usb: typec: Bus type for alternate modes (8a37d87d) · Commits · e / devices / android_kernel_teracube_emerald

Documentation/ABI/obsolete/sysfs-class-typec

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		These files are deprecated and will be removed. The same files are available
		under /sys/bus/typec (see Documentation/ABI/testing/sysfs-bus-typec).

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/svid
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		The SVID (Standard or Vendor ID) assigned by USB-IF for this
		alternate mode.

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/mode<index>/
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Every supported mode will have its own directory. The name of
		a mode will be "mode<index>" (for example mode1), where <index>
		is the actual index to the mode VDO returned by Discover Modes
		USB power delivery command.

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/mode<index>/description
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Shows description of the mode. The description is optional for
		the drivers, just like with the Billboard Devices.

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/mode<index>/vdo
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Shows the VDO in hexadecimal returned by Discover Modes command
		for this mode.

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/mode<index>/active
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Shows if the mode is active or not. The attribute can be used
		for entering/exiting the mode with partners and cable plugs, and
		with the port alternate modes it can be used for disabling
		support for specific alternate modes. Entering/exiting modes is
		supported as synchronous operation so write(2) to the attribute
		does not return until the enter/exit mode operation has
		finished. The attribute is notified when the mode is
		entered/exited so poll(2) on the attribute wakes up.
		Entering/exiting a mode will also generate uevent KOBJ_CHANGE.

		Valid values: yes, no

Documentation/ABI/testing/sysfs-bus-typec

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		What: /sys/bus/typec/devices/.../active
		Date: July 2018
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Shows if the mode is active or not. The attribute can be used
		for entering/exiting the mode. Entering/exiting modes is
		supported as synchronous operation so write(2) to the attribute
		does not return until the enter/exit mode operation has
		finished. The attribute is notified when the mode is
		entered/exited so poll(2) on the attribute wakes up.
		Entering/exiting a mode will also generate uevent KOBJ_CHANGE.

		Valid values are boolean.

		What: /sys/bus/typec/devices/.../description
		Date: July 2018
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Shows description of the mode. The description is optional for
		the drivers, just like with the Billboard Devices.

		What: /sys/bus/typec/devices/.../mode
		Date: July 2018
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		The index number of the mode returned by Discover Modes USB
		Power Delivery command. Depending on the alternate mode, the
		mode index may be significant.

		With some alternate modes (SVIDs), the mode index is assigned
		for specific functionality in the specification for that
		alternate mode.

		With other alternate modes, the mode index values are not
		assigned, and can not be therefore used for identification. When
		the mode index is not assigned, identifying the alternate mode
		must be done with either mode VDO or the description.

		What: /sys/bus/typec/devices/.../svid
		Date: July 2018
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		The Standard or Vendor ID (SVID) assigned by USB-IF for this
		alternate mode.

		What: /sys/bus/typec/devices/.../vdo
		Date: July 2018
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Shows the VDO in hexadecimal returned by Discover Modes command
		for this mode.

Documentation/ABI/testing/sysfs-class-typec

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		@@ -222,70 +222,12 @@ Description:
		available. The value can be polled.


		Alternate Mode devices.
		USB Type-C port alternate mode devices.

		The alternate modes will have Standard or Vendor ID (SVID) assigned by USB-IF.
		The ports, partners and cable plugs can have alternate modes. A supported SVID
		will consist of a set of modes. Every SVID a port/partner/plug supports will
		have a device created for it, and every supported mode for a supported SVID will
		have its own directory under that device. Below <dev> refers to the device for
		the alternate mode.

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/svid
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		The SVID (Standard or Vendor ID) assigned by USB-IF for this
		alternate mode.

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/mode<index>/
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Every supported mode will have its own directory. The name of
		a mode will be "mode<index>" (for example mode1), where <index>
		is the actual index to the mode VDO returned by Discover Modes
		USB power delivery command.

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/mode<index>/description
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Shows description of the mode. The description is optional for
		the drivers, just like with the Billboard Devices.

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/mode<index>/vdo
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Shows the VDO in hexadecimal returned by Discover Modes command
		for this mode.

		What: /sys/class/typec/<port\|partner\|cable>/<dev>/mode<index>/active
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Shows if the mode is active or not. The attribute can be used
		for entering/exiting the mode with partners and cable plugs, and
		with the port alternate modes it can be used for disabling
		support for specific alternate modes. Entering/exiting modes is
		supported as synchronous operation so write(2) to the attribute
		does not return until the enter/exit mode operation has
		finished. The attribute is notified when the mode is
		entered/exited so poll(2) on the attribute wakes up.
		Entering/exiting a mode will also generate uevent KOBJ_CHANGE.

		Valid values: yes, no

		What: /sys/class/typec/<port>/<dev>/mode<index>/supported_roles
		What: /sys/class/typec/<port>/<alt mode>/supported_roles
		Date: April 2017
		Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		Description:
		Space separated list of the supported roles.

		This attribute is available for the devices describing the
		alternate modes a port supports, and it will not be exposed with
		the devices presenting the alternate modes the partners or cable
		plugs support.

		Valid values: source, sink

Documentation/driver-api/usb/typec_bus.rst

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		API for USB Type-C Alternate Mode drivers
		=========================================

		Introduction
		------------

		Alternate modes require communication with the partner using Vendor Defined
		Messages (VDM) as defined in USB Type-C and USB Power Delivery Specifications.
		The communication is SVID (Standard or Vendor ID) specific, i.e. specific for
		every alternate mode, so every alternate mode will need a custom driver.

		USB Type-C bus allows binding a driver to the discovered partner alternate
		modes by using the SVID and the mode number.

		USB Type-C Connector Class provides a device for every alternate mode a port
		supports, and separate device for every alternate mode the partner supports.
		The drivers for the alternate modes are bound to the partner alternate mode
		devices, and the port alternate mode devices must be handled by the port
		drivers.

		When a new partner alternate mode device is registered, it is linked to the
		alternate mode device of the port that the partner is attached to, that has
		matching SVID and mode. Communication between the port driver and alternate mode
		driver will happen using the same API.

		The port alternate mode devices are used as a proxy between the partner and the
		alternate mode drivers, so the port drivers are only expected to pass the SVID
		specific commands from the alternate mode drivers to the partner, and from the
		partners to the alternate mode drivers. No direct SVID specific communication is
		needed from the port drivers, but the port drivers need to provide the operation
		callbacks for the port alternate mode devices, just like the alternate mode
		drivers need to provide them for the partner alternate mode devices.

		Usage:
		------

		General
		~~~~~~~

		By default, the alternate mode drivers are responsible for entering the mode.
		It is also possible to leave the decision about entering the mode to the user
		space (See Documentation/ABI/testing/sysfs-class-typec). Port drivers should not
		enter any modes on their own.

		``->vdm`` is the most important callback in the operation callbacks vector. It
		will be used to deliver all the SVID specific commands from the partner to the
		alternate mode driver, and vice versa in case of port drivers. The drivers send
		the SVID specific commands to each other using :c:func:`typec_altmode_vmd()`.

		If the communication with the partner using the SVID specific commands results
		in need to reconfigure the pins on the connector, the alternate mode driver
		needs to notify the bus using :c:func:`typec_altmode_notify()`. The driver
		passes the negotiated SVID specific pin configuration value to the function as
		parameter. The bus driver will then configure the mux behind the connector using
		that value as the state value for the mux, and also call blocking notification
		chain to notify the external drivers about the state of the connector that need
		to know it.

		NOTE: The SVID specific pin configuration values must always start from
		``TYPEC_STATE_MODAL``. USB Type-C specification defines two default states for
		the connector: ``TYPEC_STATE_USB`` and ``TYPEC_STATE_SAFE``. These values are
		reserved by the bus as the first possible values for the state. When the
		alternate mode is entered, the bus will put the connector into
		``TYPEC_STATE_SAFE`` before sending Enter or Exit Mode command as defined in USB
		Type-C Specification, and also put the connector back to ``TYPEC_STATE_USB``
		after the mode has been exited.

		An example of working definitions for SVID specific pin configurations would
		look like this:

		enum {
		ALTMODEX_CONF_A = TYPEC_STATE_MODAL,
		ALTMODEX_CONF_B,
		...
		};

		Helper macro ``TYPEC_MODAL_STATE()`` can also be used:

		#define ALTMODEX_CONF_A = TYPEC_MODAL_STATE(0);
		#define ALTMODEX_CONF_B = TYPEC_MODAL_STATE(1);

		Notification chain
		~~~~~~~~~~~~~~~~~~

		The drivers for the components that the alternate modes are designed for need to
		get details regarding the results of the negotiation with the partner, and the
		pin configuration of the connector. In case of DisplayPort alternate mode for
		example, the GPU drivers will need to know those details. In case of
		Thunderbolt alternate mode, the thunderbolt drivers will need to know them, and
		so on.

		The notification chain is designed for this purpose. The drivers can register
		notifiers with :c:func:`typec_altmode_register_notifier()`.

		Cable plug alternate modes
		~~~~~~~~~~~~~~~~~~~~~~~~~~

		The alternate mode drivers are not bound to cable plug alternate mode devices,
		only to the partner alternate mode devices. If the alternate mode supports, or
		requires, a cable that responds to SOP Prime, and optionally SOP Double Prime
		messages, the driver for that alternate mode must request handle to the cable
		plug alternate modes using :c:func:`typec_altmode_get_plug()`, and take over
		their control.

		Driver API
		----------

		Alternate mode driver registering/unregistering
		~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

		.. kernel-doc:: drivers/usb/typec/bus.c
		:functions: typec_altmode_register_driver typec_altmode_unregister_driver

		Alternate mode driver operations
		~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

		.. kernel-doc:: drivers/usb/typec/bus.c
		:functions: typec_altmode_enter typec_altmode_exit typec_altmode_attention typec_altmode_vdm typec_altmode_notify

		API for the port drivers
		~~~~~~~~~~~~~~~~~~~~~~~~

		.. kernel-doc:: drivers/usb/typec/bus.c
		:functions: typec_match_altmode

		Cable Plug operations
		~~~~~~~~~~~~~~~~~~~~~

		.. kernel-doc:: drivers/usb/typec/bus.c
		:functions: typec_altmode_get_plug typec_altmode_put_plug

		Notifications
		~~~~~~~~~~~~~
		.. kernel-doc:: drivers/usb/typec/class.c
		:functions: typec_altmode_register_notifier typec_altmode_unregister_notifier

MAINTAINERS

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		@@ -14955,7 +14955,7 @@ L: linux-usb@vger.kernel.org
		S: Maintained
		F: drivers/usb/typec/mux/pi3usb30532.c

		USB TYPEC SUBSYSTEM
		USB TYPEC CLASS
		M: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		L: linux-usb@vger.kernel.org
		S: Maintained
		@@ -14964,6 +14964,15 @@ F: Documentation/driver-api/usb/typec.rst
		F: drivers/usb/typec/
		F: include/linux/usb/typec.h

		USB TYPEC BUS FOR ALTERNATE MODES
		M: Heikki Krogerus <heikki.krogerus@linux.intel.com>
		L: linux-usb@vger.kernel.org
		S: Maintained
		F: Documentation/ABI/testing/sysfs-bus-typec
		F: Documentation/driver-api/usb/typec_bus.rst
		F: drivers/usb/typec/altmodes/
		F: include/linux/usb/typec_altmode.h

		USB UHCI DRIVER
		M: Alan Stern <stern@rowland.harvard.edu>
		L: linux-usb@vger.kernel.org