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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * linux/include/asm-xtensa/semaphore.h
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 2001 - 2005 Tensilica Inc.
9 */
10
11#ifndef _XTENSA_SEMAPHORE_H
12#define _XTENSA_SEMAPHORE_H
13
14#include <asm/atomic.h>
15#include <asm/system.h>
16#include <linux/wait.h>
17#include <linux/rwsem.h>
18
19struct semaphore {
20 atomic_t count;
21 int sleepers;
22 wait_queue_head_t wait;
23};
24
25#define __SEMAPHORE_INITIALIZER(name,n) \
26{ \
27 .count = ATOMIC_INIT(n), \
28 .sleepers = 0, \
29 .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
30}
31
32#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
33 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
34
35#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
36
37static inline void sema_init (struct semaphore *sem, int val)
38{
39 atomic_set(&sem->count, val);
40 sem->sleepers = 0;
41 init_waitqueue_head(&sem->wait);
42}
43
44static inline void init_MUTEX (struct semaphore *sem)
45{
46 sema_init(sem, 1);
47}
48
49static inline void init_MUTEX_LOCKED (struct semaphore *sem)
50{
51 sema_init(sem, 0);
52}
53
54asmlinkage void __down(struct semaphore * sem);
55asmlinkage int __down_interruptible(struct semaphore * sem);
56asmlinkage int __down_trylock(struct semaphore * sem);
57asmlinkage void __up(struct semaphore * sem);
58
59extern spinlock_t semaphore_wake_lock;
60
61static inline void down(struct semaphore * sem)
62{
63 might_sleep();
64
65 if (atomic_sub_return(1, &sem->count) < 0)
66 __down(sem);
67}
68
69static inline int down_interruptible(struct semaphore * sem)
70{
71 int ret = 0;
72
73 might_sleep();
74
75 if (atomic_sub_return(1, &sem->count) < 0)
76 ret = __down_interruptible(sem);
77 return ret;
78}
79
80static inline int down_trylock(struct semaphore * sem)
81{
82 int ret = 0;
83
84 if (atomic_sub_return(1, &sem->count) < 0)
85 ret = __down_trylock(sem);
86 return ret;
87}
88
89/*
90 * Note! This is subtle. We jump to wake people up only if
91 * the semaphore was negative (== somebody was waiting on it).
92 */
93static inline void up(struct semaphore * sem)
94{
95 if (atomic_add_return(1, &sem->count) <= 0)
96 __up(sem);
97}
98
99#endif /* _XTENSA_SEMAPHORE_H */