Re: powerpc/85xx: Add support for the "socrates" board (MPC8544)

[Anton Vorontsov <avorontsov@ru.mvista.com>]

On Tue, Mar 31, 2009 at 09:05:28AM -0600, Grant Likely wrote:
[...]
> >>>>> +       soc8544@e0000000 {
> >>>>> +               #address-cells = <1>;
> >>>>> +               #size-cells = <1>;
> >>>>> +               device_type = "soc";
> >>>> Drop device_type here too.
> >>> Grrr, I just realized that removing the devices type "soc" has broken
> >>> fsl_get_sys_freq(). See:
> >>>
> >>> http://lxr.linux.no/linux+v2.6.29/arch/powerpc/sysdev/fsl_soc.c#L80
> >>>
> >>> We need a quick fix and we could take the occasion to establish a common
> >>> function for the MPC52xx as well, but it's not obvious to me how to find
> >>> the SOC node without the device type property.
> >>
> >> SoC node should have a compatible property, just like everything else.
> >>
> >> compatible = "fsl,mpc8544-immr";  (immr == Internally Memory Mapped Registers)
> >>
> >> Many other boards already do this.
> >
> > Yes, it does, but searching for the SOC node is not straight-forward
> > because there is no common compatibility string but many CPU-specific
> > compatibility strings, e.g. "fsl,mpc8560-immr", etc. Have I missed
> > something?
> 
> Choose a new value ("fsl,mpc-immr" perhaps?), document exactly what it
> means, and add add it to the end of the compatible list.

As Scott Wood once pointed out, IMMR does not exists for MPC85xx
parts. There it's called CCSR.

See this thread:

http://www.mail-archive.com/linuxppc-dev@ozlabs.org/msg12665.html

I still think that
"fsl,mpc83NN-immr", "fsl,soc", "simple-bus" for 83xx
and
"fsl,mpc85NN-ccsr", "fsl,soc", "simple-bus" for 85xx

would be OK, at least to start with. We can always deprecate "fsl,soc"
compatible in favour of something more elegant, but "fsl,soc" should be
just fine to replace device_type = "soc".

Also, there is another good thing about "fsl,soc" -- U-Boot already
finds it for 83xx CPUs. ;-)

-- 
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2