#ifdef CONFIG_MMU
#define page_to_bus(page) (page_to_phys(page))
-extern void iounmap(void __iomem *addr);
+extern void iounmap(volatile void __iomem *addr);
extern void __iomem *ioremap(phys_addr_t address, unsigned long size);
#define ioremap_nocache(addr, size) ioremap((addr), (size))