Commit 5523662e authored by Stephen Chandler Paul's avatar Stephen Chandler Paul Committed by Dmitry Torokhov

Input: add userio module

Debugging input devices, specifically laptop touchpads, can be tricky
without having the physical device handy. Here we try to remedy that
with userio. This module allows an application to connect to a character
device provided by the kernel, and emulate any serio device. In
combination with userspace programs that can record PS/2 devices and
replay them through the /dev/userio device, this allows developers to
debug driver issues on the PS/2 level with devices simply by requesting
a recording from the user experiencing the issue without having to have
the physical hardware in front of them.
Signed-off-by: default avatarStephen Chandler Paul <cpaul@redhat.com>
Reviewed-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 06a16293
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
......@@ -11100,6 +11100,12 @@ S: Maintained
F: drivers/media/v4l2-core/videobuf2-*
F: include/media/videobuf2-*
VIRTUAL SERIO DEVICE DRIVER
M: Stephen Chandler Paul <thatslyude@gmail.com>
S: Maintained
F: drivers/input/serio/userio.c
F: include/uapi/linux/userio.h
VIRTIO CONSOLE DRIVER
M: Amit Shah <amit.shah@redhat.com>
L: virtualization@lists.linux-foundation.org
......
......@@ -292,4 +292,18 @@ config SERIO_SUN4I_PS2
To compile this driver as a module, choose M here: the
module will be called sun4i-ps2.
config USERIO
tristate "User space serio port driver support"
help
Say Y here if you want to support user level drivers for serio
subsystem accessible under char device 10:240 - /dev/userio. Using
this facility userspace programs can implement serio ports that
will be used by the standard in-kernel serio consumer drivers,
such as psmouse and atkbd.
To compile this driver as a module, choose M here: the module will be
called userio.
If you are unsure, say N.
endif
......@@ -30,3 +30,4 @@ obj-$(CONFIG_SERIO_APBPS2) += apbps2.o
obj-$(CONFIG_SERIO_OLPC_APSP) += olpc_apsp.o
obj-$(CONFIG_HYPERV_KEYBOARD) += hyperv-keyboard.o
obj-$(CONFIG_SERIO_SUN4I_PS2) += sun4i-ps2.o
obj-$(CONFIG_USERIO) += userio.o
/*
* userio kernel serio device emulation module
* Copyright (C) 2015 Red Hat
* Copyright (C) 2015 Stephen Chandler Paul <thatslyude@gmail.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
* General Public License for more details.
*/
#include <linux/circ_buf.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/serio.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <uapi/linux/userio.h>
#define USERIO_NAME "userio"
#define USERIO_BUFSIZE 16
static struct miscdevice userio_misc;
struct userio_device {
struct serio *serio;
struct mutex mutex;
bool running;
u8 head;
u8 tail;
spinlock_t buf_lock;
unsigned char buf[USERIO_BUFSIZE];
wait_queue_head_t waitq;
};
/**
* userio_device_write - Write data from serio to a userio device in userspace
* @id: The serio port for the userio device
* @val: The data to write to the device
*/
static int userio_device_write(struct serio *id, unsigned char val)
{
struct userio_device *userio = id->port_data;
unsigned long flags;
spin_lock_irqsave(&userio->buf_lock, flags);
userio->buf[userio->head] = val;
userio->head = (userio->head + 1) % USERIO_BUFSIZE;
if (userio->head == userio->tail)
dev_warn(userio_misc.this_device,
"Buffer overflowed, userio client isn't keeping up");
spin_unlock_irqrestore(&userio->buf_lock, flags);
wake_up_interruptible(&userio->waitq);
return 0;
}
static int userio_char_open(struct inode *inode, struct file *file)
{
struct userio_device *userio;
userio = kzalloc(sizeof(struct userio_device), GFP_KERNEL);
if (!userio)
return -ENOMEM;
mutex_init(&userio->mutex);
spin_lock_init(&userio->buf_lock);
init_waitqueue_head(&userio->waitq);
userio->serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
if (!userio->serio) {
kfree(userio);
return -ENOMEM;
}
userio->serio->write = userio_device_write;
userio->serio->port_data = userio;
file->private_data = userio;
return 0;
}
static int userio_char_release(struct inode *inode, struct file *file)
{
struct userio_device *userio = file->private_data;
if (userio->running) {
/*
* Don't free the serio port here, serio_unregister_port()
* does it for us.
*/
serio_unregister_port(userio->serio);
} else {
kfree(userio->serio);
}
kfree(userio);
return 0;
}
static ssize_t userio_char_read(struct file *file, char __user *user_buffer,
size_t count, loff_t *ppos)
{
struct userio_device *userio = file->private_data;
int error;
size_t nonwrap_len, copylen;
unsigned char buf[USERIO_BUFSIZE];
unsigned long flags;
/*
* By the time we get here, the data that was waiting might have
* been taken by another thread. Grab the buffer lock and check if
* there's still any data waiting, otherwise repeat this process
* until we have data (unless the file descriptor is non-blocking
* of course).
*/
for (;;) {
spin_lock_irqsave(&userio->buf_lock, flags);
nonwrap_len = CIRC_CNT_TO_END(userio->head,
userio->tail,
USERIO_BUFSIZE);
copylen = min(nonwrap_len, count);
if (copylen) {
memcpy(buf, &userio->buf[userio->tail], copylen);
userio->tail = (userio->tail + copylen) %
USERIO_BUFSIZE;
}
spin_unlock_irqrestore(&userio->buf_lock, flags);
if (nonwrap_len)
break;
/* buffer was/is empty */
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
/*
* count == 0 is special - no IO is done but we check
* for error conditions (see above).
*/
if (count == 0)
return 0;
error = wait_event_interruptible(userio->waitq,
userio->head != userio->tail);
if (error)
return error;
}
if (copylen)
if (copy_to_user(user_buffer, buf, copylen))
return -EFAULT;
return copylen;
}
static ssize_t userio_char_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
struct userio_device *userio = file->private_data;
struct userio_cmd cmd;
int error;
if (count != sizeof(cmd)) {
dev_warn(userio_misc.this_device, "Invalid payload size\n");
return -EINVAL;
}
if (copy_from_user(&cmd, buffer, sizeof(cmd)))
return -EFAULT;
error = mutex_lock_interruptible(&userio->mutex);
if (error)
return error;
switch (cmd.type) {
case USERIO_CMD_REGISTER:
if (!userio->serio->id.type) {
dev_warn(userio_misc.this_device,
"No port type given on /dev/userio\n");
error = -EINVAL;
goto out;
}
if (userio->running) {
dev_warn(userio_misc.this_device,
"Begin command sent, but we're already running\n");
error = -EBUSY;
goto out;
}
userio->running = true;
serio_register_port(userio->serio);
break;
case USERIO_CMD_SET_PORT_TYPE:
if (userio->running) {
dev_warn(userio_misc.this_device,
"Can't change port type on an already running userio instance\n");
error = -EBUSY;
goto out;
}
userio->serio->id.type = cmd.data;
break;
case USERIO_CMD_SEND_INTERRUPT:
if (!userio->running) {
dev_warn(userio_misc.this_device,
"The device must be registered before sending interrupts\n");
error = -ENODEV;
goto out;
}
serio_interrupt(userio->serio, cmd.data, 0);
break;
default:
error = -EOPNOTSUPP;
goto out;
}
out:
mutex_unlock(&userio->mutex);
return error ?: count;
}
static unsigned int userio_char_poll(struct file *file, poll_table *wait)
{
struct userio_device *userio = file->private_data;
poll_wait(file, &userio->waitq, wait);
if (userio->head != userio->tail)
return POLLIN | POLLRDNORM;
return 0;
}
static const struct file_operations userio_fops = {
.owner = THIS_MODULE,
.open = userio_char_open,
.release = userio_char_release,
.read = userio_char_read,
.write = userio_char_write,
.poll = userio_char_poll,
.llseek = no_llseek,
};
static struct miscdevice userio_misc = {
.fops = &userio_fops,
.minor = USERIO_MINOR,
.name = USERIO_NAME,
};
module_driver(userio_misc, misc_register, misc_deregister);
MODULE_ALIAS_MISCDEV(USERIO_MINOR);
MODULE_ALIAS("devname:" USERIO_NAME);
MODULE_AUTHOR("Stephen Chandler Paul <thatslyude@gmail.com>");
MODULE_DESCRIPTION("Virtual Serio Device Support");
MODULE_LICENSE("GPL");
......@@ -49,6 +49,7 @@
#define LOOP_CTRL_MINOR 237
#define VHOST_NET_MINOR 238
#define UHID_MINOR 239
#define USERIO_MINOR 240
#define MISC_DYNAMIC_MINOR 255
struct device;
......
/*
* userio: virtual serio device support
* Copyright (C) 2015 Red Hat
* Copyright (C) 2015 Lyude (Stephen Chandler Paul) <cpaul@redhat.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
* details.
*
* This is the public header used for user-space communication with the userio
* driver. __attribute__((__packed__)) is used for all structs to keep ABI
* compatibility between all architectures.
*/
#ifndef _USERIO_H
#define _USERIO_H
#include <linux/types.h>
enum userio_cmd_type {
USERIO_CMD_REGISTER = 0,
USERIO_CMD_SET_PORT_TYPE = 1,
USERIO_CMD_SEND_INTERRUPT = 2
};
/*
* userio Commands
* All commands sent to /dev/userio are encoded using this structure. The type
* field should contain a USERIO_CMD* value that indicates what kind of command
* is being sent to userio. The data field should contain the accompanying
* argument for the command, if there is one.
*/
struct userio_cmd {
__u8 type;
__u8 data;
} __attribute__((__packed__));
#endif /* !_USERIO_H */
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