[linux-2.6-block.git] / include / asm-avr32 / semaphore.h

/*
 * SMP- and interrupt-safe semaphores.
 *
 * Copyright (C) 2006 Atmel Corporation
 *
 * Based on include/asm-i386/semaphore.h
 *   Copyright (C) 1996 Linus Torvalds
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#ifndef __ASM_AVR32_SEMAPHORE_H
#define __ASM_AVR32_SEMAPHORE_H

#include <linux/linkage.h>

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

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

#define __SEMAPHORE_INITIALIZER(name, n)				\
{									\
	.count		= ATOMIC_INIT(n),				\
	.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)

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

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

/*
 * This is ugly, but we want the default case to fall through.
 * "__down_failed" is a special asm handler that calls the C
 * routine that actually waits. See arch/i386/kernel/semaphore.c
 */
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 ret = 0;

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

/*
 * Non-blockingly attempt to down() a semaphore.
 * Returns zero if we acquired it
 */
static inline int down_trylock(struct semaphore * sem)
{
	return atomic_dec_if_positive(&sem->count) < 0;
}

/*
 * 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 /*__ASM_AVR32_SEMAPHORE_H */
Commit	Line	Data
5f97f7f9 HS	1	/*
	2	* SMP- and interrupt-safe semaphores.
	3	*
	4	* Copyright (C) 2006 Atmel Corporation
	5	*
	6	* Based on include/asm-i386/semaphore.h
	7	* Copyright (C) 1996 Linus Torvalds
	8	*
	9	* This program is free software; you can redistribute it and/or modify
	10	* it under the terms of the GNU General Public License version 2 as
	11	* published by the Free Software Foundation.
	12	*/
	13	#ifndef __ASM_AVR32_SEMAPHORE_H
	14	#define __ASM_AVR32_SEMAPHORE_H
	15
	16	#include <linux/linkage.h>
	17
	18	#include <asm/system.h>
	19	#include <asm/atomic.h>
	20	#include <linux/wait.h>
	21	#include <linux/rwsem.h>
	22
	23	struct semaphore {
	24	atomic_t count;
	25	int sleepers;
	26	wait_queue_head_t wait;
	27	};
	28
	29	#define __SEMAPHORE_INITIALIZER(name, n) \
	30	{ \
	31	.count = ATOMIC_INIT(n), \
	32	.wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
	33	}
	34
	35	#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
	36	struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
	37
	38	#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
5f97f7f9 HS	39
	40	static inline void sema_init (struct semaphore *sem, int val)
	41	{
	42	atomic_set(&sem->count, val);
	43	sem->sleepers = 0;
	44	init_waitqueue_head(&sem->wait);
	45	}
	46
	47	static inline void init_MUTEX (struct semaphore *sem)
	48	{
	49	sema_init(sem, 1);
	50	}
	51
	52	static inline void init_MUTEX_LOCKED (struct semaphore *sem)
	53	{
	54	sema_init(sem, 0);
	55	}
	56
	57	void __down(struct semaphore * sem);
	58	int __down_interruptible(struct semaphore * sem);
	59	void __up(struct semaphore * sem);
	60
	61	/*
	62	* This is ugly, but we want the default case to fall through.
	63	* "__down_failed" is a special asm handler that calls the C
	64	* routine that actually waits. See arch/i386/kernel/semaphore.c
	65	*/
	66	static inline void down(struct semaphore * sem)
	67	{
	68	might_sleep();
	69	if (unlikely(atomic_dec_return (&sem->count) < 0))
	70	__down (sem);
	71	}
	72
	73	/*
	74	* Interruptible try to acquire a semaphore. If we obtained
	75	* it, return zero. If we were interrupted, returns -EINTR
	76	*/
	77	static inline int down_interruptible(struct semaphore * sem)
	78	{
	79	int ret = 0;
	80
	81	might_sleep();
	82	if (unlikely(atomic_dec_return (&sem->count) < 0))
	83	ret = __down_interruptible (sem);
	84	return ret;
	85	}
	86
	87	/*
	88	* Non-blockingly attempt to down() a semaphore.
	89	* Returns zero if we acquired it
	90	*/
	91	static inline int down_trylock(struct semaphore * sem)
	92	{
	93	return atomic_dec_if_positive(&sem->count) < 0;
	94	}
	95
	96	/*
	97	* Note! This is subtle. We jump to wake people up only if
	98	* the semaphore was negative (== somebody was waiting on it).
	99	* The default case (no contention) will result in NO
	100	* jumps for both down() and up().
	101	*/
	102	static inline void up(struct semaphore * sem)
103	{
104	if (unlikely(atomic_inc_return (&sem->count) <= 0))
105	__up (sem);
106	}
107
108	#endif /__ASM_AVR32_SEMAPHORE_H /