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Diffstat (limited to 'include/linux/timex.h')
| -rw-r--r-- | include/linux/timex.h | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/include/linux/timex.h b/include/linux/timex.h new file mode 100644 index 00000000..99bc88b1 --- /dev/null +++ b/include/linux/timex.h @@ -0,0 +1,266 @@ +/***************************************************************************** + * * + * Copyright (c) David L. Mills 1993 * + * * + * Permission to use, copy, modify, and distribute this software and its * + * documentation for any purpose and without fee is hereby granted, provided * + * that the above copyright notice appears in all copies and that both the * + * copyright notice and this permission notice appear in supporting * + * documentation, and that the name University of Delaware not be used in * + * advertising or publicity pertaining to distribution of the software * + * without specific, written prior permission. The University of Delaware * + * makes no representations about the suitability this software for any * + * purpose. It is provided "as is" without express or implied warranty. * + * * + *****************************************************************************/ + +/* + * Modification history timex.h + * + * 29 Dec 97 Russell King + * Moved CLOCK_TICK_RATE, CLOCK_TICK_FACTOR and FINETUNE to asm/timex.h + * for ARM machines + * + * 9 Jan 97 Adrian Sun + * Shifted LATCH define to allow access to alpha machines. + * + * 26 Sep 94 David L. Mills + * Added defines for hybrid phase/frequency-lock loop. + * + * 19 Mar 94 David L. Mills + * Moved defines from kernel routines to header file and added new + * defines for PPS phase-lock loop. + * + * 20 Feb 94 David L. Mills + * Revised status codes and structures for external clock and PPS + * signal discipline. + * + * 28 Nov 93 David L. Mills + * Adjusted parameters to improve stability and increase poll + * interval. + * + * 17 Sep 93 David L. Mills + * Created file $NTP/include/sys/timex.h + * 07 Oct 93 Torsten Duwe + * Derived linux/timex.h + * 1995-08-13 Torsten Duwe + * kernel PLL updated to 1994-12-13 specs (rfc-1589) + * 1997-08-30 Ulrich Windl + * Added new constant NTP_PHASE_LIMIT + * 2004-08-12 Christoph Lameter + * Reworked time interpolation logic + */ +#ifndef _LINUX_TIMEX_H +#define _LINUX_TIMEX_H + +#include <linux/time.h> + +#define NTP_API 4 /* NTP API version */ + +/* + * syscall interface - used (mainly by NTP daemon) + * to discipline kernel clock oscillator + */ +struct timex { + unsigned int modes; /* mode selector */ + long offset; /* time offset (usec) */ + long freq; /* frequency offset (scaled ppm) */ + long maxerror; /* maximum error (usec) */ + long esterror; /* estimated error (usec) */ + int status; /* clock command/status */ + long constant; /* pll time constant */ + long precision; /* clock precision (usec) (read only) */ + long tolerance; /* clock frequency tolerance (ppm) + * (read only) + */ + struct timeval time; /* (read only, except for ADJ_SETOFFSET) */ + long tick; /* (modified) usecs between clock ticks */ + + long ppsfreq; /* pps frequency (scaled ppm) (ro) */ + long jitter; /* pps jitter (us) (ro) */ + int shift; /* interval duration (s) (shift) (ro) */ + long stabil; /* pps stability (scaled ppm) (ro) */ + long jitcnt; /* jitter limit exceeded (ro) */ + long calcnt; /* calibration intervals (ro) */ + long errcnt; /* calibration errors (ro) */ + long stbcnt; /* stability limit exceeded (ro) */ + + int tai; /* TAI offset (ro) */ + + int :32; int :32; int :32; int :32; + int :32; int :32; int :32; int :32; + int :32; int :32; int :32; +}; + +/* + * Mode codes (timex.mode) + */ +#define ADJ_OFFSET 0x0001 /* time offset */ +#define ADJ_FREQUENCY 0x0002 /* frequency offset */ +#define ADJ_MAXERROR 0x0004 /* maximum time error */ +#define ADJ_ESTERROR 0x0008 /* estimated time error */ +#define ADJ_STATUS 0x0010 /* clock status */ +#define ADJ_TIMECONST 0x0020 /* pll time constant */ +#define ADJ_TAI 0x0080 /* set TAI offset */ +#define ADJ_SETOFFSET 0x0100 /* add 'time' to current time */ +#define ADJ_MICRO 0x1000 /* select microsecond resolution */ +#define ADJ_NANO 0x2000 /* select nanosecond resolution */ +#define ADJ_TICK 0x4000 /* tick value */ + +#ifdef __KERNEL__ +#define ADJ_ADJTIME 0x8000 /* switch between adjtime/adjtimex modes */ +#define ADJ_OFFSET_SINGLESHOT 0x0001 /* old-fashioned adjtime */ +#define ADJ_OFFSET_READONLY 0x2000 /* read-only adjtime */ +#else +#define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */ +#define ADJ_OFFSET_SS_READ 0xa001 /* read-only adjtime */ +#endif + +/* NTP userland likes the MOD_ prefix better */ +#define MOD_OFFSET ADJ_OFFSET +#define MOD_FREQUENCY ADJ_FREQUENCY +#define MOD_MAXERROR ADJ_MAXERROR +#define MOD_ESTERROR ADJ_ESTERROR +#define MOD_STATUS ADJ_STATUS +#define MOD_TIMECONST ADJ_TIMECONST +#define MOD_TAI ADJ_TAI +#define MOD_MICRO ADJ_MICRO +#define MOD_NANO ADJ_NANO + + +/* + * Status codes (timex.status) + */ +#define STA_PLL 0x0001 /* enable PLL updates (rw) */ +#define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */ +#define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */ +#define STA_FLL 0x0008 /* select frequency-lock mode (rw) */ + +#define STA_INS 0x0010 /* insert leap (rw) */ +#define STA_DEL 0x0020 /* delete leap (rw) */ +#define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */ +#define STA_FREQHOLD 0x0080 /* hold frequency (rw) */ + +#define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */ +#define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */ +#define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */ +#define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */ + +#define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */ +#define STA_NANO 0x2000 /* resolution (0 = us, 1 = ns) (ro) */ +#define STA_MODE 0x4000 /* mode (0 = PLL, 1 = FLL) (ro) */ +#define STA_CLK 0x8000 /* clock source (0 = A, 1 = B) (ro) */ + +/* read-only bits */ +#define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \ + STA_PPSERROR | STA_CLOCKERR | STA_NANO | STA_MODE | STA_CLK) + +/* + * Clock states (time_state) + */ +#define TIME_OK 0 /* clock synchronized, no leap second */ +#define TIME_INS 1 /* insert leap second */ +#define TIME_DEL 2 /* delete leap second */ +#define TIME_OOP 3 /* leap second in progress */ +#define TIME_WAIT 4 /* leap second has occurred */ +#define TIME_ERROR 5 /* clock not synchronized */ +#define TIME_BAD TIME_ERROR /* bw compat */ + +#ifdef __KERNEL__ +#include <linux/compiler.h> +#include <linux/types.h> +#include <linux/param.h> + +#include <asm/timex.h> + +/* + * SHIFT_PLL is used as a dampening factor to define how much we + * adjust the frequency correction for a given offset in PLL mode. + * It also used in dampening the offset correction, to define how + * much of the current value in time_offset we correct for each + * second. Changing this value changes the stiffness of the ntp + * adjustment code. A lower value makes it more flexible, reducing + * NTP convergence time. A higher value makes it stiffer, increasing + * convergence time, but making the clock more stable. + * + * In David Mills' nanokernel reference implementation SHIFT_PLL is 4. + * However this seems to increase convergence time much too long. + * + * https://lists.ntp.org/pipermail/hackers/2008-January/003487.html + * + * In the above mailing list discussion, it seems the value of 4 + * was appropriate for other Unix systems with HZ=100, and that + * SHIFT_PLL should be decreased as HZ increases. However, Linux's + * clock steering implementation is HZ independent. + * + * Through experimentation, a SHIFT_PLL value of 2 was found to allow + * for fast convergence (very similar to the NTPv3 code used prior to + * v2.6.19), with good clock stability. + * + * + * SHIFT_FLL is used as a dampening factor to define how much we + * adjust the frequency correction for a given offset in FLL mode. + * In David Mills' nanokernel reference implementation SHIFT_FLL is 2. + * + * MAXTC establishes the maximum time constant of the PLL. + */ +#define SHIFT_PLL 2 /* PLL frequency factor (shift) */ +#define SHIFT_FLL 2 /* FLL frequency factor (shift) */ +#define MAXTC 10 /* maximum time constant (shift) */ + +/* + * SHIFT_USEC defines the scaling (shift) of the time_freq and + * time_tolerance variables, which represent the current frequency + * offset and maximum frequency tolerance. + */ +#define SHIFT_USEC 16 /* frequency offset scale (shift) */ +#define PPM_SCALE ((s64)NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC)) +#define PPM_SCALE_INV_SHIFT 19 +#define PPM_SCALE_INV ((1LL << (PPM_SCALE_INV_SHIFT + NTP_SCALE_SHIFT)) / \ + PPM_SCALE + 1) + +#define MAXPHASE 500000000L /* max phase error (ns) */ +#define MAXFREQ 500000 /* max frequency error (ns/s) */ +#define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SCALE_SHIFT) +#define MINSEC 256 /* min interval between updates (s) */ +#define MAXSEC 2048 /* max interval between updates (s) */ +#define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */ + +/* + * kernel variables + * Note: maximum error = NTP synch distance = dispersion + delay / 2; + * estimated error = NTP dispersion. + */ +extern unsigned long tick_usec; /* USER_HZ period (usec) */ +extern unsigned long tick_nsec; /* ACTHZ period (nsec) */ + +extern void ntp_init(void); +extern void ntp_clear(void); + +/* Required to safely shift negative values */ +#define shift_right(x, s) ({ \ + __typeof__(x) __x = (x); \ + __typeof__(s) __s = (s); \ + __x < 0 ? -(-__x >> __s) : __x >> __s; \ +}) + +#define NTP_SCALE_SHIFT 32 + +#define NTP_INTERVAL_FREQ (HZ) +#define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ) + +/* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */ +extern u64 ntp_tick_length(void); + +extern int second_overflow(unsigned long secs); +extern int do_adjtimex(struct timex *); +extern void hardpps(const struct timespec *, const struct timespec *); + +int read_current_timer(unsigned long *timer_val); + +/* The clock frequency of the i8253/i8254 PIT */ +#define PIT_TICK_RATE 1193182ul + +#endif /* KERNEL */ + +#endif /* LINUX_TIMEX_H */ |