sdla_x25.c

linux-2.6.15.6

/*======================================================================
 * 	Build media header.
 * 	o encapsulate packet according to encapsulation type.
 *
 * 	The trick here is to put packet type (Ethertype) into 'protocol' 
 *      field of the socket buffer, so that we don't forget it.  
 *      If encapsulation fails, set skb->protocol to 0 and discard 
 *      packet later.
 *
 * 	Return:		media header length.
 *======================================================================*/

static int if_header(struct sk_buff* skb, struct net_device* dev,
		     unsigned short type, void* daddr, void* saddr,
		     unsigned len)
{
	x25_channel_t* chan = dev->priv;
	int hdr_len = dev->hard_header_len;
	
	skb->protocol = htons(type);
	if (!chan->protocol){
		hdr_len = wanrouter_encapsulate(skb, dev, type);
		if (hdr_len < 0){
			hdr_len = 0;
			skb->protocol = htons(0);
		}
	}
	return hdr_len;
}

/*===============================================================
 * 	Re-build media header.
 *
 * 	Return:		1	physical address resolved.
 *			0	physical address not resolved
 *==============================================================*/

static int if_rebuild_hdr (struct sk_buff* skb)
{
	struct net_device *dev = skb->dev; 
	x25_channel_t* chan = dev->priv;
	sdla_t* card = chan->card;

	printk(KERN_INFO "%s: rebuild_header() called for interface %s!\n",
		card->devname, dev->name);
	return 1;
}


/*============================================================================
 * Handle transmit timeout event from netif watchdog
 */
static void if_tx_timeout(struct net_device *dev)
{
    	x25_channel_t* chan = dev->priv;
	sdla_t *card = chan->card;

	/* If our device stays busy for at least 5 seconds then we will
	 * kick start the device by making dev->tbusy = 0.  We expect
	 * that our device never stays busy more than 5 seconds. So this                 
	 * is only used as a last resort.
	 */

	++chan->if_send_stat.if_send_tbusy_timeout;
	printk (KERN_INFO "%s: Transmit timed out on %s\n", 
			card->devname, dev->name);
	netif_wake_queue (dev);
}


/*=========================================================================
 * 	Send a packet on a network interface.
 * 	o set tbusy flag (marks start of the transmission).
 * 	o check link state. If link is not up, then drop the packet.
 * 	o check channel status. If it's down then initiate a call.
 * 	o pass a packet to corresponding WAN device.
 * 	o free socket buffer
 *
 * 	Return:	0	complete (socket buffer must be freed)
 *		non-0	packet may be re-transmitted (tbusy must be set)
 *
 * 	Notes:
 * 	1. This routine is called either by the protocol stack or by the "net
 *    	bottom half" (with interrupts enabled).
 * 	2. Setting tbusy flag will inhibit further transmit requests from the
 *    	protocol stack and can be used for flow control with protocol layer.
 *
 *========================================================================*/

static int if_send(struct sk_buff* skb, struct net_device* dev)
{
	x25_channel_t* chan = dev->priv;
	sdla_t* card = chan->card;
	TX25Status* status = card->flags;
	int udp_type;
	unsigned long smp_flags=0;

	++chan->if_send_stat.if_send_entry;

	netif_stop_queue(dev);

	/* No need to check frame length, since socket code
         * will perform the check for us */

	chan->tick_counter = jiffies;
	
	/* Critical region starts here */
	S508_S514_lock(card, &smp_flags);
	
	if (test_and_set_bit(SEND_CRIT, (void*)&card->wandev.critical)){
		printk(KERN_INFO "Hit critical in if_send()! %lx\n",card->wandev.critical);
		goto if_send_crit_exit;
	}
	
	udp_type = udp_pkt_type(skb, card);

        if(udp_type != UDP_INVALID_TYPE) {

                if(store_udp_mgmt_pkt(udp_type, UDP_PKT_FRM_STACK, card, dev, skb,
                        chan->common.lcn)) {

                        status->imask |= INTR_ON_TIMER;
                        if (udp_type == UDP_XPIPE_TYPE){
                                chan->if_send_stat.if_send_PIPE_request++;
			}
               	}
		netif_start_queue(dev);
		clear_bit(SEND_CRIT,(void*)&card->wandev.critical);
		S508_S514_unlock(card, &smp_flags);
		return 0;
	}

	if (chan->transmit_length){
		//FIXME: This check doesn't make sense any more
		if (chan->common.state != WAN_CONNECTED){
			chan->transmit_length=0;
			atomic_set(&chan->common.driver_busy,0);
		}else{
			netif_stop_queue(dev);
			++card->u.x.tx_interrupts_pending;
		        status->imask |= INTR_ON_TX_FRAME;
			clear_bit(SEND_CRIT,(void*)&card->wandev.critical);
			S508_S514_unlock(card, &smp_flags);
			return 1;
		}
	}

	if (card->wandev.state != WAN_CONNECTED){
		++chan->ifstats.tx_dropped;
		++card->wandev.stats.tx_dropped;
		++chan->if_send_stat.if_send_wan_disconnected;	
		
	}else if ( chan->protocol && (chan->protocol != skb->protocol)){
		printk(KERN_INFO
			"%s: unsupported Ethertype 0x%04X on interface %s!\n",
			chan->name, htons(skb->protocol), dev->name);
		
		printk(KERN_INFO "PROTO %Xn", htons(chan->protocol));
		++chan->ifstats.tx_errors;
		++chan->ifstats.tx_dropped;
		++card->wandev.stats.tx_dropped;
		++chan->if_send_stat.if_send_protocol_error;
		
	}else switch (chan->common.state){

		case WAN_DISCONNECTED:
			/* Try to establish connection. If succeded, then start
			 * transmission, else drop a packet.
			 */
			if (chan->common.usedby == API){
				++chan->ifstats.tx_dropped;
				++card->wandev.stats.tx_dropped;
				break;
			}else{
				if (chan_connect(dev) != 0){
					++chan->ifstats.tx_dropped;
					++card->wandev.stats.tx_dropped;
					break;
				}
			}
			/* fall through */

		case WAN_CONNECTED:
			if( skb->protocol == htons(ETH_P_IPX)) {
				if(chan->enable_IPX) {
					switch_net_numbers( skb->data, 
						chan->network_number, 0);
				} else {
					++card->wandev.stats.tx_dropped;
					++chan->ifstats.tx_dropped;
					++chan->if_send_stat.if_send_protocol_error;
					goto if_send_crit_exit;
				}
			}
			/* We never drop here, if cannot send than, copy
	                 * a packet into a transmit buffer 
                         */
			chan_send(dev, skb->data, skb->len, 0);
			break;

		default:
			++chan->ifstats.tx_dropped;	
			++card->wandev.stats.tx_dropped;
			break;
	}


if_send_crit_exit:
	
       	dev_kfree_skb_any(skb);

	netif_start_queue(dev);
	clear_bit(SEND_CRIT,(void*)&card->wandev.critical);
	S508_S514_unlock(card, &smp_flags);
	return 0;
}

/*============================================================================
 * Setup so that a frame can be transmitted on the occurrence of a transmit
 * interrupt.
 *===========================================================================*/

static void setup_for_delayed_transmit(struct net_device* dev, void* buf,
				       unsigned len)
{
        x25_channel_t* chan = dev->priv;
        sdla_t* card = chan->card;
	TX25Status* status = card->flags;

	++chan->if_send_stat.if_send_adptr_bfrs_full;

        if(chan->transmit_length) {
                printk(KERN_INFO "%s: Error, transmit length set in delayed transmit!\n",
				card->devname);
                return;
        }

	if (chan->common.usedby == API){
		if (len > X25_CHAN_MTU+sizeof(x25api_hdr_t)) {
			++chan->ifstats.tx_dropped;	
			++card->wandev.stats.tx_dropped;
			printk(KERN_INFO "%s: Length is too big for delayed transmit\n",
				card->devname);
			return;
		}
	}else{
		if (len > X25_MAX_DATA) {
			++chan->ifstats.tx_dropped;	
			++card->wandev.stats.tx_dropped;
			printk(KERN_INFO "%s: Length is too big for delayed transmit\n",
				card->devname);
			return;
		}
	}

        chan->transmit_length = len;
	atomic_set(&chan->common.driver_busy,1);
        memcpy(chan->transmit_buffer, buf, len);

	++chan->if_send_stat.if_send_tx_int_enabled;

	/* Enable Transmit Interrupt */
	++card->u.x.tx_interrupts_pending;
        status->imask |= INTR_ON_TX_FRAME;
}


/*===============================================================
 * net_device_stats
 *
 * 	Get ethernet-style interface statistics.
 * 	Return a pointer to struct enet_statistics.
 *
 *==============================================================*/
static struct net_device_stats *if_stats(struct net_device* dev)
{
	x25_channel_t *chan = dev->priv;

	if(chan == NULL)
		return NULL;

	return &chan->ifstats;
}


/*
 *	Interrupt Handlers 
 */

/*
 * X.25 Interrupt Service Routine.
 */

static void wpx_isr (sdla_t* card)
{
	TX25Status* status = card->flags;

	card->in_isr = 1;
	++card->statistics.isr_entry;

	if (test_bit(PERI_CRIT,(void*)&card->wandev.critical)){
		card->in_isr=0;
		status->iflags = 0;
		return;
	}
	
	if (test_bit(SEND_CRIT, (void*)&card->wandev.critical)){

 		printk(KERN_INFO "%s: wpx_isr: wandev.critical set to 0x%02lx, int type = 0x%02x\n", 
			card->devname, card->wandev.critical, status->iflags);
		card->in_isr = 0;
		status->iflags = 0;
		return;
	}

	/* For all interrupts set the critical flag to CRITICAL_RX_INTR.
         * If the if_send routine is called with this flag set it will set
         * the enable transmit flag to 1. (for a delayed interrupt)
         */
	switch (status->iflags){

		case RX_INTR_PENDING:		/* receive interrupt */
			rx_intr(card);
			break;

		case TX_INTR_PENDING:		/* transmit interrupt */
			tx_intr(card);
			break;

		case MODEM_INTR_PENDING:	/* modem status interrupt */
			status_intr(card);
			break;

		case X25_ASY_TRANS_INTR_PENDING:	/* network event interrupt */
			event_intr(card);
			break;

		case TIMER_INTR_PENDING:
			timer_intr(card);
			break;

		default:		/* unwanted interrupt */
			spur_intr(card);
	}

	card->in_isr = 0;
	status->iflags = 0;	/* clear interrupt condition */
}

/*
 * 	Receive interrupt handler.
 * 	This routine handles fragmented IP packets using M-bit according to the
 * 	RFC1356.
 * 	o map ligical channel number to network interface.
 * 	o allocate socket buffer or append received packet to the existing one.
 * 	o if M-bit is reset (i.e. it's the last packet in a sequence) then 
 *   	decapsulate packet and pass socket buffer to the protocol stack.
 *
 * 	Notes:
 * 	1. When allocating a socket buffer, if M-bit is set then more data is
 *    	coming and we have to allocate buffer for the maximum IP packet size
 *    	expected on this channel.
 * 	2. If something goes wrong and X.25 packet has to be dropped (e.g. no
 *    	socket buffers available) the whole packet sequence must be discarded.
 */

static void rx_intr (sdla_t* card)
{
	TX25Mbox* rxmb = card->rxmb;
	unsigned lcn = rxmb->cmd.lcn;
	struct net_device* dev = find_channel(card,lcn);
	x25_channel_t* chan;
	struct sk_buff* skb=NULL;

	if (dev == NULL){
		/* Invalid channel, discard packet */
		printk(KERN_INFO "%s: receiving on orphaned LCN %d!\n",
			card->devname, lcn);
		return;
	}

	chan = dev->priv;
	chan->i_timeout_sofar = jiffies;


	/* Copy the data from the board, into an
         * skb buffer 
	 */
	if (wanpipe_pull_data_in_skb(card,dev,&skb)){
		++chan->ifstats.rx_dropped;
		++card->wandev.stats.rx_dropped;
		++chan->rx_intr_stat.rx_intr_no_socket;
		++chan->rx_intr_stat.rx_intr_bfr_not_passed_to_stack;
		return;
	}

	dev->last_rx = jiffies;		/* timestamp */


	/* ------------ API ----------------*/

	if (chan->common.usedby == API){

		if (bh_enqueue(dev, skb)){
			++chan->ifstats.rx_dropped;
			++card->wandev.stats.rx_dropped;
			++chan->rx_intr_stat.rx_intr_bfr_not_passed_to_stack;
			dev_kfree_skb_any(skb);
			return;
		}		

		++chan->ifstats.rx_packets;
		chan->ifstats.rx_bytes += skb->len;
		

		chan->rx_skb = NULL;
		if (!test_and_set_bit(0, &chan->tq_working)){
			wanpipe_queue_work(&chan->common.wanpipe_work);
		}
		return;
	}


	/* ------------- WANPIPE -------------------*/
	
	/* set rx_skb to NULL so we won't access it later when kernel already owns it */
	chan->rx_skb=NULL;
	
	/* Decapsulate packet, if necessary */
	if (!skb->protocol && !wanrouter_type_trans(skb, dev)){
		/* can't decapsulate packet */
                dev_kfree_skb_any(skb);
		++chan->ifstats.rx_errors;
		++chan->ifstats.rx_dropped;
		++card->wandev.stats.rx_dropped;
		++chan->rx_intr_stat.rx_intr_bfr_not_passed_to_stack;

	}else{