dt-bindings: power: reset: gpio-restart: Convert to json-schema

Drive a GPIO line that can be used to restart the system from a restart

handler.

This binding supports level and edge triggered reset.  At driver load

time, the driver will request the given gpio line and install a restart

handler. If the optional properties 'open-source' is not found, the GPIO line

will be driven in the inactive state.  Otherwise its not driven until

the restart is initiated.

When the system is restarted, the restart handler will be invoked in

priority order.  The gpio is configured as an output, and driven active,

triggering a level triggered reset condition. This will also cause an

inactive->active edge condition, triggering positive edge triggered

reset. After a delay specified by active-delay, the GPIO is set to

inactive, thus causing an active->inactive edge, triggering negative edge

triggered reset. After a delay specified by inactive-delay, the GPIO

is driven active again.  After a delay specified by wait-delay, the

restart handler completes allowing other restart handlers to be attempted.

Required properties:

- compatible : should be "gpio-restart".

- gpios : The GPIO to set high/low, see "gpios property" in

  Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be

  low to reset the board set it to "Active Low", otherwise set

  gpio to "Active High".

Optional properties:

- open-source : Treat the GPIO as being open source and defer driving

  it to when the restart is initiated.  If this optional property is not

  specified, the GPIO is initialized as an output in its inactive state.

- priority : A priority ranging from 0 to 255 (default 128) according to

  the following guidelines:

	0:	Restart handler of last resort, with limited restart

		capabilities

	128:	Default restart handler; use if no other restart handler is

		expected to be available, and/or if restart functionality is

		sufficient to restart the entire system

	255:	Highest priority restart handler, will preempt all other

		restart handlers

- active-delay: Delay (default 100) to wait after driving gpio active [ms]

- inactive-delay: Delay (default 100) to wait after driving gpio inactive [ms]

- wait-delay: Delay (default 3000) to wait after completing restart

  sequence [ms]

Examples:

gpio-restart {

	compatible = "gpio-restart";

	gpios = <&gpio 4 0>;

	priority = <128>;

	active-delay = <100>;

	inactive-delay = <100>;

	wait-delay = <3000>;

};

# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)

%YAML 1.2

---

$id: http://devicetree.org/schemas/power/reset/gpio-restart.yaml#

$schema: http://devicetree.org/meta-schemas/core.yaml#

title: GPIO controlled reset

maintainers:

  - Sebastian Reichel <sre@kernel.org>

description: >

  Drive a GPIO line that can be used to restart the system from a restart handler.

  This binding supports level and edge triggered reset.  At driver load time, the driver will

  request the given gpio line and install a restart handler. If the optional properties

  'open-source' is not found, the GPIO line will be driven in the inactive state.  Otherwise its

  not driven until the restart is initiated.

  When the system is restarted, the restart handler will be invoked in priority order.  The GPIO

  is configured as an output, and driven active, triggering a level triggered reset condition.

  This will also cause an inactive->active edge condition, triggering positive edge triggered

  reset. After a delay specified by active-delay, the GPIO is set to inactive, thus causing an

  active->inactive edge, triggering negative edge triggered reset. After a delay specified by

  inactive-delay, the GPIO is driven active again.  After a delay specified by wait-delay, the

  restart handler completes allowing other restart handlers to be attempted.

properties:

  compatible:

    const: gpio-restart

  gpios:

    description: The GPIO to set high/low, see "gpios property" in

      Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be low to reset the board

      set it to "Active Low", otherwise set GPIO to "Active High".

  open-source:

    $ref: /schemas/types.yaml#/definitions/flag

    description: Treat the GPIO as being open source and defer driving it to when the restart is

      initiated.  If this optional property is not specified, the GPIO is initialized as an output

      in its inactive state.

  priority:

    $ref: /schemas/types.yaml#/definitions/uint32

    description: |

      A priority ranging from 0 to 255 (default 128) according to the following guidelines:

        0:   Restart handler of last resort, with limited restart capabilities.

        128: Default restart handler; use if no other restart handler is expected to be available,

             and/or if restart functionality is sufficient to restart the entire system.

        255: Highest priority restart handler, will preempt all other restart handlers.

    minimum: 0

    maximum: 255

    default: 128

  active-delay:

    $ref: /schemas/types.yaml#/definitions/uint32

    description: Delay (default 100) to wait after driving gpio active [ms]

    default: 100

  inactive-delay:

    $ref: /schemas/types.yaml#/definitions/uint32

    description: Delay (default 100) to wait after driving gpio inactive [ms]

    default: 100

  wait-delay:

    $ref: /schemas/types.yaml#/definitions/uint32

    description: Delay (default 3000) to wait after completing restart sequence [ms]

    default: 100

additionalProperties: false

required:

  - compatible

  - gpios

examples:

  - |

    gpio-restart {

      compatible = "gpio-restart";

      gpios = <&gpio 4 0>;

      priority = <128>;

      active-delay = <100>;

      inactive-delay = <100>;

      wait-delay = <3000>;

    };