Subversion Repositories or1k

#ifndef _ASM_PARISC_ATOMIC_H_
#define _ASM_PARISC_ATOMIC_H_
 
#include <linux/config.h>
#include <asm/system.h>
 
/* Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>.  */
 
/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 *
 * And probably incredibly slow on parisc.  OTOH, we don't
 * have to write any serious assembly.   prumpf
 */
#ifdef CONFIG_SMP
#include <asm/spinlock_t.h>
 
/* Use an array of spinlocks for our atomic_ts.
** Hash function to index into a different SPINLOCK.
** Since "a" is usually an address, ">>8" makes one spinlock per 64-bytes.
*/
#  define ATOMIC_HASH_SIZE 4
#  define ATOMIC_HASH(a) (&__atomic_hash[(((unsigned long) a)>>8)&(ATOMIC_HASH_SIZE-1)])
 
extern spinlock_t __atomic_hash[ATOMIC_HASH_SIZE];
 
/* copied from <asm/spinlock.h> and modified.
 * No CONFIG_DEBUG_SPINLOCK support.
 *
 * XXX REVISIT these could be renamed and moved to spinlock_t.h as well
 */
#define SPIN_LOCK(x)	do { while(__ldcw(&(x)->lock) == 0); } while(0)
#define SPIN_UNLOCK(x)  do { (x)->lock = 1; } while(0)
 
#else	/* CONFIG_SMP */
 
#define ATOMIC_HASH_SIZE 1
#define ATOMIC_HASH(a)	(0)
 
#define SPIN_LOCK(x) (void)(x)
#define SPIN_UNLOCK(x) do { } while(0)
 
#endif	/* CONFIG_SMP */
 
/* copied from <linux/spinlock.h> and modified */
#define SPIN_LOCK_IRQSAVE(lock, flags)	do { \
	local_irq_save(flags); 	SPIN_LOCK(lock); \
} while (0)
 
#define SPIN_UNLOCK_IRQRESTORE(lock, flags) do { \
	SPIN_UNLOCK(lock);  local_irq_restore(flags); \
} while (0)
 
/* Note that we need not lock read accesses - aligned word writes/reads
 * are atomic, so a reader never sees unconsistent values.
 *
 * Cache-line alignment would conflict with, for example, linux/module.h
 */
 
typedef struct {
	volatile int counter;
} atomic_t;
 
 
/* This should get optimized out since it's never called.
** Or get a link error if xchg is used "wrong".
*/
extern void __xchg_called_with_bad_pointer(void);
 
/* __xchg32/64 defined in arch/parisc/lib/bitops.c */
extern unsigned long __xchg8(char, char *);
extern unsigned long __xchg32(int, int *);
#ifdef __LP64__
extern unsigned long __xchg64(unsigned long, unsigned long *);
#endif
 
/* optimizer better get rid of switch since size is a constant */
static __inline__ unsigned long __xchg(unsigned long x, __volatile__ void * ptr,
                                       int size)
{
 
	switch(size) {
#ifdef __LP64__
	case 8: return __xchg64(x,(unsigned long *) ptr);
#endif
	case 4: return __xchg32((int) x, (int *) ptr);
	case 1: return __xchg8((char) x, (char *) ptr);
	}
	__xchg_called_with_bad_pointer();
	return x;
}
 
 
/*
** REVISIT - Abandoned use of LDCW in xchg() for now:
** o need to test sizeof(*ptr) to avoid clearing adjacent bytes
** o and while we are at it, could 64-bit code use LDCD too?
**
**	if (__builtin_constant_p(x) && (x == NULL))
**		if (((unsigned long)p & 0xf) == 0)
**			return __ldcw(p);
*/
#define xchg(ptr,x) \
	((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
 
 
#define __HAVE_ARCH_CMPXCHG	1
 
/* bug catcher for when unsupported size is used - won't link */
extern void __cmpxchg_called_with_bad_pointer(void);
 
/* __cmpxchg_u32/u64 defined in arch/parisc/lib/bitops.c */
extern unsigned long __cmpxchg_u32(volatile unsigned int *m, unsigned int old, unsigned int new_);
extern unsigned long __cmpxchg_u64(volatile unsigned long *ptr, unsigned long old, unsigned long new_);
 
/* don't worry...optimizer will get rid of most of this */
static __inline__ unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
{
	switch(size) {
#ifdef __LP64__
	case 8: return __cmpxchg_u64((unsigned long *)ptr, old, new_);
#endif
	case 4: return __cmpxchg_u32((unsigned int *)ptr, (unsigned int) old, (unsigned int) new_);
	}
	__cmpxchg_called_with_bad_pointer();
	return old;
}
 
#define cmpxchg(ptr,o,n)						 \
  ({									 \
     __typeof__(*(ptr)) _o_ = (o);					 \
     __typeof__(*(ptr)) _n_ = (n);					 \
     (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,		 \
				    (unsigned long)_n_, sizeof(*(ptr))); \
  })
 
 
 
/* It's possible to reduce all atomic operations to either
 * __atomic_add_return, __atomic_set and __atomic_ret (the latter
 * is there only for consistency). */
 
static __inline__ int __atomic_add_return(int i, atomic_t *v)
{
	int ret;
	unsigned long flags;
	SPIN_LOCK_IRQSAVE(ATOMIC_HASH(v), flags);
 
	ret = (v->counter += i);
 
	SPIN_UNLOCK_IRQRESTORE(ATOMIC_HASH(v), flags);
	return ret;
}
 
static __inline__ void __atomic_set(atomic_t *v, int i) 
{
	unsigned long flags;
	SPIN_LOCK_IRQSAVE(ATOMIC_HASH(v), flags);
 
	v->counter = i;
 
	SPIN_UNLOCK_IRQRESTORE(ATOMIC_HASH(v), flags);
}
 
static __inline__ int __atomic_read(atomic_t *v)
{
	return v->counter;
}
 
/* exported interface */
 
#define atomic_add(i,v)		((void)(__atomic_add_return( (i),(v))))
#define atomic_sub(i,v)		((void)(__atomic_add_return(-(i),(v))))
#define atomic_inc(v)		((void)(__atomic_add_return(   1,(v))))
#define atomic_dec(v)		((void)(__atomic_add_return(  -1,(v))))
 
#define atomic_add_return(i,v)	(__atomic_add_return( (i),(v)))
#define atomic_sub_return(i,v)	(__atomic_add_return(-(i),(v)))
#define atomic_inc_return(v)	(__atomic_add_return(   1,(v)))
#define atomic_dec_return(v)	(__atomic_add_return(  -1,(v)))
 
#define atomic_dec_and_test(v)	(atomic_dec_return(v) == 0)
 
#define atomic_set(v,i)		(__atomic_set((v),i))
#define atomic_read(v)		(__atomic_read(v))
 
#define ATOMIC_INIT(i)	{ (i) }
 
#define smp_mb__before_atomic_dec()	smp_mb()
#define smp_mb__after_atomic_dec()	smp_mb()
#define smp_mb__before_atomic_inc()	smp_mb()
#define smp_mb__after_atomic_inc()	smp_mb()
 
#endif