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+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-clause
+# Copyright 2023 Google LLC
+#
+
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/firmware.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: /firmware Node
+
+maintainers:
+ - Simon Glass <sjg@chromium.org>
+
+description: |
+ The '/firmware' node does not represent a real device, but serves as a place
+ for recording information about the main firmware used on the device, such as
+ a map of its contents. This is used by the Operating System (OS), user space
+ programs and possibly other firmware components. Data in the '/firmware' node
+ does not itself represent the hardware.
+
+ Properties in this node should be common to (and used by) at least two
+ firmware projects, such as U-Boot and TF-A. Project-specific subnodes can be
+ used for properties which are specific to a single project.
+
+ Purpose of '/firmware' node
+ ---------------------------
+
+ Firmware has traditionally been fairly opaque to the OS, with the OS taking
+ no interest in its contents, version, layout or how it might be updated. This
+ is less than ideal, since firmware is an important part of the system and
+ visibility into its operation is every bit as important as visbility into the
+ OS and user-space programs within the system.
+
+ The traditional approach has been to let firmware deal with firmware, and the
+ OS deal with everything else. Updating firmware has been handled by firmware.
+ For example, the UEFI spec defines a way for the OS to post a 'capsule' which
+ is discovered next time the system boots, permitting firmware updates. But
+ firmware updates in firmware are highly problematic. They require a reboot
+ and a sometimes-lengthy wait with a strange-looking interface unfamiliar
+ to most users. It seems better to make the update as transparent as possible
+ to the user. As an example of that, ChromeOS has full knowledge of the
+ firmware version and layout, updates it in the background from user space and
+ instantly selects the new firmware when the user reboots or logs out.
+
+ A common objection to considering the system holistically is that some parts
+ of the system are inaccessible to the OS, such as a secure enclave. However
+ this does not preclude providing visibility into what is present in that
+ enclave. Firmware-version information is still useful. Firmware updates are
+ still needed and can still be initiated from user space.
+
+ Another objection is that firmware should provide an interface to the OS,
+ while keeping its structure private. This thinking is largely driven by
+ extrapolating from how firmware has been handled in the 'BIOS' days.
+ It should be considered a degenerate case rather than the norm. As complexity
+ increases, it creates an artificial boundary between two pieces of the whole.
+ Mechanisms then need to be invented to cross this unnecessary chasm. An
+ example of this is Intel's Dynamic Platform and Thermal Framework (DPTF),
+ which consists of user-space, OS and firmware components all working towards
+ a shared goal. We need a standard description of these cross-system pieces.
+
+ In order to 'teach the OS about firmware', we need a place to put this
+ information. That is the purpose of this node.
+
+ In an Open Source world the entire model of firmware needs to adjust to be
+ more open, more visible and managed just like any other part of the system.
+ The major goal is to standardise how firmware is presented to the OS and user
+ space, so that common utilities can be used to manage the entire system,
+ including the firmware. For example, fwupd can look in this node for
+ information on how to update the firmware, similar to how VBE works. [1]
+ It is likely that other purposes will come to light over time.
+
+ [1] https://github.com/fwupd/fwupd/tree/main/plugins/vbe
+
+properties:
+ $nodename:
+ const: firmware
+
+ "#address-cells": true
+ "#size-cells": true
+
+additionalProperties:
+ type: object
Add a motivation and purpose for this new proposed node. Signed-off-by: Simon Glass <sjg@chromium.org> --- (no changes since v1) dtschema/schemas/firmware.yaml | 83 ++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) create mode 100644 dtschema/schemas/firmware.yaml