lock.h revision 1.8 
1/*	$NetBSD: lock.h,v 1.8 2005/12/28 19:09:29 perry Exp $	*/
2
3/*-
4 * Copyright (c) 2000 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the NetBSD
21 *	Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 *    contributors may be used to endorse or promote products derived
24 *    from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39/*
40 * Machine-dependent spin lock operations.
41 */
42
43#ifndef _POWERPC_LOCK_H_
44#define _POWERPC_LOCK_H_
45
46static __inline void
47__cpu_simple_lock_init(__cpu_simple_lock_t *alp)
48{
49	*alp = __SIMPLELOCK_UNLOCKED;
50	__asm volatile ("sync");
51}
52
53static __inline void
54__cpu_simple_lock(__cpu_simple_lock_t *alp)
55{
56	int old;
57
58	__asm volatile ("	\
59				\n\
601:	lwarx	%0,0,%1		\n\
61	cmpwi	%0,%2		\n\
62	beq+	3f		\n\
632:	lwzx	%0,0,%1		\n\
64	cmpwi	%0,%2		\n\
65	beq+	1b		\n\
66	b	2b		\n\
673:	stwcx.	%3,0,%1		\n\
68	bne-	1b		\n\
69	isync			\n\
70				\n"
71	: "=&r"(old)
72	: "r"(alp), "I"(__SIMPLELOCK_UNLOCKED), "r"(__SIMPLELOCK_LOCKED)
73	: "memory");
74}
75
76static __inline int
77__cpu_simple_lock_try(__cpu_simple_lock_t *alp)
78{
79	int old, dummy;
80
81	__asm volatile ("	\
82				\n\
831:	lwarx	%0,0,%1		\n\
84	cmpwi	%0,%2		\n\
85	bne	2f		\n\
86	stwcx.	%3,0,%1		\n\
87	bne-	1b		\n\
882:	stwcx.	%3,0,%4		\n\
89	isync			\n\
90				\n"
91	: "=&r"(old)
92	: "r"(alp), "I"(__SIMPLELOCK_UNLOCKED), "r"(__SIMPLELOCK_LOCKED),
93	  "r"(&dummy)
94	: "memory");
95
96	return (old == __SIMPLELOCK_UNLOCKED);
97}
98
99static __inline void
100__cpu_simple_unlock(__cpu_simple_lock_t *alp)
101{
102	__asm volatile ("sync");
103	*alp = __SIMPLELOCK_UNLOCKED;
104}
105
106#endif /* _POWERPC_LOCK_H_ */
107