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 #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