+/* Convert DMA address to offset into virtually contiguous buffer. */
+size_t fw_iso_buffer_lookup(struct fw_iso_buffer *buffer, dma_addr_t completed)
+{
+ int i;
+ dma_addr_t address;
+ ssize_t offset;
+
+ for (i = 0; i < buffer->page_count; i++) {
+ address = page_private(buffer->pages[i]);
+ offset = (ssize_t)completed - (ssize_t)address;
+ if (offset > 0 && offset <= PAGE_SIZE)
+ return (i << PAGE_SHIFT) + offset;
+ }
+
+ return 0;
+}
+