1 /*****************************************************************************
3 * Copyright (c) David L. Mills 1993 *
5 * Permission to use, copy, modify, and distribute this software and its *
6 * documentation for any purpose and without fee is hereby granted, provided *
7 * that the above copyright notice appears in all copies and that both the *
8 * copyright notice and this permission notice appear in supporting *
9 * documentation, and that the name University of Delaware not be used in *
10 * advertising or publicity pertaining to distribution of the software *
11 * without specific, written prior permission. The University of Delaware *
12 * makes no representations about the suitability this software for any *
13 * purpose. It is provided "as is" without express or implied warranty. *
15 *****************************************************************************/
18 * Modification history timex.h
20 * 29 Dec 97 Russell King
21 * Moved CLOCK_TICK_RATE, CLOCK_TICK_FACTOR and FINETUNE to asm/timex.h
25 * Shifted LATCH define to allow access to alpha machines.
27 * 26 Sep 94 David L. Mills
28 * Added defines for hybrid phase/frequency-lock loop.
30 * 19 Mar 94 David L. Mills
31 * Moved defines from kernel routines to header file and added new
32 * defines for PPS phase-lock loop.
34 * 20 Feb 94 David L. Mills
35 * Revised status codes and structures for external clock and PPS
38 * 28 Nov 93 David L. Mills
39 * Adjusted parameters to improve stability and increase poll
42 * 17 Sep 93 David L. Mills
43 * Created file $NTP/include/sys/timex.h
44 * 07 Oct 93 Torsten Duwe
45 * Derived linux/timex.h
46 * 1995-08-13 Torsten Duwe
47 * kernel PLL updated to 1994-12-13 specs (rfc-1589)
48 * 1997-08-30 Ulrich Windl
49 * Added new constant NTP_PHASE_LIMIT
51 #ifndef _LINUX_TIMEX_H
52 #define _LINUX_TIMEX_H
54 #include <linux/config.h>
55 #include <linux/compiler.h>
57 #include <asm/param.h>
60 * The following defines establish the engineering parameters of the PLL
61 * model. The HZ variable establishes the timer interrupt frequency, 100 Hz
62 * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the
63 * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the
64 * nearest power of two in order to avoid hardware multiply operations.
66 #if HZ >= 12 && HZ < 24
68 #elif HZ >= 24 && HZ < 48
70 #elif HZ >= 48 && HZ < 96
72 #elif HZ >= 96 && HZ < 192
74 #elif HZ >= 192 && HZ < 384
76 #elif HZ >= 384 && HZ < 768
78 #elif HZ >= 768 && HZ < 1536
85 * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
86 * for a slightly underdamped convergence characteristic. SHIFT_KH
87 * establishes the damping of the FLL and is chosen by wisdom and black
90 * MAXTC establishes the maximum time constant of the PLL. With the
91 * SHIFT_KG and SHIFT_KF values given and a time constant range from
92 * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
95 #define SHIFT_KG 6 /* phase factor (shift) */
96 #define SHIFT_KF 16 /* PLL frequency factor (shift) */
97 #define SHIFT_KH 2 /* FLL frequency factor (shift) */
98 #define MAXTC 6 /* maximum time constant (shift) */
101 * The SHIFT_SCALE define establishes the decimal point of the time_phase
102 * variable which serves as an extension to the low-order bits of the
103 * system clock variable. The SHIFT_UPDATE define establishes the decimal
104 * point of the time_offset variable which represents the current offset
105 * with respect to standard time. The FINENSEC define represents 1 nsec in
108 * SHIFT_USEC defines the scaling (shift) of the time_freq and
109 * time_tolerance variables, which represent the current frequency
110 * offset and maximum frequency tolerance.
112 * FINENSEC is 1 ns in SHIFT_UPDATE units of the time_phase variable.
114 #define SHIFT_SCALE 22 /* phase scale (shift) */
115 #define SHIFT_UPDATE (SHIFT_KG + MAXTC) /* time offset scale (shift) */
116 #define SHIFT_USEC 16 /* frequency offset scale (shift) */
117 #define FINENSEC (1L << (SHIFT_SCALE - 10)) /* ~1 ns in phase units */
119 #define MAXPHASE 512000L /* max phase error (us) */
120 #define MAXFREQ (512L << SHIFT_USEC) /* max frequency error (ppm) */
121 #define MAXTIME (200L << PPS_AVG) /* max PPS error (jitter) (200 us) */
122 #define MINSEC 16L /* min interval between updates (s) */
123 #define MAXSEC 1200L /* max interval between updates (s) */
124 #define NTP_PHASE_LIMIT (MAXPHASE << 5) /* beyond max. dispersion */
127 * The following defines are used only if a pulse-per-second (PPS)
128 * signal is available and connected via a modem control lead, such as
129 * produced by the optional ppsclock feature incorporated in the Sun
130 * asynch driver. They establish the design parameters of the frequency-
131 * lock loop used to discipline the CPU clock oscillator to the PPS
134 * PPS_AVG is the averaging factor for the frequency loop, as well as
135 * the time and frequency dispersion.
137 * PPS_SHIFT and PPS_SHIFTMAX specify the minimum and maximum
138 * calibration intervals, respectively, in seconds as a power of two.
140 * PPS_VALID is the maximum interval before the PPS signal is considered
141 * invalid and protocol updates used directly instead.
143 * MAXGLITCH is the maximum interval before a time offset of more than
144 * MAXTIME is believed.
146 #define PPS_AVG 2 /* pps averaging constant (shift) */
147 #define PPS_SHIFT 2 /* min interval duration (s) (shift) */
148 #define PPS_SHIFTMAX 8 /* max interval duration (s) (shift) */
149 #define PPS_VALID 120 /* pps signal watchdog max (s) */
150 #define MAXGLITCH 30 /* pps signal glitch max (s) */
153 * Pick up the architecture specific timex specifications
155 #include <asm/timex.h>
157 /* LATCH is used in the interval timer and ftape setup. */
158 #define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
160 /* Suppose we want to devide two numbers NOM and DEN: NOM/DEN, the we can
161 * improve accuracy by shifting LSH bits, hence calculating:
163 * This however means trouble for large NOM, because (NOM << LSH) may no
164 * longer fit in 32 bits. The following way of calculating this gives us
165 * some slack, under the following conditions:
166 * - (NOM / DEN) fits in (32 - LSH) bits.
167 * - (NOM % DEN) fits in (32 - LSH) bits.
169 #define SH_DIV(NOM,DEN,LSH) ( ((NOM / DEN) << LSH) \
170 + (((NOM % DEN) << LSH) + DEN / 2) / DEN)
172 /* HZ is the requested value. ACTHZ is actual HZ ("<< 8" is for accuracy) */
173 #define ACTHZ (SH_DIV (CLOCK_TICK_RATE, LATCH, 8))
175 /* TICK_NSEC is the time between ticks in nsec assuming real ACTHZ */
176 #define TICK_NSEC (SH_DIV (1000000UL * 1000, ACTHZ, 8))
178 /* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
179 #define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
181 /* TICK_USEC_TO_NSEC is the time between ticks in nsec assuming real ACTHZ and */
182 /* a value TUSEC for TICK_USEC (can be set bij adjtimex) */
183 #define TICK_USEC_TO_NSEC(TUSEC) (SH_DIV (TUSEC * USER_HZ * 1000, ACTHZ, 8))
186 #include <linux/time.h>
188 * syscall interface - used (mainly by NTP daemon)
189 * to discipline kernel clock oscillator
192 unsigned int modes; /* mode selector */
193 long offset; /* time offset (usec) */
194 long freq; /* frequency offset (scaled ppm) */
195 long maxerror; /* maximum error (usec) */
196 long esterror; /* estimated error (usec) */
197 int status; /* clock command/status */
198 long constant; /* pll time constant */
199 long precision; /* clock precision (usec) (read only) */
200 long tolerance; /* clock frequency tolerance (ppm)
203 struct timeval time; /* (read only) */
204 long tick; /* (modified) usecs between clock ticks */
206 long ppsfreq; /* pps frequency (scaled ppm) (ro) */
207 long jitter; /* pps jitter (us) (ro) */
208 int shift; /* interval duration (s) (shift) (ro) */
209 long stabil; /* pps stability (scaled ppm) (ro) */
210 long jitcnt; /* jitter limit exceeded (ro) */
211 long calcnt; /* calibration intervals (ro) */
212 long errcnt; /* calibration errors (ro) */
213 long stbcnt; /* stability limit exceeded (ro) */
215 int :32; int :32; int :32; int :32;
216 int :32; int :32; int :32; int :32;
217 int :32; int :32; int :32; int :32;
221 * Mode codes (timex.mode)
223 #define ADJ_OFFSET 0x0001 /* time offset */
224 #define ADJ_FREQUENCY 0x0002 /* frequency offset */
225 #define ADJ_MAXERROR 0x0004 /* maximum time error */
226 #define ADJ_ESTERROR 0x0008 /* estimated time error */
227 #define ADJ_STATUS 0x0010 /* clock status */
228 #define ADJ_TIMECONST 0x0020 /* pll time constant */
229 #define ADJ_TICK 0x4000 /* tick value */
230 #define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */
232 /* xntp 3.4 compatibility names */
233 #define MOD_OFFSET ADJ_OFFSET
234 #define MOD_FREQUENCY ADJ_FREQUENCY
235 #define MOD_MAXERROR ADJ_MAXERROR
236 #define MOD_ESTERROR ADJ_ESTERROR
237 #define MOD_STATUS ADJ_STATUS
238 #define MOD_TIMECONST ADJ_TIMECONST
239 #define MOD_CLKB ADJ_TICK
240 #define MOD_CLKA ADJ_OFFSET_SINGLESHOT /* 0x8000 in original */
244 * Status codes (timex.status)
246 #define STA_PLL 0x0001 /* enable PLL updates (rw) */
247 #define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */
248 #define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */
249 #define STA_FLL 0x0008 /* select frequency-lock mode (rw) */
251 #define STA_INS 0x0010 /* insert leap (rw) */
252 #define STA_DEL 0x0020 /* delete leap (rw) */
253 #define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */
254 #define STA_FREQHOLD 0x0080 /* hold frequency (rw) */
256 #define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */
257 #define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */
258 #define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */
259 #define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */
261 #define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */
263 #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
264 STA_PPSERROR | STA_CLOCKERR) /* read-only bits */
267 * Clock states (time_state)
269 #define TIME_OK 0 /* clock synchronized, no leap second */
270 #define TIME_INS 1 /* insert leap second */
271 #define TIME_DEL 2 /* delete leap second */
272 #define TIME_OOP 3 /* leap second in progress */
273 #define TIME_WAIT 4 /* leap second has occurred */
274 #define TIME_ERROR 5 /* clock not synchronized */
275 #define TIME_BAD TIME_ERROR /* bw compat */
280 * Note: maximum error = NTP synch distance = dispersion + delay / 2;
281 * estimated error = NTP dispersion.
283 extern unsigned long tick_usec; /* USER_HZ period (usec) */
284 extern unsigned long tick_nsec; /* ACTHZ period (nsec) */
285 extern int tickadj; /* amount of adjustment per tick */
288 * phase-lock loop variables
290 extern int time_state; /* clock status */
291 extern int time_status; /* clock synchronization status bits */
292 extern long time_offset; /* time adjustment (us) */
293 extern long time_constant; /* pll time constant */
294 extern long time_tolerance; /* frequency tolerance (ppm) */
295 extern long time_precision; /* clock precision (us) */
296 extern long time_maxerror; /* maximum error */
297 extern long time_esterror; /* estimated error */
299 extern long time_phase; /* phase offset (scaled us) */
300 extern long time_freq; /* frequency offset (scaled ppm) */
301 extern long time_adj; /* tick adjust (scaled 1 / HZ) */
302 extern long time_reftime; /* time at last adjustment (s) */
304 extern long time_adjust; /* The amount of adjtime left */
305 extern long time_next_adjust; /* Value for time_adjust at next tick */
307 /* interface variables pps->timer interrupt */
308 extern long pps_offset; /* pps time offset (us) */
309 extern long pps_jitter; /* time dispersion (jitter) (us) */
310 extern long pps_freq; /* frequency offset (scaled ppm) */
311 extern long pps_stabil; /* frequency dispersion (scaled ppm) */
312 extern long pps_valid; /* pps signal watchdog counter */
314 /* interface variables pps->adjtimex */
315 extern int pps_shift; /* interval duration (s) (shift) */
316 extern long pps_jitcnt; /* jitter limit exceeded */
317 extern long pps_calcnt; /* calibration intervals */
318 extern long pps_errcnt; /* calibration errors */
319 extern long pps_stbcnt; /* stability limit exceeded */
321 #ifdef CONFIG_TIME_INTERPOLATION
323 struct time_interpolator {
324 /* cache-hot stuff first: */
325 unsigned long (*get_offset) (void);
326 void (*update) (long);
327 void (*reset) (void);
329 /* cache-cold stuff follows here: */
330 struct time_interpolator *next;
331 unsigned long frequency; /* frequency in counts/second */
332 long drift; /* drift in parts-per-million (or -1) */
335 extern volatile unsigned long last_nsec_offset;
336 #ifndef __HAVE_ARCH_CMPXCHG
337 extern spin_lock_t last_nsec_offset_lock;
339 extern struct time_interpolator *time_interpolator;
341 extern void register_time_interpolator(struct time_interpolator *);
342 extern void unregister_time_interpolator(struct time_interpolator *);
344 /* Called with xtime WRITE-lock acquired. */
346 time_interpolator_update(long delta_nsec)
348 struct time_interpolator *ti = time_interpolator;
350 if (last_nsec_offset > 0) {
351 #ifdef __HAVE_ARCH_CMPXCHG
352 unsigned long new, old;
355 old = last_nsec_offset;
356 if (old > delta_nsec)
357 new = old - delta_nsec;
360 } while (cmpxchg(&last_nsec_offset, old, new) != old);
363 * This really hurts, because it serializes gettimeofday(), but without an
364 * atomic single-word compare-and-exchange, there isn't all that much else
367 spin_lock(&last_nsec_offset_lock);
369 last_nsec_offset -= min(last_nsec_offset, delta_nsec);
371 spin_unlock(&last_nsec_offset_lock);
376 (*ti->update)(delta_nsec);
379 /* Called with xtime WRITE-lock acquired. */
381 time_interpolator_reset(void)
383 struct time_interpolator *ti = time_interpolator;
385 last_nsec_offset = 0;
390 /* Called with xtime READ-lock acquired. */
391 static inline unsigned long
392 time_interpolator_get_offset(void)
394 struct time_interpolator *ti = time_interpolator;
396 return (*ti->get_offset)();
397 return last_nsec_offset;
400 #else /* !CONFIG_TIME_INTERPOLATION */
403 time_interpolator_update(long delta_nsec)
408 time_interpolator_reset(void)
412 static inline unsigned long
413 time_interpolator_get_offset(void)
418 #endif /* !CONFIG_TIME_INTERPOLATION */
422 #endif /* LINUX_TIMEX_H */