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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include "ntp_internal.h"#include "timekeeping_internal.h"
/** * struct ntp_data - Structure holding all NTP related state * @tick_usec: USER_HZ period in microseconds * @tick_length: Adjusted tick length * @tick_length_base: Base value for @tick_length * @time_state: State of the clock synchronization * @time_status: Clock status bits * @time_offset: Time adjustment in nanoseconds * @time_constant: PLL time constant * @time_maxerror: Maximum error in microseconds holding the NTP sync distance * (NTP dispersion + delay / 2) * @time_esterror: Estimated error in microseconds holding NTP dispersion * @time_freq: Frequency offset scaled nsecs/secs * @time_reftime: Time at last adjustment in seconds * @time_adjust: Adjustment value * @ntp_tick_adj: Constant boot-param configurable NTP tick adjustment (upscaled) * @ntp_next_leap_sec: Second value of the next pending leapsecond, or TIME64_MAX if no leap * * @pps_valid: PPS signal watchdog counter * @pps_tf: PPS phase median filter * @pps_jitter: PPS current jitter in nanoseconds * @pps_fbase: PPS beginning of the last freq interval * @pps_shift: PPS current interval duration in seconds (shift value) * @pps_intcnt: PPS interval counter * @pps_freq: PPS frequency offset in scaled ns/s * @pps_stabil: PPS current stability in scaled ns/s * @pps_calcnt: PPS monitor: calibration intervals * @pps_jitcnt: PPS monitor: jitter limit exceeded * @pps_stbcnt: PPS monitor: stability limit exceeded * @pps_errcnt: PPS monitor: calibration errors * * Protected by the timekeeping locks. */struct ntp_data { unsigned long tick_usec; u64 tick_length; u64 tick_length_base; int time_state; int time_status; s64 time_offset; long time_constant; long time_maxerror; long time_esterror; s64 time_freq; time64_t time_reftime; long time_adjust; s64 ntp_tick_adj; time64_t ntp_next_leap_sec;#ifdef CONFIG_NTP_PPS int pps_valid; long pps_tf[3]; long pps_jitter; struct timespec64 pps_fbase; int pps_shift; int pps_intcnt; s64 pps_freq; long pps_stabil; long pps_calcnt; long pps_jitcnt; long pps_stbcnt; long pps_errcnt;#endif};
static struct ntp_data tk_ntp_data[TIMEKEEPERS_MAX] = { [ 0 ... TIMEKEEPERS_MAX - 1 ] = { .tick_usec = USER_TICK_USEC, .time_state = TIME_OK, .time_status = STA_UNSYNC, .time_constant = 2, .time_maxerror = NTP_PHASE_LIMIT, .time_esterror = NTP_PHASE_LIMIT, .ntp_next_leap_sec = TIME64_MAX, },};
#define SECS_PER_DAY 86400#define MAX_TICKADJ 500LL /* usecs */#define MAX_TICKADJ_SCALED \ (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)#define MAX_TAI_OFFSET 100000
#ifdef CONFIG_NTP_PPS
/* * The following variables are used when a pulse-per-second (PPS) signal * is available. They establish the engineering parameters of the clock * discipline loop when controlled by the PPS signal. */#define PPS_VALID 10 /* PPS signal watchdog max (s) */#define PPS_POPCORN 4 /* popcorn spike threshold (shift) */#define PPS_INTMIN 2 /* min freq interval (s) (shift) */#define PPS_INTMAX 8 /* max freq interval (s) (shift) */#define PPS_INTCOUNT 4 /* number of consecutive good intervals to increase pps_shift or consecutive bad intervals to decrease it */#define PPS_MAXWANDER 100000 /* max PPS freq wander (ns/s) */
/* * PPS kernel consumer compensates the whole phase error immediately. * Otherwise, reduce the offset by a fixed factor times the time constant. */static inline s64 ntp_offset_chunk(struct ntp_data *ntpdata, s64 offset){ if (ntpdata->time_status & STA_PPSTIME && ntpdata->time_status & STA_PPSSIGNAL) return offset; else return shift_right(offset, SHIFT_PLL + ntpdata->time_constant);}
static inline void pps_reset_freq_interval(struct ntp_data *ntpdata){ /* The PPS calibration interval may end surprisingly early */ ntpdata->pps_shift = PPS_INTMIN; ntpdata->pps_intcnt = 0;}
/** * pps_clear - Clears the PPS state variables * @ntpdata: Pointer to ntp data */static inline void pps_clear(struct ntp_data *ntpdata){ pps_reset_freq_interval(ntpdata); ntpdata->pps_tf[0] = 0; ntpdata->pps_tf[1] = 0; ntpdata->pps_tf[2] = 0; ntpdata->pps_fbase.tv_sec = ntpdata->pps_fbase.tv_nsec = 0; ntpdata->pps_freq = 0;}
/* * Decrease pps_valid to indicate that another second has passed since the * last PPS signal. When it reaches 0, indicate that PPS signal is missing. */static inline void pps_dec_valid(struct ntp_data *ntpdata){ if (ntpdata->pps_valid > 0) { ntpdata->pps_valid--; } else { ntpdata->time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR); pps_clear(ntpdata); }}
static inline void pps_set_freq(struct ntp_data *ntpdata){ ntpdata->pps_freq = ntpdata->time_freq;}
static inline bool is_error_status(int status){ return (status & (STA_UNSYNC|STA_CLOCKERR)) /* * PPS signal lost when either PPS time or PPS frequency * synchronization requested */ || ((status & (STA_PPSFREQ|STA_PPSTIME)) && !(status & STA_PPSSIGNAL)) /* * PPS jitter exceeded when PPS time synchronization * requested */ || ((status & (STA_PPSTIME|STA_PPSJITTER)) == (STA_PPSTIME|STA_PPSJITTER)) /* * PPS wander exceeded or calibration error when PPS * frequency synchronization requested */ || ((status & STA_PPSFREQ) && (status & (STA_PPSWANDER|STA_PPSERROR)));}
static inline void pps_fill_timex(struct ntp_data *ntpdata, struct __kernel_timex *txc){ txc->ppsfreq = shift_right((ntpdata->pps_freq >> PPM_SCALE_INV_SHIFT) * PPM_SCALE_INV, NTP_SCALE_SHIFT); txc->jitter = ntpdata->pps_jitter; if (!(ntpdata->time_status & STA_NANO)) txc->jitter = ntpdata->pps_jitter / NSEC_PER_USEC; txc->shift = ntpdata->pps_shift; txc->stabil = ntpdata->pps_stabil; txc->jitcnt = ntpdata->pps_jitcnt; txc->calcnt = ntpdata->pps_calcnt; txc->errcnt = ntpdata->pps_errcnt; txc->stbcnt = ntpdata->pps_stbcnt;}
#else /* !CONFIG_NTP_PPS */
static inline s64 ntp_offset_chunk(struct ntp_data *ntpdata, s64 offset){ return shift_right(offset, SHIFT_PLL + ntpdata->time_constant);}
static inline void pps_reset_freq_interval(struct ntp_data *ntpdata) {}static inline void pps_clear(struct ntp_data *ntpdata) {}static inline void pps_dec_valid(struct ntp_data *ntpdata) {}static inline void pps_set_freq(struct ntp_data *ntpdata) {}
static inline bool is_error_status(int status){ return status & (STA_UNSYNC|STA_CLOCKERR);}
static inline void pps_fill_timex(struct ntp_data *ntpdata, struct __kernel_timex *txc){ /* 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;}
#endif /* CONFIG_NTP_PPS */
/* * Update tick_length and tick_length_base, based on tick_usec, ntp_tick_adj and * time_freq: */static void ntp_update_frequency(struct ntp_data *ntpdata){ u64 second_length, new_base, tick_usec = (u64)ntpdata->tick_usec;
second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << NTP_SCALE_SHIFT;
second_length += ntpdata->ntp_tick_adj; second_length += ntpdata->time_freq;
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: */ ntpdata->tick_length += new_base - ntpdata->tick_length_base; ntpdata->tick_length_base = new_base;}
static inline s64 ntp_update_offset_fll(struct ntp_data *ntpdata, s64 offset64, long secs){ ntpdata->time_status &= ~STA_MODE;
if (secs < MINSEC) return 0;
if (!(ntpdata->time_status & STA_FLL) && (secs <= MAXSEC)) return 0;
ntpdata->time_status |= STA_MODE;
return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);}
static void ntp_update_offset(struct ntp_data *ntpdata, long offset){ s64 freq_adj, offset64; long secs, real_secs;
if (!(ntpdata->time_status & STA_PLL)) return;
if (!(ntpdata->time_status & STA_NANO)) { /* Make sure the multiplication below won't overflow */ offset = clamp(offset, -USEC_PER_SEC, USEC_PER_SEC); offset *= NSEC_PER_USEC; }
/* Scale the phase adjustment and clamp to the operating range. */ offset = clamp(offset, -MAXPHASE, MAXPHASE);
/* * Select how the frequency is to be controlled * and in which mode (PLL or FLL). */ real_secs = ktime_get_ntp_seconds(ntpdata - tk_ntp_data); secs = (long)(real_secs - ntpdata->time_reftime); if (unlikely(ntpdata->time_status & STA_FREQHOLD)) secs = 0;
ntpdata->time_reftime = real_secs;
offset64 = offset; freq_adj = ntp_update_offset_fll(ntpdata, offset64, secs);
/* * Clamp update interval to reduce PLL gain with low * sampling rate (e.g. intermittent network connection) * to avoid instability. */ if (unlikely(secs > 1 << (SHIFT_PLL + 1 + ntpdata->time_constant))) secs = 1 << (SHIFT_PLL + 1 + ntpdata->time_constant);
freq_adj += (offset64 * secs) << (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + ntpdata->time_constant));
freq_adj = min(freq_adj + ntpdata->time_freq, MAXFREQ_SCALED);
ntpdata->time_freq = max(freq_adj, -MAXFREQ_SCALED);
ntpdata->time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);}
static void __ntp_clear(struct ntp_data *ntpdata){ /* Stop active adjtime() */ ntpdata->time_adjust = 0; ntpdata->time_status |= STA_UNSYNC; ntpdata->time_maxerror = NTP_PHASE_LIMIT; ntpdata->time_esterror = NTP_PHASE_LIMIT;
ntp_update_frequency(ntpdata);
ntpdata->tick_length = ntpdata->tick_length_base; ntpdata->time_offset = 0;
ntpdata->ntp_next_leap_sec = TIME64_MAX; /* Clear PPS state variables */ pps_clear(ntpdata);}
/** * ntp_clear - Clears the NTP state variables * @tkid: Timekeeper ID to be able to select proper ntp data array member */void ntp_clear(unsigned int tkid){ __ntp_clear(&tk_ntp_data[tkid]);}
u64 ntp_tick_length(unsigned int tkid){ return tk_ntp_data[tkid].tick_length;}
/** * ntp_get_next_leap - Returns the next leapsecond in CLOCK_REALTIME ktime_t * @tkid: Timekeeper ID * * Returns: For @tkid == TIMEKEEPER_CORE this provides the time of the next * leap second against CLOCK_REALTIME in a ktime_t format if a * leap second is pending. KTIME_MAX otherwise. */ktime_t ntp_get_next_leap(unsigned int tkid){ struct ntp_data *ntpdata = &tk_ntp_data[TIMEKEEPER_CORE];
if (tkid != TIMEKEEPER_CORE) return KTIME_MAX;
if ((ntpdata->time_state == TIME_INS) && (ntpdata->time_status & STA_INS)) return ktime_set(ntpdata->ntp_next_leap_sec, 0);
return KTIME_MAX;}
/* * 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. * * Also handles leap second processing, and returns leap offset */int second_overflow(unsigned int tkid, time64_t secs){ struct ntp_data *ntpdata = &tk_ntp_data[tkid]; s64 delta; int leap = 0; s32 rem;
/* * 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. */ switch (ntpdata->time_state) { case TIME_OK: if (ntpdata->time_status & STA_INS) { ntpdata->time_state = TIME_INS; div_s64_rem(secs, SECS_PER_DAY, &rem); ntpdata->ntp_next_leap_sec = secs + SECS_PER_DAY - rem; } else if (ntpdata->time_status & STA_DEL) { ntpdata->time_state = TIME_DEL; div_s64_rem(secs + 1, SECS_PER_DAY, &rem); ntpdata->ntp_next_leap_sec = secs + SECS_PER_DAY - rem; } break; case TIME_INS: if (!(ntpdata->time_status & STA_INS)) { ntpdata->ntp_next_leap_sec = TIME64_MAX; ntpdata->time_state = TIME_OK; } else if (secs == ntpdata->ntp_next_leap_sec) { leap = -1; ntpdata->time_state = TIME_OOP; pr_notice("Clock: inserting leap second 23:59:60 UTC\n"); } break; case TIME_DEL: if (!(ntpdata->time_status & STA_DEL)) { ntpdata->ntp_next_leap_sec = TIME64_MAX; ntpdata->time_state = TIME_OK; } else if (secs == ntpdata->ntp_next_leap_sec) { leap = 1; ntpdata->ntp_next_leap_sec = TIME64_MAX; ntpdata->time_state = TIME_WAIT; pr_notice("Clock: deleting leap second 23:59:59 UTC\n"); } break; case TIME_OOP: ntpdata->ntp_next_leap_sec = TIME64_MAX; ntpdata->time_state = TIME_WAIT; break; case TIME_WAIT: if (!(ntpdata->time_status & (STA_INS | STA_DEL))) ntpdata->time_state = TIME_OK; break; }
/* Bump the maxerror field */ ntpdata->time_maxerror += MAXFREQ / NSEC_PER_USEC; if (ntpdata->time_maxerror > NTP_PHASE_LIMIT) { ntpdata->time_maxerror = NTP_PHASE_LIMIT; ntpdata->time_status |= STA_UNSYNC; }
/* Compute the phase adjustment for the next second */ ntpdata->tick_length = ntpdata->tick_length_base;
delta = ntp_offset_chunk(ntpdata, ntpdata->time_offset); ntpdata->time_offset -= delta; ntpdata->tick_length += delta;
/* Check PPS signal */ pps_dec_valid(ntpdata);
if (!ntpdata->time_adjust) goto out;
if (ntpdata->time_adjust > MAX_TICKADJ) { ntpdata->time_adjust -= MAX_TICKADJ; ntpdata->tick_length += MAX_TICKADJ_SCALED; goto out; }
if (ntpdata->time_adjust < -MAX_TICKADJ) { ntpdata->time_adjust += MAX_TICKADJ; ntpdata->tick_length -= MAX_TICKADJ_SCALED; goto out; }
ntpdata->tick_length += (s64)(ntpdata->time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ) << NTP_SCALE_SHIFT; ntpdata->time_adjust = 0;
out: return leap;}
#if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC)static void sync_hw_clock(struct work_struct *work);static DECLARE_WORK(sync_work, sync_hw_clock);static struct hrtimer sync_hrtimer;#define SYNC_PERIOD_NS (11ULL * 60 * NSEC_PER_SEC)
static enum hrtimer_restart sync_timer_callback(struct hrtimer *timer){ queue_work(system_freezable_power_efficient_wq, &sync_work);
return HRTIMER_NORESTART;}
static void sched_sync_hw_clock(unsigned long offset_nsec, bool retry){ ktime_t exp = ktime_set(ktime_get_real_seconds(), 0);
if (retry) exp = ktime_add_ns(exp, 2ULL * NSEC_PER_SEC - offset_nsec); else exp = ktime_add_ns(exp, SYNC_PERIOD_NS - offset_nsec);
hrtimer_start(&sync_hrtimer, exp, HRTIMER_MODE_ABS);}
/* * Check whether @now is correct versus the required time to update the RTC * and calculate the value which needs to be written to the RTC so that the * next seconds increment of the RTC after the write is aligned with the next * seconds increment of clock REALTIME. * * tsched t1 write(t2.tv_sec - 1sec)) t2 RTC increments seconds * * t2.tv_nsec == 0 * tsched = t2 - set_offset_nsec * newval = t2 - NSEC_PER_SEC * * ==> neval = tsched + set_offset_nsec - NSEC_PER_SEC * * As the execution of this code is not guaranteed to happen exactly at * tsched this allows it to happen within a fuzzy region: * * abs(now - tsched) < FUZZ * * If @now is not inside the allowed window the function returns false. */static inline bool rtc_tv_nsec_ok(unsigned long set_offset_nsec, struct timespec64 *to_set, const struct timespec64 *now){ /* Allowed error in tv_nsec, arbitrarily set to 5 jiffies in ns. */ const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5; struct timespec64 delay = {.tv_sec = -1, .tv_nsec = set_offset_nsec};
*to_set = timespec64_add(*now, delay);
if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) { to_set->tv_nsec = 0; return true; }
if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) { to_set->tv_sec++; to_set->tv_nsec = 0; return true; } return false;}
#ifdef CONFIG_GENERIC_CMOS_UPDATEint __weak update_persistent_clock64(struct timespec64 now64){ return -ENODEV;}#elsestatic inline int update_persistent_clock64(struct timespec64 now64){ return -ENODEV;}#endif
#ifdef CONFIG_RTC_SYSTOHC/* Save NTP synchronized time to the RTC */static int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec){ struct rtc_device *rtc; struct rtc_time tm; int err = -ENODEV;
rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE); if (!rtc) return -ENODEV;
if (!rtc->ops || !rtc->ops->set_time) goto out_close;
/* First call might not have the correct offset */ if (*offset_nsec == rtc->set_offset_nsec) { rtc_time64_to_tm(to_set->tv_sec, &tm); err = rtc_set_time(rtc, &tm); } else { /* Store the update offset and let the caller try again */ *offset_nsec = rtc->set_offset_nsec; err = -EAGAIN; }out_close: rtc_class_close(rtc); return err;}#elsestatic inline int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec){ return -ENODEV;}#endif
/** * ntp_synced - Tells whether the NTP status is not UNSYNC * Returns: true if not UNSYNC, false otherwise */static inline bool ntp_synced(void){ return !(tk_ntp_data[TIMEKEEPER_CORE].time_status & STA_UNSYNC);}
/* * If we have an externally synchronized Linux clock, then update RTC clock * accordingly every ~11 minutes. Generally RTCs can only store second * precision, but many RTCs will adjust the phase of their second tick to * match the moment of update. This infrastructure arranges to call to the RTC * set at the correct moment to phase synchronize the RTC second tick over * with the kernel clock. */static void sync_hw_clock(struct work_struct *work){ /* * The default synchronization offset is 500ms for the deprecated * update_persistent_clock64() under the assumption that it uses * the infamous CMOS clock (MC146818). */ static unsigned long offset_nsec = NSEC_PER_SEC / 2; struct timespec64 now, to_set; int res = -EAGAIN;
/* * Don't update if STA_UNSYNC is set and if ntp_notify_cmos_timer() * managed to schedule the work between the timer firing and the * work being able to rearm the timer. Wait for the timer to expire. */ if (!ntp_synced() || hrtimer_is_queued(&sync_hrtimer)) return;
ktime_get_real_ts64(&now); /* If @now is not in the allowed window, try again */ if (!rtc_tv_nsec_ok(offset_nsec, &to_set, &now)) goto rearm;
/* Take timezone adjusted RTCs into account */ if (persistent_clock_is_local) to_set.tv_sec -= (sys_tz.tz_minuteswest * 60);
/* Try the legacy RTC first. */ res = update_persistent_clock64(to_set); if (res != -ENODEV) goto rearm;
/* Try the RTC class */ res = update_rtc(&to_set, &offset_nsec); if (res == -ENODEV) return;rearm: sched_sync_hw_clock(offset_nsec, res != 0);}
void ntp_notify_cmos_timer(bool offset_set){ /* * If the time jumped (using ADJ_SETOFFSET) cancels sync timer, * which may have been running if the time was synchronized * prior to the ADJ_SETOFFSET call. */ if (offset_set) hrtimer_cancel(&sync_hrtimer);
/* * When the work is currently executed but has not yet the timer * rearmed this queues the work immediately again. No big issue, * just a pointless work scheduled. */ if (ntp_synced() && !hrtimer_is_queued(&sync_hrtimer)) queue_work(system_freezable_power_efficient_wq, &sync_work);}
static void __init ntp_init_cmos_sync(void){ hrtimer_setup(&sync_hrtimer, sync_timer_callback, CLOCK_REALTIME, HRTIMER_MODE_ABS);}#else /* CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */static inline void __init ntp_init_cmos_sync(void) { }#endif /* !CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */
/* * Propagate a new txc->status value into the NTP state: */static inline void process_adj_status(struct ntp_data *ntpdata, const struct __kernel_timex *txc){ if ((ntpdata->time_status & STA_PLL) && !(txc->status & STA_PLL)) { ntpdata->time_state = TIME_OK; ntpdata->time_status = STA_UNSYNC; ntpdata->ntp_next_leap_sec = TIME64_MAX; /* Restart PPS frequency calibration */ pps_reset_freq_interval(ntpdata); }
/* * If we turn on PLL adjustments then reset the * reference time to current time. */ if (!(ntpdata->time_status & STA_PLL) && (txc->status & STA_PLL)) ntpdata->time_reftime = ktime_get_ntp_seconds(ntpdata - tk_ntp_data);
/* only set allowed bits */ ntpdata->time_status &= STA_RONLY; ntpdata->time_status |= txc->status & ~STA_RONLY;}
static inline void process_adjtimex_modes(struct ntp_data *ntpdata, const struct __kernel_timex *txc, s32 *time_tai){ if (txc->modes & ADJ_STATUS) process_adj_status(ntpdata, txc);
if (txc->modes & ADJ_NANO) ntpdata->time_status |= STA_NANO;
if (txc->modes & ADJ_MICRO) ntpdata->time_status &= ~STA_NANO;
if (txc->modes & ADJ_FREQUENCY) { ntpdata->time_freq = txc->freq * PPM_SCALE; ntpdata->time_freq = min(ntpdata->time_freq, MAXFREQ_SCALED); ntpdata->time_freq = max(ntpdata->time_freq, -MAXFREQ_SCALED); /* Update pps_freq */ pps_set_freq(ntpdata); }
if (txc->modes & ADJ_MAXERROR) ntpdata->time_maxerror = clamp(txc->maxerror, 0, NTP_PHASE_LIMIT);
if (txc->modes & ADJ_ESTERROR) ntpdata->time_esterror = clamp(txc->esterror, 0, NTP_PHASE_LIMIT);
if (txc->modes & ADJ_TIMECONST) { ntpdata->time_constant = clamp(txc->constant, 0, MAXTC); if (!(ntpdata->time_status & STA_NANO)) ntpdata->time_constant += 4; ntpdata->time_constant = clamp(ntpdata->time_constant, 0, MAXTC); }
if (txc->modes & ADJ_TAI && txc->constant >= 0 && txc->constant <= MAX_TAI_OFFSET) *time_tai = txc->constant;
if (txc->modes & ADJ_OFFSET) ntp_update_offset(ntpdata, txc->offset);
if (txc->modes & ADJ_TICK) ntpdata->tick_usec = txc->tick;
if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET)) ntp_update_frequency(ntpdata);}
/* * adjtimex() mainly allows reading (and writing, if superuser) of * kernel time-keeping variables. used by xntpd. */int ntp_adjtimex(unsigned int tkid, struct __kernel_timex *txc, const struct timespec64 *ts, s32 *time_tai, struct audit_ntp_data *ad){ struct ntp_data *ntpdata = &tk_ntp_data[tkid]; int result;
if (txc->modes & ADJ_ADJTIME) { long save_adjust = ntpdata->time_adjust;
if (!(txc->modes & ADJ_OFFSET_READONLY)) { /* adjtime() is independent from ntp_adjtime() */ ntpdata->time_adjust = txc->offset; ntp_update_frequency(ntpdata);
audit_ntp_set_old(ad, AUDIT_NTP_ADJUST, save_adjust); audit_ntp_set_new(ad, AUDIT_NTP_ADJUST, ntpdata->time_adjust); } txc->offset = save_adjust; } else { /* If there are input parameters, then process them: */ if (txc->modes) { audit_ntp_set_old(ad, AUDIT_NTP_OFFSET, ntpdata->time_offset); audit_ntp_set_old(ad, AUDIT_NTP_FREQ, ntpdata->time_freq); audit_ntp_set_old(ad, AUDIT_NTP_STATUS, ntpdata->time_status); audit_ntp_set_old(ad, AUDIT_NTP_TAI, *time_tai); audit_ntp_set_old(ad, AUDIT_NTP_TICK, ntpdata->tick_usec);
process_adjtimex_modes(ntpdata, txc, time_tai);
audit_ntp_set_new(ad, AUDIT_NTP_OFFSET, ntpdata->time_offset); audit_ntp_set_new(ad, AUDIT_NTP_FREQ, ntpdata->time_freq); audit_ntp_set_new(ad, AUDIT_NTP_STATUS, ntpdata->time_status); audit_ntp_set_new(ad, AUDIT_NTP_TAI, *time_tai); audit_ntp_set_new(ad, AUDIT_NTP_TICK, ntpdata->tick_usec); }
txc->offset = shift_right(ntpdata->time_offset * NTP_INTERVAL_FREQ, NTP_SCALE_SHIFT); if (!(ntpdata->time_status & STA_NANO)) txc->offset = div_s64(txc->offset, NSEC_PER_USEC); }
result = ntpdata->time_state; if (is_error_status(ntpdata->time_status)) result = TIME_ERROR;
txc->freq = shift_right((ntpdata->time_freq >> PPM_SCALE_INV_SHIFT) * PPM_SCALE_INV, NTP_SCALE_SHIFT); txc->maxerror = ntpdata->time_maxerror; txc->esterror = ntpdata->time_esterror; txc->status = ntpdata->time_status; txc->constant = ntpdata->time_constant; txc->precision = 1; txc->tolerance = MAXFREQ_SCALED / PPM_SCALE; txc->tick = ntpdata->tick_usec; txc->tai = *time_tai;
/* Fill PPS status fields */ pps_fill_timex(ntpdata, txc);
txc->time.tv_sec = ts->tv_sec; txc->time.tv_usec = ts->tv_nsec; if (!(ntpdata->time_status & STA_NANO)) txc->time.tv_usec = ts->tv_nsec / NSEC_PER_USEC;
/* Handle leapsec adjustments */ if (unlikely(ts->tv_sec >= ntpdata->ntp_next_leap_sec)) { if ((ntpdata->time_state == TIME_INS) && (ntpdata->time_status & STA_INS)) { result = TIME_OOP; txc->tai++; txc->time.tv_sec--; } if ((ntpdata->time_state == TIME_DEL) && (ntpdata->time_status & STA_DEL)) { result = TIME_WAIT; txc->tai--; txc->time.tv_sec++; } if ((ntpdata->time_state == TIME_OOP) && (ts->tv_sec == ntpdata->ntp_next_leap_sec)) result = TIME_WAIT; }
return result;}
#ifdef CONFIG_NTP_PPS
/* * struct pps_normtime is basically a struct timespec, but it is * semantically different (and it is the reason why it was invented): * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC) */struct pps_normtime { s64 sec; /* seconds */ long nsec; /* nanoseconds */};
/* * Normalize the timestamp so that nsec is in the * [ -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval */static inline struct pps_normtime pps_normalize_ts(struct timespec64 ts){ struct pps_normtime norm = { .sec = ts.tv_sec, .nsec = ts.tv_nsec };
if (norm.nsec > (NSEC_PER_SEC >> 1)) { norm.nsec -= NSEC_PER_SEC; norm.sec++; }
return norm;}
/* Get current phase correction and jitter */static inline long pps_phase_filter_get(struct ntp_data *ntpdata, long *jitter){ *jitter = ntpdata->pps_tf[0] - ntpdata->pps_tf[1]; if (*jitter < 0) *jitter = -*jitter;
/* TODO: test various filters */ return ntpdata->pps_tf[0];}
/* Add the sample to the phase filter */static inline void pps_phase_filter_add(struct ntp_data *ntpdata, long err){ ntpdata->pps_tf[2] = ntpdata->pps_tf[1]; ntpdata->pps_tf[1] = ntpdata->pps_tf[0]; ntpdata->pps_tf[0] = err;}
/* * Decrease frequency calibration interval length. It is halved after four * consecutive unstable intervals. */static inline void pps_dec_freq_interval(struct ntp_data *ntpdata){ if (--ntpdata->pps_intcnt <= -PPS_INTCOUNT) { ntpdata->pps_intcnt = -PPS_INTCOUNT; if (ntpdata->pps_shift > PPS_INTMIN) { ntpdata->pps_shift--; ntpdata->pps_intcnt = 0; } }}
/* * Increase frequency calibration interval length. It is doubled after * four consecutive stable intervals. */static inline void pps_inc_freq_interval(struct ntp_data *ntpdata){ if (++ntpdata->pps_intcnt >= PPS_INTCOUNT) { ntpdata->pps_intcnt = PPS_INTCOUNT; if (ntpdata->pps_shift < PPS_INTMAX) { ntpdata->pps_shift++; ntpdata->pps_intcnt = 0; } }}
/* * Update clock frequency based on MONOTONIC_RAW clock PPS signal * timestamps * * At the end of the calibration interval the difference between the * first and last MONOTONIC_RAW clock timestamps divided by the length * of the interval becomes the frequency update. If the interval was * too long, the data are discarded. * Returns the difference between old and new frequency values. */static long hardpps_update_freq(struct ntp_data *ntpdata, struct pps_normtime freq_norm){ long delta, delta_mod; s64 ftemp;
/* Check if the frequency interval was too long */ if (freq_norm.sec > (2 << ntpdata->pps_shift)) { ntpdata->time_status |= STA_PPSERROR; ntpdata->pps_errcnt++; pps_dec_freq_interval(ntpdata); printk_deferred(KERN_ERR "hardpps: PPSERROR: interval too long - %lld s\n", freq_norm.sec); return 0; }
/* * Here the raw frequency offset and wander (stability) is * calculated. If the wander is less than the wander threshold the * interval is increased; otherwise it is decreased. */ ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT, freq_norm.sec); delta = shift_right(ftemp - ntpdata->pps_freq, NTP_SCALE_SHIFT); ntpdata->pps_freq = ftemp; if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) { printk_deferred(KERN_WARNING "hardpps: PPSWANDER: change=%ld\n", delta); ntpdata->time_status |= STA_PPSWANDER; ntpdata->pps_stbcnt++; pps_dec_freq_interval(ntpdata); } else { /* Good sample */ pps_inc_freq_interval(ntpdata); }
/* * The stability metric is calculated as the average of recent * frequency changes, but is used only for performance monitoring */ delta_mod = delta; if (delta_mod < 0) delta_mod = -delta_mod; ntpdata->pps_stabil += (div_s64(((s64)delta_mod) << (NTP_SCALE_SHIFT - SHIFT_USEC), NSEC_PER_USEC) - ntpdata->pps_stabil) >> PPS_INTMIN;
/* If enabled, the system clock frequency is updated */ if ((ntpdata->time_status & STA_PPSFREQ) && !(ntpdata->time_status & STA_FREQHOLD)) { ntpdata->time_freq = ntpdata->pps_freq; ntp_update_frequency(ntpdata); }
return delta;}
/* Correct REALTIME clock phase error against PPS signal */static void hardpps_update_phase(struct ntp_data *ntpdata, long error){ long correction = -error; long jitter;
/* Add the sample to the median filter */ pps_phase_filter_add(ntpdata, correction); correction = pps_phase_filter_get(ntpdata, &jitter);
/* * Nominal jitter is due to PPS signal noise. If it exceeds the * threshold, the sample is discarded; otherwise, if so enabled, * the time offset is updated. */ if (jitter > (ntpdata->pps_jitter << PPS_POPCORN)) { printk_deferred(KERN_WARNING "hardpps: PPSJITTER: jitter=%ld, limit=%ld\n", jitter, (ntpdata->pps_jitter << PPS_POPCORN)); ntpdata->time_status |= STA_PPSJITTER; ntpdata->pps_jitcnt++; } else if (ntpdata->time_status & STA_PPSTIME) { /* Correct the time using the phase offset */ ntpdata->time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ); /* Cancel running adjtime() */ ntpdata->time_adjust = 0; } /* Update jitter */ ntpdata->pps_jitter += (jitter - ntpdata->pps_jitter) >> PPS_INTMIN;}
/* * __hardpps() - discipline CPU clock oscillator to external PPS signal * * This routine is called at each PPS signal arrival in order to * discipline the CPU clock oscillator to the PPS signal. It takes two * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former * is used to correct clock phase error and the latter is used to * correct the frequency. * * This code is based on David Mills's reference nanokernel * implementation. It was mostly rewritten but keeps the same idea. */void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts){ struct ntp_data *ntpdata = &tk_ntp_data[TIMEKEEPER_CORE]; struct pps_normtime pts_norm, freq_norm;
pts_norm = pps_normalize_ts(*phase_ts);
/* Clear the error bits, they will be set again if needed */ ntpdata->time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
/* indicate signal presence */ ntpdata->time_status |= STA_PPSSIGNAL; ntpdata->pps_valid = PPS_VALID;
/* * When called for the first time, just start the frequency * interval */ if (unlikely(ntpdata->pps_fbase.tv_sec == 0)) { ntpdata->pps_fbase = *raw_ts; return; }
/* Ok, now we have a base for frequency calculation */ freq_norm = pps_normalize_ts(timespec64_sub(*raw_ts, ntpdata->pps_fbase));
/* * Check that the signal is in the range * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it */ if ((freq_norm.sec == 0) || (freq_norm.nsec > MAXFREQ * freq_norm.sec) || (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) { ntpdata->time_status |= STA_PPSJITTER; /* Restart the frequency calibration interval */ ntpdata->pps_fbase = *raw_ts; printk_deferred(KERN_ERR "hardpps: PPSJITTER: bad pulse\n"); return; }
/* Signal is ok. Check if the current frequency interval is finished */ if (freq_norm.sec >= (1 << ntpdata->pps_shift)) { ntpdata->pps_calcnt++; /* Restart the frequency calibration interval */ ntpdata->pps_fbase = *raw_ts; hardpps_update_freq(ntpdata, freq_norm); }
hardpps_update_phase(ntpdata, pts_norm.nsec);
}#endif /* CONFIG_NTP_PPS */
static int __init ntp_tick_adj_setup(char *str){ int rc = kstrtos64(str, 0, &tk_ntp_data[TIMEKEEPER_CORE].ntp_tick_adj); if (rc) return rc;
tk_ntp_data[TIMEKEEPER_CORE].ntp_tick_adj <<= NTP_SCALE_SHIFT; return 1;}__setup("ntp_tick_adj=", ntp_tick_adj_setup);
void __init ntp_init(void){ for (int id = 0; id < TIMEKEEPERS_MAX; id++) __ntp_clear(tk_ntp_data + id); ntp_init_cmos_sync();}