Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux...
[wrt350n-kernel.git] / include / asm-m32r / semaphore.h
blobb5bf95a6f2b475890eebdd8ff5f3eec29e872153
1 #ifndef _ASM_M32R_SEMAPHORE_H
2 #define _ASM_M32R_SEMAPHORE_H
4 #include <linux/linkage.h>
6 #ifdef __KERNEL__
8 /*
9 * SMP- and interrupt-safe semaphores..
11 * Copyright (C) 1996 Linus Torvalds
12 * Copyright (C) 2004, 2006 Hirokazu Takata <takata at linux-m32r.org>
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>
21 struct semaphore {
22 atomic_t count;
23 int sleepers;
24 wait_queue_head_t wait;
27 #define __SEMAPHORE_INITIALIZER(name, n) \
28 { \
29 .count = ATOMIC_INIT(n), \
30 .sleepers = 0, \
31 .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
34 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
35 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
37 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
39 static inline void sema_init (struct semaphore *sem, int val)
42 * *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
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.
47 atomic_set(&sem->count, val);
48 sem->sleepers = 0;
49 init_waitqueue_head(&sem->wait);
52 static inline void init_MUTEX (struct semaphore *sem)
54 sema_init(sem, 1);
57 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
59 sema_init(sem, 0);
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 */);
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);
73 * Atomically decrement the semaphore's count. If it goes negative,
74 * block the calling thread in the TASK_UNINTERRUPTIBLE state.
76 static inline void down(struct semaphore * sem)
78 might_sleep();
79 if (unlikely(atomic_dec_return(&sem->count) < 0))
80 __down(sem);
84 * Interruptible try to acquire a semaphore. If we obtained
85 * it, return zero. If we were interrupted, returns -EINTR
87 static inline int down_interruptible(struct semaphore * sem)
89 int result = 0;
91 might_sleep();
92 if (unlikely(atomic_dec_return(&sem->count) < 0))
93 result = __down_interruptible(sem);
95 return result;
99 * Non-blockingly attempt to down() a semaphore.
100 * Returns zero if we acquired it
102 static inline int down_trylock(struct semaphore * sem)
104 unsigned long flags;
105 long count;
106 int result = 0;
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 */
122 local_irq_restore(flags);
124 if (unlikely(count < 0))
125 result = __down_trylock(sem);
127 return result;
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().
136 static inline void up(struct semaphore * sem)
138 if (unlikely(atomic_inc_return(&sem->count) <= 0))
139 __up(sem);
142 #endif /* __KERNEL__ */
144 #endif /* _ASM_M32R_SEMAPHORE_H */