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 __MUTEX_INITIALIZER(name) __SEMAPHORE_INIT(name,1)
  28
  29 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  30         struct semaphore name = __SEMAPHORE_INIT(name,count)
  31
  32 #define DECLARE_MUTEX(name)             __DECLARE_SEMAPHORE_GENERIC(name,1)
  33 #define DECLARE_MUTEX_LOCKED(name)      __DECLARE_SEMAPHORE_GENERIC(name,0)
  34
  35 static inline void sema_init(struct semaphore *sem, int val)
  36 {
  37         atomic_set(&sem->count, val);
  38         sem->sleepers = 0;
  39         init_waitqueue_head(&sem->wait);
  40 }
  41
  42 static inline void init_MUTEX(struct semaphore *sem)
  43 {
  44         sema_init(sem, 1);
  45 }
  46
  47 static inline void init_MUTEX_LOCKED(struct semaphore *sem)
  48 {
  49         sema_init(sem, 0);
  50 }
  51
  52 static inline int sema_count(struct semaphore *sem)
  53 {
  54         return atomic_read(&sem->count);
  55 }
  56
  57 /*
  58  * special register calling convention
  59  */
  60 asmlinkage void __down_failed(void);
  61 asmlinkage int  __down_interruptible_failed(void);
  62 asmlinkage int  __down_trylock_failed(void);
  63 asmlinkage void __up_wakeup(void);
  64
  65 extern void __down(struct semaphore * sem);
  66 extern int  __down_interruptible(struct semaphore * sem);
  67 extern int  __down_trylock(struct semaphore * sem);
  68 extern void __up(struct semaphore * sem);
  69
  70 /*
  71  * This is ugly, but we want the default case to fall through.
  72  * "__down" is the actual routine that waits...
  73  */
  74 static inline void down(struct semaphore * sem)
  75 {
  76         might_sleep();
  77         __down_op(sem, __down_failed);
  78 }
  79
  80 /*
  81  * This is ugly, but we want the default case to fall through.
  82  * "__down_interruptible" is the actual routine that waits...
  83  */
  84 static inline int down_interruptible (struct semaphore * sem)
  85 {
  86         might_sleep();
  87         return __down_op_ret(sem, __down_interruptible_failed);
  88 }
  89
  90 static inline int down_trylock(struct semaphore *sem)
  91 {
  92         return __down_op_ret(sem, __down_trylock_failed);
  93 }
  94
  95 /*
  96  * Note! This is subtle. We jump to wake people up only if
  97  * the semaphore was negative (== somebody was waiting on it).
  98  * The default case (no contention) will result in NO
  99  * jumps for both down() and up().
 100  */
 101 static inline void up(struct semaphore * sem)
 102 {
 103         __up_op(sem, __up_wakeup);
 104 }
 105
 106 #endif