lock.h revision 1.7 1 1.7 thorpej /* $NetBSD: lock.h,v 1.7 2000/04/29 03:31:55 thorpej Exp $ */
2 1.1 pk
3 1.1 pk /*-
4 1.4 thorpej * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
5 1.1 pk * All rights reserved.
6 1.1 pk *
7 1.1 pk * This code is derived from software contributed to The NetBSD Foundation
8 1.1 pk * by Paul Kranenburg.
9 1.1 pk *
10 1.1 pk * Redistribution and use in source and binary forms, with or without
11 1.1 pk * modification, are permitted provided that the following conditions
12 1.1 pk * are met:
13 1.1 pk * 1. Redistributions of source code must retain the above copyright
14 1.1 pk * notice, this list of conditions and the following disclaimer.
15 1.1 pk * 2. Redistributions in binary form must reproduce the above copyright
16 1.1 pk * notice, this list of conditions and the following disclaimer in the
17 1.1 pk * documentation and/or other materials provided with the distribution.
18 1.1 pk * 3. All advertising materials mentioning features or use of this software
19 1.1 pk * must display the following acknowledgement:
20 1.1 pk * This product includes software developed by the NetBSD
21 1.1 pk * Foundation, Inc. and its contributors.
22 1.1 pk * 4. Neither the name of The NetBSD Foundation nor the names of its
23 1.1 pk * contributors may be used to endorse or promote products derived
24 1.1 pk * from this software without specific prior written permission.
25 1.1 pk *
26 1.1 pk * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 1.1 pk * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 1.1 pk * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 1.1 pk * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 1.1 pk * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 1.1 pk * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 1.1 pk * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 1.1 pk * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 1.1 pk * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 1.1 pk * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 1.1 pk * POSSIBILITY OF SUCH DAMAGE.
37 1.1 pk */
38 1.1 pk
39 1.1 pk #ifndef _MACHINE_LOCK_H
40 1.1 pk #define _MACHINE_LOCK_H
41 1.1 pk
42 1.1 pk /*
43 1.1 pk * Machine dependent spin lock operations.
44 1.1 pk */
45 1.1 pk
46 1.5 thorpej /*
47 1.7 thorpej * The value for __SIMPLELOCK_LOCKED is what ldstub() naturally stores
48 1.5 thorpej * `lock_data' given its address (and the fact that SPARC is big-endian).
49 1.5 thorpej */
50 1.7 thorpej #define __SIMPLELOCK_LOCKED 0xff000000
51 1.7 thorpej #define __SIMPLELOCK_UNLOCKED 0
52 1.5 thorpej
53 1.7 thorpej /* XXX So we can expose this to userland. */
54 1.7 thorpej #define __ldstub(__addr) \
55 1.7 thorpej ({ \
56 1.7 thorpej __v; \
57 1.7 thorpej \
58 1.7 thorpej __asm __volatile("ldstub [%1],%0" \
59 1.7 thorpej : "=r" (__v) \
60 1.7 thorpej : "r" (__addr) \
61 1.7 thorpej : "memory"); \
62 1.7 thorpej \
63 1.7 thorpej __v; \
64 1.7 thorpej })
65 1.7 thorpej
66 1.7 thorpej static __inline void __cpu_simple_lock_init __P((__volatile int *))
67 1.7 thorpej __attribute__((__unused__));
68 1.7 thorpej static __inline void __cpu_simple_lock __P((__volatile int *))
69 1.7 thorpej __attribute__((__unused__));
70 1.7 thorpej static __inline int __cpu_simple_lock_try __P((__volatile int *))
71 1.7 thorpej __attribute__((__unused__));
72 1.7 thorpej static __inline void __cpu_simple_unlock __P((__volatile int *))
73 1.7 thorpej __attribute__((__unused__));
74 1.7 thorpej
75 1.7 thorpej static __inline void
76 1.7 thorpej __cpu_simple_lock_init(__volatile int *alp)
77 1.1 pk {
78 1.2 pk
79 1.7 thorpej *alp = __SIMPLELOCK_UNLOCKED;
80 1.1 pk }
81 1.1 pk
82 1.7 thorpej static __inline void
83 1.7 thorpej __cpu_simple_lock(__volatile int *alp)
84 1.1 pk {
85 1.2 pk
86 1.2 pk /*
87 1.7 thorpej * If someone else holds the lock use simple reads until it
88 1.7 thorpej * is released, then retry the atomic operation. This reduces
89 1.7 thorpej * memory bus contention because the cache-coherency logic
90 1.7 thorpej * does not have to broadcast invalidates on the lock while
91 1.7 thorpej * we spin on it.
92 1.2 pk */
93 1.7 thorpej while (__ldstub(alp) != __SIMPLELOCK_UNLOCKED) {
94 1.7 thorpej while (*alp != __SIMPLELOCK_UNLOCKED)
95 1.7 thorpej /* spin */ ;
96 1.2 pk }
97 1.1 pk }
98 1.1 pk
99 1.7 thorpej static __inline int
100 1.7 thorpej __cpu_simple_lock_try(__volatile int *alp)
101 1.1 pk {
102 1.2 pk
103 1.7 thorpej return (__ldstub(alp) == __SIMPLELOCK_UNLOCKED);
104 1.1 pk }
105 1.1 pk
106 1.7 thorpej static __inline void
107 1.7 thorpej __cpu_simple_unlock(__volatile int *alp)
108 1.1 pk {
109 1.2 pk
110 1.7 thorpej *alp = __SIMPLELOCK_UNLOCKED;
111 1.1 pk }
112 1.1 pk
113 1.1 pk #endif /* _MACHINE_LOCK_H */
114