regulator: add QCOM RPMh regulator driver

This patch series adds a driver and device tree binding documentation for PMIC regulator control via Resource Power Manager-hardened (RPMh) on some Qualcomm Technologies, Inc. SoCs such as SDM845. RPMh is a hardware block which contains several accelerators which are used to manage various hardware resources that are shared between the processors of the SoC. The final hardware state of a regulator is determined within RPMh by performing max aggregation of the requests made by all of the processors.

The RPMh regulator driver depends upon the RPMh driver [1] and command DB driver [2] which are both still undergoing review. It also depends upon three recent regulator patches: [3], [4], and [5] as well as an RPMh helper patch [6].

Changes since v8 [7]:
- Used C++ style comment for qcom-rpmh-regulator.c copyright
- Removed RPMH_REGULATOR_MODE_COUNT
- Changed ternary operator to if else statement in rpmh_regulator_vrm_set_mode_bypass()
- Changed LDO mode mappings to use REGULATOR_MODE_NORMAL for HPM instead of REGULATOR_MODE_FAST
- Replaced mapping arrays with switch case statements in of_map_mode callback functions

Changes since v7 [8]:
- Removed the cmd_db_ready() call from the driver probe function as it is now handled by the RPMh driver itself [6]
- Added Reviewed-by tag for driver patch 2/2

Changes since v6 [9]:
- Removed 'count' parameter from rpmh_regulator_send_request() since it is always 1
- Fixed _rpmh_regulator_vrm_set_voltage_sel() return value
- Added a helper function to capture common code between rpmh_regulator_enable() and rpmh_regulator_disable()
- Added an iterator for pmic_rpmh_data in rpmh_regulator_init_vreg()
- Added Reviewed-by tag for both patches

Changes since v5 [10]:
- Removed unused constants
- Added Reviewed-by tag for DT patch 1/2

Changes since v4 [11]:
- Removed support for DT properties qcom,regulator-drms-modes and qcom,drms-mode-max-microamps
- Specified fixed DRMS high power mode minimum limits for LDO type regulators
- Removed DRMS support for SMPS and BOB type regulators
- Simplified voltage caching logic

Changes since v3 [12]:
- Removed support for DT properties qcom,regulator-initial-microvolt and qcom,headroom-microvolt
- Renamed DT property qcom,allowed-drms-modes to be qcom,regulator-drms-modes
- Updated DT binding documentation to mention which common regulator bindings can be used for qcom-rpmh-regulator devices
- Added voltage caching so that voltage requests are only sent to RPMh after the regulator has been enabled at least once
- Changed 'voltage_selector' default value to be -ENOTRECOVERABLE to interact with [5]
- Initialized 'enabled' to -EINVAL so that unused regulators are disabled by regulator_late_cleanup()
- Removed rpmh_regulator_load_default_parameters() as it is no longer needed
- Updated the mode usage description in qcom,rpmh-regulator.h

Changes since v2 [13]:
- Replaced '_' with '-' in device tree supply property names
- Renamed qcom_rpmh-regulator.c to be qcom-rpmh-regulator.c
- Updated various DT property names to use "microvolt" and "microamp"
- Moved allowed modes constraint specification out of the driver [4]
- Replaced rpmh_client with device pointer to match new RPMh API [1]
- Corrected drms mode threshold checking
- Initialized voltage_selector to -EINVAL when not specified in DT
- Added constants for PMIC regulator hardware modes
- Corrected type sign of mode mapping tables
- Made variable names for mode arrays plural
- Simplified Kconfig depends on
- Removed unnecessary constants and struct fields
- Added some descriptive comments

Changes since v1 [14]:
- Addressed review feedback from Doug, Mark, and Stephen
- Replaced set_voltage()/get_voltage() callbacks with set_voltage_sel()/ get_voltage_sel()
- Added set_bypass()/get_bypass() callbacks for BOB pass-through mode control
- Removed top-level PMIC data structures
- Removed initialization variables from structs and passed them as function parameters
- Removed various comments and error messages
- Simplified mode handling
- Refactored per-PMIC rpmh-regulator data specification
- Simplified probe function
- Moved header into DT patch
- Removed redundant property listings from DT binding documentation

[1]: https://lkml.org/lkml/2018/6/20/519
[2]: https://lkml.org/lkml/2018/4/10/714
[3]: https://lkml.org/lkml/2018/4/18/556
[4]: https://lkml.org/lkml/2018/5/11/696
[5]: https://lkml.org/lkml/2018/5/15/1005
[6]: https://lkml.org/lkml/2018/6/18/1188
[7]: https://lkml.org/lkml/2018/6/22/935
[8]: https://lkml.org/lkml/2018/6/8/573
[9]: https://lkml.org/lkml/2018/6/4/879
[10]: https://lkml.org/lkml/2018/6/1/895
[11]: https://lkml.org/lkml/2018/5/22/1168
[12]: https://lkml.org/lkml/2018/5/11/701
[13]: https://lkml.org/lkml/2018/4/13/687
[14]: https://lkml.org/lkml/2018/3/16/1431

David Collins (2):
regulator: dt-bindings: add QCOM RPMh regulator bindings
regulator: add QCOM RPMh regulator driver

 .../bindings/regulator/qcom,rpmh-regulator.txt     | 160 +++++
 drivers/regulator/Kconfig                          |   9 +
 drivers/regulator/Makefile                         |   1 +
 drivers/regulator/qcom-rpmh-regulator.c            | 769 +++++++++++++++++++++
 .../dt-bindings/regulator/qcom,rpmh-regulator.h    |  36 +
 5 files changed, 975 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/regulator/qcom,rpmh-regulator.txt
 create mode 100644 drivers/regulator/qcom-rpmh-regulator.c
 create mode 100644 include/dt-bindings/regulator/qcom,rpmh-regulator.h

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