Re: OF device mappings

[Grant Likely <grant.likely@secretlab.ca>]

On Sat, Feb 28, 2009 at 10:46 AM, Gary Thomas <gary@mlbassoc.com> wrote:
> Still looking for some help... =A0I need to be able to locate
> the kernel platform_device which corresponds to an instance
> from my OF tree. =A0Basically, I have a [somewhat] unrelated
> driver which needs to know these things, so the drivers in
> question should not have to be affected.
>
> In particular, I'm working with the net/dsa drivers (Distributed
> Switch Architecture) which need access to the network driver as
> well as the MII/MDIO bus driver. =A0It doesn't make sense to tie
> those drivers back to DSA, but rather let the DSA driver find
> its way to them.
>
> I've defined this in by DTS tree:
> =A0 =A0 =A0 =A0lan1 {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0cell-index =3D <0x01>;

Side note, why do you have cell-index here?  I suspect that you're
using it incorrectly.

> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0compatible =3D "marvell,m88e609x";
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0net_dev =3D "fsl-gianfar.0";
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0mii_bus =3D "fsl-gianfar_mdio.14";

These two lines don't make much sense.  They are encoding Linux
internal details with could very well change in the future.

> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0net_devX =3D <&eth0>;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0mii_busX =3D <&mii_bus>;

This is the right thing to do.  This give you the phandle to the relevant n=
ode.

Once you have a handle to the node, you can iterate through the
of_platform bus devices and look for a node which has a matching node
pointer stored in archdata.  That will give you a struct device which
is contained by a struct of_device (note well: this will give you an
of_device, not a platform_device.)

I'm working on a set of patches which should make this much easier.
I'll try to remember to CC you when I post them to the list.

> =A0 =A0 =A0 =A0};
> ... two ways to find the same node.
>
> Using 'net_dev' (which I admit is pretty hokey), I can look
> up the corresponding platform device, which does work for
> the DSA layer. =A0What I want is to be able to get to this
> from the 'net_devX' pointer, but I don't seem to be able
> to get out of the OF tree and into the actual platform
> device tree to find the appropriate instance.
>
> Any pointers?
>
> Thanks
>
> --
> ------------------------------------------------------------
> Gary Thomas =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 | =A0Consulting for the
> MLB Associates =A0 =A0 =A0 =A0 =A0 =A0 =A0| =A0 =A0Embedded world
> ------------------------------------------------------------
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--=20
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.