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 };
  20
  21 #define __SEMAPHORE_INIT(name, n)                                       \
  22 {                                                                       \
  23         .count          = ATOMIC_INIT(n),                               \
  24         .sleepers       = 0,                                            \
  25         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait),   \
  26 }
  27
  28 #define __MUTEX_INITIALIZER(name) \
  29         __SEMAPHORE_INIT(name,1)
  30
  31 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  32         struct semaphore name = __SEMAPHORE_INIT(name,count)
  33
  34 #define DECLARE_MUTEX(name)             __DECLARE_SEMAPHORE_GENERIC(name,1)
  35 #define DECLARE_MUTEX_LOCKED(name)      __DECLARE_SEMAPHORE_GENERIC(name,0)
  36
  37 static inline void sema_init(struct semaphore *sem, int val)
  38 {
  39         atomic_set(&sem->count, val);
  40         sem->sleepers = 0;
  41         init_waitqueue_head(&sem->wait);
  42 }
  43
  44 static inline void init_MUTEX(struct semaphore *sem)
  45 {
  46         sema_init(sem, 1);
  47 }
  48
  49 static inline void init_MUTEX_LOCKED(struct semaphore *sem)
  50 {
  51         sema_init(sem, 0);
  52 }
  53
  54 /*
  55  * special register calling convention
  56  */
  57 asmlinkage void __down_failed(void);
  58 asmlinkage int  __down_interruptible_failed(void);
  59 asmlinkage int  __down_trylock_failed(void);
  60 asmlinkage void __up_wakeup(void);
  61
  62 extern void __down(struct semaphore * sem);
  63 extern int  __down_interruptible(struct semaphore * sem);
  64 extern int  __down_trylock(struct semaphore * sem);
  65 extern void __up(struct semaphore * sem);
  66
  67 /*
  68  * This is ugly, but we want the default case to fall through.
  69  * "__down" is the actual routine that waits...
  70  */
  71 static inline void down(struct semaphore * sem)
  72 {
  73         might_sleep();
  74         __down_op(sem, __down_failed);
  75 }
  76
  77 /*
  78  * This is ugly, but we want the default case to fall through.
  79  * "__down_interruptible" is the actual routine that waits...
  80  */
  81 static inline int down_interruptible (struct semaphore * sem)
  82 {
  83         might_sleep();
  84         return __down_op_ret(sem, __down_interruptible_failed);
  85 }
  86
  87 static inline int down_trylock(struct semaphore *sem)
  88 {
  89         return __down_op_ret(sem, __down_trylock_failed);
  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  */
  98 static inline void up(struct semaphore * sem)
  99 {
 100         __up_op(sem, __up_wakeup);
 101 }
 102
 103 #endif