[OpenBIOS] usb driver to support usb keyboard

[Mark Cave-Ayland]

On 05/05/14 10:26, BALATON Zoltan wrote:

> On Sun, 4 May 2014, Mark Cave-Ayland wrote:
>> On 03/05/14 10:56, BALATON Zoltan wrote:
>>> On Fri, 3 May 2014, Tarl Neustaedter wrote:
>>>> I'm not volunteering to do the work (lest I hear my boss scream in
>>>> agony), but I suspect this is a case that it just drops in and works.
>>>> Lillian wrote it for the OneLaptop project, and I understand that
>>>> implementation and OpenBios haven't diverged all that much.
>>>
>>> Problem is I don't know where to drop it to try if it works and if it
>>> doesn't I don't know how to debug Forth so I could only shoot in the
>>> dark. I don't even know where to start with this Forth driver.
>
> As this seems to be the preferred way I looked at it again to see if I
> can start trying to integrate the usb2 driver from openfirmwre but I
> still don't see where to start.
>
>> Sadly the PCI code in OpenBIOS is still written in C so there would be
>> some interface work required there.

First place I would look at is in drivers/pci.c and 
drivers/pci-database.c to make sure that the USB host is detected in the 
firmware tree - it should appear without any properties. Next download 
the IEEE1275 PCI bindings and have a look at the words there.

Probably the first place to start is getting the PCI config space 
accesses working; for this you will probably need to implement some 
Forth wrappers around C for the PCI config space access functions from 
the PCI bindings.

>> In terms of testing the code, Forth is an interpreted language so you
>> can literally copy/paste from the source files into a serial console
>> and see what happens ;)  I suspect that the reality will be slightly
>> different though, for example we know that OpenFirmware has behaviours
>> which aren't implemented in OpenBIOS.
>
> The usb driver is split into 75 *.fth files so it's not obvious what to
> paste in a console. Additionally there are some *.bth files that seem to
> build some FCode modules but these are not working on OpenBIOS as they
> contain words that I did not find in OpenBIOS. So I don't know how to
> get OpenBIOS's Forth at least try to interpret these files to see what
> is missing.

In OpenBIOS, files are added into the build.xml file which generates a 
set of Makefiles when running the switch-arch script.

The .bth files are probably used to create FCode blobs, much in the same 
way as the toke utility from the OpenBIOS fcode-utils does. Take a look 
at drivers/build.xml and in particular the vga driver to see how this is 
done, as this was a driver I converted over from C.

> The ohci.bth file looks like this:
>
> ---begin---
> purpose: Load file for OHCI HCD
>
> command: &tokenize &this
> build-now
>
> silent on
>
> begin-tokenizing ohci.fc
>
> FCode-version2
>
> " ohci" encode-string " device_type" property
>
> fload ${BP}/dev/usb2/hcd/ohci/loadpkg.fth
>
> end0
>
> end-tokenizing
> ---end---
>
> and the hcd/ohci/loadpkg.fth referenced here contains more fload
> commands that load the other parts. What is the equivalent in OpenBIOS's
> Forth to do this?

Instead of fload, you should be able to use include instead (see 
forth/bootstrap/start.fs). And for tokenizing, you simply run the Forth 
source code through fcode-utils' toke command.

Also once you start to get a feel for the work and think it's viable, we 
should get Stefan to make sure he's okay with the OpenFirmware license 
with respect to OpenBIOS' GPLv2.


HTH,

Mark.