Adding bindings to represent a virtual cpufreq device. Virtual machines may expose MMIO regions for a virtual cpufreq device for guests to read frequency information or to request frequency selection. The virtual cpufreq device has an individual controller for each frequency domain. Performance points for a given domain can be normalized across all domains for ease of allowing for virtual machines to migrate between hosts. Co-developed-by: Saravana Kannan <saravanak@xxxxxxxxxx> Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx> Signed-off-by: David Dai <davidai@xxxxxxxxxx> --- .../cpufreq/qemu,cpufreq-virtual.yaml | 110 ++++++++++++++++++ 1 file changed, 110 insertions(+) create mode 100644 Documentation/devicetree/bindings/cpufreq/qemu,cpufreq-virtual.yaml diff --git a/Documentation/devicetree/bindings/cpufreq/qemu,cpufreq-virtual.yaml b/Documentation/devicetree/bindings/cpufreq/qemu,cpufreq-virtual.yaml new file mode 100644 index 000000000000..cd617baf75e7 --- /dev/null +++ b/Documentation/devicetree/bindings/cpufreq/qemu,cpufreq-virtual.yaml @@ -0,0 +1,110 @@ +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/cpufreq/qemu,cpufreq-virtual.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Virtual CPUFreq + +maintainers: + - David Dai <davidai@xxxxxxxxxx> + - Saravana Kannan <saravanak@xxxxxxxxxx> + +description: + Virtual CPUFreq is a virtualized driver in guest kernels that sends frequency + selection of its vCPUs as a hint to the host through MMIO regions. Each vCPU + is associated with a frequency domain which can be shared with other vCPUs. + Each frequency domain has its own set of registers for frequency controls. + +properties: + compatible: + const: qemu,virtual-cpufreq + + reg: + maxItems: 1 + description: + Address and size of region containing frequency controls for each of the + frequency domains. Regions for each frequency domain is placed + contiguously and contain registers for controlling DVFS(Dynamic Frequency + and Voltage) characteristics. The size of the region is proportional to + total number of frequency domains. This device also needs the CPUs to + list their OPPs using operating-points-v2 tables. The OPP tables for the + CPUs should use normalized "frequency" values where the OPP with the + highest performance among all the vCPUs is listed as 1024 KHz. The rest + of the frequencies of all the vCPUs should be normalized based on their + performance relative to that 1024 KHz OPP. This makes it much easier to + migrate the VM across systems which might have different physical CPU + OPPs. + +required: + - compatible + - reg + +additionalProperties: false + +examples: + - | + // This example shows a two CPU configuration with a frequency domain + // for each CPU showing normalized performance points. + cpus { + #address-cells = <1>; + #size-cells = <0>; + + cpu@0 { + compatible = "arm,armv8"; + device_type = "cpu"; + reg = <0x0>; + operating-points-v2 = <&opp_table0>; + }; + + cpu@1 { + compatible = "arm,armv8"; + device_type = "cpu"; + reg = <0x0>; + operating-points-v2 = <&opp_table1>; + }; + }; + + opp_table0: opp-table-0 { + compatible = "operating-points-v2"; + + opp64000 { opp-hz = /bits/ 64 <64000>; }; + opp128000 { opp-hz = /bits/ 64 <128000>; }; + opp192000 { opp-hz = /bits/ 64 <192000>; }; + opp256000 { opp-hz = /bits/ 64 <256000>; }; + opp320000 { opp-hz = /bits/ 64 <320000>; }; + opp384000 { opp-hz = /bits/ 64 <384000>; }; + opp425000 { opp-hz = /bits/ 64 <425000>; }; + }; + + opp_table1: opp-table-1 { + compatible = "operating-points-v2"; + + opp64000 { opp-hz = /bits/ 64 <64000>; }; + opp128000 { opp-hz = /bits/ 64 <128000>; }; + opp192000 { opp-hz = /bits/ 64 <192000>; }; + opp256000 { opp-hz = /bits/ 64 <256000>; }; + opp320000 { opp-hz = /bits/ 64 <320000>; }; + opp384000 { opp-hz = /bits/ 64 <384000>; }; + opp448000 { opp-hz = /bits/ 64 <448000>; }; + opp512000 { opp-hz = /bits/ 64 <512000>; }; + opp576000 { opp-hz = /bits/ 64 <576000>; }; + opp640000 { opp-hz = /bits/ 64 <640000>; }; + opp704000 { opp-hz = /bits/ 64 <704000>; }; + opp768000 { opp-hz = /bits/ 64 <768000>; }; + opp832000 { opp-hz = /bits/ 64 <832000>; }; + opp896000 { opp-hz = /bits/ 64 <896000>; }; + opp960000 { opp-hz = /bits/ 64 <960000>; }; + opp1024000 { opp-hz = /bits/ 64 <1024000>; }; + + }; + + soc { + #address-cells = <1>; + #size-cells = <1>; + + cpufreq@1040000 { + compatible = "qemu,virtual-cpufreq"; + reg = <0x1040000 0x10>; + }; + }; -- 2.43.0.429.g432eaa2c6b-goog
