2 * arch/arm/include/asm/atomic.h
4 * Copyright (C) 1996 Russell King.
5 * Copyright (C) 2002 Deep Blue Solutions Ltd.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 #ifndef __ASM_ARM_ATOMIC_H
12 #define __ASM_ARM_ATOMIC_H
14 #include <linux/compiler.h>
15 #include <linux/types.h>
16 #include <asm/system.h>
18 #define ATOMIC_INIT(i) { (i) }
23 * On ARM, ordinary assignment (str instruction) doesn't clear the local
24 * strex/ldrex monitor on some implementations. The reason we can use it for
25 * atomic_set() is the clrex or dummy strex done on every exception return.
27 #define atomic_read(v) ((v)->counter)
28 #define atomic_set(v,i) (((v)->counter) = (i))
30 #if __LINUX_ARM_ARCH__ >= 6
33 * ARMv6 UP and SMP safe atomic ops. We use load exclusive and
34 * store exclusive to ensure that these are atomic. We may loop
35 * to ensure that the update happens.
37 static inline void atomic_add(int i, atomic_t *v)
42 __asm__ __volatile__("@ atomic_add\n"
45 " strex %1, %0, [%2]\n"
48 : "=&r" (result), "=&r" (tmp)
49 : "r" (&v->counter), "Ir" (i)
53 static inline int atomic_add_return(int i, atomic_t *v)
60 __asm__ __volatile__("@ atomic_add_return\n"
63 " strex %1, %0, [%2]\n"
66 : "=&r" (result), "=&r" (tmp)
67 : "r" (&v->counter), "Ir" (i)
75 static inline void atomic_sub(int i, atomic_t *v)
80 __asm__ __volatile__("@ atomic_sub\n"
83 " strex %1, %0, [%2]\n"
86 : "=&r" (result), "=&r" (tmp)
87 : "r" (&v->counter), "Ir" (i)
91 static inline int atomic_sub_return(int i, atomic_t *v)
98 __asm__ __volatile__("@ atomic_sub_return\n"
101 " strex %1, %0, [%2]\n"
104 : "=&r" (result), "=&r" (tmp)
105 : "r" (&v->counter), "Ir" (i)
113 static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
115 unsigned long oldval, res;
120 __asm__ __volatile__("@ atomic_cmpxchg\n"
124 "strexeq %0, %4, [%2]\n"
125 : "=&r" (res), "=&r" (oldval)
126 : "r" (&ptr->counter), "Ir" (old), "r" (new)
135 static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
137 unsigned long tmp, tmp2;
139 __asm__ __volatile__("@ atomic_clear_mask\n"
140 "1: ldrex %0, [%2]\n"
142 " strex %1, %0, [%2]\n"
145 : "=&r" (tmp), "=&r" (tmp2)
146 : "r" (addr), "Ir" (mask)
150 #else /* ARM_ARCH_6 */
153 #error SMP not supported on pre-ARMv6 CPUs
156 static inline int atomic_add_return(int i, atomic_t *v)
161 raw_local_irq_save(flags);
163 v->counter = val += i;
164 raw_local_irq_restore(flags);
168 #define atomic_add(i, v) (void) atomic_add_return(i, v)
170 static inline int atomic_sub_return(int i, atomic_t *v)
175 raw_local_irq_save(flags);
177 v->counter = val -= i;
178 raw_local_irq_restore(flags);
182 #define atomic_sub(i, v) (void) atomic_sub_return(i, v)
184 static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
189 raw_local_irq_save(flags);
191 if (likely(ret == old))
193 raw_local_irq_restore(flags);
198 static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
202 raw_local_irq_save(flags);
204 raw_local_irq_restore(flags);
207 #endif /* __LINUX_ARM_ARCH__ */
209 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
211 static inline int atomic_add_unless(atomic_t *v, int a, int u)
216 while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c)
220 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
222 #define atomic_inc(v) atomic_add(1, v)
223 #define atomic_dec(v) atomic_sub(1, v)
225 #define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0)
226 #define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0)
227 #define atomic_inc_return(v) (atomic_add_return(1, v))
228 #define atomic_dec_return(v) (atomic_sub_return(1, v))
229 #define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
231 #define atomic_add_negative(i,v) (atomic_add_return(i, v) < 0)
233 #define smp_mb__before_atomic_dec() smp_mb()
234 #define smp_mb__after_atomic_dec() smp_mb()
235 #define smp_mb__before_atomic_inc() smp_mb()
236 #define smp_mb__after_atomic_inc() smp_mb()
238 #include <asm-generic/atomic-long.h>