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Diffstat (limited to 'include/asm-mn10300/semaphore.h')
| -rw-r--r-- | include/asm-mn10300/semaphore.h | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/include/asm-mn10300/semaphore.h b/include/asm-mn10300/semaphore.h new file mode 100644 index 000000000000..5a9e1ad0b253 --- /dev/null +++ b/include/asm-mn10300/semaphore.h @@ -0,0 +1,169 @@ +/* MN10300 Semaphores + * + * Copyright (C) 2007 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 Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ +#ifndef _ASM_SEMAPHORE_H +#define _ASM_SEMAPHORE_H + +#ifndef __ASSEMBLY__ + +#include <linux/linkage.h> +#include <linux/wait.h> +#include <linux/spinlock.h> +#include <linux/rwsem.h> + +#define SEMAPHORE_DEBUG 0 + +/* + * the semaphore definition + * - if count is >0 then there are tokens available on the semaphore for down + * to collect + * - if count 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 { + atomic_t count; /* it's not really atomic, it's + * just that certain modules + * expect to be able to access + * it directly */ + 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, init_count) \ +{ \ + .count = ATOMIC_INIT(init_count), \ + .wait_lock = __SPIN_LOCK_UNLOCKED((name).wait_lock), \ + .wait_list = 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; + int count; + +#if SEMAPHORE_DEBUG + CHECK_MAGIC(sem->__magic); +#endif + + spin_lock_irqsave(&sem->wait_lock, flags); + count = atomic_read(&sem->count); + if (likely(count > 0)) { + atomic_set(&sem->count, count - 1); + spin_unlock_irqrestore(&sem->wait_lock, flags); + } else { + __down(sem, flags); + } +} + +static inline int down_interruptible(struct semaphore *sem) +{ + unsigned long flags; + int count, ret = 0; + +#if SEMAPHORE_DEBUG + CHECK_MAGIC(sem->__magic); +#endif + + spin_lock_irqsave(&sem->wait_lock, flags); + count = atomic_read(&sem->count); + if (likely(count > 0)) { + atomic_set(&sem->count, count - 1); + 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 count, success = 0; + +#if SEMAPHORE_DEBUG + CHECK_MAGIC(sem->__magic); +#endif + + spin_lock_irqsave(&sem->wait_lock, flags); + count = atomic_read(&sem->count); + if (likely(count > 0)) { + atomic_set(&sem->count, count - 1); + 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 + atomic_set(&sem->count, atomic_read(&sem->count) + 1); + spin_unlock_irqrestore(&sem->wait_lock, flags); +} + +static inline int sem_getcount(struct semaphore *sem) +{ + return atomic_read(&sem->count); +} + +#endif /* __ASSEMBLY__ */ + +#endif |