From mboxrd@z Thu Jan 1 00:00:00 1970 From: Palmer Dabbelt Subject: [PATCH 2/3] dt-bindings: interrupt-controller: RISC-V local interrupt controller docs Date: Fri, 22 Jun 2018 16:20:05 -0700 Message-ID: <20180622232006.12158-3-palmer@sifive.com> References: <20180622232006.12158-1-palmer@sifive.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180622232006.12158-1-palmer@sifive.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+glpr-linux-riscv=m.gmane.org@lists.infradead.org To: tglx@linutronix.de, jason@lakedaemon.net, marc.zyngier@arm.com, robh+dt@kernel.org, mark.rutland@arm.com Cc: devicetree@vger.kernel.org, aou@eecs.berkeley.edu, Palmer Dabbelt , linux-kernel@vger.kernel.org, Palmer Dabbelt , linux-riscv@lists.infradead.org, shorne@gmail.com List-Id: devicetree@vger.kernel.org From: Palmer Dabbelt This patch adds documentation on the RISC-V local interrupt controller, which is a per-hart interrupt controller that manages all interrupts entering a RISC-V hart. This interrupt controller is present on all RISC-V systems. Signed-off-by: Palmer Dabbelt --- .../interrupt-controller/riscv,cpu-intc.txt | 41 ++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt diff --git a/Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt b/Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt new file mode 100644 index 000000000000..61900e2e3868 --- /dev/null +++ b/Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt @@ -0,0 +1,41 @@ +RISC-V Hart-Level Interrupt Controller (HLIC) +--------------------------------------------- + +RISC-V cores include Control Status Registers (CSRs) which are local to each +hart and can be read or written by software. Some of these CSRs are used to +control local interrupts connected to the core. Every interrupt is ultimately +routed through a hart's HLIC before it interrupts that hart. + +The RISC-V supervisor ISA manual specifies three interrupt sources that are +attached to every HLIC: software interrupts, the timer interrupt, and external +interrupts. Software interrupts are used to send IPIs between cores. The +timer interrupt comes from an architecturally mandated real-time timer that is +controller via SBI calls and CSR reads. External interrupts connect all other +device interrupts to the HLIC, which are routed via the platform-level +interrupt controller (PLIC). + +All RISC-V systems that conform to the supervisor ISA specification are +required to have a HLIC with these three interrupt sources present. Since the +interrupt map is defined by the ISA it's not listed in the HLIC's device tree +entry, though external interrupt controllers (like the PLIC, for example) will +need to define how their interrupts map to the relevant HLICs. + +Required properties: +- compatible : "riscv,cpu-intc" +- #interrupt-cells : should be <1> +- interrupt-controller : Identifies the node as an interrupt controller + +Furthermore, this interrupt-controller MUST be embedded inside the cpu +definition of the hart whose CSRs control these local interrupts. + +An example device tree entry for a HLIC is show below. + + cpu1: cpu@1 { + compatible = "riscv"; + ... + cpu1-intc: interrupt-controller { + #interrupt-cells = <1>; + compatible = "riscv,cpu-intc"; + interrupt-controller; + }; + }; -- 2.16.4