mirror of
https://github.com/torvalds/linux
synced 2024-11-05 18:23:50 +00:00
e2ba573120
Now that all files under Documentation/input follows the ReST markup language, rename them to *.rst and create a book for the Linux Input subsystem. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
85 lines
2.9 KiB
ReStructuredText
85 lines
2.9 KiB
ReStructuredText
.. include:: <isonum.txt>
|
|
|
|
===================
|
|
The userio Protocol
|
|
===================
|
|
|
|
|
|
:Copyright: |copy| 2015 Stephen Chandler Paul <thatslyude@gmail.com>
|
|
|
|
Sponsored by Red Hat
|
|
|
|
|
|
Introduction
|
|
=============
|
|
|
|
This module is intended to try to make the lives of input driver developers
|
|
easier by allowing them to test various serio devices (mainly the various
|
|
touchpads found on laptops) without having to have the physical device in front
|
|
of them. userio accomplishes this by allowing any privileged userspace program
|
|
to directly interact with the kernel's serio driver and control a virtual serio
|
|
port from there.
|
|
|
|
Usage overview
|
|
==============
|
|
|
|
In order to interact with the userio kernel module, one simply opens the
|
|
/dev/userio character device in their applications. Commands are sent to the
|
|
kernel module by writing to the device, and any data received from the serio
|
|
driver is read as-is from the /dev/userio device. All of the structures and
|
|
macros you need to interact with the device are defined in <linux/userio.h> and
|
|
<linux/serio.h>.
|
|
|
|
Command Structure
|
|
=================
|
|
|
|
The struct used for sending commands to /dev/userio is as follows::
|
|
|
|
struct userio_cmd {
|
|
__u8 type;
|
|
__u8 data;
|
|
};
|
|
|
|
``type`` describes the type of command that is being sent. This can be any one
|
|
of the USERIO_CMD macros defined in <linux/userio.h>. ``data`` is the argument
|
|
that goes along with the command. In the event that the command doesn't have an
|
|
argument, this field can be left untouched and will be ignored by the kernel.
|
|
Each command should be sent by writing the struct directly to the character
|
|
device. In the event that the command you send is invalid, an error will be
|
|
returned by the character device and a more descriptive error will be printed
|
|
to the kernel log. Only one command can be sent at a time, any additional data
|
|
written to the character device after the initial command will be ignored.
|
|
|
|
To close the virtual serio port, just close /dev/userio.
|
|
|
|
Commands
|
|
========
|
|
|
|
USERIO_CMD_REGISTER
|
|
~~~~~~~~~~~~~~~~~~~
|
|
|
|
Registers the port with the serio driver and begins transmitting data back and
|
|
forth. Registration can only be performed once a port type is set with
|
|
USERIO_CMD_SET_PORT_TYPE. Has no argument.
|
|
|
|
USERIO_CMD_SET_PORT_TYPE
|
|
~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Sets the type of port we're emulating, where ``data`` is the port type being
|
|
set. Can be any of the macros from <linux/serio.h>. For example: SERIO_8042
|
|
would set the port type to be a normal PS/2 port.
|
|
|
|
USERIO_CMD_SEND_INTERRUPT
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Sends an interrupt through the virtual serio port to the serio driver, where
|
|
``data`` is the interrupt data being sent.
|
|
|
|
Userspace tools
|
|
===============
|
|
|
|
The userio userspace tools are able to record PS/2 devices using some of the
|
|
debugging information from i8042, and play back the devices on /dev/userio. The
|
|
latest version of these tools can be found at:
|
|
|
|
https://github.com/Lyude/ps2emu
|