[PATCH v4 1/2] dt-bindings: soc: qcom: Add RPM Master stats

From: Konrad Dybcio
Date: Mon Apr 17 2023 - 13:38:04 EST


The RPM MSG RAM contains per-RPM-master (e.g. APPS, ADSP etc.) sleep
statistics. They let one assess which core is actively preventing the
system from entering a true low-power mode.

Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
---
.../bindings/soc/qcom/qcom,rpm-master-stats.yaml | 69 ++++++++++++++++++++++
1 file changed, 69 insertions(+)

diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,rpm-master-stats.yaml b/Documentation/devicetree/bindings/soc/qcom/qcom,rpm-master-stats.yaml
new file mode 100644
index 000000000000..8a654979ce92
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom,rpm-master-stats.yaml
@@ -0,0 +1,69 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/qcom/qcom,rpm-master-stats.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Technologies, Inc. (QTI) RPM Master Stats
+
+maintainers:
+ - Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
+
+description: |
+ The Qualcomm RPM (Resource Power Manager) architecture includes a concept
+ of "RPM Masters". They can be thought of as "the local gang leaders", usually
+ spanning a single subsystem (e.g. APSS, ADSP, CDSP). All of the RPM decisons
+ (particularly around entering hardware-driven low power modes: XO shutdown
+ and total system-wide power collapse) are first made at Master-level, and
+ only then aggregated for the entire system.
+
+ The Master Stats provide a few useful bits that can be used to assess whether
+ our device has entered the desired low-power mode, how long it took to do so,
+ the duration of that residence, how long it took to come back online,
+ how many times a given sleep state was entered and which cores are actively
+ voting for staying awake.
+
+ This scheme has been used on various SoCs in the 2013-2023 era, with some
+ newer or higher-end designs providing this information through an SMEM query.
+
+properties:
+ compatible:
+ const: qcom,rpm-master-stats
+
+ qcom,rpm-msg-ram:
+ $ref: /schemas/types.yaml#/definitions/phandle-array
+ description: Phandle to an RPM MSG RAM slice containing the master stats
+ minItems: 1
+ maxItems: 5
+
+ qcom,master-names:
+ $ref: /schemas/types.yaml#/definitions/string-array
+ description:
+ The name of the RPM Master which owns the MSG RAM slice where this
+ instance of Master Stats resides
+ minItems: 1
+ maxItems: 5
+
+required:
+ - compatible
+ - qcom,rpm-msg-ram
+ - qcom,master-names
+
+additionalProperties: false
+
+examples:
+ - |
+ stats {
+ compatible = "qcom,rpm-master-stats";
+ qcom,rpm-msg-ram = <&apss_master_stats>,
+ <&mpss_master_stats>,
+ <&adsp_master_stats>,
+ <&cdsp_master_stats>,
+ <&tz_master_stats>;
+ qcom,master-names = "APSS",
+ "MPSS",
+ "ADSP",
+ "CDSP",
+ "TZ";
+ };
+...

--
2.40.0