[PATCH v2 4/5] iommu/mediatek: Improve safety for mediatek, smi property in larb nodes

[Yong Wu]

No functional change. Just improve safety from dts.

All the larbs that connect to one IOMMU must connect with the same
smi-common. This patch checks all the mediatek,smi property for each
larb, If their mediatek,smi are different, it will return fails.
Also avoid there is no available smi-larb nodes.

Suggested-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
---
 drivers/iommu/mtk_iommu.c | 49 ++++++++++++++++++++++++++-------------
 1 file changed, 33 insertions(+), 16 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index a869d4aee7b3..5e86fd48928a 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -1044,7 +1044,7 @@ 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, *smi_subcomm_node;
+	struct device_node *larbnode, *frst_avail_smicomm_node = NULL;
 	struct platform_device *plarbdev;
 	struct device_link *link;
 	int i, larb_nr, ret;
@@ -1056,6 +1056,7 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 		return -EINVAL;
 
 	for (i = 0; i < larb_nr; i++) {
+		struct device_node *smicomm_node, *smi_subcomm_node;
 		u32 id;
 
 		larbnode = of_parse_phandle(dev->of_node, "mediatek,larbs", i);
@@ -1091,27 +1092,43 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 		}
 		data->larb_imu[id].dev = &plarbdev->dev;
 
+		/* Get smi-(sub)-common dev from the last larb. */
+		smi_subcomm_node = of_parse_phandle(larbnode, "mediatek,smi", 0);
+		if (!smi_subcomm_node) {
+			ret = -EINVAL;
+			goto err_larbnode_put;
+		}
+
+		/*
+		 * 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;
+
+		if (!frst_avail_smicomm_node) {
+			frst_avail_smicomm_node = smicomm_node;
+		} else if (frst_avail_smicomm_node != smicomm_node) {
+			dev_err(dev, "mediatek,smi is not right @larb%d.", id);
+			of_node_put(smicomm_node);
+			ret = -EINVAL;
+			goto err_larbnode_put;
+		} else {
+			of_node_put(smicomm_node);
+		}
+
 		component_match_add_release(dev, match, component_release_of,
 					    component_compare_of, larbnode);
 	}
 
-	/* Get smi-(sub)-common dev from the last larb. */
-	smi_subcomm_node = of_parse_phandle(larbnode, "mediatek,smi", 0);
-	if (!smi_subcomm_node)
+	if (!frst_avail_smicomm_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);
+	plarbdev = of_find_device_by_node(frst_avail_smicomm_node);
+	of_node_put(frst_avail_smicomm_node);
 	data->smicomm_dev = &plarbdev->dev;
 
 	link = device_link_add(data->smicomm_dev, dev,
-- 
2.18.0