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);
36 static inline void do_set_rtc(void)
38 /* last time the cmos clock got updated */
39 static long last_rtc_update=0;
42 * If we have an externally synchronized Linux clock, then update
43 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
44 * called as close as possible to 500 ms before the new second starts.
47 xtime.tv_sec > last_rtc_update + 660 &&
48 (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
49 (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
50 if (set_rtc_mmss(xtime.tv_sec) == 0)
51 last_rtc_update = xtime.tv_sec;
53 last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
58 * timer_interrupt() needs to keep up the real-time clock,
59 * as well as call the "do_timer()" routine every clocktick
61 irqreturn_t arch_timer_interrupt(int irq, void *dummy)
65 profile_tick(CPU_PROFILING);
67 write_seqlock(&xtime_lock);
73 write_sequnlock(&xtime_lock);
76 update_process_times(user_mode(get_irq_regs()));
81 static unsigned long read_rtc_mmss(void)
83 unsigned int year, mon, day, hour, min, sec;
86 mach_gettod(&year, &mon, &day, &hour, &min, &sec);
88 year = mon = day = hour = min = sec = 0;
90 if ((year += 1900) < 1970)
93 return mktime(year, mon, day, hour, min, sec);;
98 xtime.tv_sec = read_rtc_mmss();
100 wall_to_monotonic.tv_sec = -xtime.tv_sec;