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Diffstat (limited to 'cpukit/score/src/kern_ntptime.c')
| -rw-r--r-- | cpukit/score/src/kern_ntptime.c | 1194 |
1 files changed, 1194 insertions, 0 deletions
diff --git a/cpukit/score/src/kern_ntptime.c b/cpukit/score/src/kern_ntptime.c new file mode 100644 index 0000000000..c6f70079b3 --- /dev/null +++ b/cpukit/score/src/kern_ntptime.c @@ -0,0 +1,1194 @@ +/** + * @file + * + * @ingroup RTEMSScoreTimecounter + * + * @brief This source file contains the implementation of ntp_gettime(), + * ntp_adjtime(), adjtime(), and _Timecounter_NTP_update_second(). + */ + +/*- + *********************************************************************** + * * + * Copyright (c) David L. Mills 1993-2001 * + * * + * Permission to use, copy, modify, and distribute this software and * + * its documentation for any purpose and without fee is hereby * + * granted, provided that the above copyright notice appears in all * + * copies and that both the copyright notice and this permission * + * notice appear in supporting documentation, and that the name * + * University of Delaware not be used in advertising or publicity * + * pertaining to distribution of the software without specific, * + * written prior permission. The University of Delaware makes no * + * representations about the suitability this software for any * + * purpose. It is provided "as is" without express or implied * + * warranty. * + * * + **********************************************************************/ + +/* + * Adapted from the original sources for FreeBSD and timecounters by: + * Poul-Henning Kamp <phk@FreeBSD.org>. + * + * The 32bit version of the "LP" macros seems a bit past its "sell by" + * date so I have retained only the 64bit version and included it directly + * in this file. + * + * Only minor changes done to interface with the timecounters over in + * sys/kern/kern_clock.c. Some of the comments below may be (even more) + * confusing and/or plain wrong in that context. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_ntp.h" + +#include <sys/param.h> +#ifndef __rtems__ +#include <sys/systm.h> +#include <sys/sysproto.h> +#include <sys/eventhandler.h> +#include <sys/kernel.h> +#include <sys/priv.h> +#include <sys/proc.h> +#include <sys/lock.h> +#include <sys/mutex.h> +#endif /* __rtems__ */ +#include <sys/time.h> +#include <sys/timex.h> +#include <sys/timetc.h> +#ifdef __rtems__ +#define _KERNEL +#endif /* __rtems__ */ +#include <sys/timepps.h> +#ifndef __rtems__ +#include <sys/syscallsubr.h> +#include <sys/sysctl.h> +#else /* __rtems__ */ +#include <rtems/sysinit.h> +#include <rtems/score/timecounter.h> +#include <errno.h> +#include <string.h> +#define nanotime(_tsp) _Timecounter_Nanotime(_tsp) +#define ntp_update_second _Timecounter_NTP_update_second +#define time_uptime _Timecounter_Time_uptime +struct thread; + +static inline long +lmax(long a, long b) +{ + + if (a > b) + return (a); + return (b); +} + +static inline quad_t +qmin(quad_t a, quad_t b) +{ + + if (a < b) + return (a); + return (b); +} +#endif /* __rtems__ */ + +#ifndef __rtems__ +#ifdef PPS_SYNC +FEATURE(pps_sync, "Support usage of external PPS signal by kernel PLL"); +#endif +#endif /* __rtems__ */ + +/* + * Single-precision macros for 64-bit machines + */ +typedef int64_t l_fp; +#define L_ADD(v, u) ((v) += (u)) +#define L_SUB(v, u) ((v) -= (u)) +#define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32) +#define L_NEG(v) ((v) = -(v)) +#define L_RSHIFT(v, n) \ + do { \ + if ((v) < 0) \ + (v) = -(-(v) >> (n)); \ + else \ + (v) = (v) >> (n); \ + } while (0) +#define L_MPY(v, a) ((v) *= (a)) +#define L_CLR(v) ((v) = 0) +#define L_ISNEG(v) ((v) < 0) +#define L_LINT(v, a) ((v) = (int64_t)(a) << 32) +#define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) + +/* + * Generic NTP kernel interface + * + * These routines constitute the Network Time Protocol (NTP) interfaces + * for user and daemon application programs. The ntp_gettime() routine + * provides the time, maximum error (synch distance) and estimated error + * (dispersion) to client user application programs. The ntp_adjtime() + * routine is used by the NTP daemon to adjust the system clock to an + * externally derived time. The time offset and related variables set by + * this routine are used by other routines in this module to adjust the + * phase and frequency of the clock discipline loop which controls the + * system clock. + * + * When the kernel time is reckoned directly in nanoseconds (NTP_NANO + * defined), the time at each tick interrupt is derived directly from + * the kernel time variable. When the kernel time is reckoned in + * microseconds, (NTP_NANO undefined), the time is derived from the + * kernel time variable together with a variable representing the + * leftover nanoseconds at the last tick interrupt. In either case, the + * current nanosecond time is reckoned from these values plus an + * interpolated value derived by the clock routines in another + * architecture-specific module. The interpolation can use either a + * dedicated counter or a processor cycle counter (PCC) implemented in + * some architectures. + * + * Note that all routines must run at priority splclock or higher. + */ +/* + * Phase/frequency-lock loop (PLL/FLL) definitions + * + * The nanosecond clock discipline uses two variable types, time + * variables and frequency variables. Both types are represented as 64- + * bit fixed-point quantities with the decimal point between two 32-bit + * halves. On a 32-bit machine, each half is represented as a single + * word and mathematical operations are done using multiple-precision + * arithmetic. On a 64-bit machine, ordinary computer arithmetic is + * used. + * + * A time variable is a signed 64-bit fixed-point number in ns and + * fraction. It represents the remaining time offset to be amortized + * over succeeding tick interrupts. The maximum time offset is about + * 0.5 s and the resolution is about 2.3e-10 ns. + * + * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 + * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * |s s s| ns | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | fraction | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * + * A frequency variable is a signed 64-bit fixed-point number in ns/s + * and fraction. It represents the ns and fraction to be added to the + * kernel time variable at each second. The maximum frequency offset is + * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. + * + * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 + * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * |s s s s s s s s s s s s s| ns/s | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * | fraction | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + */ +/* + * The following variables establish the state of the PLL/FLL and the + * residual time and frequency offset of the local clock. + */ +#define SHIFT_PLL 4 /* PLL loop gain (shift) */ +#define SHIFT_FLL 2 /* FLL loop gain (shift) */ + +static int time_state = TIME_OK; /* clock state */ +#ifdef __rtems__ +static +#endif /* __rtems__ */ +int time_status = STA_UNSYNC; /* clock status bits */ +static long time_tai; /* TAI offset (s) */ +static long time_monitor; /* last time offset scaled (ns) */ +static long time_constant; /* poll interval (shift) (s) */ +static long time_precision = 1; /* clock precision (ns) */ +static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */ +#ifdef __rtems__ +static +#endif /* __rtems__ */ +long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ +static long time_reftime; /* uptime at last adjustment (s) */ +static l_fp time_offset; /* time offset (ns) */ +static l_fp time_freq; /* frequency offset (ns/s) */ +static l_fp time_adj; /* tick adjust (ns/s) */ + +static int64_t time_adjtime; /* correction from adjtime(2) (usec) */ + +#ifndef __rtems__ +static struct mtx ntp_lock; +MTX_SYSINIT(ntp, &ntp_lock, "ntp", MTX_SPIN); + +#define NTP_LOCK() mtx_lock_spin(&ntp_lock) +#define NTP_UNLOCK() mtx_unlock_spin(&ntp_lock) +#define NTP_ASSERT_LOCKED() mtx_assert(&ntp_lock, MA_OWNED) +#else /* __rtems__ */ +#define NTP_LOCK() \ + do { \ + ISR_lock_Context lock_context; \ + _Timecounter_Acquire(&lock_context); +#define NTP_UNLOCK() \ + _Timecounter_Release(&lock_context); \ + } while (0) +#define NTP_ASSERT_LOCKED() \ + _Assert(_ISR_lock_Is_owner(&_Timecounter_Lock)) +#endif /* __rtems__ */ + +#ifdef PPS_SYNC +/* + * The following variables are used when a pulse-per-second (PPS) signal + * is available and connected via a modem control lead. They establish + * the engineering parameters of the clock discipline loop when + * controlled by the PPS signal. + */ +#define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ +#define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ +#define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ +#define PPS_PAVG 4 /* phase avg interval (s) (shift) */ +#define PPS_VALID 120 /* PPS signal watchdog max (s) */ +#define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ +#define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ + +static struct timespec pps_tf[3]; /* phase median filter */ +static l_fp pps_freq; /* scaled frequency offset (ns/s) */ +static long pps_fcount; /* frequency accumulator */ +static long pps_jitter; /* nominal jitter (ns) */ +static long pps_stabil; /* nominal stability (scaled ns/s) */ +static long pps_lastsec; /* time at last calibration (s) */ +static int pps_valid; /* signal watchdog counter */ +static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ +static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ +static int pps_intcnt; /* wander counter */ + +/* + * PPS signal quality monitors + */ +static long pps_calcnt; /* calibration intervals */ +static long pps_jitcnt; /* jitter limit exceeded */ +static long pps_stbcnt; /* stability limit exceeded */ +static long pps_errcnt; /* calibration errors */ +#endif /* PPS_SYNC */ +/* + * End of phase/frequency-lock loop (PLL/FLL) definitions + */ + +static void hardupdate(long offset); +static void ntp_gettime1(struct ntptimeval *ntvp); +static bool ntp_is_time_error(int tsl); + +static bool +ntp_is_time_error(int tsl) +{ + + /* + * Status word error decode. If any of these conditions occur, + * an error is returned, instead of the status word. Most + * applications will care only about the fact the system clock + * may not be trusted, not about the details. + * + * Hardware or software error + */ + if ((tsl & (STA_UNSYNC | STA_CLOCKERR)) || + + /* + * PPS signal lost when either time or frequency synchronization + * requested + */ + (tsl & (STA_PPSFREQ | STA_PPSTIME) && + !(tsl & STA_PPSSIGNAL)) || + + /* + * PPS jitter exceeded when time synchronization requested + */ + (tsl & STA_PPSTIME && tsl & STA_PPSJITTER) || + + /* + * PPS wander exceeded or calibration error when frequency + * synchronization requested + */ + (tsl & STA_PPSFREQ && + tsl & (STA_PPSWANDER | STA_PPSERROR))) + return (true); + + return (false); +} + +static void +ntp_gettime1(struct ntptimeval *ntvp) +{ + struct timespec atv; /* nanosecond time */ + + NTP_ASSERT_LOCKED(); + + nanotime(&atv); + ntvp->time.tv_sec = atv.tv_sec; + ntvp->time.tv_nsec = atv.tv_nsec; + ntvp->maxerror = time_maxerror; + ntvp->esterror = time_esterror; + ntvp->tai = time_tai; + ntvp->time_state = time_state; + + if (ntp_is_time_error(time_status)) + ntvp->time_state = TIME_ERROR; +} + +/* + * ntp_gettime() - NTP user application interface + * + * See the timex.h header file for synopsis and API description. Note that + * the TAI offset is returned in the ntvtimeval.tai structure member. + */ +#ifndef __rtems__ +#ifndef _SYS_SYSPROTO_H_ +struct ntp_gettime_args { + struct ntptimeval *ntvp; +}; +#endif +/* ARGSUSED */ +int +sys_ntp_gettime(struct thread *td, struct ntp_gettime_args *uap) +{ + struct ntptimeval ntv; + + memset(&ntv, 0, sizeof(ntv)); + + NTP_LOCK(); + ntp_gettime1(&ntv); + NTP_UNLOCK(); + + td->td_retval[0] = ntv.time_state; + return (copyout(&ntv, uap->ntvp, sizeof(ntv))); +} +#else /* __rtems__ */ +int +ntp_gettime(struct ntptimeval *ntv) +{ + + if (ntv == NULL) { + errno = EFAULT; + return (-1); + } + + ntv = memset(ntv, 0, sizeof(*ntv)); + + NTP_LOCK(); + ntp_gettime1(ntv); + NTP_UNLOCK(); + + return (ntv->time_state); +} +#endif /* __rtems__ */ + +#ifndef __rtems__ +static int +ntp_sysctl(SYSCTL_HANDLER_ARGS) +{ + struct ntptimeval ntv; /* temporary structure */ + + memset(&ntv, 0, sizeof(ntv)); + + NTP_LOCK(); + ntp_gettime1(&ntv); + NTP_UNLOCK(); + + return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req)); +} + +SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, + ""); +SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE | CTLFLAG_RD | + CTLFLAG_MPSAFE, 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", + ""); + +#ifdef PPS_SYNC +SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, + &pps_shiftmax, 0, "Max interval duration (sec) (shift)"); +SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, + &pps_shift, 0, "Interval duration (sec) (shift)"); +SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, + &time_monitor, 0, "Last time offset scaled (ns)"); + +SYSCTL_S64(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD | CTLFLAG_MPSAFE, + &pps_freq, 0, + "Scaled frequency offset (ns/sec)"); +SYSCTL_S64(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD | CTLFLAG_MPSAFE, + &time_freq, 0, + "Frequency offset (ns/sec)"); +#endif +#endif /* __rtems__ */ + +/* + * ntp_adjtime() - NTP daemon application interface + * + * See the timex.h header file for synopsis and API description. Note that + * the timex.constant structure member has a dual purpose to set the time + * constant and to set the TAI offset. + */ +#ifdef __rtems__ +static +#endif /* __rtems__ */ +int +kern_ntp_adjtime(struct thread *td, struct timex *ntv, int *retvalp) +{ + long freq; /* frequency ns/s) */ + int modes; /* mode bits from structure */ +#ifndef __rtems__ + int error, retval; +#else /* __rtems__ */ + int retval; +#endif /* __rtems__ */ + + /* + * Update selected clock variables - only the superuser can + * change anything. Note that there is no error checking here on + * the assumption the superuser should know what it is doing. + * Note that either the time constant or TAI offset are loaded + * from the ntv.constant member, depending on the mode bits. If + * the STA_PLL bit in the status word is cleared, the state and + * status words are reset to the initial values at boot. + */ + modes = ntv->modes; +#ifndef __rtems__ + error = 0; + if (modes) + error = priv_check(td, PRIV_NTP_ADJTIME); + if (error != 0) + return (error); +#endif /* __rtems__ */ + NTP_LOCK(); + if (modes & MOD_MAXERROR) + time_maxerror = ntv->maxerror; + if (modes & MOD_ESTERROR) + time_esterror = ntv->esterror; + if (modes & MOD_STATUS) { + if (time_status & STA_PLL && !(ntv->status & STA_PLL)) { + time_state = TIME_OK; + time_status = STA_UNSYNC; +#ifdef PPS_SYNC + pps_shift = PPS_FAVG; +#endif /* PPS_SYNC */ + } + time_status &= STA_RONLY; + time_status |= ntv->status & ~STA_RONLY; + } + if (modes & MOD_TIMECONST) { + if (ntv->constant < 0) + time_constant = 0; + else if (ntv->constant > MAXTC) + time_constant = MAXTC; + else + time_constant = ntv->constant; + } + if (modes & MOD_TAI) { + if (ntv->constant > 0) /* XXX zero & negative numbers ? */ + time_tai = ntv->constant; + } +#ifdef PPS_SYNC + if (modes & MOD_PPSMAX) { + if (ntv->shift < PPS_FAVG) + pps_shiftmax = PPS_FAVG; + else if (ntv->shift > PPS_FAVGMAX) + pps_shiftmax = PPS_FAVGMAX; + else + pps_shiftmax = ntv->shift; + } +#endif /* PPS_SYNC */ + if (modes & MOD_NANO) + time_status |= STA_NANO; + if (modes & MOD_MICRO) + time_status &= ~STA_NANO; + if (modes & MOD_CLKB) + time_status |= STA_CLK; + if (modes & MOD_CLKA) + time_status &= ~STA_CLK; + if (modes & MOD_FREQUENCY) { + freq = (ntv->freq * 1000LL) >> 16; + if (freq > MAXFREQ) + L_LINT(time_freq, MAXFREQ); + else if (freq < -MAXFREQ) + L_LINT(time_freq, -MAXFREQ); + else { + /* + * ntv->freq is [PPM * 2^16] = [us/s * 2^16] + * time_freq is [ns/s * 2^32] + */ + time_freq = ntv->freq * 1000LL * 65536LL; + } +#ifdef PPS_SYNC + pps_freq = time_freq; +#endif /* PPS_SYNC */ + } + if (modes & MOD_OFFSET) { + if (time_status & STA_NANO) + hardupdate(ntv->offset); + else + hardupdate(ntv->offset * 1000); + } + + /* + * Retrieve all clock variables. Note that the TAI offset is + * returned only by ntp_gettime(); + */ + if (time_status & STA_NANO) + ntv->offset = L_GINT(time_offset); + else + ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ + ntv->freq = L_GINT((time_freq / 1000LL) << 16); + ntv->maxerror = time_maxerror; + ntv->esterror = time_esterror; + ntv->status = time_status; + ntv->constant = time_constant; + if (time_status & STA_NANO) + ntv->precision = time_precision; + else + ntv->precision = time_precision / 1000; + ntv->tolerance = MAXFREQ * SCALE_PPM; +#ifdef PPS_SYNC + ntv->shift = pps_shift; + ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16); + if (time_status & STA_NANO) + ntv->jitter = pps_jitter; + else + ntv->jitter = pps_jitter / 1000; + ntv->stabil = pps_stabil; + ntv->calcnt = pps_calcnt; + ntv->errcnt = pps_errcnt; + ntv->jitcnt = pps_jitcnt; + ntv->stbcnt = pps_stbcnt; +#endif /* PPS_SYNC */ + retval = ntp_is_time_error(time_status) ? TIME_ERROR : time_state; + NTP_UNLOCK(); + + *retvalp = retval; + return (0); +} + +#ifndef _SYS_SYSPROTO_H_ +struct ntp_adjtime_args { + struct timex *tp; +}; +#endif + +#ifndef __rtems__ +int +sys_ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap) +{ + struct timex ntv; + int error, retval; + + error = copyin(uap->tp, &ntv, sizeof(ntv)); + if (error == 0) { + error = kern_ntp_adjtime(td, &ntv, &retval); + if (error == 0) { + error = copyout(&ntv, uap->tp, sizeof(ntv)); + if (error == 0) + td->td_retval[0] = retval; + } + } + return (error); +} +#else /* __rtems__ */ +int +ntp_adjtime(struct timex *ntv) +{ + int error; + int retval; + + if (ntv == NULL) { + errno = EFAULT; + return (-1); + } + + error = kern_ntp_adjtime(NULL, ntv, &retval); + _Assert_Unused_variable_equals(error, 0); + return (retval); +} +#endif /* __rtems__ */ + +/* + * second_overflow() - called after ntp_tick_adjust() + * + * This routine is ordinarily called immediately following the above + * routine ntp_tick_adjust(). While these two routines are normally + * combined, they are separated here only for the purposes of + * simulation. + */ +void +ntp_update_second(int64_t *adjustment, time_t *newsec) +{ + int tickrate; + l_fp ftemp; /* 32/64-bit temporary */ + +#ifndef __rtems__ + NTP_LOCK(); +#else /* __rtems__ */ + NTP_ASSERT_LOCKED(); +#endif /* __rtems__ */ + + /* + * On rollover of the second both the nanosecond and microsecond + * clocks are updated and the state machine cranked as + * necessary. The phase adjustment to be used for the next + * second is calculated and the maximum error is increased by + * the tolerance. + */ + time_maxerror += MAXFREQ / 1000; + + /* + * 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 nano_time() routine or + * external clock driver will insure that reported time + * is always monotonic. + */ + switch (time_state) { + /* + * No warning. + */ + case TIME_OK: + if (time_status & STA_INS) + time_state = TIME_INS; + else if (time_status & STA_DEL) + time_state = TIME_DEL; + break; + + /* + * Insert second 23:59:60 following second + * 23:59:59. + */ + case TIME_INS: + if (!(time_status & STA_INS)) + time_state = TIME_OK; + else if ((*newsec) % 86400 == 0) { + (*newsec)--; + time_state = TIME_OOP; + time_tai++; + } + break; + + /* + * Delete second 23:59:59. + */ + case TIME_DEL: + if (!(time_status & STA_DEL)) + time_state = TIME_OK; + else if (((*newsec) + 1) % 86400 == 0) { + (*newsec)++; + time_tai--; + time_state = TIME_WAIT; + } + break; + + /* + * Insert second in progress. + */ + case TIME_OOP: + time_state = TIME_WAIT; + break; + + /* + * Wait for status bits to clear. + */ + case TIME_WAIT: + if (!(time_status & (STA_INS | STA_DEL))) + time_state = TIME_OK; + } + + /* + * Compute the total time adjustment for the next second + * in ns. The offset is reduced by a factor depending on + * whether the PPS signal is operating. Note that the + * value is in effect scaled by the clock frequency, + * since the adjustment is added at each tick interrupt. + */ + ftemp = time_offset; +#ifdef PPS_SYNC + /* XXX even if PPS signal dies we should finish adjustment ? */ + if (time_status & STA_PPSTIME && time_status & + STA_PPSSIGNAL) + L_RSHIFT(ftemp, pps_shift); + else + L_RSHIFT(ftemp, SHIFT_PLL + time_constant); +#else + L_RSHIFT(ftemp, SHIFT_PLL + time_constant); +#endif /* PPS_SYNC */ + time_adj = ftemp; + L_SUB(time_offset, ftemp); + L_ADD(time_adj, time_freq); + + /* + * Apply any correction from adjtime(2). If more than one second + * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500 PPM) + * until the last second is slewed the final < 500 usecs. + */ + if (time_adjtime != 0) { + if (time_adjtime > 1000000) + tickrate = 5000; + else if (time_adjtime < -1000000) + tickrate = -5000; + else if (time_adjtime > 500) + tickrate = 500; + else if (time_adjtime < -500) + tickrate = -500; + else + tickrate = time_adjtime; + time_adjtime -= tickrate; + L_LINT(ftemp, tickrate * 1000); + L_ADD(time_adj, ftemp); + } + *adjustment = time_adj; + +#ifdef PPS_SYNC + if (pps_valid > 0) + pps_valid--; + else + time_status &= ~STA_PPSSIGNAL; +#endif /* PPS_SYNC */ + +#ifndef __rtems__ + NTP_UNLOCK(); +#endif /* __rtems__ */ +} +#ifdef __rtems__ +static void +_NTP_Initialize(void) +{ + + _Timecounter_Set_NTP_update_second(ntp_update_second); +} + +RTEMS_SYSINIT_ITEM(_NTP_Initialize, RTEMS_SYSINIT_DEVICE_DRIVERS, + RTEMS_SYSINIT_ORDER_FOURTH); +#endif /* __rtems__ */ + +/* + * hardupdate() - local clock update + * + * This routine is called by ntp_adjtime() to update the local clock + * phase and frequency. The implementation is of an adaptive-parameter, + * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new + * time and frequency offset estimates for each call. If the kernel PPS + * discipline code is configured (PPS_SYNC), the PPS signal itself + * determines the new time offset, instead of the calling argument. + * Presumably, calls to ntp_adjtime() occur only when the caller + * believes the local clock is valid within some bound (+-128 ms with + * NTP). If the caller's time is far different than the PPS time, an + * argument will ensue, and it's not clear who will lose. + * + * For uncompensated quartz crystal oscillators and nominal update + * intervals less than 256 s, operation should be in phase-lock mode, + * where the loop is disciplined to phase. For update intervals greater + * than 1024 s, operation should be in frequency-lock mode, where the + * loop is disciplined to frequency. Between 256 s and 1024 s, the mode + * is selected by the STA_MODE status bit. + */ +static void +hardupdate(long offset /* clock offset (ns) */) +{ + long mtemp; + l_fp ftemp; + + NTP_ASSERT_LOCKED(); + + /* + * Select how the phase is to be controlled and from which + * source. If the PPS signal is present and enabled to + * discipline the time, the PPS offset is used; otherwise, the + * argument offset is used. + */ + if (!(time_status & STA_PLL)) + return; + if (!(time_status & STA_PPSTIME && time_status & + STA_PPSSIGNAL)) { + if (offset > MAXPHASE) + time_monitor = MAXPHASE; + else if (offset < -MAXPHASE) + time_monitor = -MAXPHASE; + else + time_monitor = offset; + L_LINT(time_offset, time_monitor); + } + + /* + * Select how the frequency is to be controlled and in which + * mode (PLL or FLL). If the PPS signal is present and enabled + * to discipline the frequency, the PPS frequency is used; + * otherwise, the argument offset is used to compute it. + */ + if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { + time_reftime = time_uptime; + return; + } + if (time_status & STA_FREQHOLD || time_reftime == 0) + time_reftime = time_uptime; + mtemp = time_uptime - time_reftime; + L_LINT(ftemp, time_monitor); + L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); + L_MPY(ftemp, mtemp); + L_ADD(time_freq, ftemp); + time_status &= ~STA_MODE; + if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > + MAXSEC)) { + L_LINT(ftemp, (time_monitor << 4) / mtemp); + L_RSHIFT(ftemp, SHIFT_FLL + 4); + L_ADD(time_freq, ftemp); + time_status |= STA_MODE; + } + time_reftime = time_uptime; + if (L_GINT(time_freq) > MAXFREQ) + L_LINT(time_freq, MAXFREQ); + else if (L_GINT(time_freq) < -MAXFREQ) + L_LINT(time_freq, -MAXFREQ); +} + +#ifdef PPS_SYNC +/* + * hardpps() - discipline CPU clock oscillator to external PPS signal + * + * This routine is called at each PPS interrupt in order to discipline + * the CPU clock oscillator to the PPS signal. There are two independent + * first-order feedback loops, one for the phase, the other for the + * frequency. The phase loop measures and grooms the PPS phase offset + * and leaves it in a handy spot for the seconds overflow routine. The + * frequency loop averages successive PPS phase differences and + * calculates the PPS frequency offset, which is also processed by the + * seconds overflow routine. The code requires the caller to capture the + * time and architecture-dependent hardware counter values in + * nanoseconds at the on-time PPS signal transition. + * + * Note that, on some Unix systems this routine runs at an interrupt + * priority level higher than the timer interrupt routine hardclock(). + * Therefore, the variables used are distinct from the hardclock() + * variables, except for the actual time and frequency variables, which + * are determined by this routine and updated atomically. + * + * tsp - time at current PPS event + * delta_nsec - time elapsed between the previous and current PPS event + */ +void +hardpps(struct timespec *tsp, long delta_nsec) +{ + long u_sec, u_nsec, v_nsec; /* temps */ + l_fp ftemp; + + NTP_LOCK(); + + /* + * The signal is first processed by a range gate and frequency + * discriminator. The range gate rejects noise spikes outside + * the range +-500 us. The frequency discriminator rejects input + * signals with apparent frequency outside the range 1 +-500 + * PPM. If two hits occur in the same second, we ignore the + * later hit; if not and a hit occurs outside the range gate, + * keep the later hit for later comparison, but do not process + * it. + */ + time_status |= STA_PPSSIGNAL | STA_PPSJITTER; + time_status &= ~(STA_PPSWANDER | STA_PPSERROR); + pps_valid = PPS_VALID; + u_sec = tsp->tv_sec; + u_nsec = tsp->tv_nsec; + if (u_nsec >= (NANOSECOND >> 1)) { + u_nsec -= NANOSECOND; + u_sec++; + } + v_nsec = u_nsec - pps_tf[0].tv_nsec; + if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - MAXFREQ) + goto out; + pps_tf[2] = pps_tf[1]; + pps_tf[1] = pps_tf[0]; + pps_tf[0].tv_sec = u_sec; + pps_tf[0].tv_nsec = u_nsec; + + /* + * Update the frequency accumulator using the difference between the + * current and previous PPS event measured directly by the timecounter. + */ + pps_fcount += delta_nsec - NANOSECOND; + if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) + goto out; + time_status &= ~STA_PPSJITTER; + + /* + * A three-stage median filter is used to help denoise the PPS + * time. The median sample becomes the time offset estimate; the + * difference between the other two samples becomes the time + * dispersion (jitter) estimate. + */ + if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { + if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { + v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ + u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; + } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { + v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ + u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; + } else { + v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ + u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; + } + } else { + if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { + v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ + u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; + } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { + v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ + u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; + } else { + v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ + u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; + } + } + + /* + * Nominal jitter is due to PPS signal noise and interrupt + * latency. If it exceeds the popcorn threshold, the sample is + * discarded. otherwise, if so enabled, the time offset is + * updated. We can tolerate a modest loss of data here without + * much degrading time accuracy. + * + * The measurements being checked here were made with the system + * timecounter, so the popcorn threshold is not allowed to fall below + * the number of nanoseconds in two ticks of the timecounter. For a + * timecounter running faster than 1 GHz the lower bound is 2ns, just + * to avoid a nonsensical threshold of zero. + */ + if (u_nsec > lmax(pps_jitter << PPS_POPCORN, + 2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) { + time_status |= STA_PPSJITTER; + pps_jitcnt++; + } else if (time_status & STA_PPSTIME) { + time_monitor = -v_nsec; + L_LINT(time_offset, time_monitor); + } + pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; + u_sec = pps_tf[0].tv_sec - pps_lastsec; + if (u_sec < (1 << pps_shift)) + goto out; + + /* + * At the end of the calibration interval the difference between + * the first and last counter values becomes the scaled + * frequency. It will later be divided by the length of the + * interval to determine the frequency update. If the frequency + * exceeds a sanity threshold, or if the actual calibration + * interval is not equal to the expected length, the data are + * discarded. We can tolerate a modest loss of data here without + * much degrading frequency accuracy. + */ + pps_calcnt++; + v_nsec = -pps_fcount; + pps_lastsec = pps_tf[0].tv_sec; + pps_fcount = 0; + u_nsec = MAXFREQ << pps_shift; + if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << pps_shift)) { + time_status |= STA_PPSERROR; + pps_errcnt++; + goto out; + } + + /* + * Here the raw frequency offset and wander (stability) is + * calculated. If the wander is less than the wander threshold + * for four consecutive averaging intervals, the interval is + * doubled; if it is greater than the threshold for four + * consecutive intervals, the interval is halved. The scaled + * frequency offset is converted to frequency offset. The + * stability metric is calculated as the average of recent + * frequency changes, but is used only for performance + * monitoring. + */ + L_LINT(ftemp, v_nsec); + L_RSHIFT(ftemp, pps_shift); + L_SUB(ftemp, pps_freq); + u_nsec = L_GINT(ftemp); + if (u_nsec > PPS_MAXWANDER) { + L_LINT(ftemp, PPS_MAXWANDER); + pps_intcnt--; + time_status |= STA_PPSWANDER; + pps_stbcnt++; + } else if (u_nsec < -PPS_MAXWANDER) { + L_LINT(ftemp, -PPS_MAXWANDER); + pps_intcnt--; + time_status |= STA_PPSWANDER; + pps_stbcnt++; + } else { + pps_intcnt++; + } + if (pps_intcnt >= 4) { + pps_intcnt = 4; + if (pps_shift < pps_shiftmax) { + pps_shift++; + pps_intcnt = 0; + } + } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { + pps_intcnt = -4; + if (pps_shift > PPS_FAVG) { + pps_shift--; + pps_intcnt = 0; + } + } + if (u_nsec < 0) + u_nsec = -u_nsec; + pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; + + /* + * The PPS frequency is recalculated and clamped to the maximum + * MAXFREQ. If enabled, the system clock frequency is updated as + * well. + */ + L_ADD(pps_freq, ftemp); + u_nsec = L_GINT(pps_freq); + if (u_nsec > MAXFREQ) + L_LINT(pps_freq, MAXFREQ); + else if (u_nsec < -MAXFREQ) + L_LINT(pps_freq, -MAXFREQ); + if (time_status & STA_PPSFREQ) + time_freq = pps_freq; + +out: + NTP_UNLOCK(); +} +#endif /* PPS_SYNC */ + +#ifndef __rtems__ +#ifndef _SYS_SYSPROTO_H_ +struct adjtime_args { + struct timeval *delta; + struct timeval *olddelta; +}; +#endif +/* ARGSUSED */ +int +sys_adjtime(struct thread *td, struct adjtime_args *uap) +{ + struct timeval delta, olddelta, *deltap; + int error; + + if (uap->delta) { + error = copyin(uap->delta, &delta, sizeof(delta)); + if (error) + return (error); + deltap = δ + } else + deltap = NULL; + error = kern_adjtime(td, deltap, &olddelta); + if (uap->olddelta && error == 0) + error = copyout(&olddelta, uap->olddelta, sizeof(olddelta)); + return (error); +} + +int +kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta) +#else /* __rtems__ */ +static int +kern_adjtime(const struct timeval *delta, struct timeval *olddelta) +#endif /* __rtems__ */ +{ + struct timeval atv; + int64_t ltr, ltw; +#ifndef __rtems__ + int error; +#endif /* __rtems__ */ + + if (delta != NULL) { +#ifndef __rtems__ + error = priv_check(td, PRIV_ADJTIME); + if (error != 0) + return (error); +#endif /* __rtems__ */ + ltw = (int64_t)delta->tv_sec * 1000000 + delta->tv_usec; + } + NTP_LOCK(); + ltr = time_adjtime; + if (delta != NULL) + time_adjtime = ltw; + NTP_UNLOCK(); + if (olddelta != NULL) { + atv.tv_sec = ltr / 1000000; + atv.tv_usec = ltr % 1000000; + if (atv.tv_usec < 0) { + atv.tv_usec += 1000000; + atv.tv_sec--; + } + *olddelta = atv; + } + return (0); +} +#ifdef __rtems__ +int +adjtime(const struct timeval *delta, struct timeval *olddelta) +{ + int error; + + error = kern_adjtime(delta, olddelta); + _Assert_Unused_variable_equals(error, 0); + return (0); +} +#endif /* __rtems__ */ + +#ifndef __rtems__ +static struct callout resettodr_callout; +static int resettodr_period = 1800; + +static void +periodic_resettodr(void *arg __unused) +{ + + /* + * Read of time_status is lock-less, which is fine since + * ntp_is_time_error() operates on the consistent read value. + */ + if (!ntp_is_time_error(time_status)) + resettodr(); + if (resettodr_period > 0) + callout_schedule(&resettodr_callout, resettodr_period * hz); +} + +static void +shutdown_resettodr(void *arg __unused, int howto __unused) +{ + + callout_drain(&resettodr_callout); + /* Another unlocked read of time_status */ + if (resettodr_period > 0 && !ntp_is_time_error(time_status)) + resettodr(); +} + +static int +sysctl_resettodr_period(SYSCTL_HANDLER_ARGS) +{ + int error; + + error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); + if (error || !req->newptr) + return (error); + if (cold) + goto done; + if (resettodr_period == 0) + callout_stop(&resettodr_callout); + else + callout_reset(&resettodr_callout, resettodr_period * hz, + periodic_resettodr, NULL); +done: + return (0); +} + +SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT | CTLFLAG_RWTUN | + CTLFLAG_MPSAFE, &resettodr_period, 1800, sysctl_resettodr_period, "I", + "Save system time to RTC with this period (in seconds)"); + +static void +start_periodic_resettodr(void *arg __unused) +{ + + EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL, + SHUTDOWN_PRI_FIRST); + callout_init(&resettodr_callout, 1); + if (resettodr_period == 0) + return; + callout_reset(&resettodr_callout, resettodr_period * hz, + periodic_resettodr, NULL); +} + +SYSINIT(periodic_resettodr, SI_SUB_LAST, SI_ORDER_MIDDLE, + start_periodic_resettodr, NULL); +#endif /* __rtems__ */ |