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/config.h> /* CONFIG_HEARTBEAT */
  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/rtc.h>
  22
  23 #include <asm/machdep.h>
  24 #include <asm/io.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, struct pt_regs * regs)
  42 {
  43         do_timer(regs);
  44 #ifndef CONFIG_SMP
  45         update_process_times(user_mode(regs));
  46 #endif
  47         profile_tick(CPU_PROFILING, regs);
  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         extern unsigned long wall_jiffies;
 100         unsigned long seq;
 101         unsigned long usec, sec, lost;
 102         unsigned long max_ntp_tick = tick_usec - tickadj;
 103
 104         do {
 105                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 106
 107                 usec = mach_gettimeoffset();
 108                 lost = jiffies - wall_jiffies;
 109
 110                 /*
 111                  * If time_adjust is negative then NTP is slowing the clock
 112                  * so make sure not to go into next possible interval.
 113                  * Better to lose some accuracy than have time go backwards..
 114                  */
 115                 if (unlikely(time_adjust < 0)) {
 116                         usec = min(usec, max_ntp_tick);
 117
 118                         if (lost)
 119                                 usec += lost * max_ntp_tick;
 120                 }
 121                 else if (unlikely(lost))
 122                         usec += lost * tick_usec;
 123
 124                 sec = xtime.tv_sec;
 125                 usec += xtime.tv_nsec/1000;
 126         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 127
 128
 129         while (usec >= 1000000) {
 130                 usec -= 1000000;
 131                 sec++;
 132         }
 133
 134         tv->tv_sec = sec;
 135         tv->tv_usec = usec;
 136 }
 137
 138 EXPORT_SYMBOL(do_gettimeofday);
 139
 140 int do_settimeofday(struct timespec *tv)
 141 {
 142         time_t wtm_sec, sec = tv->tv_sec;
 143         long wtm_nsec, nsec = tv->tv_nsec;
 144         extern unsigned long wall_jiffies;
 145
 146         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 147                 return -EINVAL;
 148
 149         write_seqlock_irq(&xtime_lock);
 150         /* This is revolting. We need to set the xtime.tv_nsec
 151          * correctly. However, the value in this location is
 152          * is value at the last tick.
 153          * Discover what correction gettimeofday
 154          * would have done, and then undo it!
 155          */
 156         nsec -= 1000 * (mach_gettimeoffset() +
 157                         (jiffies - wall_jiffies) * (1000000 / HZ));
 158
 159         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 160         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 161
 162         set_normalized_timespec(&xtime, sec, nsec);
 163         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 164
 165         ntp_clear();
 166         write_sequnlock_irq(&xtime_lock);
 167         clock_was_set();
 168         return 0;
 169 }
 170
 171 EXPORT_SYMBOL(do_settimeofday);
 172
 173 /*
 174  * Scheduler clock - returns current time in ns units.
 175  */
 176 unsigned long long sched_clock(void)
 177 {
 178        return (unsigned long long)jiffies*(1000000000/HZ);
 179 }
 180