Documentation/devicetree/bindings/watchdog/aspeed,ast2400-wdt.yaml

# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/watchdog/aspeed,ast2400-wdt.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Aspeed watchdog timer controllers

maintainers:
  - Andrew Jeffery <andrew@codeconstruct.com.au>

properties:
  compatible:
    enum:
      - aspeed,ast2400-wdt
      - aspeed,ast2500-wdt
      - aspeed,ast2600-wdt

  reg:
    maxItems: 1

  clocks:
    maxItems: 1
    description: >
      The clock used to drive the watchdog counter. From the AST2500 no source
      other than the 1MHz clock can be selected, so the clocks property is
      optional.

  aspeed,reset-type:
    $ref: /schemas/types.yaml#/definitions/string
    enum:
      - cpu
      - soc
      - system
      - none
    default: system
    description: >
      The watchdog can be programmed to generate one of three different types of
      reset when a timeout occcurs.

      Specifying 'cpu' will only reset the processor on a timeout event.

      Specifying 'soc' will reset a configurable subset of the SoC's controllers
      on a timeout event. Controllers critical to the SoC's operation may remain
      untouched. The set of SoC controllers to reset may be specified via the
      aspeed,reset-mask property if the node has the aspeed,ast2500-wdt or
      aspeed,ast2600-wdt compatible.

      Specifying 'system' will reset all controllers on a timeout event, as if
      EXTRST had been asserted.

      Specifying 'none' will cause the timeout event to have no reset effect.
      Another watchdog engine on the chip must be used for chip reset operations.

  aspeed,alt-boot:
    $ref: /schemas/types.yaml#/definitions/flag
    description: >
      Direct the watchdog to configure the SoC to boot from the alternative boot
      region if a timeout occurs.

  aspeed,external-signal:
    $ref: /schemas/types.yaml#/definitions/flag
    description: >
      Assert the timeout event on an external signal pin associated with the
      watchdog controller instance. The pin must be muxed appropriately.

  aspeed,ext-pulse-duration:
    $ref: /schemas/types.yaml#/definitions/uint32
    description: >
      The duration, in microseconds, of the pulse emitted on the external signal
      pin.

  aspeed,ext-push-pull:
    $ref: /schemas/types.yaml#/definitions/flag
    description: >
      If aspeed,external-signal is specified in the node, set the external
      signal pin's drive type to push-pull. If aspeed,ext-push-pull is not
      specified then the pin is configured as open-drain.

  aspeed,ext-active-high:
    $ref: /schemas/types.yaml#/definitions/flag
    description: >
      If both aspeed,external-signal and aspeed,ext-push-pull are specified in
      the node, set the pulse polarity to active-high. If aspeed,ext-active-high
      is not specified then the pin is configured as active-low.

  aspeed,reset-mask:
    $ref: /schemas/types.yaml#/definitions/uint32-array
    minItems: 1
    maxItems: 2
    description: >
      A bitmask indicating which peripherals will be reset if the watchdog
      timer expires. On AST2500 SoCs this should be a single word defined using
      the AST2500_WDT_RESET_* macros; on AST2600 SoCs this should be a two-word
      array with the first word defined using the AST2600_WDT_RESET1_* macros,
      and the second word defined using the AST2600_WDT_RESET2_* macros.

required:
  - compatible
  - reg

allOf:
  - if:
      anyOf:
        - required:
            - aspeed,ext-push-pull
        - required:
            - aspeed,ext-active-high
        - required:
            - aspeed,reset-mask
    then:
      properties:
        compatible:
          enum:
            - aspeed,ast2500-wdt
            - aspeed,ast2600-wdt
  - if:
      required:
        - aspeed,ext-active-high
    then:
      required:
        - aspeed,ext-push-pull

additionalProperties: false

examples:
  - |
    watchdog@1e785000 {
        compatible = "aspeed,ast2400-wdt";
        reg = <0x1e785000 0x1c>;
        aspeed,reset-type = "system";
        aspeed,external-signal;
    };
  - |
    #include <dt-bindings/watchdog/aspeed-wdt.h>
    watchdog@1e785040 {
        compatible = "aspeed,ast2600-wdt";
        reg = <0x1e785040 0x40>;
        aspeed,reset-type = "soc";
        aspeed,reset-mask = <AST2600_WDT_RESET1_DEFAULT
                            (AST2600_WDT_RESET2_DEFAULT & ~AST2600_WDT_RESET2_LPC)>;
    };