FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/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.
    
    This can contain more than one phandle for power domain providers that provide
    multiple power domains. That is, one phandle for each power domain. If only one
    phandle is available, then the same OPP table will be used for all power domains
    provided by the power domain provider.
    
    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. These are mandatory except for the case where the OPP table
      is present only to indicate dependency between devices using the opp-shared
      property.
    
    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. This is a
      required property for all device nodes, unless another "required" property to
      uniquely identify the OPP nodes exists. Devices like power domains must have
      another (implementation dependent) property.
    
    - opp-peak-kBps: Peak bandwidth in kilobytes per second, expressed as an array
      of 32-bit big-endian integers. Each element of the array represents the
      peak bandwidth value of each interconnect path. The number of elements should
      match the number of interconnect paths.
    
    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.
   
   - opp-level: A value representing the performance level of the device,
     expressed as a 32-bit integer.
   
   - opp-avg-kBps: Average bandwidth in kilobytes per second, expressed as an array
     of 32-bit big-endian integers. Each element of the array represents the
     average bandwidth value of each interconnect path. The number of elements
     should match the number of interconnect paths. This property is only
     meaningful in OPP tables where opp-peak-kBps is present.
   
   - 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. If multiple OPPs
     in the table have this, the OPP with highest opp-hz will be used.
   
   - opp-supported-hw: This property allows a platform to enable only a subset of
     the OPPs from the larger set present in the OPP table, based on the current
     version of the hardware (already known to the operating system).
   
     Each block present in the array of blocks in this property, represents a
     sub-group of hardware versions supported by the OPP. i.e. <sub-group A>,
     <sub-group B>, etc. The OPP will be enabled if _any_ of these sub-groups match
     the hardware's version.
   
     Each sub-group is a platform defined array representing the hierarchy of
     hardware versions supported by the platform. For a platform with three
     hierarchical levels of version (X.Y.Z), this field shall look like
   
     opp-supported-hw = <X1 Y1 Z1>, <X2 Y2 Z2>, <X3 Y3 Z3>.
   
     Each level (eg. X1) in version hierarchy is represented by a 32 bit value, one
     bit per version and so there can be maximum 32 versions per level. Logical AND
     (&) operation is performed for each level with the hardware's level version
     and a non-zero output for _all_ the levels in a sub-group means the OPP is
     supported by hardware. A value of 0xFFFFFFFF for each level in the sub-group
     will enable the OPP for all versions for the hardware.
   
   - status: Marks the node enabled/disabled.
   
   - required-opps: This contains phandle to an OPP node in another device's OPP
     table. It may contain an array of phandles, where each phandle points to an
     OPP of a different device. It should not contain multiple phandles to the OPP
     nodes in the same OPP table. This specifies the minimum required OPP of the
     device(s), whose OPP's phandle is present in this property, for the
     functioning of the current device at the current OPP (where this property is
     present).
   
   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";
                   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-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-900000000 {
                           /*
                            * Supports:
                            * - All cuts and substrate where process version is 0x2.
                            * - All cuts and process where substrate version is 0x2.
                            */
                           opp-supported-hw = <0xFFFFFFFF 0xFFFFFFFF 0x02>, <0xFFFFFFFF 0x01 0xFFFFFFFF>
                           opp-hz = /bits/ 64 <900000000>;
                           ...
                   };
           };
   };
   
   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 */
                   };
           };
   };
   
   Example 7: Single cluster Quad-core ARM cortex A53, OPP points from firmware,
   distinct clock controls but two sets of clock/voltage/current lines.
   
   / {
           cpus {
                   #address-cells = <2>;
                   #size-cells = <0>;
   
                   cpu@0 {
                           compatible = "arm,cortex-a53";
                           reg = <0x0 0x100>;
                           next-level-cache = <&A53_L2>;
                           clocks = <&dvfs_controller 0>;
                           operating-points-v2 = <&cpu_opp0_table>;
                   };
                   cpu@1 {
                           compatible = "arm,cortex-a53";
                           reg = <0x0 0x101>;
                           next-level-cache = <&A53_L2>;
                           clocks = <&dvfs_controller 1>;
                           operating-points-v2 = <&cpu_opp0_table>;
                   };
                   cpu@2 {
                           compatible = "arm,cortex-a53";
                           reg = <0x0 0x102>;
                           next-level-cache = <&A53_L2>;
                           clocks = <&dvfs_controller 2>;
                           operating-points-v2 = <&cpu_opp1_table>;
                   };
                   cpu@3 {
                           compatible = "arm,cortex-a53";
                           reg = <0x0 0x103>;
                           next-level-cache = <&A53_L2>;
                           clocks = <&dvfs_controller 3>;
                           operating-points-v2 = <&cpu_opp1_table>;
                   };
   
           };
   
           cpu_opp0_table: opp0_table {
                   compatible = "operating-points-v2";
                   opp-shared;
           };
   
           cpu_opp1_table: opp1_table {
                   compatible = "operating-points-v2";
                   opp-shared;
           };
   };

Cache object: cc1a5bacad2e32744b5794c30ae0c939