Linux-2.6.12-rc2

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

/*
 * Copyright 2001 MontaVista Software Inc.
 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
 * Copyright (c) 2003, 2004  Maciej W. Rozycki
 *
 * Common time service routines for MIPS machines. See
 * Documentation/mips/time.README.
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/param.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/module.h>

#include <asm/bootinfo.h>
#include <asm/compiler.h>
#include <asm/cpu.h>
#include <asm/cpu-features.h>
#include <asm/div64.h>
#include <asm/sections.h>
#include <asm/time.h>

/*
 * The integer part of the number of usecs per jiffy is taken from tick,
 * but the fractional part is not recorded, so we calculate it using the
 * initial value of HZ.  This aids systems where tick isn't really an
 * integer (e.g. for HZ = 128).
 */
#define USECS_PER_JIFFY         TICK_SIZE
#define USECS_PER_JIFFY_FRAC    ((unsigned long)(u32)((1000000ULL << 32) / HZ))

#define TICK_SIZE       (tick_nsec / 1000)

u64 jiffies_64 = INITIAL_JIFFIES;

EXPORT_SYMBOL(jiffies_64);

/*
 * forward reference
 */
extern volatile unsigned long wall_jiffies;

DEFINE_SPINLOCK(rtc_lock);

/*
 * By default we provide the null RTC ops
 */
static unsigned long null_rtc_get_time(void)
{
        return mktime(2000, 1, 1, 0, 0, 0);
}

static int null_rtc_set_time(unsigned long sec)
{
        return 0;
}

unsigned long (*rtc_get_time)(void) = null_rtc_get_time;
int (*rtc_set_time)(unsigned long) = null_rtc_set_time;
int (*rtc_set_mmss)(unsigned long);


/* usecs per counter cycle, shifted to left by 32 bits */
static unsigned int sll32_usecs_per_cycle;

/* how many counter cycles in a jiffy */
static unsigned long cycles_per_jiffy;

/* Cycle counter value at the previous timer interrupt.. */
static unsigned int timerhi, timerlo;

/* expirelo is the count value for next CPU timer interrupt */
static unsigned int expirelo;


/*
 * Null timer ack for systems not needing one (e.g. i8254).
 */
static void null_timer_ack(void) { /* nothing */ }

/*
 * Null high precision timer functions for systems lacking one.
 */
static unsigned int null_hpt_read(void)
{
        return 0;
}

static void null_hpt_init(unsigned int count) { /* nothing */ }


/*
 * Timer ack for an R4k-compatible timer of a known frequency.
 */
static void c0_timer_ack(void)
{
        unsigned int count;

        /* Ack this timer interrupt and set the next one.  */
        expirelo += cycles_per_jiffy;
        write_c0_compare(expirelo);

        /* Check to see if we have missed any timer interrupts.  */
        count = read_c0_count();
        if ((count - expirelo) < 0x7fffffff) {
                /* missed_timer_count++; */
                expirelo = count + cycles_per_jiffy;
                write_c0_compare(expirelo);
        }
}

/*
 * High precision timer functions for a R4k-compatible timer.
 */
static unsigned int c0_hpt_read(void)
{
        return read_c0_count();
}

/* For use solely as a high precision timer.  */
static void c0_hpt_init(unsigned int count)
{
        write_c0_count(read_c0_count() - count);
}

/* For use both as a high precision timer and an interrupt source.  */
static void c0_hpt_timer_init(unsigned int count)
{
        count = read_c0_count() - count;
        expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
        write_c0_count(expirelo - cycles_per_jiffy);
        write_c0_compare(expirelo);
        write_c0_count(count);
}

int (*mips_timer_state)(void);
void (*mips_timer_ack)(void);
unsigned int (*mips_hpt_read)(void);
void (*mips_hpt_init)(unsigned int);


/*
 * This version of gettimeofday has microsecond resolution and better than
 * microsecond precision on fast machines with cycle counter.
 */
void do_gettimeofday(struct timeval *tv)
{
        unsigned long seq;
        unsigned long lost;
        unsigned long usec, sec;
        unsigned long max_ntp_tick = tick_usec - tickadj;

        do {
                seq = read_seqbegin(&xtime_lock);

                usec = do_gettimeoffset();

                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)) {
                        usec = min(usec, max_ntp_tick);

                        if (lost)
                                usec += lost * max_ntp_tick;
                } else if (unlikely(lost))
                        usec += lost * tick_usec;

                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 -= do_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);

/*
 * Gettimeoffset routines.  These routines returns the time duration
 * since last timer interrupt in usecs.
 *
 * If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
 * Otherwise use calibrate_gettimeoffset()
 *
 * If the CPU does not have the counter register, you can either supply
 * your own gettimeoffset() routine, or use null_gettimeoffset(), which
 * gives the same resolution as HZ.
 */

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


/* The function pointer to one of the gettimeoffset funcs.  */
unsigned long (*do_gettimeoffset)(void) = null_gettimeoffset;


static unsigned long fixed_rate_gettimeoffset(void)
{
        u32 count;
        unsigned long res;

        /* Get last timer tick in absolute kernel time */
        count = mips_hpt_read();

        /* .. relative to previous jiffy (32 bits is enough) */
        count -= timerlo;

        __asm__("multu  %1,%2"
                : "=h" (res)
                : "r" (count), "r" (sll32_usecs_per_cycle)
                : "lo", GCC_REG_ACCUM);

        /*
         * Due to possible jiffies inconsistencies, we need to check
         * the result so that we'll get a timer that is monotonic.
         */
        if (res >= USECS_PER_JIFFY)
                res = USECS_PER_JIFFY - 1;

        return res;
}


/*
 * Cached "1/(clocks per usec) * 2^32" value.
 * It has to be recalculated once each jiffy.
 */
static unsigned long cached_quotient;

/* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
static unsigned long last_jiffies;

/*
 * This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
 */
static unsigned long calibrate_div32_gettimeoffset(void)
{
        u32 count;
        unsigned long res, tmp;
        unsigned long quotient;

        tmp = jiffies;

        quotient = cached_quotient;

        if (last_jiffies != tmp) {
                last_jiffies = tmp;
                if (last_jiffies != 0) {
                        unsigned long r0;
                        do_div64_32(r0, timerhi, timerlo, tmp);
                        do_div64_32(quotient, USECS_PER_JIFFY,
                                    USECS_PER_JIFFY_FRAC, r0);
                        cached_quotient = quotient;
                }
        }

        /* Get last timer tick in absolute kernel time */
        count = mips_hpt_read();

        /* .. relative to previous jiffy (32 bits is enough) */
        count -= timerlo;

        __asm__("multu  %1,%2"
                : "=h" (res)
                : "r" (count), "r" (quotient)
                : "lo", GCC_REG_ACCUM);

        /*
         * Due to possible jiffies inconsistencies, we need to check
         * the result so that we'll get a timer that is monotonic.
         */
        if (res >= USECS_PER_JIFFY)
                res = USECS_PER_JIFFY - 1;

        return res;
}

static unsigned long calibrate_div64_gettimeoffset(void)
{
        u32 count;
        unsigned long res, tmp;
        unsigned long quotient;

        tmp = jiffies;

        quotient = cached_quotient;

        if (last_jiffies != tmp) {
                last_jiffies = tmp;
                if (last_jiffies) {
                        unsigned long r0;
                        __asm__(".set   push\n\t"
                                ".set   mips3\n\t"
                                "lwu    %0,%3\n\t"
                                "dsll32 %1,%2,0\n\t"
                                "or     %1,%1,%0\n\t"
                                "ddivu  $0,%1,%4\n\t"
                                "mflo   %1\n\t"
                                "dsll32 %0,%5,0\n\t"
                                "or     %0,%0,%6\n\t"
                                "ddivu  $0,%0,%1\n\t"
                                "mflo   %0\n\t"
                                ".set   pop"
                                : "=&r" (quotient), "=&r" (r0)
                                : "r" (timerhi), "m" (timerlo),
                                  "r" (tmp), "r" (USECS_PER_JIFFY),
                                  "r" (USECS_PER_JIFFY_FRAC)
                                : "hi", "lo", GCC_REG_ACCUM);
                        cached_quotient = quotient;
                }
        }

        /* Get last timer tick in absolute kernel time */
        count = mips_hpt_read();

        /* .. relative to previous jiffy (32 bits is enough) */
        count -= timerlo;

        __asm__("multu  %1,%2"
                : "=h" (res)
                : "r" (count), "r" (quotient)
                : "lo", GCC_REG_ACCUM);

        /*
         * Due to possible jiffies inconsistencies, we need to check
         * the result so that we'll get a timer that is monotonic.
         */
        if (res >= USECS_PER_JIFFY)
                res = USECS_PER_JIFFY - 1;

        return res;
}


/* last time when xtime and rtc are sync'ed up */
static long last_rtc_update;

/*
 * local_timer_interrupt() does profiling and process accounting
 * on a per-CPU basis.
 *
 * In UP mode, it is invoked from the (global) timer_interrupt.
 *
 * In SMP mode, it might invoked by per-CPU timer interrupt, or
 * a broadcasted inter-processor interrupt which itself is triggered
 * by the global timer interrupt.
 */
void local_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
        if (current->pid)
                profile_tick(CPU_PROFILING, regs);
        update_process_times(user_mode(regs));
}

/*
 * High-level timer interrupt service routines.  This function
 * is set as irqaction->handler and is invoked through do_IRQ.
 */
irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
        unsigned long j;
        unsigned int count;

        count = mips_hpt_read();
        mips_timer_ack();

        /* Update timerhi/timerlo for intra-jiffy calibration. */
        timerhi += count < timerlo;                     /* Wrap around */
        timerlo = count;

        /*
         * call the generic timer interrupt handling
         */
        do_timer(regs);

        /*
         * If we have an externally synchronized Linux clock, then update
         * CMOS clock accordingly every ~11 minutes. rtc_set_time() has to be
         * called as close as possible to 500 ms before the new second starts.
         */
        write_seqlock(&xtime_lock);
        if ((time_status & STA_UNSYNC) == 0 &&
            xtime.tv_sec > last_rtc_update + 660 &&
            (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
            (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
                if (rtc_set_mmss(xtime.tv_sec) == 0) {
                        last_rtc_update = xtime.tv_sec;
                } else {
                        /* do it again in 60 s */
                        last_rtc_update = xtime.tv_sec - 600;
                }
        }
        write_sequnlock(&xtime_lock);

        /*
         * If jiffies has overflown in this timer_interrupt, we must
         * update the timer[hi]/[lo] to make fast gettimeoffset funcs
         * quotient calc still valid. -arca
         *
         * The first timer interrupt comes late as interrupts are
         * enabled long after timers are initialized.  Therefore the
         * high precision timer is fast, leading to wrong gettimeoffset()
         * calculations.  We deal with it by setting it based on the
         * number of its ticks between the second and the third interrupt.
         * That is still somewhat imprecise, but it's a good estimate.
         * --macro
         */
        j = jiffies;
        if (j < 4) {
                static unsigned int prev_count;
                static int hpt_initialized;

                switch (j) {
                case 0:
                        timerhi = timerlo = 0;
                        mips_hpt_init(count);
                        break;
                case 2:
                        prev_count = count;
                        break;
                case 3:
                        if (!hpt_initialized) {
                                unsigned int c3 = 3 * (count - prev_count);

                                timerhi = 0;
                                timerlo = c3;
                                mips_hpt_init(count - c3);
                                hpt_initialized = 1;
                        }
                        break;
                default:
                        break;
                }
        }

        /*
         * In UP mode, we call local_timer_interrupt() to do profiling
         * and process accouting.
         *
         * In SMP mode, local_timer_interrupt() is invoked by appropriate
         * low-level local timer interrupt handler.
         */
        local_timer_interrupt(irq, dev_id, regs);

        return IRQ_HANDLED;
}

asmlinkage void ll_timer_interrupt(int irq, struct pt_regs *regs)
{
        irq_enter();
        kstat_this_cpu.irqs[irq]++;

        /* we keep interrupt disabled all the time */
        timer_interrupt(irq, NULL, regs);

        irq_exit();
}

asmlinkage void ll_local_timer_interrupt(int irq, struct pt_regs *regs)
{
        irq_enter();
        if (smp_processor_id() != 0)
                kstat_this_cpu.irqs[irq]++;

        /* we keep interrupt disabled all the time */
        local_timer_interrupt(irq, NULL, regs);

        irq_exit();
}

/*
 * time_init() - it does the following things.
 *
 * 1) board_time_init() -
 *      a) (optional) set up RTC routines,
 *      b) (optional) calibrate and set the mips_hpt_frequency
 *          (only needed if you intended to use fixed_rate_gettimeoffset
 *           or use cpu counter as timer interrupt source)
 * 2) setup xtime based on rtc_get_time().
 * 3) choose a appropriate gettimeoffset routine.
 * 4) calculate a couple of cached variables for later usage
 * 5) board_timer_setup() -
 *      a) (optional) over-write any choices made above by time_init().
 *      b) machine specific code should setup the timer irqaction.
 *      c) enable the timer interrupt
 */

void (*board_time_init)(void);
void (*board_timer_setup)(struct irqaction *irq);

unsigned int mips_hpt_frequency;

static struct irqaction timer_irqaction = {
        .handler = timer_interrupt,
        .flags = SA_INTERRUPT,
        .name = "timer",
};

static unsigned int __init calibrate_hpt(void)
{
        u64 frequency;
        u32 hpt_start, hpt_end, hpt_count, hz;

        const int loops = HZ / 10;
        int log_2_loops = 0;
        int i;

        /*
         * We want to calibrate for 0.1s, but to avoid a 64-bit
         * division we round the number of loops up to the nearest
         * power of 2.
         */
        while (loops > 1 << log_2_loops)
                log_2_loops++;
        i = 1 << log_2_loops;

        /*
         * Wait for a rising edge of the timer interrupt.
         */
        while (mips_timer_state());
        while (!mips_timer_state());

        /*
         * Now see how many high precision timer ticks happen
         * during the calculated number of periods between timer
         * interrupts.
         */
        hpt_start = mips_hpt_read();
        do {
                while (mips_timer_state());
                while (!mips_timer_state());
        } while (--i);
        hpt_end = mips_hpt_read();

        hpt_count = hpt_end - hpt_start;
        hz = HZ;
        frequency = (u64)hpt_count * (u64)hz;

        return frequency >> log_2_loops;
}

void __init time_init(void)
{
        if (board_time_init)
                board_time_init();

        if (!rtc_set_mmss)
                rtc_set_mmss = rtc_set_time;

        xtime.tv_sec = rtc_get_time();
        xtime.tv_nsec = 0;

        set_normalized_timespec(&wall_to_monotonic,
                                -xtime.tv_sec, -xtime.tv_nsec);

        /* Choose appropriate high precision timer routines.  */
        if (!cpu_has_counter && !mips_hpt_read) {
                /* No high precision timer -- sorry.  */
                mips_hpt_read = null_hpt_read;
                mips_hpt_init = null_hpt_init;
        } else if (!mips_hpt_frequency && !mips_timer_state) {
                /* A high precision timer of unknown frequency.  */
                if (!mips_hpt_read) {
                        /* No external high precision timer -- use R4k.  */
                        mips_hpt_read = c0_hpt_read;
                        mips_hpt_init = c0_hpt_init;
                }

                if ((current_cpu_data.isa_level == MIPS_CPU_ISA_M32) ||
                         (current_cpu_data.isa_level == MIPS_CPU_ISA_I) ||
                         (current_cpu_data.isa_level == MIPS_CPU_ISA_II))
                        /*
                         * We need to calibrate the counter but we don't have
                         * 64-bit division.
                         */
                        do_gettimeoffset = calibrate_div32_gettimeoffset;
                else
                        /*
                         * We need to calibrate the counter but we *do* have
                         * 64-bit division.
                         */
                        do_gettimeoffset = calibrate_div64_gettimeoffset;
        } else {
                /* We know counter frequency.  Or we can get it.  */
                if (!mips_hpt_read) {
                        /* No external high precision timer -- use R4k.  */
                        mips_hpt_read = c0_hpt_read;

                        if (mips_timer_state)
                                mips_hpt_init = c0_hpt_init;
                        else {
                                /* No external timer interrupt -- use R4k.  */
                                mips_hpt_init = c0_hpt_timer_init;
                                mips_timer_ack = c0_timer_ack;
                        }
                }
                if (!mips_hpt_frequency)
                        mips_hpt_frequency = calibrate_hpt();

                do_gettimeoffset = fixed_rate_gettimeoffset;

                /* Calculate cache parameters.  */
                cycles_per_jiffy = (mips_hpt_frequency + HZ / 2) / HZ;

                /* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq  */
                do_div64_32(sll32_usecs_per_cycle,
                            1000000, mips_hpt_frequency / 2,
                            mips_hpt_frequency);

                /* Report the high precision timer rate for a reference.  */
                printk("Using %u.%03u MHz high precision timer.\n",
                       ((mips_hpt_frequency + 500) / 1000) / 1000,
                       ((mips_hpt_frequency + 500) / 1000) % 1000);
        }

        if (!mips_timer_ack)
                /* No timer interrupt ack (e.g. i8254).  */
                mips_timer_ack = null_timer_ack;

        /* This sets up the high precision timer for the first interrupt.  */
        mips_hpt_init(mips_hpt_read());

        /*
         * Call board specific timer interrupt setup.
         *
         * this pointer must be setup in machine setup routine.
         *
         * Even if a machine chooses to use a low-level timer interrupt,
         * it still needs to setup the timer_irqaction.
         * In that case, it might be better to set timer_irqaction.handler
         * to be NULL function so that we are sure the high-level code
         * is not invoked accidentally.
         */
        board_timer_setup(&timer_irqaction);
}

#define FEBRUARY                2
#define STARTOFTIME             1970
#define SECDAY                  86400L
#define SECYR                   (SECDAY * 365)
#define leapyear(y)             ((!((y) % 4) && ((y) % 100)) || !((y) % 400))
#define days_in_year(y)         (leapyear(y) ? 366 : 365)
#define days_in_month(m)        (month_days[(m) - 1])

static int month_days[12] = {
        31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};

void to_tm(unsigned long tim, struct rtc_time *tm)
{
        long hms, day, gday;
        int i;

        gday = day = tim / SECDAY;
        hms = tim % SECDAY;

        /* Hours, minutes, seconds are easy */
        tm->tm_hour = hms / 3600;
        tm->tm_min = (hms % 3600) / 60;
        tm->tm_sec = (hms % 3600) % 60;

        /* Number of years in days */
        for (i = STARTOFTIME; day >= days_in_year(i); i++)
                day -= days_in_year(i);
        tm->tm_year = i;

        /* Number of months in days left */
        if (leapyear(tm->tm_year))
                days_in_month(FEBRUARY) = 29;
        for (i = 1; day >= days_in_month(i); i++)
                day -= days_in_month(i);
        days_in_month(FEBRUARY) = 28;
        tm->tm_mon = i - 1;             /* tm_mon starts from 0 to 11 */

        /* Days are what is left over (+1) from all that. */
        tm->tm_mday = day + 1;

        /*
         * Determine the day of week
         */
        tm->tm_wday = (gday + 4) % 7;   /* 1970/1/1 was Thursday */
}

EXPORT_SYMBOL(rtc_lock);
EXPORT_SYMBOL(to_tm);
EXPORT_SYMBOL(rtc_set_time);
EXPORT_SYMBOL(rtc_get_time);

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