include/asm-arm26/semaphore.h

   1 /*
   2  * linux/include/asm-arm/semaphore.h
   3  */
   4 #ifndef __ASM_ARM_SEMAPHORE_H
   5 #define __ASM_ARM_SEMAPHORE_H
   6
   7 #include <linux/linkage.h>
   8 #include <linux/spinlock.h>
   9 #include <linux/wait.h>
  10 #include <linux/rwsem.h>
  11
  12 #include <asm/atomic.h>
  13 #include <asm/locks.h>
  14
  15 struct semaphore {
  16         atomic_t count;
  17         int sleepers;
  18         wait_queue_head_t wait;
  19 #if WAITQUEUE_DEBUG
  20         long __magic;
  21 #endif
  22 };
  23
  24 #if WAITQUEUE_DEBUG
  25 # define __SEM_DEBUG_INIT(name) \
  26                 , (long)&(name).__magic
  27 #else
  28 # define __SEM_DEBUG_INIT(name)
  29 #endif
  30
  31 #define __SEMAPHORE_INIT(name,count)                    \
  32         { ATOMIC_INIT(count), 0,                        \
  33           __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  34           __SEM_DEBUG_INIT(name) }
  35
  36 #define __MUTEX_INITIALIZER(name) \
  37         __SEMAPHORE_INIT(name,1)
  38
  39 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  40         struct semaphore name = __SEMAPHORE_INIT(name,count)
  41
  42 #define DECLARE_MUTEX(name)             __DECLARE_SEMAPHORE_GENERIC(name,1)
  43 #define DECLARE_MUTEX_LOCKED(name)      __DECLARE_SEMAPHORE_GENERIC(name,0)
  44
  45 static inline void sema_init(struct semaphore *sem, int val)
  46 {
  47         atomic_set(&sem->count, val);
  48         sem->sleepers = 0;
  49         init_waitqueue_head(&sem->wait);
  50 #if WAITQUEUE_DEBUG
  51         sem->__magic = (long)&sem->__magic;
  52 #endif
  53 }
  54
  55 static inline void init_MUTEX(struct semaphore *sem)
  56 {
  57         sema_init(sem, 1);
  58 }
  59
  60 static inline void init_MUTEX_LOCKED(struct semaphore *sem)
  61 {
  62         sema_init(sem, 0);
  63 }
  64
  65 /*
  66  * special register calling convention
  67  */
  68 asmlinkage void __down_failed(void);
  69 asmlinkage int  __down_interruptible_failed(void);
  70 asmlinkage int  __down_trylock_failed(void);
  71 asmlinkage void __up_wakeup(void);
  72
  73 extern void __down(struct semaphore * sem);
  74 extern int  __down_interruptible(struct semaphore * sem);
  75 extern int  __down_trylock(struct semaphore * sem);
  76 extern void __up(struct semaphore * sem);
  77
  78 /*
  79  * This is ugly, but we want the default case to fall through.
  80  * "__down" is the actual routine that waits...
  81  */
  82 static inline void down(struct semaphore * sem)
  83 {
  84 #if WAITQUEUE_DEBUG
  85         CHECK_MAGIC(sem->__magic);
  86 #endif
  87         might_sleep();
  88         __down_op(sem, __down_failed);
  89 }
  90
  91 /*
  92  * This is ugly, but we want the default case to fall through.
  93  * "__down_interruptible" is the actual routine that waits...
  94  */
  95 static inline int down_interruptible (struct semaphore * sem)
  96 {
  97 #if WAITQUEUE_DEBUG
  98         CHECK_MAGIC(sem->__magic);
  99 #endif
 100         might_sleep();
 101         return __down_op_ret(sem, __down_interruptible_failed);
 102 }
 103
 104 static inline int down_trylock(struct semaphore *sem)
 105 {
 106 #if WAITQUEUE_DEBUG
 107         CHECK_MAGIC(sem->__magic);
 108 #endif
 109
 110         return __down_op_ret(sem, __down_trylock_failed);
 111 }
 112
 113 /*
 114  * Note! This is subtle. We jump to wake people up only if
 115  * the semaphore was negative (== somebody was waiting on it).
 116  * The default case (no contention) will result in NO
 117  * jumps for both down() and up().
 118  */
 119 static inline void up(struct semaphore * sem)
 120 {
 121 #if WAITQUEUE_DEBUG
 122         CHECK_MAGIC(sem->__magic);
 123 #endif
 124
 125         __up_op(sem, __up_wakeup);
 126 }
 127
 128 #endif