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

Manivannan Sadhasivam
2021-03-08T05:33:10Z

On Fri, Mar 05, 2021 at 05:36:57PM -0600, Rob Herring wrote:
> On Mon, Feb 22, 2021 at 05:32:58PM +0530, Manivannan Sadhasivam wrote:
> > 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
>
> Don't you need 64-bit regions potentially? Though 4GB should be enough
> for anyone.
>

Yes, given the size of current NAND based systems around, I thought 32 bit is
enough.

> If more than one addr+size, then you need a matrix.
>

Okay.

Thanks,
Mani

> > + 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).
> > +
> > allOf:
> > - $ref: "nand-controller.yaml#"
> >
> > --
> > 2.25.1
> >