FDT for MPC5200, CPU revision, MSCAN

FDT for MPC5200, CPU revision, MSCAN

[Wolfgang Grandegger]

Hello,

is there a way to distinguish the CPU revision (Rev.A vs. Rev.B) of the 
MPC5200, preferably at run time? Or should this be defined in the FDT?
I ask, because some settings depend on the CPU revision due to hardware 
bugs, like the clock source used for MSCAN.

Thanks.

Wolfgang.

Re: FDT for MPC5200, CPU revision, MSCAN

[Wolfgang Grandegger]

Wolfgang Grandegger wrote:
> Hello,
> 
> is there a way to distinguish the CPU revision (Rev.A vs. Rev.B) of the 
> MPC5200, preferably at run time? Or should this be defined in the FDT?
> I ask, because some settings depend on the CPU revision due to hardware 
> bugs, like the clock source used for MSCAN.

I found the information here:

$ cat Documentation/powerpc/mpc52xx-device-tree-bindings.txt
...
The 5200B is almost the same as the 5200, but not quite.  It fixes
silicon bugs and it adds a small number of enhancements.  Most of the
devices either provide exactly the same interface as on the 5200.  A few
devices have extra functions but still have a backwards compatible mode.
To express this infomation as completely as possible, 5200B device trees
should have two items in the compatible list;
"mpc5200b-<device>\0mpc5200-<device>".  It is *strongly* recommended
that 5200B device trees follow this convention (instead of only listing
the base mpc5200 item).
...

Sorry for the noise.

Wolfgang.

Re: FDT for MPC5200, CPU revision, MSCAN

[Grant Likely]

On 4/20/07, Wolfgang Grandegger <wg@grandegger.com> wrote:
> Wolfgang Grandegger wrote:
> > Hello,
> >
> > is there a way to distinguish the CPU revision (Rev.A vs. Rev.B) of the
> > MPC5200, preferably at run time? Or should this be defined in the FDT?
> > I ask, because some settings depend on the CPU revision due to hardware
> > bugs, like the clock source used for MSCAN.

This stuff is defined in the device tree.  If you need to detect the
version at runtime, then ideally your bootloader will read the PVR/SVR
to determine the chip version and then pass the correct FDT to the
kernel.

> I found the information here:
>
> $ cat Documentation/powerpc/mpc52xx-device-tree-bindings.txt
<snip>
> Sorry for the noise.

Not noise; good question.

g.

-- 
Grant Likely, B.Sc. P.Eng.
Secret Lab Technologies Ltd.
grant.likely@secretlab.ca
(403) 399-0195

Re: FDT for MPC5200, CPU revision, MSCAN

[Wolfgang Grandegger]

Grant Likely wrote:
> On 4/20/07, Wolfgang Grandegger <wg@grandegger.com> wrote:
>> Wolfgang Grandegger wrote:
>> > Hello,
>> >
>> > is there a way to distinguish the CPU revision (Rev.A vs. Rev.B) of the
>> > MPC5200, preferably at run time? Or should this be defined in the FDT?
>> > I ask, because some settings depend on the CPU revision due to hardware
>> > bugs, like the clock source used for MSCAN.
> 
> This stuff is defined in the device tree.  If you need to detect the
> version at runtime, then ideally your bootloader will read the PVR/SVR
> to determine the chip version and then pass the correct FDT to the
> kernel.

OK, I already realized the revision field in the DTS.

>> I found the information here:
>>
>> $ cat Documentation/powerpc/mpc52xx-device-tree-bindings.txt
> <snip>
>> Sorry for the noise.
> 
> Not noise; good question.

OK, then more questions for MSCAN related properties. The clock source 
for MSCAN is either derived from IPB or directly from the oscillator 
clock via CLKSRC bit. I guess that the property "system-clock" should 
provide that frequency:

$ cat Documentation/powerpc/mpc52xx-device-tree-bindings.txt
...
system-frequency        int             Fsystem frequency; source of all
                                         other clocks.

It needs also to be defined by the boot loader.

Thanks.

Wolfgang.