/* * linux/kernel/time/timekeeping.c * * Kernel timekeeping code and accessor functions * * This code was moved from linux/kernel/timer.c. * Please see that file for copyright and history logs. * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include static struct timekeeper timekeeper; /* flag for if timekeeping is suspended */ int __read_mostly timekeeping_suspended; /* Flag for if there is a persistent clock on this platform */ bool __read_mostly persistent_clock_exist = false; static inline void tk_normalize_xtime(struct timekeeper *tk) { while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) { tk->xtime_nsec -= (u64)NSEC_PER_SEC << tk->shift; tk->xtime_sec++; } } static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts) { tk->xtime_sec = ts->tv_sec; tk->xtime_nsec = (u64)ts->tv_nsec << tk->shift; } static void tk_xtime_add(struct timekeeper *tk, const struct timespec *ts) { tk->xtime_sec += ts->tv_sec; tk->xtime_nsec += (u64)ts->tv_nsec << tk->shift; tk_normalize_xtime(tk); } static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec wtm) { struct timespec tmp; /* * Verify consistency of: offset_real = -wall_to_monotonic * before modifying anything */ set_normalized_timespec(&tmp, -tk->wall_to_monotonic.tv_sec, -tk->wall_to_monotonic.tv_nsec); WARN_ON_ONCE(tk->offs_real.tv64 != timespec_to_ktime(tmp).tv64); tk->wall_to_monotonic = wtm; set_normalized_timespec(&tmp, -wtm.tv_sec, -wtm.tv_nsec); tk->offs_real = timespec_to_ktime(tmp); } static void tk_set_sleep_time(struct timekeeper *tk, struct timespec t) { /* Verify consistency before modifying */ WARN_ON_ONCE(tk->offs_boot.tv64 != timespec_to_ktime(tk->total_sleep_time).tv64); tk->total_sleep_time = t; tk->offs_boot = timespec_to_ktime(t); } /** * timekeeper_setup_internals - Set up internals to use clocksource clock. * * @clock: Pointer to clocksource. * * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment * pair and interval request. * * Unless you're the timekeeping code, you should not be using this! */ static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock) { cycle_t interval; u64 tmp, ntpinterval; struct clocksource *old_clock; old_clock = tk->clock; tk->clock = clock; clock->cycle_last = clock->read(clock); /* Do the ns -> cycle conversion first, using original mult */ tmp = NTP_INTERVAL_LENGTH; tmp <<= clock->shift; ntpinterval = tmp; tmp += clock->mult/2; do_div(tmp, clock->mult); if (tmp == 0) tmp = 1; interval = (cycle_t) tmp; tk->cycle_interval = interval; /* Go back from cycles -> shifted ns */ tk->xtime_interval = (u64) interval * clock->mult; tk->xtime_remainder = ntpinterval - tk->xtime_interval; tk->raw_interval = ((u64) interval * clock->mult) >> clock->shift; /* if changing clocks, convert xtime_nsec shift units */ if (old_clock) { int shift_change = clock->shift - old_clock->shift; if (shift_change < 0) tk->xtime_nsec >>= -shift_change; else tk->xtime_nsec <<= shift_change; } tk->shift = clock->shift; tk->ntp_error = 0; tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift; /* * The timekeeper keeps its own mult values for the currently * active clocksource. These value will be adjusted via NTP * to counteract clock drifting. */ tk->mult = clock->mult; } /* Timekeeper helper functions. */ #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET u32 (*arch_gettimeoffset)(void); u32 get_arch_timeoffset(void) { if (likely(arch_gettimeoffset)) return arch_gettimeoffset(); return 0; } #else static inline u32 get_arch_timeoffset(void) { return 0; } #endif static inline s64 timekeeping_get_ns(struct timekeeper *tk) { cycle_t cycle_now, cycle_delta; struct clocksource *clock; s64 nsec; /* read clocksource: */ clock = tk->clock; cycle_now = clock->read(clock); /* calculate the delta since the last update_wall_time: */ cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; nsec = cycle_delta * tk->mult + tk->xtime_nsec; nsec >>= tk->shift; /* If arch requires, add in get_arch_timeoffset() */ return nsec + get_arch_timeoffset(); } static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk) { cycle_t cycle_now, cycle_delta; struct clocksource *clock; s64 nsec; /* read clocksource: */ clock = tk->clock; cycle_now = clock->read(clock); /* calculate the delta since the last update_wall_time: */ cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; /* convert delta to nanoseconds. */ nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); /* If arch requires, add in get_arch_timeoffset() */ return nsec + get_arch_timeoffset(); } static RAW_NOTIFIER_HEAD(pvclock_gtod_chain); static void update_pvclock_gtod(struct timekeeper *tk) { raw_notifier_call_chain(&pvclock_gtod_chain, 0, tk); } /** * pvclock_gtod_register_notifier - register a pvclock timedata update listener * * Must hold write on timekeeper.lock */ int pvclock_gtod_register_notifier(struct notifier_block *nb) { struct timekeeper *tk = &timekeeper; unsigned long flags; int ret; write_seqlock_irqsave(&tk->lock, flags); ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb); /* update timekeeping data */ update_pvclock_gtod(tk); write_sequnlock_irqrestore(&tk->lock, flags); return ret; } EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier); /** * pvclock_gtod_unregister_notifier - unregister a pvclock * timedata update listener * * Must hold write on timekeeper.lock */ int pvclock_gtod_unregister_notifier(struct notifier_block *nb) { struct timekeeper *tk = &timekeeper; unsigned long flags; int ret; write_seqlock_irqsave(&tk->lock, flags); ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb); write_sequnlock_irqrestore(&tk->lock, flags); return ret; } EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier); /* must hold write on timekeeper.lock */ static void timekeeping_update(struct timekeeper *tk, bool clearntp) { if (clearntp) { tk->ntp_error = 0; ntp_clear(); } update_vsyscall(tk); update_pvclock_gtod(tk); } /** * timekeeping_forward_now - update clock to the current time * * Forward the current clock to update its state since the last call to * update_wall_time(). This is useful before significant clock changes, * as it avoids having to deal with this time offset explicitly. */ static void timekeeping_forward_now(struct timekeeper *tk) { cycle_t cycle_now, cycle_delta; struct clocksource *clock; s64 nsec; clock = tk->clock; cycle_now = clock->read(clock); cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; clock->cycle_last = cycle_now; tk->xtime_nsec += cycle_delta * tk->mult; /* If arch requires, add in get_arch_timeoffset() */ tk->xtime_nsec += (u64)get_arch_timeoffset() << tk->shift; tk_normalize_xtime(tk); nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); timespec_add_ns(&tk->raw_time, nsec); } /** * __getnstimeofday - Returns the time of day in a timespec. * @ts: pointer to the timespec to be set * * Updates the time of day in the timespec. * Returns 0 on success, or -ve when suspended (timespec will be undefined). */ int __getnstimeofday(struct timespec *ts) { struct timekeeper *tk = &timekeeper; unsigned long seq; s64 nsecs = 0; do { seq = read_seqbegin(&tk->lock); ts->tv_sec = tk->xtime_sec; nsecs = timekeeping_get_ns(tk); } while (read_seqretry(&tk->lock, seq)); ts->tv_nsec = 0; timespec_add_ns(ts, nsecs); /* * Do not bail out early, in case there were callers still using * the value, even in the face of the WARN_ON. */ if (unlikely(timekeeping_suspended)) return -EAGAIN; return 0; } EXPORT_SYMBOL(__getnstimeofday); /** * getnstimeofday - Returns the time of day in a timespec. * @ts: pointer to the timespec to be set * * Returns the time of day in a timespec (WARN if suspended). */ void getnstimeofday(struct timespec *ts) { WARN_ON(__getnstimeofday(ts)); } EXPORT_SYMBOL(getnstimeofday); ktime_t ktime_get(void) { struct timekeeper *tk = &timekeeper; unsigned int seq; s64 secs, nsecs; WARN_ON(timekeeping_suspended); do { seq = read_seqbegin(&tk->lock); secs = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec; } while (read_seqretry(&tk->lock, seq)); /* * Use ktime_set/ktime_add_ns to create a proper ktime on * 32-bit architectures without CONFIG_KTIME_SCALAR. */ return ktime_add_ns(ktime_set(secs, 0), nsecs); } EXPORT_SYMBOL_GPL(ktime_get); /** * ktime_get_ts - get the monotonic clock in timespec format * @ts: pointer to timespec variable * * The function calculates the monotonic clock from the realtime * clock and the wall_to_monotonic offset and stores the result * in normalized timespec format in the variable pointed to by @ts. */ void ktime_get_ts(struct timespec *ts) { struct timekeeper *tk = &timekeeper; struct timespec tomono; s64 nsec; unsigned int seq; WARN_ON(timekeeping_suspended); do { seq = read_seqbegin(&tk->lock); ts->tv_sec = tk->xtime_sec; nsec = timekeeping_get_ns(tk); tomono = tk->wall_to_monotonic; } while (read_seqretry(&tk->lock, seq)); ts->tv_sec += tomono.tv_sec; ts->tv_nsec = 0; timespec_add_ns(ts, nsec + tomono.tv_nsec); } EXPORT_SYMBOL_GPL(ktime_get_ts); /** * timekeeping_clocktai - Returns the TAI time of day in a timespec * @ts: pointer to the timespec to be set * * Returns the time of day in a timespec. */ void timekeeping_clocktai(struct timespec *ts) { struct timekeeper *tk = &timekeeper; unsigned long seq; u64 nsecs; WARN_ON(timekeeping_suspended); do { seq = read_seqbegin(&tk->lock); ts->tv_sec = tk->xtime_sec + tk->tai_offset; nsecs = timekeeping_get_ns(tk); } while (read_seqretry(&tk->lock, seq)); ts->tv_nsec = 0; timespec_add_ns(ts, nsecs); } EXPORT_SYMBOL(timekeeping_clocktai); #ifdef CONFIG_NTP_PPS /** * getnstime_raw_and_real - get day and raw monotonic time in timespec format * @ts_raw: pointer to the timespec to be set to raw monotonic time * @ts_real: pointer to the timespec to be set to the time of day * * This function reads both the time of day and raw monotonic time at the * same time atomically and stores the resulting timestamps in timespec * format. */ void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real) { struct timekeeper *tk = &timekeeper; unsigned long seq; s64 nsecs_raw, nsecs_real; WARN_ON_ONCE(timekeeping_suspended); do { seq = read_seqbegin(&tk->lock); *ts_raw = tk->raw_time; ts_real->tv_sec = tk->xtime_sec; ts_real->tv_nsec = 0; nsecs_raw = timekeeping_get_ns_raw(tk); nsecs_real = timekeeping_get_ns(tk); } while (read_seqretry(&tk->lock, seq)); timespec_add_ns(ts_raw, nsecs_raw); timespec_add_ns(ts_real, nsecs_real); } EXPORT_SYMBOL(getnstime_raw_and_real); #endif /* CONFIG_NTP_PPS */ /** * do_gettimeofday - Returns the time of day in a timeval * @tv: pointer to the timeval to be set * * NOTE: Users should be converted to using getnstimeofday() */ void do_gettimeofday(struct timeval *tv) { struct timespec now; getnstimeofday(&now); tv->tv_sec = now.tv_sec; tv->tv_usec = now.tv_nsec/1000; } EXPORT_SYMBOL(do_gettimeofday); /** * do_settimeofday - Sets the time of day * @tv: pointer to the timespec variable containing the new time * * Sets the time of day to the new time and update NTP and notify hrtimers */ int do_settimeofday(const struct timespec *tv) { struct timekeeper *tk = &timekeeper; struct timespec ts_delta, xt; unsigned long flags; if (!timespec_valid_strict(tv)) return -EINVAL; write_seqlock_irqsave(&tk->lock, flags); timekeeping_forward_now(tk); xt = tk_xtime(tk); ts_delta.tv_sec = tv->tv_sec - xt.tv_sec; ts_delta.tv_nsec = tv->tv_nsec - xt.tv_nsec; tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, ts_delta)); tk_set_xtime(tk, tv); timekeeping_update(tk, true); write_sequnlock_irqrestore(&tk->lock, flags); /* signal hrtimers about time change */ clock_was_set(); return 0; } EXPORT_SYMBOL(do_settimeofday); /** * timekeeping_inject_offset - Adds or subtracts from the current time. * @tv: pointer to the timespec variable containing the offset * * Adds or subtracts an offset value from the current time. */ int timekeeping_inject_offset(struct timespec *ts) { struct timekeeper *tk = &timekeeper; unsigned long flags; struct timespec tmp; int ret = 0; if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC) return -EINVAL; write_seqlock_irqsave(&tk->lock, flags); timekeeping_forward_now(tk); /* Make sure the proposed value is valid */ tmp = timespec_add(tk_xtime(tk), *ts); if (!timespec_valid_strict(&tmp)) { ret = -EINVAL; goto error; } tk_xtime_add(tk, ts); tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *ts)); error: /* even if we error out, we forwarded the time, so call update */ timekeeping_update(tk, true); write_sequnlock_irqrestore(&tk->lock, flags); /* signal hrtimers about time change */ clock_was_set(); return ret; } EXPORT_SYMBOL(timekeeping_inject_offset); /** * timekeeping_get_tai_offset - Returns current TAI offset from UTC * */ s32 timekeeping_get_tai_offset(void) { struct timekeeper *tk = &timekeeper; unsigned int seq; s32 ret; do { seq = read_seqbegin(&tk->lock); ret = tk->tai_offset; } while (read_seqretry(&tk->lock, seq)); return ret; } /** * __timekeeping_set_tai_offset - Lock free worker function * */ void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset) { tk->tai_offset = tai_offset; } /** * timekeeping_set_tai_offset - Sets the current TAI offset from UTC * */ void timekeeping_set_tai_offset(s32 tai_offset) { struct timekeeper *tk = &timekeeper; unsigned long flags; write_seqlock_irqsave(&tk->lock, flags); __timekeeping_set_tai_offset(tk, tai_offset); write_sequnlock_irqrestore(&tk->lock, flags); } /** * change_clocksource - Swaps clocksources if a new one is available * * Accumulates current time interval and initializes new clocksource */ static int change_clocksource(void *data) { struct timekeeper *tk = &timekeeper; struct clocksource *new, *old; unsigned long flags; new = (struct clocksource *) data; write_seqlock_irqsave(&tk->lock, flags); timekeeping_forward_now(tk); if (!new->enable || new->enable(new) == 0) { old = tk->clock; tk_setup_internals(tk, new); if (old->disable) old->disable(old); } timekeeping_update(tk, true); write_sequnlock_irqrestore(&tk->lock, flags); return 0; } /** * timekeeping_notify - Install a new clock source * @clock: pointer to the clock source * * This function is called from clocksource.c after a new, better clock * source has been registered. The caller holds the clocksource_mutex. */ void timekeeping_notify(struct clocksource *clock) { struct timekeeper *tk = &timekeeper; if (tk->clock == clock) return; stop_machine(change_clocksource, clock, NULL); tick_clock_notify(); } /** * ktime_get_real - get the real (wall-) time in ktime_t format * * returns the time in ktime_t format */ ktime_t ktime_get_real(void) { struct timespec now; getnstimeofday(&now); return timespec_to_ktime(now); } EXPORT_SYMBOL_GPL(ktime_get_real); /** * getrawmonotonic - Returns the raw monotonic time in a timespec * @ts: pointer to the timespec to be set * * Returns the raw monotonic time (completely un-modified by ntp) */ void getrawmonotonic(struct timespec *ts) { struct timekeeper *tk = &timekeeper; unsigned long seq; s64 nsecs; do { seq = read_seqbegin(&tk->lock); nsecs = timekeeping_get_ns_raw(tk); *ts = tk->raw_time; } while (read_seqretry(&tk->lock, seq)); timespec_add_ns(ts, nsecs); } EXPORT_SYMBOL(getrawmonotonic); /** * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres */ int timekeeping_valid_for_hres(void) { struct timekeeper *tk = &timekeeper; unsigned long seq; int ret; do { seq = read_seqbegin(&tk->lock); ret = tk->clock->flags & CLOCK_SOURCE_VALID_FOR_HRES; } while (read_seqretry(&tk->lock, seq)); return ret; } /** * timekeeping_max_deferment - Returns max time the clocksource can be deferred */ u64 timekeeping_max_deferment(void) { struct timekeeper *tk = &timekeeper; unsigned long seq; u64 ret; do { seq = read_seqbegin(&tk->lock); ret = tk->clock->max_idle_ns; } while (read_seqretry(&tk->lock, seq)); return ret; } /** * read_persistent_clock - Return time from the persistent clock. * * Weak dummy function for arches that do not yet support it. * Reads the time from the battery backed persistent clock. * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported. * * XXX - Do be sure to remove it once all arches implement it. */ void __attribute__((weak)) read_persistent_clock(struct timespec *ts) { ts->tv_sec = 0; ts->tv_nsec = 0; } /** * read_boot_clock - Return time of the system start. * * Weak dummy function for arches that do not yet support it. * Function to read the exact time the system has been started. * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported. * * XXX - Do be sure to remove it once all arches implement it. */ void __attribute__((weak)) read_boot_clock(struct timespec *ts) { ts->tv_sec = 0; ts->tv_nsec = 0; } /* * timekeeping_init - Initializes the clocksource and common timekeeping values */ void __init timekeeping_init(void) { struct timekeeper *tk = &timekeeper; struct clocksource *clock; unsigned long flags; struct timespec now, boot, tmp; read_persistent_clock(&now); if (!timespec_valid_strict(&now)) { pr_warn("WARNING: Persistent clock returned invalid value!\n" " Check your CMOS/BIOS settings.\n"); now.tv_sec = 0; now.tv_nsec = 0; } else if (now.tv_sec || now.tv_nsec) persistent_clock_exist = true; read_boot_clock(&boot); if (!timespec_valid_strict(&boot)) { pr_warn("WARNING: Boot clock returned invalid value!\n" " Check your CMOS/BIOS settings.\n"); boot.tv_sec = 0; boot.tv_nsec = 0; } seqlock_init(&tk->lock); ntp_init(); write_seqlock_irqsave(&tk->lock, flags); clock = clocksource_default_clock(); if (clock->enable) clock->enable(clock); tk_setup_internals(tk, clock); tk_set_xtime(tk, &now); tk->raw_time.tv_sec = 0; tk->raw_time.tv_nsec = 0; if (boot.tv_sec == 0 && boot.tv_nsec == 0) boot = tk_xtime(tk); set_normalized_timespec(&tmp, -boot.tv_sec, -boot.tv_nsec); tk_set_wall_to_mono(tk, tmp); tmp.tv_sec = 0; tmp.tv_nsec = 0; tk_set_sleep_time(tk, tmp); write_sequnlock_irqrestore(&tk->lock, flags); } /* time in seconds when suspend began */ static struct timespec timekeeping_suspend_time; /** * __timekeeping_inject_sleeptime - Internal function to add sleep interval * @delta: pointer to a timespec delta value * * Takes a timespec offset measuring a suspend interval and properly * adds the sleep offset to the timekeeping variables. */ static void __timekeeping_inject_sleeptime(struct timekeeper *tk, struct timespec *delta) { if (!timespec_valid_strict(delta)) { printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid " "sleep delta value!\n"); return; } tk_xtime_add(tk, delta); tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *delta)); tk_set_sleep_time(tk, timespec_add(tk->total_sleep_time, *delta)); } /** * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values * @delta: pointer to a timespec delta value * * This hook is for architectures that cannot support read_persistent_clock * because their RTC/persistent clock is only accessible when irqs are enabled. * * This function should only be called by rtc_resume(), and allows * a suspend offset to be injected into the timekeeping values. */ void timekeeping_inject_sleeptime(struct timespec *delta) { struct timekeeper *tk = &timekeeper; unsigned long flags; /* * Make sure we don't set the clock twice, as timekeeping_resume() * already did it */ if (has_persistent_clock()) return; write_seqlock_irqsave(&tk->lock, flags); timekeeping_forward_now(tk); __timekeeping_inject_sleeptime(tk, delta); timekeeping_update(tk, true); write_sequnlock_irqrestore(&tk->lock, flags); /* signal hrtimers about time change */ clock_was_set(); } /** * timekeeping_resume - Resumes the generic timekeeping subsystem. * * This is for the generic clocksource timekeeping. * xtime/wall_to_monotonic/jiffies/etc are * still managed by arch specific suspend/resume code. */ static void timekeeping_resume(void) { struct timekeeper *tk = &timekeeper; struct clocksource *clock = tk->clock; unsigned long flags; struct timespec ts_new, ts_delta; cycle_t cycle_now, cycle_delta; bool suspendtime_found = false; read_persistent_clock(&ts_new); clockevents_resume(); clocksource_resume(); write_seqlock_irqsave(&tk->lock, flags); /* * After system resumes, we need to calculate the suspended time and * compensate it for the OS time. There are 3 sources that could be * used: Nonstop clocksource during suspend, persistent clock and rtc * device. * * One specific platform may have 1 or 2 or all of them, and the * preference will be: * suspend-nonstop clocksource -> persistent clock -> rtc * The less preferred source will only be tried if there is no better * usable source. The rtc part is handled separately in rtc core code. */ cycle_now = clock->read(clock); if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) && cycle_now > clock->cycle_last) { u64 num, max = ULLONG_MAX; u32 mult = clock->mult; u32 shift = clock->shift; s64 nsec = 0; cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; /* * "cycle_delta * mutl" may cause 64 bits overflow, if the * suspended time is too long. In that case we need do the * 64 bits math carefully */ do_div(max, mult); if (cycle_delta > max) { num = div64_u64(cycle_delta, max); nsec = (((u64) max * mult) >> shift) * num; cycle_delta -= num * max; } nsec += ((u64) cycle_delta * mult) >> shift; ts_delta = ns_to_timespec(nsec); suspendtime_found = true; } else if (timespec_compare(&ts_new, &timekeeping_suspend_time) > 0) { ts_delta = timespec_sub(ts_new, timekeeping_suspend_time); suspendtime_found = true; } if (suspendtime_found) __timekeeping_inject_sleeptime(tk, &ts_delta); /* Re-base the last cycle value */ clock->cycle_last = cycle_now; tk->ntp_error = 0; timekeeping_suspended = 0; timekeeping_update(tk, false); write_sequnlock_irqrestore(&tk->lock, flags); touch_softlockup_watchdog(); clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); /* Resume hrtimers */ hrtimers_resume(); } static int timekeeping_suspend(void) { struct timekeeper *tk = &timekeeper; unsigned long flags; struct timespec delta, delta_delta; static struct timespec old_delta; read_persistent_clock(&timekeeping_suspend_time); write_seqlock_irqsave(&tk->lock, flags); timekeeping_forward_now(tk); timekeeping_suspended = 1; /* * To avoid drift caused by repeated suspend/resumes, * which each can add ~1 second drift error, * try to compensate so the difference in system time * and persistent_clock time stays close to constant. */ delta = timespec_sub(tk_xtime(tk), timekeeping_suspend_time); delta_delta = timespec_sub(delta, old_delta); if (abs(delta_delta.tv_sec) >= 2) { /* * if delta_delta is too large, assume time correction * has occured and set old_delta to the current delta. */ old_delta = delta; } else { /* Otherwise try to adjust old_system to compensate */ timekeeping_suspend_time = timespec_add(timekeeping_suspend_time, delta_delta); } write_sequnlock_irqrestore(&tk->lock, flags); clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); clocksource_suspend(); clockevents_suspend(); return 0; } /* sysfs resume/suspend bits for timekeeping */ static struct syscore_ops timekeeping_syscore_ops = { .resume = timekeeping_resume, .suspend = timekeeping_suspend, }; static int __init timekeeping_init_ops(void) { register_syscore_ops(&timekeeping_syscore_ops); return 0; } device_initcall(timekeeping_init_ops); /* * If the error is already larger, we look ahead even further * to compensate for late or lost adjustments. */ static __always_inline int timekeeping_bigadjust(struct timekeeper *tk, s64 error, s64 *interval, s64 *offset) { s64 tick_error, i; u32 look_ahead, adj; s32 error2, mult; /* * Use the current error value to determine how much to look ahead. * The larger the error the slower we adjust for it to avoid problems * with losing too many ticks, otherwise we would overadjust and * produce an even larger error. The smaller the adjustment the * faster we try to adjust for it, as lost ticks can do less harm * here. This is tuned so that an error of about 1 msec is adjusted * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks). */ error2 = tk->ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ); error2 = abs(error2); for (look_ahead = 0; error2 > 0; look_ahead++) error2 >>= 2; /* * Now calculate the error in (1 << look_ahead) ticks, but first * remove the single look ahead already included in the error. */ tick_error = ntp_tick_length() >> (tk->ntp_error_shift + 1); tick_error -= tk->xtime_interval >> 1; error = ((error - tick_error) >> look_ahead) + tick_error; /* Finally calculate the adjustment shift value. */ i = *interval; mult = 1; if (error < 0) { error = -error; *interval = -*interval; *offset = -*offset; mult = -1; } for (adj = 0; error > i; adj++) error >>= 1; *interval <<= adj; *offset <<= adj; return mult << adj; } /* * Adjust the multiplier to reduce the error value, * this is optimized for the most common adjustments of -1,0,1, * for other values we can do a bit more work. */ static void timekeeping_adjust(struct timekeeper *tk, s64 offset) { s64 error, interval = tk->cycle_interval; int adj; /* * The point of this is to check if the error is greater than half * an interval. * * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs. * * Note we subtract one in the shift, so that error is really error*2. * This "saves" dividing(shifting) interval twice, but keeps the * (error > interval) comparison as still measuring if error is * larger than half an interval. * * Note: It does not "save" on aggravation when reading the code. */ error = tk->ntp_error >> (tk->ntp_error_shift - 1); if (error > interval) { /* * We now divide error by 4(via shift), which checks if * the error is greater than twice the interval. * If it is greater, we need a bigadjust, if its smaller, * we can adjust by 1. */ error >>= 2; /* * XXX - In update_wall_time, we round up to the next * nanosecond, and store the amount rounded up into * the error. This causes the likely below to be unlikely. * * The proper fix is to avoid rounding up by using * the high precision tk->xtime_nsec instead of * xtime.tv_nsec everywhere. Fixing this will take some * time. */ if (likely(error <= interval)) adj = 1; else adj = timekeeping_bigadjust(tk, error, &interval, &offset); } else { if (error < -interval) { /* See comment above, this is just switched for the negative */ error >>= 2; if (likely(error >= -interval)) { adj = -1; interval = -interval; offset = -offset; } else { adj = timekeeping_bigadjust(tk, error, &interval, &offset); } } else { goto out_adjust; } } if (unlikely(tk->clock->maxadj && (tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) { printk_once(KERN_WARNING "Adjusting %s more than 11%% (%ld vs %ld)\n", tk->clock->name, (long)tk->mult + adj, (long)tk->clock->mult + tk->clock->maxadj); } /* * So the following can be confusing. * * To keep things simple, lets assume adj == 1 for now. * * When adj != 1, remember that the interval and offset values * have been appropriately scaled so the math is the same. * * The basic idea here is that we're increasing the multiplier * by one, this causes the xtime_interval to be incremented by * one cycle_interval. This is because: * xtime_interval = cycle_interval * mult * So if mult is being incremented by one: * xtime_interval = cycle_interval * (mult + 1) * Its the same as: * xtime_interval = (cycle_interval * mult) + cycle_interval * Which can be shortened to: * xtime_interval += cycle_interval * * So offset stores the non-accumulated cycles. Thus the current * time (in shifted nanoseconds) is: * now = (offset * adj) + xtime_nsec * Now, even though we're adjusting the clock frequency, we have * to keep time consistent. In other words, we can't jump back * in time, and we also want to avoid jumping forward in time. * * So given the same offset value, we need the time to be the same * both before and after the freq adjustment. * now = (offset * adj_1) + xtime_nsec_1 * now = (offset * adj_2) + xtime_nsec_2 * So: * (offset * adj_1) + xtime_nsec_1 = * (offset * adj_2) + xtime_nsec_2 * And we know: * adj_2 = adj_1 + 1 * So: * (offset * adj_1) + xtime_nsec_1 = * (offset * (adj_1+1)) + xtime_nsec_2 * (offset * adj_1) + xtime_nsec_1 = * (offset * adj_1) + offset + xtime_nsec_2 * Canceling the sides: * xtime_nsec_1 = offset + xtime_nsec_2 * Which gives us: * xtime_nsec_2 = xtime_nsec_1 - offset * Which simplfies to: * xtime_nsec -= offset * * XXX - TODO: Doc ntp_error calculation. */ tk->mult += adj; tk->xtime_interval += interval; tk->xtime_nsec -= offset; tk->ntp_error -= (interval - offset) << tk->ntp_error_shift; out_adjust: /* * It may be possible that when we entered this function, xtime_nsec * was very small. Further, if we're slightly speeding the clocksource * in the code above, its possible the required corrective factor to * xtime_nsec could cause it to underflow. * * Now, since we already accumulated the second, cannot simply roll * the accumulated second back, since the NTP subsystem has been * notified via second_overflow. So instead we push xtime_nsec forward * by the amount we underflowed, and add that amount into the error. * * We'll correct this error next time through this function, when * xtime_nsec is not as small. */ if (unlikely((s64)tk->xtime_nsec < 0)) { s64 neg = -(s64)tk->xtime_nsec; tk->xtime_nsec = 0; tk->ntp_error += neg << tk->ntp_error_shift; } } /** * accumulate_nsecs_to_secs - Accumulates nsecs into secs * * Helper function that accumulates a the nsecs greater then a second * from the xtime_nsec field to the xtime_secs field. * It also calls into the NTP code to handle leapsecond processing. * */ static inline void accumulate_nsecs_to_secs(struct timekeeper *tk) { u64 nsecps = (u64)NSEC_PER_SEC << tk->shift; while (tk->xtime_nsec >= nsecps) { int leap; tk->xtime_nsec -= nsecps; tk->xtime_sec++; /* Figure out if its a leap sec and apply if needed */ leap = second_overflow(tk->xtime_sec); if (unlikely(leap)) { struct timespec ts; tk->xtime_sec += leap; ts.tv_sec = leap; ts.tv_nsec = 0; tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, ts)); __timekeeping_set_tai_offset(tk, tk->tai_offset - leap); clock_was_set_delayed(); } } } /** * logarithmic_accumulation - shifted accumulation of cycles * * This functions accumulates a shifted interval of cycles into * into a shifted interval nanoseconds. Allows for O(log) accumulation * loop. * * Returns the unconsumed cycles. */ static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset, u32 shift) { u64 raw_nsecs; /* If the offset is smaller then a shifted interval, do nothing */ if (offset < tk->cycle_interval<cycle_interval << shift; tk->clock->cycle_last += tk->cycle_interval << shift; tk->xtime_nsec += tk->xtime_interval << shift; accumulate_nsecs_to_secs(tk); /* Accumulate raw time */ raw_nsecs = (u64)tk->raw_interval << shift; raw_nsecs += tk->raw_time.tv_nsec; if (raw_nsecs >= NSEC_PER_SEC) { u64 raw_secs = raw_nsecs; raw_nsecs = do_div(raw_secs, NSEC_PER_SEC); tk->raw_time.tv_sec += raw_secs; } tk->raw_time.tv_nsec = raw_nsecs; /* Accumulate error between NTP and clock interval */ tk->ntp_error += ntp_tick_length() << shift; tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) << (tk->ntp_error_shift + shift); return offset; } #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD static inline void old_vsyscall_fixup(struct timekeeper *tk) { s64 remainder; /* * Store only full nanoseconds into xtime_nsec after rounding * it up and add the remainder to the error difference. * XXX - This is necessary to avoid small 1ns inconsistnecies caused * by truncating the remainder in vsyscalls. However, it causes * additional work to be done in timekeeping_adjust(). Once * the vsyscall implementations are converted to use xtime_nsec * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD * users are removed, this can be killed. */ remainder = tk->xtime_nsec & ((1ULL << tk->shift) - 1); tk->xtime_nsec -= remainder; tk->xtime_nsec += 1ULL << tk->shift; tk->ntp_error += remainder << tk->ntp_error_shift; } #else #define old_vsyscall_fixup(tk) #endif /** * update_wall_time - Uses the current clocksource to increment the wall time * */ static void update_wall_time(void) { struct clocksource *clock; struct timekeeper *tk = &timekeeper; cycle_t offset; int shift = 0, maxshift; unsigned long flags; write_seqlock_irqsave(&tk->lock, flags); /* Make sure we're fully resumed: */ if (unlikely(timekeeping_suspended)) goto out; clock = tk->clock; #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET offset = tk->cycle_interval; #else offset = (clock->read(clock) - clock->cycle_last) & clock->mask; #endif /* Check if there's really nothing to do */ if (offset < tk->cycle_interval) goto out; /* * With NO_HZ we may have to accumulate many cycle_intervals * (think "ticks") worth of time at once. To do this efficiently, * we calculate the largest doubling multiple of cycle_intervals * that is smaller than the offset. We then accumulate that * chunk in one go, and then try to consume the next smaller * doubled multiple. */ shift = ilog2(offset) - ilog2(tk->cycle_interval); shift = max(0, shift); /* Bound shift to one less than what overflows tick_length */ maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1; shift = min(shift, maxshift); while (offset >= tk->cycle_interval) { offset = logarithmic_accumulation(tk, offset, shift); if (offset < tk->cycle_interval<lock, flags); } /** * getboottime - Return the real time of system boot. * @ts: pointer to the timespec to be set * * Returns the wall-time of boot in a timespec. * * This is based on the wall_to_monotonic offset and the total suspend * time. Calls to settimeofday will affect the value returned (which * basically means that however wrong your real time clock is at boot time, * you get the right time here). */ void getboottime(struct timespec *ts) { struct timekeeper *tk = &timekeeper; struct timespec boottime = { .tv_sec = tk->wall_to_monotonic.tv_sec + tk->total_sleep_time.tv_sec, .tv_nsec = tk->wall_to_monotonic.tv_nsec + tk->total_sleep_time.tv_nsec }; set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec); } EXPORT_SYMBOL_GPL(getboottime); /** * get_monotonic_boottime - Returns monotonic time since boot * @ts: pointer to the timespec to be set * * Returns the monotonic time since boot in a timespec. * * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also * includes the time spent in suspend. */ void get_monotonic_boottime(struct timespec *ts) { struct timekeeper *tk = &timekeeper; struct timespec tomono, sleep; s64 nsec; unsigned int seq; WARN_ON(timekeeping_suspended); do { seq = read_seqbegin(&tk->lock); ts->tv_sec = tk->xtime_sec; nsec = timekeeping_get_ns(tk); tomono = tk->wall_to_monotonic; sleep = tk->total_sleep_time; } while (read_seqretry(&tk->lock, seq)); ts->tv_sec += tomono.tv_sec + sleep.tv_sec; ts->tv_nsec = 0; timespec_add_ns(ts, nsec + tomono.tv_nsec + sleep.tv_nsec); } EXPORT_SYMBOL_GPL(get_monotonic_boottime); /** * ktime_get_boottime - Returns monotonic time since boot in a ktime * * Returns the monotonic time since boot in a ktime * * This is similar to CLOCK_MONTONIC/ktime_get, but also * includes the time spent in suspend. */ ktime_t ktime_get_boottime(void) { struct timespec ts; get_monotonic_boottime(&ts); return timespec_to_ktime(ts); } EXPORT_SYMBOL_GPL(ktime_get_boottime); /** * monotonic_to_bootbased - Convert the monotonic time to boot based. * @ts: pointer to the timespec to be converted */ void monotonic_to_bootbased(struct timespec *ts) { struct timekeeper *tk = &timekeeper; *ts = timespec_add(*ts, tk->total_sleep_time); } EXPORT_SYMBOL_GPL(monotonic_to_bootbased); unsigned long get_seconds(void) { struct timekeeper *tk = &timekeeper; return tk->xtime_sec; } EXPORT_SYMBOL(get_seconds); struct timespec __current_kernel_time(void) { struct timekeeper *tk = &timekeeper; return tk_xtime(tk); } struct timespec current_kernel_time(void) { struct timekeeper *tk = &timekeeper; struct timespec now; unsigned long seq; do { seq = read_seqbegin(&tk->lock); now = tk_xtime(tk); } while (read_seqretry(&tk->lock, seq)); return now; } EXPORT_SYMBOL(current_kernel_time); struct timespec get_monotonic_coarse(void) { struct timekeeper *tk = &timekeeper; struct timespec now, mono; unsigned long seq; do { seq = read_seqbegin(&tk->lock); now = tk_xtime(tk); mono = tk->wall_to_monotonic; } while (read_seqretry(&tk->lock, seq)); set_normalized_timespec(&now, now.tv_sec + mono.tv_sec, now.tv_nsec + mono.tv_nsec); return now; } /* * Must hold jiffies_lock */ void do_timer(unsigned long ticks) { jiffies_64 += ticks; update_wall_time(); calc_global_load(ticks); } /** * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic, * and sleep offsets. * @xtim: pointer to timespec to be set with xtime * @wtom: pointer to timespec to be set with wall_to_monotonic * @sleep: pointer to timespec to be set with time in suspend */ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim, struct timespec *wtom, struct timespec *sleep) { struct timekeeper *tk = &timekeeper; unsigned long seq; do { seq = read_seqbegin(&tk->lock); *xtim = tk_xtime(tk); *wtom = tk->wall_to_monotonic; *sleep = tk->total_sleep_time; } while (read_seqretry(&tk->lock, seq)); } #ifdef CONFIG_HIGH_RES_TIMERS /** * ktime_get_update_offsets - hrtimer helper * @offs_real: pointer to storage for monotonic -> realtime offset * @offs_boot: pointer to storage for monotonic -> boottime offset * * Returns current monotonic time and updates the offsets * Called from hrtimer_interupt() or retrigger_next_event() */ ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot) { struct timekeeper *tk = &timekeeper; ktime_t now; unsigned int seq; u64 secs, nsecs; do { seq = read_seqbegin(&tk->lock); secs = tk->xtime_sec; nsecs = timekeeping_get_ns(tk); *offs_real = tk->offs_real; *offs_boot = tk->offs_boot; } while (read_seqretry(&tk->lock, seq)); now = ktime_add_ns(ktime_set(secs, 0), nsecs); now = ktime_sub(now, *offs_real); return now; } #endif /** * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format */ ktime_t ktime_get_monotonic_offset(void) { struct timekeeper *tk = &timekeeper; unsigned long seq; struct timespec wtom; do { seq = read_seqbegin(&tk->lock); wtom = tk->wall_to_monotonic; } while (read_seqretry(&tk->lock, seq)); return timespec_to_ktime(wtom); } EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset); /** * xtime_update() - advances the timekeeping infrastructure * @ticks: number of ticks, that have elapsed since the last call. * * Must be called with interrupts disabled. */ void xtime_update(unsigned long ticks) { write_seqlock(&jiffies_lock); do_timer(ticks); write_sequnlock(&jiffies_lock); }