| /* |
| * 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; |
| static int tick_do_timer_cpu = -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; |
| |
| 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; |
| out: |
| 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; |
| } |
| 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: |
| 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; |
| |
| 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); |
| } |