/* *  linux/arch/arm/kernel/time.c * *  Copyright (C) 1991, 1992, 1995  Linus Torvalds *  Modifications for ARM (C) 1994-2001 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * *  This file contains the ARM-specific time handling details: *  reading the RTC at bootup, etc... */#include <linux/export.h>#include <linux/kernel.h>#include <linux/interrupt.h>#include <linux/time.h>#include <linux/init.h>#include <linux/sched.h>#include <linux/smp.h>#include <linux/timex.h>#include <linux/errno.h>#include <linux/profile.h>#include <linux/syscore_ops.h>#include <linux/timer.h>#include <linux/irq.h> #include <asm/leds.h>#include <asm/thread_info.h>#include <asm/sched_clock.h>#include <asm/stacktrace.h>#include <asm/mach/arch.h>#include <asm/mach/time.h> /* * Our system timer. */static struct sys_timer *system_timer; #if defined(CONFIG_RTC_DRV_CMOS) || defined(CONFIG_RTC_DRV_CMOS_MODULE) || \    defined(CONFIG_NVRAM) || defined(CONFIG_NVRAM_MODULE)/* this needs a better home */DEFINE_SPINLOCK(rtc_lock);EXPORT_SYMBOL(rtc_lock);#endif	/* pc-style 'CMOS' RTC support */ /* change this if you have some constant time drift */#define USECS_PER_JIFFY	(1000000/HZ) #ifdef CONFIG_SMPunsigned long profile_pc(struct pt_regs *regs){	struct stackframe frame; 	if (!in_lock_functions(regs->ARM_pc))		return regs->ARM_pc; 	frame.fp = regs->ARM_fp;	frame.sp = regs->ARM_sp;	frame.lr = regs->ARM_lr;	frame.pc = regs->ARM_pc;	do {		int ret = unwind_frame(&frame);		if (ret < 0)			return 0;	} while (in_lock_functions(frame.pc)); 	return frame.pc;}EXPORT_SYMBOL(profile_pc);#endif #ifdef CONFIG_ARCH_USES_GETTIMEOFFSETu32 arch_gettimeoffset(void){	if (system_timer->offset != NULL)		return system_timer->offset() * 1000; 	return 0;}#endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */ #ifdef CONFIG_LEDS_TIMERstatic inline void do_leds(void){	static unsigned int count = HZ/2; 	if (--count == 0) {		count = HZ/2;		leds_event(led_timer);	}}#else#define	do_leds()#endif  #ifndef CONFIG_GENERIC_CLOCKEVENTS/* * Kernel system timer support. */void timer_tick(void){	profile_tick(CPU_PROFILING);	do_leds();	xtime_update(1);#ifndef CONFIG_SMP	update_process_times(user_mode(get_irq_regs()));#endif}#endif static void dummy_clock_access(struct timespec *ts){	ts->tv_sec = 0;	ts->tv_nsec = 0;} static clock_access_fn __read_persistent_clock = dummy_clock_access;static clock_access_fn __read_boot_clock = dummy_clock_access;; void read_persistent_clock(struct timespec *ts){	__read_persistent_clock(ts);} void read_boot_clock(struct timespec *ts){	__read_boot_clock(ts);} int __init register_persistent_clock(clock_access_fn read_boot,				     clock_access_fn read_persistent){	/* Only allow the clockaccess functions to be registered once */	if (__read_persistent_clock == dummy_clock_access &&	    __read_boot_clock == dummy_clock_access) {		if (read_boot)			__read_boot_clock = read_boot;		if (read_persistent)			__read_persistent_clock = read_persistent; 		return 0;	} 	return -EINVAL;} #if defined(CONFIG_PM) && !defined(CONFIG_GENERIC_CLOCKEVENTS)static int timer_suspend(void){	if (system_timer->suspend)		system_timer->suspend(); 	return 0;} static void timer_resume(void){	if (system_timer->resume)		system_timer->resume();}#else#define timer_suspend NULL#define timer_resume NULL#endif static struct syscore_ops timer_syscore_ops = {	.suspend	= timer_suspend,	.resume		= timer_resume,}; static int __init timer_init_syscore_ops(void){	register_syscore_ops(&timer_syscore_ops); 	return 0;} device_initcall(timer_init_syscore_ops); void __init time_init(void){	system_timer = machine_desc->timer;	system_timer->init();	sched_clock_postinit();}