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
  39 static inline void sema_init(struct semaphore *sem, int val)
  40 {
  41         *sem = (struct semaphore)__SEMAPHORE_INITIALIZER(*sem, val);
  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 /*
  62  * This is ugly, but we want the default case to fall through.
  63  * "down_failed" is a special asm handler that calls the C
  64  * routine that actually waits.
  65  */
  66 static inline void down(struct semaphore *sem)
  67 {
  68         might_sleep();
  69         if (atomic_dec_return(&sem->count) < 0)
  70                 __down(sem);
  71 }
  72
  73 static inline int down_interruptible(struct semaphore *sem)
  74 {
  75         int ret = 0;
  76
  77         might_sleep();
  78         if (atomic_dec_return(&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_dec_return(&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  * The default case (no contention) will result in NO
  96  * jumps for both down() and up().
  97  */
  98 static inline void up(struct semaphore *sem)
  99 {
 100         if (atomic_inc_return(&sem->count) <= 0)
 101                 __up(sem);
 102 }
 103
 104 #endif                          /* __ASSEMBLY__ */
 105 #endif                          /* _BFIN_SEMAPHORE_H */