clock.c revision 1.2 
1/*	$NetBSD: clock.c,v 1.2 2001/11/17 18:55:57 kleink Exp $	*/
2
3/*
4 * Copyright (C) 1995, 1996 Wolfgang Solfrank.
5 * Copyright (C) 1995, 1996 TooLs GmbH.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by TooLs GmbH.
19 * 4. The name of TooLs GmbH may not be used to endorse or promote products
20 *    derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
27 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
28 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
29 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
30 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
31 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34#include <lib/libsa/stand.h>
35#include <dev/isa/isareg.h>
36#include <dev/ic/i8253reg.h>
37
38#include "boot.h"
39
40u_long ns_per_tick = NS_PER_TICK;
41
42static inline u_quad_t mftb __P((void));
43
44static inline u_quad_t
45mftb()
46{
47	u_long scratch;
48	u_quad_t tb;
49
50	asm ("1: mftbu %0; mftb %0+1; mftbu %1; cmpw %0,%1; bne 1b"
51	    : "=r"(tb), "=r"(scratch));
52	return (tb);
53}
54
55/*
56 * Wait for about n microseconds (at least!).
57 */
58void
59delay(n)
60	u_int n;
61{
62	u_quad_t tb;
63	u_long tbh, tbl, scratch;
64
65	tb = mftb();
66	tb += (n * 1000 + ns_per_tick - 1) / ns_per_tick;
67	tbh = tb >> 32;
68	tbl = tb;
69	asm ("1: mftbu %0; cmpw %0,%1; blt 1b; bgt 2f; mftb %0; cmpw 0, %0,%2; blt 1b; 2:"
70		: "=r"(scratch) : "r"(tbh), "r"(tbl));
71}
72