target/linux/ubicom32/files/arch/ubicom32/include/asm/semaphore-helper.h

   1 /*
   2  * arch/ubicom32/include/asm/semaphore-helper.h
   3  *   Semaphore related definitions for Ubicom32 architecture.
   4  *
   5  * (C) Copyright 2009, Ubicom, Inc.
   6  *
   7  * This file is part of the Ubicom32 Linux Kernel Port.
   8  *
   9  * The Ubicom32 Linux Kernel Port is free software: you can redistribute
  10  * it and/or modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation, either version 2 of the
  12  * License, or (at your option) any later version.
  13  *
  14  * The Ubicom32 Linux Kernel Port is distributed in the hope that it
  15  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  16  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  17  * the GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with the Ubicom32 Linux Kernel Port.  If not,
  21  * see <http://www.gnu.org/licenses/>.
  22  *
  23  * Ubicom32 implementation derived from (with many thanks):
  24  *   arch/m68knommu
  25  *   arch/blackfin
  26  *   arch/parisc
  27  */
  28 #ifndef _ASM_UBICOM32_SEMAPHORE_HELPER_H
  29 #define _ASM_UBICOM32_SEMAPHORE_HELPER_H
  30
  31 /*
  32  * SMP- and interrupt-safe semaphores helper functions.
  33  *
  34  * (C) Copyright 1996 Linus Torvalds
  35  *
  36  * m68k version by Andreas Schwab
  37  */
  38
  39
  40 /*
  41  * These two _must_ execute atomically wrt each other.
  42  */
  43 static inline void wake_one_more(struct semaphore * sem)
  44 {
  45         atomic_inc(&sem->waking);
  46 }
  47
  48 static inline int waking_non_zero(struct semaphore *sem)
  49 {
  50         int ret;
  51         unsigned long flags;
  52
  53         spin_lock_irqsave(&semaphore_wake_lock, flags);
  54         ret = 0;
  55         if (atomic_read(&sem->waking) > 0) {
  56                 atomic_dec(&sem->waking);
  57                 ret = 1;
  58         }
  59         spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  60         return ret;
  61 }
  62
  63 /*
  64  * waking_non_zero_interruptible:
  65  *      1       got the lock
  66  *      0       go to sleep
  67  *      -EINTR  interrupted
  68  */
  69 static inline int waking_non_zero_interruptible(struct semaphore *sem,
  70                                                 struct task_struct *tsk)
  71 {
  72         int ret;
  73         unsigned long flags;
  74
  75         spin_lock_irqsave(&semaphore_wake_lock, flags);
  76         ret = 0;
  77         if (atomic_read(&sem->waking) > 0) {
  78                 atomic_dec(&sem->waking);
  79                 ret = 1;
  80         } else if (signal_pending(tsk)) {
  81                 atomic_inc(&sem->count);
  82                 ret = -EINTR;
  83         }
  84         spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  85         return ret;
  86 }
  87
  88 /*
  89  * waking_non_zero_trylock:
  90  *      1       failed to lock
  91  *      0       got the lock
  92  */
  93 static inline int waking_non_zero_trylock(struct semaphore *sem)
  94 {
  95         int ret;
  96         unsigned long flags;
  97
  98         spin_lock_irqsave(&semaphore_wake_lock, flags);
  99         ret = 1;
 100         if (atomic_read(&sem->waking) > 0) {
 101                 atomic_dec(&sem->waking);
 102                 ret = 0;
 103         } else
 104                 atomic_inc(&sem->count);
 105         spin_unlock_irqrestore(&semaphore_wake_lock, flags);
 106         return ret;
 107 }
 108
 109 #endif /* _ASM_UBICOM32_SEMAPHORE_HELPER_H */