Re: [PATCH 1/6] iommu/qcom: Use the asid read from device-tree if specified

Rob Clark
2019-09-26T20:06:20Z

On Thu, Sep 26, 2019 at 5:05 AM <kholk11@gmail.com> wrote:
>
> From: AngeloGioacchino Del Regno <kholk11@gmail.com>
>
> As specified in this driver, the context banks are 0x1000 apart.
> Problem is that sometimes the context number (our asid) does not
> match this logic and we end up using the wrong one: this starts
> being a problem in the case that we need to send TZ commands
> to do anything on a specific context.
>
> For this reason, read the ASID from the DT if the property
> "qcom,ctx-num" is present on the IOMMU context node.
>
> Signed-off-by: AngeloGioacchino Del Regno <kholk11@gmail.com>
> ---
> .../devicetree/bindings/iommu/qcom,iommu.txt | 1 +
> drivers/iommu/qcom_iommu.c | 17 ++++++++++++++---
> 2 files changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/iommu/qcom,iommu.txt b/Documentation/devicetree/bindings/iommu/qcom,iommu.txt
> index 059139abce35..98102b323196 100644
> --- a/Documentation/devicetree/bindings/iommu/qcom,iommu.txt
> +++ b/Documentation/devicetree/bindings/iommu/qcom,iommu.txt
> @@ -38,6 +38,7 @@ to non-secure vs secure interrupt line.
> - "qcom,msm-iommu-v1-sec" : secure context bank
> - reg : Base address and size of context bank within the iommu
> - interrupts : The context fault irq.
> + - qcom,ctx-num : The number associated to the context bank

I guess this should be more like:

+ and the following optional properties:
+ - qcom,ctx-num : The number associated to the context bank

(since this is an optional property)

BR,
-R

>
> ** Optional properties:
>
> diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c
> index dadc707573a2..5837556af147 100644
> --- a/drivers/iommu/qcom_iommu.c
> +++ b/drivers/iommu/qcom_iommu.c
> @@ -557,7 +557,8 @@ static int qcom_iommu_of_xlate(struct device *dev, struct of_phandle_args *args)
> * index into qcom_iommu->ctxs:
> */
> if (WARN_ON(asid < 1) ||
> - WARN_ON(asid > qcom_iommu->num_ctxs))
> + WARN_ON(asid > qcom_iommu->num_ctxs) ||
> + WARN_ON(qcom_iommu->ctxs[asid - 1] == NULL))
> return -EINVAL;
>
> if (!fwspec->iommu_priv) {
> @@ -665,7 +666,8 @@ static int qcom_iommu_sec_ptbl_init(struct device *dev)
>
> static int get_asid(const struct device_node *np)
> {
> - u32 reg;
> + u32 reg, val;
> + int asid;
>
> /* read the "reg" property directly to get the relative address
> * of the context bank, and calculate the asid from that:
> @@ -673,7 +675,16 @@ static int get_asid(const struct device_node *np)
> if (of_property_read_u32_index(np, "reg", 0, &reg))
> return -ENODEV;
>
> - return reg / 0x1000; /* context banks are 0x1000 apart */
> + /* Context banks are 0x1000 apart but, in some cases, the ASID
> + * number doesn't match to this logic and needs to be passed
> + * from the DT configuration explicitly.
> + */
> + if (of_property_read_u32(np, "qcom,ctx-num", &val))
> + asid = reg / 0x1000;
> + else
> + asid = val;
> +
> + return asid;
> }
>
> static int qcom_iommu_ctx_probe(struct platform_device *pdev)
> --
> 2.21.0