![Thomas Gleixner](/assets/img/avatar_default.png)
Architectures register their clock event devices, in the clock events core. Users of the clockevents core can get clock event devices for their use. The clockevents core code provides notification mechanisms for various clock related management events. This allows to control the clock event devices without the architectures having to worry about the details of function assignment. This is also a preliminary for high resolution timers and dynamic ticks to allow the core code to control the clock functionality without intrusive changes to the architecture code. [Fixes-by: Ingo Molnar <mingo@elte.hu>] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: john stultz <johnstul@us.ibm.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
205 lines
6.1 KiB
C
205 lines
6.1 KiB
C
/*
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* include/linux/hrtimer.h
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*
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* hrtimers - High-resolution kernel timers
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*
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* Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
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*
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* data type definitions, declarations, prototypes
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*
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* Started by: Thomas Gleixner and Ingo Molnar
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*
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* For licencing details see kernel-base/COPYING
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*/
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#ifndef _LINUX_HRTIMER_H
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#define _LINUX_HRTIMER_H
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#include <linux/rbtree.h>
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#include <linux/ktime.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/wait.h>
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struct hrtimer_clock_base;
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struct hrtimer_cpu_base;
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/*
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* Mode arguments of xxx_hrtimer functions:
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*/
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enum hrtimer_mode {
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HRTIMER_MODE_ABS, /* Time value is absolute */
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HRTIMER_MODE_REL, /* Time value is relative to now */
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};
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/*
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* Return values for the callback function
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*/
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enum hrtimer_restart {
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HRTIMER_NORESTART, /* Timer is not restarted */
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HRTIMER_RESTART, /* Timer must be restarted */
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};
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/*
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* Bit values to track state of the timer
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*
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* Possible states:
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*
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* 0x00 inactive
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* 0x01 enqueued into rbtree
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* 0x02 callback function running
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* 0x03 callback function running and enqueued
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* (was requeued on another CPU)
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*
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* The "callback function running and enqueued" status is only possible on
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* SMP. It happens for example when a posix timer expired and the callback
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* queued a signal. Between dropping the lock which protects the posix timer
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* and reacquiring the base lock of the hrtimer, another CPU can deliver the
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* signal and rearm the timer. We have to preserve the callback running state,
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* as otherwise the timer could be removed before the softirq code finishes the
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* the handling of the timer.
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*
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* The HRTIMER_STATE_ENQUEUE bit is always or'ed to the current state to
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* preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
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*
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* All state transitions are protected by cpu_base->lock.
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*/
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#define HRTIMER_STATE_INACTIVE 0x00
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#define HRTIMER_STATE_ENQUEUED 0x01
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#define HRTIMER_STATE_CALLBACK 0x02
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/**
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* struct hrtimer - the basic hrtimer structure
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* @node: red black tree node for time ordered insertion
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* @expires: the absolute expiry time in the hrtimers internal
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* representation. The time is related to the clock on
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* which the timer is based.
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* @function: timer expiry callback function
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* @base: pointer to the timer base (per cpu and per clock)
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* @state: state information (See bit values above)
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*
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* The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
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*/
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struct hrtimer {
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struct rb_node node;
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ktime_t expires;
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enum hrtimer_restart (*function)(struct hrtimer *);
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struct hrtimer_clock_base *base;
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unsigned long state;
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};
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/**
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* struct hrtimer_sleeper - simple sleeper structure
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* @timer: embedded timer structure
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* @task: task to wake up
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*
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* task is set to NULL, when the timer expires.
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*/
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struct hrtimer_sleeper {
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struct hrtimer timer;
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struct task_struct *task;
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};
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/**
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* struct hrtimer_base - the timer base for a specific clock
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* @index: clock type index for per_cpu support when moving a
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* timer to a base on another cpu.
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* @active: red black tree root node for the active timers
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* @first: pointer to the timer node which expires first
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* @resolution: the resolution of the clock, in nanoseconds
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* @get_time: function to retrieve the current time of the clock
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* @get_softirq_time: function to retrieve the current time from the softirq
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* @softirq_time: the time when running the hrtimer queue in the softirq
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*/
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struct hrtimer_clock_base {
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struct hrtimer_cpu_base *cpu_base;
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clockid_t index;
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struct rb_root active;
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struct rb_node *first;
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ktime_t resolution;
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ktime_t (*get_time)(void);
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ktime_t (*get_softirq_time)(void);
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ktime_t softirq_time;
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};
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#define HRTIMER_MAX_CLOCK_BASES 2
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/*
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* struct hrtimer_cpu_base - the per cpu clock bases
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* @lock: lock protecting the base and associated clock bases
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* and timers
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* @lock_key: the lock_class_key for use with lockdep
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* @clock_base: array of clock bases for this cpu
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* @curr_timer: the timer which is executing a callback right now
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*/
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struct hrtimer_cpu_base {
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spinlock_t lock;
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struct lock_class_key lock_key;
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struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
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};
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/*
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* clock_was_set() is a NOP for non- high-resolution systems. The
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* time-sorted order guarantees that a timer does not expire early and
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* is expired in the next softirq when the clock was advanced.
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*/
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#define clock_was_set() do { } while (0)
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extern ktime_t ktime_get(void);
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extern ktime_t ktime_get_real(void);
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/* Exported timer functions: */
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/* Initialize timers: */
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extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
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enum hrtimer_mode mode);
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/* Basic timer operations: */
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extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
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const enum hrtimer_mode mode);
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extern int hrtimer_cancel(struct hrtimer *timer);
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extern int hrtimer_try_to_cancel(struct hrtimer *timer);
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static inline int hrtimer_restart(struct hrtimer *timer)
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{
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return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
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}
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/* Query timers: */
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extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
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extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
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#ifdef CONFIG_NO_IDLE_HZ
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extern ktime_t hrtimer_get_next_event(void);
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#endif
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/*
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* A timer is active, when it is enqueued into the rbtree or the callback
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* function is running.
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*/
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static inline int hrtimer_active(const struct hrtimer *timer)
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{
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return timer->state != HRTIMER_STATE_INACTIVE;
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}
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/* Forward a hrtimer so it expires after now: */
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extern unsigned long
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hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
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/* Precise sleep: */
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extern long hrtimer_nanosleep(struct timespec *rqtp,
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struct timespec __user *rmtp,
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const enum hrtimer_mode mode,
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const clockid_t clockid);
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extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
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extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
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struct task_struct *tsk);
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/* Soft interrupt function to run the hrtimer queues: */
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extern void hrtimer_run_queues(void);
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/* Bootup initialization: */
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extern void __init hrtimers_init(void);
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#endif
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