[RFC 3/3] powerpc: Add DTS file for the Motorola PrPMC2800 platform
David Gibson
david at gibson.dropbear.id.au
Thu Mar 29 10:35:50 EST 2007
On Wed, Mar 28, 2007 at 09:43:16AM -0700, Yoder Stuart-B08248 wrote:
[snip]
> > +
> > + mv64x60 at f1000000 { /* Marvell Discovery */
> > + #address-cells = <1>;
> > + #size-cells = <1>;
> > + #interrupt-cells = <1>;
> > + device_type = "mv64360";
> > + compatible = "mv64x60";
> > + clock-frequency = <7f28155>; /*
> > 133.333333 Mhz */
> > + reg = <f1000000 00010000>;
> > + virtual-reg = <f1000000>;
>
> What is virtual-reg for? I gather it is related to the bootwrapper
> needed virtual addresses for devices reg blocks. But, I counted
> 12 instances of the property in this file. Are all needed by the
> bootwrapper??
That does seem like a lot. The only thing that should need
virtual-reg properties is serial ports. In fact, specifically, only
serial ports that the zImage is actually expected to use.
In fact, with Scott's addition of xlate_reg() to the bootwrapper,
virtual-reg should only be needed on systems that enter the zImage
with MMU on.
> Does anyone where this property came from historically? If it's
> specifically for a Linux bootwrapper the name should reflect
> that-- linux,bootwrapper-reg-vaddr -- or something...
> I also wonder if there is a better place to put this information.
> The device nodes strictly speaking should be describing the devices
> _physical_ characteristics.
Yes, but where else is there? virtual-reg is a hack, but a very
useful one.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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