| 1 | /*********************************************************************** |
| 2 | * * |
| 3 | * Copyright (c) David L. Mills 1993-2001 * |
| 4 | * * |
| 5 | * Permission to use, copy, modify, and distribute this software and * |
| 6 | * its documentation for any purpose and without fee is hereby * |
| 7 | * granted, provided that the above copyright notice appears in all * |
| 8 | * copies and that both the copyright notice and this permission * |
| 9 | * notice appear in supporting documentation, and that the name * |
| 10 | * University of Delaware not be used in advertising or publicity * |
| 11 | * pertaining to distribution of the software without specific, * |
| 12 | * written prior permission. The University of Delaware makes no * |
| 13 | * representations about the suitability this software for any * |
| 14 | * purpose. It is provided "as is" without express or implied * |
| 15 | * warranty. * |
| 16 | * * |
| 17 | **********************************************************************/ |
| 18 | |
| 19 | /* |
| 20 | * Adapted from the original sources for FreeBSD and timecounters by: |
| 21 | * Poul-Henning Kamp <phk@FreeBSD.org>. |
| 22 | * |
| 23 | * The 32bit version of the "LP" macros seems a bit past its "sell by" |
| 24 | * date so I have retained only the 64bit version and included it directly |
| 25 | * in this file. |
| 26 | * |
| 27 | * Only minor changes done to interface with the timecounters over in |
| 28 | * sys/kern/kern_clock.c. Some of the comments below may be (even more) |
| 29 | * confusing and/or plain wrong in that context. |
| 30 | * |
| 31 | * $FreeBSD: src/sys/kern/kern_ntptime.c,v 1.32.2.2 2001/04/22 11:19:46 jhay Exp $ |
| 32 | */ |
| 33 | |
| 34 | #include "opt_ntp.h" |
| 35 | |
| 36 | #include <sys/param.h> |
| 37 | #include <sys/systm.h> |
| 38 | #include <sys/sysmsg.h> |
| 39 | #include <sys/kernel.h> |
| 40 | #include <sys/proc.h> |
| 41 | #include <sys/caps.h> |
| 42 | #include <sys/time.h> |
| 43 | #include <sys/timex.h> |
| 44 | #include <sys/timepps.h> |
| 45 | #include <sys/sysctl.h> |
| 46 | |
| 47 | #include <sys/thread2.h> |
| 48 | |
| 49 | /* |
| 50 | * Single-precision macros for 64-bit machines |
| 51 | */ |
| 52 | typedef long long l_fp; |
| 53 | #define L_ADD(v, u) ((v) += (u)) |
| 54 | #define L_SUB(v, u) ((v) -= (u)) |
| 55 | #define L_ADDHI(v, a) ((v) += (long long)(a) << 32) |
| 56 | #define L_NEG(v) ((v) = -(v)) |
| 57 | #define L_RSHIFT(v, n) \ |
| 58 | do { \ |
| 59 | if ((v) < 0) \ |
| 60 | (v) = -(-(v) >> (n)); \ |
| 61 | else \ |
| 62 | (v) = (v) >> (n); \ |
| 63 | } while (0) |
| 64 | #define L_MPY(v, a) ((v) *= (a)) |
| 65 | #define L_CLR(v) ((v) = 0) |
| 66 | #define L_ISNEG(v) ((v) < 0) |
| 67 | #define L_LINT(v, a) ((v) = (long long)(a) << 32) |
| 68 | #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) |
| 69 | |
| 70 | /* |
| 71 | * Generic NTP kernel interface |
| 72 | * |
| 73 | * These routines constitute the Network Time Protocol (NTP) interfaces |
| 74 | * for user and daemon application programs. The ntp_gettime() routine |
| 75 | * provides the time, maximum error (synch distance) and estimated error |
| 76 | * (dispersion) to client user application programs. The ntp_adjtime() |
| 77 | * routine is used by the NTP daemon to adjust the system clock to an |
| 78 | * externally derived time. The time offset and related variables set by |
| 79 | * this routine are used by other routines in this module to adjust the |
| 80 | * phase and frequency of the clock discipline loop which controls the |
| 81 | * system clock. |
| 82 | * |
| 83 | * When the kernel time is reckoned directly in nanoseconds (NTP_NANO |
| 84 | * defined), the time at each tick interrupt is derived directly from |
| 85 | * the kernel time variable. When the kernel time is reckoned in |
| 86 | * microseconds, (NTP_NANO undefined), the time is derived from the |
| 87 | * kernel time variable together with a variable representing the |
| 88 | * leftover nanoseconds at the last tick interrupt. In either case, the |
| 89 | * current nanosecond time is reckoned from these values plus an |
| 90 | * interpolated value derived by the clock routines in another |
| 91 | * architecture-specific module. The interpolation can use either a |
| 92 | * dedicated counter or a processor cycle counter (PCC) implemented in |
| 93 | * some architectures. |
| 94 | * |
| 95 | * Note that all routines must run at priority splclock or higher. |
| 96 | */ |
| 97 | /* |
| 98 | * Phase/frequency-lock loop (PLL/FLL) definitions |
| 99 | * |
| 100 | * The nanosecond clock discipline uses two variable types, time |
| 101 | * variables and frequency variables. Both types are represented as 64- |
| 102 | * bit fixed-point quantities with the decimal point between two 32-bit |
| 103 | * halves. On a 32-bit machine, each half is represented as a single |
| 104 | * word and mathematical operations are done using multiple-precision |
| 105 | * arithmetic. On a 64-bit machine, ordinary computer arithmetic is |
| 106 | * used. |
| 107 | * |
| 108 | * A time variable is a signed 64-bit fixed-point number in ns and |
| 109 | * fraction. It represents the remaining time offset to be amortized |
| 110 | * over succeeding tick interrupts. The maximum time offset is about |
| 111 | * 0.5 s and the resolution is about 2.3e-10 ns. |
| 112 | * |
| 113 | * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 |
| 114 | * 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 |
| 115 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 116 | * |s s s| ns | |
| 117 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 118 | * | fraction | |
| 119 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 120 | * |
| 121 | * A frequency variable is a signed 64-bit fixed-point number in ns/s |
| 122 | * and fraction. It represents the ns and fraction to be added to the |
| 123 | * kernel time variable at each second. The maximum frequency offset is |
| 124 | * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. |
| 125 | * |
| 126 | * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 |
| 127 | * 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 |
| 128 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 129 | * |s s s s s s s s s s s s s| ns/s | |
| 130 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 131 | * | fraction | |
| 132 | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| 133 | */ |
| 134 | /* |
| 135 | * The following variables establish the state of the PLL/FLL and the |
| 136 | * residual time and frequency offset of the local clock. |
| 137 | */ |
| 138 | #define SHIFT_PLL 4 /* PLL loop gain (shift) */ |
| 139 | #define SHIFT_FLL 2 /* FLL loop gain (shift) */ |
| 140 | |
| 141 | static int time_state = TIME_OK; /* clock state */ |
| 142 | static int time_status = STA_UNSYNC; /* clock status bits */ |
| 143 | static long time_tai; /* TAI offset (s) */ |
| 144 | static long time_monitor; /* last time offset scaled (ns) */ |
| 145 | static long time_constant; /* poll interval (shift) (s) */ |
| 146 | static long time_precision = 1; /* clock precision (ns) */ |
| 147 | static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */ |
| 148 | static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ |
| 149 | static time_t time_reftime; /* time at last adjustment (s) */ |
| 150 | static long time_tick; /* nanoseconds per tick (ns) */ |
| 151 | static l_fp time_offset; /* time offset (ns) */ |
| 152 | static l_fp time_freq; /* frequency offset (ns/s) */ |
| 153 | static l_fp time_adj; /* tick adjust (ns/s) */ |
| 154 | |
| 155 | static struct lock ntp_lock = LOCK_INITIALIZER("ntplk", 0, 0); |
| 156 | |
| 157 | #ifdef PPS_SYNC |
| 158 | /* |
| 159 | * The following variables are used when a pulse-per-second (PPS) signal |
| 160 | * is available and connected via a modem control lead. They establish |
| 161 | * the engineering parameters of the clock discipline loop when |
| 162 | * controlled by the PPS signal. |
| 163 | */ |
| 164 | #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ |
| 165 | #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ |
| 166 | #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ |
| 167 | #define PPS_PAVG 4 /* phase avg interval (s) (shift) */ |
| 168 | #define PPS_VALID 120 /* PPS signal watchdog max (s) */ |
| 169 | #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ |
| 170 | #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ |
| 171 | |
| 172 | static struct timespec pps_tf[3]; /* phase median filter */ |
| 173 | static l_fp pps_freq; /* scaled frequency offset (ns/s) */ |
| 174 | static long pps_fcount; /* frequency accumulator */ |
| 175 | static long pps_jitter; /* nominal jitter (ns) */ |
| 176 | static long pps_stabil; /* nominal stability (scaled ns/s) */ |
| 177 | static long pps_lastsec; /* time at last calibration (s) */ |
| 178 | static int pps_valid; /* signal watchdog counter */ |
| 179 | static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ |
| 180 | static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ |
| 181 | static int pps_intcnt; /* wander counter */ |
| 182 | |
| 183 | /* |
| 184 | * PPS signal quality monitors |
| 185 | */ |
| 186 | static long pps_calcnt; /* calibration intervals */ |
| 187 | static long pps_jitcnt; /* jitter limit exceeded */ |
| 188 | static long pps_stbcnt; /* stability limit exceeded */ |
| 189 | static long pps_errcnt; /* calibration errors */ |
| 190 | #endif /* PPS_SYNC */ |
| 191 | /* |
| 192 | * End of phase/frequency-lock loop (PLL/FLL) definitions |
| 193 | */ |
| 194 | |
| 195 | static void ntp_init(void); |
| 196 | static void hardupdate(long offset); |
| 197 | |
| 198 | /* |
| 199 | * ntp_gettime() - NTP user application interface |
| 200 | * |
| 201 | * See the timex.h header file for synopsis and API description. Note |
| 202 | * that the TAI offset is returned in the ntvtimeval.tai structure |
| 203 | * member. |
| 204 | */ |
| 205 | static int |
| 206 | ntp_sysctl(SYSCTL_HANDLER_ARGS) |
| 207 | { |
| 208 | struct ntptimeval ntv; /* temporary structure */ |
| 209 | struct timespec atv; /* nanosecond time */ |
| 210 | int error; |
| 211 | |
| 212 | lockmgr(&ntp_lock, LK_EXCLUSIVE); |
| 213 | |
| 214 | nanotime(&atv); |
| 215 | ntv.time.tv_sec = atv.tv_sec; |
| 216 | ntv.time.tv_nsec = atv.tv_nsec; |
| 217 | ntv.maxerror = time_maxerror; |
| 218 | ntv.esterror = time_esterror; |
| 219 | ntv.tai = time_tai; |
| 220 | ntv.time_state = time_state; |
| 221 | |
| 222 | /* |
| 223 | * Status word error decode. If any of these conditions occur, |
| 224 | * an error is returned, instead of the status word. Most |
| 225 | * applications will care only about the fact the system clock |
| 226 | * may not be trusted, not about the details. |
| 227 | * |
| 228 | * Hardware or software error |
| 229 | */ |
| 230 | if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || |
| 231 | |
| 232 | /* |
| 233 | * PPS signal lost when either time or frequency synchronization |
| 234 | * requested |
| 235 | */ |
| 236 | (time_status & (STA_PPSFREQ | STA_PPSTIME) && |
| 237 | !(time_status & STA_PPSSIGNAL)) || |
| 238 | |
| 239 | /* |
| 240 | * PPS jitter exceeded when time synchronization requested |
| 241 | */ |
| 242 | (time_status & STA_PPSTIME && |
| 243 | time_status & STA_PPSJITTER) || |
| 244 | |
| 245 | /* |
| 246 | * PPS wander exceeded or calibration error when frequency |
| 247 | * synchronization requested |
| 248 | */ |
| 249 | (time_status & STA_PPSFREQ && |
| 250 | time_status & (STA_PPSWANDER | STA_PPSERROR))) { |
| 251 | ntv.time_state = TIME_ERROR; |
| 252 | } |
| 253 | |
| 254 | error = sysctl_handle_opaque(oidp, &ntv, sizeof ntv, req); |
| 255 | lockmgr(&ntp_lock, LK_RELEASE); |
| 256 | |
| 257 | return error; |
| 258 | } |
| 259 | |
| 260 | SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, ""); |
| 261 | SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD, |
| 262 | 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", ""); |
| 263 | |
| 264 | #ifdef PPS_SYNC |
| 265 | SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, ""); |
| 266 | SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, ""); |
| 267 | SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, ""); |
| 268 | |
| 269 | SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", ""); |
| 270 | SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", ""); |
| 271 | #endif |
| 272 | /* |
| 273 | * ntp_adjtime() - NTP daemon application interface |
| 274 | * |
| 275 | * See the timex.h header file for synopsis and API description. Note |
| 276 | * that the timex.constant structure member has a dual purpose to set |
| 277 | * the time constant and to set the TAI offset. |
| 278 | * |
| 279 | * MPALMOSTSAFE |
| 280 | */ |
| 281 | int |
| 282 | sys_ntp_adjtime(struct sysmsg *sysmsg, const struct ntp_adjtime_args *uap) |
| 283 | { |
| 284 | struct timex ntv; /* temporary structure */ |
| 285 | long freq; /* frequency ns/s) */ |
| 286 | int modes; /* mode bits from structure */ |
| 287 | int error; |
| 288 | |
| 289 | error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); |
| 290 | if (error) |
| 291 | return(error); |
| 292 | |
| 293 | /* |
| 294 | * Update selected clock variables - only the superuser can |
| 295 | * change anything. Note that there is no error checking here on |
| 296 | * the assumption the superuser should know what it is doing. |
| 297 | * Note that either the time constant or TAI offset are loaded |
| 298 | * from the ntv.constant member, depending on the mode bits. If |
| 299 | * the STA_PLL bit in the status word is cleared, the state and |
| 300 | * status words are reset to the initial values at boot. |
| 301 | */ |
| 302 | modes = ntv.modes; |
| 303 | if (modes) |
| 304 | error = caps_priv_check_self(SYSCAP_NOSETTIME); |
| 305 | if (error) |
| 306 | return (error); |
| 307 | |
| 308 | lockmgr(&ntp_lock, LK_EXCLUSIVE); |
| 309 | crit_enter(); |
| 310 | if (modes & MOD_MAXERROR) |
| 311 | time_maxerror = ntv.maxerror; |
| 312 | if (modes & MOD_ESTERROR) |
| 313 | time_esterror = ntv.esterror; |
| 314 | if (modes & MOD_STATUS) { |
| 315 | if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { |
| 316 | time_state = TIME_OK; |
| 317 | time_status = STA_UNSYNC; |
| 318 | #ifdef PPS_SYNC |
| 319 | pps_shift = PPS_FAVG; |
| 320 | #endif /* PPS_SYNC */ |
| 321 | } |
| 322 | time_status &= STA_RONLY; |
| 323 | time_status |= ntv.status & ~STA_RONLY; |
| 324 | } |
| 325 | if (modes & MOD_TIMECONST) { |
| 326 | if (ntv.constant < 0) |
| 327 | time_constant = 0; |
| 328 | else if (ntv.constant > MAXTC) |
| 329 | time_constant = MAXTC; |
| 330 | else |
| 331 | time_constant = ntv.constant; |
| 332 | } |
| 333 | if (modes & MOD_TAI) { |
| 334 | if (ntv.constant > 0) /* XXX zero & negative numbers ? */ |
| 335 | time_tai = ntv.constant; |
| 336 | } |
| 337 | #ifdef PPS_SYNC |
| 338 | if (modes & MOD_PPSMAX) { |
| 339 | if (ntv.shift < PPS_FAVG) |
| 340 | pps_shiftmax = PPS_FAVG; |
| 341 | else if (ntv.shift > PPS_FAVGMAX) |
| 342 | pps_shiftmax = PPS_FAVGMAX; |
| 343 | else |
| 344 | pps_shiftmax = ntv.shift; |
| 345 | } |
| 346 | #endif /* PPS_SYNC */ |
| 347 | if (modes & MOD_NANO) |
| 348 | time_status |= STA_NANO; |
| 349 | if (modes & MOD_MICRO) |
| 350 | time_status &= ~STA_NANO; |
| 351 | if (modes & MOD_CLKB) |
| 352 | time_status |= STA_CLK; |
| 353 | if (modes & MOD_CLKA) |
| 354 | time_status &= ~STA_CLK; |
| 355 | if (modes & MOD_OFFSET) { |
| 356 | if (time_status & STA_NANO) |
| 357 | hardupdate(ntv.offset); |
| 358 | else |
| 359 | hardupdate(ntv.offset * 1000); |
| 360 | } |
| 361 | /* |
| 362 | * Note: the userland specified frequency is in seconds per second |
| 363 | * times 65536e+6. Multiply by a thousand and divide by 65336 to |
| 364 | * get nanoseconds. |
| 365 | */ |
| 366 | if (modes & MOD_FREQUENCY) { |
| 367 | freq = (ntv.freq * 1000LL) >> 16; |
| 368 | if (freq > MAXFREQ) |
| 369 | L_LINT(time_freq, MAXFREQ); |
| 370 | else if (freq < -MAXFREQ) |
| 371 | L_LINT(time_freq, -MAXFREQ); |
| 372 | else |
| 373 | L_LINT(time_freq, freq); |
| 374 | #ifdef PPS_SYNC |
| 375 | pps_freq = time_freq; |
| 376 | #endif /* PPS_SYNC */ |
| 377 | } |
| 378 | |
| 379 | /* |
| 380 | * Retrieve all clock variables. Note that the TAI offset is |
| 381 | * returned only by ntp_gettime(); |
| 382 | */ |
| 383 | if (time_status & STA_NANO) |
| 384 | ntv.offset = time_monitor; |
| 385 | else |
| 386 | ntv.offset = time_monitor / 1000; /* XXX rounding ? */ |
| 387 | ntv.freq = L_GINT((time_freq / 1000LL) << 16); |
| 388 | ntv.maxerror = time_maxerror; |
| 389 | ntv.esterror = time_esterror; |
| 390 | ntv.status = time_status; |
| 391 | ntv.constant = time_constant; |
| 392 | if (time_status & STA_NANO) |
| 393 | ntv.precision = time_precision; |
| 394 | else |
| 395 | ntv.precision = time_precision / 1000; |
| 396 | ntv.tolerance = MAXFREQ * SCALE_PPM; |
| 397 | #ifdef PPS_SYNC |
| 398 | ntv.shift = pps_shift; |
| 399 | ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16); |
| 400 | if (time_status & STA_NANO) |
| 401 | ntv.jitter = pps_jitter; |
| 402 | else |
| 403 | ntv.jitter = pps_jitter / 1000; |
| 404 | ntv.stabil = pps_stabil; |
| 405 | ntv.calcnt = pps_calcnt; |
| 406 | ntv.errcnt = pps_errcnt; |
| 407 | ntv.jitcnt = pps_jitcnt; |
| 408 | ntv.stbcnt = pps_stbcnt; |
| 409 | #endif /* PPS_SYNC */ |
| 410 | crit_exit(); |
| 411 | lockmgr(&ntp_lock, LK_RELEASE); |
| 412 | |
| 413 | error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); |
| 414 | if (error) |
| 415 | return (error); |
| 416 | |
| 417 | /* |
| 418 | * Status word error decode. See comments in |
| 419 | * ntp_gettime() routine. |
| 420 | */ |
| 421 | if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || |
| 422 | (time_status & (STA_PPSFREQ | STA_PPSTIME) && |
| 423 | !(time_status & STA_PPSSIGNAL)) || |
| 424 | (time_status & STA_PPSTIME && |
| 425 | time_status & STA_PPSJITTER) || |
| 426 | (time_status & STA_PPSFREQ && |
| 427 | time_status & (STA_PPSWANDER | STA_PPSERROR))) { |
| 428 | sysmsg->sysmsg_result = TIME_ERROR; |
| 429 | } else { |
| 430 | sysmsg->sysmsg_result = time_state; |
| 431 | } |
| 432 | return (0); |
| 433 | } |
| 434 | |
| 435 | /* |
| 436 | * second_overflow() - called after ntp_tick_adjust() |
| 437 | * |
| 438 | * This routine is ordinarily called from hardclock() whenever the seconds |
| 439 | * hand rolls over. It returns leap seconds to add or drop, and sets nsec_adj |
| 440 | * to the total adjustment to make over the next second in (ns << 32). |
| 441 | * |
| 442 | * This routine is only called by cpu #0. |
| 443 | */ |
| 444 | int |
| 445 | ntp_update_second(time_t newsec, int64_t *nsec_adj) |
| 446 | { |
| 447 | l_fp ftemp; /* 32/64-bit temporary */ |
| 448 | int adjsec = 0; |
| 449 | |
| 450 | /* |
| 451 | * On rollover of the second both the nanosecond and microsecond |
| 452 | * clocks are updated and the state machine cranked as |
| 453 | * necessary. The phase adjustment to be used for the next |
| 454 | * second is calculated and the maximum error is increased by |
| 455 | * the tolerance. |
| 456 | */ |
| 457 | time_maxerror += MAXFREQ / 1000; |
| 458 | |
| 459 | /* |
| 460 | * Leap second processing. If in leap-insert state at |
| 461 | * the end of the day, the system clock is set back one |
| 462 | * second; if in leap-delete state, the system clock is |
| 463 | * set ahead one second. The nano_time() routine or |
| 464 | * external clock driver will insure that reported time |
| 465 | * is always monotonic. |
| 466 | */ |
| 467 | switch (time_state) { |
| 468 | |
| 469 | /* |
| 470 | * No warning. |
| 471 | */ |
| 472 | case TIME_OK: |
| 473 | if (time_status & STA_INS) |
| 474 | time_state = TIME_INS; |
| 475 | else if (time_status & STA_DEL) |
| 476 | time_state = TIME_DEL; |
| 477 | break; |
| 478 | |
| 479 | /* |
| 480 | * Insert second 23:59:60 following second |
| 481 | * 23:59:59. |
| 482 | */ |
| 483 | case TIME_INS: |
| 484 | if (!(time_status & STA_INS)) |
| 485 | time_state = TIME_OK; |
| 486 | else if ((newsec) % 86400 == 0) { |
| 487 | --adjsec; |
| 488 | time_state = TIME_OOP; |
| 489 | } |
| 490 | break; |
| 491 | |
| 492 | /* |
| 493 | * Delete second 23:59:59. |
| 494 | */ |
| 495 | case TIME_DEL: |
| 496 | if (!(time_status & STA_DEL)) |
| 497 | time_state = TIME_OK; |
| 498 | else if (((newsec) + 1) % 86400 == 0) { |
| 499 | ++adjsec; |
| 500 | time_tai--; |
| 501 | time_state = TIME_WAIT; |
| 502 | } |
| 503 | break; |
| 504 | |
| 505 | /* |
| 506 | * Insert second in progress. |
| 507 | */ |
| 508 | case TIME_OOP: |
| 509 | time_tai++; |
| 510 | time_state = TIME_WAIT; |
| 511 | break; |
| 512 | |
| 513 | /* |
| 514 | * Wait for status bits to clear. |
| 515 | */ |
| 516 | case TIME_WAIT: |
| 517 | if (!(time_status & (STA_INS | STA_DEL))) |
| 518 | time_state = TIME_OK; |
| 519 | } |
| 520 | |
| 521 | /* |
| 522 | * time_offset represents the total time adjustment we wish to |
| 523 | * make (over no particular period of time). time_freq represents |
| 524 | * the frequency compensation we wish to apply. |
| 525 | * |
| 526 | * time_adj represents the total adjustment we wish to make over |
| 527 | * one full second. hardclock usually applies this adjustment in |
| 528 | * time_adj / hz jumps, hz times a second. |
| 529 | */ |
| 530 | ftemp = time_offset; |
| 531 | #ifdef PPS_SYNC |
| 532 | /* XXX even if PPS signal dies we should finish adjustment ? */ |
| 533 | if ((time_status & STA_PPSTIME) && (time_status & STA_PPSSIGNAL)) |
| 534 | L_RSHIFT(ftemp, pps_shift); |
| 535 | else |
| 536 | L_RSHIFT(ftemp, SHIFT_PLL + time_constant); |
| 537 | #else |
| 538 | L_RSHIFT(ftemp, SHIFT_PLL + time_constant); |
| 539 | #endif /* PPS_SYNC */ |
| 540 | time_adj = ftemp; /* adjustment for part of the offset */ |
| 541 | L_SUB(time_offset, ftemp); |
| 542 | L_ADD(time_adj, time_freq); /* add frequency correction */ |
| 543 | *nsec_adj = time_adj; |
| 544 | #ifdef PPS_SYNC |
| 545 | if (pps_valid > 0) |
| 546 | pps_valid--; |
| 547 | else |
| 548 | time_status &= ~STA_PPSSIGNAL; |
| 549 | #endif /* PPS_SYNC */ |
| 550 | return(adjsec); |
| 551 | } |
| 552 | |
| 553 | /* |
| 554 | * ntp_init() - initialize variables and structures |
| 555 | * |
| 556 | * This routine must be called after the kernel variables hz and tick |
| 557 | * are set or changed and before the next tick interrupt. In this |
| 558 | * particular implementation, these values are assumed set elsewhere in |
| 559 | * the kernel. The design allows the clock frequency and tick interval |
| 560 | * to be changed while the system is running. So, this routine should |
| 561 | * probably be integrated with the code that does that. |
| 562 | */ |
| 563 | static void |
| 564 | ntp_init(void) |
| 565 | { |
| 566 | |
| 567 | /* |
| 568 | * The following variable must be initialized any time the |
| 569 | * kernel variable hz is changed. |
| 570 | */ |
| 571 | time_tick = NANOSECOND / hz; |
| 572 | |
| 573 | /* |
| 574 | * The following variables are initialized only at startup. Only |
| 575 | * those structures not cleared by the compiler need to be |
| 576 | * initialized, and these only in the simulator. In the actual |
| 577 | * kernel, any nonzero values here will quickly evaporate. |
| 578 | */ |
| 579 | L_CLR(time_offset); |
| 580 | L_CLR(time_freq); |
| 581 | #ifdef PPS_SYNC |
| 582 | pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; |
| 583 | pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; |
| 584 | pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; |
| 585 | pps_fcount = 0; |
| 586 | L_CLR(pps_freq); |
| 587 | #endif /* PPS_SYNC */ |
| 588 | } |
| 589 | |
| 590 | SYSINIT(ntpclocks, SI_BOOT2_CLOCKS, SI_ORDER_FIRST, ntp_init, NULL); |
| 591 | |
| 592 | /* |
| 593 | * hardupdate() - local clock update |
| 594 | * |
| 595 | * This routine is called by ntp_adjtime() to update the local clock |
| 596 | * phase and frequency. The implementation is of an adaptive-parameter, |
| 597 | * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new |
| 598 | * time and frequency offset estimates for each call. If the kernel PPS |
| 599 | * discipline code is configured (PPS_SYNC), the PPS signal itself |
| 600 | * determines the new time offset, instead of the calling argument. |
| 601 | * Presumably, calls to ntp_adjtime() occur only when the caller |
| 602 | * believes the local clock is valid within some bound (+-128 ms with |
| 603 | * NTP). If the caller's time is far different than the PPS time, an |
| 604 | * argument will ensue, and it's not clear who will lose. |
| 605 | * |
| 606 | * For uncompensated quartz crystal oscillators and nominal update |
| 607 | * intervals less than 256 s, operation should be in phase-lock mode, |
| 608 | * where the loop is disciplined to phase. For update intervals greater |
| 609 | * than 1024 s, operation should be in frequency-lock mode, where the |
| 610 | * loop is disciplined to frequency. Between 256 s and 1024 s, the mode |
| 611 | * is selected by the STA_MODE status bit. |
| 612 | */ |
| 613 | static void |
| 614 | hardupdate(long offset) |
| 615 | { |
| 616 | long mtemp; |
| 617 | l_fp ftemp; |
| 618 | |
| 619 | /* |
| 620 | * Select how the phase is to be controlled and from which |
| 621 | * source. If the PPS signal is present and enabled to |
| 622 | * discipline the time, the PPS offset is used; otherwise, the |
| 623 | * argument offset is used. |
| 624 | */ |
| 625 | if (!(time_status & STA_PLL)) |
| 626 | return; |
| 627 | if (!((time_status & STA_PPSTIME) && (time_status & STA_PPSSIGNAL))) { |
| 628 | if (offset > MAXPHASE) |
| 629 | time_monitor = MAXPHASE; |
| 630 | else if (offset < -MAXPHASE) |
| 631 | time_monitor = -MAXPHASE; |
| 632 | else |
| 633 | time_monitor = offset; |
| 634 | L_LINT(time_offset, time_monitor); |
| 635 | } |
| 636 | |
| 637 | /* |
| 638 | * Select how the frequency is to be controlled and in which |
| 639 | * mode (PLL or FLL). If the PPS signal is present and enabled |
| 640 | * to discipline the frequency, the PPS frequency is used; |
| 641 | * otherwise, the argument offset is used to compute it. |
| 642 | */ |
| 643 | if ((time_status & STA_PPSFREQ) && time_status & STA_PPSSIGNAL) { |
| 644 | time_reftime = time_uptime; |
| 645 | return; |
| 646 | } |
| 647 | if ((time_status & STA_FREQHOLD) || time_reftime == 0) |
| 648 | time_reftime = time_uptime; |
| 649 | mtemp = time_uptime - time_reftime; |
| 650 | L_LINT(ftemp, time_monitor); |
| 651 | L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); |
| 652 | L_MPY(ftemp, mtemp); |
| 653 | L_ADD(time_freq, ftemp); |
| 654 | time_status &= ~STA_MODE; |
| 655 | if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) { |
| 656 | L_LINT(ftemp, (time_monitor << 4) / mtemp); |
| 657 | L_RSHIFT(ftemp, SHIFT_FLL + 4); |
| 658 | L_ADD(time_freq, ftemp); |
| 659 | time_status |= STA_MODE; |
| 660 | } |
| 661 | time_reftime = time_uptime; |
| 662 | if (L_GINT(time_freq) > MAXFREQ) |
| 663 | L_LINT(time_freq, MAXFREQ); |
| 664 | else if (L_GINT(time_freq) < -MAXFREQ) |
| 665 | L_LINT(time_freq, -MAXFREQ); |
| 666 | } |
| 667 | |
| 668 | #ifdef PPS_SYNC |
| 669 | /* |
| 670 | * hardpps() - discipline CPU clock oscillator to external PPS signal |
| 671 | * |
| 672 | * This routine is called at each PPS interrupt in order to discipline |
| 673 | * the CPU clock oscillator to the PPS signal. There are two independent |
| 674 | * first-order feedback loops, one for the phase, the other for the |
| 675 | * frequency. The phase loop measures and grooms the PPS phase offset |
| 676 | * and leaves it in a handy spot for the seconds overflow routine. The |
| 677 | * frequency loop averages successive PPS phase differences and |
| 678 | * calculates the PPS frequency offset, which is also processed by the |
| 679 | * seconds overflow routine. The code requires the caller to capture the |
| 680 | * time and architecture-dependent hardware counter values in |
| 681 | * nanoseconds at the on-time PPS signal transition. |
| 682 | * |
| 683 | * Note that, on some Unix systems this routine runs at an interrupt |
| 684 | * priority level higher than the timer interrupt routine hardclock(). |
| 685 | * Therefore, the variables used are distinct from the hardclock() |
| 686 | * variables, except for the actual time and frequency variables, which |
| 687 | * are determined by this routine and updated atomically. |
| 688 | */ |
| 689 | void |
| 690 | hardpps(struct timespec *tsp, long nsec) |
| 691 | { |
| 692 | long u_sec, u_nsec, v_nsec; /* temps */ |
| 693 | l_fp ftemp; |
| 694 | |
| 695 | /* |
| 696 | * The signal is first processed by a range gate and frequency |
| 697 | * discriminator. The range gate rejects noise spikes outside |
| 698 | * the range +-500 us. The frequency discriminator rejects input |
| 699 | * signals with apparent frequency outside the range 1 +-500 |
| 700 | * PPM. If two hits occur in the same second, we ignore the |
| 701 | * later hit; if not and a hit occurs outside the range gate, |
| 702 | * keep the later hit for later comparison, but do not process |
| 703 | * it. |
| 704 | */ |
| 705 | time_status |= STA_PPSSIGNAL | STA_PPSJITTER; |
| 706 | time_status &= ~(STA_PPSWANDER | STA_PPSERROR); |
| 707 | pps_valid = PPS_VALID; |
| 708 | u_sec = tsp->tv_sec; |
| 709 | u_nsec = tsp->tv_nsec; |
| 710 | if (u_nsec >= (NANOSECOND >> 1)) { |
| 711 | u_nsec -= NANOSECOND; |
| 712 | u_sec++; |
| 713 | } |
| 714 | v_nsec = u_nsec - pps_tf[0].tv_nsec; |
| 715 | if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - |
| 716 | MAXFREQ) |
| 717 | return; |
| 718 | pps_tf[2] = pps_tf[1]; |
| 719 | pps_tf[1] = pps_tf[0]; |
| 720 | pps_tf[0].tv_sec = u_sec; |
| 721 | pps_tf[0].tv_nsec = u_nsec; |
| 722 | |
| 723 | /* |
| 724 | * Compute the difference between the current and previous |
| 725 | * counter values. If the difference exceeds 0.5 s, assume it |
| 726 | * has wrapped around, so correct 1.0 s. If the result exceeds |
| 727 | * the tick interval, the sample point has crossed a tick |
| 728 | * boundary during the last second, so correct the tick. Very |
| 729 | * intricate. |
| 730 | */ |
| 731 | u_nsec = nsec; |
| 732 | if (u_nsec > (NANOSECOND >> 1)) |
| 733 | u_nsec -= NANOSECOND; |
| 734 | else if (u_nsec < -(NANOSECOND >> 1)) |
| 735 | u_nsec += NANOSECOND; |
| 736 | pps_fcount += u_nsec; |
| 737 | if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) |
| 738 | return; |
| 739 | time_status &= ~STA_PPSJITTER; |
| 740 | |
| 741 | /* |
| 742 | * A three-stage median filter is used to help denoise the PPS |
| 743 | * time. The median sample becomes the time offset estimate; the |
| 744 | * difference between the other two samples becomes the time |
| 745 | * dispersion (jitter) estimate. |
| 746 | */ |
| 747 | if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { |
| 748 | if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { |
| 749 | v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ |
| 750 | u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; |
| 751 | } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { |
| 752 | v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ |
| 753 | u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; |
| 754 | } else { |
| 755 | v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ |
| 756 | u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; |
| 757 | } |
| 758 | } else { |
| 759 | if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { |
| 760 | v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ |
| 761 | u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; |
| 762 | } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { |
| 763 | v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ |
| 764 | u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; |
| 765 | } else { |
| 766 | v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ |
| 767 | u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; |
| 768 | } |
| 769 | } |
| 770 | |
| 771 | /* |
| 772 | * Nominal jitter is due to PPS signal noise and interrupt |
| 773 | * latency. If it exceeds the popcorn threshold, the sample is |
| 774 | * discarded. otherwise, if so enabled, the time offset is |
| 775 | * updated. We can tolerate a modest loss of data here without |
| 776 | * much degrading time accuracy. |
| 777 | */ |
| 778 | if (u_nsec > (pps_jitter << PPS_POPCORN)) { |
| 779 | time_status |= STA_PPSJITTER; |
| 780 | pps_jitcnt++; |
| 781 | } else if (time_status & STA_PPSTIME) { |
| 782 | time_monitor = -v_nsec; |
| 783 | L_LINT(time_offset, time_monitor); |
| 784 | } |
| 785 | pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; |
| 786 | u_sec = pps_tf[0].tv_sec - pps_lastsec; |
| 787 | if (u_sec < (1 << pps_shift)) |
| 788 | return; |
| 789 | |
| 790 | /* |
| 791 | * At the end of the calibration interval the difference between |
| 792 | * the first and last counter values becomes the scaled |
| 793 | * frequency. It will later be divided by the length of the |
| 794 | * interval to determine the frequency update. If the frequency |
| 795 | * exceeds a sanity threshold, or if the actual calibration |
| 796 | * interval is not equal to the expected length, the data are |
| 797 | * discarded. We can tolerate a modest loss of data here without |
| 798 | * much degrading frequency accuracy. |
| 799 | */ |
| 800 | pps_calcnt++; |
| 801 | v_nsec = -pps_fcount; |
| 802 | pps_lastsec = pps_tf[0].tv_sec; |
| 803 | pps_fcount = 0; |
| 804 | u_nsec = MAXFREQ << pps_shift; |
| 805 | if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << |
| 806 | pps_shift)) { |
| 807 | time_status |= STA_PPSERROR; |
| 808 | pps_errcnt++; |
| 809 | return; |
| 810 | } |
| 811 | |
| 812 | /* |
| 813 | * Here the raw frequency offset and wander (stability) is |
| 814 | * calculated. If the wander is less than the wander threshold |
| 815 | * for four consecutive averaging intervals, the interval is |
| 816 | * doubled; if it is greater than the threshold for four |
| 817 | * consecutive intervals, the interval is halved. The scaled |
| 818 | * frequency offset is converted to frequency offset. The |
| 819 | * stability metric is calculated as the average of recent |
| 820 | * frequency changes, but is used only for performance |
| 821 | * monitoring. |
| 822 | */ |
| 823 | L_LINT(ftemp, v_nsec); |
| 824 | L_RSHIFT(ftemp, pps_shift); |
| 825 | L_SUB(ftemp, pps_freq); |
| 826 | u_nsec = L_GINT(ftemp); |
| 827 | if (u_nsec > PPS_MAXWANDER) { |
| 828 | L_LINT(ftemp, PPS_MAXWANDER); |
| 829 | pps_intcnt--; |
| 830 | time_status |= STA_PPSWANDER; |
| 831 | pps_stbcnt++; |
| 832 | } else if (u_nsec < -PPS_MAXWANDER) { |
| 833 | L_LINT(ftemp, -PPS_MAXWANDER); |
| 834 | pps_intcnt--; |
| 835 | time_status |= STA_PPSWANDER; |
| 836 | pps_stbcnt++; |
| 837 | } else { |
| 838 | pps_intcnt++; |
| 839 | } |
| 840 | if (pps_intcnt >= 4) { |
| 841 | pps_intcnt = 4; |
| 842 | if (pps_shift < pps_shiftmax) { |
| 843 | pps_shift++; |
| 844 | pps_intcnt = 0; |
| 845 | } |
| 846 | } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { |
| 847 | pps_intcnt = -4; |
| 848 | if (pps_shift > PPS_FAVG) { |
| 849 | pps_shift--; |
| 850 | pps_intcnt = 0; |
| 851 | } |
| 852 | } |
| 853 | if (u_nsec < 0) |
| 854 | u_nsec = -u_nsec; |
| 855 | pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; |
| 856 | |
| 857 | /* |
| 858 | * The PPS frequency is recalculated and clamped to the maximum |
| 859 | * MAXFREQ. If enabled, the system clock frequency is updated as |
| 860 | * well. |
| 861 | */ |
| 862 | L_ADD(pps_freq, ftemp); |
| 863 | u_nsec = L_GINT(pps_freq); |
| 864 | if (u_nsec > MAXFREQ) |
| 865 | L_LINT(pps_freq, MAXFREQ); |
| 866 | else if (u_nsec < -MAXFREQ) |
| 867 | L_LINT(pps_freq, -MAXFREQ); |
| 868 | if (time_status & STA_PPSFREQ) |
| 869 | time_freq = pps_freq; |
| 870 | } |
| 871 | #endif /* PPS_SYNC */ |