plip.c

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				return TIMEOUT;
			}
			c0 = read_status(dev);
			printk(KERN_WARNING "%s: transmit timeout(%d,%02x)\n",
			       dev->name, snd->state, c0);
		} else
			error = HS_TIMEOUT;
		nl->enet_stats.tx_errors++;
		nl->enet_stats.tx_aborted_errors++;
	} else if (nl->connection == PLIP_CN_RECEIVE) {
		if (rcv->state == PLIP_PK_TRIGGER) {
			/* Transmission was interrupted. */
			spin_unlock_irq(&nl->lock);
			return OK;
		}
		if (error != ERROR) { /* Timeout */
			if (++nl->timeout_count <= 3) {
				spin_unlock_irq(&nl->lock);
				/* Try again later */
				return TIMEOUT;
			}
			c0 = read_status(dev);
			printk(KERN_WARNING "%s: receive timeout(%d,%02x)\n",
			       dev->name, rcv->state, c0);
		}
		nl->enet_stats.rx_dropped++;
	}
	rcv->state = PLIP_PK_DONE;
	if (rcv->skb) {
		kfree_skb(rcv->skb);
		rcv->skb = NULL;
	}
	snd->state = PLIP_PK_DONE;
	if (snd->skb) {
		dev_kfree_skb(snd->skb);
		snd->skb = NULL;
	}
	spin_unlock_irq(&nl->lock);
	if (error == HS_TIMEOUT) {
		DISABLE(dev->irq);
		synchronize_irq();
	}
	disable_parport_interrupts (dev);
	netif_stop_queue (dev);
	nl->connection = PLIP_CN_ERROR;
	write_data (dev, 0x00);

	return TIMEOUT;
}

static int
plip_none(struct net_device *dev, struct net_local *nl,
	  struct plip_local *snd, struct plip_local *rcv)
{
	return OK;
}

/* PLIP_RECEIVE --- receive a byte(two nibbles)
   Returns OK on success, TIMEOUT on timeout */
inline static int
plip_receive(unsigned short nibble_timeout, struct net_device *dev,
	     enum plip_nibble_state *ns_p, unsigned char *data_p)
{
	unsigned char c0, c1;
	unsigned int cx;

	switch (*ns_p) {
	case PLIP_NB_BEGIN:
		cx = nibble_timeout;
		while (1) {
			c0 = read_status(dev);
			udelay(PLIP_DELAY_UNIT);
			if ((c0 & 0x80) == 0) {
				c1 = read_status(dev);
				if (c0 == c1)
					break;
			}
			if (--cx == 0)
				return TIMEOUT;
		}
		*data_p = (c0 >> 3) & 0x0f;
		write_data (dev, 0x10); /* send ACK */
		*ns_p = PLIP_NB_1;

	case PLIP_NB_1:
		cx = nibble_timeout;
		while (1) {
			c0 = read_status(dev);
			udelay(PLIP_DELAY_UNIT);
			if (c0 & 0x80) {
				c1 = read_status(dev);
				if (c0 == c1)
					break;
			}
			if (--cx == 0)
				return TIMEOUT;
		}
		*data_p |= (c0 << 1) & 0xf0;
		write_data (dev, 0x00); /* send ACK */
		*ns_p = PLIP_NB_BEGIN;
	case PLIP_NB_2:
		break;
	}
	return OK;
}

/*
 *	Determine the packet's protocol ID. The rule here is that we 
 *	assume 802.3 if the type field is short enough to be a length.
 *	This is normal practice and works for any 'now in use' protocol.
 *
 *	PLIP is ethernet ish but the daddr might not be valid if unicast.
 *	PLIP fortunately has no bus architecture (its Point-to-point).
 *
 *	We can't fix the daddr thing as that quirk (more bug) is embedded
 *	in far too many old systems not all even running Linux.
 */
 
static unsigned short plip_type_trans(struct sk_buff *skb, struct net_device *dev)
{
	struct ethhdr *eth;
	unsigned char *rawp;
	
	skb->mac.raw=skb->data;
	skb_pull(skb,dev->hard_header_len);
	eth= skb->mac.ethernet;
	
	if(*eth->h_dest&1)
	{
		if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
			skb->pkt_type=PACKET_BROADCAST;
		else
			skb->pkt_type=PACKET_MULTICAST;
	}
	
	/*
	 *	This ALLMULTI check should be redundant by 1.4
	 *	so don't forget to remove it.
	 */
	 
	if (ntohs(eth->h_proto) >= 1536)
		return eth->h_proto;
		
	rawp = skb->data;
	
	/*
	 *	This is a magic hack to spot IPX packets. Older Novell breaks
	 *	the protocol design and runs IPX over 802.3 without an 802.2 LLC
	 *	layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
	 *	won't work for fault tolerant netware but does for the rest.
	 */
	if (*(unsigned short *)rawp == 0xFFFF)
		return htons(ETH_P_802_3);
		
	/*
	 *	Real 802.2 LLC
	 */
	return htons(ETH_P_802_2);
}


/* PLIP_RECEIVE_PACKET --- receive a packet */
static int
plip_receive_packet(struct net_device *dev, struct net_local *nl,
		    struct plip_local *snd, struct plip_local *rcv)
{
	unsigned short nibble_timeout = nl->nibble;
	unsigned char *lbuf;

	switch (rcv->state) {
	case PLIP_PK_TRIGGER:
		DISABLE(dev->irq);
		/* Don't need to synchronize irq, as we can safely ignore it */
		disable_parport_interrupts (dev);
		write_data (dev, 0x01); /* send ACK */
		if (net_debug > 2)
			printk(KERN_DEBUG "%s: receive start\n", dev->name);
		rcv->state = PLIP_PK_LENGTH_LSB;
		rcv->nibble = PLIP_NB_BEGIN;

	case PLIP_PK_LENGTH_LSB:
		if (snd->state != PLIP_PK_DONE) {
			if (plip_receive(nl->trigger, dev,
					 &rcv->nibble, &rcv->length.b.lsb)) {
				/* collision, here dev->tbusy == 1 */
				rcv->state = PLIP_PK_DONE;
				nl->is_deferred = 1;
				nl->connection = PLIP_CN_SEND;
				queue_task(&nl->deferred, &tq_timer);
				enable_parport_interrupts (dev);
				ENABLE(dev->irq);
				return OK;
			}
		} else {
			if (plip_receive(nibble_timeout, dev,
					 &rcv->nibble, &rcv->length.b.lsb))
				return TIMEOUT;
		}
		rcv->state = PLIP_PK_LENGTH_MSB;

	case PLIP_PK_LENGTH_MSB:
		if (plip_receive(nibble_timeout, dev,
				 &rcv->nibble, &rcv->length.b.msb))
			return TIMEOUT;
		if (rcv->length.h > dev->mtu + dev->hard_header_len
		    || rcv->length.h < 8) {
			printk(KERN_WARNING "%s: bogus packet size %d.\n", dev->name, rcv->length.h);
			return ERROR;
		}
		/* Malloc up new buffer. */
		rcv->skb = dev_alloc_skb(rcv->length.h + 2);
		if (rcv->skb == NULL) {
			printk(KERN_ERR "%s: Memory squeeze.\n", dev->name);
			return ERROR;
		}
		skb_reserve(rcv->skb, 2);	/* Align IP on 16 byte boundaries */
		skb_put(rcv->skb,rcv->length.h);
		rcv->skb->dev = dev;
		rcv->state = PLIP_PK_DATA;
		rcv->byte = 0;
		rcv->checksum = 0;

	case PLIP_PK_DATA:
		lbuf = rcv->skb->data;
		do
			if (plip_receive(nibble_timeout, dev,
					 &rcv->nibble, &lbuf[rcv->byte]))
				return TIMEOUT;
		while (++rcv->byte < rcv->length.h);
		do
			rcv->checksum += lbuf[--rcv->byte];
		while (rcv->byte);
		rcv->state = PLIP_PK_CHECKSUM;

	case PLIP_PK_CHECKSUM:
		if (plip_receive(nibble_timeout, dev,
				 &rcv->nibble, &rcv->data))
			return TIMEOUT;
		if (rcv->data != rcv->checksum) {
			nl->enet_stats.rx_crc_errors++;
			if (net_debug)
				printk(KERN_DEBUG "%s: checksum error\n", dev->name);
			return ERROR;
		}
		rcv->state = PLIP_PK_DONE;

	case PLIP_PK_DONE:
		/* Inform the upper layer for the arrival of a packet. */
		rcv->skb->protocol=plip_type_trans(rcv->skb, dev);
		netif_rx(rcv->skb);
		nl->enet_stats.rx_bytes += rcv->length.h;
		nl->enet_stats.rx_packets++;
		rcv->skb = NULL;
		if (net_debug > 2)
			printk(KERN_DEBUG "%s: receive end\n", dev->name);

		/* Close the connection. */
		write_data (dev, 0x00);
		spin_lock_irq(&nl->lock);
		if (snd->state != PLIP_PK_DONE) {
			nl->connection = PLIP_CN_SEND;
			spin_unlock_irq(&nl->lock);
			queue_task(&nl->immediate, &tq_immediate);
			mark_bh(IMMEDIATE_BH);
			enable_parport_interrupts (dev);
			ENABLE(dev->irq);
			return OK;
		} else {
			nl->connection = PLIP_CN_NONE;
			spin_unlock_irq(&nl->lock);
			enable_parport_interrupts (dev);
			ENABLE(dev->irq);
			return OK;
		}
	}
	return OK;
}

/* PLIP_SEND --- send a byte (two nibbles)
   Returns OK on success, TIMEOUT when timeout    */
inline static int
plip_send(unsigned short nibble_timeout, struct net_device *dev,
	  enum plip_nibble_state *ns_p, unsigned char data)
{
	unsigned char c0;
	unsigned int cx;

	switch (*ns_p) {
	case PLIP_NB_BEGIN:
		write_data (dev, data & 0x0f);
		*ns_p = PLIP_NB_1;

	case PLIP_NB_1:
		write_data (dev, 0x10 | (data & 0x0f));
		cx = nibble_timeout;
		while (1) {
			c0 = read_status(dev);
			if ((c0 & 0x80) == 0)
				break;
			if (--cx == 0)
				return TIMEOUT;
			udelay(PLIP_DELAY_UNIT);
		}
		write_data (dev, 0x10 | (data >> 4));
		*ns_p = PLIP_NB_2;

	case PLIP_NB_2:
		write_data (dev, (data >> 4));
		cx = nibble_timeout;
		while (1) {
			c0 = read_status(dev);
			if (c0 & 0x80)
				break;
			if (--cx == 0)
				return TIMEOUT;
			udelay(PLIP_DELAY_UNIT);
		}
		*ns_p = PLIP_NB_BEGIN;
		return OK;
	}
	return OK;
}

/* PLIP_SEND_PACKET --- send a packet */
static int
plip_send_packet(struct net_device *dev, struct net_local *nl,
		 struct plip_local *snd, struct plip_local *rcv)
{
	unsigned short nibble_timeout = nl->nibble;
	unsigned char *lbuf;
	unsigned char c0;
	unsigned int cx;

	if (snd->skb == NULL || (lbuf = snd->skb->data) == NULL) {
		printk(KERN_DEBUG "%s: send skb lost\n", dev->name);
		snd->state = PLIP_PK_DONE;
		snd->skb = NULL;
		return ERROR;
	}

	switch (snd->state) {
	case PLIP_PK_TRIGGER:
		if ((read_status(dev) & 0xf8) != 0x80)
			return HS_TIMEOUT;

		/* Trigger remote rx interrupt. */
		write_data (dev, 0x08);
		cx = nl->trigger;
		while (1) {
			udelay(PLIP_DELAY_UNIT);
			spin_lock_irq(&nl->lock);
			if (nl->connection == PLIP_CN_RECEIVE) {
				spin_unlock_irq(&nl->lock);
				/* Interrupted. */
				nl->enet_stats.collisions++;
				return OK;
			}
			c0 = read_status(dev);
			if (c0 & 0x08) {
				spin_unlock_irq(&nl->lock);
				DISABLE(dev->irq);
				synchronize_irq();
				if (nl->connection == PLIP_CN_RECEIVE) {
					/* Interrupted.
					   We don't need to enable irq,
					   as it is soon disabled.    */
					/* Yes, we do. New variant of
					   {enable,disable}_irq *counts*
					   them.  -- AV  */
					ENABLE(dev->irq);
					nl->enet_stats.collisions++;
					return OK;
				}
				disable_parport_interrupts (dev);
				if (net_debug > 2)
					printk(KERN_DEBUG "%s: send start\n", dev->name);
				snd->state = PLIP_PK_LENGTH_LSB;
				snd->nibble = PLIP_NB_BEGIN;
				nl->timeout_count = 0;
				break;
			}
			spin_unlock_irq(&nl->lock);
			if (--cx == 0) {
				write_data (dev, 0x00);
				return HS_TIMEOUT;
			}
		}

	case PLIP_PK_LENGTH_LSB:
		if (plip_send(nibble_timeout, dev,
			      &snd->nibble, snd->length.b.lsb))
			return TIMEOUT;
		snd->state = PLIP_PK_LENGTH_MSB;

	case PLIP_PK_LENGTH_MSB:
		if (plip_send(nibble_timeout, dev,
			      &snd->nibble, snd->length.b.msb))
			return TIMEOUT;
		snd->state = PLIP_PK_DATA;
		snd->byte = 0;
		snd->checksum = 0;

	case PLIP_PK_DATA:
		do
			if (plip_send(nibble_timeout, dev,
				      &snd->nibble, lbuf[snd->byte]))
				return TIMEOUT;
		while (++snd->byte < snd->length.h);
		do
			snd->checksum += lbuf[--snd->byte];
		while (snd->byte);
		snd->state = PLIP_PK_CHECKSUM;

	case PLIP_PK_CHECKSUM:
		if (plip_send(nibble_timeout, dev,
			      &snd->nibble, snd->checksum))
			return TIMEOUT;

		nl->enet_stats.tx_bytes += snd->skb->len;
		dev_kfree_skb(snd->skb);
		nl->enet_stats.tx_packets++;
		snd->state = PLIP_PK_DONE;

	case PLIP_PK_DONE:
		/* Close the connection */
		write_data (dev, 0x00);
		snd->skb = NULL;
		if (net_debug > 2)
			printk(KERN_DEBUG "%s: send end\n", dev->name);
		nl->connection = PLIP_CN_CLOSING;
		nl->is_deferred = 1;
		queue_task(&nl->deferred, &tq_timer);
		enable_parport_interrupts (dev);
		ENABLE(dev->irq);
		return OK;
	}
	return OK;
}

static int
plip_connection_close(struct net_device *dev, struct net_local *nl,
		      struct plip_local *snd, struct plip_local *rcv)
{
	spin_lock_irq(&nl->lock);
	if (nl->connection == PLIP_CN_CLOSING) {
		nl->connection = PLIP_CN_NONE;
		netif_wake_queue (dev);
	}
	spin_unlock_irq(&nl->lock);
	if (nl->should_relinquish) {
		nl->should_relinquish = nl->port_owner = 0;
		parport_release(nl->pardev);
	}
	return OK;
}

/* PLIP_ERROR --- wait till other end settled */
static int
plip_error(struct net_device *dev, struct net_local *nl,
	   struct plip_local *snd, struct plip_local *rcv)
{
	unsigned char status;

	status = read_status(dev);
	if ((status & 0xf8) == 0x80) {
		if (net_debug > 2)
			printk(KERN_DEBUG "%s: reset interface.\n", dev->name);
		nl->connection = PLIP_CN_NONE;
		nl->should_relinquish = 0;
		netif_start_queue (dev);
		enable_parport_interrupts (dev);
		ENABLE(dev->irq);
		netif_wake_queue (dev);
	} else {
		nl->is_deferred = 1;
		queue_task(&nl->deferred, &tq_timer);
	}

	return OK;
}