linux/include/linux/hrtimer.h

// SPDX-License-Identifier: GPL-2.0
/*
 *  hrtimers - High-resolution kernel timers
 *
 *   Copyright(C) 2005, Thomas Gleixner <[email protected]>
 *   Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
 *
 *  data type definitions, declarations, prototypes
 *
 *  Started by: Thomas Gleixner and Ingo Molnar
 */
#ifndef _LINUX_HRTIMER_H
#define _LINUX_HRTIMER_H

#include <linux/hrtimer_defs.h>
#include <linux/hrtimer_types.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/percpu-defs.h>
#include <linux/rbtree.h>
#include <linux/timer.h>

/*
 * Mode arguments of xxx_hrtimer functions:
 *
 * HRTIMER_MODE_ABS		- Time value is absolute
 * HRTIMER_MODE_REL		- Time value is relative to now
 * HRTIMER_MODE_PINNED		- Timer is bound to CPU (is only considered
 *				  when starting the timer)
 * HRTIMER_MODE_SOFT		- Timer callback function will be executed in
 *				  soft irq context
 * HRTIMER_MODE_HARD		- Timer callback function will be executed in
 *				  hard irq context even on PREEMPT_RT.
 */
enum hrtimer_mode { … };

/*
 * Values to track state of the timer
 *
 * Possible states:
 *
 * 0x00		inactive
 * 0x01		enqueued into rbtree
 *
 * The callback state is not part of the timer->state because clearing it would
 * mean touching the timer after the callback, this makes it impossible to free
 * the timer from the callback function.
 *
 * Therefore we track the callback state in:
 *
 *	timer->base->cpu_base->running == timer
 *
 * On SMP it is possible to have a "callback function running and enqueued"
 * status. It happens for example when a posix timer expired and the callback
 * queued a signal. Between dropping the lock which protects the posix timer
 * and reacquiring the base lock of the hrtimer, another CPU can deliver the
 * signal and rearm the timer.
 *
 * All state transitions are protected by cpu_base->lock.
 */
#define HRTIMER_STATE_INACTIVE …
#define HRTIMER_STATE_ENQUEUED …

/**
 * struct hrtimer_sleeper - simple sleeper structure
 * @timer:	embedded timer structure
 * @task:	task to wake up
 *
 * task is set to NULL, when the timer expires.
 */
struct hrtimer_sleeper { … };

static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
{ … }

static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
{ … }

static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, u64 delta)
{ … }

static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
{ … }

static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
{ … }

static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
{ … }

static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
{ … }

static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
{ … }

static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
{ … }
static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
{ … }

static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
{ … }

static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
{ … }

static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
{ … }

static inline int hrtimer_is_hres_active(struct hrtimer *timer)
{ … }

#ifdef CONFIG_HIGH_RES_TIMERS
struct clock_event_device;

extern void hrtimer_interrupt(struct clock_event_device *dev);

extern unsigned int hrtimer_resolution;

#else

#define hrtimer_resolution …

#endif

static inline ktime_t
__hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
{ … }

static inline ktime_t
hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
{ … }

#ifdef CONFIG_TIMERFD
extern void timerfd_clock_was_set(void);
extern void timerfd_resume(void);
#else
static inline void timerfd_clock_was_set(void) { }
static inline void timerfd_resume(void) { }
#endif

DECLARE_PER_CPU(struct tick_device, tick_cpu_device);

#ifdef CONFIG_PREEMPT_RT
void hrtimer_cancel_wait_running(const struct hrtimer *timer);
#else
static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
{ … }
#endif

/* Exported timer functions: */

/* Initialize timers: */
extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
			 enum hrtimer_mode mode);
extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
				 enum hrtimer_mode mode);

#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
				  enum hrtimer_mode mode);
extern void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
					  clockid_t clock_id,
					  enum hrtimer_mode mode);

extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
#else
static inline void hrtimer_init_on_stack(struct hrtimer *timer,
					 clockid_t which_clock,
					 enum hrtimer_mode mode)
{
	hrtimer_init(timer, which_clock, mode);
}

static inline void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
						 clockid_t clock_id,
						 enum hrtimer_mode mode)
{
	hrtimer_init_sleeper(sl, clock_id, mode);
}

static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
#endif

/* Basic timer operations: */
extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
				   u64 range_ns, const enum hrtimer_mode mode);

/**
 * hrtimer_start - (re)start an hrtimer
 * @timer:	the timer to be added
 * @tim:	expiry time
 * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
 *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
 *		softirq based mode is considered for debug purpose only!
 */
static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
				 const enum hrtimer_mode mode)
{ … }

extern int hrtimer_cancel(struct hrtimer *timer);
extern int hrtimer_try_to_cancel(struct hrtimer *timer);

static inline void hrtimer_start_expires(struct hrtimer *timer,
					 enum hrtimer_mode mode)
{ … }

void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
				   enum hrtimer_mode mode);

static inline void hrtimer_restart(struct hrtimer *timer)
{ … }

/* Query timers: */
extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);

/**
 * hrtimer_get_remaining - get remaining time for the timer
 * @timer:	the timer to read
 */
static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
{ … }

extern u64 hrtimer_get_next_event(void);
extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);

extern bool hrtimer_active(const struct hrtimer *timer);

/**
 * hrtimer_is_queued - check, whether the timer is on one of the queues
 * @timer:	Timer to check
 *
 * Returns: True if the timer is queued, false otherwise
 *
 * The function can be used lockless, but it gives only a current snapshot.
 */
static inline bool hrtimer_is_queued(struct hrtimer *timer)
{ … }

/*
 * Helper function to check, whether the timer is running the callback
 * function
 */
static inline int hrtimer_callback_running(struct hrtimer *timer)
{ … }

/* Forward a hrtimer so it expires after now: */
extern u64
hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);

/**
 * hrtimer_forward_now() - forward the timer expiry so it expires after now
 * @timer:	hrtimer to forward
 * @interval:	the interval to forward
 *
 * It is a variant of hrtimer_forward(). The timer will expire after the current
 * time of the hrtimer clock base. See hrtimer_forward() for details.
 */
static inline u64 hrtimer_forward_now(struct hrtimer *timer,
				      ktime_t interval)
{ … }

/* Precise sleep: */

extern int nanosleep_copyout(struct restart_block *, struct timespec64 *);
extern long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
			      const clockid_t clockid);

extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
				    const enum hrtimer_mode mode);
extern int schedule_hrtimeout_range_clock(ktime_t *expires,
					  u64 delta,
					  const enum hrtimer_mode mode,
					  clockid_t clock_id);
extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);

/* Soft interrupt function to run the hrtimer queues: */
extern void hrtimer_run_queues(void);

/* Bootup initialization: */
extern void __init hrtimers_init(void);

/* Show pending timers: */
extern void sysrq_timer_list_show(void);

int hrtimers_prepare_cpu(unsigned int cpu);
#ifdef CONFIG_HOTPLUG_CPU
int hrtimers_cpu_dying(unsigned int cpu);
#else
#define hrtimers_cpu_dying …
#endif

#endif