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/errno.h>
  14 #include <linux/module.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 #include <linux/profile.h>
  21 #include <linux/time.h>
  22 #include <linux/timex.h>
  23
  24 #include <asm/machdep.h>
  25 #include <asm/io.h>
  26
  27 #define TICK_SIZE (tick_nsec / 1000)
  28
  29
  30 static inline int set_rtc_mmss(unsigned long nowtime)
  31 {
  32         if (mach_set_clock_mmss)
  33                 return mach_set_clock_mmss (nowtime);
  34         return -1;
  35 }
  36
  37 /*
  38  * timer_interrupt() needs to keep up the real-time clock,
  39  * as well as call the "do_timer()" routine every clocktick
  40  */
  41 static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
  42 {
  43         /* last time the cmos clock got updated */
  44         static long last_rtc_update=0;
  45
  46         /* may need to kick the hardware timer */
  47         if (mach_tick)
  48           mach_tick();
  49
  50         write_seqlock(&xtime_lock);
  51
  52         do_timer(1);
  53 #ifndef CONFIG_SMP
  54         update_process_times(user_mode(regs));
  55 #endif
  56         if (current->pid)
  57                 profile_tick(CPU_PROFILING, regs);
  58
  59         /*
  60          * If we have an externally synchronized Linux clock, then update
  61          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  62          * called as close as possible to 500 ms before the new second starts.
  63          */
  64         if (ntp_synced() &&
  65             xtime.tv_sec > last_rtc_update + 660 &&
  66             (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
  67             (xtime.tv_nsec  / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
  68           if (set_rtc_mmss(xtime.tv_sec) == 0)
  69             last_rtc_update = xtime.tv_sec;
  70           else
  71             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  72         }
  73 #ifdef CONFIG_HEARTBEAT
  74         /* use power LED as a heartbeat instead -- much more useful
  75            for debugging -- based on the version for PReP by Cort */
  76         /* acts like an actual heart beat -- ie thump-thump-pause... */
  77         if (mach_heartbeat) {
  78             static unsigned cnt = 0, period = 0, dist = 0;
  79
  80             if (cnt == 0 || cnt == dist)
  81                 mach_heartbeat( 1 );
  82             else if (cnt == 7 || cnt == dist+7)
  83                 mach_heartbeat( 0 );
  84
  85             if (++cnt > period) {
  86                 cnt = 0;
  87                 /* The hyperbolic function below modifies the heartbeat period
  88                  * length in dependency of the current (5min) load. It goes
  89                  * through the points f(0)=126, f(1)=86, f(5)=51,
  90                  * f(inf)->30. */
  91                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  92                 dist = period / 4;
  93             }
  94         }
  95 #endif /* CONFIG_HEARTBEAT */
  96
  97         write_sequnlock(&xtime_lock);
  98         return(IRQ_HANDLED);
  99 }
 100
 101 void time_init(void)
 102 {
 103         unsigned int year, mon, day, hour, min, sec;
 104
 105         extern void arch_gettod(int *year, int *mon, int *day, int *hour,
 106                                 int *min, int *sec);
 107
 108         arch_gettod(&year, &mon, &day, &hour, &min, &sec);
 109
 110         if ((year += 1900) < 1970)
 111                 year += 100;
 112         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
 113         xtime.tv_nsec = 0;
 114         wall_to_monotonic.tv_sec = -xtime.tv_sec;
 115
 116         mach_sched_init(timer_interrupt);
 117 }
 118
 119 /*
 120  * This version of gettimeofday has near microsecond resolution.
 121  */
 122 void do_gettimeofday(struct timeval *tv)
 123 {
 124         unsigned long flags;
 125         unsigned long seq;
 126         unsigned long usec, sec;
 127
 128         do {
 129                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 130                 usec = mach_gettimeoffset ? mach_gettimeoffset() : 0;
 131                 sec = xtime.tv_sec;
 132                 usec += (xtime.tv_nsec / 1000);
 133         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 134
 135         while (usec >= 1000000) {
 136                 usec -= 1000000;
 137                 sec++;
 138         }
 139
 140         tv->tv_sec = sec;
 141         tv->tv_usec = usec;
 142 }
 143
 144 EXPORT_SYMBOL(do_gettimeofday);
 145
 146 int do_settimeofday(struct timespec *tv)
 147 {
 148         time_t wtm_sec, sec = tv->tv_sec;
 149         long wtm_nsec, nsec = tv->tv_nsec;
 150
 151         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 152                 return -EINVAL;
 153
 154         write_seqlock_irq(&xtime_lock);
 155         /*
 156          * This is revolting. We need to set the xtime.tv_usec
 157          * correctly. However, the value in this location is
 158          * is value at the last tick.
 159          * Discover what correction gettimeofday
 160          * would have done, and then undo it!
 161          */
 162         if (mach_gettimeoffset)
 163                 nsec -= (mach_gettimeoffset() * 1000);
 164
 165         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 166         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 167
 168         set_normalized_timespec(&xtime, sec, nsec);
 169         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 170
 171         ntp_clear();
 172         write_sequnlock_irq(&xtime_lock);
 173         clock_was_set();
 174         return 0;
 175 }
 176
 177 /*
 178  * Scheduler clock - returns current time in nanosec units.
 179  */
 180 unsigned long long sched_clock(void)
 181 {
 182         return (unsigned long long)jiffies * (1000000000 / HZ);
 183 }
 184
 185 EXPORT_SYMBOL(do_settimeofday);