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Generic device properties framework updates for v4.12-rc1
- Extend the ACPI _DSD properties code and the generic device
properties framework to support the concept of remote endponts
(Mika Westerberg, Sakari Ailus).
- Document the support for ports and endpoints in _DSD properties
and extend the generic device properties framework to make it
more suitable for the handling of ports and endpoints (Sakari
Ailus).
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Merge tag 'devprop-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull generic device properties framework updates from Rafael Wysocki:
"These add support for the ports and endpoints concepts, based on the
existing DT support for them, to the generic device properties
framework and update the ACPI _DSD properties code to recognize ports
and endpoints accordingly.
Specifics:
- Extend the ACPI _DSD properties code and the generic device
properties framework to support the concept of remote endponts
(Mika Westerberg, Sakari Ailus).
- Document the support for ports and endpoints in _DSD properties and
extend the generic device properties framework to make it more
suitable for the handling of ports and endpoints (Sakari Ailus)"
* tag 'devprop-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
device property: Read strings using string array reading functions
device property: fwnode_property_read_string_array() returns nr of strings
device property: Fix reading pset strings using array access functions
device property: fwnode_property_read_string_array() may return -EILSEQ
ACPI / DSD: Document references, ports and endpoints
device property: Add fwnode_get_next_parent()
device property: Add support for fwnode endpoints
device property: Make dev_fwnode() public
of: Add of_fwnode_handle() to convert device nodes to fwnode_handle
device property: Add fwnode_handle_get()
device property: Add support for remote endpoints
ACPI / property: Add support for remote endpoints
device property: Add fwnode_get_named_child_node()
ACPI / property: Add fwnode_get_next_child_node()
device property: Add fwnode_get_parent()
ACPI / property: Add possiblity to retrieve parent firmware node
This commit is contained in:
Linus Torvalds
commit
5fab10041b
8 changed files with 761 additions and 105 deletions
162
Documentation/acpi/dsd/graph.txt
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162
Documentation/acpi/dsd/graph.txt
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Graphs
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_DSD
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----
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_DSD (Device Specific Data) [7] is a predefined ACPI device
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configuration object that can be used to convey information on
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hardware features which are not specifically covered by the ACPI
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specification [1][6]. There are two _DSD extensions that are relevant
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for graphs: property [4] and hierarchical data extensions [5]. The
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property extension provides generic key-value pairs whereas the
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hierarchical data extension supports nodes with references to other
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nodes, forming a tree. The nodes in the tree may contain properties as
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defined by the property extension. The two extensions together provide
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a tree-like structure with zero or more properties (key-value pairs)
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in each node of the tree.
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The data structure may be accessed at runtime by using the device_*
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and fwnode_* functions defined in include/linux/fwnode.h .
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Fwnode represents a generic firmware node object. It is independent on
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the firmware type. In ACPI, fwnodes are _DSD hierarchical data
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extensions objects. A device's _DSD object is represented by an
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fwnode.
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The data structure may be referenced to elsewhere in the ACPI tables
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by using a hard reference to the device itself and an index to the
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hierarchical data extension array on each depth.
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Ports and endpoints
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-------------------
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The port and endpoint concepts are very similar to those in Devicetree
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[3]. A port represents an interface in a device, and an endpoint
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represents a connection to that interface.
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All port nodes are located under the device's "_DSD" node in the
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hierarchical data extension tree. The property extension related to
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each port node must contain the key "port" and an integer value which
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is the number of the port. The object it refers to should be called "PRTX",
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where "X" is the number of the port.
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Further on, endpoints are located under the individual port nodes. The
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first hierarchical data extension package list entry of the endpoint
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nodes must begin with "endpoint" and must be followed by the number
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of the endpoint. The object it refers to should be called "EPXY", where
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"X" is the number of the port and "Y" is the number of the endpoint.
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Each port node contains a property extension key "port", the value of
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which is the number of the port node. The each endpoint is similarly numbered
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with a property extension key "endpoint". Port numbers must be unique within a
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device and endpoint numbers must be unique within a port.
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The endpoint reference uses property extension with "remote-endpoint" property
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name followed by a reference in the same package. Such references consist of the
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the remote device reference, number of the port in the device and finally the
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number of the endpoint in that port. Individual references thus appear as:
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Package() { device, port_number, endpoint_number }
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The references to endpoints must be always done both ways, to the
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remote endpoint and back from the referred remote endpoint node.
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A simple example of this is show below:
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Scope (\_SB.PCI0.I2C2)
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{
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Device (CAM0)
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{
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Name (_DSD, Package () {
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ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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Package () {
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Package () { "compatible", Package () { "nokia,smia" } },
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},
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ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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Package () {
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Package () { "port0", "PRT0" },
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}
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})
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Name (PRT0, Package() {
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ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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Package () {
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Package () { "port", 0 },
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},
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ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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Package () {
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Package () { "endpoint0", "EP00" },
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}
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})
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Name (EP00, Package() {
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ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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Package () {
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Package () { "endpoint", 0 },
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Package () { "remote-endpoint", Package() { \_SB.PCI0.ISP, 4, 0 } },
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}
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})
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}
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}
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Scope (\_SB.PCI0)
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{
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Device (ISP)
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{
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Name (_DSD, Package () {
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ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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Package () {
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Package () { "port4", "PRT4" },
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}
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})
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Name (PRT4, Package() {
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ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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Package () {
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Package () { "port", 4 }, /* CSI-2 port number */
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},
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ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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Package () {
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Package () { "endpoint0", "EP40" },
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}
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})
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Name (EP40, Package() {
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ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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Package () {
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Package () { "endpoint", 0 },
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Package () { "remote-endpoint", Package () { \_SB.PCI0.I2C2.CAM0, 0, 0 } },
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}
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})
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}
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}
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Here, the port 0 of the "CAM0" device is connected to the port 4 of
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the "ISP" device and vice versa.
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References
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----------
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[1] _DSD (Device Specific Data) Implementation Guide.
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<URL:http://www.uefi.org/sites/default/files/resources/_DSD-implementation-guide-toplevel-1_1.htm>,
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referenced 2016-10-03.
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[2] Devicetree. <URL:http://www.devicetree.org>, referenced 2016-10-03.
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[3] Documentation/devicetree/bindings/graph.txt
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[4] Device Properties UUID For _DSD.
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<URL:http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf>,
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referenced 2016-10-04.
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[5] Hierarchical Data Extension UUID For _DSD.
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<URL:http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.pdf>,
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referenced 2016-10-04.
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[6] Advanced Configuration and Power Interface Specification.
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<URL:http://www.uefi.org/sites/default/files/resources/ACPI_6_1.pdf>,
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referenced 2016-10-04.
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[7] _DSD Device Properties Usage Rules.
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Documentation/acpi/DSD-properties-rules.txt
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