include/asm-m32r/semaphore.h

   1 #ifndef _ASM_M32R_SEMAPHORE_H
   2 #define _ASM_M32R_SEMAPHORE_H
   3
   4 #include <linux/linkage.h>
   5
   6 #ifdef __KERNEL__
   7
   8 /*
   9  * SMP- and interrupt-safe semaphores..
  10  *
  11  * Copyright (C) 1996  Linus Torvalds
  12  * Copyright (C) 2004, 2006  Hirokazu Takata <takata at linux-m32r.org>
  13  */
  14
  15 #include <linux/wait.h>
  16 #include <linux/rwsem.h>
  17 #include <asm/assembler.h>
  18 #include <asm/system.h>
  19 #include <asm/atomic.h>
  20
  21 struct semaphore {
  22         atomic_t count;
  23         int sleepers;
  24         wait_queue_head_t wait;
  25 };
  26
  27 #define __SEMAPHORE_INITIALIZER(name, n)                                \
  28 {                                                                       \
  29         .count          = ATOMIC_INIT(n),                               \
  30         .sleepers       = 0,                                            \
  31         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  32 }
  33
  34 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  35         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  36
  37 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  38 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  39
  40 static inline void sema_init (struct semaphore *sem, int val)
  41 {
  42 /*
  43  *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  44  *
  45  * i'd rather use the more flexible initialization above, but sadly
  46  * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well.
  47  */
  48         atomic_set(&sem->count, val);
  49         sem->sleepers = 0;
  50         init_waitqueue_head(&sem->wait);
  51 }
  52
  53 static inline void init_MUTEX (struct semaphore *sem)
  54 {
  55         sema_init(sem, 1);
  56 }
  57
  58 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  59 {
  60         sema_init(sem, 0);
  61 }
  62
  63 asmlinkage void __down_failed(void /* special register calling convention */);
  64 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  65 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  66 asmlinkage void __up_wakeup(void /* special register calling convention */);
  67
  68 asmlinkage void __down(struct semaphore * sem);
  69 asmlinkage int  __down_interruptible(struct semaphore * sem);
  70 asmlinkage int  __down_trylock(struct semaphore * sem);
  71 asmlinkage void __up(struct semaphore * sem);
  72
  73 /*
  74  * Atomically decrement the semaphore's count.  If it goes negative,
  75  * block the calling thread in the TASK_UNINTERRUPTIBLE state.
  76  */
  77 static inline void down(struct semaphore * sem)
  78 {
  79         might_sleep();
  80         if (unlikely(atomic_dec_return(&sem->count) < 0))
  81                 __down(sem);
  82 }
  83
  84 /*
  85  * Interruptible try to acquire a semaphore.  If we obtained
  86  * it, return zero.  If we were interrupted, returns -EINTR
  87  */
  88 static inline int down_interruptible(struct semaphore * sem)
  89 {
  90         int result = 0;
  91
  92         might_sleep();
  93         if (unlikely(atomic_dec_return(&sem->count) < 0))
  94                 result = __down_interruptible(sem);
  95
  96         return result;
  97 }
  98
  99 /*
 100  * Non-blockingly attempt to down() a semaphore.
 101  * Returns zero if we acquired it
 102  */
 103 static inline int down_trylock(struct semaphore * sem)
 104 {
 105         unsigned long flags;
 106         long count;
 107         int result = 0;
 108
 109         local_irq_save(flags);
 110         __asm__ __volatile__ (
 111                 "# down_trylock                 \n\t"
 112                 DCACHE_CLEAR("%0", "r4", "%1")
 113                 M32R_LOCK" %0, @%1;             \n\t"
 114                 "addi   %0, #-1;                \n\t"
 115                 M32R_UNLOCK" %0, @%1;           \n\t"
 116                 : "=&r" (count)
 117                 : "r" (&sem->count)
 118                 : "memory"
 119 #ifdef CONFIG_CHIP_M32700_TS1
 120                 , "r4"
 121 #endif  /* CONFIG_CHIP_M32700_TS1 */
 122         );
 123         local_irq_restore(flags);
 124
 125         if (unlikely(count < 0))
 126                 result = __down_trylock(sem);
 127
 128         return result;
 129 }
 130
 131 /*
 132  * Note! This is subtle. We jump to wake people up only if
 133  * the semaphore was negative (== somebody was waiting on it).
 134  * The default case (no contention) will result in NO
 135  * jumps for both down() and up().
 136  */
 137 static inline void up(struct semaphore * sem)
 138 {
 139         if (unlikely(atomic_inc_return(&sem->count) <= 0))
 140                 __up(sem);
 141 }
 142
 143 #endif  /* __KERNEL__ */
 144
 145 #endif  /* _ASM_M32R_SEMAPHORE_H */