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// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
/* Copyright 2014-2015 IBM Corp. */
#ifndef __TIMER_H
#define __TIMER_H
#include <stdint.h>
#include <ccan/list/list.h>
struct timer;
typedef void (*timer_func_t)(struct timer *t, void *data, uint64_t now);
/* Structure exposed in order to be able to allocate it
* statically but otherwise, use accessors, don't access
* the fields directly
*
* WARNING: Do not free a timer object unless you have cancelled
* it first or you know it won't reschedule itself and have done
* a sync_timer() on it. The timer core *will* access the object
* again after you return from the expiry callback so it must not
* be freed from the callback itself.
*/
struct timer {
struct list_node link;
uint64_t target;
timer_func_t expiry;
void * user_data;
void * running;
uint64_t gen;
};
extern void init_timer(struct timer *t, timer_func_t expiry, void *data);
/* (re)schedule a timer. If already scheduled, it's expiry will be updated
*
* This doesn't synchronize so if the timer also reschedules itself there
* is no telling which one "wins". The advantage is that this can be called
* with any lock held or from the timer expiry itself.
*
* We support a magic expiry of TIMER_POLL which causes a given timer to
* be called whenever OPAL main polling loop is run, which is often during
* boot and occasionally while Linux is up. This can be used with both
* schedule_timer() and schedule_timer_at()
*
* This is useful for a number of interrupt driven drivers to have a way
* to crank their state machine at times when the interrupt isn't available
* such as during early boot.
*
* Note: For convenience, schedule_timer() returns the current TB value
*/
#define TIMER_POLL ((uint64_t)-1)
extern uint64_t schedule_timer(struct timer *t, uint64_t how_long);
extern void schedule_timer_at(struct timer *t, uint64_t when);
/* Synchronization point with the timer. If the callback has started before
* that function is called, it will be complete when this function returns.
*
* It might start *again* but at least anything before this will be visible
* to any subsequent occurrence.
*
* The usual issue of such sync functions exist: don't call it while holding
* a lock that the timer callback might take or from the timer expiry itself.
*/
extern void sync_timer(struct timer *t);
/* cancel_timer() will ensure the timer isn't concurrently running so
* the cancellation is guaranteed even if the timer reschedules itself.
*
* This uses sync_timer() internally so don't call this while holding a
* lock the timer might use.
*/
extern void cancel_timer(struct timer *t);
/* cancel_timer_async() allows to remove the timer from the schedule
* list without trying to synchronize. This is useful if the cancellation
* must happen while holding locks that would make the synchronization
* impossible. The user is responsible of ensuring it deals with potentially
* spurrious occurrences
*/
extern void cancel_timer_async(struct timer *t);
/* Run the timers */
extern void check_timers(bool from_interrupt);
/* Core init */
void late_init_timers(void);
#endif /* __TIMER_H */
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