diff options
Diffstat (limited to 'kernel/time/ntp.c')
| -rw-r--r-- | kernel/time/ntp.c | 350 |
1 files changed, 350 insertions, 0 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c new file mode 100644 index 00000000000..47195fa0ec4 --- /dev/null +++ b/kernel/time/ntp.c @@ -0,0 +1,350 @@ +/* + * 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 <asm/div64.h> +#include <asm/timex.h> + +/* + * Timekeeping variables + */ +unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */ +unsigned long tick_nsec; /* ACTHZ period (nsec) */ +static u64 tick_length, tick_length_base; + +#define MAX_TICKADJ 500 /* microsecs */ +#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \ + TICK_LENGTH_SHIFT) / HZ) + +/* + * 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_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) */ +long time_freq; /* frequency offset (scaled ppm)*/ +static long time_reftime; /* time at last adjustment (s) */ +long time_adjust; + +#define CLOCK_TICK_OVERFLOW (LATCH * HZ - CLOCK_TICK_RATE) +#define CLOCK_TICK_ADJUST (((s64)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / \ + (s64)CLOCK_TICK_RATE) + +static void ntp_update_frequency(void) +{ + tick_length_base = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << TICK_LENGTH_SHIFT; + tick_length_base += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT; + tick_length_base += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC); + + do_div(tick_length_base, HZ); + + tick_nsec = tick_length_base >> TICK_LENGTH_SHIFT; +} + +/** + * 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; +} + +/* + * 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) +{ + long time_adj; + + /* Bump the maxerror field */ + time_maxerror += MAXFREQ >> SHIFT_USEC; + if (time_maxerror > NTP_PHASE_LIMIT) { + time_maxerror = NTP_PHASE_LIMIT; + time_status |= STA_UNSYNC; + } + + /* + * 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. The microtime() + * routine or external clock driver will insure that reported time is + * always monotonic. The ugly divides should be replaced. + */ + switch (time_state) { + case TIME_OK: + if (time_status & STA_INS) + time_state = TIME_INS; + else if (time_status & STA_DEL) + time_state = TIME_DEL; + break; + case TIME_INS: + if (xtime.tv_sec % 86400 == 0) { + xtime.tv_sec--; + wall_to_monotonic.tv_sec++; + /* + * The timer interpolator will make time change + * gradually instead of an immediate jump by one second + */ + time_interpolator_update(-NSEC_PER_SEC); + time_state = TIME_OOP; + clock_was_set(); + printk(KERN_NOTICE "Clock: inserting leap second " + "23:59:60 UTC\n"); + } + break; + case TIME_DEL: + if ((xtime.tv_sec + 1) % 86400 == 0) { + xtime.tv_sec++; + wall_to_monotonic.tv_sec--; + /* + * Use of time interpolator for a gradual change of + * time + */ + time_interpolator_update(NSEC_PER_SEC); + time_state = TIME_WAIT; + clock_was_set(); + printk(KERN_NOTICE "Clock: deleting leap second " + "23:59:59 UTC\n"); + } + break; + case TIME_OOP: + time_state = TIME_WAIT; + break; + case TIME_WAIT: + if (!(time_status & (STA_INS | STA_DEL))) + time_state = TIME_OK; + } + + /* + * 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 += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE); + + 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 { + time_adjust = 0; + tick_length += (s64)(time_adjust * NSEC_PER_USEC / + HZ) << TICK_LENGTH_SHIFT; + } + } +} + +/* + * Return how long ticks are at the moment, that is, how much time + * update_wall_time_one_tick will add to xtime next time we call it + * (assuming no calls to do_adjtimex in the meantime). + * The return value is in fixed-point nanoseconds shifted by the + * specified number of bits to the right of the binary point. + * This function has no side-effects. + */ +u64 current_tick_length(void) +{ + return tick_length; +} + + +void __attribute__ ((weak)) notify_arch_cmos_timer(void) +{ + return; +} + +/* adjtimex mainly allows reading (and writing, if superuser) of + * kernel time-keeping variables. used by xntpd. + */ +int do_adjtimex(struct timex *txc) +{ + long ltemp, mtemp, save_adjust; + s64 freq_adj, temp64; + int result; + + /* In order to modify anything, you gotta be super-user! */ + if (txc->modes && !capable(CAP_SYS_TIME)) + return -EPERM; + + /* Now we validate the data before disabling interrupts */ + + if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) + /* singleshot must not be used with any other mode bits */ + if (txc->modes != ADJ_OFFSET_SINGLESHOT) + return -EINVAL; + + if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET)) + /* adjustment Offset limited to +- .512 seconds */ + if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE ) + return -EINVAL; + + /* if the quartz is off by more than 10% something is VERY wrong ! */ + if (txc->modes & ADJ_TICK) + if (txc->tick < 900000/USER_HZ || + txc->tick > 1100000/USER_HZ) + return -EINVAL; + + write_seqlock_irq(&xtime_lock); + result = time_state; /* mostly `TIME_OK' */ + + /* Save for later - semantics of adjtime is to return old value */ + save_adjust = time_adjust; + +#if 0 /* STA_CLOCKERR is never set yet */ + time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */ +#endif + /* If there are input parameters, then process them */ + if (txc->modes) + { + if (txc->modes & ADJ_STATUS) /* only set allowed bits */ + time_status = (txc->status & ~STA_RONLY) | + (time_status & STA_RONLY); + + if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */ + if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) { + result = -EINVAL; + goto leave; + } + time_freq = ((s64)txc->freq * NSEC_PER_USEC) >> (SHIFT_USEC - SHIFT_NSEC); + } + + if (txc->modes & ADJ_MAXERROR) { + if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) { + result = -EINVAL; + goto leave; + } + time_maxerror = txc->maxerror; + } + + if (txc->modes & ADJ_ESTERROR) { + if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) { + result = -EINVAL; + goto leave; + } + time_esterror = txc->esterror; + } + + if (txc->modes & ADJ_TIMECONST) { /* p. 24 */ + if (txc->constant < 0) { /* NTP v4 uses values > 6 */ + result = -EINVAL; + goto leave; + } + time_constant = min(txc->constant + 4, (long)MAXTC); + } + + if (txc->modes & ADJ_OFFSET) { /* values checked earlier */ + if (txc->modes == ADJ_OFFSET_SINGLESHOT) { + /* adjtime() is independent from ntp_adjtime() */ + time_adjust = txc->offset; + } + else if (time_status & STA_PLL) { + ltemp = txc->offset * NSEC_PER_USEC; + + /* + * Scale the phase adjustment and + * clamp to the operating range. + */ + time_offset = min(ltemp, MAXPHASE * NSEC_PER_USEC); + time_offset = max(time_offset, -MAXPHASE * NSEC_PER_USEC); + + /* + * Select whether the frequency is to be controlled + * and in which mode (PLL or FLL). Clamp to the operating + * range. Ugly multiply/divide should be replaced someday. + */ + + 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)time_offset * mtemp; + freq_adj = shift_right(freq_adj, time_constant * 2 + + (SHIFT_PLL + 2) * 2 - SHIFT_NSEC); + if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) { + temp64 = (s64)time_offset << (SHIFT_NSEC - SHIFT_FLL); + if (time_offset < 0) { + temp64 = -temp64; + do_div(temp64, mtemp); + freq_adj -= temp64; + } else { + do_div(temp64, mtemp); + freq_adj += temp64; + } + } + freq_adj += time_freq; + freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC); + time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC); + time_offset = (time_offset / HZ) << SHIFT_UPDATE; + } /* STA_PLL */ + } /* txc->modes & ADJ_OFFSET */ + if (txc->modes & ADJ_TICK) + tick_usec = txc->tick; + + if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET)) + ntp_update_frequency(); + } /* txc->modes */ +leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0) + result = TIME_ERROR; + + if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) + txc->offset = save_adjust; + else + txc->offset = shift_right(time_offset, SHIFT_UPDATE) * HZ / 1000; + txc->freq = (time_freq / NSEC_PER_USEC) << (SHIFT_USEC - SHIFT_NSEC); + txc->maxerror = time_maxerror; + txc->esterror = time_esterror; + txc->status = time_status; + txc->constant = time_constant; + txc->precision = 1; + txc->tolerance = MAXFREQ; + txc->tick = tick_usec; + + /* 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); + do_gettimeofday(&txc->time); + notify_arch_cmos_timer(); + return(result); +} |