LXR linux/include/asm-mn10300/atomic.h

   1/* MN10300 Atomic counter operations
   2 *
   3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public Licence
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the Licence, or (at your option) any later version.
  10 */
  11#ifndef _ASM_ATOMIC_H
  12#define _ASM_ATOMIC_H
  13
  14#ifdef CONFIG_SMP
  15#error not SMP safe
  16#endif
  17
  18/*
  19 * Atomic operations that C can't guarantee us.  Useful for
  20 * resource counting etc..
  21 */
  22
  23/*
  24 * Make sure gcc doesn't try to be clever and move things around
  25 * on us. We need to use _exactly_ the address the user gave us,
  26 * not some alias that contains the same information.
  27 */
  28typedef struct {
  29        int     counter;
  30} atomic_t;
  31
  32#define ATOMIC_INIT(i)  { (i) }
  33
  34#ifdef __KERNEL__
  35
  36/**
  37 * atomic_read - read atomic variable
  38 * @v: pointer of type atomic_t
  39 *
  40 * Atomically reads the value of @v.  Note that the guaranteed
  41 * useful range of an atomic_t is only 24 bits.
  42 */
  43#define atomic_read(v)  ((v)->counter)
  44
  45/**
  46 * atomic_set - set atomic variable
  47 * @v: pointer of type atomic_t
  48 * @i: required value
  49 *
  50 * Atomically sets the value of @v to @i.  Note that the guaranteed
  51 * useful range of an atomic_t is only 24 bits.
  52 */
  53#define atomic_set(v, i) (((v)->counter) = (i))
  54
  55#include <asm/system.h>
  56
  57/**
  58 * atomic_add_return - add integer to atomic variable
  59 * @i: integer value to add
  60 * @v: pointer of type atomic_t
  61 *
  62 * Atomically adds @i to @v and returns the result
  63 * Note that the guaranteed useful range of an atomic_t is only 24 bits.
  64 */
  65static inline int atomic_add_return(int i, atomic_t *v)
  66{
  67        unsigned long flags;
  68        int temp;
  69
  70        local_irq_save(flags);
  71        temp = v->counter;
  72        temp += i;
  73        v->counter = temp;
  74        local_irq_restore(flags);
  75
  76        return temp;
  77}
  78
  79/**
  80 * atomic_sub_return - subtract integer from atomic variable
  81 * @i: integer value to subtract
  82 * @v: pointer of type atomic_t
  83 *
  84 * Atomically subtracts @i from @v and returns the result
  85 * Note that the guaranteed useful range of an atomic_t is only 24 bits.
  86 */
  87static inline int atomic_sub_return(int i, atomic_t *v)
  88{
  89        unsigned long flags;
  90        int temp;
  91
  92        local_irq_save(flags);
  93        temp = v->counter;
  94        temp -= i;
  95        v->counter = temp;
  96        local_irq_restore(flags);
  97
  98        return temp;
  99}
 100
 101static inline int atomic_add_negative(int i, atomic_t *v)
 102{
 103        return atomic_add_return(i, v) < 0;
 104}
 105
 106static inline void atomic_add(int i, atomic_t *v)
 107{
 108        atomic_add_return(i, v);
 109}
 110
 111static inline void atomic_sub(int i, atomic_t *v)
 112{
 113        atomic_sub_return(i, v);
 114}
 115
 116static inline void atomic_inc(atomic_t *v)
 117{
 118        atomic_add_return(1, v);
 119}
 120
 121static inline void atomic_dec(atomic_t *v)
 122{
 123        atomic_sub_return(1, v);
 124}
 125
 126#define atomic_dec_return(v)            atomic_sub_return(1, (v))
 127#define atomic_inc_return(v)            atomic_add_return(1, (v))
 128
 129#define atomic_sub_and_test(i, v)       (atomic_sub_return((i), (v)) == 0)
 130#define atomic_dec_and_test(v)          (atomic_sub_return(1, (v)) == 0)
 131#define atomic_inc_and_test(v)          (atomic_add_return(1, (v)) == 0)
 132
 133#define atomic_add_unless(v, a, u)                              \
 134({                                                              \
 135        int c, old;                                             \
 136        c = atomic_read(v);                                     \
 137        while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
 138                c = old;                                        \
 139        c != (u);                                               \
 140})
 141
 142#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
 143
 144static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
 145{
 146        unsigned long flags;
 147
 148        mask = ~mask;
 149        local_irq_save(flags);
 150        *addr &= mask;
 151        local_irq_restore(flags);
 152}
 153
 154#define atomic_xchg(ptr, v)             (xchg(&(ptr)->counter, (v)))
 155#define atomic_cmpxchg(v, old, new)     (cmpxchg(&((v)->counter), (old), (new)))
 156
 157/* Atomic operations are already serializing on MN10300??? */
 158#define smp_mb__before_atomic_dec()     barrier()
 159#define smp_mb__after_atomic_dec()      barrier()
 160#define smp_mb__before_atomic_inc()     barrier()
 161#define smp_mb__after_atomic_inc()      barrier()
 162
 163#include <asm-generic/atomic.h>
 164
 165#endif /* __KERNEL__ */
 166#endif /* _ASM_ATOMIC_H */
 167