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From: rvaswani@codeaurora.org (rvaswani at codeaurora.org)
To: linux-arm-kernel@lists.infradead.org
Subject: [DT] API to determine if interrupt is PPI or SPI ?
Date: Fri, 27 Jul 2012 13:00:24 -0700 (PDT)	[thread overview]
Message-ID: <8cdb3e7e9dc79635a130214cf6ba1dd4.squirrel@www.codeaurora.org> (raw)
In-Reply-To: <20120727130947.GN559@mudshark.cambridge.arm.com>

> On Fri, Jul 27, 2012 at 01:33:36PM +0100, Rob Herring wrote:
>> On 07/26/2012 02:18 PM, rvaswani at codeaurora.org wrote:
>> > Hello,
>> >
>> > We can specify the interrupt information in the device tree using the
>> arm
>> > gic convention.
>> > Is there an API to read directly the 1st cell and determine if an
>> > interrupt is a PPI or a SPI ? This information is directly relevant to
>> the
>> > driver because it needs to call request_irq or request_percpu_irq
>> based on
>> > this data.
>> >
>> > How should this be done ideally ?
>>
>> Seems a bit strange to me that you would have a h/w block that can be
>> connected either way...
>
> The CPU PMU can be wired as either SPI or PPI. The latter makes more sense
> to
> me but usually (although not exclusively) it's wired using the former.
>
> Will
>

We have the same driver for a hardware for different chipsets and
unfortunately the hardware team decided to connect this GIC interrupt
differently across these chipsets. This leaves us with a software choice
to make.
We could add another property to the device tree (like irq-is-percpu,
irq-is-not-percpu), but that seems redundant.
We were hoping to have an API to tell us the SPI/PPI difference since this
information is already encoded in the interrupt-cells in the device tree
for this device.
Would that be the right way to go or there is something better that can be
done ?

Thanks,
Rohit

-- 
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

WARNING: multiple messages have this Message-ID (diff)
From: rvaswani@codeaurora.org
To: Will Deacon <will.deacon@arm.com>
Cc: "devicetree-discuss@lists.ozlabs.org"
	<devicetree-discuss@lists.ozlabs.org>,
	"rvaswani@codeaurora.org" <rvaswani@codeaurora.org>,
	"grant.likely@secretlab.ca" <grant.likely@secretlab.ca>,
	"davidb@codeaurora.org" <davidb@codeaurora.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [DT] API to determine if interrupt is PPI or SPI ?
Date: Fri, 27 Jul 2012 13:00:24 -0700 (PDT)	[thread overview]
Message-ID: <8cdb3e7e9dc79635a130214cf6ba1dd4.squirrel@www.codeaurora.org> (raw)
In-Reply-To: <20120727130947.GN559@mudshark.cambridge.arm.com>

> On Fri, Jul 27, 2012 at 01:33:36PM +0100, Rob Herring wrote:
>> On 07/26/2012 02:18 PM, rvaswani@codeaurora.org wrote:
>> > Hello,
>> >
>> > We can specify the interrupt information in the device tree using the
>> arm
>> > gic convention.
>> > Is there an API to read directly the 1st cell and determine if an
>> > interrupt is a PPI or a SPI ? This information is directly relevant to
>> the
>> > driver because it needs to call request_irq or request_percpu_irq
>> based on
>> > this data.
>> >
>> > How should this be done ideally ?
>>
>> Seems a bit strange to me that you would have a h/w block that can be
>> connected either way...
>
> The CPU PMU can be wired as either SPI or PPI. The latter makes more sense
> to
> me but usually (although not exclusively) it's wired using the former.
>
> Will
>

We have the same driver for a hardware for different chipsets and
unfortunately the hardware team decided to connect this GIC interrupt
differently across these chipsets. This leaves us with a software choice
to make.
We could add another property to the device tree (like irq-is-percpu,
irq-is-not-percpu), but that seems redundant.
We were hoping to have an API to tell us the SPI/PPI difference since this
information is already encoded in the interrupt-cells in the device tree
for this device.
Would that be the right way to go or there is something better that can be
done ?

Thanks,
Rohit

-- 
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

  reply	other threads:[~2012-07-27 20:00 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-26 19:18 [DT] API to determine if interrupt is PPI or SPI ? rvaswani at codeaurora.org
2012-07-26 19:18 ` rvaswani
2012-07-27 12:33 ` Rob Herring
2012-07-27 12:33   ` Rob Herring
2012-07-27 13:09   ` Will Deacon
2012-07-27 13:09     ` Will Deacon
2012-07-27 20:00     ` rvaswani at codeaurora.org [this message]
2012-07-27 20:00       ` rvaswani

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