of/address: Handle #address-cells > 2 specially

When a bus specifies #address-cells > 2, of_bus_default_map() now
assumes that the mapping isn't for a physical address but rather an
identifier that needs to match exactly.

This is required by bindings that use multiple cells to translate a
resource to the parent bus (device index, type, ...).

See here for the discussion:

	https://lists.ozlabs.org/pipermail/devicetree-discuss/2012-June/016577.html

Originally-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

drivers/of/address.c

@@ -69,6 +69,14 @@ static u64 of_bus_default_map(u32 *addr, const __be32 *range,
 		 (unsigned long long)cp, (unsigned long long)s,
 		 (unsigned long long)da);
 
+	/*
+	 * If the number of address cells is larger than 2 we assume the
+	 * mapping doesn't specify a physical address. Rather, the address
+	 * specifies an identifier that must match exactly.
+	 */
+	if (na > 2 && memcmp(range, addr, na * 4) != 0)
+		return OF_BAD_ADDR;
+
 	if (da < cp || da >= (cp + s))
 		return OF_BAD_ADDR;
 	return da - cp;