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 #ifdef __KERNEL__
   7 /*
   8  * SMP- and interrupt-safe semaphores.
   9  *
  10  * (C) Copyright 1996 Linus Torvalds
  11  *
  12  * SuperH verison by Niibe Yutaka
  13  *  (Currently no asm implementation but generic C code...)
  14  */
  15
  16 #include <linux/spinlock.h>
  17 #include <linux/rwsem.h>
  18 #include <linux/wait.h>
  19
  20 #include <asm/system.h>
  21 #include <asm/atomic.h>
  22
  23 struct semaphore {
  24         atomic_t count;
  25         int sleepers;
  26         wait_queue_head_t wait;
  27 };
  28
  29 #define __SEMAPHORE_INITIALIZER(name, n)                                \
  30 {                                                                       \
  31         .count          = ATOMIC_INIT(n),                               \
  32         .sleepers       = 0,                                            \
  33         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  34 }
  35
  36 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  37         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  38
  39 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  40 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  41
  42 static inline void sema_init (struct semaphore *sem, int val)
  43 {
  44 /*
  45  *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  46  *
  47  * i'd rather use the more flexible initialization above, but sadly
  48  * GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
  49  */
  50         atomic_set(&sem->count, val);
  51         sem->sleepers = 0;
  52         init_waitqueue_head(&sem->wait);
  53 }
  54
  55 static inline void init_MUTEX (struct semaphore *sem)
  56 {
  57         sema_init(sem, 1);
  58 }
  59
  60 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  61 {
  62         sema_init(sem, 0);
  63 }
  64
  65 #if 0
  66 asmlinkage void __down_failed(void /* special register calling convention */);
  67 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  68 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  69 asmlinkage void __up_wakeup(void /* special register calling convention */);
  70 #endif
  71
  72 asmlinkage void __down(struct semaphore * sem);
  73 asmlinkage int  __down_interruptible(struct semaphore * sem);
  74 asmlinkage int  __down_trylock(struct semaphore * sem);
  75 asmlinkage void __up(struct semaphore * sem);
  76
  77 extern spinlock_t semaphore_wake_lock;
  78
  79 static inline void down(struct semaphore * sem)
  80 {
  81         might_sleep();
  82         if (atomic_dec_return(&sem->count) < 0)
  83                 __down(sem);
  84 }
  85
  86 static inline int down_interruptible(struct semaphore * sem)
  87 {
  88         int ret = 0;
  89
  90         might_sleep();
  91         if (atomic_dec_return(&sem->count) < 0)
  92                 ret = __down_interruptible(sem);
  93         return ret;
  94 }
  95
  96 static inline int down_trylock(struct semaphore * sem)
  97 {
  98         int ret = 0;
  99
 100         if (atomic_dec_return(&sem->count) < 0)
 101                 ret = __down_trylock(sem);
 102         return ret;
 103 }
 104
 105 /*
 106  * Note! This is subtle. We jump to wake people up only if
 107  * the semaphore was negative (== somebody was waiting on it).
 108  */
 109 static inline void up(struct semaphore * sem)
 110 {
 111         if (atomic_inc_return(&sem->count) <= 0)
 112                 __up(sem);
 113 }
 114
 115 #endif
 116 #endif /* __ASM_SH_SEMAPHORE_H */