/* SPDX-License-Identifier: GPL-2.0-only */ /* * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com) */ #ifndef __ASM_BARRIER_H #define __ASM_BARRIER_H #ifdef CONFIG_ISA_ARCV2 /* * ARCv2 based HS38 cores are in-order issue, but still weakly ordered * due to micro-arch buffering/queuing of load/store, cache hit vs. miss ... * * Explicit barrier provided by DMB instruction * - Operand supports fine grained load/store/load+store semantics * - Ensures that selected memory operation issued before it will complete * before any subsequent memory operation of same type * - DMB guarantees SMP as well as local barrier semantics * (asm-generic/barrier.h ensures sane smp_*mb if not defined here, i.e. * UP: barrier(), SMP: smp_*mb == *mb) * - DSYNC provides DMB+completion_of_cache_bpu_maintenance_ops hence not needed * in the general case. Plus it only provides full barrier. */ #define mb() asm volatile("dmb 3\n" : : : "memory") #define rmb() asm volatile("dmb 1\n" : : : "memory") #define wmb() asm volatile("dmb 2\n" : : : "memory") #else /* * ARCompact based cores (ARC700) only have SYNC instruction which is super * heavy weight as it flushes the pipeline as well. * There are no real SMP implementations of such cores. */ #define mb() asm volatile("sync\n" : : : "memory") #endif #include <asm-generic/barrier.h> #endif