Re: [PATCH 2/3] dt-bindings: mtd: Add a property to declare secure regions in Qcom NANDc

Miquel Raynal
2021-02-23T16:50:27Z

Hi Manivannan,

Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> wrote on Mon,
22 Feb 2021 17:32:58 +0530:

> On a typical end product, a vendor may choose to secure some regions in
> the NAND memory which are supposed to stay intact between FW upgrades.
> The access to those regions will be blocked by a secure element like
> Trustzone. So the normal world software like Linux kernel should not
> touch these regions (including reading).
>
> So let's add a property for declaring such secure regions so that the
> driver can skip touching them.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
> Documentation/devicetree/bindings/mtd/qcom,nandc.yaml | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mtd/qcom,nandc.yaml b/Documentation/devicetree/bindings/mtd/qcom,nandc.yaml
> index 84ad7ff30121..7500e20da9c1 100644
> --- a/Documentation/devicetree/bindings/mtd/qcom,nandc.yaml
> +++ b/Documentation/devicetree/bindings/mtd/qcom,nandc.yaml
> @@ -48,6 +48,13 @@ patternProperties:
> enum:
> - 512
>
> + qcom,secure-regions:
> + $ref: /schemas/types.yaml#/definitions/uint32-array
> + description:
> + Regions in the NAND memory which are protected using a secure element
> + like Trustzone. This property contains the start address and size of
> + the secure regions present (optional).

What does this "(optional)" means? If you mean the property is optional
then it should be described accordingly in the yaml file, or am I
missing something?

I wonder if it wouldn't be better to make this a NAND chip node
property. I don't think a qcom prefix is needed as potentially many
other SoCs might have the same "feature".

I'm fine adding support for it in the qcom driver only though.

> +
> allOf:
> - $ref: "nand-controller.yaml#"
>

Thanks,
Miquèl