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#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
37
38static inline void sema_init (struct semaphore *sem, int val)
39{
40	atomic_set(&sem->count, val);
41	sem->sleepers = 0;
42	init_waitqueue_head(&sem->wait);
43}
44
45static inline void init_MUTEX (struct semaphore *sem)
46{
47	sema_init(sem, 1);
48}
49
50static inline void init_MUTEX_LOCKED (struct semaphore *sem)
51{
52	sema_init(sem, 0);
53}
54
55asmlinkage void __down(struct semaphore * sem);
56asmlinkage int  __down_interruptible(struct semaphore * sem);
57asmlinkage int  __down_trylock(struct semaphore * sem);
58asmlinkage void __up(struct semaphore * sem);
59
60extern spinlock_t semaphore_wake_lock;
61
62static inline void down(struct semaphore * sem)
63{
64	might_sleep();
65
66	if (atomic_sub_return(1, &sem->count) < 0)
67		__down(sem);
68}
69
70static inline int down_interruptible(struct semaphore * sem)
71{
72	int ret = 0;
73
74	might_sleep();
75
76	if (atomic_sub_return(1, &sem->count) < 0)
77		ret = __down_interruptible(sem);
78	return ret;
79}
80
81static inline int down_trylock(struct semaphore * sem)
82{
83	int ret = 0;
84
85	if (atomic_sub_return(1, &sem->count) < 0)
86		ret = __down_trylock(sem);
87	return ret;
88}
89
90/*
91 * Note! This is subtle. We jump to wake people up only if
92 * the semaphore was negative (== somebody was waiting on it).
93 */
94static inline void up(struct semaphore * sem)
95{
96	if (atomic_add_return(1, &sem->count) <= 0)
97		__up(sem);
98}
99
100#endif /* _XTENSA_SEMAPHORE_H */
101