automerging branch "kernel.org-palmer-linux/wip-irq-3-plic" into "riscv-all"

# Conflicts:
#	drivers/irqchip/Kconfig
#	drivers/irqchip/Makefile

Author: palmer-dabbelt

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>;
+	};

drivers/irqchip/Kconfig

@@ -385,4 +385,15 @@ config RISCV_INTC
 	   Without a local interrupt controller the system will be unable to
 	   handle any interrupts, including those passed via the PLIC.
 
+config RISCV_PLIC
+	bool "Platform-Level Interrupt Controller"
+	depends on RISCV
+	default y
+	help
+	   This enables support for the PLIC chip found in standard RISC-V
+	   systems.  The PLIC controls devices interrupts and connects them to
+	   each core's local interrupt controller.  Aside from timer and
+	   software interrupts, all other interrupt sources (MSI, GPIO, etc)
+	   are subordinate to the PLIC.
+
 	   If you don't know what to do here, say Y.

drivers/irqchip/Makefile

@@ -88,3 +88,4 @@ obj-$(CONFIG_GOLDFISH_PIC) 		+= irq-goldfish-pic.o
 obj-$(CONFIG_NDS32)			+= irq-ativic32.o
 obj-$(CONFIG_QCOM_PDC)			+= qcom-pdc.o
 obj-$(CONFIG_RISCV_INTC)		+= irq-riscv-intc.o
+obj-$(CONFIG_RISCV_PLIC)		+= irq-riscv-plic.o