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/*

 *

 * Common time routines among all ppc machines.

 *

 * Written by Cort Dougan (cort@cs.nmt.edu) to merge

 * Paul Mackerras' version and mine for PReP and Pmac.

 * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).

 * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)

 *

 * First round of bugfixes by Gabriel Paubert (paubert@iram.es)

 * to make clock more stable (2.4.0-test5). The only thing

 * that this code assumes is that the timebases have been synchronized

 * by firmware on SMP and are never stopped (never do sleep

 * on SMP then, nap and doze are OK).

 *

 * Speeded up do_gettimeofday by getting rid of references to

 * xtime (which required locks for consistency). (mikejc@us.ibm.com)

 *

 * TODO (not necessarily in this file):

 * - improve precision and reproducibility of timebase frequency

 * measurement at boot time. (for iSeries, we calibrate the timebase

 * against the Titan chip's clock.)

 * - for astronomical applications: add a new function to get

 * non ambiguous timestamps even around leap seconds. This needs

 * a new timestamp format and a good name.

 *

 * 1997-09-10  Updated NTP code according to technical memorandum Jan '96

 *             "A Kernel Model for Precision Timekeeping" by Dave Mills

 *

 *      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/config.h>

#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/timex.h>

#include <linux/kernel_stat.h>

#include <linux/mc146818rtc.h>

#include <linux/time.h>

#include <linux/init.h>

#include <asm/naca.h>

#include <asm/segment.h>

#include <asm/io.h>

#include <asm/processor.h>

#include <asm/nvram.h>

#include <asm/cache.h>

#include <asm/machdep.h>

#include <asm/init.h>

#ifdef CONFIG_PPC_ISERIES

#include <asm/iSeries/HvCallXm.h>

#endif

#include <asm/uaccess.h>

#include <asm/time.h>

#include <asm/ppcdebug.h>

void smp_local_timer_interrupt(struct pt_regs *);

extern void setup_before_console_init();

/* keep track of when we need to update the rtc */

time_t last_rtc_update;

extern rwlock_t xtime_lock;

extern int piranha_simulator;

#ifdef CONFIG_PPC_ISERIES

unsigned long iSeries_recal_titan = 0;

unsigned long iSeries_recal_tb = 0;

static unsigned long first_settimeofday = 1;

#endif

#define XSEC_PER_SEC (1024*1024)

#define USEC_PER_SEC (1000000)

unsigned long tb_ticks_per_jiffy;

unsigned long tb_ticks_per_usec;

unsigned long tb_ticks_per_sec;

unsigned long next_xtime_sync_tb;

unsigned long xtime_sync_interval;

unsigned long tb_to_xs;

unsigned long processor_freq;

spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;

extern unsigned long wall_jiffies;

extern unsigned long lpEvent_count;

extern int smp_tb_synchronized;

extern unsigned long prof_cpu_mask;

extern unsigned int * prof_buffer;

extern unsigned long prof_len;

extern unsigned long prof_shift;

extern char _stext;

extern struct timezone sys_tz;

void ppc_adjtimex(void);

static unsigned adjusting_time = 0;

static void ppc_do_profile (unsigned long nip)

{

        /*

         * Only measure the CPUs specified by /proc/irq/prof_cpu_mask.

         * (default is all CPUs.)

         */

        if (!((1<<smp_processor_id()) & prof_cpu_mask))

                return;

        nip -= (unsigned long) &_stext;

        nip >>= prof_shift;

        /*

         * Don't ignore out-of-bounds EIP values silently,

         * put them into the last histogram slot, so if

         * present, they will show up as a sharp peak.

         */

        if (nip > prof_len-1)

                nip = prof_len-1;

        atomic_inc((atomic_t *)&prof_buffer[nip]);

}

static __inline__ void timer_check_rtc(void)

{

        /*

         * update the rtc when needed, this should be performed on the

         * right fraction of a second. Half or full second ?

         * Full second works on mk48t59 clocks, others need testing.

         * Note that this update is basically only used through

         * the adjtimex system calls. Setting the HW clock in

         * any other way is a /dev/rtc and userland business.

         * This is still wrong by -0.5/+1.5 jiffies because of the

         * timer interrupt resolution and possible delay, but here we

         * hit a quantization limit which can only be solved by higher

         * resolution timers and decoupling time management from timer

         * interrupts. This is also wrong on the clocks

         * which require being written at the half second boundary.

         * We should have an rtc call that only sets the minutes and

         * seconds like on Intel to avoid problems with non UTC clocks.

         */

        if ( (time_status & STA_UNSYNC) == 0 &&

             xtime.tv_sec - last_rtc_update >= 659 &&

             abs(xtime.tv_usec - (1000000-1000000/HZ)) < 500000/HZ &&

             jiffies - wall_jiffies == 1) {

            struct rtc_time tm;

            to_tm(xtime.tv_sec+1, &tm);

            tm.tm_year -= 1900;

            tm.tm_mon -= 1;

            if (ppc_md.set_rtc_time(&tm) == 0)

                last_rtc_update = xtime.tv_sec+1;

            else

                /* Try again one minute later */

                last_rtc_update += 60;

        }

}

/* Synchronize xtime with do_gettimeofday */

static __inline__ void timer_sync_xtime( unsigned long cur_tb )

{

        struct timeval my_tv;

        if ( cur_tb > next_xtime_sync_tb ) {

                next_xtime_sync_tb = cur_tb + xtime_sync_interval;

                do_gettimeofday( &my_tv );

                if ( xtime.tv_sec <= my_tv.tv_sec ) {

                        xtime.tv_sec = my_tv.tv_sec;

                        xtime.tv_usec = my_tv.tv_usec;

                }

        }

}

#ifdef CONFIG_PPC_ISERIES

/*

 * This function recalibrates the timebase based on the 49-bit time-of-day

 * value in the Titan chip.  The Titan is much more accurate than the value

 * returned by the service processor for the timebase frequency.

 */

static void iSeries_tb_recal(void)

{

        struct div_result divres;

        unsigned long titan, tb;

        tb = get_tb();

        titan = HvCallXm_loadTod();

        if ( iSeries_recal_titan ) {

                unsigned long tb_ticks = tb - iSeries_recal_tb;

                unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;

                unsigned long new_tb_ticks_per_sec   = (tb_ticks * USEC_PER_SEC)/titan_usec;

                unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;

                long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;

                char sign = '+';

                /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */

                new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;

                if ( tick_diff < 0 ) {

                        tick_diff = -tick_diff;

                        sign = '-';

                }

                if ( tick_diff ) {

                        if ( tick_diff < tb_ticks_per_jiffy/25 ) {

                                printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",

                                                new_tb_ticks_per_jiffy, sign, tick_diff );

                                tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;

                                tb_ticks_per_sec   = new_tb_ticks_per_sec;

                                div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );

                                systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;

                                tb_to_xs = divres.result_low;

                                systemcfg->tb_to_xs = tb_to_xs;

                        }

                        else {

                                printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"

                                        "                   new tb_ticks_per_jiffy = %lu\n"

                                        "                   old tb_ticks_per_jiffy = %lu\n",

                                        new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );

                        }

                }

        }

        iSeries_recal_titan = titan;

        iSeries_recal_tb = tb;

}

#endif

/*

 * For iSeries shared processors, we have to let the hypervisor

 * set the hardware decrementer.  We set a virtual decrementer

 * in the ItLpPaca and call the hypervisor if the virtual

 * decrementer is less than the current value in the hardware

 * decrementer. (almost always the new decrementer value will

 * be greater than the current hardware decementer so the hypervisor

 * call will not be needed)

 */

unsigned long tb_last_stamp=0;

/*

 * timer_interrupt - gets called when the decrementer overflows,

 * with interrupts disabled.

 */

int timer_interrupt(struct pt_regs * regs)

{

        int next_dec;

        unsigned long cur_tb;

        struct paca_struct *lpaca = get_paca();

        unsigned long cpu = lpaca->xPacaIndex;

        struct ItLpQueue * lpq;

        irq_enter(cpu);

        if ((!user_mode(regs)) && (prof_buffer))

                ppc_do_profile(instruction_pointer(regs));

        pmc_timeslice_tick(); /* Hack this in for now */

        lpaca->xLpPaca.xIntDword.xFields.xDecrInt = 0;

        while (lpaca->next_jiffy_update_tb <= (cur_tb = get_tb())) {

#ifdef CONFIG_SMP

                smp_local_timer_interrupt(regs);

#endif

                if (cpu == 0) {

                        write_lock(&xtime_lock);

                        tb_last_stamp = lpaca->next_jiffy_update_tb;

                        do_timer(regs);

                        timer_sync_xtime( cur_tb );

                        timer_check_rtc();

                        write_unlock(&xtime_lock);

                        if ( adjusting_time && (time_adjust == 0) )

                                ppc_adjtimex();

                }

                lpaca->next_jiffy_update_tb += tb_ticks_per_jiffy;

        }

        next_dec = lpaca->next_jiffy_update_tb - cur_tb;

        if (next_dec > lpaca->default_decr)

                next_dec = lpaca->default_decr;

        set_dec(next_dec);

        lpq = lpaca->lpQueuePtr;

        if (lpq && ItLpQueue_isLpIntPending(lpq))

                lpEvent_count += ItLpQueue_process(lpq, regs);

        irq_exit(cpu);

        if (softirq_pending(cpu))

                do_softirq();

        return 1;

}

/*

 * This version of gettimeofday has microsecond resolution.

 */

void do_gettimeofday(struct timeval *tv)

{

        unsigned long sec, usec, tb_ticks;

        unsigned long xsec, tb_xsec;

        unsigned long temp_tb_to_xs, temp_stamp_xsec;

        unsigned long tb_count_1, tb_count_2;

        unsigned long always_zero;

        struct systemcfg *gtdp;

        gtdp = systemcfg;

        /*

         * The following loop guarantees that we see a consistent view of the

         * tb_to_xs and stamp_xsec variables.  These two variables can change

         * (eg. when xntpd adjusts the clock frequency) and an inconsistent

         * view (one variable changed, the other not) could result in a wildly

         * wrong result for do_gettimeofday.

         *

         * The code which updates these variables (ppc_adjtimex below)

         * increments tb_update_count, then updates the two variables and then

         * increments tb_update_count again.  This code reads tb_update_count,

         * reads the two variables and then reads tb_update_count again.  It

         * loops doing this until the two reads of tb_update_count yield the

         * same value and that value is even.  This ensures a consistent view

         * of the two variables.

         *

         * The strange looking assembler code below causes the hardware to

         * think that reading the two variables is dependent on the first read

         * of tb_update_count and that the second reading of tb_update_count is

         * dependent on reading the two variables.  This assures ordering

         * without the need for a lwsync, which is much more expensive.

         */

        do {

                tb_ticks = get_tb() - gtdp->tb_orig_stamp;

                tb_count_1 = gtdp->tb_update_count;

                __asm__ __volatile__ (

"               andc    %0,%2,%2\n\

                add     %1,%3,%0\n\

"               : "=&r"(always_zero), "=r"(gtdp)

                : "r"(tb_count_1), "r"(gtdp) );

                temp_tb_to_xs = gtdp->tb_to_xs;

                temp_stamp_xsec = gtdp->stamp_xsec;

                __asm__ __volatile__ (

"               add     %0,%2,%3\n\

                andc    %0,%0,%0\n\

                add     %1,%4,%0\n\

"               : "=&r"(always_zero), "=r"(gtdp)

                : "r"(temp_stamp_xsec), "r"(temp_tb_to_xs), "r"(gtdp) );

                tb_count_2 = gtdp->tb_update_count;

        } while ( tb_count_2 - ( tb_count_1 & 0xfffffffffffffffe ) );

        /* These calculations are faster (gets rid of divides)

         * if done in units of 1/2^20 rather than microseconds.

         * The conversion to microseconds at the end is done

         * without a divide (and in fact, without a multiply) */

        tb_xsec = mulhdu( tb_ticks, temp_tb_to_xs );

        xsec = temp_stamp_xsec + tb_xsec;

        sec = xsec / XSEC_PER_SEC;

        xsec -= sec * XSEC_PER_SEC;

        usec = (xsec * USEC_PER_SEC)/XSEC_PER_SEC;

        tv->tv_sec = sec;

        tv->tv_usec = usec;

}

void do_settimeofday(struct timeval *tv)

{

        unsigned long flags;

        unsigned long delta_xsec;

        long int tb_delta, new_usec, new_sec;

        unsigned long new_xsec;

        write_lock_irqsave(&xtime_lock, flags);

        /* Updating the RTC is not the job of this code. If the time is

         * stepped under NTP, the RTC will be update after STA_UNSYNC

         * is cleared. Tool like clock/hwclock either copy the RTC

         * to the system time, in which case there is no point in writing

         * to the RTC again, or write to the RTC but then they don't call

         * settimeofday to perform this operation.

         */

#ifdef CONFIG_PPC_ISERIES

        if ( first_settimeofday ) {

                iSeries_tb_recal();

                first_settimeofday = 0;

        }

#endif

        tb_delta = tb_ticks_since(tb_last_stamp);

        tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy;

        new_sec = tv->tv_sec;

        new_usec = tv->tv_usec - tb_delta / tb_ticks_per_usec;

        while (new_usec <0) {

                new_sec--;

                new_usec += USEC_PER_SEC;

        }

        xtime.tv_usec = new_usec;

        xtime.tv_sec = new_sec;

        /* In case of a large backwards jump in time with NTP, we want the

         * clock to be updated as soon as the PLL is again in lock.

         */

        last_rtc_update = new_sec - 658;

        time_adjust = 0;                /* stop active adjtime() */

        time_status |= STA_UNSYNC;

        time_maxerror = NTP_PHASE_LIMIT;

        time_esterror = NTP_PHASE_LIMIT;

        delta_xsec = mulhdu( (tb_last_stamp-systemcfg->tb_orig_stamp), systemcfg->tb_to_xs );

        new_xsec = (tv->tv_usec * XSEC_PER_SEC) / USEC_PER_SEC;

        new_xsec += tv->tv_sec * XSEC_PER_SEC;

        if ( new_xsec > delta_xsec ) {

                systemcfg->stamp_xsec = new_xsec - delta_xsec;

        }

        else {

                /* This is only for the case where the user is setting the time

                 * way back to a time such that the boot time would have been

                 * before 1970 ... eg. we booted ten days ago, and we are

                 * setting the time to Jan 5, 1970 */

                systemcfg->stamp_xsec = new_xsec;

                systemcfg->tb_orig_stamp = tb_last_stamp;

        }

        systemcfg->tz_minuteswest = sys_tz.tz_minuteswest;

        systemcfg->tz_dsttime = sys_tz.tz_dsttime;

        write_unlock_irqrestore(&xtime_lock, flags);

}

/*

 * This function is a copy of the architecture independent function

 * but which calls do_settimeofday rather than setting the xtime

 * fields itself.  This way, the fields which are used for

 * do_settimeofday get updated too.

 */

long ppc64_sys32_stime(int* tptr)

{

        int value;

        struct timeval myTimeval;

        if (!capable(CAP_SYS_TIME))

                return -EPERM;

        if (get_user(value, tptr))

                return -EFAULT;

        myTimeval.tv_sec = value;

        myTimeval.tv_usec = 0;

        do_settimeofday(&myTimeval);

        return 0;

}

/*

 * This function is a copy of the architecture independent function

 * but which calls do_settimeofday rather than setting the xtime

 * fields itself.  This way, the fields which are used for

 * do_settimeofday get updated too.

 */

long ppc64_sys_stime(long* tptr)

{

        long value;

        struct timeval myTimeval;

        if (!capable(CAP_SYS_TIME))

                return -EPERM;

        if (get_user(value, tptr))

                return -EFAULT;

        myTimeval.tv_sec = value;

        myTimeval.tv_usec = 0;

        do_settimeofday(&myTimeval);

        return 0;

}

void __init time_init(void)

{

        /* This function is only called on the boot processor */

        unsigned long flags;

        struct rtc_time tm;

        ppc_md.calibrate_decr();

        if ( ! piranha_simulator ) {

                ppc_md.get_boot_time(&tm);

        }

        write_lock_irqsave(&xtime_lock, flags);

        xtime.tv_sec = mktime(tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,

                              tm.tm_hour, tm.tm_min, tm.tm_sec);

        tb_last_stamp = get_tb();

        systemcfg->tb_orig_stamp = tb_last_stamp;

        systemcfg->tb_update_count = 0;

        systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;

        systemcfg->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;

        systemcfg->tb_to_xs = tb_to_xs;

        xtime_sync_interval = tb_ticks_per_sec - (tb_ticks_per_sec/8);

        next_xtime_sync_tb = tb_last_stamp + xtime_sync_interval;

        time_freq = 0;

        xtime.tv_usec = 0;

        last_rtc_update = xtime.tv_sec;

        write_unlock_irqrestore(&xtime_lock, flags);

        /* Not exact, but the timer interrupt takes care of this */

        set_dec(tb_ticks_per_jiffy);

        /* This horrible hack gives setup a hook just before console_init */

        setup_before_console_init();

}

/*

 * After adjtimex is called, adjust the conversion of tb ticks

 * to microseconds to keep do_gettimeofday synchronized

 * with ntpd.

 *

 * Use the time_adjust, time_freq and time_offset computed by adjtimex to

 * adjust the frequency.

 */

/* #define DEBUG_PPC_ADJTIMEX 1 */

void ppc_adjtimex(void)

{

        unsigned long den, new_tb_ticks_per_sec, tb_ticks, old_xsec, new_tb_to_xs, new_xsec, new_stamp_xsec;

        unsigned long tb_ticks_per_sec_delta;

        long delta_freq, ltemp;

        struct div_result divres;

        unsigned long flags;

        long singleshot_ppm = 0;

        /* Compute parts per million frequency adjustment to accomplish the time adjustment

           implied by time_offset to be applied over the elapsed time indicated by time_constant.

           Use SHIFT_USEC to get it into the same units as time_freq. */

        if ( time_offset < 0 ) {

                ltemp = -time_offset;

                ltemp <<= SHIFT_USEC - SHIFT_UPDATE;

                ltemp >>= SHIFT_KG + time_constant;

                ltemp = -ltemp;

        }

        else {

                ltemp = time_offset;

                ltemp <<= SHIFT_USEC - SHIFT_UPDATE;

                ltemp >>= SHIFT_KG + time_constant;

        }

        /* If there is a single shot time adjustment in progress */

        if ( time_adjust ) {

#ifdef DEBUG_PPC_ADJTIMEX

                printk("ppc_adjtimex: ");

                if ( adjusting_time == 0 )

                        printk("starting ");

                printk("single shot time_adjust = %ld\n", time_adjust);

#endif  

                adjusting_time = 1;

                /* Compute parts per million frequency adjustment to match time_adjust */

                singleshot_ppm = tickadj * HZ;

                /*

                 * The adjustment should be tickadj*HZ to match the code in

                 * linux/kernel/timer.c, but experiments show that this is too

                 * large. 3/4 of tickadj*HZ seems about right

                 */

                singleshot_ppm -= singleshot_ppm / 4;

                /* Use SHIFT_USEC to get it into the same units as time_freq */

                singleshot_ppm <<= SHIFT_USEC;

                if ( time_adjust < 0 )

                        singleshot_ppm = -singleshot_ppm;

        }

        else {

#ifdef DEBUG_PPC_ADJTIMEX

                if ( adjusting_time )

                        printk("ppc_adjtimex: ending single shot time_adjust\n");

#endif

                adjusting_time = 0;

        }

        /* Add up all of the frequency adjustments */

        delta_freq = time_freq + ltemp + singleshot_ppm;

        /* Compute a new value for tb_ticks_per_sec based on the frequency adjustment */

        den = 1000000 * (1 << (SHIFT_USEC - 8));

        if ( delta_freq < 0 ) {

                tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( (-delta_freq) >> (SHIFT_USEC - 8))) / den;

                new_tb_ticks_per_sec = tb_ticks_per_sec + tb_ticks_per_sec_delta;

        }

        else {

                tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( delta_freq >> (SHIFT_USEC - 8))) / den;

                new_tb_ticks_per_sec = tb_ticks_per_sec - tb_ticks_per_sec_delta;

        }

#ifdef DEBUG_PPC_ADJTIMEX

        printk("ppc_adjtimex: ltemp = %ld, time_freq = %ld, singleshot_ppm = %ld\n", ltemp, time_freq, singleshot_ppm);

        printk("ppc_adjtimex: tb_ticks_per_sec - base = %ld  new = %ld\n", tb_ticks_per_sec, new_tb_ticks_per_sec);

#endif

        /*

         * Compute a new value of tb_to_xs (used to convert tb to microseconds

         * and a new value of stamp_xsec which is the time (in 1/2^20 second

         * units) corresponding to tb_orig_stamp.  This new value of stamp_xsec

         * compensates for the change in frequency (implied by the new

         * tb_to_xs) and so guarantees that the current time remains the same

         *

         */

        tb_ticks = get_tb() - systemcfg->tb_orig_stamp;

        div128_by_32( 1024*1024, 0, new_tb_ticks_per_sec, &divres );

        new_tb_to_xs = divres.result_low;

        new_xsec = mulhdu( tb_ticks, new_tb_to_xs );

        write_lock_irqsave( &xtime_lock, flags );

        old_xsec = mulhdu( tb_ticks, systemcfg->tb_to_xs );

        new_stamp_xsec = systemcfg->stamp_xsec + old_xsec - new_xsec;

        /*

         * tb_update_count is used to allow the problem state gettimeofday code

         * to assure itself that it sees a consistent view of the tb_to_xs and

         * stamp_xsec variables.  It reads the tb_update_count, then reads

         * tb_to_xs and stamp_xsec and then reads tb_update_count again.  If

         * the two values of tb_update_count match and are even then the

         * tb_to_xs and stamp_xsec values are consistent.  If not, then it

         * loops back and reads them again until this criteria is met.

         */

        ++(systemcfg->tb_update_count);

        wmb();

        systemcfg->tb_to_xs = new_tb_to_xs;

        systemcfg->stamp_xsec = new_stamp_xsec;

        wmb();

        ++(systemcfg->tb_update_count);

        write_unlock_irqrestore( &xtime_lock, flags );

}

#define TICK_SIZE tick

#define FEBRUARY        2

#define STARTOFTIME     1970

#define SECDAY          86400L

#define SECYR           (SECDAY * 365)

#define leapyear(year)          ((year) % 4 == 0)

#define days_in_year(a)         (leapyear(a) ? 366 : 365)

#define days_in_month(a)        (month_days[(a) - 1])

static int month_days[12] = {

        31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31

};

/*

 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)

 */

void GregorianDay(struct rtc_time * tm)

{

        int leapsToDate;

        int lastYear;

        int day;

        int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };

        lastYear=tm->tm_year-1;

        /*

         * Number of leap corrections to apply up to end of last year

         */

        leapsToDate = lastYear/4 - lastYear/100 + lastYear/400;

        /*

         * This year is a leap year if it is divisible by 4 except when it is

         * divisible by 100 unless it is divisible by 400

         *

         * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be

         */

        if((tm->tm_year%4==0) &&

           ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) &&

           (tm->tm_mon>2))

        {

                /*

                 * We are past Feb. 29 in a leap year

                 */

                day=1;

        }

        else

        {

                day=0;

        }

        day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +

                   tm->tm_mday;

        tm->tm_wday=day%7;

}

void to_tm(int tim, struct rtc_time * tm)

{

        register int    i;

        register long   hms, day;

        day = tim / SECDAY;

        hms = tim % SECDAY;

        /* Hours, minutes, seconds are easy */

        tm->tm_hour = hms / 3600;