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 __MUTEX_INITIALIZER(name)                                       \
  33         __SEMAPHORE_INITIALIZER(name, 1)
  34
  35 #define __DECLARE_SEMAPHORE_GENERIC(name,count)                         \
  36         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  37
  38 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  39 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  40
  41 static inline void sema_init (struct semaphore *sem, int val)
  42 {
  43         atomic_set(&sem->count, val);
  44         init_waitqueue_head(&sem->wait);
  45 }
  46
  47 static inline void init_MUTEX (struct semaphore *sem)
  48 {
  49         sema_init(sem, 1);
  50 }
  51
  52 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  53 {
  54         sema_init(sem, 0);
  55 }
  56
  57 asmlinkage void __down(struct semaphore * sem);
  58 asmlinkage int  __down_interruptible(struct semaphore * sem);
  59 asmlinkage int  __down_trylock(struct semaphore * sem);
  60 asmlinkage void __up(struct semaphore * sem);
  61
  62 extern spinlock_t semaphore_wake_lock;
  63
  64 static inline void down(struct semaphore * sem)
  65 {
  66         might_sleep();
  67
  68         if (atomic_sub_return(1, &sem->count) < 0)
  69                 __down(sem);
  70 }
  71
  72 static inline int down_interruptible(struct semaphore * sem)
  73 {
  74         int ret = 0;
  75
  76         might_sleep();
  77
  78         if (atomic_sub_return(1, &sem->count) < 0)
  79                 ret = __down_interruptible(sem);
  80         return ret;
  81 }
  82
  83 static inline int down_trylock(struct semaphore * sem)
  84 {
  85         int ret = 0;
  86
  87         if (atomic_sub_return(1, &sem->count) < 0)
  88                 ret = __down_trylock(sem);
  89         return ret;
  90 }
  91
  92 /*
  93  * Note! This is subtle. We jump to wake people up only if
  94  * the semaphore was negative (== somebody was waiting on it).
  95  */
  96 static inline void up(struct semaphore * sem)
  97 {
  98         if (atomic_add_return(1, &sem->count) <= 0)
  99                 __up(sem);
 100 }
 101
 102 #endif /* _XTENSA_SEMAPHORE_H */