Dear Thierry Reding,
Thanks for your feedback!
On Mon, 25 Mar 2013 08:58:10 +0100, Thierry Reding wrote:
> That sounds very much like one of the use-cases that were discussed. The
> easiest solution would probably be to add an API to look up an MSI chip
> from a DT phandle, so that the PCIe controller's device node could have
> it as a property, somewhat like this:
>
> msi: interrupt-controller {
> };
>
> pcie-controller {
> ...
> marvell,msi = <&msi>;
> ...
> };
I'm not sure how to handle this msi interrupt controller with the main
interrupt controller. For now, I have:
mpic: interrupt-controller@d0020000 {
reg = <0xd0020a00 0x2d0>,
<0xd0021070 0x58>;
};
[...]
soc {
interrupt-parent = <&mpic>;
[...]
};
And the MSI interrupt controller shares the same registers as the MPIC.
So should it be something like:
interrupt-controller {
reg = <0xd0020a00 0x2d0>,
<0xd0021070 0x58>;
mpic {
/* Not sure what to have here */
};
msi {
/* Here either */
};
};
soc {
interrupt-parent = <&mpic>;
pcie-controller {
marvell,msi = <&msi>;
};
};
Or some other idea?
> Then add some basic infrastructure to register the MSI chip with a
> global list, call that from the interrupt controller initialization:
>
> ...
> msi_chip_add(&msi);
> ...
>
> And finally look it up from the PCIe controller driver:
>
> node = of_parse_phandle(dev->of_node, "marvell,msi", 0);
> if (node)
> msi = of_find_msi_chip_by_node(node);
>
> That's roughly what other subsystems do. I wrote something similar once
> for backlight devices, though the registration step (msi_chip_add)
> wasn't necessary there since backlight devices all go into a common
> struct class so class_find_device() can be used instead of going through
> a separate registry.
Ok, that part sounds good to me. I'm still unsure about the DT
representation, though (see above), and experience has shown that's
it's a pretty good idea to discuss a little bit the DT representation
before going on with some code :)
Thanks again for your feedback!
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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