diff options
Diffstat (limited to 'include/asm-generic/atomic.h')
| -rw-r--r-- | include/asm-generic/atomic.h | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h new file mode 100644 index 00000000..1ced6413 --- /dev/null +++ b/include/asm-generic/atomic.h @@ -0,0 +1,198 @@ +/* + * Generic C implementation of atomic counter operations. Usable on + * UP systems only. Do not include in machine independent code. + * + * Originally implemented for MN10300. + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ +#ifndef __ASM_GENERIC_ATOMIC_H +#define __ASM_GENERIC_ATOMIC_H + +#include <asm/cmpxchg.h> + +#ifdef CONFIG_SMP +/* Force people to define core atomics */ +# if !defined(atomic_add_return) || !defined(atomic_sub_return) || \ + !defined(atomic_clear_mask) || !defined(atomic_set_mask) +# error "SMP requires a little arch-specific magic" +# endif +#endif + +/* + * Atomic operations that C can't guarantee us. Useful for + * resource counting etc.. + */ + +#define ATOMIC_INIT(i) { (i) } + +#ifdef __KERNEL__ + +/** + * atomic_read - read atomic variable + * @v: pointer of type atomic_t + * + * Atomically reads the value of @v. + */ +#ifndef atomic_read +#define atomic_read(v) (*(volatile int *)&(v)->counter) +#endif + +/** + * atomic_set - set atomic variable + * @v: pointer of type atomic_t + * @i: required value + * + * Atomically sets the value of @v to @i. + */ +#define atomic_set(v, i) (((v)->counter) = (i)) + +#include <linux/irqflags.h> + +/** + * atomic_add_return - add integer to atomic variable + * @i: integer value to add + * @v: pointer of type atomic_t + * + * Atomically adds @i to @v and returns the result + */ +#ifndef atomic_add_return +static inline int atomic_add_return(int i, atomic_t *v) +{ + unsigned long flags; + int temp; + + raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ + temp = v->counter; + temp += i; + v->counter = temp; + raw_local_irq_restore(flags); + + return temp; +} +#endif + +/** + * atomic_sub_return - subtract integer from atomic variable + * @i: integer value to subtract + * @v: pointer of type atomic_t + * + * Atomically subtracts @i from @v and returns the result + */ +#ifndef atomic_sub_return +static inline int atomic_sub_return(int i, atomic_t *v) +{ + unsigned long flags; + int temp; + + raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ + temp = v->counter; + temp -= i; + v->counter = temp; + raw_local_irq_restore(flags); + + return temp; +} +#endif + +static inline int atomic_add_negative(int i, atomic_t *v) +{ + return atomic_add_return(i, v) < 0; +} + +static inline void atomic_add(int i, atomic_t *v) +{ + atomic_add_return(i, v); +} + +static inline void atomic_sub(int i, atomic_t *v) +{ + atomic_sub_return(i, v); +} + +static inline void atomic_inc(atomic_t *v) +{ + atomic_add_return(1, v); +} + +static inline void atomic_dec(atomic_t *v) +{ + atomic_sub_return(1, v); +} + +#define atomic_dec_return(v) atomic_sub_return(1, (v)) +#define atomic_inc_return(v) atomic_add_return(1, (v)) + +#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) +#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0) +#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0) + +#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) +#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) + +#define cmpxchg_local(ptr, o, n) \ + ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ + (unsigned long)(n), sizeof(*(ptr)))) + +#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) + +static inline int __atomic_add_unless(atomic_t *v, int a, int u) +{ + int c, old; + c = atomic_read(v); + while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) + c = old; + return c; +} + +/** + * atomic_clear_mask - Atomically clear bits in atomic variable + * @mask: Mask of the bits to be cleared + * @v: pointer of type atomic_t + * + * Atomically clears the bits set in @mask from @v + */ +#ifndef atomic_clear_mask +static inline void atomic_clear_mask(unsigned long mask, atomic_t *v) +{ + unsigned long flags; + + mask = ~mask; + raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ + v->counter &= mask; + raw_local_irq_restore(flags); +} +#endif + +/** + * atomic_set_mask - Atomically set bits in atomic variable + * @mask: Mask of the bits to be set + * @v: pointer of type atomic_t + * + * Atomically sets the bits set in @mask in @v + */ +#ifndef atomic_set_mask +static inline void atomic_set_mask(unsigned int mask, atomic_t *v) +{ + unsigned long flags; + + raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ + v->counter |= mask; + raw_local_irq_restore(flags); +} +#endif + +/* Assume that atomic operations are already serializing */ +#define smp_mb__before_atomic_dec() barrier() +#define smp_mb__after_atomic_dec() barrier() +#define smp_mb__before_atomic_inc() barrier() +#define smp_mb__after_atomic_inc() barrier() + +#endif /* __KERNEL__ */ +#endif /* __ASM_GENERIC_ATOMIC_H */ |