Re: [PATCH 06/24] C6X: devicetree

From: Arnd Bergmann
Date: Tue Sep 13 2011 - 02:44:23 EST


On Monday 12 September 2011 19:20:35 Mark Salter wrote:
> On Mon, 2011-09-12 at 14:11 -0600, Grant Likely wrote:
> > On Wed, Aug 31, 2011 at 05:26:41PM -0400, Mark Salter wrote:
> > > + interrupt-controller;
> > > + #interrupt-cells = <1>;
> > > + compatible = "ti,c64x+core-pic";
> >
> > The interrupt controller isn't addressable? Is it integrated into
> > the CPU?
>
> Yes, that core controller is controlled through registers accessed
> with special-purpose instructions, not MMIO. Other controllers, like
> megamodule and some as-yet unimplemented use MMIO.

Are these instructions specific to the interrupt controller or
do they access a register space that can contain arbitrary
devices?

If there is a separate address space for special devices, it might
be good to describe that in the device tree, like we do for PCI
I/O space.

Arnd
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