1 /* $Id: semaphore.h,v 1.3 2001/05/08 13:54:09 bjornw Exp $ */
3 /* On the i386 these are coded in asm, perhaps we should as well. Later.. */
5 #ifndef _CRIS_SEMAPHORE_H
6 #define _CRIS_SEMAPHORE_H
8 #define RW_LOCK_BIAS 0x01000000
10 #include <linux/wait.h>
11 #include <linux/spinlock.h>
12 #include <linux/rwsem.h>
14 #include <asm/system.h>
15 #include <asm/atomic.h>
18 * CRIS semaphores, implemented in C-only so far.
24 wait_queue_head_t wait;
27 #define __SEMAPHORE_INITIALIZER(name, n) \
29 .count = ATOMIC_INIT(n), \
30 .waking = ATOMIC_INIT(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)
38 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
40 static inline void sema_init(struct semaphore *sem, int val)
42 *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
45 static inline void init_MUTEX (struct semaphore *sem)
50 static inline void init_MUTEX_LOCKED (struct semaphore *sem)
55 extern void __down(struct semaphore * sem);
56 extern int __down_interruptible(struct semaphore * sem);
57 extern int __down_trylock(struct semaphore * sem);
58 extern void __up(struct semaphore * sem);
60 /* notice - we probably can do cli/sti here instead of saving */
62 static inline void down(struct semaphore * sem)
69 /* atomically decrement the semaphores count, and if its negative, we wait */
70 cris_atomic_save(sem, flags);
71 failed = --(sem->count.counter) < 0;
72 cris_atomic_restore(sem, flags);
79 * This version waits in interruptible state so that the waiting
80 * process can be killed. The down_interruptible routine
81 * returns negative for signalled and zero for semaphore acquired.
84 static inline int down_interruptible(struct semaphore * sem)
91 /* atomically decrement the semaphores count, and if its negative, we wait */
92 cris_atomic_save(sem, flags);
93 failed = --(sem->count.counter) < 0;
94 cris_atomic_restore(sem, flags);
96 failed = __down_interruptible(sem);
100 static inline int down_trylock(struct semaphore * sem)
105 cris_atomic_save(sem, flags);
106 failed = --(sem->count.counter) < 0;
107 cris_atomic_restore(sem, flags);
109 failed = __down_trylock(sem);
115 * Note! This is subtle. We jump to wake people up only if
116 * the semaphore was negative (== somebody was waiting on it).
117 * The default case (no contention) will result in NO
118 * jumps for both down() and up().
120 static inline void up(struct semaphore * sem)
125 /* atomically increment the semaphores count, and if it was negative, we wake people */
126 cris_atomic_save(sem, flags);
127 wakeup = ++(sem->count.counter) <= 0;
128 cris_atomic_restore(sem, flags);