Re: [PATCH v5 3/3] arm: dts: am335x-sancloud-bbe-lite: UEFI SPI export

Tom Rini
2022-12-24T16:51:38Z

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On Sat, Dec 24, 2022 at 12:03:52PM +0000, Paul Barker wrote:
> On 20/12/2022 15:55, Rob Herring wrote:
> > On Wed, Nov 23, 2022 at 05:50:06PM +0000, Paul Barker wrote:
> >> Add properties to the Authenta SPI flash device node to enable access by
> >> a UEFI application using a fixed GUID.
> >>
> >> Signed-off-by: Paul Barker <paul.barker@sancloud.com>
> >> ---
> >> arch/arm/dts/am335x-sancloud-bbe-lite-u-boot.dtsi | 13 ++++++++++---
> >> arch/arm/dts/am335x-sancloud-bbe-lite.dts | 2 +-
> >> 2 files changed, 11 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/arch/arm/dts/am335x-sancloud-bbe-lite-u-boot.dtsi b/arch/arm/dts/am335x-sancloud-bbe-lite-u-boot.dtsi
> >> index 01c105ebb383..6c4ff67f9a4b 100644
> >> --- a/arch/arm/dts/am335x-sancloud-bbe-lite-u-boot.dtsi
> >> +++ b/arch/arm/dts/am335x-sancloud-bbe-lite-u-boot.dtsi
> >> @@ -38,7 +38,14 @@
> >>
> >> &spi0 {
> >> u-boot,dm-pre-reloc;
> >> - channel@0 {
> >> - u-boot,dm-pre-reloc;
> >> - };
> >> +};
> >> +
> >> +&authenta_flash {
> >> + u-boot,dm-pre-reloc;
> >> +
> >> + u-boot,uefi-spi-vendor = "micron";
> >> + u-boot,uefi-spi-part-number = "mt25ql128abb";
> >
> > Looks like a compatible string. Yet, the flash node compatible string,
> > micron,spi-authenta, is not documented (though in use for spidev). So
> > use a compatible string for the flash that is specific to the flash
> > model. I assume there is some reason the specific model is needed?
>
> For context, the UEFI Platform Initialization (PI) spec defines
> EFI_SPI_PART, EFI_SPI_PERIPHERAL and EFI_SPI_IO_PROTOCOL structures.
> I'm referencing v1.7 Errata A. See https://uefi.org/specifications for
> downloads.
>
> The EFI_SPI_PART structure has "Vendor" and "PartNumber" fields. We need
> something to put in those fields and the device tree is the best place
> to store the data. These properties are in the `-u-boot.dtsi` file so
> they won't be submitted to the Linux kernel.

Well, IMHO, this doesn't belong in U-Boot only for forever. Just like
other bindings/properties that we're working on getting merged upstream
and so that there is really Just One Device Tree, this should go
upstream I believe. This might be another case of starts in -u-boot.dtsi
while things get sorted out.

--
Tom

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