The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_clock.c

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    1 /*
    2  * Copyright (c) 1988 University of Utah.
    3  * Copyright (c) 1982, 1990, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * the Systems Programming Group of the University of Utah Computer
    8  * Science Department.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *      This product includes software developed by the University of
   21  *      California, Berkeley and its contributors.
   22  * 4. Neither the name of the University nor the names of its contributors
   23  *    may be used to endorse or promote products derived from this software
   24  *    without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   36  * SUCH DAMAGE.
   37  *
   38  *      from: Utah $Hdr: clock.c 1.18 91/01/21$
   39  *      from: @(#)clock.c       8.2 (Berkeley) 1/12/94
   40  *      from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
   41  *      and
   42  *      from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
   43  */
   44 
   45 /*
   46  * Helpers for time-of-day clocks. This is useful for architectures that need
   47  * support multiple models of such clocks, and generally serves to make the
   48  * code more machine-independent.
   49  * If the clock in question can also be used as a time counter, the driver
   50  * needs to initiate this.
   51  * This code is not yet used by all architectures.
   52  */
   53 
   54 /*
   55  * Generic routines to convert between a POSIX date
   56  * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
   57  * Derived from NetBSD arch/hp300/hp300/clock.c
   58  */
   59 
   60 #include <sys/cdefs.h>
   61 __FBSDID("$FreeBSD: releng/5.2/sys/kern/subr_clock.c 116182 2003-06-11 00:56:59Z obrien $");
   62 
   63 #include <sys/param.h>
   64 #include <sys/systm.h>
   65 #include <sys/kernel.h>
   66 #include <sys/bus.h>
   67 #include <sys/clock.h>
   68 #include <sys/sysctl.h>
   69 #include <sys/timetc.h>
   70 
   71 /* XXX: for the  CPU_* sysctl OID constants. */
   72 #include <machine/cpu.h>
   73 
   74 #include "clock_if.h"
   75 
   76 static __inline int leapyear(int year);
   77 static int sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS);
   78 
   79 #define FEBRUARY        2
   80 #define days_in_year(y)         (leapyear(y) ? 366 : 365)
   81 #define days_in_month(y, m) \
   82         (month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
   83 /* Day of week. Days are counted from 1/1/1970, which was a Thursday */
   84 #define day_of_week(days)       (((days) + 4) % 7)
   85 
   86 static const int month_days[12] = {
   87         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
   88 };
   89 
   90 static device_t clock_dev = NULL;
   91 static long clock_res;
   92 
   93 int adjkerntz;          /* local offset from GMT in seconds */
   94 int disable_rtc_set;    /* disable resettodr() if != 0 */
   95 int wall_cmos_clock;    /* wall CMOS clock assumed if != 0 */
   96 
   97 /*
   98  * These have traditionally been in machdep, but should probably be moved to
   99  * kern.
  100  */
  101 SYSCTL_PROC(_machdep, CPU_ADJKERNTZ, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
  102         &adjkerntz, 0, sysctl_machdep_adjkerntz, "I", "");
  103 
  104 SYSCTL_INT(_machdep, CPU_DISRTCSET, disable_rtc_set,
  105         CTLFLAG_RW, &disable_rtc_set, 0, "");
  106 
  107 SYSCTL_INT(_machdep, CPU_WALLCLOCK, wall_cmos_clock,
  108         CTLFLAG_RW, &wall_cmos_clock, 0, "");
  109 
  110 static int
  111 sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
  112 {
  113         int error;
  114         error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2,
  115                 req);
  116         if (!error && req->newptr)
  117                 resettodr();
  118         return (error);
  119 }
  120 
  121 /*
  122  * This inline avoids some unnecessary modulo operations
  123  * as compared with the usual macro:
  124  *   ( ((year % 4) == 0 &&
  125  *      (year % 100) != 0) ||
  126  *     ((year % 400) == 0) )
  127  * It is otherwise equivalent.
  128  */
  129 static __inline int
  130 leapyear(int year)
  131 {
  132         int rv = 0;
  133 
  134         if ((year & 3) == 0) {
  135                 rv = 1;
  136                 if ((year % 100) == 0) {
  137                         rv = 0;
  138                         if ((year % 400) == 0)
  139                                 rv = 1;
  140                 }
  141         }
  142         return (rv);
  143 }
  144 
  145 int
  146 clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
  147 {
  148         time_t secs;
  149         int i, year, days;
  150 
  151         year = ct->year;
  152 
  153         /* Sanity checks. */
  154         if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
  155             ct->day > days_in_month(year, ct->mon) ||
  156             ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 ||
  157             ct->year > 2037)            /* time_t overflow */
  158                 return (EINVAL);
  159 
  160         /*
  161          * Compute days since start of time
  162          * First from years, then from months.
  163          */
  164         days = 0;
  165         for (i = POSIX_BASE_YEAR; i < year; i++)
  166                 days += days_in_year(i);
  167 
  168         /* Months */
  169         for (i = 1; i < ct->mon; i++)
  170                 days += days_in_month(year, i);
  171         days += (ct->day - 1);
  172 
  173         /* Another sanity check. */
  174         if (ct->dow != -1 && ct->dow != day_of_week(days))
  175                 return (EINVAL);
  176 
  177         /* Add hours, minutes, seconds. */
  178         secs = ((days * 24 + ct->hour) * 60 + ct->min) * 60 + ct->sec;
  179 
  180         ts->tv_sec = secs;
  181         ts->tv_nsec = ct->nsec;
  182         return (0);
  183 }
  184 
  185 void
  186 clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
  187 {
  188         int i, year, days;
  189         time_t rsec;    /* remainder seconds */
  190         time_t secs;
  191 
  192         secs = ts->tv_sec;
  193         days = secs / SECDAY;
  194         rsec = secs % SECDAY;
  195 
  196         ct->dow = day_of_week(days);
  197 
  198         /* Subtract out whole years, counting them in i. */
  199         for (year = POSIX_BASE_YEAR; days >= days_in_year(year); year++)
  200                 days -= days_in_year(year);
  201         ct->year = year;
  202 
  203         /* Subtract out whole months, counting them in i. */
  204         for (i = 1; days >= days_in_month(year, i); i++)
  205                 days -= days_in_month(year, i);
  206         ct->mon = i;
  207 
  208         /* Days are what is left over (+1) from all that. */
  209         ct->day = days + 1;
  210 
  211         /* Hours, minutes, seconds are easy */
  212         ct->hour = rsec / 3600;
  213         rsec = rsec % 3600;
  214         ct->min  = rsec / 60;
  215         rsec = rsec % 60;
  216         ct->sec  = rsec;
  217         ct->nsec = ts->tv_nsec;
  218 }
  219 
  220 void
  221 clock_register(device_t dev, long res)
  222 {
  223 
  224         if (clock_dev != NULL) {
  225                 if (clock_res > res) {
  226                         if (bootverbose) {
  227                                 device_printf(dev, "not installed as "
  228                                     "time-of-day clock: clock %s has higher "
  229                                     "resolution\n", device_get_name(clock_dev));
  230                         }
  231                         return;
  232                 } else {
  233                         if (bootverbose) {
  234                                 device_printf(clock_dev, "removed as "
  235                                     "time-of-day clock: clock %s has higher "
  236                                     "resolution\n", device_get_name(dev));
  237                         }
  238                 }
  239         }
  240         clock_dev = dev;
  241         clock_res = res;
  242         if (bootverbose) {
  243                 device_printf(dev, "registered as a time-of-day clock "
  244                     "(resolution %ldus)\n", res);
  245         }
  246 }
  247 
  248 /*
  249  * inittodr and settodr derived from the i386 versions written
  250  * by Christoph Robitschko <chmr@edvz.tu-graz.ac.at>,  reintroduced and
  251  * updated by Chris Stenton <chris@gnome.co.uk> 8/10/94
  252  */
  253 
  254 /*
  255  * Initialize the time of day register, based on the time base which is, e.g.
  256  * from a filesystem.
  257  */
  258 void
  259 inittodr(time_t base)
  260 {
  261         struct timespec diff, ref, ts;
  262         int error;
  263 
  264         if (base) {
  265                 ref.tv_sec = base;
  266                 ref.tv_nsec = 0;
  267                 tc_setclock(&ref);
  268         }
  269 
  270         if (clock_dev == NULL) {
  271                 printf("warning: no time-of-day clock registered, system time "
  272                     "will not be set accurately\n");
  273                 return;
  274         }
  275         error = CLOCK_GETTIME(clock_dev, &ts);
  276         if (error != 0 && error != EINVAL) {
  277                 printf("warning: clock_gettime failed (%d), the system time "
  278                     "will not be set accurately\n", error);
  279                 return;
  280         }
  281         if (error == EINVAL || ts.tv_sec < 0) {
  282                 printf("Invalid time in real time clock.\n");
  283                 printf("Check and reset the date immediately!\n");
  284         }
  285 
  286         ts.tv_sec += tz_minuteswest * 60 +
  287             (wall_cmos_clock ? adjkerntz : 0);
  288 
  289         if (timespeccmp(&ref, &ts, >)) {
  290                 diff = ref;
  291                 timespecsub(&ref, &ts);
  292         } else {
  293                 diff = ts;
  294                 timespecsub(&diff, &ref);
  295         }
  296         if (ts.tv_sec >= 2) {
  297                 /* badly off, adjust it */
  298                 tc_setclock(&ts);
  299         }
  300 }
  301 
  302 /*
  303  * Write system time back to RTC
  304  */
  305 void
  306 resettodr()
  307 {
  308         struct timespec ts;
  309         int error;
  310 
  311         if (disable_rtc_set || clock_dev == NULL)
  312                 return;
  313 
  314         getnanotime(&ts);
  315         ts.tv_sec -= tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0);
  316         if ((error = CLOCK_SETTIME(clock_dev, &ts)) != 0) {
  317                 printf("warning: clock_settime failed (%d), time-of-day clock "
  318                     "not adjusted to system time\n", error);
  319                 return;
  320         }
  321 }

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