include/asm-blackfin/semaphore-helper.h

   1 /* Based on M68K version,       Lineo Inc.      May 2001 */
   2
   3 #ifndef _BFIN_SEMAPHORE_HELPER_H
   4 #define _BFIN_SEMAPHORE_HELPER_H
   5
   6 /*
   7  * SMP- and interrupt-safe semaphores helper functions.
   8  *
   9  * (C) Copyright 1996 Linus Torvalds
  10  *
  11  */
  12
  13 #include <asm/errno.h>
  14
  15 /*
  16  * These two _must_ execute atomically wrt each other.
  17  */
  18 static inline void wake_one_more(struct semaphore *sem)
  19 {
  20         atomic_inc(&sem->waking);
  21 }
  22
  23 static inline int waking_non_zero(struct semaphore *sem)
  24 {
  25         int ret;
  26         unsigned long flags = 0;
  27
  28         spin_lock_irqsave(&semaphore_wake_lock, flags);
  29         ret = 0;
  30         if (atomic_read(&sem->waking) > 0) {
  31                 atomic_dec(&sem->waking);
  32                 ret = 1;
  33         }
  34         spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  35         return ret;
  36 }
  37
  38 /*
  39  * waking_non_zero_interruptible:
  40  *      1       got the lock
  41  *      0       go to sleep
  42  *      -EINTR  interrupted
  43  */
  44 static inline int waking_non_zero_interruptible(struct semaphore *sem,
  45                                                 struct task_struct *tsk)
  46 {
  47         int ret = 0;
  48         unsigned long flags = 0;
  49
  50         spin_lock_irqsave(&semaphore_wake_lock, flags);
  51         if (atomic_read(&sem->waking) > 0) {
  52                 atomic_dec(&sem->waking);
  53                 ret = 1;
  54         } else if (signal_pending(tsk)) {
  55                 atomic_inc(&sem->count);
  56                 ret = -EINTR;
  57         }
  58         spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  59         return ret;
  60 }
  61
  62 /*
  63  * waking_non_zero_trylock:
  64  *      1       failed to lock
  65  *      0       got the lock
  66  */
  67 static inline int waking_non_zero_trylock(struct semaphore *sem)
  68 {
  69         int ret = 1;
  70         unsigned long flags = 0;
  71
  72         spin_lock_irqsave(&semaphore_wake_lock, flags);
  73         if (atomic_read(&sem->waking) > 0) {
  74                 atomic_dec(&sem->waking);
  75                 ret = 0;
  76         } else
  77                 atomic_inc(&sem->count);
  78         spin_unlock_irqrestore(&semaphore_wake_lock, flags);
  79         return ret;
  80 }
  81
  82 #endif                          /* _BFIN_SEMAPHORE_HELPER_H */