LXR linux/include/asm-arm26/atomic.h

   1/*
   2 *  linux/include/asm-arm26/atomic.h
   3 *
   4 *  Copyright (c) 1996 Russell King.
   5 *  Modified for arm26 by Ian Molton
   6 *
   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.
  10 *
  11 *  Changelog:
  12 *   25-11-2004 IM      Updated for 2.6.9
  13 *   27-06-1996 RMK     Created
  14 *   13-04-1997 RMK     Made functions atomic!
  15 *   07-12-1997 RMK     Upgraded for v2.1.
  16 *   26-08-1998 PJB     Added #ifdef __KERNEL__
  17 *
  18 *  FIXME - its probably worth seeing what these compile into...
  19 */
  20#ifndef __ASM_ARM_ATOMIC_H
  21#define __ASM_ARM_ATOMIC_H
  22
  23
  24#ifdef CONFIG_SMP
  25#error SMP is NOT supported
  26#endif
  27
  28typedef struct { volatile int counter; } atomic_t;
  29
  30#define ATOMIC_INIT(i)  { (i) }
  31
  32#ifdef __KERNEL__
  33#include <asm/system.h>
  34
  35#define atomic_read(v) ((v)->counter)
  36#define atomic_set(v,i) (((v)->counter) = (i))
  37
  38static inline int atomic_add_return(int i, atomic_t *v)
  39{
  40        unsigned long flags;
  41        int val;
  42
  43        local_irq_save(flags);
  44        val = v->counter;
  45        v->counter = val += i;
  46        local_irq_restore(flags);
  47
  48        return val;
  49}
  50
  51static inline int atomic_sub_return(int i, atomic_t *v)
  52{
  53        unsigned long flags;
  54        int val;
  55
  56        local_irq_save(flags);
  57        val = v->counter;
  58        v->counter = val -= i;
  59        local_irq_restore(flags);
  60
  61        return val;
  62}
  63
  64static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
  65{
  66        int ret;
  67        unsigned long flags;
  68
  69        local_irq_save(flags);
  70        ret = v->counter;
  71        if (likely(ret == old))
  72                v->counter = new;
  73        local_irq_restore(flags);
  74
  75        return ret;
  76}
  77
  78#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
  79
  80static inline int atomic_add_unless(atomic_t *v, int a, int u)
  81{
  82        int ret;
  83        unsigned long flags;
  84
  85        local_irq_save(flags);
  86        ret = v->counter;
  87        if (ret != u)
  88                v->counter += a;
  89        local_irq_restore(flags);
  90
  91        return ret != u;
  92}
  93#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
  94
  95static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
  96{
  97        unsigned long flags;
  98
  99        local_irq_save(flags);
 100        *addr &= ~mask;
 101        local_irq_restore(flags);
 102}
 103
 104#define atomic_add(i, v)        (void) atomic_add_return(i, v)
 105#define atomic_inc(v)           (void) atomic_add_return(1, v)
 106#define atomic_sub(i, v)        (void) atomic_sub_return(i, v)
 107#define atomic_dec(v)           (void) atomic_sub_return(1, v)
 108
 109#define atomic_inc_and_test(v)  (atomic_add_return(1, v) == 0)
 110#define atomic_dec_and_test(v)  (atomic_sub_return(1, v) == 0)
 111#define atomic_inc_return(v)    (atomic_add_return(1, v))
 112#define atomic_dec_return(v)    (atomic_sub_return(1, v))
 113
 114#define atomic_add_negative(i,v) (atomic_add_return(i, v) < 0)
 115
 116/* Atomic operations are already serializing on ARM26 */
 117#define smp_mb__before_atomic_dec()     barrier()
 118#define smp_mb__after_atomic_dec()      barrier()
 119#define smp_mb__before_atomic_inc()     barrier()
 120#define smp_mb__after_atomic_inc()      barrier()
 121
 122#include <asm-generic/atomic.h>
 123#endif
 124#endif
 125