/* 3c527.c: 3Com Etherlink/MC32 driver for Linux 2.4 and 2.6.
 *
 *      (c) Copyright 1998 Red Hat Software Inc
 *      Written by Alan Cox.
 *      Further debugging by Carl Drougge.
 *      Initial SMP support by Felipe W Damasio <felipewd@terra.com.br>
 *      Heavily modified by Richard Procter <rnp@paradise.net.nz>
 *
 *      Based on skeleton.c written 1993-94 by Donald Becker and ne2.c
 *      (for the MCA stuff) written by Wim Dumon.
 *
 *      Thanks to 3Com for making this possible by providing me with the
 *      documentation.
 *
 *      This software may be used and distributed according to the terms
 *      of the GNU General Public License, incorporated herein by reference.
 *
 */

#define DRV_NAME                "3c527"
#define DRV_VERSION             "0.7-SMP"
#define DRV_RELDATE             "2003/09/21"

static const char *version =
DRV_NAME ".c:v" DRV_VERSION " " DRV_RELDATE " Richard Procter <rnp@paradise.net.nz>\n";

/**
 * DOC: Traps for the unwary
 *
 *      The diagram (Figure 1-1) and the POS summary disagree with the
 *      "Interrupt Level" section in the manual.
 *
 *      The manual contradicts itself when describing the minimum number
 *      buffers in the 'configure lists' command.
 *      My card accepts a buffer config of 4/4.
 *
 *      Setting the SAV BP bit does not save bad packets, but
 *      only enables RX on-card stats collection.
 *
 *      The documentation in places seems to miss things. In actual fact
 *      I've always eventually found everything is documented, it just
 *      requires careful study.
 *
 * DOC: Theory Of Operation
 *
 *      The 3com 3c527 is a 32bit MCA bus mastering adapter with a large
 *      amount of on board intelligence that housekeeps a somewhat dumber
 *      Intel NIC. For performance we want to keep the transmit queue deep
 *      as the card can transmit packets while fetching others from main
 *      memory by bus master DMA. Transmission and reception are driven by
 *      circular buffer queues.
 *
 *      The mailboxes can be used for controlling how the card traverses
 *      its buffer rings, but are used only for inital setup in this
 *      implementation.  The exec mailbox allows a variety of commands to
 *      be executed. Each command must complete before the next is
 *      executed. Primarily we use the exec mailbox for controlling the
 *      multicast lists.  We have to do a certain amount of interesting
 *      hoop jumping as the multicast list changes can occur in interrupt
 *      state when the card has an exec command pending. We defer such
 *      events until the command completion interrupt.
 *
 *      A copy break scheme (taken from 3c59x.c) is employed whereby
 *      received frames exceeding a configurable length are passed
 *      directly to the higher networking layers without incuring a copy,
 *      in what amounts to a time/space trade-off.
 *
 *      The card also keeps a large amount of statistical information
 *      on-board. In a perfect world, these could be used safely at no
 *      cost. However, lacking information to the contrary, processing
 *      them without races would involve so much extra complexity as to
 *      make it unworthwhile to do so. In the end, a hybrid SW/HW
 *      implementation was made necessary --- see mc32_update_stats().
 *
 * DOC: Notes
 *
 *      It should be possible to use two or more cards, but at this stage
 *      only by loading two copies of the same module.
 *
 *      The on-board 82586 NIC has trouble receiving multiple
 *      back-to-back frames and so is likely to drop packets from fast
 *      senders.
**/

#include <linux/module.h>

#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/mca-legacy.h>
#include <linux/ioport.h>
#include <linux/in.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/wait.h>
#include <linux/ethtool.h>
#include <linux/completion.h>
#include <linux/bitops.h>
#include <linux/semaphore.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/dma.h>

#include "3c527.h"

MODULE_LICENSE("GPL");

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

/* use 0 for production, 1 for verification, >2 for debug */
#ifndef NET_DEBUG
#define NET_DEBUG 2
#endif

#undef DEBUG_IRQ

static unsigned int mc32_debug = NET_DEBUG;

/* The number of low I/O ports used by the ethercard. */
#define MC32_IO_EXTENT  8

/* As implemented, values must be a power-of-2 -- 4/8/16/32 */
#define TX_RING_LEN     32       /* Typically the card supports 37  */
#define RX_RING_LEN     8        /*     "       "        "          */

/* Copy break point, see above for details.
 * Setting to > 1512 effectively disables this feature. */
#define RX_COPYBREAK    200      /* Value from 3c59x.c */

/* Issue the 82586 workaround command - this is for "busy lans", but
 * basically means for all lans now days - has a performance (latency)
 * cost, but best set. */
static const int WORKAROUND_82586=1;

/* Pointers to buffers and their on-card records */
struct mc32_ring_desc
{
        volatile struct skb_header *p;
        struct sk_buff *skb;
};

/* Information that needs to be kept for each board. */
struct mc32_local
{
        int slot;

        u32 base;
        volatile struct mc32_mailbox *rx_box;
        volatile struct mc32_mailbox *tx_box;
        volatile struct mc32_mailbox *exec_box;
        volatile struct mc32_stats *stats;    /* Start of on-card statistics */
        u16 tx_chain;           /* Transmit list start offset */
        u16 rx_chain;           /* Receive list start offset */
        u16 tx_len;             /* Transmit list count */
        u16 rx_len;             /* Receive list count */

        u16 xceiver_desired_state; /* HALTED or RUNNING */
        u16 cmd_nonblocking;    /* Thread is uninterested in command result */
        u16 mc_reload_wait;     /* A multicast load request is pending */
        u32 mc_list_valid;      /* True when the mclist is set */

        struct mc32_ring_desc tx_ring[TX_RING_LEN];     /* Host Transmit ring */
        struct mc32_ring_desc rx_ring[RX_RING_LEN];     /* Host Receive ring */

        atomic_t tx_count;      /* buffers left */
        atomic_t tx_ring_head;  /* index to tx en-queue end */
        u16 tx_ring_tail;       /* index to tx de-queue end */

        u16 rx_ring_tail;       /* index to rx de-queue end */

        struct semaphore cmd_mutex;    /* Serialises issuing of execute commands */
        struct completion execution_cmd; /* Card has completed an execute command */
        struct completion xceiver_cmd;   /* Card has completed a tx or rx command */
};

/* The station (ethernet) address prefix, used for a sanity check. */
#define SA_ADDR0 0x02
#define SA_ADDR1 0x60
#define SA_ADDR2 0xAC

struct mca_adapters_t {
        unsigned int    id;
        char            *name;
};

static const struct mca_adapters_t mc32_adapters[] = {
        { 0x0041, "3COM EtherLink MC/32" },
        { 0x8EF5, "IBM High Performance Lan Adapter" },
        { 0x0000, NULL }
};


/* Macros for ring index manipulations */
static inline u16 next_rx(u16 rx) { return (rx+1)&(RX_RING_LEN-1); };
static inline u16 prev_rx(u16 rx) { return (rx-1)&(RX_RING_LEN-1); };

static inline u16 next_tx(u16 tx) { return (tx+1)&(TX_RING_LEN-1); };


/* Index to functions, as function prototypes. */
static int      mc32_probe1(struct net_device *dev, int ioaddr);
static int      mc32_command(struct net_device *dev, u16 cmd, void *data, int len);
static int      mc32_open(struct net_device *dev);
static void     mc32_timeout(struct net_device *dev);
static int      mc32_send_packet(struct sk_buff *skb, struct net_device *dev);
static irqreturn_t mc32_interrupt(int irq, void *dev_id);
static int      mc32_close(struct net_device *dev);
static struct   net_device_stats *mc32_get_stats(struct net_device *dev);
static void     mc32_set_multicast_list(struct net_device *dev);
static void     mc32_reset_multicast_list(struct net_device *dev);
static const struct ethtool_ops netdev_ethtool_ops;

static void cleanup_card(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        unsigned slot = lp->slot;
        mca_mark_as_unused(slot);
        mca_set_adapter_name(slot, NULL);
        free_irq(dev->irq, dev);
        release_region(dev->base_addr, MC32_IO_EXTENT);
}

/**
 * mc32_probe   -       Search for supported boards
 * @unit: interface number to use
 *
 * Because MCA bus is a real bus and we can scan for cards we could do a
 * single scan for all boards here. Right now we use the passed in device
 * structure and scan for only one board. This needs fixing for modules
 * in particular.
 */

struct net_device *__init mc32_probe(int unit)
{
        struct net_device *dev = alloc_etherdev(sizeof(struct mc32_local));
        static int current_mca_slot = -1;
        int i;
        int err;

        if (!dev)
                return ERR_PTR(-ENOMEM);

        if (unit >= 0)
                sprintf(dev->name, "eth%d", unit);

        /* Do not check any supplied i/o locations.
           POS registers usually don't fail :) */

        /* MCA cards have POS registers.
           Autodetecting MCA cards is extremely simple.
           Just search for the card. */

        for(i = 0; (mc32_adapters[i].name != NULL); i++) {
                current_mca_slot =
                        mca_find_unused_adapter(mc32_adapters[i].id, 0);

                if(current_mca_slot != MCA_NOTFOUND) {
                        if(!mc32_probe1(dev, current_mca_slot))
                        {
                                mca_set_adapter_name(current_mca_slot,
                                                mc32_adapters[i].name);
                                mca_mark_as_used(current_mca_slot);
                                err = register_netdev(dev);
                                if (err) {
                                        cleanup_card(dev);
                                        free_netdev(dev);
                                        dev = ERR_PTR(err);
                                }
                                return dev;
                        }

                }
        }
        free_netdev(dev);
        return ERR_PTR(-ENODEV);
}

/**
 * mc32_probe1  -       Check a given slot for a board and test the card
 * @dev:  Device structure to fill in
 * @slot: The MCA bus slot being used by this card
 *
 * Decode the slot data and configure the card structures. Having done this we
 * can reset the card and configure it. The card does a full self test cycle
 * in firmware so we have to wait for it to return and post us either a
 * failure case or some addresses we use to find the board internals.
 */

static int __init mc32_probe1(struct net_device *dev, int slot)
{
        static unsigned version_printed;
        int i, err;
        u8 POS;
        u32 base;
        struct mc32_local *lp = netdev_priv(dev);
        static u16 mca_io_bases[]={
                0x7280,0x7290,
                0x7680,0x7690,
                0x7A80,0x7A90,
                0x7E80,0x7E90
        };
        static u32 mca_mem_bases[]={
                0x00C0000,
                0x00C4000,
                0x00C8000,
                0x00CC000,
                0x00D0000,
                0x00D4000,
                0x00D8000,
                0x00DC000
        };
        static char *failures[]={
                "Processor instruction",
                "Processor data bus",
                "Processor data bus",
                "Processor data bus",
                "Adapter bus",
                "ROM checksum",
                "Base RAM",
                "Extended RAM",
                "82586 internal loopback",
                "82586 initialisation failure",
                "Adapter list configuration error"
        };

        /* Time to play MCA games */

        if (mc32_debug  &&  version_printed++ == 0)
                printk(KERN_DEBUG "%s", version);

        printk(KERN_INFO "%s: %s found in slot %d:", dev->name, cardname, slot);

        POS = mca_read_stored_pos(slot, 2);

        if(!(POS&1))
        {
                printk(" disabled.\n");
                return -ENODEV;
        }

        /* Fill in the 'dev' fields. */
        dev->base_addr = mca_io_bases[(POS>>1)&7];
        dev->mem_start = mca_mem_bases[(POS>>4)&7];

        POS = mca_read_stored_pos(slot, 4);
        if(!(POS&1))
        {
                printk("memory window disabled.\n");
                return -ENODEV;
        }

        POS = mca_read_stored_pos(slot, 5);

        i=(POS>>4)&3;
        if(i==3)
        {
                printk("invalid memory window.\n");
                return -ENODEV;
        }

        i*=16384;
        i+=16384;

        dev->mem_end=dev->mem_start + i;

        dev->irq = ((POS>>2)&3)+9;

        if(!request_region(dev->base_addr, MC32_IO_EXTENT, cardname))
        {
                printk("io 0x%3lX, which is busy.\n", dev->base_addr);
                return -EBUSY;
        }

        printk("io 0x%3lX irq %d mem 0x%lX (%dK)\n",
                dev->base_addr, dev->irq, dev->mem_start, i/1024);


        /* We ought to set the cache line size here.. */


        /*
         *      Go PROM browsing
         */

        /* Retrieve and print the ethernet address. */
        for (i = 0; i < 6; i++)
        {
                mca_write_pos(slot, 6, i+12);
                mca_write_pos(slot, 7, 0);

                dev->dev_addr[i] = mca_read_pos(slot,3);
        }

        printk("%s: Address %pM", dev->name, dev->dev_addr);

        mca_write_pos(slot, 6, 0);
        mca_write_pos(slot, 7, 0);

        POS = mca_read_stored_pos(slot, 4);

        if(POS&2)
                printk(" : BNC port selected.\n");
        else
                printk(" : AUI port selected.\n");

        POS=inb(dev->base_addr+HOST_CTRL);
        POS|=HOST_CTRL_ATTN|HOST_CTRL_RESET;
        POS&=~HOST_CTRL_INTE;
        outb(POS, dev->base_addr+HOST_CTRL);
        /* Reset adapter */
        udelay(100);
        /* Reset off */
        POS&=~(HOST_CTRL_ATTN|HOST_CTRL_RESET);
        outb(POS, dev->base_addr+HOST_CTRL);

        udelay(300);

        /*
         *      Grab the IRQ
         */

        err = request_irq(dev->irq, &mc32_interrupt, IRQF_SHARED | IRQF_SAMPLE_RANDOM, DRV_NAME, dev);
        if (err) {
                release_region(dev->base_addr, MC32_IO_EXTENT);
                printk(KERN_ERR "%s: unable to get IRQ %d.\n", DRV_NAME, dev->irq);
                goto err_exit_ports;
        }

        memset(lp, 0, sizeof(struct mc32_local));
        lp->slot = slot;

        i=0;

        base = inb(dev->base_addr);

        while(base == 0xFF)
        {
                i++;
                if(i == 1000)
                {
                        printk(KERN_ERR "%s: failed to boot adapter.\n", dev->name);
                        err = -ENODEV;
                        goto err_exit_irq;
                }
                udelay(1000);
                if(inb(dev->base_addr+2)&(1<<5))
                        base = inb(dev->base_addr);
        }

        if(base>0)
        {
                if(base < 0x0C)
                        printk(KERN_ERR "%s: %s%s.\n", dev->name, failures[base-1],
                                base<0x0A?" test failure":"");
                else
                        printk(KERN_ERR "%s: unknown failure %d.\n", dev->name, base);
                err = -ENODEV;
                goto err_exit_irq;
        }

        base=0;
        for(i=0;i<4;i++)
        {
                int n=0;

                while(!(inb(dev->base_addr+2)&(1<<5)))
                {
                        n++;
                        udelay(50);
                        if(n>100)
                        {
                                printk(KERN_ERR "%s: mailbox read fail (%d).\n", dev->name, i);
                                err = -ENODEV;
                                goto err_exit_irq;
                        }
                }

                base|=(inb(dev->base_addr)<<(8*i));
        }

        lp->exec_box=isa_bus_to_virt(dev->mem_start+base);

        base=lp->exec_box->data[1]<<16|lp->exec_box->data[0];

        lp->base = dev->mem_start+base;

        lp->rx_box=isa_bus_to_virt(lp->base + lp->exec_box->data[2]);
        lp->tx_box=isa_bus_to_virt(lp->base + lp->exec_box->data[3]);

        lp->stats = isa_bus_to_virt(lp->base + lp->exec_box->data[5]);

        /*
         *      Descriptor chains (card relative)
         */

        lp->tx_chain            = lp->exec_box->data[8];   /* Transmit list start offset */
        lp->rx_chain            = lp->exec_box->data[10];  /* Receive list start offset */
        lp->tx_len              = lp->exec_box->data[9];   /* Transmit list count */
        lp->rx_len              = lp->exec_box->data[11];  /* Receive list count */

        init_MUTEX_LOCKED(&lp->cmd_mutex);
        init_completion(&lp->execution_cmd);
        init_completion(&lp->xceiver_cmd);

        printk("%s: Firmware Rev %d. %d RX buffers, %d TX buffers. Base of 0x%08X.\n",
                dev->name, lp->exec_box->data[12], lp->rx_len, lp->tx_len, lp->base);

        dev->open               = mc32_open;
        dev->stop               = mc32_close;
        dev->hard_start_xmit    = mc32_send_packet;
        dev->get_stats          = mc32_get_stats;
        dev->set_multicast_list = mc32_set_multicast_list;
        dev->tx_timeout         = mc32_timeout;
        dev->watchdog_timeo     = HZ*5; /* Board does all the work */
        dev->ethtool_ops        = &netdev_ethtool_ops;

        return 0;

err_exit_irq:
        free_irq(dev->irq, dev);
err_exit_ports:
        release_region(dev->base_addr, MC32_IO_EXTENT);
        return err;
}


/**
 *      mc32_ready_poll         -       wait until we can feed it a command
 *      @dev:   The device to wait for
 *
 *      Wait until the card becomes ready to accept a command via the
 *      command register. This tells us nothing about the completion
 *      status of any pending commands and takes very little time at all.
 */

static inline void mc32_ready_poll(struct net_device *dev)
{
        int ioaddr = dev->base_addr;
        while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
}


/**
 *      mc32_command_nowait     -       send a command non blocking
 *      @dev: The 3c527 to issue the command to
 *      @cmd: The command word to write to the mailbox
 *      @data: A data block if the command expects one
 *      @len: Length of the data block
 *
 *      Send a command from interrupt state. If there is a command
 *      currently being executed then we return an error of -1. It
 *      simply isn't viable to wait around as commands may be
 *      slow. This can theoretically be starved on SMP, but it's hard
 *      to see a realistic situation.  We do not wait for the command
 *      to complete --- we rely on the interrupt handler to tidy up
 *      after us.
 */

static int mc32_command_nowait(struct net_device *dev, u16 cmd, void *data, int len)
{
        struct mc32_local *lp = netdev_priv(dev);
        int ioaddr = dev->base_addr;
        int ret = -1;

        if (down_trylock(&lp->cmd_mutex) == 0)
        {
                lp->cmd_nonblocking=1;
                lp->exec_box->mbox=0;
                lp->exec_box->mbox=cmd;
                memcpy((void *)lp->exec_box->data, data, len);
                barrier();      /* the memcpy forgot the volatile so be sure */

                /* Send the command */
                mc32_ready_poll(dev);
                outb(1<<6, ioaddr+HOST_CMD);

                ret = 0;

                /* Interrupt handler will signal mutex on completion */
        }

        return ret;
}


/**
 *      mc32_command    -       send a command and sleep until completion
 *      @dev: The 3c527 card to issue the command to
 *      @cmd: The command word to write to the mailbox
 *      @data: A data block if the command expects one
 *      @len: Length of the data block
 *
 *      Sends exec commands in a user context. This permits us to wait around
 *      for the replies and also to wait for the command buffer to complete
 *      from a previous command before we execute our command. After our
 *      command completes we will attempt any pending multicast reload
 *      we blocked off by hogging the exec buffer.
 *
 *      You feed the card a command, you wait, it interrupts you get a
 *      reply. All well and good. The complication arises because you use
 *      commands for filter list changes which come in at bh level from things
 *      like IPV6 group stuff.
 */

static int mc32_command(struct net_device *dev, u16 cmd, void *data, int len)
{
        struct mc32_local *lp = netdev_priv(dev);
        int ioaddr = dev->base_addr;
        int ret = 0;

        down(&lp->cmd_mutex);

        /*
         *     My Turn
         */

        lp->cmd_nonblocking=0;
        lp->exec_box->mbox=0;
        lp->exec_box->mbox=cmd;
        memcpy((void *)lp->exec_box->data, data, len);
        barrier();      /* the memcpy forgot the volatile so be sure */

        mc32_ready_poll(dev);
        outb(1<<6, ioaddr+HOST_CMD);

        wait_for_completion(&lp->execution_cmd);

        if(lp->exec_box->mbox&(1<<13))
                ret = -1;

        up(&lp->cmd_mutex);

        /*
         *      A multicast set got blocked - try it now
         */

        if(lp->mc_reload_wait)
        {
                mc32_reset_multicast_list(dev);
        }

        return ret;
}


/**
 *      mc32_start_transceiver  -       tell board to restart tx/rx
 *      @dev: The 3c527 card to issue the command to
 *
 *      This may be called from the interrupt state, where it is used
 *      to restart the rx ring if the card runs out of rx buffers.
 *
 *      We must first check if it's ok to (re)start the transceiver. See
 *      mc32_close for details.
 */

static void mc32_start_transceiver(struct net_device *dev) {

        struct mc32_local *lp = netdev_priv(dev);
        int ioaddr = dev->base_addr;

        /* Ignore RX overflow on device closure */
        if (lp->xceiver_desired_state==HALTED)
                return;

        /* Give the card the offset to the post-EOL-bit RX descriptor */
        mc32_ready_poll(dev);
        lp->rx_box->mbox=0;
        lp->rx_box->data[0]=lp->rx_ring[prev_rx(lp->rx_ring_tail)].p->next;
        outb(HOST_CMD_START_RX, ioaddr+HOST_CMD);

        mc32_ready_poll(dev);
        lp->tx_box->mbox=0;
        outb(HOST_CMD_RESTRT_TX, ioaddr+HOST_CMD);   /* card ignores this on RX restart */

        /* We are not interrupted on start completion */
}


/**
 *      mc32_halt_transceiver   -       tell board to stop tx/rx
 *      @dev: The 3c527 card to issue the command to
 *
 *      We issue the commands to halt the card's transceiver. In fact,
 *      after some experimenting we now simply tell the card to
 *      suspend. When issuing aborts occasionally odd things happened.
 *
 *      We then sleep until the card has notified us that both rx and
 *      tx have been suspended.
 */

static void mc32_halt_transceiver(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        int ioaddr = dev->base_addr;

        mc32_ready_poll(dev);
        lp->rx_box->mbox=0;
        outb(HOST_CMD_SUSPND_RX, ioaddr+HOST_CMD);
        wait_for_completion(&lp->xceiver_cmd);

        mc32_ready_poll(dev);
        lp->tx_box->mbox=0;
        outb(HOST_CMD_SUSPND_TX, ioaddr+HOST_CMD);
        wait_for_completion(&lp->xceiver_cmd);
}


/**
 *      mc32_load_rx_ring       -       load the ring of receive buffers
 *      @dev: 3c527 to build the ring for
 *
 *      This initalises the on-card and driver datastructures to
 *      the point where mc32_start_transceiver() can be called.
 *
 *      The card sets up the receive ring for us. We are required to use the
 *      ring it provides, although the size of the ring is configurable.
 *
 *      We allocate an sk_buff for each ring entry in turn and
 *      initalise its house-keeping info. At the same time, we read
 *      each 'next' pointer in our rx_ring array. This reduces slow
 *      shared-memory reads and makes it easy to access predecessor
 *      descriptors.
 *
 *      We then set the end-of-list bit for the last entry so that the
 *      card will know when it has run out of buffers.
 */

static int mc32_load_rx_ring(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        int i;
        u16 rx_base;
        volatile struct skb_header *p;

        rx_base=lp->rx_chain;

        for(i=0; i<RX_RING_LEN; i++) {
                lp->rx_ring[i].skb=alloc_skb(1532, GFP_KERNEL);
                if (lp->rx_ring[i].skb==NULL) {
                        for (;i>=0;i--)
                                kfree_skb(lp->rx_ring[i].skb);
                        return -ENOBUFS;
                }
                skb_reserve(lp->rx_ring[i].skb, 18);

                p=isa_bus_to_virt(lp->base+rx_base);

                p->control=0;
                p->data=isa_virt_to_bus(lp->rx_ring[i].skb->data);
                p->status=0;
                p->length=1532;

                lp->rx_ring[i].p=p;
                rx_base=p->next;
        }

        lp->rx_ring[i-1].p->control |= CONTROL_EOL;

        lp->rx_ring_tail=0;

        return 0;
}


/**
 *      mc32_flush_rx_ring      -       free the ring of receive buffers
 *      @lp: Local data of 3c527 to flush the rx ring of
 *
 *      Free the buffer for each ring slot. This may be called
 *      before mc32_load_rx_ring(), eg. on error in mc32_open().
 *      Requires rx skb pointers to point to a valid skb, or NULL.
 */

static void mc32_flush_rx_ring(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        int i;

        for(i=0; i < RX_RING_LEN; i++)
        {
                if (lp->rx_ring[i].skb) {
                        dev_kfree_skb(lp->rx_ring[i].skb);
                        lp->rx_ring[i].skb = NULL;
                }
                lp->rx_ring[i].p=NULL;
        }
}


/**
 *      mc32_load_tx_ring       -       load transmit ring
 *      @dev: The 3c527 card to issue the command to
 *
 *      This sets up the host transmit data-structures.
 *
 *      First, we obtain from the card it's current postion in the tx
 *      ring, so that we will know where to begin transmitting
 *      packets.
 *
 *      Then, we read the 'next' pointers from the on-card tx ring into
 *      our tx_ring array to reduce slow shared-mem reads. Finally, we
 *      intitalise the tx house keeping variables.
 *
 */

static void mc32_load_tx_ring(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        volatile struct skb_header *p;
        int i;
        u16 tx_base;

        tx_base=lp->tx_box->data[0];

        for(i=0 ; i<TX_RING_LEN ; i++)
        {
                p=isa_bus_to_virt(lp->base+tx_base);
                lp->tx_ring[i].p=p;
                lp->tx_ring[i].skb=NULL;

                tx_base=p->next;
        }

        /* -1 so that tx_ring_head cannot "lap" tx_ring_tail */
        /* see mc32_tx_ring */

        atomic_set(&lp->tx_count, TX_RING_LEN-1);
        atomic_set(&lp->tx_ring_head, 0);
        lp->tx_ring_tail=0;
}


/**
 *      mc32_flush_tx_ring      -       free transmit ring
 *      @lp: Local data of 3c527 to flush the tx ring of
 *
 *      If the ring is non-empty, zip over the it, freeing any
 *      allocated skb_buffs.  The tx ring house-keeping variables are
 *      then reset. Requires rx skb pointers to point to a valid skb,
 *      or NULL.
 */

static void mc32_flush_tx_ring(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        int i;

        for (i=0; i < TX_RING_LEN; i++)
        {
                if (lp->tx_ring[i].skb)
                {
                        dev_kfree_skb(lp->tx_ring[i].skb);
                        lp->tx_ring[i].skb = NULL;
                }
        }

        atomic_set(&lp->tx_count, 0);
        atomic_set(&lp->tx_ring_head, 0);
        lp->tx_ring_tail=0;
}


/**
 *      mc32_open       -       handle 'up' of card
 *      @dev: device to open
 *
 *      The user is trying to bring the card into ready state. This requires
 *      a brief dialogue with the card. Firstly we enable interrupts and then
 *      'indications'. Without these enabled the card doesn't bother telling
 *      us what it has done. This had me puzzled for a week.
 *
 *      We configure the number of card descriptors, then load the network
 *      address and multicast filters. Turn on the workaround mode. This
 *      works around a bug in the 82586 - it asks the firmware to do
 *      so. It has a performance (latency) hit but is needed on busy
 *      [read most] lans. We load the ring with buffers then we kick it
 *      all off.
 */

static int mc32_open(struct net_device *dev)
{
        int ioaddr = dev->base_addr;
        struct mc32_local *lp = netdev_priv(dev);
        u8 one=1;
        u8 regs;
        u16 descnumbuffs[2] = {TX_RING_LEN, RX_RING_LEN};

        /*
         *      Interrupts enabled
         */

        regs=inb(ioaddr+HOST_CTRL);
        regs|=HOST_CTRL_INTE;
        outb(regs, ioaddr+HOST_CTRL);

        /*
         *      Allow ourselves to issue commands
         */

        up(&lp->cmd_mutex);


        /*
         *      Send the indications on command
         */

        mc32_command(dev, 4, &one, 2);

        /*
         *      Poke it to make sure it's really dead.
         */

        mc32_halt_transceiver(dev);
        mc32_flush_tx_ring(dev);

        /*
         *      Ask card to set up on-card descriptors to our spec
         */

        if(mc32_command(dev, 8, descnumbuffs, 4)) {
                printk("%s: %s rejected our buffer configuration!\n",
                       dev->name, cardname);
                mc32_close(dev);
                return -ENOBUFS;
        }

        /* Report new configuration */
        mc32_command(dev, 6, NULL, 0);

        lp->tx_chain            = lp->exec_box->data[8];   /* Transmit list start offset */
        lp->rx_chain            = lp->exec_box->data[10];  /* Receive list start offset */
        lp->tx_len              = lp->exec_box->data[9];   /* Transmit list count */
        lp->rx_len              = lp->exec_box->data[11];  /* Receive list count */

        /* Set Network Address */
        mc32_command(dev, 1, dev->dev_addr, 6);

        /* Set the filters */
        mc32_set_multicast_list(dev);

        if (WORKAROUND_82586) {
                u16 zero_word=0;
                mc32_command(dev, 0x0D, &zero_word, 2);   /* 82586 bug workaround on  */
        }

        mc32_load_tx_ring(dev);

        if(mc32_load_rx_ring(dev))
        {
                mc32_close(dev);
                return -ENOBUFS;
        }

        lp->xceiver_desired_state = RUNNING;

        /* And finally, set the ball rolling... */
        mc32_start_transceiver(dev);

        netif_start_queue(dev);

        return 0;
}


/**
 *      mc32_timeout    -       handle a timeout from the network layer
 *      @dev: 3c527 that timed out
 *
 *      Handle a timeout on transmit from the 3c527. This normally means
 *      bad things as the hardware handles cable timeouts and mess for
 *      us.
 *
 */

static void mc32_timeout(struct net_device *dev)
{
        printk(KERN_WARNING "%s: transmit timed out?\n", dev->name);
        /* Try to restart the adaptor. */
        netif_wake_queue(dev);
}


/**
 *      mc32_send_packet        -       queue a frame for transmit
 *      @skb: buffer to transmit
 *      @dev: 3c527 to send it out of

 *
 *      Transmit a buffer. This normally means throwing the buffer onto
 *      the transmit queue as the queue is quite large. If the queue is
 *      full then we set tx_busy and return. Once the interrupt handler
 *      gets messages telling it to reclaim transmit queue entries, we will
 *      clear tx_busy and the kernel will start calling this again.
 *
 *      We do not disable interrupts or acquire any locks; this can
 *      run concurrently with mc32_tx_ring(), and the function itself
 *      is serialised at a higher layer. However, similarly for the
 *      card itself, we must ensure that we update tx_ring_head only
 *      after we've established a valid packet on the tx ring (and
 *      before we let the card "see" it, to prevent it racing with the
 *      irq handler).
 *
 */

static int mc32_send_packet(struct sk_buff *skb, struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        u32 head = atomic_read(&lp->tx_ring_head);

        volatile struct skb_header *p, *np;

        netif_stop_queue(dev);

        if(atomic_read(&lp->tx_count)==0) {
                return 1;
        }

        if (skb_padto(skb, ETH_ZLEN)) {
                netif_wake_queue(dev);
                return 0;
        }

        atomic_dec(&lp->tx_count);

        /* P is the last sending/sent buffer as a pointer */
        p=lp->tx_ring[head].p;

        head = next_tx(head);

        /* NP is the buffer we will be loading */
        np=lp->tx_ring[head].p;

        /* We will need this to flush the buffer out */
        lp->tx_ring[head].skb=skb;

        np->length      = unlikely(skb->len < ETH_ZLEN) ? ETH_ZLEN : skb->len;
        np->data        = isa_virt_to_bus(skb->data);
        np->status      = 0;
        np->control     = CONTROL_EOP | CONTROL_EOL;
        wmb();

        /*
         * The new frame has been setup; we can now
         * let the interrupt handler and card "see" it
         */

        atomic_set(&lp->tx_ring_head, head);
        p->control     &= ~CONTROL_EOL;

        netif_wake_queue(dev);
        return 0;
}


/**
 *      mc32_update_stats       -       pull off the on board statistics
 *      @dev: 3c527 to service
 *
 *
 *      Query and reset the on-card stats. There's the small possibility
 *      of a race here, which would result in an underestimation of
 *      actual errors. As such, we'd prefer to keep all our stats
 *      collection in software. As a rule, we do. However it can't be
 *      used for rx errors and collisions as, by default, the card discards
 *      bad rx packets.
 *
 *      Setting the SAV BP in the rx filter command supposedly
 *      stops this behaviour. However, testing shows that it only seems to
 *      enable the collation of on-card rx statistics --- the driver
 *      never sees an RX descriptor with an error status set.
 *
 */

static void mc32_update_stats(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        volatile struct mc32_stats *st = lp->stats;

        u32 rx_errors=0;

        rx_errors+=dev->stats.rx_crc_errors   +=st->rx_crc_errors;
                                                   st->rx_crc_errors=0;
        rx_errors+=dev->stats.rx_fifo_errors  +=st->rx_overrun_errors;
                                                   st->rx_overrun_errors=0;
        rx_errors+=dev->stats.rx_frame_errors +=st->rx_alignment_errors;
                                                   st->rx_alignment_errors=0;
        rx_errors+=dev->stats.rx_length_errors+=st->rx_tooshort_errors;
                                                   st->rx_tooshort_errors=0;
        rx_errors+=dev->stats.rx_missed_errors+=st->rx_outofresource_errors;
                                                   st->rx_outofresource_errors=0;
        dev->stats.rx_errors=rx_errors;

        /* Number of packets which saw one collision */
        dev->stats.collisions+=st->dataC[10];
        st->dataC[10]=0;

        /* Number of packets which saw 2--15 collisions */
        dev->stats.collisions+=st->dataC[11];
        st->dataC[11]=0;
}


/**
 *      mc32_rx_ring    -       process the receive ring
 *      @dev: 3c527 that needs its receive ring processing
 *
 *
 *      We have received one or more indications from the card that a
 *      receive has completed. The buffer ring thus contains dirty
 *      entries. We walk the ring by iterating over the circular rx_ring
 *      array, starting at the next dirty buffer (which happens to be the
 *      one we finished up at last time around).
 *
 *      For each completed packet, we will either copy it and pass it up
 *      the stack or, if the packet is near MTU sized, we allocate
 *      another buffer and flip the old one up the stack.
 *
 *      We must succeed in keeping a buffer on the ring. If necessary we
 *      will toss a received packet rather than lose a ring entry. Once
 *      the first uncompleted descriptor is found, we move the
 *      End-Of-List bit to include the buffers just processed.
 *
 */

static void mc32_rx_ring(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        volatile struct skb_header *p;
        u16 rx_ring_tail;
        u16 rx_old_tail;
        int x=0;

        rx_old_tail = rx_ring_tail = lp->rx_ring_tail;

        do
        {
                p=lp->rx_ring[rx_ring_tail].p;

                if(!(p->status & (1<<7))) { /* Not COMPLETED */
                        break;
                }
                if(p->status & (1<<6)) /* COMPLETED_OK */
                {

                        u16 length=p->length;
                        struct sk_buff *skb;
                        struct sk_buff *newskb;

                        /* Try to save time by avoiding a copy on big frames */

                        if ((length > RX_COPYBREAK)
                            && ((newskb=dev_alloc_skb(1532)) != NULL))
                        {
                                skb=lp->rx_ring[rx_ring_tail].skb;
                                skb_put(skb, length);

                                skb_reserve(newskb,18);
                                lp->rx_ring[rx_ring_tail].skb=newskb;
                                p->data=isa_virt_to_bus(newskb->data);
                        }
                        else
                        {
                                skb=dev_alloc_skb(length+2);

                                if(skb==NULL) {
                                        dev->stats.rx_dropped++;
                                        goto dropped;
                                }

                                skb_reserve(skb,2);
                                memcpy(skb_put(skb, length),
                                       lp->rx_ring[rx_ring_tail].skb->data, length);
                        }

                        skb->protocol=eth_type_trans(skb,dev);
                        dev->stats.rx_packets++;
                        dev->stats.rx_bytes += length;
                        netif_rx(skb);
                }

        dropped:
                p->length = 1532;
                p->status = 0;

                rx_ring_tail=next_rx(rx_ring_tail);
        }
        while(x++<48);

        /* If there was actually a frame to be processed, place the EOL bit */
        /* at the descriptor prior to the one to be filled next */

        if (rx_ring_tail != rx_old_tail)
        {
                lp->rx_ring[prev_rx(rx_ring_tail)].p->control |=  CONTROL_EOL;
                lp->rx_ring[prev_rx(rx_old_tail)].p->control  &= ~CONTROL_EOL;

                lp->rx_ring_tail=rx_ring_tail;
        }
}


/**
 *      mc32_tx_ring    -       process completed transmits
 *      @dev: 3c527 that needs its transmit ring processing
 *
 *
 *      This operates in a similar fashion to mc32_rx_ring. We iterate
 *      over the transmit ring. For each descriptor which has been
 *      processed by the card, we free its associated buffer and note
 *      any errors. This continues until the transmit ring is emptied
 *      or we reach a descriptor that hasn't yet been processed by the
 *      card.
 *
 */

static void mc32_tx_ring(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        volatile struct skb_header *np;

        /*
         * We rely on head==tail to mean 'queue empty'.
         * This is why lp->tx_count=TX_RING_LEN-1: in order to prevent
         * tx_ring_head wrapping to tail and confusing a 'queue empty'
         * condition with 'queue full'
         */

        while (lp->tx_ring_tail != atomic_read(&lp->tx_ring_head))
        {
                u16 t;

                t=next_tx(lp->tx_ring_tail);
                np=lp->tx_ring[t].p;

                if(!(np->status & (1<<7)))
                {
                        /* Not COMPLETED */
                        break;
                }
                dev->stats.tx_packets++;
                if(!(np->status & (1<<6))) /* Not COMPLETED_OK */
                {
                        dev->stats.tx_errors++;

                        switch(np->status&0x0F)
                        {
                                case 1:
                                        dev->stats.tx_aborted_errors++;
                                        break; /* Max collisions */
                                case 2:
                                        dev->stats.tx_fifo_errors++;
                                        break;
                                case 3:
                                        dev->stats.tx_carrier_errors++;
                                        break;
                                case 4:
                                        dev->stats.tx_window_errors++;
                                        break;  /* CTS Lost */
                                case 5:
                                        dev->stats.tx_aborted_errors++;
                                        break; /* Transmit timeout */
                        }
                }
                /* Packets are sent in order - this is
                    basically a FIFO queue of buffers matching
                    the card ring */
                dev->stats.tx_bytes+=lp->tx_ring[t].skb->len;
                dev_kfree_skb_irq(lp->tx_ring[t].skb);
                lp->tx_ring[t].skb=NULL;
                atomic_inc(&lp->tx_count);
                netif_wake_queue(dev);

                lp->tx_ring_tail=t;
        }

}


/**
 *      mc32_interrupt          -       handle an interrupt from a 3c527
 *      @irq: Interrupt number
 *      @dev_id: 3c527 that requires servicing
 *      @regs: Registers (unused)
 *
 *
 *      An interrupt is raised whenever the 3c527 writes to the command
 *      register. This register contains the message it wishes to send us
 *      packed into a single byte field. We keep reading status entries
 *      until we have processed all the control items, but simply count
 *      transmit and receive reports. When all reports are in we empty the
 *      transceiver rings as appropriate. This saves the overhead of
 *      multiple command requests.
 *
 *      Because MCA is level-triggered, we shouldn't miss indications.
 *      Therefore, we needn't ask the card to suspend interrupts within
 *      this handler. The card receives an implicit acknowledgment of the
 *      current interrupt when we read the command register.
 *
 */

static irqreturn_t mc32_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = dev_id;
        struct mc32_local *lp;
        int ioaddr, status, boguscount = 0;
        int rx_event = 0;
        int tx_event = 0;

        ioaddr = dev->base_addr;
        lp = netdev_priv(dev);

        /* See whats cooking */

        while((inb(ioaddr+HOST_STATUS)&HOST_STATUS_CWR) && boguscount++<2000)
        {
                status=inb(ioaddr+HOST_CMD);

#ifdef DEBUG_IRQ
                printk("Status TX%d RX%d EX%d OV%d BC%d\n",
                        (status&7), (status>>3)&7, (status>>6)&1,
                        (status>>7)&1, boguscount);
#endif

                switch(status&7)
                {
                        case 0:
                                break;
                        case 6: /* TX fail */
                        case 2: /* TX ok */
                                tx_event = 1;
                                break;
                        case 3: /* Halt */
                        case 4: /* Abort */
                                complete(&lp->xceiver_cmd);
                                break;
                        default:
                                printk("%s: strange tx ack %d\n", dev->name, status&7);
                }
                status>>=3;
                switch(status&7)
                {
                        case 0:
                                break;
                        case 2: /* RX */
                                rx_event=1;
                                break;
                        case 3: /* Halt */
                        case 4: /* Abort */
                                complete(&lp->xceiver_cmd);
                                break;
                        case 6:
                                /* Out of RX buffers stat */
                                /* Must restart rx */
                                dev->stats.rx_dropped++;
                                mc32_rx_ring(dev);
                                mc32_start_transceiver(dev);
                                break;
                        default:
                                printk("%s: strange rx ack %d\n",
                                        dev->name, status&7);
                }
                status>>=3;
                if(status&1)
                {
                        /*
                         * No thread is waiting: we need to tidy
                         * up ourself.
                         */

                        if (lp->cmd_nonblocking) {
                                up(&lp->cmd_mutex);
                                if (lp->mc_reload_wait)
                                        mc32_reset_multicast_list(dev);
                        }
                        else complete(&lp->execution_cmd);
                }
                if(status&2)
                {
                        /*
                         *      We get interrupted once per
                         *      counter that is about to overflow.
                         */

                        mc32_update_stats(dev);
                }
        }


        /*
         *      Process the transmit and receive rings
         */

        if(tx_event)
                mc32_tx_ring(dev);

        if(rx_event)
                mc32_rx_ring(dev);

        return IRQ_HANDLED;
}


/**
 *      mc32_close      -       user configuring the 3c527 down
 *      @dev: 3c527 card to shut down
 *
 *      The 3c527 is a bus mastering device. We must be careful how we
 *      shut it down. It may also be running shared interrupt so we have
 *      to be sure to silence it properly
 *
 *      We indicate that the card is closing to the rest of the
 *      driver.  Otherwise, it is possible that the card may run out
 *      of receive buffers and restart the transceiver while we're
 *      trying to close it.
 *
 *      We abort any receive and transmits going on and then wait until
 *      any pending exec commands have completed in other code threads.
 *      In theory we can't get here while that is true, in practice I am
 *      paranoid
 *
 *      We turn off the interrupt enable for the board to be sure it can't
 *      intefere with other devices.
 */

static int mc32_close(struct net_device *dev)
{
        struct mc32_local *lp = netdev_priv(dev);
        int ioaddr = dev->base_addr;

        u8 regs;
        u16 one=1;

        lp->xceiver_desired_state = HALTED;
        netif_stop_queue(dev);

        /*
         *      Send the indications on command (handy debug check)
         */

        mc32_command(dev, 4, &one, 2);

        /* Shut down the transceiver */

        mc32_halt_transceiver(dev);

        /* Ensure we issue no more commands beyond this point */

        down(&lp->cmd_mutex);

        /* Ok the card is now stopping */

        regs=inb(ioaddr+HOST_CTRL);
        regs&=~HOST_CTRL_INTE;
        outb(regs, ioaddr+HOST_CTRL);

        mc32_flush_rx_ring(dev);
        mc32_flush_tx_ring(dev);

        mc32_update_stats(dev);

        return 0;
}


/**
 *      mc32_get_stats          -       hand back stats to network layer
 *      @dev: The 3c527 card to handle
 *
 *      We've collected all the stats we can in software already. Now
 *      it's time to update those kept on-card and return the lot.
 *
 */

static struct net_device_stats *mc32_get_stats(struct net_device *dev)
{
        mc32_update_stats(dev);
        return &dev->stats;
}


/**
 *      do_mc32_set_multicast_list      -       attempt to update multicasts
 *      @dev: 3c527 device to load the list on
 *      @retry: indicates this is not the first call.
 *
 *
 *      Actually set or clear the multicast filter for this adaptor. The
 *      locking issues are handled by this routine. We have to track
 *      state as it may take multiple calls to get the command sequence
 *      completed. We just keep trying to schedule the loads until we
 *      manage to process them all.
 *
 *      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.
 *
 *      See mc32_update_stats() regards setting the SAV BP bit.
 *
 */

static void do_mc32_set_multicast_list(struct net_device *dev, int retry)
{
        struct mc32_local *lp = netdev_priv(dev);
        u16 filt = (1<<2); /* Save Bad Packets, for stats purposes */

        if ((dev->flags&IFF_PROMISC) ||
            (dev->flags&IFF_ALLMULTI) ||
            dev->mc_count > 10)
                /* Enable promiscuous mode */
                filt |= 1;
        else if(dev->mc_count)
        {
                unsigned char block[62];
                unsigned char *bp;
                struct dev_mc_list *dmc=dev->mc_list;

                int i;

                if(retry==0)
                        lp->mc_list_valid = 0;
                if(!lp->mc_list_valid)
                {
                        block[1]=0;
                        block[0]=dev->mc_count;
                        bp=block+2;

                        for(i=0;i<dev->mc_count;i++)
                        {
                                memcpy(bp, dmc->dmi_addr, 6);
                                bp+=6;
                                dmc=dmc->next;
                        }
                        if(mc32_command_nowait(dev, 2, block, 2+6*dev->mc_count)==-1)
                        {
                                lp->mc_reload_wait = 1;
                                return;
                        }
                        lp->mc_list_valid=1;
                }
        }

        if(mc32_command_nowait(dev, 0, &filt, 2)==-1)
        {
                lp->mc_reload_wait = 1;
        }
        else {
                lp->mc_reload_wait = 0;
        }
}


/**
 *      mc32_set_multicast_list -       queue multicast list update
 *      @dev: The 3c527 to use
 *
 *      Commence loading the multicast list. This is called when the kernel
 *      changes the lists. It will override any pending list we are trying to
 *      load.
 */

static void mc32_set_multicast_list(struct net_device *dev)
{
        do_mc32_set_multicast_list(dev,0);
}


/**
 *      mc32_reset_multicast_list       -       reset multicast list
 *      @dev: The 3c527 to use
 *
 *      Attempt the next step in loading the multicast lists. If this attempt
 *      fails to complete then it will be scheduled and this function called
 *      again later from elsewhere.
 */

static void mc32_reset_multicast_list(struct net_device *dev)
{
        do_mc32_set_multicast_list(dev,1);
}

static void netdev_get_drvinfo(struct net_device *dev,
                               struct ethtool_drvinfo *info)
{
        strcpy(info->driver, DRV_NAME);
        strcpy(info->version, DRV_VERSION);
        sprintf(info->bus_info, "MCA 0x%lx", dev->base_addr);
}

static u32 netdev_get_msglevel(struct net_device *dev)
{
        return mc32_debug;
}

static void netdev_set_msglevel(struct net_device *dev, u32 level)
{
        mc32_debug = level;
}

static const struct ethtool_ops netdev_ethtool_ops = {
        .get_drvinfo            = netdev_get_drvinfo,
        .get_msglevel           = netdev_get_msglevel,
        .set_msglevel           = netdev_set_msglevel,
};

#ifdef MODULE

static struct net_device *this_device;

/**
 *      init_module             -       entry point
 *
 *      Probe and locate a 3c527 card. This really should probe and locate
 *      all the 3c527 cards in the machine not just one of them. Yes you can
 *      insmod multiple modules for now but it's a hack.
 */

int __init init_module(void)
{
        this_device = mc32_probe(-1);
        if (IS_ERR(this_device))
                return PTR_ERR(this_device);
        return 0;
}

/**
 *      cleanup_module  -       free resources for an unload
 *
 *      Unloading time. We release the MCA bus resources and the interrupt
 *      at which point everything is ready to unload. The card must be stopped
 *      at this point or we would not have been called. When we unload we
 *      leave the card stopped but not totally shut down. When the card is
 *      initialized it must be rebooted or the rings reloaded before any
 *      transmit operations are allowed to start scribbling into memory.
 */

void __exit cleanup_module(void)
{
        unregister_netdev(this_device);
        cleanup_card(this_device);
        free_netdev(this_device);
}

#endif /* MODULE */