include/asm-ppc/atomic.h

   1 /*
   2  * PowerPC atomic operations
   3  */
   4
   5 #ifndef _ASM_PPC_ATOMIC_H_
   6 #define _ASM_PPC_ATOMIC_H_
   7
   8 typedef struct { volatile int counter; } atomic_t;
   9
  10 #ifdef __KERNEL__
  11
  12 #define ATOMIC_INIT(i)  { (i) }
  13
  14 #define atomic_read(v)          ((v)->counter)
  15 #define atomic_set(v,i)         (((v)->counter) = (i))
  16
  17 extern void atomic_clear_mask(unsigned long mask, unsigned long *addr);
  18
  19 #ifdef CONFIG_SMP
  20 #define SMP_SYNC        "sync"
  21 #define SMP_ISYNC       "\n\tisync"
  22 #else
  23 #define SMP_SYNC        ""
  24 #define SMP_ISYNC
  25 #endif
  26
  27 /* Erratum #77 on the 405 means we need a sync or dcbt before every stwcx.
  28  * The old ATOMIC_SYNC_FIX covered some but not all of this.
  29  */
  30 #ifdef CONFIG_IBM405_ERR77
  31 #define PPC405_ERR77(ra,rb)     "dcbt " #ra "," #rb ";"
  32 #else
  33 #define PPC405_ERR77(ra,rb)
  34 #endif
  35
  36 static __inline__ void atomic_add(int a, atomic_t *v)
  37 {
  38         int t;
  39
  40         __asm__ __volatile__(
  41 "1:     lwarx   %0,0,%3         # atomic_add\n\
  42         add     %0,%2,%0\n"
  43         PPC405_ERR77(0,%3)
  44 "       stwcx.  %0,0,%3 \n\
  45         bne-    1b"
  46         : "=&r" (t), "=m" (v->counter)
  47         : "r" (a), "r" (&v->counter), "m" (v->counter)
  48         : "cc");
  49 }
  50
  51 static __inline__ int atomic_add_return(int a, atomic_t *v)
  52 {
  53         int t;
  54
  55         __asm__ __volatile__(
  56 "1:     lwarx   %0,0,%2         # atomic_add_return\n\
  57         add     %0,%1,%0\n"
  58         PPC405_ERR77(0,%2)
  59 "       stwcx.  %0,0,%2 \n\
  60         bne-    1b"
  61         SMP_ISYNC
  62         : "=&r" (t)
  63         : "r" (a), "r" (&v->counter)
  64         : "cc", "memory");
  65
  66         return t;
  67 }
  68
  69 #define atomic_add_negative(a, v)       (atomic_add_return((a), (v)) < 0)
  70
  71 static __inline__ void atomic_sub(int a, atomic_t *v)
  72 {
  73         int t;
  74
  75         __asm__ __volatile__(
  76 "1:     lwarx   %0,0,%3         # atomic_sub\n\
  77         subf    %0,%2,%0\n"
  78         PPC405_ERR77(0,%3)
  79 "       stwcx.  %0,0,%3 \n\
  80         bne-    1b"
  81         : "=&r" (t), "=m" (v->counter)
  82         : "r" (a), "r" (&v->counter), "m" (v->counter)
  83         : "cc");
  84 }
  85
  86 static __inline__ int atomic_sub_return(int a, atomic_t *v)
  87 {
  88         int t;
  89
  90         __asm__ __volatile__(
  91 "1:     lwarx   %0,0,%2         # atomic_sub_return\n\
  92         subf    %0,%1,%0\n"
  93         PPC405_ERR77(0,%2)
  94 "       stwcx.  %0,0,%2 \n\
  95         bne-    1b"
  96         SMP_ISYNC
  97         : "=&r" (t)
  98         : "r" (a), "r" (&v->counter)
  99         : "cc", "memory");
 100
 101         return t;
 102 }
 103
 104 static __inline__ void atomic_inc(atomic_t *v)
 105 {
 106         int t;
 107
 108         __asm__ __volatile__(
 109 "1:     lwarx   %0,0,%2         # atomic_inc\n\
 110         addic   %0,%0,1\n"
 111         PPC405_ERR77(0,%2)
 112 "       stwcx.  %0,0,%2 \n\
 113         bne-    1b"
 114         : "=&r" (t), "=m" (v->counter)
 115         : "r" (&v->counter), "m" (v->counter)
 116         : "cc");
 117 }
 118
 119 static __inline__ int atomic_inc_return(atomic_t *v)
 120 {
 121         int t;
 122
 123         __asm__ __volatile__(
 124 "1:     lwarx   %0,0,%1         # atomic_inc_return\n\
 125         addic   %0,%0,1\n"
 126         PPC405_ERR77(0,%1)
 127 "       stwcx.  %0,0,%1 \n\
 128         bne-    1b"
 129         SMP_ISYNC
 130         : "=&r" (t)
 131         : "r" (&v->counter)
 132         : "cc", "memory");
 133
 134         return t;
 135 }
 136
 137 /*
 138  * atomic_inc_and_test - increment and test
 139  * @v: pointer of type atomic_t
 140  *
 141  * Atomically increments @v by 1
 142  * and returns true if the result is zero, or false for all
 143  * other cases.
 144  */
 145 #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
 146
 147 static __inline__ void atomic_dec(atomic_t *v)
 148 {
 149         int t;
 150
 151         __asm__ __volatile__(
 152 "1:     lwarx   %0,0,%2         # atomic_dec\n\
 153         addic   %0,%0,-1\n"
 154         PPC405_ERR77(0,%2)\
 155 "       stwcx.  %0,0,%2\n\
 156         bne-    1b"
 157         : "=&r" (t), "=m" (v->counter)
 158         : "r" (&v->counter), "m" (v->counter)
 159         : "cc");
 160 }
 161
 162 static __inline__ int atomic_dec_return(atomic_t *v)
 163 {
 164         int t;
 165
 166         __asm__ __volatile__(
 167 "1:     lwarx   %0,0,%1         # atomic_dec_return\n\
 168         addic   %0,%0,-1\n"
 169         PPC405_ERR77(0,%1)
 170 "       stwcx.  %0,0,%1\n\
 171         bne-    1b"
 172         SMP_ISYNC
 173         : "=&r" (t)
 174         : "r" (&v->counter)
 175         : "cc", "memory");
 176
 177         return t;
 178 }
 179
 180 #define atomic_sub_and_test(a, v)       (atomic_sub_return((a), (v)) == 0)
 181 #define atomic_dec_and_test(v)          (atomic_dec_return((v)) == 0)
 182
 183 /*
 184  * Atomically test *v and decrement if it is greater than 0.
 185  * The function returns the old value of *v minus 1.
 186  */
 187 static __inline__ int atomic_dec_if_positive(atomic_t *v)
 188 {
 189         int t;
 190
 191         __asm__ __volatile__(
 192 "1:     lwarx   %0,0,%1         # atomic_dec_if_positive\n\
 193         addic.  %0,%0,-1\n\
 194         blt-    2f\n"
 195         PPC405_ERR77(0,%1)
 196 "       stwcx.  %0,0,%1\n\
 197         bne-    1b"
 198         SMP_ISYNC
 199         "\n\
 200 2:"     : "=&r" (t)
 201         : "r" (&v->counter)
 202         : "cc", "memory");
 203
 204         return t;
 205 }
 206
 207 #define __MB    __asm__ __volatile__ (SMP_SYNC : : : "memory")
 208 #define smp_mb__before_atomic_dec()     __MB
 209 #define smp_mb__after_atomic_dec()      __MB
 210 #define smp_mb__before_atomic_inc()     __MB
 211 #define smp_mb__after_atomic_inc()      __MB
 212
 213 #endif /* __KERNEL__ */
 214 #endif /* _ASM_PPC_ATOMIC_H_ */