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

[Matthias Brugger <matthias.bgg@gmail.com>]

On 18/10/2022 04:42, Yong Wu wrote:
> 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>

Reviewed-by: Matthias Brugger <matthias.bgg@gmail.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;