xref: /src/sys/arch/prep/stand/boot/clock.c

/*	$NetBSD: clock.c,v 1.1 2000/02/29 15:21:48 nonaka 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 <lib/libsa/stand.h>
#include <dev/isa/isareg.h>
#include <dev/ic/i8253reg.h>

#include "boot.h"

u_long ns_per_tick = NS_PER_TICK;

static inline u_quad_t mftb __P((void));

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);
}

/*
 * Wait for about n microseconds (at least!).
 */
void
delay(n)
	u_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, %0,%2; blt 1b; 2:"
		:: "r"(scratch), "r"(tbh), "r"(tbl));
}