summaryrefslogtreecommitdiffstats
path: root/include/asm-ppc/semaphore.h
blob: 92063a8689ca47b01f1311fe6985676ede6fe7f2 (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
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
#ifndef _PPC_SEMAPHORE_H
#define _PPC_SEMAPHORE_H

/*
 * Swiped from asm-sparc/semaphore.h and modified
 * -- Cort (cort@cs.nmt.edu)
 *
 * Stole some rw spinlock-based semaphore stuff from asm-alpha/semaphore.h
 * -- Ani Joshi (ajoshi@unixbox.com)
 */

#ifdef __KERNEL__

#include <asm/atomic.h>
#include <asm/system.h>
#include <linux/wait.h>

struct semaphore {
	atomic_t count;
	atomic_t waking;
	wait_queue_head_t wait;
#if WAITQUEUE_DEBUG
	long __magic;
#endif
};

#if WAITQUEUE_DEBUG
# define __SEM_DEBUG_INIT(name) \
		, (long)&(name).__magic
#else
# define __SEM_DEBUG_INIT(name)
#endif

#define __SEMAPHORE_INITIALIZER(name,count) \
{ ATOMIC_INIT(count), ATOMIC_INIT(0), __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
	__SEM_DEBUG_INIT(name) }

#define __MUTEX_INITIALIZER(name) \
	__SEMAPHORE_INITIALIZER(name,1)

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

#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)

extern inline void sema_init (struct semaphore *sem, int val)
{
	atomic_set(&sem->count, val);
	atomic_set(&sem->waking, 0);
	init_waitqueue_head(&sem->wait);
#if WAITQUEUE_DEBUG
	sem->__magic = (long)&sem->__magic;
#endif
}

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);
extern int  __down_interruptible(struct semaphore * sem);
extern int  __down_trylock(struct semaphore * sem);
extern void __up(struct semaphore * sem);

extern inline void down(struct semaphore * sem)
{
	if (atomic_dec_return(&sem->count) >= 0)
		wmb();
	else
		__down(sem);
}

extern inline int down_interruptible(struct semaphore * sem)
{
	int ret = 0;

	if (atomic_dec_return(&sem->count) >= 0)
		wmb();
	else
		ret = __down_interruptible(sem);
	return ret;
}

extern inline int down_trylock(struct semaphore * sem)
{
	int ret = 0;

	if (atomic_dec_return(&sem->count) >= 0)
		wmb();
	else
		ret = __down_trylock(sem);
	return ret;
}

extern inline void up(struct semaphore * sem)
{
	mb();
	if (atomic_inc_return(&sem->count) <= 0)
		__up(sem);
}	


/* RW spinlock-based semaphores */

struct rw_semaphore
{
	spinlock_t lock;
	int rd, wr;
	wait_queue_head_t wait;
#if WAITQUEUE_DEBUG
	long __magic;
#endif
};

#define __RWSEM_INITIALIZER(name, rd, wr)		\
{							\
	SPIN_LOCK_UNLOCKED,				\
	(rd), (wr),					\
	__WAIT_QUEUE_HEAD_INITIALIZER((name).wait)	\
	__SEM_DEBUG_INIT(name)				\
}

#define __DECLARE_RWSEM_GENERIC(name, rd, wr)		\
	struct rw_semaphore name = __RWSEM_INITIALIZER(name, rd, wr)

#define DECLARE_RWSEM(name) __DECLARE_RWSEM_GENERIC(name, 0, 0)
#define DECLARE_RWSEM_READ_LOCKED(name) __DECLARE_RWSEM_GENERIC(name, 1, 0)
#define DECLAER_RWSEM_WRITE_LOCKED(name) __DECLARE_RWSEM_GENERIC(name, 0, 1)

extern inline void init_rwsem(struct rw_semaphore *sem)
{
	spin_lock_init(&sem->lock);
	sem->rd = sem->wr = 0;
	init_waitqueue_head(&sem->wait);
#if WAITQUEUE_DEBUG
	sem->__magic = (long)&sem->__magic;
#endif
}

#ifndef CHECK_MAGIC
#define CHECK_MAGIC(x)
#endif

extern void down_read_failed(struct rw_semaphore *);
extern void down_write_failed(struct rw_semaphore *);

extern inline void down_read(struct rw_semaphore *sem)
{
	CHECK_MAGIC(sem->__magic);

	spin_lock_irq(&sem->lock);
	if (sem->wr)
		down_read_failed(sem);
	sem->rd++;
	spin_unlock_irq(&sem->lock);
}

extern inline void down_write(struct rw_semaphore *sem)
{
	CHECK_MAGIC(sem->__magic);

	spin_lock(&sem->lock);
	if(sem->rd || sem->wr)
		down_write_failed(sem);
	sem->wr = 1;
	spin_unlock(&sem->lock);
}

#define up_read(sem)							\
	do {								\
		unsigned long flags;					\
									\
		CHECK_MAGIC((sem)->__magic);				\
									\
		spin_lock_irqsave(&(sem)->lock, flags);			\
		if (!--(sem)->rd && waitqueue_active(&(sem)->wait))	\
			wake_up(&(sem)->wait);				\
		spin_unlock_irqrestore(&(sem)->lock, flags);		\
	} while (0)

#define up_write(sem)							\
	do {								\
		unsigned long flags;					\
									\
		CHECK_MAGIC((sem)->__magic);				\
									\
		spin_lock_irqsave(&(sem)->lock, flags);			\
		(sem)->wr = 0;						\
		if (waitqueue_active(&(sem)->wait))			\
			wake_up(&(sem)->wait);				\
		spin_unlock_irqrestore(&(sem)->lock, flags);		\
	} while (0)


#endif /* __KERNEL__ */

#endif /* !(_PPC_SEMAPHORE_H) */