[U-Boot] SPL Platdata howto?

[Simon Goldschmidt]

On Fri, Dec 21, 2018 at 10:20 PM Simon Goldschmidt
<simon.k.r.goldschmidt at gmail.com> wrote:
>
>
>
> Am Fr., 21. Dez. 2018, 22:16 hat Simon Glass <sjg at chromium.org> geschrieben:
>>
>> 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.
>
>
> SPI flash actually needs it the other way round. At least the cadence qspi driver I'm using checks for a subnode that describes the flash chip.
>
> I'll see if I can add that to dtoc.

By now I have SPI successfully running with platdata by adding child
arrays to the platdata struct via dtoc.

However, probing the flash chip is not found in 'spi_get_bus_and_cs'
and so the transfer falls back to 100 kHz, which is of course bad.
That code expects a udevice child under the spi udevice. Looks like
that needs more changes than just in dtoc?

Did you have SPI running with platdata on any board, yet?

Regards,
Simon