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#ifndef __ASM_ARCH_SPINLOCK_H
#define __ASM_ARCH_SPINLOCK_H
#include <asm/system.h>
#define RW_LOCK_BIAS 0x01000000
#define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 }
#define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
#define spin_is_locked(x) (*(volatile signed char *)(&(x)->lock) <= 0)
#define spin_unlock_wait(x) do { barrier(); } while(spin_is_locked(x))
extern void cris_spin_unlock(void *l, int val);
extern void cris_spin_lock(void *l);
extern int cris_spin_trylock(void* l);
static inline void _raw_spin_unlock(spinlock_t *lock)
{
__asm__ volatile ("move.d %1,%0" \
: "=m" (lock->lock) \
: "r" (1) \
: "memory");
}
static inline int _raw_spin_trylock(spinlock_t *lock)
{
return cris_spin_trylock((void*)&lock->lock);
}
static inline void _raw_spin_lock(spinlock_t *lock)
{
cris_spin_lock((void*)&lock->lock);
}
static inline void _raw_spin_lock_flags (spinlock_t *lock, unsigned long flags)
{
_raw_spin_lock(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.
*/
typedef struct {
spinlock_t lock;
volatile int counter;
#ifdef CONFIG_PREEMPT
unsigned int break_lock;
#endif
} rwlock_t;
#define RW_LOCK_UNLOCKED (rwlock_t) { {1}, 0 }
#define rwlock_init(lp) do { *(lp) = RW_LOCK_UNLOCKED; } while (0)
/**
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
#define read_can_lock(x) ((int)(x)->counter >= 0)
/**
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
#define write_can_lock(x) ((x)->counter == 0)
#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
/* read_lock, read_unlock are pretty straightforward. Of course it somehow
* sucks we end up saving/restoring flags twice for read_lock_irqsave aso. */
static __inline__ void _raw_read_lock(rwlock_t *rw)
{
unsigned long flags;
local_irq_save(flags);
_raw_spin_lock(&rw->lock);
rw->counter++;
_raw_spin_unlock(&rw->lock);
local_irq_restore(flags);
}
static __inline__ void _raw_read_unlock(rwlock_t *rw)
{
unsigned long flags;
local_irq_save(flags);
_raw_spin_lock(&rw->lock);
rw->counter--;
_raw_spin_unlock(&rw->lock);
local_irq_restore(flags);
}
/* write_lock is less trivial. We optimistically grab the lock and check
* if we surprised any readers. If so we release the lock and wait till
* they're all gone before trying again
*
* Also note that we don't use the _irqsave / _irqrestore suffixes here.
* If we're called with interrupts enabled and we've got readers (or other
* writers) in interrupt handlers someone fucked up and we'd dead-lock
* sooner or later anyway. prumpf */
static __inline__ void _raw_write_lock(rwlock_t *rw)
{
retry:
_raw_spin_lock(&rw->lock);
if(rw->counter != 0) {
/* this basically never happens */
_raw_spin_unlock(&rw->lock);
while(rw->counter != 0);
goto retry;
}
/* got it. now leave without unlocking */
rw->counter = -1; /* remember we are locked */
}
/* write_unlock is absolutely trivial - we don't have to wait for anything */
static __inline__ void _raw_write_unlock(rwlock_t *rw)
{
rw->counter = 0;
_raw_spin_unlock(&rw->lock);
}
static __inline__ int _raw_write_trylock(rwlock_t *rw)
{
_raw_spin_lock(&rw->lock);
if (rw->counter != 0) {
/* this basically never happens */
_raw_spin_unlock(&rw->lock);
return 0;
}
/* got it. now leave without unlocking */
rw->counter = -1; /* remember we are locked */
return 1;
}
static __inline__ int is_read_locked(rwlock_t *rw)
{
return rw->counter > 0;
}
static __inline__ int is_write_locked(rwlock_t *rw)
{
return rw->counter < 0;
}
#endif /* __ASM_ARCH_SPINLOCK_H */
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