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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-09-08 01:01:14 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-09-08 01:01:14 -0300
commite5fd91f1ef340da553f7a79da9540c3db711c937 (patch)
treeb11842027dc6641da63f4bcc524f8678263304a3 /arch/arc/include/asm/barrier.h
parent2a9b0348e685a63d97486f6749622b61e9e3292f (diff)
Linux-libre 4.2-gnu
Diffstat (limited to 'arch/arc/include/asm/barrier.h')
-rw-r--r--arch/arc/include/asm/barrier.h48
1 files changed, 48 insertions, 0 deletions
diff --git a/arch/arc/include/asm/barrier.h b/arch/arc/include/asm/barrier.h
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+/*
+ * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#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")
+
+#endif
+
+#ifdef CONFIG_ISA_ARCOMPACT
+
+/*
+ * 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