include/asm-arm26/semaphore.h

   1 /*
   2  * linux/include/asm-arm26/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 __DECLARE_SEMAPHORE_GENERIC(name,count) \
  29         struct semaphore name = __SEMAPHORE_INIT(name,count)
  30
  31 #define DECLARE_MUTEX(name)             __DECLARE_SEMAPHORE_GENERIC(name,1)
  32 #define DECLARE_MUTEX_LOCKED(name)      __DECLARE_SEMAPHORE_GENERIC(name,0)
  33
  34 static inline void sema_init(struct semaphore *sem, int val)
  35 {
  36         atomic_set(&sem->count, val);
  37         sem->sleepers = 0;
  38         init_waitqueue_head(&sem->wait);
  39 }
  40
  41 static inline void init_MUTEX(struct semaphore *sem)
  42 {
  43         sema_init(sem, 1);
  44 }
  45
  46 static inline void init_MUTEX_LOCKED(struct semaphore *sem)
  47 {
  48         sema_init(sem, 0);
  49 }
  50
  51 /*
  52  * special register calling convention
  53  */
  54 asmlinkage void __down_failed(void);
  55 asmlinkage int  __down_interruptible_failed(void);
  56 asmlinkage int  __down_trylock_failed(void);
  57 asmlinkage void __up_wakeup(void);
  58
  59 extern void __down(struct semaphore * sem);
  60 extern int  __down_interruptible(struct semaphore * sem);
  61 extern int  __down_trylock(struct semaphore * sem);
  62 extern void __up(struct semaphore * sem);
  63
  64 /*
  65  * This is ugly, but we want the default case to fall through.
  66  * "__down" is the actual routine that waits...
  67  */
  68 static inline void down(struct semaphore * sem)
  69 {
  70         might_sleep();
  71         __down_op(sem, __down_failed);
  72 }
  73
  74 /*
  75  * This is ugly, but we want the default case to fall through.
  76  * "__down_interruptible" is the actual routine that waits...
  77  */
  78 static inline int down_interruptible (struct semaphore * sem)
  79 {
  80         might_sleep();
  81         return __down_op_ret(sem, __down_interruptible_failed);
  82 }
  83
  84 static inline int down_trylock(struct semaphore *sem)
  85 {
  86         return __down_op_ret(sem, __down_trylock_failed);
  87 }
  88
  89 /*
  90  * Note! This is subtle. We jump to wake people up only if
  91  * the semaphore was negative (== somebody was waiting on it).
  92  * The default case (no contention) will result in NO
  93  * jumps for both down() and up().
  94  */
  95 static inline void up(struct semaphore * sem)
  96 {
  97         __up_op(sem, __up_wakeup);
  98 }
  99
 100 #endif