[v5,0/5] Add support for QCOM Core Power Reduction

Message

Niklas Cassel Nov. 15, 2019, 12:15 p.m. UTC

This series adds support for Core Power Reduction (CPR), a form of
Adaptive Voltage Scaling (AVS), found on certain Qualcomm SoCs.

This series is based on top of the qcs404 cpufreq patch series that
hasn't landed yet:
https://patchwork.kernel.org/project/linux-arm-msm/list/?series=173423
as well as that series' matching device tree changes:
https://patchwork.kernel.org/project/linux-arm-msm/list/?series=165457

CPR is a technology that reduces core power on a CPU or on other device.
It reads voltage settings from efuses (that have been written in
production), it uses these voltage settings as initial values, for each
OPP.

After moving to a certain OPP, CPR monitors dynamic factors such as
temperature, etc. and adjusts the voltage for that frequency accordingly
to save power and meet silicon characteristic requirements.

This driver has been developed together with Jorge Ramirez-Ortiz, and
is based on an RFC by Stephen Boyd[1], which in turn is based on work
by others on codeaurora.org[2].

[1] https://lkml.org/lkml/2015/9/18/833
[2] https://www.codeaurora.org/cgit/quic/la/kernel/msm-3.10/tree/drivers/regulator/cpr-regulator.c?h=msm-3.10

Changes since V4:
Implemented review comments from Stephen Boyd.
Removed suspend()/resume(), since they did the same things as ->power_on()/
->power_off() genpd callbacks.

Niklas Cassel (5):
  dt-bindings: power: avs: Add support for CPR (Core Power Reduction)
  power: avs: Add support for CPR (Core Power Reduction)
  arm64: dts: qcom: qcs404: Add CPR and populate OPP table
  arm64: defconfig: enable CONFIG_QCOM_CPR
  arm64: defconfig: enable CONFIG_ARM_QCOM_CPUFREQ_NVMEM

 .../bindings/power/avs/qcom,cpr.txt           |  130 ++
 MAINTAINERS                                   |    8 +
 arch/arm64/boot/dts/qcom/qcs404.dtsi          |  132 +-
 arch/arm64/configs/defconfig                  |    2 +
 drivers/power/avs/Kconfig                     |   15 +
 drivers/power/avs/Makefile                    |    1 +
 drivers/power/avs/qcom-cpr.c                  | 1755 +++++++++++++++++
 7 files changed, 2035 insertions(+), 8 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/power/avs/qcom,cpr.txt
 create mode 100644 drivers/power/avs/qcom-cpr.c