/* * linux/kernel/time/tick-common.c * * This file contains the base functions to manage periodic tick * related events. * * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> * 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 <asm/irq_regs.h> #include "tick-internal.h" /* * Tick devices */DEFINE_PER_CPU(struct tick_device, tick_cpu_device);/* * Tick next event: keeps track of the tick time */ktime_t tick_next_period;ktime_t tick_period;int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;static DEFINE_RAW_SPINLOCK(tick_device_lock); /* * Debugging: see timer_list.c */struct tick_device *tick_get_device(int cpu){	return &per_cpu(tick_cpu_device, cpu);} /** * tick_is_oneshot_available - check for a oneshot capable event device */int tick_is_oneshot_available(void){	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); 	if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT))		return 0;	if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))		return 1;	return tick_broadcast_oneshot_available();} /* * Periodic tick */static void tick_periodic(int cpu){	if (tick_do_timer_cpu == cpu) {		write_seqlock(&xtime_lock); 		/* Keep track of the next tick event */		tick_next_period = ktime_add(tick_next_period, tick_period); 		do_timer(1);		write_sequnlock(&xtime_lock);	} 	update_process_times(user_mode(get_irq_regs()));	profile_tick(CPU_PROFILING);} /* * Event handler for periodic ticks */void tick_handle_periodic(struct clock_event_device *dev){	int cpu = smp_processor_id();	ktime_t next; 	tick_periodic(cpu); 	if (dev->mode != CLOCK_EVT_MODE_ONESHOT)		return;	/*	 * Setup the next period for devices, which do not have	 * periodic mode:	 */	next = ktime_add(dev->next_event, tick_period);	for (;;) {		if (!clockevents_program_event(dev, next, ktime_get()))			return;		/*		 * Have to be careful here. If we're in oneshot mode,		 * before we call tick_periodic() in a loop, we need		 * to be sure we're using a real hardware clocksource.		 * Otherwise we could get trapped in an infinite		 * loop, as the tick_periodic() increments jiffies,		 * when then will increment time, posibly causing		 * the loop to trigger again and again.		 */		if (timekeeping_valid_for_hres())			tick_periodic(cpu);		next = ktime_add(next, tick_period);	}} /* * 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_seqbegin(&xtime_lock);			next = tick_next_period;		} while (read_seqretry(&xtime_lock, 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);		}	}} /* * Setup the tick device */static void tick_setup_device(struct tick_device *td,			      struct clock_event_device *newdev, int cpu,			      const struct cpumask *cpumask){	ktime_t next_event;	void (*handler)(struct clock_event_device *) = NULL; 	/*	 * First device setup ?	 */	if (!td->evtdev) {		/*		 * If no cpu took the do_timer update, assign it to		 * this cpu:		 */		if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {			tick_do_timer_cpu = cpu;			tick_next_period = ktime_get();			tick_period = ktime_set(0, NSEC_PER_SEC / HZ);		} 		/*		 * Startup in periodic mode first.		 */		td->mode = TICKDEV_MODE_PERIODIC;	} else {		handler = td->evtdev->event_handler;		next_event = td->evtdev->next_event;		td->evtdev->event_handler = clockevents_handle_noop;	} 	td->evtdev = newdev; 	/*	 * When the device is not per cpu, pin the interrupt to the	 * current cpu:	 */	if (!cpumask_equal(newdev->cpumask, cpumask))		irq_set_affinity(newdev->irq, cpumask); 	/*	 * When global broadcasting is active, check if the current	 * device is registered as a placeholder for broadcast mode.	 * This allows us to handle this x86 misfeature in a generic	 * way.	 */	if (tick_device_uses_broadcast(newdev, cpu))		return; 	if (td->mode == TICKDEV_MODE_PERIODIC)		tick_setup_periodic(newdev, 0);	else		tick_setup_oneshot(newdev, handler, next_event);} /* * 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; 	raw_spin_lock_irqsave(&tick_device_lock, flags); 	cpu = smp_processor_id();	if (!cpumask_test_cpu(cpu, newdev->cpumask))		goto out_bc; 	td = &per_cpu(tick_cpu_device, cpu);	curdev = td->evtdev; 	/* cpu local device ? */	if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) { 		/*		 * 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 && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))			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_shutdown(curdev);		curdev = NULL;	}	clockevents_exchange_device(curdev, newdev);	tick_setup_device(td, newdev, cpu, cpumask_of(cpu));	if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)		tick_oneshot_notify(); 	raw_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; 	raw_spin_unlock_irqrestore(&tick_device_lock, flags); 	return ret;} /* * Transfer the do_timer job away from a dying cpu. * * Called with interrupts disabled. */static void tick_handover_do_timer(int *cpup){	if (*cpup == tick_do_timer_cpu) {		int cpu = cpumask_first(cpu_online_mask); 		tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :			TICK_DO_TIMER_NONE;	}} /* * Shutdown an event device on a given cpu: * * This is called on a life CPU, when a CPU is dead. So we cannot * access the hardware device itself. * We just set the mode and remove it from the lists. */static void tick_shutdown(unsigned int *cpup){	struct tick_device *td = &per_cpu(tick_cpu_device, *cpup);	struct clock_event_device *dev = td->evtdev;	unsigned long flags; 	raw_spin_lock_irqsave(&tick_device_lock, flags);	td->mode = TICKDEV_MODE_PERIODIC;	if (dev) {		/*		 * Prevent that the clock events layer tries to call		 * the set mode function!		 */		dev->mode = CLOCK_EVT_MODE_UNUSED;		clockevents_exchange_device(dev, NULL);		td->evtdev = NULL;	}	raw_spin_unlock_irqrestore(&tick_device_lock, flags);} static void tick_suspend(void){	struct tick_device *td = &__get_cpu_var(tick_cpu_device);	unsigned long flags; 	raw_spin_lock_irqsave(&tick_device_lock, flags);	clockevents_shutdown(td->evtdev);	raw_spin_unlock_irqrestore(&tick_device_lock, flags);} 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);} /* * Notification about clock event devices */static int tick_notify(struct notifier_block *nb, unsigned long reason,			       void *dev){	switch (reason) { 	case CLOCK_EVT_NOTIFY_ADD:		return tick_check_new_device(dev); 	case CLOCK_EVT_NOTIFY_BROADCAST_ON:	case CLOCK_EVT_NOTIFY_BROADCAST_OFF:	case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:		tick_broadcast_on_off(reason, dev);		break; 	case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:	case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:		tick_broadcast_oneshot_control(reason);		break; 	case CLOCK_EVT_NOTIFY_CPU_DYING:		tick_handover_do_timer(dev);		break; 	case CLOCK_EVT_NOTIFY_CPU_DEAD:		tick_shutdown_broadcast_oneshot(dev);		tick_shutdown_broadcast(dev);		tick_shutdown(dev);		break; 	case CLOCK_EVT_NOTIFY_SUSPEND:		tick_suspend();		tick_suspend_broadcast();		break; 	case CLOCK_EVT_NOTIFY_RESUME:		tick_resume();		break; 	default:		break;	} 	return NOTIFY_OK;} static struct notifier_block tick_notifier = {	.notifier_call = tick_notify,}; /** * tick_init - initialize the tick control * * Register the notifier with the clockevents framework */void __init tick_init(void){	clockevents_register_notifier(&tick_notifier);}