Annotation of sys/arch/arm/include/lock.h, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: lock.h,v 1.2 2004/12/30 23:31:02 drahn Exp $ */
2: /* $NetBSD: lock.h,v 1.3 2002/10/07 23:19:49 bjh21 Exp $ */
3:
4: /*-
5: * Copyright (c) 2000, 2001 The NetBSD Foundation, Inc.
6: * All rights reserved.
7: *
8: * This code is derived from software contributed to The NetBSD Foundation
9: * by Jason R. Thorpe.
10: *
11: * Redistribution and use in source and binary forms, with or without
12: * modification, are permitted provided that the following conditions
13: * are met:
14: * 1. Redistributions of source code must retain the above copyright
15: * notice, this list of conditions and the following disclaimer.
16: * 2. Redistributions in binary form must reproduce the above copyright
17: * notice, this list of conditions and the following disclaimer in the
18: * documentation and/or other materials provided with the distribution.
19: * 3. All advertising materials mentioning features or use of this software
20: * must display the following acknowledgement:
21: * This product includes software developed by the NetBSD
22: * Foundation, Inc. and its contributors.
23: * 4. Neither the name of The NetBSD Foundation nor the names of its
24: * contributors may be used to endorse or promote products derived
25: * from this software without specific prior written permission.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28: * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29: * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30: * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31: * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32: * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33: * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34: * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35: * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36: * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37: * POSSIBILITY OF SUCH DAMAGE.
38: */
39:
40: /*
41: * Machine-dependent spin lock operations.
42: *
43: * NOTE: The SWP insn used here is available only on ARM architecture
44: * version 3 and later (as well as 2a). What we are going to do is
45: * expect that the kernel will trap and emulate the insn. That will
46: * be slow, but give us the atomicity that we need.
47: */
48:
49: #ifndef _ARM_LOCK_H_
50: #define _ARM_LOCK_H_
51:
52: typedef __volatile int __cpu_simple_lock_t;
53:
54: #define __SIMPLELOCK_LOCKED 1
55: #define __SIMPLELOCK_UNLOCKED 0
56:
57: static __inline int
58: __swp(int __val, __volatile int *__ptr)
59: {
60:
61: __asm __volatile("swp %0, %1, [%2]"
62: : "=r" (__val) : "r" (__val), "r" (__ptr) : "memory");
63: return __val;
64: }
65:
66: static __inline void __attribute__((__unused__))
67: __cpu_simple_lock_init(__cpu_simple_lock_t *alp)
68: {
69:
70: *alp = __SIMPLELOCK_UNLOCKED;
71: }
72:
73: static __inline void __attribute__((__unused__))
74: __cpu_simple_lock(__cpu_simple_lock_t *alp)
75: {
76:
77: while (__swp(__SIMPLELOCK_LOCKED, alp) != __SIMPLELOCK_UNLOCKED)
78: continue;
79: }
80:
81: static __inline int __attribute__((__unused__))
82: __cpu_simple_lock_try(__cpu_simple_lock_t *alp)
83: {
84:
85: return (__swp(__SIMPLELOCK_LOCKED, alp) == __SIMPLELOCK_UNLOCKED);
86: }
87:
88: static __inline void __attribute__((__unused__))
89: __cpu_simple_unlock(__cpu_simple_lock_t *alp)
90: {
91:
92: *alp = __SIMPLELOCK_UNLOCKED;
93: }
94:
95: #endif /* _ARM_LOCK_H_ */
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