From mboxrd@z Thu Jan  1 00:00:00 1970
From: marc_gonzalez@sigmadesigns.com (Marc Gonzalez)
Date: Wed, 20 Jan 2016 17:36:57 +0100
Subject: [RFC PATCH v3] irqchip: Add support for Tango interrupt controller
In-Reply-To: <yw1xmvs0qkue.fsf@unicorn.mansr.com>
References: <569CE0F2.1060507@sigmadesigns.com>
 <569D0B80.1010908@sigmadesigns.com> <569D165E.4060004@sigmadesigns.com>
 <569FAFF5.4090909@arm.com> <yw1xr3hcqlix.fsf@unicorn.mansr.com>
 <569FB471.8000909@arm.com> <yw1xmvs0qkue.fsf@unicorn.mansr.com>
Message-ID: <569FB7A9.9080309@sigmadesigns.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 20/01/2016 17:25, M?ns Rullg?rd wrote:

> Marc Zyngier <marc.zyngier@arm.com> writes:
> 
>> On 20/01/16 16:10, M?ns Rullg?rd wrote:
>>
>>> Marc Zyngier <marc.zyngier@arm.com> writes:
>>>
>>>>> +	if (of_property_read_u32(node, "reg", &ctl))
>>>>> +		panic("%s: failed to get reg base", node->name);
>>>>> +
>>>>> +	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
>>>>> +	chip->ctl = ctl;
>>>>> +	chip->base = base;
>>>
>>> As I said before, this assumes the outer DT node uses a ranges
>>> property.  Normally reg properties work the same whether they specify an
>>> offset within an outer "ranges" or have a full address directly.  It
>>> would be easy enough to make this work with either, so I don't see any
>>> reason not to.
>>
>> Yup, that is a good point. I guess Marc can address this in the next
>> round, since we need a DT binding anyway.
> 
> I'd suggest using of_address_to_resource() on both nodes and subtracting
> the start addresses returned.

For my own reference, Marc Zyngier suggested:
"you should use of_iomap to map the child nodes, and not mess with
the parent one."