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 #include <linux/wait.h>
  19
  20 #include <asm/system.h>
  21 #include <asm/atomic.h>
  22
  23 struct semaphore {
  24         atomic_t count;
  25         int sleepers;
  26         wait_queue_head_t wait;
  27 };
  28
  29 #define __SEMAPHORE_INITIALIZER(name, n)                                \
  30 {                                                                       \
  31         .count          = ATOMIC_INIT(n),                               \
  32         .sleepers       = 0,                                            \
  33         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  34 }
  35
  36 #define __MUTEX_INITIALIZER(name) \
  37         __SEMAPHORE_INITIALIZER(name,1)
  38
  39 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  40         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  41
  42 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  43 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  44
  45 static inline void sema_init (struct semaphore *sem, int val)
  46 {
  47 /*
  48  *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  49  *
  50  * i'd rather use the more flexible initialization above, but sadly
  51  * GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
  52  */
  53         atomic_set(&sem->count, val);
  54         sem->sleepers = 0;
  55         init_waitqueue_head(&sem->wait);
  56 }
  57
  58 static inline void init_MUTEX (struct semaphore *sem)
  59 {
  60         sema_init(sem, 1);
  61 }
  62
  63 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  64 {
  65         sema_init(sem, 0);
  66 }
  67
  68 #if 0
  69 asmlinkage void __down_failed(void /* special register calling convention */);
  70 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  71 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  72 asmlinkage void __up_wakeup(void /* special register calling convention */);
  73 #endif
  74
  75 asmlinkage void __down(struct semaphore * sem);
  76 asmlinkage int  __down_interruptible(struct semaphore * sem);
  77 asmlinkage int  __down_trylock(struct semaphore * sem);
  78 asmlinkage void __up(struct semaphore * sem);
  79
  80 extern spinlock_t semaphore_wake_lock;
  81
  82 static inline void down(struct semaphore * sem)
  83 {
  84         might_sleep();
  85         if (atomic_dec_return(&sem->count) < 0)
  86                 __down(sem);
  87 }
  88
  89 static inline int down_interruptible(struct semaphore * sem)
  90 {
  91         int ret = 0;
  92
  93         might_sleep();
  94         if (atomic_dec_return(&sem->count) < 0)
  95                 ret = __down_interruptible(sem);
  96         return ret;
  97 }
  98
  99 static inline int down_trylock(struct semaphore * sem)
 100 {
 101         int ret = 0;
 102
 103         if (atomic_dec_return(&sem->count) < 0)
 104                 ret = __down_trylock(sem);
 105         return ret;
 106 }
 107
 108 /*
 109  * Note! This is subtle. We jump to wake people up only if
 110  * the semaphore was negative (== somebody was waiting on it).
 111  */
 112 static inline void up(struct semaphore * sem)
 113 {
 114         if (atomic_inc_return(&sem->count) <= 0)
 115                 __up(sem);
 116 }
 117
 118 #endif
 119 #endif /* __ASM_SH_SEMAPHORE_H */