FreeBSD/Linux Kernel Cross Reference
sys/sys/timex.h
1 /* $NetBSD: timex.h,v 1.7 2002/03/17 11:14:04 simonb Exp $ */
2
3 /******************************************************************************
4 * *
5 * Copyright (c) David L. Mills 1993, 1994 *
6 * *
7 * Permission to use, copy, modify, and distribute this software and its *
8 * documentation for any purpose and without fee is hereby granted, provided *
9 * that the above copyright notice appears in all copies and that both the *
10 * copyright notice and this permission notice appear in supporting *
11 * documentation, and that the name University of Delaware not be used in *
12 * advertising or publicity pertaining to distribution of the software *
13 * without specific, written prior permission. The University of Delaware *
14 * makes no representations about the suitability this software for any *
15 * purpose. It is provided "as is" without express or implied warranty. *
16 * *
17 ******************************************************************************/
18
19 /*
20 * Modification history timex.h
21 *
22 * 26 Sep 94 David L. Mills
23 * Added defines for hybrid phase/frequency-lock loop.
24 *
25 * 19 Mar 94 David L. Mills
26 * Moved defines from kernel routines to header file and added new
27 * defines for PPS phase-lock loop.
28 *
29 * 20 Feb 94 David L. Mills
30 * Revised status codes and structures for external clock and PPS
31 * signal discipline.
32 *
33 * 28 Nov 93 David L. Mills
34 * Adjusted parameters to improve stability and increase poll
35 * interval.
36 *
37 * 17 Sep 93 David L. Mills
38 * Created file
39 */
40 /*
41 * This header file defines the Network Time Protocol (NTP) interfaces
42 * for user and daemon application programs. These are implemented using
43 * private syscalls and data structures and require specific kernel
44 * support.
45 *
46 * NAME
47 * ntp_gettime - NTP user application interface
48 *
49 * SYNOPSIS
50 * #include <sys/timex.h>
51 *
52 * int syscall(SYS_ntp_gettime, tptr)
53 *
54 * int SYS_ntp_gettime defined in syscall.h header file
55 * struct ntptimeval *tptr pointer to ntptimeval structure
56 *
57 * NAME
58 * ntp_adjtime - NTP daemon application interface
59 *
60 * SYNOPSIS
61 * #include <sys/timex.h>
62 *
63 * int syscall(SYS_ntp_adjtime, mode, tptr)
64 *
65 * int SYS_ntp_adjtime defined in syscall.h header file
66 * struct timex *tptr pointer to timex structure
67 *
68 */
69 #ifndef _SYS_TIMEX_H_
70 #define _SYS_TIMEX_H_ 1
71
72 #ifndef MSDOS /* Microsoft specific */
73 #include <sys/syscall.h>
74 #endif /* MSDOS */
75
76 /*
77 * The following defines establish the engineering parameters of the
78 * phase-lock loop (PLL) model used in the kernel implementation. These
79 * parameters have been carefully chosen by analysis for good stability
80 * and wide dynamic range.
81 *
82 * The hz variable is defined in the kernel build environment. It
83 * establishes the timer interrupt frequency, 100 Hz for the SunOS
84 * kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the OSF/1
85 * kernel. SHIFT_HZ expresses the same value as the nearest power of two
86 * in order to avoid hardware multiply operations.
87 *
88 * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
89 * for a slightly underdamped convergence characteristic. SHIFT_KH
90 * establishes the damping of the FLL and is chosen by wisdom and black
91 * art.
92 *
93 * MAXTC establishes the maximum time constant of the PLL. With the
94 * SHIFT_KG and SHIFT_KF values given and a time constant range from
95 * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
96 * respectively.
97 */
98
99
100 #define SHIFT_KG 6 /* phase factor (shift) */
101 #define SHIFT_KF 16 /* PLL frequency factor (shift) */
102 #define SHIFT_KH 2 /* FLL frequency factor (shift) */
103 #define MAXTC 6 /* maximum time constant (shift) */
104
105 /*
106 * The following defines establish the scaling of the various variables
107 * used by the PLL. They are chosen to allow the greatest precision
108 * possible without overflow of a 32-bit word.
109 *
110 * SHIFT_SCALE defines the scaling (shift) of the time_phase variable,
111 * which serves as a an extension to the low-order bits of the system
112 * clock variable time.tv_usec.
113 *
114 * SHIFT_UPDATE defines the scaling (shift) of the time_offset variable,
115 * which represents the current time offset with respect to standard
116 * time.
117 *
118 * SHIFT_USEC defines the scaling (shift) of the time_freq and
119 * time_tolerance variables, which represent the current frequency
120 * offset and maximum frequency tolerance.
121 *
122 * FINEUSEC is 1 us in SHIFT_UPDATE units of the time_phase variable.
123 */
124 #define SHIFT_SCALE 22 /* phase scale (shift) */
125 #define SHIFT_UPDATE (SHIFT_KG + MAXTC) /* time offset scale (shift) */
126 #define SHIFT_USEC 16 /* frequency offset scale (shift) */
127 #define FINEUSEC (1L << SHIFT_SCALE) /* 1 us in phase units */
128
129 /*
130 * The following defines establish the performance envelope of the PLL.
131 * They insure it operates within predefined limits, in order to satisfy
132 * correctness assertions. An excursion which exceeds these bounds is
133 * clamped to the bound and operation proceeds accordingly. In practice,
134 * this can occur only if something has failed or is operating out of
135 * tolerance, but otherwise the PLL continues to operate in a stable
136 * mode.
137 *
138 * MAXPHASE must be set greater than or equal to CLOCK.MAX (128 ms), as
139 * defined in the NTP specification. CLOCK.MAX establishes the maximum
140 * time offset allowed before the system time is reset, rather than
141 * incrementally adjusted. Here, the maximum offset is clamped to
142 * MAXPHASE only in order to prevent overflow errors due to defective
143 * protocol implementations.
144 *
145 * MAXFREQ is the maximum frequency tolerance of the CPU clock
146 * oscillator plus the maximum slew rate allowed by the protocol. It
147 * should be set to at least the frequency tolerance of the oscillator
148 * plus 100 ppm for vernier frequency adjustments. If the kernel
149 * PPS discipline code is configured (PPS_SYNC), the oscillator time and
150 * frequency are disciplined to an external source, presumably with
151 * negligible time and frequency error relative to UTC, and MAXFREQ can
152 * be reduced.
153 *
154 * MAXTIME is the maximum jitter tolerance of the PPS signal if the
155 * kernel PPS discipline code is configured (PPS_SYNC).
156 *
157 * MINSEC and MAXSEC define the lower and upper bounds on the interval
158 * between protocol updates.
159 */
160 #define MAXPHASE 512000L /* max phase error (us) */
161 #ifdef PPS_SYNC
162 #define MAXFREQ (512L << SHIFT_USEC) /* max freq error (100 ppm) */
163 #define MAXTIME (200L << PPS_AVG) /* max PPS error (jitter) (200 us) */
164 #else
165 #define MAXFREQ (512L << SHIFT_USEC) /* max freq error (200 ppm) */
166 #endif /* PPS_SYNC */
167 #define MINSEC 16L /* min interval between updates (s) */
168 #define MAXSEC 1200L /* max interval between updates (s) */
169
170 #ifdef PPS_SYNC
171 /*
172 * The following defines are used only if a pulse-per-second (PPS)
173 * signal is available and connected via a modem control lead, such as
174 * produced by the optional ppsclock feature incorporated in the Sun
175 * asynch driver. They establish the design parameters of the frequency-
176 * lock loop used to discipline the CPU clock oscillator to the PPS
177 * signal.
178 *
179 * PPS_AVG is the averaging factor for the frequency loop, as well as
180 * the time and frequency dispersion.
181 *
182 * PPS_SHIFT and PPS_SHIFTMAX specify the minimum and maximum
183 * calibration intervals, respectively, in seconds as a power of two.
184 *
185 * PPS_VALID is the maximum interval before the PPS signal is considered
186 * invalid and protocol updates used directly instead.
187 *
188 * MAXGLITCH is the maximum interval before a time offset of more than
189 * MAXTIME is believed.
190 */
191 #define PPS_AVG 2 /* pps averaging constant (shift) */
192 #define PPS_SHIFT 2 /* min interval duration (s) (shift) */
193 #define PPS_SHIFTMAX 8 /* max interval duration (s) (shift) */
194 #define PPS_VALID 120 /* pps signal watchdog max (s) */
195 #define MAXGLITCH 30 /* pps signal glitch max (s) */
196 #endif /* PPS_SYNC */
197
198 /*
199 * The following defines and structures define the user interface for
200 * the ntp_gettime() and ntp_adjtime() system calls.
201 *
202 * Control mode codes (timex.modes)
203 */
204 #define MOD_OFFSET 0x0001 /* set time offset */
205 #define MOD_FREQUENCY 0x0002 /* set frequency offset */
206 #define MOD_MAXERROR 0x0004 /* set maximum time error */
207 #define MOD_ESTERROR 0x0008 /* set estimated time error */
208 #define MOD_STATUS 0x0010 /* set clock status bits */
209 #define MOD_TIMECONST 0x0020 /* set pll time constant */
210 #define MOD_CLKB 0x4000 /* set clock B */
211 #define MOD_CLKA 0x8000 /* set clock A */
212
213 /*
214 * Status codes (timex.status)
215 */
216 #define STA_PLL 0x0001 /* enable PLL updates (rw) */
217 #define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */
218 #define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */
219 #define STA_FLL 0x0008 /* select frequency-lock mode (rw) */
220
221 #define STA_INS 0x0010 /* insert leap (rw) */
222 #define STA_DEL 0x0020 /* delete leap (rw) */
223 #define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */
224 #define STA_FREQHOLD 0x0080 /* hold frequency (rw) */
225
226 #define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */
227 #define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */
228 #define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */
229 #define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */
230
231 #define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */
232
233 #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
234 STA_PPSERROR | STA_CLOCKERR) /* read-only bits */
235
236 /*
237 * Clock states (time_state)
238 */
239 #define TIME_OK 0 /* no leap second warning */
240 #define TIME_INS 1 /* insert leap second warning */
241 #define TIME_DEL 2 /* delete leap second warning */
242 #define TIME_OOP 3 /* leap second in progress */
243 #define TIME_WAIT 4 /* leap second has occurred */
244 #define TIME_ERROR 5 /* clock not synchronized */
245
246 /*
247 * NTP user interface (ntp_gettime()) - used to read kernel clock values
248 *
249 * Note: maximum error = NTP synch distance = dispersion + delay / 2;
250 * estimated error = NTP dispersion.
251 */
252 struct ntptimeval {
253 struct timeval time; /* current time (ro) */
254 long maxerror; /* maximum error (us) (ro) */
255 long esterror; /* estimated error (us) (ro) */
256 };
257
258 /*
259 * NTP daemon interface - (ntp_adjtime()) used to discipline CPU clock
260 * oscillator
261 */
262 struct timex {
263 unsigned int modes; /* clock mode bits (wo) */
264 long offset; /* time offset (us) (rw) */
265 long freq; /* frequency offset (scaled ppm) (rw) */
266 long maxerror; /* maximum error (us) (rw) */
267 long esterror; /* estimated error (us) (rw) */
268 int status; /* clock status bits (rw) */
269 long constant; /* pll time constant (rw) */
270 long precision; /* clock precision (us) (ro) */
271 long tolerance; /* clock frequency tolerance (scaled
272 * ppm) (ro) */
273 /*
274 * The following read-only structure members are implemented
275 * only if the PPS signal discipline is configured in the
276 * kernel.
277 */
278 long ppsfreq; /* pps frequency (scaled ppm) (ro) */
279 long jitter; /* pps jitter (us) (ro) */
280 int shift; /* interval duration (s) (shift) (ro) */
281 long stabil; /* pps stability (scaled ppm) (ro) */
282 long jitcnt; /* jitter limit exceeded (ro) */
283 long calcnt; /* calibration intervals (ro) */
284 long errcnt; /* calibration errors (ro) */
285 long stbcnt; /* stability limit exceeded (ro) */
286
287 };
288
289 #if defined(__FreeBSD__) || defined(__NetBSD__)
290
291 #ifndef _KERNEL
292 #include <sys/cdefs.h>
293
294 __BEGIN_DECLS
295 int ntp_gettime __P((struct ntptimeval *));
296 int ntp_adjtime __P((struct timex *));
297 __END_DECLS
298
299 #endif /* not _KERNEL */
300
301 #endif /* __FreeBSD__ || __NetBSD__ */
302
303 #ifdef __NetBSD__
304 #ifdef _KERNEL
305 __BEGIN_DECLS
306 int ntp_settime1(struct timex *, register_t *);
307 int ntp_adjtime1(struct timex *, void *, register_t *);
308 __END_DECLS
309 #endif /* _KERNEL */
310 #endif /* __NetBSD__ */
311 #endif /* _SYS_TIMEX_H_ */
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