linux-sg2042/include/linux/timex.h

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/*****************************************************************************
* *
* 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/compiler.h>
#include <linux/time.h>
#include <asm/param.h>
#define NTP_API 4 /* NTP API version */
/*
* SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
* for a slightly underdamped convergence characteristic. SHIFT_KH
* establishes the damping of the FLL and is chosen by wisdom and black
* art.
*
* MAXTC establishes the maximum time constant of the PLL. With the
* SHIFT_KG and SHIFT_KF values given and a time constant range from
* zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
* respectively.
*/
#define SHIFT_PLL 4 /* 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 (NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC))
#define PPM_SCALE_INV_SHIFT 20
#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 */
/*
* 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) */
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_MICRO 0x1000 /* select microsecond resolution */
#define ADJ_NANO 0x2000 /* select nanosecond resolution */
#define ADJ_TICK 0x4000 /* tick value */
#define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */
#define ADJ_OFFSET_SS_READ 0xa001 /* read-only adjtime */
/* xntp 3.4 compatibility names */
#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
/*
* 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 <asm/timex.h>
/*
* 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 int tickadj; /* amount of adjustment per tick */
/*
* phase-lock loop variables
*/
extern int time_status; /* clock synchronization status bits */
extern long time_maxerror; /* maximum error */
extern long time_esterror; /* estimated error */
extern long time_adjust; /* The amount of adjtime left */
extern void ntp_init(void);
extern void ntp_clear(void);
/**
* ntp_synced - Returns 1 if the NTP status is not UNSYNC
*
*/
static inline int ntp_synced(void)
{
return !(time_status & STA_UNSYNC);
}
/* 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
#ifdef CONFIG_NO_HZ
#define NTP_INTERVAL_FREQ (2)
#else
#define NTP_INTERVAL_FREQ (HZ)
#endif
time: remove obsolete CLOCK_TICK_ADJUST The first version of the ntp_interval/tick_length inconsistent usage patch was recently merged as bbe4d18ac2e058c56adb0cd71f49d9ed3216a405 http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bbe4d18ac2e058c56adb0cd71f49d9ed3216a405 While the fix did greatly improve the situation, it was correctly pointed out by Roman that it does have a small bug: If the users change clocksources after the system has been running and NTP has made corrections, the correctoins made against the old clocksource will be applied against the new clocksource, causing error. The second attempt, which corrects the issue in the NTP_INTERVAL_LENGTH definition has also made it up-stream as commit e13a2e61dd5152f5499d2003470acf9c838eab84 http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e13a2e61dd5152f5499d2003470acf9c838eab84 Roman has correctly pointed out that CLOCK_TICK_ADJUST is calculated based on the PIT's frequency, and isn't really relevant to non-PIT driven clocksources (that is, clocksources other then jiffies and pit). This patch reverts both of those changes, and simply removes CLOCK_TICK_ADJUST. This does remove the granularity error correction for users of PIT and Jiffies clocksource users, but the granularity error but for the majority of users, it should be within the 500ppm range NTP can accommodate for. For systems that have granularity errors greater then 500ppm, the "ntp_tick_adj=" boot option can be used to compensate. [johnstul@us.ibm.com: provided changelog] [mattilinnanvuori@yahoo.com: maek ntp_tick_adj static] Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Acked-by: john stultz <johnstul@us.ibm.com> Signed-off-by: Matti Linnanvuori <mattilinnanvuori@yahoo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: mingo@elte.hu Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-03-05 07:14:26 +08:00
#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 tick_length;
[PATCH] Provide an interface for getting the current tick length This provides an interface for arch code to find out how many nanoseconds are going to be added on to xtime by the next call to do_timer. The value returned is a fixed-point number in 52.12 format in nanoseconds. The reason for this format is that it gives the full precision that the timekeeping code is using internally. The motivation for this is to fix a problem that has arisen on 32-bit powerpc in that the value returned by do_gettimeofday drifts apart from xtime if NTP is being used. PowerPC is now using a lockless do_gettimeofday based on reading the timebase register and performing some simple arithmetic. (This method of getting the time is also exported to userspace via the VDSO.) However, the factor and offset it uses were calculated based on the nominal tick length and weren't being adjusted when NTP varied the tick length. Note that 64-bit powerpc has had the lockless do_gettimeofday for a long time now. It also had an extremely hairy routine that got called from the 32-bit compat routine for adjtimex, which adjusted the factor and offset according to what it thought the timekeeping code was going to do. Not only was this only called if a 32-bit task did adjtimex (i.e. not if a 64-bit task did adjtimex), it was also duplicating computations from kernel/timer.c and it wasn't clear that it was (still) correct. The simple solution is to ask the timekeeping code how long the current jiffy will be on each timer interrupt, after calling do_timer. If this jiffy will be a different length from the last one, we then need to compute new values for the factor and offset used in the lockless do_gettimeofday. In this way we can keep xtime and do_gettimeofday in sync, even when NTP is varying the tick length. Note that when adjtimex varies the tick length, it almost always introduces the variation from the next tick on. The only case I could see where adjtimex would vary the length of the current tick is when an old-style adjtime adjustment is being cancelled. (It's not clear to me why the adjustment has to be cancelled immediately rather than from the next tick on.) Thus I don't see any real need for a hook in adjtimex; the rare case of an old-style adjustment being cancelled can be fixed up at the next tick. Signed-off-by: Paul Mackerras <paulus@samba.org> Acked-by: john stultz <johnstul@us.ibm.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-17 07:30:23 +08:00
extern void second_overflow(void);
extern void update_ntp_one_tick(void);
extern int do_adjtimex(struct timex *);
/* Don't use! Compatibility define for existing users. */
#define tickadj (500/HZ ? : 1)
int read_current_timer(unsigned long *timer_val);
#endif /* KERNEL */
#endif /* LINUX_TIMEX_H */