Subversion Repositories test_project

/*

 * 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/irq.h>

#include <linux/percpu.h>

#include <linux/profile.h>

#include <linux/sched.h>

#include <linux/tick.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 = -1;

DEFINE_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 = __get_cpu_var(tick_cpu_device).evtdev;

        return dev && (dev->features & CLOCK_EVT_FEAT_ONESHOT);

}

/*

 * 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;

                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) {

                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,

                              cpumask_t 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 == -1) {

                        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 = newdev;

        /*

         * When the device is not per cpu, pin the interrupt to the

         * current cpu:

         */

        if (!cpus_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;

        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;

}

/*

 * 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;

        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;

        }

        /* Transfer the do_timer job away from this cpu */

        if (*cpup == tick_do_timer_cpu) {

                int cpu = first_cpu(cpu_online_map);

                tick_do_timer_cpu = (cpu != NR_CPUS) ? cpu : -1;

        }

        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;

        spin_lock_irqsave(&tick_device_lock, flags);

        clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_SHUTDOWN);

        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();

        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();

        }

        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_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);

}