count--;		if (fp && *fp++) {			if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))				sp->stats.rx_errors++;			continue;		}	}	sixpack_decode(sp, buf, count1);}/* * Open the high-level part of the 6pack channel. * This function is called by the TTY module when the * 6pack line discipline is called for.  Because we are * sure the tty line exists, we only have to link it to * a free 6pcack channel... */static int sixpack_open(struct tty_struct *tty){	struct sixpack *sp = (struct sixpack *) tty->disc_data;	int err;	/* First make sure we're not already connected. */	if (sp && sp->magic == SIXPACK_MAGIC)		return -EEXIST;	/* OK.  Find a free 6pack channel to use. */	if ((sp = sp_alloc()) == NULL)		return -ENFILE;	sp->tty = tty;	tty->disc_data = sp;	if (tty->driver.flush_buffer)		tty->driver.flush_buffer(tty);	if (tty->ldisc.flush_buffer)		tty->ldisc.flush_buffer(tty);	/* Restore default settings */	sp->dev->type = ARPHRD_AX25;	/* Perform the low-level 6pack initialization. */	if ((err = sp_open(sp->dev)))		return err;	/* Done.  We have linked the TTY line to a channel. */	tnc_init(sp);	return sp->dev->base_addr;}/* * Close down a 6pack channel. * This means flushing out any pending queues, and then restoring the * TTY line discipline to what it was before it got hooked to 6pack * (which usually is TTY again). */static void sixpack_close(struct tty_struct *tty){	struct sixpack *sp = (struct sixpack *) tty->disc_data;	/* First make sure we're connected. */	if (!sp || sp->magic != SIXPACK_MAGIC)		return;	rtnl_lock();	dev_close(sp->dev);	del_timer(&sp->tx_t);	del_timer(&sp->resync_t);	tty->disc_data = 0;	sp->tty = NULL;	sp_free(sp);	unregister_netdevice(sp->dev);	rtnl_unlock();}static struct net_device_stats *sp_get_stats(struct net_device *dev){	struct sixpack *sp = (struct sixpack *) dev->priv;	return &sp->stats;}static int sp_set_mac_address(struct net_device *dev, void *addr){	return copy_from_user(dev->dev_addr, addr, AX25_ADDR_LEN) ? -EFAULT : 0;}static int sp_set_dev_mac_address(struct net_device *dev, void *addr){	struct sockaddr *sa = addr;	memcpy(dev->dev_addr, sa->sa_data, AX25_ADDR_LEN);	return 0;}/* Perform I/O control on an active 6pack channel. */static int sixpack_ioctl(struct tty_struct *tty, void *file, int cmd, void *arg){	struct sixpack *sp = (struct sixpack *) tty->disc_data;	unsigned int tmp;	/* First make sure we're connected. */	if (!sp || sp->magic != SIXPACK_MAGIC)		return -EINVAL;	switch(cmd) {	case SIOCGIFNAME:		return copy_to_user(arg, sp->dev->name, strlen(sp->dev->name) + 1) ? -EFAULT : 0;	case SIOCGIFENCAP:		return put_user(0, (int *)arg);	case SIOCSIFENCAP:		if (get_user(tmp, (int *) arg))			return -EFAULT;		sp->mode = tmp;		sp->dev->addr_len        = AX25_ADDR_LEN;	  /* sizeof an AX.25 addr */		sp->dev->hard_header_len = AX25_KISS_HEADER_LEN + AX25_MAX_HEADER_LEN + 3;		sp->dev->type            = ARPHRD_AX25;		return 0;	 case SIOCSIFHWADDR:		return sp_set_mac_address(sp->dev, arg);	/* Allow stty to read, but not set, the serial port */	case TCGETS:	case TCGETA:		return n_tty_ioctl(tty, (struct file *) file, cmd, (unsigned long) arg);	default:		return -ENOIOCTLCMD;	}}static int sp_open_dev(struct net_device *dev){	struct sixpack *sp = (struct sixpack *) dev->priv;	if (sp->tty == NULL)		return -ENODEV;	return 0;}/* Fill in our line protocol discipline */static struct tty_ldisc sp_ldisc = {	magic:		TTY_LDISC_MAGIC,	name:		"6pack",	open:		sixpack_open,	close:		sixpack_close,	ioctl:		(int (*)(struct tty_struct *, struct file *,			unsigned int, unsigned long)) sixpack_ioctl,	receive_buf:	sixpack_receive_buf,	receive_room:	sixpack_receive_room,	write_wakeup:	sixpack_write_wakeup,};/* Initialize 6pack control device -- register 6pack line discipline */static char msg_banner[]  __initdata = KERN_INFO "AX.25: 6pack driver, " SIXPACK_VERSION " (dynamic channels, max=%d)\n";static char msg_nomem[]   __initdata = KERN_ERR  "6pack: can't allocate sixpack_ctrls[] array! No 6pack available.\n";static char msg_regfail[] __initdata = KERN_ERR  "6pack: can't register line discipline (err = %d)\n";static int __init sixpack_init_driver(void){	int status;	/* Do sanity checks on maximum device parameter. */	if (sixpack_maxdev < 4)		sixpack_maxdev = 4;	printk(msg_banner, sixpack_maxdev);	sixpack_ctrls = (sixpack_ctrl_t **) kmalloc(sizeof(void*)*sixpack_maxdev, GFP_KERNEL);	if (sixpack_ctrls == NULL) {		printk(msg_nomem);		return -ENOMEM;	}	/* Clear the pointer array, we allocate devices when we need them */	memset(sixpack_ctrls, 0, sizeof(void*)*sixpack_maxdev); /* Pointers */	/* Register the provided line protocol discipline */	if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0) {		printk(msg_regfail, status);		kfree(sixpack_ctrls);	}	return status;}static const char msg_unregfail[] __exitdata = KERN_ERR "6pack: can't unregister line discipline (err = %d)\n";static void __exit sixpack_exit_driver(void){	int i;	if ((i = tty_register_ldisc(N_6PACK, NULL)))		printk(msg_unregfail, i);	for (i = 0; i < sixpack_maxdev; i++) {		if (sixpack_ctrls[i]) {			/*			* VSV = if dev->start==0, then device			* unregistered while close proc.			*/			if (netif_running(&sixpack_ctrls[i]->dev))				 unregister_netdev(&sixpack_ctrls[i]->dev);			kfree(sixpack_ctrls[i]);		}	}	kfree(sixpack_ctrls);}/* Initialize the 6pack driver.  Called by DDI. */static int sixpack_init(struct net_device *dev){	struct sixpack *sp = (struct sixpack *) dev->priv;	static char ax25_bcast[AX25_ADDR_LEN] =		{'Q'<<1,'S'<<1,'T'<<1,' '<<1,' '<<1,' '<<1,'0'<<1};	static char ax25_test[AX25_ADDR_LEN] =		{'L'<<1,'I'<<1,'N'<<1,'U'<<1,'X'<<1,' '<<1,'1'<<1};	if (sp == NULL)		/* Allocation failed ?? */		return -ENODEV;	/* Set up the "6pack Control Block". (And clear statistics) */	memset(sp, 0, sizeof (struct sixpack));	sp->magic  = SIXPACK_MAGIC;	sp->dev	   = dev;	/* Finish setting up the DEVICE info. */	dev->mtu		= SIXP_MTU;	dev->hard_start_xmit	= sp_xmit;	dev->open		= sp_open_dev;	dev->stop		= sp_close;	dev->hard_header	= sp_header;	dev->get_stats	        = sp_get_stats;	dev->set_mac_address    = sp_set_dev_mac_address;	dev->hard_header_len	= AX25_MAX_HEADER_LEN;	dev->addr_len		= AX25_ADDR_LEN;	dev->type		= ARPHRD_AX25;	dev->tx_queue_len	= 10;	dev->rebuild_header	= sp_rebuild_header;	dev->tx_timeout		= NULL;	memcpy(dev->broadcast, ax25_bcast, AX25_ADDR_LEN);	/* Only activated in AX.25 mode */	memcpy(dev->dev_addr, ax25_test, AX25_ADDR_LEN);	/*    ""      ""       ""    "" */	/* New-style flags. */	dev->flags		= 0;	return 0;}/* ----> 6pack timer interrupt handler and friends. <---- */static void sp_start_tx_timer(struct sixpack *sp){	int when = sp->slottime;	del_timer(&sp->tx_t);	sp->tx_t.data = (unsigned long) sp;	sp->tx_t.function = sp_xmit_on_air;	sp->tx_t.expires = jiffies + ((when+1)*HZ)/100;	add_timer(&sp->tx_t);}/* encode an AX.25 packet into 6pack */static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw, int length, unsigned char tx_delay){	int count = 0;	unsigned char checksum = 0, buf[400];	int raw_count = 0;	tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;	tx_buf_raw[raw_count++] = SIXP_SEOF;	buf[0] = tx_delay;	for (count = 1; count < length; count++)		buf[count] = tx_buf[count];	for (count = 0; count < length; count++)		checksum += buf[count];	buf[length] = (unsigned char) 0xff - checksum;	for (count = 0; count <= length; count++) {		if ((count % 3) == 0) {			tx_buf_raw[raw_count++] = (buf[count] & 0x3f);			tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);		} else if ((count % 3) == 1) {			tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);			tx_buf_raw[raw_count] =	((buf[count] >> 2) & 0x3c);		} else {			tx_buf_raw[raw_count++] |= (buf[count] & 0x03);			tx_buf_raw[raw_count++] = (buf[count] >> 2);		}	}	if ((length % 3) != 2)		raw_count++;	tx_buf_raw[raw_count++] = SIXP_SEOF;	return raw_count;}/* decode a 6pack packet */static voidsixpack_decode(struct sixpack *sp, unsigned char pre_rbuff[], int count){	unsigned char inbyte;	int count1;	for (count1 = 0; count1 < count; count1++) {		inbyte = pre_rbuff[count1];		if (inbyte == SIXP_FOUND_TNC) {			printk(KERN_INFO "6pack: TNC found.\n");			sp->tnc_ok = 1;			del_timer(&sp->resync_t);		}		if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)			decode_prio_command(inbyte, sp);		else if ((inbyte & SIXP_STD_CMD_MASK) != 0)			decode_std_command(inbyte, sp);		else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)			decode_data(inbyte, sp);	}}static int tnc_init(struct sixpack *sp){	unsigned char inbyte = 0xe8;	sp->tty->driver.write(sp->tty, 0, &inbyte, 1);	del_timer(&sp->resync_t);	sp->resync_t.data = (unsigned long) sp;	sp->resync_t.function = resync_tnc;	sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;	add_timer(&sp->resync_t);	return 0;}/* identify and execute a 6pack priority command byte */static void decode_prio_command(unsigned char cmd, struct sixpack *sp){	unsigned char channel;	int actual;	channel = cmd & SIXP_CHN_MASK;	if ((cmd & SIXP_PRIO_DATA_MASK) != 0) {     /* idle ? */	/* RX and DCD flags can only be set in the same prio command,	   if the DCD flag has been set without the RX flag in the previous	   prio command. If DCD has not been set before, something in the	   transmission has gone wrong. In this case, RX and DCD are	   cleared in order to prevent the decode_data routine from	   reading further data that might be corrupt. */		if (((sp->status & SIXP_DCD_MASK) == 0) &&			((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {				if (sp->status != 1)					printk(KERN_DEBUG "6pack: protocol violation\n");				else					sp->status = 0;				cmd &= !SIXP_RX_DCD_MASK;		}		sp->status = cmd & SIXP_PRIO_DATA_MASK;	}	else { /* output watchdog char if idle */		if ((sp->status2 != 0) && (sp->duplex == 1)) {			sp->led_state = 0x70;			sp->tty->driver.write(sp->tty, 0, &sp->led_state, 1);			sp->tx_enable = 1;			actual = sp->tty->driver.write(sp->tty, 0, sp->xbuff, sp->status2);			sp->xleft -= actual;			sp->xhead += actual;			sp->led_state = 0x60;			sp->status2 = 0;		}	}	/* needed to trigger the TNC watchdog */	sp->tty->driver.write(sp->tty, 0, &sp->led_state, 1);        /* if the state byte has been received, the TNC is present,           so the resync timer can be reset. */	if (sp->tnc_ok == 1) {		del_timer(&sp->resync_t);		sp->resync_t.data = (unsigned long) sp;		sp->resync_t.function = resync_tnc;		sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;		add_timer(&sp->resync_t);	}	sp->status1 = cmd & SIXP_PRIO_DATA_MASK;}/* try to resync the TNC. Called by the resync timer defined in  decode_prio_command */static void resync_tnc(unsigned long channel){	static char resync_cmd = 0xe8;	struct sixpack *sp = (struct sixpack *) channel;	printk(KERN_INFO "6pack: resyncing TNC\n");	/* clear any data that might have been received */	sp->rx_count = 0;	sp->rx_count_cooked = 0;	/* reset state machine */	sp->status = 1;	sp->status1 = 1;	sp->status2 = 0;	sp->tnc_ok = 0;	/* resync the TNC */	sp->led_state = 0x60;	sp->tty->driver.write(sp->tty, 0, &sp->led_state, 1);	sp->tty->driver.write(sp->tty, 0, &resync_cmd, 1);	/* Start resync timer again -- the TNC might be still absent */	del_timer(&sp->resync_t);	sp->resync_t.data = (unsigned long) sp;	sp->resync_t.function = resync_tnc;	sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;	add_timer(&sp->resync_t);}/* identify and execute a standard 6pack command byte */static void decode_std_command(unsigned char cmd, struct sixpack *sp){	unsigned char checksum = 0, rest = 0, channel;	short i;	channel = cmd & SIXP_CHN_MASK;	switch (cmd & SIXP_CMD_MASK) {     /* normal command */		case SIXP_SEOF:			if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {				if ((sp->status & SIXP_RX_DCD_MASK) ==					SIXP_RX_DCD_MASK) {					sp->led_state = 0x68;					sp->tty->driver.write(sp->tty, 0, &sp->led_state, 1);				}			} else {				sp->led_state = 0x60;				/* fill trailing bytes with zeroes */				sp->tty->driver.write(sp->tty, 0, &sp->led_state, 1);				rest = sp->rx_count;				if (rest != 0)					 for (i = rest; i <= 3; i++)						decode_data(0, sp);				if (rest == 2)					sp->rx_count_cooked -= 2;				else if (rest == 3)					sp->rx_count_cooked -= 1;				for (i = 0; i < sp->rx_count_cooked; i++)					checksum += sp->cooked_buf[i];				if (checksum != SIXP_CHKSUM) {					printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);				} else {					sp->rcount = sp->rx_count_cooked-2;					sp_bump(sp, 0);				}				sp->rx_count_cooked = 0;			}			break;		case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");			break;		case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");			break;		case SIXP_RX_BUF_OVL:			printk(KERN_DEBUG "6pack: RX buffer overflow\n");	}}/* decode 4 sixpack-encoded bytes into 3 data bytes */static void decode_data(unsigned char inbyte, struct sixpack *sp){	unsigned char *buf;	if (sp->rx_count != 3)		sp->raw_buf[sp->rx_count++] = inbyte;	else {		buf = sp->raw_buf;		sp->cooked_buf[sp->rx_count_cooked++] =			buf[0] | ((buf[1] << 2) & 0xc0);		sp->cooked_buf[sp->rx_count_cooked++] =			(buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);		sp->cooked_buf[sp->rx_count_cooked++] =			(buf[2] & 0x03) | (inbyte << 2);		sp->rx_count = 0;	}}MODULE_AUTHOR("Andreas K鰊sgen <ajk@ccac.rwth-aachen.de>");MODULE_DESCRIPTION("6pack driver for AX.25");MODULE_LICENSE("GPL");module_init(sixpack_init_driver);module_exit(sixpack_exit_driver);