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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/*
24 * the semaphore definition
25 * - if counter is >0 then there are tokens available on the semaphore for down to collect
26 * - if counter is <=0 then there are no spare tokens, and anyone that wants one must wait
27 * - if wait_list is not empty, then there are processes waiting for the semaphore
28 */
29struct semaphore {
30 unsigned counter;
31 spinlock_t wait_lock;
32 struct list_head wait_list;
33#ifdef CONFIG_DEBUG_SEMAPHORE
34 unsigned __magic;
35#endif
36};
37
38#ifdef CONFIG_DEBUG_SEMAPHORE
39# define __SEM_DEBUG_INIT(name) , (long)&(name).__magic
40#else
41# define __SEM_DEBUG_INIT(name)
42#endif
43
44
45#define __SEMAPHORE_INITIALIZER(name,count) \
46{ count, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __SEM_DEBUG_INIT(name) }
47
48#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
49 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
50
51#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
52
53static inline void sema_init (struct semaphore *sem, int val)
54{
55 *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
56}
57
58static inline void init_MUTEX (struct semaphore *sem)
59{
60 sema_init(sem, 1);
61}
62
63static inline void init_MUTEX_LOCKED (struct semaphore *sem)
64{
65 sema_init(sem, 0);
66}
67
68extern void __down(struct semaphore *sem, unsigned long flags);
69extern int __down_interruptible(struct semaphore *sem, unsigned long flags);
70extern void __up(struct semaphore *sem);
71
72static inline void down(struct semaphore *sem)
73{
74 unsigned long flags;
75
76#ifdef CONFIG_DEBUG_SEMAPHORE
77 CHECK_MAGIC(sem->__magic);
78#endif
79
80 spin_lock_irqsave(&sem->wait_lock, flags);
81 if (likely(sem->counter > 0)) {
82 sem->counter--;
83 spin_unlock_irqrestore(&sem->wait_lock, flags);
84 }
85 else {
86 __down(sem, flags);
87 }
88}
89
90static inline int down_interruptible(struct semaphore *sem)
91{
92 unsigned long flags;
93 int ret = 0;
94
95#ifdef CONFIG_DEBUG_SEMAPHORE
96 CHECK_MAGIC(sem->__magic);
97#endif
98
99 spin_lock_irqsave(&sem->wait_lock, flags);
100 if (likely(sem->counter > 0)) {
101 sem->counter--;
102 spin_unlock_irqrestore(&sem->wait_lock, flags);
103 }
104 else {
105 ret = __down_interruptible(sem, flags);
106 }
107 return ret;
108}
109
110/*
111 * non-blockingly attempt to down() a semaphore.
112 * - returns zero if we acquired it
113 */
114static inline int down_trylock(struct semaphore *sem)
115{
116 unsigned long flags;
117 int success = 0;
118
119#ifdef CONFIG_DEBUG_SEMAPHORE
120 CHECK_MAGIC(sem->__magic);
121#endif
122
123 spin_lock_irqsave(&sem->wait_lock, flags);
124 if (sem->counter > 0) {
125 sem->counter--;
126 success = 1;
127 }
128 spin_unlock_irqrestore(&sem->wait_lock, flags);
129 return !success;
130}
131
132static inline void up(struct semaphore *sem)
133{
134 unsigned long flags;
135
136#ifdef CONFIG_DEBUG_SEMAPHORE
137 CHECK_MAGIC(sem->__magic);
138#endif
139
140 spin_lock_irqsave(&sem->wait_lock, flags);
141 if (!list_empty(&sem->wait_list))
142 __up(sem);
143 else
144 sem->counter++;
145 spin_unlock_irqrestore(&sem->wait_lock, flags);
146}
147
148static inline int sem_getcount(struct semaphore *sem)
149{
150 return sem->counter;
151}
152
153#endif /* __ASSEMBLY__ */
154
155#endif