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   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2003, 06, 07 by Ralf Baechle (ralf@linux-mips.org)
   7  */
   8 #ifndef __ASM_CMPXCHG_H
   9 #define __ASM_CMPXCHG_H
  10
  11 #include <linux/irqflags.h>
  12
  13 #define __HAVE_ARCH_CMPXCHG 1
  14
  15 #define __cmpxchg_asm(ld, st, m, old, new)                              \
  16 ({                                                                      \
  17         __typeof(*(m)) __ret;                                           \
  18                                                                         \
  19         if (cpu_has_llsc && R10000_LLSC_WAR) {                          \
  20                 __asm__ __volatile__(                                   \
  21                 "       .set    push                            \n"     \
  22                 "       .set    noat                            \n"     \
  23                 "       .set    mips3                           \n"     \
  24                 "1:     " ld "  %0, %2          # __cmpxchg_asm \n"     \
  25                 "       bne     %0, %z3, 2f                     \n"     \
  26                 "       .set    mips0                           \n"     \
  27                 "       move    $1, %z4                         \n"     \
  28                 "       .set    mips3                           \n"     \
  29                 "       " st "  $1, %1                          \n"     \
  30                 "       beqzl   $1, 1b                          \n"     \
  31                 "2:                                             \n"     \
  32                 "       .set    pop                             \n"     \
  33                 : "=&r" (__ret), "=R" (*m)                              \
  34                 : "R" (*m), "Jr" (old), "Jr" (new)                      \
  35                 : "memory");                                            \
  36         } else if (cpu_has_llsc) {                                      \
  37                 __asm__ __volatile__(                                   \
  38                 "       .set    push                            \n"     \
  39                 "       .set    noat                            \n"     \
  40                 "       .set    mips3                           \n"     \
  41                 "1:     " ld "  %0, %2          # __cmpxchg_asm \n"     \
  42                 "       bne     %0, %z3, 2f                     \n"     \
  43                 "       .set    mips0                           \n"     \
  44                 "       move    $1, %z4                         \n"     \
  45                 "       .set    mips3                           \n"     \
  46                 "       " st "  $1, %1                          \n"     \
  47                 "       beqz    $1, 3f                          \n"     \
  48                 "2:                                             \n"     \
  49                 "       .subsection 2                           \n"     \
  50                 "3:     b       1b                              \n"     \
  51                 "       .previous                               \n"     \
  52                 "       .set    pop                             \n"     \
  53                 : "=&r" (__ret), "=R" (*m)                              \
  54                 : "R" (*m), "Jr" (old), "Jr" (new)                      \
  55                 : "memory");                                            \
  56         } else {                                                        \
  57                 unsigned long __flags;                                  \
  58                                                                         \
  59                 raw_local_irq_save(__flags);                            \
  60                 __ret = *m;                                             \
  61                 if (__ret == old)                                       \
  62                         *m = new;                                       \
  63                 raw_local_irq_restore(__flags);                         \
  64         }                                                               \
  65                                                                         \
  66         __ret;                                                          \
  67 })
  68
  69 /*
  70  * This function doesn't exist, so you'll get a linker error
  71  * if something tries to do an invalid cmpxchg().
  72  */
  73 extern void __cmpxchg_called_with_bad_pointer(void);
  74
  75 #define __cmpxchg(ptr,old,new,barrier)                                  \
  76 ({                                                                      \
  77         __typeof__(ptr) __ptr = (ptr);                                  \
  78         __typeof__(*(ptr)) __old = (old);                               \
  79         __typeof__(*(ptr)) __new = (new);                               \
  80         __typeof__(*(ptr)) __res = 0;                                   \
  81                                                                         \
  82         barrier;                                                        \
  83                                                                         \
  84         switch (sizeof(*(__ptr))) {                                     \
  85         case 4:                                                         \
  86                 __res = __cmpxchg_asm("ll", "sc", __ptr, __old, __new); \
  87                 break;                                                  \
  88         case 8:                                                         \
  89                 if (sizeof(long) == 8) {                                \
  90                         __res = __cmpxchg_asm("lld", "scd", __ptr,      \
  91                                            __old, __new);               \
  92                         break;                                          \
  93                 }                                                       \
  94         default:                                                        \
  95                 __cmpxchg_called_with_bad_pointer();                    \
  96                 break;                                                  \
  97         }                                                               \
  98                                                                         \
  99         barrier;                                                        \
 100                                                                         \
 101         __res;                                                          \
 102 })
 103
 104 #define cmpxchg(ptr, old, new)          __cmpxchg(ptr, old, new, smp_llsc_mb())
 105 #define cmpxchg_local(ptr, old, new)    __cmpxchg(ptr, old, new,)
 106
 107 #endif /* __ASM_CMPXCHG_H */