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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/slab.h>
#include <linux/poll.h>
#include <linux/module.h>
#include <linux/serio.h>
#include <linux/init.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];
unsigned int refcnt;
struct serio *serio;
struct miscdevice dev;
wait_queue_head_t wait;
struct list_head list;
struct list_head node;
};
struct serio_raw_list {
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);
static unsigned int serio_raw_no;
/*********************************************************************
* Interface with userspace (file operations) *
*********************************************************************/
static int serio_raw_fasync(int fd, struct file *file, int on)
{
struct serio_raw_list *list = file->private_data;
int retval;
retval = fasync_helper(fd, file, on, &list->fasync);
return retval < 0 ? retval : 0;
}
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_list *list;
int retval = 0;
retval = mutex_lock_interruptible(&serio_raw_mutex);
if (retval)
return retval;
if (!(serio_raw = serio_raw_locate(iminor(inode)))) {
retval = -ENODEV;
goto out;
}
if (!serio_raw->serio) {
retval = -ENODEV;
goto out;
}
if (!(list = kzalloc(sizeof(struct serio_raw_list), GFP_KERNEL))) {
retval = -ENOMEM;
goto out;
}
list->serio_raw = serio_raw;
file->private_data = list;
serio_raw->refcnt++;
list_add_tail(&list->node, &serio_raw->list);
out:
mutex_unlock(&serio_raw_mutex);
return retval;
}
static int serio_raw_cleanup(struct serio_raw *serio_raw)
{
if (--serio_raw->refcnt == 0) {
misc_deregister(&serio_raw->dev);
list_del_init(&serio_raw->node);
kfree(serio_raw);
return 1;
}
return 0;
}
static int serio_raw_release(struct inode *inode, struct file *file)
{
struct serio_raw_list *list = file->private_data;
struct serio_raw *serio_raw = list->serio_raw;
mutex_lock(&serio_raw_mutex);
serio_raw_fasync(-1, file, 0);
serio_raw_cleanup(serio_raw);
mutex_unlock(&serio_raw_mutex);
return 0;
}
static int serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
{
unsigned long flags;
int empty;
spin_lock_irqsave(&serio_raw->serio->lock, flags);
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;
}
spin_unlock_irqrestore(&serio_raw->serio->lock, flags);
return !empty;
}
static ssize_t serio_raw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
{
struct serio_raw_list *list = file->private_data;
struct serio_raw *serio_raw = list->serio_raw;
char c;
ssize_t retval = 0;
if (!serio_raw->serio)
return -ENODEV;
if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
return -EAGAIN;
retval = wait_event_interruptible(list->serio_raw->wait,
serio_raw->head != serio_raw->tail || !serio_raw->serio);
if (retval)
return retval;
if (!serio_raw->serio)
return -ENODEV;
while (retval < count && serio_raw_fetch_byte(serio_raw, &c)) {
if (put_user(c, buffer++))
return -EFAULT;
retval++;
}
return retval;
}
static ssize_t serio_raw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
{
struct serio_raw_list *list = file->private_data;
ssize_t written = 0;
int retval;
unsigned char c;
retval = mutex_lock_interruptible(&serio_raw_mutex);
if (retval)
return retval;
if (!list->serio_raw->serio) {
retval = -ENODEV;
goto out;
}
if (count > 32)
count = 32;
while (count--) {
if (get_user(c, buffer++)) {
retval = -EFAULT;
goto out;
}
if (serio_write(list->serio_raw->serio, c)) {
retval = -EIO;
goto out;
}
written++;
};
out:
mutex_unlock(&serio_raw_mutex);
return written;
}
static unsigned int serio_raw_poll(struct file *file, poll_table *wait)
{
struct serio_raw_list *list = file->private_data;
poll_wait(file, &list->serio_raw->wait, wait);
if (list->serio_raw->head != list->serio_raw->tail)
return POLLIN | POLLRDNORM;
return 0;
}
static 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,
};
/*********************************************************************
* Interface with serio port *
*********************************************************************/
static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
unsigned int dfl)
{
struct serio_raw *serio_raw = serio_get_drvdata(serio);
struct serio_raw_list *list;
unsigned int head = serio_raw->head;
/* we are holding serio->lock here so we are prootected */
serio_raw->queue[head] = data;
head = (head + 1) % SERIO_RAW_QUEUE_LEN;
if (likely(head != serio_raw->tail)) {
serio_raw->head = head;
list_for_each_entry(list, &serio_raw->list, node)
kill_fasync(&list->fasync, SIGIO, POLL_IN);
wake_up_interruptible(&serio_raw->wait);
}
return
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