[PATCH v3 2/3] ARM: dts: Add nvmem node for BCM2711 bootloader public key

[Tim Gover]

On Fri, 21 Apr 2023 at 08:55, Krzysztof Kozlowski
<krzysztof.kozlowski at linaro.org> wrote:
>
> On 20/04/2023 14:29, Ivan T. Ivanov wrote:
> > From: Tim Gover <tim.gover at raspberrypi.com>
> >
> > Make a copy of the bootloader secure-boot public key available to the OS
> > via an nvmem node. The placement information is populated by the
> > Raspberry Pi firmware[1] if a public key is present in the BCM2711
> > bootloader EEPROM.
> >
> > [1] https://www.raspberrypi.com/documentation/computers/configuration.html#nvmem-nodes
> >
> > Signed-off-by: Tim Gover <tim.gover at raspberrypi.com>
> > [iivanov] Added link to documentation.
> > Signed-off-by: Ivan T. Ivanov <iivanov at suse.de>
> > ---
> >  arch/arm/boot/dts/bcm2711-rpi.dtsi | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/arch/arm/boot/dts/bcm2711-rpi.dtsi b/arch/arm/boot/dts/bcm2711-rpi.dtsi
> > index 98817a6675b9..e30fbe84f9c3 100644
> > --- a/arch/arm/boot/dts/bcm2711-rpi.dtsi
> > +++ b/arch/arm/boot/dts/bcm2711-rpi.dtsi
> > @@ -15,6 +15,7 @@ aliases {
> >               ethernet0 = &genet;
> >               pcie0 = &pcie0;
> >               blconfig = &blconfig;
> > +             blpubkey = &blpubkey;
> >       };
> >  };
> >
> > @@ -67,6 +68,19 @@ blconfig: nvram at 0 {
> >               no-map;
> >               status = "disabled";
> >       };
> > +
> > +     /*
> > +      * RPi4 will copy the binary public key blob (if present) from the bootloader
> > +      * into memory for use by the OS.
> > +      */
> > +     blpubkey: nvram at 1 {
> > +             compatible = "raspberrypi,bootloader-public-key", "nvmem-rmem";
> > +             #address-cells = <1>;
> > +             #size-cells = <1>;
> > +             reg = <0x0 0x0 0x0>;
> > +             no-map;
> > +             status = "disabled";
>
> Why this is disabled? What external resources are missing?
>
> Best regards,
> Krzysztof

These nodes default to disabled because the firmware will not populate
them if the public-key or configuration file are not present.
e.g. There's no requirement to have a bootloader EEPROM on BCM2711.

Tim