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kernel/time/clocksource.c
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/* * linux/kernel/time/clocksource.c * * This file contains the functions which manage clocksource drivers. * * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * TODO WishList: * o Allow clocksource drivers to be unregistered |
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*/ |
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#include <linux/device.h> |
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#include <linux/clocksource.h> |
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#include <linux/init.h> #include <linux/module.h> |
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#include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */ |
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#include <linux/tick.h> |
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#include <linux/kthread.h> |
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|
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void timecounter_init(struct timecounter *tc, const struct cyclecounter *cc, u64 start_tstamp) { tc->cc = cc; tc->cycle_last = cc->read(cc); tc->nsec = start_tstamp; } |
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EXPORT_SYMBOL_GPL(timecounter_init); |
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/** * timecounter_read_delta - get nanoseconds since last call of this function * @tc: Pointer to time counter * * When the underlying cycle counter runs over, this will be handled * correctly as long as it does not run over more than once between * calls. * * The first call to this function for a new time counter initializes * the time tracking and returns an undefined result. */ static u64 timecounter_read_delta(struct timecounter *tc) { cycle_t cycle_now, cycle_delta; u64 ns_offset; /* read cycle counter: */ cycle_now = tc->cc->read(tc->cc); /* calculate the delta since the last timecounter_read_delta(): */ cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask; /* convert to nanoseconds: */ ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta); /* update time stamp of timecounter_read_delta() call: */ tc->cycle_last = cycle_now; return ns_offset; } u64 timecounter_read(struct timecounter *tc) { u64 nsec; /* increment time by nanoseconds since last call */ nsec = timecounter_read_delta(tc); nsec += tc->nsec; tc->nsec = nsec; return nsec; } |
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EXPORT_SYMBOL_GPL(timecounter_read); |
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u64 timecounter_cyc2time(struct timecounter *tc, cycle_t cycle_tstamp) { u64 cycle_delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask; u64 nsec; /* * Instead of always treating cycle_tstamp as more recent * than tc->cycle_last, detect when it is too far in the * future and treat it as old time stamp instead. */ if (cycle_delta > tc->cc->mask / 2) { cycle_delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask; nsec = tc->nsec - cyclecounter_cyc2ns(tc->cc, cycle_delta); } else { nsec = cyclecounter_cyc2ns(tc->cc, cycle_delta) + tc->nsec; } return nsec; } |
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EXPORT_SYMBOL_GPL(timecounter_cyc2time); |
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|
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/** * 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 |
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* @maxsec: guaranteed runtime conversion range in seconds |
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* * 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. * |
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* The @maxsec conversion range argument controls the time frame in |
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* 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 |
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clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec) |
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{ u64 tmp; u32 sft, sftacc= 32; /* * Calculate the shift factor which is limiting the conversion * range: */ |
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tmp = ((u64)maxsec * from) >> 32; |
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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; |
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tmp += from / 2; |
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do_div(tmp, from); if ((tmp >> sftacc) == 0) break; } *mult = tmp; *shift = sft; } |
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/*[Clocksource internal variables]--------- * curr_clocksource: |
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* currently selected clocksource. |
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* clocksource_list: * linked list with the registered clocksources |
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* clocksource_mutex: * protects manipulations to curr_clocksource and the clocksource_list |
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* override_name: * Name of the user-specified clocksource. */ |
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static struct clocksource *curr_clocksource; |
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static LIST_HEAD(clocksource_list); |
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static DEFINE_MUTEX(clocksource_mutex); |
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static char override_name[32]; |
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static int finished_booting; |
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|
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#ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
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static void clocksource_watchdog_work(struct work_struct *work); |
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static LIST_HEAD(watchdog_list); static struct clocksource *watchdog; static struct timer_list watchdog_timer; |
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static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
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static DEFINE_SPINLOCK(watchdog_lock); |
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static int watchdog_running; |
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static atomic_t watchdog_reset_pending; |
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|
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static int clocksource_watchdog_kthread(void *data); |
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static void __clocksource_change_rating(struct clocksource *cs, int rating); |
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|
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/* |
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* Interval: 0.5sec Threshold: 0.0625s |
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*/ #define WATCHDOG_INTERVAL (HZ >> 1) |
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#define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
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|
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static void clocksource_watchdog_work(struct work_struct *work) { /* * 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"); } |
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static void __clocksource_unstable(struct clocksource *cs) |
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{ |
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cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
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cs->flags |= CLOCK_SOURCE_UNSTABLE; |
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if (finished_booting) schedule_work(&watchdog_work); |
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} |
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static void clocksource_unstable(struct clocksource *cs, int64_t delta) { printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns) ", cs->name, delta); __clocksource_unstable(cs); } /** * clocksource_mark_unstable - mark clocksource unstable via watchdog * @cs: clocksource to be marked unstable * * This function is called instead of clocksource_change_rating from * cpu hotplug code to avoid a deadlock between the clocksource mutex * and the cpu hotplug mutex. It defers the update of the clocksource * to the watchdog thread. */ 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->wd_list)) list_add(&cs->wd_list, &watchdog_list); __clocksource_unstable(cs); } spin_unlock_irqrestore(&watchdog_lock, flags); } |
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static void clocksource_watchdog(unsigned long data) { |
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struct clocksource *cs; |
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cycle_t csnow, wdnow; int64_t wd_nsec, cs_nsec; |
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int next_cpu, reset_pending; |
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spin_lock(&watchdog_lock); |
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if (!watchdog_running) goto out; |
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|
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reset_pending = atomic_read(&watchdog_reset_pending); |
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list_for_each_entry(cs, &watchdog_list, wd_list) { /* Clocksource already marked unstable? */ |
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if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
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if (finished_booting) schedule_work(&watchdog_work); |
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continue; |
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} |
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local_irq_disable(); |
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csnow = cs->read(cs); |
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wdnow = watchdog->read(watchdog); local_irq_enable(); |
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|
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/* Clocksource initialized ? */ |
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if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || atomic_read(&watchdog_reset_pending)) { |
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cs->flags |= CLOCK_SOURCE_WATCHDOG; |
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cs->wd_last = wdnow; cs->cs_last = csnow; |
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continue; } |
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wd_nsec = clocksource_cyc2ns((wdnow - cs->wd_last) & watchdog->mask, watchdog->mult, watchdog->shift); cs_nsec = clocksource_cyc2ns((csnow - cs->cs_last) & |
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cs->mask, cs->mult, cs->shift); |
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cs->cs_last = csnow; cs->wd_last = wdnow; |
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if (atomic_read(&watchdog_reset_pending)) continue; |
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/* Check the deviation from the watchdog clocksource. */ |
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if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) { |
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clocksource_unstable(cs, cs_nsec - wd_nsec); continue; } if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; /* * We just marked the clocksource as highres-capable, * notify the rest of the system as well so that we * transition into high-res mode: */ tick_clock_notify(); |
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} } |
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/* |
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* We only clear the watchdog_reset_pending, when we did a * full cycle through all clocksources. */ if (reset_pending) atomic_dec(&watchdog_reset_pending); /* |
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* 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); watchdog_timer.expires += WATCHDOG_INTERVAL; add_timer_on(&watchdog_timer, next_cpu); |
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out: |
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spin_unlock(&watchdog_lock); } |
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|
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static inline void clocksource_start_watchdog(void) { if (watchdog_running || !watchdog || list_empty(&watchdog_list)) return; init_timer(&watchdog_timer); watchdog_timer.function = clocksource_watchdog; |
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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; } |
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static inline void clocksource_reset_watchdog(void) { struct clocksource *cs; list_for_each_entry(cs, &watchdog_list, wd_list) cs->flags &= ~CLOCK_SOURCE_WATCHDOG; } |
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static void clocksource_resume_watchdog(void) { |
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atomic_inc(&watchdog_reset_pending); |
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} |
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static void clocksource_enqueue_watchdog(struct clocksource *cs) |
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{ |
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unsigned long flags; spin_lock_irqsave(&watchdog_lock, flags); if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { |
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/* cs is a clocksource to be watched. */ |
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list_add(&cs->wd_list, &watchdog_list); |
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cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
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} else { |
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/* cs is a watchdog. */ |
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if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
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cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
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/* Pick the best watchdog. */ |
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if (!watchdog || cs->rating > watchdog->rating) { |
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watchdog = cs; |
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/* Reset watchdog cycles */ |
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clocksource_reset_watchdog(); |
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} } |
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/* Check if the watchdog timer needs to be started. */ clocksource_start_watchdog(); |
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spin_unlock_irqrestore(&watchdog_lock, flags); } |
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static void clocksource_dequeue_watchdog(struct clocksource *cs) { struct clocksource *tmp; unsigned long flags; spin_lock_irqsave(&watchdog_lock, flags); if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { /* cs is a watched clocksource. */ list_del_init(&cs->wd_list); } else if (cs == watchdog) { /* Reset watchdog cycles */ clocksource_reset_watchdog(); /* Current watchdog is removed. Find an alternative. */ watchdog = NULL; list_for_each_entry(tmp, &clocksource_list, list) { if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY) continue; if (!watchdog || tmp->rating > watchdog->rating) watchdog = tmp; } } cs->flags &= ~CLOCK_SOURCE_WATCHDOG; /* Check if the watchdog timer needs to be stopped. */ clocksource_stop_watchdog(); spin_unlock_irqrestore(&watchdog_lock, flags); } |
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static int clocksource_watchdog_kthread(void *data) |
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{ struct clocksource *cs, *tmp; unsigned long flags; |
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LIST_HEAD(unstable); |
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|
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mutex_lock(&clocksource_mutex); |
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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); |
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list_add(&cs->wd_list, &unstable); |
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} /* Check if the watchdog timer needs to be stopped. */ clocksource_stop_watchdog(); |
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spin_unlock_irqrestore(&watchdog_lock, flags); /* Needs to be done outside of watchdog lock */ list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { list_del_init(&cs->wd_list); |
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__clocksource_change_rating(cs, 0); |
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} |
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mutex_unlock(&clocksource_mutex); |
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return 0; |
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} |
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#else /* CONFIG_CLOCKSOURCE_WATCHDOG */ static void clocksource_enqueue_watchdog(struct clocksource *cs) |
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{ if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; } |
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static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
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static inline void clocksource_resume_watchdog(void) { } |
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static inline int clocksource_watchdog_kthread(void *data) { return 0; } |
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#endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
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|
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/** |
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* clocksource_suspend - suspend the clocksource(s) */ void clocksource_suspend(void) { struct clocksource *cs; list_for_each_entry_reverse(cs, &clocksource_list, list) if (cs->suspend) cs->suspend(cs); } /** |
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* clocksource_resume - resume the clocksource(s) */ void clocksource_resume(void) { |
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struct clocksource *cs; |
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|
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list_for_each_entry(cs, &clocksource_list, list) |
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if (cs->resume) |
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cs->resume(cs); |
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clocksource_resume_watchdog(); |
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} /** |
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* clocksource_touch_watchdog - Update watchdog * * Update the watchdog after exception contexts such as kgdb so as not |
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* to incorrectly trip the watchdog. This might fail when the kernel * was stopped in code which holds watchdog_lock. |
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*/ void clocksource_touch_watchdog(void) { clocksource_resume_watchdog(); } |
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/** |
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* clocksource_max_adjustment- Returns max adjustment amount * @cs: Pointer to clocksource * */ static u32 clocksource_max_adjustment(struct clocksource *cs) { u64 ret; /* * We won't try to correct for more then 11% adjustments (110,000 ppm), */ ret = (u64)cs->mult * 11; do_div(ret,100); return (u32)ret; } /** |
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* clocksource_max_deferment - Returns max time the clocksource can be deferred * @cs: Pointer to clocksource * */ static u64 clocksource_max_deferment(struct clocksource *cs) { u64 max_nsecs, max_cycles; /* * Calculate the maximum number of cycles that we can pass to the * cyc2ns function without overflowing a 64-bit signed result. The |
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* maximum number of cycles is equal to ULLONG_MAX/(cs->mult+cs->maxadj) * which is equivalent to the below. * max_cycles < (2^63)/(cs->mult + cs->maxadj) * max_cycles < 2^(log2((2^63)/(cs->mult + cs->maxadj))) * max_cycles < 2^(log2(2^63) - log2(cs->mult + cs->maxadj)) * max_cycles < 2^(63 - log2(cs->mult + cs->maxadj)) * max_cycles < 1 << (63 - log2(cs->mult + cs->maxadj)) |
98962465e nohz: Prevent clo... |
513 514 515 516 |
* Please note that we add 1 to the result of the log2 to account for * any rounding errors, ensure the above inequality is satisfied and * no overflow will occur. */ |
d65670a78 clocksource: Avoi... |
517 |
max_cycles = 1ULL << (63 - (ilog2(cs->mult + cs->maxadj) + 1)); |
98962465e nohz: Prevent clo... |
518 519 520 521 |
/* * The actual maximum number of cycles we can defer the clocksource is * determined by the minimum of max_cycles and cs->mask. |
d65670a78 clocksource: Avoi... |
522 523 |
* Note: Here we subtract the maxadj to make sure we don't sleep for * too long if there's a large negative adjustment. |
98962465e nohz: Prevent clo... |
524 525 |
*/ max_cycles = min_t(u64, max_cycles, (u64) cs->mask); |
d65670a78 clocksource: Avoi... |
526 527 |
max_nsecs = clocksource_cyc2ns(max_cycles, cs->mult - cs->maxadj, cs->shift); |
98962465e nohz: Prevent clo... |
528 529 530 531 532 533 534 |
/* * To ensure that the clocksource does not wrap whilst we are idle, * limit the time the clocksource can be deferred by 12.5%. Please * note a margin of 12.5% is used because this can be computed with * a shift, versus say 10% which would require division. */ |
b1f919664 clocksource: Fix ... |
535 |
return max_nsecs - (max_nsecs >> 3); |
98962465e nohz: Prevent clo... |
536 |
} |
592913ecb time: Kill off CO... |
537 |
#ifndef CONFIG_ARCH_USES_GETTIMEOFFSET |
734efb467 [PATCH] Time: Clo... |
538 |
|
734efb467 [PATCH] Time: Clo... |
539 |
/** |
f1b82746c clocksource: Clea... |
540 |
* clocksource_select - Select the best clocksource available |
734efb467 [PATCH] Time: Clo... |
541 |
* |
75c5158f7 timekeeping: Upda... |
542 |
* Private function. Must hold clocksource_mutex when called. |
734efb467 [PATCH] Time: Clo... |
543 |
* |
92c7e0025 [PATCH] Simplify ... |
544 545 |
* Select the clocksource with the best rating, or the clocksource, * which is selected by userspace override. |
734efb467 [PATCH] Time: Clo... |
546 |
*/ |
f1b82746c clocksource: Clea... |
547 |
static void clocksource_select(void) |
734efb467 [PATCH] Time: Clo... |
548 |
{ |
f1b82746c clocksource: Clea... |
549 |
struct clocksource *best, *cs; |
5d8b34fdc [PATCH] clocksour... |
550 |
|
75c5158f7 timekeeping: Upda... |
551 |
if (!finished_booting || list_empty(&clocksource_list)) |
f1b82746c clocksource: Clea... |
552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 |
return; /* First clocksource on the list has the best rating. */ best = list_first_entry(&clocksource_list, struct clocksource, list); /* Check for the override clocksource. */ list_for_each_entry(cs, &clocksource_list, list) { if (strcmp(cs->name, override_name) != 0) continue; /* * Check to make sure we don't switch to a non-highres * capable clocksource if the tick code is in oneshot * mode (highres or nohz) */ if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && tick_oneshot_mode_active()) { /* Override clocksource cannot be used. */ printk(KERN_WARNING "Override clocksource %s is not " "HRT compatible. Cannot switch while in " "HRT/NOHZ mode ", cs->name); override_name[0] = 0; } else /* Override clocksource can be used. */ best = cs; break; } |
75c5158f7 timekeeping: Upda... |
577 578 579 580 581 582 |
if (curr_clocksource != best) { printk(KERN_INFO "Switching to clocksource %s ", best->name); curr_clocksource = best; timekeeping_notify(curr_clocksource); } |
f1b82746c clocksource: Clea... |
583 |
} |
734efb467 [PATCH] Time: Clo... |
584 |
|
592913ecb time: Kill off CO... |
585 |
#else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */ |
54a6bc0b0 clocksource: Dela... |
586 587 588 589 |
static inline void clocksource_select(void) { } #endif |
75c5158f7 timekeeping: Upda... |
590 591 592 593 594 595 596 597 598 |
/* * clocksource_done_booting - Called near the end of core bootup * * Hack to avoid lots of clocksource churn at boot time. * We use fs_initcall because we want this to start before * device_initcall but after subsys_initcall. */ static int __init clocksource_done_booting(void) { |
ad6759fbf timekeeping: Prev... |
599 600 601 |
mutex_lock(&clocksource_mutex); curr_clocksource = clocksource_default_clock(); mutex_unlock(&clocksource_mutex); |
75c5158f7 timekeeping: Upda... |
602 |
finished_booting = 1; |
54a6bc0b0 clocksource: Dela... |
603 604 605 606 607 |
/* * Run the watchdog first to eliminate unstable clock sources */ clocksource_watchdog_kthread(NULL); |
e6c733050 clocksource: cloc... |
608 |
mutex_lock(&clocksource_mutex); |
75c5158f7 timekeeping: Upda... |
609 |
clocksource_select(); |
e6c733050 clocksource: cloc... |
610 |
mutex_unlock(&clocksource_mutex); |
75c5158f7 timekeeping: Upda... |
611 612 613 |
return 0; } fs_initcall(clocksource_done_booting); |
92c7e0025 [PATCH] Simplify ... |
614 615 |
/* * Enqueue the clocksource sorted by rating |
734efb467 [PATCH] Time: Clo... |
616 |
*/ |
f1b82746c clocksource: Clea... |
617 |
static void clocksource_enqueue(struct clocksource *cs) |
734efb467 [PATCH] Time: Clo... |
618 |
{ |
f1b82746c clocksource: Clea... |
619 620 |
struct list_head *entry = &clocksource_list; struct clocksource *tmp; |
92c7e0025 [PATCH] Simplify ... |
621 |
|
f1b82746c clocksource: Clea... |
622 |
list_for_each_entry(tmp, &clocksource_list, list) |
92c7e0025 [PATCH] Simplify ... |
623 |
/* Keep track of the place, where to insert */ |
f1b82746c clocksource: Clea... |
624 625 626 |
if (tmp->rating >= cs->rating) entry = &tmp->list; list_add(&cs->list, entry); |
734efb467 [PATCH] Time: Clo... |
627 |
} |
d7e81c269 clocksource: Add ... |
628 |
/** |
852db46d5 clocksource: Add ... |
629 |
* __clocksource_updatefreq_scale - Used update clocksource with new freq |
b1b73d095 time/clocksource:... |
630 |
* @cs: clocksource to be registered |
d7e81c269 clocksource: Add ... |
631 632 633 |
* @scale: Scale factor multiplied against freq to get clocksource hz * @freq: clocksource frequency (cycles per second) divided by scale * |
852db46d5 clocksource: Add ... |
634 |
* This should only be called from the clocksource->enable() method. |
d7e81c269 clocksource: Add ... |
635 636 |
* * This *SHOULD NOT* be called directly! Please use the |
852db46d5 clocksource: Add ... |
637 |
* clocksource_updatefreq_hz() or clocksource_updatefreq_khz helper functions. |
d7e81c269 clocksource: Add ... |
638 |
*/ |
852db46d5 clocksource: Add ... |
639 |
void __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq) |
d7e81c269 clocksource: Add ... |
640 |
{ |
c0e299b1a clockevents/sourc... |
641 |
u64 sec; |
d7e81c269 clocksource: Add ... |
642 |
/* |
724ed53e8 clocksource: Get ... |
643 644 645 646 647 648 649 650 |
* Calc the maximum number of seconds which we can run before * wrapping around. For clocksources which have a mask > 32bit * we need to limit the max sleep time to have a good * conversion precision. 10 minutes is still a reasonable * amount. That results in a shift value of 24 for a * clocksource with mask >= 40bit and f >= 4GHz. That maps to * ~ 0.06ppm granularity for NTP. We apply the same 12.5% * margin as we do in clocksource_max_deferment() |
d7e81c269 clocksource: Add ... |
651 |
*/ |
b1f919664 clocksource: Fix ... |
652 |
sec = (cs->mask - (cs->mask >> 3)); |
724ed53e8 clocksource: Get ... |
653 654 655 656 657 658 |
do_div(sec, freq); do_div(sec, scale); if (!sec) sec = 1; else if (sec > 600 && cs->mask > UINT_MAX) sec = 600; |
d7e81c269 clocksource: Add ... |
659 |
clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, |
724ed53e8 clocksource: Get ... |
660 |
NSEC_PER_SEC / scale, sec * scale); |
d65670a78 clocksource: Avoi... |
661 662 663 664 665 666 667 668 669 670 671 672 673 |
/* * for clocksources that have large mults, to avoid overflow. * Since mult may be adjusted by ntp, add an safety extra margin * */ cs->maxadj = clocksource_max_adjustment(cs); while ((cs->mult + cs->maxadj < cs->mult) || (cs->mult - cs->maxadj > cs->mult)) { cs->mult >>= 1; cs->shift--; cs->maxadj = clocksource_max_adjustment(cs); } |
d7e81c269 clocksource: Add ... |
674 |
cs->max_idle_ns = clocksource_max_deferment(cs); |
852db46d5 clocksource: Add ... |
675 676 677 678 679 |
} EXPORT_SYMBOL_GPL(__clocksource_updatefreq_scale); /** * __clocksource_register_scale - Used to install new clocksources |
b1b73d095 time/clocksource:... |
680 |
* @cs: clocksource to be registered |
852db46d5 clocksource: Add ... |
681 682 683 684 685 686 687 688 689 690 |
* @scale: Scale factor multiplied against freq to get clocksource hz * @freq: clocksource frequency (cycles per second) divided by scale * * Returns -EBUSY if registration fails, zero otherwise. * * This *SHOULD NOT* be called directly! Please use the * clocksource_register_hz() or clocksource_register_khz helper functions. */ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) { |
b595076a1 tree-wide: fix co... |
691 |
/* Initialize mult/shift and max_idle_ns */ |
852db46d5 clocksource: Add ... |
692 |
__clocksource_updatefreq_scale(cs, scale, freq); |
d7e81c269 clocksource: Add ... |
693 |
|
852db46d5 clocksource: Add ... |
694 |
/* Add clocksource to the clcoksource list */ |
d7e81c269 clocksource: Add ... |
695 696 |
mutex_lock(&clocksource_mutex); clocksource_enqueue(cs); |
d7e81c269 clocksource: Add ... |
697 |
clocksource_enqueue_watchdog(cs); |
e05b2efb8 clocksource: Inst... |
698 |
clocksource_select(); |
d7e81c269 clocksource: Add ... |
699 700 701 702 |
mutex_unlock(&clocksource_mutex); return 0; } EXPORT_SYMBOL_GPL(__clocksource_register_scale); |
734efb467 [PATCH] Time: Clo... |
703 |
/** |
a27525497 [PATCH] time: ren... |
704 |
* clocksource_register - Used to install new clocksources |
b1b73d095 time/clocksource:... |
705 |
* @cs: clocksource to be registered |
734efb467 [PATCH] Time: Clo... |
706 707 708 |
* * Returns -EBUSY if registration fails, zero otherwise. */ |
f1b82746c clocksource: Clea... |
709 |
int clocksource_register(struct clocksource *cs) |
734efb467 [PATCH] Time: Clo... |
710 |
{ |
d65670a78 clocksource: Avoi... |
711 712 713 714 715 716 |
/* calculate max adjustment for given mult/shift */ cs->maxadj = clocksource_max_adjustment(cs); WARN_ONCE(cs->mult + cs->maxadj < cs->mult, "Clocksource %s might overflow on 11%% adjustment ", cs->name); |
98962465e nohz: Prevent clo... |
717 718 |
/* calculate max idle time permitted for this clocksource */ cs->max_idle_ns = clocksource_max_deferment(cs); |
75c5158f7 timekeeping: Upda... |
719 |
mutex_lock(&clocksource_mutex); |
f1b82746c clocksource: Clea... |
720 |
clocksource_enqueue(cs); |
fb63a0ebe clocksource: Refa... |
721 |
clocksource_enqueue_watchdog(cs); |
e05b2efb8 clocksource: Inst... |
722 |
clocksource_select(); |
75c5158f7 timekeeping: Upda... |
723 |
mutex_unlock(&clocksource_mutex); |
f1b82746c clocksource: Clea... |
724 |
return 0; |
734efb467 [PATCH] Time: Clo... |
725 |
} |
a27525497 [PATCH] time: ren... |
726 |
EXPORT_SYMBOL(clocksource_register); |
734efb467 [PATCH] Time: Clo... |
727 |
|
d0981a1b2 clocksource: Prot... |
728 729 730 731 732 733 734 |
static void __clocksource_change_rating(struct clocksource *cs, int rating) { list_del(&cs->list); cs->rating = rating; clocksource_enqueue(cs); clocksource_select(); } |
734efb467 [PATCH] Time: Clo... |
735 |
/** |
92c7e0025 [PATCH] Simplify ... |
736 |
* clocksource_change_rating - Change the rating of a registered clocksource |
b1b73d095 time/clocksource:... |
737 738 |
* @cs: clocksource to be changed * @rating: new rating |
734efb467 [PATCH] Time: Clo... |
739 |
*/ |
92c7e0025 [PATCH] Simplify ... |
740 |
void clocksource_change_rating(struct clocksource *cs, int rating) |
734efb467 [PATCH] Time: Clo... |
741 |
{ |
75c5158f7 timekeeping: Upda... |
742 |
mutex_lock(&clocksource_mutex); |
d0981a1b2 clocksource: Prot... |
743 |
__clocksource_change_rating(cs, rating); |
75c5158f7 timekeeping: Upda... |
744 |
mutex_unlock(&clocksource_mutex); |
734efb467 [PATCH] Time: Clo... |
745 |
} |
fb63a0ebe clocksource: Refa... |
746 |
EXPORT_SYMBOL(clocksource_change_rating); |
734efb467 [PATCH] Time: Clo... |
747 |
|
4713e22ce clocksource: add ... |
748 749 |
/** * clocksource_unregister - remove a registered clocksource |
b1b73d095 time/clocksource:... |
750 |
* @cs: clocksource to be unregistered |
4713e22ce clocksource: add ... |
751 752 753 |
*/ void clocksource_unregister(struct clocksource *cs) { |
75c5158f7 timekeeping: Upda... |
754 |
mutex_lock(&clocksource_mutex); |
fb63a0ebe clocksource: Refa... |
755 |
clocksource_dequeue_watchdog(cs); |
4713e22ce clocksource: add ... |
756 |
list_del(&cs->list); |
f1b82746c clocksource: Clea... |
757 |
clocksource_select(); |
75c5158f7 timekeeping: Upda... |
758 |
mutex_unlock(&clocksource_mutex); |
4713e22ce clocksource: add ... |
759 |
} |
fb63a0ebe clocksource: Refa... |
760 |
EXPORT_SYMBOL(clocksource_unregister); |
4713e22ce clocksource: add ... |
761 |
|
2b0137001 [PATCH] clocksour... |
762 |
#ifdef CONFIG_SYSFS |
734efb467 [PATCH] Time: Clo... |
763 764 765 |
/** * sysfs_show_current_clocksources - sysfs interface for current clocksource * @dev: unused |
b1b73d095 time/clocksource:... |
766 |
* @attr: unused |
734efb467 [PATCH] Time: Clo... |
767 768 769 770 771 |
* @buf: char buffer to be filled with clocksource list * * Provides sysfs interface for listing current clocksource. */ static ssize_t |
d369a5d8f clocksource: conv... |
772 773 |
sysfs_show_current_clocksources(struct device *dev, struct device_attribute *attr, char *buf) |
734efb467 [PATCH] Time: Clo... |
774 |
{ |
5e2cb1018 time: fix sysfs_s... |
775 |
ssize_t count = 0; |
734efb467 [PATCH] Time: Clo... |
776 |
|
75c5158f7 timekeeping: Upda... |
777 |
mutex_lock(&clocksource_mutex); |
5e2cb1018 time: fix sysfs_s... |
778 779 |
count = snprintf(buf, PAGE_SIZE, "%s ", curr_clocksource->name); |
75c5158f7 timekeeping: Upda... |
780 |
mutex_unlock(&clocksource_mutex); |
734efb467 [PATCH] Time: Clo... |
781 |
|
5e2cb1018 time: fix sysfs_s... |
782 |
return count; |
734efb467 [PATCH] Time: Clo... |
783 784 785 786 787 |
} /** * sysfs_override_clocksource - interface for manually overriding clocksource * @dev: unused |
b1b73d095 time/clocksource:... |
788 |
* @attr: unused |
734efb467 [PATCH] Time: Clo... |
789 790 791 792 |
* @buf: name of override clocksource * @count: length of buffer * * Takes input from sysfs interface for manually overriding the default |
b71a8eb0f tree-wide: fix ty... |
793 |
* clocksource selection. |
734efb467 [PATCH] Time: Clo... |
794 |
*/ |
d369a5d8f clocksource: conv... |
795 796 |
static ssize_t sysfs_override_clocksource(struct device *dev, struct device_attribute *attr, |
734efb467 [PATCH] Time: Clo... |
797 798 799 |
const char *buf, size_t count) { size_t ret = count; |
92c7e0025 [PATCH] Simplify ... |
800 |
|
734efb467 [PATCH] Time: Clo... |
801 802 803 804 805 806 807 808 809 |
/* strings from sysfs write are not 0 terminated! */ if (count >= sizeof(override_name)) return -EINVAL; /* strip of : */ if (buf[count-1] == ' ') count--; |
734efb467 [PATCH] Time: Clo... |
810 |
|
75c5158f7 timekeeping: Upda... |
811 |
mutex_lock(&clocksource_mutex); |
734efb467 [PATCH] Time: Clo... |
812 |
|
92c7e0025 [PATCH] Simplify ... |
813 814 |
if (count > 0) memcpy(override_name, buf, count); |
734efb467 [PATCH] Time: Clo... |
815 |
override_name[count] = 0; |
f1b82746c clocksource: Clea... |
816 |
clocksource_select(); |
734efb467 [PATCH] Time: Clo... |
817 |
|
75c5158f7 timekeeping: Upda... |
818 |
mutex_unlock(&clocksource_mutex); |
734efb467 [PATCH] Time: Clo... |
819 820 821 822 823 824 825 |
return ret; } /** * sysfs_show_available_clocksources - sysfs interface for listing clocksource * @dev: unused |
b1b73d095 time/clocksource:... |
826 |
* @attr: unused |
734efb467 [PATCH] Time: Clo... |
827 828 829 830 831 |
* @buf: char buffer to be filled with clocksource list * * Provides sysfs interface for listing registered clocksources */ static ssize_t |
d369a5d8f clocksource: conv... |
832 833 |
sysfs_show_available_clocksources(struct device *dev, struct device_attribute *attr, |
4a0b2b4db sysdev: Pass the ... |
834 |
char *buf) |
734efb467 [PATCH] Time: Clo... |
835 |
{ |
2e1975868 kernel/time/clock... |
836 |
struct clocksource *src; |
5e2cb1018 time: fix sysfs_s... |
837 |
ssize_t count = 0; |
734efb467 [PATCH] Time: Clo... |
838 |
|
75c5158f7 timekeeping: Upda... |
839 |
mutex_lock(&clocksource_mutex); |
2e1975868 kernel/time/clock... |
840 |
list_for_each_entry(src, &clocksource_list, list) { |
cd6d95d84 clocksource: prev... |
841 842 843 844 845 846 |
/* * Don't show non-HRES clocksource if the tick code is * in one shot mode (highres=on or nohz=on) */ if (!tick_oneshot_mode_active() || (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
3f68535ad clocksource: sani... |
847 |
count += snprintf(buf + count, |
5e2cb1018 time: fix sysfs_s... |
848 849 |
max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "%s ", src->name); |
734efb467 [PATCH] Time: Clo... |
850 |
} |
75c5158f7 timekeeping: Upda... |
851 |
mutex_unlock(&clocksource_mutex); |
734efb467 [PATCH] Time: Clo... |
852 |
|
5e2cb1018 time: fix sysfs_s... |
853 854 855 |
count += snprintf(buf + count, max((ssize_t)PAGE_SIZE - count, (ssize_t)0), " "); |
734efb467 [PATCH] Time: Clo... |
856 |
|
5e2cb1018 time: fix sysfs_s... |
857 |
return count; |
734efb467 [PATCH] Time: Clo... |
858 859 860 861 862 |
} /* * Sysfs setup bits: */ |
d369a5d8f clocksource: conv... |
863 |
static DEVICE_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
f5f1a24a2 [PATCH] clocksour... |
864 |
sysfs_override_clocksource); |
734efb467 [PATCH] Time: Clo... |
865 |
|
d369a5d8f clocksource: conv... |
866 |
static DEVICE_ATTR(available_clocksource, 0444, |
f5f1a24a2 [PATCH] clocksour... |
867 |
sysfs_show_available_clocksources, NULL); |
734efb467 [PATCH] Time: Clo... |
868 |
|
d369a5d8f clocksource: conv... |
869 |
static struct bus_type clocksource_subsys = { |
af5ca3f4e Driver core: chan... |
870 |
.name = "clocksource", |
d369a5d8f clocksource: conv... |
871 |
.dev_name = "clocksource", |
734efb467 [PATCH] Time: Clo... |
872 |
}; |
d369a5d8f clocksource: conv... |
873 |
static struct device device_clocksource = { |
734efb467 [PATCH] Time: Clo... |
874 |
.id = 0, |
d369a5d8f clocksource: conv... |
875 |
.bus = &clocksource_subsys, |
734efb467 [PATCH] Time: Clo... |
876 |
}; |
ad596171e [PATCH] Time: Use... |
877 |
static int __init init_clocksource_sysfs(void) |
734efb467 [PATCH] Time: Clo... |
878 |
{ |
d369a5d8f clocksource: conv... |
879 |
int error = subsys_system_register(&clocksource_subsys, NULL); |
734efb467 [PATCH] Time: Clo... |
880 881 |
if (!error) |
d369a5d8f clocksource: conv... |
882 |
error = device_register(&device_clocksource); |
734efb467 [PATCH] Time: Clo... |
883 |
if (!error) |
d369a5d8f clocksource: conv... |
884 |
error = device_create_file( |
734efb467 [PATCH] Time: Clo... |
885 |
&device_clocksource, |
d369a5d8f clocksource: conv... |
886 |
&dev_attr_current_clocksource); |
734efb467 [PATCH] Time: Clo... |
887 |
if (!error) |
d369a5d8f clocksource: conv... |
888 |
error = device_create_file( |
734efb467 [PATCH] Time: Clo... |
889 |
&device_clocksource, |
d369a5d8f clocksource: conv... |
890 |
&dev_attr_available_clocksource); |
734efb467 [PATCH] Time: Clo... |
891 892 893 894 |
return error; } device_initcall(init_clocksource_sysfs); |
2b0137001 [PATCH] clocksour... |
895 |
#endif /* CONFIG_SYSFS */ |
734efb467 [PATCH] Time: Clo... |
896 897 898 899 900 901 902 903 904 905 |
/** * boot_override_clocksource - boot clock override * @str: override name * * Takes a clocksource= boot argument and uses it * as the clocksource override name. */ static int __init boot_override_clocksource(char* str) { |
75c5158f7 timekeeping: Upda... |
906 |
mutex_lock(&clocksource_mutex); |
734efb467 [PATCH] Time: Clo... |
907 908 |
if (str) strlcpy(override_name, str, sizeof(override_name)); |
75c5158f7 timekeeping: Upda... |
909 |
mutex_unlock(&clocksource_mutex); |
734efb467 [PATCH] Time: Clo... |
910 911 912 913 914 915 916 917 918 919 920 921 922 923 |
return 1; } __setup("clocksource=", boot_override_clocksource); /** * boot_override_clock - Compatibility layer for deprecated boot option * @str: override name * * DEPRECATED! Takes a clock= boot argument and uses it * as the clocksource override name */ static int __init boot_override_clock(char* str) { |
5d0cf410e [PATCH] Time: i38... |
924 925 926 927 928 929 930 931 932 |
if (!strcmp(str, "pmtmr")) { printk("Warning: clock=pmtmr is deprecated. " "Use clocksource=acpi_pm. "); return boot_override_clocksource("acpi_pm"); } printk("Warning! clock= boot option is deprecated. " "Use clocksource=xyz "); |
734efb467 [PATCH] Time: Clo... |
933 934 935 936 |
return boot_override_clocksource(str); } __setup("clock=", boot_override_clock); |