tick-oneshot.c

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/*
 * linux/kernel/time/tick-oneshot.c
 *
 * This file contains functions which manage high resolution tick
 * related events.
 *
 * Copyright(C) 2005-2006, Thomas Gleixner <[email protected]>
 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
 *
 * This code is licenced under the GPL version 2. For details see
 * kernel-base/COPYING.
 */
#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/hrtimer.h>
#include <linux/interrupt.h>
#include <linux/percpu.h>
#include <linux/profile.h>
#include <linux/sched.h>

#include "tick-internal.h"

int tick_program_event(ktime_t expires, int force)
{
    struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);

    return clockevents_program_event(dev, expires, force);
}

void tick_resume_oneshot(void)
{
    struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);

    clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
    clockevents_program_event(dev, ktime_get(), true);
}

void tick_setup_oneshot(struct clock_event_device *newdev,
            void (*handler)(struct clock_event_device *),
            ktime_t next_event)
{
    newdev->event_handler = handler;
    clockevents_set_mode(newdev, CLOCK_EVT_MODE_ONESHOT);
    clockevents_program_event(newdev, next_event, true);
}

int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *))
{
    struct tick_device *td = &__get_cpu_var(tick_cpu_device);
    struct clock_event_device *dev = td->evtdev;

    if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT) ||
            !tick_device_is_functional(dev)) {

        printk(KERN_INFO "Clockevents: "
               "could not switch to one-shot mode:");
        if (!dev) {
            printk(" no tick device\n");
        } else {
            if (!tick_device_is_functional(dev))
                printk(" %s is not functional.\n", dev->name);
            else
                printk(" %s does not support one-shot mode.\n",
                       dev->name);
        }
        return -EINVAL;
    }

    td->mode = TICKDEV_MODE_ONESHOT;
    dev->event_handler = handler;
    clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
    tick_broadcast_switch_to_oneshot();
    return 0;
}

int tick_oneshot_mode_active(void)
{
    unsigned long flags;
    int ret;

    local_irq_save(flags);
    ret = __this_cpu_read(tick_cpu_device.mode) == TICKDEV_MODE_ONESHOT;
    local_irq_restore(flags);

    return ret;
}

#ifdef CONFIG_HIGH_RES_TIMERS

int tick_init_highres(void)
{
    return tick_switch_to_oneshot(hrtimer_interrupt);
}
#endif