dt-bindings: interconnect: qcom,msm8998-cpu-bwmon: add BWMON device

Add bindings for the Qualcomm Bandwidth Monitor device providing
performance data on interconnects.  The bindings describe only BWMON CPU
(version 4), e.g. the instance which appeared for the first on Qualcomm
MSM8998 SoC and is also used on SDM845.  This BWMON device sits between
CPU and Last Level Cache Controller.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Georgi Djakov <djakov@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220704121730.127925-2-krzysztof.kozlowski@linaro.org

Documentation/devicetree/bindings/interconnect/qcom,msm8998-bwmon.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/interconnect/qcom,msm8998-bwmon.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Interconnect Bandwidth Monitor
+
+maintainers:
+  - Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
+
+description: |
+  Bandwidth Monitor measures current throughput on buses between various NoC
+  fabrics and provides information when it crosses configured thresholds.
+
+  Certain SoCs might have more than one Bandwidth Monitors, for example on SDM845::
+   - Measuring the bandwidth between CPUs and Last Level Cache Controller -
+     called just BWMON,
+   - Measuring the bandwidth between Last Level Cache Controller and memory
+     (DDR) - called LLCC BWMON.
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - qcom,sdm845-bwmon
+          - const: qcom,msm8998-bwmon
+      - const: qcom,msm8998-bwmon       # BWMON v4
+
+  interconnects:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  operating-points-v2: true
+  opp-table: true
+
+  reg:
+    # BWMON v4 (currently described) and BWMON v5 use one register address
+    # space.  BWMON v2 uses two register spaces - not yet described.
+    maxItems: 1
+
+required:
+  - compatible
+  - interconnects
+  - interrupts
+  - operating-points-v2
+  - opp-table
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interconnect/qcom,sdm845.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    pmu@1436400 {
+        compatible = "qcom,sdm845-bwmon", "qcom,msm8998-bwmon";
+        reg = <0x01436400 0x600>;
+        interrupts = <GIC_SPI 581 IRQ_TYPE_LEVEL_HIGH>;
+        interconnects = <&gladiator_noc MASTER_APPSS_PROC 3 &mem_noc SLAVE_LLCC 3>;
+
+        operating-points-v2 = <&cpu_bwmon_opp_table>;
+
+        cpu_bwmon_opp_table: opp-table {
+            compatible = "operating-points-v2";
+            opp-0 {
+                opp-peak-kBps = <4800000>;
+            };
+            opp-1 {
+                opp-peak-kBps = <9216000>;
+            };
+            opp-2 {
+                opp-peak-kBps = <15052800>;
+            };
+            opp-3 {
+                opp-peak-kBps = <20889600>;
+            };
+            opp-4 {
+                opp-peak-kBps = <25497600>;
+            };
+        };
+    };