include/asm-nios2nommu/semaphore-helper.h

   1 #ifndef _NIOS2NOMMU_SEMAPHORE_HELPER_H
   2 #define _NIOS2NOMMU_SEMAPHORE_HELPER_H
   3
   4 /*--------------------------------------------------------------------
   5  *
   6  * include/asm-nios2nommu/semaphore.h
   7  *
   8  * SMP- and interrupt-safe semaphores helper functions.
   9  *
  10  * Derived from M68knommu
  11  *
  12  * (C) Copyright 1996 Linus Torvalds
  13  * m68k version by Andreas Schwab
  14  * Copyright (C) 2004   Microtronix Datacom Ltd
  15  *
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 2 of the License, or
  19  * (at your option) any later version.
  20  *
  21  * This program is distributed in the hope that it will be useful,
  22  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  23  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  24  * GNU General Public License for more details.
  25  *
  26  * Jan/20/2004          dgt         NiosII
  27  *
  28  ---------------------------------------------------------------------*/
  29
  30 /*
  31  * These two _must_ execute atomically wrt each other.
  32  */
  33 static inline void wake_one_more(struct semaphore * sem)
  34 {
  35         atomic_inc(&sem->waking);
  36 }
  37
  38 static inline int waking_non_zero(struct semaphore *sem)
  39 {
  40         int ret;
  41         unsigned long flags;
  42
  43         spin_lock_irqsave(&semaphore_wake_lock, flags);
  44         ret = 0;
  45         if (atomic_read(&sem->waking) > 0) {
  46                 atomic_dec(&sem->waking);
  47                 ret = 1;
  48         }
  49         spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  50         return ret;
  51 }
  52
  53 /*
  54  * waking_non_zero_interruptible:
  55  *      1       got the lock
  56  *      0       go to sleep
  57  *      -EINTR  interrupted
  58  */
  59 static inline int waking_non_zero_interruptible(struct semaphore *sem,
  60                                                 struct task_struct *tsk)
  61 {
  62         int ret;
  63         unsigned long flags;
  64
  65         spin_lock_irqsave(&semaphore_wake_lock, flags);
  66         ret = 0;
  67         if (atomic_read(&sem->waking) > 0) {
  68                 atomic_dec(&sem->waking);
  69                 ret = 1;
  70         } else if (signal_pending(tsk)) {
  71                 atomic_inc(&sem->count);
  72                 ret = -EINTR;
  73         }
  74         spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  75         return ret;
  76 }
  77
  78 /*
  79  * waking_non_zero_trylock:
  80  *      1       failed to lock
  81  *      0       got the lock
  82  */
  83 static inline int waking_non_zero_trylock(struct semaphore *sem)
  84 {
  85         int ret;
  86         unsigned long flags;
  87
  88         spin_lock_irqsave(&semaphore_wake_lock, flags);
  89         ret = 1;
  90         if (atomic_read(&sem->waking) > 0) {
  91                 atomic_dec(&sem->waking);
  92                 ret = 0;
  93         } else
  94                 atomic_inc(&sem->count);
  95         spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  96         return ret;
  97 }
  98
  99 #endif