2 * linux/arch/arm/kernel/time.c
4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
5 * Modifications for ARM (C) 1994-2001 Russell King
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * This file contains the ARM-specific time handling details:
12 * reading the RTC at bootup, etc...
14 * 1994-07-02 Alan Modra
15 * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
16 * 1998-12-20 Updated NTP code according to technical memorandum Jan '96
17 * "A Kernel Model for Precision Timekeeping" by Dave Mills
19 #include <linux/config.h>
20 #include <linux/module.h>
21 #include <linux/kernel.h>
22 #include <linux/interrupt.h>
23 #include <linux/time.h>
24 #include <linux/init.h>
25 #include <linux/smp.h>
26 #include <linux/timex.h>
27 #include <linux/errno.h>
28 #include <linux/profile.h>
30 #include <asm/hardware.h>
35 u64 jiffies_64 = INITIAL_JIFFIES;
37 extern unsigned long wall_jiffies;
39 /* this needs a better home */
40 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
42 #ifdef CONFIG_SA1100_RTC_MODULE
43 EXPORT_SYMBOL(rtc_lock);
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 if (next_rtc_update &&
106 time_before(xtime.tv_sec, next_rtc_update))
109 if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) &&
110 xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1))
115 * rtc update failed. Try again in 60s
117 next_rtc_update = xtime.tv_sec + 60;
119 next_rtc_update = xtime.tv_sec + 660;
124 static void dummy_leds_event(led_event_t evt)
128 void (*leds_event)(led_event_t) = dummy_leds_event;
130 EXPORT_SYMBOL(leds_event);
133 #ifdef CONFIG_LEDS_TIMER
134 static void do_leds(void)
136 static unsigned int count = 50;
140 leds_event(led_timer);
147 void do_gettimeofday(struct timeval *tv)
151 unsigned long usec, sec, lost;
154 seq = read_seqbegin_irqsave(&xtime_lock, flags);
155 usec = gettimeoffset();
157 lost = jiffies - wall_jiffies;
159 usec += lost * USECS_PER_JIFFY;
162 usec += xtime.tv_nsec / 1000;
163 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
165 /* usec may have gone up a lot: be safe */
166 while (usec >= 1000000) {
175 int do_settimeofday(struct timespec *tv)
177 time_t wtm_sec, sec = tv->tv_sec;
178 long wtm_nsec, nsec = tv->tv_nsec;
180 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
183 write_seqlock_irq(&xtime_lock);
185 * This is revolting. We need to set "xtime" correctly. However, the
186 * value in this location is the value at the most recent update of
187 * wall time. Discover what correction gettimeofday() would have
188 * done, and then undo it!
190 nsec -= gettimeoffset() * NSEC_PER_USEC;
191 nsec -= (jiffies - wall_jiffies) * TICK_NSEC;
193 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
194 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
196 set_normalized_timespec(&xtime, sec, nsec);
197 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
199 time_adjust = 0; /* stop active adjtime() */
200 time_status |= STA_UNSYNC;
201 time_maxerror = NTP_PHASE_LIMIT;
202 time_esterror = NTP_PHASE_LIMIT;
203 write_sequnlock_irq(&xtime_lock);
208 static struct irqaction timer_irq = {
210 .flags = SA_INTERRUPT,
214 * Include architecture specific code
216 #include <asm/arch/time.h>