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