From: Matt Sealey <matt@genesi-usa•com>
To: Grant Likely <grant.likely@secretlab•ca>
Cc: linuxppc-dev@ozlabs•org, "S. Fricke" <silvio.fricke@gmail•com>
Subject: Re: [NEWBIE] Interrupt-problem mpc5200
Date: Fri, 14 Sep 2007 14:29:59 +0100 [thread overview]
Message-ID: <46EA8CD7.2050304@genesi-usa.com> (raw)
In-Reply-To: <fa686aa40709111205n5d9f9654m6f2b96d468dfd017@mail.gmail.com>
Grant!
I have a newbie question which I never had properly answered. On the
MPC52xx and specifically regarding the device tree, how are interrupt
numbers assigned?
On Efika (and in the DT docs) it's basically the X Y Z where X is the
type (critical, main, peripheral, sdma), Y is the number of the
interrupt, and Z is it's sense level.
However while X and Z are easy to derive, how do you work out what Y
is meant to be given a device? Is it a bit number in the interrupt
register, or the value of the encoded interrupt register or something
else algorithmically determined?
I am just finding the code in Linux that derives this number fairly
elusive (the irq setup function for the mpc52xx platform is truly
sparse, irq_of_find_and_map isn't much help). Maybe I am just not
looking in the right place but not being an MPC52xx PIC Expert I
wouldn't even know where to start...
--
Matt Sealey <matt@genesi-usa•com>
Genesi, Manager, Developer Relations
Grant Likely wrote:
> On 9/11/07, S. Fricke <silvio.fricke@googlemail•com> wrote:
>> Hello,
>>
>>>> [...]
>>>> intr = mpc52xx_find_and_map("mpc52xx-pic");
>>>> if(!intr) {
>>>> panic(__FILE__ ": mpc52xx-pic - MAP failed");
>>>> }
>>>>
>>>> set_irq_chip(MPC52xx_IRQ2, &my_irq_chip);
>>> You probably don't want to do this (unless you are cascading IRQs to
>>> custom external hardware). All you should need is the call to
>>> request_irq() to register your irq handler, and code in your ISR
>>> handler to clear the interrupt condition.
>>>
>>> You do *NOT* want to program the interrupt controller directly. The
>>> mpc5200 interrupt controller already has a driver. Don't go twiddling
>>> the registers manually.
>> OK!
>>
>> I have tried it before and i get a "-ENOSYS" returned.
>>
>> My code was/is now:
>> --==>
>> request_irq(MPC52xx_IRQ2, intmod_isr, IRQF_DISABLED , "intmod",
>> INTMOD_IRQ_BOARD);
>> <==--
>>
>> I have looked up "kernel/irq/manage.c". "-ENOSYS" is returned on function
>> "setup_irq" because the used irq(MPC52xx_IRQ2) is the same as no_irq_chip.
>>
>> THE MPC52xx_IRQ2 is a excerpt from "include/ppc/mpc52xx.h" (per copy
>> paste), but mpc52xx is (now) a powerpc-arch. What is the desired value for
>> IRQ-2 on a mpc5200b?
>
> The irq number you pass into request_irq is a system-wide irq number;
> it doesn't necessarily map directly onto the MPC52xx irq number.
> Typically, you'd have a node for your device in the device tree which
> has a phandle back to the interrupt node and you would use
> irq_of_parse_and_map() to map it back to a system-wide irq number.
>
> Otherwise, you need to call of_irq_map_raw with the pointer to the
> 52xx interrupt controller node and the interrupt number in the form
> expected by the device tree. (But adding a device tree node for your
> device is far easier).
>
> Cheers,
> g.
>
next prev parent reply other threads:[~2007-09-14 13:28 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-06 13:30 [NEWBIE] Interrupt-problem mpc5200 S. Fricke
2007-09-11 12:41 ` S. Fricke
2007-09-11 14:19 ` Grant Likely
2007-09-11 18:28 ` S. Fricke
2007-09-11 19:05 ` Grant Likely
2007-09-12 18:30 ` S. Fricke
2007-09-12 19:29 ` Grant Likely
2007-09-19 7:16 ` S. Fricke
2007-09-19 14:31 ` Grant Likely
2007-09-14 13:29 ` Matt Sealey [this message]
2007-09-14 14:53 ` Grant Likely
2007-09-14 15:18 ` Matt Sealey
2007-09-14 15:49 ` Grant Likely
2007-09-14 16:04 ` Matt Sealey
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