drm/tegra: gr2d: Add IOMMU support

Attach GR2D to the display IOMMU group in order to provide GR2D access
to BO's IOVA.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/gr2d.c

@@ -7,12 +7,14 @@
  */
 
 #include <linux/clk.h>
+#include <linux/iommu.h>
 
 #include "drm.h"
 #include "gem.h"
 #include "gr2d.h"
 
 struct gr2d {
+	struct iommu_group *group;
 	struct tegra_drm_client client;
 	struct host1x_channel *channel;
 	struct clk *clk;
@@ -30,7 +32,9 @@ static int gr2d_init(struct host1x_client *client)
 	struct tegra_drm_client *drm = host1x_to_drm_client(client);
 	struct drm_device *dev = dev_get_drvdata(client->parent);
 	unsigned long flags = HOST1X_SYNCPT_HAS_BASE;
+	struct tegra_drm *tegra = dev->dev_private;
 	struct gr2d *gr2d = to_gr2d(drm);
+	int err;
 
 	gr2d->channel = host1x_channel_request(client->dev);
 	if (!gr2d->channel)
@@ -42,23 +46,46 @@ static int gr2d_init(struct host1x_client *client)
 		return -ENOMEM;
 	}
 
-	return tegra_drm_register_client(dev->dev_private, drm);
+	if (tegra->domain) {
+		gr2d->group = iommu_group_get(client->dev);
+
+		if (gr2d->group) {
+			err = iommu_attach_group(tegra->domain, gr2d->group);
+			if (err < 0) {
+				dev_err(client->dev,
+					"failed to attach to domain: %d\n",
+					err);
+				host1x_syncpt_free(client->syncpts[0]);
+				host1x_channel_put(gr2d->channel);
+				iommu_group_put(gr2d->group);
+				return err;
+			}
+		}
+	}
+
+	return tegra_drm_register_client(tegra, drm);
 }
 
 static int gr2d_exit(struct host1x_client *client)
 {
 	struct tegra_drm_client *drm = host1x_to_drm_client(client);
 	struct drm_device *dev = dev_get_drvdata(client->parent);
+	struct tegra_drm *tegra = dev->dev_private;
 	struct gr2d *gr2d = to_gr2d(drm);
 	int err;
 
-	err = tegra_drm_unregister_client(dev->dev_private, drm);
+	err = tegra_drm_unregister_client(tegra, drm);
 	if (err < 0)
 		return err;
 
 	host1x_syncpt_free(client->syncpts[0]);
 	host1x_channel_put(gr2d->channel);
 
+	if (gr2d->group) {
+		iommu_detach_group(tegra->domain, gr2d->group);
+		iommu_group_put(gr2d->group);
+	}
+
 	return 0;
 }