[PATCH 1/2] powerpc: document the MPIC device tree binding

[Scott Wood]

On Mon, 17 Jan 2011 18:52:24 -0600
Meador Inge <meador_inge at mentor.com> wrote:

> +** Required properties:
> +
> +   NOTE: Many of these descriptions were paraphrased from [1] to aid
> +         readability.
> +
> +   - name : Specifies the name of the MPIC.

"name" isn't really a property with flat trees.  The appropriate
node name, according to the Generic Names recommendation and ePAPR, is
interrupt-controller.

> +   - device_type : Specifies the device type of this MPIC.  The value 
> of this
> +                   property shall be "open-pic".

Can we drop device_type, and fix the kernel to look for compatible
instead?

> +   - compatible : Specifies the compatibility list for the MPIC.  The 
> property
> +                  value shall include "chrp,open-pic".

ePAPR wants just "open-pic".  And while chrp,open-pic is common in
existing trees, only one platform currently checks for it.

I'd make in "open-pic" in the binding, and have the kernel accept
either one.

> +** Optional properties:
> +
> +   - no-reset : The presence of this property indicates that the MPIC
> +                should not be reset during runtime initialization.
> +   - protected-sources : Specifies a list of interrupt sources that are 
> not
> +                         available for use and whose corresponding vectors
> +                         should not be initialized.  A typical use case for
> +                         this property is in AMP systems where multiple
> +                         independent operating systems need to share 
> the MPIC
> +                         without clobbering each other.
> +

Can we define no-reset as meaning that all vectors are in a sane state
(either directed at other cores, or masked)?

If we do that, maybe we can get rid of protected-sources.

-Scott