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 <asm/segment.h>
   7
   8 #define prepare_to_switch()     do { } while(0)
   9
  10 /*
  11  * switch_to(n) should switch tasks to task ptr, first checking that
  12  * ptr isn't the current task, in which case it does nothing.  This
  13  * also clears the TS-flag if the task we switched to has used the
  14  * math co-processor latest.
  15  */
  16 /*
  17  * switch_to() saves the extra registers, that are not saved
  18  * automatically by SAVE_SWITCH_STACK in resume(), ie. d0-d5 and
  19  * a0-a1. Some of these are used by schedule() and its predecessors
  20  * and so we might get see unexpected behaviors when a task returns
  21  * with unexpected register values.
  22  *
  23  * syscall stores these registers itself and none of them are used
  24  * by syscall after the function in the syscall has been called.
  25  *
  26  * Beware that resume now expects *next to be in d1 and the offset of
  27  * tss to be in a1. This saves a few instructions as we no longer have
  28  * to push them onto the stack and read them back right after.
  29  *
  30  * 02/17/96 - Jes Sorensen (jds@kom.auc.dk)
  31  *
  32  * Changed 96/09/19 by Andreas Schwab
  33  * pass prev in a0, next in a1, offset of tss in d1, and whether
  34  * the mm structures are shared in d2 (to avoid atc flushing).
  35  */
  36 asmlinkage void resume(void);
  37 #define switch_to(prev,next,last) { \
  38   register void *_prev __asm__ ("a0") = (prev); \
  39   register void *_next __asm__ ("a1") = (next); \
  40   register void *_last __asm__ ("d1"); \
  41   __asm__ __volatile__("jbsr " SYMBOL_NAME_STR(resume) \
  42                        : "=d" (_last) : "a" (_prev), "a" (_next) \
  43                        : "d0", "d1", "d2", "d3", "d4", "d5", "a0", "a1"); \
  44   (last) = _last; \
  45 }
  46
  47 #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
  48 #define tas(ptr) (xchg((ptr),1))
  49
  50 struct __xchg_dummy { unsigned long a[100]; };
  51 #define __xg(x) ((volatile struct __xchg_dummy *)(x))
  52
  53 #if defined(MACH_ATARI_ONLY) && !defined(CONFIG_HADES)
  54 /* block out HSYNC on the atari */
  55 #define __sti() __asm__ __volatile__ ("andiw #0xfbff,%/sr": : : "memory")
  56 #else /* portable version */
  57 #define __sti() __asm__ __volatile__ ("andiw #0xf8ff,%/sr": : : "memory")
  58 #endif /* machine compilation types */
  59 #define __cli() __asm__ __volatile__ ("oriw  #0x0700,%/sr": : : "memory")
  60 #define nop() __asm__ __volatile__ ("nop"::)
  61 #define mb()  __asm__ __volatile__ (""   : : :"memory")
  62 #define rmb()  __asm__ __volatile__ (""   : : :"memory")
  63 #define wmb()  __asm__ __volatile__ (""   : : :"memory")
  64
  65 #define __save_flags(x) \
  66 __asm__ __volatile__("movew %/sr,%0":"=d" (x) : /* no input */ :"memory")
  67
  68 #define __restore_flags(x) \
  69 __asm__ __volatile__("movew %0,%/sr": /* no outputs */ :"d" (x) : "memory")
  70
  71 #define cli() __cli()
  72 #define sti() __sti()
  73 #define save_flags(x) __save_flags(x)
  74 #define restore_flags(x) __restore_flags(x)
  75 #define save_and_cli(flags)   do { save_flags(flags); cli(); } while(0)
  76
  77 #ifndef CONFIG_RMW_INSNS
  78 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
  79 {
  80   unsigned long tmp, flags;
  81
  82   save_flags(flags);
  83   cli();
  84
  85   switch (size) {
  86   case 1:
  87     __asm__ __volatile__
  88     ("moveb %2,%0\n\t"
  89      "moveb %1,%2"
  90     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
  91     break;
  92   case 2:
  93     __asm__ __volatile__
  94     ("movew %2,%0\n\t"
  95      "movew %1,%2"
  96     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
  97     break;
  98   case 4:
  99     __asm__ __volatile__
 100     ("movel %2,%0\n\t"
 101      "movel %1,%2"
 102     : "=&d" (tmp) : "d" (x), "m" (*__xg(ptr)) : "memory");
 103     break;
 104   }
 105   restore_flags(flags);
 106   return tmp;
 107 }
 108 #else
 109 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
 110 {
 111         switch (size) {
 112             case 1:
 113                 __asm__ __volatile__
 114                         ("moveb %2,%0\n\t"
 115                          "1:\n\t"
 116                          "casb %0,%1,%2\n\t"
 117                          "jne 1b"
 118                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 119                 break;
 120             case 2:
 121                 __asm__ __volatile__
 122                         ("movew %2,%0\n\t"
 123                          "1:\n\t"
 124                          "casw %0,%1,%2\n\t"
 125                          "jne 1b"
 126                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 127                 break;
 128             case 4:
 129                 __asm__ __volatile__
 130                         ("movel %2,%0\n\t"
 131                          "1:\n\t"
 132                          "casl %0,%1,%2\n\t"
 133                          "jne 1b"
 134                          : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
 135                 break;
 136         }
 137         return x;
 138 }
 139 #endif
 140
 141 #endif /* _M68K_SYSTEM_H */