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 <fenglin.wu@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-...

---
Fenglin Wu (3):
      dt-bindings: input: Add Qualcomm SPMI PMIC haptics
      dt-bindings: mfd: qcom,spmi-pmic: Document haptics device
      input: misc: Add Qualcomm SPMI PMIC haptics driver

 .../bindings/input/qcom,spmi-haptics.yaml          | 132 ++++
 .../devicetree/bindings/mfd/qcom,spmi-pmic.yaml    |   4 +
 drivers/input/misc/Kconfig                         |  11 +
 drivers/input/misc/Makefile                        |   1 +
 drivers/input/misc/qcom-spmi-haptics.c             | 838 +++++++++++++++++++++
 5 files changed, 986 insertions(+)
---
base-commit: 66725039f7090afe14c31bd259e2059a68f04023
change-id: 20260616-qcom-spmi-haptics-3cc97e7b232e

Best regards,
--  
Fenglin Wu <fenglin.wu@oss.qualcomm.com>