Subversion Repositories or1k

#ifndef _ASM_PARISC_SEMAPHORE_H

#define _ASM_PARISC_SEMAPHORE_H

/*

 * SMP- and interrupt-safe semaphores.

 *

 * (C) Copyright 1996 Linus Torvalds

 *

 * PA-RISC version by Matthew Wilcox

 *

 */

#include <linux/spinlock.h>

#include <linux/wait.h>

#include <linux/rwsem.h>

#include <asm/system.h>

/*

 * The `count' is initialised to the number of people who are allowed to

 * take the lock.  (Normally we want a mutex, so this is `1').  if

 * `count' is positive, the lock can be taken.  if it's 0, no-one is

 * waiting on it.  if it's -1, at least one task is waiting.

 */

struct semaphore {

        spinlock_t      sentry;

        int             count;

        wait_queue_head_t wait;

#if WAITQUEUE_DEBUG

        long __magic;

#endif

};

#if WAITQUEUE_DEBUG

# define __SEM_DEBUG_INIT(name) \

                , (long)&(name).__magic

#else

# define __SEM_DEBUG_INIT(name)

#endif

#define __SEMAPHORE_INITIALIZER(name,count) \

{ SPIN_LOCK_UNLOCKED, count, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \

        __SEM_DEBUG_INIT(name) }

#define __MUTEX_INITIALIZER(name) \

        __SEMAPHORE_INITIALIZER(name,1)

#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)

extern 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);

}

static inline int sem_getcount(struct semaphore *sem)

{

        return sem->count;

}

asmlinkage void __down(struct semaphore * sem);

asmlinkage int  __down_interruptible(struct semaphore * sem);

asmlinkage void __up(struct semaphore * sem);

/* Semaphores can be `tried' from irq context.  So we have to disable

 * interrupts while we're messing with the semaphore.  Sorry.

 */

extern __inline__ void down(struct semaphore * sem)

{

#if WAITQUEUE_DEBUG

        CHECK_MAGIC(sem->__magic);

#endif

        spin_lock_irq(&sem->sentry);

        if (sem->count > 0) {

                sem->count--;

        } else {

                __down(sem);

        }

        spin_unlock_irq(&sem->sentry);

}

extern __inline__ int down_interruptible(struct semaphore * sem)

{

        int ret = 0;

#if WAITQUEUE_DEBUG

        CHECK_MAGIC(sem->__magic);

#endif

        spin_lock_irq(&sem->sentry);

        if (sem->count > 0) {

                sem->count--;

        } else {

                ret = __down_interruptible(sem);

        }

        spin_unlock_irq(&sem->sentry);

        return ret;

}

/*

 * down_trylock returns 0 on success, 1 if we failed to get the lock.

 * May not sleep, but must preserve irq state

 */

extern __inline__ int down_trylock(struct semaphore * sem)

{

        int flags, count;

#if WAITQUEUE_DEBUG

        CHECK_MAGIC(sem->__magic);

#endif

        spin_lock_irqsave(&sem->sentry, flags);

        count = sem->count - 1;

        if (count >= 0)

                sem->count = count;

        spin_unlock_irqrestore(&sem->sentry, flags);

        return (count < 0);

}

/*

 * Note! This is subtle. We jump to wake people up only if

 * the semaphore was negative (== somebody was waiting on it).

 */

extern __inline__ void up(struct semaphore * sem)

{

        int flags;

#if WAITQUEUE_DEBUG

        CHECK_MAGIC(sem->__magic);

#endif

        spin_lock_irqsave(&sem->sentry, flags);

        if (sem->count < 0) {

                __up(sem);

        } else {

                sem->count++;

        }

        spin_unlock_irqrestore(&sem->sentry, flags);

}

#endif /* _ASM_PARISC_SEMAPHORE_H */