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
  39 static inline void sema_init (struct semaphore *sem, int val)
  40 {
  41 /*
  42  *      *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  43  *
  44  * i'd rather use the more flexible initialization above, but sadly
  45  * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well.
  46  */
  47         atomic_set(&sem->count, val);
  48         sem->sleepers = 0;
  49         init_waitqueue_head(&sem->wait);
  50 }
  51
  52 static inline void init_MUTEX (struct semaphore *sem)
  53 {
  54         sema_init(sem, 1);
  55 }
  56
  57 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
  58 {
  59         sema_init(sem, 0);
  60 }
  61
  62 asmlinkage void __down_failed(void /* special register calling convention */);
  63 asmlinkage int  __down_failed_interruptible(void  /* params in registers */);
  64 asmlinkage int  __down_failed_trylock(void  /* params in registers */);
  65 asmlinkage void __up_wakeup(void /* special register calling convention */);
  66
  67 asmlinkage void __down(struct semaphore * sem);
  68 asmlinkage int  __down_interruptible(struct semaphore * sem);
  69 asmlinkage int  __down_trylock(struct semaphore * sem);
  70 asmlinkage void __up(struct semaphore * sem);
  71
  72 /*
  73  * Atomically decrement the semaphore's count.  If it goes negative,
  74  * block the calling thread in the TASK_UNINTERRUPTIBLE state.
  75  */
  76 static inline void down(struct semaphore * sem)
  77 {
  78         might_sleep();
  79         if (unlikely(atomic_dec_return(&sem->count) < 0))
  80                 __down(sem);
  81 }
  82
  83 /*
  84  * Interruptible try to acquire a semaphore.  If we obtained
  85  * it, return zero.  If we were interrupted, returns -EINTR
  86  */
  87 static inline int down_interruptible(struct semaphore * sem)
  88 {
  89         int result = 0;
  90
  91         might_sleep();
  92         if (unlikely(atomic_dec_return(&sem->count) < 0))
  93                 result = __down_interruptible(sem);
  94
  95         return result;
  96 }
  97
  98 /*
  99  * Non-blockingly attempt to down() a semaphore.
 100  * Returns zero if we acquired it
 101  */
 102 static inline int down_trylock(struct semaphore * sem)
 103 {
 104         unsigned long flags;
 105         long count;
 106         int result = 0;
 107
 108         local_irq_save(flags);
 109         __asm__ __volatile__ (
 110                 "# down_trylock                 \n\t"
 111                 DCACHE_CLEAR("%0", "r4", "%1")
 112                 M32R_LOCK" %0, @%1;             \n\t"
 113                 "addi   %0, #-1;                \n\t"
 114                 M32R_UNLOCK" %0, @%1;           \n\t"
 115                 : "=&r" (count)
 116                 : "r" (&sem->count)
 117                 : "memory"
 118 #ifdef CONFIG_CHIP_M32700_TS1
 119                 , "r4"
 120 #endif  /* CONFIG_CHIP_M32700_TS1 */
 121         );
 122         local_irq_restore(flags);
 123
 124         if (unlikely(count < 0))
 125                 result = __down_trylock(sem);
 126
 127         return result;
 128 }
 129
 130 /*
 131  * Note! This is subtle. We jump to wake people up only if
 132  * the semaphore was negative (== somebody was waiting on it).
 133  * The default case (no contention) will result in NO
 134  * jumps for both down() and up().
 135  */
 136 static inline void up(struct semaphore * sem)
 137 {
 138         if (unlikely(atomic_inc_return(&sem->count) <= 0))
 139                 __up(sem);
 140 }
 141
 142 #endif  /* __KERNEL__ */
 143
 144 #endif  /* _ASM_M32R_SEMAPHORE_H */