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Documentation: Add documentation for Fastboot and Composite Multifunction Gadget 

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Sascha Hauer 2014-07-21 17:08:19 +02:00
parent 530731353d
commit 46ff98b011
1 changed files with 48 additions and 0 deletions
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Documentation/user/usb.rst
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@ -95,3 +95,51 @@ USB serial console
barebox can provide a serial console over USB. This can be initialized with the
:ref:`command_usbserial` command. Once the host is plugged in it should show a
new serial device, on Linux for example ``/dev/ttyACM0``.
Android Fastboot support
^^^^^^^^^^^^^^^^^^^^^^^^
barebox has support for the android fastboot protocol. There is no dedicated command
for initializing the fastboot protocol, instead it is integrated into the Multifunction
Composite Gadget, see :`ref:command_usbgadget` for a usage description.
The Fastboot gadget supports the following commands:
- fastboot flash
- fastboot getvar
- fastboot boot
- fastboot reboot
**NOTE** ``fastboot erase`` is not yet implemented. This means flashing MTD partitions
does not yet work.
The barebox Fastboot gadget supports the following non standard extensions:
- ``fastboot getvar all``
Shows a list of all variables
- ``fastboot oem getenv <varname>``
Shows a barebox environment variable
- ``fastboot oem setenv <varname>=<value>``
Sets a barebox environment variable
- ``fastboot oem exec <cmd>``
executes a shell command. Note the output can't be seen on the host, but the fastboot
command returns successfully when the barebox command was successful and it fails when
the barebox command fails.
USB Composite Multifunction Gadget
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
With the Composite Multifunction Gadget it is possible to create a USB device with
multiple functions. A useful combination is creating a Fastboot gadget and a USB serial
console. This combination can be created with:
.. code-block:: sh
usbgadget -A /dev/mmc2.0(root),/dev/mmc2.1(data) -a
The ``-A`` option will create a Fastboot function providing ``/dev/mmc2.0`` as root
partition and ``/dev/mmc2.1`` as data partition. The ``-a`` option will create a
USB CDC ACM compliant serial device.
Unlike the :ref:`command_dfu` command the ``usbgadget`` command returns immediately
after creating the gadget. The gadget can be removed with ``usbgadget -d``.