This basically abandons my earlier attempts and goes back to Takahiro
Akashi's driver.  Here is the link to Takahiro's patchset:

https://lore.kernel.org/all/20231005025843.508689-1-takahiro.akashi@linaro.org/ (local)

v5: Addresses Andy's cleanups to the driver.
    Adrresses Krzysztof's comments about the dt spec file.
    And almost all the subsystem prefixes were wrong.

v4: Addressed Andy's comments about kernel-doc
    Addressed Rob's comments on the spec file

v3: Forward ported Takahiro's patches and added some fixes ups to make
    it work on current kernels.

AKASHI Takahiro (3):
  pinctrl: introduce pinctrl_gpio_get_config()
  gpio: dt-bindings: Add bindings for pinctrl based generic gpio driver
  gpio: gpio-by-pinctrl: add pinctrl based generic GPIO driver

Dan Carpenter (4):
  pinctrl: scmi: Add SCMI_PIN_INPUT_VALUE
  pinctrl: scmi: Delete PIN_CONFIG_OUTPUT_IMPEDANCE_OHMS support
  pinctrl: scmi: ignore PIN_CONFIG_PERSIST_STATE
  firmware: arm_scmi: Allow PINCTRL_REQUEST to return EOPNOTSUPP

 .../bindings/gpio/pin-control-gpio.yaml       |  59 ++++++++++
 drivers/firmware/arm_scmi/pinctrl.c           |   2 +
 drivers/gpio/Kconfig                          |  13 +++
 drivers/gpio/Makefile                         |   1 +
 drivers/gpio/gpio-by-pinctrl.c                | 101 ++++++++++++++++++
 drivers/pinctrl/core.c                        |  31 ++++++
 drivers/pinctrl/pinctrl-scmi.c                |  46 +++++---
 include/linux/pinctrl/consumer.h              |   9 ++
 8 files changed, 249 insertions(+), 13 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
 create mode 100644 drivers/gpio/gpio-by-pinctrl.c

-- 
2.51.0