drm/tegra: Use IOMMU groups

In order to support IOMMUs more generically and transparently handle the
ARM SMMU on Tegra186, move to using groups instead of devices for domain
attachment. An IOMMU group is a set of devices that share the same IOMMU
domain and is therefore a good match to represent what Tegra DRM needs.

Signed-off-by: Thierry Reding <[e-mail]>

drivers/gpu/drm/tegra/dc.c

···
 static int tegra_dc_init(struct host1x_client *client)
 {
 	struct drm_device *drm = dev_get_drvdata(client->parent);
+	struct iommu_group *group = iommu_group_get(client->dev);
 	unsigned long flags = HOST1X_SYNCPT_CLIENT_MANAGED;
 	struct tegra_dc *dc = host1x_client_to_dc(client);
 	struct tegra_drm *tegra = drm->dev_private;
···
 	if (!dc->syncpt)
 		dev_warn(dc->dev, "failed to allocate syncpoint\n");
 
-	if (tegra->domain) {
-		err = iommu_attach_device(tegra->domain, dc->dev);
-		if (err < 0) {
-			dev_err(dc->dev, "failed to attach to domain: %d\n",
-				err);
-			return err;
+	if (group && tegra->domain) {
+		if (group != tegra->group) {
+			err = iommu_attach_group(tegra->domain, group);
+			if (err < 0) {
+				dev_err(dc->dev,
+					"failed to attach to domain: %d\n",
+					err);
+				return err;
+			}
+
+			tegra->group = group;
 		}
 
 		dc->domain = tegra->domain;
···
 	if (!IS_ERR(primary))
 		drm_plane_cleanup(primary);
 
-	if (tegra->domain) {
-		iommu_detach_device(tegra->domain, dc->dev);
+	if (group && tegra->domain) {
+		iommu_detach_group(tegra->domain, group);
 		dc->domain = NULL;
 	}
 
···
 
 static int tegra_dc_exit(struct host1x_client *client)
 {
+	struct iommu_group *group = iommu_group_get(client->dev);
 	struct tegra_dc *dc = host1x_client_to_dc(client);
 	int err;
 
···
 		return err;
 	}
 
-	if (dc->domain) {
-		iommu_detach_device(dc->domain, dc->dev);
+	if (group && dc->domain) {
+		iommu_detach_group(dc->domain, group);
 		dc->domain = NULL;
 	}
 

drivers/gpu/drm/tegra/drm.h

···
 	struct drm_device *drm;
 
 	struct iommu_domain *domain;
+	struct iommu_group *group;
 	struct mutex mm_lock;
 	struct drm_mm mm;
 

drivers/gpu/drm/tegra/vic.c

···
 static int vic_init(struct host1x_client *client)
 {
 	struct tegra_drm_client *drm = host1x_to_drm_client(client);
+	struct iommu_group *group = iommu_group_get(client->dev);
 	struct drm_device *dev = dev_get_drvdata(client->parent);
 	struct tegra_drm *tegra = dev->dev_private;
 	struct vic *vic = to_vic(drm);
 	int err;
 
-	if (tegra->domain) {
-		err = iommu_attach_device(tegra->domain, vic->dev);
+	if (group && tegra->domain) {
+		err = iommu_attach_group(tegra->domain, group);
 		if (err < 0) {
 			dev_err(vic->dev, "failed to attach to domain: %d\n",
 				err);
···
 		vic->falcon.data = tegra;
 		err = falcon_load_firmware(&vic->falcon);
 		if (err < 0)
-			goto detach_device;
+			goto detach;
 	}
 
 	vic->channel = host1x_channel_request(client->dev);
 	if (!vic->channel) {
 		err = -ENOMEM;
-		goto detach_device;
+		goto detach;
 	}
 
 	client->syncpts[0] = host1x_syncpt_request(client, 0);
···
 	host1x_syncpt_free(client->syncpts[0]);
 free_channel:
 	host1x_channel_put(vic->channel);
-detach_device:
-	if (tegra->domain)
-		iommu_detach_device(tegra->domain, vic->dev);
+detach:
+	if (group && tegra->domain)
+		iommu_detach_group(tegra->domain, group);
 
 	return err;
 }
···
 static int vic_exit(struct host1x_client *client)
 {
 	struct tegra_drm_client *drm = host1x_to_drm_client(client);
+	struct iommu_group *group = iommu_group_get(client->dev);
 	struct drm_device *dev = dev_get_drvdata(client->parent);
 	struct tegra_drm *tegra = dev->dev_private;
 	struct vic *vic = to_vic(drm);
···
 	host1x_channel_put(vic->channel);
 
 	if (vic->domain) {
-		iommu_detach_device(vic->domain, vic->dev);
+		iommu_detach_group(vic->domain, group);
 		vic->domain = NULL;
 	}