include/linux/timer.h

   1 #ifndef _LINUX_TIMER_H
   2 #define _LINUX_TIMER_H
   3
   4 #include <linux/config.h>
   5 #include <linux/list.h>
   6
   7 /*
   8  * This is completely separate from the above, and is the
   9  * "new and improved" way of handling timers more dynamically.
  10  * Hopefully efficient and general enough for most things.
  11  *
  12  * The "hardcoded" timers above are still useful for well-
  13  * defined problems, but the timer-list is probably better
  14  * when you need multiple outstanding timers or similar.
  15  *
  16  * The "data" field is in case you want to use the same
  17  * timeout function for several timeouts. You can use this
  18  * to distinguish between the different invocations.
  19  */
  20 struct timer_list {
  21         struct list_head list;
  22         unsigned long expires;
  23         unsigned long data;
  24         void (*function)(unsigned long);
  25 };
  26
  27 extern void add_timer(struct timer_list * timer);
  28 extern int del_timer(struct timer_list * timer);
  29
  30 #ifdef CONFIG_SMP
  31 extern int del_timer_sync(struct timer_list * timer);
  32 extern void sync_timers(void);
  33 #else
  34 #define del_timer_sync(t)       del_timer(t)
  35 #define sync_timers()           do { } while (0)
  36 #endif
  37
  38 /*
  39  * mod_timer is a more efficient way to update the expire field of an
  40  * active timer (if the timer is inactive it will be activated)
  41  * mod_timer(a,b) is equivalent to del_timer(a); a->expires = b; add_timer(a).
  42  * If the timer is known to be not pending (ie, in the handler), mod_timer
  43  * is less efficient than a->expires = b; add_timer(a).
  44  */
  45 int mod_timer(struct timer_list *timer, unsigned long expires);
  46
  47 extern void it_real_fn(unsigned long);
  48
  49 static inline void init_timer(struct timer_list * timer)
  50 {
  51         timer->list.next = timer->list.prev = NULL;
  52 }
  53
  54 static inline int timer_pending (const struct timer_list * timer)
  55 {
  56         return timer->list.next != NULL;
  57 }
  58
  59 /*
  60  *      These inlines deal with timer wrapping correctly. You are
  61  *      strongly encouraged to use them
  62  *      1. Because people otherwise forget
  63  *      2. Because if the timer wrap changes in future you wont have to
  64  *         alter your driver code.
  65  *
  66  * Do this with "<0" and ">=0" to only test the sign of the result. A
  67  * good compiler would generate better code (and a really good compiler
  68  * wouldn't care). Gcc is currently neither.
  69  */
  70 #define time_after(a,b)         ((long)(b) - (long)(a) < 0)
  71 #define time_before(a,b)        time_after(b,a)
  72
  73 #define time_after_eq(a,b)      ((long)(a) - (long)(b) >= 0)
  74 #define time_before_eq(a,b)     time_after_eq(b,a)
  75
  76 #endif