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.
    5  * Copyright (c) 2011 The FreeBSD Foundation
    6  * All rights reserved.
    7  *
    8  * This code is derived from software contributed to Berkeley by
    9  * the Systems Programming Group of the University of Utah Computer
   10  * Science Department.
   11  *
   12  * Portions of this software were developed by Julien Ridoux at the University
   13  * of Melbourne under sponsorship from the FreeBSD Foundation.
   14  *
   15  * Redistribution and use in source and binary forms, with or without
   16  * modification, are permitted provided that the following conditions
   17  * are met:
   18  * 1. Redistributions of source code must retain the above copyright
   19  *    notice, this list of conditions and the following disclaimer.
   20  * 2. Redistributions in binary form must reproduce the above copyright
   21  *    notice, this list of conditions and the following disclaimer in the
   22  *    documentation and/or other materials provided with the distribution.
   23  * 4. Neither the name of the University nor the names of its contributors
   24  *    may be used to endorse or promote products derived from this software
   25  *    without specific prior written permission.
   26  *
   27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   37  * SUCH DAMAGE.
   38  *
   39  *      from: Utah $Hdr: clock.c 1.18 91/01/21$
   40  *      from: @(#)clock.c       8.2 (Berkeley) 1/12/94
   41  *      from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
   42  *      and
   43  *      from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
   44  */
   45 
   46 /*
   47  * Helpers for time-of-day clocks. This is useful for architectures that need
   48  * support multiple models of such clocks, and generally serves to make the
   49  * code more machine-independent.
   50  * If the clock in question can also be used as a time counter, the driver
   51  * needs to initiate this.
   52  * This code is not yet used by all architectures.
   53  */
   54 
   55 #include <sys/cdefs.h>
   56 __FBSDID("$FreeBSD: stable/10/sys/kern/subr_rtc.c 306501 2016-09-30 13:49:50Z royger $");
   57 
   58 #include "opt_ffclock.h"
   59 
   60 #include <sys/param.h>
   61 #include <sys/systm.h>
   62 #include <sys/kernel.h>
   63 #include <sys/bus.h>
   64 #include <sys/clock.h>
   65 #include <sys/sysctl.h>
   66 #ifdef FFCLOCK
   67 #include <sys/timeffc.h>
   68 #endif
   69 #include <sys/timetc.h>
   70 
   71 #include "clock_if.h"
   72 
   73 static device_t clock_dev = NULL;
   74 static long clock_res;
   75 static struct timespec clock_adj;
   76 
   77 /* XXX: should be kern. now, it's no longer machdep.  */
   78 static int disable_rtc_set;
   79 SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set, CTLFLAG_RW, &disable_rtc_set,
   80     0, "Disallow adjusting time-of-day clock");
   81 
   82 void
   83 clock_register(device_t dev, long res)  /* res has units of microseconds */
   84 {
   85 
   86         if (clock_dev != NULL) {
   87                 if (clock_res <= res) {
   88                         if (bootverbose)
   89                                 device_printf(dev, "not installed as "
   90                                     "time-of-day clock: clock %s has higher "
   91                                     "resolution\n", device_get_name(clock_dev));
   92                         return;
   93                 }
   94                 if (bootverbose)
   95                         device_printf(clock_dev, "removed as "
   96                             "time-of-day clock: clock %s has higher "
   97                             "resolution\n", device_get_name(dev));
   98         }
   99         clock_dev = dev;
  100         clock_res = res;
  101         clock_adj.tv_sec = res / 2 / 1000000;
  102         clock_adj.tv_nsec = res / 2 % 1000000 * 1000;
  103         if (bootverbose)
  104                 device_printf(dev, "registered as a time-of-day clock "
  105                     "(resolution %ldus, adjustment %jd.%09jds)\n", res,
  106                     (intmax_t)clock_adj.tv_sec, (intmax_t)clock_adj.tv_nsec);
  107 }
  108 
  109 /*
  110  * inittodr and settodr derived from the i386 versions written
  111  * by Christoph Robitschko <chmr@edvz.tu-graz.ac.at>,  reintroduced and
  112  * updated by Chris Stenton <chris@gnome.co.uk> 8/10/94
  113  */
  114 
  115 /*
  116  * Initialize the time of day register, based on the time base which is, e.g.
  117  * from a filesystem.
  118  */
  119 void
  120 inittodr(time_t base)
  121 {
  122         struct timespec ts;
  123         int error;
  124 
  125         if (clock_dev == NULL) {
  126                 printf("warning: no time-of-day clock registered, system time "
  127                     "will not be set accurately\n");
  128                 goto wrong_time;
  129         }
  130         /* XXX: We should poll all registered RTCs in case of failure */
  131         error = CLOCK_GETTIME(clock_dev, &ts);
  132         if (error != 0 && error != EINVAL) {
  133                 printf("warning: clock_gettime failed (%d), the system time "
  134                     "will not be set accurately\n", error);
  135                 goto wrong_time;
  136         }
  137         if (error == EINVAL || ts.tv_sec < 0) {
  138                 printf("Invalid time in real time clock.\n"
  139                     "Check and reset the date immediately!\n");
  140                 goto wrong_time;
  141         }
  142 
  143         ts.tv_sec += utc_offset();
  144         timespecadd(&ts, &clock_adj);
  145         tc_setclock(&ts);
  146 #ifdef FFCLOCK
  147         ffclock_reset_clock(&ts);
  148 #endif
  149         return;
  150 
  151 wrong_time:
  152         if (base > 0) {
  153                 ts.tv_sec = base;
  154                 ts.tv_nsec = 0;
  155                 tc_setclock(&ts);
  156         }
  157 }
  158 
  159 /*
  160  * Write system time back to RTC
  161  */
  162 void
  163 resettodr(void)
  164 {
  165         struct timespec ts;
  166         int error;
  167 
  168         if (disable_rtc_set || clock_dev == NULL)
  169                 return;
  170 
  171         getnanotime(&ts);
  172         timespecadd(&ts, &clock_adj);
  173         ts.tv_sec -= utc_offset();
  174         /* XXX: We should really set all registered RTCs */
  175         if ((error = CLOCK_SETTIME(clock_dev, &ts)) != 0)
  176                 printf("warning: clock_settime failed (%d), time-of-day clock "
  177                     "not adjusted to system time\n", error);
  178 }

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