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3f7e212d 1/*
acac43e2
AS
2 * Generic C implementation of atomic counter operations. Usable on
3 * UP systems only. Do not include in machine independent code.
4 *
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5 * Originally implemented for MN10300.
6 *
7 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
8 * Written by David Howells (dhowells@redhat.com)
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public Licence
12 * as published by the Free Software Foundation; either version
13 * 2 of the Licence, or (at your option) any later version.
14 */
15#ifndef __ASM_GENERIC_ATOMIC_H
16#define __ASM_GENERIC_ATOMIC_H
17
34484277 18#include <asm/cmpxchg.h>
febdbfe8 19#include <asm/barrier.h>
34484277 20
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21/*
22 * atomic_$op() - $op integer to atomic variable
23 * @i: integer value to $op
24 * @v: pointer to the atomic variable
25 *
26 * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use
27 * smp_mb__{before,after}_atomic().
28 */
29
30/*
31 * atomic_$op_return() - $op interer to atomic variable and returns the result
32 * @i: integer value to $op
33 * @v: pointer to the atomic variable
34 *
35 * Atomically $ops @i to @v. Does imply a full memory barrier.
36 */
37
3f7e212d 38#ifdef CONFIG_SMP
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39
40/* we can build all atomic primitives from cmpxchg */
41
42#define ATOMIC_OP(op, c_op) \
43static inline void atomic_##op(int i, atomic_t *v) \
44{ \
45 int c, old; \
46 \
47 c = v->counter; \
48 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
49 c = old; \
50}
51
52#define ATOMIC_OP_RETURN(op, c_op) \
53static inline int atomic_##op##_return(int i, atomic_t *v) \
54{ \
55 int c, old; \
56 \
57 c = v->counter; \
58 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
59 c = old; \
60 \
61 return c c_op i; \
62}
63
64#else
65
66#include <linux/irqflags.h>
67
68#define ATOMIC_OP(op, c_op) \
69static inline void atomic_##op(int i, atomic_t *v) \
70{ \
71 unsigned long flags; \
72 \
73 raw_local_irq_save(flags); \
74 v->counter = v->counter c_op i; \
75 raw_local_irq_restore(flags); \
76}
77
78#define ATOMIC_OP_RETURN(op, c_op) \
79static inline int atomic_##op##_return(int i, atomic_t *v) \
80{ \
81 unsigned long flags; \
82 int ret; \
83 \
84 raw_local_irq_save(flags); \
85 ret = (v->counter = v->counter c_op i); \
86 raw_local_irq_restore(flags); \
87 \
88 return ret; \
89}
90
91#endif /* CONFIG_SMP */
92
93#ifndef atomic_add_return
94ATOMIC_OP_RETURN(add, +)
95#endif
96
97#ifndef atomic_sub_return
98ATOMIC_OP_RETURN(sub, -)
99#endif
100
101#ifndef atomic_clear_mask
102ATOMIC_OP(and, &)
103#define atomic_clear_mask(i, v) atomic_and(~(i), (v))
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104#endif
105
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106#ifndef atomic_set_mask
107#define CONFIG_ARCH_HAS_ATOMIC_OR
108ATOMIC_OP(or, |)
109#define atomic_set_mask(i, v) atomic_or((i), (v))
110#endif
111
112#undef ATOMIC_OP_RETURN
113#undef ATOMIC_OP
114
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115/*
116 * Atomic operations that C can't guarantee us. Useful for
117 * resource counting etc..
118 */
119
120#define ATOMIC_INIT(i) { (i) }
121
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122/**
123 * atomic_read - read atomic variable
124 * @v: pointer of type atomic_t
125 *
37682177 126 * Atomically reads the value of @v.
3f7e212d 127 */
7505cb60 128#ifndef atomic_read
2291059c 129#define atomic_read(v) ACCESS_ONCE((v)->counter)
7505cb60 130#endif
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131
132/**
133 * atomic_set - set atomic variable
134 * @v: pointer of type atomic_t
135 * @i: required value
136 *
37682177 137 * Atomically sets the value of @v to @i.
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138 */
139#define atomic_set(v, i) (((v)->counter) = (i))
140
df9ee292 141#include <linux/irqflags.h>
3f7e212d 142
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143static inline int atomic_add_negative(int i, atomic_t *v)
144{
145 return atomic_add_return(i, v) < 0;
146}
147
148static inline void atomic_add(int i, atomic_t *v)
149{
150 atomic_add_return(i, v);
151}
152
153static inline void atomic_sub(int i, atomic_t *v)
154{
155 atomic_sub_return(i, v);
156}
157
158static inline void atomic_inc(atomic_t *v)
159{
160 atomic_add_return(1, v);
161}
162
163static inline void atomic_dec(atomic_t *v)
164{
165 atomic_sub_return(1, v);
166}
167
168#define atomic_dec_return(v) atomic_sub_return(1, (v))
169#define atomic_inc_return(v) atomic_add_return(1, (v))
170
171#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
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172#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
173#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
3f7e212d 174
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175#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
176#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
177
f24219b4 178static inline int __atomic_add_unless(atomic_t *v, int a, int u)
8b9d4069 179{
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180 int c, old;
181 c = atomic_read(v);
182 while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
183 c = old;
184 return c;
3f7e212d 185}
00b3c28b 186
3f7e212d 187#endif /* __ASM_GENERIC_ATOMIC_H */