Messages in this thread | | | Subject | Re: polarity inversion on LS1021a | From | Marc Zyngier <> | Date | Mon, 4 Dec 2017 15:37:20 +0000 |
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On 04/12/17 15:31, Alexander Stein wrote: > 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. Almost. See my earlier reply. You just need a very minimal driver that only takes care of the polarity thing. Nobody needs to see yet another GIC driver...
M. -- Jazz is not dead. It just smells funny...
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