2.2.0-final

[davej-history.git] / kernel / time.c

/*
 *  linux/kernel/time.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  This file contains the interface functions for the various
 *  time related system calls: time, stime, gettimeofday, settimeofday,
 *                             adjtime
 */
/*
 * Modification history kernel/time.c
 * 
 * 1993-09-02    Philip Gladstone
 *      Created file with time related functions from sched.c and adjtimex() 
 * 1993-10-08    Torsten Duwe
 *      adjtime interface update and CMOS clock write code
 * 1995-08-13    Torsten Duwe
 *      kernel PLL updated to 1994-12-13 specs (rfc-1589)
 * 1999-01-16    Ulrich Windl
 *      Introduced error checking for many cases in adjtimex().
 *      Updated NTP code according to technical memorandum Jan '96
 *      "A Kernel Model for Precision Timekeeping" by Dave Mills
 *      Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10)
 *      (Even though the technical memorandum forbids it)
 */

#include <linux/mm.h>
#include <linux/timex.h>
#include <linux/smp_lock.h>

#include <asm/uaccess.h>

/* 
 * The timezone where the local system is located.  Used as a default by some
 * programs who obtain this value by using gettimeofday.
 */
struct timezone sys_tz = { 0, 0};

static void do_normal_gettime(struct timeval * tm)
{
        *tm=xtime;
}

void (*do_get_fast_time)(struct timeval *) = do_normal_gettime;

/*
 * Generic way to access 'xtime' (the current time of day).
 * This can be changed if the platform provides a more accurate (and fast!) 
 * version.
 */

void get_fast_time(struct timeval * t)
{
        do_get_fast_time(t);
}

#ifndef __alpha__

/*
 * sys_time() can be implemented in user-level using
 * sys_gettimeofday().  Is this for backwards compatibility?  If so,
 * why not move it into the appropriate arch directory (for those
 * architectures that need it).
 */
asmlinkage int sys_time(int * tloc)
{
        int i;

        /* SMP: This is fairly trivial. We grab CURRENT_TIME and 
           stuff it to user space. No side effects */
        i = CURRENT_TIME;
        if (tloc) {
                if (put_user(i,tloc))
                        i = -EFAULT;
        }
        return i;
}

/*
 * sys_stime() can be implemented in user-level using
 * sys_settimeofday().  Is this for backwards compatibility?  If so,
 * why not move it into the appropriate arch directory (for those
 * architectures that need it).
 */
 
asmlinkage int sys_stime(int * tptr)
{
        int value;

        if (!capable(CAP_SYS_TIME))
                return -EPERM;
        if (get_user(value, tptr))
                return -EFAULT;
        cli();
        xtime.tv_sec = value;
        xtime.tv_usec = 0;
        time_adjust = 0;        /* stop active adjtime() */
        time_status |= STA_UNSYNC;
        time_state = TIME_ERROR;        /* p. 24, (a) */
        time_maxerror = NTP_PHASE_LIMIT;
        time_esterror = NTP_PHASE_LIMIT;
        sti();
        return 0;
}

#endif

asmlinkage int sys_gettimeofday(struct timeval *tv, struct timezone *tz)
{
        if (tv) {
                struct timeval ktv;
                do_gettimeofday(&ktv);
                if (copy_to_user(tv, &ktv, sizeof(ktv)))
                        return -EFAULT;
        }
        if (tz) {
                if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
                        return -EFAULT;
        }
        return 0;
}

/*
 * Adjust the time obtained from the CMOS to be UTC time instead of
 * local time.
 * 
 * This is ugly, but preferable to the alternatives.  Otherwise we
 * would either need to write a program to do it in /etc/rc (and risk
 * confusion if the program gets run more than once; it would also be 
 * hard to make the program warp the clock precisely n hours)  or
 * compile in the timezone information into the kernel.  Bad, bad....
 *
 *                                              - TYT, 1992-01-01
 *
 * The best thing to do is to keep the CMOS clock in universal time (UTC)
 * as real UNIX machines always do it. This avoids all headaches about
 * daylight saving times and warping kernel clocks.
 */
inline static void warp_clock(void)
{
        cli();
        xtime.tv_sec += sys_tz.tz_minuteswest * 60;
        sti();
}

/*
 * In case for some reason the CMOS clock has not already been running
 * in UTC, but in some local time: The first time we set the timezone,
 * we will warp the clock so that it is ticking UTC time instead of
 * local time. Presumably, if someone is setting the timezone then we
 * are running in an environment where the programs understand about
 * timezones. This should be done at boot time in the /etc/rc script,
 * as soon as possible, so that the clock can be set right. Otherwise,
 * various programs will get confused when the clock gets warped.
 */

int do_sys_settimeofday(struct timeval *tv, struct timezone *tz)
{
        static int firsttime = 1;

        if (!capable(CAP_SYS_TIME))
                return -EPERM;
                
        if (tz) {
                /* SMP safe, global irq locking makes it work. */
                sys_tz = *tz;
                if (firsttime) {
                        firsttime = 0;
                        if (!tv)
                                warp_clock();
                }
        }
        if (tv)
        {
                /* SMP safe, again the code in arch/foo/time.c should
                 * globally block out interrupts when it runs.
                 */
                do_settimeofday(tv);
        }
        return 0;
}

asmlinkage int sys_settimeofday(struct timeval *tv, struct timezone *tz)
{
        struct timeval  new_tv;
        struct timezone new_tz;

        if (tv) {
                if (copy_from_user(&new_tv, tv, sizeof(*tv)))
                        return -EFAULT;
        }
        if (tz) {
                if (copy_from_user(&new_tz, tz, sizeof(*tz)))
                        return -EFAULT;
        }

        return do_sys_settimeofday(tv ? &new_tv : NULL, tz ? &new_tz : NULL);
}

long pps_offset = 0;            /* pps time offset (us) */
long pps_jitter = MAXTIME;      /* time dispersion (jitter) (us) */

long pps_freq = 0;              /* frequency offset (scaled ppm) */
long pps_stabil = MAXFREQ;      /* frequency dispersion (scaled ppm) */

long pps_valid = PPS_VALID;     /* pps signal watchdog counter */

int pps_shift = PPS_SHIFT;      /* interval duration (s) (shift) */

long pps_jitcnt = 0;            /* jitter limit exceeded */
long pps_calcnt = 0;            /* calibration intervals */
long pps_errcnt = 0;            /* calibration errors */
long pps_stbcnt = 0;            /* stability limit exceeded */

/* hook for a loadable hardpps kernel module */
void (*hardpps_ptr)(struct timeval *) = (void (*)(struct timeval *))0;

/* adjtimex mainly allows reading (and writing, if superuser) of
 * kernel time-keeping variables. used by xntpd.
 */
int do_adjtimex(struct timex *txc)
{
        long ltemp, mtemp, save_adjust;
        int error = 0;

        /* In order to modify anything, you gotta be super-user! */
        if (txc->modes && !capable(CAP_SYS_TIME))
                return -EPERM;
                
        /* Now we validate the data before disabling interrupts */

        if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
          /* adjustment Offset limited to +- .512 seconds */
                if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
                        return -EINVAL; 

        /* if the quartz is off by more than 10% something is VERY wrong ! */
        if (txc->modes & ADJ_TICK)
                if (txc->tick < 900000/HZ || txc->tick > 1100000/HZ)
                        return -EINVAL;

        cli(); /* SMP: global cli() is enough protection. */

        /* Save for later - semantics of adjtime is to return old value */
        save_adjust = time_adjust;

#if 0   /* STA_CLOCKERR is never set yet */
        time_status &= ~STA_CLOCKERR;           /* reset STA_CLOCKERR */
#endif
        /* If there are input parameters, then process them */
        if (txc->modes)
        {
            if (time_state == TIME_ERROR)
                time_state = TIME_OK;           /* reset error -- why? */

            if (txc->modes & ADJ_STATUS)        /* only set allowed bits */
                time_status =  (txc->status & ~STA_RONLY) |
                              (time_status & STA_RONLY);

            if (txc->modes & ADJ_FREQUENCY) {   /* p. 22 */
                if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) {
                    error = -EINVAL;
                    goto leave;
                }
                time_freq = txc->freq - pps_freq;
            }

            if (txc->modes & ADJ_MAXERROR) {
                if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) {
                    error = -EINVAL;
                    goto leave;
                }
                time_maxerror = txc->maxerror;
            }

            if (txc->modes & ADJ_ESTERROR) {
                if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
                    error = -EINVAL;
                    goto leave;
                }
                time_esterror = txc->esterror;
            }

            if (txc->modes & ADJ_TIMECONST) {   /* p. 24 */
                if (txc->constant < 0) {        /* NTP v4 uses values > 6 */
                    error = -EINVAL;
                    goto leave;
                }
                time_constant = txc->constant;
            }

            if (txc->modes & ADJ_OFFSET) {      /* values checked earlier */
                if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
                    /* adjtime() is independent from ntp_adjtime() */
                    time_adjust = txc->offset;
                }
                else if ( time_status & (STA_PLL | STA_PPSTIME) ) {
                    ltemp = (time_status & (STA_PPSTIME | STA_PPSSIGNAL)) ==
                            (STA_PPSTIME | STA_PPSSIGNAL) ?
                            pps_offset : txc->offset;

                    /*
                     * Scale the phase adjustment and
                     * clamp to the operating range.
                     */
                    if (ltemp > MAXPHASE)
                        time_offset = MAXPHASE << SHIFT_UPDATE;
                    else if (ltemp < -MAXPHASE)
                        time_offset = -(MAXPHASE << SHIFT_UPDATE);
                    else
                        time_offset = ltemp << SHIFT_UPDATE;

                    /*
                     * Select whether the frequency is to be controlled
                     * and in which mode (PLL or FLL). Clamp to the operating
                     * range. Ugly multiply/divide should be replaced someday.
                     */

                    if (time_status & STA_FREQHOLD || time_reftime == 0)
                        time_reftime = xtime.tv_sec;
                    mtemp = xtime.tv_sec - time_reftime;
                    time_reftime = xtime.tv_sec;
                    if (time_status & STA_FLL) {
                        if (mtemp >= MINSEC) {
                            ltemp = (time_offset / mtemp) << (SHIFT_USEC -
                                                              SHIFT_UPDATE);
                            if (ltemp < 0)
                                time_freq -= -ltemp >> SHIFT_KH;
                            else
                                time_freq += ltemp >> SHIFT_KH;
                        } else /* calibration interval too short (p. 12) */
                                time_state = TIME_ERROR;
                    } else {    /* PLL mode */
                        if (mtemp < MAXSEC) {
                            ltemp *= mtemp;
                            if (ltemp < 0)
                                time_freq -= -ltemp >> (time_constant +
                                                        time_constant +
                                                        SHIFT_KF - SHIFT_USEC);
                            else
                                time_freq += ltemp >> (time_constant +
                                                       time_constant +
                                                       SHIFT_KF - SHIFT_USEC);
                        } else /* calibration interval too long (p. 12) */
                                time_state = TIME_ERROR;
                    }
                    if (time_freq > time_tolerance)
                        time_freq = time_tolerance;
                    else if (time_freq < -time_tolerance)
                        time_freq = -time_tolerance;
                } /* STA_PLL || STA_PPSTIME */
            } /* txc->modes & ADJ_OFFSET */
            if (txc->modes & ADJ_TICK) {
                /* if the quartz is off by more than 10% something is
                   VERY wrong ! */
                if (txc->tick < 900000/HZ || txc->tick > 1100000/HZ) {
                    error = -EINVAL;
                    goto leave;
                }
                tick = txc->tick;
            }
        } /* txc->modes */
leave:  if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0
            || ((time_status & (STA_PPSFREQ|STA_PPSTIME)) != 0
                && (time_status & STA_PPSSIGNAL) == 0)
            /* p. 24, (b) */
            || ((time_status & (STA_PPSTIME|STA_PPSJITTER))
                == (STA_PPSTIME|STA_PPSJITTER))
            /* p. 24, (c) */
            || ((time_status & STA_PPSFREQ) != 0
                && (time_status & (STA_PPSWANDER|STA_PPSERROR)) != 0))
            /* p. 24, (d) */
                time_state = TIME_ERROR;
        
        if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
            txc->offset    = save_adjust;
        else {
            if (time_offset < 0)
                txc->offset = -(-time_offset >> SHIFT_UPDATE);
            else
                txc->offset = time_offset >> SHIFT_UPDATE;
        }
        txc->freq          = time_freq + pps_freq;
        txc->maxerror      = time_maxerror;
        txc->esterror      = time_esterror;
        txc->status        = time_status;
        txc->constant      = time_constant;
        txc->precision     = time_precision;
        txc->tolerance     = time_tolerance;
        do_gettimeofday(&txc->time);
        txc->tick          = tick;
        txc->ppsfreq       = pps_freq;
        txc->jitter        = pps_jitter >> PPS_AVG;
        txc->shift         = pps_shift;
        txc->stabil        = pps_stabil;
        txc->jitcnt        = pps_jitcnt;
        txc->calcnt        = pps_calcnt;
        txc->errcnt        = pps_errcnt;
        txc->stbcnt        = pps_stbcnt;

        sti();
        return(error < 0 ? error : time_state);
}

asmlinkage int sys_adjtimex(struct timex *txc_p)
{
        struct timex txc;               /* Local copy of parameter */
        int ret;

        /* Copy the user data space into the kernel copy
         * structure. But bear in mind that the structures
         * may change
         */
        if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
                return -EFAULT;
        ret = do_adjtimex(&txc);
        return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
}