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/*
* Copyright (c) 2017 Richard Braun.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*
* Low resolution timer system.
*/
#ifndef KERN_TIMER_H
#define KERN_TIMER_H
#include <stdint.h>
#include <kern/init.h>
/*
* Scheduling flags.
*/
#define TIMER_DETACHED 0x1 /* Timer completion isn't synchronized */
#define TIMER_INTR 0x2 /* Handler is run from interrupt context */
#define TIMER_HIGH_PRIO 0x4 /* Handler is run in high priority thread */
struct timer;
/*
* Type for timer callbacks.
*
* These functions implement handler operations.
*
* The schedule operation on a timer synchronizes with the handler
* operation on the same timer, and a handler operation on a timer
* synchronizes with cancel operations on the same timer.
*/
typedef void (*timer_handler_fn_t)(struct timer *);
#include <kern/timer_i.h>
/*
* Return the absolute expiration time of the timer, in ticks.
*
* This function isn't thread-safe.
*/
static inline uint64_t
timer_get_time(const struct timer *timer)
{
return timer->ticks;
}
/*
* Initialize a timer.
*
* Timers that are reponsible for releasing their own resources must
* be detached.
*/
void timer_init(struct timer *timer, timer_handler_fn_t fn, int flags);
/*
* Schedule a timer.
*
* The time of expiration is an absolute time in ticks.
*
* Timers may safely be rescheduled after completion. Periodic timers are
* implemented by rescheduling from the timer handler.
*
* If the timer has been canceled, this function does nothing. A
* canceled timer must be reinitialized before being scheduled again.
*
* This operation synchronizes with the handler operation on the same timer.
*
* This function may safely be called in interrupt context.
*/
void timer_schedule(struct timer *timer, uint64_t ticks);
/*
* Cancel a timer.
*
* The given timer must not be detached.
*
* If the timer is still scheduled, it is canceled, i.e. its handler
* operation won't start. Otherwise, if the timer has already expired,
* this function waits until the handler operation completes, or returns
* immediately if the handler operation has already completed.
*
* This function may safely be called from the timer handler, but not on
* the same timer. Canceling a timer from the timer handler is achieved by
* simply not rescheduling it.
*
* A prior handler operation on the same timer synchronizes with this
* operation.
*/
void timer_cancel(struct timer *timer);
/*
* Report a periodic event on the current processor.
*
* Interrupts and preemption must be disabled when calling this function.
*/
void timer_report_periodic_event(void);
/*
* This init operation provides :
* - timer initialization and scheduling
*/
INIT_OP_DECLARE(timer_bootstrap);
#endif /* KERN_TIMER_H */
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