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1 | /***************************************************************************** |
2 | * * |
3 | * Copyright (c) David L. Mills 1993 * |
4 | * * |
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. * |
14 | * * |
15 | *****************************************************************************/ |
16 | |
17 | /* |
18 | * Modification history timex.h |
19 | * |
20 | * 29 Dec 97 Russell King |
21 | * Moved CLOCK_TICK_RATE, CLOCK_TICK_FACTOR and FINETUNE to asm/timex.h |
22 | * for ARM machines |
23 | * |
24 | * 9 Jan 97 Adrian Sun |
25 | * Shifted LATCH define to allow access to alpha machines. |
26 | * |
27 | * 26 Sep 94 David L. Mills |
28 | * Added defines for hybrid phase/frequency-lock loop. |
29 | * |
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. |
33 | * |
34 | * 20 Feb 94 David L. Mills |
35 | * Revised status codes and structures for external clock and PPS |
36 | * signal discipline. |
37 | * |
38 | * 28 Nov 93 David L. Mills |
39 | * Adjusted parameters to improve stability and increase poll |
40 | * interval. |
41 | * |
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 |
50 | * 2004-08-12 Christoph Lameter |
51 | * Reworked time interpolation logic |
52 | */ |
53 | #ifndef _LINUX_TIMEX_H |
54 | #define _LINUX_TIMEX_H |
55 | |
56 | #include <linux/time.h> |
57 | |
58 | #define NTP_API 4 /* NTP API version */ |
59 | |
60 | /* |
61 | * syscall interface - used (mainly by NTP daemon) |
62 | * to discipline kernel clock oscillator |
63 | */ |
64 | struct timex { |
65 | unsigned int modes; /* mode selector */ |
66 | long offset; /* time offset (usec) */ |
67 | long freq; /* frequency offset (scaled ppm) */ |
68 | long maxerror; /* maximum error (usec) */ |
69 | long esterror; /* estimated error (usec) */ |
70 | int status; /* clock command/status */ |
71 | long constant; /* pll time constant */ |
72 | long precision; /* clock precision (usec) (read only) */ |
73 | long tolerance; /* clock frequency tolerance (ppm) |
74 | * (read only) |
75 | */ |
76 | struct timeval time; /* (read only, except for ADJ_SETOFFSET) */ |
77 | long tick; /* (modified) usecs between clock ticks */ |
78 | |
79 | long ppsfreq; /* pps frequency (scaled ppm) (ro) */ |
80 | long jitter; /* pps jitter (us) (ro) */ |
81 | int shift; /* interval duration (s) (shift) (ro) */ |
82 | long stabil; /* pps stability (scaled ppm) (ro) */ |
83 | long jitcnt; /* jitter limit exceeded (ro) */ |
84 | long calcnt; /* calibration intervals (ro) */ |
85 | long errcnt; /* calibration errors (ro) */ |
86 | long stbcnt; /* stability limit exceeded (ro) */ |
87 | |
88 | int tai; /* TAI offset (ro) */ |
89 | |
90 | int :32; int :32; int :32; int :32; |
91 | int :32; int :32; int :32; int :32; |
92 | int :32; int :32; int :32; |
93 | }; |
94 | |
95 | /* |
96 | * Mode codes (timex.mode) |
97 | */ |
98 | #define ADJ_OFFSET 0x0001 /* time offset */ |
99 | #define ADJ_FREQUENCY 0x0002 /* frequency offset */ |
100 | #define ADJ_MAXERROR 0x0004 /* maximum time error */ |
101 | #define ADJ_ESTERROR 0x0008 /* estimated time error */ |
102 | #define ADJ_STATUS 0x0010 /* clock status */ |
103 | #define ADJ_TIMECONST 0x0020 /* pll time constant */ |
104 | #define ADJ_TAI 0x0080 /* set TAI offset */ |
105 | #define ADJ_SETOFFSET 0x0100 /* add 'time' to current time */ |
106 | #define ADJ_MICRO 0x1000 /* select microsecond resolution */ |
107 | #define ADJ_NANO 0x2000 /* select nanosecond resolution */ |
108 | #define ADJ_TICK 0x4000 /* tick value */ |
109 | |
110 | #ifdef __KERNEL__ |
111 | #define ADJ_ADJTIME 0x8000 /* switch between adjtime/adjtimex modes */ |
112 | #define ADJ_OFFSET_SINGLESHOT 0x0001 /* old-fashioned adjtime */ |
113 | #define ADJ_OFFSET_READONLY 0x2000 /* read-only adjtime */ |
114 | #else |
115 | #define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */ |
116 | #define ADJ_OFFSET_SS_READ 0xa001 /* read-only adjtime */ |
117 | #endif |
118 | |
119 | /* NTP userland likes the MOD_ prefix better */ |
120 | #define MOD_OFFSET ADJ_OFFSET |
121 | #define MOD_FREQUENCY ADJ_FREQUENCY |
122 | #define MOD_MAXERROR ADJ_MAXERROR |
123 | #define MOD_ESTERROR ADJ_ESTERROR |
124 | #define MOD_STATUS ADJ_STATUS |
125 | #define MOD_TIMECONST ADJ_TIMECONST |
126 | #define MOD_TAI ADJ_TAI |
127 | #define MOD_MICRO ADJ_MICRO |
128 | #define MOD_NANO ADJ_NANO |
129 | |
130 | |
131 | /* |
132 | * Status codes (timex.status) |
133 | */ |
134 | #define STA_PLL 0x0001 /* enable PLL updates (rw) */ |
135 | #define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */ |
136 | #define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */ |
137 | #define STA_FLL 0x0008 /* select frequency-lock mode (rw) */ |
138 | |
139 | #define STA_INS 0x0010 /* insert leap (rw) */ |
140 | #define STA_DEL 0x0020 /* delete leap (rw) */ |
141 | #define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */ |
142 | #define STA_FREQHOLD 0x0080 /* hold frequency (rw) */ |
143 | |
144 | #define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */ |
145 | #define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */ |
146 | #define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */ |
147 | #define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */ |
148 | |
149 | #define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */ |
150 | #define STA_NANO 0x2000 /* resolution (0 = us, 1 = ns) (ro) */ |
151 | #define STA_MODE 0x4000 /* mode (0 = PLL, 1 = FLL) (ro) */ |
152 | #define STA_CLK 0x8000 /* clock source (0 = A, 1 = B) (ro) */ |
153 | |
154 | /* read-only bits */ |
155 | #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \ |
156 | STA_PPSERROR | STA_CLOCKERR | STA_NANO | STA_MODE | STA_CLK) |
157 | |
158 | /* |
159 | * Clock states (time_state) |
160 | */ |
161 | #define TIME_OK 0 /* clock synchronized, no leap second */ |
162 | #define TIME_INS 1 /* insert leap second */ |
163 | #define TIME_DEL 2 /* delete leap second */ |
164 | #define TIME_OOP 3 /* leap second in progress */ |
165 | #define TIME_WAIT 4 /* leap second has occurred */ |
166 | #define TIME_ERROR 5 /* clock not synchronized */ |
167 | #define TIME_BAD TIME_ERROR /* bw compat */ |
168 | |
169 | #ifdef __KERNEL__ |
170 | #include <linux/compiler.h> |
171 | #include <linux/types.h> |
172 | #include <linux/param.h> |
173 | |
174 | #include <asm/timex.h> |
175 | |
176 | /* |
177 | * SHIFT_PLL is used as a dampening factor to define how much we |
178 | * adjust the frequency correction for a given offset in PLL mode. |
179 | * It also used in dampening the offset correction, to define how |
180 | * much of the current value in time_offset we correct for each |
181 | * second. Changing this value changes the stiffness of the ntp |
182 | * adjustment code. A lower value makes it more flexible, reducing |
183 | * NTP convergence time. A higher value makes it stiffer, increasing |
184 | * convergence time, but making the clock more stable. |
185 | * |
186 | * In David Mills' nanokernel reference implementation SHIFT_PLL is 4. |
187 | * However this seems to increase convergence time much too long. |
188 | * |
189 | * https://lists.ntp.org/pipermail/hackers/2008-January/003487.html |
190 | * |
191 | * In the above mailing list discussion, it seems the value of 4 |
192 | * was appropriate for other Unix systems with HZ=100, and that |
193 | * SHIFT_PLL should be decreased as HZ increases. However, Linux's |
194 | * clock steering implementation is HZ independent. |
195 | * |
196 | * Through experimentation, a SHIFT_PLL value of 2 was found to allow |
197 | * for fast convergence (very similar to the NTPv3 code used prior to |
198 | * v2.6.19), with good clock stability. |
199 | * |
200 | * |
201 | * SHIFT_FLL is used as a dampening factor to define how much we |
202 | * adjust the frequency correction for a given offset in FLL mode. |
203 | * In David Mills' nanokernel reference implementation SHIFT_FLL is 2. |
204 | * |
205 | * MAXTC establishes the maximum time constant of the PLL. |
206 | */ |
207 | #define SHIFT_PLL 2 /* PLL frequency factor (shift) */ |
208 | #define SHIFT_FLL 2 /* FLL frequency factor (shift) */ |
209 | #define MAXTC 10 /* maximum time constant (shift) */ |
210 | |
211 | /* |
212 | * SHIFT_USEC defines the scaling (shift) of the time_freq and |
213 | * time_tolerance variables, which represent the current frequency |
214 | * offset and maximum frequency tolerance. |
215 | */ |
216 | #define SHIFT_USEC 16 /* frequency offset scale (shift) */ |
217 | #define PPM_SCALE ((s64)NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC)) |
218 | #define PPM_SCALE_INV_SHIFT 19 |
219 | #define PPM_SCALE_INV ((1LL << (PPM_SCALE_INV_SHIFT + NTP_SCALE_SHIFT)) / \ |
220 | PPM_SCALE + 1) |
221 | |
222 | #define MAXPHASE 500000000L /* max phase error (ns) */ |
223 | #define MAXFREQ 500000 /* max frequency error (ns/s) */ |
224 | #define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SCALE_SHIFT) |
225 | #define MINSEC 256 /* min interval between updates (s) */ |
226 | #define MAXSEC 2048 /* max interval between updates (s) */ |
227 | #define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */ |
228 | |
229 | /* |
230 | * kernel variables |
231 | * Note: maximum error = NTP synch distance = dispersion + delay / 2; |
232 | * estimated error = NTP dispersion. |
233 | */ |
234 | extern unsigned long tick_usec; /* USER_HZ period (usec) */ |
235 | extern unsigned long tick_nsec; /* ACTHZ period (nsec) */ |
236 | |
237 | /* |
238 | * phase-lock loop variables |
239 | */ |
240 | extern int time_status; /* clock synchronization status bits */ |
241 | |
242 | extern void ntp_init(void); |
243 | extern void ntp_clear(void); |
244 | |
245 | /** |
246 | * ntp_synced - Returns 1 if the NTP status is not UNSYNC |
247 | * |
248 | */ |
249 | static inline int ntp_synced(void) |
250 | { |
251 | return !(time_status & STA_UNSYNC); |
252 | } |
253 | |
254 | /* Required to safely shift negative values */ |
255 | #define shift_right(x, s) ({ \ |
256 | __typeof__(x) __x = (x); \ |
257 | __typeof__(s) __s = (s); \ |
258 | __x < 0 ? -(-__x >> __s) : __x >> __s; \ |
259 | }) |
260 | |
261 | #define NTP_SCALE_SHIFT 32 |
262 | |
263 | #define NTP_INTERVAL_FREQ (HZ) |
264 | #define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ) |
265 | |
266 | /* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */ |
267 | extern u64 tick_length; |
268 | |
269 | extern void second_overflow(void); |
270 | extern void update_ntp_one_tick(void); |
271 | extern int do_adjtimex(struct timex *); |
272 | extern void hardpps(const struct timespec *, const struct timespec *); |
273 | |
274 | int read_current_timer(unsigned long *timer_val); |
275 | |
276 | /* The clock frequency of the i8253/i8254 PIT */ |
277 | #define PIT_TICK_RATE 1193182ul |
278 | |
279 | #endif /* KERNEL */ |
280 | |
281 | #endif /* LINUX_TIMEX_H */ |
282 |
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