[coreboot] Support for Intel e6xx

Janito Vaqueiro Ferreira Filho janito.vff at gmail.com
Wed Oct 24 20:37:49 CEST 2012


I'm trying to start a port for Intel embedded processors (Atom e6xx),
but I'm having some issues with actually starting the development. I'm
basically doing trial-and-error blind development, and this isn't very
effective =)

I've had some problems with the UART interfaces exported by the SoC
(IIRC it appears to be a clocking issue, solved in the Linux kernel by
a "pch_uart" module), and so I'm currently trying to use a SuperIO
(Winbond W83627HG-W) for serial output.

Still, not much progress. Without knowing what's wrong, I decided to
see if I could get SerialICE working in order to see what's (not?)
happening. I haven't been able to make SerialICE work either, and I
was wondering if there are some tips on how to get it to work.

For starters, I added a "continue;" statement right after printing
"\n> ", which should make it an infinite loop for printing ">" lines.

For mainboard initialization, I've created a separate target on the
Kconfig file, and created the southbridge_init() and superio_init()
functions (and the chipset_init() function, calling the other two).

For the southbridge, I'm just setting up the RCBA. And for the
SuperIO, I'm following the same code other mainboards with similar
SuperIOs. After reading the datasheet, I noticed that the port to
enter extended functions depends on a bit of a specific register
(CR26, HFRAS bit), so I actually set it up to configure the port
twice, once for port 0x2e and once for port 0x4e. Would this introduce
any problems?

This still didn't work, and from the datasheets there might be some
more stuff to set-up (PIRQ routing? Enable continuous SIRQ?). From
what I could understand, the connection is:

CPU -> Root Complex -> ISA PCI bridge (LPC) -> SuperIO

Anyone know if there's more specific stuff that should be configured
before the Serial port?

Any tips regarding development? I can boot a Linux kernel normally, so
I might be able to get some info from there. Any suggestions on what
to look for? Am I at least on the right path?

If I could get SerialICE working things would at least start to get more fun =(

Thanks in advance for any help,


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