|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.
|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.
|.. kernel-doc:: drivers/base/devcon.c
| :functions: device_connection_find_match device_connection_find device_connection_add device_connection_remove