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 #if WAITQUEUE_DEBUG
  24         long __magic;
  25 #endif
  26 };
  27
  28 #if WAITQUEUE_DEBUG
  29 # define __SEM_DEBUG_INIT(name) \
  30                 , (int)&(name).__magic
  31 #else
  32 # define __SEM_DEBUG_INIT(name)
  33 #endif
  34
  35 #define __SEMAPHORE_INITIALIZER(name,count)                     \
  36         { ATOMIC_INIT(count),                                   \
  37           0,                                                    \
  38           __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)            \
  39         __SEM_DEBUG_INIT(name) }
  40
  41 #define __MUTEX_INITIALIZER(name) \
  42         __SEMAPHORE_INITIALIZER(name, 1)
  43
  44 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  45         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  46
  47 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  48 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  49
  50 static inline void sema_init (struct semaphore *sem, int val)
  51 {
  52 /*
  53  *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  54  *
  55  * i'd rather use the more flexible initialization above, but sadly
  56  * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well.
  57  */
  58         atomic_set(&sem->count, val);
  59         init_waitqueue_head(&sem->wait);
  60 #if WAITQUEUE_DEBUG
  61         sem->__magic = (int)&sem->__magic;
  62 #endif
  63 }
  64
  65 static inline void init_MUTEX (struct semaphore *sem)
  66 {
  67         sema_init(sem, 1);
  68 }
  69
  70 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  71 {
  72         sema_init(sem, 0);
  73 }
  74
  75 asmlinkage void __down(struct semaphore * sem);
  76 asmlinkage int  __down_interruptible(struct semaphore * sem);
  77 asmlinkage int  __down_trylock(struct semaphore * sem);
  78 asmlinkage void __up(struct semaphore * sem);
  79
  80 extern spinlock_t semaphore_wake_lock;
  81
  82 static inline void down(struct semaphore * sem)
  83 {
  84 #if WAITQUEUE_DEBUG
  85         CHECK_MAGIC(sem->__magic);
  86 #endif
  87
  88         if (atomic_sub_return(1, &sem->count) < 0)
  89                 __down(sem);
  90 }
  91
  92 static inline int down_interruptible(struct semaphore * sem)
  93 {
  94         int ret = 0;
  95 #if WAITQUEUE_DEBUG
  96         CHECK_MAGIC(sem->__magic);
  97 #endif
  98
  99         if (atomic_sub_return(1, &sem->count) < 0)
 100                 ret = __down_interruptible(sem);
 101         return ret;
 102 }
 103
 104 static inline int down_trylock(struct semaphore * sem)
 105 {
 106         int ret = 0;
 107 #if WAITQUEUE_DEBUG
 108         CHECK_MAGIC(sem->__magic);
 109 #endif
 110
 111         if (atomic_sub_return(1, &sem->count) < 0)
 112                 ret = __down_trylock(sem);
 113         return ret;
 114 }
 115
 116 /*
 117  * Note! This is subtle. We jump to wake people up only if
 118  * the semaphore was negative (== somebody was waiting on it).
 119  */
 120 static inline void up(struct semaphore * sem)
 121 {
 122 #if WAITQUEUE_DEBUG
 123         CHECK_MAGIC(sem->__magic);
 124 #endif
 125         if (atomic_add_return(1, &sem->count) <= 0)
 126                 __up(sem);
 127 }
 128
 129 #endif /* _XTENSA_SEMAPHORE_H */