--- /dev/null
+/*
+ * 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>
+
+/*
+ * Mode arguments of xxx_hrtimer functions:
+ */
+enum hrtimer_mode {
+ HRTIMER_ABS, /* Time value is absolute */
+ HRTIMER_REL, /* Time value is relative to now */
+};
+
+enum hrtimer_restart {
+ HRTIMER_NORESTART,
+ HRTIMER_RESTART,
+};
+
+/*
+ * Timer states:
+ */
+enum hrtimer_state {
+ HRTIMER_INACTIVE, /* Timer is inactive */
+ HRTIMER_EXPIRED, /* Timer is expired */
+ HRTIMER_PENDING, /* Timer is pending */
+};
+
+struct hrtimer_base;
+
+/**
+ * struct hrtimer - the basic hrtimer structure
+ *
+ * @node: red black tree node for time ordered insertion
+ * @list: list head for easier access to the time ordered list,
+ * without walking the red black tree.
+ * @expires: the absolute expiry time in the hrtimers internal
+ * representation. The time is related to the clock on
+ * which the timer is based.
+ * @state: state of the timer
+ * @function: timer expiry callback function
+ * @data: argument for the callback function
+ * @base: pointer to the timer base (per cpu and per clock)
+ *
+ * The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
+ */
+struct hrtimer {
+ struct rb_node node;
+ struct list_head list;
+ ktime_t expires;
+ enum hrtimer_state state;
+ int (*function)(void *);
+ void *data;
+ struct hrtimer_base *base;
+};
+
+/**
+ * struct hrtimer_base - the timer base for a specific clock
+ *
+ * @index: clock type index for per_cpu support when moving a timer
+ * to a base on another cpu.
+ * @lock: lock protecting the base and associated timers
+ * @active: red black tree root node for the active timers
+ * @pending: list of pending timers for simple time ordered access
+ * @resolution: the resolution of the clock, in nanoseconds
+ * @get_time: function to retrieve the current time of the clock
+ * @curr_timer: the timer which is executing a callback right now
+ */
+struct hrtimer_base {
+ clockid_t index;
+ spinlock_t lock;
+ struct rb_root active;
+ struct list_head pending;
+ unsigned long resolution;
+ ktime_t (*get_time)(void);
+ struct hrtimer *curr_timer;
+};
+
+/* Exported timer functions: */
+
+/* Initialize timers: */
+extern void hrtimer_init(struct hrtimer *timer, const clockid_t which_clock);
+extern void hrtimer_rebase(struct hrtimer *timer, const clockid_t which_clock);
+
+
+/* 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);
+
+#define hrtimer_restart(timer) hrtimer_start((timer), (timer)->expires, HRTIMER_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);
+
+static inline int hrtimer_active(const struct hrtimer *timer)
+{
+ return timer->state == HRTIMER_PENDING;
+}
+
+/* Forward a hrtimer so it expires after now: */
+extern unsigned long hrtimer_forward(struct hrtimer *timer,
+ const ktime_t interval);
+
+/* Soft interrupt function to run the hrtimer queues: */
+extern void hrtimer_run_queues(void);
+
+/* Bootup initialization: */
+extern void __init hrtimers_init(void);
+
+#endif
--- /dev/null
+/*
+ * linux/kernel/hrtimer.c
+ *
+ * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
+ * Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
+ *
+ * High-resolution kernel timers
+ *
+ * In contrast to the low-resolution timeout API implemented in
+ * kernel/timer.c, hrtimers provide finer resolution and accuracy
+ * depending on system configuration and capabilities.
+ *
+ * These timers are currently used for:
+ * - itimers
+ * - POSIX timers
+ * - nanosleep
+ * - precise in-kernel timing
+ *
+ * Started by: Thomas Gleixner and Ingo Molnar
+ *
+ * Credits:
+ * based on kernel/timer.c
+ *
+ * For licencing details see kernel-base/COPYING
+ */
+
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/hrtimer.h>
+#include <linux/notifier.h>
+#include <linux/syscalls.h>
+#include <linux/interrupt.h>
+
+#include <asm/uaccess.h>
+
+/**
+ * ktime_get - get the monotonic time in ktime_t format
+ *
+ * returns the time in ktime_t format
+ */
+static ktime_t ktime_get(void)
+{
+ struct timespec now;
+
+ ktime_get_ts(&now);
+
+ return timespec_to_ktime(now);
+}
+
+/**
+ * ktime_get_real - get the real (wall-) time in ktime_t format
+ *
+ * returns the time in ktime_t format
+ */
+static ktime_t ktime_get_real(void)
+{
+ struct timespec now;
+
+ getnstimeofday(&now);
+
+ return timespec_to_ktime(now);
+}
+
+EXPORT_SYMBOL_GPL(ktime_get_real);
+
+/*
+ * The timer bases:
+ */
+
+#define MAX_HRTIMER_BASES 2
+
+static DEFINE_PER_CPU(struct hrtimer_base, hrtimer_bases[MAX_HRTIMER_BASES]) =
+{
+ {
+ .index = CLOCK_REALTIME,
+ .get_time = &ktime_get_real,
+ .resolution = KTIME_REALTIME_RES,
+ },
+ {
+ .index = CLOCK_MONOTONIC,
+ .get_time = &ktime_get,
+ .resolution = KTIME_MONOTONIC_RES,
+ },
+};
+
+/**
+ * ktime_get_ts - get the monotonic clock in timespec format
+ *
+ * @ts: pointer to timespec variable
+ *
+ * The function calculates the monotonic clock from the realtime
+ * clock and the wall_to_monotonic offset and stores the result
+ * in normalized timespec format in the variable pointed to by ts.
+ */
+void ktime_get_ts(struct timespec *ts)
+{
+ struct timespec tomono;
+ unsigned long seq;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ getnstimeofday(ts);
+ tomono = wall_to_monotonic;
+
+ } while (read_seqretry(&xtime_lock, seq));
+
+ set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
+ ts->tv_nsec + tomono.tv_nsec);
+}
+
+/*
+ * Functions and macros which are different for UP/SMP systems are kept in a
+ * single place
+ */
+#ifdef CONFIG_SMP
+
+#define set_curr_timer(b, t) do { (b)->curr_timer = (t); } while (0)
+
+/*
+ * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
+ * means that all timers which are tied to this base via timer->base are
+ * locked, and the base itself is locked too.
+ *
+ * So __run_timers/migrate_timers can safely modify all timers which could
+ * be found on the lists/queues.
+ *
+ * When the timer's base is locked, and the timer removed from list, it is
+ * possible to set timer->base = NULL and drop the lock: the timer remains
+ * locked.
+ */
+static struct hrtimer_base *lock_hrtimer_base(const struct hrtimer *timer,
+ unsigned long *flags)
+{
+ struct hrtimer_base *base;
+
+ for (;;) {
+ base = timer->base;
+ if (likely(base != NULL)) {
+ spin_lock_irqsave(&base->lock, *flags);
+ if (likely(base == timer->base))
+ return base;
+ /* The timer has migrated to another CPU: */
+ spin_unlock_irqrestore(&base->lock, *flags);
+ }
+ cpu_relax();
+ }
+}
+
+/*
+ * Switch the timer base to the current CPU when possible.
+ */
+static inline struct hrtimer_base *
+switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_base *base)
+{
+ struct hrtimer_base *new_base;
+
+ new_base = &__get_cpu_var(hrtimer_bases[base->index]);
+
+ if (base != new_base) {
+ /*
+ * We are trying to schedule the timer on the local CPU.
+ * However we can't change timer's base while it is running,
+ * so we keep it on the same CPU. No hassle vs. reprogramming
+ * the event source in the high resolution case. The softirq
+ * code will take care of this when the timer function has
+ * completed. There is no conflict as we hold the lock until
+ * the timer is enqueued.
+ */
+ if (unlikely(base->curr_timer == timer))
+ return base;
+
+ /* See the comment in lock_timer_base() */
+ timer->base = NULL;
+ spin_unlock(&base->lock);
+ spin_lock(&new_base->lock);
+ timer->base = new_base;
+ }
+ return new_base;
+}
+
+#else /* CONFIG_SMP */
+
+#define set_curr_timer(b, t) do { } while (0)
+
+static inline struct hrtimer_base *
+lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
+{
+ struct hrtimer_base *base = timer->base;
+
+ spin_lock_irqsave(&base->lock, *flags);
+
+ return base;
+}
+
+#define switch_hrtimer_base(t, b) (b)
+
+#endif /* !CONFIG_SMP */
+
+/*
+ * Functions for the union type storage format of ktime_t which are
+ * too large for inlining:
+ */
+#if BITS_PER_LONG < 64
+# ifndef CONFIG_KTIME_SCALAR
+/**
+ * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
+ *
+ * @kt: addend
+ * @nsec: the scalar nsec value to add
+ *
+ * Returns the sum of kt and nsec in ktime_t format
+ */
+ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
+{
+ ktime_t tmp;
+
+ if (likely(nsec < NSEC_PER_SEC)) {
+ tmp.tv64 = nsec;
+ } else {
+ unsigned long rem = do_div(nsec, NSEC_PER_SEC);
+
+ tmp = ktime_set((long)nsec, rem);
+ }
+
+ return ktime_add(kt, tmp);
+}
+
+#else /* CONFIG_KTIME_SCALAR */
+
+# endif /* !CONFIG_KTIME_SCALAR */
+
+/*
+ * Divide a ktime value by a nanosecond value
+ */
+static unsigned long ktime_divns(const ktime_t kt, nsec_t div)
+{
+ u64 dclc, inc, dns;
+ int sft = 0;
+
+ dclc = dns = ktime_to_ns(kt);
+ inc = div;
+ /* Make sure the divisor is less than 2^32: */
+ while (div >> 32) {
+ sft++;
+ div >>= 1;
+ }
+ dclc >>= sft;
+ do_div(dclc, (unsigned long) div);
+
+ return (unsigned long) dclc;
+}
+
+#else /* BITS_PER_LONG < 64 */
+# define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))
+#endif /* BITS_PER_LONG >= 64 */
+
+/*
+ * Counterpart to lock_timer_base above:
+ */
+static inline
+void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
+{
+ spin_unlock_irqrestore(&timer->base->lock, *flags);
+}
+
+/**
+ * hrtimer_forward - forward the timer expiry
+ *
+ * @timer: hrtimer to forward
+ * @interval: the interval to forward
+ *
+ * Forward the timer expiry so it will expire in the future.
+ * The number of overruns is added to the overrun field.
+ */
+unsigned long
+hrtimer_forward(struct hrtimer *timer, const ktime_t interval)
+{
+ unsigned long orun = 1;
+ ktime_t delta, now;
+
+ now = timer->base->get_time();
+
+ delta = ktime_sub(now, timer->expires);
+
+ if (delta.tv64 < 0)
+ return 0;
+
+ if (unlikely(delta.tv64 >= interval.tv64)) {
+ nsec_t incr = ktime_to_ns(interval);
+
+ orun = ktime_divns(delta, incr);
+ timer->expires = ktime_add_ns(timer->expires, incr * orun);
+ if (timer->expires.tv64 > now.tv64)
+ return orun;
+ /*
+ * This (and the ktime_add() below) is the
+ * correction for exact:
+ */
+ orun++;
+ }
+ timer->expires = ktime_add(timer->expires, interval);
+
+ return orun;
+}
+
+/*
+ * enqueue_hrtimer - internal function to (re)start a timer
+ *
+ * The timer is inserted in expiry order. Insertion into the
+ * red black tree is O(log(n)). Must hold the base lock.
+ */
+static void enqueue_hrtimer(struct hrtimer *timer, struct hrtimer_base *base)
+{
+ struct rb_node **link = &base->active.rb_node;
+ struct list_head *prev = &base->pending;
+ struct rb_node *parent = NULL;
+ struct hrtimer *entry;
+
+ /*
+ * Find the right place in the rbtree:
+ */
+ while (*link) {
+ parent = *link;
+ entry = rb_entry(parent, struct hrtimer, node);
+ /*
+ * We dont care about collisions. Nodes with
+ * the same expiry time stay together.
+ */
+ if (timer->expires.tv64 < entry->expires.tv64)
+ link = &(*link)->rb_left;
+ else {
+ link = &(*link)->rb_right;
+ prev = &entry->list;
+ }
+ }
+
+ /*
+ * Insert the timer to the rbtree and to the sorted list:
+ */
+ rb_link_node(&timer->node, parent, link);
+ rb_insert_color(&timer->node, &base->active);
+ list_add(&timer->list, prev);
+
+ timer->state = HRTIMER_PENDING;
+}
+
+
+/*
+ * __remove_hrtimer - internal function to remove a timer
+ *
+ * Caller must hold the base lock.
+ */
+static void __remove_hrtimer(struct hrtimer *timer, struct hrtimer_base *base)
+{
+ /*
+ * Remove the timer from the sorted list and from the rbtree:
+ */
+ list_del(&timer->list);
+ rb_erase(&timer->node, &base->active);
+}
+
+/*
+ * remove hrtimer, called with base lock held
+ */
+static inline int
+remove_hrtimer(struct hrtimer *timer, struct hrtimer_base *base)
+{
+ if (hrtimer_active(timer)) {
+ __remove_hrtimer(timer, base);
+ timer->state = HRTIMER_INACTIVE;
+ return 1;
+ }
+ return 0;
+}
+
+/**
+ * hrtimer_start - (re)start an relative timer on the current CPU
+ *
+ * @timer: the timer to be added
+ * @tim: expiry time
+ * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
+ *
+ * Returns:
+ * 0 on success
+ * 1 when the timer was active
+ */
+int
+hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
+{
+ struct hrtimer_base *base, *new_base;
+ unsigned long flags;
+ int ret;
+
+ base = lock_hrtimer_base(timer, &flags);
+
+ /* Remove an active timer from the queue: */
+ ret = remove_hrtimer(timer, base);
+
+ /* Switch the timer base, if necessary: */
+ new_base = switch_hrtimer_base(timer, base);
+
+ if (mode == HRTIMER_REL)
+ tim = ktime_add(tim, new_base->get_time());
+ timer->expires = tim;
+
+ enqueue_hrtimer(timer, new_base);
+
+ unlock_hrtimer_base(timer, &flags);
+
+ return ret;
+}
+
+/**
+ * hrtimer_try_to_cancel - try to deactivate a timer
+ *
+ * @timer: hrtimer to stop
+ *
+ * Returns:
+ * 0 when the timer was not active
+ * 1 when the timer was active
+ * -1 when the timer is currently excuting the callback function and
+ * can not be stopped
+ */
+int hrtimer_try_to_cancel(struct hrtimer *timer)
+{
+ struct hrtimer_base *base;
+ unsigned long flags;
+ int ret = -1;
+
+ base = lock_hrtimer_base(timer, &flags);
+
+ if (base->curr_timer != timer)
+ ret = remove_hrtimer(timer, base);
+
+ unlock_hrtimer_base(timer, &flags);
+
+ return ret;
+
+}
+
+/**
+ * hrtimer_cancel - cancel a timer and wait for the handler to finish.
+ *
+ * @timer: the timer to be cancelled
+ *
+ * Returns:
+ * 0 when the timer was not active
+ * 1 when the timer was active
+ */
+int hrtimer_cancel(struct hrtimer *timer)
+{
+ for (;;) {
+ int ret = hrtimer_try_to_cancel(timer);
+
+ if (ret >= 0)
+ return ret;
+ }
+}
+
+/**
+ * hrtimer_get_remaining - get remaining time for the timer
+ *
+ * @timer: the timer to read
+ */
+ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
+{
+ struct hrtimer_base *base;
+ unsigned long flags;
+ ktime_t rem;
+
+ base = lock_hrtimer_base(timer, &flags);
+ rem = ktime_sub(timer->expires, timer->base->get_time());
+ unlock_hrtimer_base(timer, &flags);
+
+ return rem;
+}
+
+/**
+ * hrtimer_rebase - rebase an initialized hrtimer to a different base
+ *
+ * @timer: the timer to be rebased
+ * @clock_id: the clock to be used
+ */
+void hrtimer_rebase(struct hrtimer *timer, const clockid_t clock_id)
+{
+ struct hrtimer_base *bases;
+
+ bases = per_cpu(hrtimer_bases, raw_smp_processor_id());
+ timer->base = &bases[clock_id];
+}
+
+/**
+ * hrtimer_init - initialize a timer to the given clock
+ *
+ * @timer: the timer to be initialized
+ * @clock_id: the clock to be used
+ */
+void hrtimer_init(struct hrtimer *timer, const clockid_t clock_id)
+{
+ memset(timer, 0, sizeof(struct hrtimer));
+ hrtimer_rebase(timer, clock_id);
+}
+
+/**
+ * hrtimer_get_res - get the timer resolution for a clock
+ *
+ * @which_clock: which clock to query
+ * @tp: pointer to timespec variable to store the resolution
+ *
+ * Store the resolution of the clock selected by which_clock in the
+ * variable pointed to by tp.
+ */
+int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
+{
+ struct hrtimer_base *bases;
+
+ tp->tv_sec = 0;
+ bases = per_cpu(hrtimer_bases, raw_smp_processor_id());
+ tp->tv_nsec = bases[which_clock].resolution;
+
+ return 0;
+}
+
+/*
+ * Expire the per base hrtimer-queue:
+ */
+static inline void run_hrtimer_queue(struct hrtimer_base *base)
+{
+ ktime_t now = base->get_time();
+
+ spin_lock_irq(&base->lock);
+
+ while (!list_empty(&base->pending)) {
+ struct hrtimer *timer;
+ int (*fn)(void *);
+ int restart;
+ void *data;
+
+ timer = list_entry(base->pending.next, struct hrtimer, list);
+ if (now.tv64 <= timer->expires.tv64)
+ break;
+
+ fn = timer->function;
+ data = timer->data;
+ set_curr_timer(base, timer);
+ __remove_hrtimer(timer, base);
+ spin_unlock_irq(&base->lock);
+
+ /*
+ * fn == NULL is special case for the simplest timer
+ * variant - wake up process and do not restart:
+ */
+ if (!fn) {
+ wake_up_process(data);
+ restart = HRTIMER_NORESTART;
+ } else
+ restart = fn(data);
+
+ spin_lock_irq(&base->lock);
+
+ if (restart == HRTIMER_RESTART)
+ enqueue_hrtimer(timer, base);
+ else
+ timer->state = HRTIMER_EXPIRED;
+ }
+ set_curr_timer(base, NULL);
+ spin_unlock_irq(&base->lock);
+}
+
+/*
+ * Called from timer softirq every jiffy, expire hrtimers:
+ */
+void hrtimer_run_queues(void)
+{
+ struct hrtimer_base *base = __get_cpu_var(hrtimer_bases);
+ int i;
+
+ for (i = 0; i < MAX_HRTIMER_BASES; i++)
+ run_hrtimer_queue(&base[i]);
+}
+
+/*
+ * Functions related to boot-time initialization:
+ */
+static void __devinit init_hrtimers_cpu(int cpu)
+{
+ struct hrtimer_base *base = per_cpu(hrtimer_bases, cpu);
+ int i;
+
+ for (i = 0; i < MAX_HRTIMER_BASES; i++) {
+ spin_lock_init(&base->lock);
+ INIT_LIST_HEAD(&base->pending);
+ base++;
+ }
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static void migrate_hrtimer_list(struct hrtimer_base *old_base,
+ struct hrtimer_base *new_base)
+{
+ struct hrtimer *timer;
+ struct rb_node *node;
+
+ while ((node = rb_first(&old_base->active))) {
+ timer = rb_entry(node, struct hrtimer, node);
+ __remove_hrtimer(timer, old_base);
+ timer->base = new_base;
+ enqueue_hrtimer(timer, new_base);
+ }
+}
+
+static void migrate_hrtimers(int cpu)
+{
+ struct hrtimer_base *old_base, *new_base;
+ int i;
+
+ BUG_ON(cpu_online(cpu));
+ old_base = per_cpu(hrtimer_bases, cpu);
+ new_base = get_cpu_var(hrtimer_bases);
+
+ local_irq_disable();
+
+ for (i = 0; i < MAX_HRTIMER_BASES; i++) {
+
+ spin_lock(&new_base->lock);
+ spin_lock(&old_base->lock);
+
+ BUG_ON(old_base->curr_timer);
+
+ migrate_hrtimer_list(old_base, new_base);
+
+ spin_unlock(&old_base->lock);
+ spin_unlock(&new_base->lock);
+ old_base++;
+ new_base++;
+ }
+
+ local_irq_enable();
+ put_cpu_var(hrtimer_bases);
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+static int __devinit hrtimer_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ long cpu = (long)hcpu;
+
+ switch (action) {
+
+ case CPU_UP_PREPARE:
+ init_hrtimers_cpu(cpu);
+ break;
+
+#ifdef CONFIG_HOTPLUG_CPU
+ case CPU_DEAD:
+ migrate_hrtimers(cpu);
+ break;
+#endif
+
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __devinitdata hrtimers_nb = {
+ .notifier_call = hrtimer_cpu_notify,
+};
+
+void __init hrtimers_init(void)
+{
+ hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
+ (void *)(long)smp_processor_id());
+ register_cpu_notifier(&hrtimers_nb);
+}
+
projects / linux-2.6 / commitdiff