From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/blackfin/include/asm/barrier.h | 86 +++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 arch/blackfin/include/asm/barrier.h

(limited to 'arch/blackfin/include/asm/barrier.h')

diff --git a/arch/blackfin/include/asm/barrier.h b/arch/blackfin/include/asm/barrier.h
new file mode 100644
index 000000000..dfb66fe88
--- /dev/null
+++ b/arch/blackfin/include/asm/barrier.h
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2004-2009 Analog Devices Inc.
+ *               Tony Kou (tonyko@lineo.ca)
+ *
+ * Licensed under the GPL-2 or later
+ */
+
+#ifndef _BLACKFIN_BARRIER_H
+#define _BLACKFIN_BARRIER_H
+
+#include <asm/cache.h>
+
+#define nop()  __asm__ __volatile__ ("nop;\n\t" : : )
+
+/*
+ * Force strict CPU ordering.
+ */
+#ifdef CONFIG_SMP
+
+#ifdef __ARCH_SYNC_CORE_DCACHE
+/* Force Core data cache coherence */
+# define mb()	do { barrier(); smp_check_barrier(); smp_mark_barrier(); } while (0)
+# define rmb()	do { barrier(); smp_check_barrier(); } while (0)
+# define wmb()	do { barrier(); smp_mark_barrier(); } while (0)
+/*
+ * read_barrier_depends - Flush all pending reads that subsequents reads
+ * depend on.
+ *
+ * No data-dependent reads from memory-like regions are ever reordered
+ * over this barrier.  All reads preceding this primitive are guaranteed
+ * to access memory (but not necessarily other CPUs' caches) before any
+ * reads following this primitive that depend on the data return by
+ * any of the preceding reads.  This primitive is much lighter weight than
+ * rmb() on most CPUs, and is never heavier weight than is
+ * rmb().
+ *
+ * These ordering constraints are respected by both the local CPU
+ * and the compiler.
+ *
+ * Ordering is not guaranteed by anything other than these primitives,
+ * not even by data dependencies.  See the documentation for
+ * memory_barrier() for examples and URLs to more information.
+ *
+ * For example, the following code would force ordering (the initial
+ * value of "a" is zero, "b" is one, and "p" is "&a"):
+ *
+ * <programlisting>
+ *	CPU 0				CPU 1
+ *
+ *	b = 2;
+ *	memory_barrier();
+ *	p = &b;				q = p;
+ *					read_barrier_depends();
+ *					d = *q;
+ * </programlisting>
+ *
+ * because the read of "*q" depends on the read of "p" and these
+ * two reads are separated by a read_barrier_depends().  However,
+ * the following code, with the same initial values for "a" and "b":
+ *
+ * <programlisting>
+ *	CPU 0				CPU 1
+ *
+ *	a = 2;
+ *	memory_barrier();
+ *	b = 3;				y = b;
+ *					read_barrier_depends();
+ *					x = a;
+ * </programlisting>
+ *
+ * does not enforce ordering, since there is no data dependency between
+ * the read of "a" and the read of "b".  Therefore, on some CPUs, such
+ * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()
+ * in cases like this where there are no data dependencies.
+ */
+# define read_barrier_depends()	do { barrier(); smp_check_barrier(); } while (0)
+#endif
+
+#endif /* !CONFIG_SMP */
+
+#define smp_mb__before_atomic()	barrier()
+#define smp_mb__after_atomic()	barrier()
+
+#include <asm-generic/barrier.h>
+
+#endif /* _BLACKFIN_BARRIER_H */
-- 
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