gpu: host1x: Use IOMMU groups

Use IOMMU groups to attach the host1x device to its IOMMU domain. This
is not strictly necessary because the domain isn't shared with any other
device, but it makes the code consistent with how IOMMU is handled in
other drivers and provides an easy way to detect when no IOMMU has been
attached via device tree.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/host1x/dev.c

@@ -218,19 +218,24 @@ static int host1x_probe(struct platform_device *pdev)
 		return err;
 	}
 
-	if (iommu_present(&platform_bus_type)) {
+	host->group = iommu_group_get(&pdev->dev);
+	if (host->group) {
 		struct iommu_domain_geometry *geometry;
 		unsigned long order;
 
 		host->domain = iommu_domain_alloc(&platform_bus_type);
-		if (!host->domain)
-			return -ENOMEM;
+		if (!host->domain) {
+			err = -ENOMEM;
+			goto put_group;
+		}
 
-		err = iommu_attach_device(host->domain, &pdev->dev);
+		err = iommu_attach_group(host->domain, host->group);
 		if (err) {
 			if (err == -ENODEV) {
 				iommu_domain_free(host->domain);
 				host->domain = NULL;
+				iommu_group_put(host->group);
+				host->group = NULL;
 				goto skip_iommu;
 			}
 
@@ -296,13 +301,15 @@ static int host1x_probe(struct platform_device *pdev)
 fail_free_channels:
 	host1x_channel_list_free(&host->channel_list);
 fail_detach_device:
-	if (host->domain) {
+	if (host->group && host->domain) {
 		put_iova_domain(&host->iova);
-		iommu_detach_device(host->domain, &pdev->dev);
+		iommu_detach_group(host->domain, host->group);
 	}
 fail_free_domain:
 	if (host->domain)
 		iommu_domain_free(host->domain);
+put_group:
+	iommu_group_put(host->group);
 
 	return err;
 }
@@ -319,8 +326,9 @@ static int host1x_remove(struct platform_device *pdev)
 
 	if (host->domain) {
 		put_iova_domain(&host->iova);
-		iommu_detach_device(host->domain, &pdev->dev);
+		iommu_detach_group(host->domain, host->group);
 		iommu_domain_free(host->domain);
+		iommu_group_put(host->group);
 	}
 
 	return 0;

drivers/gpu/host1x/dev.h

@@ -117,6 +117,7 @@ struct host1x {
 	struct clk *clk;
 	struct reset_control *rst;
 
+	struct iommu_group *group;
 	struct iommu_domain *domain;
 	struct iova_domain iova;
 	dma_addr_t iova_end;