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