From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [RFC PATCH 11/13] cpufreq: add xen-cpufreq driver
Date: Fri, 10 Oct 2014 16:19:13 +0100
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To: Jan Beulich <JBeulich@suse.com>
Cc: Tim Deegan <tim@xen.org>, Oleksandr Dmytryshyn <oleksandr.dmytryshyn@globallogic.com>, xen-devel@lists.xen.org, Stefano.Stabellini@citrix.com, Stefano Stabellini <stefano.stabellini@eu.citrix.com>
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On Fri, 2014-10-10 at 13:51 +0100, Jan Beulich wrote:
> >>> On 10.10.14 at 11:59, <Ian.Campbell@citrix.com> wrote:
> > A simple i2c driver (without all the generic framework/bus
> > infrastructure which Linux has) is pretty simple.
> > 
> > I think the biggest complexity would come from i2c busses with both
> > cpufreq and other devices on them and managing the potentially shared
> > accesses.
> 
> And the recently added XENPF_resource_op would seem a pretty
> good candidate for this (except that it requires the Dom0 kernel
> code to stop accessing hardware directly, and instead go through
> this hypercall).

We'd need to introduce a dtb binding for a "pv i2c host controller"
which we would use to replace the actual one for dom0. That might be
doable I think, so long as we take care to preserve the relationships
with other nodes which might reference it.

Ian.