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/export.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 #include <linux/platform_device.h>
  23
  24 #include <asm/machdep.h>
  25 #include <asm/io.h>
  26 #include <asm/irq_regs.h>
  27
  28 #include <linux/time.h>
  29 #include <linux/timex.h>
  30 #include <linux/profile.h>
  31
  32
  33 unsigned long (*mach_random_get_entropy)(void);
  34 EXPORT_SYMBOL_GPL(mach_random_get_entropy);
  35
  36
  37 /*
  38  * timer_interrupt() needs to keep up the real-time clock,
  39  * as well as call the "xtime_update()" routine every clocktick
  40  */
  41 static irqreturn_t timer_interrupt(int irq, void *dummy)
  42 {
  43         xtime_update(1);
  44         update_process_times(user_mode(get_irq_regs()));
  45         profile_tick(CPU_PROFILING);
  46
  47 #ifdef CONFIG_HEARTBEAT
  48         /* use power LED as a heartbeat instead -- much more useful
  49            for debugging -- based on the version for PReP by Cort */
  50         /* acts like an actual heart beat -- ie thump-thump-pause... */
  51         if (mach_heartbeat) {
  52             static unsigned cnt = 0, period = 0, dist = 0;
  53
  54             if (cnt == 0 || cnt == dist)
  55                 mach_heartbeat( 1 );
  56             else if (cnt == 7 || cnt == dist+7)
  57                 mach_heartbeat( 0 );
  58
  59             if (++cnt > period) {
  60                 cnt = 0;
  61                 /* The hyperbolic function below modifies the heartbeat period
  62                  * length in dependency of the current (5min) load. It goes
  63                  * through the points f(0)=126, f(1)=86, f(5)=51,
  64                  * f(inf)->30. */
  65                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  66                 dist = period / 4;
  67             }
  68         }
  69 #endif /* CONFIG_HEARTBEAT */
  70         return IRQ_HANDLED;
  71 }
  72
  73 void read_persistent_clock(struct timespec *ts)
  74 {
  75         struct rtc_time time;
  76         ts->tv_sec = 0;
  77         ts->tv_nsec = 0;
  78
  79         if (mach_hwclk) {
  80                 mach_hwclk(0, &time);
  81
  82                 if ((time.tm_year += 1900) < 1970)
  83                         time.tm_year += 100;
  84                 ts->tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday,
  85                                       time.tm_hour, time.tm_min, time.tm_sec);
  86         }
  87 }
  88
  89 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
  90
  91 static int __init rtc_init(void)
  92 {
  93         struct platform_device *pdev;
  94
  95         if (!mach_hwclk)
  96                 return -ENODEV;
  97
  98         pdev = platform_device_register_simple("rtc-generic", -1, NULL, 0);
  99         return PTR_ERR_OR_ZERO(pdev);
 100 }
 101
 102 module_init(rtc_init);
 103
 104 #endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */
 105
 106 void __init time_init(void)
 107 {
 108         mach_sched_init(timer_interrupt);
 109 }