driver-api/phy/phy.rst

2 PHY subsystem
7 This document explains the Generic PHY Framework along with the APIs provided,
13 *PHY* is the abbreviation for physical layer. It is used to connect a device
14 to the physical medium e.g., the USB controller has a PHY to provide functions
17 controllers have PHY functionality embedded into it and others use an external
18 PHY. Other peripherals that use PHY include Wireless LAN, Ethernet,
21 The intention of creating this framework is to bring the PHY drivers spread
25 This framework will be of use only to devices that use external PHY (PHY
28 Registering/Unregistering the PHY provider
31 PHY provider refers to an entity that implements one or more PHY instances.
32 For the simple case where the PHY provider implements only a single instance of
33 the PHY, the framework provides its own implementation of of_xlate in
34 of_phy_simple_xlate. If the PHY provider implements multiple instances, it
49 arguments. For the dt boot case, all PHY providers should use one of the above
50 2 macros to register the PHY provider.
52 Often the device tree nodes associated with a PHY provider will contain a set
53 of children that each represent a single PHY. Some bindings may nest the child
72 unregister the PHY.
74 Creating the PHY
77 The PHY driver should create the PHY in order for other peripheral controllers
78 to make use of it. The PHY framework provides 2 APIs to create the PHY.
88 The PHY drivers can use one of the above 2 APIs to create the PHY by passing
90 phy_ops is a set of function pointers for performing PHY operations such as
94 can use phy_set_drvdata() after creating the PHY and use phy_get_drvdata() in
97 4. Getting a reference to the PHY
99 Before the controller can make use of the PHY, it has to get a reference to
100 it. This framework provides the following APIs to get a reference to the PHY.
114 be used to get the PHY. In the case of dt boot, the string arguments
116 non-dt boot, it should contain the label of the PHY.  The two
117 devm_phy_get associates the device with the PHY using devres on
118 successful PHY get. On driver detach, release function is invoked on
133 Releasing a reference to the PHY
136 When the controller no longer needs the PHY, it has to release the reference
137 to the PHY it has obtained using the APIs mentioned in the above section. The
138 PHY framework provides 2 APIs to release a reference to the PHY.
145 Both these APIs are used to release a reference to the PHY and devm_phy_put
146 destroys the devres associated with this PHY.
148 Destroying the PHY
151 When the driver that created the PHY is unloaded, it should destroy the PHY it
157 Both these APIs destroy the PHY and devm_phy_destroy destroys the devres
158 associated with this PHY.
163 This subsystem is pm runtime enabled. So while creating the PHY,
165 while destroying the PHY, pm_runtime_disable is called. Note that the phy
167 phy_create (PHY provider device).
170 pm_runtime_get_sync of PHY provider device because of parent-child relationship.
177 PHY Mappings
180 In order to get reference to a PHY without help from DeviceTree, the framework
196 The documentation for PHY dt binding can be found @