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

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Date:   Thu, 16 Jun 2022 13:42:02 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Will Deacon <will@...nel.org>
CC:     <iommu@...ts.linux-foundation.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, "Yong Wu" <yong.wu@...iatek.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        <mingyuan.ma@...iatek.com>, <yf.wang@...iatek.com>,
        <libo.kang@...iatek.com>, <chengci.xu@...iatek.com>,
        <youlin.pei@...iatek.com>, <anan.sun@...iatek.com>,
        <xueqi.zhang@...iatek.com>, Guenter Roeck <groeck@...omium.org>,
        "Dan Carpenter" <dan.carpenter@...cle.com>
Subject: [PATCH v2 4/5] iommu/mediatek: Improve safety for mediatek, smi property in larb nodes

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@...omium.org>
Signed-off-by: Yong Wu <yong.wu@...iatek.com>
---
 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