arch/m68knommu/kernel/time.c

   1 /*
   2  *  linux/arch/m68knommu/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>
  14 #include <linux/errno.h>
  15 #include <linux/module.h>
  16 #include <linux/sched.h>
  17 #include <linux/kernel.h>
  18 #include <linux/param.h>
  19 #include <linux/string.h>
  20 #include <linux/mm.h>
  21 #include <linux/profile.h>
  22 #include <linux/time.h>
  23 #include <linux/timex.h>
  24
  25 #include <asm/machdep.h>
  26 #include <asm/io.h>
  27
  28 #define TICK_SIZE (tick_nsec / 1000)
  29
  30 u64 jiffies_64 = INITIAL_JIFFIES;
  31
  32 EXPORT_SYMBOL(jiffies_64);
  33
  34 extern unsigned long wall_jiffies;
  35
  36
  37 static inline int set_rtc_mmss(unsigned long nowtime)
  38 {
  39         if (mach_set_clock_mmss)
  40                 return mach_set_clock_mmss (nowtime);
  41         return -1;
  42 }
  43
  44 /*
  45  * timer_interrupt() needs to keep up the real-time clock,
  46  * as well as call the "do_timer()" routine every clocktick
  47  */
  48 static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
  49 {
  50         /* last time the cmos clock got updated */
  51         static long last_rtc_update=0;
  52
  53         /* may need to kick the hardware timer */
  54         if (mach_tick)
  55           mach_tick();
  56
  57         write_seqlock(&xtime_lock);
  58
  59         do_timer(regs);
  60         if (current->pid)
  61                 profile_tick(CPU_PROFILING, regs);
  62
  63         /*
  64          * If we have an externally synchronized Linux clock, then update
  65          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  66          * called as close as possible to 500 ms before the new second starts.
  67          */
  68         if ((time_status & STA_UNSYNC) == 0 &&
  69             xtime.tv_sec > last_rtc_update + 660 &&
  70             (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
  71             (xtime.tv_nsec  / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
  72           if (set_rtc_mmss(xtime.tv_sec) == 0)
  73             last_rtc_update = xtime.tv_sec;
  74           else
  75             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  76         }
  77 #ifdef CONFIG_HEARTBEAT
  78         /* use power LED as a heartbeat instead -- much more useful
  79            for debugging -- based on the version for PReP by Cort */
  80         /* acts like an actual heart beat -- ie thump-thump-pause... */
  81         if (mach_heartbeat) {
  82             static unsigned cnt = 0, period = 0, dist = 0;
  83
  84             if (cnt == 0 || cnt == dist)
  85                 mach_heartbeat( 1 );
  86             else if (cnt == 7 || cnt == dist+7)
  87                 mach_heartbeat( 0 );
  88
  89             if (++cnt > period) {
  90                 cnt = 0;
  91                 /* The hyperbolic function below modifies the heartbeat period
  92                  * length in dependency of the current (5min) load. It goes
  93                  * through the points f(0)=126, f(1)=86, f(5)=51,
  94                  * f(inf)->30. */
  95                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  96                 dist = period / 4;
  97             }
  98         }
  99 #endif /* CONFIG_HEARTBEAT */
 100
 101         write_sequnlock(&xtime_lock);
 102         return(IRQ_HANDLED);
 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_nsec = 0;
 118         wall_to_monotonic.tv_sec = -xtime.tv_sec;
 119
 120         mach_sched_init(timer_interrupt);
 121 }
 122
 123 /*
 124  * This version of gettimeofday has near microsecond resolution.
 125  */
 126 void do_gettimeofday(struct timeval *tv)
 127 {
 128         unsigned long flags;
 129         unsigned long lost, seq;
 130         unsigned long usec, sec;
 131
 132         do {
 133                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 134                 usec = mach_gettimeoffset ? mach_gettimeoffset() : 0;
 135                 lost = jiffies - wall_jiffies;
 136                 if (lost)
 137                         usec += lost * (1000000 / HZ);
 138                 sec = xtime.tv_sec;
 139                 usec += (xtime.tv_nsec / 1000);
 140         } while (read_seqretry_irqrestore(&xtime_lock, seq, 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 EXPORT_SYMBOL(do_gettimeofday);
 152
 153 int do_settimeofday(struct timespec *tv)
 154 {
 155         time_t wtm_sec, sec = tv->tv_sec;
 156         long wtm_nsec, nsec = tv->tv_nsec;
 157
 158         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 159                 return -EINVAL;
 160
 161         write_seqlock_irq(&xtime_lock);
 162         /*
 163          * This is revolting. We need to set the xtime.tv_usec
 164          * correctly. However, the value in this location is
 165          * is value at the last tick.
 166          * Discover what correction gettimeofday
 167          * would have done, and then undo it!
 168          */
 169         if (mach_gettimeoffset)
 170                 nsec -= (mach_gettimeoffset() * 1000);
 171
 172         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 173         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 174
 175         set_normalized_timespec(&xtime, sec, nsec);
 176         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 177
 178         time_adjust = 0;                /* stop active adjtime() */
 179         time_status |= STA_UNSYNC;
 180         time_maxerror = NTP_PHASE_LIMIT;
 181         time_esterror = NTP_PHASE_LIMIT;
 182         write_sequnlock_irq(&xtime_lock);
 183         clock_was_set();
 184         return 0;
 185 }
 186
 187 /*
 188  * Scheduler clock - returns current time in nanosec units.
 189  */
 190 unsigned long long sched_clock(void)
 191 {
 192         return (unsigned long long)jiffies * (1000000000 / HZ);
 193 }
 194
 195 EXPORT_SYMBOL(do_settimeofday);