powerpc/4xx: Add support for ISA holes on 4xx PCI/X/E

This adds support for ISA memory holes on the PCI, PCI-X and
PCI-E busses of the 4xx platforms. The patch includes changes
to the Bamboo and Canyonlands device-trees to add such a hole,
others can be updated separately.

The ISA memory hole is an additional outbound window configured
in the bridge to generate PCI cycles in the low memory addresses,
thus allowing to access things such as the hard-decoded VGA
aperture at 0xa0000..0xbffff or other similar things. It's made
accessible to userspace via the new legacy_mem file in sysfs for
which support was added by a previous patch.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

arch/powerpc/boot/dts/bamboo.dts

@@ -269,7 +269,8 @@ PCI0: pci@ec000000 {
 			 * later cannot be changed. Chip supports a second
 			 * IO range but we don't use it for now
 			 */
-			ranges = <0x02000000 0x00000000 0xa0000000 0x00000000 0xa0000000 0x00000000 0x20000000
+			ranges = <0x02000000 0x00000000 0xa0000000 0x00000000 0xa0000000 0x00000000 0x40000000
+				  0x02000000 0x00000000 0x00000000 0x00000000 0xe0000000 0x00000000 0x00100000
 				  0x01000000 0x00000000 0x00000000 0x00000000 0xe8000000 0x00000000 0x00010000>;
 
 			/* Inbound 2GB range starting at 0 */

arch/powerpc/boot/dts/canyonlands.dts

@@ -343,6 +343,7 @@ PCIX0: pci@c0ec00000 {
 			 * later cannot be changed
 			 */
 			ranges = <0x02000000 0x00000000 0x80000000 0x0000000d 0x80000000 0x00000000 0x80000000
+				  0x02000000 0x00000000 0x00000000 0x0000000c 0x0ee00000 0x00000000 0x00100000
 				  0x01000000 0x00000000 0x00000000 0x0000000c 0x08000000 0x00000000 0x00010000>;
 
 			/* Inbound 2GB range starting at 0 */
@@ -373,6 +374,7 @@ PCIE0: pciex@d00000000 {
 			 * later cannot be changed
 			 */
 			ranges = <0x02000000 0x00000000 0x80000000 0x0000000e 0x00000000 0x00000000 0x80000000
+				  0x02000000 0x00000000 0x00000000 0x0000000f 0x00000000 0x00000000 0x00100000
 				  0x01000000 0x00000000 0x00000000 0x0000000f 0x80000000 0x00000000 0x00010000>;
 
 			/* Inbound 2GB range starting at 0 */
@@ -414,6 +416,7 @@ PCIE1: pciex@d20000000 {
 			 * later cannot be changed
 			 */
 			ranges = <0x02000000 0x00000000 0x80000000 0x0000000e 0x80000000 0x00000000 0x80000000
+				  0x02000000 0x00000000 0x00000000 0x0000000f 0x00100000 0x00000000 0x00100000
 				  0x01000000 0x00000000 0x00000000 0x0000000f 0x80010000 0x00000000 0x00010000>;
 
 			/* Inbound 2GB range starting at 0 */