linux_dsm_epyc7002/Documentation/devicetree/bindings/opp/opp.txt

Generic OPP (Operating Performance Points) Bindings
----------------------------------------------------

Devices work at voltage-current-frequency combinations and some implementations
have the liberty of choosing these. These combinations are called Operating
Performance Points aka OPPs. This document defines bindings for these OPPs
applicable across wide range of devices. For illustration purpose, this document
uses CPU as a device.

This document contain multiple versions of OPP binding and only one of them
should be used per device.

Binding 1: operating-points
============================

This binding only supports voltage-frequency pairs.

Properties:
- operating-points: An array of 2-tuples items, and each item consists
  of frequency and voltage like <freq-kHz vol-uV>.
	freq: clock frequency in kHz
	vol: voltage in microvolt

Examples:

cpu@0 {
	compatible = "arm,cortex-a9";
	reg = <0>;
	next-level-cache = <&L2>;
	operating-points = <
		/* kHz    uV */
		792000  1100000
		396000  950000
		198000  850000
	>;
};


Binding 2: operating-points-v2
============================

* Property: operating-points-v2

Devices supporting OPPs must set their "operating-points-v2" property with
phandle to a OPP table in their DT node. The OPP core will use this phandle to
find the operating points for the device.

If required, this can be extended for SoC vendor specific bindings. Such bindings
should be documented as Documentation/devicetree/bindings/power/<vendor>-opp.txt
and should have a compatible description like: "operating-points-v2-<vendor>".

* OPP Table Node

This describes the OPPs belonging to a device. This node can have following
properties:

Required properties:
- compatible: Allow OPPs to express their compatibility. It should be:
  "operating-points-v2".

- OPP nodes: One or more OPP nodes describing voltage-current-frequency
  combinations. Their name isn't significant but their phandle can be used to
  reference an OPP.

Optional properties:
- opp-shared: Indicates that device nodes using this OPP Table Node's phandle
  switch their DVFS state together, i.e. they share clock/voltage/current lines.
  Missing property means devices have independent clock/voltage/current lines,
  but they share OPP tables.

- status: Marks the OPP table enabled/disabled.


* OPP Node

This defines voltage-current-frequency combinations along with other related
properties.

Required properties:
- opp-hz: Frequency in Hz, expressed as a 64-bit big-endian integer.

Optional properties:
- opp-microvolt: voltage in micro Volts.

  A single regulator's voltage is specified with an array of size one or three.
  Single entry is for target voltage and three entries are for <target min max>
  voltages.

  Entries for multiple regulators shall be provided in the same field separated
  by angular brackets <>. The OPP binding doesn't provide any provisions to
  relate the values to their power supplies or the order in which the supplies
  need to be configured and that is left for the implementation specific
  binding.

  Entries for all regulators shall be of the same size, i.e. either all use a
  single value or triplets.

- opp-microvolt-<name>: Named opp-microvolt property. This is exactly similar to
  the above opp-microvolt property, but allows multiple voltage ranges to be
  provided for the same OPP. At runtime, the platform can pick a <name> and
  matching opp-microvolt-<name> property will be enabled for all OPPs. If the
  platform doesn't pick a specific <name> or the <name> doesn't match with any
  opp-microvolt-<name> properties, then opp-microvolt property shall be used, if
  present.

- opp-microamp: The maximum current drawn by the device in microamperes
  considering system specific parameters (such as transients, process, aging,
  maximum operating temperature range etc.) as necessary. This may be used to
  set the most efficient regulator operating mode.

  Should only be set if opp-microvolt is set for the OPP.

  Entries for multiple regulators shall be provided in the same field separated
  by angular brackets <>. If current values aren't required for a regulator,
  then it shall be filled with 0. If current values aren't required for any of
  the regulators, then this field is not required. The OPP binding doesn't
  provide any provisions to relate the values to their power supplies or the
  order in which the supplies need to be configured and that is left for the
  implementation specific binding.

- opp-microamp-<name>: Named opp-microamp property. Similar to
  opp-microvolt-<name> property, but for microamp instead.

- clock-latency-ns: Specifies the maximum possible transition latency (in
  nanoseconds) for switching to this OPP from any other OPP.

- turbo-mode: Marks the OPP to be used only for turbo modes. Turbo mode is
  available on some platforms, where the device can run over its operating
  frequency for a short duration of time limited by the device's power, current
  and thermal limits.

- opp-suspend: Marks the OPP to be used during device suspend. Only one OPP in
  the table should have this.

- opp-supported-hw: This enables us to select only a subset of OPPs from the
  larger OPP table, based on what version of the hardware we are running on. We
  still can't have multiple nodes with the same opp-hz value in OPP table.

  It's a user defined array containing a hierarchy of hardware version numbers,
  supported by the OPP. For example: a platform with hierarchy of three levels
  of versions (A, B and C), this field should be like <X Y Z>, where X
  corresponds to Version hierarchy A, Y corresponds to version hierarchy B and Z
  corresponds to version hierarchy C.

  Each level of hierarchy is represented by a 32 bit value, and so there can be
  only 32 different supported version per hierarchy. i.e. 1 bit per version. A
  value of 0xFFFFFFFF will enable the OPP for all versions for that hierarchy
  level. And a value of 0x00000000 will disable the OPP completely, and so we
  never want that to happen.

  If 32 values aren't sufficient for a version hierarchy, than that version
  hierarchy can be contained in multiple 32 bit values. i.e. <X Y Z1 Z2> in the
  above example, Z1 & Z2 refer to the version hierarchy Z.

- status: Marks the node enabled/disabled.

Example 1: Single cluster Dual-core ARM cortex A9, switch DVFS states together.

/ {
	cpus {
		#address-cells = <1>;
		#size-cells = <0>;

		cpu@0 {
			compatible = "arm,cortex-a9";
			reg = <0>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 0>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply0>;
			operating-points-v2 = <&cpu0_opp_table>;
		};

		cpu@1 {
			compatible = "arm,cortex-a9";
			reg = <1>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 0>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply0>;
			operating-points-v2 = <&cpu0_opp_table>;
		};
	};

	cpu0_opp_table: opp_table0 {
		compatible = "operating-points-v2";
		opp-shared;

		opp@1000000000 {
			opp-hz = /bits/ 64 <1000000000>;
			opp-microvolt = <975000 970000 985000>;
			opp-microamp = <70000>;
			clock-latency-ns = <300000>;
			opp-suspend;
		};
		opp@1100000000 {
			opp-hz = /bits/ 64 <1100000000>;
			opp-microvolt = <1000000 980000 1010000>;
			opp-microamp = <80000>;
			clock-latency-ns = <310000>;
		};
		opp@1200000000 {
			opp-hz = /bits/ 64 <1200000000>;
			opp-microvolt = <1025000>;
			clock-latency-ns = <290000>;
			turbo-mode;
		};
	};
};

Example 2: Single cluster, Quad-core Qualcom-krait, switches DVFS states
independently.

/ {
	cpus {
		#address-cells = <1>;
		#size-cells = <0>;

		cpu@0 {
			compatible = "qcom,krait";
			reg = <0>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 0>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply0>;
			operating-points-v2 = <&cpu_opp_table>;
		};

		cpu@1 {
			compatible = "qcom,krait";
			reg = <1>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 1>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply1>;
			operating-points-v2 = <&cpu_opp_table>;
		};

		cpu@2 {
			compatible = "qcom,krait";
			reg = <2>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 2>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply2>;
			operating-points-v2 = <&cpu_opp_table>;
		};

		cpu@3 {
			compatible = "qcom,krait";
			reg = <3>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 3>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply3>;
			operating-points-v2 = <&cpu_opp_table>;
		};
	};

	cpu_opp_table: opp_table {
		compatible = "operating-points-v2";

		/*
		 * Missing opp-shared property means CPUs switch DVFS states
		 * independently.
		 */

		opp@1000000000 {
			opp-hz = /bits/ 64 <1000000000>;
			opp-microvolt = <975000 970000 985000>;
			opp-microamp = <70000>;
			clock-latency-ns = <300000>;
			opp-suspend;
		};
		opp@1100000000 {
			opp-hz = /bits/ 64 <1100000000>;
			opp-microvolt = <1000000 980000 1010000>;
			opp-microamp = <80000>;
			clock-latency-ns = <310000>;
		};
		opp@1200000000 {
			opp-hz = /bits/ 64 <1200000000>;
			opp-microvolt = <1025000>;
			opp-microamp = <90000;
			lock-latency-ns = <290000>;
			turbo-mode;
		};
	};
};

Example 3: Dual-cluster, Dual-core per cluster. CPUs within a cluster switch
DVFS state together.

/ {
	cpus {
		#address-cells = <1>;
		#size-cells = <0>;

		cpu@0 {
			compatible = "arm,cortex-a7";
			reg = <0>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 0>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply0>;
			operating-points-v2 = <&cluster0_opp>;
		};

		cpu@1 {
			compatible = "arm,cortex-a7";
			reg = <1>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 0>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply0>;
			operating-points-v2 = <&cluster0_opp>;
		};

		cpu@100 {
			compatible = "arm,cortex-a15";
			reg = <100>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 1>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply1>;
			operating-points-v2 = <&cluster1_opp>;
		};

		cpu@101 {
			compatible = "arm,cortex-a15";
			reg = <101>;
			next-level-cache = <&L2>;
			clocks = <&clk_controller 1>;
			clock-names = "cpu";
			cpu-supply = <&cpu_supply1>;
			operating-points-v2 = <&cluster1_opp>;
		};
	};

	cluster0_opp: opp_table0 {
		compatible = "operating-points-v2";
		opp-shared;

		opp@1000000000 {
			opp-hz = /bits/ 64 <1000000000>;
			opp-microvolt = <975000 970000 985000>;
			opp-microamp = <70000>;
			clock-latency-ns = <300000>;
			opp-suspend;
		};
		opp@1100000000 {
			opp-hz = /bits/ 64 <1100000000>;
			opp-microvolt = <1000000 980000 1010000>;
			opp-microamp = <80000>;
			clock-latency-ns = <310000>;
		};
		opp@1200000000 {
			opp-hz = /bits/ 64 <1200000000>;
			opp-microvolt = <1025000>;
			opp-microamp = <90000>;
			clock-latency-ns = <290000>;
			turbo-mode;
		};
	};

	cluster1_opp: opp_table1 {
		compatible = "operating-points-v2";
		opp-shared;

		opp@1300000000 {
			opp-hz = /bits/ 64 <1300000000>;
			opp-microvolt = <1050000 1045000 1055000>;
			opp-microamp = <95000>;
			clock-latency-ns = <400000>;
			opp-suspend;
		};
		opp@1400000000 {
			opp-hz = /bits/ 64 <1400000000>;
			opp-microvolt = <1075000>;
			opp-microamp = <100000>;
			clock-latency-ns = <400000>;
		};
		opp@1500000000 {
			opp-hz = /bits/ 64 <1500000000>;
			opp-microvolt = <1100000 1010000 1110000>;
			opp-microamp = <95000>;
			clock-latency-ns = <400000>;
			turbo-mode;
		};
	};
};

Example 4: Handling multiple regulators

/ {
	cpus {
		cpu@0 {
			compatible = "vendor,cpu-type";
			...

			vcc0-supply = <&cpu_supply0>;
			vcc1-supply = <&cpu_supply1>;
			vcc2-supply = <&cpu_supply2>;
			operating-points-v2 = <&cpu0_opp_table>;
		};
	};

	cpu0_opp_table: opp_table0 {
		compatible = "operating-points-v2";
		opp-shared;

		opp@1000000000 {
			opp-hz = /bits/ 64 <1000000000>;
			opp-microvolt = <970000>, /* Supply 0 */
					<960000>, /* Supply 1 */
					<960000>; /* Supply 2 */
			opp-microamp =  <70000>,  /* Supply 0 */
					<70000>,  /* Supply 1 */
					<70000>;  /* Supply 2 */
			clock-latency-ns = <300000>;
		};

		/* OR */

		opp@1000000000 {
			opp-hz = /bits/ 64 <1000000000>;
			opp-microvolt = <975000 970000 985000>, /* Supply 0 */
					<965000 960000 975000>, /* Supply 1 */
					<965000 960000 975000>; /* Supply 2 */
			opp-microamp =  <70000>,		/* Supply 0 */
					<70000>,		/* Supply 1 */
					<70000>;		/* Supply 2 */
			clock-latency-ns = <300000>;
		};

		/* OR */

		opp@1000000000 {
			opp-hz = /bits/ 64 <1000000000>;
			opp-microvolt = <975000 970000 985000>, /* Supply 0 */
					<965000 960000 975000>, /* Supply 1 */
					<965000 960000 975000>; /* Supply 2 */
			opp-microamp =  <70000>,		/* Supply 0 */
					<0>,			/* Supply 1 doesn't need this */
					<70000>;		/* Supply 2 */
			clock-latency-ns = <300000>;
		};
	};
};

Example 5: opp-supported-hw
(example: three level hierarchy of versions: cuts, substrate and process)

/ {
	cpus {
		cpu@0 {
			compatible = "arm,cortex-a7";
			...

			cpu-supply = <&cpu_supply>
			operating-points-v2 = <&cpu0_opp_table_slow>;
		};
	};

	opp_table {
		compatible = "operating-points-v2";
		status = "okay";
		opp-shared;

		opp@600000000 {
			/*
			 * Supports all substrate and process versions for 0xF
			 * cuts, i.e. only first four cuts.
			 */
			opp-supported-hw = <0xF 0xFFFFFFFF 0xFFFFFFFF>
			opp-hz = /bits/ 64 <600000000>;
			opp-microvolt = <915000 900000 925000>;
			...
		};

		opp@800000000 {
			/*
			 * Supports:
			 * - cuts: only one, 6th cut (represented by 6th bit).
			 * - substrate: supports 16 different substrate versions
			 * - process: supports 9 different process versions
			 */
			opp-supported-hw = <0x20 0xff0000ff 0x0000f4f0>
			opp-hz = /bits/ 64 <800000000>;
			opp-microvolt = <915000 900000 925000>;
			...
		};
	};
};

Example 6: opp-microvolt-<name>, opp-microamp-<name>:
(example: device with two possible microvolt ranges: slow and fast)

/ {
	cpus {
		cpu@0 {
			compatible = "arm,cortex-a7";
			...

			operating-points-v2 = <&cpu0_opp_table>;
		};
	};

	cpu0_opp_table: opp_table0 {
		compatible = "operating-points-v2";
		opp-shared;

		opp@1000000000 {
			opp-hz = /bits/ 64 <1000000000>;
			opp-microvolt-slow = <915000 900000 925000>;
			opp-microvolt-fast = <975000 970000 985000>;
			opp-microamp-slow =  <70000>;
			opp-microamp-fast =  <71000>;
		};

		opp@1200000000 {
			opp-hz = /bits/ 64 <1200000000>;
			opp-microvolt-slow = <915000 900000 925000>, /* Supply vcc0 */
					      <925000 910000 935000>; /* Supply vcc1 */
			opp-microvolt-fast = <975000 970000 985000>, /* Supply vcc0 */
					     <965000 960000 975000>; /* Supply vcc1 */
			opp-microamp =  <70000>; /* Will be used for both slow/fast */
		};
	};
};