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 */ 64struct 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/* NTP userland likes the MOD_ prefix better */ 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#define MOD_TAI ADJ_TAI 126#define MOD_MICRO ADJ_MICRO 127#define MOD_NANO ADJ_NANO 128 129 130/* 131 * Status codes (timex.status) 132 */ 133#define STA_PLL 0x0001 /* enable PLL updates (rw) */ 134#define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */ 135#define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */ 136#define STA_FLL 0x0008 /* select frequency-lock mode (rw) */ 137 138#define STA_INS 0x0010 /* insert leap (rw) */ 139#define STA_DEL 0x0020 /* delete leap (rw) */ 140#define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */ 141#define STA_FREQHOLD 0x0080 /* hold frequency (rw) */ 142 143#define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */ 144#define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */ 145#define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */ 146#define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */ 147 148#define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */ 149#define STA_NANO 0x2000 /* resolution (0 = us, 1 = ns) (ro) */ 150#define STA_MODE 0x4000 /* mode (0 = PLL, 1 = FLL) (ro) */ 151#define STA_CLK 0x8000 /* clock source (0 = A, 1 = B) (ro) */ 152 153/* read-only bits */ 154#define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \ 155 STA_PPSERROR | STA_CLOCKERR | STA_NANO | STA_MODE | STA_CLK) 156 157/* 158 * Clock states (time_state) 159 */ 160#define TIME_OK 0 /* clock synchronized, no leap second */ 161#define TIME_INS 1 /* insert leap second */ 162#define TIME_DEL 2 /* delete leap second */ 163#define TIME_OOP 3 /* leap second in progress */ 164#define TIME_WAIT 4 /* leap second has occurred */ 165#define TIME_ERROR 5 /* clock not synchronized */ 166#define TIME_BAD TIME_ERROR /* bw compat */ 167 168#ifdef __KERNEL__ 169#include <linux/compiler.h> 170#include <linux/types.h> 171#include <linux/param.h> 172 173#include <asm/timex.h> 174 175/* 176 * SHIFT_PLL is used as a dampening factor to define how much we 177 * adjust the frequency correction for a given offset in PLL mode. 178 * It also used in dampening the offset correction, to define how 179 * much of the current value in time_offset we correct for each 180 * second. Changing this value changes the stiffness of the ntp 181 * adjustment code. A lower value makes it more flexible, reducing 182 * NTP convergence time. A higher value makes it stiffer, increasing 183 * convergence time, but making the clock more stable. 184 * 185 * In David Mills' nanokernel reference implementation SHIFT_PLL is 4. 186 * However this seems to increase convergence time much too long. 187 * 188 * https://lists.ntp.org/pipermail/hackers/2008-January/003487.html 189 * 190 * In the above mailing list discussion, it seems the value of 4 191 * was appropriate for other Unix systems with HZ=100, and that 192 * SHIFT_PLL should be decreased as HZ increases. However, Linux's 193 * clock steering implementation is HZ independent. 194 * 195 * Through experimentation, a SHIFT_PLL value of 2 was found to allow 196 * for fast convergence (very similar to the NTPv3 code used prior to 197 * v2.6.19), with good clock stability. 198 * 199 * 200 * SHIFT_FLL is used as a dampening factor to define how much we 201 * adjust the frequency correction for a given offset in FLL mode. 202 * In David Mills' nanokernel reference implementation SHIFT_FLL is 2. 203 * 204 * MAXTC establishes the maximum time constant of the PLL. 205 */ 206#define SHIFT_PLL 2 /* PLL frequency factor (shift) */ 207#define SHIFT_FLL 2 /* FLL frequency factor (shift) */ 208#define MAXTC 10 /* maximum time constant (shift) */ 209 210/* 211 * SHIFT_USEC defines the scaling (shift) of the time_freq and 212 * time_tolerance variables, which represent the current frequency 213 * offset and maximum frequency tolerance. 214 */ 215#define SHIFT_USEC 16 /* frequency offset scale (shift) */ 216#define PPM_SCALE ((s64)NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC)) 217#define PPM_SCALE_INV_SHIFT 19 218#define PPM_SCALE_INV ((1LL << (PPM_SCALE_INV_SHIFT + NTP_SCALE_SHIFT)) / \ 219 PPM_SCALE + 1) 220 221#define MAXPHASE 500000000L /* max phase error (ns) */ 222#define MAXFREQ 500000 /* max frequency error (ns/s) */ 223#define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SCALE_SHIFT) 224#define MINSEC 256 /* min interval between updates (s) */ 225#define MAXSEC 2048 /* max interval between updates (s) */ 226#define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */ 227 228/* 229 * kernel variables 230 * Note: maximum error = NTP synch distance = dispersion + delay / 2; 231 * estimated error = NTP dispersion. 232 */ 233extern unsigned long tick_usec; /* USER_HZ period (usec) */ 234extern unsigned long tick_nsec; /* ACTHZ period (nsec) */ 235 236/* 237 * phase-lock loop variables 238 */ 239extern int time_status; /* clock synchronization status bits */ 240 241extern void ntp_init(void); 242extern void ntp_clear(void); 243 244/** 245 * ntp_synced - Returns 1 if the NTP status is not UNSYNC 246 * 247 */ 248static inline int ntp_synced(void) 249{ 250 return !(time_status & STA_UNSYNC); 251} 252 253/* Required to safely shift negative values */ 254#define shift_right(x, s) ({ \ 255 __typeof__(x) __x = (x); \ 256 __typeof__(s) __s = (s); \ 257 __x < 0 ? -(-__x >> __s) : __x >> __s; \ 258}) 259 260#define NTP_SCALE_SHIFT 32 261 262#define NTP_INTERVAL_FREQ (HZ) 263#define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ) 264 265/* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */ 266extern u64 tick_length; 267 268extern void second_overflow(void); 269extern void update_ntp_one_tick(void); 270extern int do_adjtimex(struct timex *); 271 272int read_current_timer(unsigned long *timer_val); 273 274/* The clock frequency of the i8253/i8254 PIT */ 275#define PIT_TICK_RATE 1193182ul 276 277#endif /* KERNEL */ 278 279#endif /* LINUX_TIMEX_H */ 280