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 #ifdef WAITQUEUE_DEBUG
  20         long __magic;
  21 #endif
  22 };
  23
  24 #ifdef WAITQUEUE_DEBUG
  25 # define __SEM_DEBUG_INIT(name) .__magic = (long)&(name).__magic
  26 #else
  27 # define __SEM_DEBUG_INIT(name)
  28 #endif
  29
  30 #define __SEMAPHORE_INIT(name,cnt) {                            \
  31         .count  = ATOMIC_INIT(cnt),                             \
  32         .wait   = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait),   \
  33         __SEM_DEBUG_INIT(name)                                  \
  34 }
  35
  36 #define __MUTEX_INITIALIZER(name) __SEMAPHORE_INIT(name,1)
  37
  38 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  39         struct semaphore name = __SEMAPHORE_INIT(name,count)
  40
  41 #define DECLARE_MUTEX(name)             __DECLARE_SEMAPHORE_GENERIC(name,1)
  42 #define DECLARE_MUTEX_LOCKED(name)      __DECLARE_SEMAPHORE_GENERIC(name,0)
  43
  44 static inline void sema_init(struct semaphore *sem, int val)
  45 {
  46         atomic_set(&sem->count, val);
  47         sem->sleepers = 0;
  48         init_waitqueue_head(&sem->wait);
  49 #ifdef WAITQUEUE_DEBUG
  50         sem->__magic = (long)&sem->__magic;
  51 #endif
  52 }
  53
  54 static inline void init_MUTEX(struct semaphore *sem)
  55 {
  56         sema_init(sem, 1);
  57 }
  58
  59 static inline void init_MUTEX_LOCKED(struct semaphore *sem)
  60 {
  61         sema_init(sem, 0);
  62 }
  63
  64 static inline int sema_count(struct semaphore *sem)
  65 {
  66         return atomic_read(&sem->count);
  67 }
  68
  69 /*
  70  * special register calling convention
  71  */
  72 asmlinkage void __down_failed(void);
  73 asmlinkage int  __down_interruptible_failed(void);
  74 asmlinkage int  __down_trylock_failed(void);
  75 asmlinkage void __up_wakeup(void);
  76
  77 extern void __down(struct semaphore * sem);
  78 extern int  __down_interruptible(struct semaphore * sem);
  79 extern int  __down_trylock(struct semaphore * sem);
  80 extern void __up(struct semaphore * sem);
  81
  82 /*
  83  * This is ugly, but we want the default case to fall through.
  84  * "__down" is the actual routine that waits...
  85  */
  86 static inline void down(struct semaphore * sem)
  87 {
  88 #ifdef WAITQUEUE_DEBUG
  89         CHECK_MAGIC(sem->__magic);
  90 #endif
  91         might_sleep();
  92         __down_op(sem, __down_failed);
  93 }
  94
  95 /*
  96  * This is ugly, but we want the default case to fall through.
  97  * "__down_interruptible" is the actual routine that waits...
  98  */
  99 static inline int down_interruptible (struct semaphore * sem)
 100 {
 101 #ifdef WAITQUEUE_DEBUG
 102         CHECK_MAGIC(sem->__magic);
 103 #endif
 104         might_sleep();
 105         return __down_op_ret(sem, __down_interruptible_failed);
 106 }
 107
 108 static inline int down_trylock(struct semaphore *sem)
 109 {
 110 #ifdef WAITQUEUE_DEBUG
 111         CHECK_MAGIC(sem->__magic);
 112 #endif
 113
 114         return __down_op_ret(sem, __down_trylock_failed);
 115 }
 116
 117 /*
 118  * Note! This is subtle. We jump to wake people up only if
 119  * the semaphore was negative (== somebody was waiting on it).
 120  * The default case (no contention) will result in NO
 121  * jumps for both down() and up().
 122  */
 123 static inline void up(struct semaphore * sem)
 124 {
 125 #ifdef WAITQUEUE_DEBUG
 126         CHECK_MAGIC(sem->__magic);
 127 #endif
 128
 129         __up_op(sem, __up_wakeup);
 130 }
 131
 132 #endif