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/*

 * linux/kernel/time/tick-broadcast.c

 *

 * This file contains functions which emulate a local clock-event

 * device via a broadcast event source.

 *

 * 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"

/*

 * Broadcast support for broken x86 hardware, where the local apic

 * timer stops in C3 state.

 */

struct tick_device tick_broadcast_device;

static cpumask_t tick_broadcast_mask;

static DEFINE_SPINLOCK(tick_broadcast_lock);

#ifdef CONFIG_TICK_ONESHOT

static void tick_broadcast_clear_oneshot(int cpu);

#else

static inline void tick_broadcast_clear_oneshot(int cpu) { }

#endif

/*

 * Debugging: see timer_list.c

 */

struct tick_device *tick_get_broadcast_device(void)

{

        return &tick_broadcast_device;

}

cpumask_t *tick_get_broadcast_mask(void)

{

        return &tick_broadcast_mask;

}

/*

 * Start the device in periodic mode

 */

static void tick_broadcast_start_periodic(struct clock_event_device *bc)

{

        if (bc)

                tick_setup_periodic(bc, 1);

}

/*

 * Check, if the device can be utilized as broadcast device:

 */

int tick_check_broadcast_device(struct clock_event_device *dev)

{

        if ((tick_broadcast_device.evtdev &&

             tick_broadcast_device.evtdev->rating >= dev->rating) ||

             (dev->features & CLOCK_EVT_FEAT_C3STOP))

                return 0;

        clockevents_exchange_device(NULL, dev);

        tick_broadcast_device.evtdev = dev;

        if (!cpus_empty(tick_broadcast_mask))

                tick_broadcast_start_periodic(dev);

        return 1;

}

/*

 * Check, if the device is the broadcast device

 */

int tick_is_broadcast_device(struct clock_event_device *dev)

{

        return (dev && tick_broadcast_device.evtdev == dev);

}

/*

 * Check, if the device is disfunctional and a place holder, which

 * needs to be handled by the broadcast device.

 */

int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)

{

        unsigned long flags;

        int ret = 0;

        spin_lock_irqsave(&tick_broadcast_lock, flags);

        /*

         * Devices might be registered with both periodic and oneshot

         * mode disabled. This signals, that the device needs to be

         * operated from the broadcast device and is a placeholder for

         * the cpu local device.

         */

        if (!tick_device_is_functional(dev)) {

                dev->event_handler = tick_handle_periodic;

                cpu_set(cpu, tick_broadcast_mask);

                tick_broadcast_start_periodic(tick_broadcast_device.evtdev);

                ret = 1;

        } else {

                /*

                 * When the new device is not affected by the stop

                 * feature and the cpu is marked in the broadcast mask

                 * then clear the broadcast bit.

                 */

                if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {

                        int cpu = smp_processor_id();

                        cpu_clear(cpu, tick_broadcast_mask);

                        tick_broadcast_clear_oneshot(cpu);

                }

        }

        spin_unlock_irqrestore(&tick_broadcast_lock, flags);

        return ret;

}

/*

 * Broadcast the event to the cpus, which are set in the mask

 */

int tick_do_broadcast(cpumask_t mask)

{

        int ret = 0, cpu = smp_processor_id();

        struct tick_device *td;

        /*

         * Check, if the current cpu is in the mask

         */

        if (cpu_isset(cpu, mask)) {

                cpu_clear(cpu, mask);

                td = &per_cpu(tick_cpu_device, cpu);

                td->evtdev->event_handler(td->evtdev);

                ret = 1;

        }

        if (!cpus_empty(mask)) {

                /*

                 * It might be necessary to actually check whether the devices

                 * have different broadcast functions. For now, just use the

                 * one of the first device. This works as long as we have this

                 * misfeature only on x86 (lapic)

                 */

                cpu = first_cpu(mask);

                td = &per_cpu(tick_cpu_device, cpu);

                td->evtdev->broadcast(mask);

                ret = 1;

        }

        return ret;

}

/*

 * Periodic broadcast:

 * - invoke the broadcast handlers

 */

static void tick_do_periodic_broadcast(void)

{

        cpumask_t mask;

        spin_lock(&tick_broadcast_lock);

        cpus_and(mask, cpu_online_map, tick_broadcast_mask);

        tick_do_broadcast(mask);

        spin_unlock(&tick_broadcast_lock);

}

/*

 * Event handler for periodic broadcast ticks

 */

static void tick_handle_periodic_broadcast(struct clock_event_device *dev)

{

        tick_do_periodic_broadcast();

        /*

         * The device is in periodic mode. No reprogramming necessary:

         */

        if (dev->mode == CLOCK_EVT_MODE_PERIODIC)

                return;

        /*

         * Setup the next period for devices, which do not have

         * periodic mode:

         */

        for (;;) {

                ktime_t next = ktime_add(dev->next_event, tick_period);

                if (!clockevents_program_event(dev, next, ktime_get()))

                        return;

                tick_do_periodic_broadcast();

        }

}

/*

 * Powerstate information: The system enters/leaves a state, where

 * affected devices might stop

 */

static void tick_do_broadcast_on_off(void *why)

{

        struct clock_event_device *bc, *dev;

        struct tick_device *td;

        unsigned long flags, *reason = why;

        int cpu;

        spin_lock_irqsave(&tick_broadcast_lock, flags);

        cpu = smp_processor_id();

        td = &per_cpu(tick_cpu_device, cpu);

        dev = td->evtdev;

        bc = tick_broadcast_device.evtdev;

        /*

         * Is the device not affected by the powerstate ?

         */

        if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))

                goto out;

        if (!tick_device_is_functional(dev))

                goto out;

        switch (*reason) {

        case CLOCK_EVT_NOTIFY_BROADCAST_ON:

        case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:

                if (!cpu_isset(cpu, tick_broadcast_mask)) {

                        cpu_set(cpu, tick_broadcast_mask);

                        if (td->mode == TICKDEV_MODE_PERIODIC)

                                clockevents_set_mode(dev,

                                                     CLOCK_EVT_MODE_SHUTDOWN);

                }

                if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)

                        dev->features |= CLOCK_EVT_FEAT_DUMMY;

                break;

        case CLOCK_EVT_NOTIFY_BROADCAST_OFF:

                if (cpu_isset(cpu, tick_broadcast_mask)) {

                        cpu_clear(cpu, tick_broadcast_mask);

                        if (td->mode == TICKDEV_MODE_PERIODIC)

                                tick_setup_periodic(dev, 0);

                }

                break;

        }

        if (cpus_empty(tick_broadcast_mask))

                clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);

        else {

                if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)

                        tick_broadcast_start_periodic(bc);

                else

                        tick_broadcast_setup_oneshot(bc);

        }

out:

        spin_unlock_irqrestore(&tick_broadcast_lock, flags);

}

/*

 * Powerstate information: The system enters/leaves a state, where

 * affected devices might stop.

 */

void tick_broadcast_on_off(unsigned long reason, int *oncpu)

{

        if (!cpu_isset(*oncpu, cpu_online_map))

                printk(KERN_ERR "tick-braodcast: ignoring broadcast for "

                       "offline CPU #%d\n", *oncpu);

        else

                smp_call_function_single(*oncpu, tick_do_broadcast_on_off,

                                         &reason, 1, 1);

}

/*

 * Set the periodic handler depending on broadcast on/off

 */

void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)

{

        if (!broadcast)

                dev->event_handler = tick_handle_periodic;

        else

                dev->event_handler = tick_handle_periodic_broadcast;

}

/*

 * Remove a CPU from broadcasting

 */

void tick_shutdown_broadcast(unsigned int *cpup)

{

        struct clock_event_device *bc;

        unsigned long flags;

        unsigned int cpu = *cpup;

        spin_lock_irqsave(&tick_broadcast_lock, flags);

        bc = tick_broadcast_device.evtdev;

        cpu_clear(cpu, tick_broadcast_mask);

        if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {

                if (bc && cpus_empty(tick_broadcast_mask))

                        clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);

        }

        spin_unlock_irqrestore(&tick_broadcast_lock, flags);

}

void tick_suspend_broadcast(void)

{

        struct clock_event_device *bc;

        unsigned long flags;

        spin_lock_irqsave(&tick_broadcast_lock, flags);

        bc = tick_broadcast_device.evtdev;

        if (bc)

                clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);

        spin_unlock_irqrestore(&tick_broadcast_lock, flags);

}

int tick_resume_broadcast(void)

{

        struct clock_event_device *bc;

        unsigned long flags;

        int broadcast = 0;

        spin_lock_irqsave(&tick_broadcast_lock, flags);

        bc = tick_broadcast_device.evtdev;

        if (bc) {

                clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);

                switch (tick_broadcast_device.mode) {

                case TICKDEV_MODE_PERIODIC:

                        if(!cpus_empty(tick_broadcast_mask))

                                tick_broadcast_start_periodic(bc);

                        broadcast = cpu_isset(smp_processor_id(),

                                              tick_broadcast_mask);

                        break;

                case TICKDEV_MODE_ONESHOT:

                        broadcast = tick_resume_broadcast_oneshot(bc);

                        break;

                }

        }

        spin_unlock_irqrestore(&tick_broadcast_lock, flags);

        return broadcast;

}

#ifdef CONFIG_TICK_ONESHOT

static cpumask_t tick_broadcast_oneshot_mask;

/*

 * Debugging: see timer_list.c

 */

cpumask_t *tick_get_broadcast_oneshot_mask(void)

{

        return &tick_broadcast_oneshot_mask;

}

static int tick_broadcast_set_event(ktime_t expires, int force)

{

        struct clock_event_device *bc = tick_broadcast_device.evtdev;

        ktime_t now = ktime_get();

        int res;

        for(;;) {

                res = clockevents_program_event(bc, expires, now);

                if (!res || !force)

                        return res;

                now = ktime_get();

                expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));

        }

}

int tick_resume_broadcast_oneshot(struct clock_event_device *bc)

{

        clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);

        return 0;

}

/*

 * Handle oneshot mode broadcasting

 */

static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)

{

        struct tick_device *td;

        cpumask_t mask;

        ktime_t now, next_event;

        int cpu;

        spin_lock(&tick_broadcast_lock);

again:

        dev->next_event.tv64 = KTIME_MAX;

        next_event.tv64 = KTIME_MAX;

        mask = CPU_MASK_NONE;

        now = ktime_get();

        /* Find all expired events */

        for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;

             cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {

                td = &per_cpu(tick_cpu_device, cpu);

                if (td->evtdev->next_event.tv64 <= now.tv64)

                        cpu_set(cpu, mask);

                else if (td->evtdev->next_event.tv64 < next_event.tv64)

                        next_event.tv64 = td->evtdev->next_event.tv64;

        }

        /*

         * Wakeup the cpus which have an expired event.

         */

        tick_do_broadcast(mask);

        /*

         * Two reasons for reprogram:

         *

         * - The global event did not expire any CPU local

         * events. This happens in dyntick mode, as the maximum PIT

         * delta is quite small.

         *

         * - There are pending events on sleeping CPUs which were not

         * in the event mask

         */

        if (next_event.tv64 != KTIME_MAX) {

                /*

                 * Rearm the broadcast device. If event expired,

                 * repeat the above

                 */

                if (tick_broadcast_set_event(next_event, 0))

                        goto again;

        }

        spin_unlock(&tick_broadcast_lock);

}

/*

 * Powerstate information: The system enters/leaves a state, where

 * affected devices might stop

 */

void tick_broadcast_oneshot_control(unsigned long reason)

{

        struct clock_event_device *bc, *dev;

        struct tick_device *td;

        unsigned long flags;

        int cpu;

        spin_lock_irqsave(&tick_broadcast_lock, flags);

        /*

         * Periodic mode does not care about the enter/exit of power

         * states

         */

        if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)

                goto out;

        bc = tick_broadcast_device.evtdev;

        cpu = smp_processor_id();

        td = &per_cpu(tick_cpu_device, cpu);

        dev = td->evtdev;

        if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))

                goto out;

        if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {

                if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {

                        cpu_set(cpu, tick_broadcast_oneshot_mask);

                        clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);

                        if (dev->next_event.tv64 < bc->next_event.tv64)

                                tick_broadcast_set_event(dev->next_event, 1);

                }

        } else {

                if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {

                        cpu_clear(cpu, tick_broadcast_oneshot_mask);

                        clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);

                        if (dev->next_event.tv64 != KTIME_MAX)

                                tick_program_event(dev->next_event, 1);

                }

        }

out:

        spin_unlock_irqrestore(&tick_broadcast_lock, flags);

}

/*

 * Reset the one shot broadcast for a cpu

 *

 * Called with tick_broadcast_lock held

 */

static void tick_broadcast_clear_oneshot(int cpu)

{

        cpu_clear(cpu, tick_broadcast_oneshot_mask);

}

/**

 * tick_broadcast_setup_oneshot - setup the broadcast device

 */

void tick_broadcast_setup_oneshot(struct clock_event_device *bc)

{

        bc->event_handler = tick_handle_oneshot_broadcast;

        clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);

        bc->next_event.tv64 = KTIME_MAX;

}

/*

 * Select oneshot operating mode for the broadcast device

 */

void tick_broadcast_switch_to_oneshot(void)

{

        struct clock_event_device *bc;

        unsigned long flags;

        spin_lock_irqsave(&tick_broadcast_lock, flags);

        tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;

        bc = tick_broadcast_device.evtdev;

        if (bc)

                tick_broadcast_setup_oneshot(bc);

        spin_unlock_irqrestore(&tick_broadcast_lock, flags);

}

/*

 * Remove a dead CPU from broadcasting

 */

void tick_shutdown_broadcast_oneshot(unsigned int *cpup)

{

        unsigned long flags;

        unsigned int cpu = *cpup;

        spin_lock_irqsave(&tick_broadcast_lock, flags);

        /*

         * Clear the broadcast mask flag for the dead cpu, but do not

         * stop the broadcast device!

         */

        cpu_clear(cpu, tick_broadcast_oneshot_mask);

        spin_unlock_irqrestore(&tick_broadcast_lock, flags);

}

#endif