drm/tegra: Use the iommu dma_owner mechanism

Tegra joins many platform devices onto the same iommu_domain and builds
sort-of a DMA API on top of it.

Given that iommu_attach/detatch_device_shared() has supported this usage
model. Each device that wants to use the special domain will use
suppress_auto_claim_dma_owner and call iommu_attach_device_shared() which
will use dma owner framework to lock out other usages of the group and
refcount the domain attachment.

When the last device calls detatch the domain will be disconnected.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com> # Nexus7 T30

drivers/gpu/drm/tegra/dc.c

@@ -3275,4 +3275,5 @@ struct platform_driver tegra_dc_driver = {
 	},
 	.probe = tegra_dc_probe,
 	.remove = tegra_dc_remove,
+	.suppress_auto_claim_dma_owner = true,
 };

drivers/gpu/drm/tegra/drm.c

@@ -941,12 +941,15 @@ int tegra_drm_unregister_client(struct tegra_drm *tegra,
 	return 0;
 }
 
+/*
+ * Clients which use this function must set suppress_auto_claim_dma_owner in
+ * their platform_driver's device_driver struct.
+ */
 int host1x_client_iommu_attach(struct host1x_client *client)
 {
 	struct iommu_domain *domain = iommu_get_domain_for_dev(client->dev);
 	struct drm_device *drm = dev_get_drvdata(client->host);
 	struct tegra_drm *tegra = drm->dev_private;
-	struct iommu_group *group = NULL;
 	int err;
 
 #if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
@@ -965,48 +968,44 @@ int host1x_client_iommu_attach(struct host1x_client *client)
 	 * not the shared IOMMU domain, don't try to attach it to a different
 	 * domain. This allows using the IOMMU-backed DMA API.
 	 */
-	if (domain && domain != tegra->domain)
+	client->group = NULL;
+	if (!client->dev->iommu_group || (domain && domain != tegra->domain))
+		return iommu_device_set_dma_owner(client->dev,
+						  DMA_OWNER_DMA_API, NULL);
+
+	if (!tegra->domain)
 		return 0;
 
-	if (tegra->domain) {
-		group = iommu_group_get(client->dev);
-		if (!group)
-			return -ENODEV;
-
-		if (domain != tegra->domain) {
-			err = iommu_attach_group(tegra->domain, group);
-			if (err < 0) {
-				iommu_group_put(group);
-				return err;
-			}
-		}
+	err = iommu_device_set_dma_owner(client->dev,
+					 DMA_OWNER_PRIVATE_DOMAIN, NULL);
+	if (err)
+		return err;
 
-		tegra->use_explicit_iommu = true;
+	err = iommu_attach_device_shared(tegra->domain, client->dev);
+	if (err) {
+		iommu_device_release_dma_owner(client->dev,
+					       DMA_OWNER_PRIVATE_DOMAIN);
+		return err;
 	}
 
-	client->group = group;
-
+	tegra->use_explicit_iommu = true;
+	client->group = client->dev->iommu_group;
 	return 0;
 }
 
 void host1x_client_iommu_detach(struct host1x_client *client)
 {
+	struct iommu_domain *domain = iommu_get_domain_for_dev(client->dev);
 	struct drm_device *drm = dev_get_drvdata(client->host);
 	struct tegra_drm *tegra = drm->dev_private;
-	struct iommu_domain *domain;
 
 	if (client->group) {
-		/*
-		 * Devices that are part of the same group may no longer be
-		 * attached to a domain at this point because their group may
-		 * have been detached by an earlier client.
-		 */
-		domain = iommu_get_domain_for_dev(client->dev);
-		if (domain)
-			iommu_detach_group(tegra->domain, client->group);
-
-		iommu_group_put(client->group);
+		iommu_detach_device_shared(tegra->domain, client->dev);
+		iommu_device_release_dma_owner(client->dev,
+					       DMA_OWNER_PRIVATE_DOMAIN);
 		client->group = NULL;
+	} else {
+		iommu_device_release_dma_owner(client->dev, DMA_OWNER_DMA_API);
 	}
 }
 

drivers/gpu/drm/tegra/gr2d.c

@@ -404,4 +404,5 @@ struct platform_driver tegra_gr2d_driver = {
 	},
 	.probe = gr2d_probe,
 	.remove = gr2d_remove,
+	.suppress_auto_claim_dma_owner = true,
 };

drivers/gpu/drm/tegra/gr3d.c

@@ -639,4 +639,5 @@ struct platform_driver tegra_gr3d_driver = {
 	},
 	.probe = gr3d_probe,
 	.remove = gr3d_remove,
+	.suppress_auto_claim_dma_owner = true,
 };

drivers/gpu/drm/tegra/vic.c

@@ -526,6 +526,7 @@ struct platform_driver tegra_vic_driver = {
 	},
 	.probe = vic_probe,
 	.remove = vic_remove,
+	.suppress_auto_claim_dma_owner = true,
 };
 
 #if IS_ENABLED(CONFIG_ARCH_TEGRA_124_SOC)