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