1 /* $Id: time.c,v 1.18 2005/03/04 08:16:17 starvik Exp $
3 * linux/arch/cris/kernel/time.c
5 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
6 * Copyright (C) 1999, 2000, 2001 Axis Communications AB
8 * 1994-07-02 Alan Modra
9 * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
10 * 1995-03-26 Markus Kuhn
11 * fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
12 * precision CMOS clock update
13 * 1996-05-03 Ingo Molnar
14 * fixed time warps in do_[slow|fast]_gettimeoffset()
15 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
16 * "A Kernel Model for Precision Timekeeping" by Dave Mills
18 * Linux/CRIS specific code:
20 * Authors: Bjorn Wesen
26 #include <linux/errno.h>
27 #include <linux/module.h>
28 #include <linux/param.h>
29 #include <linux/jiffies.h>
30 #include <linux/bcd.h>
31 #include <linux/timex.h>
32 #include <linux/init.h>
33 #include <linux/profile.h>
35 int have_rtc; /* used to remember if we have an RTC or not */;
37 #define TICK_SIZE tick
39 extern unsigned long wall_jiffies;
40 extern unsigned long loops_per_jiffy; /* init/main.c */
41 unsigned long loops_per_usec;
43 extern unsigned long do_slow_gettimeoffset(void);
44 static unsigned long (*do_gettimeoffset)(void) = do_slow_gettimeoffset;
47 * This version of gettimeofday has near microsecond resolution.
49 * Note: Division is quite slow on CRIS and do_gettimeofday is called
50 * rather often. Maybe we should do some kind of approximation here
51 * (a naive approximation would be to divide by 1024).
53 void do_gettimeofday(struct timeval *tv)
56 signed long usec, sec;
57 local_irq_save(flags);
59 usec = do_gettimeoffset();
61 unsigned long lost = jiffies - wall_jiffies;
63 usec += lost * (1000000 / HZ);
67 * If time_adjust is negative then NTP is slowing the clock
68 * so make sure not to go into next possible interval.
69 * Better to lose some accuracy than have time go backwards..
71 if (unlikely(time_adjust < 0) && usec > tickadj)
75 usec += xtime.tv_nsec / 1000;
76 local_irq_restore(flags);
78 while (usec >= 1000000) {
87 EXPORT_SYMBOL(do_gettimeofday);
89 int do_settimeofday(struct timespec *tv)
91 time_t wtm_sec, sec = tv->tv_sec;
92 long wtm_nsec, nsec = tv->tv_nsec;
94 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
97 write_seqlock_irq(&xtime_lock);
99 * This is revolting. We need to set "xtime" correctly. However, the
100 * value in this location is the value at the most recent update of
101 * wall time. Discover what correction gettimeofday() would have
102 * made, and then undo it!
104 nsec -= do_gettimeoffset() * NSEC_PER_USEC;
105 nsec -= (jiffies - wall_jiffies) * TICK_NSEC;
107 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
108 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
110 set_normalized_timespec(&xtime, sec, nsec);
111 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
114 write_sequnlock_irq(&xtime_lock);
119 EXPORT_SYMBOL(do_settimeofday);
123 * BUG: This routine does not handle hour overflow properly; it just
124 * sets the minutes. Usually you'll only notice that after reboot!
127 int set_rtc_mmss(unsigned long nowtime)
130 int real_seconds, real_minutes, cmos_minutes;
132 printk(KERN_DEBUG "set_rtc_mmss(%lu)\n", nowtime);
137 cmos_minutes = CMOS_READ(RTC_MINUTES);
138 BCD_TO_BIN(cmos_minutes);
141 * since we're only adjusting minutes and seconds,
142 * don't interfere with hour overflow. This avoids
143 * messing with unknown time zones but requires your
144 * RTC not to be off by more than 15 minutes
146 real_seconds = nowtime % 60;
147 real_minutes = nowtime / 60;
148 if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
149 real_minutes += 30; /* correct for half hour time zone */
152 if (abs(real_minutes - cmos_minutes) < 30) {
153 BIN_TO_BCD(real_seconds);
154 BIN_TO_BCD(real_minutes);
155 CMOS_WRITE(real_seconds,RTC_SECONDS);
156 CMOS_WRITE(real_minutes,RTC_MINUTES);
159 "set_rtc_mmss: can't update from %d to %d\n",
160 cmos_minutes, real_minutes);
167 /* grab the time from the RTC chip */
172 unsigned int year, mon, day, hour, min, sec;
174 sec = CMOS_READ(RTC_SECONDS);
175 min = CMOS_READ(RTC_MINUTES);
176 hour = CMOS_READ(RTC_HOURS);
177 day = CMOS_READ(RTC_DAY_OF_MONTH);
178 mon = CMOS_READ(RTC_MONTH);
179 year = CMOS_READ(RTC_YEAR);
182 "rtc: sec 0x%x min 0x%x hour 0x%x day 0x%x mon 0x%x year 0x%x\n",
183 sec, min, hour, day, mon, year);
192 if ((year += 1900) < 1970)
195 return mktime(year, mon, day, hour, min, sec);
198 /* update xtime from the CMOS settings. used when /dev/rtc gets a SET_TIME.
199 * TODO: this doesn't reset the fancy NTP phase stuff as do_settimeofday does.
203 update_xtime_from_cmos(void)
206 xtime.tv_sec = get_cmos_time();
211 extern void cris_profile_sample(struct pt_regs* regs);
214 cris_do_profile(struct pt_regs* regs)
217 #if CONFIG_SYSTEM_PROFILER
218 cris_profile_sample(regs);
222 profile_tick(CPU_PROFILING, regs);
227 * Scheduler clock - returns current time in nanosec units.
229 unsigned long long sched_clock(void)
231 return (unsigned long long)jiffies * (1000000000 / HZ);
235 __init init_udelay(void)
237 loops_per_usec = (loops_per_jiffy * HZ) / 1000000;
241 __initcall(init_udelay);