arch/m68k/include/asm/system.h

   1 #ifndef _M68K_SYSTEM_H
   2 #define _M68K_SYSTEM_H
   3
   4 #include <linux/linkage.h>
   5 #include <linux/kernel.h>
   6 #include <linux/irqflags.h>
   7 #include <asm/segment.h>
   8 #include <asm/entry.h>
   9
  10 #ifdef __KERNEL__
  11
  12 /*
  13  * switch_to(n) should switch tasks to task ptr, first checking that
  14  * ptr isn't the current task, in which case it does nothing.  This
  15  * also clears the TS-flag if the task we switched to has used the
  16  * math co-processor latest.
  17  */
  18 /*
  19  * switch_to() saves the extra registers, that are not saved
  20  * automatically by SAVE_SWITCH_STACK in resume(), ie. d0-d5 and
  21  * a0-a1. Some of these are used by schedule() and its predecessors
  22  * and so we might get see unexpected behaviors when a task returns
  23  * with unexpected register values.
  24  *
  25  * syscall stores these registers itself and none of them are used
  26  * by syscall after the function in the syscall has been called.
  27  *
  28  * Beware that resume now expects *next to be in d1 and the offset of
  29  * tss to be in a1. This saves a few instructions as we no longer have
  30  * to push them onto the stack and read them back right after.
  31  *
  32  * 02/17/96 - Jes Sorensen (jds@kom.auc.dk)
  33  *
  34  * Changed 96/09/19 by Andreas Schwab
  35  * pass prev in a0, next in a1
  36  */
  37 asmlinkage void resume(void);
  38 #define switch_to(prev,next,last) do { \
  39   register void *_prev __asm__ ("a0") = (prev); \
  40   register void *_next __asm__ ("a1") = (next); \
  41   register void *_last __asm__ ("d1"); \
  42   __asm__ __volatile__("jbsr resume" \
  43                        : "=a" (_prev), "=a" (_next), "=d" (_last) \
  44                        : "0" (_prev), "1" (_next) \
  45                        : "d0", "d2", "d3", "d4", "d5"); \
  46   (last) = _last; \
  47 } while (0)
  48
  49
  50 /*
  51  * Force strict CPU ordering.
  52  * Not really required on m68k...
  53  */
  54 #define nop()           do { asm volatile ("nop"); barrier(); } while (0)
  55 #define mb()            barrier()
  56 #define rmb()           barrier()
  57 #define wmb()           barrier()
  58 #define read_barrier_depends()  ((void)0)
  59 #define set_mb(var, value)      ({ (var) = (value); wmb(); })
  60
  61 #define smp_mb()        barrier()
  62 #define smp_rmb()       barrier()
  63 #define smp_wmb()       barrier()
  64 #define smp_read_barrier_depends()      ((void)0)
  65
  66 #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
  67
  68 struct __xchg_dummy { unsigned long a[100]; };
  69 #define __xg(x) ((volatile struct __xchg_dummy *)(x))
  70
  71 #ifndef CONFIG_RMW_INSNS
  72 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
  73 {
  74         unsigned long flags, tmp;
  75
  76         local_irq_save(flags);
  77
  78         switch (size) {
  79         case 1:
  80                 tmp = *(u8 *)ptr;
  81                 *(u8 *)ptr = x;
  82                 x = tmp;
  83                 break;
  84         case 2:
  85                 tmp = *(u16 *)ptr;
  86                 *(u16 *)ptr = x;
  87                 x = tmp;
  88                 break;
  89         case 4:
  90                 tmp = *(u32 *)ptr;
  91                 *(u32 *)ptr = x;
  92                 x = tmp;
  93                 break;
  94         default:
  95                 BUG();
  96         }
  97
  98         local_irq_restore(flags);
  99         return x;
 100 }
 101 #else
 102 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
 103 {
 104         switch (size) {
 105             case 1:
 106                 __asm__ __volatile__
 107                         ("moveb %2,%0\n\t"
 108                          "1:\n\t"
 109                          "casb %0,%1,%2\n\t"
 110                          "jne 1b"
 111                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 112                 break;
 113             case 2:
 114                 __asm__ __volatile__
 115                         ("movew %2,%0\n\t"
 116                          "1:\n\t"
 117                          "casw %0,%1,%2\n\t"
 118                          "jne 1b"
 119                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 120                 break;
 121             case 4:
 122                 __asm__ __volatile__
 123                         ("movel %2,%0\n\t"
 124                          "1:\n\t"
 125                          "casl %0,%1,%2\n\t"
 126                          "jne 1b"
 127                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 128                 break;
 129         }
 130         return x;
 131 }
 132 #endif
 133
 134 #include <asm-generic/cmpxchg-local.h>
 135
 136 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
 137
 138 /*
 139  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 140  * store NEW in MEM.  Return the initial value in MEM.  Success is
 141  * indicated by comparing RETURN with OLD.
 142  */
 143 #ifdef CONFIG_RMW_INSNS
 144 #define __HAVE_ARCH_CMPXCHG     1
 145
 146 static inline unsigned long __cmpxchg(volatile void *p, unsigned long old,
 147                                       unsigned long new, int size)
 148 {
 149         switch (size) {
 150         case 1:
 151                 __asm__ __volatile__ ("casb %0,%2,%1"
 152                                       : "=d" (old), "=m" (*(char *)p)
 153                                       : "d" (new), "0" (old), "m" (*(char *)p));
 154                 break;
 155         case 2:
 156                 __asm__ __volatile__ ("casw %0,%2,%1"
 157                                       : "=d" (old), "=m" (*(short *)p)
 158                                       : "d" (new), "0" (old), "m" (*(short *)p));
 159                 break;
 160         case 4:
 161                 __asm__ __volatile__ ("casl %0,%2,%1"
 162                                       : "=d" (old), "=m" (*(int *)p)
 163                                       : "d" (new), "0" (old), "m" (*(int *)p));
 164                 break;
 165         }
 166         return old;
 167 }
 168
 169 #define cmpxchg(ptr, o, n)                                                  \
 170         ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),           \
 171                         (unsigned long)(n), sizeof(*(ptr))))
 172 #define cmpxchg_local(ptr, o, n)                                            \
 173         ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),           \
 174                         (unsigned long)(n), sizeof(*(ptr))))
 175 #else
 176
 177 /*
 178  * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
 179  * them available.
 180  */
 181 #define cmpxchg_local(ptr, o, n)                                               \
 182         ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
 183                         (unsigned long)(n), sizeof(*(ptr))))
 184
 185 #include <asm-generic/cmpxchg.h>
 186
 187 #endif
 188
 189 #define arch_align_stack(x) (x)
 190
 191 #endif /* __KERNEL__ */
 192
 193 #endif /* _M68K_SYSTEM_H */