+extern const unsigned long mips_io_port_base;
+
+/*
+ * Gcc will generate code to load the value of mips_io_port_base after each
+ * function call which may be fairly wasteful in some cases. So we don't
+ * play quite by the book. We tell gcc mips_io_port_base is a long variable
+ * which solves the code generation issue. Now we need to violate the
+ * aliasing rules a little to make initialization possible and finally we
+ * will need the barrier() to fight side effects of the aliasing chat.
+ * This trickery will eventually collapse under gcc's optimizer. Oh well.
+ */
+static inline void set_io_port_base(unsigned long base)
+{
+ * (unsigned long *) &mips_io_port_base = base;
+}