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 extern unsigned long wall_jiffies;
  30
  31
  32 static inline int set_rtc_mmss(unsigned long nowtime)
  33 {
  34         if (mach_set_clock_mmss)
  35                 return mach_set_clock_mmss (nowtime);
  36         return -1;
  37 }
  38
  39 /*
  40  * timer_interrupt() needs to keep up the real-time clock,
  41  * as well as call the "do_timer()" routine every clocktick
  42  */
  43 static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
  44 {
  45         /* last time the cmos clock got updated */
  46         static long last_rtc_update=0;
  47
  48         /* may need to kick the hardware timer */
  49         if (mach_tick)
  50           mach_tick();
  51
  52         write_seqlock(&xtime_lock);
  53
  54         do_timer(regs);
  55 #ifndef CONFIG_SMP
  56         update_process_times(user_mode(regs));
  57 #endif
  58         if (current->pid)
  59                 profile_tick(CPU_PROFILING, regs);
  60
  61         /*
  62          * If we have an externally synchronized Linux clock, then update
  63          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  64          * called as close as possible to 500 ms before the new second starts.
  65          */
  66         if (ntp_synced() &&
  67             xtime.tv_sec > last_rtc_update + 660 &&
  68             (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
  69             (xtime.tv_nsec  / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
  70           if (set_rtc_mmss(xtime.tv_sec) == 0)
  71             last_rtc_update = xtime.tv_sec;
  72           else
  73             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  74         }
  75 #ifdef CONFIG_HEARTBEAT
  76         /* use power LED as a heartbeat instead -- much more useful
  77            for debugging -- based on the version for PReP by Cort */
  78         /* acts like an actual heart beat -- ie thump-thump-pause... */
  79         if (mach_heartbeat) {
  80             static unsigned cnt = 0, period = 0, dist = 0;
  81
  82             if (cnt == 0 || cnt == dist)
  83                 mach_heartbeat( 1 );
  84             else if (cnt == 7 || cnt == dist+7)
  85                 mach_heartbeat( 0 );
  86
  87             if (++cnt > period) {
  88                 cnt = 0;
  89                 /* The hyperbolic function below modifies the heartbeat period
  90                  * length in dependency of the current (5min) load. It goes
  91                  * through the points f(0)=126, f(1)=86, f(5)=51,
  92                  * f(inf)->30. */
  93                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  94                 dist = period / 4;
  95             }
  96         }
  97 #endif /* CONFIG_HEARTBEAT */
  98
  99         write_sequnlock(&xtime_lock);
 100         return(IRQ_HANDLED);
 101 }
 102
 103 void time_init(void)
 104 {
 105         unsigned int year, mon, day, hour, min, sec;
 106
 107         extern void arch_gettod(int *year, int *mon, int *day, int *hour,
 108                                 int *min, int *sec);
 109
 110         arch_gettod(&year, &mon, &day, &hour, &min, &sec);
 111
 112         if ((year += 1900) < 1970)
 113                 year += 100;
 114         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
 115         xtime.tv_nsec = 0;
 116         wall_to_monotonic.tv_sec = -xtime.tv_sec;
 117
 118         mach_sched_init(timer_interrupt);
 119 }
 120
 121 /*
 122  * This version of gettimeofday has near microsecond resolution.
 123  */
 124 void do_gettimeofday(struct timeval *tv)
 125 {
 126         unsigned long flags;
 127         unsigned long lost, seq;
 128         unsigned long usec, sec;
 129
 130         do {
 131                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 132                 usec = mach_gettimeoffset ? mach_gettimeoffset() : 0;
 133                 lost = jiffies - wall_jiffies;
 134                 if (lost)
 135                         usec += lost * (1000000 / HZ);
 136                 sec = xtime.tv_sec;
 137                 usec += (xtime.tv_nsec / 1000);
 138         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 139
 140         while (usec >= 1000000) {
 141                 usec -= 1000000;
 142                 sec++;
 143         }
 144
 145         tv->tv_sec = sec;
 146         tv->tv_usec = usec;
 147 }
 148
 149 EXPORT_SYMBOL(do_gettimeofday);
 150
 151 int do_settimeofday(struct timespec *tv)
 152 {
 153         time_t wtm_sec, sec = tv->tv_sec;
 154         long wtm_nsec, nsec = tv->tv_nsec;
 155
 156         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 157                 return -EINVAL;
 158
 159         write_seqlock_irq(&xtime_lock);
 160         /*
 161          * This is revolting. We need to set the xtime.tv_usec
 162          * correctly. However, the value in this location is
 163          * is value at the last tick.
 164          * Discover what correction gettimeofday
 165          * would have done, and then undo it!
 166          */
 167         if (mach_gettimeoffset)
 168                 nsec -= (mach_gettimeoffset() * 1000);
 169
 170         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 171         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 172
 173         set_normalized_timespec(&xtime, sec, nsec);
 174         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 175
 176         ntp_clear();
 177         write_sequnlock_irq(&xtime_lock);
 178         clock_was_set();
 179         return 0;
 180 }
 181
 182 /*
 183  * Scheduler clock - returns current time in nanosec units.
 184  */
 185 unsigned long long sched_clock(void)
 186 {
 187         return (unsigned long long)jiffies * (1000000000 / HZ);
 188 }
 189
 190 EXPORT_SYMBOL(do_settimeofday);