/*
   * linux/include/asm-xtensa/semaphore.h
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 2001 - 2005 Tensilica Inc.
   */
  
  #ifndef _XTENSA_SEMAPHORE_H
  #define _XTENSA_SEMAPHORE_H
  
  #include <asm/atomic.h>
  #include <asm/system.h>
  #include <linux/wait.h>
  #include <linux/rwsem.h>
  
  struct semaphore {
  	atomic_t count;
  	int sleepers;
  	wait_queue_head_t wait;

  };

  #define __SEMAPHORE_INITIALIZER(name,n)					\
  {									\
  	.count		= ATOMIC_INIT(n),				\
  	.sleepers	= 0,						\
  	.wait		= __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)	\
  }

  #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)

  {

  	atomic_set(&sem->count, val);

  	sem->sleepers = 0;

  	init_waitqueue_head(&sem->wait);

  }
  
  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);
  }
  
  asmlinkage void __down(struct semaphore * sem);
  asmlinkage int  __down_interruptible(struct semaphore * sem);
  asmlinkage int  __down_trylock(struct semaphore * sem);
  asmlinkage void __up(struct semaphore * sem);
  
  extern spinlock_t semaphore_wake_lock;

  static inline void down(struct semaphore * sem)

  {

  	might_sleep();

  
  	if (atomic_sub_return(1, &sem->count) < 0)
  		__down(sem);
  }

  static inline int down_interruptible(struct semaphore * sem)

  {
  	int ret = 0;

  
  	might_sleep();

  
  	if (atomic_sub_return(1, &sem->count) < 0)
  		ret = __down_interruptible(sem);
  	return ret;
  }

  static inline int down_trylock(struct semaphore * sem)

  {
  	int ret = 0;

  
  	if (atomic_sub_return(1, &sem->count) < 0)
  		ret = __down_trylock(sem);
  	return ret;
  }
  
  /*
   * Note! This is subtle. We jump to wake people up only if
   * the semaphore was negative (== somebody was waiting on it).
   */

  static inline void up(struct semaphore * sem)

  {

  	if (atomic_add_return(1, &sem->count) <= 0)
  		__up(sem);
  }
  
  #endif /* _XTENSA_SEMAPHORE_H */