1/* 32-bit atomic xchg() and cmpxchg() definitions.
2 *
3 * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
4 * Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com.au)
5 * Copyright (C) 2007 Kyle McMartin (kyle@parisc-linux.org)
6 *
7 * Additions by Keith M Wesolowski (wesolows@foobazco.org) based
8 * on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>.
9 */
10
11#ifndef __ARCH_SPARC_CMPXCHG__
12#define __ARCH_SPARC_CMPXCHG__
13
14unsigned long __xchg_u32(volatile u32 *m, u32 new);
15void __xchg_called_with_bad_pointer(void);
16
17static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr, int size)
18{
19	switch (size) {
20	case 4:
21		return __xchg_u32(ptr, x);
22	}
23	__xchg_called_with_bad_pointer();
24	return x;
25}
26
27#define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
28
29/* Emulate cmpxchg() the same way we emulate atomics,
30 * by hashing the object address and indexing into an array
31 * of spinlocks to get a bit of performance...
32 *
33 * See arch/sparc/lib/atomic32.c for implementation.
34 *
35 * Cribbed from <asm-parisc/atomic.h>
36 */
37#define __HAVE_ARCH_CMPXCHG	1
38
39/* bug catcher for when unsupported size is used - won't link */
40void __cmpxchg_called_with_bad_pointer(void);
41/* we only need to support cmpxchg of a u32 on sparc */
42unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
43
44/* don't worry...optimizer will get rid of most of this */
45static inline unsigned long
46__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
47{
48	switch (size) {
49	case 4:
50		return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
51	default:
52		__cmpxchg_called_with_bad_pointer();
53		break;
54	}
55	return old;
56}
57
58#define cmpxchg(ptr, o, n)						\
59({									\
60	__typeof__(*(ptr)) _o_ = (o);					\
61	__typeof__(*(ptr)) _n_ = (n);					\
62	(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,	\
63			(unsigned long)_n_, sizeof(*(ptr)));		\
64})
65
66#include <asm-generic/cmpxchg-local.h>
67
68/*
69 * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
70 * them available.
71 */
72#define cmpxchg_local(ptr, o, n)				  	       \
73	((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
74			(unsigned long)(n), sizeof(*(ptr))))
75#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
76
77#endif /* __ARCH_SPARC_CMPXCHG__ */
78