mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-22 04:03:58 +08:00
b976583f88
Using incorrect :functions: syntax (extra space) causes an odd kernel-doc warning, so fix that. Documentation/driver-api/device_connection.rst:42: ERROR: Error in "kernel-doc" directive: Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
44 lines
1.8 KiB
ReStructuredText
44 lines
1.8 KiB
ReStructuredText
==================
|
|
Device connections
|
|
==================
|
|
|
|
Introduction
|
|
------------
|
|
|
|
Devices often have connections to other devices that are outside of the direct
|
|
child/parent relationship. A serial or network communication controller, which
|
|
could be a PCI device, may need to be able to get a reference to its PHY
|
|
component, which could be attached for example to the I2C bus. Some device
|
|
drivers need to be able to control the clocks or the GPIOs for their devices,
|
|
and so on.
|
|
|
|
Device connections are generic descriptions of any type of connection between
|
|
two separate devices.
|
|
|
|
Device connections alone do not create a dependency between the two devices.
|
|
They are only descriptions which are not tied to either of the devices directly.
|
|
A dependency between the two devices exists only if one of the two endpoint
|
|
devices requests a reference to the other. The descriptions themselves can be
|
|
defined in firmware (not yet supported) or they can be built-in.
|
|
|
|
Usage
|
|
-----
|
|
|
|
Device connections should exist before device ``->probe`` callback is called for
|
|
either endpoint device in the description. If the connections are defined in
|
|
firmware, this is not a problem. It should be considered if the connection
|
|
descriptions are "built-in", and need to be added separately.
|
|
|
|
The connection description consists of the names of the two devices with the
|
|
connection, i.e. the endpoints, and unique identifier for the connection which
|
|
is needed if there are multiple connections between the two devices.
|
|
|
|
After a description exists, the devices in it can request reference to the other
|
|
endpoint device, or they can request the description itself.
|
|
|
|
API
|
|
---
|
|
|
|
.. kernel-doc:: drivers/base/devcon.c
|
|
:functions: device_connection_find_match device_connection_find device_connection_add device_connection_remove
|