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 static inline void do_set_rtc(void)
  37 {
  38         /* last time the cmos clock got updated */
  39         static long last_rtc_update=0;
  40
  41         /*
  42          * If we have an externally synchronized Linux clock, then update
  43          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
  44          * called as close as possible to 500 ms before the new second starts.
  45          */
  46         if (ntp_synced() &&
  47             xtime.tv_sec > last_rtc_update + 660 &&
  48             (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
  49             (xtime.tv_nsec  / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
  50           if (set_rtc_mmss(xtime.tv_sec) == 0)
  51             last_rtc_update = xtime.tv_sec;
  52           else
  53             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
  54         }
  55 }
  56
  57 /*
  58  * timer_interrupt() needs to keep up the real-time clock,
  59  * as well as call the "do_timer()" routine every clocktick
  60  */
  61 irqreturn_t arch_timer_interrupt(int irq, void *dummy)
  62 {
  63
  64         if (current->pid)
  65                 profile_tick(CPU_PROFILING);
  66
  67         write_seqlock(&xtime_lock);
  68
  69         do_timer(1);
  70
  71         do_set_rtc();
  72
  73         write_sequnlock(&xtime_lock);
  74
  75 #ifndef CONFIG_SMP
  76         update_process_times(user_mode(get_irq_regs()));
  77 #endif
  78         return(IRQ_HANDLED);
  79 }
  80
  81 static unsigned long read_rtc_mmss(void)
  82 {
  83         unsigned int year, mon, day, hour, min, sec;
  84
  85         if (mach_gettod)
  86                 mach_gettod(&year, &mon, &day, &hour, &min, &sec);
  87         else
  88                 year = mon = day = hour = min = sec = 0;
  89
  90         if ((year += 1900) < 1970)
  91                 year += 100;
  92
  93         return  mktime(year, mon, day, hour, min, sec);;
  94 }
  95
  96 void time_init(void)
  97 {
  98         xtime.tv_sec = read_rtc_mmss();
  99         xtime.tv_nsec = 0;
 100         wall_to_monotonic.tv_sec = -xtime.tv_sec;
 101
 102         hw_timer_init();
 103 }
 104