[PATCH v4 0/2] HID: add initial support for Goodix HID-over-SPI touchscreen

[Charles Wang]

This patch introduces a new driver to support the Goodix GT7986U
touch controller. This device is not compatible with Microsoft's
HID-over-SPI protocol and therefore needs to implement its own
flavor. The data reported is packaged according to the HID
protocol but uses SPI for communication to improve speed. This
enables the device to transmit not only coordinate data but also
corresponding raw data that can be accessed by user-space programs
through the hidraw interface. The raw data can be utilized for
functions like palm rejection, thereby improving the touch experience.

Key features:
- Device connection confirmation and initialization
- IRQ-based event reporting to the input subsystem
- Support for HIDRAW operations (GET_REPORT and SET_REPORT)

Signed-off-by: Charles Wang <charles.goodix@xxxxxxxxx>
---
Changes in v4:
- Allocate memory based on the report information.
- Added a new function goodix_get_event_report() to retrieve report data,
  reducing memory copy operations and avoiding the use of reg_rw_lock.
- Add low power control operations.
- Implemented power management operations.
- Introduced GOODIX_HID_STARTED to record the current device operating state.
- Add OF match table.

Changes in v3:
- Renamed the driver file to hid-goodix-spi.c.
- Mentioned in the commit message that this implementation is not compatible with
  Microsoft's HID-over-SPI protocol.
- Modified the driver to fetch the GOODIX_HID_REPORT_ADDR from device properties.
- Add a lock to prevent concurrent hid feature request operations.
- Optimized the SPI read/write functions by reducing the number of malloc calls.

Changes in v2:
- Fixed build warnings reported by kernel test robot

---
Charles Wang (2):
  HID: hid-goodix: Add Goodix HID-over-SPI driver
  dt-bindings: input: Goodix SPI HID Touchscreen

 .../bindings/input/goodix,gt7986u.yaml        |  65 ++
 drivers/hid/Kconfig                           |   6 +
 drivers/hid/Makefile                          |   1 +
 drivers/hid/hid-goodix-spi.c                  | 812 ++++++++++++++++++
 4 files changed, 884 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/goodix,gt7986u.yaml
 create mode 100644 drivers/hid/hid-goodix-spi.c

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2.43.0