Add support for WD MyCloud EX2 Ultra (+ versatile UART-based restart/poweroff drivers)

This patchset consists of the DTS, which describes the WD MyCloud EX2 Ultra device, 'poweroff' and 'resert' drivers for power-managing MCUs connected to a board via UART (these drivers are more versatile than qnap-poweroff and could be used as a substitude), and DT bindings for these drivers.

The difference between uart-poweroff and qnap-poweroff is small, but important:
uart-poweroff is able to send to an MCU a command of arbitrary length, and the command itself is defined in a DTS file for a specific device/board, thus making this driver applicable to wider range of devices.

Evgeny Kolesnikov (5):
power: reset: Add UART-based MCU poweroff DT bindings
power: reset: Add UART-based MCU restart DT bindings power/reset: Add a power off driver for UART-based PM MCUs power/reset: Add a restart driver for UART-based PM MCUs
ARM: dts: armada385-wd-mcex2u: Add DTS file for WD My Cloud EX2 Ultra

 .../bindings/power/reset/uart-poweroff.txt    |  38 +++
 .../bindings/power/reset/uart-restart.txt     |  39 +++
 arch/arm/boot/dts/armada-385-wd-mcex2u.dts    | 313 ++++++++++++++++++
 drivers/power/reset/Kconfig                   |  14 +
 drivers/power/reset/Makefile                  |   2 +
 drivers/power/reset/uart-poweroff.c           | 155 +++++++++
 drivers/power/reset/uart-restart.c            | 204 ++++++++++++
 7 files changed, 765 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power/reset/uart-poweroff.txt
 create mode 100644 Documentation/devicetree/bindings/power/reset/uart-restart.txt
 create mode 100644 arch/arm/boot/dts/armada-385-wd-mcex2u.dts
 create mode 100644 drivers/power/reset/uart-poweroff.c
 create mode 100644 drivers/power/reset/uart-restart.c

2.21.0