From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Subject: Re: pci-mvebu driver on km_kirkwood
Date: Mon, 26 Aug 2013 13:16:15 -0600
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To: Gerlando Falauto <gerlando.falauto@keymile.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>, Andrew Lunn <andrew@lunn.ch>, Jason Cooper <jason@lakedaemon.net>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, Thierry Reding <thierry.reding@gmail.com>, Ezequiel Garcia <ezequiel.garcia@free-electrons.com>, "Longchamp,
 Valentin" <Valentin.Longchamp@keymile.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
List-Id: devicetree@vger.kernel.org

On Mon, Aug 26, 2013 at 04:49:23PM +0200, Gerlando Falauto wrote:

> One last question though... what does then the numbering ("@a,b")
> stand for? I assume if the output of a plain (i.e. no params)
> 'lspci' is

It is device,function, but it is only descriptive and not used by
Linux.
 
> I should only have a "pci@dd,f" node, with the bus numbering being
> imposed by the hierarchy after an actual probing, right?
> So the actual bus number is never listed in the device tree (whereas
> the "@device,function" is). Is that right?

The reg must encode the bus number according to the OF format:

               33222222 22221111 11111100 00000000
               10987654 32109876 54321098 76543210
 phys.hi cell: npt000ss bbbbbbbb dddddfff rrrrrrrr
phys.mid cell: hhhhhhhh hhhhhhhh hhhhhhhh hhhhhhhh
 phys.lo cell: llllllll llllllll llllllll llllllll
 
bbbbbbbb is the 8-bit Bus Number
ddddd is the 5-bit Device Number
fff is the 3-bit Function Number

Others are 0.

Jason