C++ clockevents_set_mode函数代码示例

/*
 * Setup the device for a periodic tick
 */
void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
{
	tick_set_periodic_handler(dev, broadcast);

	/* Broadcast setup ? */
	if (!tick_device_is_functional(dev))
		return;

	if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
	    !tick_broadcast_oneshot_active()) {
		clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
	} else {
		unsigned long seq;
		ktime_t next;

		do {
			seq = read_seqcount_begin(&xtime_seq);
			next = tick_next_period;
		} while (read_seqcount_retry(&xtime_seq, seq));

		clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);

		for (;;) {
			if (!clockevents_program_event(dev, next, ktime_get()))
				return;
			next = ktime_add(next, tick_period);
		}
	}
}

/**
 * tick_switch_to_oneshot - switch to oneshot mode
 */
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;
}

/**
 * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz)
 */
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, ktime_get());
}

/**
 * tick_resume_onshot - resume oneshot mode
 */
void tick_resume_oneshot(void)
{
    struct tick_device *td = &__get_cpu_var(tick_cpu_device);
    struct clock_event_device *dev = td->evtdev;

    clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
    tick_program_event(ktime_get(), 1);
}

static int tick_broadcast_set_event(ktime_t expires, int force)
{
	struct clock_event_device *bc = tick_broadcast_device.evtdev;

	if (bc->mode != CLOCK_EVT_MODE_ONESHOT)
		clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);

	return clockevents_program_event(bc, expires, force);
}

static void tick_suspend(void)
{
	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
	unsigned long flags;

	spin_lock_irqsave(&tick_device_lock, flags);
	clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_SHUTDOWN);
	spin_unlock_irqrestore(&tick_device_lock, flags);
}

static int tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
				    ktime_t expires, int force)
{
	int ret;

	if (bc->mode != CLOCK_EVT_MODE_ONESHOT)
		clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);

	ret = clockevents_program_event(bc, expires, force);
	if (!ret)
		tick_broadcast_set_affinity(bc, cpumask_of(cpu));
	return ret;
}

void tick_resume(void)
{
	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
	int broadcast = tick_resume_broadcast();

	clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME);

	if (!broadcast) {
		if (td->mode == TICKDEV_MODE_PERIODIC)
			tick_setup_periodic(td->evtdev, 0);
		else
			tick_resume_oneshot();
	}
}

/**
 * tick_switch_to_oneshot - switch to oneshot mode
 */
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))
        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;
}

/*
 * Called from irq_enter() when idle was interrupted to reenable the
 * per cpu device.
 */
void tick_check_oneshot_broadcast(int cpu)
{
	if (cpumask_test_cpu(cpu, tick_broadcast_oneshot_mask)) {
		struct tick_device *td = &per_cpu(tick_cpu_device, cpu);

		/*
		 * We might be in the middle of switching over from
		 * periodic to oneshot. If the CPU has not yet
		 * switched over, leave the device alone.
		 */
		if (td->mode == TICKDEV_MODE_ONESHOT) {
			clockevents_set_mode(td->evtdev,
					     CLOCK_EVT_MODE_ONESHOT);
		}
	}
}

static void tick_resume(void)
{
	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
	unsigned long flags;
	int broadcast = tick_resume_broadcast();

	raw_spin_lock_irqsave(&tick_device_lock, flags);
	clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME);

	if (!broadcast) {
		if (td->mode == TICKDEV_MODE_PERIODIC)
			tick_setup_periodic(td->evtdev, 0);
		else
			tick_resume_oneshot();
	}
	raw_spin_unlock_irqrestore(&tick_device_lock, flags);
}

/*
 * Check, if the new registered device should be used.
 */
static int tick_check_new_device(struct clock_event_device *newdev)
{
	struct clock_event_device *curdev;
	struct tick_device *td;
	int cpu, ret = NOTIFY_OK;
	unsigned long flags;
	cpumask_t cpumask;

	spin_lock_irqsave(&tick_device_lock, flags);

	cpu = smp_processor_id();
	if (!cpu_isset(cpu, newdev->cpumask))
		goto out_bc;

	td = &per_cpu(tick_cpu_device, cpu);
	curdev = td->evtdev;
	cpumask = cpumask_of_cpu(cpu);

	/* cpu local device ? */
	if (!cpus_equal(newdev->cpumask, cpumask)) {

		/*
		 * If the cpu affinity of the device interrupt can not
		 * be set, ignore it.
		 */
		if (!irq_can_set_affinity(newdev->irq))
			goto out_bc;

		/*
		 * If we have a cpu local device already, do not replace it
		 * by a non cpu local device
		 */
		if (curdev && cpus_equal(curdev->cpumask, cpumask))
			goto out_bc;
	}

	/*
	 * If we have an active device, then check the rating and the oneshot
	 * feature.
	 */
	if (curdev) {
		/*
		 * Prefer one shot capable devices !
		 */
		if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) &&
		    !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
			goto out_bc;
		/*
		 * Check the rating
		 */
		if (curdev->rating >= newdev->rating)
			goto out_bc;
	}

	/*
	 * Replace the eventually existing device by the new
	 * device. If the current device is the broadcast device, do
	 * not give it back to the clockevents layer !
	 */
	if (tick_is_broadcast_device(curdev)) {
		clockevents_set_mode(curdev, CLOCK_EVT_MODE_SHUTDOWN);
		curdev = NULL;
	}
	clockevents_exchange_device(curdev, newdev);
	tick_setup_device(td, newdev, cpu, cpumask);
	if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
		tick_oneshot_notify();

	spin_unlock_irqrestore(&tick_device_lock, flags);
	return NOTIFY_STOP;

out_bc:
	/*
	 * Can the new device be used as a broadcast device ?
	 */
	if (tick_check_broadcast_device(newdev))
		ret = NOTIFY_STOP;

	spin_unlock_irqrestore(&tick_device_lock, flags);

	return ret;
}

static void __cpuinit mmp_percpu_timer_stop(struct clock_event_device *clk)
{
	clockevents_set_mode(clk, CLOCK_EVT_MODE_SHUTDOWN);
	disable_irq(clk->irq);
	return;
}