aboutsummaryrefslogtreecommitdiff
path: root/include/asm-frv/semaphore.h
blob: d7aaa1911a1afed07771d7eed8437cb196bcf061 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
/* semaphore.h: semaphores for the FR-V
 *
 * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#ifndef _ASM_SEMAPHORE_H
#define _ASM_SEMAPHORE_H

#define RW_LOCK_BIAS		 0x01000000

#ifndef __ASSEMBLY__

#include <linux/linkage.h>
#include <linux/wait.h>
#include <linux/spinlock.h>
#include <linux/rwsem.h>

/*
 * the semaphore definition
 * - if counter is >0 then there are tokens available on the semaphore for down to collect
 * - if counter is <=0 then there are no spare tokens, and anyone that wants one must wait
 * - if wait_list is not empty, then there are processes waiting for the semaphore
 */
struct semaphore {
	unsigned		counter;
	spinlock_t		wait_lock;
	struct list_head	wait_list;
#ifdef CONFIG_DEBUG_SEMAPHORE
	unsigned		__magic;
#endif
};

#ifdef CONFIG_DEBUG_SEMAPHORE
# define __SEM_DEBUG_INIT(name) , (long)&(name).__magic
#else
# define __SEM_DEBUG_INIT(name)
#endif


#define __SEMAPHORE_INITIALIZER(name,count) \
{ count, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __SEM_DEBUG_INIT(name) }

#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
	struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)

#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)

static inline void sema_init (struct semaphore *sem, int val)
{
	*sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
}

static inline void init_MUTEX (struct semaphore *sem)
{
	sema_init(sem, 1);
}

static inline void init_MUTEX_LOCKED (struct semaphore *sem)
{
	sema_init(sem, 0);
}

extern void __down(struct semaphore *sem, unsigned long flags);
extern int  __down_interruptible(struct semaphore *sem, unsigned long flags);
extern void __up(struct semaphore *sem);

static inline void down(struct semaphore *sem)
{
	unsigned long flags;

#ifdef CONFIG_DEBUG_SEMAPHORE
	CHECK_MAGIC(sem->__magic);
#endif

	spin_lock_irqsave(&sem->wait_lock, flags);
	if (likely(sem->counter > 0)) {
		sem->counter--;
		spin_unlock_irqrestore(&sem->wait_lock, flags);
	}
	else {
		__down(sem, flags);
	}
}

static inline int down_interruptible(struct semaphore *sem)
{
	unsigned long flags;
	int ret = 0;

#ifdef CONFIG_DEBUG_SEMAPHORE
	CHECK_MAGIC(sem->__magic);
#endif

	spin_lock_irqsave(&sem->wait_lock, flags);
	if (likely(sem->counter > 0)) {
		sem->counter--;
		spin_unlock_irqrestore(&sem->wait_lock, flags);
	}
	else {
		ret = __down_interruptible(sem, flags);
	}
	return ret;
}

/*
 * non-blockingly attempt to down() a semaphore.
 * - returns zero if we acquired it
 */
static inline int down_trylock(struct semaphore *sem)
{
	unsigned long flags;
	int success = 0;

#ifdef CONFIG_DEBUG_SEMAPHORE
	CHECK_MAGIC(sem->__magic);
#endif

	spin_lock_irqsave(&sem->wait_lock, flags);
	if (sem->counter > 0) {
		sem->counter--;
		success = 1;
	}
	spin_unlock_irqrestore(&sem->wait_lock, flags);
	return !success;
}

static inline void up(struct semaphore *sem)
{
	unsigned long flags;

#ifdef CONFIG_DEBUG_SEMAPHORE
	CHECK_MAGIC(sem->__magic);
#endif

	spin_lock_irqsave(&sem->wait_lock, flags);
	if (!list_empty(&sem->wait_list))
		__up(sem);
	else
		sem->counter++;
	spin_unlock_irqrestore(&sem->wait_lock, flags);
}

static inline int sem_getcount(struct semaphore *sem)
{
	return sem->counter;
}

#endif /* __ASSEMBLY__ */

#endif