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system_mm.h

#ifndef _M68K_SYSTEM_H
#define _M68K_SYSTEM_H

#include <linux/linkage.h>
#include <linux/kernel.h>
#include <asm/segment.h>
#include <asm/entry.h>

#ifdef __KERNEL__

/*
 * switch_to(n) should switch tasks to task ptr, first checking that
 * ptr isn't the current task, in which case it does nothing.  This
 * also clears the TS-flag if the task we switched to has used the
 * math co-processor latest.
 */
/*
 * switch_to() saves the extra registers, that are not saved
 * automatically by SAVE_SWITCH_STACK in resume(), ie. d0-d5 and
 * a0-a1. Some of these are used by schedule() and its predecessors
 * and so we might get see unexpected behaviors when a task returns
 * with unexpected register values.
 *
 * syscall stores these registers itself and none of them are used
 * by syscall after the function in the syscall has been called.
 *
 * Beware that resume now expects *next to be in d1 and the offset of
 * tss to be in a1. This saves a few instructions as we no longer have
 * to push them onto the stack and read them back right after.
 *
 * 02/17/96 - Jes Sorensen (jds@kom.auc.dk)
 *
 * Changed 96/09/19 by Andreas Schwab
 * pass prev in a0, next in a1
 */
asmlinkage void resume(void);
#define switch_to(prev,next,last) do { \
  register void *_prev __asm__ ("a0") = (prev); \
  register void *_next __asm__ ("a1") = (next); \
  register void *_last __asm__ ("d1"); \
  __asm__ __volatile__("jbsr resume" \
                   : "=a" (_prev), "=a" (_next), "=d" (_last) \
                   : "0" (_prev), "1" (_next) \
                   : "d0", "d2", "d3", "d4", "d5"); \
  (last) = _last; \
} while (0)


/*
 * Force strict CPU ordering.
 * Not really required on m68k...
 */
#define nop()           do { asm volatile ("nop"); barrier(); } while (0)
#define mb()            barrier()
#define rmb()           barrier()
#define wmb()           barrier()
#define read_barrier_depends()      ((void)0)
#define set_mb(var, value)    ({ (var) = (value); wmb(); })

#define smp_mb()  barrier()
#define smp_rmb() barrier()
#define smp_wmb() barrier()
#define smp_read_barrier_depends()  ((void)0)

/* interrupt control.. */
#if 0
#define local_irq_enable() asm volatile ("andiw %0,%%sr": : "i" (ALLOWINT) : "memory")
#else
#include <linux/hardirq.h>
#define local_irq_enable() ({                                     \
      if (MACH_IS_Q40 || !hardirq_count())                              \
            asm volatile ("andiw %0,%%sr": : "i" (ALLOWINT) : "memory");      \
})
#endif
#define local_irq_disable() asm volatile ("oriw  #0x0700,%%sr": : : "memory")
#define local_save_flags(x) asm volatile ("movew %%sr,%0":"=d" (x) : : "memory")
#define local_irq_restore(x) asm volatile ("movew %0,%%sr": :"d" (x) : "memory")

static inline int irqs_disabled(void)
{
      unsigned long flags;
      local_save_flags(flags);
      return flags & ~ALLOWINT;
}

/* For spinlocks etc */
#define local_irq_save(x)     ({ local_save_flags(x); local_irq_disable(); })

#define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))

struct __xchg_dummy { unsigned long a[100]; };
#define __xg(x) ((volatile struct __xchg_dummy *)(x))

#ifndef CONFIG_RMW_INSNS
static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
{
      unsigned long flags, tmp;

      local_irq_save(flags);

      switch (size) {
      case 1:
            tmp = *(u8 *)ptr;
            *(u8 *)ptr = x;
            x = tmp;
            break;
      case 2:
            tmp = *(u16 *)ptr;
            *(u16 *)ptr = x;
            x = tmp;
            break;
      case 4:
            tmp = *(u32 *)ptr;
            *(u32 *)ptr = x;
            x = tmp;
            break;
      default:
            BUG();
      }

      local_irq_restore(flags);
      return x;
}
#else
static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
{
      switch (size) {
          case 1:
            __asm__ __volatile__
                  ("moveb %2,%0\n\t"
                   "1:\n\t"
                   "casb %0,%1,%2\n\t"
                   "jne 1b"
                   : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
            break;
          case 2:
            __asm__ __volatile__
                  ("movew %2,%0\n\t"
                   "1:\n\t"
                   "casw %0,%1,%2\n\t"
                   "jne 1b"
                   : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
            break;
          case 4:
            __asm__ __volatile__
                  ("movel %2,%0\n\t"
                   "1:\n\t"
                   "casl %0,%1,%2\n\t"
                   "jne 1b"
                   : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
            break;
      }
      return x;
}
#endif

#include <asm-generic/cmpxchg-local.h>

#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))

/*
 * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 * store NEW in MEM.  Return the initial value in MEM.  Success is
 * indicated by comparing RETURN with OLD.
 */
#ifdef CONFIG_RMW_INSNS
#define __HAVE_ARCH_CMPXCHG   1

static inline unsigned long __cmpxchg(volatile void *p, unsigned long old,
                              unsigned long new, int size)
{
      switch (size) {
      case 1:
            __asm__ __volatile__ ("casb %0,%2,%1"
                              : "=d" (old), "=m" (*(char *)p)
                              : "d" (new), "0" (old), "m" (*(char *)p));
            break;
      case 2:
            __asm__ __volatile__ ("casw %0,%2,%1"
                              : "=d" (old), "=m" (*(short *)p)
                              : "d" (new), "0" (old), "m" (*(short *)p));
            break;
      case 4:
            __asm__ __volatile__ ("casl %0,%2,%1"
                              : "=d" (old), "=m" (*(int *)p)
                              : "d" (new), "0" (old), "m" (*(int *)p));
            break;
      }
      return old;
}

#define cmpxchg(ptr, o, n)                                      \
      ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),       \
                  (unsigned long)(n), sizeof(*(ptr))))
#define cmpxchg_local(ptr, o, n)                                \
      ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),       \
                  (unsigned long)(n), sizeof(*(ptr))))
#else

/*
 * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
 * them available.
 */
#define cmpxchg_local(ptr, o, n)                                   \
      ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
                  (unsigned long)(n), sizeof(*(ptr))))

#ifndef CONFIG_SMP
#include <asm-generic/cmpxchg.h>
#endif

#endif

#define arch_align_stack(x) (x)

#endif /* __KERNEL__ */

#endif /* _M68K_SYSTEM_H */

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