iommu/exynos: Ensure that SYSMMU is added only once to its master device

This patch prepares Exynos IOMMU driver for deferred probing
support. Once it gets added, of_xlate() callback might be called
more than once for the same SYSMMU controller and master device
(for example it happens when masters device driver fails with
EPROBE_DEFER). This patch adds a check, which ensures that SYSMMU
controller is added to its master device (owner) only once.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/exynos-iommu.c

@@ -1253,7 +1253,7 @@ static int exynos_iommu_of_xlate(struct device *dev,
 {
 	struct exynos_iommu_owner *owner = dev->archdata.iommu;
 	struct platform_device *sysmmu = of_find_device_by_node(spec->np);
-	struct sysmmu_drvdata *data;
+	struct sysmmu_drvdata *data, *entry;
 
 	if (!sysmmu)
 		return -ENODEV;
@@ -1272,6 +1272,10 @@ static int exynos_iommu_of_xlate(struct device *dev,
 		dev->archdata.iommu = owner;
 	}
 
+	list_for_each_entry(entry, &owner->controllers, owner_node)
+		if (entry == data)
+			return 0;
+
 	list_add_tail(&data->owner_node, &owner->controllers);
 	data->master = dev;