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Initial revision

/*	$OpenBSD: clock.c,v 1.10 2004/12/24 22:50:30 miod Exp $	*/
/*	$NetBSD: clock.c,v 1.1 1996/09/30 16:34:40 ws Exp $	*/

/*
 * Copyright (C) 1995, 1996 Wolfgang Solfrank.
 * Copyright (C) 1995, 1996 TooLs GmbH.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by TooLs GmbH.
 * 4. The name of TooLs GmbH may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>

#include <machine/pio.h>
#include <machine/intr.h>
#include <machine/powerpc.h>

#include "bugtty.h"

void resettodr(void);
void decr_intr(struct clockframe *);
void calc_delayconst(void);

/*
 * Initially we assume a processor with a bus frequency of 12.5 MHz.
 */
static u_long ticks_per_sec = 3125000;
static u_long ns_per_tick = 320;
static long ticks_per_intr;
static volatile u_long lasttb;

/*
 * BCD to decimal and decimal to BCD.
 */
#define FROMBCD(x)      (((x) >> 4) * 10 + ((x) & 0xf))
#define TOBCD(x)        (((x) / 10 * 16) + ((x) % 10))

#define SECDAY          (24 * 60 * 60)
#define SECYR           (SECDAY * 365)
#define LEAPYEAR(y)     (((y) & 3) == 0)
#define YEAR0		1900

tps_t *tps;
clock_read_t *clock_read;
clock_write_t *clock_write;
time_read_t  *time_read;
time_write_t *time_write;

static u_int32_t chiptotime(int, int, int, int, int, int);

/* event tracking variables, when the next event of each time should occur */
u_int64_t nexttimerevent, prevtb, nextstatevent;

/* vars for stats */
int statint;
u_int32_t statvar;
u_int32_t statmin;

struct chiptime {
	int     sec;
	int     min;
	int     hour;
	int     wday;
	int     day;
	int     mon;
	int     year;
};

static void timetochip(struct chiptime *c);

/*
 * For now we let the machine run with boot time, not changing the clock
 * at inittodr at all.
 *
 * We might continue to do this due to setting up the real wall clock with
 * a user level utility in the future.
 */

/* ARGSUSED */
void
inittodr(time_t base)
{
	int sec, min, hour, day, mon, year;

	int badbase = 0, waszero = base == 0;

	if (base < 5 * SECYR) {
		/*
		 * If base is 0, assume filesystem time is just unknown
		 * instead of preposterous. Don't bark.
		 */
		if (base != 0)
			printf("WARNING: preposterous time in file system\n");
		/* not going to use it anyway, if the chip is readable */
		base = 21*SECYR + 186*SECDAY + SECDAY/2;
		badbase = 1;
	}

	if (clock_read != NULL ) {
		(*clock_read)( &sec, &min, &hour, &day, &mon, &year);
		time.tv_sec = chiptotime(sec, min, hour, day, mon, year);
	} else if (time_read != NULL) {
		u_int32_t cursec;
		(*time_read)(&cursec);
		time.tv_sec = cursec;
	} else {
		/* force failure */
		time.tv_sec = 0;
	} 

	if (time.tv_sec == 0) {
		printf("WARNING: unable to get date/time");
		/*
		 * Believe the time in the file system for lack of
		 * anything better, resetting the clock.
		 */
		time.tv_sec = base;
		if (!badbase)
			resettodr();
	} else {
		int deltat;

		time.tv_sec += tz.tz_minuteswest * 60;
		if (tz.tz_dsttime)
			time.tv_sec -= 3600;

		deltat = time.tv_sec - base;

		if (deltat < 0)
			deltat = -deltat;
		if (waszero || deltat < 2 * SECDAY)
			return;
		printf("WARNING: clock %s %d days",
		    time.tv_sec < base ? "lost" : "gained", deltat / SECDAY);

		if (time.tv_sec < base && deltat > 1000 * SECDAY) {
			printf(", using FS time");
			time.tv_sec = base;
		}
	}
	printf(" -- CHECK AND RESET THE DATE!\n");
}

/*
 * This code is defunct after 2068.
 * Will Unix still be here then??
 */
const short dayyr[12] =
    { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};

static u_int32_t
chiptotime(int sec, int min, int hour, int day, int mon, int year)
{
	int days, yr;

	sec = FROMBCD(sec);
	min = FROMBCD(min);
	hour = FROMBCD(hour);
	day = FROMBCD(day);
	mon = FROMBCD(mon);
	year = FROMBCD(year) + YEAR0;

	/* simple sanity checks */
	if (year < 1970 || mon < 1 || mon > 12 || day < 1 || day > 31)
		return (0);
	days = 0;
	for (yr = 1970; yr < year; yr++)
		days += LEAPYEAR(yr) ? 366 : 365;
	days += dayyr[mon - 1] + day - 1;
	if (LEAPYEAR(yr) && mon > 2)
		days++;
	/* now have days since Jan 1, 1970; the rest is easy... */
	return (days * SECDAY + hour * 3600 + min * 60 + sec);
}

void
timetochip(struct chiptime *c)
{
	int t, t2, t3, now = time.tv_sec;

	/* January 1 1970 was a Thursday (4 in unix wdays) */
	/* compute the days since the epoch */
	t2 = now / SECDAY;

	t3 = (t2 + 4) % 7;	/* day of week */
	c->wday = TOBCD(t3 + 1);

	/* compute the year */
	t = 69;
	while (t2 >= 0) {	/* whittle off years */
		t3 = t2;
		t++;
		t2 -= LEAPYEAR(t) ? 366 : 365;
	}
	c->year = t;

	/* t3 = month + day; separate */
	t = LEAPYEAR(t);
	for (t2 = 1; t2 < 12; t2++)
		if (t3 < (dayyr[t2] + ((t && (t2 > 1)) ? 1:0)))
			break;

	/* t2 is month */
	c->mon = t2;
	c->day = t3 - dayyr[t2 - 1] + 1;
	if (t && t2 > 2)
		c->day--;

	/* the rest is easy */
	t = now % SECDAY;
	c->hour = t / 3600;
	t %= 3600;
	c->min = t / 60;
	c->sec = t % 60;

	c->sec = TOBCD(c->sec);
	c->min = TOBCD(c->min);
	c->hour = TOBCD(c->hour);
	c->day = TOBCD(c->day);
	c->mon = TOBCD(c->mon);
	c->year = TOBCD((c->year - YEAR0) % 100);
}


/*
 * Similar to the above
 */
void
resettodr()
{
	struct timeval curtime = time;
	if (clock_write != NULL) {
		struct chiptime c;
		timetochip(&c);
		(*clock_write)(c.sec, c.min, c.hour, c.day, c.mon, c.year);
	} else if (time_write != NULL) {
		curtime.tv_sec -= tz.tz_minuteswest * 60;
		if (tz.tz_dsttime) {
			curtime.tv_sec += 3600;
		}
		(*time_write)(curtime.tv_sec);
	}
}

volatile int statspending;

void
decr_intr(struct clockframe *frame)
{
	u_int64_t tb;
	u_int64_t nextevent;
	int nstats;
	int s;

	/*
	 * Check whether we are initialized.
	 */
	if (!ticks_per_intr)
		return;

	/*
	 * Based on the actual time delay since the last decrementer reload,
	 * we arrange for earlier interrupt next time.
	 */

	tb = ppc_mftb();
	while (nexttimerevent <= tb)
		nexttimerevent += ticks_per_intr;

	prevtb = nexttimerevent - ticks_per_intr;

	for (nstats = 0; nextstatevent <= tb; nstats++) {
		int r;
		do {
			r = random() & (statvar - 1);
		} while (r == 0); /* random == 0 not allowed */
		nextstatevent += statmin + r;
	}

	if (nexttimerevent < nextstatevent)
		nextevent = nexttimerevent;
	else
		nextevent = nextstatevent;

	/*
	 * Need to work about the near constant skew this introduces???
	 * reloading tb here could cause a missed tick.
	 */
	ppc_mtdec(nextevent - tb);

	if (cpl & SPL_CLOCK) {
		statspending += nstats;
	} else {
		nstats += statspending;
		statspending = 0;

		s = splclock();

		/*
		 * Reenable interrupts
		 */
		ppc_intr_enable(1);

		/*
		 * Do standard timer interrupt stuff.
		 * Do softclock stuff only on the last iteration.
		 */
		frame->pri = s | SINT_CLOCK;
		while (lasttb < prevtb - ticks_per_intr) {
			/* sync lasttb with hardclock */
			lasttb += ticks_per_intr;
			hardclock(frame);
		}

		frame->pri = s;
		while (lasttb < prevtb) {
			/* sync lasttb with hardclock */
			lasttb += ticks_per_intr;
			hardclock(frame);
#if NBUGTTY > 0
			{
				extern void bugtty_chkinput(void);
				bugtty_chkinput();
			}
#endif
		}

		while (nstats-- > 0)
			statclock(frame);

		splx(s);
		ppc_intr_disable();

		/*
		 * If a tick has occurred while dealing with these,
		 * don't service it now, delay until the next tick.
		 */
	}
}

void
cpu_initclocks()
{
	int intrstate;
	int r;
	int minint;
	u_int64_t nextevent;

	intrstate = ppc_intr_disable();

	stathz = 100;
	profhz = 1000; /* must be a multiple of stathz */

	/* init secondary clock to stathz */
	statint = ticks_per_sec / stathz;
	statvar = 0x40000000; /* really big power of two */
	/* find largest 2^n which is nearly smaller than statint/2 */
	minint = statint / 2 + 100;
	while (statvar > minint)
		statvar >>= 1;

	statmin = statint - (statvar >> 1);

	lasttb = ppc_mftb();
	nexttimerevent = lasttb + ticks_per_intr;
	do {
		r = random() & (statvar - 1);
	} while (r == 0); /* random == 0 not allowed */
	nextstatevent = lasttb + statmin + r;

	if (nexttimerevent < nextstatevent)
		nextevent = nexttimerevent;
	else
		nextevent = nextstatevent;

	ppc_mtdec(nextevent - lasttb);
	ppc_intr_enable(intrstate);
}

void
calc_delayconst(void)
{
	int s;

	ticks_per_sec = (*tps)();
	s = ppc_intr_disable();
	ns_per_tick = 1000000000 / ticks_per_sec;
	ticks_per_intr = ticks_per_sec / hz;
	ppc_intr_enable(s);
}

/*
 * Fill in *tvp with current time with microsecond resolution.
 */
void
microtime(struct timeval *tvp)
{
	u_int64_t tb;
	u_int32_t ticks;
	int s;

	s = ppc_intr_disable();
	tb = ppc_mftb();
	ticks = ((tb - lasttb) * ns_per_tick) / 1000;
	*tvp = time;
	ppc_intr_enable(s);
	tvp->tv_usec += ticks;
	while (tvp->tv_usec >= 1000000) {
		tvp->tv_usec -= 1000000;
		tvp->tv_sec++;
	}
}

/*
 * Wait for about n microseconds (us) (at least!).
 */
void
delay(unsigned n)
{
	u_int64_t tb;
	u_int32_t tbh, tbl, scratch;

	tb = ppc_mftb();
	tb += (n * 1000 + ns_per_tick - 1) / ns_per_tick;
	tbh = tb >> 32;
	tbl = (u_int32_t)tb;
	asm ("1: mftbu %0; cmplw %0,%1; blt 1b; bgt 2f;"
	     " mftb %0; cmplw %0,%2; blt 1b; 2:"
	     :: "r"(scratch), "r"(tbh), "r"(tbl));
}

void
setstatclockrate(int newhz)
{
	int minint;
	int intrstate;

	intrstate = ppc_intr_disable();

	statint = ticks_per_sec / newhz;
	statvar = 0x40000000; /* really big power of two */
	/* find largest 2^n which is nearly smaller than statint/2 */
	minint = statint / 2 + 100;
	while (statvar > minint)
		statvar >>= 1;

	statmin = statint - (statvar >> 1);
	ppc_intr_enable(intrstate);

	/*
	 * XXX this allows the next stat timer to occur then it switches
	 * to the new frequency. Rather than switching instantly.
	 */
}