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 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <linux/interrupt.h>
17 #include <linux/time.h>
18 #include <linux/init.h>
19 #include <linux/sched.h>
20 #include <linux/smp.h>
21 #include <linux/timex.h>
22 #include <linux/errno.h>
23 #include <linux/profile.h>
24 #include <linux/sysdev.h>
25 #include <linux/timer.h>
26 #include <linux/irq.h>
28 #include <linux/mc146818rtc.h>
31 #include <asm/thread_info.h>
32 #include <asm/stacktrace.h>
33 #include <asm/mach/time.h>
38 struct sys_timer *system_timer;
40 #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE)
41 /* this needs a better home */
42 DEFINE_SPINLOCK(rtc_lock);
44 #ifdef CONFIG_RTC_DRV_CMOS_MODULE
45 EXPORT_SYMBOL(rtc_lock);
47 #endif /* pc-style 'CMOS' RTC support */
49 /* change this if you have some constant time drift */
50 #define USECS_PER_JIFFY (1000000/HZ)
53 unsigned long profile_pc(struct pt_regs *regs)
55 struct stackframe frame;
57 if (!in_lock_functions(regs->ARM_pc))
60 frame.fp = regs->ARM_fp;
61 frame.sp = regs->ARM_sp;
62 frame.lr = regs->ARM_lr;
63 frame.pc = regs->ARM_pc;
65 int ret = unwind_frame(&frame);
68 } while (in_lock_functions(frame.pc));
72 EXPORT_SYMBOL(profile_pc);
75 #ifndef CONFIG_GENERIC_TIME
76 static unsigned long dummy_gettimeoffset(void)
82 #ifdef CONFIG_LEDS_TIMER
83 static inline void do_leds(void)
85 static unsigned int count = HZ/2;
89 leds_event(led_timer);
96 #ifndef CONFIG_GENERIC_TIME
97 void do_gettimeofday(struct timeval *tv)
101 unsigned long usec, sec;
104 seq = read_seqbegin_irqsave(&xtime_lock, flags);
105 usec = system_timer->offset();
107 usec += xtime.tv_nsec / 1000;
108 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
110 /* usec may have gone up a lot: be safe */
111 while (usec >= 1000000) {
120 EXPORT_SYMBOL(do_gettimeofday);
122 int do_settimeofday(struct timespec *tv)
124 time_t wtm_sec, sec = tv->tv_sec;
125 long wtm_nsec, nsec = tv->tv_nsec;
127 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
130 write_seqlock_irq(&xtime_lock);
132 * This is revolting. We need to set "xtime" correctly. However, the
133 * value in this location is the value at the most recent update of
134 * wall time. Discover what correction gettimeofday() would have
135 * done, and then undo it!
137 nsec -= system_timer->offset() * NSEC_PER_USEC;
139 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
140 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
142 set_normalized_timespec(&xtime, sec, nsec);
143 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
146 write_sequnlock_irq(&xtime_lock);
151 EXPORT_SYMBOL(do_settimeofday);
152 #endif /* !CONFIG_GENERIC_TIME */
154 #ifndef CONFIG_GENERIC_CLOCKEVENTS
156 * Kernel system timer support.
158 void timer_tick(void)
160 profile_tick(CPU_PROFILING);
162 write_seqlock(&xtime_lock);
164 write_sequnlock(&xtime_lock);
166 update_process_times(user_mode(get_irq_regs()));
171 #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS)
172 static int timer_suspend(struct sys_device *dev, pm_message_t state)
174 struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
176 if (timer->suspend != NULL)
182 static int timer_resume(struct sys_device *dev)
184 struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
186 if (timer->resume != NULL)
192 #define timer_suspend NULL
193 #define timer_resume NULL
196 static struct sysdev_class timer_sysclass = {
198 .suspend = timer_suspend,
199 .resume = timer_resume,
202 static int __init timer_init_sysfs(void)
204 int ret = sysdev_class_register(&timer_sysclass);
206 system_timer->dev.cls = &timer_sysclass;
207 ret = sysdev_register(&system_timer->dev);
213 device_initcall(timer_init_sysfs);
215 void __init time_init(void)
217 #ifndef CONFIG_GENERIC_TIME
218 if (system_timer->offset == NULL)
219 system_timer->offset = dummy_gettimeoffset;
221 system_timer->init();