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) */ 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_MICRO 0x1000 /* select microsecond resolution */ 106 #define ADJ_NANO 0x2000 /* select nanosecond resolution */ 107 #define ADJ_TICK 0x4000 /* tick value */ 108 109 #ifdef __KERNEL__ 110 #define ADJ_ADJTIME 0x8000 /* switch between adjtime/adjtimex modes */ 111 #define ADJ_OFFSET_SINGLESHOT 0x0001 /* old-fashioned adjtime */ 112 #define ADJ_OFFSET_READONLY 0x2000 /* read-only adjtime */ 113 #else 114 #define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */ 115 #define ADJ_OFFSET_SS_READ 0xa001 /* read-only adjtime */ 116 #endif 117 118 /* xntp 3.4 compatibility names */ 119 #define MOD_OFFSET ADJ_OFFSET 120 #define MOD_FREQUENCY ADJ_FREQUENCY 121 #define MOD_MAXERROR ADJ_MAXERROR 122 #define MOD_ESTERROR ADJ_ESTERROR 123 #define MOD_STATUS ADJ_STATUS 124 #define MOD_TIMECONST ADJ_TIMECONST 125 126 127 /* 128 * Status codes (timex.status) 129 */ 130 #define STA_PLL 0x0001 /* enable PLL updates (rw) */ 131 #define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */ 132 #define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */ 133 #define STA_FLL 0x0008 /* select frequency-lock mode (rw) */ 134 135 #define STA_INS 0x0010 /* insert leap (rw) */ 136 #define STA_DEL 0x0020 /* delete leap (rw) */ 137 #define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */ 138 #define STA_FREQHOLD 0x0080 /* hold frequency (rw) */ 139 140 #define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */ 141 #define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */ 142 #define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */ 143 #define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */ 144 145 #define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */ 146 #define STA_NANO 0x2000 /* resolution (0 = us, 1 = ns) (ro) */ 147 #define STA_MODE 0x4000 /* mode (0 = PLL, 1 = FLL) (ro) */ 148 #define STA_CLK 0x8000 /* clock source (0 = A, 1 = B) (ro) */ 149 150 /* read-only bits */ 151 #define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \ 152 STA_PPSERROR | STA_CLOCKERR | STA_NANO | STA_MODE | STA_CLK) 153 154 /* 155 * Clock states (time_state) 156 */ 157 #define TIME_OK 0 /* clock synchronized, no leap second */ 158 #define TIME_INS 1 /* insert leap second */ 159 #define TIME_DEL 2 /* delete leap second */ 160 #define TIME_OOP 3 /* leap second in progress */ 161 #define TIME_WAIT 4 /* leap second has occurred */ 162 #define TIME_ERROR 5 /* clock not synchronized */ 163 #define TIME_BAD TIME_ERROR /* bw compat */ 164 165 #ifdef __KERNEL__ 166 #include <linux/compiler.h> 167 #include <linux/types.h> 168 #include <linux/param.h> 169 170 #include <asm/timex.h> 171 172 /* 173 * SHIFT_PLL is used as a dampening factor to define how much we 174 * adjust the frequency correction for a given offset in PLL mode. 175 * It also used in dampening the offset correction, to define how 176 * much of the current value in time_offset we correct for each 177 * second. Changing this value changes the stiffness of the ntp 178 * adjustment code. A lower value makes it more flexible, reducing 179 * NTP convergence time. A higher value makes it stiffer, increasing 180 * convergence time, but making the clock more stable. 181 * 182 * In David Mills' nanokernel reference implementation SHIFT_PLL is 4. 183 * However this seems to increase convergence time much too long. 184 * 185 * https://lists.ntp.org/pipermail/hackers/2008-January/003487.html 186 * 187 * In the above mailing list discussion, it seems the value of 4 188 * was appropriate for other Unix systems with HZ=100, and that 189 * SHIFT_PLL should be decreased as HZ increases. However, Linux's 190 * clock steering implementation is HZ independent. 191 * 192 * Through experimentation, a SHIFT_PLL value of 2 was found to allow 193 * for fast convergence (very similar to the NTPv3 code used prior to 194 * v2.6.19), with good clock stability. 195 * 196 * 197 * SHIFT_FLL is used as a dampening factor to define how much we 198 * adjust the frequency correction for a given offset in FLL mode. 199 * In David Mills' nanokernel reference implementation SHIFT_FLL is 2. 200 * 201 * MAXTC establishes the maximum time constant of the PLL. 202 */ 203 #define SHIFT_PLL 2 /* PLL frequency factor (shift) */ 204 #define SHIFT_FLL 2 /* FLL frequency factor (shift) */ 205 #define MAXTC 10 /* maximum time constant (shift) */ 206 207 /* 208 * SHIFT_USEC defines the scaling (shift) of the time_freq and 209 * time_tolerance variables, which represent the current frequency 210 * offset and maximum frequency tolerance. 211 */ 212 #define SHIFT_USEC 16 /* frequency offset scale (shift) */ 213 #define PPM_SCALE ((s64)NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC)) 214 #define PPM_SCALE_INV_SHIFT 19 215 #define PPM_SCALE_INV ((1LL << (PPM_SCALE_INV_SHIFT + NTP_SCALE_SHIFT)) / \ 216 PPM_SCALE + 1) 217 218 #define MAXPHASE 500000000L /* max phase error (ns) */ 219 #define MAXFREQ 500000 /* max frequency error (ns/s) */ 220 #define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SCALE_SHIFT) 221 #define MINSEC 256 /* min interval between updates (s) */ 222 #define MAXSEC 2048 /* max interval between updates (s) */ 223 #define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */ 224 225 /* 226 * kernel variables 227 * Note: maximum error = NTP synch distance = dispersion + delay / 2; 228 * estimated error = NTP dispersion. 229 */ 230 extern unsigned long tick_usec; /* USER_HZ period (usec) */ 231 extern unsigned long tick_nsec; /* ACTHZ period (nsec) */ 232 extern int tickadj; /* amount of adjustment per tick */ 233 234 /* 235 * phase-lock loop variables 236 */ 237 extern int time_status; /* clock synchronization status bits */ 238 extern long time_maxerror; /* maximum error */ 239 extern long time_esterror; /* estimated error */ 240 241 extern long time_adjust; /* The amount of adjtime left */ 242 243 extern void ntp_init(void); 244 extern void ntp_clear(void); 245 246 /** 247 * ntp_synced - Returns 1 if the NTP status is not UNSYNC 248 * 249 */ 250 static inline int ntp_synced(void) 251 { 252 return !(time_status & STA_UNSYNC); 253 } 254 255 /* Required to safely shift negative values */ 256 #define shift_right(x, s) ({ \ 257 __typeof__(x) __x = (x); \ 258 __typeof__(s) __s = (s); \ 259 __x < 0 ? -(-__x >> __s) : __x >> __s; \ 260 }) 261 262 #define NTP_SCALE_SHIFT 32 263 264 #define NTP_INTERVAL_FREQ (HZ) 265 #define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ) 266 267 /* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */ 268 extern u64 tick_length; 269 270 extern void second_overflow(void); 271 extern void update_ntp_one_tick(void); 272 extern int do_adjtimex(struct timex *); 273 274 /* Don't use! Compatibility define for existing users. */ 275 #define tickadj (500/HZ ? : 1) 276 277 int read_current_timer(unsigned long *timer_val); 278 279 /* The clock frequency of the i8253/i8254 PIT */ 280 #define PIT_TICK_RATE 1193182ul 281 282 #endif /* KERNEL */ 283 284 #endif /* LINUX_TIMEX_H */ 285