diff --git a/drivers/misc/swap_case.c b/drivers/misc/swap_case.c
index 18d756e..75fe641 100644
--- a/drivers/misc/swap_case.c
+++ b/drivers/misc/swap_case.c
@@ -24,9 +24,6 @@
 	u32 bar[6];
 };
 
-#define offset_to_barnum(offset)	\
-		(((offset) - PCI_BASE_ADDRESS_0) / sizeof(u32))
-
 enum {
 	MEM_TEXT_SIZE	= 0x100,
 };
@@ -144,7 +141,7 @@
 		int barnum;
 		u32 *bar, result;
 
-		barnum = offset_to_barnum(offset);
+		barnum = pci_offset_to_barnum(offset);
 		bar = &plat->bar[barnum];
 
 		result = *bar;
@@ -224,7 +221,7 @@
 		int barnum;
 		u32 *bar;
 
-		barnum = offset_to_barnum(offset);
+		barnum = pci_offset_to_barnum(offset);
 		bar = &plat->bar[barnum];
 
 		debug("w bar %d=%lx\n", barnum, value);
diff --git a/include/pci.h b/include/pci.h
index 999a594..2b82b2c 100644
--- a/include/pci.h
+++ b/include/pci.h
@@ -215,6 +215,10 @@
 #define  PCI_BASE_ADDRESS_IO_MASK	(~0x03ULL)
 /* bit 1 is reserved if address_space = 1 */
 
+/* Convert a regsister address (e.g. PCI_BASE_ADDRESS_1) to a bar # (e.g. 1) */
+#define pci_offset_to_barnum(offset)	\
+		(((offset) - PCI_BASE_ADDRESS_0) / sizeof(u32))
+
 /* Header type 0 (normal devices) */
 #define PCI_CARDBUS_CIS		0x28
 #define PCI_SUBSYSTEM_VENDOR_ID 0x2c