iommu/omap: Register driver before setting IOMMU ops

BugLink: http://bugs.launchpad.net/bugs/1764762

[ Upstream commit abaa7e5b ]

Move the registration of the OMAP IOMMU platform driver before
setting the IOMMU callbacks on the platform bus. This causes
the IOMMU devices to be probed first before the .add_device()
callback is invoked for all registered devices, and allows
the iommu_group support to be added to the OMAP IOMMU driver.

While at this, also check for the return status from bus_set_iommu.
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/iommu/omap-iommu.c

@@ -1295,6 +1295,7 @@ static int __init omap_iommu_init(void)
 	const unsigned long flags = SLAB_HWCACHE_ALIGN;
 	size_t align = 1 << 10; /* L2 pagetable alignement */
 	struct device_node *np;
+	int ret;
 
 	np = of_find_matching_node(NULL, omap_iommu_of_match);
 	if (!np)
@@ -1308,11 +1309,25 @@ static int __init omap_iommu_init(void)
 		return -ENOMEM;
 	iopte_cachep = p;
 
-	bus_set_iommu(&platform_bus_type, &omap_iommu_ops);
-
 	omap_iommu_debugfs_init();
 
-	return platform_driver_register(&omap_iommu_driver);
+	ret = platform_driver_register(&omap_iommu_driver);
+	if (ret) {
+		pr_err("%s: failed to register driver\n", __func__);
+		goto fail_driver;
+	}
+
+	ret = bus_set_iommu(&platform_bus_type, &omap_iommu_ops);
+	if (ret)
+		goto fail_bus;
+
+	return 0;
+
+fail_bus:
+	platform_driver_unregister(&omap_iommu_driver);
+fail_driver:
+	kmem_cache_destroy(iopte_cachep);
+	return ret;
 }
 subsys_initcall(omap_iommu_init);
 /* must be ready before omap3isp is probed */