2 * linux/arch/arm26/kernel/time.c
4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
5 * Modifications for ARM (C) 1994-2001 Russell King
6 * Mods for ARM26 (C) 2003 Ian Molton
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
12 * This file contains the ARM-specific time handling details:
13 * reading the RTC at bootup, etc...
15 * 1994-07-02 Alan Modra
16 * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
17 * 1998-12-20 Updated NTP code according to technical memorandum Jan '96
18 * "A Kernel Model for Precision Timekeeping" by Dave Mills
21 #include <linux/config.h>
22 #include <linux/module.h>
23 #include <linux/kernel.h>
24 #include <linux/interrupt.h>
25 #include <linux/time.h>
26 #include <linux/init.h>
27 #include <linux/smp.h>
28 #include <linux/timex.h>
29 #include <linux/errno.h>
30 #include <linux/profile.h>
32 #include <asm/hardware.h>
37 u64 jiffies_64 = INITIAL_JIFFIES;
39 EXPORT_SYMBOL(jiffies_64);
41 extern unsigned long wall_jiffies;
43 /* this needs a better home */
44 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
46 /* change this if you have some constant time drift */
47 #define USECS_PER_JIFFY (1000000/HZ)
49 static int dummy_set_rtc(void)
55 * hook for setting the RTC's idea of the current time.
57 int (*set_rtc)(void) = dummy_set_rtc;
59 static unsigned long dummy_gettimeoffset(void)
65 * hook for getting the time offset. Note that it is
66 * always called with interrupts disabled.
68 unsigned long (*gettimeoffset)(void) = dummy_gettimeoffset;
71 * Handle kernel profile stuff...
73 static inline void do_profile(struct pt_regs *regs)
75 if (!user_mode(regs) &&
78 unsigned long pc = instruction_pointer(regs);
81 pc -= (unsigned long)&_stext;
92 static unsigned long next_rtc_update;
95 * If we have an externally synchronized linux clock, then update
96 * CMOS clock accordingly every ~11 minutes. set_rtc() has to be
97 * called as close as possible to 500 ms before the new second
100 static inline void do_set_rtc(void)
102 if (time_status & STA_UNSYNC || set_rtc == NULL)
105 //FIXME - timespec.tv_sec is a time_t not unsigned long
106 if (next_rtc_update &&
107 time_before((unsigned long)xtime.tv_sec, next_rtc_update))
110 if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) &&
111 xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1))
116 * rtc update failed. Try again in 60s
118 next_rtc_update = xtime.tv_sec + 60;
120 next_rtc_update = xtime.tv_sec + 660;
125 void do_gettimeofday(struct timeval *tv)
129 unsigned long usec, sec, lost;
132 seq = read_seqbegin_irqsave(&xtime_lock, flags);
133 usec = gettimeoffset();
135 lost = jiffies - wall_jiffies;
137 usec += lost * USECS_PER_JIFFY;
140 usec += xtime.tv_nsec / 1000;
141 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
143 /* usec may have gone up a lot: be safe */
144 while (usec >= 1000000) {
153 EXPORT_SYMBOL(do_gettimeofday);
155 int do_settimeofday(struct timespec *tv)
157 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
160 write_seqlock_irq(&xtime_lock);
162 * This is revolting. We need to set "xtime" correctly. However, the
163 * value in this location is the value at the most recent update of
164 * wall time. Discover what correction gettimeofday() would have
165 * done, and then undo it!
167 tv->tv_nsec -= 1000 * (gettimeoffset() +
168 (jiffies - wall_jiffies) * USECS_PER_JIFFY);
170 while (tv->tv_nsec < 0) {
171 tv->tv_nsec += NSEC_PER_SEC;
175 xtime.tv_sec = tv->tv_sec;
176 xtime.tv_nsec = tv->tv_nsec;
177 time_adjust = 0; /* stop active adjtime() */
178 time_status |= STA_UNSYNC;
179 time_maxerror = NTP_PHASE_LIMIT;
180 time_esterror = NTP_PHASE_LIMIT;
181 write_sequnlock_irq(&xtime_lock);
186 EXPORT_SYMBOL(do_settimeofday);
188 static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
191 do_set_rtc(); //FIME - EVERY timer IRQ?
193 return IRQ_HANDLED; //FIXME - is this right?
196 static struct irqaction timer_irq = {
198 .flags = SA_INTERRUPT,
199 .handler = timer_interrupt,
202 extern void ioctime_init(void);
205 * Set up timer interrupt.
207 void __init time_init(void)
211 setup_irq(IRQ_TIMER, &timer_irq);