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Date:   Mon, 8 Mar 2021 19:01:34 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     Boris Brezillon <boris.brezillon@collabora.com>
Cc:     miquel.raynal@bootlin.com, richard@nod.at, robh+dt@kernel.org,
        linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
        Daniele.Palmas@telit.com, bjorn.andersson@linaro.org
Subject: Re: [PATCH v4 2/3] dt-bindings: mtd: Add a property to declare
 secure regions in NAND chips
Message-ID: <20210308133134.GC5457@thinkpad>
References: <20210308054447.28418-1-manivannan.sadhasivam@linaro.org>
 <20210308054447.28418-3-manivannan.sadhasivam@linaro.org>
 <20210308101059.08658fbe@collabora.com>
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On Mon, Mar 08, 2021 at 10:10:59AM +0100, Boris Brezillon wrote:
> On Mon,  8 Mar 2021 11:14:46 +0530
> Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> 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
> > drivers can skip touching them.
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
> >  Documentation/devicetree/bindings/mtd/nand-controller.yaml | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/mtd/nand-controller.yaml b/Documentation/devicetree/bindings/mtd/nand-controller.yaml
> > index d0e422f4b3e0..15a674bedca3 100644
> > --- a/Documentation/devicetree/bindings/mtd/nand-controller.yaml
> > +++ b/Documentation/devicetree/bindings/mtd/nand-controller.yaml
> > @@ -143,6 +143,13 @@ patternProperties:
> >            Ready/Busy pins. Active state refers to the NAND ready state and
> >            should be set to GPIOD_ACTIVE_HIGH unless the signal is inverted.
> >  
> > +      secure-regions:
> > +        $ref: /schemas/types.yaml#/definitions/uint32-matrix
> > +        description:
> > +          Regions in the NAND chip which are protected using a secure element
> > +          like Trustzone. This property contains the start address and size of
> > +          the secure regions present.
> > +
> 
> Since you declare this as a generic property, I think it'd be simpler
> to do the check at the core level.
> 

Hmm, so have the parsing logic in qcom driver and check in core or both parsing
and check in core?

I don't think the first one makes sense.

Thanks,
Mani

> >      required:
> >        - reg
> >  
>