um->len = params->buf_size;
                for (i = 0; i < src_cnt; i++) {
-                       unsigned long buf = (unsigned long) thread->srcs[i];
+                       void *buf = thread->srcs[i];
                        struct page *pg = virt_to_page(buf);
-                       unsigned pg_off = buf & ~PAGE_MASK;
+                       unsigned pg_off = (unsigned long) buf & ~PAGE_MASK;
 
                        um->addr[i] = dma_map_page(dev->dev, pg, pg_off,
                                                   um->len, DMA_TO_DEVICE);
                /* map with DMA_BIDIRECTIONAL to force writeback/invalidate */
                dsts = &um->addr[src_cnt];
                for (i = 0; i < dst_cnt; i++) {
-                       unsigned long buf = (unsigned long) thread->dsts[i];
+                       void *buf = thread->dsts[i];
                        struct page *pg = virt_to_page(buf);
-                       unsigned pg_off = buf & ~PAGE_MASK;
+                       unsigned pg_off = (unsigned long) buf & ~PAGE_MASK;
 
                        dsts[i] = dma_map_page(dev->dev, pg, pg_off, um->len,
                                               DMA_BIDIRECTIONAL);