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 unsigned long __xchg_u32(volatile u32 *m, u32 new);
  15 void __xchg_called_with_bad_pointer(void);
  16
  17 static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr, int size)
  18 {
  19         switch (size) {
  20         case 4:
  21                 return __xchg_u32(ptr, x);
  22         }
  23         __xchg_called_with_bad_pointer();
  24         return x;
  25 }
  26
  27 #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
  28
  29 /* Emulate cmpxchg() the same way we emulate atomics,
  30  * by hashing the object address and indexing into an array
  31  * of spinlocks to get a bit of performance...
  32  *
  33  * See arch/sparc/lib/atomic32.c for implementation.
  34  *
  35  * Cribbed from <asm-parisc/atomic.h>
  36  */
  37
  38 /* bug catcher for when unsupported size is used - won't link */
  39 void __cmpxchg_called_with_bad_pointer(void);
  40 /* we only need to support cmpxchg of a u32 on sparc */
  41 unsigned long __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
  42
  43 /* don't worry...optimizer will get rid of most of this */
  44 static inline unsigned long
  45 __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
  46 {
  47         switch (size) {
  48         case 4:
  49                 return __cmpxchg_u32((u32 *)ptr, (u32)old, (u32)new_);
  50         default:
  51                 __cmpxchg_called_with_bad_pointer();
  52                 break;
  53         }
  54         return old;
  55 }
  56
  57 #define cmpxchg(ptr, o, n)                                              \
  58 ({                                                                      \
  59         __typeof__(*(ptr)) _o_ = (o);                                   \
  60         __typeof__(*(ptr)) _n_ = (n);                                   \
  61         (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,       \
  62                         (unsigned long)_n_, sizeof(*(ptr)));            \
  63 })
  64
  65 #include <asm-generic/cmpxchg-local.h>
  66
  67 /*
  68  * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
  69  * them available.
  70  */
  71 #define cmpxchg_local(ptr, o, n)                                               \
  72         ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
  73                         (unsigned long)(n), sizeof(*(ptr))))
  74 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
  75
  76 #endif /* __ARCH_SPARC_CMPXCHG__ */