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 
14 unsigned long __xchg_u32(volatile u32 *m, u32 new);
15 void __xchg_called_with_bad_pointer(void);
16 
17 static 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 */
40 void __cmpxchg_called_with_bad_pointer(void);
41 /* we only need to support cmpxchg of a u32 on sparc */
42 unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
43 
44 /* don't worry...optimizer will get rid of most of this */
45 static 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