mirror of https://gitee.com/openkylin/linux.git
71 lines
2.9 KiB
Plaintext
71 lines
2.9 KiB
Plaintext
|
The userio Protocol
|
||
|
|
(c) 2015 Stephen Chandler Paul <thatslyude@gmail.com>
|
||
|
|
Sponsored by Red Hat
|
||
|
|
--------------------------------------------------------------------------------
|
||
|
|
|
||
|
|
1. 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.
|
||
|
|
|
||
|
|
2. 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>.
|
||
|
|
|
||
|
|
3. 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.
|
||
|
|
|
||
|
|
4. Commands
|
||
|
|
~~~~~~~~~~~
|
||
|
|
|
||
|
|
4.1 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.
|
||
|
|
|
||
|
|
4.2 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.
|
||
|
|
|
||
|
|
4.3 USERIO_CMD_SEND_INTERRUPT
|
||
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||
|
|
Sends an interrupt through the virtual serio port to the serio driver, where
|
||
|
|
"data" is the interrupt data being sent.
|
||
|
|
|
||
|
|
5. 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
|