Geode GX1 and IRQ tables

[ramesh bios]

Hi, 

Thanks for the hint. I see the BC_XMAP registers
touched in nsc/gx1/gx_setup.inc. 

        .long   BC_XMAP_1, 0x60
        .long   BC_XMAP_2, 0
        .long   BC_XMAP_3, 0

And from the gx1 spec:

---
GX_BASE+800Ch-800Fh BC_XMAP_3 Register (R/W) Default
Value = 00000000h
19:16 F0 F0 Region: Region control field for address
range F0000h to F3FFFh.

Bit Position: Function
3 PCI Accessible: The PCI slave can access this memory
if this bit is set high and if the appropriate Read or
Write Enable
bit is also set high.
2 Cache Enable1: Caching this region of memory is
inhibited if this bit is cleared.
1 Write Enable1: Write operations to this region of
memory are allowed if this bit is set high. If this
bit is cleared, then write
operations in this region are directed to the PCI
master.
0 Read Enable: Read operations to this region of
memory are allowed if this bit is set high. If this
bit is cleared then read
operations in this region are directed to the PCI
master.
---

So 3 looks like the right value to set to enable read
and write. So at first I tried with 0x33333333 just to
see what would happen if I made all those regions
read/write. (I'm still not sure how the gx1 processor
knows what part of SDRAM those regions are mapped to.)
In any case, that results in a hang immediately after
boot. You see just: "LinuxBIOS starting..." Meaning,
you don't see even raminit occur. Then I tried just
0x00030000 and that had the same effect. I then tried
moving the 3 across one by one to see if any would
avoid the hang. But nope, a 3 in any of those nibbles
causes the hang. I then tried to set write only, that
is, a value of 0x2. That does boot. But then one can't
readback the table.

So, I'm stuck. I think I need to figure out how and
where we tell the gx1 what address range maps to the
SDRAM.

--- Ian Smith <ian at abelon.com> wrote:
> Ramesh,
> 
> At 04:02 02/03/2005, ramesh bios wrote:
> >1. Shadow RAM
> >
> >I guess I would need to find a way to tell the
> >northbridge to enable shadow RAM for some range
> around
> >f0000. I looked through the CS5530A datasheet and
> see
> >shadow registers but no mention of shadowing RAM.
> Nor
> >in the GX1 datasheet either. I'm looking for some
> >register in either the GX1 or the CS5530A that
> would
> >enable this. I am looking for some register that
> would
> >enable me to remap the C0000-F0000 address range to
> >somewhere in sdram. Is that the right thing to be
> >looking for?
> 
> I think you may need to look at your settings for
> the BC_XMAP_2 and 
> BC_XMAP_3 registers on the GX1 - these control read
> and write access to the 
> BIOS shadow ram regions.
> 
> >2. Uncompressed payload
> >I'm not sure I understand what this means. Right
> now,
> >my payload is filo. In the build, I see:
> >
> >dd conv=sync bs=196608 if=/bios/filo-0.4.2/filo.elf
> >of=payload.block
> >cat payload.block > romimage
> >
> >Oh, I guess you must mean this stuff:
> >
> >objcopy -O binary linuxbios_c linuxbios_payload.bin
> >./nrv2b e linuxbios_payload.bin
> >linuxbios_payload.nrv2b
> >
> >So I guess there is some kind of compression going
> on
> >there.
> 
> Not sure if you're using Linuxbios V1 or V2 but in
> V1 there is an option in 
> your build config file to turn off compression - you
> probably need 
> something like:
> 
> option CONFIG_COMPRESS=0
> 
> If it's V2 then no doubt there is an equivalent
> there too.
> 
> >Which method would be the right thing to do? I'll
> look
> >at the shadow ram thing first then.
> >
> >Thanks.
> 
> Nope this helps
> 
> Ian
> 
> >--- "Ronald G. Minnich" <rminnich at lanl.gov> wrote:
> > >
> > >
> > > On Tue, 1 Mar 2005, ramesh bios wrote:
> > >
> > > > Strike that. The issue is somewhere with
> > > > copy_pirq_routing_table. IE: why does the copy
> to
> > > > f0000 fail. I had assumed that the 500 address
> was
> > > an
> > > > alternate location that the table was copied
> to.
> > > So
> > > > now, I'm looking at that f000 failure.
> > >
> > >
> > > the copy to f0000 fails because shadow ram is
> not
> > > set up.
> > >
> > > You can fix this one of two ways. One is to
> figure
> > > out how to enable
> > > shadow ram. The second is to make the payload
> > > uncompressed. The copy will
> > > still fail but linux will find the PIRQ table
> > > anyway.
> > >
> > > ron
> > > _______________________________________________
> > > Linuxbios mailing list
> > > Linuxbios at clustermatic.org
> > >
>
>http://www.clustermatic.org/mailman/listinfo/linuxbios
> > >
> >
> >
> >
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