iommu/mediatek: Adjust device link when it is sub-common

For MM IOMMU, We always add device link between smi-common and IOMMU HW.
In mt8195, we add smi-sub-common. Thus, if the node is sub-common, we still
need find again to get smi-common, then do device link.
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20220503071427.2285-19-yong.wu@mediatek.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/mtk_iommu.c

@@ -834,7 +834,7 @@ static const struct component_master_ops mtk_iommu_com_ops = {
 static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **match,
 				  struct mtk_iommu_data *data)
 {
-	struct device_node *larbnode, *smicomm_node;
+	struct device_node *larbnode, *smicomm_node, *smi_subcomm_node;
 	struct platform_device *plarbdev;
 	struct device_link *link;
 	int i, larb_nr, ret;
@@ -874,11 +874,21 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 					    component_compare_of, larbnode);
 	}
 
-	/* Get smi-common dev from the last larb. */
-	smicomm_node = of_parse_phandle(larbnode, "mediatek,smi", 0);
-	if (!smicomm_node)
+	/* Get smi-(sub)-common dev from the last larb. */
+	smi_subcomm_node = of_parse_phandle(larbnode, "mediatek,smi", 0);
+	if (!smi_subcomm_node)
 		return -EINVAL;
 
+	/*
+	 * It may have two level smi-common. the node is smi-sub-common if it
+	 * has a new mediatek,smi property. otherwise it is smi-commmon.
+	 */
+	smicomm_node = of_parse_phandle(smi_subcomm_node, "mediatek,smi", 0);
+	if (smicomm_node)
+		of_node_put(smi_subcomm_node);
+	else
+		smicomm_node = smi_subcomm_node;
+
 	plarbdev = of_find_device_by_node(smicomm_node);
 	of_node_put(smicomm_node);
 	data->smicomm_dev = &plarbdev->dev;