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. > 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... > > Plus, without 'interrupts' walking the hierarchy is broken. > > Erm... Which hierarchy? of_irq_init() expects that an interrupt-controller without an interrupt-parent is the root controller. So you're right. We only need to have an 'interrupt-parent', but not 'interrupts'. Rob
