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         WAITQUEUE_DEBUG
  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 __MUTEX_INITIALIZER(name) \
  51         __SEMAPHORE_INITIALIZER(name,1)
  52
  53 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  54         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  55
  56 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  57 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  58
  59 static inline void sema_init (struct semaphore *sem, int val)
  60 {
  61         *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
  62 }
  63
  64 static inline void init_MUTEX (struct semaphore *sem)
  65 {
  66         sema_init(sem, 1);
  67 }
  68
  69 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  70 {
  71         sema_init(sem, 0);
  72 }
  73
  74 extern void __down(struct semaphore *sem, unsigned long flags);
  75 extern int  __down_interruptible(struct semaphore *sem, unsigned long flags);
  76 extern void __up(struct semaphore *sem);
  77
  78 static inline void down(struct semaphore *sem)
  79 {
  80         unsigned long flags;
  81
  82 #if SEMAPHORE_DEBUG
  83         CHECK_MAGIC(sem->__magic);
  84 #endif
  85
  86         spin_lock_irqsave(&sem->wait_lock, flags);
  87         if (likely(sem->counter > 0)) {
  88                 sem->counter--;
  89                 spin_unlock_irqrestore(&sem->wait_lock, flags);
  90         }
  91         else {
  92                 __down(sem, flags);
  93         }
  94 }
  95
  96 static inline int down_interruptible(struct semaphore *sem)
  97 {
  98         unsigned long flags;
  99         int ret = 0;
 100
 101 #if SEMAPHORE_DEBUG
 102         CHECK_MAGIC(sem->__magic);
 103 #endif
 104
 105         spin_lock_irqsave(&sem->wait_lock, flags);
 106         if (likely(sem->counter > 0)) {
 107                 sem->counter--;
 108                 spin_unlock_irqrestore(&sem->wait_lock, flags);
 109         }
 110         else {
 111                 ret = __down_interruptible(sem, flags);
 112         }
 113         return ret;
 114 }
 115
 116 /*
 117  * non-blockingly attempt to down() a semaphore.
 118  * - returns zero if we acquired it
 119  */
 120 static inline int down_trylock(struct semaphore *sem)
 121 {
 122         unsigned long flags;
 123         int success = 0;
 124
 125 #if SEMAPHORE_DEBUG
 126         CHECK_MAGIC(sem->__magic);
 127 #endif
 128
 129         spin_lock_irqsave(&sem->wait_lock, flags);
 130         if (sem->counter > 0) {
 131                 sem->counter--;
 132                 success = 1;
 133         }
 134         spin_unlock_irqrestore(&sem->wait_lock, flags);
 135         return !success;
 136 }
 137
 138 static inline void up(struct semaphore *sem)
 139 {
 140         unsigned long flags;
 141
 142 #if SEMAPHORE_DEBUG
 143         CHECK_MAGIC(sem->__magic);
 144 #endif
 145
 146         spin_lock_irqsave(&sem->wait_lock, flags);
 147         if (!list_empty(&sem->wait_list))
 148                 __up(sem);
 149         else
 150                 sem->counter++;
 151         spin_unlock_irqrestore(&sem->wait_lock, flags);
 152 }
 153
 154 static inline int sem_getcount(struct semaphore *sem)
 155 {
 156         return sem->counter;
 157 }
 158
 159 #endif /* __ASSEMBLY__ */
 160
 161 #endif