// SPDX-License-Identifier: GPL-2.0/* * 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 */#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 <linux/module.h>#include <trace/events/power.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; /* * tick_do_timer_cpu is a timer core internal variable which holds the CPU NR * which is responsible for calling do_timer(), i.e. the timekeeping stuff. This * variable has two functions: * * 1) Prevent a thundering herd issue of a gazillion of CPUs trying to grab the * timekeeping lock all at once. Only the CPU which is assigned to do the * update is handling it. * * 2) Hand off the duty in the NOHZ idle case by setting the value to * TICK_DO_TIMER_NONE, i.e. a non existing CPU. So the next cpu which looks * at it will take over and keep the time keeping alive. The handover * procedure also covers cpu hotplug. */int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;#ifdef CONFIG_NO_HZ_FULL/* * tick_do_timer_boot_cpu indicates the boot CPU temporarily owns * tick_do_timer_cpu and it should be taken over by an eligible secondary * when one comes online. */static int tick_do_timer_boot_cpu __read_mostly = -1;#endif /* * 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(&jiffies_lock); /* Keep track of the next tick event */ tick_next_period = ktime_add(tick_next_period, tick_period); do_timer(1); write_sequnlock(&jiffies_lock); update_wall_time(); } 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 = dev->next_event; tick_periodic(cpu); #if defined(CONFIG_HIGH_RES_TIMERS) || defined(CONFIG_NO_HZ_COMMON) /* * The cpu might have transitioned to HIGHRES or NOHZ mode via * update_process_times() -> run_local_timers() -> * hrtimer_run_queues(). */ if (dev->event_handler != tick_handle_periodic) return;#endif if (!clockevent_state_oneshot(dev)) return; for (;;) { /* * Setup the next period for devices, which do not have * periodic mode: */ next = ktime_add(next, tick_period); if (!clockevents_program_event(dev, next, false)) 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, * which then will increment time, possibly causing * the loop to trigger again and again. */ if (timekeeping_valid_for_hres()) tick_periodic(cpu); }} /* * 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_switch_state(dev, CLOCK_EVT_STATE_PERIODIC); } else { unsigned int seq; ktime_t next; do { seq = read_seqbegin(&jiffies_lock); next = tick_next_period; } while (read_seqretry(&jiffies_lock, seq)); clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT); for (;;) { if (!clockevents_program_event(dev, next, false)) return; next = ktime_add(next, tick_period); } }} #ifdef CONFIG_NO_HZ_FULLstatic void giveup_do_timer(void *info){ int cpu = *(unsigned int *)info; WARN_ON(tick_do_timer_cpu != smp_processor_id()); tick_do_timer_cpu = cpu;} static void tick_take_do_timer_from_boot(void){ int cpu = smp_processor_id(); int from = tick_do_timer_boot_cpu; if (from >= 0 && from != cpu) smp_call_function_single(from, giveup_do_timer, &cpu, 1);}#endif /* * Setup the tick device */static void tick_setup_device(struct tick_device *td, struct clock_event_device *newdev, int cpu, const struct cpumask *cpumask){ void (*handler)(struct clock_event_device *) = NULL; ktime_t next_event = 0; /* * 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 = NSEC_PER_SEC / HZ;#ifdef CONFIG_NO_HZ_FULL /* * The boot CPU may be nohz_full, in which case set * tick_do_timer_boot_cpu so the first housekeeping * secondary that comes up will take do_timer from * us. */ if (tick_nohz_full_cpu(cpu)) tick_do_timer_boot_cpu = cpu; } else if (tick_do_timer_boot_cpu != -1 && !tick_nohz_full_cpu(cpu)) { tick_take_do_timer_from_boot(); tick_do_timer_boot_cpu = -1; WARN_ON(tick_do_timer_cpu != cpu);#endif } /* * 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. This function also returns !=0 when we keep the * current active broadcast state for this CPU. */ 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);} void tick_install_replacement(struct clock_event_device *newdev){ struct tick_device *td = this_cpu_ptr(&tick_cpu_device); int cpu = smp_processor_id(); clockevents_exchange_device(td->evtdev, newdev); tick_setup_device(td, newdev, cpu, cpumask_of(cpu)); if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) tick_oneshot_notify();} static bool tick_check_percpu(struct clock_event_device *curdev, struct clock_event_device *newdev, int cpu){ if (!cpumask_test_cpu(cpu, newdev->cpumask)) return false; if (cpumask_equal(newdev->cpumask, cpumask_of(cpu))) return true; /* Check if irq affinity can be set */ if (newdev->irq >= 0 && !irq_can_set_affinity(newdev->irq)) return false; /* Prefer an existing cpu local device */ if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu))) return false; return true;} static bool tick_check_preferred(struct clock_event_device *curdev, struct clock_event_device *newdev){ /* Prefer oneshot capable device */ if (!(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) { if (curdev && (curdev->features & CLOCK_EVT_FEAT_ONESHOT)) return false; if (tick_oneshot_mode_active()) return false; } /* * Use the higher rated one, but prefer a CPU local device with a lower * rating than a non-CPU local device */ return !curdev || newdev->rating > curdev->rating || !cpumask_equal(curdev->cpumask, newdev->cpumask);} /* * Check whether the new device is a better fit than curdev. curdev * can be NULL ! */bool tick_check_replacement(struct clock_event_device *curdev, struct clock_event_device *newdev){ if (!tick_check_percpu(curdev, newdev, smp_processor_id())) return false; return tick_check_preferred(curdev, newdev);} /* * Check, if the new registered device should be used. Called with * clockevents_lock held and interrupts disabled. */void tick_check_new_device(struct clock_event_device *newdev){ struct clock_event_device *curdev; struct tick_device *td; int cpu; cpu = smp_processor_id(); td = &per_cpu(tick_cpu_device, cpu); curdev = td->evtdev; /* cpu local device ? */ if (!tick_check_percpu(curdev, newdev, cpu)) goto out_bc; /* Preference decision */ if (!tick_check_preferred(curdev, newdev)) goto out_bc; if (!try_module_get(newdev->owner)) return; /* * 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(); return; out_bc: /* * Can the new device be used as a broadcast device ? */ tick_install_broadcast_device(newdev);} /** * tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode * @state: The target state (enter/exit) * * The system enters/leaves a state, where affected devices might stop * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups. * * Called with interrupts disabled, so clockevents_lock is not * required here because the local clock event device cannot go away * under us. */int tick_broadcast_oneshot_control(enum tick_broadcast_state state){ struct tick_device *td = this_cpu_ptr(&tick_cpu_device); if (!(td->evtdev->features & CLOCK_EVT_FEAT_C3STOP)) return 0; return __tick_broadcast_oneshot_control(state);}EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control); #ifdef CONFIG_HOTPLUG_CPU/* * Transfer the do_timer job away from a dying cpu. * * Called with interrupts disabled. Not locking required. If * tick_do_timer_cpu is owned by this cpu, nothing can change it. */void tick_handover_do_timer(void){ if (tick_do_timer_cpu == smp_processor_id()) { 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. */void tick_shutdown(unsigned int cpu){ struct tick_device *td = &per_cpu(tick_cpu_device, cpu); struct clock_event_device *dev = td->evtdev; td->mode = TICKDEV_MODE_PERIODIC; if (dev) { /* * Prevent that the clock events layer tries to call * the set mode function! */ clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED); clockevents_exchange_device(dev, NULL); dev->event_handler = clockevents_handle_noop; td->evtdev = NULL; }}#endif /** * tick_suspend_local - Suspend the local tick device * * Called from the local cpu for freeze with interrupts disabled. * * No locks required. Nothing can change the per cpu device. */void tick_suspend_local(void){ struct tick_device *td = this_cpu_ptr(&tick_cpu_device); clockevents_shutdown(td->evtdev);} /** * tick_resume_local - Resume the local tick device * * Called from the local CPU for unfreeze or XEN resume magic. * * No locks required. Nothing can change the per cpu device. */void tick_resume_local(void){ struct tick_device *td = this_cpu_ptr(&tick_cpu_device); bool broadcast = tick_resume_check_broadcast(); clockevents_tick_resume(td->evtdev); if (!broadcast) { if (td->mode == TICKDEV_MODE_PERIODIC) tick_setup_periodic(td->evtdev, 0); else tick_resume_oneshot(); }} /** * tick_suspend - Suspend the tick and the broadcast device * * Called from syscore_suspend() via timekeeping_suspend with only one * CPU online and interrupts disabled or from tick_unfreeze() under * tick_freeze_lock. * * No locks required. Nothing can change the per cpu device. */void tick_suspend(void){ tick_suspend_local(); tick_suspend_broadcast();} /** * tick_resume - Resume the tick and the broadcast device * * Called from syscore_resume() via timekeeping_resume with only one * CPU online and interrupts disabled.Lines 1–500 of 577. Load more
// SPDX-License-Identifier: GPL-2.0 /* * 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 */ #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 <linux/module.h> #include <trace/events/power.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; /* * tick_do_timer_cpu is a timer core internal variable which holds the CPU NR * which is responsible for calling do_timer(), i.e. the timekeeping stuff. This * variable has two functions: * * 1) Prevent a thundering herd issue of a gazillion of CPUs trying to grab the * timekeeping lock all at once. Only the CPU which is assigned to do the * update is handling it. * * 2) Hand off the duty in the NOHZ idle case by setting the value to * TICK_DO_TIMER_NONE, i.e. a non existing CPU. So the next cpu which looks * at it will take over and keep the time keeping alive. The handover * procedure also covers cpu hotplug. */ int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT; #ifdef CONFIG_NO_HZ_FULL /* * tick_do_timer_boot_cpu indicates the boot CPU temporarily owns * tick_do_timer_cpu and it should be taken over by an eligible secondary * when one comes online. */ static int tick_do_timer_boot_cpu __read_mostly = -1; #endif /* * 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(&jiffies_lock); /* Keep track of the next tick event */ tick_next_period = ktime_add(tick_next_period, tick_period); do_timer(1); write_sequnlock(&jiffies_lock); update_wall_time(); } 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 = dev->next_event; tick_periodic(cpu); #if defined(CONFIG_HIGH_RES_TIMERS) || defined(CONFIG_NO_HZ_COMMON) /* * The cpu might have transitioned to HIGHRES or NOHZ mode via * update_process_times() -> run_local_timers() -> * hrtimer_run_queues(). */ if (dev->event_handler != tick_handle_periodic) return; #endif if (!clockevent_state_oneshot(dev)) return; for (;;) { /* * Setup the next period for devices, which do not have * periodic mode: */ next = ktime_add(next, tick_period); if (!clockevents_program_event(dev, next, false)) 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, * which then will increment time, possibly causing * the loop to trigger again and again. */ if (timekeeping_valid_for_hres()) tick_periodic(cpu); } } /* * 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_switch_state(dev, CLOCK_EVT_STATE_PERIODIC); } else { unsigned int seq; ktime_t next; do { seq = read_seqbegin(&jiffies_lock); next = tick_next_period; } while (read_seqretry(&jiffies_lock, seq)); clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT); for (;;) { if (!clockevents_program_event(dev, next, false)) return; next = ktime_add(next, tick_period); } } } #ifdef CONFIG_NO_HZ_FULL static void giveup_do_timer(void *info) { int cpu = *(unsigned int *)info; WARN_ON(tick_do_timer_cpu != smp_processor_id()); tick_do_timer_cpu = cpu; } static void tick_take_do_timer_from_boot(void) { int cpu = smp_processor_id(); int from = tick_do_timer_boot_cpu; if (from >= 0 && from != cpu) smp_call_function_single(from, giveup_do_timer, &cpu, 1); } #endif /* * Setup the tick device */ static void tick_setup_device(struct tick_device *td, struct clock_event_device *newdev, int cpu, const struct cpumask *cpumask) { void (*handler)(struct clock_event_device *) = NULL; ktime_t next_event = 0; /* * 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 = NSEC_PER_SEC / HZ; #ifdef CONFIG_NO_HZ_FULL /* * The boot CPU may be nohz_full, in which case set * tick_do_timer_boot_cpu so the first housekeeping * secondary that comes up will take do_timer from * us. */ if (tick_nohz_full_cpu(cpu)) tick_do_timer_boot_cpu = cpu; } else if (tick_do_timer_boot_cpu != -1 && !tick_nohz_full_cpu(cpu)) { tick_take_do_timer_from_boot(); tick_do_timer_boot_cpu = -1; WARN_ON(tick_do_timer_cpu != cpu); #endif } /* * 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. This function also returns !=0 when we keep the * current active broadcast state for this CPU. */ 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); } void tick_install_replacement(struct clock_event_device *newdev) { struct tick_device *td = this_cpu_ptr(&tick_cpu_device); int cpu = smp_processor_id(); clockevents_exchange_device(td->evtdev, newdev); tick_setup_device(td, newdev, cpu, cpumask_of(cpu)); if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) tick_oneshot_notify(); } static bool tick_check_percpu(struct clock_event_device *curdev, struct clock_event_device *newdev, int cpu) { if (!cpumask_test_cpu(cpu, newdev->cpumask)) return false; if (cpumask_equal(newdev->cpumask, cpumask_of(cpu))) return true; /* Check if irq affinity can be set */ if (newdev->irq >= 0 && !irq_can_set_affinity(newdev->irq)) return false; /* Prefer an existing cpu local device */ if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu))) return false; return true; } static bool tick_check_preferred(struct clock_event_device *curdev, struct clock_event_device *newdev) { /* Prefer oneshot capable device */ if (!(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) { if (curdev && (curdev->features & CLOCK_EVT_FEAT_ONESHOT)) return false; if (tick_oneshot_mode_active()) return false; } /* * Use the higher rated one, but prefer a CPU local device with a lower * rating than a non-CPU local device */ return !curdev || newdev->rating > curdev->rating || !cpumask_equal(curdev->cpumask, newdev->cpumask); } /* * Check whether the new device is a better fit than curdev. curdev * can be NULL ! */ bool tick_check_replacement(struct clock_event_device *curdev, struct clock_event_device *newdev) { if (!tick_check_percpu(curdev, newdev, smp_processor_id())) return false; return tick_check_preferred(curdev, newdev); } /* * Check, if the new registered device should be used. Called with * clockevents_lock held and interrupts disabled. */ void tick_check_new_device(struct clock_event_device *newdev) { struct clock_event_device *curdev; struct tick_device *td; int cpu; cpu = smp_processor_id(); td = &per_cpu(tick_cpu_device, cpu); curdev = td->evtdev; /* cpu local device ? */ if (!tick_check_percpu(curdev, newdev, cpu)) goto out_bc; /* Preference decision */ if (!tick_check_preferred(curdev, newdev)) goto out_bc; if (!try_module_get(newdev->owner)) return; /* * 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(); return; out_bc: /* * Can the new device be used as a broadcast device ? */ tick_install_broadcast_device(newdev); } /** * tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode * @state: The target state (enter/exit) * * The system enters/leaves a state, where affected devices might stop * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups. * * Called with interrupts disabled, so clockevents_lock is not * required here because the local clock event device cannot go away * under us. */ int tick_broadcast_oneshot_control(enum tick_broadcast_state state) { struct tick_device *td = this_cpu_ptr(&tick_cpu_device); if (!(td->evtdev->features & CLOCK_EVT_FEAT_C3STOP)) return 0; return __tick_broadcast_oneshot_control(state); } EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control); #ifdef CONFIG_HOTPLUG_CPU /* * Transfer the do_timer job away from a dying cpu. * * Called with interrupts disabled. Not locking required. If * tick_do_timer_cpu is owned by this cpu, nothing can change it. */ void tick_handover_do_timer(void) { if (tick_do_timer_cpu == smp_processor_id()) { 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. */ void tick_shutdown(unsigned int cpu) { struct tick_device *td = &per_cpu(tick_cpu_device, cpu); struct clock_event_device *dev = td->evtdev; td->mode = TICKDEV_MODE_PERIODIC; if (dev) { /* * Prevent that the clock events layer tries to call * the set mode function! */ clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED); clockevents_exchange_device(dev, NULL); dev->event_handler = clockevents_handle_noop; td->evtdev = NULL; } } #endif /** * tick_suspend_local - Suspend the local tick device * * Called from the local cpu for freeze with interrupts disabled. * * No locks required. Nothing can change the per cpu device. */ void tick_suspend_local(void) { struct tick_device *td = this_cpu_ptr(&tick_cpu_device); clockevents_shutdown(td->evtdev); } /** * tick_resume_local - Resume the local tick device * * Called from the local CPU for unfreeze or XEN resume magic. * * No locks required. Nothing can change the per cpu device. */ void tick_resume_local(void) { struct tick_device *td = this_cpu_ptr(&tick_cpu_device); bool broadcast = tick_resume_check_broadcast(); clockevents_tick_resume(td->evtdev); if (!broadcast) { if (td->mode == TICKDEV_MODE_PERIODIC) tick_setup_periodic(td->evtdev, 0); else tick_resume_oneshot(); } } /** * tick_suspend - Suspend the tick and the broadcast device * * Called from syscore_suspend() via timekeeping_suspend with only one * CPU online and interrupts disabled or from tick_unfreeze() under * tick_freeze_lock. * * No locks required. Nothing can change the per cpu device. */ void tick_suspend(void) { tick_suspend_local(); tick_suspend_broadcast(); } /** * tick_resume - Resume the tick and the broadcast device * * Called from syscore_resume() via timekeeping_resume with only one * CPU online and interrupts disabled.