1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _TOOLS_LINUX_ASM_X86_ATOMIC_H
3#define _TOOLS_LINUX_ASM_X86_ATOMIC_H
4
5#include <linux/compiler.h>
6#include <linux/types.h>
7#include "rmwcc.h"
8
9#define LOCK_PREFIX "\n\tlock; "
10
11#include <asm/cmpxchg.h>
12
13/*
14 * Atomic operations that C can't guarantee us.  Useful for
15 * resource counting etc..
16 */
17
18#define ATOMIC_INIT(i)	{ (i) }
19
20/**
21 * atomic_read - read atomic variable
22 * @v: pointer of type atomic_t
23 *
24 * Atomically reads the value of @v.
25 */
26static inline int atomic_read(const atomic_t *v)
27{
28	return READ_ONCE((v)->counter);
29}
30
31/**
32 * atomic_set - set atomic variable
33 * @v: pointer of type atomic_t
34 * @i: required value
35 *
36 * Atomically sets the value of @v to @i.
37 */
38static inline void atomic_set(atomic_t *v, int i)
39{
40	v->counter = i;
41}
42
43/**
44 * atomic_inc - increment atomic variable
45 * @v: pointer of type atomic_t
46 *
47 * Atomically increments @v by 1.
48 */
49static inline void atomic_inc(atomic_t *v)
50{
51	asm volatile(LOCK_PREFIX "incl %0"
52		     : "+m" (v->counter));
53}
54
55/**
56 * atomic_dec_and_test - decrement and test
57 * @v: pointer of type atomic_t
58 *
59 * Atomically decrements @v by 1 and
60 * returns true if the result is 0, or false for all other
61 * cases.
62 */
63static inline int atomic_dec_and_test(atomic_t *v)
64{
65	GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
66}
67
68static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
69{
70	return cmpxchg(&v->counter, old, new);
71}
72
73#endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */
74