release/src-rt-6.x/linux/linux-2.6/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
  31 static inline int set_rtc_mmss(unsigned long nowtime)
  32 {
  33         if (mach_set_clock_mmss)
  34                 return mach_set_clock_mmss (nowtime);
  35         return -1;
  36 }
  37
  38 /*
  39  * timer_interrupt() needs to keep up the real-time clock,
  40  * as well as call the "do_timer()" routine every clocktick
  41  */
  42 static irqreturn_t timer_interrupt(int irq, void *dummy)
  43 {
  44         /* last time the cmos clock got updated */
  45         static long last_rtc_update=0;
  46
  47         /* may need to kick the hardware timer */
  48         if (mach_tick)
  49           mach_tick();
  50
  51         write_seqlock(&xtime_lock);
  52
  53         do_timer(1);
  54 #ifndef CONFIG_SMP
  55         update_process_times(user_mode(get_irq_regs()));
  56 #endif
  57         if (current->pid)
  58                 profile_tick(CPU_PROFILING);
  59
  60         /*
  61          * If we have an externally synchronized Linux clock, then update
  62          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  63          * called as close as possible to 500 ms before the new second starts.
  64          */
  65         if (ntp_synced() &&
  66             xtime.tv_sec > last_rtc_update + 660 &&
  67             (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
  68             (xtime.tv_nsec  / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
  69           if (set_rtc_mmss(xtime.tv_sec) == 0)
  70             last_rtc_update = xtime.tv_sec;
  71           else
  72             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  73         }
  74 #ifdef CONFIG_HEARTBEAT
  75         /* use power LED as a heartbeat instead -- much more useful
  76            for debugging -- based on the version for PReP by Cort */
  77         /* acts like an actual heart beat -- ie thump-thump-pause... */
  78         if (mach_heartbeat) {
  79             static unsigned cnt = 0, period = 0, dist = 0;
  80
  81             if (cnt == 0 || cnt == dist)
  82                 mach_heartbeat( 1 );
  83             else if (cnt == 7 || cnt == dist+7)
  84                 mach_heartbeat( 0 );
  85
  86             if (++cnt > period) {
  87                 cnt = 0;
  88                 /* The hyperbolic function below modifies the heartbeat period
  89                  * length in dependency of the current (5min) load. It goes
  90                  * through the points f(0)=126, f(1)=86, f(5)=51,
  91                  * f(inf)->30. */
  92                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  93                 dist = period / 4;
  94             }
  95         }
  96 #endif /* CONFIG_HEARTBEAT */
  97
  98         write_sequnlock(&xtime_lock);
  99         return(IRQ_HANDLED);
 100 }
 101
 102 void time_init(void)
 103 {
 104         unsigned int year, mon, day, hour, min, sec;
 105
 106         extern void arch_gettod(int *year, int *mon, int *day, int *hour,
 107                                 int *min, int *sec);
 108
 109         arch_gettod(&year, &mon, &day, &hour, &min, &sec);
 110
 111         if ((year += 1900) < 1970)
 112                 year += 100;
 113         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
 114         xtime.tv_nsec = 0;
 115         wall_to_monotonic.tv_sec = -xtime.tv_sec;
 116
 117         mach_sched_init(timer_interrupt);
 118 }
 119
 120 /*
 121  * This version of gettimeofday has near microsecond resolution.
 122  */
 123 void do_gettimeofday(struct timeval *tv)
 124 {
 125         unsigned long flags;
 126         unsigned long seq;
 127         unsigned long usec, sec;
 128
 129         do {
 130                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 131                 usec = mach_gettimeoffset ? mach_gettimeoffset() : 0;
 132                 sec = xtime.tv_sec;
 133                 usec += (xtime.tv_nsec / 1000);
 134         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 135
 136         while (usec >= 1000000) {
 137                 usec -= 1000000;
 138                 sec++;
 139         }
 140
 141         tv->tv_sec = sec;
 142         tv->tv_usec = usec;
 143 }
 144
 145 EXPORT_SYMBOL(do_gettimeofday);
 146
 147 int do_settimeofday(struct timespec *tv)
 148 {
 149         time_t wtm_sec, sec = tv->tv_sec;
 150         long wtm_nsec, nsec = tv->tv_nsec;
 151
 152         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 153                 return -EINVAL;
 154
 155         write_seqlock_irq(&xtime_lock);
 156         /*
 157          * This is revolting. We need to set the xtime.tv_usec
 158          * correctly. However, the value in this location is
 159          * is value at the last tick.
 160          * Discover what correction gettimeofday
 161          * would have done, and then undo it!
 162          */
 163         if (mach_gettimeoffset)
 164                 nsec -= (mach_gettimeoffset() * 1000);
 165
 166         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 167         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 168
 169         set_normalized_timespec(&xtime, sec, nsec);
 170         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 171
 172         ntp_clear();
 173         write_sequnlock_irq(&xtime_lock);
 174         clock_was_set();
 175         return 0;
 176 }
 177 EXPORT_SYMBOL(do_settimeofday);