LXR linux/include/asm-blackfin/semaphore.h

   1#ifndef _BFIN_SEMAPHORE_H
   2#define _BFIN_SEMAPHORE_H
   3
   4#ifndef __ASSEMBLY__
   5
   6#include <linux/linkage.h>
   7#include <linux/wait.h>
   8#include <linux/spinlock.h>
   9#include <linux/rwsem.h>
  10#include <asm/atomic.h>
  11
  12/*
  13 * Interrupt-safe semaphores..
  14 *
  15 * (C) Copyright 1996 Linus Torvalds
  16 *
  17 * BFIN version by akbar hussain Lineo Inc  April 2001
  18 *
  19 */
  20
  21struct semaphore {
  22        atomic_t count;
  23        int sleepers;
  24        wait_queue_head_t wait;
  25};
  26
  27#define __SEMAPHORE_INITIALIZER(name, n)                                \
  28{                                                                       \
  29        .count          = ATOMIC_INIT(n),                               \
  30        .sleepers       = 0,                                            \
  31        .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  32}
  33
  34#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  35        struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  36
  37#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  38
  39static inline void sema_init(struct semaphore *sem, int val)
  40{
  41        *sem = (struct semaphore)__SEMAPHORE_INITIALIZER(*sem, val);
  42}
  43
  44static inline void init_MUTEX(struct semaphore *sem)
  45{
  46        sema_init(sem, 1);
  47}
  48
  49static inline void init_MUTEX_LOCKED(struct semaphore *sem)
  50{
  51        sema_init(sem, 0);
  52}
  53
  54asmlinkage void __down(struct semaphore *sem);
  55asmlinkage int __down_interruptible(struct semaphore *sem);
  56asmlinkage int __down_trylock(struct semaphore *sem);
  57asmlinkage void __up(struct semaphore *sem);
  58
  59extern spinlock_t semaphore_wake_lock;
  60
  61/*
  62 * This is ugly, but we want the default case to fall through.
  63 * "down_failed" is a special asm handler that calls the C
  64 * routine that actually waits.
  65 */
  66static inline void down(struct semaphore *sem)
  67{
  68        might_sleep();
  69        if (atomic_dec_return(&sem->count) < 0)
  70                __down(sem);
  71}
  72
  73static inline int down_interruptible(struct semaphore *sem)
  74{
  75        int ret = 0;
  76
  77        might_sleep();
  78        if (atomic_dec_return(&sem->count) < 0)
  79                ret = __down_interruptible(sem);
  80        return (ret);
  81}
  82
  83static inline int down_trylock(struct semaphore *sem)
  84{
  85        int ret = 0;
  86
  87        if (atomic_dec_return(&sem->count) < 0)
  88                ret = __down_trylock(sem);
  89        return ret;
  90}
  91
  92/*
  93 * Note! This is subtle. We jump to wake people up only if
  94 * the semaphore was negative (== somebody was waiting on it).
  95 * The default case (no contention) will result in NO
  96 * jumps for both down() and up().
  97 */
  98static inline void up(struct semaphore *sem)
  99{
 100        if (atomic_inc_return(&sem->count) <= 0)
 101                __up(sem);
 102}
 103
 104#endif                          /* __ASSEMBLY__ */
 105#endif                          /* _BFIN_SEMAPHORE_H */
 106