Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 855 insertions, 0 deletions

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+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/cpu/idle-states.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Idle states binding description
+
+maintainers:
+  - Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+  - Anup Patel <anup@brainfault.org>
+
+description: |+
+  ==========================================
+  1 - Introduction
+  ==========================================
+
+  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:
+
+  - Running
+  - Idle_standby
+  - Idle_retention
+  - Sleep
+  - Off
+
+  The power states described in the SBSA document define the basic CPU states on
+  top of which ARM platforms implement power management schemes that allow an OS
+  PM implementation to put the processor in different idle states (which include
+  states listed above; "off" state is not an idle state since it does not have
+  wake-up capabilities, hence it is not considered in this document).
+
+  Idle state parameters (e.g. entry latency) are platform specific and need to
+  be characterized with bindings that provide the required information to OS PM
+  code so that it can build the required tables and use them at runtime.
+
+  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.
+
+  ===========================================
+  4 - idle-states definitions
+  ===========================================
+
+  Idle states are characterized for a specific system through a set of
+  timing and energy related properties, that underline the HW behaviour
+  triggered upon idle states entry and exit.
+
+  The following diagram depicts the CPU execution phases and related timing
+  properties required to enter and exit an idle state:
+
+  ..__[EXEC]__|__[PREP]__|__[ENTRY]__|__[IDLE]__|__[EXIT]__|__[EXEC]__..
+              |          |           |          |          |
+
+              |<------ entry ------->|
+              |       latency        |
+                                                |<- exit ->|
+                                                |  latency |
+              |<-------- min-residency -------->|
+                         |<-------  wakeup-latency ------->|
+
+      Diagram 1: CPU idle state execution phases
+
+  EXEC:  Normal CPU execution.
+
+  PREP:  Preparation phase before committing the hardware to idle mode
+    like cache flushing. This is abortable on pending wake-up
+    event conditions. The abort latency is assumed to be negligible
+    (i.e. less than the ENTRY + EXIT duration). If aborted, CPU
+    goes back to EXEC. This phase is optional. If not abortable,
+    this should be included in the ENTRY phase instead.
+
+  ENTRY:  The hardware is committed to idle mode. This period must run
+    to completion up to IDLE before anything else can happen.
+
+  IDLE:  This is the actual energy-saving idle period. This may last
+    between 0 and infinite time, until a wake-up event occurs.
+
+  EXIT:  Period during which the CPU is brought back to operational
+    mode (EXEC).
+
+  entry-latency: Worst case latency required to enter the idle state. The
+  exit-latency may be guaranteed only after entry-latency has passed.
+
+  min-residency: Minimum period, including preparation and entry, for a given
+  idle state to be worthwhile energywise.
+
+  wakeup-latency: Maximum delay between the signaling of a wake-up event and the
+  CPU being able to execute normal code again. If not specified, this is assumed
+  to be entry-latency + exit-latency.
+
+  These timing parameters can be used by an OS in different circumstances.
+
+  An idle CPU requires the expected min-residency time to select the most
+  appropriate idle state based on the expected expiry time of the next IRQ
+  (i.e. wake-up) that causes the CPU to return to the EXEC phase.
+
+  An operating system scheduler may need to compute the shortest wake-up delay
+  for CPUs in the system by detecting how long will it take to get a CPU out
+  of an idle state, e.g.:
+
+  wakeup-delay = exit-latency + max(entry-latency - (now - entry-timestamp), 0)
+
+  In other words, the scheduler can make its scheduling decision by selecting
+  (e.g. waking-up) the CPU with the shortest wake-up delay.
+  The wake-up delay must take into account the entry latency if that period
+  has not expired. The abortable nature of the PREP period can be ignored
+  if it cannot be relied upon (e.g. the PREP deadline may occur much sooner than
+  the worst case since it depends on the CPU operating conditions, i.e. caches
+  state).
+
+  An OS has to reliably probe the wakeup-latency since some devices can enforce
+  latency constraint guarantees to work properly, so the OS has to detect the
+  worst case wake-up latency it can incur if a CPU is allowed to enter an
+  idle state, and possibly to prevent that to guarantee reliable device
+  functioning.
+
+  The min-residency time parameter deserves further explanation since it is
+  expressed in time units but must factor in energy consumption coefficients.
+
+  The energy consumption of a cpu when it enters a power state can be roughly
+  characterised by the following graph:
+
+                 |
+                 |
+                 |
+             e   |
+             n   |                                      /---
+             e   |                               /------
+             r   |                        /------
+             g   |                  /-----
+             y   |           /------
+                 |       ----
+                 |      /|
+                 |     / |
+                 |    /  |
+                 |   /   |
+                 |  /    |
+                 | /     |
+                 |/      |
+            -----|-------+----------------------------------
+                0|       1                              time(ms)
+
+      Graph 1: Energy vs time example
+
+  The graph is split in two parts delimited by time 1ms on the X-axis.
+  The graph curve with X-axis values = { x | 0 < x < 1ms } has a steep slope
+  and denotes the energy costs incurred while entering and leaving the idle
+  state.
+  The graph curve in the area delimited by X-axis values = {x | x > 1ms } has
+  shallower slope and essentially represents the energy consumption of the idle
+  state.
+
+  min-residency is defined for a given idle state as the minimum expected
+  residency time for a state (inclusive of preparation and entry) after
+  which choosing that state become the most energy efficient option. A good
+  way to visualise this, is by taking the same graph above and comparing some
+  states energy consumptions plots.
+
+  For sake of simplicity, let's consider a system with two idle states IDLE1,
+  and IDLE2:
+
+            |
+            |
+            |
+            |                                                  /-- IDLE1
+         e  |                                              /---
+         n  |                                         /----
+         e  |                                     /---
+         r  |                                /-----/--------- IDLE2
+         g  |                    /-------/---------
+         y  |        ------------    /---|
+            |       /           /----    |
+            |      /        /---         |
+            |     /    /----             |
+            |    / /---                  |
+            |   ---                      |
+            |  /                         |
+            | /                          |
+            |/                           |                  time
+         ---/----------------------------+------------------------
+            |IDLE1-energy < IDLE2-energy | IDLE2-energy < IDLE1-energy
+                                         |
+                                  IDLE2-min-residency
+
+      Graph 2: idle states min-residency example
+
+  In graph 2 above, that takes into account idle states entry/exit energy
+  costs, it is clear that if the idle state residency time (i.e. time till next
+  wake-up IRQ) is less than IDLE2-min-residency, IDLE1 is the better idle state
+  choice energywise.
+
+  This is mainly down to the fact that IDLE1 entry/exit energy costs are lower
+  than IDLE2.
+
+  However, the lower power consumption (i.e. shallower energy curve slope) of
+  idle state IDLE2 implies that after a suitable time, IDLE2 becomes more energy
+  efficient.
+
+  The time at which IDLE2 becomes more energy efficient than IDLE1 (and other
+  shallower states in a system with multiple idle states) is defined
+  IDLE2-min-residency and corresponds to the time when energy consumption of
+  IDLE1 and IDLE2 states breaks even.
+
+  The definitions provided in this section underpin the idle states
+  properties specification that is the subject of the following sections.
+
+  ===========================================
+  5 - idle-states node
+  ===========================================
+
+  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.
+
+  On ARM systems, it is a container of processor idle states nodes. If the
+  system does not provide CPU power management capabilities, or the processor
+  just supports idle_standby, an idle-states node is not required.
+
+  ===========================================
+  6 - References
+  ===========================================
+
+  [1] ARM Linux Kernel documentation - CPUs bindings
+      Documentation/devicetree/bindings/arm/cpus.yaml
+
+  [2] ARM Linux Kernel documentation - PSCI bindings
+      Documentation/devicetree/bindings/arm/psci.yaml
+
+  [3] ARM Server Base System Architecture (SBSA)
+      http://infocenter.arm.com/help/index.jsp
+
+  [4] ARM Architecture Reference Manuals
+      http://infocenter.arm.com/help/index.jsp
+
+  [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
+
+  entry-method:
+    description: |
+      Usage and definition depend on ARM architecture version.
+
+      On ARM v8 64-bit this property is required.
+      On ARM 32-bit systems this property is optional
+
+      This assumes that the "enable-method" property is set to "psci" in the cpu
+      node[5] that is responsible for setting up CPU idle management in the OS
+      implementation.
+    const: psci
+
+patternProperties:
+  "^(cpu|cluster)-":
+    type: object
+    description: |
+      Each state node represents an idle state description and must be defined
+      as follows.
+
+      The idle state entered by executing the wfi instruction (idle_standby
+      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
+      idle-states node. Please refer to the entry-method bindings
+      documentation for properties definitions.
+
+    properties:
+      compatible:
+        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:
+          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.
+
+    additionalProperties: false
+
+    required:
+      - compatible
+      - entry-latency-us
+      - exit-latency-us
+      - min-residency-us
+
+additionalProperties: false
+
+examples:
+  - |
+
+    cpus {
+        #size-cells = <0>;
+        #address-cells = <2>;
+
+        cpu@0 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a57";
+            reg = <0x0 0x0>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_0_0>, <&CPU_SLEEP_0_0>,
+                    <&CLUSTER_RETENTION_0>, <&CLUSTER_SLEEP_0>;
+        };
+
+        cpu@1 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a57";
+            reg = <0x0 0x1>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_0_0>, <&CPU_SLEEP_0_0>,
+                    <&CLUSTER_RETENTION_0>, <&CLUSTER_SLEEP_0>;
+        };
+
+        cpu@100 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a57";
+            reg = <0x0 0x100>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_0_0>, <&CPU_SLEEP_0_0>,
+                    <&CLUSTER_RETENTION_0>, <&CLUSTER_SLEEP_0>;
+        };
+
+        cpu@101 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a57";
+            reg = <0x0 0x101>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_0_0>, <&CPU_SLEEP_0_0>,
+                    <&CLUSTER_RETENTION_0>, <&CLUSTER_SLEEP_0>;
+        };
+
+        cpu@10000 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a57";
+            reg = <0x0 0x10000>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_0_0>, <&CPU_SLEEP_0_0>,
+                    <&CLUSTER_RETENTION_0>, <&CLUSTER_SLEEP_0>;
+        };
+
+        cpu@10001 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a57";
+            reg = <0x0 0x10001>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_0_0>, <&CPU_SLEEP_0_0>,
+                    <&CLUSTER_RETENTION_0>, <&CLUSTER_SLEEP_0>;
+        };
+
+        cpu@10100 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a57";
+            reg = <0x0 0x10100>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_0_0>, <&CPU_SLEEP_0_0>,
+                    <&CLUSTER_RETENTION_0>, <&CLUSTER_SLEEP_0>;
+        };
+
+        cpu@10101 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a57";
+            reg = <0x0 0x10101>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_0_0>, <&CPU_SLEEP_0_0>,
+                    <&CLUSTER_RETENTION_0>, <&CLUSTER_SLEEP_0>;
+        };
+
+        cpu@100000000 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a53";
+            reg = <0x1 0x0>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_1_0>, <&CPU_SLEEP_1_0>,
+                    <&CLUSTER_RETENTION_1>, <&CLUSTER_SLEEP_1>;
+        };
+
+        cpu@100000001 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a53";
+            reg = <0x1 0x1>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_1_0>, <&CPU_SLEEP_1_0>,
+                    <&CLUSTER_RETENTION_1>, <&CLUSTER_SLEEP_1>;
+        };
+
+        cpu@100000100 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a53";
+            reg = <0x1 0x100>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_1_0>, <&CPU_SLEEP_1_0>,
+                    <&CLUSTER_RETENTION_1>, <&CLUSTER_SLEEP_1>;
+        };
+
+        cpu@100000101 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a53";
+            reg = <0x1 0x101>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_1_0>, <&CPU_SLEEP_1_0>,
+                    <&CLUSTER_RETENTION_1>, <&CLUSTER_SLEEP_1>;
+        };
+
+        cpu@100010000 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a53";
+            reg = <0x1 0x10000>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_1_0>, <&CPU_SLEEP_1_0>,
+                    <&CLUSTER_RETENTION_1>, <&CLUSTER_SLEEP_1>;
+        };
+
+        cpu@100010001 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a53";
+            reg = <0x1 0x10001>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_1_0>, <&CPU_SLEEP_1_0>,
+                    <&CLUSTER_RETENTION_1>, <&CLUSTER_SLEEP_1>;
+        };
+
+        cpu@100010100 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a53";
+            reg = <0x1 0x10100>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_1_0>, <&CPU_SLEEP_1_0>,
+                    <&CLUSTER_RETENTION_1>, <&CLUSTER_SLEEP_1>;
+        };
+
+        cpu@100010101 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a53";
+            reg = <0x1 0x10101>;
+            enable-method = "psci";
+            cpu-idle-states = <&CPU_RETENTION_1_0>, <&CPU_SLEEP_1_0>,
+                    <&CLUSTER_RETENTION_1>, <&CLUSTER_SLEEP_1>;
+        };
+
+        idle-states {
+            entry-method = "psci";
+
+            CPU_RETENTION_0_0: cpu-retention-0-0 {
+                compatible = "arm,idle-state";
+                arm,psci-suspend-param = <0x0010000>;
+                entry-latency-us = <20>;
+                exit-latency-us = <40>;
+                min-residency-us = <80>;
+            };
+
+            CLUSTER_RETENTION_0: cluster-retention-0 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                arm,psci-suspend-param = <0x1010000>;
+                entry-latency-us = <50>;
+                exit-latency-us = <100>;
+                min-residency-us = <250>;
+                wakeup-latency-us = <130>;
+            };
+
+            CPU_SLEEP_0_0: cpu-sleep-0-0 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                arm,psci-suspend-param = <0x0010000>;
+                entry-latency-us = <250>;
+                exit-latency-us = <500>;
+                min-residency-us = <950>;
+            };
+
+            CLUSTER_SLEEP_0: cluster-sleep-0 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                arm,psci-suspend-param = <0x1010000>;
+                entry-latency-us = <600>;
+                exit-latency-us = <1100>;
+                min-residency-us = <2700>;
+                wakeup-latency-us = <1500>;
+            };
+
+            CPU_RETENTION_1_0: cpu-retention-1-0 {
+                compatible = "arm,idle-state";
+                arm,psci-suspend-param = <0x0010000>;
+                entry-latency-us = <20>;
+                exit-latency-us = <40>;
+                min-residency-us = <90>;
+            };
+
+            CLUSTER_RETENTION_1: cluster-retention-1 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                arm,psci-suspend-param = <0x1010000>;
+                entry-latency-us = <50>;
+                exit-latency-us = <100>;
+                min-residency-us = <270>;
+                wakeup-latency-us = <100>;
+            };
+
+            CPU_SLEEP_1_0: cpu-sleep-1-0 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                arm,psci-suspend-param = <0x0010000>;
+                entry-latency-us = <70>;
+                exit-latency-us = <100>;
+                min-residency-us = <300>;
+                wakeup-latency-us = <150>;
+            };
+
+            CLUSTER_SLEEP_1: cluster-sleep-1 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                arm,psci-suspend-param = <0x1010000>;
+                entry-latency-us = <500>;
+                exit-latency-us = <1200>;
+                min-residency-us = <3500>;
+                wakeup-latency-us = <1300>;
+            };
+        };
+    };
+
+  - |
+    // Example 2 (ARM 32-bit, 8-cpu system, two clusters):
+
+    cpus {
+        #size-cells = <0>;
+        #address-cells = <1>;
+
+        cpu@0 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a15";
+            reg = <0x0>;
+            cpu-idle-states = <&cpu_sleep_0_0>, <&cluster_sleep_0>;
+        };
+
+        cpu@1 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a15";
+            reg = <0x1>;
+            cpu-idle-states = <&cpu_sleep_0_0>, <&cluster_sleep_0>;
+        };
+
+        cpu@2 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a15";
+            reg = <0x2>;
+            cpu-idle-states = <&cpu_sleep_0_0>, <&cluster_sleep_0>;
+        };
+
+        cpu@3 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a15";
+            reg = <0x3>;
+            cpu-idle-states = <&cpu_sleep_0_0>, <&cluster_sleep_0>;
+        };
+
+        cpu@100 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a7";
+            reg = <0x100>;
+            cpu-idle-states = <&cpu_sleep_1_0>, <&cluster_sleep_1>;
+        };
+
+        cpu@101 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a7";
+            reg = <0x101>;
+            cpu-idle-states = <&cpu_sleep_1_0>, <&cluster_sleep_1>;
+        };
+
+        cpu@102 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a7";
+            reg = <0x102>;
+            cpu-idle-states = <&cpu_sleep_1_0>, <&cluster_sleep_1>;
+        };
+
+        cpu@103 {
+            device_type = "cpu";
+            compatible = "arm,cortex-a7";
+            reg = <0x103>;
+            cpu-idle-states = <&cpu_sleep_1_0>, <&cluster_sleep_1>;
+        };
+
+        idle-states {
+            cpu_sleep_0_0: cpu-sleep-0-0 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                entry-latency-us = <200>;
+                exit-latency-us = <100>;
+                min-residency-us = <400>;
+                wakeup-latency-us = <250>;
+            };
+
+            cluster_sleep_0: cluster-sleep-0 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                entry-latency-us = <500>;
+                exit-latency-us = <1500>;
+                min-residency-us = <2500>;
+                wakeup-latency-us = <1700>;
+            };
+
+            cpu_sleep_1_0: cpu-sleep-1-0 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                entry-latency-us = <300>;
+                exit-latency-us = <500>;
+                min-residency-us = <900>;
+                wakeup-latency-us = <600>;
+            };
+
+            cluster_sleep_1: cluster-sleep-1 {
+                compatible = "arm,idle-state";
+                local-timer-stop;
+                entry-latency-us = <800>;
+                exit-latency-us = <2000>;
+                min-residency-us = <6500>;
+                wakeup-latency-us = <2300>;
+            };
+        };
+    };
+
+  - |
+    // 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>;
+            };
+        };
+    };
+
+...