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/irq_regs.h>
  26
  27 #define TICK_SIZE (tick_nsec / 1000)
  28
  29 static inline int set_rtc_mmss(unsigned long nowtime)
  30 {
  31         if (mach_set_clock_mmss)
  32                 return mach_set_clock_mmss (nowtime);
  33         return -1;
  34 }
  35
  36 /*
  37  * timer_interrupt() needs to keep up the real-time clock,
  38  * as well as call the "do_timer()" routine every clocktick
  39  */
  40 irqreturn_t arch_timer_interrupt(int irq, void *dummy)
  41 {
  42         /* last time the cmos clock got updated */
  43         static long last_rtc_update=0;
  44
  45         if (current->pid)
  46                 profile_tick(CPU_PROFILING);
  47
  48         write_seqlock(&xtime_lock);
  49
  50         do_timer(1);
  51
  52         /*
  53          * If we have an externally synchronized Linux clock, then update
  54          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  55          * called as close as possible to 500 ms before the new second starts.
  56          */
  57         if (ntp_synced() &&
  58             xtime.tv_sec > last_rtc_update + 660 &&
  59             (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
  60             (xtime.tv_nsec  / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
  61           if (set_rtc_mmss(xtime.tv_sec) == 0)
  62             last_rtc_update = xtime.tv_sec;
  63           else
  64             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  65         }
  66
  67         write_sequnlock(&xtime_lock);
  68
  69 #ifndef CONFIG_SMP
  70         update_process_times(user_mode(get_irq_regs()));
  71 #endif
  72         return(IRQ_HANDLED);
  73 }
  74
  75 void time_init(void)
  76 {
  77         unsigned int year, mon, day, hour, min, sec;
  78
  79         if (mach_gettod)
  80                 mach_gettod(&year, &mon, &day, &hour, &min, &sec);
  81         else
  82                 year = mon = day = hour = min = sec = 0;
  83
  84         if ((year += 1900) < 1970)
  85                 year += 100;
  86         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
  87         xtime.tv_nsec = 0;
  88         wall_to_monotonic.tv_sec = -xtime.tv_sec;
  89
  90         hw_timer_init();
  91 }
  92