[PATCH 0/2] Input: add support for OnePlus/OPPO Pad pogo-pin keyboards

[wyibo6109@gmail.com]

From: Yibo Wang <wyibo6109@gmail.com>

This series adds support for the magnetic pogo-pin smart keyboards of
the OnePlus Pad 3 Pro / Pad 4 and the OPPO Pad 5 Pro.  The keyboard is
built around a Tinno MCU attached to a tablet UART.  Both sides share a
single data wire, so the host gates its transmission onto the bus with a
PMIC GPIO for the duration of a frame, and every host frame is echoed
back on RX.

The MCU speaks a framed "one wire bus" protocol over the half-duplex
921600 8N1 UART: 8x 0x55 preamble, 0xF1, src/dst addresses, command,
length, payload, CRC16-IBM (poly 0x8005, init 0xC596), 0xFE and 4x 0xAA.
The protocol was reverse engineered from the vendor kernel driver; this
is a clean-room serdev reimplementation that replaces the downstream
platform driver, which depends on a private msm_geni_serial callback and
a user-space held tty fd.

Patch 1 adds the DT binding for the "oneplus,pogo-keyboard" device,
describing the supply, TX-gate and wake GPIOs and the touchpad geometry,
with a MAINTAINERS entry.

Patch 2 adds the driver: keyboard matrix, touchpad, function and URL
keys, caps-lock LED, attach detection through the wake GPIO plus a
100 ms heartbeat timeout, and the keyboard backlight as a
"pogo-keyboard::kbd_backlight" LED class device so UPower and the
desktop keyboard-backlight controls drive it through the standard
interface (the level is cached while detached and restored on
re-attach).  A sysfs battery level is exported for the keyboards that
carry a battery.

Tested on the OnePlus Pad 4 (iceland) running Linux 7.2.0-sm8850
(v7.2-based iceland tree).

---

 .../bindings/input/oneplus,pogo-keyboard.yaml |   81 ++
 MAINTAINERS                                   |    7 +
 drivers/input/keyboard/Kconfig                |   11 +
 drivers/input/keyboard/Makefile               |    1 +
 drivers/input/keyboard/oneplus-pogo-kbd.c     | 1109 +++++++++++++++++
 5 files changed, 1209 insertions(+)

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2.53.0