On 30/04/2019 21:25, Rob Herring wrote: > On Tue, Apr 30, 2019 at 10:34 AM Marc Zyngier <marc.zyngier@xxxxxxx> wrote: >> >> On 30/04/2019 16:02, Rob Herring wrote: >>> On Tue, Apr 30, 2019 at 7:13 AM Geert Uytterhoeven >>> <geert+renesas@xxxxxxxxx> wrote: >>>> >>>> Add DT bindings for the Renesas RZ/A1 Interrupt Controller. >>>> >>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> >>>> --- >>>> v2: >>>> - Add "renesas,gic-spi-base", >>>> - Document RZ/A2M. >>>> --- >>>> .../renesas,rza1-irqc.txt | 30 +++++++++++++++++++ >>>> 1 file changed, 30 insertions(+) >>>> create mode 100644 Documentation/devicetree/bindings/interrupt-controller/renesas,rza1-irqc.txt >>>> >>>> diff --git a/Documentation/devicetree/bindings/interrupt-controller/renesas,rza1-irqc.txt b/Documentation/devicetree/bindings/interrupt-controller/renesas,rza1-irqc.txt >>>> new file mode 100644 >>>> index 0000000000000000..ea8ddb6955338ccd >>>> --- /dev/null >>>> +++ b/Documentation/devicetree/bindings/interrupt-controller/renesas,rza1-irqc.txt >>>> @@ -0,0 +1,30 @@ >>>> +DT bindings for the Renesas RZ/A1 Interrupt Controller >>>> + >>>> +The RZ/A1 Interrupt Controller is a front-end for the GIC found on Renesas >>>> +RZ/A1 and RZ/A2 SoCs: >>>> + - IRQ sense select for 8 external interrupts, 1:1-mapped to 8 GIC SPI >>>> + interrupts, >>>> + - NMI edge select. >>>> + >>>> +Required properties: >>>> + - compatible: Must be "renesas,<soctype>-irqc", and "renesas,rza1-irqc" as >>>> + fallback. >>>> + Examples with soctypes are: >>>> + - "renesas,r7s72100-irqc" (RZ/A1H) >>>> + - "renesas,r7s9210-irqc" (RZ/A2M) >>>> + - #interrupt-cells: Must be 2 (an interrupt index and flags, as defined >>>> + in interrupts.txt in this directory) >>>> + - interrupt-controller: Marks the device as an interrupt controller >>>> + - reg: Base address and length of the memory resource used by the interrupt >>>> + controller >>>> + - renesas,gic-spi-base: Lowest GIC SPI interrupt number this block maps to. >>> >>> Why isn't this just an 'interrupts' property? >> >> That's likely because of kernel limitations. The DT code does an >> of_populate() on any device that it finds, parse the "interrupts" >> propertiy, resulting in the irq_descs being populated. >> >> That creates havoc, as these interrupts are not for this device, but for >> something that is connected to it. This is merely a bridge of some sort. > > 'interrupt-map' would avoid that problem I think. I'm afraid it doesn't scale at all. Case in point, the GICv3 ITS. Up to 32bit worth of IDs. How do you represent that using an interrupt-map? Agreed, that's the extreme case, but representing more than a handful of interrupts using an interrupt-map is a pain. > >> Furthermore, this is a rather long established practice: gic-v2m, >> gic-v3-mbi, mediatek,sysirq, mediatek,cirq... All the bits of glue that >> for one reason or another plug onto the GIC use the same method. > > All handling the mapping to the parent in their own way... Yes, and that's the problem. We need a scalable way to describe ranges of interrupts that are "forwarded" (for the lack of a better term), but now "owned" by the the interrupt controller. Thanks, M. -- Jazz is not dead. It just smells funny...
