include/asm-xtensa/semaphore.h

   1 /*
   2  * linux/include/asm-xtensa/semaphore.h
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (C) 2001 - 2005 Tensilica Inc.
   9  */
  10
  11 #ifndef _XTENSA_SEMAPHORE_H
  12 #define _XTENSA_SEMAPHORE_H
  13
  14 #include <asm/atomic.h>
  15 #include <asm/system.h>
  16 #include <linux/wait.h>
  17 #include <linux/rwsem.h>
  18
  19 struct semaphore {
  20         atomic_t count;
  21         int sleepers;
  22         wait_queue_head_t wait;
  23 };
  24
  25 #define __SEMAPHORE_INITIALIZER(name,n)                                 \
  26 {                                                                       \
  27         .count          = ATOMIC_INIT(n),                               \
  28         .sleepers       = 0,                                            \
  29         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  30 }
  31
  32 #define __DECLARE_SEMAPHORE_GENERIC(name,count)                         \
  33         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  34
  35 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  36 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  37
  38 static inline void sema_init (struct semaphore *sem, int val)
  39 {
  40         atomic_set(&sem->count, val);
  41         init_waitqueue_head(&sem->wait);
  42 }
  43
  44 static inline void init_MUTEX (struct semaphore *sem)
  45 {
  46         sema_init(sem, 1);
  47 }
  48
  49 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  50 {
  51         sema_init(sem, 0);
  52 }
  53
  54 asmlinkage void __down(struct semaphore * sem);
  55 asmlinkage int  __down_interruptible(struct semaphore * sem);
  56 asmlinkage int  __down_trylock(struct semaphore * sem);
  57 asmlinkage void __up(struct semaphore * sem);
  58
  59 extern spinlock_t semaphore_wake_lock;
  60
  61 static inline void down(struct semaphore * sem)
  62 {
  63         might_sleep();
  64
  65         if (atomic_sub_return(1, &sem->count) < 0)
  66                 __down(sem);
  67 }
  68
  69 static inline int down_interruptible(struct semaphore * sem)
  70 {
  71         int ret = 0;
  72
  73         might_sleep();
  74
  75         if (atomic_sub_return(1, &sem->count) < 0)
  76                 ret = __down_interruptible(sem);
  77         return ret;
  78 }
  79
  80 static inline int down_trylock(struct semaphore * sem)
  81 {
  82         int ret = 0;
  83
  84         if (atomic_sub_return(1, &sem->count) < 0)
  85                 ret = __down_trylock(sem);
  86         return ret;
  87 }
  88
  89 /*
  90  * Note! This is subtle. We jump to wake people up only if
  91  * the semaphore was negative (== somebody was waiting on it).
  92  */
  93 static inline void up(struct semaphore * sem)
  94 {
  95         if (atomic_add_return(1, &sem->count) <= 0)
  96                 __up(sem);
  97 }
  98
  99 #endif /* _XTENSA_SEMAPHORE_H */