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/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/rtc.h>
  21
  22 #include <asm/machdep.h>
  23 #include <asm/io.h>
  24 #include <asm/irq_regs.h>
  25
  26 #include <linux/time.h>
  27 #include <linux/timex.h>
  28 #include <linux/profile.h>
  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)
  42 {
  43         do_timer(1);
  44 #ifndef CONFIG_SMP
  45         update_process_times(user_mode(get_irq_regs()));
  46 #endif
  47         profile_tick(CPU_PROFILING);
  48
  49 #ifdef CONFIG_HEARTBEAT
  50         /* use power LED as a heartbeat instead -- much more useful
  51            for debugging -- based on the version for PReP by Cort */
  52         /* acts like an actual heart beat -- ie thump-thump-pause... */
  53         if (mach_heartbeat) {
  54             static unsigned cnt = 0, period = 0, dist = 0;
  55
  56             if (cnt == 0 || cnt == dist)
  57                 mach_heartbeat( 1 );
  58             else if (cnt == 7 || cnt == dist+7)
  59                 mach_heartbeat( 0 );
  60
  61             if (++cnt > period) {
  62                 cnt = 0;
  63                 /* The hyperbolic function below modifies the heartbeat period
  64                  * length in dependency of the current (5min) load. It goes
  65                  * through the points f(0)=126, f(1)=86, f(5)=51,
  66                  * f(inf)->30. */
  67                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  68                 dist = period / 4;
  69             }
  70         }
  71 #endif /* CONFIG_HEARTBEAT */
  72         return IRQ_HANDLED;
  73 }
  74
  75 void time_init(void)
  76 {
  77         struct rtc_time time;
  78
  79         if (mach_hwclk) {
  80                 mach_hwclk(0, &time);
  81
  82                 if ((time.tm_year += 1900) < 1970)
  83                         time.tm_year += 100;
  84                 xtime.tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday,
  85                                       time.tm_hour, time.tm_min, time.tm_sec);
  86                 xtime.tv_nsec = 0;
  87         }
  88         wall_to_monotonic.tv_sec = -xtime.tv_sec;
  89
  90         mach_sched_init(timer_interrupt);
  91 }
  92
  93 /*
  94  * This version of gettimeofday has near microsecond resolution.
  95  */
  96 void do_gettimeofday(struct timeval *tv)
  97 {
  98         unsigned long flags;
  99         unsigned long seq;
 100         unsigned long usec, sec;
 101         unsigned long max_ntp_tick = tick_usec - tickadj;
 102
 103         do {
 104                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 105
 106                 usec = mach_gettimeoffset();
 107
 108                 /*
 109                  * If time_adjust is negative then NTP is slowing the clock
 110                  * so make sure not to go into next possible interval.
 111                  * Better to lose some accuracy than have time go backwards..
 112                  */
 113                 if (unlikely(time_adjust < 0))
 114                         usec = min(usec, max_ntp_tick);
 115
 116                 sec = xtime.tv_sec;
 117                 usec += xtime.tv_nsec/1000;
 118         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 119
 120
 121         while (usec >= 1000000) {
 122                 usec -= 1000000;
 123                 sec++;
 124         }
 125
 126         tv->tv_sec = sec;
 127         tv->tv_usec = usec;
 128 }
 129
 130 EXPORT_SYMBOL(do_gettimeofday);
 131
 132 int do_settimeofday(struct timespec *tv)
 133 {
 134         time_t wtm_sec, sec = tv->tv_sec;
 135         long wtm_nsec, nsec = tv->tv_nsec;
 136
 137         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 138                 return -EINVAL;
 139
 140         write_seqlock_irq(&xtime_lock);
 141         /* This is revolting. We need to set the xtime.tv_nsec
 142          * correctly. However, the value in this location is
 143          * is value at the last tick.
 144          * Discover what correction gettimeofday
 145          * would have done, and then undo it!
 146          */
 147         nsec -= 1000 * mach_gettimeoffset();
 148
 149         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 150         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 151
 152         set_normalized_timespec(&xtime, sec, nsec);
 153         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 154
 155         ntp_clear();
 156         write_sequnlock_irq(&xtime_lock);
 157         clock_was_set();
 158         return 0;
 159 }
 160
 161 EXPORT_SYMBOL(do_settimeofday);