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Arnd Bergmann3f7e2122009-05-13 22:56:35 +00001/*
Arun Sharmaacac43e2011-07-26 16:09:08 -07002 * Generic C implementation of atomic counter operations. Usable on
3 * UP systems only. Do not include in machine independent code.
4 *
Arnd Bergmann3f7e2122009-05-13 22:56:35 +00005 * 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
18#ifdef CONFIG_SMP
19#error not SMP safe
20#endif
21
22/*
23 * Atomic operations that C can't guarantee us. Useful for
24 * resource counting etc..
25 */
26
27#define ATOMIC_INIT(i) { (i) }
28
29#ifdef __KERNEL__
30
31/**
32 * atomic_read - read atomic variable
33 * @v: pointer of type atomic_t
34 *
Peter Fritzsche37682172010-05-24 14:33:09 -070035 * Atomically reads the value of @v.
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000036 */
Anton Blanchardf3d46f92010-05-17 14:33:53 +100037#define atomic_read(v) (*(volatile int *)&(v)->counter)
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000038
39/**
40 * atomic_set - set atomic variable
41 * @v: pointer of type atomic_t
42 * @i: required value
43 *
Peter Fritzsche37682172010-05-24 14:33:09 -070044 * Atomically sets the value of @v to @i.
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000045 */
46#define atomic_set(v, i) (((v)->counter) = (i))
47
David Howellsdf9ee292010-10-07 14:08:55 +010048#include <linux/irqflags.h>
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000049#include <asm/system.h>
50
51/**
52 * atomic_add_return - add integer to atomic variable
53 * @i: integer value to add
54 * @v: pointer of type atomic_t
55 *
56 * Atomically adds @i to @v and returns the result
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000057 */
58static inline int atomic_add_return(int i, atomic_t *v)
59{
60 unsigned long flags;
61 int temp;
62
David Howellsdf9ee292010-10-07 14:08:55 +010063 raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000064 temp = v->counter;
65 temp += i;
66 v->counter = temp;
Michal Simek9e581432010-08-09 17:18:24 -070067 raw_local_irq_restore(flags);
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000068
69 return temp;
70}
71
72/**
73 * atomic_sub_return - subtract integer from atomic variable
74 * @i: integer value to subtract
75 * @v: pointer of type atomic_t
76 *
77 * Atomically subtracts @i from @v and returns the result
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000078 */
79static inline int atomic_sub_return(int i, atomic_t *v)
80{
81 unsigned long flags;
82 int temp;
83
David Howellsdf9ee292010-10-07 14:08:55 +010084 raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000085 temp = v->counter;
86 temp -= i;
87 v->counter = temp;
Michal Simek9e581432010-08-09 17:18:24 -070088 raw_local_irq_restore(flags);
Arnd Bergmann3f7e2122009-05-13 22:56:35 +000089
90 return temp;
91}
92
93static inline int atomic_add_negative(int i, atomic_t *v)
94{
95 return atomic_add_return(i, v) < 0;
96}
97
98static inline void atomic_add(int i, atomic_t *v)
99{
100 atomic_add_return(i, v);
101}
102
103static inline void atomic_sub(int i, atomic_t *v)
104{
105 atomic_sub_return(i, v);
106}
107
108static inline void atomic_inc(atomic_t *v)
109{
110 atomic_add_return(1, v);
111}
112
113static inline void atomic_dec(atomic_t *v)
114{
115 atomic_sub_return(1, v);
116}
117
118#define atomic_dec_return(v) atomic_sub_return(1, (v))
119#define atomic_inc_return(v) atomic_add_return(1, (v))
120
121#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
Mike Frysinger3eea44e2011-07-26 16:09:09 -0700122#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
123#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
Arnd Bergmann3f7e2122009-05-13 22:56:35 +0000124
Mathieu Lacage8b9d4062010-06-27 12:26:06 +0200125#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
126#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
127
128#define cmpxchg_local(ptr, o, n) \
129 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
130 (unsigned long)(n), sizeof(*(ptr))))
131
132#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
133
Arun Sharmaf24219b2011-07-26 16:09:07 -0700134static inline int __atomic_add_unless(atomic_t *v, int a, int u)
Mathieu Lacage8b9d4062010-06-27 12:26:06 +0200135{
136 int c, old;
137 c = atomic_read(v);
138 while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
139 c = old;
Arun Sharmaf24219b2011-07-26 16:09:07 -0700140 return c;
Mathieu Lacage8b9d4062010-06-27 12:26:06 +0200141}
Arnd Bergmann3f7e2122009-05-13 22:56:35 +0000142
Mike Frysingerf6081bd2011-07-26 16:09:10 -0700143/**
144 * atomic_clear_mask - Atomically clear bits in atomic variable
145 * @mask: Mask of the bits to be cleared
146 * @v: pointer of type atomic_t
147 *
148 * Atomically clears the bits set in @mask from @v
149 */
150static inline void atomic_clear_mask(unsigned long mask, atomic_t *v)
Arnd Bergmann3f7e2122009-05-13 22:56:35 +0000151{
152 unsigned long flags;
153
154 mask = ~mask;
Michal Simek9e581432010-08-09 17:18:24 -0700155 raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
Mike Frysingerf6081bd2011-07-26 16:09:10 -0700156 v->counter &= mask;
Michal Simek9e581432010-08-09 17:18:24 -0700157 raw_local_irq_restore(flags);
Arnd Bergmann3f7e2122009-05-13 22:56:35 +0000158}
159
Mike Frysinger00b3c282011-07-26 16:09:10 -0700160/**
161 * atomic_set_mask - Atomically set bits in atomic variable
162 * @mask: Mask of the bits to be set
163 * @v: pointer of type atomic_t
164 *
165 * Atomically sets the bits set in @mask in @v
166 */
167static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
168{
169 unsigned long flags;
170
171 raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
172 v->counter |= mask;
173 raw_local_irq_restore(flags);
174}
175
Arnd Bergmann3f7e2122009-05-13 22:56:35 +0000176/* Assume that atomic operations are already serializing */
177#define smp_mb__before_atomic_dec() barrier()
178#define smp_mb__after_atomic_dec() barrier()
179#define smp_mb__before_atomic_inc() barrier()
180#define smp_mb__after_atomic_inc() barrier()
181
Arnd Bergmann3f7e2122009-05-13 22:56:35 +0000182#endif /* __KERNEL__ */
183#endif /* __ASM_GENERIC_ATOMIC_H */