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/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/rtc.h>
  21 #include <linux/platform_device.h>
  22
  23 #include <asm/machdep.h>
  24 #include <asm/io.h>
  25 #include <asm/irq_regs.h>
  26
  27 #include <linux/time.h>
  28 #include <linux/timex.h>
  29 #include <linux/profile.h>
  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         do_timer(1);
  45 #ifndef CONFIG_SMP
  46         update_process_times(user_mode(get_irq_regs()));
  47 #endif
  48         profile_tick(CPU_PROFILING);
  49
  50 #ifdef CONFIG_HEARTBEAT
  51         /* use power LED as a heartbeat instead -- much more useful
  52            for debugging -- based on the version for PReP by Cort */
  53         /* acts like an actual heart beat -- ie thump-thump-pause... */
  54         if (mach_heartbeat) {
  55             static unsigned cnt = 0, period = 0, dist = 0;
  56
  57             if (cnt == 0 || cnt == dist)
  58                 mach_heartbeat( 1 );
  59             else if (cnt == 7 || cnt == dist+7)
  60                 mach_heartbeat( 0 );
  61
  62             if (++cnt > period) {
  63                 cnt = 0;
  64                 /* The hyperbolic function below modifies the heartbeat period
  65                  * length in dependency of the current (5min) load. It goes
  66                  * through the points f(0)=126, f(1)=86, f(5)=51,
  67                  * f(inf)->30. */
  68                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  69                 dist = period / 4;
  70             }
  71         }
  72 #endif /* CONFIG_HEARTBEAT */
  73         return IRQ_HANDLED;
  74 }
  75
  76 void __init time_init(void)
  77 {
  78         struct rtc_time time;
  79
  80         if (mach_hwclk) {
  81                 mach_hwclk(0, &time);
  82
  83                 if ((time.tm_year += 1900) < 1970)
  84                         time.tm_year += 100;
  85                 xtime.tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday,
  86                                       time.tm_hour, time.tm_min, time.tm_sec);
  87                 xtime.tv_nsec = 0;
  88         }
  89         wall_to_monotonic.tv_sec = -xtime.tv_sec;
  90
  91         mach_sched_init(timer_interrupt);
  92 }
  93
  94 /*
  95  * This version of gettimeofday has near microsecond resolution.
  96  */
  97 void do_gettimeofday(struct timeval *tv)
  98 {
  99         unsigned long flags;
 100         unsigned long seq;
 101         unsigned long usec, sec;
 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
 109                 /*
 110                  * If time_adjust is negative then NTP is slowing the clock
 111                  * so make sure not to go into next possible interval.
 112                  * Better to lose some accuracy than have time go backwards..
 113                  */
 114                 if (unlikely(time_adjust < 0))
 115                         usec = min(usec, max_ntp_tick);
 116
 117                 sec = xtime.tv_sec;
 118                 usec += xtime.tv_nsec/1000;
 119         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 120
 121
 122         while (usec >= 1000000) {
 123                 usec -= 1000000;
 124                 sec++;
 125         }
 126
 127         tv->tv_sec = sec;
 128         tv->tv_usec = usec;
 129 }
 130
 131 EXPORT_SYMBOL(do_gettimeofday);
 132
 133 int do_settimeofday(struct timespec *tv)
 134 {
 135         time_t wtm_sec, sec = tv->tv_sec;
 136         long wtm_nsec, nsec = tv->tv_nsec;
 137
 138         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 139                 return -EINVAL;
 140
 141         write_seqlock_irq(&xtime_lock);
 142         /* This is revolting. We need to set the xtime.tv_nsec
 143          * correctly. However, the value in this location is
 144          * is value at the last tick.
 145          * Discover what correction gettimeofday
 146          * would have done, and then undo it!
 147          */
 148         nsec -= 1000 * mach_gettimeoffset();
 149
 150         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 151         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 152
 153         set_normalized_timespec(&xtime, sec, nsec);
 154         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 155
 156         ntp_clear();
 157         write_sequnlock_irq(&xtime_lock);
 158         clock_was_set();
 159         return 0;
 160 }
 161
 162 EXPORT_SYMBOL(do_settimeofday);
 163
 164
 165 static int __init rtc_init(void)
 166 {
 167         struct platform_device *pdev;
 168
 169         if (!mach_hwclk)
 170                 return -ENODEV;
 171
 172         pdev = platform_device_register_simple("rtc-generic", -1, NULL, 0);
 173         if (IS_ERR(pdev))
 174                 return PTR_ERR(pdev);
 175
 176         return 0;
 177 }
 178
 179 module_init(rtc_init);