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diff --git a/Documentation/networking/pse-pd/introduction.rst b/Documentation/networking/pse-pd/introduction.rst new file mode 100644 index 000000000000..e3d3faaef717 --- /dev/null +++ b/Documentation/networking/pse-pd/introduction.rst @@ -0,0 +1,73 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Power Sourcing Equipment (PSE) in IEEE 802.3 Standard +===================================================== + +Overview +-------- + +Power Sourcing Equipment (PSE) is essential in networks for delivering power +along with data over Ethernet cables. It usually refers to devices like +switches and hubs that supply power to Powered Devices (PDs) such as IP +cameras, VoIP phones, and wireless access points. + +PSE vs. PoDL PSE +---------------- + +PSE in the IEEE 802.3 standard generally refers to equipment that provides +power alongside data over Ethernet cables, typically associated with Power over +Ethernet (PoE). + +PoDL PSE, or Power over Data Lines PSE, specifically denotes PSEs operating +with single balanced twisted-pair PHYs, as per Clause 104 of IEEE 802.3. PoDL +is significant in contexts like automotive and industrial controls where power +and data delivery over a single pair is advantageous. + +IEEE 802.3-2018 Addendums and Related Clauses +--------------------------------------------- + +Key addenda to the IEEE 802.3-2018 standard relevant to power delivery over +Ethernet are as follows: + +- **802.3af (Approved in 2003-06-12)**: Known as PoE in the market, detailed in + Clause 33, delivering up to 15.4W of power. +- **802.3at (Approved in 2009-09-11)**: Marketed as PoE+, enhancing PoE as + covered in Clause 33, increasing power delivery to up to 30W. +- **802.3bt (Approved in 2018-09-27)**: Known as 4PPoE in the market, outlined + in Clause 33. Type 3 delivers up to 60W, and Type 4 up to 100W. +- **802.3bu (Approved in 2016-12-07)**: Formerly referred to as PoDL, detailed + in Clause 104. Introduces Classes 0 - 9. Class 9 PoDL PSE delivers up to ~65W + +Kernel Naming Convention Recommendations +---------------------------------------- + +For clarity and consistency within the Linux kernel's networking subsystem, the +following naming conventions are recommended: + +- For general PSE (PoE) code, use "c33_pse" key words. For example: + ``enum ethtool_c33_pse_admin_state c33_admin_control;``. + This aligns with Clause 33, encompassing various PoE forms. + +- For PoDL PSE - specific code, use "podl_pse". For example: + ``enum ethtool_podl_pse_admin_state podl_admin_control;`` to differentiate + PoDL PSE settings according to Clause 104. + +Summary of Clause 33: Data Terminal Equipment (DTE) Power via Media Dependent Interface (MDI) +--------------------------------------------------------------------------------------------- + +Clause 33 of the IEEE 802.3 standard defines the functional and electrical +characteristics of Powered Device (PD) and Power Sourcing Equipment (PSE). +These entities enable power delivery using the same generic cabling as for data +transmission, integrating power with data communication for devices such as +10BASE-T, 100BASE-TX, or 1000BASE-T. + +Summary of Clause 104: Power over Data Lines (PoDL) of Single Balanced Twisted-Pair Ethernet +-------------------------------------------------------------------------------------------- + +Clause 104 of the IEEE 802.3 standard delineates the functional and electrical +characteristics of PoDL Powered Devices (PDs) and PoDL Power Sourcing Equipment +(PSEs). These are designed for use with single balanced twisted-pair Ethernet +Physical Layers. In this clause, 'PSE' refers specifically to PoDL PSE, and +'PD' to PoDL PD. The key intent is to provide devices with a unified interface +for both data and the power required to process this data over a single +balanced twisted-pair Ethernet connection. |