[U-Boot] SPL Platdata howto?

[Simon Glass]

Hi Simon,

On Thu, 20 Dec 2018 at 14:32, Simon Goldschmidt
<simon.k.r.goldschmidt at gmail.com> wrote:
>
> Am 20.12.2018 um 21:53 schrieb Simon Goldschmidt:
> > Am 20.12.2018 um 18:37 schrieb Simon Glass:
> >> Hi Simon,
> >>
> >> On Thu, 20 Dec 2018 at 08:03, Simon Goldschmidt
> >> <simon.k.r.goldschmidt at gmail.com> wrote:
> >>>
> >>> Am 20.12.2018 um 15:49 schrieb Simon Glass:
> >>>> Hi Simon,
> >>>>
> >>>> On Wed, 19 Dec 2018 at 14:06, Simon Goldschmidt
> >>>> <simon.k.r.goldschmidt at gmail.com> wrote:
> >>>>>
> >>>>> Hi,
> >>>>>
> >>>>> while searching for bytes to save in SPL in order to add FIT signature
> >>>>> handling, I am currently trying to get socfpga-gen5 to use OF_PLATDATA.
> >>>>>
> >>>>> To begin, I stripped down socfpga_socrates_defconfig to absolutely
> >>>>> nothing but serial drivers in SPL (with some modifications to the
> >>>>> Kconfig) and enabled DEBUG_UART to see what's going on.
> >>>>>
> >>>>> Now while this config runs OK with a dtb (it just won't boot as drivers
> >>>>> are missing -> "failed to boot from all boot devices"), it does not find
> >>>>> the serial driver after enabling OF_PLATDATA.
> >>>>>
> >>>>> So since serial_rockchip.c already uses OF_PLATDATA and is based on
> >>>>> ns16550 that my socfpga-gen5 platform is using: what do I have to do
> >>>>> besides enabling OF_PLATDATA to get this working?
> >>>>>
> >>>>> I just seems like uclass_first_device does not find any UCLASS_SERIAL
> >>>>> deivce when OF_PLATDATA is enabled.
> >>>>
> >>>> There is the of-plat.txt README.
> >>>
> >>> Yes, I should have mentioned I already read that and still had those
> >>> questions. Kconfig help says README.platdata though. We probably should
> >>> update that link.
> >>>
> >>>> Basically the dtoc tool creates U_BOOT_DEVICE() declarations and links
> >>>> them with SPL. These should show up in your image and therefore be
> >>>> bound. You can call dm_dump_all() in SPL to see what what devices are
> >>>> bound. I presume you are calling spl_init()?
> >>>>
> >>>> You can look at what dtoc produces. The example serial driver for
> >>>> Rockchip is serial_rockchip.c
> >>>
> >>> I saw that as an example (because I also have an ns16550 compatible on
> >>> my board) but couldn't figure out why it is not bound. By debugging
> >>> 'dm_scan_platdata', 'lists_bind_drivers' and 'device_bind_by_name', by
> >>> now I know the driver names don't match. That is something I did not get
> >>> just by reading of-plat.txt. I'll work on a patch to clarify that document.
> >>
> >> Yes I'd really appreciate some patches here. It is hard to know what
> >> people won't understand and this feature could really do with a more
> >> details docs or a walk-through.
> >>
> >>>
> >>> Right now, serial works. I had to add a new platform specific driver
> >>> just like serial_rockchip though. For DTS, we can pass multiple
> >>> 'compatible' strings, but for platdata, we have to create multiple
> >>> drivers. That's a bit strange when porting boards...
> >>
> >> Yes it is. I'm not sure how to solve that though. Probably dtoc can be
> >> made smarter. Ideally you only need one device of each uclass in SPL.
> >
> > Would it work to use the unchanged 'compatible' string for the '.name'
> > of U_BOOT_DEVICE generated by dtoc? Then the binding of such drivers
> > could change from comparing names to comparing to compatibles. That
> > would make it more DTS-like.
> >
> > Then, I think we could need some kind of fallback code for properties
> > that are optional in the DTS. Maybe we can create defines for each dtd
> > struct so that drivers can test the existence of dtd sturct fields using
> > #ifdef. [Given the special usage, I guess it's OK to assume that theses
> > structs are only used once per DTS so that we don't have to worry about
> > how to solve this for multiple occurrences with different optional
> > parameters?]
> >
> > Oh, and then I think dtb_platdata.py should create the dtd instances as
> > const. I'll prepare a patch for that.
> >
> >>
> >>>
> >>>>
> >>>>>
> >>>>> (And when answering this, keep in mind I need to get MMC and QSPI
> >>>>> drivers working with OF_PLATDATA - I already fixed compiler errors in
> >>>>> those, nothing more.)
> >>>>
> >>>> Yes MMC should be OK, but QSPI might be blazing a bit of a trail.
>
> Hmm, QSPI works as well when hacking the things that the driver wants to
> parse from subnode properties. However, I haven't found a way to access
> the platform data of the spi-flash from the driver.
>
> Maybe we need to somehow make subnodes available in the dt-platdata
> structs to make that work?

There is support for phandles but not for parent relationships. I
suppose it would not be impossible to add that in dtoc with a 'parent'
pointer.

Regards,
Simon


>
> Regards,
> Simon
>
> >>>
> >>> I just wanted to start with QSPI, maybe I'll do MMC first now ;-)
> >
> > And now MMC is working just fine with very small adaptions to the
> > current socfpga_dw_mmc driver! I only hope that this whole thing gives
> > me the bytes I need to implement FIT signatures in SPL...
> >
> > Regards,
> > Simon
> >
> >>>
> >>> Thanks for your hints!
> >>
> >> You're welcome, happy hunting.
> >>
> >> Regards,
> >> Simon
> >>
> >
>