NetBSD/sys/arch/prep/prep/clock.c

/*	$NetBSD: clock.c,v 1.1 2000/02/29 15:21:47 nonaka Exp $	*/
/*      $OpenBSD: clock.c,v 1.3 1997/10/13 13:42:53 pefo 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 <sys/device.h>

#include <dev/clock_subr.h>

#include <prep/prep/clockvar.h>

#define	MINYEAR	1990

void decr_intr __P((struct clockframe *));
static inline u_quad_t mftb __P((void));

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

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

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

	printf("\n");

	if (clockfns != NULL)
		panic("clockattach: multiple clocks");

	clockdev = dev;
	clockfns = fns;
}

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

	ticks_per_intr = ticks_per_sec / hz;
	asm volatile ("mftb %0" : "=r"(lasttb));
	asm volatile ("mtdec %0" :: "r"(ticks_per_intr));
}

/*
 * Initialize the time of day register, based on the time base which is, e.g.
 * from a filesystem.
 */
void
inittodr(base)
	time_t base;
{
	struct clocktime ct;
	int year;
	struct clock_ymdhms dt;
	time_t deltat;
	int badbase = 0;

	if (base < (MINYEAR - 1970) * SECYR) {
		printf("WARNING: preposterous time in file system");
		/* read the system clock anyway */
		base = (MINYEAR - 1970) * SECYR + 186 * SECDAY + SECDAY / 2;
		badbase = 1;
	}

	(*clockfns->cf_get)(clockdev, base, &ct);
#ifdef DEBUG
	printf("readclock: %d/%d/%d/%d/%d/%d", ct.year, ct.mon, ct.day,
	    ct.hour, ct.min, ct.sec);
#endif
	clockinitted = 1;

	year = 1900 + ct.year;
	if (year < 1970)
		year += 100;

	/* simple sanity checks (2037 = time_t overflow) */
	if (year < MINYEAR || year > 2037 ||
	    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;
	}

	dt.dt_year = year;
	dt.dt_mon = ct.mon;
	dt.dt_day = ct.day;
	dt.dt_hour = ct.hour;
	dt.dt_min = ct.min;
	dt.dt_sec = ct.sec;
	time.tv_sec = clock_ymdhms_to_secs(&dt);
#ifdef DEBUG
	printf("=>%ld (%d)\n", time.tv_sec, base);
#endif

	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 %ld days",
		    time.tv_sec < base ? "lost" : "gained",
		    (long)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()
{
	struct clock_ymdhms dt;
	struct clocktime ct;

	if (!clockinitted)
		return;

	clock_secs_to_ymdhms(time.tv_sec, &dt);

	/* rt clock wants 2 digits */
	ct.year = dt.dt_year % 100;
	ct.mon = dt.dt_mon;
	ct.day = dt.dt_day;
	ct.hour = dt.dt_hour;
	ct.min = dt.dt_min;
	ct.sec = dt.dt_sec;
	ct.dow = dt.dt_wday;
#ifdef DEBUG
	printf("setclock: %d/%d/%d/%d/%d/%d\n", ct.year, ct.mon, ct.day,
	    ct.hour, ct.min, ct.sec);
#endif

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

/*
 * 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(arg)
	int arg;
{

	/* Nothing we can do */
}

void
decr_intr(frame)
	struct clockframe *frame;
{
	int msr;
	int pri;
	u_long tb;
	long tick;
	int nticks;
	extern long intrcnt[];

	/*
	 * 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.
	 */
	asm ("mftb %0; mfdec %1" : "=r"(tb), "=r"(tick));
	for (nticks = 0; tick < 0; nticks++)
		tick += ticks_per_intr;
	asm volatile ("mtdec %0" :: "r"(tick));

	/*
	 * lasttb is used during microtime. Set it to the virtual
	 * start of this tick interval.
	 */
	lasttb = tb + tick - ticks_per_intr;

	intrcnt[CNT_CLOCK]++;

	pri = splclock();
	if (pri & SPL_CLOCK)
		tickspending += nticks;
	else {
		nticks += tickspending;
		tickspending = 0;

		/*
		 * Reenable interrupts
		 */
		asm volatile ("mfmsr %0; ori %0, %0, %1; mtmsr %0"
			      : "=r"(msr) : "K"(PSL_EE));
		
		/*
		 * Do standard timer interrupt stuff.
		 * Do softclock stuff only on the last iteration.
		 */
		frame->pri = pri | SINT_CLOCK;
		while (--nticks > 0)
			hardclock(frame);
		frame->pri = pri;
		hardclock(frame);
	}
	splx(pri);
}

static inline u_quad_t
mftb()
{
	u_long scratch;
	u_quad_t tb;
	
	asm ("1: mftbu %0; mftb %0+1; mftbu %1; cmpw %0,%1; bne 1b"
	    : "=r"(tb), "=r"(scratch));
	return tb;
}

/*
 * Fill in *tvp with current time with microsecond resolution.
 */
void
microtime(tvp)
	struct timeval *tvp;
{
	u_long tb;
	u_long ticks;
	int msr, scratch;
	
	asm volatile ("mfmsr %0; andi. %1,%0,%2; mtmsr %1"
		      : "=r"(msr), "=r"(scratch) : "K"((u_short)~PSL_EE));
	asm ("mftb %0" : "=r"(tb));
	ticks = (tb - lasttb) * ns_per_tick;
	*tvp = time;
	asm volatile ("mtmsr %0" :: "r"(msr));
	ticks /= 1000;
	tvp->tv_usec += ticks;
	while (tvp->tv_usec >= 1000000) {
		tvp->tv_usec -= 1000000;
		tvp->tv_sec++;
	}
}

/*
 * Wait for about n microseconds (at least!).
 */
void
delay(n)
	unsigned int n;
{
	u_quad_t tb;
	u_long tbh, tbl, scratch;
	
	tb = mftb();
	tb += (n * 1000 + ns_per_tick - 1) / ns_per_tick;
	tbh = tb >> 32;
	tbl = tb;
	asm ("1: mftbu %0; cmpw %0,%1; blt 1b; bgt 2f; mftb %0; cmpw %0,%2; blt 1b; 2:"
	     :: "r"(scratch), "r"(tbh), "r"(tbl));
}