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: releng/11.1/sys/kern/subr_rtc.c 306403 2016-09-28 09:46:29Z kib $");
   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/lock.h>
   66 #include <sys/mutex.h>
   67 #include <sys/sysctl.h>
   68 #ifdef FFCLOCK
   69 #include <sys/timeffc.h>
   70 #endif
   71 #include <sys/timetc.h>
   72 
   73 #include "clock_if.h"
   74 
   75 static device_t clock_dev = NULL;
   76 static long clock_res;
   77 static struct timespec clock_adj;
   78 struct mtx resettodr_lock;
   79 MTX_SYSINIT(resettodr_init, &resettodr_lock, "tod2rl", MTX_DEF);
   80 
   81 /* XXX: should be kern. now, it's no longer machdep.  */
   82 static int disable_rtc_set;
   83 SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set, CTLFLAG_RW, &disable_rtc_set,
   84     0, "Disallow adjusting time-of-day clock");
   85 
   86 void
   87 clock_register(device_t dev, long res)  /* res has units of microseconds */
   88 {
   89 
   90         if (clock_dev != NULL) {
   91                 if (clock_res <= res) {
   92                         if (bootverbose)
   93                                 device_printf(dev, "not installed as "
   94                                     "time-of-day clock: clock %s has higher "
   95                                     "resolution\n", device_get_name(clock_dev));
   96                         return;
   97                 }
   98                 if (bootverbose)
   99                         device_printf(clock_dev, "removed as "
  100                             "time-of-day clock: clock %s has higher "
  101                             "resolution\n", device_get_name(dev));
  102         }
  103         clock_dev = dev;
  104         clock_res = res;
  105         clock_adj.tv_sec = res / 2 / 1000000;
  106         clock_adj.tv_nsec = res / 2 % 1000000 * 1000;
  107         if (bootverbose)
  108                 device_printf(dev, "registered as a time-of-day clock "
  109                     "(resolution %ldus, adjustment %jd.%09jds)\n", res,
  110                     (intmax_t)clock_adj.tv_sec, (intmax_t)clock_adj.tv_nsec);
  111 }
  112 
  113 /*
  114  * inittodr and settodr derived from the i386 versions written
  115  * by Christoph Robitschko <chmr@edvz.tu-graz.ac.at>,  reintroduced and
  116  * updated by Chris Stenton <chris@gnome.co.uk> 8/10/94
  117  */
  118 
  119 /*
  120  * Initialize the time of day register, based on the time base which is, e.g.
  121  * from a filesystem.
  122  */
  123 void
  124 inittodr(time_t base)
  125 {
  126         struct timespec ts;
  127         int error;
  128 
  129         if (clock_dev == NULL) {
  130                 printf("warning: no time-of-day clock registered, system time "
  131                     "will not be set accurately\n");
  132                 goto wrong_time;
  133         }
  134         /* XXX: We should poll all registered RTCs in case of failure */
  135         mtx_lock(&resettodr_lock);
  136         error = CLOCK_GETTIME(clock_dev, &ts);
  137         mtx_unlock(&resettodr_lock);
  138         if (error != 0 && error != EINVAL) {
  139                 printf("warning: clock_gettime failed (%d), the system time "
  140                     "will not be set accurately\n", error);
  141                 goto wrong_time;
  142         }
  143         if (error == EINVAL || ts.tv_sec < 0) {
  144                 printf("Invalid time in real time clock.\n"
  145                     "Check and reset the date immediately!\n");
  146                 goto wrong_time;
  147         }
  148 
  149         ts.tv_sec += utc_offset();
  150         timespecadd(&ts, &clock_adj);
  151         tc_setclock(&ts);
  152 #ifdef FFCLOCK
  153         ffclock_reset_clock(&ts);
  154 #endif
  155         return;
  156 
  157 wrong_time:
  158         if (base > 0) {
  159                 ts.tv_sec = base;
  160                 ts.tv_nsec = 0;
  161                 tc_setclock(&ts);
  162         }
  163 }
  164 
  165 /*
  166  * Write system time back to RTC
  167  */
  168 void
  169 resettodr(void)
  170 {
  171         struct timespec ts;
  172         int error;
  173 
  174         if (disable_rtc_set || clock_dev == NULL)
  175                 return;
  176 
  177         getnanotime(&ts);
  178         timespecadd(&ts, &clock_adj);
  179         ts.tv_sec -= utc_offset();
  180         /* XXX: We should really set all registered RTCs */
  181         mtx_lock(&resettodr_lock);
  182         error = CLOCK_SETTIME(clock_dev, &ts);
  183         mtx_unlock(&resettodr_lock);
  184         if (error != 0)
  185                 printf("warning: clock_settime failed (%d), time-of-day clock "
  186                     "not adjusted to system time\n", error);
  187 }

Cache object: 81c4610a93d05eecd86993e6769b6b38


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