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

From: Måns Rullgård
Date: Wed Jan 20 2016 - 11:38:40 EST

Marc Gonzalez <marc_gonzalez@xxxxxxxxxxxxxxxx> writes:

> On 20/01/2016 17:25, Måns Rullgård wrote:
>> Marc Zyngier <marc.zyngier@xxxxxxx> writes:
>>> On 20/01/16 16:10, Måns Rullgård wrote:
>>>> Marc Zyngier <marc.zyngier@xxxxxxx> 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.

Måns Rullgård