On Fri, Jun 10, 2016 at 05:37:30PM +0200, Sebastian Frias wrote: > We are trying to write a driver for an interrupt controller (actually more of > a crossbar) for an ARM-based SoC. > This IRQ crossbar has 128 inputs and 24 outputs, the outputs are connected > directly to the GIC. > The idea is that the GIC handles everything, and just request a mapping from > an IRQ number (0...127, from a device's DT entry) into one of its 24 input > lines. > > By looking at current code (4.7-rc1) there seems to be a driver > (drivers/irqchip/irq-crossbar.c) that provides similar functionality. > The driver uses hierarchical irq domains (since commit 783d31863fb8 "irqchip: > crossbar: Convert dra7 crossbar to stacked domains") which we believe we > don't need because the only controller is the GIC. > However the API used previously, register_routable_domain_ops(), was removed > with commit a5561c3e845c "irqchip: gic: Get rid of routable domain". > > Trying to use the driver with hierarchical domains (after modifications for > our SoC), results on the kernel being blocked at some point: > > [ 0.041524] ThumbEE CPU extension supported. > [ 0.041589] Registering SWP/SWPB emulation handler > [ 0.052022] Freeing unused kernel memory: 12364K (c029b000 - c0eae000) > [ 0.074084] random: dbus-uuidgen urandom read with 0 bits of entropy > available > > We've put logs on the different domain_ops calls (alloc, free, translate) but > they are not called, even if the DT is supposed to tell devices to take > interrupts from this controller (*). > > Do you have suggestions on what APIs should be used, further reading/examples > and/or pointers on how debug this (logs to enable, things to look for, etc.)?
Well irq-crossbar.c seems to be very specific to the crossbar in TI chips which handle lots of inputs and lots of outputs to multiple receivers (not just the GIC) as far as I have understood it. Also, unless you modified the IRQCHIP_DECLARE at the end, I see nothing in your dtb that would match the driver at all. And even if that did match, is your crossbar at all register compatible with the TI design? irq-crossbar might be a good example for how to write such a driver, but I wouldn't have much hope of it being useful as a generic driver, never mind the unfortunate name the source file has. I suspect ti-irq-crossbar.c would have been much more appropriate. -- Len Soremsem
