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_rtc.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  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      from: Utah $Hdr: clock.c 1.18 91/01/21$
   35  *      from: @(#)clock.c       8.2 (Berkeley) 1/12/94
   36  *      from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
   37  *      and
   38  *      from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
   39  */
   40 
   41 /*
   42  * Helpers for time-of-day clocks. This is useful for architectures that need
   43  * support multiple models of such clocks, and generally serves to make the
   44  * code more machine-independent.
   45  * If the clock in question can also be used as a time counter, the driver
   46  * needs to initiate this.
   47  * This code is not yet used by all architectures.
   48  */
   49 
   50 #include <sys/cdefs.h>
   51 __FBSDID("$FreeBSD$");
   52 
   53 #include <sys/param.h>
   54 #include <sys/systm.h>
   55 #include <sys/kernel.h>
   56 #include <sys/bus.h>
   57 #include <sys/clock.h>
   58 #include <sys/sysctl.h>
   59 #include <sys/timetc.h>
   60 
   61 #include "clock_if.h"
   62 
   63 static device_t clock_dev = NULL;
   64 static long clock_res;
   65 
   66 void
   67 clock_register(device_t dev, long res)  /* res has units of microseconds */
   68 {
   69 
   70         if (clock_dev != NULL) {
   71                 if (clock_res > res) {
   72                         if (bootverbose) {
   73                                 device_printf(dev, "not installed as "
   74                                     "time-of-day clock: clock %s has higher "
   75                                     "resolution\n", device_get_name(clock_dev));
   76                         }
   77                         return;
   78                 } else {
   79                         if (bootverbose) {
   80                                 device_printf(clock_dev, "removed as "
   81                                     "time-of-day clock: clock %s has higher "
   82                                     "resolution\n", device_get_name(dev));
   83                         }
   84                 }
   85         }
   86         clock_dev = dev;
   87         clock_res = res;
   88         if (bootverbose) {
   89                 device_printf(dev, "registered as a time-of-day clock "
   90                     "(resolution %ldus)\n", res);
   91         }
   92 }
   93 
   94 /*
   95  * inittodr and settodr derived from the i386 versions written
   96  * by Christoph Robitschko <chmr@edvz.tu-graz.ac.at>,  reintroduced and
   97  * updated by Chris Stenton <chris@gnome.co.uk> 8/10/94
   98  */
   99 
  100 /*
  101  * Initialize the time of day register, based on the time base which is, e.g.
  102  * from a filesystem.
  103  */
  104 void
  105 inittodr(time_t base)
  106 {
  107         struct timespec diff, ref, ts;
  108         int error;
  109 
  110         if (base) {
  111                 ref.tv_sec = base;
  112                 ref.tv_nsec = 0;
  113                 tc_setclock(&ref);
  114         }
  115 
  116         if (clock_dev == NULL) {
  117                 printf("warning: no time-of-day clock registered, system time "
  118                     "will not be set accurately\n");
  119                 return;
  120         }
  121         error = CLOCK_GETTIME(clock_dev, &ts);
  122         if (error != 0 && error != EINVAL) {
  123                 printf("warning: clock_gettime failed (%d), the system time "
  124                     "will not be set accurately\n", error);
  125                 return;
  126         }
  127         if (error == EINVAL || ts.tv_sec < 0) {
  128                 printf("Invalid time in real time clock.\n");
  129                 printf("Check and reset the date immediately!\n");
  130         }
  131 
  132         ts.tv_sec += utc_offset();
  133 
  134         if (timespeccmp(&ref, &ts, >)) {
  135                 diff = ref;
  136                 timespecsub(&ref, &ts);
  137         } else {
  138                 diff = ts;
  139                 timespecsub(&diff, &ref);
  140         }
  141         if (ts.tv_sec >= 2) {
  142                 /* badly off, adjust it */
  143                 tc_setclock(&ts);
  144         }
  145 }
  146 
  147 /*
  148  * Write system time back to RTC
  149  */
  150 void
  151 resettodr()
  152 {
  153         struct timespec ts;
  154         int error;
  155 
  156         if (disable_rtc_set || clock_dev == NULL)
  157                 return;
  158 
  159         getnanotime(&ts);
  160         ts.tv_sec -= utc_offset();
  161         if ((error = CLOCK_SETTIME(clock_dev, &ts)) != 0) {
  162                 printf("warning: clock_settime failed (%d), time-of-day clock "
  163                     "not adjusted to system time\n", error);
  164                 return;
  165         }
  166 }

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