linux-kernel - [PATCH v3 1/2] schemas: Add a schema for memory map

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Message-ID: <20230822203446.4111742-1-sjg@chromium.org>
Date:   Tue, 22 Aug 2023 14:34:42 -0600
From:   Simon Glass <sjg@...omium.org>
To:     devicetree@...r.kernel.org
Cc:     Rob Herring <robh@...nel.org>, Ard Biesheuvel <ardb@...nel.org>,
        Chiu Chasel <chasel.chiu@...el.com>,
        U-Boot Mailing List <u-boot@...ts.denx.de>,
        Gua Guo <gua.guo@...el.com>, linux-acpi@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>,
        Yunhui Cui <cuiyunhui@...edance.com>,
        ron minnich <rminnich@...il.com>,
        Tom Rini <trini@...sulko.com>,
        Lean Sheng Tan <sheng.tan@...ements.com>,
        Mark Rutland <mark.rutland@....com>,
        Simon Glass <sjg@...omium.org>
Subject: [PATCH v3 1/2] schemas: Add a schema for memory map

The Devicetree specification skips over handling of a logical view of
the memory map, pointing users to the UEFI specification.

It is common to split firmware into 'Platform Init', which does the
initial hardware setup and a "Payload" which selects the OS to be booted.
Thus an handover interface is required between these two pieces.

Where UEFI boot-time services are not available, but UEFI firmware is
present on either side of this interface, information about memory usage
and attributes must be presented to the "Payload" in some form.

This aims to provide an initial schema for this mapping.

Note that this is separate from the existing /memory and /reserved-memory
nodes, since it is mostly concerned with what the memory is used for. It
may cover only a small fraction of available memory.

For now, no attempt is made to create an exhaustive binding, so there are
some example types listed. This can be completed once this has passed
initial review.

This binding does not include a binding for the memory 'attribute'
property, defined by EFI_BOOT_SERVICES.GetMemoryMap(). It may be useful
to have that as well, but perhaps not as a bit mask.

Signed-off-by: Simon Glass <sjg@...omium.org>
---

Changes in v3:
- Reword commit message again
- cc a lot more people, from the FFI patch
- Split out the attributes into the /memory nodes

Changes in v2:
- Reword commit message

 dtschema/schemas/memory-map.yaml | 61 ++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 dtschema/schemas/memory-map.yaml

diff --git a/dtschema/schemas/memory-map.yaml b/dtschema/schemas/memory-map.yaml
new file mode 100644
index 0000000..4b06583
--- /dev/null
+++ b/dtschema/schemas/memory-map.yaml
@@ -0,0 +1,61 @@
+# SPDX-License-Identifier: BSD-2-Clause
+# Copyright 2023 Google LLC
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/memory-map.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: /memory-map nodes
+description: |
+  Common properties always required in /memory-map nodes. These nodes are
+  intended to resolve the nonchalant clause 3.4.1 ("/memory node and UEFI")
+  in the Devicetree Specification.
+
+maintainers:
+  - Simon Glass <sjg@...omium.org>
+
+properties:
+  $nodename:
+    const: 'memory-map'
+
+patternProperties:
+  "^([a-z][a-z0-9\\-]+@[0-9a-f]+)?$":
+    type: object
+    additionalProperties: false
+
+    properties:
+      reg:
+        minItems: 1
+        maxItems: 1024
+
+      usage:
+        $ref: /schemas/types.yaml#/definitions/string
+        description: |
+          Describes the usage of the memory region, e.g.:
+
+            "acpi-reclaim", "acpi-nvs", "bootcode", "bootdata", "bootdata",
+            "runtime-code", "runtime-data".
+
+            See enum EFI_MEMORY_TYPE in "Unified Extensible Firmware Interface
+            (UEFI) Specification" for all the types. For now there are not
+            listed here.
+
+    required:
+      - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    memory-map {
+        acpi@...00 {
+            reg = <0xf0000 0x4000>;
+            usage = "acpi-reclaim";
+        };
+
+        runtime@...00000 {
+            reg = <0x12300000 0x28000>;
+            usage = "runtime-code";
+        };
+    };
+...
-- 
2.42.0.rc1.204.g551eb34607-goog