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/*
* SMP- and interrupt-safe semaphores..
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* (C) Copyright 1996 Linus Torvalds, Ralf Baechle
*/
#ifndef __ASM_MIPS_SEMAPHORE_H
#define __ASM_MIPS_SEMAPHORE_H
#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/spinlock.h>
struct semaphore {
atomic_t count;
atomic_t waking;
struct wait_queue * wait;
};
#define MUTEX ((struct semaphore) { ATOMIC_INIT(1), ATOMIC_INIT(0), NULL })
#define MUTEX_LOCKED ((struct semaphore) { ATOMIC_INIT(0), ATOMIC_INIT(0), NULL })
asmlinkage void __down(struct semaphore * sem);
asmlinkage int __down_interruptible(struct semaphore * sem);
asmlinkage int __down_trylock(struct semaphore * sem);
asmlinkage void __up(struct semaphore * sem);
extern spinlock_t semaphore_wake_lock;
#define sema_init(sem, val) atomic_set(&((sem)->count), val)
extern inline void down(struct semaphore * sem)
{
if (atomic_dec_return(&sem->count) < 0)
__down(sem);
}
extern inline int down_interruptible(struct semaphore * sem)
{
int ret = 0;
if (atomic_dec_return(&sem->count) < 0)
ret = __down_interruptible(sem);
return ret;
}
/*
* down_trylock returns 0 on success, 1 if we failed to get the lock.
*
* We must manipulate count and waking simultaneously and atomically.
* Do this by using ll/sc on the pair of 32-bit words.
*/
extern inline int down_trylock(struct semaphore * sem)
{
long ret, tmp, tmp2, sub;
#ifdef __MIPSEB__
__asm__ __volatile__("
.set mips3
0: lld %1, %4
dli %3, 0x0000000100000000
sltu %0, %1, $0
bltz %1, 1f
move %3, $0
1:
sltu %2, %1, $0
and %0, %0, %2
bnez %0, 2f
subu %0, %3
scd %1, %4
beqz %1, 0b
2:
.set mips0"
: "=&r"(ret), "=&r"(tmp), "=&r"(tmp2), "=&r"(sub)
: "m"(*sem)
: "memory");
#endif
#ifdef __MIPSEL__
#error "FIXME: down_trylock doesn't support little endian machines yet."
#endif
return ret;
}
/*
* Note! This is subtle. We jump to wake people up only if
* the semaphore was negative (== somebody was waiting on it).
*/
extern inline void up(struct semaphore * sem)
{
if (atomic_inc_return(&sem->count) <= 0)
__up(sem);
}
#endif /* __ASM_MIPS_SEMAPHORE_H */
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