| /* |
| * NTP state machine interfaces and logic. |
| * |
| * This code was mainly moved from kernel/timer.c and kernel/time.c |
| * Please see those files for relevant copyright info and historical |
| * changelogs. |
| */ |
| #include <linux/capability.h> |
| #include <linux/clocksource.h> |
| #include <linux/workqueue.h> |
| #include <linux/hrtimer.h> |
| #include <linux/jiffies.h> |
| #include <linux/math64.h> |
| #include <linux/timex.h> |
| #include <linux/time.h> |
| #include <linux/mm.h> |
| |
| /* |
| * NTP timekeeping variables: |
| */ |
| |
| /* USER_HZ period (usecs): */ |
| unsigned long tick_usec = TICK_USEC; |
| |
| /* ACTHZ period (nsecs): */ |
| unsigned long tick_nsec; |
| |
| u64 tick_length; |
| static u64 tick_length_base; |
| |
| static struct hrtimer leap_timer; |
| |
| #define MAX_TICKADJ 500LL /* usecs */ |
| #define MAX_TICKADJ_SCALED \ |
| (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ) |
| |
| /* |
| * phase-lock loop variables |
| */ |
| |
| /* |
| * clock synchronization status |
| * |
| * (TIME_ERROR prevents overwriting the CMOS clock) |
| */ |
| static int time_state = TIME_OK; |
| |
| /* clock status bits: */ |
| int time_status = STA_UNSYNC; |
| |
| /* TAI offset (secs): */ |
| static long time_tai; |
| |
| /* time adjustment (nsecs): */ |
| static s64 time_offset; |
| |
| /* pll time constant: */ |
| static long time_constant = 2; |
| |
| /* maximum error (usecs): */ |
| long time_maxerror = NTP_PHASE_LIMIT; |
| |
| /* estimated error (usecs): */ |
| long time_esterror = NTP_PHASE_LIMIT; |
| |
| /* frequency offset (scaled nsecs/secs): */ |
| static s64 time_freq; |
| |
| /* time at last adjustment (secs): */ |
| static long time_reftime; |
| |
| long time_adjust; |
| |
| /* constant (boot-param configurable) NTP tick adjustment (upscaled) */ |
| static s64 ntp_tick_adj; |
| |
| /* |
| * NTP methods: |
| */ |
| |
| /* |
| * Update (tick_length, tick_length_base, tick_nsec), based |
| * on (tick_usec, ntp_tick_adj, time_freq): |
| */ |
| static void ntp_update_frequency(void) |
| { |
| u64 second_length; |
| u64 new_base; |
| |
| second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) |
| << NTP_SCALE_SHIFT; |
| |
| second_length += ntp_tick_adj; |
| second_length += time_freq; |
| |
| tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT; |
| new_base = div_u64(second_length, NTP_INTERVAL_FREQ); |
| |
| /* |
| * Don't wait for the next second_overflow, apply |
| * the change to the tick length immediately: |
| */ |
| tick_length += new_base - tick_length_base; |
| tick_length_base = new_base; |
| } |
| |
| static inline s64 ntp_update_offset_fll(s64 offset64, long secs) |
| { |
| time_status &= ~STA_MODE; |
| |
| if (secs < MINSEC) |
| return 0; |
| |
| if (!(time_status & STA_FLL) && (secs <= MAXSEC)) |
| return 0; |
| |
| time_status |= STA_MODE; |
| |
| return div_s64(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs); |
| } |
| |
| static void ntp_update_offset(long offset) |
| { |
| s64 freq_adj; |
| s64 offset64; |
| long secs; |
| |
| if (!(time_status & STA_PLL)) |
| return; |
| |
| if (!(time_status & STA_NANO)) |
| offset *= NSEC_PER_USEC; |
| |
| /* |
| * Scale the phase adjustment and |
| * clamp to the operating range. |
| */ |
| offset = min(offset, MAXPHASE); |
| offset = max(offset, -MAXPHASE); |
| |
| /* |
| * Select how the frequency is to be controlled |
| * and in which mode (PLL or FLL). |
| */ |
| secs = xtime.tv_sec - time_reftime; |
| if (unlikely(time_status & STA_FREQHOLD)) |
| secs = 0; |
| |
| time_reftime = xtime.tv_sec; |
| |
| offset64 = offset; |
| freq_adj = (offset64 * secs) << |
| (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant)); |
| |
| freq_adj += ntp_update_offset_fll(offset64, secs); |
| |
| freq_adj = min(freq_adj + time_freq, MAXFREQ_SCALED); |
| |
| time_freq = max(freq_adj, -MAXFREQ_SCALED); |
| |
| time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ); |
| } |
| |
| /** |
| * ntp_clear - Clears the NTP state variables |
| * |
| * Must be called while holding a write on the xtime_lock |
| */ |
| void ntp_clear(void) |
| { |
| time_adjust = 0; /* stop active adjtime() */ |
| time_status |= STA_UNSYNC; |
| time_maxerror = NTP_PHASE_LIMIT; |
| time_esterror = NTP_PHASE_LIMIT; |
| |
| ntp_update_frequency(); |
| |
| tick_length = tick_length_base; |
| time_offset = 0; |
| } |
| |
| /* |
| * Leap second processing. If in leap-insert state at the end of the |
| * day, the system clock is set back one second; if in leap-delete |
| * state, the system clock is set ahead one second. |
| */ |
| static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer) |
| { |
| enum hrtimer_restart res = HRTIMER_NORESTART; |
| |
| write_seqlock(&xtime_lock); |
| |
| switch (time_state) { |
| case TIME_OK: |
| break; |
| case TIME_INS: |
| xtime.tv_sec--; |
| wall_to_monotonic.tv_sec++; |
| time_state = TIME_OOP; |
| printk(KERN_NOTICE |
| "Clock: inserting leap second 23:59:60 UTC\n"); |
| hrtimer_add_expires_ns(&leap_timer, NSEC_PER_SEC); |
| res = HRTIMER_RESTART; |
| break; |
| case TIME_DEL: |
| xtime.tv_sec++; |
| time_tai--; |
| wall_to_monotonic.tv_sec--; |
| time_state = TIME_WAIT; |
| printk(KERN_NOTICE |
| "Clock: deleting leap second 23:59:59 UTC\n"); |
| break; |
| case TIME_OOP: |
| time_tai++; |
| time_state = TIME_WAIT; |
| /* fall through */ |
| case TIME_WAIT: |
| if (!(time_status & (STA_INS | STA_DEL))) |
| time_state = TIME_OK; |
| break; |
| } |
| update_vsyscall(&xtime, clock); |
| |
| write_sequnlock(&xtime_lock); |
| |
| return res; |
| } |
| |
| /* |
| * this routine handles the overflow of the microsecond field |
| * |
| * The tricky bits of code to handle the accurate clock support |
| * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame. |
| * They were originally developed for SUN and DEC kernels. |
| * All the kudos should go to Dave for this stuff. |
| */ |
| void second_overflow(void) |
| { |
| s64 delta; |
| |
| /* Bump the maxerror field */ |
| time_maxerror += MAXFREQ / NSEC_PER_USEC; |
| if (time_maxerror > NTP_PHASE_LIMIT) { |
| time_maxerror = NTP_PHASE_LIMIT; |
| time_status |= STA_UNSYNC; |
| } |
| |
| /* |
| * Compute the phase adjustment for the next second. The offset is |
| * reduced by a fixed factor times the time constant. |
| */ |
| tick_length = tick_length_base; |
| |
| delta = shift_right(time_offset, SHIFT_PLL + time_constant); |
| time_offset -= delta; |
| tick_length += delta; |
| |
| if (!time_adjust) |
| return; |
| |
| if (time_adjust > MAX_TICKADJ) { |
| time_adjust -= MAX_TICKADJ; |
| tick_length += MAX_TICKADJ_SCALED; |
| return; |
| } |
| |
| if (time_adjust < -MAX_TICKADJ) { |
| time_adjust += MAX_TICKADJ; |
| tick_length -= MAX_TICKADJ_SCALED; |
| return; |
| } |
| |
| tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ) |
| << NTP_SCALE_SHIFT; |
| time_adjust = 0; |
| } |
| |
| #ifdef CONFIG_GENERIC_CMOS_UPDATE |
| |
| /* Disable the cmos update - used by virtualization and embedded */ |
| int no_sync_cmos_clock __read_mostly; |
| |
| static void sync_cmos_clock(struct work_struct *work); |
| |
| static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock); |
| |
| static void sync_cmos_clock(struct work_struct *work) |
| { |
| struct timespec now, next; |
| int fail = 1; |
| |
| /* |
| * If we have an externally synchronized Linux clock, then update |
| * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be |
| * called as close as possible to 500 ms before the new second starts. |
| * This code is run on a timer. If the clock is set, that timer |
| * may not expire at the correct time. Thus, we adjust... |
| */ |
| if (!ntp_synced()) { |
| /* |
| * Not synced, exit, do not restart a timer (if one is |
| * running, let it run out). |
| */ |
| return; |
| } |
| |
| getnstimeofday(&now); |
| if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) |
| fail = update_persistent_clock(now); |
| |
| next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec - (TICK_NSEC / 2); |
| if (next.tv_nsec <= 0) |
| next.tv_nsec += NSEC_PER_SEC; |
| |
| if (!fail) |
| next.tv_sec = 659; |
| else |
| next.tv_sec = 0; |
| |
| if (next.tv_nsec >= NSEC_PER_SEC) { |
| next.tv_sec++; |
| next.tv_nsec -= NSEC_PER_SEC; |
| } |
| schedule_delayed_work(&sync_cmos_work, timespec_to_jiffies(&next)); |
| } |
| |
| static void notify_cmos_timer(void) |
| { |
| if (!no_sync_cmos_clock) |
| schedule_delayed_work(&sync_cmos_work, 0); |
| } |
| |
| #else |
| static inline void notify_cmos_timer(void) { } |
| #endif |
| |
| /* |
| * Start the leap seconds timer: |
| */ |
| static inline void ntp_start_leap_timer(struct timespec *ts) |
| { |
| long now = ts->tv_sec; |
| |
| if (time_status & STA_INS) { |
| time_state = TIME_INS; |
| now += 86400 - now % 86400; |
| hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS); |
| |
| return; |
| } |
| |
| if (time_status & STA_DEL) { |
| time_state = TIME_DEL; |
| now += 86400 - (now + 1) % 86400; |
| hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS); |
| } |
| } |
| |
| /* |
| * Propagate a new txc->status value into the NTP state: |
| */ |
| static inline void process_adj_status(struct timex *txc, struct timespec *ts) |
| { |
| if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) { |
| time_state = TIME_OK; |
| time_status = STA_UNSYNC; |
| } |
| /* only set allowed bits */ |
| time_status &= STA_RONLY; |
| |
| /* |
| * If we turn on PLL adjustments then reset the |
| * reference time to current time. |
| */ |
| if (!(time_status & STA_PLL) && (txc->status & STA_PLL)) |
| time_reftime = xtime.tv_sec; |
| |
| time_status |= txc->status & ~STA_RONLY; |
| |
| switch (time_state) { |
| case TIME_OK: |
| ntp_start_leap_timer(ts); |
| break; |
| case TIME_INS: |
| case TIME_DEL: |
| time_state = TIME_OK; |
| ntp_start_leap_timer(ts); |
| case TIME_WAIT: |
| if (!(time_status & (STA_INS | STA_DEL))) |
| time_state = TIME_OK; |
| break; |
| case TIME_OOP: |
| hrtimer_restart(&leap_timer); |
| break; |
| } |
| } |
| /* |
| * Called with the xtime lock held, so we can access and modify |
| * all the global NTP state: |
| */ |
| static inline void process_adjtimex_modes(struct timex *txc, struct timespec *ts) |
| { |
| if (txc->modes & ADJ_STATUS) |
| process_adj_status(txc, ts); |
| |
| if (txc->modes & ADJ_NANO) |
| time_status |= STA_NANO; |
| |
| if (txc->modes & ADJ_MICRO) |
| time_status &= ~STA_NANO; |
| |
| if (txc->modes & ADJ_FREQUENCY) { |
| time_freq = txc->freq * PPM_SCALE; |
| time_freq = min(time_freq, MAXFREQ_SCALED); |
| time_freq = max(time_freq, -MAXFREQ_SCALED); |
| } |
| |
| if (txc->modes & ADJ_MAXERROR) |
| time_maxerror = txc->maxerror; |
| |
| if (txc->modes & ADJ_ESTERROR) |
| time_esterror = txc->esterror; |
| |
| if (txc->modes & ADJ_TIMECONST) { |
| time_constant = txc->constant; |
| if (!(time_status & STA_NANO)) |
| time_constant += 4; |
| time_constant = min(time_constant, (long)MAXTC); |
| time_constant = max(time_constant, 0l); |
| } |
| |
| if (txc->modes & ADJ_TAI && txc->constant > 0) |
| time_tai = txc->constant; |
| |
| if (txc->modes & ADJ_OFFSET) |
| ntp_update_offset(txc->offset); |
| |
| if (txc->modes & ADJ_TICK) |
| tick_usec = txc->tick; |
| |
| if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET)) |
| ntp_update_frequency(); |
| } |
| |
| /* |
| * adjtimex mainly allows reading (and writing, if superuser) of |
| * kernel time-keeping variables. used by xntpd. |
| */ |
| int do_adjtimex(struct timex *txc) |
| { |
| struct timespec ts; |
| int result; |
| |
| /* Validate the data before disabling interrupts */ |
| if (txc->modes & ADJ_ADJTIME) { |
| /* singleshot must not be used with any other mode bits */ |
| if (!(txc->modes & ADJ_OFFSET_SINGLESHOT)) |
| return -EINVAL; |
| if (!(txc->modes & ADJ_OFFSET_READONLY) && |
| !capable(CAP_SYS_TIME)) |
| return -EPERM; |
| } else { |
| /* In order to modify anything, you gotta be super-user! */ |
| if (txc->modes && !capable(CAP_SYS_TIME)) |
| return -EPERM; |
| |
| /* |
| * if the quartz is off by more than 10% then |
| * something is VERY wrong! |
| */ |
| if (txc->modes & ADJ_TICK && |
| (txc->tick < 900000/USER_HZ || |
| txc->tick > 1100000/USER_HZ)) |
| return -EINVAL; |
| |
| if (txc->modes & ADJ_STATUS && time_state != TIME_OK) |
| hrtimer_cancel(&leap_timer); |
| } |
| |
| getnstimeofday(&ts); |
| |
| write_seqlock_irq(&xtime_lock); |
| |
| if (txc->modes & ADJ_ADJTIME) { |
| long save_adjust = time_adjust; |
| |
| if (!(txc->modes & ADJ_OFFSET_READONLY)) { |
| /* adjtime() is independent from ntp_adjtime() */ |
| time_adjust = txc->offset; |
| ntp_update_frequency(); |
| } |
| txc->offset = save_adjust; |
| } else { |
| |
| /* If there are input parameters, then process them: */ |
| if (txc->modes) |
| process_adjtimex_modes(txc, &ts); |
| |
| txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ, |
| NTP_SCALE_SHIFT); |
| if (!(time_status & STA_NANO)) |
| txc->offset /= NSEC_PER_USEC; |
| } |
| |
| result = time_state; /* mostly `TIME_OK' */ |
| if (time_status & (STA_UNSYNC|STA_CLOCKERR)) |
| result = TIME_ERROR; |
| |
| txc->freq = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) * |
| PPM_SCALE_INV, NTP_SCALE_SHIFT); |
| txc->maxerror = time_maxerror; |
| txc->esterror = time_esterror; |
| txc->status = time_status; |
| txc->constant = time_constant; |
| txc->precision = 1; |
| txc->tolerance = MAXFREQ_SCALED / PPM_SCALE; |
| txc->tick = tick_usec; |
| txc->tai = time_tai; |
| |
| /* PPS is not implemented, so these are zero */ |
| txc->ppsfreq = 0; |
| txc->jitter = 0; |
| txc->shift = 0; |
| txc->stabil = 0; |
| txc->jitcnt = 0; |
| txc->calcnt = 0; |
| txc->errcnt = 0; |
| txc->stbcnt = 0; |
| |
| write_sequnlock_irq(&xtime_lock); |
| |
| txc->time.tv_sec = ts.tv_sec; |
| txc->time.tv_usec = ts.tv_nsec; |
| if (!(time_status & STA_NANO)) |
| txc->time.tv_usec /= NSEC_PER_USEC; |
| |
| notify_cmos_timer(); |
| |
| return result; |
| } |
| |
| static int __init ntp_tick_adj_setup(char *str) |
| { |
| ntp_tick_adj = simple_strtol(str, NULL, 0); |
| ntp_tick_adj <<= NTP_SCALE_SHIFT; |
| |
| return 1; |
| } |
| |
| __setup("ntp_tick_adj=", ntp_tick_adj_setup); |
| |
| void __init ntp_init(void) |
| { |
| ntp_clear(); |
| hrtimer_init(&leap_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS); |
| leap_timer.function = ntp_leap_second; |
| } |