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 u64 jiffies_64 = INITIAL_JIFFIES;
  31
  32 EXPORT_SYMBOL(jiffies_64);
  33
  34 static inline int set_rtc_mmss(unsigned long nowtime)
  35 {
  36   if (mach_set_clock_mmss)
  37     return mach_set_clock_mmss (nowtime);
  38   return -1;
  39 }
  40
  41 /*
  42  * timer_interrupt() needs to keep up the real-time clock,
  43  * as well as call the "do_timer()" routine every clocktick
  44  */
  45 static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
  46 {
  47         do_timer(regs);
  48 #ifndef CONFIG_SMP
  49         update_process_times(user_mode(regs));
  50 #endif
  51         profile_tick(CPU_PROFILING, regs);
  52
  53 #ifdef CONFIG_HEARTBEAT
  54         /* use power LED as a heartbeat instead -- much more useful
  55            for debugging -- based on the version for PReP by Cort */
  56         /* acts like an actual heart beat -- ie thump-thump-pause... */
  57         if (mach_heartbeat) {
  58             static unsigned cnt = 0, period = 0, dist = 0;
  59
  60             if (cnt == 0 || cnt == dist)
  61                 mach_heartbeat( 1 );
  62             else if (cnt == 7 || cnt == dist+7)
  63                 mach_heartbeat( 0 );
  64
  65             if (++cnt > period) {
  66                 cnt = 0;
  67                 /* The hyperbolic function below modifies the heartbeat period
  68                  * length in dependency of the current (5min) load. It goes
  69                  * through the points f(0)=126, f(1)=86, f(5)=51,
  70                  * f(inf)->30. */
  71                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  72                 dist = period / 4;
  73             }
  74         }
  75 #endif /* CONFIG_HEARTBEAT */
  76         return IRQ_HANDLED;
  77 }
  78
  79 void time_init(void)
  80 {
  81         struct rtc_time time;
  82
  83         if (mach_hwclk) {
  84                 mach_hwclk(0, &time);
  85
  86                 if ((time.tm_year += 1900) < 1970)
  87                         time.tm_year += 100;
  88                 xtime.tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday,
  89                                       time.tm_hour, time.tm_min, time.tm_sec);
  90                 xtime.tv_nsec = 0;
  91         }
  92         wall_to_monotonic.tv_sec = -xtime.tv_sec;
  93
  94         mach_sched_init(timer_interrupt);
  95 }
  96
  97 /*
  98  * This version of gettimeofday has near microsecond resolution.
  99  */
 100 void do_gettimeofday(struct timeval *tv)
 101 {
 102         unsigned long flags;
 103         extern unsigned long wall_jiffies;
 104         unsigned long seq;
 105         unsigned long usec, sec, lost;
 106         unsigned long max_ntp_tick = tick_usec - tickadj;
 107
 108         do {
 109                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 110
 111                 usec = mach_gettimeoffset();
 112                 lost = jiffies - wall_jiffies;
 113
 114                 /*
 115                  * If time_adjust is negative then NTP is slowing the clock
 116                  * so make sure not to go into next possible interval.
 117                  * Better to lose some accuracy than have time go backwards..
 118                  */
 119                 if (unlikely(time_adjust < 0)) {
 120                         usec = min(usec, max_ntp_tick);
 121
 122                         if (lost)
 123                                 usec += lost * max_ntp_tick;
 124                 }
 125                 else if (unlikely(lost))
 126                         usec += lost * tick_usec;
 127
 128                 sec = xtime.tv_sec;
 129                 usec += xtime.tv_nsec/1000;
 130         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 131
 132
 133         while (usec >= 1000000) {
 134                 usec -= 1000000;
 135                 sec++;
 136         }
 137
 138         tv->tv_sec = sec;
 139         tv->tv_usec = usec;
 140 }
 141
 142 EXPORT_SYMBOL(do_gettimeofday);
 143
 144 int do_settimeofday(struct timespec *tv)
 145 {
 146         time_t wtm_sec, sec = tv->tv_sec;
 147         long wtm_nsec, nsec = tv->tv_nsec;
 148         extern unsigned long wall_jiffies;
 149
 150         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 151                 return -EINVAL;
 152
 153         write_seqlock_irq(&xtime_lock);
 154         /* This is revolting. We need to set the xtime.tv_nsec
 155          * correctly. However, the value in this location is
 156          * is value at the last tick.
 157          * Discover what correction gettimeofday
 158          * would have done, and then undo it!
 159          */
 160         nsec -= 1000 * (mach_gettimeoffset() +
 161                         (jiffies - wall_jiffies) * (1000000 / HZ));
 162
 163         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 164         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 165
 166         set_normalized_timespec(&xtime, sec, nsec);
 167         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 168
 169         time_adjust = 0;                /* stop active adjtime() */
 170         time_status |= STA_UNSYNC;
 171         time_maxerror = NTP_PHASE_LIMIT;
 172         time_esterror = NTP_PHASE_LIMIT;
 173         write_sequnlock_irq(&xtime_lock);
 174         clock_was_set();
 175         return 0;
 176 }
 177
 178 EXPORT_SYMBOL(do_settimeofday);
 179
 180 /*
 181  * Scheduler clock - returns current time in ns units.
 182  */
 183 unsigned long long sched_clock(void)
 184 {
 185        return (unsigned long long)jiffies*(1000000000/HZ);
 186 }
 187