135 lines
3.1 KiB
C
135 lines
3.1 KiB
C
/* $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
|