Platform bus/ppc sys model...

[Kumar Gala]

On Mar 30, 2005, at 7:52 AM, Andrei Konovalov wrote:

> Sylvain Munaut wrote:
>  > Hi,
>  >
> >
> >> Is there some good documentation about how to use the platform bus 
> / ppc
>  >> sys model or is it only possible to read and try to understand the 
> code
>  >> for the freescale devices?
>  >
> >
> > I'm not aware on documentation for the ppc_sys model in particular 
> but
>  > the code is pretty easy to understand/read.
> >
> > Basically you have a ???_devices.c that describe all the devices you 
> can
>  > find in a family of devices (by family I mean basically the same
> > processors but with slightly different options/peripheral), then a
> > ???_sys.c that describe each particular variant with the devices that
> > are really implemented in that variant). Then somewhere in platform 
> init
> > code, you need to identify the ppc system  you're runngin on ( by a
> > identify_ppc_sys_by_id(mfspr(SPRN_SVR)); for e.g. ).
>  >
> > Kumar, if I got it wrong, please correct ;)

thats a pretty fair description.

> Do I understand correct that the ppc_sys model used by 85xx, 83xx, and 
> 52xx
>  SOCs is not so well suited for Virtex-II Pro (which Jakob and me bear 
> in mind)?
>  In case of Xilinx ???_devices.c could be the list of all the IPs 
> supported in linux.
>  But ???_sys.c has little sense as for any given combination of the 
> particular
>  Virtex-II Pro chip and the particular board the set of IPs (as well 
> as the memory
> map, interrupt numbers, some hardware options (if ethernet has SGDMA 
> or not))
>  is not fixed. I.e. ideally we would need some kind of run time system 
> configuration
>  instead of compiled time system configuration implemented by 
> ???_sys.c.

This is correct.  There is nothing that precludes us from building up a 
way to dynamically create the information.  Is there some way to query 
the hardware itself, or is the information implied something else?

- kumar