[PATCH] powerpc: fix cell iommu setup

A small bug crept in the iommu driver when we made it more
generic. This patch is needed for boards that have a dma
window that does not start at bus address zero.
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/cell/iommu.c

@@ -289,7 +289,7 @@ static void cell_do_map_iommu(struct cell_iommu *iommu,
 	ioc_base = iommu->mapped_base;
 	ioc_mmio_base = iommu->mapped_mmio_base;
 
-	for (real_address = 0, io_address = 0;
+	for (real_address = 0, io_address = map_start;
 	     io_address <= map_start + map_size;
 	     real_address += io_page_size, io_address += io_page_size) {
 		ioste = get_iost_entry(fake_iopt, io_address, io_page_size);
@@ -302,7 +302,7 @@ static void cell_do_map_iommu(struct cell_iommu *iommu,
 		set_iopt_cache(ioc_mmio_base,
 			get_ioc_hash_1way(ioste, io_address),
 			get_ioc_tag(ioste, io_address),
-			get_iopt_entry(real_address-map_start, ioid, IOPT_PROT_RW));
+			get_iopt_entry(real_address, ioid, IOPT_PROT_RW));
 	}
 }