include/asm-m68k/system.h

   1 #ifndef _M68K_SYSTEM_H
   2 #define _M68K_SYSTEM_H
   3
   4 #include <linux/config.h> /* get configuration macros */
   5 #include <linux/linkage.h>
   6 #include <linux/kernel.h>
   7 #include <asm/segment.h>
   8 #include <asm/entry.h>
   9
  10 #define prepare_to_switch()     do { } while(0)
  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, offset of tss in d1, and whether
  36  * the mm structures are shared in d2 (to avoid atc flushing).
  37  */
  38 asmlinkage void resume(void);
  39 #define switch_to(prev,next,last) { \
  40   register void *_prev __asm__ ("a0") = (prev); \
  41   register void *_next __asm__ ("a1") = (next); \
  42   register void *_last __asm__ ("d1"); \
  43   __asm__ __volatile__("jbsr " SYMBOL_NAME_STR(resume) \
  44                        : "=d" (_last) : "a" (_prev), "a" (_next) \
  45                        : "d0", "d1", "d2", "d3", "d4", "d5", "a0", "a1"); \
  46   (last) = _last; \
  47 }
  48
  49
  50 /* interrupt control.. */
  51 #if 0
  52 #define __sti() asm volatile ("andiw %0,%%sr": : "i" (ALLOWINT) : "memory")
  53 #else
  54 #include <asm/hardirq.h>
  55 #define __sti() ({                                                              \
  56         if (!local_irq_count(smp_processor_id()))                               \
  57                 asm volatile ("andiw %0,%%sr": : "i" (ALLOWINT) : "memory");    \
  58 })
  59 #endif
  60 #define __cli() asm volatile ("oriw  #0x0700,%%sr": : : "memory")
  61 #define __save_flags(x) asm volatile ("movew %%sr,%0":"=d" (x) : : "memory")
  62 #define __restore_flags(x) asm volatile ("movew %0,%%sr": :"d" (x) : "memory")
  63
  64 /* For spinlocks etc */
  65 #define local_irq_save(x)       ({ __save_flags(x); __cli(); })
  66 #define local_irq_restore(x)    __restore_flags(x)
  67 #define local_irq_disable()     __cli()
  68 #define local_irq_enable()      __sti()
  69
  70 #define cli()                   __cli()
  71 #define sti()                   __sti()
  72 #define save_flags(x)           __save_flags(x)
  73 #define restore_flags(x)        __restore_flags(x)
  74 #define save_and_cli(flags)   do { save_flags(flags); cli(); } while(0)
  75
  76 /*
  77  * Force strict CPU ordering.
  78  * Not really required on m68k...
  79  */
  80 #define nop()           do { asm volatile ("nop"); barrier(); } while (0)
  81 #define mb()            barrier()
  82 #define rmb()           barrier()
  83 #define wmb()           barrier()
  84 #define set_mb(var, value)    do { xchg(&var, value); } while (0)
  85 #define set_wmb(var, value)    do { var = value; wmb(); } while (0)
  86
  87 #define smp_mb()        barrier()
  88 #define smp_rmb()       barrier()
  89 #define smp_wmb()       barrier()
  90
  91
  92 #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
  93 #define tas(ptr) (xchg((ptr),1))
  94
  95 struct __xchg_dummy { unsigned long a[100]; };
  96 #define __xg(x) ((volatile struct __xchg_dummy *)(x))
  97
  98 #ifndef CONFIG_RMW_INSNS
  99 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
 100 {
 101   unsigned long tmp, flags;
 102
 103   save_flags(flags);
 104   cli();
 105
 106   switch (size) {
 107   case 1:
 108     __asm__ __volatile__
 109     ("moveb %2,%0\n\t"
 110      "moveb %1,%2"
 111     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
 112     break;
 113   case 2:
 114     __asm__ __volatile__
 115     ("movew %2,%0\n\t"
 116      "movew %1,%2"
 117     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
 118     break;
 119   case 4:
 120     __asm__ __volatile__
 121     ("movel %2,%0\n\t"
 122      "movel %1,%2"
 123     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
 124     break;
 125   }
 126   restore_flags(flags);
 127   return tmp;
 128 }
 129 #else
 130 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
 131 {
 132         switch (size) {
 133             case 1:
 134                 __asm__ __volatile__
 135                         ("moveb %2,%0\n\t"
 136                          "1:\n\t"
 137                          "casb %0,%1,%2\n\t"
 138                          "jne 1b"
 139                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 140                 break;
 141             case 2:
 142                 __asm__ __volatile__
 143                         ("movew %2,%0\n\t"
 144                          "1:\n\t"
 145                          "casw %0,%1,%2\n\t"
 146                          "jne 1b"
 147                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 148                 break;
 149             case 4:
 150                 __asm__ __volatile__
 151                         ("movel %2,%0\n\t"
 152                          "1:\n\t"
 153                          "casl %0,%1,%2\n\t"
 154                          "jne 1b"
 155                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 156                 break;
 157         }
 158         return x;
 159 }
 160 #endif
 161
 162 #endif /* _M68K_SYSTEM_H */