time.c

优龙2410linux2.6.8内核源代码

/*
 *  linux/arch/h8300/kernel/time.c
 *
 *  Yoshinori Sato <[e-mail]>
 *
 *  Copied/hacked from:
 *
 *  linux/arch/m68k/kernel/time.c
 *
 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
 *
 * This file contains the m68k-specific time handling details.
 * Most of the stuff is located in the machine specific files.
 *
 * 1997-09-10	Updated NTP code according to technical memorandum Jan '96
 *		"A Kernel Model for Precision Timekeeping" by Dave Mills
 */

#include <linux/config.h> /* CONFIG_HEARTBEAT */
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/timex.h>
#include <linux/profile.h>

#include <asm/io.h>
#include <asm/target_time.h>

#define	TICK_SIZE (tick_nsec / 1000)

u64 jiffies_64;

EXPORT_SYMBOL(jiffies_64);

static inline void do_profile (unsigned long pc)
{
	if (prof_buffer && current->pid) {
		extern int _stext;
		pc -= (unsigned long) &_stext;
		pc >>= prof_shift;
		if (pc < prof_len)
			++prof_buffer[pc];
		else
		/*
		 * Don't ignore out-of-bounds PC values silently,
		 * put them into the last histogram slot, so if
		 * present, they will show up as a sharp peak.
		 */
			++prof_buffer[prof_len-1];
	}
}

/*
 * timer_interrupt() needs to keep up the real-time clock,
 * as well as call the "do_timer()" routine every clocktick
 */
static void timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
{
	/* may need to kick the hardware timer */
	platform_timer_eoi();

	do_timer(regs);

	if (!user_mode(regs))
		do_profile(regs->pc);

}

void time_init(void)
{
	unsigned int year, mon, day, hour, min, sec;

	/* FIX by dqg : Set to zero for platforms that don't have tod */
	/* without this time is undefined and can overflow time_t, causing  */
	/* very stange errors */
	year = 1980;
	mon = day = 1;
	hour = min = sec = 0;
	platform_gettod (&year, &mon, &day, &hour, &min, &sec);

	if ((year += 1900) < 1970)
		year += 100;
	xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
	xtime.tv_nsec = 0;

	platform_timer_setup(timer_interrupt);
}

/*
 * This version of gettimeofday has near microsecond resolution.
 */
void do_gettimeofday(struct timeval *tv)
{
	unsigned long flags;
	unsigned long usec, sec;

	read_lock_irqsave(&xtime_lock, flags);
	usec = 0;
	sec = xtime.tv_sec;
	usec += (xtime.tv_nsec / 1000);
	read_unlock_irqrestore(&xtime_lock, flags);

	while (usec >= 1000000) {
		usec -= 1000000;
		sec++;
	}

	tv->tv_sec = sec;
	tv->tv_usec = usec;
}

EXPORT_SYMBOL(do_gettimeofday);

int do_settimeofday(struct timespec *tv)
{
	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
		return -EINVAL;

	write_lock_irq(&xtime_lock);
	/* This is revolting. We need to set the xtime.tv_usec
	 * correctly. However, the value in this location is
	 * is value at the last tick.
	 * Discover what correction gettimeofday
	 * would have done, and then undo it!
	 */
	while (tv->tv_nsec < 0) {
		tv->tv_nsec += NSEC_PER_SEC;
		tv->tv_sec--;
	}

	xtime.tv_sec = tv->tv_sec;
	xtime.tv_nsec = tv->tv_nsec;
	time_adjust = 0;		/* stop active adjtime() */
	time_status |= STA_UNSYNC;
	time_maxerror = NTP_PHASE_LIMIT;
	time_esterror = NTP_PHASE_LIMIT;
	write_sequnlock_irq(&xtime_lock);
	clock_was_set();
	return 0;
}

EXPORT_SYMBOL(do_settimeofday);

unsigned long long sched_clock(void)
{
	return (unsigned long long)jiffies * (1000000000 / HZ);

}