How to get revision and serial numbers with device tree?

[Arnd Bergmann]

On Thursday 27 September 2012, Lauri Hintsala wrote:
> 
> /proc/cpuinfo contains revision and serial numbers. They are got from 
> ATAGs when device tree is disabled. How are they managed when device 
> tree is in use? On my imx28 based board they are zeros.

Right, we don't currently interpret a serial number from the device tree.
At least IBM uses a "system-id" property in the root node for the serial
number, and we could theoretically show this in /proc/cpuid, but I don't
think any of the ARM systems currently fill this correctly, and it is
a string property, so we can't use it interchangeably with the integer
in the ATAGs.

	Arnd