[PATCH v6 0/4] regulator: qcom-rpmh: Support RPMH address reads and use it for rpmh-regulators

This patch series adds a new `rpmh_read()` API to allow reading RPMH
addresses. Using this API enhances the RPMH regulator driver by adding
readback of the voltage/bypass/mode settings as they have been applied by
APPS during the bootloader stage, so regulator framework can get them
via `get_mode`, `get_bypass` & `get_voltage_selector` callbacks during
regulator registration.

This is needed because currently regulator framework does a unnecessary
write with `min-microvolt` DT setting for all the RPMH regulators during
regulator registration, because the first time after boot the value is
seen as -ENOTRECOVERABLE, as there is no option to read these regulator
settings.

With this change this unnecessary write can be avoided and regulator
framework gets a sense of the initial state set during the bootloader
stage for all regulator settings.

NOTE - During discussion on the v2 series - PATCH 3/4, reviewer had
inquired about possible need for the use of the sync_state() to handle the
"multiple" client case - for maintaining the regulator settings till all
the clients are probed.

This case was not covered in my previous series and had originally planned
to do that series separately. But after the discussion decided to merge
the 2 series as it seemed this would be a better approach. But after
working on sync_state change. I realized a basic issue with using
sync_state() for regulators - that its per-driver and not per-regulator
resource. But we needed a sync_state callback for each regulator separately.

I had been experimenting with few ideas but seems its going to need more
time for me to close on the equivalent solution that has per-regulator
sync_state or something to that effect. So I thought to close on this
series and attend to that separately.

Signed-off-by: Kamal Wadhwa <[email protected]>
---
Changes in v6:
- Dropped the `get_status()` callback and all associated status-tracking
  (vreg->status, rpmh_vreg_update_status(), rpmh_regulator_vrm_get_status()),
  as Mark pointed out get_status() must reflect actual hardware state, not a
  cached/driver-computed value, and the ENABLE/MODE/BYPASS registers are
  control/vote registers written by this driver rather than free-running
  status registers. Renamed determine_initial_status() to
  determine_initial_mode() accordingly; mode/bypass/voltage readback via
  get_mode()/get_bypass()/get_voltage_sel() is unaffected.
- Link to v5: https://patch.msgid.link/[email protected]

Changes in v5:
- In `_rpmh_regulator_vrm_get_voltage()`, removed the min/max voltage
  range check that was suppressing out-of-range readback values, as
  suggested by Mark. The raw hardware-read voltage is now always
  reported to the regulator framework. A separate patch will be sent
  to handle out-of-range voltage constraint handling in core.c.
- Sorted the `#include <linux/bits.h>` alphabetically with the rest of
  the include block, as pointed out by Konrad.
- Removed the `rpmh_regulator_read_data()` wrapper (a oneliner around
  `rpmh_read()`) and inlined `rpmh_read()` at each call site instead,
  as suggested by Konrad.
- Dropped the unnecessary `sts = 0` initialization in
  `rpmh_regulator_determine_initial_status()`, since it is always
  initialized before use, as pointed out by Konrad.
- Added a blank line above the `return` statements in the `!pmic_mode`
  block of `rpmh_regulator_determine_initial_status()`, for consistency
  with the rest of the function, as pointed out by Konrad.
- Link to v4: https://lore.kernel.org/all/[email protected]/

Changes in v4:
- Modified the register mask macros to use  GENMASK()/BIT() instead of
  numbers as suggested by reviewer.
- Removed the unreachable code in the determine_initial_status() for XOB
  type regulators status update logic as suggested by reviewer.
- Link to v3: https://lore.kernel.org/all/[email protected]/

Changes in v3:
- Removed "bypass_supported" as that is not needed for regulators
  that don't have set_bypass implemented, as pointed by Dmitry.
- Handled the corner case where the mode/bypass setting is read 0, but
  its unclear if the register has been set to 0 or its un-accessed.
- Dropped `convert_mode_to_status()` and use the `regulator_mode_to_status()`
  instead.
- Refactored some code to simplify the `status` update after every
  enable/mode/bypass setting change.
- Corrected subject line of all patches to have `regulator: qcom-rpmh:`
  for all the `qcom-rpmh-regulator.c` file changes, as pointed by Bjorn.
- Re-ordered the series to have the `rpmh.c` driver patches first and
  than `qcom-rpmh-regulator.c` driver patches as asked by Bjorn.
- In the BOB5 bypass fix patch (PATCH 1/4 in previous series), added
  the fixes commit#, as it was missed earlier.
- In the rpmh driver change(PATCH 2/4 in previous series), modified
  commit wording and removed linked as suggested by reviewer.
- Fixed kernel test robot issues and other formatting issues in
  PATCH 3/4 of last series.
- Corrected the checkpatch error fix PATCH 4/4 to keep to only
  one error in comment section which existed prior to this
  series.
- Modified the subject line a little and added proper tags
- Link to v2: https://lore.kernel.org/all/20251022-add-rpmh-read-support-v2-0-5c7a8e4df601@oss.qualcomm.com/

Changes in v2:
- Fixed the BOB bypass mode handling (existing issue in current driver).
  This was needed for `get_status()` implementation.
- Implemented `get_status()` callback.
- Callbacks for `is_enabled()` & `get_mode()` will now be used as-is
  ie. v1 changes reverted.
- Bootstrapped the read values for `mode` and `status` in probe, based on
  comments received from reviewer.
- Callback for `get_voltage_sel()` has been modified to handle cases
  where read voltage is out-of-range defined in the regulator DT settings,
  this is needed to ensure backward compatibilty. Regulator probes may
  fail otherwise for some older targets.
- This patch is rebased & tested on:
  https://lore.kernel.org/all/[email protected]/
  to avoid any merge issues.
- Fixed code style issues reported by checkpatch.pl script.
- Link to v1: https://lore.kernel.org/r/20250623-add-rpmh-read-support-v1-0-ae583d260195@oss.qualcomm.com

To: Bjorn Andersson <[email protected]>
To: Konrad Dybcio <[email protected]>
To: Liam Girdwood <[email protected]>
To: Mark Brown <[email protected]>
To: Vinod Koul <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Kamal Wadhwa <[email protected]>

---
Kamal Wadhwa (3):
      regulator: qcom-rpmh: Fix PMIC5 BOB bypass mode handling
      regulator: qcom-rpmh: readback voltage/bypass/mode set during bootup
      regulator: qcom-rpmh: Fix coding style issues

Maulik Shah (1):
      soc: qcom: rpmh: Add support to read back resource settings

 drivers/regulator/qcom-rpmh-regulator.c | 128 +++++++++++++++++++++++++++++++-
 drivers/soc/qcom/rpmh-rsc.c             |  13 +++-
 drivers/soc/qcom/rpmh.c                 |  47 +++++++++++-
 include/soc/qcom/rpmh.h                 |   5 ++
 include/soc/qcom/tcs.h                  |   2 +
 5 files changed, 187 insertions(+), 8 deletions(-)
---
base-commit: 5c73cd9f0819c1c44e373e3dabb68318b1de1a12
change-id: 20260720-b4-read-rpmh-v5-bab1bd1cbe55

Best regards,
--  
Kamal Wadhwa <[email protected]>