Disintegrate asm/system.h for IA64

Disintegrate asm/system.h for IA64.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Tony Luck <tony.luck@intel.com>
cc: linux-ia64@vger.kernel.org

1 files changed, 68 insertions, 0 deletions

diff --git a/arch/ia64/include/asm/barrier.h b/arch/ia64/include/asm/barrier.h
new file mode 100644
index 000000000000..60576e06b6fb
--- /dev/null
+++ b/arch/ia64/include/asm/barrier.h
@@ -0,0 +1,68 @@
+/*
+ * Memory barrier definitions.  This is based on information published
+ * in the Processor Abstraction Layer and the System Abstraction Layer
+ * manual.
+ *
+ * Copyright (C) 1998-2003 Hewlett-Packard Co
+ *	David Mosberger-Tang <davidm@hpl.hp.com>
+ * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
+ * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
+ */
+#ifndef _ASM_IA64_BARRIER_H
+#define _ASM_IA64_BARRIER_H
+
+#include <linux/compiler.h>
+
+/*
+ * Macros to force memory ordering.  In these descriptions, "previous"
+ * and "subsequent" refer to program order; "visible" means that all
+ * architecturally visible effects of a memory access have occurred
+ * (at a minimum, this means the memory has been read or written).
+ *
+ *   wmb():	Guarantees that all preceding stores to memory-
+ *		like regions are visible before any subsequent
+ *		stores and that all following stores will be
+ *		visible only after all previous stores.
+ *   rmb():	Like wmb(), but for reads.
+ *   mb():	wmb()/rmb() combo, i.e., all previous memory
+ *		accesses are visible before all subsequent
+ *		accesses and vice versa.  This is also known as
+ *		a "fence."
+ *
+ * Note: "mb()" and its variants cannot be used as a fence to order
+ * accesses to memory mapped I/O registers.  For that, mf.a needs to
+ * be used.  However, we don't want to always use mf.a because (a)
+ * it's (presumably) much slower than mf and (b) mf.a is supported for
+ * sequential memory pages only.
+ */
+#define mb()	ia64_mf()
+#define rmb()	mb()
+#define wmb()	mb()
+#define read_barrier_depends()	do { } while(0)
+
+#ifdef CONFIG_SMP
+# define smp_mb()	mb()
+# define smp_rmb()	rmb()
+# define smp_wmb()	wmb()
+# define smp_read_barrier_depends()	read_barrier_depends()
+#else
+# define smp_mb()	barrier()
+# define smp_rmb()	barrier()
+# define smp_wmb()	barrier()
+# define smp_read_barrier_depends()	do { } while(0)
+#endif
+
+/*
+ * XXX check on this ---I suspect what Linus really wants here is
+ * acquire vs release semantics but we can't discuss this stuff with
+ * Linus just yet.  Grrr...
+ */
+#define set_mb(var, value)	do { (var) = (value); mb(); } while (0)
+
+/*
+ * The group barrier in front of the rsm & ssm are necessary to ensure
+ * that none of the previous instructions in the same group are
+ * affected by the rsm/ssm.
+ */
+
+#endif /* _ASM_IA64_BARRIER_H */