arch/sparc/include/asm/cmpxchg_32.h

   1 /* 32-bit atomic xchg() and cmpxchg() definitions.
   2  *
   3  * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
   4  * Copyright (C) 2000 Anton Blanchard (anton@linuxcare.com.au)
   5  * Copyright (C) 2007 Kyle McMartin (kyle@parisc-linux.org)
   6  *
   7  * Additions by Keith M Wesolowski (wesolows@foobazco.org) based
   8  * on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>.
   9  */
  10
  11 #ifndef __ARCH_SPARC_CMPXCHG__
  12 #define __ARCH_SPARC_CMPXCHG__
  13
  14 static inline unsigned long xchg_u32(__volatile__ unsigned long *m, unsigned long val)
  15 {
  16         __asm__ __volatile__("swap [%2], %0"
  17                              : "=&r" (val)
  18                              : "0" (val), "r" (m)
  19                              : "memory");
  20         return val;
  21 }
  22
  23 extern void __xchg_called_with_bad_pointer(void);
  24
  25 static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr, int size)
  26 {
  27         switch (size) {
  28         case 4:
  29                 return xchg_u32(ptr, x);
  30         }
  31         __xchg_called_with_bad_pointer();
  32         return x;
  33 }
  34
  35 #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
  36
  37 /* Emulate cmpxchg() the same way we emulate atomics,
  38  * by hashing the object address and indexing into an array
  39  * of spinlocks to get a bit of performance...
  40  *
  41  * See arch/sparc/lib/atomic32.c for implementation.
  42  *
  43  * Cribbed from <asm-parisc/atomic.h>
  44  */
  45 #define __HAVE_ARCH_CMPXCHG     1
  46
  47 /* bug catcher for when unsupported size is used - won't link */
  48 extern void __cmpxchg_called_with_bad_pointer(void);
  49 /* we only need to support cmpxchg of a u32 on sparc */
  50 extern unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
  51
  52 /* don't worry...optimizer will get rid of most of this */
  53 static inline unsigned long
  54 __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
  55 {
  56         switch (size) {
  57         case 4:
  58                 return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
  59         default:
  60                 __cmpxchg_called_with_bad_pointer();
  61                 break;
  62         }
  63         return old;
  64 }
  65
  66 #define cmpxchg(ptr, o, n)                                              \
  67 ({                                                                      \
  68         __typeof__(*(ptr)) _o_ = (o);                                   \
  69         __typeof__(*(ptr)) _n_ = (n);                                   \
  70         (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,       \
  71                         (unsigned long)_n_, sizeof(*(ptr)));            \
  72 })
  73
  74 #include <asm-generic/cmpxchg-local.h>
  75
  76 /*
  77  * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
  78  * them available.
  79  */
  80 #define cmpxchg_local(ptr, o, n)                                               \
  81         ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
  82                         (unsigned long)(n), sizeof(*(ptr))))
  83 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
  84
  85 #endif /* __ARCH_SPARC_CMPXCHG__ */