Adding bindings to represent a virtual cpufreq device.
Virtual machines may expose MMIO regions for a virtual cpufreq device
for guests to read performance information or to request performance
selection. The virtual cpufreq device has an individual controller for
each performance 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@google.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: David Dai <davidai@google.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
---
.../cpufreq/qemu,virtual-cpufreq.yaml | 48 +++++++++++++++++++
1 file changed, 48 insertions(+)
create mode 100644 Documentation/devicetree/bindings/cpufreq/qemu,virtual-cpufreq.yaml
diff --git a/Documentation/devicetree/bindings/cpufreq/qemu,virtual-cpufreq.yaml b/Documentation/devicetree/bindings/cpufreq/qemu,virtual-cpufreq.yaml
new file mode 100644
index 000000000000..018d98bcdc82
--- /dev/null
+++ b/Documentation/devicetree/bindings/cpufreq/qemu,virtual-cpufreq.yaml
@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/cpufreq/qemu,virtual-cpufreq.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Virtual CPUFreq
+
+maintainers:
+ - David Dai <davidai@google.com>
+ - Saravana Kannan <saravanak@google.com>
+
+description:
+ Virtual CPUFreq is a virtualized driver in guest kernels that sends performance
+ selection of its vCPUs as a hint to the host through MMIO regions. Each vCPU
+ is associated with a performance domain which can be shared with other vCPUs.
+ Each performance domain has its own set of registers for performance controls.
+
+properties:
+ compatible:
+ const: qemu,virtual-cpufreq
+
+ reg:
+ maxItems: 1
+ description:
+ Address and size of region containing performance controls for each of the
+ performance domains. Regions for each performance 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 performance domains.
+
+required:
+ - compatible
+ - reg
+
+additionalProperties: false
+
+examples:
+ - |
+ soc {
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+ cpufreq@1040000 {
+ compatible = "qemu,virtual-cpufreq";
+ reg = <0x1040000 0x2000>;
+ };
+ };
--
2.46.0.792.g87dc391469-goog