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1/*
2 * Atomic operations that C can't guarantee us. Useful for
3 * resource counting etc.
4 *
5 * But use these as seldom as possible since they are slower than
6 * regular operations.
7 *
8 * Copyright (C) 2004-2006 Atmel Corporation
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14#ifndef __ASM_AVR32_ATOMIC_H
15#define __ASM_AVR32_ATOMIC_H
16
17#include <asm/system.h>
18
19typedef struct { volatile int counter; } atomic_t;
20#define ATOMIC_INIT(i) { (i) }
21
22#define atomic_read(v) ((v)->counter)
23#define atomic_set(v, i) (((v)->counter) = i)
24
25/*
26 * atomic_sub_return - subtract the atomic variable
27 * @i: integer value to subtract
28 * @v: pointer of type atomic_t
29 *
30 * Atomically subtracts @i from @v. Returns the resulting value.
31 */
32static inline int atomic_sub_return(int i, atomic_t *v)
33{
34 int result;
35
36 asm volatile(
37 "/* atomic_sub_return */\n"
38 "1: ssrf 5\n"
39 " ld.w %0, %2\n"
40 " sub %0, %3\n"
41 " stcond %1, %0\n"
42 " brne 1b"
43 : "=&r"(result), "=o"(v->counter)
44 : "m"(v->counter), "rKs21"(i)
45 : "cc");
46
47 return result;
48}
49
50/*
51 * atomic_add_return - add integer to atomic variable
52 * @i: integer value to add
53 * @v: pointer of type atomic_t
54 *
55 * Atomically adds @i to @v. Returns the resulting value.
56 */
57static inline int atomic_add_return(int i, atomic_t *v)
58{
59 int result;
60
61 if (__builtin_constant_p(i) && (i >= -1048575) && (i <= 1048576))
62 result = atomic_sub_return(-i, v);
63 else
64 asm volatile(
65 "/* atomic_add_return */\n"
66 "1: ssrf 5\n"
67 " ld.w %0, %1\n"
68 " add %0, %3\n"
69 " stcond %2, %0\n"
70 " brne 1b"
71 : "=&r"(result), "=o"(v->counter)
72 : "m"(v->counter), "r"(i)
73 : "cc", "memory");
74
75 return result;
76}
77
78/*
79 * atomic_sub_unless - sub unless the number is a given value
80 * @v: pointer of type atomic_t
81 * @a: the amount to add to v...
82 * @u: ...unless v is equal to u.
83 *
84 * If the atomic value v is not equal to u, this function subtracts a
85 * from v, and returns non zero. If v is equal to u then it returns
86 * zero. This is done as an atomic operation.
87*/
88static inline int atomic_sub_unless(atomic_t *v, int a, int u)
89{
90 int tmp, result = 0;
91
92 asm volatile(
93 "/* atomic_sub_unless */\n"
94 "1: ssrf 5\n"
95 " ld.w %0, %3\n"
96 " cp.w %0, %5\n"
97 " breq 1f\n"
98 " sub %0, %4\n"
99 " stcond %2, %0\n"
100 " brne 1b\n"
101 " mov %1, 1\n"
102 "1:"
103 : "=&r"(tmp), "=&r"(result), "=o"(v->counter)
104 : "m"(v->counter), "rKs21"(a), "rKs21"(u)
105 : "cc", "memory");
106
107 return result;
108}
109
110/*
111 * atomic_add_unless - add unless the number is a given value
112 * @v: pointer of type atomic_t
113 * @a: the amount to add to v...
114 * @u: ...unless v is equal to u.
115 *
116 * If the atomic value v is not equal to u, this function adds a to v,
117 * and returns non zero. If v is equal to u then it returns zero. This
118 * is done as an atomic operation.
119*/
120static inline int atomic_add_unless(atomic_t *v, int a, int u)
121{
122 int tmp, result;
123
124 if (__builtin_constant_p(a) && (a >= -1048575) && (a <= 1048576))
125 result = atomic_sub_unless(v, -a, u);
126 else {
127 result = 0;
128 asm volatile(
129 "/* atomic_add_unless */\n"
130 "1: ssrf 5\n"
131 " ld.w %0, %3\n"
132 " cp.w %0, %5\n"
133 " breq 1f\n"
134 " add %0, %4\n"
135 " stcond %2, %0\n"
136 " brne 1b\n"
137 " mov %1, 1\n"
138 "1:"
139 : "=&r"(tmp), "=&r"(result), "=o"(v->counter)
140 : "m"(v->counter), "r"(a), "ir"(u)
141 : "cc", "memory");
142 }
143
144 return result;
145}
146
147/*
148 * atomic_sub_if_positive - conditionally subtract integer from atomic variable
149 * @i: integer value to subtract
150 * @v: pointer of type atomic_t
151 *
152 * Atomically test @v and subtract @i if @v is greater or equal than @i.
153 * The function returns the old value of @v minus @i.
154 */
155static inline int atomic_sub_if_positive(int i, atomic_t *v)
156{
157 int result;
158
159 asm volatile(
160 "/* atomic_sub_if_positive */\n"
161 "1: ssrf 5\n"
162 " ld.w %0, %2\n"
163 " sub %0, %3\n"
164 " brlt 1f\n"
165 " stcond %1, %0\n"
166 " brne 1b\n"
167 "1:"
168 : "=&r"(result), "=o"(v->counter)
169 : "m"(v->counter), "ir"(i)
170 : "cc", "memory");
171
172 return result;
173}
174
175#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
176#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
177
178#define atomic_sub(i, v) (void)atomic_sub_return(i, v)
179#define atomic_add(i, v) (void)atomic_add_return(i, v)
180#define atomic_dec(v) atomic_sub(1, (v))
181#define atomic_inc(v) atomic_add(1, (v))
182
183#define atomic_dec_return(v) atomic_sub_return(1, v)
184#define atomic_inc_return(v) atomic_add_return(1, v)
185
186#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
187#define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0)
188#define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0)
189#define atomic_add_negative(i, v) (atomic_add_return(i, v) < 0)
190
191#define atomic_inc_not_zero(v) atomic_add_unless(v, 1, 0)
192#define atomic_dec_if_positive(v) atomic_sub_if_positive(1, v)
193
194#define smp_mb__before_atomic_dec() barrier()
195#define smp_mb__after_atomic_dec() barrier()
196#define smp_mb__before_atomic_inc() barrier()
197#define smp_mb__after_atomic_inc() barrier()
198
199#include <asm-generic/atomic.h>
200
201#endif /* __ASM_AVR32_ATOMIC_H */