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.
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 */
};
};
};
