time.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 400 行

/*
 *  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...
 *
 *  1994-07-02  Alan Modra
 *              fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
 *  1998-12-20  Updated NTP code according to technical memorandum Jan '96
 *              "A Kernel Model for Precision Timekeeping" by Dave Mills
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/timex.h>
#include <linux/errno.h>
#include <linux/profile.h>
#include <linux/sysdev.h>
#include <linux/timer.h>
#include <linux/hrtime.h>

#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/leds.h>
#include <asm/thread_info.h>
#include <asm/mach/time.h>

u64 jiffies_64 = INITIAL_JIFFIES;

EXPORT_SYMBOL(jiffies_64);

extern unsigned long wall_jiffies;

/* this needs a better home */
spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;

#ifdef CONFIG_SA1100_RTC_MODULE
EXPORT_SYMBOL(rtc_lock);
#endif

/* change this if you have some constant time drift */
#define USECS_PER_JIFFY	(1000000/HZ)

#ifdef CONFIG_SMP
unsigned long profile_pc(struct pt_regs *regs)
{
	unsigned long fp, pc = instruction_pointer(regs);

	if (in_lock_functions(pc)) {
		fp = thread_saved_fp(current);
		pc = pc_pointer(((unsigned long *)fp)[-1]);
	}

	return pc;
}
EXPORT_SYMBOL(profile_pc);
#endif

/*
 * hook for setting the RTC's idea of the current time.
 */
int (*set_rtc)(void);

static unsigned long dummy_gettimeoffset(void)
{
	return 0;
}

/*
 * hook for getting the time offset.  Note that it is
 * always called with interrupts disabled.
 */
unsigned long (*gettimeoffset)(void) = dummy_gettimeoffset;

/*
 * Scheduler clock - returns current time in nanosec units.
 * This is the default implementation.  Sub-architecture
 * implementations can override this.
 */
unsigned long long __attribute__((weak)) sched_clock(void)
{
	return (unsigned long long)jiffies * (1000000000 / HZ);
}

static unsigned long next_rtc_update;

/*
 * If we have an externally synchronized linux clock, then update
 * CMOS clock accordingly every ~11 minutes.  set_rtc() has to be
 * called as close as possible to 500 ms before the new second
 * starts.
 */
static inline void do_set_rtc(void)
{
	if (time_status & STA_UNSYNC || set_rtc == NULL)
		return;

	if (next_rtc_update &&
	    time_before((unsigned long)xtime.tv_sec, next_rtc_update))
		return;

	if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) &&
	    xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1))
		return;

	if (set_rtc())
		/*
		 * rtc update failed.  Try again in 60s
		 */
		next_rtc_update = xtime.tv_sec + 60;
	else
		next_rtc_update = xtime.tv_sec + 660;
}

#ifdef CONFIG_LEDS

static void dummy_leds_event(led_event_t evt)
{
}

void (*leds_event)(led_event_t) = dummy_leds_event;

struct leds_evt_name {
	const char	name[8];
	int		on;
	int		off;
};

static const struct leds_evt_name evt_names[] = {
	{ "amber", led_amber_on, led_amber_off },
	{ "blue",  led_blue_on,  led_blue_off  },
	{ "green", led_green_on, led_green_off },
	{ "red",   led_red_on,   led_red_off   },
};

static ssize_t leds_store(struct sys_device *dev, const char *buf, size_t size)
{
	int ret = -EINVAL, len = strcspn(buf, " ");

	if (len > 0 && buf[len] == '\0')
		len--;

	if (strncmp(buf, "claim", len) == 0) {
		leds_event(led_claim);
		ret = size;
	} else if (strncmp(buf, "release", len) == 0) {
		leds_event(led_release);
		ret = size;
	} else {
		int i;

		for (i = 0; i < ARRAY_SIZE(evt_names); i++) {
			if (strlen(evt_names[i].name) != len ||
			    strncmp(buf, evt_names[i].name, len) != 0)
				continue;
			if (strncmp(buf+len, " on", 3) == 0) {
				leds_event(evt_names[i].on);
				ret = size;
			} else if (strncmp(buf+len, " off", 4) == 0) {
				leds_event(evt_names[i].off);
				ret = size;
			}
			break;
		}
	}
	return ret;
}

static SYSDEV_ATTR(event, 0200, NULL, leds_store);

static int leds_suspend(struct sys_device *dev, u32 state)
{
	leds_event(led_stop);
	return 0;
}

static int leds_resume(struct sys_device *dev)
{
	leds_event(led_start);
	return 0;
}

static int leds_shutdown(struct sys_device *dev)
{
	leds_event(led_halted);
	return 0;
}

static struct sysdev_class leds_sysclass = {
	set_kset_name("leds"),
	.shutdown	= leds_shutdown,
	.suspend	= leds_suspend,
	.resume		= leds_resume,
};

static struct sys_device leds_device = {
	.id		= 0,
	.cls		= &leds_sysclass,
};

static int __init leds_init(void)
{
	int ret;
	ret = sysdev_class_register(&leds_sysclass);
	if (ret == 0)
		ret = sysdev_register(&leds_device);
	if (ret == 0)
		ret = sysdev_create_file(&leds_device, &attr_event);
	return ret;
}

device_initcall(leds_init);

EXPORT_SYMBOL(leds_event);
#endif

#ifdef CONFIG_LEDS_TIMER
static inline void do_leds(void)
{
	static unsigned int count = 50;

	if (--count == 0) {
		count = 50;
		leds_event(led_timer);
	}
}
#else
#define	do_leds()
#endif

#ifdef CONFIG_HIGH_RES_TIMERS
void do_gettimeofday(struct timeval *tv)
{
        unsigned long flags;
        unsigned long seq;
        unsigned long sec, nsec, clk_nsec;
        unsigned long max_ntp_tick;

        do {
                seq = read_seqbegin_irqsave(&xtime_lock, flags);

                nsec = arch_cycle_to_nsec(get_arch_cycles(wall_jiffies));

                sec = xtime.tv_sec;
                clk_nsec = xtime.tv_nsec;
        } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));

        /* usec may have gone up a lot: be safe */
/*
         * If time_adjust is negative then NTP is slowing the clock
         * so make sure not to go into next possible interval.
         * Better to lose some accuracy than have time go backwards..

         * Note, in this kernel wall_jiffies and jiffies will always
         * be the same, at least under the lock.
         */
        if (unlikely(time_adjust < 0)) {
                max_ntp_tick = tick_nsec - (tickadj * NSEC_PER_USEC);
                if (max_ntp_tick > nsec)
                        nsec = max_ntp_tick - nsec;
        }

        nsec += clk_nsec;

        while (nsec >= NSEC_PER_SEC) {
                nsec -=  NSEC_PER_SEC;
                sec++;
        }

        tv->tv_sec = sec;
        tv->tv_usec = nsec / NSEC_PER_USEC;
}
#else
void do_gettimeofday(struct timeval *tv)
{
	unsigned long flags;
	unsigned long seq;
	unsigned long usec, sec, lost;

	do {
		seq = read_seqbegin_irqsave(&xtime_lock, flags);
		usec = gettimeoffset();

		lost = jiffies - wall_jiffies;
		if (lost)
			usec += lost * USECS_PER_JIFFY;

		sec = xtime.tv_sec;
		usec += xtime.tv_nsec / 1000;
	} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));

	/* usec may have gone up a lot: be safe */
	while (usec >= 1000000) {
		usec -= 1000000;
		sec++;
	}

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

EXPORT_SYMBOL(do_gettimeofday);

int do_settimeofday(struct timespec *tv)
{
	time_t wtm_sec, sec = tv->tv_sec;
	long wtm_nsec, nsec = tv->tv_nsec;

	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
		return -EINVAL;

	write_seqlock_irq(&xtime_lock);
	/*
	 * This is revolting. We need to set "xtime" correctly. However, the
	 * value in this location is the value at the most recent update of
	 * wall time.  Discover what correction gettimeofday() would have
	 * done, and then undo it!
	 */
	nsec -= gettimeoffset() * NSEC_PER_USEC;
	nsec -= (jiffies - wall_jiffies) * TICK_NSEC;

	wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
	wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);

	set_normalized_timespec(&xtime, sec, nsec);
	set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_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);

/**
 * save_time_delta - Save the offset between system time and RTC time
 * @delta: pointer to timespec to store delta
 * @rtc: pointer to timespec for current RTC time
 *
 * Return a delta between the system time and the RTC time, such
 * that system time can be restored later with restore_time_delta()
 */
void save_time_delta(struct timespec *delta, struct timespec *rtc)
{
	set_normalized_timespec(delta,
				xtime.tv_sec - rtc->tv_sec,
				xtime.tv_nsec - rtc->tv_nsec);
}
EXPORT_SYMBOL(save_time_delta);

/**
 * restore_time_delta - Restore the current system time
 * @delta: delta returned by save_time_delta()
 * @rtc: pointer to timespec for current RTC time
 */
void restore_time_delta(struct timespec *delta, struct timespec *rtc)
{
	struct timespec ts;

	set_normalized_timespec(&ts,
				delta->tv_sec + rtc->tv_sec,
				delta->tv_nsec + rtc->tv_nsec);

	do_settimeofday(&ts);
}
EXPORT_SYMBOL(restore_time_delta);

void timer_tick(struct pt_regs *regs)
{
	profile_tick(CPU_PROFILING, regs);
	do_leds();
	do_set_rtc();
	do_timer(regs);
}

void (*init_arch_time)(void);

void __init time_init(void)
{
	init_arch_time();
}