Re: [PATCH] RFC: interrupt consistency check for OF GPIO IRQs

From: Alexander Holler
Date: Thu Sep 12 2013 - 11:57:52 EST


Am 12.09.2013 17:19, schrieb Stephen Warren:

IRQs, DMA channels, and GPIOs are all different things. Their bindings
are defined independently. While it's good to define new types of
bindings consistently with other bindings, this hasn't always happened,
so you can make zero assumptions about the IRQ bindings by reading the
documentation for any other kind of binding.

Multiple interrupts are defined as follows:

// Optional; otherwise inherited from parent/grand-parent/...
interrupt-parent = <&gpio6>;
// Must be in a fixed order, unless binding defines that the
// optional interrupt-names property is to be used.
interrupts = <1 IRQF_TRIGGER_HIGH> <2 IRQF_TRIGGER_LOW>;
// Optional; binding for device defines whether it must
// be present
interrupt-names = "foo", "bar";

If you need multiple interrupts, each with a different parent, you need
to use an interrupt-map property (Google it for a more complete
explanation I guess). Unlike "interrupts", "interrupt-map" has a phandle
in each entry, and hence each entry can refer to a different IRQ
controller. You end up defining a dummy interrupt controller node (which
may be the leaf node with multiple IRQ outputs, which then points at
itself as the interrupt parent), pointing the leaf node's
interrupt-parent at that node, and then having interrupt-map "demux" the
N interrupt outputs to the various interrupt controllers.
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What a mess. I assume that is the price that bindings don't have to change.

Thanks for clarifying that,

Alexander Holler
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