2 * linux/kernel/time/tick-oneshot.c
4 * This file contains functions which manage high resolution tick
7 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
8 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
9 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
11 * This code is licenced under the GPL version 2. For details see
12 * kernel-base/COPYING.
14 #include <linux/cpu.h>
15 #include <linux/err.h>
16 #include <linux/hrtimer.h>
17 #include <linux/interrupt.h>
18 #include <linux/percpu.h>
19 #include <linux/profile.h>
20 #include <linux/sched.h>
21 #include <linux/tick.h>
23 #include "tick-internal.h"
26 * tick_program_event internal worker function
28 static int __tick_program_event(struct clock_event_device *dev,
29 ktime_t expires, int force)
31 ktime_t now = ktime_get();
34 int ret = clockevents_program_event(dev, expires, now);
39 expires = ktime_add(now, ktime_set(0, dev->min_delta_ns));
46 int tick_program_event(ktime_t expires, int force)
48 struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
50 return __tick_program_event(dev, expires, force);
54 * tick_resume_onshot - resume oneshot mode
56 void tick_resume_oneshot(void)
58 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
59 struct clock_event_device *dev = td->evtdev;
61 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
62 tick_program_event(ktime_get(), 1);
66 * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz)
68 void tick_setup_oneshot(struct clock_event_device *newdev,
69 void (*handler)(struct clock_event_device *),
72 newdev->event_handler = handler;
73 clockevents_set_mode(newdev, CLOCK_EVT_MODE_ONESHOT);
74 __tick_program_event(newdev, next_event, 1);
78 * tick_switch_to_oneshot - switch to oneshot mode
80 int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *))
82 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
83 struct clock_event_device *dev = td->evtdev;
85 if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT) ||
86 !tick_device_is_functional(dev)) {
88 printk(KERN_INFO "Clockevents: "
89 "could not switch to one-shot mode:");
91 printk(" no tick device\n");
93 if (!tick_device_is_functional(dev))
94 printk(" %s is not functional.\n", dev->name);
96 printk(" %s does not support one-shot mode.\n",
102 td->mode = TICKDEV_MODE_ONESHOT;
103 dev->event_handler = handler;
104 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
105 tick_broadcast_switch_to_oneshot();
109 #ifdef CONFIG_HIGH_RES_TIMERS
111 * tick_init_highres - switch to high resolution mode
113 * Called with interrupts disabled.
115 int tick_init_highres(void)
117 return tick_switch_to_oneshot(hrtimer_interrupt);