drm/tegra: Use iommu_paging_domain_alloc()

Commit <17de3f5fdd35> ("iommu: Retire bus ops") removes iommu ops from
the bus structure. The iommu subsystem no longer relies on bus for
operations. So iommu_domain_alloc() interface is no longer relevant.

Replace iommu_domain_alloc() with iommu_paging_domain_alloc() which takes
the physical device from which the host1x_device virtual device was
instantiated. This physical device is a common parent to all physical
devices that are part of the virtual device.

Suggested-by: Thierry Reding <[e-mail]>
Signed-off-by: Lu Baolu <[e-mail]>
Signed-off-by: Lyude Paul <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/tegra/drm.c

···
 
 static int host1x_drm_probe(struct host1x_device *dev)
 {
+	struct device *dma_dev = dev->dev.parent;
 	struct tegra_drm *tegra;
 	struct drm_device *drm;
 	int err;
···
 		goto put;
 	}
 
-	if (host1x_drm_wants_iommu(dev) && iommu_present(&platform_bus_type)) {
-		tegra->domain = iommu_domain_alloc(&platform_bus_type);
+	if (host1x_drm_wants_iommu(dev) && device_iommu_mapped(dma_dev)) {
+		tegra->domain = iommu_paging_domain_alloc(dma_dev);
 		if (!tegra->domain) {
 			err = -ENOMEM;
 			goto free;