97 lines
2.8 KiB
ReStructuredText
97 lines
2.8 KiB
ReStructuredText
|
.. SPDX-License-Identifier: GPL-2.0
|
||
|
|
.. include:: <isonum.txt>
|
||
|
|
|
||
|
|
===================================
|
||
|
|
Referencing hierarchical data nodes
|
||
|
|
===================================
|
||
|
|
|
||
|
|
:Copyright: |copy| 2018, 2021 Intel Corporation
|
||
|
|
:Author: Sakari Ailus <sakari.ailus@linux.intel.com>
|
||
|
|
|
||
|
|
ACPI in general allows referring to device objects in the tree only.
|
||
|
|
Hierarchical data extension nodes may not be referred to directly, hence this
|
||
|
|
document defines a scheme to implement such references.
|
||
|
|
|
||
|
|
A reference consist of the device object name followed by one or more
|
||
|
|
hierarchical data extension [dsd-guide] keys. Specifically, the hierarchical
|
||
|
|
data extension node which is referred to by the key shall lie directly under
|
||
|
|
the parent object i.e. either the device object or another hierarchical data
|
||
|
|
extension node.
|
||
|
|
|
||
|
|
The keys in the hierarchical data nodes shall consist of the name of the node,
|
||
|
|
"@" character and the number of the node in hexadecimal notation (without pre-
|
||
|
|
or postfixes). The same ACPI object shall include the _DSD property extension
|
||
|
|
with a property "reg" that shall have the same numerical value as the number of
|
||
|
|
the node.
|
||
|
|
|
||
|
|
In case a hierarchical data extensions node has no numerical value, then the
|
||
|
|
"reg" property shall be omitted from the ACPI object's _DSD properties and the
|
||
|
|
"@" character and the number shall be omitted from the hierarchical data
|
||
|
|
extension key.
|
||
|
|
|
||
|
|
|
||
|
|
Example
|
||
|
|
=======
|
||
|
|
|
||
|
|
In the ASL snippet below, the "reference" _DSD property contains a
|
||
|
|
device object reference to DEV0 and under that device object, a
|
||
|
|
hierarchical data extension key "node@1" referring to the NOD1 object
|
||
|
|
and lastly, a hierarchical data extension key "anothernode" referring to
|
||
|
|
the ANOD object which is also the final target node of the reference.
|
||
|
|
::
|
||
|
|
|
||
|
|
Device (DEV0)
|
||
|
|
{
|
||
|
|
Name (_DSD, Package () {
|
||
|
|
ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
|
||
|
|
Package () {
|
||
|
|
Package () { "node@0", "NOD0" },
|
||
|
|
Package () { "node@1", "NOD1" },
|
||
|
|
}
|
||
|
|
})
|
||
|
|
Name (NOD0, Package() {
|
||
|
|
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
|
||
|
|
Package () {
|
||
|
|
Package () { "reg", 0 },
|
||
|
|
Package () { "random-property", 3 },
|
||
|
|
}
|
||
|
|
})
|
||
|
|
Name (NOD1, Package() {
|
||
|
|
ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
|
||
|
|
Package () {
|
||
|
|
Package () { "reg", 1 },
|
||
|
|
Package () { "anothernode", "ANOD" },
|
||
|
|
}
|
||
|
|
})
|
||
|
|
Name (ANOD, Package() {
|
||
|
|
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
|
||
|
|
Package () {
|
||
|
|
Package () { "random-property", 0 },
|
||
|
|
}
|
||
|
|
})
|
||
|
|
}
|
||
|
|
|
||
|
|
Device (DEV1)
|
||
|
|
{
|
||
|
|
Name (_DSD, Package () {
|
||
|
|
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
|
||
|
|
Package () {
|
||
|
|
Package () {
|
||
|
|
"reference", Package () {
|
||
|
|
^DEV0, "node@1", "anothernode"
|
||
|
|
}
|
||
|
|
},
|
||
|
|
}
|
||
|
|
})
|
||
|
|
}
|
||
|
|
|
||
|
|
Please also see a graph example in
|
||
|
|
Documentation/firmware-guide/acpi/dsd/graph.rst.
|
||
|
|
|
||
|
|
References
|
||
|
|
==========
|
||
|
|
|
||
|
|
[dsd-guide] DSD Guide.
|
||
|
|
https://github.com/UEFI/DSD-Guide/blob/main/dsd-guide.adoc, referenced
|
||
|
|
2021-11-30.
|