[apple/xnu.git] / osfmk / i386 / rtclock.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */

/*
 *      File:           i386/rtclock.c
 *      Purpose:        Routines for handling the machine dependent
 *                      real-time clock. This clock is generated by
 *                      the Intel 8254 Programmable Interval Timer.
 */

#include <cpus.h>
#include <platforms.h>
#include <mp_v1_1.h>
#include <mach_kdb.h>
#include <kern/cpu_number.h>
#include <kern/cpu_data.h>
#include <kern/clock.h>
#include <kern/macro_help.h>
#include <kern/misc_protos.h>
#include <kern/spl.h>
#include <machine/mach_param.h> /* HZ */
#include <mach/vm_prot.h>
#include <vm/pmap.h>
#include <vm/vm_kern.h>         /* for kernel_map */
#include <i386/ipl.h>
#include <i386/pit.h>
#include <i386/pio.h>
#include <i386/misc_protos.h>
#include <i386/rtclock_entries.h>
#include <i386/hardclock_entries.h>

int             sysclk_config(void);

int             sysclk_init(void);

kern_return_t   sysclk_gettime(
        mach_timespec_t                 *cur_time);

kern_return_t   sysclk_getattr(
        clock_flavor_t                  flavor,
        clock_attr_t                    attr,
        mach_msg_type_number_t  *count);

kern_return_t   sysclk_setattr(
        clock_flavor_t                  flavor,
        clock_attr_t                    attr,
        mach_msg_type_number_t  count);

void            sysclk_setalarm(
        mach_timespec_t                 *alarm_time);

extern  void (*IOKitRegisterInterruptHook)(void *,  int irq, int isclock);

/*
 * Inlines to get timestamp counter value.
 */

static inline void rdtsc_hilo(uint32_t *hi, uint32_t *lo) {
        asm volatile("rdtsc": "=a" (*lo), "=d" (*hi));
}

static inline uint64_t rdtsc_64(void) {
        uint64_t result;
        asm volatile("rdtsc": "=A" (result));
        return result;
}

/*
 * Lists of clock routines.
 */
struct clock_ops  sysclk_ops = {
        sysclk_config,                  sysclk_init,
        sysclk_gettime,                 0,
        sysclk_getattr,                 sysclk_setattr,
        sysclk_setalarm,
};

int             calend_config(void);

int             calend_init(void);

kern_return_t   calend_gettime(
        mach_timespec_t                 *cur_time);

kern_return_t   calend_settime(
        mach_timespec_t                 *cur_time);

kern_return_t   calend_getattr(
        clock_flavor_t                  flavor,
        clock_attr_t                    attr,
        mach_msg_type_number_t  *count);

struct clock_ops calend_ops = {
        calend_config,                  calend_init,
        calend_gettime,                 calend_settime,
        calend_getattr,                 0,
        0,
};

/* local data declarations */
mach_timespec_t         *RtcTime = (mach_timespec_t *)0;
mach_timespec_t         *RtcAlrm;
clock_res_t                     RtcDelt;

/* global data declarations */
struct  {
        uint64_t                        abstime;

        mach_timespec_t         time;
        mach_timespec_t         alarm_time;     /* time of next alarm */

        mach_timespec_t         calend_offset;
        boolean_t                       calend_is_set;

        uint64_t                        timer_deadline;
        boolean_t                       timer_is_set;
        clock_timer_func_t      timer_expire;

        clock_res_t                     new_ires;       /* pending new resolution (nano ) */
        clock_res_t                     intr_nsec;      /* interrupt resolution (nano) */

        decl_simple_lock_data(,lock)    /* real-time clock device lock */
} rtclock;

unsigned int            clknum;                        /* clks per second */
unsigned int            new_clknum;                    /* pending clknum */
unsigned int            time_per_clk;                  /* time per clk in ZHZ */
unsigned int            clks_per_int;                  /* clks per interrupt */
unsigned int            clks_per_int_99;
int                                     rtc_intr_count;                /* interrupt counter */
int                                     rtc_intr_hertz;                /* interrupts per HZ */
int                                     rtc_intr_freq;                 /* interrupt frequency */
int                                     rtc_print_lost_tick;           /* print lost tick */

uint32_t                rtc_cyc_per_sec;                /* processor cycles per seconds */
uint32_t                rtc_last_int_tsc_lo;            /* tsc values saved per interupt */
uint32_t                rtc_last_int_tsc_hi;

/*
 *      Macros to lock/unlock real-time clock device.
 */
#define LOCK_RTC(s)                                     \
MACRO_BEGIN                                                     \
        (s) = splclock();                               \
        simple_lock(&rtclock.lock);             \
MACRO_END

#define UNLOCK_RTC(s)                           \
MACRO_BEGIN                                                     \
        simple_unlock(&rtclock.lock);   \
        splx(s);                                                \
MACRO_END

/*
 * i8254 control.  ** MONUMENT **
 *
 * The i8254 is a traditional PC device with some arbitrary characteristics.
 * Basically, it is a register that counts at a fixed rate and can be
 * programmed to generate an interrupt every N counts.  The count rate is
 * clknum counts per second (see pit.h), historically 1193167 we believe.
 * Various constants are computed based on this value, and we calculate
 * them at init time for execution efficiency.  To obtain sufficient
 * accuracy, some of the calculation are most easily done in floating
 * point and then converted to int.
 *
 * We want an interrupt every 10 milliseconds, approximately.  The count
 * which will do that is clks_per_int.  However, that many counts is not
 * *exactly* 10 milliseconds; it is a bit more or less depending on
 * roundoff.  The actual time per tick is calculated and saved in
 * rtclock.intr_nsec, and it is that value which is added to the time
 * register on each tick.
 *
 * The i8254 counter can be read between interrupts in order to determine
 * the time more accurately.  The counter counts down from the preset value
 * toward 0, and we have to handle the case where the counter has been
 * reset just before being read and before the interrupt has been serviced.
 * Given a count since the last interrupt, the time since then is given
 * by (count * time_per_clk).  In order to minimize integer truncation,
 * we perform this calculation in an arbitrary unit of time which maintains
 * the maximum precision, i.e. such that one tick is 1.0e9 of these units,
 * or close to the precision of a 32-bit int.  We then divide by this unit
 * (which doesn't lose precision) to get nanoseconds.  For notation
 * purposes, this unit is defined as ZHZ = zanoseconds per nanosecond.
 *
 * This sequence to do all this is in sysclk_gettime.  For efficiency, this
 * sequence also needs the value that the counter will have if it has just
 * overflowed, so we precompute that also.  ALSO, certain platforms
 * (specifically the DEC XL5100) have been observed to have problem
 * with latching the counter, and they occasionally (say, one out of
 * 100,000 times) return a bogus value.  Hence, the present code reads
 * the counter twice and checks for a consistent pair of values.
 *
 * Some attributes of the rt clock can be changed, including the
 * interrupt resolution.  We default to the minimum resolution (10 ms),
 * but allow a finer resolution to be requested.  The assumed frequency
 * of the clock can also be set since it appears that the actual
 * frequency of real-world hardware can vary from the nominal by
 * 200 ppm or more.  When the frequency is set, the values above are
 * recomputed and we continue without resetting or changing anything else.
 */
#define RTC_MINRES      (NSEC_PER_SEC / HZ)     /* nsec per tick */
#define RTC_MAXRES      (RTC_MINRES / 20)       /* nsec per tick */
#define ZANO            (1000000000)
#define ZHZ             (ZANO / (NSEC_PER_SEC / HZ))
#define READ_8254(val)  { \
        outb(PITCTL_PORT, PIT_C0);             \
        (val) = inb(PITCTR0_PORT);               \
        (val) |= inb(PITCTR0_PORT) << 8 ; }

/*
 * Calibration delay counts.
 */
unsigned int    delaycount = 100;
unsigned int    microdata = 50;

/*
 * Forward decl.
 */

extern int   measure_delay(int us);
void         rtc_setvals( unsigned int, clock_res_t );

static void  rtc_set_cyc_per_sec();

/*
 * Initialize non-zero clock structure values.
 */
void
rtc_setvals(
        unsigned int new_clknum,
        clock_res_t  new_ires
        )
{
    unsigned int timeperclk;
    unsigned int scale0;
    unsigned int scale1;
    unsigned int res;

    clknum = new_clknum;
    rtc_intr_freq = (NSEC_PER_SEC / new_ires);
    rtc_intr_hertz = rtc_intr_freq / HZ;
    clks_per_int = (clknum + (rtc_intr_freq / 2)) / rtc_intr_freq;
    clks_per_int_99 = clks_per_int - clks_per_int/100;

    /*
     * The following calculations are done with scaling integer operations
     * in order that the integer results are accurate to the lsb.
     */
    timeperclk = div_scale(ZANO, clknum, &scale0);      /* 838.105647 nsec */

    time_per_clk = mul_scale(ZHZ, timeperclk, &scale1); /* 83810 */
    if (scale0 > scale1)
        time_per_clk >>= (scale0 - scale1);
    else if (scale0 < scale1)
        panic("rtc_clock: time_per_clk overflow\n");

    /*
     * Notice that rtclock.intr_nsec is signed ==> use unsigned int res
     */
    res = mul_scale(clks_per_int, timeperclk, &scale1); /* 10000276 */
    if (scale0 > scale1)
        rtclock.intr_nsec = res >> (scale0 - scale1);
    else
        panic("rtc_clock: rtclock.intr_nsec overflow\n");

    rtc_intr_count = 1;
    RtcDelt = rtclock.intr_nsec/2;
}

/*
 * Configure the real-time clock device. Return success (1)
 * or failure (0).
 */

int
sysclk_config(void)
{
        int     RtcFlag;
        int     pic;

#if     NCPUS > 1
        mp_disable_preemption();
        if (cpu_number() != master_cpu) {
                mp_enable_preemption();
                return(1);
        }
        mp_enable_preemption();
#endif
        /*
         * Setup device.
         */
#if     MP_V1_1
    {
        extern boolean_t mp_v1_1_initialized;
        if (mp_v1_1_initialized)
            pic = 2;
        else
            pic = 0;
    }
#else
        pic = 0;        /* FIXME .. interrupt registration moved to AppleIntelClock */
#endif


        /*
         * We should attempt to test the real-time clock
         * device here. If it were to fail, we should panic
         * the system.
         */
        RtcFlag = /* test device */1;
        printf("realtime clock configured\n");

        simple_lock_init(&rtclock.lock, ETAP_NO_TRACE);
        return (RtcFlag);
}

/*
 * Initialize the real-time clock device. Return success (1)
 * or failure (0). Since the real-time clock is required to
 * provide canonical mapped time, we allocate a page to keep
 * the clock time value. In addition, various variables used
 * to support the clock are initialized.  Note: the clock is
 * not started until rtclock_reset is called.
 */
int
sysclk_init(void)
{
        vm_offset_t     *vp;
#if     NCPUS > 1
        mp_disable_preemption();
        if (cpu_number() != master_cpu) {
                mp_enable_preemption();
                return(1);
        }
        mp_enable_preemption();
#endif

        RtcTime = &rtclock.time;
        rtc_setvals( CLKNUM, RTC_MINRES );  /* compute constants */
        rtc_set_cyc_per_sec();  /* compute number of tsc beats per second */
        return (1);
}

static volatile unsigned int     last_ival = 0;

/*
 * Get the clock device time. This routine is responsible
 * for converting the device's machine dependent time value
 * into a canonical mach_timespec_t value.
 */
kern_return_t
sysclk_gettime(
        mach_timespec_t *cur_time)      /* OUT */
{
        mach_timespec_t itime = {0, 0};
        unsigned int    val, val2;
        int             s;

        if (!RtcTime) {
                /* Uninitialized */
                cur_time->tv_nsec = 0;
                cur_time->tv_sec = 0;
                return (KERN_SUCCESS);
        }

        /*
         * Inhibit interrupts. Determine the incremental
         * time since the last interrupt. (This could be
         * done in assembler for a bit more speed).
         */
        LOCK_RTC(s);
        do {
            READ_8254(val);                 /* read clock */
            READ_8254(val2);                /* read clock */
        } while ( val2 > val || val2 < val - 10 );
        if ( val > clks_per_int_99 ) {
            outb( 0x0a, 0x20 );             /* see if interrupt pending */
            if ( inb( 0x20 ) & 1 )
                itime.tv_nsec = rtclock.intr_nsec; /* yes, add a tick */
        }
        itime.tv_nsec += ((clks_per_int - val) * time_per_clk) / ZHZ;
        if ( itime.tv_nsec < last_ival ) {
            if (rtc_print_lost_tick)
                printf( "rtclock: missed clock interrupt.\n" );
        }
        last_ival = itime.tv_nsec;
        cur_time->tv_sec = rtclock.time.tv_sec;
        cur_time->tv_nsec = rtclock.time.tv_nsec;
        UNLOCK_RTC(s);
        ADD_MACH_TIMESPEC(cur_time, ((mach_timespec_t *)&itime));
        return (KERN_SUCCESS);
}

kern_return_t
sysclk_gettime_internal(
        mach_timespec_t *cur_time)      /* OUT */
{
        mach_timespec_t itime = {0, 0};
        unsigned int    val, val2;

        if (!RtcTime) {
                /* Uninitialized */
                cur_time->tv_nsec = 0;
                cur_time->tv_sec = 0;
                return (KERN_SUCCESS);
        }

        /*
         * Inhibit interrupts. Determine the incremental
         * time since the last interrupt. (This could be
         * done in assembler for a bit more speed).
         */
        do {
            READ_8254(val);                 /* read clock */
            READ_8254(val2);                /* read clock */
        } while ( val2 > val || val2 < val - 10 );
        if ( val > clks_per_int_99 ) {
            outb( 0x0a, 0x20 );             /* see if interrupt pending */
            if ( inb( 0x20 ) & 1 )
                itime.tv_nsec = rtclock.intr_nsec; /* yes, add a tick */
        }
        itime.tv_nsec += ((clks_per_int - val) * time_per_clk) / ZHZ;
        if ( itime.tv_nsec < last_ival ) {
            if (rtc_print_lost_tick)
                printf( "rtclock: missed clock interrupt.\n" );
        }
        last_ival = itime.tv_nsec;
        cur_time->tv_sec = rtclock.time.tv_sec;
        cur_time->tv_nsec = rtclock.time.tv_nsec;
        ADD_MACH_TIMESPEC(cur_time, ((mach_timespec_t *)&itime));
        return (KERN_SUCCESS);
}

/*
 * Get the clock device time when ALL interrupts are already disabled.
 * Same as above except for turning interrupts off and on.
 * This routine is responsible for converting the device's machine dependent
 * time value into a canonical mach_timespec_t value.
 */
void
sysclk_gettime_interrupts_disabled(
        mach_timespec_t *cur_time)      /* OUT */
{
        mach_timespec_t itime = {0, 0};
        unsigned int    val;

        if (!RtcTime) {
                /* Uninitialized */
                cur_time->tv_nsec = 0;
                cur_time->tv_sec = 0;
                return;
        }

        simple_lock(&rtclock.lock);

        /*
         * Copy the current time knowing that we cant be interrupted
         * between the two longwords and so dont need to use MTS_TO_TS
         */
        READ_8254(val);                     /* read clock */
        if ( val > clks_per_int_99 ) {
            outb( 0x0a, 0x20 );             /* see if interrupt pending */
            if ( inb( 0x20 ) & 1 )
                itime.tv_nsec = rtclock.intr_nsec; /* yes, add a tick */
        }
        itime.tv_nsec += ((clks_per_int - val) * time_per_clk) / ZHZ;
        if ( itime.tv_nsec < last_ival ) {
            if (rtc_print_lost_tick)
                printf( "rtclock: missed clock interrupt.\n" );
        }
        last_ival = itime.tv_nsec;
        cur_time->tv_sec = rtclock.time.tv_sec;
        cur_time->tv_nsec = rtclock.time.tv_nsec;
        ADD_MACH_TIMESPEC(cur_time, ((mach_timespec_t *)&itime));

        simple_unlock(&rtclock.lock);
}

// utility routine 
// Code to calculate how many processor cycles are in a second...

static void
rtc_set_cyc_per_sec() 
{

        int     x, y;
        uint64_t cycles;
        uint32_t   c[15];          // array for holding sampled cycle counts
        mach_timespec_t tst[15];  // array for holding time values. NOTE for some reason tv_sec not work

        for (x=0; x<15; x++) {  // quick sample 15 times
                tst[x].tv_sec = 0;
                tst[x].tv_nsec = 0;
                sysclk_gettime_internal(&tst[x]);
                rdtsc_hilo(&y, &c[x]);
        }
        y = 0;
        cycles = 0;
        for (x=0; x<14; x++) {
          // simple formula really. calculate the numerator as the number of elapsed processor
          // cycles * 1000 to adjust for the resolution we want. The denominator is the
          // elapsed "real" time in nano-seconds. The result will be the processor speed in  
          // Mhz. any overflows will be discarded before they are added
          if ((c[x+1] > c[x]) && (tst[x+1].tv_nsec > tst[x].tv_nsec)) {
                cycles += ((uint64_t)(c[x+1]-c[x]) * NSEC_PER_SEC ) / (uint64_t)(tst[x+1].tv_nsec - tst[x].tv_nsec);       // elapsed nsecs
                y +=1;
          }
        }
        if (y>0) { // we got more than 1 valid sample. This also takes care of the case of if the clock isn't running
          cycles = cycles / y;    // calc our average
        }
        rtc_cyc_per_sec = cycles;
        rdtsc_hilo(&rtc_last_int_tsc_hi, &rtc_last_int_tsc_lo);
}

static
natural_t
get_uptime_cycles(void)
{
        // get the time since the last interupt based on the processors TSC ignoring the
        // RTC for speed
 
        uint32_t   a,d,intermediate_lo,intermediate_hi,result;
        uint64_t   newTime;
        
        rdtsc_hilo(&d, &a);
        if (d != rtc_last_int_tsc_hi) {
          newTime = d-rtc_last_int_tsc_hi;
          newTime = (newTime<<32) + (a-rtc_last_int_tsc_lo);
          result = newTime;
        } else {
          result = a-rtc_last_int_tsc_lo;
        }
        __asm__ volatile ( " mul %3 ": "=eax" (intermediate_lo), "=edx" (intermediate_hi): "a"(result), "d"(NSEC_PER_SEC) );
        __asm__ volatile ( " div %3": "=eax" (result): "eax"(intermediate_lo), "edx" (intermediate_hi), "ecx" (rtc_cyc_per_sec) );
        return result;
}


/*
 * Get clock device attributes.
 */
kern_return_t
sysclk_getattr(
        clock_flavor_t          flavor,
        clock_attr_t            attr,           /* OUT */
        mach_msg_type_number_t  *count)         /* IN/OUT */
{
        spl_t   s;

        if (*count != 1)
                return (KERN_FAILURE);
        switch (flavor) {

        case CLOCK_GET_TIME_RES:        /* >0 res */
#if     (NCPUS == 1 || (MP_V1_1 && 0))
                LOCK_RTC(s);
                *(clock_res_t *) attr = 1000;
                UNLOCK_RTC(s);
                break;
#endif  /* (NCPUS == 1 || (MP_V1_1 && 0)) && AT386 */
        case CLOCK_ALARM_CURRES:        /* =0 no alarm */
                LOCK_RTC(s);
                *(clock_res_t *) attr = rtclock.intr_nsec;
                UNLOCK_RTC(s);
                break;

        case CLOCK_ALARM_MAXRES:
                *(clock_res_t *) attr = RTC_MAXRES;
                break;

        case CLOCK_ALARM_MINRES:
                *(clock_res_t *) attr = RTC_MINRES;
                break;

        default:
                return (KERN_INVALID_VALUE);
        }
        return (KERN_SUCCESS);
}

/*
 * Set clock device attributes.
 */
kern_return_t
sysclk_setattr(
        clock_flavor_t          flavor,
        clock_attr_t            attr,           /* IN */
        mach_msg_type_number_t  count)          /* IN */
{
        spl_t           s;
        int             freq;
        int             adj;
        clock_res_t     new_ires;

        if (count != 1)
                return (KERN_FAILURE);
        switch (flavor) {

        case CLOCK_GET_TIME_RES:
        case CLOCK_ALARM_MAXRES:
        case CLOCK_ALARM_MINRES:
                return (KERN_FAILURE);

        case CLOCK_ALARM_CURRES:
                new_ires = *(clock_res_t *) attr;

                /*
                 * The new resolution must be within the predetermined
                 * range.  If the desired resolution cannot be achieved
                 * to within 0.1%, an error is returned.
                 */
                if (new_ires < RTC_MAXRES || new_ires > RTC_MINRES)
                        return (KERN_INVALID_VALUE);
                freq = (NSEC_PER_SEC / new_ires);
                adj = (((clknum % freq) * new_ires) / clknum);
                if (adj > (new_ires / 1000))
                        return (KERN_INVALID_VALUE);
                /*
                 * Record the new alarm resolution which will take effect
                 * on the next HZ aligned clock tick.
                 */
                LOCK_RTC(s);
                if ( freq != rtc_intr_freq ) {
                    rtclock.new_ires = new_ires;
                    new_clknum = clknum;
                }
                UNLOCK_RTC(s);
                return (KERN_SUCCESS);

        default:
                return (KERN_INVALID_VALUE);
        }
}

/*
 * Set next alarm time for the clock device. This call
 * always resets the time to deliver an alarm for the
 * clock.
 */
void
sysclk_setalarm(
        mach_timespec_t *alarm_time)
{
        spl_t           s;

        LOCK_RTC(s);
        rtclock.alarm_time = *alarm_time;
        RtcAlrm = &rtclock.alarm_time;
        UNLOCK_RTC(s);
}

/*
 * Configure the calendar clock.
 */
int
calend_config(void)
{
        return bbc_config();
}

/*
 * Initialize calendar clock.
 */
int
calend_init(void)
{
        return (1);
}

/*
 * Get the current clock time.
 */
kern_return_t
calend_gettime(
        mach_timespec_t *cur_time)      /* OUT */
{
        spl_t           s;

        LOCK_RTC(s);
        if (!rtclock.calend_is_set) {
                UNLOCK_RTC(s);
                return (KERN_FAILURE);
        }

        (void) sysclk_gettime_internal(cur_time);
        ADD_MACH_TIMESPEC(cur_time, &rtclock.calend_offset);
        UNLOCK_RTC(s);

        return (KERN_SUCCESS);
}

/*
 * Set the current clock time.
 */
kern_return_t
calend_settime(
        mach_timespec_t *new_time)
{
        mach_timespec_t curr_time;
        spl_t           s;

        LOCK_RTC(s);
        (void) sysclk_gettime_internal(&curr_time);
        rtclock.calend_offset = *new_time;
        SUB_MACH_TIMESPEC(&rtclock.calend_offset, &curr_time);
        rtclock.calend_is_set = TRUE;
        UNLOCK_RTC(s);

        (void) bbc_settime(new_time);

        return (KERN_SUCCESS);
}

/*
 * Get clock device attributes.
 */
kern_return_t
calend_getattr(
        clock_flavor_t          flavor,
        clock_attr_t            attr,           /* OUT */
        mach_msg_type_number_t  *count)         /* IN/OUT */
{
        spl_t   s;

        if (*count != 1)
                return (KERN_FAILURE);
        switch (flavor) {

        case CLOCK_GET_TIME_RES:        /* >0 res */
#if     (NCPUS == 1 || (MP_V1_1 && 0))
                LOCK_RTC(s);
                *(clock_res_t *) attr = 1000;
                UNLOCK_RTC(s);
                break;
#else   /* (NCPUS == 1 || (MP_V1_1 && 0)) && AT386 */
                LOCK_RTC(s);
                *(clock_res_t *) attr = rtclock.intr_nsec;
                UNLOCK_RTC(s);
                break;
#endif  /* (NCPUS == 1 || (MP_V1_1 && 0)) && AT386 */

        case CLOCK_ALARM_CURRES:        /* =0 no alarm */
        case CLOCK_ALARM_MINRES:
        case CLOCK_ALARM_MAXRES:
                *(clock_res_t *) attr = 0;
                break;

        default:
                return (KERN_INVALID_VALUE);
        }
        return (KERN_SUCCESS);
}

void
clock_adjust_calendar(
        clock_res_t     nsec)
{
        spl_t           s;

        LOCK_RTC(s);
        if (rtclock.calend_is_set)
                ADD_MACH_TIMESPEC_NSEC(&rtclock.calend_offset, nsec);
        UNLOCK_RTC(s);
}

void
clock_initialize_calendar(void)
{
        mach_timespec_t bbc_time, curr_time;
        spl_t           s;

        if (bbc_gettime(&bbc_time) != KERN_SUCCESS)
                return;

        LOCK_RTC(s);
        if (!rtclock.calend_is_set) {
                (void) sysclk_gettime_internal(&curr_time);
                rtclock.calend_offset = bbc_time;
                SUB_MACH_TIMESPEC(&rtclock.calend_offset, &curr_time);
                rtclock.calend_is_set = TRUE;
        }
        UNLOCK_RTC(s);
}

mach_timespec_t
clock_get_calendar_offset(void)
{
        mach_timespec_t result = MACH_TIMESPEC_ZERO;
        spl_t           s;

        LOCK_RTC(s);
        if (rtclock.calend_is_set)
                result = rtclock.calend_offset;
        UNLOCK_RTC(s);

        return (result);
}

void
clock_timebase_info(
        mach_timebase_info_t    info)
{
        spl_t   s;

        LOCK_RTC(s);
        info->numer = info->denom = 1;
        UNLOCK_RTC(s);
}       

void
clock_set_timer_deadline(
        uint64_t                        deadline)
{
        spl_t                   s;

        LOCK_RTC(s);
        rtclock.timer_deadline = deadline;
        rtclock.timer_is_set = TRUE;
        UNLOCK_RTC(s);
}

void
clock_set_timer_func(
        clock_timer_func_t              func)
{
        spl_t           s;

        LOCK_RTC(s);
        if (rtclock.timer_expire == NULL)
                rtclock.timer_expire = func;
        UNLOCK_RTC(s);
}

\f

/*
 * Load the count register and start the clock.
 */
#define RTCLOCK_RESET() {                                       \
        outb(PITCTL_PORT, PIT_C0|PIT_NDIVMODE|PIT_READMODE);    \
        outb(PITCTR0_PORT, (clks_per_int & 0xff));              \
        outb(PITCTR0_PORT, (clks_per_int >> 8));                \
}

/*
 * Reset the clock device. This causes the realtime clock
 * device to reload its mode and count value (frequency).
 * Note: the CPU should be calibrated
 * before starting the clock for the first time.
 */

void
rtclock_reset(void)
{
        int             s;

#if     NCPUS > 1 && !(MP_V1_1 && 0)
        mp_disable_preemption();
        if (cpu_number() != master_cpu) {
                mp_enable_preemption();
                return;
        }
        mp_enable_preemption();
#endif  /* NCPUS > 1 && AT386 && !MP_V1_1 */
        LOCK_RTC(s);
        RTCLOCK_RESET();
        UNLOCK_RTC(s);
}

/*
 * Real-time clock device interrupt. Called only on the
 * master processor. Updates the clock time and upcalls
 * into the higher level clock code to deliver alarms.
 */
int
rtclock_intr(void)
{
        uint64_t                abstime;
        mach_timespec_t clock_time;
        int                             i;
        spl_t                   s;

        /*
         * Update clock time. Do the update so that the macro
         * MTS_TO_TS() for reading the mapped time works (e.g.
         * update in order: mtv_csec, mtv_time.tv_nsec, mtv_time.tv_sec).
         */      
        LOCK_RTC(s);
        rdtsc_hilo(&rtc_last_int_tsc_hi, &rtc_last_int_tsc_lo);
        i = rtclock.time.tv_nsec + rtclock.intr_nsec;
        if (i < NSEC_PER_SEC)
            rtclock.time.tv_nsec = i;
        else {
            rtclock.time.tv_nsec = i - NSEC_PER_SEC;
            rtclock.time.tv_sec++;
        }
        /* note time now up to date */
        last_ival = 0;

        rtclock.abstime += rtclock.intr_nsec;
        abstime = rtclock.abstime;
        if (    rtclock.timer_is_set                            &&
                        rtclock.timer_deadline <= abstime               ) {
                rtclock.timer_is_set = FALSE;
                UNLOCK_RTC(s);

                (*rtclock.timer_expire)(abstime);

                LOCK_RTC(s);
        }

        /*
         * Perform alarm clock processing if needed. The time
         * passed up is incremented by a half-interrupt tick
         * to trigger alarms closest to their desired times.
         * The clock_alarm_intr() routine calls sysclk_setalrm()
         * before returning if later alarms are pending.
         */

        if (RtcAlrm && (RtcAlrm->tv_sec < RtcTime->tv_sec ||
                        (RtcAlrm->tv_sec == RtcTime->tv_sec &&
                         RtcDelt >= RtcAlrm->tv_nsec - RtcTime->tv_nsec))) {
                clock_time.tv_sec = 0;
                clock_time.tv_nsec = RtcDelt;
                ADD_MACH_TIMESPEC (&clock_time, RtcTime);
                RtcAlrm = 0;
                UNLOCK_RTC(s);
                /*
                 * Call clock_alarm_intr() without RTC-lock.
                 * The lock ordering is always CLOCK-lock
                 * before RTC-lock.
                 */
                clock_alarm_intr(SYSTEM_CLOCK, &clock_time);
                LOCK_RTC(s);
        }

        /*
         * On a HZ-tick boundary: return 0 and adjust the clock
         * alarm resolution (if requested).  Otherwise return a
         * non-zero value.
         */
        if ((i = --rtc_intr_count) == 0) {
            if (rtclock.new_ires) {
                        rtc_setvals(new_clknum, rtclock.new_ires);
                        RTCLOCK_RESET();            /* lock clock register */
                        rtclock.new_ires = 0;
            }
            rtc_intr_count = rtc_intr_hertz;
        }
        UNLOCK_RTC(s);
        return (i);
}

void
clock_get_uptime(
        uint64_t                *result)
{
        uint32_t                ticks;
        spl_t                   s;

        LOCK_RTC(s);
        ticks = get_uptime_cycles();
        *result = rtclock.abstime;
        UNLOCK_RTC(s);

        *result += ticks;
}

void
clock_interval_to_deadline(
        uint32_t                interval,
        uint32_t                scale_factor,
        uint64_t                *result)
{
        uint64_t                abstime;

        clock_get_uptime(result);

        clock_interval_to_absolutetime_interval(interval, scale_factor, &abstime);

        *result += abstime;
}

void
clock_interval_to_absolutetime_interval(
        uint32_t                interval,
        uint32_t                scale_factor,
        uint64_t                *result)
{
        *result = (uint64_t)interval * scale_factor;
}

void
clock_absolutetime_interval_to_deadline(
        uint64_t                abstime,
        uint64_t                *result)
{
        clock_get_uptime(result);

        *result += abstime;
}

void
absolutetime_to_nanoseconds(
        uint64_t                abstime,
        uint64_t                *result)
{
        *result = abstime;
}

void
nanoseconds_to_absolutetime(
        uint64_t                nanoseconds,
        uint64_t                *result)
{
        *result = nanoseconds;
}

/*
 * measure_delay(microseconds)
 *
 * Measure elapsed time for delay calls
 * Returns microseconds.
 * 
 * Microseconds must not be too large since the counter (short) 
 * will roll over.  Max is about 13 ms.  Values smaller than 1 ms are ok.
 * This uses the assumed frequency of the rt clock which is emperically
 * accurate to only about 200 ppm.
 */

int
measure_delay(
        int us)
{
        unsigned int    lsb, val;

        outb(PITCTL_PORT, PIT_C0|PIT_NDIVMODE|PIT_READMODE);
        outb(PITCTR0_PORT, 0xff);       /* set counter to max value */
        outb(PITCTR0_PORT, 0xff);
        delay(us);
        outb(PITCTL_PORT, PIT_C0);
        lsb = inb(PITCTR0_PORT);
        val = (inb(PITCTR0_PORT) << 8) | lsb;
        val = 0xffff - val;
        val *= 1000000;
        val /= CLKNUM;
        return(val);
}

/*
 * calibrate_delay(void)
 *
 * Adjust delaycount.  Called from startup before clock is started
 * for normal interrupt generation.
 */

void
calibrate_delay(void)
{
        unsigned        val;
        int             prev = 0;
        register int    i;

        printf("adjusting delay count: %d", delaycount);
        for (i=0; i<10; i++) {
                prev = delaycount;
                /* 
                 * microdata must not be too large since measure_timer
                 * will not return accurate values if the counter (short) 
                 * rolls over
                 */
                val = measure_delay(microdata);
                if (val == 0) {
                  delaycount *= 2;
                } else {
                delaycount *= microdata;
                delaycount += val-1;    /* round up to upper us */
                delaycount /= val;
                }
                if (delaycount <= 0)
                        delaycount = 1;
                if (delaycount != prev)
                        printf(" %d", delaycount);
        }
        printf("\n");
}

#if     MACH_KDB
void
test_delay(void);

void
test_delay(void)
{
        register i;

        for (i = 0; i < 10; i++)
                printf("%d, %d\n", i, measure_delay(i));
        for (i = 10; i <= 100; i+=10)
                printf("%d, %d\n", i, measure_delay(i));
}
#endif  /* MACH_KDB */