This patch adds documentation for the platform-level interrupt controller (PLIC) found in all RISC-V systems. This interrupt controller routes interrupts from all the devices in the system to each hart-local interrupt controller. Note: the DTS bindings for the PLIC aren't set in stone yet, as we might want to change how we're specifying holes in the hart list. Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxx> --- .../bindings/interrupt-controller/riscv,plic0.txt | 55 ++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 Documentation/devicetree/bindings/interrupt-controller/riscv,plic0.txt diff --git a/Documentation/devicetree/bindings/interrupt-controller/riscv,plic0.txt b/Documentation/devicetree/bindings/interrupt-controller/riscv,plic0.txt new file mode 100644 index 000000000000..99cd359dbd43 --- /dev/null +++ b/Documentation/devicetree/bindings/interrupt-controller/riscv,plic0.txt @@ -0,0 +1,55 @@ +RISC-V Platform-Level Interrupt Controller (PLIC) +------------------------------------------------- + +The RISC-V supervisor ISA specification allows for the presence of a +platform-level interrupt controller (PLIC). The PLIC connects all external +interrupts in the system to all hart contexts in the system, via the external +interrupt source in each hart's hart-local interrupt controller (HLIC). A hart +context is a privilege mode in a hardware execution thread. For example, in +an 4 core system with 2-way SMT, you have 8 harts and probably at least two +privilege modes per hart; machine mode and supervisor mode. + +Each interrupt can be enabled on per-context basis. Any context can claim +a pending enabled interrupt and then release it once it has been handled. + +Each interrupt has a configurable priority. Higher priority interrupts are +serviced firs. Each context can specify a priority threshold. Interrupts +with priority below this threshold will not cause the PLIC to raise its +interrupt line leading to the context. + +While the PLIC supports both edge-triggered and level-triggered interrupts, +interrupt handlers are oblivious to this distinction and therefor it is not +specific in the PLIC device-tree binding. + +While the RISC-V ISA doesn't specify a memory layout for the PLIC, the +"riscv,plic0" device is a concrete implementation of the PLIC that contains a +specific memory layout. More details about the memory layout of the +"riscv,plic0" device can be found as a comment in the device driver, or as part +of the SiFive U5 Coreplex Series Manual (page 22 of the PDF of version 1.0) +<https://www.sifive.com/documentation/coreplex/u5-coreplex-series-manual/> + +Required properties: +- compatible : "riscv,plic0" +- #address-cells : should be <0> +- #interrupt-cells : should be <1> +- interrupt-controller : Identifies the node as an interrupt controller +- reg : Should contain 1 register range (address and length) +- interrupts-extended : Specifies which contexts are connected to the PLIC, + with "-1" specifying that a context is not present. + +Example: + + plic: interrupt-controller@c000000 { + #address-cells = <0>; + #interrupt-cells = <1>; + compatible = "riscv,plic0"; + interrupt-controller; + interrupts-extended = < + &cpu0-intc 11 + &cpu1-intc 11 &cpu1-intc 9 + &cpu2-intc 11 &cpu2-intc 9 + &cpu3-intc 11 &cpu3-intc 9 + &cpu4-intc 11 &cpu4-intc 9>; + reg = <0xc000000 0x4000000>; + riscv,ndev = <10>; + }; -- 2.13.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
