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/*
* Raw serio device providing access to a raw byte stream from underlying
* serio port. Closely emulates behavior of pre-2.6 /dev/psaux device
*
* Copyright (c) 2004 Dmitry Torokhov
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*/
#include <linux/kref.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/module.h>
#include <linux/serio.h>
#include <linux/major.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#define DRIVER_DESC "Raw serio driver"
MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
#define SERIO_RAW_QUEUE_LEN 64
struct serio_raw {
unsigned char queue[SERIO_RAW_QUEUE_LEN];
unsigned int tail, head;
char name[16];
struct kref kref;
struct serio *serio;
struct miscdevice dev;
wait_queue_head_t wait;
struct list_head client_list;
struct list_head node;
bool dead;
};
struct serio_raw_client {
struct fasync_struct *fasync;
struct serio_raw *serio_raw;
struct list_head node;
};
static DEFINE_MUTEX(serio_raw_mutex);
static LIST_HEAD(serio_raw_list);
/*********************************************************************
* Interface with userspace (file operations) *
*********************************************************************/
static int serio_raw_fasync(int fd, struct file *file, int on)
{
struct serio_raw_client *client = file->private_data;
return fasync_helper(fd, file, on, &client->fasync);
}
static struct serio_raw *serio_raw_locate(int minor)
{
struct serio_raw *serio_raw;
list_for_each_entry(serio_raw, &serio_raw_list, node) {
if (serio_raw->dev.minor == minor)
return serio_raw;
}
return NULL;
}
static int serio_raw_open(struct inode *inode, struct file *file)
{
struct serio_raw *serio_raw;
struct serio_raw_client *client;
int retval;
retval = mutex_lock_interruptible(&serio_raw_mutex);
if (retval)
return retval;
serio_raw = serio_raw_locate(iminor(inode));
if (!serio_raw) {
retval = -ENODEV;
goto out;
}
if (serio_raw->dead) {
retval = -ENODEV;
goto out;
}
client = kzalloc(sizeof(struct serio_raw_client), GFP_KERNEL);
if (!client) {
retval = -ENOMEM;
goto out;
}
client->serio_raw = serio_raw;
file->private_data = client;
kref_get(&serio_raw->kref);
serio_pause_rx(serio_raw->serio);
list_add_tail(&client->node, &serio_raw->client_list);
serio_continue_rx(serio_raw->serio);
out:
mutex_unlock(&serio_raw_mutex);
return retval;
}
static void serio_raw_free(struct kref *kref)
{
struct serio_raw *serio_raw =
container_of(kref, struct serio_raw, kref);
put_device(&serio_raw->serio->dev);
kfree(serio_raw);
}
static int serio_raw_release(struct inode *inode, struct file *file)
{
struct serio_raw_client *client = file->private_data;
struct serio_raw *serio_raw = client->serio_raw;
serio_pause_rx(serio_raw->serio);
list_del(&client->node);
serio_continue_rx(serio_raw->serio);
kfree(client);
kref_put(&serio_raw->kref, serio_raw_free);
return 0;
}
static bool serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
{
bool empty;
serio_pause_rx(serio_raw->serio);
empty = serio_raw->head == serio_raw->tail;
if (!empty) {
*c = serio_raw->queue[serio_raw->tail];
serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
}
serio_continue_rx(serio_raw->serio);
return !empty;
}
static ssize_t serio_raw_read(struct file *file, char __user *buffer,
size_t count, loff_t *ppos)
{
struct serio_raw_client *client = file->private_data;
struct serio_raw *serio_raw = client->serio_raw;
char uninitialized_var(c);
ssize_t read = 0;
int error;
for (;;) {
if (serio_raw->dead)
return -ENODEV;
if (serio_raw->head == serio_raw->tail &&
(file->f_flags & O_NONBLOCK))
return -EAGAIN;
if (count == 0)
break;
while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
if (put_user(c, buffer++))
return -EFAULT;
read++;
}
if (read)
break;
if (!(file->f_flags & O_NONBLOCK)) {
error = wait_event_interruptible(serio_raw->wait,
serio_raw->head != serio_raw->tail ||
serio_raw->dead);
if (error)
return error;
}
}
return read;
}
static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
struct serio_raw_client *client = file->private_data;
struct serio_raw *serio_raw = client->serio_raw;
int retval = 0;
unsigned char c;
retval = mutex_lock_interruptible(&serio_raw_mutex);
if (retval)
return retval;
if (serio_raw->dead) {
retval = -ENODEV;
goto out;
}
if (count > 32)
count = 32;
while (count--) {
if (get_user(c, buffer++)) {
retval = -EFAULT;
goto out;
}
if (serio_write(serio_raw->serio, c)) {
/* Either signal error or partial write */
if (retval == 0)
retval = -EIO;
goto out;
}
retval++;
}
out:
mutex_unlock(&serio_raw_mutex);
return retval;
}
static unsigned int serio_raw_poll(struct file *file, poll_table *wait)
{
struct serio_raw_client *client = file->private_data;
struct serio_raw *serio_raw = client->serio_raw;
unsigned int mask;
poll_wait(file, &serio_raw->wait, wait);
mask = serio_raw->dead ? POLLHUP | POLLERR : POLLOUT | POLLWRNORM;
if (serio_raw->head != serio_raw->tail)
mask |= POLLIN | POLLRDNORM;
return mask;
}
static const struct file_operations serio_raw_fops = {
.owner = THIS_MODULE,
.open = serio_raw_open,
.release = serio_raw_release,
.read = serio_raw_read,
.write = serio_raw_write,
.poll = serio_raw_poll,
.fasync = serio_raw_fasync,
.llseek = noop_llseek,
};
/*********************************************************************
* Interface with serio port *
*********************************************************************/
static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
unsigned int dfl)
{<
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