[U-Boot] suggest on how to convey value of 'CCSRBAR' to user on FSL PPC parts

[Peter Tyser]

On Tue, 2009-08-04 at 09:27 -0500, Kumar Gala wrote:
> On Aug 4, 2009, at 9:24 AM, Wolfgang Denk wrote:
> 
> > Dear Kumar Gala,
> >
> > In message  
> > <7ACC3970-1B73-4828-941C-48C6601A7F80 at kernel.crashing.org> you wrote:
> >> I had two ideas on simple ways to convey the value of CCSRBAR, IMMR,
> >> etc.. on various Freescale PPC SoCs.  Knowing the value is useful in
> >> debugging if you need to dump the register space.  I wanted to see if
> >> people had a preference or other ideas:
> >>
> >> 1. add it as output when we boot:
> >
> > This would be only acceptable when DEBUG is enabled, and even this
> > it's ugly.
> >
> >> 2. add it as a environment variable
> >>
> >> ccsrbar=fe000000
> >
> > Please don't.
> >
> >> I also thought about having it as a command but that seems like a lot
> >> of code w/o any real purpose.
> >
> > I don't understand what exactly you need it for.
> >
> > The information should be part of struct bd_info for all relevant
> > architectures, and struct global_data holds a pointer to bd_info as
> > the first element, and on PowerPC R2 holds a pointer to the global
> > data.
> >
> > So you can easily define a GDB macro to do something like this:
> >
> > (gdb) print/x ((gd_t *)$r2)->bd->bi_immr_base
> 
> I didn't think about it being in the bd.  I can use 'bdinfo' to output  
> its value.

We'd toyed around with adding a "memmap" command which would display
chip select mappings, and/or tlb mappings.  I think lots of people
(especially end-users) would find this info useful as the same issue you
have with determining the CCSR address applies to other memory regions.

The bd_info structure has some of the same data that the memmap command
would show, but it doesn't have info such as bank width, cache
attributes, and only supports mem, NOR flash, CCSR, and SRAM.

Do others think such a command would be useful?

Best,
Peter