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/*
* include/asm-sh/spinlock.h
*
* Copyright (C) 2002, 2003 Paul Mundt
*
* 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.
*/
#ifndef __ASM_SH_SPINLOCK_H
#define __ASM_SH_SPINLOCK_H
#include <asm/atomic.h>
/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
*/
#define __raw_spin_is_locked(x) ((x)->lock != 0)
#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
#define __raw_spin_unlock_wait(x) \
do { cpu_relax(); } while (__raw_spin_is_locked(x))
/*
* Simple spin lock operations. There are two variants, one clears IRQ's
* on the local processor, one does not.
*
* We make no fairness assumptions. They have a cost.
*/
static inline void __raw_spin_lock(raw_spinlock_t *lock)
{
__asm__ __volatile__ (
"1:\n\t"
"tas.b @%0\n\t"
"bf/s 1b\n\t"
"nop\n\t"
: "=r" (lock->lock)
: "r" (&lock->lock)
: "t", "memory"
);
}
static inline void __raw_spin_unlock(raw_spinlock_t *lock)
{
assert_spin_locked(lock);
lock->lock = 0;
}
#define __raw_spin_trylock(x) (!test_and_set_bit(0, &(x)->lock))
/*
* Read-write spinlocks, allowing multiple readers but only one writer.
*
* NOTE! it is quite common to have readers in interrupts but no interrupt
* writers. For those circumstances we can "mix" irq-safe locks - any writer
* needs to get a irq-safe write-lock, but readers can get non-irqsafe
* read-locks.
*/
static inline void __raw_read_lock(raw_rwlock_t *rw)
{
__raw_spin_lock(&rw->lock);
atomic_inc(&rw->counter);
__raw_spin_unlock(&rw->lock);
}
static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
__raw_spin_lock(&rw->lock);
atomic_dec(&rw->counter);
__raw_spin_unlock(&rw->lock);
}
static inline void __raw_write_lock(raw_rwlock_t *rw)
{
__raw_spin_lock(&rw->lock);
atomic_set(&rw->counter, -1);
}
static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
atomic_set(&rw->counter, 0);
__raw_spin_unlock(&rw->lock);
}
static inline int __raw_read_trylock(raw_rwlock_t *lock)
{
atomic_t *count = (atomic_t*)lock;
if (atomic_dec_return(count) >= 0)
return 1;
atomic_inc(count);
return 0;
}
static inline int __raw_write_trylock(raw_rwlock_t *rw)
{
if (atomic_sub_and_test(RW_LOCK_BIAS, &rw->counter))
return 1;
atomic_add(RW_LOCK_BIAS, &rw->counter);
return 0;
}
#define _raw_spin_relax(lock) cpu_relax()
#define _raw_read_relax(lock) cpu_relax()
#define _raw_write_relax(lock) cpu_relax()
#endif /* __ASM_SH_SPINLOCK_H */
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