3c501.c

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	{
		int gp_start = 0x800 - (ETH_ZLEN < skb->len ? skb->len : ETH_ZLEN);
		unsigned char *buf = skb->data;

		lp->tx_pkt_start = gp_start;
    		lp->collisions = 0;

    		lp->stats.tx_bytes += skb->len;

		/*
		 *	Command mode with status cleared should [in theory]
		 *	mean no more interrupts can be pending on the card.
		 */

		outb_p(AX_SYS, AX_CMD);
		inb_p(RX_STATUS);
		inb_p(TX_STATUS);

		lp->loading = 1;
		lp->txing = 1;

		/*
		 *	Turn interrupts back on while we spend a pleasant afternoon
		 *	loading bytes into the board
		 */

		spin_unlock_irqrestore(&lp->lock, flags);
		
		outw(0x00, RX_BUF_CLR);		/* Set rx packet area to 0. */
		outw(gp_start, GP_LOW);		/* aim - packet will be loaded into buffer start */
		outsb(DATAPORT,buf,skb->len);	/* load buffer (usual thing each byte increments the pointer) */
		outw(gp_start, GP_LOW);		/* the board reuses the same register */
	
		if(lp->loading != 2)
		{
			outb(AX_XMIT, AX_CMD);		/* fire ... Trigger xmit.  */
			lp->loading=0;
			dev->trans_start = jiffies;
			if (el_debug > 2)
				printk(" queued xmit.\n");
			dev_kfree_skb (skb);
			return 0;
		}
		/* A receive upset our load, despite our best efforts */
		if(el_debug>2)
			printk("%s: burped during tx load.\n", dev->name);
		spin_lock_irqsave(&lp->lock, flags);
	}
	while(1);

}


/**
 * el_interrupt:
 * @irq: Interrupt number
 * @dev_id: The 3c501 that burped
 * @regs: Register data (surplus to our requirements)
 *
 * Handle the ether interface interrupts. The 3c501 needs a lot more 
 * hand holding than most cards. In paticular we get a transmit interrupt
 * with a collision error because the board firmware isnt capable of rewinding
 * its own transmit buffer pointers. It can however count to 16 for us.
 *
 * On the receive side the card is also very dumb. It has no buffering to
 * speak of. We simply pull the packet out of its PIO buffer (which is slow)
 * and queue it for the kernel. Then we reset the card for the next packet.
 *
 * We sometimes get suprise interrupts late both because the SMP IRQ delivery
 * is message passing and because the card sometimes seems to deliver late. I
 * think if it is part way through a receive and the mode is changed it carries
 * on receiving and sends us an interrupt. We have to band aid all these cases
 * to get a sensible 150kbytes/second performance. Even then you want a small
 * TCP window.
 */

static void el_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	struct net_device *dev = dev_id;
	struct net_local *lp;
	int ioaddr;
	int axsr;			/* Aux. status reg. */

	ioaddr = dev->base_addr;
	lp = (struct net_local *)dev->priv;

	spin_lock(&lp->lock);
	
	/*
	 *	What happened ?
	 */

	axsr = inb(AX_STATUS);

	/*
	 *	Log it
	 */

	if (el_debug > 3)
		printk(KERN_DEBUG "%s: el_interrupt() aux=%#02x", dev->name, axsr);

        if(lp->loading==1 && !lp->txing)
        	printk(KERN_WARNING "%s: Inconsistent state loading while not in tx\n",
        		dev->name);

	if (lp->txing)
	{

    		/*
    		 *	Board in transmit mode. May be loading. If we are
    		 *	loading we shouldn't have got this.
    		 */

		int txsr = inb(TX_STATUS);

		if(lp->loading==1)
		{
			if(el_debug > 2)
			{
				printk(KERN_DEBUG "%s: Interrupt while loading [", dev->name);
				printk(" txsr=%02x gp=%04x rp=%04x]\n", txsr, inw(GP_LOW),inw(RX_LOW));
			}
			lp->loading=2;		/* Force a reload */
			spin_unlock(&lp->lock);
			return;
		}

		if (el_debug > 6)
			printk(KERN_DEBUG " txsr=%02x gp=%04x rp=%04x", txsr, inw(GP_LOW),inw(RX_LOW));

		if ((axsr & 0x80) && (txsr & TX_READY) == 0)
		{
			/*
			 *	FIXME: is there a logic to whether to keep on trying or
			 *	reset immediately ?
			 */
			if(el_debug>1)
				printk("%s: Unusual interrupt during Tx, txsr=%02x axsr=%02x"
			  		" gp=%03x rp=%03x.\n", dev->name, txsr, axsr,
			inw(ioaddr + EL1_DATAPTR), inw(ioaddr + EL1_RXPTR));
			lp->txing = 0;
			netif_wake_queue(dev);
		}
		else if (txsr & TX_16COLLISIONS)
		{
			/*
			 *	Timed out
			 */
			if (el_debug)
				printk("%s: Transmit failed 16 times, Ethernet jammed?\n",dev->name);
			outb(AX_SYS, AX_CMD);
			lp->txing = 0;
			lp->stats.tx_aborted_errors++;
			netif_wake_queue(dev);
		}
		else if (txsr & TX_COLLISION)
		{
			/*
			 *	Retrigger xmit.
			 */

			if (el_debug > 6)
				printk(" retransmitting after a collision.\n");
			/*
			 *	Poor little chip can't reset its own start pointer
			 */

			outb(AX_SYS, AX_CMD);
			outw(lp->tx_pkt_start, GP_LOW);
			outb(AX_XMIT, AX_CMD);
			lp->stats.collisions++;
			spin_unlock(&lp->lock);
			return;
		}
		else
		{
			/*
			 *	It worked.. we will now fall through and receive
			 */
			lp->stats.tx_packets++;
			if (el_debug > 6)
				printk(" Tx succeeded %s\n",
		       			(txsr & TX_RDY) ? "." : "but tx is busy!");
			/*
			 *	This is safe the interrupt is atomic WRT itself.
			 */

			lp->txing = 0;
			netif_wake_queue(dev);	/* In case more to transmit */
		}
	}
	else
	{
    		/*
    		 *	In receive mode.
    		 */

		int rxsr = inb(RX_STATUS);
		if (el_debug > 5)
			printk(" rxsr=%02x txsr=%02x rp=%04x", rxsr, inb(TX_STATUS),inw(RX_LOW));
		/*
		 *	Just reading rx_status fixes most errors.
		 */
		if (rxsr & RX_MISSED)
			lp->stats.rx_missed_errors++;
		else if (rxsr & RX_RUNT)
		{	/* Handled to avoid board lock-up. */
			lp->stats.rx_length_errors++;
			if (el_debug > 5)
				printk(" runt.\n");
		}
		else if (rxsr & RX_GOOD)
		{
			/*
			 *	Receive worked.
			 */
			el_receive(dev);
		}
		else
		{
			/*
			 *	Nothing?  Something is broken!
			 */
			if (el_debug > 2)
				printk("%s: No packet seen, rxsr=%02x **resetting 3c501***\n",
					dev->name, rxsr);
			el_reset(dev);
		}
		if (el_debug > 3)
			printk(".\n");
	}

	/*
	 *	Move into receive mode
	 */

	outb(AX_RX, AX_CMD);
	outw(0x00, RX_BUF_CLR);
	inb(RX_STATUS);		/* Be certain that interrupts are cleared. */
	inb(TX_STATUS);
	spin_unlock(&lp->lock);
	return;
}


/**
 * el_receive:
 * @dev: Device to pull the packets from
 *
 * We have a good packet. Well, not really "good", just mostly not broken.
 * We must check everything to see if it is good. In paticular we occasionally
 * get wild packet sizes from the card. If the packet seems sane we PIO it
 * off the card and queue it for the protocol layers.
 */

static void el_receive(struct net_device *dev)
{
	struct net_local *lp = (struct net_local *)dev->priv;
	int ioaddr = dev->base_addr;
	int pkt_len;
	struct sk_buff *skb;

	pkt_len = inw(RX_LOW);

	if (el_debug > 4)
		printk(" el_receive %d.\n", pkt_len);

	if ((pkt_len < 60)  ||  (pkt_len > 1536))
	{
		if (el_debug)
			printk("%s: bogus packet, length=%d\n", dev->name, pkt_len);
		lp->stats.rx_over_errors++;
		return;
	}

	/*
	 *	Command mode so we can empty the buffer
	 */

	outb(AX_SYS, AX_CMD);
	skb = dev_alloc_skb(pkt_len+2);

	/*
	 *	Start of frame
	 */

	outw(0x00, GP_LOW);
	if (skb == NULL)
	{
		printk("%s: Memory squeeze, dropping packet.\n", dev->name);
		lp->stats.rx_dropped++;
		return;
	}
	else
	{
    		skb_reserve(skb,2);	/* Force 16 byte alignment */
		skb->dev = dev;
		/*
		 *	The read increments through the bytes. The interrupt
		 *	handler will fix the pointer when it returns to
		 *	receive mode.
		 */
		insb(DATAPORT, skb_put(skb,pkt_len), pkt_len);
		skb->protocol=eth_type_trans(skb,dev);
		netif_rx(skb);
		lp->stats.rx_packets++;
		lp->stats.rx_bytes+=pkt_len;
	}
	return;
}

/**
 * el_reset: Reset a 3c501 card
 * @dev: The 3c501 card about to get zapped
 *
 * Even resetting a 3c501 isnt simple. When you activate reset it loses all
 * its configuration. You must hold the lock when doing this. The function
 * cannot take the lock itself as it is callable from the irq handler.
 */

static void  el_reset(struct net_device *dev)
{
	struct net_local *lp = (struct net_local *)dev->priv;
	int ioaddr = dev->base_addr;

	if (el_debug> 2)
		printk("3c501 reset...");
	outb(AX_RESET, AX_CMD);		/* Reset the chip */
	outb(AX_LOOP, AX_CMD);		/* Aux control, irq and loopback enabled */
	{
		int i;
		for (i = 0; i < 6; i++)	/* Set the station address. */
			outb(dev->dev_addr[i], ioaddr + i);
	}

	outw(0, RX_BUF_CLR);		/* Set rx packet area to 0. */
	outb(TX_NORM, TX_CMD);		/* tx irq on done, collision */
	outb(RX_NORM, RX_CMD);		/* Set Rx commands. */
	inb(RX_STATUS);			/* Clear status. */
	inb(TX_STATUS);
	lp->txing = 0;
}

/**
 * el1_close:
 * @dev: 3c501 card to shut down
 *
 * Close a 3c501 card. The IFF_UP flag has been cleared by the user via
 * the SIOCSIFFLAGS ioctl. We stop any further transmissions being queued,
 * and then disable the interrupts. Finally we reset the chip. The effects
 * of the rest will be cleaned up by #el1_open. Always returns 0 indicating
 * a success.
 */
 
static int el1_close(struct net_device *dev)
{
	int ioaddr = dev->base_addr;

	if (el_debug > 2)
		printk("%s: Shutting down Ethernet card at %#x.\n", dev->name, ioaddr);

	netif_stop_queue(dev);
	
	/*
	 *	Free and disable the IRQ.
	 */

	free_irq(dev->irq, dev);
	outb(AX_RESET, AX_CMD);		/* Reset the chip */

	return 0;
}

/**
 * el1_get_stats:
 * @dev: The card to get the statistics for
 *
 * In smarter devices this function is needed to pull statistics off the
 * board itself. The 3c501 has no hardware statistics. We maintain them all
 * so they are by definition always up to date.
 *
 * Returns the statistics for the card from the card private data
 */
 
static struct net_device_stats *el1_get_stats(struct net_device *dev)
{
	struct net_local *lp = (struct net_local *)dev->priv;
	return &lp->stats;
}

/**
 * set_multicast_list:
 * @dev: The device to adjust
 *
 * Set or clear the multicast filter for this adaptor to use the best-effort 
 * filtering supported. The 3c501 supports only three modes of filtering.
 * It always receives broadcasts and packets for itself. You can choose to
 * optionally receive all packets, or all multicast packets on top of this.
 */

static void set_multicast_list(struct net_device *dev)
{
	int ioaddr = dev->base_addr;

	if(dev->flags&IFF_PROMISC)
	{
		outb(RX_PROM, RX_CMD);
		inb(RX_STATUS);
	}
	else if (dev->mc_list || dev->flags&IFF_ALLMULTI)
	{
		outb(RX_MULT, RX_CMD);	/* Multicast or all multicast is the same */
		inb(RX_STATUS);		/* Clear status. */
	}
	else
	{
		outb(RX_NORM, RX_CMD);
		inb(RX_STATUS);
	}
}

#ifdef MODULE

static struct net_device dev_3c501 = {
	init:		el1_probe,
	base_addr:	0x280,
	irq:		5,
};

static int io=0x280;
static int irq=5;
MODULE_PARM(io, "i");
MODULE_PARM(irq, "i");

/**
 * init_module:
 *
 * When the driver is loaded as a module this function is called. We fake up
 * a device structure with the base I/O and interrupt set as if it was being
 * called from Space.c. This minimises the extra code that would otherwise
 * be required.
 *
 * Returns 0 for success or -EIO if a card is not found. Returning an error
 * here also causes the module to be unloaded
 */
 
int init_module(void)
{
	dev_3c501.irq=irq;
	dev_3c501.base_addr=io;
	if (register_netdev(&dev_3c501) != 0)
		return -EIO;
	return 0;
}

/**
 * cleanup_module:
 * 
 * The module is being unloaded. We unhook our network device from the system
 * and then free up the resources we took when the card was found.
 */
 
void cleanup_module(void)
{
	/*
	 *	No need to check MOD_IN_USE, as sys_delete_module() checks.
	 */

	unregister_netdev(&dev_3c501);

	/*
	 *	Free up the private structure, or leak memory :-)
	 */

	kfree(dev_3c501.priv);
	dev_3c501.priv = NULL;	/* gets re-allocated by el1_probe1 */

	/*
	 *	If we don't do this, we can't re-insmod it later.
	 */
	release_region(dev_3c501.base_addr, EL1_IO_EXTENT);
}

#endif /* MODULE */

/*
 * Local variables:
 *  compile-command: "gcc -D__KERNEL__ -Wall -Wstrict-prototypes -O6 -fomit-frame-pointer  -m486 -c -o 3c501.o 3c501.c"
 *  kept-new-versions: 5
 * End:
 */