Proposal: U-Boot MTD (rewriting old story)

[Simon Glass]

Hi Tom,

On Wed, 4 Aug 2021 at 12:49, Tom Rini <trini at konsulko.com> wrote:
>
> On Wed, Aug 04, 2021 at 10:09:55AM -0600, Simon Glass wrote:
> > Hi Jagan,
> >
> > On Tue, 3 Aug 2021 at 09:01, Jagan Teki <jagan at amarulasolutions.com> wrote:
> > >
> > > Yes, this is the old discussion and triggered again now since we had a
> > > discussion on the last U-Boot contributor call.
> > >
> > > I will brief the main points here, as most of the details are
> > > mentioned in previous threads.
> > >
> > > Here are the couple of old and new implementations on the SPI-NOR side.
> > >
> > > http://u-boot.10912.n7.nabble.com/PATCH-v10-00-27-dm-Generic-MTD-Subsystem-with-SPI-NOR-interface-tt315694.html#none
> > > http://u-boot.10912.n7.nabble.com/PATCH-0-5-mtd-Implement-MTD-UCLASS-use-SPINOR-td419538.html#a419541
> > > https://patchwork.ozlabs.org/project/uboot/cover/20200709111709.68904-1-jagan@amarulasolutions.com/
> > >
> > > Idea is to
> > > 1. Create MTD_UCLASS, already present
> > > 2. Create DM MTD Operations, above patchset does.
> > > 3. Create Flash specific MTD UClass's like
> > >     UCLASS_NAND
> > >     UCLASS_SPI_NAND
> > >     UCLASS_SPI_NOR
> > >     UCLASS_NOR
> > >     UCLASS_UBI
> > > and register to UCLASS_MTD as interface slaves like how MMC, SCSI are
> > > registered to UCLASS_BLK
> > > 4. Sync only respective flash specific code, and drop __UBOOT__
> > > 5. Interface mtd, sf, and nand commands to UCLASS_MTD.
> >
> > This all seems good to me.
> >
> > >
> > > Hard points:
> > > 1. Hard to arrange Linux specific code and drop unneeded _UBOOT_ code,
> > > but possible.
> > > 2. Requires a lot of testing.
> >
> > Let's add simple emulators for NAND, SPI_NAND and UBI. We already have
> > one for SPI_NOR I believe. That will be a good long-term investment.
>
> What are our viable options here via QEMU?

I don't mean QEMU, just sandbox emulators. They are pretty simple to
write and faster/easier to run and debug than qemu.

Regards,
Simon