Il CD di internet/CD.iso/SOURCE/KERNEL-S/V1.2/LINUX-1.2/LINUX-1/linux/drivers/net/de600.c

C/C++ Source or Header | 1995-02-07 | 22.1 KB | 849 lines

static char *version =
    "de600.c: $Revision: 1.40 $,  Bjorn Ekwall ([e-mail])\n";
/*
 *    de600.c
 *
 *    Linux driver for the D-Link DE-600 Ethernet pocket adapter.
 *
 *    Portions (C) Copyright 1993, 1994 by Bjorn Ekwall
 *    The Author may be reached as [e-mail]
 *
 *    Based on adapter information gathered from DE600.ASM by D-Link Inc.,
 *    as included on disk C in the v.2.11 of PC/TCP from FTP Software.
 *    For DE600.asm:
 *        Portions (C) Copyright 1990 D-Link, Inc.
 *        Copyright, 1988-1992, Russell Nelson, Crynwr Software
 *
 *    Adapted to the sample network driver core for linux,
 *    written by: Donald Becker <[e-mail]>
 *    C/O Supercomputing Research Ctr., 17100 Science Dr., Bowie MD 20715
 *
 *    compile-command:
 *    "gcc -D__KERNEL__  -Wall -Wstrict-prototypes -O6 -fomit-frame-pointer \
 *     -m486 -c de600.c
 *
 **************************************************************/
/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2, or (at your option)
 *    any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 **************************************************************/
/* Add another "; SLOW_DOWN_IO" here if your adapter won't work OK: */
#define DE600_SLOW_DOWN SLOW_DOWN_IO; SLOW_DOWN_IO; SLOW_DOWN_IO

 /*
 * If you still have trouble reading/writing to the adapter,
 * modify the following "#define": (see <asm/io.h> for more info)
#define REALLY_SLOW_IO
 */
#define SLOW_IO_BY_JUMPING /* Looks "better" than dummy write to port 0x80 :-) */

/*
 * If you want to enable automatic continuous checking for the DE600,
 * keep this #define enabled.
 * It doesn't cost much per packet, so I think it is worth it!
 * If you disagree, comment away the #define, and live with it...
 *
 */
#define CHECK_LOST_DE600

/*
 * Enable this #define if you want the adapter to do a "ifconfig down" on
 * itself when we have detected that something is possibly wrong with it.
 * The default behaviour is to retry with "adapter_init()" until success.
 * This should be used for debugging purposes only.
 * (Depends on the CHECK_LOST_DE600 above)
 *
 */
#define SHUTDOWN_WHEN_LOST

/*
 * See comment at "de600_rspace()"!
 * This is an *ugly* hack, but for now it achieves its goal of
 * faking a TCP flow-control that will not flood the poor DE600.
 *
 * Tricks TCP to announce a small max window (max 2 fast packets please :-)
 *
 * Comment away at your own risk!
 *
 * Update: Use the more general per-device maxwindow parameter instead.
 */
#undef FAKE_SMALL_MAX

/* use 0 for production, 1 for verification, >2 for debug */
#ifdef DE600_DEBUG
#define PRINTK(x) if (de600_debug >= 2) printk x
#else
#define DE600_DEBUG 0
#define PRINTK(x) /**/
#endif
unsigned int de600_debug = DE600_DEBUG;

#ifdef MODULE
#include <linux/module.h>
#include <linux/version.h>
#endif

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

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

#ifdef FAKE_SMALL_MAX
static unsigned long de600_rspace(struct sock *sk);
#include "../../net/inet/sock.h"
#endif

#define netstats enet_statistics
typedef unsigned char byte;

/**************************************************
 *                                                *
 * Definition of D-Link Ethernet Pocket adapter   *
 *                                                *
 **************************************************/
/*
 * D-Link Ethernet pocket adapter ports
 */
/*
 * OK, so I'm cheating, but there are an awful lot of
 * reads and writes in order to get anything in and out
 * of the DE-600 with 4 bits at a time in the parallel port,
 * so every saved instruction really helps :-)
 *
 * That is, I don't care what the device struct says
 * but hope that Space.c will keep the rest of the drivers happy.
 */
#ifndef DE600_IO
#define DE600_IO 0x378
#endif

#define DATA_PORT    (DE600_IO)
#define STATUS_PORT    (DE600_IO + 1)
#define COMMAND_PORT    (DE600_IO + 2)

#ifndef DE600_IRQ
#define DE600_IRQ    7
#endif
/*
 * It really should look like this, and autoprobing as well...
 *
#define DATA_PORT    (dev->base_addr + 0)
#define STATUS_PORT    (dev->base_addr + 1)
#define COMMAND_PORT    (dev->base_addr + 2)
#define DE600_IRQ    dev->irq
 */

/*
 * D-Link COMMAND_PORT commands
 */
#define SELECT_NIC    0x04 /* select Network Interface Card */
#define SELECT_PRN    0x1c /* select Printer */
#define NML_PRN        0xec /* normal Printer situation */
#define IRQEN        0x10 /* enable IRQ line */

/*
 * D-Link STATUS_PORT
 */
#define RX_BUSY        0x80
#define RX_GOOD        0x40
#define TX_FAILED16    0x10
#define TX_BUSY        0x08

/*
 * D-Link DATA_PORT commands
 * command in low 4 bits
 * data in high 4 bits
 * select current data nibble with HI_NIBBLE bit
 */
#define WRITE_DATA    0x00 /* write memory */
#define READ_DATA    0x01 /* read memory */
#define STATUS        0x02 /* read  status register */
#define COMMAND        0x03 /* write command register (see COMMAND below) */
#define NULL_COMMAND    0x04 /* null command */
#define RX_LEN        0x05 /* read  received packet length */
#define TX_ADDR        0x06 /* set adapter transmit memory address */
#define RW_ADDR        0x07 /* set adapter read/write memory address */
#define HI_NIBBLE    0x08 /* read/write the high nibble of data,
                or-ed with rest of command */

/*
 * command register, accessed through DATA_PORT with low bits = COMMAND
 */
#define RX_ALL        0x01 /* PROMISCUOUS */
#define RX_BP        0x02 /* default: BROADCAST & PHYSICAL ADDRESS */
#define RX_MBP        0x03 /* MULTICAST, BROADCAST & PHYSICAL ADDRESS */

#define TX_ENABLE    0x04 /* bit 2 */
#define RX_ENABLE    0x08 /* bit 3 */

#define RESET        0x80 /* set bit 7 high */
#define STOP_RESET    0x00 /* set bit 7 low */

/*
 * data to command register
 * (high 4 bits in write to DATA_PORT)
 */
#define RX_PAGE2_SELECT    0x10 /* bit 4, only 2 pages to select */
#define RX_BASE_PAGE    0x20 /* bit 5, always set when specifying RX_ADDR */
#define FLIP_IRQ    0x40 /* bit 6 */

/*
 * D-Link adapter internal memory:
 *
 * 0-2K 1:st transmit page (send from pointer up to 2K)
 * 2-4K    2:nd transmit page (send from pointer up to 4K)
 *
 * 4-6K 1:st receive page (data from 4K upwards)
 * 6-8K 2:nd receive page (data from 6K upwards)
 *
 * 8K+    Adapter ROM (contains magic code and last 3 bytes of Ethernet address)
 */
#define MEM_2K        0x0800 /* 2048 */
#define MEM_4K        0x1000 /* 4096 */
#define MEM_6K        0x1800 /* 6144 */
#define NODE_ADDRESS    0x2000 /* 8192 */

#define RUNT 60        /* Too small Ethernet packet */

/**************************************************
 *                                                *
 *             End of definition                  *
 *                                                *
 **************************************************/

/*
 * Index to functions, as function prototypes.
 */
/* Routines used internally. (See "convenience macros") */
static byte    de600_read_status(struct device *dev);
static byte    de600_read_byte(unsigned char type, struct device *dev);

/* Put in the device structure. */
static int    de600_open(struct device *dev);
static int    de600_close(struct device *dev);
static struct netstats *get_stats(struct device *dev);
static int    de600_start_xmit(struct sk_buff *skb, struct device *dev);

/* Dispatch from interrupts. */
static void    de600_interrupt(int irq, struct pt_regs *regs);
static int    de600_tx_intr(struct device *dev, int irq_status);
static void    de600_rx_intr(struct device *dev);

/* Initialization */
static void    trigger_interrupt(struct device *dev);
int        de600_probe(struct device *dev);
static int    adapter_init(struct device *dev);

/*
 * D-Link driver variables:
 */
static volatile int        rx_page        = 0;

#define TX_PAGES 2
static volatile int        tx_fifo[TX_PAGES];
static volatile int        tx_fifo_in = 0;
static volatile int        tx_fifo_out = 0;
static volatile int        free_tx_pages = TX_PAGES;
static int            was_down = 0;

/*
 * Convenience macros/functions for D-Link adapter
 */

#define select_prn() outb_p(SELECT_PRN, COMMAND_PORT); DE600_SLOW_DOWN
#define select_nic() outb_p(SELECT_NIC, COMMAND_PORT); DE600_SLOW_DOWN

/* Thanks for hints from Mark Burton <[e-mail]> */
#define de600_put_byte(data) ( \
    outb_p(((data) << 4)   | WRITE_DATA            , DATA_PORT), \
    outb_p(((data) & 0xf0) | WRITE_DATA | HI_NIBBLE, DATA_PORT))

/*
 * The first two outb_p()'s below could perhaps be deleted if there
 * would be more delay in the last two. Not certain about it yet...
 */
#define de600_put_command(cmd) ( \
    outb_p(( rx_page        << 4)   | COMMAND            , DATA_PORT), \
    outb_p(( rx_page        & 0xf0) | COMMAND | HI_NIBBLE, DATA_PORT), \
    outb_p(((rx_page | cmd) << 4)   | COMMAND            , DATA_PORT), \
    outb_p(((rx_page | cmd) & 0xf0) | COMMAND | HI_NIBBLE, DATA_PORT))

#define de600_setup_address(addr,type) ( \
    outb_p((((addr) << 4) & 0xf0) | type            , DATA_PORT), \
    outb_p(( (addr)       & 0xf0) | type | HI_NIBBLE, DATA_PORT), \
    outb_p((((addr) >> 4) & 0xf0) | type            , DATA_PORT), \
    outb_p((((addr) >> 8) & 0xf0) | type | HI_NIBBLE, DATA_PORT))

#define rx_page_adr() ((rx_page & RX_PAGE2_SELECT)?(MEM_6K):(MEM_4K))

/* Flip bit, only 2 pages */
#define next_rx_page() (rx_page ^= RX_PAGE2_SELECT)

#define tx_page_adr(a) (((a) + 1) * MEM_2K)

static inline byte
de600_read_status(struct device *dev)
{
    byte status;

    outb_p(STATUS, DATA_PORT);
    status = inb(STATUS_PORT);
    outb_p(NULL_COMMAND | HI_NIBBLE, DATA_PORT);

    return status;
}

static inline byte
de600_read_byte(unsigned char type, struct device *dev) { /* dev used by macros */
    byte lo;

    (void)outb_p((type), DATA_PORT);
    lo = ((unsigned char)inb(STATUS_PORT)) >> 4;
    (void)outb_p((type) | HI_NIBBLE, DATA_PORT);
    return ((unsigned char)inb(STATUS_PORT) & (unsigned char)0xf0) | lo;
}

/*
 * Open/initialize the board.  This is called (in the current kernel)
 * after booting when 'ifconfig <dev->name> $IP_ADDR' is run (in rc.inet1).
 *
 * 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 a non-reboot way to recover if something goes wrong.
 */
static int
de600_open(struct device *dev)
{
    if (request_irq(DE600_IRQ, de600_interrupt, 0, "de600")) {
        printk ("%s: unable to get IRQ %d\n", dev->name, DE600_IRQ);
        return 1;
    }
    irq2dev_map[DE600_IRQ] = dev;

#ifdef MODULE
    MOD_INC_USE_COUNT;
#endif
    dev->start = 1;
    if (adapter_init(dev)) {
        return 1;
    }

    return 0;
}

/*
 * The inverse routine to de600_open().
 */
static int
de600_close(struct device *dev)
{
    select_nic();
    rx_page = 0;
    de600_put_command(RESET);
    de600_put_command(STOP_RESET);
    de600_put_command(0);
    select_prn();

    if (dev->start) {
        free_irq(DE600_IRQ);
        irq2dev_map[DE600_IRQ] = NULL;
        dev->start = 0;
#ifdef MODULE
        MOD_DEC_USE_COUNT;
#endif
    }
    return 0;
}

static struct netstats *
get_stats(struct device *dev)
{
    return (struct netstats *)(dev->priv);
}

static inline void
trigger_interrupt(struct device *dev)
{
    de600_put_command(FLIP_IRQ);
    select_prn();
    DE600_SLOW_DOWN;
    select_nic();
    de600_put_command(0);
}

/*
 * Copy a buffer to the adapter transmit page memory.
 * Start sending.
 */
static int
de600_start_xmit(struct sk_buff *skb, struct device *dev)
{
    int    transmit_from;
    int    len;
    int    tickssofar;
    byte    *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;
    }

    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. */
        if (adapter_init(dev)) {
            return 1;
        }
    }

    /* Start real output */
    PRINTK(("de600_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 */

#ifdef CHECK_LOST_DE600
    /* This costs about 40 instructions per packet... */
    de600_setup_address(NODE_ADDRESS, RW_ADDR);
    de600_read_byte(READ_DATA, dev);
    if (was_down || (de600_read_byte(READ_DATA, dev) != 0xde)) {
        if (adapter_init(dev)) {
            sti();
            return 1;
        }
    }
#endif

    de600_setup_address(transmit_from, RW_ADDR);
    for ( ; len > 0; --len, ++buffer)
        de600_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 a faked interrupt */
        de600_setup_address(transmit_from, TX_ADDR);
        de600_put_command(TX_ENABLE);
    }
    else {
        dev->tbusy = !free_tx_pages;
        select_prn();
    }

    sti(); /* interrupts back on */

#ifdef FAKE_SMALL_MAX
    /* This will "patch" the socket TCP proto at an early moment */
    if (skb->sk && (skb->sk->protocol == IPPROTO_TCP) &&
        (skb->sk->prot->rspace != &de600_rspace))
        skb->sk->prot->rspace = de600_rspace; /* Ugh! */
#endif

    dev_kfree_skb (skb, FREE_WRITE);

    return 0;
}

/*
 * The typical workload of the driver:
 * Handle the network interface interrupts.
 */
static void
de600_interrupt(int irq, struct pt_regs * regs)
{
    struct device    *dev = irq2dev_map[irq];
    byte        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) || (DE600_IRQ != irq)) {
        printk("%s: bogus interrupt %d\n", dev?dev->name:"DE-600", irq);
        return;
    }

    dev->interrupt = 1;
    select_nic();
    irq_status = de600_read_status(dev);

    do {
        PRINTK(("de600_interrupt (%02X)\n", irq_status));

        if (irq_status & RX_GOOD)
            de600_rx_intr(dev);
        else if (!(irq_status & RX_BUSY))
            de600_put_command(RX_ENABLE);

        /* Any transmission in progress? */
        if (free_tx_pages < TX_PAGES)
            retrig = de600_tx_intr(dev, irq_status);
        else
            retrig = 0;

        irq_status = de600_read_status(dev);
    } while ( (irq_status & RX_GOOD) || ((++boguscount < 100) && 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
de600_tx_intr(struct device *dev, int irq_status)
{
    /*
     * Returns 1 if tx still not done
     */

    mark_bh(NET_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;
        de600_setup_address(tx_fifo[tx_fifo_out], TX_ADDR);
        de600_put_command(TX_ENABLE);
        return 1;
    }
    /* else */

    return 0;
}

/*
 * We have a good packet, get it out of the adapter.
 */
static void
de600_rx_intr(struct device *dev)
{
    struct sk_buff    *skb;
    int        i;
    int        read_from;
    int        size;
    register unsigned char    *buffer;

    cli();
    /* Get size of received packet */
    size = de600_read_byte(RX_LEN, dev);    /* low byte */
    size += (de600_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();
    de600_put_command(RX_ENABLE);
    sti();

    if ((size < 32)  ||  (size > 1535)) {
        printk("%s: Bogus packet size %d.\n", dev->name, size);
        if (size > 10000)
            adapter_init(dev);
        return;
    }

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

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

    /* copy the packet into the buffer */
    de600_setup_address(read_from, RW_ADDR);
    for (i = size; i > 0; --i, ++buffer)
        *buffer = de600_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
de600_probe(struct device *dev)
{
    int    i;
    static struct netstats de600_netstats;
    /*dev->priv = kmalloc(sizeof(struct netstats), GFP_KERNEL);*/

    printk("%s: D-Link DE-600 pocket adapter", dev->name);
    /* Alpha testers must have the version number to report bugs. */
    if (de600_debug > 1)
        printk(version);

    /* probe for adapter */
    rx_page = 0;
    select_nic();
    (void)de600_read_status(dev);
    de600_put_command(RESET);
    de600_put_command(STOP_RESET);
    if (de600_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 */
    de600_setup_address(NODE_ADDRESS, RW_ADDR);
    for (i = 0; i < ETH_ALEN; i++) {
        dev->dev_addr[i] = de600_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;
    }

#if 0 /* Not yet */
    if (check_region(DE600_IO, 3)) {
        printk(", port 0x%x busy\n", DE600_IO);
        return EBUSY;
    }
#endif
    request_region(DE600_IO, 3, "de600");

    printk(", Ethernet Address: %02X", dev->dev_addr[0]);
    for (i = 1; i < ETH_ALEN; i++)
        printk(":%02X",dev->dev_addr[i]);
    printk("\n");

    /* Initialize the device structure. */
    /*dev->priv = kmalloc(sizeof(struct netstats), GFP_KERNEL);*/
    dev->priv = &de600_netstats;

    memset(dev->priv, 0, sizeof(struct netstats));
    dev->get_stats = get_stats;

    dev->open = de600_open;
    dev->stop = de600_close;
    dev->hard_start_xmit = &de600_start_xmit;

    ether_setup(dev);

    select_prn();
    return 0;
}

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

    save_flags(flags);
    cli();

    select_nic();
    rx_page = 0; /* used by RESET */
    de600_put_command(RESET);
    de600_put_command(STOP_RESET);
#ifdef CHECK_LOST_DE600
    /* Check if it is still there... */
    /* Get the some bytes of the adapter ethernet address from the ROM */
    de600_setup_address(NODE_ADDRESS, RW_ADDR);
    de600_read_byte(READ_DATA, dev);
    if ((de600_read_byte(READ_DATA, dev) != 0xde) ||
        (de600_read_byte(READ_DATA, dev) != 0x15)) {
    /* was: if (de600_read_status(dev) & 0xf0) { */
        printk("Something has happened to the DE-600!  Please check it"
#ifdef SHUTDOWN_WHEN_LOST
            " and do a new ifconfig"
#endif /* SHUTDOWN_WHEN_LOST */
            "!\n");
#ifdef SHUTDOWN_WHEN_LOST
        /* Goodbye, cruel world... */
        dev->flags &= ~IFF_UP;
        de600_close(dev);
#endif /* SHUTDOWN_WHEN_LOST */
        was_down = 1;
        dev->tbusy = 1;        /* Transmit busy...  */
        return 1; /* failed */
    }
#endif /* CHECK_LOST_DE600 */
    if (was_down) {
        printk("Thanks, I feel much better now!\n");
        was_down = 0;
    }

    dev->tbusy = 0;        /* Transmit busy...  */
    dev->interrupt = 0;
    tx_fifo_in = 0;
    tx_fifo_out = 0;
    free_tx_pages = TX_PAGES;

    /* set the ether address. */
    de600_setup_address(NODE_ADDRESS, RW_ADDR);
    for (i = 0; i < ETH_ALEN; i++)
        de600_put_byte(dev->dev_addr[i]);

    /* where to start saving incoming packets */
    rx_page = RX_BP | RX_BASE_PAGE;
    de600_setup_address(MEM_4K, RW_ADDR);
    /* Enable receiver */
    de600_put_command(RX_ENABLE);
    select_prn();
    restore_flags(flags);

    return 0; /* OK */
}

#ifdef FAKE_SMALL_MAX
/*
 *    The new router code (coming soon 8-) ) will fix this properly.
 */
#define DE600_MIN_WINDOW 1024
#define DE600_MAX_WINDOW 2048
#define DE600_TCP_WINDOW_DIFF 1024
/*
 * Copied from "net/inet/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 keep up with a net saturated
 *  with packets homing in on it :-( )
 *
 * 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!
 *
 * Note that the returned window info will never be smaller than
 * DE600_MIN_WINDOW, i.e. 1024
 * This differs from the standard function, that can return an
 * arbitrarily small window!
 */
#define min(a,b)    ((a)<(b)?(a):(b))
static unsigned long
de600_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 = DE600_MAX_WINDOW - DE600_TCP_WINDOW_DIFF;
 */

    if (sk->rmem_alloc >= sk->rcvbuf-2*DE600_MIN_WINDOW) return(0);
    amt = min((sk->rcvbuf-sk->rmem_alloc)/2/*-DE600_MIN_WINDOW*/, DE600_MAX_WINDOW);
    if (amt < 0) return(0);
    return(amt);
  }
  return(0);
}
#endif

#ifdef MODULE
char kernel_version[] = UTS_RELEASE;
static char nullname[8];
static struct device de600_dev = {
    nullname, 0, 0, 0, 0, 0, 0, 0, 0, 0, NULL, de600_probe };

int
init_module(void)
{
    if (register_netdev(&de600_dev) != 0)
        return -EIO;
    return 0;
}

void
cleanup_module(void)
{
    unregister_netdev(&de600_dev);
    release_region(DE600_IO, 3);
}
#endif /* MODULE */