[PATCH V5 1/3] OPP: Redefine bindings to overcome shortcomings
From: Rob Herring <hidden>
Date: 2015-05-20 13:27:59
Also in:
linux-devicetree, linux-pm
On Tue, May 19, 2015 at 10:41 PM, Viresh Kumar [off-list ref] wrote:
Current OPP (Operating performance point) DT bindings are proven to be insufficient at multiple instances. The shortcomings we are trying to solve here: - Getting clock/voltage/current rails sharing information between CPUs. Shared by all cores vs independent clock per core vs shared clock per cluster. - Support for specifying current levels along with voltages. - Support for multiple regulators. - Support for turbo modes. - Other per OPP settings: transition latencies, disabled status, etc.? - Expandability of OPPs in future. This patch introduces new bindings "operating-points-v2" to get these problems solved. Refer to the bindings for more details. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
This looks good to me: Reviewed-by: Rob Herring <robh@kernel.org> As I've mentioned before, I would like to see some users' acks on this as well. Rob
quoted hunk ↗ jump to hunk
--- Documentation/devicetree/bindings/power/opp.txt | 379 +++++++++++++++++++++++- 1 file changed, 375 insertions(+), 4 deletions(-)diff --git a/Documentation/devicetree/bindings/power/opp.txt b/Documentation/devicetree/bindings/power/opp.txt index 74499e5033fc..d132e2927b21 100644 --- a/Documentation/devicetree/bindings/power/opp.txt +++ b/Documentation/devicetree/bindings/power/opp.txt@@ -1,8 +1,19 @@ -* Generic OPP Interface +Generic OPP (Operating Performance Points) Bindings +---------------------------------------------------- -SoCs have a standard set of tuples consisting of frequency and -voltage pairs that the device will support per voltage domain. These -are called Operating Performance Points or OPPs. +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@@ -23,3 +34,363 @@ cpu at 0 { 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 descriptor in their DT node. The OPP core will use this phandle +to find the operating points for the device. + + +* OPP Descriptor 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 descriptor'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. + + +* OPP Node + +This defines voltage-current-frequency combinations along with other related +properties. + +Required properties: +- opp-hz: Frequency in Hz + +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 must be present in the same order as + regulators are specified in device's DT node. + +- 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 must be present in the same order as + regulators are specified in device's DT node. If this property isn't required + for few regulators, then this should be marked as zero for them. If it isn't + required for any regulator, then this property need not be 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. + +- 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 at 0 { + compatible = "arm,cortex-a9"; + reg = <0>; + next-level-cache = <&L2>; + clocks = <&clk_controller 0>; + clock-names = "cpu"; + opp-supply = <&cpu_supply0>; + operating-points-v2 = <&cpu0_opp>; + }; + + cpu at 1 { + compatible = "arm,cortex-a9"; + reg = <1>; + next-level-cache = <&L2>; + clocks = <&clk_controller 0>; + clock-names = "cpu"; + opp-supply = <&cpu_supply0>; + operating-points-v2 = <&cpu0_opp>; + }; + }; + + cpu0_opp: opp0 { + compatible = "operating-points-v2"; + opp-shared; + + entry00 { + opp-hz = <1000000000>; + opp-microvolt = <970000 975000 985000>; + opp-microamp = <70000>; + clock-latency-ns = <300000>; + }; + entry01 { + opp-hz = <1100000000>; + opp-microvolt = <980000 1000000 1010000>; + opp-microamp = <80000>; + clock-latency-ns = <310000>; + }; + entry02 { + opp-hz = <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 at 0 { + compatible = "qcom,krait"; + reg = <0>; + next-level-cache = <&L2>; + clocks = <&clk_controller 0>; + clock-names = "cpu"; + opp-supply = <&cpu_supply0>; + operating-points-v2 = <&cpu0_opp>; + }; + + cpu at 1 { + compatible = "qcom,krait"; + reg = <1>; + next-level-cache = <&L2>; + clocks = <&clk_controller 1>; + clock-names = "cpu"; + opp-supply = <&cpu_supply1>; + operating-points-v2 = <&cpu0_opp>; + }; + + cpu at 2 { + compatible = "qcom,krait"; + reg = <2>; + next-level-cache = <&L2>; + clocks = <&clk_controller 2>; + clock-names = "cpu"; + opp-supply = <&cpu_supply2>; + operating-points-v2 = <&cpu0_opp>; + }; + + cpu at 3 { + compatible = "qcom,krait"; + reg = <3>; + next-level-cache = <&L2>; + clocks = <&clk_controller 3>; + clock-names = "cpu"; + opp-supply = <&cpu_supply3>; + operating-points-v2 = <&cpu0_opp>; + }; + }; + + cpu0_opp: opp0 { + compatible = "operating-points-v2"; + + /* + * Missing opp-shared property means CPUs switch DVFS states + * independently. + */ + + entry00 { + opp-hz = <1000000000>; + opp-microvolt = <970000 975000 985000>; + opp-microamp = <70000>; + clock-latency-ns = <300000>; + }; + entry01 { + opp-hz = <1100000000>; + opp-microvolt = <980000 1000000 1010000>; + opp-microamp = <80000>; + clock-latency-ns = <310000>; + }; + entry02 { + opp-hz = <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 at 0 { + compatible = "arm,cortex-a7"; + reg = <0>; + next-level-cache = <&L2>; + clocks = <&clk_controller 0>; + clock-names = "cpu"; + opp-supply = <&cpu_supply0>; + operating-points-v2 = <&cluster0_opp>; + }; + + cpu at 1 { + compatible = "arm,cortex-a7"; + reg = <1>; + next-level-cache = <&L2>; + clocks = <&clk_controller 0>; + clock-names = "cpu"; + opp-supply = <&cpu_supply0>; + operating-points-v2 = <&cluster0_opp>; + }; + + cpu at 100 { + compatible = "arm,cortex-a15"; + reg = <100>; + next-level-cache = <&L2>; + clocks = <&clk_controller 1>; + clock-names = "cpu"; + opp-supply = <&cpu_supply1>; + operating-points-v2 = <&cluster1_opp>; + }; + + cpu at 101 { + compatible = "arm,cortex-a15"; + reg = <101>; + next-level-cache = <&L2>; + clocks = <&clk_controller 1>; + clock-names = "cpu"; + opp-supply = <&cpu_supply1>; + operating-points-v2 = <&cluster1_opp>; + }; + }; + + cluster0_opp: opp0 { + compatible = "operating-points-v2"; + opp-shared; + + entry00 { + opp-hz = <1000000000>; + opp-microvolt = <970000 975000 985000>; + opp-microamp = <70000>; + clock-latency-ns = <300000>; + }; + entry01 { + opp-hz = <1100000000>; + opp-microvolt = <980000 1000000 1010000>; + opp-microamp = <80000>; + clock-latency-ns = <310000>; + }; + entry02 { + opp-hz = <1200000000>; + opp-microvolt = <1025000>; + opp-microamp = <90000>; + clock-latency-ns = <290000>; + turbo-mode; + }; + }; + + cluster1_opp: opp1 { + compatible = "operating-points-v2"; + opp-shared; + + entry10 { + opp-hz = <1300000000>; + opp-microvolt = <1045000 1050000 1055000>; + opp-microamp = <95000>; + clock-latency-ns = <400000>; + }; + entry11 { + opp-hz = <1400000000>; + opp-microvolt = <1075000>; + opp-microamp = <100000>; + clock-latency-ns = <400000>; + }; + entry12 { + opp-hz = <1500000000>; + opp-microvolt = <1010000 1100000 1110000>; + opp-microamp = <95000>; + clock-latency-ns = <400000>; + turbo-mode; + }; + }; +}; + +Example 4: Handling multiple regulators + +/ { + cpus { + cpu at 0 { + compatible = "arm,cortex-a7"; + ... + + opp-supply = <&cpu_supply0>, <&cpu_supply1>, <&cpu_supply2>; + operating-points-v2 = <&cpu0_opp>; + }; + }; + + cpu0_opp: opp0 { + compatible = "operating-points-v2"; + opp-shared; + + entry00 { + opp-hz = <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 */ + + entry00 { + opp-hz = <1000000000>; + opp-microvolt = <970000 975000 985000>, /* Supply 0 */ + <960000 965000 975000>, /* Supply 1 */ + <960000 965000 975000>; /* Supply 2 */ + opp-microamp = <70000>, /* Supply 0 */ + <70000>, /* Supply 1 */ + <70000>; /* Supply 2 */ + clock-latency-ns = <300000>; + }; + + /* OR */ + + entry00 { + opp-hz = <1000000000>; + opp-microvolt = <970000 975000 985000>, /* Supply 0 */ + <960000 965000 975000>, /* Supply 1 */ + <960000 965000 975000>; /* Supply 2 */ + opp-microamp = <70000>, /* Supply 0 */ + <0>, /* Supply 1 doesn't need this */ + <70000>; /* Supply 2 */ + clock-latency-ns = <300000>; + }; + }; +}; --2.4.0 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html