[PATCH v7 5/6] iommu/mediatek: Improve safety for mediatek,smi property in larb nodes

From: Yong Wu <yong.wu@mediatek.com>
To: Joerg Roedel <joro@8bytes.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Will Deacon <will@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>, <iommu@lists.linux.dev>,
	<linux-mediatek@lists.infradead.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, Yong Wu <yong.wu@mediatek.com>,
	AngeloGioacchino Del Regno 
	<angelogioacchino.delregno@collabora.com>,
	<mingyuan.ma@mediatek.com>, <yf.wang@mediatek.com>,
	<libo.kang@mediatek.com>, <chengci.xu@mediatek.com>,
	<youlin.pei@mediatek.com>, <anan.sun@mediatek.com>,
	<xueqi.zhang@mediatek.com>, Guenter Roeck <groeck@chromium.org>,
	Dan Carpenter <dan.carpenter@oracle.com>
Subject: [PATCH v7 5/6] iommu/mediatek: Improve safety for mediatek,smi property in larb nodes
Date: Tue, 18 Oct 2022 10:42:57 +0800	[thread overview]
Message-ID: <20221018024258.19073-6-yong.wu@mediatek.com> (raw)
In-Reply-To: <20221018024258.19073-1-yong.wu@mediatek.com>

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@chromium.org>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/iommu/mtk_iommu.c | 53 +++++++++++++++++++++++++++------------
 1 file changed, 37 insertions(+), 16 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 9cbff48f03c0..f7ac102e343f 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -1042,7 +1042,7 @@ 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, *pcommdev;
 	struct device_link *link;
 	int i, larb_nr, ret;
@@ -1054,6 +1054,7 @@ 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);
@@ -1094,27 +1095,47 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 			goto err_larbdev_put;
 		}
 
+		/* 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_larbdev_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;
+
+		/*
+		 * All the larbs that connect to one IOMMU must connect with the same
+		 * smi-common.
+		 */
+		if (!frst_avail_smicomm_node) {
+			frst_avail_smicomm_node = smicomm_node;
+		} else if (frst_avail_smicomm_node != smicomm_node) {
+			dev_err(dev, "mediatek,smi property is not right @larb%d.", id);
+			of_node_put(smicomm_node);
+			ret = -EINVAL;
+			goto err_larbdev_put;
+		} else {
+			of_node_put(smicomm_node);
+		}
+
 		component_match_add(dev, match, component_compare_dev, &plarbdev->dev);
 		platform_device_put(plarbdev);
 	}
 
-	/* 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;
-
-	pcommdev = of_find_device_by_node(smicomm_node);
-	of_node_put(smicomm_node);
+	pcommdev = of_find_device_by_node(frst_avail_smicomm_node);
+	of_node_put(frst_avail_smicomm_node);
 	if (!pcommdev)
 		return -ENODEV;
 	data->smicomm_dev = &pcommdev->dev;
-- 
2.18.0

