path: root/drivers/net/wan/x25_asy.c

/*
 *	Things to sort out:
 *
 *	o	tbusy handling
 *	o	allow users to set the parameters
 *	o	sync/async switching ?
 *
 *	Note: This does _not_ implement CCITT X.25 asynchronous framing
 *	recommendations. Its primarily for testing purposes. If you wanted
 *	to do CCITT then in theory all you need is to nick the HDLC async
 *	checksum routines from ppp.c
 *      Changes:
 *
 *	2000-10-29	Henner Eisen	lapb_data_indication() return status.
 */

#include <linux/module.h>

#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/bitops.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/x25.h>
#include <linux/lapb.h>
#include <linux/init.h>
#include "x25_asy.h"

#include <net/x25device.h>

static struct net_device **x25_asy_devs;
static int x25_asy_maxdev = SL_NRUNIT;

module_param(x25_asy_maxdev, int, 0);
MODULE_LICENSE("GPL");

static int x25_asy_esc(unsigned char *p, unsigned char *d, int len);
static void x25_asy_unesc(struct x25_asy *sl, unsigned char c);
static void x25_asy_setup(struct net_device *dev);

/* Find a free X.25 channel, and link in this `tty' line. */
static struct x25_asy *x25_asy_alloc(void)
{
	struct net_device *dev = NULL;
	struct x25_asy *sl;
	int i;

	if (x25_asy_devs == NULL)
		return NULL;	/* Master array missing ! */

	for (i = 0; i < x25_asy_maxdev; i++) {
		dev = x25_asy_devs[i];

		/* Not allocated ? */
		if (dev == NULL)
			break;

		sl = dev->priv;
		/* Not in use ? */
		if (!test_and_set_bit(SLF_INUSE, &sl->flags))
			return sl;
	}


	/* Sorry, too many, all slots in use */
	if (i >= x25_asy_maxdev)
		return NULL;

	/* If no channels are available, allocate one */
	if (!dev) {
		char name[IFNAMSIZ];
		sprintf(name, "x25asy%d", i);

		dev = alloc_netdev(sizeof(struct x25_asy),
				   name, x25_asy_setup);
		if (!dev)
			return NULL;

		/* Initialize channel control data */
		sl = dev->priv;
		dev->base_addr    = i;

		/* register device so that it can be ifconfig'ed       */
		if (register_netdev(dev) == 0) {
			/* (Re-)Set the INUSE bit.   Very Important! */
			set_bit(SLF_INUSE, &sl->flags);
			x25_asy_devs[i] = dev;
			return sl;
		} else {
			printk("x25_asy_alloc() - register_netdev() failure.\n");
			free_netdev(dev);
		}
	}
	return NULL;
}


/* Free an X.25 channel. */
static void x25_asy_free(struct x25_asy *sl)
{
	/* Free all X.25 frame buffers. */
	if (sl->rbuff)  {
		kfree(sl->rbuff);
	}
	sl->rbuff = NULL;
	if (sl->xbuff)  {
		kfree(sl->xbuff);
	}
	sl->xbuff = NULL;

	if (!test_and_clear_bit(SLF_INUSE, &sl->flags)) {
		printk("%s: x25_asy_free for already free unit.\n", sl->dev->name);
	}
}

static int x25_asy_change_mtu(struct net_device *dev, int newmtu)
{
	struct x25_asy *sl = dev->priv;
	unsigned char *xbuff, *rbuff;
	int len = 2* newmtu;

	xbuff = (unsigned char *) kmalloc (len + 4, GFP_ATOMIC);
	rbuff = (unsigned char *) kmalloc (len + 4, GFP_ATOMIC);

	if (xbuff == NULL || rbuff == NULL)  
	{
		printk("%s: unable to grow X.25 buffers, MTU change cancelled.\n",
		       dev->name);
		if (xbuff != NULL)  
			kfree(xbuff);
		if (rbuff != NULL)  
			kfree(rbuff);
		return -ENOMEM;
	}

	spin_lock_bh(&sl->lock);
	xbuff    = xchg(&sl->xbuff, xbuff);
	if (sl->xleft)  {
		if (sl->xleft <= len)  {
			memcpy(sl->xbuff, sl->xhead, sl->xleft);
		} else  {
			sl->xleft = 0;
			sl->stats.tx_dropped++;
		}
	}
	sl->xhead = sl->xbuff;

	rbuff	 = xchg(&sl->rbuff, rbuff);
	if (sl->rcount)  {
		if (sl->rcount <= len) {
			memcpy(sl->rbuff, rbuff, sl->rcount);
		} else  {
			sl->rcount = 0;
			sl->stats.rx_over_errors++;
			set_bit(SLF_ERROR, &sl->flags);
		}
	}

	dev->mtu    = newmtu;
	sl->buffsize = len;

	spin_unlock_bh(&sl->lock);

	if (xbuff != NULL) 
		kfree(xbuff);
	if (rbuff != NULL)
		kfree(rbuff);
	return 0;
}


/* Set the "sending" flag.  This must be atomic, hence the ASM. */

static inline void x25_asy_lock(struct x25_asy *sl)
{
	netif_stop_queue(sl->dev