Linux-2.6.12-rc2

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / arch / i386 / kernel / time.c

/*
 *  linux/arch/i386/kernel/time.c
 *
 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
 *
 * This file contains the PC-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
 * 1995-03-26    Markus Kuhn
 *      fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
 *      precision CMOS clock update
 * 1996-05-03    Ingo Molnar
 *      fixed time warps in do_[slow|fast]_gettimeoffset()
 * 1997-09-10   Updated NTP code according to technical memorandum Jan '96
 *              "A Kernel Model for Precision Timekeeping" by Dave Mills
 * 1998-09-05    (Various)
 *      More robust do_fast_gettimeoffset() algorithm implemented
 *      (works with APM, Cyrix 6x86MX and Centaur C6),
 *      monotonic gettimeofday() with fast_get_timeoffset(),
 *      drift-proof precision TSC calibration on boot
 *      (C. Scott Ananian <cananian@alumni.princeton.edu>, Andrew D.
 *      Balsa <andrebalsa@altern.org>, Philip Gladstone <philip@raptor.com>;
 *      ported from 2.0.35 Jumbo-9 by Michael Krause <m.krause@tu-harburg.de>).
 * 1998-12-16    Andrea Arcangeli
 *      Fixed Jumbo-9 code in 2.1.131: do_gettimeofday was missing 1 jiffy
 *      because was not accounting lost_ticks.
 * 1998-12-24 Copyright (C) 1998  Andrea Arcangeli
 *      Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
 *      serialize accesses to xtime/lost_ticks).
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/module.h>
#include <linux/sysdev.h>
#include <linux/bcd.h>
#include <linux/efi.h>
#include <linux/mca.h>

#include <asm/io.h>
#include <asm/smp.h>
#include <asm/irq.h>
#include <asm/msr.h>
#include <asm/delay.h>
#include <asm/mpspec.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
#include <asm/timer.h>

#include "mach_time.h"

#include <linux/timex.h>
#include <linux/config.h>

#include <asm/hpet.h>

#include <asm/arch_hooks.h>

#include "io_ports.h"

extern spinlock_t i8259A_lock;
int pit_latch_buggy;              /* extern */

#include "do_timer.h"

u64 jiffies_64 = INITIAL_JIFFIES;

EXPORT_SYMBOL(jiffies_64);

unsigned long cpu_khz;  /* Detected as we calibrate the TSC */

extern unsigned long wall_jiffies;

DEFINE_SPINLOCK(rtc_lock);

DEFINE_SPINLOCK(i8253_lock);
EXPORT_SYMBOL(i8253_lock);

struct timer_opts *cur_timer = &timer_none;

/*
 * This is a special lock that is owned by the CPU and holds the index
 * register we are working with.  It is required for NMI access to the
 * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
 */
volatile unsigned long cmos_lock = 0;
EXPORT_SYMBOL(cmos_lock);

/* Routines for accessing the CMOS RAM/RTC. */
unsigned char rtc_cmos_read(unsigned char addr)
{
        unsigned char val;
        lock_cmos_prefix(addr);
        outb_p(addr, RTC_PORT(0));
        val = inb_p(RTC_PORT(1));
        lock_cmos_suffix(addr);
        return val;
}
EXPORT_SYMBOL(rtc_cmos_read);

void rtc_cmos_write(unsigned char val, unsigned char addr)
{
        lock_cmos_prefix(addr);
        outb_p(addr, RTC_PORT(0));
        outb_p(val, RTC_PORT(1));
        lock_cmos_suffix(addr);
}
EXPORT_SYMBOL(rtc_cmos_write);

/*
 * This version of gettimeofday has microsecond resolution
 * and better than microsecond precision on fast x86 machines with TSC.
 */
void do_gettimeofday(struct timeval *tv)
{
        unsigned long seq;
        unsigned long usec, sec;
        unsigned long max_ntp_tick;

        do {
                unsigned long lost;

                seq = read_seqbegin(&xtime_lock);

                usec = cur_timer->get_offset();
                lost = jiffies - wall_jiffies;

                /*
                 * 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..
                 */
                if (unlikely(time_adjust < 0)) {
                        max_ntp_tick = (USEC_PER_SEC / HZ) - tickadj;
                        usec = min(usec, max_ntp_tick);

                        if (lost)
                                usec += lost * max_ntp_tick;
                }
                else if (unlikely(lost))
                        usec += lost * (USEC_PER_SEC / HZ);

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

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

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

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
         * made, and then undo it!
         */
        nsec -= cur_timer->get_offset() * 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);

static int set_rtc_mmss(unsigned long nowtime)
{
        int retval;

        WARN_ON(irqs_disabled());

        /* gets recalled with irq locally disabled */
        spin_lock_irq(&rtc_lock);
        if (efi_enabled)
                retval = efi_set_rtc_mmss(nowtime);
        else
                retval = mach_set_rtc_mmss(nowtime);
        spin_unlock_irq(&rtc_lock);

        return retval;
}


int timer_ack;

/* monotonic_clock(): returns # of nanoseconds passed since time_init()
 *              Note: This function is required to return accurate
 *              time even in the absence of multiple timer ticks.
 */
unsigned long long monotonic_clock(void)
{
        return cur_timer->monotonic_clock();
}
EXPORT_SYMBOL(monotonic_clock);

#if defined(CONFIG_SMP) && defined(CONFIG_FRAME_POINTER)
unsigned long profile_pc(struct pt_regs *regs)
{
        unsigned long pc = instruction_pointer(regs);

        if (in_lock_functions(pc))
                return *(unsigned long *)(regs->ebp + 4);

        return pc;
}
EXPORT_SYMBOL(profile_pc);
#endif

/*
 * timer_interrupt() needs to keep up the real-time clock,
 * as well as call the "do_timer()" routine every clocktick
 */
static inline void do_timer_interrupt(int irq, void *dev_id,
                                        struct pt_regs *regs)
{
#ifdef CONFIG_X86_IO_APIC
        if (timer_ack) {
                /*
                 * Subtle, when I/O APICs are used we have to ack timer IRQ
                 * manually to reset the IRR bit for do_slow_gettimeoffset().
                 * This will also deassert NMI lines for the watchdog if run
                 * on an 82489DX-based system.
                 */
                spin_lock(&i8259A_lock);
                outb(0x0c, PIC_MASTER_OCW3);
                /* Ack the IRQ; AEOI will end it automatically. */
                inb(PIC_MASTER_POLL);
                spin_unlock(&i8259A_lock);
        }
#endif

        do_timer_interrupt_hook(regs);


        if (MCA_bus) {
                /* The PS/2 uses level-triggered interrupts.  You can't
                turn them off, nor would you want to (any attempt to
                enable edge-triggered interrupts usually gets intercepted by a
                special hardware circuit).  Hence we have to acknowledge
                the timer interrupt.  Through some incredibly stupid
                design idea, the reset for IRQ 0 is done by setting the
                high bit of the PPI port B (0x61).  Note that some PS/2s,
                notably the 55SX, work fine if this is removed.  */

                irq = inb_p( 0x61 );    /* read the current state */
                outb_p( irq|0x80, 0x61 );       /* reset the IRQ */
        }
}

/*
 * This is the same as the above, except we _also_ save the current
 * Time Stamp Counter value at the time of the timer interrupt, so that
 * we later on can estimate the time of day more exactly.
 */
irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
        /*
         * Here we are in the timer irq handler. We just have irqs locally
         * disabled but we don't know if the timer_bh is running on the other
         * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
         * the irq version of write_lock because as just said we have irq
         * locally disabled. -arca
         */
        write_seqlock(&xtime_lock);

        cur_timer->mark_offset();
 
        do_timer_interrupt(irq, NULL, regs);

        write_sequnlock(&xtime_lock);
        return IRQ_HANDLED;
}

/* not static: needed by APM */
unsigned long get_cmos_time(void)
{
        unsigned long retval;

        spin_lock(&rtc_lock);

        if (efi_enabled)
                retval = efi_get_time();
        else
                retval = mach_get_cmos_time();

        spin_unlock(&rtc_lock);

        return retval;
}
static void sync_cmos_clock(unsigned long dummy);

static struct timer_list sync_cmos_timer =
                                      TIMER_INITIALIZER(sync_cmos_clock, 0, 0);

static void sync_cmos_clock(unsigned long dummy)
{
        struct timeval now, next;
        int fail = 1;

        /*
         * If we have an externally synchronized Linux clock, then update
         * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
         * called as close as possible to 500 ms before the new second starts.
         * This code is run on a timer.  If the clock is set, that timer
         * may not expire at the correct time.  Thus, we adjust...
         */
        if ((time_status & STA_UNSYNC) != 0)
                /*
                 * Not synced, exit, do not restart a timer (if one is
                 * running, let it run out).
                 */
                return;

        do_gettimeofday(&now);
        if (now.tv_usec >= USEC_AFTER - ((unsigned) TICK_SIZE) / 2 &&
            now.tv_usec <= USEC_BEFORE + ((unsigned) TICK_SIZE) / 2)
                fail = set_rtc_mmss(now.tv_sec);

        next.tv_usec = USEC_AFTER - now.tv_usec;
        if (next.tv_usec <= 0)
                next.tv_usec += USEC_PER_SEC;

        if (!fail)
                next.tv_sec = 659;
        else
                next.tv_sec = 0;

        if (next.tv_usec >= USEC_PER_SEC) {
                next.tv_sec++;
                next.tv_usec -= USEC_PER_SEC;
        }
        mod_timer(&sync_cmos_timer, jiffies + timeval_to_jiffies(&next));
}

void notify_arch_cmos_timer(void)
{
        mod_timer(&sync_cmos_timer, jiffies + 1);
}

static long clock_cmos_diff, sleep_start;

static int timer_suspend(struct sys_device *dev, u32 state)
{
        /*
         * Estimate time zone so that set_time can update the clock
         */
        clock_cmos_diff = -get_cmos_time();
        clock_cmos_diff += get_seconds();
        sleep_start = get_cmos_time();
        return 0;
}

static int timer_resume(struct sys_device *dev)
{
        unsigned long flags;
        unsigned long sec;
        unsigned long sleep_length;

#ifdef CONFIG_HPET_TIMER
        if (is_hpet_enabled())
                hpet_reenable();
#endif
        sec = get_cmos_time() + clock_cmos_diff;
        sleep_length = (get_cmos_time() - sleep_start) * HZ;
        write_seqlock_irqsave(&xtime_lock, flags);
        xtime.tv_sec = sec;
        xtime.tv_nsec = 0;
        write_sequnlock_irqrestore(&xtime_lock, flags);
        jiffies += sleep_length;
        wall_jiffies += sleep_length;
        return 0;
}

static struct sysdev_class timer_sysclass = {
        .resume = timer_resume,
        .suspend = timer_suspend,
        set_kset_name("timer"),
};


/* XXX this driverfs stuff should probably go elsewhere later -john */
static struct sys_device device_timer = {
        .id     = 0,
        .cls    = &timer_sysclass,
};

static int time_init_device(void)
{
        int error = sysdev_class_register(&timer_sysclass);
        if (!error)
                error = sysdev_register(&device_timer);
        return error;
}

device_initcall(time_init_device);

#ifdef CONFIG_HPET_TIMER
extern void (*late_time_init)(void);
/* Duplicate of time_init() below, with hpet_enable part added */
static void __init hpet_time_init(void)
{
        xtime.tv_sec = get_cmos_time();
        xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
        set_normalized_timespec(&wall_to_monotonic,
                -xtime.tv_sec, -xtime.tv_nsec);

        if (hpet_enable() >= 0) {
                printk("Using HPET for base-timer\n");
        }

        cur_timer = select_timer();
        printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name);

        time_init_hook();
}
#endif

void __init time_init(void)
{
#ifdef CONFIG_HPET_TIMER
        if (is_hpet_capable()) {
                /*
                 * HPET initialization needs to do memory-mapped io. So, let
                 * us do a late initialization after mem_init().
                 */
                late_time_init = hpet_time_init;
                return;
        }
#endif
        xtime.tv_sec = get_cmos_time();
        xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
        set_normalized_timespec(&wall_to_monotonic,
                -xtime.tv_sec, -xtime.tv_nsec);

        cur_timer = select_timer();
        printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name);

        time_init_hook();
}