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1da177e4 LT |
1 | /* semaphore.h: semaphores for the FR-V |
2 | * | |
3 | * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | #ifndef _ASM_SEMAPHORE_H | |
12 | #define _ASM_SEMAPHORE_H | |
13 | ||
14 | #define RW_LOCK_BIAS 0x01000000 | |
15 | ||
16 | #ifndef __ASSEMBLY__ | |
17 | ||
18 | #include <linux/linkage.h> | |
19 | #include <linux/wait.h> | |
20 | #include <linux/spinlock.h> | |
21 | #include <linux/rwsem.h> | |
22 | ||
23 | #define SEMAPHORE_DEBUG WAITQUEUE_DEBUG | |
24 | ||
25 | /* | |
26 | * the semaphore definition | |
27 | * - if counter is >0 then there are tokens available on the semaphore for down to collect | |
28 | * - if counter is <=0 then there are no spare tokens, and anyone that wants one must wait | |
29 | * - if wait_list is not empty, then there are processes waiting for the semaphore | |
30 | */ | |
31 | struct semaphore { | |
32 | unsigned counter; | |
33 | spinlock_t wait_lock; | |
34 | struct list_head wait_list; | |
35 | #if SEMAPHORE_DEBUG | |
36 | unsigned __magic; | |
37 | #endif | |
38 | }; | |
39 | ||
40 | #if SEMAPHORE_DEBUG | |
41 | # define __SEM_DEBUG_INIT(name) , (long)&(name).__magic | |
42 | #else | |
43 | # define __SEM_DEBUG_INIT(name) | |
44 | #endif | |
45 | ||
46 | ||
47 | #define __SEMAPHORE_INITIALIZER(name,count) \ | |
48 | { count, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __SEM_DEBUG_INIT(name) } | |
49 | ||
50 | #define __MUTEX_INITIALIZER(name) \ | |
51 | __SEMAPHORE_INITIALIZER(name,1) | |
52 | ||
53 | #define __DECLARE_SEMAPHORE_GENERIC(name,count) \ | |
54 | struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) | |
55 | ||
56 | #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) | |
57 | #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) | |
58 | ||
59 | static inline void sema_init (struct semaphore *sem, int val) | |
60 | { | |
61 | *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val); | |
62 | } | |
63 | ||
64 | static inline void init_MUTEX (struct semaphore *sem) | |
65 | { | |
66 | sema_init(sem, 1); | |
67 | } | |
68 | ||
69 | static inline void init_MUTEX_LOCKED (struct semaphore *sem) | |
70 | { | |
71 | sema_init(sem, 0); | |
72 | } | |
73 | ||
74 | extern void __down(struct semaphore *sem, unsigned long flags); | |
75 | extern int __down_interruptible(struct semaphore *sem, unsigned long flags); | |
76 | extern void __up(struct semaphore *sem); | |
77 | ||
78 | static inline void down(struct semaphore *sem) | |
79 | { | |
80 | unsigned long flags; | |
81 | ||
82 | #if SEMAPHORE_DEBUG | |
83 | CHECK_MAGIC(sem->__magic); | |
84 | #endif | |
85 | ||
86 | spin_lock_irqsave(&sem->wait_lock, flags); | |
87 | if (likely(sem->counter > 0)) { | |
88 | sem->counter--; | |
89 | spin_unlock_irqrestore(&sem->wait_lock, flags); | |
90 | } | |
91 | else { | |
92 | __down(sem, flags); | |
93 | } | |
94 | } | |
95 | ||
96 | static inline int down_interruptible(struct semaphore *sem) | |
97 | { | |
98 | unsigned long flags; | |
99 | int ret = 0; | |
100 | ||
101 | #if SEMAPHORE_DEBUG | |
102 | CHECK_MAGIC(sem->__magic); | |
103 | #endif | |
104 | ||
105 | spin_lock_irqsave(&sem->wait_lock, flags); | |
106 | if (likely(sem->counter > 0)) { | |
107 | sem->counter--; | |
108 | spin_unlock_irqrestore(&sem->wait_lock, flags); | |
109 | } | |
110 | else { | |
111 | ret = __down_interruptible(sem, flags); | |
112 | } | |
113 | return ret; | |
114 | } | |
115 | ||
116 | /* | |
117 | * non-blockingly attempt to down() a semaphore. | |
118 | * - returns zero if we acquired it | |
119 | */ | |
120 | static inline int down_trylock(struct semaphore *sem) | |
121 | { | |
122 | unsigned long flags; | |
123 | int success = 0; | |
124 | ||
125 | #if SEMAPHORE_DEBUG | |
126 | CHECK_MAGIC(sem->__magic); | |
127 | #endif | |
128 | ||
129 | spin_lock_irqsave(&sem->wait_lock, flags); | |
130 | if (sem->counter > 0) { | |
131 | sem->counter--; | |
132 | success = 1; | |
133 | } | |
134 | spin_unlock_irqrestore(&sem->wait_lock, flags); | |
135 | return !success; | |
136 | } | |
137 | ||
138 | static inline void up(struct semaphore *sem) | |
139 | { | |
140 | unsigned long flags; | |
141 | ||
142 | #if SEMAPHORE_DEBUG | |
143 | CHECK_MAGIC(sem->__magic); | |
144 | #endif | |
145 | ||
146 | spin_lock_irqsave(&sem->wait_lock, flags); | |
147 | if (!list_empty(&sem->wait_list)) | |
148 | __up(sem); | |
149 | else | |
150 | sem->counter++; | |
151 | spin_unlock_irqrestore(&sem->wait_lock, flags); | |
152 | } | |
153 | ||
154 | static inline int sem_getcount(struct semaphore *sem) | |
155 | { | |
156 | return sem->counter; | |
157 | } | |
158 | ||
159 | #endif /* __ASSEMBLY__ */ | |
160 | ||
161 | #endif |