isa-skeleton.c

讲述linux的初始化过程

	 * Always allocate the DMA channel after the IRQ,
	 * and clean up on failure.
	 */
	if (request_dma(dev->dma, cardname)) {
		free_irq(dev->irq, dev);
		return -EAGAIN;
	}

	/* Reset the hardware here. Don't forget to set the station address. */
	chipset_init(dev, 1);
	outb(0x00, ioaddr);
	np->open_time = jiffies;

	/* We are now ready to accept transmit requeusts from
	 * the queueing layer of the networking.
	 */
	netif_start_queue(dev);

	return 0;
}

/* This will only be invoked if your driver is _not_ in XOFF state.
 * What this means is that you need not check it, and that this
 * invariant will hold if you make sure that the netif_*_queue()
 * calls are done at the proper times.
 */
static int net_send_packet(struct sk_buff *skb, struct net_device *dev)
{
	struct net_local *np = (struct net_local *)dev->priv;
	int ioaddr = dev->base_addr;
	short length = ETH_ZLEN < skb->len ? skb->len : ETH_ZLEN;
	unsigned char *buf = skb->data;

	/* If some error occurs while trying to transmit this
	 * packet, you should return '1' from this function.
	 * In such a case you _may not_ do anything to the
	 * SKB, it is still owned by the network queueing
	 * layer when an error is returned.  This means you
	 * may not modify any SKB fields, you may not free
	 * the SKB, etc.
	 */

#if TX_RING
	/* This is the most common case for modern hardware.
	 * The spinlock protects this code from the TX complete
	 * hardware interrupt handler.  Queue flow control is
	 * thus managed under this lock as well.
	 */
	spin_lock_irq(&np->lock);

	add_to_tx_ring(np, skb, length);
	dev->trans_start = jiffies;

	/* If we just used up the very last entry in the
	 * TX ring on this device, tell the queueing
	 * layer to send no more.
	 */
	if (tx_full(dev))
		netif_stop_queue(dev);

	/* When the TX completion hw interrupt arrives, this
	 * is when the transmit statistics are updated.
	 */

	spin_unlock_irq(&np->lock);
#else
	/* This is the case for older hardware which takes
	 * a single transmit buffer at a time, and it is
	 * just written to the device via PIO.
	 *
	 * No spin locking is needed since there is no TX complete
	 * event.  If by chance your card does have a TX complete
	 * hardware IRQ then you may need to utilize np->lock here.
	 */
	hardware_send_packet(ioaddr, buf, length);
	np->stats.tx_bytes += skb->len;

	dev->trans_start = jiffies;

	/* You might need to clean up and record Tx statistics here. */
	if (inw(ioaddr) == /*RU*/81)
		np->stats.tx_aborted_errors++;
	dev_kfree_skb (skb);
#endif

	return 0;
}

#if TX_RING
/* This handles TX complete events posted by the device
 * via interrupts.
 */
void net_tx(struct net_device *dev)
{
	struct net_local *np = (struct net_local *)dev->priv;
	int entry;

	/* This protects us from concurrent execution of
	 * our dev->hard_start_xmit function above.
	 */
	spin_lock(&np->lock);

	entry = np->tx_old;
	while (tx_entry_is_sent(np, entry)) {
		struct sk_buff *skb = np->skbs[entry];

		np->stats.tx_bytes += skb->len;
		dev_kfree_skb_irq (skb);

		entry = next_tx_entry(np, entry);
	}
	np->tx_old = entry;

	/* If we had stopped the queue due to a "tx full"
	 * condition, and space has now been made available,
	 * wake up the queue.
	 */
	if (netif_queue_stopped(dev) && ! tx_full(dev))
		netif_wake_queue(dev);

	spin_unlock(&np->lock);
}
#endif

/*
 * The typical workload of the driver:
 * Handle the network interface interrupts.
 */
static void net_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	struct net_device *dev = dev_id;
	struct net_local *np;
	int ioaddr, status;

	ioaddr = dev->base_addr;

	np = (struct net_local *)dev->priv;
	status = inw(ioaddr + 0);

	if (status & RX_INTR) {
		/* Got a packet(s). */
		net_rx(dev);
	}
#if TX_RING
	if (status & TX_INTR) {
		/* Transmit complete. */
		net_tx(dev);
		np->stats.tx_packets++;
		netif_wake_queue(dev);
	}
#endif
	if (status & COUNTERS_INTR) {
		/* Increment the appropriate 'localstats' field. */
		np->stats.tx_window_errors++;
	}
}

/* We have a good packet(s), get it/them out of the buffers. */
static void
net_rx(struct net_device *dev)
{
	struct net_local *lp = (struct net_local *)dev->priv;
	int ioaddr = dev->base_addr;
	int boguscount = 10;

	do {
		int status = inw(ioaddr);
		int pkt_len = inw(ioaddr);
	  
		if (pkt_len == 0)		/* Read all the frames? */
			break;			/* Done for now */

		if (status & 0x40) {	/* There was an error. */
			lp->stats.rx_errors++;
			if (status & 0x20) lp->stats.rx_frame_errors++;
			if (status & 0x10) lp->stats.rx_over_errors++;
			if (status & 0x08) lp->stats.rx_crc_errors++;
			if (status & 0x04) lp->stats.rx_fifo_errors++;
		} else {
			/* Malloc up new buffer. */
			struct sk_buff *skb;

			lp->stats.rx_bytes+=pkt_len;
			
			skb = dev_alloc_skb(pkt_len);
			if (skb == NULL) {
				printk(KERN_NOTICE "%s: Memory squeeze, dropping packet.\n",
					   dev->name);
				lp->stats.rx_dropped++;
				break;
			}
			skb->dev = dev;

			/* 'skb->data' points to the start of sk_buff data area. */
			memcpy(skb_put(skb,pkt_len), (void*)dev->rmem_start,
				   pkt_len);
			/* or */
			insw(ioaddr, skb->data, (pkt_len + 1) >> 1);

			netif_rx(skb);
			lp->stats.rx_packets++;
		}
	} while (--boguscount);

	return;
}

/* The inverse routine to net_open(). */
static int
net_close(struct net_device *dev)
{
	struct net_local *lp = (struct net_local *)dev->priv;
	int ioaddr = dev->base_addr;

	lp->open_time = 0;

	netif_stop_queue(dev);

	/* Flush the Tx and disable Rx here. */

	disable_dma(dev->dma);

	/* If not IRQ or DMA jumpered, free up the line. */
	outw(0x00, ioaddr+0);	/* Release the physical interrupt line. */

	free_irq(dev->irq, dev);
	free_dma(dev->dma);

	/* Update the statistics here. */

	return 0;

}

/*
 * Get the current statistics.
 * This may be called with the card open or closed.
 */
static struct net_device_stats *net_get_stats(struct net_device *dev)
{
	struct net_local *lp = (struct net_local *)dev->priv;
	short ioaddr = dev->base_addr;

	/* Update the statistics from the device registers. */
	lp->stats.rx_missed_errors = inw(ioaddr+1);
	return &lp->stats;
}

/*
 * Set or clear the multicast filter for this adaptor.
 * num_addrs == -1	Promiscuous mode, receive all packets
 * num_addrs == 0	Normal mode, clear multicast list
 * num_addrs > 0	Multicast mode, receive normal and MC packets,
 *			and do best-effort filtering.
 */
static void
set_multicast_list(struct net_device *dev)
{
	short ioaddr = dev->base_addr;
	if (dev->flags&IFF_PROMISC)
	{
		/* Enable promiscuous mode */
		outw(MULTICAST|PROMISC, ioaddr);
	}
	else if((dev->flags&IFF_ALLMULTI) || dev->mc_count > HW_MAX_ADDRS)
	{
		/* Disable promiscuous mode, use normal mode. */
		hardware_set_filter(NULL);

		outw(MULTICAST, ioaddr);
	}
	else if(dev->mc_count)
	{
		/* Walk the address list, and load the filter */
		hardware_set_filter(dev->mc_list);

		outw(MULTICAST, ioaddr);
	}
	else 
		outw(0, ioaddr);
}

#ifdef MODULE

static struct net_device this_device;
static int io = 0x300;
static int irq;
static int dma;
static int mem;

int init_module(void)
{
	int result;

	if (io == 0)
		printk(KERN_WARNING "%s: You shouldn't use auto-probing with insmod!\n",
			   cardname);

	/* Copy the parameters from insmod into the device structure. */
	this_device.base_addr = io;
	this_device.irq       = irq;
	this_device.dma       = dma;
	this_device.mem_start = mem;
	this_device.init      = netcard_probe;

	if ((result = register_netdev(&this_device)) != 0)
		return result;

	return 0;
}

void
cleanup_module(void)
{
	/* No need to check MOD_IN_USE, as sys_delete_module() checks. */
	unregister_netdev(&this_device);
	/*
	 * If we don't do this, we can't re-insmod it later.
	 * Release irq/dma here, when you have jumpered versions and
	 * allocate them in net_probe1().
	 */
	/*
	   free_irq(this_device.irq, dev);
	   free_dma(this_device.dma);
	*/
	release_region(this_device.base_addr, NETCARD_IO_EXTENT);

	if (this_device.priv)
		kfree(this_device.priv);
}

#endif /* MODULE */

/*
 * Local variables:
 *  compile-command:
 *	gcc -D__KERNEL__ -Wall -Wstrict-prototypes -Wwrite-strings
 *	-Wredundant-decls -O2 -m486 -c skeleton.c
 *  version-control: t
 *  kept-new-versions: 5
 *  tab-width: 4
 *  c-indent-level: 4
 * End:
 */