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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 __DECLARE_SEMAPHORE_GENERIC(name,count) \
51 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
52
53#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
54#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
55
56static inline void sema_init (struct semaphore *sem, int val)
57{
58 *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
59}
60
61static inline void init_MUTEX (struct semaphore *sem)
62{
63 sema_init(sem, 1);
64}
65
66static inline void init_MUTEX_LOCKED (struct semaphore *sem)
67{
68 sema_init(sem, 0);
69}
70
71extern void __down(struct semaphore *sem, unsigned long flags);
72extern int __down_interruptible(struct semaphore *sem, unsigned long flags);
73extern void __up(struct semaphore *sem);
74
75static inline void down(struct semaphore *sem)
76{
77 unsigned long flags;
78
79#if SEMAPHORE_DEBUG
80 CHECK_MAGIC(sem->__magic);
81#endif
82
83 spin_lock_irqsave(&sem->wait_lock, flags);
84 if (likely(sem->counter > 0)) {
85 sem->counter--;
86 spin_unlock_irqrestore(&sem->wait_lock, flags);
87 }
88 else {
89 __down(sem, flags);
90 }
91}
92
93static inline int down_interruptible(struct semaphore *sem)
94{
95 unsigned long flags;
96 int ret = 0;
97
98#if SEMAPHORE_DEBUG
99 CHECK_MAGIC(sem->__magic);
100#endif
101
102 spin_lock_irqsave(&sem->wait_lock, flags);
103 if (likely(sem->counter > 0)) {
104 sem->counter--;
105 spin_unlock_irqrestore(&sem->wait_lock, flags);
106 }
107 else {
108 ret = __down_interruptible(sem, flags);
109 }
110 return ret;
111}
112
113/*
114 * non-blockingly attempt to down() a semaphore.
115 * - returns zero if we acquired it
116 */
117static inline int down_trylock(struct semaphore *sem)
118{
119 unsigned long flags;
120 int success = 0;
121
122#if SEMAPHORE_DEBUG
123 CHECK_MAGIC(sem->__magic);
124#endif
125
126 spin_lock_irqsave(&sem->wait_lock, flags);
127 if (sem->counter > 0) {
128 sem->counter--;
129 success = 1;
130 }
131 spin_unlock_irqrestore(&sem->wait_lock, flags);
132 return !success;
133}
134
135static inline void up(struct semaphore *sem)
136{
137 unsigned long flags;
138
139#if SEMAPHORE_DEBUG
140 CHECK_MAGIC(sem->__magic);
141#endif
142
143 spin_lock_irqsave(&sem->wait_lock, flags);
144 if (!list_empty(&sem->wait_list))
145 __up(sem);
146 else
147 sem->counter++;
148 spin_unlock_irqrestore(&sem->wait_lock, flags);
149}
150
151static inline int sem_getcount(struct semaphore *sem)
152{
153 return sem->counter;
154}
155
156#endif /* __ASSEMBLY__ */
157
158#endif