+/* High resolution timer related functions */
+#ifdef CONFIG_HIGH_RES_TIMERS
+
+/*
+ * High resolution timer enabled ?
+ */
+static int hrtimer_hres_enabled __read_mostly = 1;
+
+/*
+ * Enable / Disable high resolution mode
+ */
+static int __init setup_hrtimer_hres(char *str)
+{
+ if (!strcmp(str, "off"))
+ hrtimer_hres_enabled = 0;
+ else if (!strcmp(str, "on"))
+ hrtimer_hres_enabled = 1;
+ else
+ return 0;
+ return 1;
+}
+
+__setup("highres=", setup_hrtimer_hres);
+
+/*
+ * hrtimer_high_res_enabled - query, if the highres mode is enabled
+ */
+static inline int hrtimer_is_hres_enabled(void)
+{
+ return hrtimer_hres_enabled;
+}
+
+/*
+ * Is the high resolution mode active ?
+ */
+static inline int hrtimer_hres_active(void)
+{
+ return __get_cpu_var(hrtimer_bases).hres_active;
+}
+
+/*
+ * Reprogram the event source with checking both queues for the
+ * next event
+ * Called with interrupts disabled and base->lock held
+ */
+static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base)
+{
+ int i;
+ struct hrtimer_clock_base *base = cpu_base->clock_base;
+ ktime_t expires;
+
+ cpu_base->expires_next.tv64 = KTIME_MAX;
+
+ for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
+ struct hrtimer *timer;
+
+ if (!base->first)
+ continue;
+ timer = rb_entry(base->first, struct hrtimer, node);
+ expires = ktime_sub(timer->expires, base->offset);
+ if (expires.tv64 < cpu_base->expires_next.tv64)
+ cpu_base->expires_next = expires;
+ }
+
+ if (cpu_base->expires_next.tv64 != KTIME_MAX)
+ tick_program_event(cpu_base->expires_next, 1);
+}
+
+/*
+ * Shared reprogramming for clock_realtime and clock_monotonic
+ *
+ * When a timer is enqueued and expires earlier than the already enqueued
+ * timers, we have to check, whether it expires earlier than the timer for
+ * which the clock event device was armed.
+ *
+ * Called with interrupts disabled and base->cpu_base.lock held
+ */
+static int hrtimer_reprogram(struct hrtimer *timer,
+ struct hrtimer_clock_base *base)
+{
+ ktime_t *expires_next = &__get_cpu_var(hrtimer_bases).expires_next;
+ ktime_t expires = ktime_sub(timer->expires, base->offset);
+ int res;
+
+ /*
+ * When the callback is running, we do not reprogram the clock event
+ * device. The timer callback is either running on a different CPU or
+ * the callback is executed in the hrtimer_interupt context. The
+ * reprogramming is handled either by the softirq, which called the
+ * callback or at the end of the hrtimer_interrupt.
+ */
+ if (hrtimer_callback_running(timer))
+ return 0;
+
+ if (expires.tv64 >= expires_next->tv64)
+ return 0;
+
+ /*
+ * Clockevents returns -ETIME, when the event was in the past.
+ */
+ res = tick_program_event(expires, 0);
+ if (!IS_ERR_VALUE(res))
+ *expires_next = expires;
+ return res;
+}
+
+
+/*
+ * Retrigger next event is called after clock was set
+ *
+ * Called with interrupts disabled via on_each_cpu()
+ */
+static void retrigger_next_event(void *arg)
+{
+ struct hrtimer_cpu_base *base;
+ struct timespec realtime_offset;
+ unsigned long seq;
+
+ if (!hrtimer_hres_active())
+ return;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ set_normalized_timespec(&realtime_offset,
+ -wall_to_monotonic.tv_sec,
+ -wall_to_monotonic.tv_nsec);
+ } while (read_seqretry(&xtime_lock, seq));
+
+ base = &__get_cpu_var(hrtimer_bases);
+
+ /* Adjust CLOCK_REALTIME offset */
+ spin_lock(&base->lock);
+ base->clock_base[CLOCK_REALTIME].offset =
+ timespec_to_ktime(realtime_offset);
+
+ hrtimer_force_reprogram(base);
+ spin_unlock(&base->lock);
+}
+
+/*
+ * Clock realtime was set
+ *
+ * Change the offset of the realtime clock vs. the monotonic
+ * clock.
+ *
+ * We might have to reprogram the high resolution timer interrupt. On
+ * SMP we call the architecture specific code to retrigger _all_ high
+ * resolution timer interrupts. On UP we just disable interrupts and
+ * call the high resolution interrupt code.
+ */
+void clock_was_set(void)
+{
+ /* Retrigger the CPU local events everywhere */
+ on_each_cpu(retrigger_next_event, NULL, 0, 1);
+}
+
+/*
+ * Check, whether the timer is on the callback pending list
+ */
+static inline int hrtimer_cb_pending(const struct hrtimer *timer)
+{
+ return timer->state & HRTIMER_STATE_PENDING;
+}
+
+/*
+ * Remove a timer from the callback pending list
+ */
+static inline void hrtimer_remove_cb_pending(struct hrtimer *timer)
+{
+ list_del_init(&timer->cb_entry);
+}
+
+/*
+ * Initialize the high resolution related parts of cpu_base
+ */
+static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
+{
+ base->expires_next.tv64 = KTIME_MAX;
+ base->hres_active = 0;
+ INIT_LIST_HEAD(&base->cb_pending);
+}
+
+/*
+ * Initialize the high resolution related parts of a hrtimer
+ */
+static inline void hrtimer_init_timer_hres(struct hrtimer *timer)
+{
+ INIT_LIST_HEAD(&timer->cb_entry);
+}
+
+/*
+ * When High resolution timers are active, try to reprogram. Note, that in case
+ * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
+ * check happens. The timer gets enqueued into the rbtree. The reprogramming
+ * and expiry check is done in the hrtimer_interrupt or in the softirq.
+ */
+static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
+ struct hrtimer_clock_base *base)
+{
+ if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) {
+
+ /* Timer is expired, act upon the callback mode */
+ switch(timer->cb_mode) {
+ case HRTIMER_CB_IRQSAFE_NO_RESTART:
+ /*
+ * We can call the callback from here. No restart
+ * happens, so no danger of recursion
+ */
+ BUG_ON(timer->function(timer) != HRTIMER_NORESTART);
+ return 1;
+ case HRTIMER_CB_IRQSAFE_NO_SOFTIRQ:
+ /*
+ * This is solely for the sched tick emulation with
+ * dynamic tick support to ensure that we do not
+ * restart the tick right on the edge and end up with
+ * the tick timer in the softirq ! The calling site
+ * takes care of this.
+ */
+ return 1;
+ case HRTIMER_CB_IRQSAFE:
+ case HRTIMER_CB_SOFTIRQ:
+ /*
+ * Move everything else into the softirq pending list !
+ */
+ list_add_tail(&timer->cb_entry,
+ &base->cpu_base->cb_pending);
+ timer->state = HRTIMER_STATE_PENDING;
+ raise_softirq(HRTIMER_SOFTIRQ);
+ return 1;
+ default:
+ BUG();
+ }
+ }
+ return 0;
+}
+
+/*
+ * Switch to high resolution mode
+ */
+static void hrtimer_switch_to_hres(void)
+{
+ struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
+ unsigned long flags;
+
+ if (base->hres_active)
+ return;
+
+ local_irq_save(flags);
+
+ if (tick_init_highres()) {
+ local_irq_restore(flags);
+ return;
+ }
+ base->hres_active = 1;
+ base->clock_base[CLOCK_REALTIME].resolution = KTIME_HIGH_RES;
+ base->clock_base[CLOCK_MONOTONIC].resolution = KTIME_HIGH_RES;
+
+ tick_setup_sched_timer();
+
+ /* "Retrigger" the interrupt to get things going */
+ retrigger_next_event(NULL);
+ local_irq_restore(flags);
+ printk(KERN_INFO "Switched to high resolution mode on CPU %d\n",
+ smp_processor_id());
+}
+
+#else
+
+static inline int hrtimer_hres_active(void) { return 0; }
+static inline int hrtimer_is_hres_enabled(void) { return 0; }
+static inline void hrtimer_switch_to_hres(void) { }
+static inline void hrtimer_force_reprogram(struct hrtimer_cpu_base *base) { }
+static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
+ struct hrtimer_clock_base *base)
+{
+ return 0;
+}
+static inline int hrtimer_cb_pending(struct hrtimer *timer) { return 0; }
+static inline void hrtimer_remove_cb_pending(struct hrtimer *timer) { }
+static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
+static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { }
+
+#endif /* CONFIG_HIGH_RES_TIMERS */
+
+#ifdef CONFIG_TIMER_STATS
+void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer, void *addr)
+{
+ if (timer->start_site)
+ return;
+
+ timer->start_site = addr;
+ memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
+ timer->start_pid = current->pid;
+}
+#endif
+