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#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/spinlock_types.h>
/* Note that PA-RISC has to use `1' to mean unlocked and `0' to mean locked
* since it only has load-and-zero. Moreover, at least on some PA processors,
* the semaphore address has to be 16-byte aligned.
*/
static inline int __raw_spin_is_locked(raw_spinlock_t *x)
{
volatile unsigned int *a = __ldcw_align(x);
return *a == 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))
static inline void __raw_spin_lock(raw_spinlock_t *x)
{
volatile unsigned int *a;
mb();
a = __ldcw_align(x);
while (__ldcw(a) == 0)
while (*a == 0);
mb();
}
static inline void __raw_spin_unlock(raw_spinlock_t *x)
{
volatile unsigned int *a;
mb();
a = __ldcw_align(x);
*a = 1;
mb();
}
static inline int __raw_spin_trylock(raw_spinlock_t *x)
{
volatile unsigned int *a;
int ret;
mb();
a = __ldcw_align(x);
ret = __ldcw(a) != 0;
mb();
return ret;
}
/*
* Read-write spinlocks, allowing multiple readers
* but only one writer.
*/
#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(raw_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(raw_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(raw_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)
cpu_relax();
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(raw_rwlock_t *rw)
{
rw->counter = 0;
__raw_spin_unlock(&rw->lock);
}
static __inline__ int __raw_write_trylock(raw_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 __raw_is_read_locked(raw_rwlock_t *rw)
{
return rw->counter > 0;
}
static __inline__ int __raw_is_write_locked(raw_rwlock_t *rw)
{
return rw->counter < 0;
}
#endif /* __ASM_SPINLOCK_H */
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