+ dev_info(&dev->dev, "uio device registered with irq %lx\n",
+ udev->info.irq);
+
+ /*
+ * Doing a harmless dma mapping for attaching the device to
+ * the iommu identity mapping if kernel boots with iommu=pt.
+ * Note this is not a problem if no IOMMU at all.
+ */
+ map_addr = dma_alloc_coherent(&dev->dev, 1024, &map_dma_addr,
+ GFP_KERNEL);
+ if (map_addr)
+ memset(map_addr, 0, 1024);
+
+ if (!map_addr)
+ dev_info(&dev->dev, "dma mapping failed\n");
+ else {
+ dev_info(&dev->dev, "mapping 1K dma=%#llx host=%p\n",
+ (unsigned long long)map_dma_addr, map_addr);
+
+ dma_free_coherent(&dev->dev, 1024, map_addr, map_dma_addr);
+ dev_info(&dev->dev, "unmapping 1K dma=%#llx host=%p\n",
+ (unsigned long long)map_dma_addr, map_addr);
+ }