Support the remote devices on the remote processor via the RPMSG bus on
i.MX platform.

Changes in v6:
 - make the driver more generic with the actions below:
     rename the driver file to gpio-rpmsg.c
     remove the imx related info in the function and variable names
     rename the imx_rpmsg.h to rpdev_info.h
     create a gpio-rpmsg.yaml and refer it in imx_rproc.yaml
 - update the gpio-rpmsg.rst according to the feedback from Andrew and
   move the source file to driver-api/gpio
 - fix the bug reported by Zhongqiu Han
 - remove the I2C related info

Changes in v5:
 - move the gpio-rpmsg.rst from admin-guide to staging directory after
   discussion with Randy Dunlap.
 - add include files with some code improvements per Bartosz's comments.

Changes in v4:
 - add a documentation to describe the transport protocol per Andrew's
   comments.
 - add a new handler to get the gpio direction.

Changes in v3:
 - fix various format issue and return value check per Peng 's review
   comments.
 - add the logic to also populate the subnodes which are not in the
   device map per Arnaud's request. (in imx_rproc.c)
 - update the yaml per Frank's review comments.

Changes in v2:
 - re-implemented the gpio driver per Linus Walleij's feedback by using
   GPIOLIB_IRQCHIP helper library.
 - fix various format issue per Mathieu/Peng 's review comments.
 - update the yaml doc per Rob's feedback

Shenwei Wang (5):
  dt-bindings: remoteproc: imx_rproc: Add "rpmsg" subnode support
  remoteproc: imx_rproc: Populate devices under "rpmsg" subnode
  docs: driver-api: gpio: generic gpio driver over rpmsg bus
  gpio: rpmsg: add generic rpmsg GPIO driver
  arm64: dts: imx8ulp: Add rpmsg node under imx_rproc

 .../devicetree/bindings/gpio/gpio-rpmsg.yaml  |  49 ++
 .../bindings/remoteproc/fsl,imx-rproc.yaml    |  54 ++
 Documentation/driver-api/gpio/gpio-rpmsg.rst  | 232 +++++++++
 Documentation/driver-api/gpio/index.rst       |   1 +
 arch/arm64/boot/dts/freescale/imx8ulp.dtsi    |  27 +
 drivers/gpio/Kconfig                          |  16 +
 drivers/gpio/Makefile                         |   1 +
 drivers/gpio/gpio-rpmsg.c                     | 490 ++++++++++++++++++
 drivers/remoteproc/imx_rproc.c                | 143 +++++
 include/linux/rpmsg/rpdev_info.h              |  33 ++
 10 files changed, 1046 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/gpio-rpmsg.yaml
 create mode 100644 Documentation/driver-api/gpio/gpio-rpmsg.rst
 create mode 100644 drivers/gpio/gpio-rpmsg.c
 create mode 100644 include/linux/rpmsg/rpdev_info.h

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2.43.0