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Diffstat (limited to 'arch/sh/include/asm/barrier.h')
| -rw-r--r-- | arch/sh/include/asm/barrier.h | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/arch/sh/include/asm/barrier.h b/arch/sh/include/asm/barrier.h new file mode 100644 index 000000000..43715308b --- /dev/null +++ b/arch/sh/include/asm/barrier.h @@ -0,0 +1,39 @@ +/* + * Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima + * Copyright (C) 2002 Paul Mundt + */ +#ifndef __ASM_SH_BARRIER_H +#define __ASM_SH_BARRIER_H + +#if defined(CONFIG_CPU_SH4A) || defined(CONFIG_CPU_SH5) +#include <asm/cache_insns.h> +#endif + +/* + * A brief note on ctrl_barrier(), the control register write barrier. + * + * Legacy SH cores typically require a sequence of 8 nops after + * modification of a control register in order for the changes to take + * effect. On newer cores (like the sh4a and sh5) this is accomplished + * with icbi. + * + * Also note that on sh4a in the icbi case we can forego a synco for the + * write barrier, as it's not necessary for control registers. + * + * Historically we have only done this type of barrier for the MMUCR, but + * it's also necessary for the CCR, so we make it generic here instead. + */ +#if defined(CONFIG_CPU_SH4A) || defined(CONFIG_CPU_SH5) +#define mb() __asm__ __volatile__ ("synco": : :"memory") +#define rmb() mb() +#define wmb() mb() +#define ctrl_barrier() __icbi(PAGE_OFFSET) +#else +#define ctrl_barrier() __asm__ __volatile__ ("nop;nop;nop;nop;nop;nop;nop;nop") +#endif + +#define set_mb(var, value) do { (void)xchg(&var, value); } while (0) + +#include <asm-generic/barrier.h> + +#endif /* __ASM_SH_BARRIER_H */ |