dts/bindings/watchdog/gd,gd32-fwdgt.yaml

# Copyright (c) 2021, TOKITA Hiroshi
# SPDX-License-Identifier: Apache-2.0

description: GD32 free watchdog timer

compatible: "gd,gd32-fwdgt"

include: base.yaml

properties:
  reg:
    required: true

  initial-timeout-ms:
    type: int
    default: 250
    description: |
      Set timeout value in milliseconds.
      The following equation gives the maximum timeout value

        timeout = (reload + 1) / (peripheral_freqency / prescaler).

      where the maximum prescaler = 256 and the maximum reload = 4096.
      The peripheral_frequency uses GD32_LOW_SPEED_IRC_FREQUENCY
      that defined in modules/hal_gigadevice/Kconfig.
      Validate the value is within a capable range at the compile time.

      The default value defined is close to the register reset value
      from values that don't cause calculation errors in both cases of
      the low-speed internal RC oscillator frequency is 32kHz or 40kHz.

      0.25 [timeout in sec] = (1999 [reload] + 1) / (32000 [freq] / 4 [prescaler])
      0.25 [timeout in sec] = (2499 [reload] + 1) / (40000 [freq] / 4 [prescaler])