aboutsummaryrefslogtreecommitdiffstats
path: root/include/asm-m32r/semaphore.h
blob: 81750edc8916267e035dcf47484afe001910c74a (plain) (blame)
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
#ifndef _ASM_M32R_SEMAPHORE_H
#define _ASM_M32R_SEMAPHORE_H

#include <linux/linkage.h>

#ifdef __KERNEL__

/*
 * SMP- and interrupt-safe semaphores..
 *
 * Copyright (C) 1996  Linus Torvalds
 * Copyright (C) 2004, 2006  Hirokazu Takata <takata at linux-m32r.org>
 */

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

struct semaphore {
	atomic_t count;
	int sleepers;
	wait_queue_head_t wait;
};

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

#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)

static inline void sema_init (struct semaphore *sem, int val)
{
/*
 *	*sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
 *
 * i'd rather use the more flexible initialization above, but sadly
 * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well.
 */
	atomic_set(&sem->count, val);
	sem->sleepers = 0;
	init_waitqueue_head(&sem->wait);
}

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);
}

asmlinkage void __down_failed(void /* special register calling convention */);
asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
asmlinkage int  __down_failed_trylock(void  /* params in registers */);
asmlinkage void __up_wakeup(void /* special register calling convention */);

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

/*
 * Atomically decrement the semaphore's count.  If it goes negative,
 * block the calling thread in the TASK_UNINTERRUPTIBLE state.
 */
static inline void down(struct semaphore * sem)
{
	might_sleep();
	if (unlikely(atomic_dec_return(&sem->count) < 0))
		__down(sem);
}

/*
 * Interruptible try to acquire a semaphore.  If we obtained
 * it, return zero.  If we were interrupted, returns -EINTR
 */
static inline int down_interruptible(struct semaphore * sem)
{
	int result = 0;

	might_sleep();
	if (unlikely(atomic_dec_return(&sem->count) < 0))
		result = __down_interruptible(sem);

	return result;
}

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

	local_irq_save(flags);
	__asm__ __volatile__ (
		"# down_trylock			\n\t"
		DCACHE_CLEAR("%0", "r4", "%1")
		M32R_LOCK" %0, @%1;		\n\t"
		"addi	%0, #-1;		\n\t"
		M32R_UNLOCK" %0, @%1;		\n\t"
		: "=&r" (count)
		: "r" (&sem->count)
		: "memory"
#ifdef CONFIG_CHIP_M32700_TS1
		, "r4"
#endif	/* CONFIG_CHIP_M32700_TS1 */
	);
	local_irq_restore(flags);

	if (unlikely(count < 0))
		result = __down_trylock(sem);

	return result;
}

/*
 * Note! This is subtle. We jump to wake people up only if
 * the semaphore was negative (== somebody was waiting on it).
 * The default case (no contention) will result in NO
 * jumps for both down() and up().
 */
static inline void up(struct semaphore * sem)
{
	if (unlikely(atomic_inc_return(&sem->count) <= 0))
		__up(sem);
}

#endif  /* __KERNEL__ */

#endif  /* _ASM_M32R_SEMAPHORE_H */