arch/m68k/kernel/time.c

   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  * 1997-09-10   Updated NTP code according to technical memorandum Jan '96
  10  *              "A Kernel Model for Precision Timekeeping" by Dave Mills
  11  */
  12
  13 #include <linux/config.h> /* CONFIG_HEARTBEAT */
  14 #include <linux/errno.h>
  15 #include <linux/sched.h>
  16 #include <linux/kernel.h>
  17 #include <linux/param.h>
  18 #include <linux/string.h>
  19 #include <linux/mm.h>
  20
  21 #include <asm/machdep.h>
  22 #include <asm/io.h>
  23
  24 #include <linux/timex.h>
  25
  26
  27 static inline int set_rtc_mmss(unsigned long nowtime)
  28 {
  29   if (mach_set_clock_mmss)
  30     return mach_set_clock_mmss (nowtime);
  31   return -1;
  32 }
  33
  34 static inline void do_profile (unsigned long pc)
  35 {
  36         if (prof_buffer && current->pid) {
  37                 extern int _stext;
  38                 pc -= (unsigned long) &_stext;
  39                 pc >>= prof_shift;
  40                 if (pc < prof_len)
  41                         ++prof_buffer[pc];
  42                 else
  43                 /*
  44                  * Don't ignore out-of-bounds PC values silently,
  45                  * put them into the last histogram slot, so if
  46                  * present, they will show up as a sharp peak.
  47                  */
  48                         ++prof_buffer[prof_len-1];
  49         }
  50 }
  51
  52 /*
  53  * timer_interrupt() needs to keep up the real-time clock,
  54  * as well as call the "do_timer()" routine every clocktick
  55  */
  56 static void timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
  57 {
  58         /* last time the cmos clock got updated */
  59         static long last_rtc_update=0;
  60
  61         do_timer(regs);
  62
  63         if (!user_mode(regs))
  64                 do_profile(regs->pc);
  65
  66         /*
  67          * If we have an externally synchronized Linux clock, then update
  68          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  69          * called as close as possible to 500 ms before the new second starts.
  70          */
  71         if ((time_status & STA_UNSYNC) == 0 &&
  72             xtime.tv_sec > last_rtc_update + 660 &&
  73             xtime.tv_usec >= 500000 - ((unsigned) tick) / 2 &&
  74             xtime.tv_usec <= 500000 + ((unsigned) tick) / 2) {
  75           if (set_rtc_mmss(xtime.tv_sec) == 0)
  76             last_rtc_update = xtime.tv_sec;
  77           else
  78             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  79         }
  80 #ifdef CONFIG_HEARTBEAT
  81         /* use power LED as a heartbeat instead -- much more useful
  82            for debugging -- based on the version for PReP by Cort */
  83         /* acts like an actual heart beat -- ie thump-thump-pause... */
  84         if (mach_heartbeat) {
  85             static unsigned cnt = 0, period = 0, dist = 0;
  86
  87             if (cnt == 0 || cnt == dist)
  88                 mach_heartbeat( 1 );
  89             else if (cnt == 7 || cnt == dist+7)
  90                 mach_heartbeat( 0 );
  91
  92             if (++cnt > period) {
  93                 cnt = 0;
  94                 /* The hyperbolic function below modifies the heartbeat period
  95                  * length in dependency of the current (5min) load. It goes
  96                  * through the points f(0)=126, f(1)=86, f(5)=51,
  97                  * f(inf)->30. */
  98                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  99                 dist = period / 4;
 100             }
 101         }
 102 #endif /* CONFIG_HEARTBEAT */
 103 }
 104
 105 void time_init(void)
 106 {
 107         unsigned int year, mon, day, hour, min, sec;
 108
 109         extern void arch_gettod(int *year, int *mon, int *day, int *hour,
 110                                 int *min, int *sec);
 111
 112         arch_gettod (&year, &mon, &day, &hour, &min, &sec);
 113
 114         if ((year += 1900) < 1970)
 115                 year += 100;
 116         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
 117         xtime.tv_usec = 0;
 118
 119         mach_sched_init(timer_interrupt);
 120 }
 121
 122 extern rwlock_t xtime_lock;
 123
 124 /*
 125  * This version of gettimeofday has near microsecond resolution.
 126  */
 127 void do_gettimeofday(struct timeval *tv)
 128 {
 129         extern volatile unsigned long lost_ticks;
 130         unsigned long flags;
 131         unsigned long usec, sec, lost;
 132
 133         read_lock_irqsave(&xtime_lock, flags);
 134         usec = mach_gettimeoffset();
 135         lost = lost_ticks;
 136         if (lost)
 137                 usec += lost * (1000000/HZ);
 138         sec = xtime.tv_sec;
 139         usec += xtime.tv_usec;
 140         read_unlock_irqrestore(&xtime_lock, flags);
 141
 142         while (usec >= 1000000) {
 143                 usec -= 1000000;
 144                 sec++;
 145         }
 146
 147         tv->tv_sec = sec;
 148         tv->tv_usec = usec;
 149 }
 150
 151 void do_settimeofday(struct timeval *tv)
 152 {
 153         write_lock_irq(&xtime_lock);
 154         /* This is revolting. We need to set the xtime.tv_usec
 155          * correctly. However, the value in this location is
 156          * is value at the last tick.
 157          * Discover what correction gettimeofday
 158          * would have done, and then undo it!
 159          */
 160         tv->tv_usec -= mach_gettimeoffset();
 161
 162         while (tv->tv_usec < 0) {
 163                 tv->tv_usec += 1000000;
 164                 tv->tv_sec--;
 165         }
 166
 167         xtime = *tv;
 168         time_adjust = 0;                /* stop active adjtime() */
 169         time_status |= STA_UNSYNC;
 170         time_maxerror = NTP_PHASE_LIMIT;
 171         time_esterror = NTP_PHASE_LIMIT;
 172         write_unlock_irq(&xtime_lock);
 173 }