These ICs support SPI and I2C interfaces, up to 10 finger touch, stylus and gesture events.
This driver is derived from the Goodix gtx8_driver_linux available at [1] and only supports the GT9886 and GT9896 ICs present in the Xiaomi Mi 9T and Xiaomi Redmi Note 10 Pro smartphones. The current implementation only supports Normandy and Yellowstone type ICs, aka only GT9886 and GT9896. It is also limited to I2C only, since I don't have a device with GTX8 over SPI at hand. Adding support for SPI should be fairly easy in the future, since the code uses a regmap. Support for advanced features like: - Firmware updates - Stylus events - Gesture events - Nanjing IC support is not included in current version. The current support requires a previously flashed firmware to be present. As I did not have access to datasheets for these ICs, I extracted the addresses from a couple of config files using a small tool [2]. The addresses are identical for the same IC families in all configs I observed, however not all of them make sense and I stubbed out firmware request support due to this. I've taken a lot of inspiration from the goodix_berlin driver, but the Berlin and GTX8 series of touchscreen ICs differ quite a bit. The driver architecture is the same overall, i.e. the power-up sequence and general concepts are the mostly same, but it is very clear that they are different generations when looking at it in more detail. Some of the differences: - There is no equivalent to the bootoption reg that I can find in the public GTX8 drivers - Firmware version struct layout is different yet again - GTX8 does not expose IC information at runtime as far as I can tell - The checksum method differs yet again - The vendor driver reads only 1 touch upfront rather than 2 - Register addresses are 16-bit on GTX8 and 32-bit on Berlin - Firmware requests don't appear to really exist on GTX8 >From what I can tell, the evolution seems to be: Normandy -> Yellowstone -> Berlin since Normandy and Yellowstone are already quite different (especially with the way checksums work) and Yellowstone has a couple of things (checksum, fw_version) that appear similar to Berlin series ICs. I've tried to make the Berlin driver work for GTX8 ICs before, but they're so different (and I lack documentation for registers to perhaps make some parts work on GTX8) that I'd rather support these ICs in a new and tiny driver. I hope that makes sense. I took heavy inspiration from the Berlin driver, but the only parts that are really common between them are very trivial things like e.g. the input dev config or power on, which I don't think are worth putting in a separate header. [1] https://github.com/goodix/gtx8_driver_linux [2] https://github.com/sm7150-mainline/goodix-cfg-bin Signed-off-by: Aelin Reidel <[email protected]> --- Changes in v1 (post-RFC): - Drop RFC prefix, the series has been tested enough and works well as-is - Update my name and email address - Add some reasoning for a new driver to the cover letter - Add Rob's R-b on the dt-bindings patch - Add Piyush's T-b to the driver patch - Link to RFC: https://lore.kernel.org/r/[email protected] --- Aelin Reidel (3): dt-bindings: input: document Goodix GTX8 Touchscreen ICs Input: add support for Goodix GTX8 Touchscreen ICs MAINTAINERS: add an entry for Goodix GTX8 Touchscreen driver .../bindings/input/touchscreen/goodix,gt9886.yaml | 71 +++ MAINTAINERS | 7 + drivers/input/touchscreen/Kconfig | 15 + drivers/input/touchscreen/Makefile | 1 + drivers/input/touchscreen/goodix_gtx8.c | 562 +++++++++++++++++++++ drivers/input/touchscreen/goodix_gtx8.h | 137 +++++ 6 files changed, 793 insertions(+) --- base-commit: fe9e3edb6a215515d1148d32a5c445c5bdd7916f change-id: 20250918-gtx8-59a50ccd78a5 Best regards, -- Aelin Reidel <[email protected]>
