[PATCH v4 02/11] FWU: Add FWU metadata access driver for GPT partitioned block devices

[Sughosh Ganu]

hi Masami,

On Thu, 10 Feb 2022 at 08:45, Masami Hiramatsu
<masami.hiramatsu at linaro.org> wrote:
>
> 2022年2月10日(木) 10:43 Masami Hiramatsu <masami.hiramatsu at linaro.org>:
> >
> > > > > > Of course as I said in the other thread, I would like to put the
> > > > > > dfu_alt_info like information in the devicetree too.
> > > > > > (But it maybe different from this discussion)
> > > > >
> > > > > Just curious, why do you need to define a variable like dfu_alt_info
> > > > > in a device tree. If this has already been described earlier, you can
> > > > > point me to that discussion. Trying to understand what benefit does
> > > > > having the variables defined in a device tree brings. Thanks.
> > > >
> > > > If we can consolidate the configuration information related to the
> > > > firmware layout on the devicetree, it is very easy to understand
> > > > and manage the firmware update only by checking the devicetree.
> > > > Current design is very fragile from the consistency viewpoint,
> > > > because there are 3 different information we are using for FWU,
> > > > Kconfig, devicetree and u-boot env-variables. If one of them
> > > > sets inconsistent value, FWU may not work as we expected.
> > >
> > > I get your point. But I think generating the dfu_alt_info at runtime,
> > > like how it is done for the ST platforms is in general a better
> > > method, as against using a static variable defined in the device tree.
> >
> > Yeah, the GPT based one is able to store this information on the GPT,
> > and it must be a primary definition.
> >
> > > With runtime generation of the variable, the same code can be used on
> > > multiple platforms and can be generated at runtime -- I feel that is
> > > better than defining the variable in every platform's device tree.
> >
> > I don't agree this point at least for non-GPT devices, since the
> > firmware storage layout depends on the platform hardware configuration
> > statically in such cases.
>
> I changed my mind, it can be solved if we have "uuid" property for
> each partition in the devicetree. I will explain later.
>
> > Of course if the device uses GPT to store the firmware, we have to
> > follow the GPT layout and FWU Metadata to find the corresponding
> > firmware partition.
> >
> > > Btw, there is also provision to define the variable(or part of it)
> > > statically through Kconfig variables. As against your concern about
> > > the feature using multiple methods for stating information, it is
> > > indeed valid. But I guess we can have documentation explaining how
> > > each of that information needs to be defined. Thanks.
> >
> > Yeah, even using GPT, we need to set correct UUID to the FWU metadata,
> > and the metadata depends on Kconfig if we keep putting the #of
> > images-per-bank and the #of banks in the Kconfig, and storage
>
> Sorry, I confused. there are "#of images and #of banks per image".
>
> > (controller) is defined in the devicetree.
> >
> > And I still feel this "chain of definitions" seems a bit fragile. This
> > fragile comes from the FWU metadata is not enough self-described (it
> > has no the #of images-per-bank and the #of banks, without this
> > information we can not decode FWU metadata itself.)
> > Anyway, if we can define the #of images-per-bank and the #of banks in
> > the devicetree, we don't need to change the binary but just changing
> > the devicetree for the different products which has different firmware
> > layout. I think that is more flexible.

Do you really feel that using config values for #banks and
#images_per_bank is such a bad idea. With the approach that you
suggest, we will have to use variable sized arrays, and populate the
values in the probe function of every driver. Also, since you are
going to use the same fwu_mdata.h header in your other project, will
you be able to use variable sized arrays there as well. I feel that we
are complicating things without much benefits.

>
> What I would like to suggest is
>
> /* For GPT BLK backend */
> fwu_mdata {
>     compatible = "u-boot,fwu-mdata-gpt";
>     fwu-mdata-store = <&mmc1>;
>     /* No need to specify the mdata partition, because it finds the
> mdata by partition type uuid. */
>     banks = <2>;
>     images-per-bank = <1>;
> };
>
> /* For SF backend */
> fwu_mdata {
>     compatible = "u-boot,fwu-mdata-sf";
>     fwu-mdata-store = <&spi-flash0>;
>     mdata-offsets = <500000, 520000>; /* Or specified by partition label? */
>     banks = <6>;
>     images-per-bank = <1>;
> };

Looks good overall. Should the mdata-offsets property be instead
mdata-parts, where we define the start offset and size of the metadata
partitions. Or are we going to figure out the size of the metadata
partition through some other mechanism.

Also, do are using a different compatible string for every type of
storage device type. Can we not do with a common string instead? I
understand your reasoning here, of trying to identify the driver at
runtime. Just that I wonder if we are going to build multiple drivers
for a platform. Although I do not have a strong opinion on this.

>
> Note that this is only for the metadata, the real firmware layout issue
> still exists. If we can add "uuid" property for the fixed-partitions node
> as a additional property, e.g.
>
> spi-flash at 0 {
>    partitions {
>        compatible = "fixed-partitions";
>        ...
>        uuid = "aaaaaaaa-bbbb-cccc-dddd-eeeeffffgggg";
>        ...
>        partition at 600000 {
>            label = "Firmware-Bank0";
>            reg = <600000, 400000>;
>            uuid = "12345678-aaaa-bbbb-cccc-0123456789ab";
>        };
>        ...
>    };
> };
>
> Then we can decode the real fwu-mdata and find corresponding
> partitions, and able to build dfu_alt_info in runtime.

This is a sound idea. With this method, we can still use the GUIDs in
the metadata structure, and map those with the partitions using the
above nodes. Only question is, are these partition
nodes(partition at 600000) standard, and are defined for all platforms,
for all type of devices(like NOR, Nand). If so, this scheme will work.

-sughosh

>
> What would you think?
>
> Thank you,
>
> >
> > Thank you,
> >
> > >
> > > -sughosh
> > >
> > > >
> > > > That is my impression felt from porting AB update on the DeveloperBox platform.
> > > >
> > > > Thank you,
> > > >
> > > > >
> > > > > -sughosh
> > > > >
> > > > > >
> > > > > > Thank you,
> > > > > >
> > > > > >
> > > > > > > +                       ret = 0;
> > > > > > > +               }
> > > > > > > +       }
> > > > > > > +
> > > > > > > +       return ret;
> > > > > > > +}
> > > > > > > +
> > > > > > > +static int fwu_mdata_gpt_blk_probe(struct udevice *dev)
> > > > > > > +{
> > > > > > > +       int ret;
> > > > > > > +       struct udevice *mdata_dev = NULL;
> > > > > > > +
> > > > > > > +       ret = fwu_get_mdata_device(&mdata_dev);
> > > > > > > +       if (ret)
> > > > > > > +               return ret;
> > > > > > > +
> > > > > > > +       dev_set_priv(dev, mdata_dev);
> > > > > > > +
> > > > > > > +       return 0;
> > > > > > > +}
> > > > > > > +
> > > > > > > +static const struct fwu_mdata_ops fwu_gpt_blk_ops = {
> > > > > > > +       .get_image_alt_num = fwu_gpt_get_image_alt_num,
> > > > > > > +       .mdata_check = fwu_gpt_mdata_check,
> > > > > > > +       .get_mdata = fwu_gpt_get_mdata,
> > > > > > > +       .update_mdata = fwu_gpt_update_mdata,
> > > > > > > +};
> > > > > > > +
> > > > > > > +static const struct udevice_id fwu_mdata_ids[] = {
> > > > > > > +       { .compatible = "u-boot,fwu-mdata" },
> > > > > >
> > > > > > > +       { }
> > > > > > > +};
> > > > > > > +
> > > > > > > +U_BOOT_DRIVER(fwu_mdata_gpt_blk) = {
> > > > > > > +       .name           = "fwu-mdata-gpt-blk",
> > > > > > > +       .id             = UCLASS_FWU_MDATA,
> > > > > > > +       .of_match       = fwu_mdata_ids,
> > > > > > > +       .ops            = &fwu_gpt_blk_ops,
> > > > > > > +       .probe          = fwu_mdata_gpt_blk_probe,
> > > > > > > +};
> > > > > > > diff --git a/include/fwu.h b/include/fwu.h
> > > > > > > index 5a99c579fc..2c7db2dff9 100644
> > > > > > > --- a/include/fwu.h
> > > > > > > +++ b/include/fwu.h
> > > > > > > @@ -43,6 +43,8 @@ int fwu_get_active_index(u32 *active_idx);
> > > > > > >  int fwu_update_active_index(u32 active_idx);
> > > > > > >  int fwu_get_image_alt_num(efi_guid_t image_type_id, u32 update_bank,
> > > > > > >                           int *alt_num);
> > > > > > > +int fwu_get_mdata_device(struct udevice **mdata_dev);
> > > > > > > +int fwu_verify_mdata(struct fwu_mdata *mdata, bool pri_part);
> > > > > > >  int fwu_mdata_check(void);
> > > > > > >  int fwu_revert_boot_index(void);
> > > > > > >  int fwu_accept_image(efi_guid_t *img_type_id, u32 bank);
> > > > > > > --
> > > > > > > 2.17.1
> > > > > > >
> > > > > >
> > > > > >
> > > > > > --
> > > > > > Masami Hiramatsu
> > > >
> > > >
> > > >
> > > > --
> > > > Masami Hiramatsu
> >
> >
> >
> > --
> > Masami Hiramatsu
>
>
>
> --
> Masami Hiramatsu