[0/2] Add Realtek Otto WDT support

Message

Sander Vanheule Oct. 13, 2021, 1:28 p.m. UTC

This watchdog timer found on Realtek's Otto MIPS platforms, including the
RTL838x and RTL839x series of ethernet switch SoCs. It has a number of reset
modes (SoC, CPU, software), and can provide pretimeout interrupts.

The timer has two timeout phases. Both phases have a maximum duration of 32
prescaled clock ticks, which is ca. 43s with a clock of 200MHz:
- Phase 1: During this phase, the WDT can be pinged to reset the timeout.
- Phase 2: Starts after phase 1 has timed out, and only serves to give the
  system some time to clean up, or notify others that it's going to reset.
  During this phase, pinging the WDT has no effect, and a reset is unavoidable.

The driver has been tested on a Zyxel GS1900-8 (RTL8380, mainline kernel and
OpenWrt), a Zyxel GS1900-48 (RTL8393, mainline), and a Netgear GS110TPPv1
(RTL8381, mainline).

Sander Vanheule (2):
  dt-bindings: watchdog: Realtek Otto WDT binding
  watchdog: Add Realtek Otto watchdog timer

 .../bindings/watchdog/realtek,otto-wdt.yaml   |  89 ++++
 MAINTAINERS                                   |   7 +
 drivers/watchdog/Kconfig                      |  13 +
 drivers/watchdog/Makefile                     |   1 +
 drivers/watchdog/realtek_otto_wdt.c           | 411 ++++++++++++++++++
 5 files changed, 521 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
 create mode 100644 drivers/watchdog/realtek_otto_wdt.c