[U-Boot] usbtty Support on AT91SAM9XXX chipsets

[Remy Bohmer]

Hello Daniel,

>> There are indeed 2 routes:
>> 1. If you need a serial console, you can still use it with the older
>> usbtty code.
>> 2. Adapt the new CDC layer such that it becomes suitable for console
>> purposes as well. I would be happy integrating patches for this in the
>> USB branch. That would allow us to migrate to 1 usb-gadget layer in
>> the future which can be kept close to the linux development.

> If we were to take option 1 then what do you propose would be the easiest
> way of integrating the current usbtty implementation with the AT91 USB
> device. Is a 'wrapper' between the two frameworks practical or would we be
> better off writing a new UDC implementation for AT91 that matches the other
> implementations.

Well, the benefit of writing a wrapper is that new devices can be
integrated with a lot less effort, because it can be almost be
copy-pasted from linux. Bugfixes in Linux can be easier integrated in
U-boot as well.
Writing a new implementation would be code duplication. So, I would
prefer a wrapper.

> For option 2, I think we need to take serial.c and u_serial.c from Linux and
> then make them work with the uBoot console framework. Is this correct?

Yes.

>> > Also, if this is the
>> > way to go, could someone confirm which version of the Linux Gadget
>> > framework ether.c and friends are based on.  It appears to be completely
>> > different to the latest version.
>>
>> It is a port from Linux 2.6.27 to U-boot.
>> Latest kernel changes are not integrated yet. But the port was kept
>> quite close to the original code to make it easier to upgrade later
>> on.
>
> OK, we'll have a look at that version as a starting point. I presume you
> mean the original 2.6.27, not any of the 2.6.27.x series.

OK, 2.6.27, not 2.6.27.x

Kind Regards,

Remy