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/* 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
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