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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#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 */
31struct 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
59static inline void sema_init (struct semaphore *sem, int val)
60{
61 *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
62}
63
64static inline void init_MUTEX (struct semaphore *sem)
65{
66 sema_init(sem, 1);
67}
68
69static inline void init_MUTEX_LOCKED (struct semaphore *sem)
70{
71 sema_init(sem, 0);
72}
73
74extern void __down(struct semaphore *sem, unsigned long flags);
75extern int __down_interruptible(struct semaphore *sem, unsigned long flags);
76extern void __up(struct semaphore *sem);
77
78static 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
96static 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 */
120static 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
138static 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
154static inline int sem_getcount(struct semaphore *sem)
155{
156 return sem->counter;
157}
158
159#endif /* __ASSEMBLY__ */
160
161#endif