linux/Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
Rafał Miłecki 5db1c2dbc0 dt-bindings: nvmem: add U-Boot environment variables binding
U-Boot uses environment variables for storing device setup data. It
usually needs to be accessed by a bootloader, kernel and often
user-space.

This binding allows describing environment data located in a raw flash
partition. It's treated as NVMEM device and can be reused later for
other storage devices.

Using DT should be cleaner than hardcoding & duplicating such info in
multiple places. Bootloader & kernel can share DTS and user-space can
try reading it too or just have correct data exposed by a kernel.

A custom "compatible" string allows system to automatically load
relevant NVMEM driver but phandle can be also used for reading raw
location.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220228131250.16943-1-zajec5@gmail.com
2022-03-23 18:10:00 -05:00

63 lines
1.6 KiB
YAML

# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
%YAML 1.2
---
$id: http://devicetree.org/schemas/nvmem/u-boot,env.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: U-Boot environment variables
description: |
U-Boot uses environment variables to store device parameters and
configuration. They may be used for booting process, setup or keeping end user
info.
Data is stored using U-Boot specific formats (variant specific header and NUL
separated key-value pairs).
Environment data can be stored on various storage entities, e.g.:
1. Raw flash partition
2. UBI volume
This binding allows marking storage device (as containing env data) and
specifying used format.
Right now only flash partition case is covered but it may be extended to e.g.
UBI volumes in the future.
maintainers:
- Rafał Miłecki <rafal@milecki.pl>
properties:
compatible:
oneOf:
- description: A standalone env data block
const: u-boot,env
- description: Two redundant blocks with active one flagged
const: u-boot,env-redundant-bool
- description: Two redundant blocks with active having higher counter
const: u-boot,env-redundant-count
reg:
maxItems: 1
additionalProperties: false
examples:
- |
partitions {
compatible = "fixed-partitions";
#address-cells = <1>;
#size-cells = <1>;
partition@0 {
reg = <0x0 0x40000>;
label = "u-boot";
read-only;
};
env: partition@40000 {
compatible = "u-boot,env";
reg = <0x40000 0x10000>;
};
};