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From: Grant Likely <grant.likely@secretlab.ca>
Subject: Re: [PATCH] of: Have of_device_add call platform_device_add rather than device_add
To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Rob Herring <rob.herring@calxeda.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        devicetree-discuss <devicetree-discuss@lists.ozlabs.org>
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Date: Thu, 22 Nov 2012 15:36:21 +0000
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On Wed, 21 Nov 2012 11:14:30 -0700, Jason Gunthorpe <jgunthorpe@obsidianresearch.com> wrote:
> On Wed, Nov 21, 2012 at 06:07:46PM +0000, Grant Likely wrote:
> 
> > > Which is nesting the generic gpio driver under a larger region..
> > 
> > Try two sibling nodes with overlapping addresses. There are powerpc
> > device trees doing that even though it isn't legal by the ofw and
> > epapr specs.
> 
> Both my examples were using sibling nodes in the OF tree.
> 
> 	pex@e0000000 {
> 		device_type = "pci";
> 		ranges = <0x02000000 0x00000000 0x00000000  0xe0000000  0x0 0x8000000>;
> 		bus-range = <0x0 0xFF>;
> 		chip@0 {
> 			ranges = <0x02000000 0x00000000 0x00000000  0x02000000 0x00000000 0x00000000  0x0 0x8000000>;
> 			chip_control@0 {
> 				compatible = "orc,chip,control";
> 				assigned-addresses = <0x02000000 0x0 0x0  0x0 4096>;
> 			};
> 
> 			gpio3: chip_gpio@8 {
> 			        #gpio-cells = <2>;
> 				compatible = "linux,basic-mmio-gpio";
> 				gpio-controller;
> 				reg-names = "dat", "set", "dirin";
> 				assigned-addresses = <0x02000000 0x0 0x8  0x0 4>,
> 				                     <0x02000000 0x0 0xc  0x0 4>,
> 				                     <0x02000000 0x0 0x10  0x0 4>;
> 			};
> 
> Non-conformant yes, but it is the simplest way to get linux to bind
> two drivers to the same memory space.

Hmm... I've not tried it with assigned-address. I tried with two sibling
platform devices using just the 'reg' property. That the kernel will
complain about. For powerpc-only, the patch I posted allows the device
to get registered anyway even though the range incorrectly overlaps.

g.