1 /* 2 * Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima 3 * Copyright (C) 2002 Paul Mundt 4 */ 5 #ifndef __ASM_SH_BARRIER_H 6 #define __ASM_SH_BARRIER_H 7 8 #if defined(CONFIG_CPU_SH4A) || defined(CONFIG_CPU_SH5) 9 #include <asm/cache_insns.h> 10 #endif 11 12 /* 13 * A brief note on ctrl_barrier(), the control register write barrier. 14 * 15 * Legacy SH cores typically require a sequence of 8 nops after 16 * modification of a control register in order for the changes to take 17 * effect. On newer cores (like the sh4a and sh5) this is accomplished 18 * with icbi. 19 * 20 * Also note that on sh4a in the icbi case we can forego a synco for the 21 * write barrier, as it's not necessary for control registers. 22 * 23 * Historically we have only done this type of barrier for the MMUCR, but 24 * it's also necessary for the CCR, so we make it generic here instead. 25 */ 26 #if defined(CONFIG_CPU_SH4A) || defined(CONFIG_CPU_SH5) 27 #define mb() __asm__ __volatile__ ("synco": : :"memory") 28 #define rmb() mb() 29 #define wmb() mb() 30 #define ctrl_barrier() __icbi(PAGE_OFFSET) 31 #else 32 #define ctrl_barrier() __asm__ __volatile__ ("nop;nop;nop;nop;nop;nop;nop;nop") 33 #endif 34 35 #define set_mb(var, value) do { (void)xchg(&var, value); } while (0) 36 37 #include <asm-generic/barrier.h> 38 39 #endif /* __ASM_SH_BARRIER_H */ 40