arch/m68k/kernel/time.c

/* */
This source file includes following definitions.
set_rtc_mmss
timer_interrupt
mktime
time_init
do_gettimeofday
do_settimeofday
   1 /*
   2  *  linux/arch/m68k/kernel/time.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5  *
   6  * This file contains the m68k-specific time handling details.
   7  * Most of the stuff is located in the machine specific files.
   8  */
   9 
  10 #include <linux/errno.h>
  11 #include <linux/sched.h>
  12 #include <linux/kernel.h>
  13 #include <linux/param.h>
  14 #include <linux/string.h>
  15 #include <linux/mm.h>
  16 
  17 #include <asm/machdep.h>
  18 #include <asm/segment.h>
  19 #include <asm/io.h>
  20 
  21 #include <linux/timex.h>
  22 
  23 
  24 static inline int set_rtc_mmss(unsigned long nowtime)
     /*  */
  25 {
  26   if (mach_set_clock_mmss)
  27     return mach_set_clock_mmss (nowtime);
  28   return -1;
  29 }
  30 
  31 /*
  32  * timer_interrupt() needs to keep up the real-time clock,
  33  * as well as call the "do_timer()" routine every clocktick
  34  */
  35 static void timer_interrupt(int irq, struct pt_regs * regs, void *dummy)
     /*  */
  36 {
  37         /* last time the cmos clock got updated */
  38         static long last_rtc_update=0;
  39 
  40         do_timer(regs);
  41 
  42         /*
  43          * If we have an externally synchronized Linux clock, then update
  44          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  45          * called as close as possible to 500 ms before the new second starts.
  46          */
  47         if (time_state != TIME_BAD && xtime.tv_sec > last_rtc_update + 660 &&
  48             xtime.tv_usec > 500000 - (tick >> 1) &&
  49             xtime.tv_usec < 500000 + (tick >> 1))
  50           if (set_rtc_mmss(xtime.tv_sec) == 0)
  51             last_rtc_update = xtime.tv_sec;
  52           else
  53             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  54 }
  55 
  56 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
  57  * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
  58  * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
  59  *
  60  * [For the Julian calendar (which was used in Russia before 1917,
  61  * Britain & colonies before 1752, anywhere else before 1582,
  62  * and is still in use by some communities) leave out the
  63  * -year/100+year/400 terms, and add 10.]
  64  *
  65  * This algorithm was first published by Gauss (I think).
  66  *
  67  * WARNING: this function will overflow on 2106-02-07 06:28:16 on
  68  * machines were long is 32-bit! (However, as time_t is signed, we
  69  * will already get problems at other places on 2038-01-19 03:14:08)
  70  */
  71 static inline unsigned long mktime(unsigned int year, unsigned int mon,
     /*  */
  72         unsigned int day, unsigned int hour,
  73         unsigned int min, unsigned int sec)
  74 {
  75         if (0 >= (int) (mon -= 2)) {    /* 1..12 -> 11,12,1..10 */
  76                 mon += 12;      /* Puts Feb last since it has leap day */
  77                 year -= 1;
  78         }
  79         return (((
  80             (unsigned long)(year/4 - year/100 + year/400 + 367*mon/12 + day) +
  81               year*365 - 719499
  82             )*24 + hour /* now have hours */
  83            )*60 + min /* now have minutes */
  84           )*60 + sec; /* finally seconds */
  85 }
  86 
  87 void time_init(void)
     /*  */
  88 {
  89         unsigned int year, mon, day, hour, min, sec;
  90 
  91         extern void arch_gettod(int *year, int *mon, int *day, int *hour,
  92                                 int *min, int *sec);
  93 
  94         arch_gettod (&year, &mon, &day, &hour, &min, &sec);
  95 
  96         if ((year += 1900) < 1970)
  97                 year += 100;
  98         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
  99         xtime.tv_usec = 0;
 100 
 101         mach_sched_init(timer_interrupt);
 102 }
 103 
 104 /*
 105  * This version of gettimeofday has near microsecond resolution.
 106  */
 107 void do_gettimeofday(struct timeval *tv)
     /*  */
 108 {
 109         unsigned long flags;
 110 
 111         save_flags(flags);
 112         cli();
 113         *tv = xtime;
 114         tv->tv_usec += mach_gettimeoffset();
 115         if (tv->tv_usec >= 1000000) {
 116                 tv->tv_usec -= 1000000;
 117                 tv->tv_sec++;
 118         }
 119         restore_flags(flags);
 120 }
 121 
 122 void do_settimeofday(struct timeval *tv)
     /*  */
 123 {
 124         cli();
 125         /* This is revolting. We need to set the xtime.tv_usec
 126          * correctly. However, the value in this location is
 127          * is value at the last tick.
 128          * Discover what correction gettimeofday
 129          * would have done, and then undo it!
 130          */
 131         tv->tv_usec -= mach_gettimeoffset();
 132 
 133         if (tv->tv_usec < 0) {
 134                 tv->tv_usec += 1000000;
 135                 tv->tv_sec--;
 136         }
 137 
 138         xtime = *tv;
 139         time_state = TIME_BAD;
 140         time_maxerror = 0x70000000;
 141         time_esterror = 0x70000000;
 142         sti();
 143 }
/* */
root/arch/m68k/kernel/time.c

DEFINITIONS
