0001 # SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
0002 %YAML 1.2
0003 ---
0004 $id: http://devicetree.org/schemas/reserved-memory/reserved-memory.yaml#
0005 $schema: http://devicetree.org/meta-schemas/core.yaml#
0006
0007 title: /reserved-memory Child Node Common Device Tree Bindings
0008
0009 maintainers:
0010 - devicetree-spec@vger.kernel.org
0011
0012 description: >
0013 Reserved memory is specified as a node under the /reserved-memory node. The
0014 operating system shall exclude reserved memory from normal usage one can
0015 create child nodes describing particular reserved (excluded from normal use)
0016 memory regions. Such memory regions are usually designed for the special
0017 usage by various device drivers.
0018
0019 Each child of the reserved-memory node specifies one or more regions
0020 of reserved memory. Each child node may either use a 'reg' property to
0021 specify a specific range of reserved memory, or a 'size' property with
0022 optional constraints to request a dynamically allocated block of
0023 memory.
0024
0025 Following the generic-names recommended practice, node names should
0026 reflect the purpose of the node (ie. "framebuffer" or "dma-pool").
0027 Unit address (@<address>) should be appended to the name if the node
0028 is a static allocation.
0029
0030 properties:
0031 reg: true
0032
0033 size:
0034 $ref: /schemas/types.yaml#/definitions/uint32-array
0035 minItems: 1
0036 maxItems: 2
0037 description: >
0038 Length based on parent's \#size-cells. Size in bytes of memory to
0039 reserve.
0040
0041 alignment:
0042 $ref: /schemas/types.yaml#/definitions/uint32-array
0043 minItems: 1
0044 maxItems: 2
0045 description: >
0046 Length based on parent's \#size-cells. Address boundary for
0047 alignment of allocation.
0048
0049 alloc-ranges:
0050 $ref: /schemas/types.yaml#/definitions/uint32-array
0051 description: >
0052 Address and Length pairs. Specifies regions of memory that are
0053 acceptable to allocate from.
0054
0055 no-map:
0056 type: boolean
0057 description: >
0058 Indicates the operating system must not create a virtual mapping
0059 of the region as part of its standard mapping of system memory,
0060 nor permit speculative access to it under any circumstances other
0061 than under the control of the device driver using the region.
0062
0063 reusable:
0064 type: boolean
0065 description: >
0066 The operating system can use the memory in this region with the
0067 limitation that the device driver(s) owning the region need to be
0068 able to reclaim it back. Typically that means that the operating
0069 system can use that region to store volatile or cached data that
0070 can be otherwise regenerated or migrated elsewhere.
0071
0072 allOf:
0073 - if:
0074 required:
0075 - no-map
0076
0077 then:
0078 not:
0079 required:
0080 - reusable
0081
0082 - if:
0083 required:
0084 - reusable
0085
0086 then:
0087 not:
0088 required:
0089 - no-map
0090
0091 oneOf:
0092 - required:
0093 - reg
0094
0095 - required:
0096 - size
0097
0098 additionalProperties: true
0099
0100 ...
