I've written following kernel module to convert network device into
tty. Why is it usefull?
Well, I like unix for its "everything is a file" rule. Unfortunately,
network devices do not follow same rules. I see no reason why I should
not be allowed to run ppp over point-to-point ethernet.
What is worse, there's even practical problem. Infrared
connections. irda consorcium produced something very ugly. I'd like to
use irda devices for some other protocol than irda. One such is
available - it is called scarab (basically simplex slip). As long as
I'm talking about <115200 speeds and about non-toshiba notebooks, it
is ok. I can choose not to tell system ttyS1 is in fact irda and run
scarab over it. But toshiba's irda port does not look like serial any
more, so I have to use toshoboe module. But toshoboe looks like
network device, not like tty (required for scarab). Ok, so here's
module. It does not work too well, but it should give you hint of what
I'm doing.
Compile by
gcc -D__KERNEL__ -I/usr/src/linux/include -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -pipe -fno-strength-reduce -m386 -DCPU=386 -DMODULE -c -o n2cd.o n2cd.c
Some pieces are simply wrong (alloc_skb in n2cd_write), I'd be happy
if someone told me how to repair them.
Pavel
/*
* Copyright 1999 Pavel Machek, distribute under GPL version 2 or later.
*
* This converts network device into character device.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/malloc.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/poll.h>
#include <linux/miscdevice.h>
#include <linux/random.h>
#include <linux/wait.h>
#include <linux/fs.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/kbd_kern.h>
#include <linux/pci.h>
#include <asm/io.h>
#include <asm/dma.h>
#include <asm/byteorder.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/irq.h>
#define ID printk( "n2cd: " )
//#define ETH_P_N2CD 1234
//#define ETH_P_N2CD ETH_P_IP
#define ETH_P_N2CD ETH_P_IRDA
#define MAXDEVS 64
static struct device *my_dev, *attached_device;
static struct tty_struct *my_tty = NULL;
/* --------------- My hack to overcome flip inadequacy -------------- */
struct tq_struct tqueue;
int todo = 0;
static void do_softint(void *unused)
{
if (todo & 1) {
if (my_tty->flags & (1 << TTY_DO_WRITE_WAKEUP))
if (my_tty->ldisc.write_wakeup) {
ID; printk( "Waking up line discipline\n" );
(my_tty->ldisc.write_wakeup)(my_tty);
}
wake_up_interruptible(&my_tty->write_wait);
}
}
/* --------------------- generic tir2000 handling -------------------------- */
static void
receive_byte(struct device *dev, int what)
{
tty_insert_flip_char(my_tty, what, 0);
}
void
send_wakeup( struct device *dev )
{
ID; printk( "Should wakeup\n" );
todo |= 1;
queue_task(&tqueue, &tq_immediate);
mark_bh(IMMEDIATE_BH);
}
static int
n2cd_rcv(struct sk_buff *skb, struct device *dev, struct packet_type *pt)
{
char *data = skb->nh.raw;
int i;
ID; printk( "Message came (%d bytes)\n", skb->len );
if (!my_tty) {
printk( "Noone is listening\n" );
return 0;
}
for (i=0; i<skb->len; i++)
receive_byte(dev, data[i]);
tty_flip_buffer_push(my_tty);
return 0;
}
static struct packet_type n2cd_packet_type =
{
__constant_htons(ETH_P_N2CD),
NULL, /* All devices */
n2cd_rcv,
NULL,
NULL,
#ifdef CONFIG_SWAP_VIA_NETWORK
1,
#endif
};
/* ------------------------- Character device interface --------------------------- */
static ssize_t n2cd_write(struct tty_struct *tty, int from_user, const unsigned char * buffer, int count)
{
int r = 0;
struct sk_buff *skb;
char *target;
ID; printk( "write %d bytes...", count );
if (from_user && (r = verify_area(VERIFY_READ, buffer, count))) {
printk( "verify area failed\n" );
return r;
}
if (count>512) /* Limit size to mtu */
count = 512;
skb = alloc_skb(3*count+50, GFP_KERNEL);
if (skb == NULL)
return 0;
skb_reserve(skb, count+25);
skb->nh.raw = skb->data;
target = (char *) skb_put(skb,count);
memcpy(target, buffer, count);
skb->dev = attached_device; /* My device - dev; */
skb->protocol = __constant_htons (ETH_P_N2CD);
dev_queue_xmit(skb);
printk( "wrote %d bytes\n", count );
return count;
}
static int n2cd_open(struct tty_struct *tty, struct file * file)
{
ID; printk( "Openning device\n" );
my_tty = tty;
#if 0
my_tty->low_latency = 1;
#endif
return 0;
}
static void n2cd_close(struct tty_struct *tty, struct file * file)
{
ID; printk( "Closing device\n" );
my_tty = NULL;
ID; printk( "net close\n" );
}
void
n2cd_attach(char *name)
{
struct device *dev;
read_lock(&dev_base_lock);
for (dev = dev_base; dev != NULL; dev = dev->next) {
if (!strcmp(dev->name, name))
break;
}
read_unlock(&dev_base_lock);
if (!dev) {
ID; printk( "attach: device not found\n" );
return;
}
printk( "attaching to device %s\n", dev->name );
attached_device = dev;
}
static int n2cd_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
{
printk( "ioctl came\n" );
if (cmd == 0xf506) {
return 0;
}
return -ENOIOCTLCMD;
}
static void n2cd_set_termios(struct tty_struct *tty, struct termios *old)
{
printk( "set termios came\n" );
}
static int n2cd_chars_in_buffer(struct tty_struct *tty)
{
return 0;
}
static void n2cd_wait_until_sent(struct tty_struct *tty, int timeout)
{
}
static struct termios n2cd_deftermios = {
0,
0,
(B9600 | CS8 | CREAD | HUPCL | CLOCAL),
0,
0,
INIT_C_CC
};
static struct tty_driver n2cd_tty = {
0,
};
static struct tty_struct *n2cd_ttys[MAXDEVS];
static struct termios *n2cd_termios[MAXDEVS];
static struct termios *n2cd_termioslocked[MAXDEVS];
static int n2cd_refcount;
#ifdef MODULE
int init_module(void)
{
printk( "n2cd: V0.1.0, copyright 1999 Pavel Machek\n" );
my_dev = kmalloc(1, GFP_KERNEL);
memset(&tqueue, 0, sizeof(tqueue));
tqueue.routine = do_softint;
tqueue.data = NULL;
n2cd_tty.magic = TTY_DRIVER_MAGIC;
n2cd_tty.name = "n2cd";
n2cd_tty.driver_name = "n2cd";
n2cd_tty.major = 63;
n2cd_tty.minor_start = 0;
n2cd_tty.num = 1;
n2cd_tty.type = TTY_DRIVER_TYPE_SERIAL;
n2cd_tty.table = n2cd_ttys;
n2cd_tty.termios = n2cd_termios;
n2cd_tty.termios_locked = n2cd_termioslocked;
n2cd_tty.refcount = &n2cd_refcount;
n2cd_tty.open = n2cd_open;
n2cd_tty.close = n2cd_close;
n2cd_tty.write = n2cd_write;
n2cd_tty.init_termios = n2cd_deftermios;
n2cd_tty.chars_in_buffer = n2cd_chars_in_buffer;
n2cd_tty.ioctl = n2cd_ioctl;
n2cd_tty.set_termios = n2cd_set_termios;
n2cd_tty.wait_until_sent = n2cd_wait_until_sent;
n2cd_attach("irda0");
if (tty_register_driver(&n2cd_tty)) {
ID; printk( "failed to register driver\n" );
}
dev_add_pack(&n2cd_packet_type);
return 0;
}
void cleanup_module(void)
{
ID; printk( "cleanup\n" );
if (tty_unregister_driver(&n2cd_tty)) {
ID; printk( "failed to unregister driver; await armagedon\n" );
}
}
#endif
-- I'm really pavel@ucw.cz. Look at http://195.113.31.123/~pavel. Pavel Hi! I'm a .signature virus! Copy me into your ~/.signature, please!- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/