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Diffstat (limited to 'Documentation/usb')
| -rw-r--r-- | Documentation/usb/typec.rst | 184 | ||||
| -rw-r--r-- | Documentation/usb/usb3-debug-port.rst | 100 |
2 files changed, 0 insertions, 284 deletions
diff --git a/Documentation/usb/typec.rst b/Documentation/usb/typec.rst deleted file mode 100644 index b67a46779de9..000000000000 --- a/Documentation/usb/typec.rst +++ /dev/null @@ -1,184 +0,0 @@ - -USB Type-C connector class -========================== - -Introduction ------------- - -The typec class is meant for describing the USB Type-C ports in a system to the -user space in unified fashion. The class is designed to provide nothing else -except the user space interface implementation in hope that it can be utilized -on as many platforms as possible. - -The platforms are expected to register every USB Type-C port they have with the -class. In a normal case the registration will be done by a USB Type-C or PD PHY -driver, but it may be a driver for firmware interface such as UCSI, driver for -USB PD controller or even driver for Thunderbolt3 controller. This document -considers the component registering the USB Type-C ports with the class as "port -driver". - -On top of showing the capabilities, the class also offer user space control over -the roles and alternate modes of ports, partners and cable plugs when the port -driver is capable of supporting those features. - -The class provides an API for the port drivers described in this document. The -attributes are described in Documentation/ABI/testing/sysfs-class-typec. - -User space interface --------------------- -Every port will be presented as its own device under /sys/class/typec/. The -first port will be named "port0", the second "port1" and so on. - -When connected, the partner will be presented also as its own device under -/sys/class/typec/. The parent of the partner device will always be the port it -is attached to. The partner attached to port "port0" will be named -"port0-partner". Full path to the device would be -/sys/class/typec/port0/port0-partner/. - -The cable and the two plugs on it may also be optionally presented as their own -devices under /sys/class/typec/. The cable attached to the port "port0" port -will be named port0-cable and the plug on the SOP Prime end (see USB Power -Delivery Specification ch. 2.4) will be named "port0-plug0" and on the SOP -Double Prime end "port0-plug1". The parent of a cable will always be the port, -and the parent of the cable plugs will always be the cable. - -If the port, partner or cable plug supports Alternate Modes, every supported -Alternate Mode SVID will have their own device describing them. Note that the -Alternate Mode devices will not be attached to the typec class. The parent of an -alternate mode will be the device that supports it, so for example an alternate -mode of port0-partner will be presented under /sys/class/typec/port0-partner/. -Every mode that is supported will have its own group under the Alternate Mode -device named "mode<index>", for example /sys/class/typec/port0/<alternate -mode>/mode1/. The requests for entering/exiting a mode can be done with "active" -attribute file in that group. - -Driver API ----------- - -Registering the ports -~~~~~~~~~~~~~~~~~~~~~ - -The port drivers will describe every Type-C port they control with struct -typec_capability data structure, and register them with the following API: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_register_port typec_unregister_port - -When registering the ports, the prefer_role member in struct typec_capability -deserves special notice. If the port that is being registered does not have -initial role preference, which means the port does not execute Try.SNK or -Try.SRC by default, the member must have value TYPEC_NO_PREFERRED_ROLE. -Otherwise if the port executes Try.SNK by default, the member must have value -TYPEC_DEVICE, and with Try.SRC the value must be TYPEC_HOST. - -Registering Partners -~~~~~~~~~~~~~~~~~~~~ - -After successful connection of a partner, the port driver needs to register the -partner with the class. Details about the partner need to be described in struct -typec_partner_desc. The class copies the details of the partner during -registration. The class offers the following API for registering/unregistering -partners. - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_register_partner typec_unregister_partner - -The class will provide a handle to struct typec_partner if the registration was -successful, or NULL. - -If the partner is USB Power Delivery capable, and the port driver is able to -show the result of Discover Identity command, the partner descriptor structure -should include handle to struct usb_pd_identity instance. The class will then -create a sysfs directory for the identity under the partner device. The result -of Discover Identity command can then be reported with the following API: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_partner_set_identity - -Registering Cables -~~~~~~~~~~~~~~~~~~ - -After successful connection of a cable that supports USB Power Delivery -Structured VDM "Discover Identity", the port driver needs to register the cable -and one or two plugs, depending if there is CC Double Prime controller present -in the cable or not. So a cable capable of SOP Prime communication, but not SOP -Double Prime communication, should only have one plug registered. For more -information about SOP communication, please read chapter about it from the -latest USB Power Delivery specification. - -The plugs are represented as their own devices. The cable is registered first, -followed by registration of the cable plugs. The cable will be the parent device -for the plugs. Details about the cable need to be described in struct -typec_cable_desc and about a plug in struct typec_plug_desc. The class copies -the details during registration. The class offers the following API for -registering/unregistering cables and their plugs: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_register_cable typec_unregister_cable typec_register_plug - typec_unregister_plug - -The class will provide a handle to struct typec_cable and struct typec_plug if -the registration is successful, or NULL if it isn't. - -If the cable is USB Power Delivery capable, and the port driver is able to show -the result of Discover Identity command, the cable descriptor structure should -include handle to struct usb_pd_identity instance. The class will then create a -sysfs directory for the identity under the cable device. The result of Discover -Identity command can then be reported with the following API: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_cable_set_identity - -Notifications -~~~~~~~~~~~~~ - -When the partner has executed a role change, or when the default roles change -during connection of a partner or cable, the port driver must use the following -APIs to report it to the class: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_set_data_role typec_set_pwr_role typec_set_vconn_role - typec_set_pwr_opmode - -Alternate Modes -~~~~~~~~~~~~~~~ - -USB Type-C ports, partners and cable plugs may support Alternate Modes. Each -Alternate Mode will have identifier called SVID, which is either a Standard ID -given by USB-IF or vendor ID, and each supported SVID can have 1 - 6 modes. The -class provides struct typec_mode_desc for describing individual mode of a SVID, -and struct typec_altmode_desc which is a container for all the supported modes. - -Ports that support Alternate Modes need to register each SVID they support with -the following API: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_port_register_altmode - -If a partner or cable plug provides a list of SVIDs as response to USB Power -Delivery Structured VDM Discover SVIDs message, each SVID needs to be -registered. - -API for the partners: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_partner_register_altmode - -API for the Cable Plugs: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_plug_register_altmode - -So ports, partners and cable plugs will register the alternate modes with their -own functions, but the registration will always return a handle to struct -typec_altmode on success, or NULL. The unregistration will happen with the same -function: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_unregister_altmode - -If a partner or cable plug enters or exits a mode, the port driver needs to -notify the class with the following API: - -.. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_altmode_update_active diff --git a/Documentation/usb/usb3-debug-port.rst b/Documentation/usb/usb3-debug-port.rst deleted file mode 100644 index feb1a36a65b7..000000000000 --- a/Documentation/usb/usb3-debug-port.rst +++ /dev/null @@ -1,100 +0,0 @@ -=============== -USB3 debug port -=============== - -:Author: Lu Baolu <baolu.lu@linux.intel.com> -:Date: March 2017 - -GENERAL -======= - -This is a HOWTO for using the USB3 debug port on x86 systems. - -Before using any kernel debugging functionality based on USB3 -debug port, you need to:: - - 1) check whether any USB3 debug port is available in - your system; - 2) check which port is used for debugging purposes; - 3) have a USB 3.0 super-speed A-to-A debugging cable. - -INTRODUCTION -============ - -The xHCI debug capability (DbC) is an optional but standalone -functionality provided by the xHCI host controller. The xHCI -specification describes DbC in the section 7.6. - -When DbC is initialized and enabled, it will present a debug -device through the debug port (normally the first USB3 -super-speed port). The debug device is fully compliant with -the USB framework and provides the equivalent of a very high -performance full-duplex serial link between the debug target -(the system under debugging) and a debug host. - -EARLY PRINTK -============ - -DbC has been designed to log early printk messages. One use for -this feature is kernel debugging. For example, when your machine -crashes very early before the regular console code is initialized. -Other uses include simpler, lockless logging instead of a full- -blown printk console driver and klogd. - -On the debug target system, you need to customize a debugging -kernel with CONFIG_EARLY_PRINTK_USB_XDBC enabled. And, add below -kernel boot parameter:: - - "earlyprintk=xdbc" - -If there are multiple xHCI controllers in your system, you can -append a host contoller index to this kernel parameter. This -index starts from 0. - -Current design doesn't support DbC runtime suspend/resume. As -the result, you'd better disable runtime power management for -USB subsystem by adding below kernel boot parameter:: - - "usbcore.autosuspend=-1" - -Before starting the debug target, you should connect the debug -port to a USB port (root port or port of any external hub) on -the debug host. The cable used to connect these two ports -should be a USB 3.0 super-speed A-to-A debugging cable. - -During early boot of the debug target, DbC will be detected and -initialized. After initialization, the debug host should be able -to enumerate the debug device in debug target. The debug host -will then bind the debug device with the usb_debug driver module -and create the /dev/ttyUSB device. - -If the debug device enumeration goes smoothly, you should be able -to see below kernel messages on the debug host:: - - # tail -f /var/log/kern.log - [ 1815.983374] usb 4-3: new SuperSpeed USB device number 4 using xhci_hcd - [ 1815.999595] usb 4-3: LPM exit latency is zeroed, disabling LPM. - [ 1815.999899] usb 4-3: New USB device found, idVendor=1d6b, idProduct=0004 - [ 1815.999902] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3 - [ 1815.999903] usb 4-3: Product: Remote GDB - [ 1815.999904] usb 4-3: Manufacturer: Linux - [ 1815.999905] usb 4-3: SerialNumber: 0001 - [ 1816.000240] usb_debug 4-3:1.0: xhci_dbc converter detected - [ 1816.000360] usb 4-3: xhci_dbc converter now attached to ttyUSB0 - -You can use any communication program, for example minicom, to -read and view the messages. Below simple bash scripts can help -you to check the sanity of the setup. - -.. code-block:: sh - - ===== start of bash scripts ============= - #!/bin/bash - - while true ; do - while [ ! -d /sys/class/tty/ttyUSB0 ] ; do - : - done - cat /dev/ttyUSB0 - done - ===== end of bash scripts =============== |