diff options
Diffstat (limited to 'kernel/time/ntp.c')
| -rw-r--r-- | kernel/time/ntp.c | 453 |
1 files changed, 453 insertions, 0 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c new file mode 100644 index 0000000..8ff15e5 --- /dev/null +++ b/kernel/time/ntp.c @@ -0,0 +1,453 @@ +/* + * linux/kernel/time/ntp.c + * + * 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/mm.h> +#include <linux/time.h> +#include <linux/timex.h> +#include <linux/jiffies.h> +#include <linux/hrtimer.h> +#include <linux/capability.h> +#include <linux/math64.h> +#include <linux/clocksource.h> +#include <linux/workqueue.h> +#include <asm/timex.h> + +/* + * Timekeeping variables + */ +unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */ +unsigned long tick_nsec; /* ACTHZ period (nsec) */ +u64 tick_length; +static u64 tick_length_base; + +static struct hrtimer leap_timer; + +#define MAX_TICKADJ 500 /* microsecs */ +#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \ + NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ) + +/* + * phase-lock loop variables + */ +/* TIME_ERROR prevents overwriting the CMOS clock */ +static int time_state = TIME_OK; /* clock synchronization status */ +int time_status = STA_UNSYNC; /* clock status bits */ +static long time_tai; /* TAI offset (s) */ +static s64 time_offset; /* time adjustment (ns) */ +static long time_constant = 2; /* pll time constant */ +long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */ +long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */ +static s64 time_freq; /* frequency offset (scaled ns/s)*/ +static long time_reftime; /* time at last adjustment (s) */ +long time_adjust; +static long ntp_tick_adj; + +static void ntp_update_frequency(void) +{ + u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) + << NTP_SCALE_SHIFT; + second_length += (s64)ntp_tick_adj << NTP_SCALE_SHIFT; + second_length += time_freq; + + tick_length_base = second_length; + + tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT; + tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ); +} + +static void ntp_update_offset(long offset) +{ + long mtemp; + s64 freq_adj; + + 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). + */ + if (time_status & STA_FREQHOLD || time_reftime == 0) + time_reftime = xtime.tv_sec; + mtemp = xtime.tv_sec - time_reftime; + time_reftime = xtime.tv_sec; + + freq_adj = (s64)offset * mtemp; + freq_adj <<= NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant); + time_status &= ~STA_MODE; + if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) { + freq_adj += div_s64((s64)offset << (NTP_SCALE_SHIFT - SHIFT_FLL), + mtemp); + time_status |= STA_MODE; + } + freq_adj += time_freq; + freq_adj = min(freq_adj, MAXFREQ_SCALED); + time_freq = max(freq_adj, -MAXFREQ_SCALED); + + time_offset = div_s64((s64)offset << 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_irq(&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_irq(&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 time_adj; + + /* 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; + time_adj = shift_right(time_offset, SHIFT_PLL + time_constant); + time_offset -= time_adj; + tick_length += time_adj; + + if (unlikely(time_adjust)) { + if (time_adjust > MAX_TICKADJ) { + time_adjust -= MAX_TICKADJ; + tick_length += MAX_TICKADJ_SCALED; + } else if (time_adjust < -MAX_TICKADJ) { + time_adjust += MAX_TICKADJ; + tick_length -= MAX_TICKADJ_SCALED; + } else { + 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 + +/* 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% 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 there are input parameters, then process them */ + 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; + goto adj_done; + } + if (txc->modes) { + long sec; + + if (txc->modes & ADJ_STATUS) { + 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; + time_status |= txc->status & ~STA_RONLY; + + switch (time_state) { + case TIME_OK: + start_timer: + sec = ts.tv_sec; + if (time_status & STA_INS) { + time_state = TIME_INS; + sec += 86400 - sec % 86400; + hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS); + } else if (time_status & STA_DEL) { + time_state = TIME_DEL; + sec += 86400 - (sec + 1) % 86400; + hrtimer_start(&leap_timer, ktime_set(sec, 0), HRTIMER_MODE_ABS); + } + break; + case TIME_INS: + case TIME_DEL: + time_state = TIME_OK; + goto start_timer; + break; + case TIME_WAIT: + if (!(time_status & (STA_INS | STA_DEL))) + time_state = TIME_OK; + break; + case TIME_OOP: + hrtimer_restart(&leap_timer); + break; + } + } + + 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 = (s64)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(); + } + + txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ, + NTP_SCALE_SHIFT); + if (!(time_status & STA_NANO)) + txc->offset /= NSEC_PER_USEC; + +adj_done: + 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) * + (s64)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); + 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; +} |
