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