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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 <s.hauer@pengutronix.de>
This commit is contained in:
Sascha Hauer 2013-12-12 17:17:06 +01:00
parent 8fc3a93825
commit 3c46c02c54
2 changed files with 71 additions and 1 deletions
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58
common/poller.c
View File

@ -11,24 +11,82 @@
#include <module.h>
#include <param.h>
#include <poller.h>
#include <clock.h>
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;

14
include/poller.h
View File

@ -12,13 +12,25 @@
struct poller_struct {
void (*func)(struct poller_struct *poller);
int registered;
struct list_head list;
};
int poller_register(struct poller_struct *poller);
int poller_unregister(struct poller_struct *poller);
struct poller_async;
struct poller_async {
struct poller_struct poller;
void (*fn)(void *);
void *ctx;
uint64_t end;
};
int poller_call_async(struct poller_async *pa, uint64_t delay_ns,
void (*fn)(void *), void *ctx);
int poller_async_cancel(struct poller_async *pa);
#ifdef CONFIG_POLLER
void poller_call(void);