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      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, cnt)				\
     22 {								\
     23 	.count	= ATOMIC_INIT(cnt),				\
     24 	.wait	= __WAIT_QUEUE_HEAD_INITIALIZER((name).wait),	\
     25 }
     26 
     27 #define __DECLARE_SEMAPHORE_GENERIC(name,count)	\
     28 	struct semaphore name = __SEMAPHORE_INIT(name,count)
     29 
     30 #define DECLARE_MUTEX(name)		__DECLARE_SEMAPHORE_GENERIC(name,1)
     31 #define DECLARE_MUTEX_LOCKED(name)	__DECLARE_SEMAPHORE_GENERIC(name,0)
     32 
     33 static inline void sema_init(struct semaphore *sem, int val)
     34 {
     35 	atomic_set(&sem->count, val);
     36 	sem->sleepers = 0;
     37 	init_waitqueue_head(&sem->wait);
     38 }
     39 
     40 static inline void init_MUTEX(struct semaphore *sem)
     41 {
     42 	sema_init(sem, 1);
     43 }
     44 
     45 static inline void init_MUTEX_LOCKED(struct semaphore *sem)
     46 {
     47 	sema_init(sem, 0);
     48 }
     49 
     50 /*
     51  * special register calling convention
     52  */
     53 asmlinkage void __down_failed(void);
     54 asmlinkage int  __down_interruptible_failed(void);
     55 asmlinkage int  __down_trylock_failed(void);
     56 asmlinkage void __up_wakeup(void);
     57 
     58 extern void __down(struct semaphore * sem);
     59 extern int  __down_interruptible(struct semaphore * sem);
     60 extern int  __down_trylock(struct semaphore * sem);
     61 extern void __up(struct semaphore * sem);
     62 
     63 /*
     64  * This is ugly, but we want the default case to fall through.
     65  * "__down" is the actual routine that waits...
     66  */
     67 static inline void down(struct semaphore * sem)
     68 {
     69 	might_sleep();
     70 	__down_op(sem, __down_failed);
     71 }
     72 
     73 /*
     74  * This is ugly, but we want the default case to fall through.
     75  * "__down_interruptible" is the actual routine that waits...
     76  */
     77 static inline int down_interruptible (struct semaphore * sem)
     78 {
     79 	might_sleep();
     80 	return __down_op_ret(sem, __down_interruptible_failed);
     81 }
     82 
     83 static inline int down_trylock(struct semaphore *sem)
     84 {
     85 	return __down_op_ret(sem, __down_trylock_failed);
     86 }
     87 
     88 /*
     89  * Note! This is subtle. We jump to wake people up only if
     90  * the semaphore was negative (== somebody was waiting on it).
     91  * The default case (no contention) will result in NO
     92  * jumps for both down() and up().
     93  */
     94 static inline void up(struct semaphore * sem)
     95 {
     96 	__up_op(sem, __up_wakeup);
     97 }
     98 
     99 #endif
    100