1. 根目录:
2. arch
3. mips
4. include
5. asm
6. barrier.h

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2006 by Ralf Baechle (ralf@linux-mips.org)
 */
#ifndef __ASM_BARRIER_H
#define __ASM_BARRIER_H

#include <asm/addrspace.h>

#define read_barrier_depends()		do { } while(0)
#define smp_read_barrier_depends()	do { } while(0)

#ifdef CONFIG_CPU_HAS_SYNC
#define __sync()				\
	__asm__ __volatile__(			\
		".set	push\n\t"		\
		".set	noreorder\n\t"		\
		".set	mips2\n\t"		\
		"sync\n\t"			\
		".set	pop"			\
		: /* no output */		\
		: /* no input */		\
		: "memory")
#else
#define __sync()	do { } while(0)
#endif

#define __fast_iob()				\
	__asm__ __volatile__(			\
		".set	push\n\t"		\
		".set	noreorder\n\t"		\
		"lw	$0,%0\n\t"		\
		"nop\n\t"			\
		".set	pop"			\
		: /* no output */		\
		: "m" (*(int *)CKSEG1)		\
		: "memory")
#ifdef CONFIG_CPU_CAVIUM_OCTEON
# define OCTEON_SYNCW_STR	".set push\n.set arch=octeon\nsyncw\nsyncw\n.set pop\n"
# define __syncw()	__asm__ __volatile__(OCTEON_SYNCW_STR : : : "memory")

# define fast_wmb()	__syncw()
# define fast_rmb()	barrier()
# define fast_mb()	__sync()
# define fast_iob()	do { } while (0)
#else /* ! CONFIG_CPU_CAVIUM_OCTEON */
# define fast_wmb()	__sync()
# define fast_rmb()	__sync()
# define fast_mb()	__sync()
# ifdef CONFIG_SGI_IP28
#  define fast_iob()				\
	__asm__ __volatile__(			\
		".set	push\n\t"		\
		".set	noreorder\n\t"		\
		"lw	$0,%0\n\t"		\
		"sync\n\t"			\
		"lw	$0,%0\n\t"		\
		".set	pop"			\
		: /* no output */		\
		: "m" (*(int *)CKSEG1ADDR(0x1fa00004)) \
		: "memory")
# else
#  define fast_iob()				\
	do {					\
		__sync();			\
		__fast_iob();			\
	} while (0)
# endif
#endif /* CONFIG_CPU_CAVIUM_OCTEON */

#ifdef CONFIG_CPU_HAS_WB

#include <asm/wbflush.h>

#define mb()		wbflush()
#define iob()		wbflush()

#else /* !CONFIG_CPU_HAS_WB */

#define mb()		fast_mb()
#define iob()		fast_iob()

#endif /* !CONFIG_CPU_HAS_WB */

#define wmb()		fast_wmb()
#define rmb()		fast_rmb()
#define dma_wmb()	fast_wmb()
#define dma_rmb()	fast_rmb()

#if defined(CONFIG_WEAK_ORDERING) && defined(CONFIG_SMP)
# ifdef CONFIG_CPU_CAVIUM_OCTEON
#  define smp_mb()	__sync()
#  define smp_rmb()	barrier()
#  define smp_wmb()	__syncw()
# else
#  define smp_mb()	__asm__ __volatile__("sync" : : :"memory")
#  define smp_rmb()	__asm__ __volatile__("sync" : : :"memory")
#  define smp_wmb()	__asm__ __volatile__("sync" : : :"memory")
# endif
#else
#define smp_mb()	barrier()
#define smp_rmb()	barrier()
#define smp_wmb()	barrier()
#endif

#if defined(CONFIG_WEAK_REORDERING_BEYOND_LLSC) && defined(CONFIG_SMP)
#define __WEAK_LLSC_MB		"	sync	\n"
#else
#define __WEAK_LLSC_MB		"		\n"
#endif

#define set_mb(var, value) \
	do { var = value; smp_mb(); } while (0)

#define smp_llsc_mb()	__asm__ __volatile__(__WEAK_LLSC_MB : : :"memory")

#ifdef CONFIG_CPU_CAVIUM_OCTEON
#define smp_mb__before_llsc() smp_wmb()
/* Cause previous writes to become visible on all CPUs as soon as possible */
#define nudge_writes() __asm__ __volatile__(".set push\n\t"		\
					    ".set arch=octeon\n\t"	\
					    "syncw\n\t"			\
					    ".set pop" : : : "memory")
#else
#define smp_mb__before_llsc() smp_llsc_mb()
#define nudge_writes() mb()
#endif

#define smp_store_release(p, v)						\
do {									\
	compiletime_assert_atomic_type(*p);				\
	smp_mb();							\
	ACCESS_ONCE(*p) = (v);						\
} while (0)

#define smp_load_acquire(p)						\
({									\
	typeof(*p) ___p1 = ACCESS_ONCE(*p);				\
	compiletime_assert_atomic_type(*p);				\
	smp_mb();							\
	___p1;								\
})

#define smp_mb__before_atomic()	smp_mb__before_llsc()
#define smp_mb__after_atomic()	smp_llsc_mb()

#endif /* __ASM_BARRIER_H */