arch/metag/include/asm/atomic_lock1.h

   1 #ifndef __ASM_METAG_ATOMIC_LOCK1_H
   2 #define __ASM_METAG_ATOMIC_LOCK1_H
   3
   4 #define ATOMIC_INIT(i)  { (i) }
   5
   6 #include <linux/compiler.h>
   7
   8 #include <asm/barrier.h>
   9 #include <asm/global_lock.h>
  10
  11 static inline int atomic_read(const atomic_t *v)
  12 {
  13         return READ_ONCE((v)->counter);
  14 }
  15
  16 /*
  17  * atomic_set needs to be take the lock to protect atomic_add_unless from a
  18  * possible race, as it reads the counter twice:
  19  *
  20  *  CPU0                               CPU1
  21  *  atomic_add_unless(1, 0)
  22  *    ret = v->counter (non-zero)
  23  *    if (ret != u)                    v->counter = 0
  24  *      v->counter += 1 (counter set to 1)
  25  *
  26  * Making atomic_set take the lock ensures that ordering and logical
  27  * consistency is preserved.
  28  */
  29 static inline int atomic_set(atomic_t *v, int i)
  30 {
  31         unsigned long flags;
  32
  33         __global_lock1(flags);
  34         fence();
  35         v->counter = i;
  36         __global_unlock1(flags);
  37         return i;
  38 }
  39
  40 #define ATOMIC_OP(op, c_op)                                             \
  41 static inline void atomic_##op(int i, atomic_t *v)                      \
  42 {                                                                       \
  43         unsigned long flags;                                            \
  44                                                                         \
  45         __global_lock1(flags);                                          \
  46         fence();                                                        \
  47         v->counter c_op i;                                              \
  48         __global_unlock1(flags);                                        \
  49 }                                                                       \
  50
  51 #define ATOMIC_OP_RETURN(op, c_op)                                      \
  52 static inline int atomic_##op##_return(int i, atomic_t *v)              \
  53 {                                                                       \
  54         unsigned long result;                                           \
  55         unsigned long flags;                                            \
  56                                                                         \
  57         __global_lock1(flags);                                          \
  58         result = v->counter;                                            \
  59         result c_op i;                                                  \
  60         fence();                                                        \
  61         v->counter = result;                                            \
  62         __global_unlock1(flags);                                        \
  63                                                                         \
  64         return result;                                                  \
  65 }
  66
  67 #define ATOMIC_OPS(op, c_op) ATOMIC_OP(op, c_op) ATOMIC_OP_RETURN(op, c_op)
  68
  69 ATOMIC_OPS(add, +=)
  70 ATOMIC_OPS(sub, -=)
  71 ATOMIC_OP(and, &=)
  72 ATOMIC_OP(or, |=)
  73 ATOMIC_OP(xor, ^=)
  74
  75 #undef ATOMIC_OPS
  76 #undef ATOMIC_OP_RETURN
  77 #undef ATOMIC_OP
  78
  79 static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
  80 {
  81         int ret;
  82         unsigned long flags;
  83
  84         __global_lock1(flags);
  85         ret = v->counter;
  86         if (ret == old) {
  87                 fence();
  88                 v->counter = new;
  89         }
  90         __global_unlock1(flags);
  91
  92         return ret;
  93 }
  94
  95 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
  96
  97 static inline int __atomic_add_unless(atomic_t *v, int a, int u)
  98 {
  99         int ret;
 100         unsigned long flags;
 101
 102         __global_lock1(flags);
 103         ret = v->counter;
 104         if (ret != u) {
 105                 fence();
 106                 v->counter += a;
 107         }
 108         __global_unlock1(flags);
 109
 110         return ret;
 111 }
 112
 113 static inline int atomic_sub_if_positive(int i, atomic_t *v)
 114 {
 115         int ret;
 116         unsigned long flags;
 117
 118         __global_lock1(flags);
 119         ret = v->counter - 1;
 120         if (ret >= 0) {
 121                 fence();
 122                 v->counter = ret;
 123         }
 124         __global_unlock1(flags);
 125
 126         return ret;
 127 }
 128
 129 #endif /* __ASM_METAG_ATOMIC_LOCK1_H */