include/asm-generic/atomic.h

   1 /*
   2  * Generic C implementation of atomic counter operations
   3  * Originally implemented for MN10300.
   4  *
   5  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   6  * Written by David Howells (dhowells@redhat.com)
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public Licence
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the Licence, or (at your option) any later version.
  12  */
  13 #ifndef __ASM_GENERIC_ATOMIC_H
  14 #define __ASM_GENERIC_ATOMIC_H
  15
  16 #ifdef CONFIG_SMP
  17 #error not SMP safe
  18 #endif
  19
  20 /*
  21  * Atomic operations that C can't guarantee us.  Useful for
  22  * resource counting etc..
  23  */
  24
  25 #define ATOMIC_INIT(i)  { (i) }
  26
  27 #ifdef __KERNEL__
  28
  29 /**
  30  * atomic_read - read atomic variable
  31  * @v: pointer of type atomic_t
  32  *
  33  * Atomically reads the value of @v.  Note that the guaranteed
  34  * useful range of an atomic_t is only 24 bits.
  35  */
  36 #define atomic_read(v)  ((v)->counter)
  37
  38 /**
  39  * atomic_set - set atomic variable
  40  * @v: pointer of type atomic_t
  41  * @i: required value
  42  *
  43  * Atomically sets the value of @v to @i.  Note that the guaranteed
  44  * useful range of an atomic_t is only 24 bits.
  45  */
  46 #define atomic_set(v, i) (((v)->counter) = (i))
  47
  48 #include <asm/system.h>
  49
  50 /**
  51  * atomic_add_return - add integer to atomic variable
  52  * @i: integer value to add
  53  * @v: pointer of type atomic_t
  54  *
  55  * Atomically adds @i to @v and returns the result
  56  * Note that the guaranteed useful range of an atomic_t is only 24 bits.
  57  */
  58 static inline int atomic_add_return(int i, atomic_t *v)
  59 {
  60         unsigned long flags;
  61         int temp;
  62
  63         local_irq_save(flags);
  64         temp = v->counter;
  65         temp += i;
  66         v->counter = temp;
  67         local_irq_restore(flags);
  68
  69         return temp;
  70 }
  71
  72 /**
  73  * atomic_sub_return - subtract integer from atomic variable
  74  * @i: integer value to subtract
  75  * @v: pointer of type atomic_t
  76  *
  77  * Atomically subtracts @i from @v and returns the result
  78  * Note that the guaranteed useful range of an atomic_t is only 24 bits.
  79  */
  80 static inline int atomic_sub_return(int i, atomic_t *v)
  81 {
  82         unsigned long flags;
  83         int temp;
  84
  85         local_irq_save(flags);
  86         temp = v->counter;
  87         temp -= i;
  88         v->counter = temp;
  89         local_irq_restore(flags);
  90
  91         return temp;
  92 }
  93
  94 static inline int atomic_add_negative(int i, atomic_t *v)
  95 {
  96         return atomic_add_return(i, v) < 0;
  97 }
  98
  99 static inline void atomic_add(int i, atomic_t *v)
 100 {
 101         atomic_add_return(i, v);
 102 }
 103
 104 static inline void atomic_sub(int i, atomic_t *v)
 105 {
 106         atomic_sub_return(i, v);
 107 }
 108
 109 static inline void atomic_inc(atomic_t *v)
 110 {
 111         atomic_add_return(1, v);
 112 }
 113
 114 static inline void atomic_dec(atomic_t *v)
 115 {
 116         atomic_sub_return(1, v);
 117 }
 118
 119 #define atomic_dec_return(v)            atomic_sub_return(1, (v))
 120 #define atomic_inc_return(v)            atomic_add_return(1, (v))
 121
 122 #define atomic_sub_and_test(i, v)       (atomic_sub_return((i), (v)) == 0)
 123 #define atomic_dec_and_test(v)          (atomic_sub_return(1, (v)) == 0)
 124 #define atomic_inc_and_test(v)          (atomic_add_return(1, (v)) == 0)
 125
 126 #define atomic_add_unless(v, a, u)                              \
 127 ({                                                              \
 128         int c, old;                                             \
 129         c = atomic_read(v);                                     \
 130         while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
 131                 c = old;                                        \
 132         c != (u);                                               \
 133 })
 134
 135 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
 136
 137 static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
 138 {
 139         unsigned long flags;
 140
 141         mask = ~mask;
 142         local_irq_save(flags);
 143         *addr &= mask;
 144         local_irq_restore(flags);
 145 }
 146
 147 #define atomic_xchg(ptr, v)             (xchg(&(ptr)->counter, (v)))
 148 #define atomic_cmpxchg(v, old, new)     (cmpxchg(&((v)->counter), (old), (new)))
 149
 150 #define cmpxchg_local(ptr, o, n)                                               \
 151         ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
 152                         (unsigned long)(n), sizeof(*(ptr))))
 153
 154 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
 155
 156 /* Assume that atomic operations are already serializing */
 157 #define smp_mb__before_atomic_dec()     barrier()
 158 #define smp_mb__after_atomic_dec()      barrier()
 159 #define smp_mb__before_atomic_inc()     barrier()
 160 #define smp_mb__after_atomic_inc()      barrier()
 161
 162 #include <asm-generic/atomic-long.h>
 163
 164 #endif /* __KERNEL__ */
 165 #endif /* __ASM_GENERIC_ATOMIC_H */