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
  48 static inline void sema_init (struct semaphore *sem, int val)
  49 {
  50 /*
  51  *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  52  *
  53  * i'd rather use the more flexible initialization above, but sadly
  54  * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well.
  55  */
  56         atomic_set(&sem->count, val);
  57         sem->sleepers = 0;
  58         init_waitqueue_head(&sem->wait);
  59 }
  60
  61 static inline void init_MUTEX (struct semaphore *sem)
  62 {
  63         sema_init(sem, 1);
  64 }
  65
  66 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  67 {
  68         sema_init(sem, 0);
  69 }
  70
  71 #if 0
  72 asmlinkage void __down_failed(void /* special register calling convention */);
  73 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  74 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  75 asmlinkage void __up_wakeup(void /* special register calling convention */);
  76 #endif
  77
  78 asmlinkage void __down(struct semaphore * sem);
  79 asmlinkage int  __down_interruptible(struct semaphore * sem);
  80 asmlinkage int  __down_trylock(struct semaphore * sem);
  81 asmlinkage void __up(struct semaphore * sem);
  82
  83 extern spinlock_t semaphore_wake_lock;
  84
  85 static inline void down(struct semaphore * sem)
  86 {
  87         if (atomic_dec_return(&sem->count) < 0)
  88                 __down(sem);
  89 }
  90
  91 static inline int down_interruptible(struct semaphore * sem)
  92 {
  93         int ret = 0;
  94
  95         if (atomic_dec_return(&sem->count) < 0)
  96                 ret = __down_interruptible(sem);
  97         return ret;
  98 }
  99
 100 static inline int down_trylock(struct semaphore * sem)
 101 {
 102         int ret = 0;
 103
 104         if (atomic_dec_return(&sem->count) < 0)
 105                 ret = __down_trylock(sem);
 106         return ret;
 107 }
 108
 109 /*
 110  * Note! This is subtle. We jump to wake people up only if
 111  * the semaphore was negative (== somebody was waiting on it).
 112  */
 113 static inline void up(struct semaphore * sem)
 114 {
 115         if (atomic_inc_return(&sem->count) <= 0)
 116                 __up(sem);
 117 }
 118
 119 #endif /* __ASM_SH64_SEMAPHORE_H */