[PATCH v6 0/2] input: misc: Add an initial driver for haptics inside Qcom PMIH010x PMIC

Qualcomm PMIH0108 PMIC has a haptics module inside and it could drive
a LRA actuator with several play modes, including: DIRECT_PLAY, FIFO,
PAT_MEM, SWR, etc. Add an initial driver to support two of the play
modes using the input force-feedback framework:

-- FF_CONSTANT effect for DIRECT_PLAY mode which drives sinusoidual
  waveforms with fixed period and amplitude, which would generate
  a constant vibration effect on the LRA actuator.

-- FF_PERIODIC effect with FF_CUSTOM for FIFO streaming mode, which
  can play an arbitrary waveform composed of a sequence of 8-bit
  samples at a configurable play rate.

Also, add the device node in the existing pmih0108 dtsi files, and enble
the haptics device for several boards by updating the vmax and
lra-period sttings according to the LRA components that mounted on each
of them.

Signed-off-by: Fenglin Wu <redacted>
---
Changes in v6:
Drop patch [2/3] as it has been applied in
  https://lore.kernel.org/linux-input/178602255123.2917765.7426706813083510078.b4-ty@b4/ (local)

Fixed Sashiko review comments:
- Add FF_SINE waveform support since FF_RUMBLE would be converted to FF_PERIODIC
  effect with FF_SINE waveform, and it is required to be supported. Also, clamp the
  FIFO play length with replay.length, also document the limitation of supporting
  replay.delay, u.periodic.magnitude and the envelope
- Add a separate worker to handle timeout stop, which gives a clear
  way to distinguish timeout stop requests from actual play stop requests.
- Replace disable_delayed_work_sync() in close() to cancel_delayed_work_sync()
  as it caused an issue that the work would be disabled permanently.
- Move haptics_enable_module(h, false) into the reset action(). Calling it
  in close() would desynchronize the runtime PM state and could cause issues
  if a play is triggered after close() and before the auto suspend timer
  expires.
- Link to v5: https://patch.msgid.link/20260804-qcom-spmi-haptics-v5-0-77128ebbdd2d@oss.qualcomm.com

Changes in v5:
Fixed review comments from Dmitry:
- Change to use "err" for the "ret" which hold error code
- Remove "haptics_queue_pending(...)" functtion and inline it into the
  caller.
- In haptics_fifo_empty_irq() when writing FIFO chunk failed, instead of
  stop the plan immediately, just clear the FIFO threshold to mask the
  interrupt.
- Add "lockdep_assert_held(&h->play_lock)" for the helper functions
  which require to be called when the lock is held.
- Add "gain_work" to handle set_gain() immediately.
- Set input device bus_type to "BUS_HOST".
- Move the remove teardown to input device close()
- Link to v4: https://patch.msgid.link/20260717-qcom-spmi-haptics-v4-0-b0fe0ed30849@oss.qualcomm.com

Changes in v4:
Fixed Sashiko AI review comments in the driver:
- In haptics_start_fifo(), remove the goto and do the clear in the error
  paths directly, also add a comment to explain that disabling the IRQ
  synchronously won't cause a deadlock.
- When data refilling failed in IRQ handler, stop the play and disable
  the IRQ to avoid the potential IRQ storming issue
- in play_work(), check if the effect_id in the request is the one which
  under playing before stopping the play.
- Link to v3: https://patch.msgid.link/20260713-qcom-spmi-haptics-v3-0-c931bb7cb94f@oss.qualcomm.com

Also, add trailers in the binding changes.

Changes in v3:

In the binding:
- Removed the ref for qcom,vmax-microvolt as the property with standard
  unit already has a ref in dtschema
- Added 'qcom,pmih0108-haptics' as a device-specific compatible

In the driver, fixed Sashiko AI review comments with below changes:
- Added a list to queue and serialize all of the request, which helps to
  avoid the races between playback(), which is protected by evdev's event_lock,
  and play_work(), which is protected by play_lock.
- Changed to use guard(mutex) or scoped_guard(mutex, ) for cleaner mutex logic
  usages, and update protection section to prevent race conditions.
- Added runtime pm control in haptics_stop() function, use it as an unified interface
  under the guard of 'play_lock' in play_work()/erase()/remove()/suspend(),
  to ensure the runtime pm control correctness in race conditions.
- Removed unnecessary stop play sequence in fifo_empty_irq() as the HW would
  automatically stop after the FIFO samples are played out.
- Added a common interface haptics_clear_effect() to clear the FIFO data with gaurd
  of 'fifo_lock', and use it before upload() and in erase() to prevent race
  condition.
- used __free() for safe memory cleanup
- Checked play_rate against negative value when loading FF_PERIOD effect
- Limited the custom_data length to 48K prevent potential OOM

- Link to v2: https://patch.msgid.link/20260624-qcom-spmi-haptics-v2-0-b9118e60f3e3@oss.qualcomm.com

Changes in v2:

Dropped dtsi change and I will resend them after the driver and binding changes get accepted.

Updated haptics binding and addressed review comments from Krzysztof and Konrad:
- Extended the description to clarify the 'PAT_MEM' mode (not yet supported in the driver)
  by comparing it with the 'FIFO' mode.
- Updated the compatible string to 'qcom,spmi-haptics' to match the file name and removed
  the PMIC wildcard.
- Simplified register names to 'cfg' and 'ptn'.
- Corrected the unit naming for the 'qcom,vmax-microvolt' property.
- Added an additional clarification for the 'qcom,lra-period-us' property.

Updated the driver to address review comments from Konrad and Julian:
- In haptics_write_fifo_chunk(), separated variable declaration and assignment, and added
  comments explaining the 4-byte and 1-byte FIFO writes.
- Replaced manual 'x * n / d' calculations with mult_frac().
- Switched to disable_irq() to prevent late IRQs after device removal.
- Replaced property reads with device_property_read_u32().
- Remove the 'INPUT' dependency in Kconfig

Updated the driver to address feedback from Sashiko AI:
- Guarded pm_runtime_resume()/suspend() with 'pm_ref_held' to prevent runtime PM reference leaks.
- Replaced spinlock with a mutex to protect FIFO data during playback and avoid calling
  sleepable regmap APIs under spinlock.
- Adjusted suspend/remove() sequence to stop playback before canceling work, and freed
  FIFO buffers to prevent potential memory leaks.
- In FF_PERIODIC handling, allocated 'fifo_data' before assigning data to ensure its
  consistency with 'data_len'.
- Registered the input device after enabling runtime PM.
- Unify to use 'h->dev' pointer in probe()

- Link to v1: https://patch.msgid.link/20260616-qcom-spmi-haptics-v1-0-d24e422de6b4@oss.qualcomm.com

---
Fenglin Wu (2):
      dt-bindings: input: Add Qualcomm SPMI PMIC haptics
      input: misc: Add Qualcomm SPMI PMIC haptics driver

 .../bindings/input/qcom,spmi-haptics.yaml          |  136 +++
 drivers/input/misc/Kconfig                         |   11 +
 drivers/input/misc/Makefile                        |    1 +
 drivers/input/misc/qcom-spmi-haptics.c             | 1252 ++++++++++++++++++++
 4 files changed, 1400 insertions(+)
---
base-commit: 66725039f7090afe14c31bd259e2059a68f04023
change-id: 20260616-qcom-spmi-haptics-3cc97e7b232e

Best regards,
--  
Fenglin Wu [off-list ref]