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

     /*-
      * Copyright (c) 1988 University of Utah.
      * Copyright (c) 1982, 1990, 1993
      *      The Regents of the University of California.
      * Copyright (c) 2011 The FreeBSD Foundation
      * All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * the Systems Programming Group of the University of Utah Computer
     * Science Department.
     *
     * Portions of this software were developed by Julien Ridoux at the University
     * of Melbourne under sponsorship from the FreeBSD Foundation.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      from: Utah $Hdr: clock.c 1.18 91/01/21$
     *      from: @(#)clock.c       8.2 (Berkeley) 1/12/94
     *      from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
     *      and
     *      from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
     */
    
    /*
     * Helpers for time-of-day clocks. This is useful for architectures that need
     * support multiple models of such clocks, and generally serves to make the
     * code more machine-independent.
     * If the clock in question can also be used as a time counter, the driver
     * needs to initiate this.
     * This code is not yet used by all architectures.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/10.1/sys/kern/subr_rtc.c 227723 2011-11-19 14:10:16Z lstewart $");
    
    #include "opt_ffclock.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/bus.h>
    #include <sys/clock.h>
    #include <sys/sysctl.h>
    #ifdef FFCLOCK
    #include <sys/timeffc.h>
    #endif
    #include <sys/timetc.h>
    
    #include "clock_if.h"
    
    static device_t clock_dev = NULL;
    static long clock_res;
    static struct timespec clock_adj;
    
    /* XXX: should be kern. now, it's no longer machdep.  */
    static int disable_rtc_set;
    SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set, CTLFLAG_RW, &disable_rtc_set,
        0, "Disallow adjusting time-of-day clock");
    
    void
    clock_register(device_t dev, long res)  /* res has units of microseconds */
    {
    
            if (clock_dev != NULL) {
                    if (clock_res > res) {
                            if (bootverbose)
                                    device_printf(dev, "not installed as "
                                        "time-of-day clock: clock %s has higher "
                                        "resolution\n", device_get_name(clock_dev));
                            return;
                    }
                    if (bootverbose)
                            device_printf(clock_dev, "removed as "
                                "time-of-day clock: clock %s has higher "
                                "resolution\n", device_get_name(dev));
            }
            clock_dev = dev;
           clock_res = res;
           clock_adj.tv_sec = res / 2 / 1000000;
           clock_adj.tv_nsec = res / 2 % 1000000 * 1000;
           if (bootverbose)
                   device_printf(dev, "registered as a time-of-day clock "
                       "(resolution %ldus, adjustment %jd.%09jds)\n", res,
                       (intmax_t)clock_adj.tv_sec, (intmax_t)clock_adj.tv_nsec);
   }
   
   /*
    * inittodr and settodr derived from the i386 versions written
    * by Christoph Robitschko <chmr@edvz.tu-graz.ac.at>,  reintroduced and
    * updated by Chris Stenton <chris@gnome.co.uk> 8/10/94
    */
   
   /*
    * Initialize the time of day register, based on the time base which is, e.g.
    * from a filesystem.
    */
   void
   inittodr(time_t base)
   {
           struct timespec ts;
           int error;
   
           if (clock_dev == NULL) {
                   printf("warning: no time-of-day clock registered, system time "
                       "will not be set accurately\n");
                   goto wrong_time;
           }
           /* XXX: We should poll all registered RTCs in case of failure */
           error = CLOCK_GETTIME(clock_dev, &ts);
           if (error != 0 && error != EINVAL) {
                   printf("warning: clock_gettime failed (%d), the system time "
                       "will not be set accurately\n", error);
                   goto wrong_time;
           }
           if (error == EINVAL || ts.tv_sec < 0) {
                   printf("Invalid time in real time clock.\n"
                       "Check and reset the date immediately!\n");
                   goto wrong_time;
           }
   
           ts.tv_sec += utc_offset();
           timespecadd(&ts, &clock_adj);
           tc_setclock(&ts);
   #ifdef FFCLOCK
           ffclock_reset_clock(&ts);
   #endif
           return;
   
   wrong_time:
           if (base > 0) {
                   ts.tv_sec = base;
                   ts.tv_nsec = 0;
                   tc_setclock(&ts);
           }
   }
   
   /*
    * Write system time back to RTC
    */
   void
   resettodr(void)
   {
           struct timespec ts;
           int error;
   
           if (disable_rtc_set || clock_dev == NULL)
                   return;
   
           getnanotime(&ts);
           timespecadd(&ts, &clock_adj);
           ts.tv_sec -= utc_offset();
           /* XXX: We should really set all registered RTCs */
           if ((error = CLOCK_SETTIME(clock_dev, &ts)) != 0)
                   printf("warning: clock_settime failed (%d), time-of-day clock "
                       "not adjusted to system time\n", error);
   }

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