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dt-bindings: Add common bindings for ARM and RISC-V idle states 

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@wdc.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Anup Patel 2022-02-10 11:19:46 +05:30 committed by Palmer Dabbelt
parent 6abf32f1d9
commit 1bd524f7e8
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4 changed files with 219 additions and 19 deletions
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2
Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
View File

@ -81,4 +81,4 @@ Example:
};
};
[1]. Documentation/devicetree/bindings/arm/idle-states.yaml
[1]. Documentation/devicetree/bindings/cpu/idle-states.yaml

2
Documentation/devicetree/bindings/arm/psci.yaml
View File

@ -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-":

228
Documentation/devicetree/bindings/arm/idle-states.yaml → Documentation/devicetree/bindings/cpu/idle-states.yaml
View File

@ -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@arm.com>
- Anup Patel <anup@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@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@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;
};
};
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>;
};
};
};
...

6
Documentation/devicetree/bindings/riscv/cpus.yaml
View File

@ -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