nds32: MMU definitions

This patch includes virtual memory layout, PHYS_OFFSET is defined as 0x0. It
also includes the 4KB/8KB page size configurations and pte operations.

Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/nds32/include/asm/shmparam.h

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#ifndef _ASMNDS32_SHMPARAM_H
+#define _ASMNDS32_SHMPARAM_H
+
+/*
+ * This should be the size of the virtually indexed cache/ways,
+ * whichever is greater since the cache aliases every size/ways
+ * bytes.
+ */
+#define	SHMLBA	(4 * SZ_8K)	/* attach addr a multiple of this */
+
+/*
+ * Enforce SHMLBA in shmat
+ */
+#define __ARCH_FORCE_SHMLBA
+
+#endif /* _ASMNDS32_SHMPARAM_H */