// SPDX-License-Identifier: GPL-2.0+/* * This file contains the functions which manage clocksource drivers. * * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/device.h>#include <linux/clocksource.h>#include <linux/init.h>#include <linux/module.h>#include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */#include <linux/tick.h>#include <linux/kthread.h> #include "tick-internal.h"#include "timekeeping_internal.h" /** * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks * @mult: pointer to mult variable * @shift: pointer to shift variable * @from: frequency to convert from * @to: frequency to convert to * @maxsec: guaranteed runtime conversion range in seconds * * The function evaluates the shift/mult pair for the scaled math * operations of clocksources and clockevents. * * @to and @from are frequency values in HZ. For clock sources @to is * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock * event @to is the counter frequency and @from is NSEC_PER_SEC. * * The @maxsec conversion range argument controls the time frame in * seconds which must be covered by the runtime conversion with the * calculated mult and shift factors. This guarantees that no 64bit * overflow happens when the input value of the conversion is * multiplied with the calculated mult factor. Larger ranges may * reduce the conversion accuracy by chosing smaller mult and shift * factors. */voidclocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec){ u64 tmp; u32 sft, sftacc= 32; /* * Calculate the shift factor which is limiting the conversion * range: */ tmp = ((u64)maxsec * from) >> 32; while (tmp) { tmp >>=1; sftacc--; } /* * Find the conversion shift/mult pair which has the best * accuracy and fits the maxsec conversion range: */ for (sft = 32; sft > 0; sft--) { tmp = (u64) to << sft; tmp += from / 2; do_div(tmp, from); if ((tmp >> sftacc) == 0) break; } *mult = tmp; *shift = sft;}EXPORT_SYMBOL_GPL(clocks_calc_mult_shift); /*[Clocksource internal variables]--------- * curr_clocksource: * currently selected clocksource. * suspend_clocksource: * used to calculate the suspend time. * clocksource_list: * linked list with the registered clocksources * clocksource_mutex: * protects manipulations to curr_clocksource and the clocksource_list * override_name: * Name of the user-specified clocksource. */static struct clocksource *curr_clocksource;static struct clocksource *suspend_clocksource;static LIST_HEAD(clocksource_list);static DEFINE_MUTEX(clocksource_mutex);static char override_name[CS_NAME_LEN];static int finished_booting;static u64 suspend_start; #ifdef CONFIG_CLOCKSOURCE_WATCHDOGstatic void clocksource_watchdog_work(struct work_struct *work);static void clocksource_select(void); static LIST_HEAD(watchdog_list);static struct clocksource *watchdog;static struct timer_list watchdog_timer;static DECLARE_WORK(watchdog_work, clocksource_watchdog_work);static DEFINE_SPINLOCK(watchdog_lock);static int watchdog_running;static atomic_t watchdog_reset_pending; static inline void clocksource_watchdog_lock(unsigned long *flags){ spin_lock_irqsave(&watchdog_lock, *flags);} static inline void clocksource_watchdog_unlock(unsigned long *flags){ spin_unlock_irqrestore(&watchdog_lock, *flags);} static int clocksource_watchdog_kthread(void *data);static void __clocksource_change_rating(struct clocksource *cs, int rating); /* * Interval: 0.5sec Threshold: 0.0625s */#define WATCHDOG_INTERVAL (HZ >> 1)#define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) static void clocksource_watchdog_work(struct work_struct *work){ /* * We cannot directly run clocksource_watchdog_kthread() here, because * clocksource_select() calls timekeeping_notify() which uses * stop_machine(). One cannot use stop_machine() from a workqueue() due * lock inversions wrt CPU hotplug. * * Also, we only ever run this work once or twice during the lifetime * of the kernel, so there is no point in creating a more permanent * kthread for this. * * If kthread_run fails the next watchdog scan over the * watchdog_list will find the unstable clock again. */ kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog");} static void __clocksource_unstable(struct clocksource *cs){ cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); cs->flags |= CLOCK_SOURCE_UNSTABLE; /* * If the clocksource is registered clocksource_watchdog_kthread() will * re-rate and re-select. */ if (list_empty(&cs->list)) { cs->rating = 0; return; } if (cs->mark_unstable) cs->mark_unstable(cs); /* kick clocksource_watchdog_kthread() */ if (finished_booting) schedule_work(&watchdog_work);} /** * clocksource_mark_unstable - mark clocksource unstable via watchdog * @cs: clocksource to be marked unstable * * This function is called by the x86 TSC code to mark clocksources as unstable; * it defers demotion and re-selection to a kthread. */void clocksource_mark_unstable(struct clocksource *cs){ unsigned long flags; spin_lock_irqsave(&watchdog_lock, flags); if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { if (!list_empty(&cs->list) && list_empty(&cs->wd_list)) list_add(&cs->wd_list, &watchdog_list); __clocksource_unstable(cs); } spin_unlock_irqrestore(&watchdog_lock, flags);} static void clocksource_watchdog(struct timer_list *unused){ struct clocksource *cs; u64 csnow, wdnow, cslast, wdlast, delta; int64_t wd_nsec, cs_nsec; int next_cpu, reset_pending; spin_lock(&watchdog_lock); if (!watchdog_running) goto out; reset_pending = atomic_read(&watchdog_reset_pending); list_for_each_entry(cs, &watchdog_list, wd_list) { /* Clocksource already marked unstable? */ if (cs->flags & CLOCK_SOURCE_UNSTABLE) { if (finished_booting) schedule_work(&watchdog_work); continue; } local_irq_disable(); csnow = cs->read(cs); wdnow = watchdog->read(watchdog); local_irq_enable(); /* Clocksource initialized ? */ if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || atomic_read(&watchdog_reset_pending)) { cs->flags |= CLOCK_SOURCE_WATCHDOG; cs->wd_last = wdnow; cs->cs_last = csnow; continue; } delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask); wd_nsec = clocksource_cyc2ns(delta, watchdog->mult, watchdog->shift); delta = clocksource_delta(csnow, cs->cs_last, cs->mask); cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); wdlast = cs->wd_last; /* save these in case we print them */ cslast = cs->cs_last; cs->cs_last = csnow; cs->wd_last = wdnow; if (atomic_read(&watchdog_reset_pending)) continue; /* Check the deviation from the watchdog clocksource. */ if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", smp_processor_id(), cs->name); pr_warn(" '%s' wd_now: %llx wd_last: %llx mask: %llx\n", watchdog->name, wdnow, wdlast, watchdog->mask); pr_warn(" '%s' cs_now: %llx cs_last: %llx mask: %llx\n", cs->name, csnow, cslast, cs->mask); __clocksource_unstable(cs); continue; } if (cs == curr_clocksource && cs->tick_stable) cs->tick_stable(cs); if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { /* Mark it valid for high-res. */ cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; /* * clocksource_done_booting() will sort it if * finished_booting is not set yet. */ if (!finished_booting) continue; /* * If this is not the current clocksource let * the watchdog thread reselect it. Due to the * change to high res this clocksource might * be preferred now. If it is the current * clocksource let the tick code know about * that change. */ if (cs != curr_clocksource) { cs->flags |= CLOCK_SOURCE_RESELECT; schedule_work(&watchdog_work); } else { tick_clock_notify(); } } } /* * We only clear the watchdog_reset_pending, when we did a * full cycle through all clocksources. */ if (reset_pending) atomic_dec(&watchdog_reset_pending); /* * Cycle through CPUs to check if the CPUs stay synchronized * to each other. */ next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); if (next_cpu >= nr_cpu_ids) next_cpu = cpumask_first(cpu_online_mask); /* * Arm timer if not already pending: could race with concurrent * pair clocksource_stop_watchdog() clocksource_start_watchdog(). */ if (!timer_pending(&watchdog_timer)) { watchdog_timer.expires += WATCHDOG_INTERVAL; add_timer_on(&watchdog_timer, next_cpu); }out: spin_unlock(&watchdog_lock);} static inline void clocksource_start_watchdog(void){ if (watchdog_running || !watchdog || list_empty(&watchdog_list)) return; timer_setup(&watchdog_timer, clocksource_watchdog, 0); watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); watchdog_running = 1;} static inline void clocksource_stop_watchdog(void){ if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) return; del_timer(&watchdog_timer); watchdog_running = 0;} static inline void clocksource_reset_watchdog(void){ struct clocksource *cs; list_for_each_entry(cs, &watchdog_list, wd_list) cs->flags &= ~CLOCK_SOURCE_WATCHDOG;} static void clocksource_resume_watchdog(void){ atomic_inc(&watchdog_reset_pending);} static void clocksource_enqueue_watchdog(struct clocksource *cs){ INIT_LIST_HEAD(&cs->wd_list); if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { /* cs is a clocksource to be watched. */ list_add(&cs->wd_list, &watchdog_list); cs->flags &= ~CLOCK_SOURCE_WATCHDOG; } else { /* cs is a watchdog. */ if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; }} static void clocksource_select_watchdog(bool fallback){ struct clocksource *cs, *old_wd; unsigned long flags; spin_lock_irqsave(&watchdog_lock, flags); /* save current watchdog */ old_wd = watchdog; if (fallback) watchdog = NULL; list_for_each_entry(cs, &clocksource_list, list) { /* cs is a clocksource to be watched. */ if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) continue; /* Skip current if we were requested for a fallback. */ if (fallback && cs == old_wd) continue; /* Pick the best watchdog. */ if (!watchdog || cs->rating > watchdog->rating) watchdog = cs; } /* If we failed to find a fallback restore the old one. */ if (!watchdog) watchdog = old_wd; /* If we changed the watchdog we need to reset cycles. */ if (watchdog != old_wd) clocksource_reset_watchdog(); /* Check if the watchdog timer needs to be started. */ clocksource_start_watchdog(); spin_unlock_irqrestore(&watchdog_lock, flags);} static void clocksource_dequeue_watchdog(struct clocksource *cs){ if (cs != watchdog) { if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { /* cs is a watched clocksource. */ list_del_init(&cs->wd_list); /* Check if the watchdog timer needs to be stopped. */ clocksource_stop_watchdog(); } }} static int __clocksource_watchdog_kthread(void){ struct clocksource *cs, *tmp; unsigned long flags; int select = 0; spin_lock_irqsave(&watchdog_lock, flags); list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { if (cs->flags & CLOCK_SOURCE_UNSTABLE) { list_del_init(&cs->wd_list); __clocksource_change_rating(cs, 0); select = 1; } if (cs->flags & CLOCK_SOURCE_RESELECT) { cs->flags &= ~CLOCK_SOURCE_RESELECT; select = 1; } } /* Check if the watchdog timer needs to be stopped. */ clocksource_stop_watchdog(); spin_unlock_irqrestore(&watchdog_lock, flags); return select;} static int clocksource_watchdog_kthread(void *data){ mutex_lock(&clocksource_mutex); if (__clocksource_watchdog_kthread()) clocksource_select(); mutex_unlock(&clocksource_mutex); return 0;} static bool clocksource_is_watchdog(struct clocksource *cs){ return cs == watchdog;} #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ static void clocksource_enqueue_watchdog(struct clocksource *cs){ if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;} static void clocksource_select_watchdog(bool fallback) { }static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }static inline void clocksource_resume_watchdog(void) { }static inline int __clocksource_watchdog_kthread(void) { return 0; }static bool clocksource_is_watchdog(struct clocksource *cs) { return false; }void clocksource_mark_unstable(struct clocksource *cs) { } static inline void clocksource_watchdog_lock(unsigned long *flags) { }static inline void clocksource_watchdog_unlock(unsigned long *flags) { } #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ static bool clocksource_is_suspend(struct clocksource *cs){ return cs == suspend_clocksource;} static void __clocksource_suspend_select(struct clocksource *cs){ /* * Skip the clocksource which will be stopped in suspend state. */ if (!(cs->flags & CLOCK_SOURCE_SUSPEND_NONSTOP)) return; /* * The nonstop clocksource can be selected as the suspend clocksource to * calculate the suspend time, so it should not supply suspend/resume * interfaces to suspend the nonstop clocksource when system suspends. */ if (cs->suspend || cs->resume) { pr_warn("Nonstop clocksource %s should not supply suspend/resume interfaces\n", cs->name); } /* Pick the best rating. */ if (!suspend_clocksource || cs->rating > suspend_clocksource->rating) suspend_clocksource = cs;} /** * clocksource_suspend_select - Select the best clocksource for suspend timing * @fallback: if select a fallback clocksource */static void clocksource_suspend_select(bool fallback){ struct clocksource *cs, *old_suspend; old_suspend = suspend_clocksource; if (fallback)Lines 1–500 of 1244. 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// SPDX-License-Identifier: GPL-2.0+ /* * This file contains the functions which manage clocksource drivers. * * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/device.h> #include <linux/clocksource.h> #include <linux/init.h> #include <linux/module.h> #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */ #include <linux/tick.h> #include <linux/kthread.h> #include "tick-internal.h" #include "timekeeping_internal.h" /** * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks * @mult: pointer to mult variable * @shift: pointer to shift variable * @from: frequency to convert from * @to: frequency to convert to * @maxsec: guaranteed runtime conversion range in seconds * * The function evaluates the shift/mult pair for the scaled math * operations of clocksources and clockevents. * * @to and @from are frequency values in HZ. For clock sources @to is * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock * event @to is the counter frequency and @from is NSEC_PER_SEC. * * The @maxsec conversion range argument controls the time frame in * seconds which must be covered by the runtime conversion with the * calculated mult and shift factors. This guarantees that no 64bit * overflow happens when the input value of the conversion is * multiplied with the calculated mult factor. Larger ranges may * reduce the conversion accuracy by chosing smaller mult and shift * factors. */ void clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec) { u64 tmp; u32 sft, sftacc= 32; /* * Calculate the shift factor which is limiting the conversion * range: */ tmp = ((u64)maxsec * from) >> 32; while (tmp) { tmp >>=1; sftacc--; } /* * Find the conversion shift/mult pair which has the best * accuracy and fits the maxsec conversion range: */ for (sft = 32; sft > 0; sft--) { tmp = (u64) to << sft; tmp += from / 2; do_div(tmp, from); if ((tmp >> sftacc) == 0) break; } *mult = tmp; *shift = sft; } EXPORT_SYMBOL_GPL(clocks_calc_mult_shift); /*[Clocksource internal variables]--------- * curr_clocksource: * currently selected clocksource. * suspend_clocksource: * used to calculate the suspend time. * clocksource_list: * linked list with the registered clocksources * clocksource_mutex: * protects manipulations to curr_clocksource and the clocksource_list * override_name: * Name of the user-specified clocksource. */ static struct clocksource *curr_clocksource; static struct clocksource *suspend_clocksource; static LIST_HEAD(clocksource_list); static DEFINE_MUTEX(clocksource_mutex); static char override_name[CS_NAME_LEN]; static int finished_booting; static u64 suspend_start; #ifdef CONFIG_CLOCKSOURCE_WATCHDOG static void clocksource_watchdog_work(struct work_struct *work); static void clocksource_select(void); static LIST_HEAD(watchdog_list); static struct clocksource *watchdog; static struct timer_list watchdog_timer; static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); static DEFINE_SPINLOCK(watchdog_lock); static int watchdog_running; static atomic_t watchdog_reset_pending; static inline void clocksource_watchdog_lock(unsigned long *flags) { spin_lock_irqsave(&watchdog_lock, *flags); } static inline void clocksource_watchdog_unlock(unsigned long *flags) { spin_unlock_irqrestore(&watchdog_lock, *flags); } static int clocksource_watchdog_kthread(void *data); static void __clocksource_change_rating(struct clocksource *cs, int rating); /* * Interval: 0.5sec Threshold: 0.0625s */ #define WATCHDOG_INTERVAL (HZ >> 1) #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) static void clocksource_watchdog_work(struct work_struct *work) { /* * We cannot directly run clocksource_watchdog_kthread() here, because * clocksource_select() calls timekeeping_notify() which uses * stop_machine(). One cannot use stop_machine() from a workqueue() due * lock inversions wrt CPU hotplug. * * Also, we only ever run this work once or twice during the lifetime * of the kernel, so there is no point in creating a more permanent * kthread for this. * * If kthread_run fails the next watchdog scan over the * watchdog_list will find the unstable clock again. */ kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); } static void __clocksource_unstable(struct clocksource *cs) { cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); cs->flags |= CLOCK_SOURCE_UNSTABLE; /* * If the clocksource is registered clocksource_watchdog_kthread() will * re-rate and re-select. */ if (list_empty(&cs->list)) { cs->rating = 0; return; } if (cs->mark_unstable) cs->mark_unstable(cs); /* kick clocksource_watchdog_kthread() */ if (finished_booting) schedule_work(&watchdog_work); } /** * clocksource_mark_unstable - mark clocksource unstable via watchdog * @cs: clocksource to be marked unstable * * This function is called by the x86 TSC code to mark clocksources as unstable; * it defers demotion and re-selection to a kthread. */ void clocksource_mark_unstable(struct clocksource *cs) { unsigned long flags; spin_lock_irqsave(&watchdog_lock, flags); if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { if (!list_empty(&cs->list) && list_empty(&cs->wd_list)) list_add(&cs->wd_list, &watchdog_list); __clocksource_unstable(cs); } spin_unlock_irqrestore(&watchdog_lock, flags); } static void clocksource_watchdog(struct timer_list *unused) { struct clocksource *cs; u64 csnow, wdnow, cslast, wdlast, delta; int64_t wd_nsec, cs_nsec; int next_cpu, reset_pending; spin_lock(&watchdog_lock); if (!watchdog_running) goto out; reset_pending = atomic_read(&watchdog_reset_pending); list_for_each_entry(cs, &watchdog_list, wd_list) { /* Clocksource already marked unstable? */ if (cs->flags & CLOCK_SOURCE_UNSTABLE) { if (finished_booting) schedule_work(&watchdog_work); continue; } local_irq_disable(); csnow = cs->read(cs); wdnow = watchdog->read(watchdog); local_irq_enable(); /* Clocksource initialized ? */ if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || atomic_read(&watchdog_reset_pending)) { cs->flags |= CLOCK_SOURCE_WATCHDOG; cs->wd_last = wdnow; cs->cs_last = csnow; continue; } delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask); wd_nsec = clocksource_cyc2ns(delta, watchdog->mult, watchdog->shift); delta = clocksource_delta(csnow, cs->cs_last, cs->mask); cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift); wdlast = cs->wd_last; /* save these in case we print them */ cslast = cs->cs_last; cs->cs_last = csnow; cs->wd_last = wdnow; if (atomic_read(&watchdog_reset_pending)) continue; /* Check the deviation from the watchdog clocksource. */ if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) { pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", smp_processor_id(), cs->name); pr_warn(" '%s' wd_now: %llx wd_last: %llx mask: %llx\n", watchdog->name, wdnow, wdlast, watchdog->mask); pr_warn(" '%s' cs_now: %llx cs_last: %llx mask: %llx\n", cs->name, csnow, cslast, cs->mask); __clocksource_unstable(cs); continue; } if (cs == curr_clocksource && cs->tick_stable) cs->tick_stable(cs); if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { /* Mark it valid for high-res. */ cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; /* * clocksource_done_booting() will sort it if * finished_booting is not set yet. */ if (!finished_booting) continue; /* * If this is not the current clocksource let * the watchdog thread reselect it. Due to the * change to high res this clocksource might * be preferred now. If it is the current * clocksource let the tick code know about * that change. */ if (cs != curr_clocksource) { cs->flags |= CLOCK_SOURCE_RESELECT; schedule_work(&watchdog_work); } else { tick_clock_notify(); } } } /* * We only clear the watchdog_reset_pending, when we did a * full cycle through all clocksources. */ if (reset_pending) atomic_dec(&watchdog_reset_pending); /* * Cycle through CPUs to check if the CPUs stay synchronized * to each other. */ next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); if (next_cpu >= nr_cpu_ids) next_cpu = cpumask_first(cpu_online_mask); /* * Arm timer if not already pending: could race with concurrent * pair clocksource_stop_watchdog() clocksource_start_watchdog(). */ if (!timer_pending(&watchdog_timer)) { watchdog_timer.expires += WATCHDOG_INTERVAL; add_timer_on(&watchdog_timer, next_cpu); } out: spin_unlock(&watchdog_lock); } static inline void clocksource_start_watchdog(void) { if (watchdog_running || !watchdog || list_empty(&watchdog_list)) return; timer_setup(&watchdog_timer, clocksource_watchdog, 0); watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); watchdog_running = 1; } static inline void clocksource_stop_watchdog(void) { if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) return; del_timer(&watchdog_timer); watchdog_running = 0; } static inline void clocksource_reset_watchdog(void) { struct clocksource *cs; list_for_each_entry(cs, &watchdog_list, wd_list) cs->flags &= ~CLOCK_SOURCE_WATCHDOG; } static void clocksource_resume_watchdog(void) { atomic_inc(&watchdog_reset_pending); } static void clocksource_enqueue_watchdog(struct clocksource *cs) { INIT_LIST_HEAD(&cs->wd_list); if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { /* cs is a clocksource to be watched. */ list_add(&cs->wd_list, &watchdog_list); cs->flags &= ~CLOCK_SOURCE_WATCHDOG; } else { /* cs is a watchdog. */ if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; } } static void clocksource_select_watchdog(bool fallback) { struct clocksource *cs, *old_wd; unsigned long flags; spin_lock_irqsave(&watchdog_lock, flags); /* save current watchdog */ old_wd = watchdog; if (fallback) watchdog = NULL; list_for_each_entry(cs, &clocksource_list, list) { /* cs is a clocksource to be watched. */ if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) continue; /* Skip current if we were requested for a fallback. */ if (fallback && cs == old_wd) continue; /* Pick the best watchdog. */ if (!watchdog || cs->rating > watchdog->rating) watchdog = cs; } /* If we failed to find a fallback restore the old one. */ if (!watchdog) watchdog = old_wd; /* If we changed the watchdog we need to reset cycles. */ if (watchdog != old_wd) clocksource_reset_watchdog(); /* Check if the watchdog timer needs to be started. */ clocksource_start_watchdog(); spin_unlock_irqrestore(&watchdog_lock, flags); } static void clocksource_dequeue_watchdog(struct clocksource *cs) { if (cs != watchdog) { if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { /* cs is a watched clocksource. */ list_del_init(&cs->wd_list); /* Check if the watchdog timer needs to be stopped. */ clocksource_stop_watchdog(); } } } static int __clocksource_watchdog_kthread(void) { struct clocksource *cs, *tmp; unsigned long flags; int select = 0; spin_lock_irqsave(&watchdog_lock, flags); list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { if (cs->flags & CLOCK_SOURCE_UNSTABLE) { list_del_init(&cs->wd_list); __clocksource_change_rating(cs, 0); select = 1; } if (cs->flags & CLOCK_SOURCE_RESELECT) { cs->flags &= ~CLOCK_SOURCE_RESELECT; select = 1; } } /* Check if the watchdog timer needs to be stopped. */ clocksource_stop_watchdog(); spin_unlock_irqrestore(&watchdog_lock, flags); return select; } static int clocksource_watchdog_kthread(void *data) { mutex_lock(&clocksource_mutex); if (__clocksource_watchdog_kthread()) clocksource_select(); mutex_unlock(&clocksource_mutex); return 0; } static bool clocksource_is_watchdog(struct clocksource *cs) { return cs == watchdog; } #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ static void clocksource_enqueue_watchdog(struct clocksource *cs) { if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; } static void clocksource_select_watchdog(bool fallback) { } static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } static inline void clocksource_resume_watchdog(void) { } static inline int __clocksource_watchdog_kthread(void) { return 0; } static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } void clocksource_mark_unstable(struct clocksource *cs) { } static inline void clocksource_watchdog_lock(unsigned long *flags) { } static inline void clocksource_watchdog_unlock(unsigned long *flags) { } #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ static bool clocksource_is_suspend(struct clocksource *cs) { return cs == suspend_clocksource; } static void __clocksource_suspend_select(struct clocksource *cs) { /* * Skip the clocksource which will be stopped in suspend state. */ if (!(cs->flags & CLOCK_SOURCE_SUSPEND_NONSTOP)) return; /* * The nonstop clocksource can be selected as the suspend clocksource to * calculate the suspend time, so it should not supply suspend/resume * interfaces to suspend the nonstop clocksource when system suspends. */ if (cs->suspend || cs->resume) { pr_warn("Nonstop clocksource %s should not supply suspend/resume interfaces\n", cs->name); } /* Pick the best rating. */ if (!suspend_clocksource || cs->rating > suspend_clocksource->rating) suspend_clocksource = cs; } /** * clocksource_suspend_select - Select the best clocksource for suspend timing * @fallback: if select a fallback clocksource */ static void clocksource_suspend_select(bool fallback) { struct clocksource *cs, *old_suspend; old_suspend = suspend_clocksource; if (fallback)