include/asm-frv/semaphore.h

   1 /* semaphore.h: semaphores for the FR-V
   2  *
   3  * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11 #ifndef _ASM_SEMAPHORE_H
  12 #define _ASM_SEMAPHORE_H
  13
  14 #define RW_LOCK_BIAS             0x01000000
  15
  16 #ifndef __ASSEMBLY__
  17
  18 #include <linux/linkage.h>
  19 #include <linux/wait.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/rwsem.h>
  22
  23 #define SEMAPHORE_DEBUG         0
  24
  25 /*
  26  * the semaphore definition
  27  * - if counter is >0 then there are tokens available on the semaphore for down to collect
  28  * - if counter is <=0 then there are no spare tokens, and anyone that wants one must wait
  29  * - if wait_list is not empty, then there are processes waiting for the semaphore
  30  */
  31 struct semaphore {
  32         unsigned                counter;
  33         spinlock_t              wait_lock;
  34         struct list_head        wait_list;
  35 #if SEMAPHORE_DEBUG
  36         unsigned                __magic;
  37 #endif
  38 };
  39
  40 #if SEMAPHORE_DEBUG
  41 # define __SEM_DEBUG_INIT(name) , (long)&(name).__magic
  42 #else
  43 # define __SEM_DEBUG_INIT(name)
  44 #endif
  45
  46
  47 #define __SEMAPHORE_INITIALIZER(name,count) \
  48 { count, SPIN_LOCK_UNLOCKED, LIST_HEAD_INIT((name).wait_list) __SEM_DEBUG_INIT(name) }
  49
  50 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  51         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  52
  53 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  54 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  55
  56 static inline void sema_init (struct semaphore *sem, int val)
  57 {
  58         *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
  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 extern void __down(struct semaphore *sem, unsigned long flags);
  72 extern int  __down_interruptible(struct semaphore *sem, unsigned long flags);
  73 extern void __up(struct semaphore *sem);
  74
  75 static inline void down(struct semaphore *sem)
  76 {
  77         unsigned long flags;
  78
  79 #if SEMAPHORE_DEBUG
  80         CHECK_MAGIC(sem->__magic);
  81 #endif
  82
  83         spin_lock_irqsave(&sem->wait_lock, flags);
  84         if (likely(sem->counter > 0)) {
  85                 sem->counter--;
  86                 spin_unlock_irqrestore(&sem->wait_lock, flags);
  87         }
  88         else {
  89                 __down(sem, flags);
  90         }
  91 }
  92
  93 static inline int down_interruptible(struct semaphore *sem)
  94 {
  95         unsigned long flags;
  96         int ret = 0;
  97
  98 #if SEMAPHORE_DEBUG
  99         CHECK_MAGIC(sem->__magic);
 100 #endif
 101
 102         spin_lock_irqsave(&sem->wait_lock, flags);
 103         if (likely(sem->counter > 0)) {
 104                 sem->counter--;
 105                 spin_unlock_irqrestore(&sem->wait_lock, flags);
 106         }
 107         else {
 108                 ret = __down_interruptible(sem, flags);
 109         }
 110         return ret;
 111 }
 112
 113 /*
 114  * non-blockingly attempt to down() a semaphore.
 115  * - returns zero if we acquired it
 116  */
 117 static inline int down_trylock(struct semaphore *sem)
 118 {
 119         unsigned long flags;
 120         int success = 0;
 121
 122 #if SEMAPHORE_DEBUG
 123         CHECK_MAGIC(sem->__magic);
 124 #endif
 125
 126         spin_lock_irqsave(&sem->wait_lock, flags);
 127         if (sem->counter > 0) {
 128                 sem->counter--;
 129                 success = 1;
 130         }
 131         spin_unlock_irqrestore(&sem->wait_lock, flags);
 132         return !success;
 133 }
 134
 135 static inline void up(struct semaphore *sem)
 136 {
 137         unsigned long flags;
 138
 139 #if SEMAPHORE_DEBUG
 140         CHECK_MAGIC(sem->__magic);
 141 #endif
 142
 143         spin_lock_irqsave(&sem->wait_lock, flags);
 144         if (!list_empty(&sem->wait_list))
 145                 __up(sem);
 146         else
 147                 sem->counter++;
 148         spin_unlock_irqrestore(&sem->wait_lock, flags);
 149 }
 150
 151 static inline int sem_getcount(struct semaphore *sem)
 152 {
 153         return sem->counter;
 154 }
 155
 156 #endif /* __ASSEMBLY__ */
 157
 158 #endif