xref: /openbmc/linux/arch/parisc/include/asm/cmpxchg.h (revision 2cf1c348)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * forked from parisc asm/atomic.h which was:
4  *	Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>
5  *	Copyright (C) 2006 Kyle McMartin <kyle@parisc-linux.org>
6  */
7 
8 #ifndef _ASM_PARISC_CMPXCHG_H_
9 #define _ASM_PARISC_CMPXCHG_H_
10 
11 /* This should get optimized out since it's never called.
12 ** Or get a link error if xchg is used "wrong".
13 */
14 extern void __xchg_called_with_bad_pointer(void);
15 
16 /* __xchg32/64 defined in arch/parisc/lib/bitops.c */
17 extern unsigned long __xchg8(char, volatile char *);
18 extern unsigned long __xchg32(int, volatile int *);
19 #ifdef CONFIG_64BIT
20 extern unsigned long __xchg64(unsigned long, volatile unsigned long *);
21 #endif
22 
23 /* optimizer better get rid of switch since size is a constant */
24 static inline unsigned long
25 __xchg(unsigned long x, volatile void *ptr, int size)
26 {
27 	switch (size) {
28 #ifdef CONFIG_64BIT
29 	case 8: return __xchg64(x, (volatile unsigned long *) ptr);
30 #endif
31 	case 4: return __xchg32((int) x, (volatile int *) ptr);
32 	case 1: return __xchg8((char) x, (volatile char *) ptr);
33 	}
34 	__xchg_called_with_bad_pointer();
35 	return x;
36 }
37 
38 /*
39 ** REVISIT - Abandoned use of LDCW in xchg() for now:
40 ** o need to test sizeof(*ptr) to avoid clearing adjacent bytes
41 ** o and while we are at it, could CONFIG_64BIT code use LDCD too?
42 **
43 **	if (__builtin_constant_p(x) && (x == NULL))
44 **		if (((unsigned long)p & 0xf) == 0)
45 **			return __ldcw(p);
46 */
47 #define arch_xchg(ptr, x)						\
48 ({									\
49 	__typeof__(*(ptr)) __ret;					\
50 	__typeof__(*(ptr)) _x_ = (x);					\
51 	__ret = (__typeof__(*(ptr)))					\
52 		__xchg((unsigned long)_x_, (ptr), sizeof(*(ptr)));	\
53 	__ret;								\
54 })
55 
56 /* bug catcher for when unsupported size is used - won't link */
57 extern void __cmpxchg_called_with_bad_pointer(void);
58 
59 /* __cmpxchg_u32/u64 defined in arch/parisc/lib/bitops.c */
60 extern unsigned long __cmpxchg_u32(volatile unsigned int *m, unsigned int old,
61 				   unsigned int new_);
62 extern u64 __cmpxchg_u64(volatile u64 *ptr, u64 old, u64 new_);
63 extern u8 __cmpxchg_u8(volatile u8 *ptr, u8 old, u8 new_);
64 
65 /* don't worry...optimizer will get rid of most of this */
66 static inline unsigned long
67 __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
68 {
69 	switch (size) {
70 #ifdef CONFIG_64BIT
71 	case 8: return __cmpxchg_u64((u64 *)ptr, old, new_);
72 #endif
73 	case 4: return __cmpxchg_u32((unsigned int *)ptr,
74 				     (unsigned int)old, (unsigned int)new_);
75 	case 1: return __cmpxchg_u8((u8 *)ptr, old & 0xff, new_ & 0xff);
76 	}
77 	__cmpxchg_called_with_bad_pointer();
78 	return old;
79 }
80 
81 #define arch_cmpxchg(ptr, o, n)						 \
82 ({									 \
83 	__typeof__(*(ptr)) _o_ = (o);					 \
84 	__typeof__(*(ptr)) _n_ = (n);					 \
85 	(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,	 \
86 				    (unsigned long)_n_, sizeof(*(ptr))); \
87 })
88 
89 #include <asm-generic/cmpxchg-local.h>
90 
91 static inline unsigned long __cmpxchg_local(volatile void *ptr,
92 				      unsigned long old,
93 				      unsigned long new_, int size)
94 {
95 	switch (size) {
96 #ifdef CONFIG_64BIT
97 	case 8:	return __cmpxchg_u64((u64 *)ptr, old, new_);
98 #endif
99 	case 4:	return __cmpxchg_u32(ptr, old, new_);
100 	default:
101 		return __generic_cmpxchg_local(ptr, old, new_, size);
102 	}
103 }
104 
105 /*
106  * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
107  * them available.
108  */
109 #define arch_cmpxchg_local(ptr, o, n)					\
110 	((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o),	\
111 			(unsigned long)(n), sizeof(*(ptr))))
112 #ifdef CONFIG_64BIT
113 #define arch_cmpxchg64_local(ptr, o, n)					\
114 ({									\
115 	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
116 	cmpxchg_local((ptr), (o), (n));					\
117 })
118 #else
119 #define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
120 #endif
121 
122 #define arch_cmpxchg64(ptr, o, n) __cmpxchg_u64(ptr, o, n)
123 
124 #endif /* _ASM_PARISC_CMPXCHG_H_ */
125