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