include/asm-sh/semaphore.h

   1 #ifndef __ASM_SH_SEMAPHORE_H
   2 #define __ASM_SH_SEMAPHORE_H
   3
   4 #include <linux/linkage.h>
   5
   6 /*
   7  * SMP- and interrupt-safe semaphores.
   8  *
   9  * (C) Copyright 1996 Linus Torvalds
  10  *
  11  * SuperH verison by Niibe Yutaka
  12  *
  13  */
  14
  15 #include <linux/spinlock.h>
  16
  17 #include <asm/system.h>
  18 #include <asm/atomic.h>
  19
  20 struct semaphore {
  21         atomic_t count;
  22         int waking;
  23         wait_queue_head_t wait;
  24 #if WAITQUEUE_DEBUG
  25         long __magic;
  26 #endif
  27 };
  28
  29 #if WAITQUEUE_DEBUG
  30 # define __SEM_DEBUG_INIT(name) \
  31                 , (int)&(name).__magic
  32 #else
  33 # define __SEM_DEBUG_INIT(name)
  34 #endif
  35
  36 #define __SEMAPHORE_INITIALIZER(name,count) \
  37 { ATOMIC_INIT(count), 0, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
  38         __SEM_DEBUG_INIT(name) }
  39
  40 #define __MUTEX_INITIALIZER(name) \
  41         __SEMAPHORE_INITIALIZER(name,1)
  42
  43 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  44         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  45
  46 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  47 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  48
  49 extern inline void sema_init (struct semaphore *sem, int val)
  50 {
  51 /*
  52  *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  53  *
  54  * i'd rather use the more flexible initialization above, but sadly
  55  * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well.
  56  */
  57         atomic_set(&sem->count, val);
  58         sem->waking = 0;
  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_failed(void /* special register calling convention */);
  76 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  77 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  78 asmlinkage void __up_wakeup(void /* special register calling convention */);
  79
  80 asmlinkage void __down(struct semaphore * sem);
  81 asmlinkage int  __down_interruptible(struct semaphore * sem);
  82 asmlinkage int  __down_trylock(struct semaphore * sem);
  83 asmlinkage void __up(struct semaphore * sem);
  84
  85 extern spinlock_t semaphore_wake_lock;
  86
  87 extern __inline__ void down(struct semaphore * sem)
  88 {
  89 #if WAITQUEUE_DEBUG
  90         CHECK_MAGIC(sem->__magic);
  91 #endif
  92
  93         if (atomic_dec_return(&sem->count) < 0)
  94                 __down(sem);
  95 }
  96
  97 extern __inline__ int down_interruptible(struct semaphore * sem)
  98 {
  99         int ret = 0;
 100 #if WAITQUEUE_DEBUG
 101         CHECK_MAGIC(sem->__magic);
 102 #endif
 103
 104         if (atomic_dec_return(&sem->count) < 0)
 105                 ret = __down_interruptible(sem);
 106         return ret;
 107 }
 108
 109 extern __inline__ int down_trylock(struct semaphore * sem)
 110 {
 111         int ret = 0;
 112 #if WAITQUEUE_DEBUG
 113         CHECK_MAGIC(sem->__magic);
 114 #endif
 115
 116         if (atomic_dec_return(&sem->count) < 0)
 117                 ret = __down_trylock(sem);
 118         return ret;
 119 }
 120
 121 /*
 122  * Note! This is subtle. We jump to wake people up only if
 123  * the semaphore was negative (== somebody was waiting on it).
 124  */
 125 extern __inline__ void up(struct semaphore * sem)
 126 {
 127 #if WAITQUEUE_DEBUG
 128         CHECK_MAGIC(sem->__magic);
 129 #endif
 130         if (atomic_inc_return(&sem->count) <= 0)
 131                 __up(sem);
 132 }
 133
 134 #endif /* __ASM_SH_SEMAPHORE_H */