/* * include/linux/hrtimer.h * * hrtimers - High-resolution kernel timers * * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de> * Copyright(C) 2005, Red Hat, Inc., Ingo Molnar * * data type definitions, declarations, prototypes * * Started by: Thomas Gleixner and Ingo Molnar * * For licencing details see kernel-base/COPYING */ #ifndef _LINUX_HRTIMER_H #define _LINUX_HRTIMER_H #include <linux/rbtree.h> #include <linux/ktime.h> #include <linux/init.h> #include <linux/list.h> #include <linux/wait.h> struct hrtimer_clock_base; struct hrtimer_cpu_base; /* * Mode arguments of xxx_hrtimer functions: */ enum hrtimer_mode { HRTIMER_MODE_ABS, /* Time value is absolute */ HRTIMER_MODE_REL, /* Time value is relative to now */ }; /* * Return values for the callback function */ enum hrtimer_restart { HRTIMER_NORESTART, /* Timer is not restarted */ HRTIMER_RESTART, /* Timer must be restarted */ }; /* * hrtimer callback modes: * * HRTIMER_CB_SOFTIRQ: Callback must run in softirq context * HRTIMER_CB_IRQSAFE: Callback may run in hardirq context * HRTIMER_CB_IRQSAFE_NO_RESTART: Callback may run in hardirq context and * does not restart the timer * HRTIMER_CB_IRQSAFE_NO_SOFTIRQ: Callback must run in hardirq context * Special mode for tick emultation */ enum hrtimer_cb_mode { HRTIMER_CB_SOFTIRQ, HRTIMER_CB_IRQSAFE, HRTIMER_CB_IRQSAFE_NO_RESTART, HRTIMER_CB_IRQSAFE_NO_SOFTIRQ, }; /* * Values to track state of the timer * * Possible states: * * 0x00 inactive * 0x01 enqueued into rbtree * 0x02 callback function running * 0x04 callback pending (high resolution mode) * * Special case: * 0x03 callback function running and enqueued * (was requeued on another CPU) * The "callback function running and enqueued" status is only possible on * SMP. 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. We have to preserve the callback running state, * as otherwise the timer could be removed before the softirq code finishes the * the handling of the timer. * * The HRTIMER_STATE_ENQUEUE bit is always or'ed to the current state to * preserve the HRTIMER_STATE_CALLBACK bit in the above scenario. * * All state transitions are protected by cpu_base->lock. */ #define HRTIMER_STATE_INACTIVE 0x00 #define HRTIMER_STATE_ENQUEUED 0x01 #define HRTIMER_STATE_CALLBACK 0x02 #define HRTIMER_STATE_PENDING 0x04 /** * struct hrtimer - the basic hrtimer structure * @node: red black tree node for time ordered insertion * @expires: the absolute expiry time in the hrtimers internal * representation. The time is related to the clock on * which the timer is based. * @function: timer expiry callback function * @base: pointer to the timer base (per cpu and per clock) * @state: state information (See bit values above) * @cb_mode: high resolution timer feature to select the callback execution * mode * @cb_entry: list head to enqueue an expired timer into the callback list * @start_site: timer statistics field to store the site where the timer * was started * @start_comm: timer statistics field to store the name of the process which * started the timer * @start_pid: timer statistics field to store the pid of the task which * started the timer * * The hrtimer structure must be initialized by hrtimer_init() */ struct hrtimer { struct rb_node node; ktime_t expires; enum hrtimer_restart (*function)(struct hrtimer *); struct hrtimer_clock_base *base; unsigned long state; enum hrtimer_cb_mode cb_mode; struct list_head cb_entry; #ifdef CONFIG_TIMER_STATS void *start_site; char start_comm[16]; int start_pid; #endif }; /** * 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 { struct hrtimer timer; struct task_struct *task; }; /** * struct hrtimer_clock_base - the timer base for a specific clock * @cpu_base: per cpu clock base * @index: clock type index for per_cpu support when moving a * timer to a base on another cpu. * @active: red black tree root node for the active timers * @first: pointer to the timer node which expires first * @resolution: the resolution of the clock, in nanoseconds * @get_time: function to retrieve the current time of the clock * @get_softirq_time: function to retrieve the current time from the softirq * @softirq_time: the time when running the hrtimer queue in the softirq * @cb_pending: list of timers where the callback is pending * @offset: offset of this clock to the monotonic base * @reprogram: function to reprogram the timer event */ struct hrtimer_clock_base { struct hrtimer_cpu_base *cpu_base; clockid_t index; struct rb_root active; struct rb_node *first; ktime_t resolution; ktime_t (*get_time)(void); ktime_t (*get_softirq_time)(void); ktime_t softirq_time; #ifdef CONFIG_HIGH_RES_TIMERS ktime_t offset; int (*reprogram)(struct hrtimer *t, struct hrtimer_clock_base *b, ktime_t n); #endif }; #define HRTIMER_MAX_CLOCK_BASES 2 /* * struct hrtimer_cpu_base - the per cpu clock bases * @lock: lock protecting the base and associated clock bases * and timers * @lock_key: the lock_class_key for use with lockdep * @clock_base: array of clock bases for this cpu * @curr_timer: the timer which is executing a callback right now * @expires_next: absolute time of the next event which was scheduled * via clock_set_next_event() * @hres_active: State of high resolution mode * @check_clocks: Indictator, when set evaluate time source and clock * event devices whether high resolution mode can be * activated. * @cb_pending: Expired timers are moved from the rbtree to this * list in the timer interrupt. The list is processed * in the softirq. * @nr_events: Total number of timer interrupt events */ struct hrtimer_cpu_base { spinlock_t lock; struct lock_class_key lock_key; struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES]; struct list_head cb_pending; #ifdef CONFIG_HIGH_RES_TIMERS ktime_t expires_next; int hres_active; unsigned long nr_events; #endif }; #ifdef CONFIG_HIGH_RES_TIMERS struct clock_event_device; extern void clock_was_set(void); extern void hres_timers_resume(void); extern void hrtimer_interrupt(struct clock_event_device *dev); /* * In high resolution mode the time reference must be read accurate */ static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer) { return timer->base->get_time(); } static inline int hrtimer_is_hres_active(struct hrtimer *timer) { return timer->base->cpu_base->hres_active; } /* * The resolution of the clocks. The resolution value is returned in * the clock_getres() system call to give application programmers an * idea of the (in)accuracy of timers. Timer values are rounded up to * this resolution values. */ # define KTIME_HIGH_RES (ktime_t) { .tv64 = 1 } # define KTIME_MONOTONIC_RES KTIME_HIGH_RES #else # define KTIME_MONOTONIC_RES KTIME_LOW_RES /* * clock_was_set() is a NOP for non- high-resolution systems. The * time-sorted order guarantees that a timer does not expire early and * is expired in the next softirq when the clock was advanced. */ static inline void clock_was_set(void) { } static inline void hres_timers_resume(void) { } /* * In non high resolution mode the time reference is taken from * the base softirq time variable. */ static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer) { return timer->base->softirq_time; } static inline int hrtimer_is_hres_active(struct hrtimer *timer) { return 0; } #endif extern ktime_t ktime_get(void); extern ktime_t ktime_get_real(void); /* Exported timer functions: */ /* Initialize timers: */ extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock, enum hrtimer_mode mode); /* Basic timer operations: */ extern int 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 int hrtimer_restart(struct hrtimer *timer) { return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS); } /* Query timers: */ extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer); extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp); extern ktime_t hrtimer_get_next_event(void); /* * A timer is active, when it is enqueued into the rbtree or the callback * function is running. */ static inline int hrtimer_active(const struct hrtimer *timer) { return timer->state != HRTIMER_STATE_INACTIVE; } /* * Helper function to check, whether the timer is on one of the queues */ static inline int hrtimer_is_queued(struct hrtimer *timer) { return timer->state & (HRTIMER_STATE_ENQUEUED | HRTIMER_STATE_PENDING); } /* Forward a hrtimer so it expires after now: */ extern unsigned long hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval); /* Precise sleep: */ extern long hrtimer_nanosleep(struct timespec *rqtp, struct timespec *rmtp, const enum hrtimer_mode mode, const clockid_t clockid); extern long hrtimer_nanosleep_restart(struct restart_block *restart_block); extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *tsk); /* Soft interrupt function to run the hrtimer queues: */ extern void hrtimer_run_queues(void); extern void hrtimer_run_pending(void); /* Bootup initialization: */ extern void __init hrtimers_init(void); #if BITS_PER_LONG < 64 extern unsigned long ktime_divns(const ktime_t kt, s64 div); #else /* BITS_PER_LONG < 64 */ # define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div)) #endif /* Show pending timers: */ extern void sysrq_timer_list_show(void); /* * Timer-statistics info: */ #ifdef CONFIG_TIMER_STATS extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf, void *timerf, char *comm, unsigned int timer_flag); static inline void timer_stats_account_hrtimer(struct hrtimer *timer) { timer_stats_update_stats(timer, timer->start_pid, timer->start_site, timer->function, timer->start_comm, 0); } extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer, void *addr); static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer) { __timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0)); } static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer) { timer->start_site = NULL; } #else static inline void timer_stats_account_hrtimer(struct hrtimer *timer) { } static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer) { } static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer) { } #endif #endif