -11,24 +11,82 @@ #include #include #include +#include static LIST_HEAD(poller_list); static int poller_active; int poller_register(struct poller_struct *poller) { + if (poller->registered) + return -EBUSY; + list_add_tail(&poller->list, &poller_list); + poller->registered = 1; return 0; } int poller_unregister(struct poller_struct *poller) { + if (!poller->registered) + return -ENODEV; + list_del(&poller->list); + poller->registered = 0; return 0; } +static void poller_async_callback(struct poller_struct *poller) +{ + struct poller_async *pa = container_of(poller, struct poller_async, poller); + + if (get_time_ns() < pa->end) + return; + + pa->fn(pa->ctx); + pa->fn = NULL; + poller_unregister(&pa->poller); +} + +/* + * Cancel an outstanding asynchronous function call + * + * @pa the poller that has been scheduled + * + * Cancel an outstanding function call. Returns 0 if the call + * has actually been cancelled or -ENODEV when the call wasn't + * scheduled. + * + */ +int poller_async_cancel(struct poller_async *pa) +{ + return poller_unregister(&pa->poller); +} + +/* + * Call a function asynchronously + * + * @pa the poller to be used + * @delay The delay in nanoseconds + * @fn The function to call + * @ctx context pointer passed to the function + * + * This calls the passed function after a delay of delay_ns. Returns + * a pointer which can be used as a cookie to cancel a scheduled call. + */ +int poller_call_async(struct poller_async *pa, uint64_t delay_ns, + void (*fn)(void *), void *ctx) +{ + pa->ctx = ctx; + pa->poller.func = poller_async_callback; + pa->end = get_time_ns() + delay_ns; + pa->fn = fn; + + return poller_register(&pa->poller); +} + void poller_call(void) { struct poller_struct *poller, *tmp; -- cgit v1.2.3