include/asm-sh/semaphore.h

   1 #ifndef __ASM_SH_SEMAPHORE_H
   2 #define __ASM_SH_SEMAPHORE_H
   3
   4 #include <linux/linkage.h>
   5
   6 #ifdef __KERNEL__
   7 /*
   8  * SMP- and interrupt-safe semaphores.
   9  *
  10  * (C) Copyright 1996 Linus Torvalds
  11  *
  12  * SuperH verison by Niibe Yutaka
  13  *  (Currently no asm implementation but generic C code...)
  14  */
  15
  16 #include <linux/spinlock.h>
  17 #include <linux/rwsem.h>
  18
  19 #include <asm/system.h>
  20 #include <asm/atomic.h>
  21
  22 struct semaphore {
  23         atomic_t count;
  24         int sleepers;
  25         wait_queue_head_t wait;
  26 #if WAITQUEUE_DEBUG
  27         long __magic;
  28 #endif
  29 };
  30
  31 #if WAITQUEUE_DEBUG
  32 # define __SEM_DEBUG_INIT(name) \
  33                 , (int)&(name).__magic
  34 #else
  35 # define __SEM_DEBUG_INIT(name)
  36 #endif
  37
  38 #define __SEMAPHORE_INITIALIZER(name,count) \
  39 { ATOMIC_INIT(count), 0, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
  40         __SEM_DEBUG_INIT(name) }
  41
  42 #define __MUTEX_INITIALIZER(name) \
  43         __SEMAPHORE_INITIALIZER(name,1)
  44
  45 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  46         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  47
  48 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  49 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  50
  51 static inline void sema_init (struct semaphore *sem, int val)
  52 {
  53 /*
  54  *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  55  *
  56  * i'd rather use the more flexible initialization above, but sadly
  57  * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well.
  58  */
  59         atomic_set(&sem->count, val);
  60         sem->sleepers = 0;
  61         init_waitqueue_head(&sem->wait);
  62 #if WAITQUEUE_DEBUG
  63         sem->__magic = (int)&sem->__magic;
  64 #endif
  65 }
  66
  67 static inline void init_MUTEX (struct semaphore *sem)
  68 {
  69         sema_init(sem, 1);
  70 }
  71
  72 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  73 {
  74         sema_init(sem, 0);
  75 }
  76
  77 #if 0
  78 asmlinkage void __down_failed(void /* special register calling convention */);
  79 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  80 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  81 asmlinkage void __up_wakeup(void /* special register calling convention */);
  82 #endif
  83
  84 asmlinkage void __down(struct semaphore * sem);
  85 asmlinkage int  __down_interruptible(struct semaphore * sem);
  86 asmlinkage int  __down_trylock(struct semaphore * sem);
  87 asmlinkage void __up(struct semaphore * sem);
  88
  89 extern spinlock_t semaphore_wake_lock;
  90
  91 static inline void down(struct semaphore * sem)
  92 {
  93 #if WAITQUEUE_DEBUG
  94         CHECK_MAGIC(sem->__magic);
  95 #endif
  96
  97         if (atomic_dec_return(&sem->count) < 0)
  98                 __down(sem);
  99 }
 100
 101 static inline int down_interruptible(struct semaphore * sem)
 102 {
 103         int ret = 0;
 104 #if WAITQUEUE_DEBUG
 105         CHECK_MAGIC(sem->__magic);
 106 #endif
 107
 108         if (atomic_dec_return(&sem->count) < 0)
 109                 ret = __down_interruptible(sem);
 110         return ret;
 111 }
 112
 113 static inline int down_trylock(struct semaphore * sem)
 114 {
 115         int ret = 0;
 116 #if WAITQUEUE_DEBUG
 117         CHECK_MAGIC(sem->__magic);
 118 #endif
 119
 120         if (atomic_dec_return(&sem->count) < 0)
 121                 ret = __down_trylock(sem);
 122         return ret;
 123 }
 124
 125 /*
 126  * Note! This is subtle. We jump to wake people up only if
 127  * the semaphore was negative (== somebody was waiting on it).
 128  */
 129 static inline void up(struct semaphore * sem)
 130 {
 131 #if WAITQUEUE_DEBUG
 132         CHECK_MAGIC(sem->__magic);
 133 #endif
 134         if (atomic_inc_return(&sem->count) <= 0)
 135                 __up(sem);
 136 }
 137
 138 #endif
 139 #endif /* __ASM_SH_SEMAPHORE_H */