274 lines
11 KiB
C
274 lines
11 KiB
C
/******************************************************************************
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* *
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* Copyright (c) David L. Mills 1993, 1994 *
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* *
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* Permission to use, copy, modify, and distribute this software and its *
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* documentation for any purpose and without fee is hereby granted, provided *
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* that the above copyright notice appears in all copies and that both the *
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* copyright notice and this permission notice appear in supporting *
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* documentation, and that the name University of Delaware not be used in *
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* advertising or publicity pertaining to distribution of the software *
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* without specific, written prior permission. The University of Delaware *
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* makes no representations about the suitability this software for any *
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* purpose. It is provided "as is" without express or implied warranty. *
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* *
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******************************************************************************/
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/*
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* Modification history timex.h
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*
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* 19 Mar 94 David L. Mills
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* Moved defines from kernel routines to header file and added new
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* defines for PPS phase-lock loop.
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*
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* 20 Feb 94 David L. Mills
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* Revised status codes and structures for external clock and PPS
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* signal discipline.
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*
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* 28 Nov 93 David L. Mills
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* Adjusted parameters to improve stability and increase poll
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* interval.
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*
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* 17 Sep 93 David L. Mills
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* Created file
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*/
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/*
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* This header file defines the Network Time Protocol (NTP) interfaces
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* for user and daemon application programs. These are implemented using
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* private syscalls and data structures and require specific kernel
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* support.
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*
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* NAME
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* ntp_gettime - NTP user application interface
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*
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* SYNOPSIS
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* #include <sys/timex.h>
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*
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* int syscall(SYS_ntp_gettime, tptr)
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*
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* int SYS_ntp_gettime defined in syscall.h header file
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* struct ntptimeval *tptr pointer to ntptimeval structure
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*
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* NAME
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* ntp_adjtime - NTP daemon application interface
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*
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* SYNOPSIS
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* #include <sys/timex.h>
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*
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* int syscall(SYS_ntp_adjtime, mode, tptr)
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*
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* int SYS_ntp_adjtime defined in syscall.h header file
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* struct timex *tptr pointer to timex structure
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*
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*/
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#ifndef MSDOS /* Microsoft specific */
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#include <sys/syscall.h>
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#endif /* MSDOS */
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/*
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* The following defines establish the engineering parameters of the
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* phase-lock loop (PLL) model used in the kernel implementation. These
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* parameters have been carefully chosen by analysis for good stability
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* and wide dynamic range.
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*
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* The hz variable is defined in the kernel build environment. It
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* establishes the timer interrupt frequency, 100 Hz for the SunOS
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* kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the OSF/1
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* kernel. SHIFT_HZ expresses the same value as the nearest power of two
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* in order to avoid hardware multiply operations.
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*
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* SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen
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* for a slightly underdamped convergence characteristic.
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*
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* MAXTC establishes the maximum time constant of the PLL. With the
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* SHIFT_KG and SHIFT_KF values given and a time constant range from
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* zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
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* respectively.
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*/
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#define SHIFT_HZ 7 /* log2(hz) */
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#define SHIFT_KG 6 /* phase factor (shift) */
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#define SHIFT_KF 16 /* frequency factor (shift) */
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#define MAXTC 6 /* maximum time constant (shift) */
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/*
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* The following defines establish the scaling of the various variables
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* used by the PLL. They are chosen to allow the greatest precision
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* possible without overflow of a 32-bit word.
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*
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* SHIFT_SCALE defines the scaling (shift) of the time_phase variable,
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* which serves as a an extension to the low-order bits of the system
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* clock variable time.tv_usec.
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*
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* SHIFT_UPDATE defines the scaling (shift) of the time_offset variable,
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* which represents the current time offset with respect to standard
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* time.
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*
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* SHIFT_USEC defines the scaling (shift) of the time_freq and
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* time_tolerance variables, which represent the current frequency
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* offset and maximum frequency tolerance.
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*
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* FINEUSEC is 1 us in SHIFT_UPDATE units of the time_phase variable.
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*/
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#define SHIFT_SCALE 23 /* phase scale (shift) */
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#define SHIFT_UPDATE (SHIFT_KG + MAXTC) /* time offset scale (shift) */
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#define SHIFT_USEC 16 /* frequency offset scale (shift) */
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#define FINEUSEC (1L << SHIFT_SCALE) /* 1 us in phase units */
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/*
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* The following defines establish the performance envelope of the PLL.
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* They insure it operates within predefined limits, in order to satisfy
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* correctness assertions. An excursion which exceeds these bounds is
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* clamped to the bound and operation proceeds accordingly. In practice,
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* this can occur only if something has failed or is operating out of
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* tolerance, but otherwise the PLL continues to operate in a stable
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* mode.
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*
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* MAXPHASE must be set greater than or equal to CLOCK.MAX (128 ms), as
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* defined in the NTP specification. CLOCK.MAX establishes the maximum
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* time offset allowed before the system time is reset, rather than
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* incrementally adjusted. Here, the maximum offset is clamped to
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* MAXPHASE only in order to prevent overflow errors due to defective
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* protocol implementations.
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*
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* MAXFREQ is the maximum frequency tolerance of the CPU clock
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* oscillator plus the maximum slew rate allowed by the protocol. It
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* should be set to at least the frequency tolerance of the oscillator
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* plus 100 ppm for vernier frequency adjustments. If the kernel
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* PPS discipline code is configured (PPS_SYNC), the oscillator time and
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* frequency are disciplined to an external source, presumably with
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* negligible time and frequency error relative to UTC, and MAXFREQ can
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* be reduced.
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*
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* MAXTIME is the maximum jitter tolerance of the PPS signal if the
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* kernel PPS discipline code is configured (PPS_SYNC).
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*
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* MINSEC and MAXSEC define the lower and upper bounds on the interval
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* between protocol updates.
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*/
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#define MAXPHASE 128000L /* max phase error (us) */
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#ifdef PPS_SYNC
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#define MAXFREQ (100L << SHIFT_USEC) /* max freq error (100 ppm) */
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#define MAXTIME (200L << PPS_AVG) /* max PPS error (jitter) (200 us) */
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#else
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#define MAXFREQ (200L << SHIFT_USEC) /* max freq error (200 ppm) */
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#endif /* PPS_SYNC */
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#define MINSEC 16L /* min interval between updates (s) */
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#define MAXSEC 1200L /* max interval between updates (s) */
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#ifdef PPS_SYNC
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/*
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* The following defines are used only if a pulse-per-second (PPS)
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* signal is available and connected via a modem control lead, such as
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* produced by the optional ppsclock feature incorporated in the Sun
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* asynch driver. They establish the design parameters of the frequency-
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* lock loop used to discipline the CPU clock oscillator to the PPS
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* signal.
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*
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* PPS_AVG is the averaging factor for the frequency loop, as well as
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* the time and frequency dispersion.
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*
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* PPS_SHIFT and PPS_SHIFTMAX specify the minimum and maximum
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* calibration intervals, respectively, in seconds as a power of two.
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*
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* PPS_VALID is the maximum interval before the PPS signal is considered
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* invalid and protocol updates used directly instead.
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*
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* MAXGLITCH is the maximum interval before a time offset of more than
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* MAXTIME is believed.
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*/
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#define PPS_AVG 2 /* pps averaging constant (shift) */
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#define PPS_SHIFT 2 /* min interval duration (s) (shift) */
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#define PPS_SHIFTMAX 8 /* max interval duration (s) (shift) */
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#define PPS_VALID 120 /* pps signal watchdog max (s) */
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#define MAXGLITCH 30 /* pps signal glitch max (s) */
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#endif /* PPS_SYNC */
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/*
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* The following defines and structures define the user interface for
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* the ntp_gettime() and ntp_adjtime() system calls.
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*
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* Control mode codes (timex.modes)
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*/
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#define MOD_OFFSET 0x0001 /* set time offset */
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#define MOD_FREQUENCY 0x0002 /* set frequency offset */
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#define MOD_MAXERROR 0x0004 /* set maximum time error */
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#define MOD_ESTERROR 0x0008 /* set estimated time error */
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#define MOD_STATUS 0x0010 /* set clock status bits */
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#define MOD_TIMECONST 0x0020 /* set pll time constant */
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#define MOD_CLKB 0x4000 /* set clock B */
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#define MOD_CLKA 0x8000 /* set clock A */
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/*
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* Status codes (timex.status)
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*/
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#define STA_PLL 0x0001 /* enable PLL updates (rw) */
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#define STA_PPSFREQ 0x0002 /* enable PPS freq discipline (rw) */
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#define STA_PPSTIME 0x0004 /* enable PPS time discipline (rw) */
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#define STA_INS 0x0010 /* insert leap (rw) */
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#define STA_DEL 0x0020 /* delete leap (rw) */
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#define STA_UNSYNC 0x0040 /* clock unsynchronized (rw) */
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#define STA_PPSSIGNAL 0x0100 /* PPS signal present (ro) */
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#define STA_PPSJITTER 0x0200 /* PPS signal jitter exceeded (ro) */
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#define STA_PPSWANDER 0x0400 /* PPS signal wander exceeded (ro) */
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#define STA_PPSERROR 0x0800 /* PPS signal calibration error (ro) */
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#define STA_CLOCKERR 0x1000 /* clock hardware fault (ro) */
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#define STA_RONLY (STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | \
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STA_PPSERROR | STA_CLOCKERR) /* read-only bits */
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/*
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* Clock states (time_state)
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*/
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#define TIME_OK 0 /* no leap second warning */
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#define TIME_INS 1 /* insert leap second warning */
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#define TIME_DEL 2 /* delete leap second warning */
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#define TIME_OOP 3 /* leap second in progress */
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#define TIME_WAIT 4 /* leap second has occured */
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#define TIME_ERROR 5 /* clock not synchronized */
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/*
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* NTP user interface (ntp_gettime()) - used to read kernel clock values
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*
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* Note: maximum error = NTP synch distance = dispersion + delay / 2;
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* estimated error = NTP dispersion.
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*/
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struct ntptimeval {
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struct timeval time; /* current time (ro) */
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LONG maxerror; /* maximum error (us) (ro) */
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LONG esterror; /* estimated error (us) (ro) */
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};
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/*
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* NTP daemon interface - (ntp_adjtime()) used to discipline CPU clock
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* oscillator
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*/
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struct timex {
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unsigned int modes; /* clock mode bits (wo) */
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LONG offset; /* time offset (us) (rw) */
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LONG freq; /* frequency offset (scaled ppm) (rw) */
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LONG maxerror; /* maximum error (us) (rw) */
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LONG esterror; /* estimated error (us) (rw) */
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int status; /* clock status bits (rw) */
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LONG constant; /* pll time constant (rw) */
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LONG precision; /* clock precision (us) (ro) */
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LONG tolerance; /* clock frequency tolerance (scaled
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* ppm) (ro) */
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/*
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* The following read-only structure members are implemented
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* only if the PPS signal discipline is configured in the
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* kernel.
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*/
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LONG ppsfreq; /* pps frequency (scaled ppm) (ro) */
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LONG jitter; /* pps jitter (us) (ro) */
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int shift; /* interval duration (s) (shift) (ro) */
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LONG stabil; /* pps stability (scaled ppm) (ro) */
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LONG jitcnt; /* jitter limit exceeded (ro) */
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LONG calcnt; /* calibration intervals (ro) */
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LONG errcnt; /* calibration errors (ro) */
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LONG stbcnt; /* stability limit exceeded (ro) */
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};
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