tools/arch/sh/include/asm/barrier.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copied from the kernel sources:
   4  *
   5  * Copyright (C) 1999, 2000  Niibe Yutaka  &  Kaz Kojima
   6  * Copyright (C) 2002 Paul Mundt
   7  */
   8 #ifndef __TOOLS_LINUX_ASM_SH_BARRIER_H
   9 #define __TOOLS_LINUX_ASM_SH_BARRIER_H
  10
  11 /*
  12  * A brief note on ctrl_barrier(), the control register write barrier.
  13  *
  14  * Legacy SH cores typically require a sequence of 8 nops after
  15  * modification of a control register in order for the changes to take
  16  * effect. On newer cores (like the sh4a and sh5) this is accomplished
  17  * with icbi.
  18  *
  19  * Also note that on sh4a in the icbi case we can forego a synco for the
  20  * write barrier, as it's not necessary for control registers.
  21  *
  22  * Historically we have only done this type of barrier for the MMUCR, but
  23  * it's also necessary for the CCR, so we make it generic here instead.
  24  */
  25 #if defined(__SH4A__)
  26 #define mb()            __asm__ __volatile__ ("synco": : :"memory")
  27 #define rmb()           mb()
  28 #define wmb()           mb()
  29 #endif
  30
  31 #include <asm-generic/barrier.h>
  32
  33 #endif /* __TOOLS_LINUX_ASM_SH_BARRIER_H */