isa-skeleton.c

讲述linux的初始化过程

/* isa-skeleton.c: A network driver outline for linux.
 *
 *	Written 1993-94 by Donald Becker.
 *
 *	Copyright 1993 United States Government as represented by the
 *	Director, National Security Agency.
 *
 *	This software may be used and distributed according to the terms
 *	of the GNU Public License, incorporated herein by reference.
 *
 *	The author may be reached as [e-mail], or C/O
 *	Center of Excellence in Space Data and Information Sciences
 *	   Code 930.5, Goddard Space Flight Center, Greenbelt MD 20771
 *
 *	This file is an outline for writing a network device driver for the
 *	the Linux operating system.
 *
 *	To write (or understand) a driver, have a look at the "loopback.c" file to
 *	get a feel of what is going on, and then use the code below as a skeleton
 *	for the new driver.
 *
 */

static const char *version =
	"isa-skeleton.c:v1.51 9/24/94 Donald Becker ([e-mail])\n";

/*
 *  Sources:
 *	List your sources of programming information to document that
 *	the driver is your own creation, and give due credit to others
 *	that contributed to the work. Remember that GNU project code
 *	cannot use proprietary or trade secret information. Interface
 *	definitions are generally considered non-copyrightable to the
 *	extent that the same names and structures must be used to be
 *	compatible.
 *
 *	Finally, keep in mind that the Linux kernel is has an API, not
 *	ABI. Proprietary object-code-only distributions are not permitted
 *	under the GPL.
 */

#include <linux/module.h>

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/in.h>
#include <linux/malloc.h>
#include <linux/string.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <linux/spinlock.h>
#include <asm/io.h>
#include <asm/dma.h>
#include <linux/errno.h>
#include <linux/init.h>

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>

/*
 * The name of the card. Is used for messages and in the requests for
 * io regions, irqs and dma channels
 */
static const char* cardname = "netcard";

/* First, a few definitions that the brave might change. */

/* A zero-terminated list of I/O addresses to be probed. */
static unsigned int netcard_portlist[] __initdata =
   { 0x200, 0x240, 0x280, 0x2C0, 0x300, 0x320, 0x340, 0};

/* use 0 for production, 1 for verification, >2 for debug */
#ifndef NET_DEBUG
#define NET_DEBUG 2
#endif
static unsigned int net_debug = NET_DEBUG;

/* The number of low I/O ports used by the ethercard. */
#define NETCARD_IO_EXTENT	32

#define MY_TX_TIMEOUT  ((400*HZ)/1000)

/* Information that need to be kept for each board. */
struct net_local {
	struct net_device_stats stats;
	long open_time;			/* Useless example local info. */

	/* Tx control lock.  This protects the transmit buffer ring
	 * state along with the "tx full" state of the driver.  This
	 * means all netif_queue flow control actions are protected
	 * by this lock as well.
	 */
	spinlock_t lock;
};

/* The station (ethernet) address prefix, used for IDing the board. */
#define SA_ADDR0 0x00
#define SA_ADDR1 0x42
#define SA_ADDR2 0x65

/* Index to functions, as function prototypes. */

extern int netcard_probe(struct net_device *dev);

static int	netcard_probe1(struct net_device *dev, int ioaddr);
static int	net_open(struct net_device *dev);
static int	net_send_packet(struct sk_buff *skb, struct net_device *dev);
static void	net_interrupt(int irq, void *dev_id, struct pt_regs *regs);
static void	net_rx(struct net_device *dev);
static int	net_close(struct net_device *dev);
static struct	net_device_stats *net_get_stats(struct net_device *dev);
static void	set_multicast_list(struct net_device *dev);
static void     net_tx_timeout(struct net_device *dev);


/* Example routines you must write ;->. */
#define tx_done(dev) 1
static void	hardware_send_packet(short ioaddr, char *buf, int length);
static void 	chipset_init(struct net_device *dev, int startp);

/*
 * Check for a network adaptor of this type, and return '0' iff one exists.
 * If dev->base_addr == 0, probe all likely locations.
 * If dev->base_addr == 1, always return failure.
 * If dev->base_addr == 2, allocate space for the device and return success
 * (detachable devices only).
 */
int __init 
netcard_probe(struct net_device *dev)
{
	int i;
	int base_addr = dev->base_addr;

	SET_MODULE_OWNER(dev);

	if (base_addr > 0x1ff)    /* Check a single specified location. */
		return netcard_probe1(dev, base_addr);
	else if (base_addr != 0)  /* Don't probe at all. */
		return -ENXIO;

	for (i = 0; netcard_portlist[i]; i++) {
		int ioaddr = netcard_portlist[i];
		if (check_region(ioaddr, NETCARD_IO_EXTENT))
			continue;
		if (netcard_probe1(dev, ioaddr) == 0)
			return 0;
	}

	return -ENODEV;
}

/*
 * This is the real probe routine. Linux has a history of friendly device
 * probes on the ISA bus. A good device probes avoids doing writes, and
 * verifies that the correct device exists and functions.
 */
static int __init netcard_probe1(struct net_device *dev, int ioaddr)
{
	struct net_local *np;
	static unsigned version_printed = 0;
	int i;

	/*
	 * For ethernet adaptors the first three octets of the station address 
	 * contains the manufacturer's unique code. That might be a good probe
	 * method. Ideally you would add additional checks.
	 */ 
	if (inb(ioaddr + 0) != SA_ADDR0
		||	 inb(ioaddr + 1) != SA_ADDR1
		||	 inb(ioaddr + 2) != SA_ADDR2) {
		return -ENODEV;
	}

	if (net_debug  &&  version_printed++ == 0)
		printk(KERN_DEBUG "%s", version);

	printk(KERN_INFO "%s: %s found at %#3x, ", dev->name, cardname, ioaddr);

	/* Fill in the 'dev' fields. */
	dev->base_addr = ioaddr;

	/* Retrieve and print the ethernet address. */
	for (i = 0; i < 6; i++)
		printk(" %2.2x", dev->dev_addr[i] = inb(ioaddr + i));

#ifdef jumpered_interrupts
	/*
	 * If this board has jumpered interrupts, allocate the interrupt
	 * vector now. There is no point in waiting since no other device
	 * can use the interrupt, and this marks the irq as busy. Jumpered
	 * interrupts are typically not reported by the boards, and we must
	 * used autoIRQ to find them.
	 */

	if (dev->irq == -1)
		;	/* Do nothing: a user-level program will set it. */
	else if (dev->irq < 2) {	/* "Auto-IRQ" */
		autoirq_setup(0);
		/* Trigger an interrupt here. */

		dev->irq = autoirq_report(0);
		if (net_debug >= 2)
			printk(" autoirq is %d", dev->irq);
	} else if (dev->irq == 2)
		/*
		 * Fixup for users that don't know that IRQ 2 is really
		 * IRQ9, or don't know which one to set.
		 */
		dev->irq = 9;

	{
		int irqval = request_irq(dev->irq, &net_interrupt, 0, cardname, dev);
		if (irqval) {
			printk("%s: unable to get IRQ %d (irqval=%d).\n",
				   dev->name, dev->irq, irqval);
			return -EAGAIN;
		}
	}
#endif	/* jumpered interrupt */
#ifdef jumpered_dma
	/*
	 * If we use a jumpered DMA channel, that should be probed for and
	 * allocated here as well. See lance.c for an example.
	 */
	if (dev->dma == 0) {
		if (request_dma(dev->dma, cardname)) {
			printk("DMA %d allocation failed.\n", dev->dma);
			return -EAGAIN;
		} else
			printk(", assigned DMA %d.\n", dev->dma);
	} else {
		short dma_status, new_dma_status;

		/* Read the DMA channel status registers. */
		dma_status = ((inb(DMA1_STAT_REG) >> 4) & 0x0f) |
			(inb(DMA2_STAT_REG) & 0xf0);
		/* Trigger a DMA request, perhaps pause a bit. */
		outw(0x1234, ioaddr + 8);
		/* Re-read the DMA status registers. */
		new_dma_status = ((inb(DMA1_STAT_REG) >> 4) & 0x0f) |
			(inb(DMA2_STAT_REG) & 0xf0);
		/*
		 * Eliminate the old and floating requests,
		 * and DMA4 the cascade.
		 */
		new_dma_status ^= dma_status;
		new_dma_status &= ~0x10;
		for (i = 7; i > 0; i--)
			if (test_bit(i, &new_dma_status)) {
				dev->dma = i;
				break;
			}
		if (i <= 0) {
			printk("DMA probe failed.\n");
			return -EAGAIN;
		} 
		if (request_dma(dev->dma, cardname)) {
			printk("probed DMA %d allocation failed.\n", dev->dma);
			return -EAGAIN;
		}
	}
#endif	/* jumpered DMA */

	/* Initialize the device structure. */
	if (dev->priv == NULL) {
		dev->priv = kmalloc(sizeof(struct net_local), GFP_KERNEL);
		if (dev->priv == NULL)
			return -ENOMEM;
	}

	memset(dev->priv, 0, sizeof(struct net_local));

	np = (struct net_local *)dev->priv;
	spin_lock_init(&np->lock);

	/* Grab the region so that no one else tries to probe our ioports. */
	request_region(ioaddr, NETCARD_IO_EXTENT, cardname);

	dev->open		= net_open;
	dev->stop		= net_close;
	dev->hard_start_xmit	= net_send_packet;
	dev->get_stats		= net_get_stats;
	dev->set_multicast_list = &set_multicast_list;

        dev->tx_timeout		= &net_tx_timeout;
        dev->watchdog_timeo	= MY_TX_TIMEOUT; 

	/* Fill in the fields of the device structure with ethernet values. */
	ether_setup(dev);

	return 0;
}

static void net_tx_timeout(struct net_device *dev)
{
	struct net_local *np = (struct net_local *)dev->priv;

	printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
	       tx_done(dev) ? "IRQ conflict" : "network cable problem");

	/* Try to restart the adaptor. */
	chipset_init(dev, 1);

	np->stats.tx_errors++;

	/* If we have space available to accept new transmit
	 * requests, wake up the queueing layer.  This would
	 * be the case if the chipset_init() call above just
	 * flushes out the tx queue and empties it.
	 *
	 * If instead, the tx queue is retained then the
	 * netif_wake_queue() call should be placed in the
	 * TX completion interrupt handler of the driver instead
	 * of here.
	 */
	if (!tx_full(dev))
		netif_wake_queue(dev);
}

/*
 * Open/initialize the board. This is called (in the current kernel)
 * sometime after booting when the 'ifconfig' program is run.
 *
 * This routine should set everything up anew at each open, even
 * registers that "should" only need to be set once at boot, so that
 * there is non-reboot way to recover if something goes wrong.
 */
static int
net_open(struct net_device *dev)
{
	struct net_local *np = (struct net_local *)dev->priv;
	int ioaddr = dev->base_addr;
	/*
	 * This is used if the interrupt line can turned off (shared).
	 * See 3c503.c for an example of selecting the IRQ at config-time.
	 */
	if (request_irq(dev->irq, &net_interrupt, 0, cardname, dev)) {
		return -EAGAIN;
	}
	/*