/****************************************************************************** *                                                                            * * Copyright (c) David L. Mills 1993                                    * *                                                                            * * Permission to use, copy, modify, and distribute this software and its      * * documentation for any purpose and without fee is hereby granted, provided  * * that the above copyright notice appears in all copies and that both the    * * copyright notice and this permission notice appear in supporting           * * documentation, and that the name University of Delaware not be used in     * * advertising or publicity pertaining to distribution of the software        * * without specific, written prior permission.  The University of Delaware    * * makes no representations about the suitability this software for any       * * purpose.  It is provided "as is" without express or implied warranty.      * *                                                                            * ******************************************************************************//* * Modification history hightime.c * * 31 Dec 93	David L. Mills *	Created file *//* * uniqtime() - Highball counter/timer interface */#include <machine/reg.h>#include <sys/param.h>#include <sys/user.h>#include <sys/kernel.h>#include <sys/vnode.h>#include <sys/proc.h>#include <machine/clock.h>#include <machine/high.h>#include <machine/pte.h>/* * Global variables */extern int tick;			/* tick the clock tocks to */extern struct timeval time;		/* system time *//* * Local variables */static struct timeval lasttime;		/* last time returned */static struct highregs *reg = NULL;	/* data/status pointer */u_long cnt_w0, cnt_w1, cnt_w2, cnt_w3;	/* counter registers *//* * Highball error counters */long high_badtime;			/* bad highball time *//* * The clock_offset variable is the offset which converts the hardware * counters to system time. It is initialized from the kernel time * variable upon first call to uniqtime() and on each call to the * settimeofday() system call. Also, it is adjusted by the adjtime() * and ntp_adjtime() system calls with the same increment as the * kernel time variable. */struct timeval clock_offset;		/* current time offset *//* * This routine reads the seconds and microseconds from the Highball * counter/timer interface and returns a Unix timeval. It is intended as * a dropin replacement for the SunOS 4.1.x uniqtime() routine or the * Van Jacobson microtime() routine. */microtime(tvp)	struct timeval *tvp;{	uniqtime(tvp);}intuniqtime(tvp)	struct timeval *tvp;{	struct timeval dtime, htime;	long ltemp;	/*	 * Map the registers and initialize the time offset. Initialize the	 * return time from the original system time, so if anything goes	 * wrong the system doesn't lock up.	 */	if (reg == NULL) {		reg = (struct highregs *)map_regs(HIGH_ADDR + 0x2000,		    sizeof(reg), OBIO);		reg->csr = DIV5;		clock_set(&time);	}	*tvp = time;	/*	 * Read the counter registers and convert to system time.	 */	highboard(&htime);	htime.tv_sec += clock_offset.tv_sec;	htime.tv_usec += clock_offset.tv_usec;	if (htime.tv_usec > 1000000) {		htime.tv_sec++;		htime.tv_usec -= 1000000;	}	/*	 * The following makes sure the clock is monotonically advancing	 * and never stuck, unless off by more than a second. If the	 * return time is too far different from the original system time,	 * return the original system time instead.	 */	dtime.tv_sec = lasttime.tv_sec - htime.tv_sec;	dtime.tv_usec = lasttime.tv_usec - htime.tv_usec;	if (dtime.tv_usec < 0) {		dtime.tv_usec += 1000000;		dtime.tv_sec--;	}	if (dtime.tv_sec == 0) {		if (dtime.tv_usec > tick - 2)			dtime.tv_usec = tick - 2;		htime.tv_usec += dtime.tv_usec + 1;		if (htime.tv_usec >= 1000000) {			htime.tv_usec -= 1000000;			htime.tv_sec++;		}	}	lasttime = htime;	ltemp = htime.tv_sec - time.tv_sec;	if (ltemp > MAXDIFF || ltemp < -MAXDIFF) {		high_badtime++;		return (EBADTIME);	}	*tvp = htime;	return (0);}/* * clock_set(tvp) * * This routine sets the clock offset of the highball counter relative * to the time of the argument. It is called by the settimeofday() * system call through its dependencies. */clock_set(tvp)	struct timeval *tvp;{	struct timeval ntime;	clock_offset = *tvp;	highboard(&ntime);	clock_offset.tv_sec -= ntime.tv_sec;	clock_offset.tv_usec -= ntime.tv_usec;	if (clock_offset.tv_usec < 0) {		clock_offset.tv_sec--;		clock_offset.tv_usec += 1000000;	}}/* * highboard(tvp) * * Read the seconds and microseconds from the Highboard and convert to * timeval format. Each 64-bit long word of the counter array includes * 16 bits of the composite counter. Read from high to low-rder, then * compare in reverse order. If a compare discrepancy is found, do it * again. Pray for no hot/cold bits. */highboard(tvp)	struct timeval *tvp;{	while(1) {		reg->clock_strobe = 1;		cnt_w3 = reg->cnt_w3 & 0xffff;		cnt_w2 = reg->cnt_w2 & 0xffff;		cnt_w1 = reg->cnt_w1 & 0xf;		cnt_w0 = reg->cnt_w0 & 0xffff;		if (cnt_w1 != (reg->cnt_w1 & 0xf))			continue;		if (cnt_w2 != (reg->cnt_w2 & 0xffff))			continue;		if (cnt_w3 != (reg->cnt_w3 & 0xffff))			continue;		break;	}	tvp->tv_sec = (cnt_w3 << 16) + cnt_w2;	tvp->tv_usec = (cnt_w1 << 16) + cnt_w0;}