Questions on interrupt vector assignment on MPC8641D
Tiejun.Chen at windriver.com
Wed Sep 22 10:36:43 EST 2010
> -----Original Message-----
> linuxppc-dev-bounces+tiejun.chen=windriver.com at lists.ozlabs.or
> [mailto:linuxppc-dev-bounces+tiejun.chen=windriver.com at lists.o
> zlabs.org] On Behalf Of Scott Wood
> Sent: Wednesday, September 22, 2010 6:07 AM
> To: Anderson, Trevor
> Cc: david.hagood at gmail.com; linuxppc-dev at lists.ozlabs.org
> Subject: Re: Questions on interrupt vector assignment on MPC8641D
> On Tue, 21 Sep 2010 17:37:15 -0400
> "Anderson, Trevor" <tanderson at curtisswright.com> wrote:
> > IRQ assignments for MPC8641D are "virtual",
> This is true for powerpc in general.
> > meaning "made up" and quite difficult to determine by
> looking through code.
> > But I believe the plan goes something like this:
> > IRQ
> > ---------
> > 0 No interrupt
> > 1 - 15 External interrupts (only 1..12 would be used)
> > 16 - 127 Internal interrupts - see Table 9-2 of
> 8641D ref man,
> > Add 15 to the numbers shown
> > 128 - 255 Yours, or your BSP's, to do with as you like
> > 256 - 511 Message Signaled Interrupts
> > If you look in the sample device trees for 8641 cards
> you'll see that
> > the interrupt values cited there for various devices match
> the 16..127
> > group above.
> There are two different numberspaces involved here.
> The MPIC interrupt numberspace in the device tree (which is
> not virtual; it is a private numberspace to MPIC) is based on
> the offset of the registers for that interrupt source.
> External interrupts start at zero (which is valid), internal
> at 16, and special things like MSIs at higher numbers (I
> don't think it's quite 256).
This should be depend on the given platform. For example 0xe0~0xe7 are
ranged for MSI on Freescale targets. And it can avoid easily to conflict
those used lower numbers when the special MSI interrupt numbers are
> The numberspace for virtual interrupts, which is what you
> pass to request_irq(), is dynamically allocated. You
> shouldn't need to know anything about it other than that zero
> is invalid, and you get the virtual IRQ from
> irq_of_parse_and_map() or another such mapping function.
> In neither case is there a range that is set aside for you
> "to do with as you like". If you have another interrupt
> controller and need a block of virtual interrupts, register
> the controller with
> irq_alloc_host() and you'll get a block assigned.
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