release/src-rt-6.x/linux/linux-2.6/include/asm-blackfin/semaphore.h

   1 #ifndef _BFIN_SEMAPHORE_H
   2 #define _BFIN_SEMAPHORE_H
   3
   4 #ifndef __ASSEMBLY__
   5
   6 #include <linux/linkage.h>
   7 #include <linux/wait.h>
   8 #include <linux/spinlock.h>
   9 #include <linux/rwsem.h>
  10 #include <asm/atomic.h>
  11
  12 /*
  13  * Interrupt-safe semaphores..
  14  *
  15  * (C) Copyright 1996 Linus Torvalds
  16  *
  17  * BFIN version by akbar hussain Lineo Inc  April 2001
  18  *
  19  */
  20
  21 struct semaphore {
  22         atomic_t count;
  23         int sleepers;
  24         wait_queue_head_t wait;
  25 };
  26
  27 #define __SEMAPHORE_INITIALIZER(name, n)                                \
  28 {                                                                       \
  29         .count          = ATOMIC_INIT(n),                               \
  30         .sleepers       = 0,                                            \
  31         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  32 }
  33
  34 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  35         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  36
  37 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  38 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  39
  40 static inline void sema_init(struct semaphore *sem, int val)
  41 {
  42         *sem = (struct semaphore)__SEMAPHORE_INITIALIZER(*sem, val);
  43 }
  44
  45 static inline void init_MUTEX(struct semaphore *sem)
  46 {
  47         sema_init(sem, 1);
  48 }
  49
  50 static inline void init_MUTEX_LOCKED(struct semaphore *sem)
  51 {
  52         sema_init(sem, 0);
  53 }
  54
  55 asmlinkage void __down(struct semaphore *sem);
  56 asmlinkage int __down_interruptible(struct semaphore *sem);
  57 asmlinkage int __down_trylock(struct semaphore *sem);
  58 asmlinkage void __up(struct semaphore *sem);
  59
  60 extern spinlock_t semaphore_wake_lock;
  61
  62 /*
  63  * This is ugly, but we want the default case to fall through.
  64  * "down_failed" is a special asm handler that calls the C
  65  * routine that actually waits.
  66  */
  67 static inline void down(struct semaphore *sem)
  68 {
  69         might_sleep();
  70         if (atomic_dec_return(&sem->count) < 0)
  71                 __down(sem);
  72 }
  73
  74 static inline int down_interruptible(struct semaphore *sem)
  75 {
  76         int ret = 0;
  77
  78         might_sleep();
  79         if (atomic_dec_return(&sem->count) < 0)
  80                 ret = __down_interruptible(sem);
  81         return (ret);
  82 }
  83
  84 static inline int down_trylock(struct semaphore *sem)
  85 {
  86         int ret = 0;
  87
  88         if (atomic_dec_return(&sem->count) < 0)
  89                 ret = __down_trylock(sem);
  90         return ret;
  91 }
  92
  93 /*
  94  * Note! This is subtle. We jump to wake people up only if
  95  * the semaphore was negative (== somebody was waiting on it).
  96  * The default case (no contention) will result in NO
  97  * jumps for both down() and up().
  98  */
  99 static inline void up(struct semaphore *sem)
 100 {
 101         if (atomic_inc_return(&sem->count) <= 0)
 102                 __up(sem);
 103 }
 104
 105 #endif                          /* __ASSEMBLY__ */
 106 #endif                          /* _BFIN_SEMAPHORE_H */