[PATCH v10 7/8] dt-bindings: Add common bindings for ARM and RISC-V idle states
Guo Ren
guoren at kernel.org
Mon Feb 7 22:20:48 PST 2022
Acked-by: Guo Ren <guoren at kernel.org>
On Wed, Jan 26, 2022 at 7:50 PM Anup Patel <apatel at ventanamicro.com> wrote:
>
> From: Anup Patel <anup.patel at wdc.com>
>
> The RISC-V CPU idle states will be described in under the
> /cpus/idle-states DT node in the same way as ARM CPU idle
> states.
>
> This patch adds common bindings documentation for both ARM
> and RISC-V idle states.
>
> Signed-off-by: Anup Patel <anup.patel at wdc.com>
> Signed-off-by: Anup Patel <apatel at ventanamicro.com>
> Reviewed-by: Rob Herring <robh at kernel.org>
> ---
> .../bindings/arm/msm/qcom,idle-state.txt | 2 +-
> .../devicetree/bindings/arm/psci.yaml | 2 +-
> .../bindings/{arm => cpu}/idle-states.yaml | 228 ++++++++++++++++--
> .../devicetree/bindings/riscv/cpus.yaml | 6 +
> 4 files changed, 219 insertions(+), 19 deletions(-)
> rename Documentation/devicetree/bindings/{arm => cpu}/idle-states.yaml (74%)
>
> diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
> index 6ce0b212ec6d..606b4b1b709d 100644
> --- a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
> +++ b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
> @@ -81,4 +81,4 @@ Example:
> };
> };
>
> -[1]. Documentation/devicetree/bindings/arm/idle-states.yaml
> +[1]. Documentation/devicetree/bindings/cpu/idle-states.yaml
> diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml
> index 8b77cf83a095..dd83ef278af0 100644
> --- a/Documentation/devicetree/bindings/arm/psci.yaml
> +++ b/Documentation/devicetree/bindings/arm/psci.yaml
> @@ -101,7 +101,7 @@ properties:
> bindings in [1]) must specify this property.
>
> [1] Kernel documentation - ARM idle states bindings
> - Documentation/devicetree/bindings/arm/idle-states.yaml
> + Documentation/devicetree/bindings/cpu/idle-states.yaml
>
> patternProperties:
> "^power-domain-":
> diff --git a/Documentation/devicetree/bindings/arm/idle-states.yaml b/Documentation/devicetree/bindings/cpu/idle-states.yaml
> similarity index 74%
> rename from Documentation/devicetree/bindings/arm/idle-states.yaml
> rename to Documentation/devicetree/bindings/cpu/idle-states.yaml
> index 52bce5dbb11f..95506ffb816c 100644
> --- a/Documentation/devicetree/bindings/arm/idle-states.yaml
> +++ b/Documentation/devicetree/bindings/cpu/idle-states.yaml
> @@ -1,25 +1,30 @@
> # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> %YAML 1.2
> ---
> -$id: http://devicetree.org/schemas/arm/idle-states.yaml#
> +$id: http://devicetree.org/schemas/cpu/idle-states.yaml#
> $schema: http://devicetree.org/meta-schemas/core.yaml#
>
> -title: ARM idle states binding description
> +title: Idle states binding description
>
> maintainers:
> - Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> + - Anup Patel <anup at brainfault.org>
>
> description: |+
> ==========================================
> 1 - Introduction
> ==========================================
>
> - ARM systems contain HW capable of managing power consumption dynamically,
> - where cores can be put in different low-power states (ranging from simple wfi
> - to power gating) according to OS PM policies. The CPU states representing the
> - range of dynamic idle states that a processor can enter at run-time, can be
> - specified through device tree bindings representing the parameters required to
> - enter/exit specific idle states on a given processor.
> + ARM and RISC-V systems contain HW capable of managing power consumption
> + dynamically, where cores can be put in different low-power states (ranging
> + from simple wfi to power gating) according to OS PM policies. The CPU states
> + representing the range of dynamic idle states that a processor can enter at
> + run-time, can be specified through device tree bindings representing the
> + parameters required to enter/exit specific idle states on a given processor.
> +
> + ==========================================
> + 2 - ARM idle states
> + ==========================================
>
> According to the Server Base System Architecture document (SBSA, [3]), the
> power states an ARM CPU can be put into are identified by the following list:
> @@ -43,8 +48,23 @@ description: |+
> The device tree binding definition for ARM idle states is the subject of this
> document.
>
> + ==========================================
> + 3 - RISC-V idle states
> + ==========================================
> +
> + On RISC-V systems, the HARTs (or CPUs) [6] can be put in platform specific
> + suspend (or idle) states (ranging from simple WFI, power gating, etc). The
> + RISC-V SBI v0.3 (or higher) [7] hart state management extension provides a
> + standard mechanism for OS 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 registers and CSR values for all privilege modes whereas
> + a non-retentive suspend state will not preserve HART registers and CSR
> + values.
> +
> ===========================================
> - 2 - idle-states definitions
> + 4 - idle-states definitions
> ===========================================
>
> Idle states are characterized for a specific system through a set of
> @@ -211,10 +231,10 @@ description: |+
> properties specification that is the subject of the following sections.
>
> ===========================================
> - 3 - idle-states node
> + 5 - idle-states node
> ===========================================
>
> - ARM processor idle states are defined within the idle-states node, which is
> + The processor idle states are defined within the idle-states node, which is
> a direct child of the cpus node [1] and provides a container where the
> processor idle states, defined as device tree nodes, are listed.
>
> @@ -223,7 +243,7 @@ description: |+
> just supports idle_standby, an idle-states node is not required.
>
> ===========================================
> - 4 - References
> + 6 - References
> ===========================================
>
> [1] ARM Linux Kernel documentation - CPUs bindings
> @@ -238,9 +258,15 @@ description: |+
> [4] ARM Architecture Reference Manuals
> http://infocenter.arm.com/help/index.jsp
>
> - [6] ARM Linux Kernel documentation - Booting AArch64 Linux
> + [5] ARM Linux Kernel documentation - Booting AArch64 Linux
> Documentation/arm64/booting.rst
>
> + [6] RISC-V Linux Kernel documentation - CPUs bindings
> + Documentation/devicetree/bindings/riscv/cpus.yaml
> +
> + [7] RISC-V Supervisor Binary Interface (SBI)
> + http://github.com/riscv/riscv-sbi-doc/riscv-sbi.adoc
> +
> properties:
> $nodename:
> const: idle-states
> @@ -253,7 +279,7 @@ properties:
> On ARM 32-bit systems this property is optional
>
> This assumes that the "enable-method" property is set to "psci" in the cpu
> - node[6] that is responsible for setting up CPU idle management in the OS
> + node[5] that is responsible for setting up CPU idle management in the OS
> implementation.
> const: psci
>
> @@ -265,8 +291,8 @@ patternProperties:
> as follows.
>
> The idle state entered by executing the wfi instruction (idle_standby
> - SBSA,[3][4]) is considered standard on all ARM platforms and therefore
> - must not be listed.
> + SBSA,[3][4]) is considered standard on all ARM and RISC-V platforms and
> + therefore must not be listed.
>
> In addition to the properties listed above, a state node may require
> additional properties specific to the entry-method defined in the
> @@ -275,7 +301,27 @@ patternProperties:
>
> properties:
> compatible:
> - const: arm,idle-state
> + enum:
> + - arm,idle-state
> + - riscv,idle-state
> +
> + arm,psci-suspend-param:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description: |
> + power_state parameter to pass to the ARM PSCI suspend call.
> +
> + Device tree nodes that require usage of PSCI CPU_SUSPEND function
> + (i.e. idle states node with entry-method property is set to "psci")
> + must specify this property.
> +
> + riscv,sbi-suspend-param:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description: |
> + suspend_type parameter to pass to the RISC-V SBI HSM suspend call.
> +
> + This property is required in idle state nodes of device tree meant
> + for RISC-V systems. For more details on the suspend_type parameter
> + refer the SBI specifiation v0.3 (or higher) [7].
>
> local-timer-stop:
> description:
> @@ -317,6 +363,8 @@ patternProperties:
> description:
> A string used as a descriptive name for the idle state.
>
> + additionalProperties: false
> +
> required:
> - compatible
> - entry-latency-us
> @@ -658,4 +706,150 @@ examples:
> };
> };
>
> + - |
> + // Example 3 (RISC-V 64-bit, 4-cpu systems, two clusters):
> +
> + cpus {
> + #size-cells = <0>;
> + #address-cells = <1>;
> +
> + cpu at 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>;
> +
> + cpu_intc0: interrupt-controller {
> + #interrupt-cells = <1>;
> + compatible = "riscv,cpu-intc";
> + interrupt-controller;
> + };
> + };
> +
> + cpu at 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 at 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 at 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;
> + };
> + };
> +
> + idle-states {
> + CPU_RET_0_0: cpu-retentive-0-0 {
> + compatible = "riscv,idle-state";
> + riscv,sbi-suspend-param = <0x10000000>;
> + 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>;
> + };
> + };
> + };
> +
> ...
> diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
> index aa5fb64d57eb..f62f646bc695 100644
> --- a/Documentation/devicetree/bindings/riscv/cpus.yaml
> +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
> @@ -99,6 +99,12 @@ properties:
> - compatible
> - interrupt-controller
>
> + cpu-idle-states:
> + $ref: '/schemas/types.yaml#/definitions/phandle-array'
> + description: |
> + List of phandles to idle state nodes supported
> + by this hart (see ./idle-states.yaml).
> +
> required:
> - riscv,isa
> - interrupt-controller
> --
> 2.25.1
>
>
> --
> kvm-riscv mailing list
> kvm-riscv at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kvm-riscv
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
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