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File: [cvs.NetBSD.org] / src / sys / arch / alpha / alpha / clock.c (download)

Revision 1.14, Sat Nov 23 06:31:57 1996 UTC (27 years, 4 months ago) by cgd
Branch: MAIN
CVS Tags: thorpej-setroot, mrg-vm-swap, is-newarp-before-merge, is-newarp-base, is-newarp
Branch point for: alpha-nwscons
Changes since 1.13: +19 -6 lines

move interrupt establishment to just before clock interrupts are
enabled (from the attach routine), and add comments as to why.
Some PALcode apparently 'saves' a clock interrupt for the kernel,
and if the clock interrupt handler is enabled at attach time, it
will be run when that interrupt hits, i.e. right after the spl0()
at the end of autoconfiguration.  That would cause hardclock to be
run, but proc0's p_stats isn't set up by then, which would cause
hardclock to crash.

/*	$NetBSD: clock.c,v 1.14 1996/11/23 06:31:57 cgd Exp $	*/

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department and Ralph Campbell.
 *
 * 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 the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 THE REGENTS OR CONTRIBUTORS 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.
 *
 * from: Utah Hdr: clock.c 1.18 91/01/21
 *
 *	@(#)clock.c	8.1 (Berkeley) 6/10/93
 */

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

#include <machine/rpb.h>
#include <machine/autoconf.h>

#include <alpha/alpha/clockvar.h>

#define	SECMIN	((unsigned)60)			/* seconds per minute */
#define	SECHOUR	((unsigned)(60*SECMIN))		/* seconds per hour */
#define	SECDAY	((unsigned)(24*SECHOUR))	/* seconds per day */
#define	SECYR	((unsigned)(365*SECDAY))	/* seconds per common year */

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

struct device *clockdev;
const struct clockfns *clockfns;
int clockinitted;

void
clockattach(dev, fns)
	struct device *dev;
	const struct clockfns *fns;
{

	/*
	 * Just bookkeeping.
	 */
	printf("\n");

	if (clockfns != NULL)
		panic("clockattach: multiple clocks");
	clockdev = dev;
	clockfns = fns;
#ifdef EVCNT_COUNTERS
	evcnt_attach(dev, "intr", &clock_intr_evcnt);
#endif
}

/*
 * Machine-dependent clock routines.
 *
 * Startrtclock restarts the real-time clock, which provides
 * hardclock interrupts to kern_clock.c.
 *
 * Inittodr initializes the time of day hardware which provides
 * date functions.  Its primary function is to use some file
 * system information in case the hardare clock lost state.
 *
 * Resettodr restores the time of day hardware after a time change.
 */

/*
 * Start the real-time and statistics clocks. Leave stathz 0 since there
 * are no other timers available.
 */
void
cpu_initclocks()
{
	extern int tickadj;

	if (clockfns == NULL)
		panic("cpu_initclocks: no clock attached");

	hz = 1024;		/* 1024 Hz clock */
	tick = 1000000 / hz;	/* number of microseconds between interrupts */
	tickfix = 1000000 - (hz * tick);
	if (tickfix) {
		int ftp;

		ftp = min(ffs(tickfix), ffs(hz));
		tickfix >>= (ftp - 1);
		tickfixinterval = hz >> (ftp - 1);
        }

	/*
	 * Establish the clock interrupt; it's a special case.
	 *
	 * We establish the clock interrupt this late because if
	 * we do it at clock attach time, we may have never been at
	 * spl0() since taking over the system.  Some versions of
	 * PALcode save a clock interrupt, which would get delivered
	 * when we spl0() in autoconf.c.  If established the clock
	 * interrupt handler earlier, that interrupt would go to
	 * hardclock, which would then fall over because p->p_stats
	 * isn't set at that time.
	 */
	set_clockintr();

	/*
	 * Get the clock started.
	 */
	(*clockfns->cf_init)(clockdev);
}

/*
 * We assume newhz is either stathz or profhz, and that neither will
 * change after being set up above.  Could recalculate intervals here
 * but that would be a drag.
 */
void
setstatclockrate(newhz)
	int newhz;
{

	/* nothing we can do */
}

/*
 * This code is defunct after 2099.
 * Will Unix still be here then??
 */
static short dayyr[12] = {
	0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
};

/*
 * Initialze the time of day register, based on the time base which is, e.g.
 * from a filesystem.  Base provides the time to within six months,
 * and the time of year clock (if any) provides the rest.
 */
void
inittodr(base)
	time_t base;
{
	register int days, yr;
	struct clocktime ct;
	time_t deltat;
	int badbase;

	if (base < 5*SECYR) {
		printf("WARNING: preposterous time in file system");
		/* read the system clock anyway */
		base = 6*SECYR + 186*SECDAY + SECDAY/2;
		badbase = 1;
	} else
		badbase = 0;

	(*clockfns->cf_get)(clockdev, base, &ct);
	clockinitted = 1;

	/* simple sanity checks */
	if (ct.year < 70 || ct.mon < 1 || ct.mon > 12 || ct.day < 1 ||
	    ct.day > 31 || ct.hour > 23 || ct.min > 59 || ct.sec > 59) {
		/*
		 * Believe the time in the file system for lack of
		 * anything better, resetting the TODR.
		 */
		time.tv_sec = base;
		if (!badbase) {
			printf("WARNING: preposterous clock chip time\n");
			resettodr();
		}
		goto bad;
	}
	days = 0;
	for (yr = 70; yr < ct.year; yr++)
		days += LEAPYEAR(yr) ? 366 : 365;
	days += dayyr[ct.mon - 1] + ct.day - 1;
	if (LEAPYEAR(yr) && ct.mon > 2)
		days++;
	/* now have days since Jan 1, 1970; the rest is easy... */
	time.tv_sec =
	    days * SECDAY + ct.hour * SECHOUR + ct.min * SECMIN + ct.sec;

	if (!badbase) {
		/*
		 * See if we gained/lost two or more days;
		 * if so, assume something is amiss.
		 */
		deltat = time.tv_sec - base;
		if (deltat < 0)
			deltat = -deltat;
		if (deltat < 2 * SECDAY)
			return;
		printf("WARNING: clock %s %d days",
		    time.tv_sec < base ? "lost" : "gained", deltat / SECDAY);
	}
bad:
	printf(" -- CHECK AND RESET THE DATE!\n");
}

/*
 * Reset the TODR based on the time value; used when the TODR
 * has a preposterous value and also when the time is reset
 * by the stime system call.  Also called when the TODR goes past
 * TODRZERO + 100*(SECYEAR+2*SECDAY) (e.g. on Jan 2 just after midnight)
 * to wrap the TODR around.
 */
void
resettodr()
{
	register int t, t2;
	struct clocktime ct;

	if (!clockinitted)
		return;

	/* compute the day of week. */
	t2 = time.tv_sec / SECDAY;
	ct.dow = (t2 + 4) % 7;	/* 1/1/1970 was thursday */

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

	/* t = month + day; separate */
	t2 = LEAPYEAR(ct.year);
	for (ct.mon = 1; ct.mon < 12; ct.mon++)
		if (t < dayyr[ct.mon] + (t2 && ct.mon > 1))
			break;

	ct.day = t - dayyr[ct.mon - 1] + 1;
	if (t2 && ct.mon > 2)
		ct.day--;

	/* the rest is easy */
	t = time.tv_sec % SECDAY;
	ct.hour = t / SECHOUR;
	t %= 3600;
	ct.min = t / SECMIN;
	ct.sec = t % SECMIN;

	(*clockfns->cf_set)(clockdev, &ct);
}