[POWERPC] Derive ebc ranges property from EBC registers

In the device tree for Ebony, the 'ranges' property in the node for
the EBC bridge shows the mappings from the chip select / address lines
actually used for the EBC peripherals into the address space of the
OPB.  At present, these mappings are hardcoded in ebony.dts for the
mappings set up by the OpenBIOS firmware when it configures the EBC
bridge.

This replaces the hardcoded mappings with code in the zImage to
read the EBC configuration registers and create an appropriate ranges
property based on them.  This should make the zImage and kernel more
robust to changes in firmware configuration.  In particular, some of
the Ebony's DIP switches can change the effective address of the Flash
and other peripherals in OPB space.  With this patch, the kernel will
be able to cope with at least some of the possible variations.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 3 insertions, 5 deletions

diff --git a/arch/powerpc/boot/dts/ebony.dts b/arch/powerpc/boot/dts/ebony.dts
index 0ec02f4726b5..586a2fc13c63 100644
--- a/arch/powerpc/boot/dts/ebony.dts
+++ b/arch/powerpc/boot/dts/ebony.dts
@@ -135,11 +135,9 @@
 				#address-cells = <2>;
 				#size-cells = <1>;
 				clock-frequency = <0>; // Filled in by zImage
-				ranges = <0 00000000 fff00000 100000
-					  1 00000000 48000000 100000
-					  2 00000000 ff800000 400000
-					  3 00000000 48200000 100000
-					  7 00000000 48300000 100000>;
+				// ranges property is supplied by zImage
+				// based on firmware's configuration of the
+				// EBC bridge
 				interrupts = <5 4>;
 				interrupt-parent = <&UIC1>;