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