arch/sh/include/asm/barrier.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (C) 1999, 2000  Niibe Yutaka  &  Kaz Kojima
   4  * Copyright (C) 2002 Paul Mundt
   5  */
   6 #ifndef __ASM_SH_BARRIER_H
   7 #define __ASM_SH_BARRIER_H
   8
   9 #if defined(CONFIG_CPU_SH4A)
  10 #include <asm/cache_insns.h>
  11 #endif
  12
  13 /*
  14  * A brief note on ctrl_barrier(), the control register write barrier.
  15  *
  16  * Legacy SH cores typically require a sequence of 8 nops after
  17  * modification of a control register in order for the changes to take
  18  * effect. On newer cores (like the sh4a and sh5) this is accomplished
  19  * with icbi.
  20  *
  21  * Also note that on sh4a in the icbi case we can forego a synco for the
  22  * write barrier, as it's not necessary for control registers.
  23  *
  24  * Historically we have only done this type of barrier for the MMUCR, but
  25  * it's also necessary for the CCR, so we make it generic here instead.
  26  */
  27 #if defined(CONFIG_CPU_SH4A)
  28 #define mb()            __asm__ __volatile__ ("synco": : :"memory")
  29 #define rmb()           mb()
  30 #define wmb()           mb()
  31 #define ctrl_barrier()  __icbi(PAGE_OFFSET)
  32 #else
  33 #if defined(CONFIG_CPU_J2) && defined(CONFIG_SMP)
  34 #define __smp_mb()      do { int tmp = 0; __asm__ __volatile__ ("cas.l %0,%0,@%1" : "+r"(tmp) : "z"(&tmp) : "memory", "t"); } while(0)
  35 #define __smp_rmb()     __smp_mb()
  36 #define __smp_wmb()     __smp_mb()
  37 #endif
  38 #define ctrl_barrier()  __asm__ __volatile__ ("nop;nop;nop;nop;nop;nop;nop;nop")
  39 #endif
  40
  41 #define __smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0)
  42
  43 #include <asm-generic/barrier.h>
  44
  45 #endif /* __ASM_SH_BARRIER_H */