arch/m68k/include/asm/system_no.h

   1 #ifndef _M68KNOMMU_SYSTEM_H
   2 #define _M68KNOMMU_SYSTEM_H
   3
   4 #include <linux/linkage.h>
   5 #include <linux/irqflags.h>
   6 #include <asm/segment.h>
   7 #include <asm/entry.h>
   8
   9 /*
  10  * switch_to(n) should switch tasks to task ptr, first checking that
  11  * ptr isn't the current task, in which case it does nothing.  This
  12  * also clears the TS-flag if the task we switched to has used the
  13  * math co-processor latest.
  14  */
  15 /*
  16  * switch_to() saves the extra registers, that are not saved
  17  * automatically by SAVE_SWITCH_STACK in resume(), ie. d0-d5 and
  18  * a0-a1. Some of these are used by schedule() and its predecessors
  19  * and so we might get see unexpected behaviors when a task returns
  20  * with unexpected register values.
  21  *
  22  * syscall stores these registers itself and none of them are used
  23  * by syscall after the function in the syscall has been called.
  24  *
  25  * Beware that resume now expects *next to be in d1 and the offset of
  26  * tss to be in a1. This saves a few instructions as we no longer have
  27  * to push them onto the stack and read them back right after.
  28  *
  29  * 02/17/96 - Jes Sorensen (jds@kom.auc.dk)
  30  *
  31  * Changed 96/09/19 by Andreas Schwab
  32  * pass prev in a0, next in a1, offset of tss in d1, and whether
  33  * the mm structures are shared in d2 (to avoid atc flushing).
  34  */
  35 asmlinkage void resume(void);
  36 #define switch_to(prev,next,last)                               \
  37 {                                                               \
  38   void *_last;                                                  \
  39   __asm__ __volatile__(                                         \
  40         "movel  %1, %%a0\n\t"                                   \
  41         "movel  %2, %%a1\n\t"                                   \
  42         "jbsr resume\n\t"                                       \
  43         "movel  %%d1, %0\n\t"                                   \
  44        : "=d" (_last)                                           \
  45        : "d" (prev), "d" (next)                                 \
  46        : "cc", "d0", "d1", "d2", "d3", "d4", "d5", "a0", "a1"); \
  47   (last) = _last;                                               \
  48 }
  49
  50 #define iret() __asm__ __volatile__ ("rte": : :"memory", "sp", "cc")
  51
  52 /*
  53  * Force strict CPU ordering.
  54  * Not really required on m68k...
  55  */
  56 #define nop()  asm volatile ("nop"::)
  57 #define mb()   asm volatile (""   : : :"memory")
  58 #define rmb()  asm volatile (""   : : :"memory")
  59 #define wmb()  asm volatile (""   : : :"memory")
  60 #define set_mb(var, value)      ({ (var) = (value); wmb(); })
  61
  62 #ifdef CONFIG_SMP
  63 #define smp_mb()        mb()
  64 #define smp_rmb()       rmb()
  65 #define smp_wmb()       wmb()
  66 #define smp_read_barrier_depends()      read_barrier_depends()
  67 #else
  68 #define smp_mb()        barrier()
  69 #define smp_rmb()       barrier()
  70 #define smp_wmb()       barrier()
  71 #define smp_read_barrier_depends()      do { } while(0)
  72 #endif
  73
  74 #define read_barrier_depends()  ((void)0)
  75
  76 #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
  77
  78 struct __xchg_dummy { unsigned long a[100]; };
  79 #define __xg(x) ((volatile struct __xchg_dummy *)(x))
  80
  81 #ifndef CONFIG_RMW_INSNS
  82 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
  83 {
  84   unsigned long tmp, flags;
  85
  86   local_irq_save(flags);
  87
  88   switch (size) {
  89   case 1:
  90     __asm__ __volatile__
  91     ("moveb %2,%0\n\t"
  92      "moveb %1,%2"
  93     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
  94     break;
  95   case 2:
  96     __asm__ __volatile__
  97     ("movew %2,%0\n\t"
  98      "movew %1,%2"
  99     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
 100     break;
 101   case 4:
 102     __asm__ __volatile__
 103     ("movel %2,%0\n\t"
 104      "movel %1,%2"
 105     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
 106     break;
 107   }
 108   local_irq_restore(flags);
 109   return tmp;
 110 }
 111 #else
 112 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
 113 {
 114         switch (size) {
 115             case 1:
 116                 __asm__ __volatile__
 117                         ("moveb %2,%0\n\t"
 118                          "1:\n\t"
 119                          "casb %0,%1,%2\n\t"
 120                          "jne 1b"
 121                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 122                 break;
 123             case 2:
 124                 __asm__ __volatile__
 125                         ("movew %2,%0\n\t"
 126                          "1:\n\t"
 127                          "casw %0,%1,%2\n\t"
 128                          "jne 1b"
 129                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 130                 break;
 131             case 4:
 132                 __asm__ __volatile__
 133                         ("movel %2,%0\n\t"
 134                          "1:\n\t"
 135                          "casl %0,%1,%2\n\t"
 136                          "jne 1b"
 137                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 138                 break;
 139         }
 140         return x;
 141 }
 142 #endif
 143
 144 #include <asm-generic/cmpxchg-local.h>
 145
 146 /*
 147  * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
 148  * them available.
 149  */
 150 #define cmpxchg_local(ptr, o, n)                                               \
 151         ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
 152                         (unsigned long)(n), sizeof(*(ptr))))
 153 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
 154
 155 #ifndef CONFIG_SMP
 156 #include <asm-generic/cmpxchg.h>
 157 #endif
 158
 159 #define arch_align_stack(x) (x)
 160
 161
 162 #endif /* _M68KNOMMU_SYSTEM_H */