On Tuesday 01 October 2013 09:48 AM, Rob Herring wrote: > On 10/01/2013 06:13 AM, Sricharan R wrote: >> Hi, >> >> On Monday 30 September 2013 08:39 PM, Rob Herring wrote: >>> On 09/30/2013 08:59 AM, Sricharan R wrote: >>>> Some socs have a large number of interrupts requests to service >>>> the needs of its many peripherals and subsystems. All of the interrupt >>>> requests lines from the subsystems are not needed at the same >>>> time, so they have to be muxed to the controllers appropriately. >>>> In such places a interrupt controllers are preceded by an >>>> IRQ CROSSBAR that provides flexibility in muxing the device interrupt >>>> requests to the controller inputs. >>>> >>>> This series models the peripheral interrupts that can be routed through >>>> the crossbar to the GIC as 'routable-irqs'. The routable irqs are added >>>> in a separate linear domain inside the GIC. The registered routable domain's >>>> callback are invoked as a part of the GIC's callback, which in turn should >>>> allocate a free irq line and configure the IP accordingly. So every peripheral >>>> in the dts files mentions the fixed crossbar number as its interrupt. A free >>>> gic line for that gets allocated and configured when the peripheral's interrupt >>>> is mapped. >>>> >>>> The minimal crossbar driver to track and allocate free GIC lines and configure the >>>> crossbar is added here, along with the DT bindings. >>> Seems like interrupt-map property is what you need here. >>> >>> http://devicetree.org/Device_Tree_Usage#Advanced_Interrupt_Mapping >>> >>> Versatile Express also has an example. >> OK, but the idea was not to tie up the crossbar<->interrupt numbers at the >> DTS level, but to assign it dynamically during runtime. This was one of the >> comments that came up with first crossbar support patches, which was assigning a >> interrupt line to crossbar number in the DTS and setting it up in crossbar probe. > > Is there an actual usecase on a single h/w design that you run out of > interrupts and it is a user decision which interrupts to use? > Yes. There are 240 peripheral interrupts connected out of which 160 can be used in this specific case. > You could fill in the interrupt-map at run-time. It would have to be > early (bootloader or early kernel init) and can't be at request_irq time. > Well all options are tried before coming up to the $subject solution. It was suggested by Thomas in the last review. >> https://lkml.org/lkml/2013/7/18/416 >> >> Since this approach of assigning in DTS was opposed, we moved to IRQCHIP and >> that did not go as well. Finally was asked to handle this as a part of GIC driver with >> a separate domain. >> >> http://www.spinics.net/lists/linux-omap/msg97085.html > > This has nothing to do with the GIC, so it does not belong there. > Well the router makes connections from peripheral to GIC. Thomas can better explain it but I think since its doing irq routing for GIC on a given hardware, I don't see any issue having some generic map/unmap function in GIC. The actual implementation is still outside of GIC. Regards, Sasntosh -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
