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#ifndef _PPC_SEMAPHORE_HELPER_H
#define _PPC_SEMAPHORE_HELPER_H
/*
* SMP- and interrupt-safe semaphores..
*
* (C) Copyright 1996 Linus Torvalds
* Adapted for PowerPC by Gary Thomas and Paul Mackerras
*/
#include <asm/atomic.h>
/*
* These two (wake_one_more and waking_non_zero) _must_ execute
* atomically wrt each other.
*
* This is trivially done with load with reservation and
* store conditional on the ppc.
*/
static inline void wake_one_more(struct semaphore * sem)
{
atomic_inc(&sem->waking);
}
static inline int waking_non_zero(struct semaphore *sem)
{
int ret, tmp;
/* Atomic decrement sem->waking iff it is > 0 */
__asm__ __volatile__(
"1: lwarx %1,0,%2\n" /* tmp = sem->waking */
" cmpwi 0,%1,0\n" /* test tmp */
" addic %1,%1,-1\n" /* --tmp */
" ble- 2f\n" /* exit if tmp was <= 0 */
" stwcx. %1,0,%2\n" /* update sem->waking */
" bne- 1b\n" /* try again if update failed*/
" li %0,1\n" /* ret = 1 */
"2:"
: "=r" (ret), "=&r" (tmp)
: "r" (&sem->waking), "0" (0)
: "cr0", "memory");
return ret;
}
/*
* waking_non_zero_interruptible:
* 1 got the lock
* 0 go to sleep
* -EINTR interrupted
*/
static inline int waking_non_zero_interruptible(struct semaphore *sem,
struct task_struct *tsk)
{
int ret, tmp;
/* Atomic decrement sem->waking iff it is > 0 */
__asm__ __volatile__(
"1: lwarx %1,0,%2\n" /* tmp = sem->waking */
" cmpwi 0,%1,0\n" /* test tmp */
" addic %1,%1,-1\n" /* --tmp */
" ble- 2f\n" /* exit if tmp was <= 0 */
" stwcx. %1,0,%2\n" /* update sem->waking */
" bne- 1b\n" /* try again if update failed*/
" li %0,1\n" /* ret = 1 */
"2:"
: "=r" (ret), "=&r" (tmp)
: "r" (&sem->waking), "0" (0)
: "cr0", "memory");
if (ret == 0 && signal_pending(tsk)) {
atomic_inc(&sem->count);
ret = -EINTR;
}
return ret;
}
/*
* waking_non_zero_trylock:
* 1 failed to lock
* 0 got the lock
*/
static inline int waking_non_zero_trylock(struct semaphore *sem)
{
int ret, tmp;
/* Atomic decrement sem->waking iff it is > 0 */
__asm__ __volatile__(
"1: lwarx %1,0,%2\n" /* tmp = sem->waking */
" cmpwi 0,%1,0\n" /* test tmp */
" addic %1,%1,-1\n" /* --tmp */
" ble- 2f\n" /* exit if tmp was <= 0 */
" stwcx. %1,0,%2\n" /* update sem->waking */
" bne- 1b\n" /* try again if update failed*/
" li %0,0\n" /* ret = 0 */
"2:"
: "=r" (ret), "=&r" (tmp)
: "r" (&sem->waking), "0" (1)
: "cr0", "memory");
if (ret)
atomic_inc(&sem->count);
return ret;
}
#endif /* _PPC_SEMAPHORE_HELPER_H */
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