On Sat, Mar 6, 2021 at 4:52 AM Rob Herring <robh@xxxxxxxxxx> wrote: > > On Sun, Feb 21, 2021 at 03:07:57PM +0530, Anup Patel wrote: > > The RISC-V CPU idle states will be described in DT under the > > /cpus/riscv-idle-states DT node. This patch adds the bindings > > documentation for riscv-idle-states DT nodes and idle state DT > > nodes under it. > > > > Signed-off-by: Anup Patel <anup.patel@xxxxxxx> > > --- > > .../bindings/riscv/idle-states.yaml | 250 ++++++++++++++++++ > > 1 file changed, 250 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/riscv/idle-states.yaml > > > > diff --git a/Documentation/devicetree/bindings/riscv/idle-states.yaml b/Documentation/devicetree/bindings/riscv/idle-states.yaml > > new file mode 100644 > > index 000000000000..3eff763fed23 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/riscv/idle-states.yaml > > @@ -0,0 +1,250 @@ > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/riscv/idle-states.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: RISC-V idle states binding description > > + > > +maintainers: > > + - Anup Patel <anup.patel@xxxxxxx> > > + > > +description: |+ > > + RISC-V systems can manage power consumption dynamically, where HARTs > > + (or CPUs) [1] can be put in different platform specific suspend (or > > + idle) states (ranging from simple WFI, power gating, etc). The RISC-V > > + SBI [2] hart state management extension provides a standard mechanism > > + for OSes to request HART state transitions. > > + > > + The platform specific suspend (or idle) states of a hart can be either > > + retentive or non-rententive in nature. A retentive suspend state will > > + preserve hart register and CSR values for all privilege modes whereas > > + a non-retentive suspend state will not preserve hart register and CSR > > + values. The suspend (or idle) state entered by executing the WFI > > + instruction is considered standard on all RISC-V systems and therefore > > + must not be listed in device tree. > > + > > + The device tree binding definition for RISC-V idle states described > > + in this document is quite similar to the ARM idle states [3]. > > + > > + References > > + > > + [1] RISC-V Linux Kernel documentation - CPUs bindings > > + Documentation/devicetree/bindings/riscv/cpus.yaml > > + > > + [2] RISC-V Supervisor Binary Interface (SBI) > > + http://github.com/riscv/riscv-sbi-doc/riscv-sbi.adoc > > + > > + [3] ARM idle states binding description - Idle states bindings > > + Documentation/devicetree/bindings/arm/idle-states.yaml > > I'd assume there's common parts we can share. Yes, except few properties most are the same. We can have a shared DT bindings for both ARM and RISC-V but both architectures will always have some architecture specific details (or properties) which need to be documented under arch specific DT documentation. Is it okay if this is done as a separate series ? > > > + > > +properties: > > + $nodename: > > + const: riscv-idle-states > > Just 'idle-states' like Arm. I had tried "idle-states" node name but DT bindings check complaints conflict with ARM idle state bindings. > > > + > > +patternProperties: > > + "^(cpu|cluster)-": > > + type: object > > + description: | > > + Each state node represents an idle state description and must be > > + defined as follows. > > + > > additionalProperties: false okay, will update. > > > + properties: > > + compatible: > > + const: riscv,idle-state > > + > > + local-timer-stop: > > + description: > > + If present the CPU local timer control logic is lost on state > > + entry, otherwise it is retained. > > + type: boolean > > + > > + entry-latency-us: > > + description: > > + Worst case latency in microseconds required to enter the idle state. > > + > > + exit-latency-us: > > + description: > > + Worst case latency in microseconds required to exit the idle state. > > + The exit-latency-us duration may be guaranteed only after > > + entry-latency-us has passed. > > + > > + min-residency-us: > > + description: > > + Minimum residency duration in microseconds, inclusive of preparation > > + and entry, for this idle state to be considered worthwhile energy > > + wise (refer to section 2 of this document for a complete description). > > + > > + wakeup-latency-us: > > + description: | > > + Maximum delay between the signaling of a wake-up event and the CPU > > + being able to execute normal code again. If omitted, this is assumed > > + to be equal to: > > + > > + entry-latency-us + exit-latency-us > > + > > + It is important to supply this value on systems where the duration > > + of PREP phase (see diagram 1, section 2) is non-neglibigle. In such > > + systems entry-latency-us + exit-latency-us will exceed > > + wakeup-latency-us by this duration. > > + > > + idle-state-name: > > + $ref: /schemas/types.yaml#/definitions/string > > + description: > > + A string used as a descriptive name for the idle state. > > + > > + required: > > + - compatible > > + - entry-latency-us > > + - exit-latency-us > > + - min-residency-us > > + > > +additionalProperties: false I will move this up. > > + > > +examples: > > + - | > > + > > + cpus { > > + #size-cells = <0>; > > + #address-cells = <1>; > > + > > + cpu@0 { > > + device_type = "cpu"; > > + compatible = "riscv"; > > + reg = <0x0>; > > + riscv,isa = "rv64imafdc"; > > + mmu-type = "riscv,sv48"; > > + cpu-idle-states = <&CPU_RET_0_0 &CPU_NONRET_0_0 > > + &CLUSTER_RET_0 &CLUSTER_NONRET_0>; > > You should need to add this property to your cpu schema. Okay, will update. > > > + > > + cpu_intc0: interrupt-controller { > > + #interrupt-cells = <1>; > > + compatible = "riscv,cpu-intc"; > > + interrupt-controller; > > + }; > > + }; > > + > > + cpu@1 { > > + device_type = "cpu"; > > + compatible = "riscv"; > > + reg = <0x1>; > > + riscv,isa = "rv64imafdc"; > > + mmu-type = "riscv,sv48"; > > + cpu-idle-states = <&CPU_RET_0_0 &CPU_NONRET_0_0 > > + &CLUSTER_RET_0 &CLUSTER_NONRET_0>; > > + > > + cpu_intc1: interrupt-controller { > > + #interrupt-cells = <1>; > > + compatible = "riscv,cpu-intc"; > > + interrupt-controller; > > + }; > > + }; > > + > > + cpu@10 { > > + device_type = "cpu"; > > + compatible = "riscv"; > > + reg = <0x10>; > > + riscv,isa = "rv64imafdc"; > > + mmu-type = "riscv,sv48"; > > + cpu-idle-states = <&CPU_RET_1_0 &CPU_NONRET_1_0 > > + &CLUSTER_RET_1 &CLUSTER_NONRET_1>; > > + > > + cpu_intc10: interrupt-controller { > > + #interrupt-cells = <1>; > > + compatible = "riscv,cpu-intc"; > > + interrupt-controller; > > + }; > > + }; > > + > > + cpu@11 { > > + device_type = "cpu"; > > + compatible = "riscv"; > > + reg = <0x11>; > > + riscv,isa = "rv64imafdc"; > > + mmu-type = "riscv,sv48"; > > + cpu-idle-states = <&CPU_RET_1_0 &CPU_NONRET_1_0 > > + &CLUSTER_RET_1 &CLUSTER_NONRET_1>; > > + > > + cpu_intc11: interrupt-controller { > > + #interrupt-cells = <1>; > > + compatible = "riscv,cpu-intc"; > > + interrupt-controller; > > + }; > > + }; > > + > > + riscv-idle-states { > > + CPU_RET_0_0: cpu-retentive-0-0 { > > + compatible = "riscv,idle-state"; > > + riscv,sbi-suspend-param = <0x10000000>; > > Not documented. Ahh, I missed this one. I will add it in next patch revision. > > > + entry-latency-us = <20>; > > + exit-latency-us = <40>; > > + min-residency-us = <80>; > > + }; > > + > > + CPU_NONRET_0_0: cpu-nonretentive-0-0 { > > + compatible = "riscv,idle-state"; > > + riscv,sbi-suspend-param = <0x90000000>; > > + entry-latency-us = <250>; > > + exit-latency-us = <500>; > > + min-residency-us = <950>; > > + }; > > + > > + CLUSTER_RET_0: cluster-retentive-0 { > > + compatible = "riscv,idle-state"; > > + riscv,sbi-suspend-param = <0x11000000>; > > + local-timer-stop; > > + entry-latency-us = <50>; > > + exit-latency-us = <100>; > > + min-residency-us = <250>; > > + wakeup-latency-us = <130>; > > + }; > > + > > + CLUSTER_NONRET_0: cluster-nonretentive-0 { > > + compatible = "riscv,idle-state"; > > + riscv,sbi-suspend-param = <0x91000000>; > > + local-timer-stop; > > + entry-latency-us = <600>; > > + exit-latency-us = <1100>; > > + min-residency-us = <2700>; > > + wakeup-latency-us = <1500>; > > + }; > > + > > + CPU_RET_1_0: cpu-retentive-1-0 { > > + compatible = "riscv,idle-state"; > > + riscv,sbi-suspend-param = <0x10000010>; > > + entry-latency-us = <20>; > > + exit-latency-us = <40>; > > + min-residency-us = <80>; > > + }; > > + > > + CPU_NONRET_1_0: cpu-nonretentive-1-0 { > > + compatible = "riscv,idle-state"; > > + riscv,sbi-suspend-param = <0x90000010>; > > + entry-latency-us = <250>; > > + exit-latency-us = <500>; > > + min-residency-us = <950>; > > + }; > > + > > + CLUSTER_RET_1: cluster-retentive-1 { > > + compatible = "riscv,idle-state"; > > + riscv,sbi-suspend-param = <0x11000010>; > > + local-timer-stop; > > + entry-latency-us = <50>; > > + exit-latency-us = <100>; > > + min-residency-us = <250>; > > + wakeup-latency-us = <130>; > > + }; > > + > > + CLUSTER_NONRET_1: cluster-nonretentive-1 { > > + compatible = "riscv,idle-state"; > > + riscv,sbi-suspend-param = <0x91000010>; > > + local-timer-stop; > > + entry-latency-us = <600>; > > + exit-latency-us = <1100>; > > + min-residency-us = <2700>; > > + wakeup-latency-us = <1500>; > > + }; > > + }; > > + }; > > + > > +... > > -- > > 2.25.1 > > Regards, Anup
