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# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/reserved-memory/reserved-memory.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: /reserved-memory Child Node Common Device Tree Bindings
maintainers:
- devicetree-spec@vger.kernel.org
description: >
Reserved memory is specified as a node under the /reserved-memory node. The
operating system shall exclude reserved memory from normal usage one can
create child nodes describing particular reserved (excluded from normal use)
memory regions. Such memory regions are usually designed for the special
usage by various device drivers.
Each child of the reserved-memory node specifies one or more regions
of reserved memory. Each child node may either use a 'reg' property to
specify a specific range of reserved memory, or a 'size' property with
optional constraints to request a dynamically allocated block of
memory.
Following the generic-names recommended practice, node names should
reflect the purpose of the node (ie. "framebuffer" or "dma-pool").
Unit address (@<address>) should be appended to the name if the node
is a static allocation.
properties:
reg: true
size:
$ref: /schemas/types.yaml#/definitions/uint32-array
minItems: 1
maxItems: 2
description: >
Length based on parent's \#size-cells. Size in bytes of memory to
reserve.
alignment:
$ref: /schemas/types.yaml#/definitions/uint32-array
minItems: 1
maxItems: 2
description: >
Length based on parent's \#size-cells. Address boundary for
alignment of allocation.
alloc-ranges:
$ref: /schemas/types.yaml#/definitions/uint32-array
description: >
Address and Length pairs. Specifies regions of memory that are
acceptable to allocate from.
no-map:
type: boolean
description: >
Indicates the operating system must not create a virtual mapping
of the region as part of its standard mapping of system memory,
nor permit speculative access to it under any circumstances other
than under the control of the device driver using the region.
reusable:
type: boolean
description: >
The operating system can use the memory in this region with the
limitation that the device driver(s) owning the region need to be
able to reclaim it back. Typically that means that the operating
system can use that region to store volatile or cached data that
can be otherwise regenerated or migrated elsewhere.
allOf:
- if:
required:
- no-map
then:
not:
required:
- reusable
- if:
required:
- reusable
then:
not:
required:
- no-map
oneOf:
- required:
- reg
- required:
- size
additionalProperties: true
...
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