linux-kernel - Re: [RFC PATCH v3] irqchip: Add support for Tango interrupt controller

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Date:	Fri, 22 Jan 2016 16:58:07 +0100
From:	Marc Gonzalez <marc_gonzalez@...madesigns.com>
To:	Mans Rullgard <mans@...sr.com>
CC:	Marc Zyngier <marc.zyngier@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux ARM <linux-arm-kernel@...ts.infradead.org>,
	Sebastian Frias <sf84@...oste.net>
Subject: Re: [RFC PATCH v3] irqchip: Add support for Tango interrupt
 controller

On 20/01/2016 19:09, Måns Rullgård wrote:

> Marc Gonzalez <marc_gonzalez@...madesigns.com> writes:
> 
>> On 20/01/2016 17:38, Måns Rullgård wrote:
>>
>>> Marc Gonzalez <marc_gonzalez@...madesigns.com> writes:
>>>
>>>> On 20/01/2016 17:25, Måns Rullgård wrote:
>>>>
>>>>> Marc Zyngier <marc.zyngier@....com> writes:
>>>>>
>>>>>> On 20/01/16 16:10, Måns Rullgård wrote:
>>>>>>
>>>>>>> Marc Zyngier <marc.zyngier@....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."
>>>
>>> That's going to get very messy since the generic irqchip code needs all
>>> the registers as offsets from a common base address.
>>
>> The two suggestions are over my head at the moment.
>>
>> Do you want to submit v4 and have Marc Z take a look?
> 
> Done.  If this isn't acceptable either, I'm out of ideas that don't end
> up being far uglier than anything suggested so far.

With your latest patch, can I drop the ranges property?

Regards.