/* 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> #define SEMAPHORE_DEBUG WAITQUEUE_DEBUG /* * 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; #if SEMAPHORE_DEBUG unsigned __magic; #endif }; #if SEMAPHORE_DEBUG # 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) #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); } 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; #if SEMAPHORE_DEBUG 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; #if SEMAPHORE_DEBUG 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; #if SEMAPHORE_DEBUG 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; #if SEMAPHORE_DEBUG 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