io_mapping_map_atomic_wc
vaddr = io_mapping_map_atomic_wc(mapping, base);
vaddr = io_mapping_map_atomic_wc(mapping, base);
vaddr = (void __force *)io_mapping_map_atomic_wc(&ggtt->iomap,
s = io_mapping_map_atomic_wc(&ggtt->iomap, slot);