[coreboot] Code organization question Re: Next target: ASUS TUSI-M

[Keith Hui]

Hi Joseph,

Okay, now I probably can use some help, at least in how to organize
the code. Below is what I understand up to this point, but feel free
to stop and correct me.

SIS630 is just one chip. All the chipsets we have so far seems to
always have a "northbridge" plus a "southbridge", at least that's how
the coreboot source tree is organized. Northbridge has raminit.c for
initializing (S)DRAM, a chip.h where some stuff got declared - but not
100% sure what, northbridge.c as a "driver" for ramstage for detecting
and enabling PCI resources, as well as building a memory table, and
debug.c with functions needed for CONFIG_DEBUG_RAM_SETUP.

Southbridge has...
bootblock.c for code required to make the whole ROM chip accessible
all ACPI stuff (will be a while before I can get to that)
one ramstage "driver" for each PCI device the bridge supports eg. IDE, USB, LAN
romstage smbus access code for reading SPD

Mainboard has...
devicetree.cb for describing the board's devices

Here are my questions. If the answer can be found in a certain file in
the tree, tell me - I'll read it.

For this single chip chipset, should I put everything into
northbridge, or keep only RAM init and bus scan stuff in
src/northbridge, and put IDE/USB/LAN/SMBus/LPC/ISA etc. in
src/southrbidge? In this scheme where would VGA fit?

SIS630 and my board has onboard VGA that shares memory with main. I
have the VGA BIOS extracted. Do I still need to write code to
initialize it? If so, where in the coreboot tree?

What is the relationship between devicetree.cb, sconfig, parameters
available to be included in cmos.layout, northbridge and southbridge
drivers? Say I need to have add a setting in cmos.layout to
enable/disable the built in LAN, in how many places do I have to
declare this setting? My factory bios writes some known values into
various superio LDNs during early initialization. Can I declare them
in devicetree.cb or I have to write them in C into some early init
code? Also, should I declare devices that can be enabled/disabled
either in software or by jumper?

In declaring devices in devicetree.cb, does "device pci_domain 1..."
means PCI bus 1, like the AGP slot on a 440BX?

The IDE, USB and LAN devices on SIS chipsets so often share the same
PCI IDs and probably the same initialization sequence. There is
currently only one other SIS southbridge in the tree (the 966) but its
IDE has the same 1039:5513 ID as that on the 630. Any way I can share
this code, or I still have to duplicate it? Any chance I can factor it
out like Sil3114?

In the ramstage driver model, what is the relationships between chip.h,

Looking at my factory BIOS disassembly and what coreboot v1 had done,
I am going to have to write some known values into known registers,
both in the northbridge device, "southbridge device", and superio.
Where usually is this done? bootblock_northbridge_init() for
tinybootblock, in the mainboard romstage main(), in raminit.c before
actually doing RAM init? I figure the first option is the earliest and
best opportunity, following factory bios' lead.

I had a long chat the other night with Idwer helping him port coreboot
to intel 865. Figures it's about time I get some help for myself.

Thanks.
Keith

On Wed, Jan 5, 2011 at 5:55 AM, Joseph Smith <joe at settoplinux.org> wrote:
>
>
> On Wed, 5 Jan 2011 00:06:29 -0500, Keith Hui <buurin at gmail.com> wrote:
>> This is the next board I want to port coreboot to. And the three logs
>> are attached. "Sissy" is what I name the machine the board is in,
>> after SiS. :D
>>
>> The flash chip i know for sure is SST 39SF020A. It needs a board
>> enable, for which I have figured out 3 of the 5 operations involved,
>> thanks to Luc's slides up at Phoronix.
>>
>> It used a soldered PLCC32 flash chip. I soldered a socket on myself,
>> and the chip miraclously survived. But I have not been able to get
>> another of the same chip for backup. All my 3 spares are DIP32.
>>
>> Super I/O is IT8705F, already supported. So it looks like all that's
>> needed is porting SiS630 from coreboot v1. I think I would also be the
>> first to port a single chip chipset to v4.
>>
>> Thanks to a previous thread on this list, I got the '630 datasheet,
>> but I don't know for sure what is different between it (the 630) and
>> my chip (630ET).
>>
>> Appreciate all the help I can get for this one.
>
> Sweet! I have a bunch of SIS 630 boards laying around, anything I can do to
> help just let me know :-)
>
> --
> Thanks,
> Joseph Smith
> Set-Top-Linux
> www.settoplinux.org
>
>