2 * Atomic operations that C can't guarantee us. Useful for
3 * resource counting etc.
5 * But use these as seldom as possible since they are slower than
8 * Copyright (C) 2004-2006 Atmel Corporation
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.
14 #ifndef __ASM_AVR32_ATOMIC_H
15 #define __ASM_AVR32_ATOMIC_H
17 #include <linux/types.h>
18 #include <asm/system.h>
20 #define ATOMIC_INIT(i) { (i) }
22 #define atomic_read(v) (*(volatile int *)&(v)->counter)
23 #define atomic_set(v, i) (((v)->counter) = i)
26 * atomic_sub_return - subtract the atomic variable
27 * @i: integer value to subtract
28 * @v: pointer of type atomic_t
30 * Atomically subtracts @i from @v. Returns the resulting value.
32 static inline int atomic_sub_return(int i, atomic_t *v)
37 "/* atomic_sub_return */\n"
43 : "=&r"(result), "=o"(v->counter)
44 : "m"(v->counter), "rKs21"(i)
51 * atomic_add_return - add integer to atomic variable
52 * @i: integer value to add
53 * @v: pointer of type atomic_t
55 * Atomically adds @i to @v. Returns the resulting value.
57 static inline int atomic_add_return(int i, atomic_t *v)
61 if (__builtin_constant_p(i) && (i >= -1048575) && (i <= 1048576))
62 result = atomic_sub_return(-i, v);
65 "/* atomic_add_return */\n"
71 : "=&r"(result), "=o"(v->counter)
72 : "m"(v->counter), "r"(i)
79 * atomic_sub_unless - sub unless the number is a given value
80 * @v: pointer of type atomic_t
81 * @a: the amount to subtract from v...
82 * @u: ...unless v is equal to u.
84 * Atomically subtract @a from @v, so long as it was not @u.
85 * Returns the old value of @v.
87 static inline void atomic_sub_unless(atomic_t *v, int a, int u)
92 "/* atomic_sub_unless */\n"
101 : "=&r"(tmp), "=o"(v->counter)
102 : "m"(v->counter), "rKs21"(a), "rKs21"(u)
107 * __atomic_add_unless - add unless the number is a given value
108 * @v: pointer of type atomic_t
109 * @a: the amount to add to v...
110 * @u: ...unless v is equal to u.
112 * Atomically adds @a to @v, so long as it was not @u.
113 * Returns the old value of @v.
115 static inline int __atomic_add_unless(atomic_t *v, int a, int u)
117 int tmp, old = atomic_read(v);
119 if (__builtin_constant_p(a) && (a >= -1048575) && (a <= 1048576))
120 atomic_sub_unless(v, -a, u);
123 "/* __atomic_add_unless */\n"
132 : "=&r"(tmp), "=o"(v->counter)
133 : "m"(v->counter), "r"(a), "ir"(u)
141 * atomic_sub_if_positive - conditionally subtract integer from atomic variable
142 * @i: integer value to subtract
143 * @v: pointer of type atomic_t
145 * Atomically test @v and subtract @i if @v is greater or equal than @i.
146 * The function returns the old value of @v minus @i.
148 static inline int atomic_sub_if_positive(int i, atomic_t *v)
153 "/* atomic_sub_if_positive */\n"
161 : "=&r"(result), "=o"(v->counter)
162 : "m"(v->counter), "ir"(i)
168 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
169 #define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
171 #define atomic_sub(i, v) (void)atomic_sub_return(i, v)
172 #define atomic_add(i, v) (void)atomic_add_return(i, v)
173 #define atomic_dec(v) atomic_sub(1, (v))
174 #define atomic_inc(v) atomic_add(1, (v))
176 #define atomic_dec_return(v) atomic_sub_return(1, v)
177 #define atomic_inc_return(v) atomic_add_return(1, v)
179 #define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
180 #define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0)
181 #define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0)
182 #define atomic_add_negative(i, v) (atomic_add_return(i, v) < 0)
184 #define atomic_dec_if_positive(v) atomic_sub_if_positive(1, v)
186 #define smp_mb__before_atomic_dec() barrier()
187 #define smp_mb__after_atomic_dec() barrier()
188 #define smp_mb__before_atomic_inc() barrier()
189 #define smp_mb__after_atomic_inc() barrier()
191 #endif /* __ASM_AVR32_ATOMIC_H */