156 lines
3.5 KiB
C
156 lines
3.5 KiB
C
/* semaphore.h: semaphores for the FR-V
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*
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* Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_SEMAPHORE_H
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#define _ASM_SEMAPHORE_H
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#define RW_LOCK_BIAS 0x01000000
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#ifndef __ASSEMBLY__
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#include <linux/linkage.h>
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#include <linux/wait.h>
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#include <linux/spinlock.h>
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#include <linux/rwsem.h>
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/*
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* the semaphore definition
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* - if counter is >0 then there are tokens available on the semaphore for down to collect
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* - if counter is <=0 then there are no spare tokens, and anyone that wants one must wait
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* - if wait_list is not empty, then there are processes waiting for the semaphore
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*/
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struct semaphore {
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unsigned counter;
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spinlock_t wait_lock;
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struct list_head wait_list;
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#ifdef CONFIG_DEBUG_SEMAPHORE
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unsigned __magic;
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#endif
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};
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#ifdef CONFIG_DEBUG_SEMAPHORE
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# define __SEM_DEBUG_INIT(name) , (long)&(name).__magic
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#else
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# define __SEM_DEBUG_INIT(name)
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#endif
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#define __SEMAPHORE_INITIALIZER(name,count) \
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{ count, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __SEM_DEBUG_INIT(name) }
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#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
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struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
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#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
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static inline void sema_init (struct semaphore *sem, int val)
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{
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*sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
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}
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static inline void init_MUTEX (struct semaphore *sem)
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{
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sema_init(sem, 1);
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}
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static inline void init_MUTEX_LOCKED (struct semaphore *sem)
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{
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sema_init(sem, 0);
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}
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extern void __down(struct semaphore *sem, unsigned long flags);
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extern int __down_interruptible(struct semaphore *sem, unsigned long flags);
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extern void __up(struct semaphore *sem);
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static inline void down(struct semaphore *sem)
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{
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unsigned long flags;
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#ifdef CONFIG_DEBUG_SEMAPHORE
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CHECK_MAGIC(sem->__magic);
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#endif
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spin_lock_irqsave(&sem->wait_lock, flags);
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if (likely(sem->counter > 0)) {
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sem->counter--;
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spin_unlock_irqrestore(&sem->wait_lock, flags);
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}
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else {
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__down(sem, flags);
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}
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}
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static inline int down_interruptible(struct semaphore *sem)
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{
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unsigned long flags;
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int ret = 0;
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#ifdef CONFIG_DEBUG_SEMAPHORE
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CHECK_MAGIC(sem->__magic);
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#endif
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spin_lock_irqsave(&sem->wait_lock, flags);
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if (likely(sem->counter > 0)) {
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sem->counter--;
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spin_unlock_irqrestore(&sem->wait_lock, flags);
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}
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else {
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ret = __down_interruptible(sem, flags);
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}
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return ret;
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}
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/*
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* non-blockingly attempt to down() a semaphore.
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* - returns zero if we acquired it
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*/
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static inline int down_trylock(struct semaphore *sem)
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{
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unsigned long flags;
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int success = 0;
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#ifdef CONFIG_DEBUG_SEMAPHORE
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CHECK_MAGIC(sem->__magic);
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#endif
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spin_lock_irqsave(&sem->wait_lock, flags);
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if (sem->counter > 0) {
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sem->counter--;
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success = 1;
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}
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spin_unlock_irqrestore(&sem->wait_lock, flags);
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return !success;
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}
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static inline void up(struct semaphore *sem)
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{
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unsigned long flags;
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#ifdef CONFIG_DEBUG_SEMAPHORE
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CHECK_MAGIC(sem->__magic);
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#endif
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spin_lock_irqsave(&sem->wait_lock, flags);
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if (!list_empty(&sem->wait_list))
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__up(sem);
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else
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sem->counter++;
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spin_unlock_irqrestore(&sem->wait_lock, flags);
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}
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static inline int sem_getcount(struct semaphore *sem)
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{
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return sem->counter;
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}
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#endif /* __ASSEMBLY__ */
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#endif
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