linux-kernel - Re: [PATCH 1/2] i2c: i2c-ocores: Add irq support for sparc

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Message-ID: <5087AF40.7090105@gaisler.com>
Date:	Wed, 24 Oct 2012 11:05:04 +0200
From:	Andreas Larsson <andreas@...sler.com>
To:	Peter Korsgaard <jacmet@...site.dk>
CC:	linux-i2c@...r.kernel.org, Jean Delvare <khali@...ux-fr.org>,
	Ben Dooks <ben-linux@...ff.org>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	linux-kernel@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	software@...sler.com
Subject: Re: [PATCH 1/2] i2c: i2c-ocores: Add irq support for sparc

On 10/23/2012 10:13 PM, Peter Korsgaard wrote:
>>>>>> "Andreas" == Andreas Larsson <andreas@...sler.com> writes:
>
>   Andreas> There are no platform resources of type IORESOURCE_IRQ on
>   Andreas> sparc, so the irq number is acquired in a different manner for
>   Andreas> sparc. The general case uses platform_get_irq, that internally
>   Andreas> still uses platform_get_resource.
>
> I have no idea why sparc is being odd in this regard, but assuming this
> is how it's done, I'm fine with this change.
>
> A quick grep doesn't find any other drivers doing this though:
>
> git grep -l archdata.irqs drivers | xargs grep platform_get_irq
>
> Acked-by: Peter Korsgaard <jacmet@...site.dk>

Other drivers that work both on sparc and on other platforms usually use 
irq_of_parse_and_map on a corresponding device_node. For non-sparc 
architectures irq_of_parse_and_map sets up mappings that needs to be 
teared down on module exit. Sparc however has its own version of 
irq_of_parse_and_map that just returns the irq number using archdata.irq[].

I am trying to get through a patch platform_get_irq to work for sparc as 
well. If that eventually goes through, the CONFIG_SPARC stuff can then 
be removed cleanly from this driver withouth having to mess with 
irq_of_parse_and_map and tearing mappings down.

Another solution is to use irq_of_parse_and_map for the of-case if no 
irq was found using platform_get_irq. But that would make for more 
rearrangements and add the need for irq_dispose_mapping to be added on 
module exit as well (even though the disposing would do nothing for sparc).

Cheers,
Andreas Larsson

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