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

[Grant Likely]

On Wed, Apr 1, 2009 at 1:36 AM, Wolfgang Grandegger <wg at grandegger.com> wrote:
> Anton Vorontsov wrote:
>> On Tue, Mar 31, 2009 at 09:05:28AM -0600, Grant Likely wrote:
>> [...]
>>>>>>>> +       soc8544 at 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. ;-)
>
> Ugh! I just realize the full impact of removing device type "soc". It
> will break compatibility with U-Boot for many boards. Is it worth it?

Yes, I know this.  I'm not asking you to fix all the other boards, but
make sure that it is not required for the new board.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.