agp: Support 64-bit APBASE

Per the AGP 3.0 spec, APBASE is a standard PCI BAR and may be either 32
bits or 64 bits wide.  Many drivers read APBASE directly, but they only
handled 32-bit BARs.

The PCI core reads APBASE at enumeration-time.  Use pci_bus_address()
instead of reading it again in the driver.  This works correctly for both
32-bit and 64-bit BARs.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/char/agp/via-agp.c

@@ -43,16 +43,15 @@ static int via_fetch_size(void)
 
 static int via_configure(void)
 {
-	u32 temp;
 	struct aper_size_info_8 *current_size;
 
 	current_size = A_SIZE_8(agp_bridge->current_size);
 	/* aperture size */
 	pci_write_config_byte(agp_bridge->dev, VIA_APSIZE,
 			      current_size->size_value);
-	/* address to map too */
-	pci_read_config_dword(agp_bridge->dev, AGP_APBASE, &temp);
-	agp_bridge->gart_bus_addr = (temp & PCI_BASE_ADDRESS_MEM_MASK);
+	/* address to map to */
+	agp_bridge->gart_bus_addr = pci_bus_address(agp_bridge->dev,
+						    AGP_APERTURE_BAR);
 
 	/* GART control register */
 	pci_write_config_dword(agp_bridge->dev, VIA_GARTCTRL, 0x0000000f);
@@ -132,9 +131,9 @@ static int via_configure_agp3(void)
 
 	current_size = A_SIZE_16(agp_bridge->current_size);
 
-	/* address to map too */
-	pci_read_config_dword(agp_bridge->dev, AGP_APBASE, &temp);
-	agp_bridge->gart_bus_addr = (temp & PCI_BASE_ADDRESS_MEM_MASK);
+	/* address to map to */
+	agp_bridge->gart_bus_addr = pci_bus_address(agp_bridge->dev,
+						    AGP_APERTURE_BAR);
 
 	/* attbase - aperture GATT base */
 	pci_write_config_dword(agp_bridge->dev, VIA_AGP3_ATTBASE,