Messages in this thread | | | From | Alexander Stein <> | Subject | Re: polarity inversion on LS1021a | Date | Mon, 04 Dec 2017 16:31:39 +0100 |
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Hi Rasmus,
On Monday, December 4, 2017, 4:11:06 PM CET Rasmus Villemoes wrote: > The LS1021A has a standard GIC-400, but allows inverting the polarity of > six external interrupt lines via a certain register, effectively > supporting IRQ_TYPE_LEVEL_LOW and IRQ_TYPE_EDGE_FALLING for those. > > I'm trying to figure out how one would add support for this. The patch > below works but is obviously just meant to help show what I mean, so > please don't comment on all the things that are wrong with it. > > It feels wrong to create a whole new irqchip driver copy-pasting the > entire irg-gic.c, but I can't figure out how and where one could hook > into the existing one. Any pointers on how to do this properly will be > greatly appreciated.
In my opinion a new irqchip is still required, but solely for modifying SCFG_INTPCR depending on IRQ_TYPE_* You would need to insert it as a cascading interrupt chip in device tree. You also need to protect accesses to this register using a spinlock. This is at least my idea how I would have done it, though never got time for it.
Best regards, Alexander
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