2 * linux/arch/m68k/kernel/time.c
4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
6 * This file contains the m68k-specific time handling details.
7 * Most of the stuff is located in the machine specific files.
9 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
10 * "A Kernel Model for Precision Timekeeping" by Dave Mills
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>
20 #include <linux/rtc.h>
22 #include <asm/machdep.h>
25 #include <linux/time.h>
26 #include <linux/timex.h>
27 #include <linux/profile.h>
29 static inline int set_rtc_mmss(unsigned long nowtime)
31 if (mach_set_clock_mmss)
32 return mach_set_clock_mmss (nowtime);
37 * timer_interrupt() needs to keep up the real-time clock,
38 * as well as call the "do_timer()" routine every clocktick
40 static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
44 update_process_times(user_mode(regs));
46 profile_tick(CPU_PROFILING, regs);
48 #ifdef CONFIG_HEARTBEAT
49 /* use power LED as a heartbeat instead -- much more useful
50 for debugging -- based on the version for PReP by Cort */
51 /* acts like an actual heart beat -- ie thump-thump-pause... */
53 static unsigned cnt = 0, period = 0, dist = 0;
55 if (cnt == 0 || cnt == dist)
57 else if (cnt == 7 || cnt == dist+7)
62 /* The hyperbolic function below modifies the heartbeat period
63 * length in dependency of the current (5min) load. It goes
64 * through the points f(0)=126, f(1)=86, f(5)=51,
66 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
70 #endif /* CONFIG_HEARTBEAT */
81 if ((time.tm_year += 1900) < 1970)
83 xtime.tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday,
84 time.tm_hour, time.tm_min, time.tm_sec);
87 wall_to_monotonic.tv_sec = -xtime.tv_sec;
89 mach_sched_init(timer_interrupt);
93 * This version of gettimeofday has near microsecond resolution.
95 void do_gettimeofday(struct timeval *tv)
99 unsigned long usec, sec;
100 unsigned long max_ntp_tick = tick_usec - tickadj;
103 seq = read_seqbegin_irqsave(&xtime_lock, flags);
105 usec = mach_gettimeoffset();
108 * If time_adjust is negative then NTP is slowing the clock
109 * so make sure not to go into next possible interval.
110 * Better to lose some accuracy than have time go backwards..
112 if (unlikely(time_adjust < 0))
113 usec = min(usec, max_ntp_tick);
116 usec += xtime.tv_nsec/1000;
117 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
120 while (usec >= 1000000) {
129 EXPORT_SYMBOL(do_gettimeofday);
131 int do_settimeofday(struct timespec *tv)
133 time_t wtm_sec, sec = tv->tv_sec;
134 long wtm_nsec, nsec = tv->tv_nsec;
136 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
139 write_seqlock_irq(&xtime_lock);
140 /* This is revolting. We need to set the xtime.tv_nsec
141 * correctly. However, the value in this location is
142 * is value at the last tick.
143 * Discover what correction gettimeofday
144 * would have done, and then undo it!
146 nsec -= 1000 * mach_gettimeoffset();
148 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
149 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
151 set_normalized_timespec(&xtime, sec, nsec);
152 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
155 write_sequnlock_irq(&xtime_lock);
160 EXPORT_SYMBOL(do_settimeofday);
163 * Scheduler clock - returns current time in ns units.
165 unsigned long long sched_clock(void)
167 return (unsigned long long)jiffies*(1000000000/HZ);