2 * linux/arch/m68knommu/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/profile.h>
21 #include <linux/time.h>
22 #include <linux/timex.h>
24 #include <asm/machdep.h>
25 #include <asm/irq_regs.h>
27 #define TICK_SIZE (tick_nsec / 1000)
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 irqreturn_t arch_timer_interrupt(int irq, void *dummy)
42 /* last time the cmos clock got updated */
43 static long last_rtc_update=0;
45 write_seqlock(&xtime_lock);
49 update_process_times(user_mode(get_irq_regs()));
52 profile_tick(CPU_PROFILING);
55 * If we have an externally synchronized Linux clock, then update
56 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
57 * called as close as possible to 500 ms before the new second starts.
60 xtime.tv_sec > last_rtc_update + 660 &&
61 (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
62 (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
63 if (set_rtc_mmss(xtime.tv_sec) == 0)
64 last_rtc_update = xtime.tv_sec;
66 last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
69 write_sequnlock(&xtime_lock);
75 unsigned int year, mon, day, hour, min, sec;
78 mach_gettod(&year, &mon, &day, &hour, &min, &sec);
80 year = mon = day = hour = min = sec = 0;
82 if ((year += 1900) < 1970)
84 xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
86 wall_to_monotonic.tv_sec = -xtime.tv_sec;
92 * This version of gettimeofday has near microsecond resolution.
94 void do_gettimeofday(struct timeval *tv)
98 unsigned long usec, sec;
101 seq = read_seqbegin_irqsave(&xtime_lock, flags);
102 usec = hw_timer_offset();
104 usec += (xtime.tv_nsec / 1000);
105 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
107 while (usec >= 1000000) {
116 EXPORT_SYMBOL(do_gettimeofday);
118 int do_settimeofday(struct timespec *tv)
120 time_t wtm_sec, sec = tv->tv_sec;
121 long wtm_nsec, nsec = tv->tv_nsec;
123 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
126 write_seqlock_irq(&xtime_lock);
128 * This is revolting. We need to set the xtime.tv_usec
129 * correctly. However, the value in this location is
130 * is value at the last tick.
131 * Discover what correction gettimeofday
132 * would have done, and then undo it!
134 nsec -= (hw_timer_offset() * 1000);
136 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
137 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
139 set_normalized_timespec(&xtime, sec, nsec);
140 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
143 write_sequnlock_irq(&xtime_lock);
147 EXPORT_SYMBOL(do_settimeofday);