sh: Prepare for dynamic PMB support

To allow the MMU to be switched between 29bit and 32bit mode at runtime
some constants need to swapped for functions that return a runtime
value.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/mm/init.c

@@ -323,4 +323,12 @@ int memory_add_physaddr_to_nid(u64 addr)
 }
 EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 #endif
+
 #endif /* CONFIG_MEMORY_HOTPLUG */
+
+#ifdef CONFIG_PMB
+int __in_29bit_mode(void)
+{
+	return !(ctrl_inl(PMB_PASCR) & PASCR_SE);
+}
+#endif /* CONFIG_PMB */