d_link.c

Linux 1.0 内核C源代码 Linux最早版本代码 由Linus Torvalds亲自书写的

{
	int		transmit_from;
	int		len;
	int		tickssofar;
	unsigned char	*buffer = skb->data;

	/*
	 * If some higher layer thinks we've missed a
	 * tx-done interrupt we are passed NULL.
	 * Caution: dev_tint() handles the cli()/sti() itself.
	 */

	if (skb == NULL) {
		dev_tint(dev);
		return 0;
	}

	/* For ethernet, fill in the header (hardware addresses) with an arp. */
	if (!skb->arp)
		if(dev->rebuild_header(skb->data, dev)) {
			skb->dev = dev;
			arp_queue (skb);
			return 0;
		}
	skb->arp = 1;

	if (free_tx_pages <= 0) {	/* Do timeouts, to avoid hangs. */
		tickssofar = jiffies - dev->trans_start;

		if (tickssofar < 5)
			return 1;

		/* else */
		printk("%s: transmit timed out (%d), %s?\n",
			dev->name,
			tickssofar,
			"network cable problem"
			);
		/* Restart the adapter. */
		adapter_init(dev);
	}

	/* Start real output */
	PRINTK(("d_link_start_xmit:len=%d, page %d/%d\n", skb->len, tx_fifo_in, free_tx_pages));

	if ((len = skb->len) < RUNT)
		len = RUNT;

	cli();
	select_nic();

	tx_fifo[tx_fifo_in] = transmit_from = tx_page_adr(tx_fifo_in) - len;
	tx_fifo_in = (tx_fifo_in + 1) % TX_PAGES; /* Next free tx page */

	d_link_setup_address(transmit_from, RW_ADDR);
	for ( ; len > 0; --len, ++buffer)
		d_link_put_byte(*buffer);

	if (free_tx_pages-- == TX_PAGES) { /* No transmission going on */
		dev->trans_start = jiffies;
		dev->tbusy = 0;	/* allow more packets into adapter */
		/* Send page and generate an interrupt */
		d_link_setup_address(transmit_from, TX_ADDR);
		d_link_put_command(TX_ENABLE);
	}
	else {
		dev->tbusy = !free_tx_pages;
		select_prn();
	}
	
	sti(); /* interrupts back on */
	
	if (skb->free)
		kfree_skb (skb, FREE_WRITE);

	return 0;
}

/*
 * The typical workload of the driver:
 * Handle the network interface interrupts.
 */
static void
d_link_interrupt(int reg_ptr)
{
	int		irq = -(((struct pt_regs *)reg_ptr)->orig_eax+2);
	struct device	*dev = irq2dev_map[irq];
	unsigned char	irq_status;
	int		retrig = 0;
	int		boguscount = 0;

	/* This might just as well be deleted now, no crummy drivers present :-) */
	if ((dev == NULL) || (dev->start == 0) || (D_LINK_IRQ != irq)) {
		printk("%s: bogus interrupt %d\n", dev?dev->name:"DE-600", irq);
		return;
	}

	dev->interrupt = 1;
	select_nic();
	irq_status = d_link_read_status(dev);

	do {
		PRINTK(("d_link_interrupt (%2.2X)\n", irq_status));

		if (irq_status & RX_GOOD)
			d_link_rx_intr(dev);
		else if (!(irq_status & RX_BUSY))
			d_link_put_command(RX_ENABLE);

		/* Any transmission in progress? */
		if (free_tx_pages < TX_PAGES)
			retrig = d_link_tx_intr(dev, irq_status);
		else
			retrig = 0;

		irq_status = d_link_read_status(dev);
	} while ( (irq_status & RX_GOOD) || ((++boguscount < 10) && retrig) );
	/*
	 * Yeah, it _looks_ like busy waiting, smells like busy waiting
	 * and I know it's not PC, but please, it will only occur once
	 * in a while and then only for a loop or so (< 1ms for sure!)
	 */

	/* Enable adapter interrupts */
	dev->interrupt = 0;
	select_prn();

	if (retrig)
		trigger_interrupt(dev);

	sti();
	return;
}

static int
d_link_tx_intr(struct device *dev, int irq_status)
{
	/*
	 * Returns 1 if tx still not done
	 */

	mark_bh(INET_BH);
	/* Check if current transmission is done yet */
	if (irq_status & TX_BUSY)
		return 1; /* tx not done, try again */

	/* else */
	/* If last transmission OK then bump fifo index */
	if (!(irq_status & TX_FAILED16)) {
		tx_fifo_out = (tx_fifo_out + 1) % TX_PAGES;
		++free_tx_pages;
		((struct netstats *)(dev->priv))->tx_packets++;
		dev->tbusy = 0;
	}

	/* More to send, or resend last packet? */
	if ((free_tx_pages < TX_PAGES) || (irq_status & TX_FAILED16)) {
		dev->trans_start = jiffies;
		d_link_setup_address(tx_fifo[tx_fifo_out], TX_ADDR);
		d_link_put_command(TX_ENABLE);
		return 1;
	}
	/* else */

	return 0;
}

/*
 * We have a good packet, get it out of the adapter.
 */
static void
d_link_rx_intr(struct device *dev)
{
	struct sk_buff	*skb;
	int		i;
	int		read_from;
	int		size;
	int		sksize;
	register unsigned char	*buffer;

	cli();
	/* Get size of received packet */
	size = d_link_read_byte(RX_LEN, dev);	/* low byte */
	size += (d_link_read_byte(RX_LEN, dev) << 8);	/* high byte */
	size -= 4;	/* Ignore trailing 4 CRC-bytes */

	/* Tell adapter where to store next incoming packet, enable receiver */
	read_from = rx_page_adr();
	next_rx_page();
	d_link_put_command(RX_ENABLE);
	sti();

	if ((size < 32)  ||  (size > 1535))
		printk("%s: Bogus packet size %d.\n", dev->name, size);

	sksize = sizeof(struct sk_buff) + size;
	skb = alloc_skb(sksize, GFP_ATOMIC);
	sti();
	if (skb == NULL) {
		printk("%s: Couldn't allocate a sk_buff of size %d.\n",
			dev->name, sksize);
		return;
	}
	/* else */

	skb->lock = 0;
	skb->mem_len = sksize;
	skb->mem_addr = skb;
	/* 'skb->data' points to the start of sk_buff data area. */
	buffer = skb->data;

	/* copy the packet into the buffer */
	d_link_setup_address(read_from, RW_ADDR);
	for (i = size; i > 0; --i, ++buffer)
		*buffer = d_link_read_byte(READ_DATA, dev);
	
	((struct netstats *)(dev->priv))->rx_packets++; /* count all receives */

	if (dev_rint((unsigned char *)skb, size, IN_SKBUFF, dev))
		printk("%s: receive buffers full.\n", dev->name);
	/*
	 * If any worth-while packets have been received, dev_rint()
	 * has done a mark_bh(INET_BH) for us and will work on them
	 * when we get to the bottom-half routine.
	 */
}

int
d_link_init(struct device *dev)
{
	int	i;

	printk("%s: D-Link DE-600 pocket adapter", dev->name);
	/* Alpha testers must have the version number to report bugs. */
	if (d_link_debug > 1)
		printk(version);

	/* probe for adapter */
	rx_page = 0;
	select_nic();
	(void)d_link_read_status(dev);
	d_link_put_command(RESET);
	d_link_put_command(STOP_RESET);
	if (d_link_read_status(dev) & 0xf0) {
		printk(": not at I/O %#3x.\n", DATA_PORT);
		return ENODEV;
	}

	/*
	 * Maybe we found one,
	 * have to check if it is a D-Link DE-600 adapter...
	 */

	/* Get the adapter ethernet address from the ROM */
	d_link_setup_address(NODE_ADDRESS, RW_ADDR);
	for (i = 0; i < ETH_ALEN; i++) {
		dev->dev_addr[i] = d_link_read_byte(READ_DATA, dev);
		dev->broadcast[i] = 0xff;
	}

	/* Check magic code */
	if ((dev->dev_addr[1] == 0xde) && (dev->dev_addr[2] == 0x15)) {
		/* OK, install real address */
		dev->dev_addr[0] = 0x00;
		dev->dev_addr[1] = 0x80;
		dev->dev_addr[2] = 0xc8;
		dev->dev_addr[3] &= 0x0f;
		dev->dev_addr[3] |= 0x70;
	} else {
		printk(" not identified in the printer port\n");
		return ENODEV;
	}

	printk(", Ethernet Address: %2.2X", dev->dev_addr[0]);
	for (i = 1; i < ETH_ALEN; i++)
		printk(":%2.2X",dev->dev_addr[i]);
	printk("\n");

	/* Initialize the device structure. */
	dev->priv = kmalloc(sizeof(struct netstats), GFP_KERNEL);
	memset(dev->priv, 0, sizeof(struct netstats));

	for (i = 0; i < DEV_NUMBUFFS; i++)
		dev->buffs[i] = NULL;

	dev->get_stats = get_stats;
	dev->hard_header = eth_header;
	dev->add_arp = eth_add_arp;
	dev->queue_xmit = dev_queue_xmit;
	dev->rebuild_header = eth_rebuild_header;
	dev->type_trans = eth_type_trans;

	dev->open = d_link_open;
	dev->stop = d_link_close;
	dev->hard_start_xmit = &d_link_start_xmit;

	/* These are ethernet specific. */
	dev->type = ARPHRD_ETHER;
	dev->hard_header_len = ETH_HLEN;
	dev->mtu = 1500; /* eth_mtu */
	dev->addr_len	= ETH_ALEN;

	/* New-style flags. */
	dev->flags = IFF_BROADCAST;
	dev->family = AF_INET;
	dev->pa_addr = 0;
	dev->pa_brdaddr = 0;
	dev->pa_mask = 0;
	dev->pa_alen = sizeof(unsigned long);

	select_prn();
	return 0;
}

static void
adapter_init(struct device *dev)
{
	int	i;

	cli();
	dev->tbusy = 0;		/* Transmit busy...  */
	dev->interrupt = 0;
	dev->start = 1;

	select_nic();
	rx_page = 0; /* used by RESET */
	d_link_put_command(RESET);
	d_link_put_command(STOP_RESET);

	tx_fifo_in = 0;
	tx_fifo_out = 0;
	free_tx_pages = TX_PAGES;

	/* set the ether address. */
	d_link_setup_address(NODE_ADDRESS, RW_ADDR);
	for (i = 0; i < ETH_ALEN; i++)
		d_link_put_byte(dev->dev_addr[i]);

	/* where to start saving incoming packets */
	rx_page = RX_BP | RX_BASE_PAGE;
	d_link_setup_address(MEM_4K, RW_ADDR);
	/* Enable receiver */
	d_link_put_command(RX_ENABLE);
	select_prn();
	sti();
}

#define D_LINK_MIN_WINDOW 1024
#define D_LINK_MAX_WINDOW 2048
#define D_LINK_TCP_WINDOW_DIFF 1024
/*
 * Copied from sock.c
 *
 * Sets a lower max receive window in order to achieve <= 2
 * packets arriving at the adapter in fast succession.
 * (No way that a DE-600 can cope with an ethernet saturated with its packets :-)
 *
 * Since there are only 2 receive buffers in the DE-600
 * and it takes some time to copy from the adapter,
 * this is absolutely necessary for any TCP performance whatsoever!
 *
 */
#define min(a,b)	((a)<(b)?(a):(b))
static unsigned long
d_link_rspace(struct sock *sk)
{
  int amt;

  if (sk != NULL) {
/*
 * Hack! You might want to play with commenting away the following line,
 * if you know what you do!
 */
  	sk->max_unacked = D_LINK_MAX_WINDOW - D_LINK_TCP_WINDOW_DIFF;

	if (sk->rmem_alloc >= SK_RMEM_MAX-2*D_LINK_MIN_WINDOW) return(0);
	amt = min((SK_RMEM_MAX-sk->rmem_alloc)/2-D_LINK_MIN_WINDOW, D_LINK_MAX_WINDOW);
	if (amt < 0) return(0);
	return(amt);
  }
  return(0);
}