MIPS: Provide pci_address_to_pio.

Without I/O ports won't work.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3697/

arch/mips/include/asm/prom.h

@@ -12,6 +12,9 @@
 #define __ASM_PROM_H
 
 #ifdef CONFIG_OF
+#include <linux/bug.h>
+#include <linux/io.h>
+#include <linux/types.h>
 #include <asm/bootinfo.h>
 
 extern int early_init_dt_scan_memory_arch(unsigned long node,
@@ -21,6 +24,18 @@ extern int reserve_mem_mach(unsigned long addr, unsigned long size);
 extern void free_mem_mach(unsigned long addr, unsigned long size);
 
 extern void device_tree_init(void);
+
+static inline unsigned long pci_address_to_pio(phys_addr_t address)
+{
+	/*
+	 * The ioport address can be directly used by inX() / outX()
+	 */
+	BUG_ON(address > IO_SPACE_LIMIT);
+
+	return (unsigned long) address;
+}
+#define pci_address_to_pio pci_address_to_pio
+
 #else /* CONFIG_OF */
 static inline void device_tree_init(void) { }
 #endif /* CONFIG_OF */