U-Boot

# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
# Copyright 2021 Google LLC

%YAML 1.2
---
$id: http://devicetree.org/schemas/options/u-boot.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: U-Boot configuration node

maintainers:
  - Simon Glass <sjg@chromium.org>

description: |
  The u-boot,config node provides basic configuration information to U-Boot,
  for use during its execution. It can be used to control U-Boot's behaviour
  in various ways.

properties:
  $nodename:
    const: u-boot

  compatible:
    const: u-boot,config

  bootcmd:
    $ref: /schemas/types.yaml#/definitions/string
    description: |
      Allows overwriting of the boot command used by U-Boot on startup. If
      present, U-Boot uses this command instead. Note that this feature can
      work even if loading the environment is disabled, e.g. for security
      reasons. See also bootsecure.

  bootdelay-sec:
    description: |
      Allows selecting of the U-Boot bootdelay, to control whether U-Boot
      waits on boot or for how long. This allows this option to be configured
      by the build system or by a previous-stage binary. For example, if the
      images is being packed for testing or a user holds down a button, it may
      allow a delay, but disable it for production.

      If this property is not present, a default value is used instead.

      Note that this uses the 'sec' property unit, even though it allows a
      negative value.

      Values:

      -1: no bootdelay and the user cannot interrupt boot
      0: no bootdelay but use user can still interrupt boot by holding down a
        key, if enabled
      >= 1: delay for this many seconds


  bootsecure:
    $ref: /schemas/types.yaml#/definitions/uint32
    default: 0
    maximum: 2
    description: |
      Controls the execution of the boot command in U-Boot, e.g. selecting
      between using a special function to run commands, or the normal CLI. This
      can be used in production images, to restrict the amount of parsing done
      or the options available, to cut back on the available surface for
      security attacks.

      Values:

      0: normal boot using CLI (default if not present)
      1: use secure boot mechanism instead to parse and run commands
        other values are reserved for future use
      2: use simplified command line (e.g. avoid hush)
      3... reserved

  bootscr-address:
    $ref: /schemas/types.yaml#/definitions/uint64
    default: 0x0
    description:
      Holds the full address of the boot script file. It helps in making
      automated flow easier by fetching the 64bit address directly from DT.
      Value should be automatically copied to the U-Boot 'scriptaddr' variable.
      When it is defined, bootscr-ram-offset property should be ignored.
      Actually only one of them should be present in the DT.

  bootscr-ram-offset:
    $ref: /schemas/types.yaml#/definitions/uint64
    default: 0x0
    description:
      Holds the boot script file offset from the start of the ram base address.
      Platforms with run-time RAM-detection algorithms should use this property
      because it is not clear exactly where the script address should be placed.
      Using it will provide the option to specify boot script offset from
      detected RAM start. The U-Boot 'scriptaddr' variable should be composed as
      detected RAM start plus value of bootscr-ram-offset property.
      It should be used only when bootscr-address is not defined.

  silent-console:
    $ref: /schemas/types.yaml#/definitions/uint32
    default: 0
    maximum: 2
    description: |
      This allows the console to be silenced by default on boot. This can allow
      easy disabling of console output on a production build, for example. When
      suppressed, the console is still active. This feature only suppresses the
      console output itself, on all output devices.

      Values:

      0: console output appears as normal (default)
      1: console output is suppressed but console recording still operates (if
        enabled)
      2: console output is suppressed and not recorded

required:
  - compatible

if:
  required:
    - bootscr-address
then:
  properties:
    bootscr-ram-offset: false

additionalProperties: false

examples:
  - |
    options {
      u-boot {
        compatible = "u-boot,config";
        bootcmd = "vboot go auto";
        bootdelay-sec = <(-1)>;
        bootsecure = <1>;
        bootscr-address = /bits/ 64 <0x1000>;
        silent-console = <1>;
      };
    };