include/asm-sh64/semaphore.h

   1 #ifndef __ASM_SH64_SEMAPHORE_H
   2 #define __ASM_SH64_SEMAPHORE_H
   3
   4 /*
   5  * This file is subject to the terms and conditions of the GNU General Public
   6  * License.  See the file "COPYING" in the main directory of this archive
   7  * for more details.
   8  *
   9  * include/asm-sh64/semaphore.h
  10  *
  11  * Copyright (C) 2000, 2001  Paolo Alberelli
  12  *
  13  * SMP- and interrupt-safe semaphores.
  14  *
  15  * (C) Copyright 1996 Linus Torvalds
  16  *
  17  * SuperH verison by Niibe Yutaka
  18  *  (Currently no asm implementation but generic C code...)
  19  *
  20  */
  21
  22 #include <linux/linkage.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/wait.h>
  25 #include <linux/rwsem.h>
  26
  27 #include <asm/system.h>
  28 #include <asm/atomic.h>
  29
  30 struct semaphore {
  31         atomic_t count;
  32         int sleepers;
  33         wait_queue_head_t wait;
  34 };
  35
  36 #define __SEMAPHORE_INITIALIZER(name, n)                                \
  37 {                                                                       \
  38         .count          = ATOMIC_INIT(n),                               \
  39         .sleepers       = 0,                                            \
  40         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  41 }
  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 static 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->sleepers = 0;
  59         init_waitqueue_head(&sem->wait);
  60 }
  61
  62 static inline void init_MUTEX (struct semaphore *sem)
  63 {
  64         sema_init(sem, 1);
  65 }
  66
  67 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  68 {
  69         sema_init(sem, 0);
  70 }
  71
  72 #if 0
  73 asmlinkage void __down_failed(void /* special register calling convention */);
  74 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  75 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  76 asmlinkage void __up_wakeup(void /* special register calling convention */);
  77 #endif
  78
  79 asmlinkage void __down(struct semaphore * sem);
  80 asmlinkage int  __down_interruptible(struct semaphore * sem);
  81 asmlinkage int  __down_trylock(struct semaphore * sem);
  82 asmlinkage void __up(struct semaphore * sem);
  83
  84 extern spinlock_t semaphore_wake_lock;
  85
  86 static inline void down(struct semaphore * sem)
  87 {
  88         if (atomic_dec_return(&sem->count) < 0)
  89                 __down(sem);
  90 }
  91
  92 static inline int down_interruptible(struct semaphore * sem)
  93 {
  94         int ret = 0;
  95
  96         if (atomic_dec_return(&sem->count) < 0)
  97                 ret = __down_interruptible(sem);
  98         return ret;
  99 }
 100
 101 static inline int down_trylock(struct semaphore * sem)
 102 {
 103         int ret = 0;
 104
 105         if (atomic_dec_return(&sem->count) < 0)
 106                 ret = __down_trylock(sem);
 107         return ret;
 108 }
 109
 110 /*
 111  * Note! This is subtle. We jump to wake people up only if
 112  * the semaphore was negative (== somebody was waiting on it).
 113  */
 114 static inline void up(struct semaphore * sem)
 115 {
 116         if (atomic_inc_return(&sem->count) <= 0)
 117                 __up(sem);
 118 }
 119
 120 #endif /* __ASM_SH64_SEMAPHORE_H */