@@ -293,10 +293,13 @@ config SERIO_SUN4I_PS2
module will be called sun4i-ps2.
config USERIO
- tristate "Virtual serio device support"
+ tristate "User space serio port driver support"
help
- Say Y here if you want to emulate serio devices using the userio
- kernel module.
+ 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.
@@ -4,14 +4,14 @@
* 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.
+ * 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 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>
@@ -27,14 +27,14 @@
#include <linux/poll.h>
#include <uapi/linux/userio.h>
-#define USERIO_NAME "userio"
-#define USERIO_BUFSIZE 16
+#define USERIO_NAME "userio"
+#define USERIO_BUFSIZE 16
static struct miscdevice userio_misc;
struct userio_device {
struct serio *serio;
- struct mutex lock;
+ struct mutex mutex;
bool running;
@@ -81,7 +81,7 @@ static int userio_char_open(struct inode *inode, struct file *file)
if (!userio)
return -ENOMEM;
- mutex_init(&userio->lock);
+ mutex_init(&userio->mutex);
spin_lock_init(&userio->buf_lock);
init_waitqueue_head(&userio->waitq);
@@ -103,12 +103,15 @@ static int userio_char_release(struct inode *inode, struct file *file)
{
struct userio_device *userio = file->private_data;
- /* Don't free the serio port here, serio_unregister_port() does
- * this for us */
- if (userio->running)
+ if (userio->running) {
+ /*
+ * Don't free the serio port here, serio_unregister_port()
+ * does it for us.
+ */
serio_unregister_port(userio->serio);
- else
+ } else {
kfree(userio->serio);
+ }
kfree(userio);
@@ -119,48 +122,56 @@ 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 ret;
+ int error;
size_t nonwrap_len, copylen;
unsigned char buf[USERIO_BUFSIZE];
unsigned long flags;
- if (!count)
- return 0;
-
/*
- * By the time we get here, the data that was waiting might have been
- * taken by another thread. Grab the mutex 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)
+ * 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);
- if (userio->head != userio->tail)
- break;
+ 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;
- ret = wait_event_interruptible(userio->waitq,
- userio->head != userio->tail);
- if (ret)
- return ret;
+ /*
+ * 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;
}
- nonwrap_len = CIRC_CNT_TO_END(userio->head, userio->tail,
- USERIO_BUFSIZE);
- copylen = min(nonwrap_len, count);
- memcpy(buf, &userio->buf[userio->tail], copylen);
-
- userio->tail = (userio->tail + copylen) % USERIO_BUFSIZE;
-
- spin_unlock_irqrestore(&userio->buf_lock, flags);
-
- if (copy_to_user(user_buffer, buf, copylen))
- return -EFAULT;
+ if (copylen)
+ if (copy_to_user(user_buffer, buf, copylen))
+ return -EFAULT;
return copylen;
}
@@ -170,7 +181,7 @@ static ssize_t userio_char_write(struct file *file, const char __user *buffer,
{
struct userio_device *userio = file->private_data;
struct userio_cmd cmd;
- int ret;
+ int error;
if (count != sizeof(cmd)) {
dev_warn(userio_misc.this_device, "Invalid payload size\n");
@@ -180,9 +191,9 @@ static ssize_t userio_char_write(struct file *file, const char __user *buffer,
if (copy_from_user(&cmd, buffer, sizeof(cmd)))
return -EFAULT;
- ret = mutex_lock_interruptible(&userio->lock);
- if (ret)
- return ret;
+ error = mutex_lock_interruptible(&userio->mutex);
+ if (error)
+ return error;
switch (cmd.type) {
case USERIO_CMD_REGISTER:
@@ -190,14 +201,14 @@ static ssize_t userio_char_write(struct file *file, const char __user *buffer,
dev_warn(userio_misc.this_device,
"No port type given on /dev/userio\n");
- ret = -EINVAL;
+ error = -EINVAL;
goto out;
}
+
if (userio->running) {
dev_warn(userio_misc.this_device,
"Begin command sent, but we're already running\n");
-
- ret = -EBUSY;
+ error = -EBUSY;
goto out;
}
@@ -209,8 +220,7 @@ static ssize_t userio_char_write(struct file *file, const char __user *buffer,
if (userio->running) {
dev_warn(userio_misc.this_device,
"Can't change port type on an already running userio instance\n");
-
- ret = -EBUSY;
+ error = -EBUSY;
goto out;
}
@@ -221,8 +231,7 @@ static ssize_t userio_char_write(struct file *file, const char __user *buffer,
if (!userio->running) {
dev_warn(userio_misc.this_device,
"The device must be registered before sending interrupts\n");
-
- ret = -ENODEV;
+ error = -ENODEV;
goto out;
}
@@ -230,15 +239,13 @@ static ssize_t userio_char_write(struct file *file, const char __user *buffer,
break;
default:
- ret = -EOPNOTSUPP;
+ error = -EOPNOTSUPP;
goto out;
}
- ret = sizeof(cmd);
-
out:
- mutex_unlock(&userio->lock);
- return ret;
+ mutex_unlock(&userio->mutex);
+ return error ?: count;
}
static unsigned int userio_char_poll(struct file *file, poll_table *wait)
@@ -268,6 +275,7 @@ static struct miscdevice userio_misc = {
.minor = USERIO_MINOR,
.name = USERIO_NAME,
};
+module_driver(userio_misc, misc_register, misc_deregister);
MODULE_ALIAS_MISCDEV(USERIO_MINOR);
MODULE_ALIAS("devname:" USERIO_NAME);
@@ -275,5 +283,3 @@ MODULE_ALIAS("devname:" USERIO_NAME);
MODULE_AUTHOR("Stephen Chandler Paul <thatslyude@gmail.com>");
MODULE_DESCRIPTION("Virtual Serio Device Support");
MODULE_LICENSE("GPL");
-
-module_driver(userio_misc, misc_register, misc_deregister);