/* $Id: semaphore.h,v 1.3 2001/05/08 13:54:09 bjornw Exp $ */ /* On the i386 these are coded in asm, perhaps we should as well. Later.. */ #ifndef _CRIS_SEMAPHORE_H #define _CRIS_SEMAPHORE_H #define RW_LOCK_BIAS 0x01000000 #include <linux/wait.h> #include <linux/spinlock.h> #include <linux/rwsem.h> #include <asm/system.h> #include <asm/atomic.h> /* * CRIS semaphores, implemented in C-only so far. */ struct semaphore { atomic_t count; atomic_t waking; wait_queue_head_t wait; }; #define __SEMAPHORE_INITIALIZER(name, n) \ { \ .count = ATOMIC_INIT(n), \ .waking = ATOMIC_INIT(0), \ .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ } #define __DECLARE_SEMAPHORE_GENERIC(name,count) \ struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) static inline void sema_init(struct semaphore *sem, int val) { *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); } static inline void init_MUTEX (struct semaphore *sem) { sema_init(sem, 1); } static inline void init_MUTEX_LOCKED (struct semaphore *sem) { sema_init(sem, 0); } extern void __down(struct semaphore * sem); extern int __down_interruptible(struct semaphore * sem); extern int __down_trylock(struct semaphore * sem); extern void __up(struct semaphore * sem); /* notice - we probably can do cli/sti here instead of saving */ static inline void down(struct semaphore * sem) { unsigned long flags; int failed; might_sleep(); /* atomically decrement the semaphores count, and if its negative, we wait */ cris_atomic_save(sem, flags); failed = --(sem->count.counter) < 0; cris_atomic_restore(sem, flags); if(failed) { __down(sem); } } /* * This version waits in interruptible state so that the waiting * process can be killed. The down_interruptible routine * returns negative for signalled and zero for semaphore acquired. */ static inline int down_interruptible(struct semaphore * sem) { unsigned long flags; int failed; might_sleep(); /* atomically decrement the semaphores count, and if its negative, we wait */ cris_atomic_save(sem, flags); failed = --(sem->count.counter) < 0; cris_atomic_restore(sem, flags); if(failed) failed = __down_interruptible(sem); return(failed); } static inline int down_trylock(struct semaphore * sem) { unsigned long flags; int failed; cris_atomic_save(sem, flags); failed = --(sem->count.counter) < 0; cris_atomic_restore(sem, flags); if(failed) failed = __down_trylock(sem); return(failed); } /* * Note! This is subtle. We jump to wake people up only if * the semaphore was negative (== somebody was waiting on it). * The default case (no contention) will result in NO * jumps for both down() and up(). */ static inline void up(struct semaphore * sem) { unsigned long flags; int wakeup; /* atomically increment the semaphores count, and if it was negative, we wake people */ cris_atomic_save(sem, flags); wakeup = ++(sem->count.counter) <= 0; cris_atomic_restore(sem, flags); if(wakeup) { __up(sem); } } #endif