soc: qcom: icc-bwmon: Add bandwidth monitoring driver

Bandwidth monitoring (BWMON) sits between various subsytems like CPU,
GPU, Last Level caches and memory subsystem.  The BWMON can be
configured to monitor the data throuhput between memory and other
subsytems.  The throughput is measured within specified sampling window
and is used to vote for corresponding interconnect bandwidth.

Current implementation brings support for BWMON v4, used for example on
SDM845 to measure bandwidth between CPU (gladiator_noc) and Last Level
Cache (memnoc).  Usage of this BWMON allows to remove fixed bandwidth
votes from cpufreq (CPU nodes) thus achieve high memory throughput even
with lower CPU frequencies.

The driver was tested on SDM845.

Co-developed-by: Thara Gopinath <thara.gopinath@gmail.com>
Signed-off-by: Thara Gopinath <thara.gopinath@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220704121730.127925-3-krzysztof.kozlowski@linaro.org

MAINTAINERS

@@ -16523,6 +16523,13 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/i2c/i2c-qcom-cci.txt
 F:	drivers/i2c/busses/i2c-qcom-cci.c
 
+QUALCOMM INTERCONNECT BWMON DRIVER
+M:	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
+L:	linux-arm-msm@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/interconnect/qcom,msm8998-bwmon.yaml
+F:	drivers/soc/qcom/icc-bwmon.c
+
 QUALCOMM IOMMU
 M:	Rob Clark <robdclark@gmail.com>
 L:	iommu@lists.linux-foundation.org

drivers/soc/qcom/Kconfig

@@ -230,4 +230,19 @@ config QCOM_APR
 	  application processor and QDSP6. APR is
 	  used by audio driver to configure QDSP6
 	  ASM, ADM and AFE modules.
+
+config QCOM_ICC_BWMON
+	tristate "QCOM Interconnect Bandwidth Monitor driver"
+	depends on ARCH_QCOM || COMPILE_TEST
+	select PM_OPP
+	help
+	  Sets up driver monitoring bandwidth on various interconnects and
+	  based on that voting for interconnect bandwidth, adjusting their
+	  speed to current demand.
+	  Current implementation brings support for BWMON v4, used for example
+	  on SDM845 to measure bandwidth between CPU (gladiator_noc) and Last
+	  Level Cache (memnoc).  Usage of this BWMON allows to remove some of
+	  the fixed bandwidth votes from cpufreq (CPU nodes) thus achieve high
+	  memory throughput even with lower CPU frequencies.
+
 endmenu

drivers/soc/qcom/Makefile

@@ -28,3 +28,4 @@ obj-$(CONFIG_QCOM_LLCC) += llcc-qcom.o
 obj-$(CONFIG_QCOM_RPMHPD) += rpmhpd.o
 obj-$(CONFIG_QCOM_RPMPD) += rpmpd.o
 obj-$(CONFIG_QCOM_KRYO_L2_ACCESSORS) +=	kryo-l2-accessors.o
+obj-$(CONFIG_QCOM_ICC_BWMON)	+= icc-bwmon.o