[PATCH v9 0/2] Add driver support for ESWIN EIC7700 PVT controller

[dongxuyang@eswincomputing.com]

From: Xuyang Dong <dongxuyang@eswincomputing.com>

Add support for the ESWIN EIC7700 PVT (Voltage, Temperature) sensor

Features:
The driver supports monitoring of voltage and temperature parameters
through the hardware monitoring subsystem. It provides an access to the
sampled Temperature and Voltage.

Test:
Tested this patch on the SiFive HiFive Premier P550 (which uses the ESWIN
EIC7700 SoC).

Updates:
  Changes in v9:
  - Taking over from Huan He <hehuan1@eswincomputing.com>, who has left the 
    company and whose email is no longer reachable. 
    Huan He's Signed-off-by tag is retained to acknowledge the original 
    contribution.
  - Update eswin,eic7700-pvt.yaml
    - Add 'Reviewed-by: Conor Dooley <conor.dooley@microchip.com>' tag.
  - Update eic7700-pvt.c and eic7700-pvt.h
    - Remove config HWMON.
    - Add eic7700_pvt_set_trim(pvt, PVT_TRIM_DEF) in
      eic7700_pvt_runtime_resume(). Re-apply the trim values to prevent
      incorrect sensor readings upon wake (Sashiko review of v8).

  - Link to v8: https://lore.kernel.org/all/20260625061049.1614-1-hehuan1@eswincomputing.com/

  Changes in v8:
  - Update eswin,eic7700-pvt.yaml
    - Delete reviewed-by tag of Krzysztof Kozlowski due to functional
      changes. Add the APB clock because when the kernel is booted with
      CMDLINE option "clk_ignore_unused", the APB clock remains enabled by
      default; without this option, the APB clock may be gated and the PVT
      driver will not operate correctly
  - Update eic7700-pvt.c and eic7700-pvt.h
    - Add APB clock support and retrieve clocks using devm_clk_bulk_get()
    - Update eic7700_pvt_hard_isr() to verify PVT_INT_STAT before clearing
      the interrupt and completing a conversion, preventing spurious
      interrupts from returning stale data or completing a conversion early
    - Update eic7700_pvt_probe() to register the PM runtime cleanup action
      before requesting the IRQ, so the IRQ is torn down before clocks are
      disabled during driver removal, preventing a possible
      use-after-disable of the hardware clock in the ISR

  - Link to v7: https://lore.kernel.org/all/20260611090505.734-1-hehuan1@eswincomputing.com/

  Changes in v7:
  - Remove the unused reset control pointer from struct pvt_hwmon and keep
    the reset control handle local to eic7700_pvt_probe()
  - Update eic7700_pvt_init_iface() to disable PVT_ENA_EN before clearing
    the interrupt status, preventing a possible level-triggered interrupt
    storm if the bootloader leaves the conversion engine running
  - Update eic7700_pvt_disable_pm_runtime() to explicitly disable runtime
    PM and avoid an unbalanced disable_depth

  - Link to v6: https://lore.kernel.org/all/20260604080430.126-1-hehuan1@eswincomputing.com/

  Changes in v6:
  - Fix the !CONFIG_PM probe error path by disabling the clock if IRQ
    request fails before the PM cleanup action is registered
  - Replace pm_runtime_put_noidle() with pm_runtime_put() in the IRQ
    handler to avoid a runtime PM reference-count race with the read path
  - Remove the unused pvt_clear_data() devres action and its associated
    devm_add_action() registration

  - Link to v5: https://lore.kernel.org/all/20260515091942.449-1-hehuan1@eswincomputing.com/

  Changes in v5:
  - Update eswin,eic7700-pvt.yaml
    - Drop the label enum constraint and remove label from the required
      list
    - Add '#thermal-sensor-cells' to the required list
    - Rename the example node to the generic sensor@... form
    - Update the binding description to describe one temperature sensor
      and one voltage sensor
  - Update eic7700-pvt.c
    - Register the hwmon device with the fixed name "pvt"
    - Remove label-based instance identification from the driver
    - Fix CONFIG_PM=n support by keeping the clock enabled when runtime PM
      is unavailable
    - Add pm_runtime_force_suspend() in the cleanup path to avoid leaving
      the device active during unbind
    - Switch system sleep callbacks to pm_runtime_force_suspend() and
      pm_runtime_force_resume()
    - Guard ISR register accesses with pm_runtime_get_if_active()
    - Add synchronize_irq() on the timeout path to avoid stale completion
      races
    - Remove temp_offset support because the raw trim register does not
      match the hwmon ABI
    - Align the commit message with the implementation (one temperature
      sensor, one voltage sensor)

  - Link to v4: https://lore.kernel.org/all/20260430064107.1598-1-hehuan1@eswincomputing.com/

  Changes in v4:
  - Update eswin,eic7700-pvt.yaml
    - Delete reviewed-by tag of Conor Dooley, because the label enum
      constraint is introduced
  - Update eic7700-pvt.c and eic7700-pvt.h
    - Remove the unused LVT/ULVT/SVT process-monitoring channels
    - Remove the probe-time power check since the PVT block is always
      powered on EIC7700 and the extra verification is unnecessary
    - Stop requesting the interrupt as shared and use the dedicated PVT IRQ
      only
    - Reorder probe initialization so the interface is initialized before
      the clock is disabled, avoiding register accesses with the clock gated
    - Fix runtime PM reference handling on error paths by balancing
      pm_runtime_get_noresume() with pm_runtime_put_noidle()
    - Add pm_runtime_put_noidle() handling for failed pm_runtime_get_sync()
      calls in hwmon read/write paths
    - Switch the PM callback registration from pm_sleep_ptr() to pm_ptr()

  - Link to v3: https://lore.kernel.org/all/20260306094312.1043-1-hehuan1@eswincomputing.com/

  Changes in v3:
  - Update eswin,eic7700-pvt.yaml
    - Remove redundant label property description and use 'label: true' to
      reference the definition in hwmon-common.yaml
    - Replace 'additionalProperties: false' with
      'unevaluatedProperties: false'
    - Remove the description for '#thermal-sensor-cells'
  - Update eic7700-pvt.c and eic7700-pvt.h
    - Fix clock reference count imbalance with Runtime PM:
      Replace devm_clk_get_enabled() with devm_clk_get() and manually
      manage clock enable/disable to avoid double-disable in remove() when
      Runtime PM is active. Clock is now enabled only during probe for
      eic7700_pvt_check_pwr(), then disabled before enabling Runtime PM,
      which takes full control of the clock thereafter
    - Add detailed comment explaining the spurious interrupt risk in
      eic7700_pvt_check_pwr()
    - Replace wait_for_completion_interruptible() with
      wait_for_completion_timeout() to prevent infinite wait

  - Link to v2: https://lore.kernel.org/all/20260128101400.859-1-hehuan1@eswincomputing.com/

  Changes in v2:
  - Update eswin,eic7700-pvt.yaml
    - Reference the hwmon-common.yaml file
    - Remove the clock-names and reset-names properties
    - Move additionalProperties: false after the required block
    - Remove one example node to avoid redundancy
  - Update eic7700-pvt.c and eic7700-pvt.h
    - Remove unused sensor macros (PVT_SENSOR_FIRST, PVT_SENSOR_LAST,
      PVT_SENSORS_NUM)
    - Drop the unnecessary hwmon-sysfs.h header
    - Replace dynamic sensor info allocation with a static array and unify
      sensor labels
    - Remove unused hwmon_temp_type attribute
    - Eliminate redundant validation checks
    - Remove mutex and related locking, relying on hwmon core
      serialization
    - Replace per-sensor caches and completions with a single data cache
      and completion object
    - Remove pvt->sensor tracking. ISR no longer depends on the currently
      selected sensor
    - Move devm_add_action() registration after init_completion() for
      safer cleanup, and update cleanup function (pvt_clear_data)
    - Replace devm_reset_control_get_optional_exclusive() with
      devm_reset_control_get_exclusive_deasserted()
    - Replace eic7700_pvt_remove() with eic7700_pvt_disable_pm_runtime()
      and move it after PM runtime enable to avoid resource leaks on probe
      failure and remove clock disable and reset assert from
      eic7700_pvt_disable_pm_runtime() as it is already handled by devm_*
      framework
    - Remove redundant clock presence check in runtime_resume

  - Link to v1: https://lore.kernel.org/all/20260109090718.442-1-hehuan1@eswincomputing.com/

Huan He (2):
  dt-bindings: hwmon: Add Eswin EIC7700 PVT sensor
  hwmon: Add Eswin EIC7700 PVT sensor driver

 .../bindings/hwmon/eswin,eic7700-pvt.yaml     |  72 +++
 drivers/hwmon/Kconfig                         |  11 +
 drivers/hwmon/Makefile                        |   1 +
 drivers/hwmon/eic7700-pvt.c                   | 509 ++++++++++++++++++
 drivers/hwmon/eic7700-pvt.h                   |  99 ++++
 5 files changed, 692 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/eswin,eic7700-pvt.yaml
 create mode 100644 drivers/hwmon/eic7700-pvt.c
 create mode 100644 drivers/hwmon/eic7700-pvt.h

--
2.34.1