Subversion Repositories or1k

/* atp.c: Attached (pocket) ethernet adapter driver for linux. */

/*

        This is a driver for commonly OEMed pocket (parallel port)

        ethernet adapters based on the Realtek RTL8002 and RTL8012 chips.

        Written 1993-95,1997 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 becker@CESDIS.gsfc.nasa.gov, or C/O

        Center of Excellence in Space Data and Information Sciences

                Code 930.5, Goddard Space Flight Center, Greenbelt MD 20771

        The timer-based reset code was written by Bill Carlson, wwc@super.org.

*/

static const char *version =

        "atp.c:v1.08 4/1/97 Donald Becker (becker@cesdis.gsfc.nasa.gov)\n";

/* Operational parameters that may be safely changed. */

/* Time in jiffies before concluding the transmitter is hung. */

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

/*

        This file is a device driver for the RealTek (aka AT-Lan-Tec) pocket

        ethernet adapter.  This is a common low-cost OEM pocket ethernet

        adapter, sold under many names.

  Sources:

        This driver was written from the packet driver assembly code provided by

        Vincent Bono of AT-Lan-Tec.      Ever try to figure out how a complicated

        device works just from the assembly code?  It ain't pretty.  The following

        description is written based on guesses and writing lots of special-purpose

        code to test my theorized operation.

        In 1997 Realtek made available the documentation for the second generation

        RTL8012 chip, which has lead to several driver improvements.

          http://www.realtek.com.tw/cn/cn.html

                                        Theory of Operation

        The RTL8002 adapter seems to be built around a custom spin of the SEEQ

        controller core.  It probably has a 16K or 64K internal packet buffer, of

        which the first 4K is devoted to transmit and the rest to receive.

        The controller maintains the queue of received packet and the packet buffer

        access pointer internally, with only 'reset to beginning' and 'skip to next

        packet' commands visible.  The transmit packet queue holds two (or more?)

        packets: both 'retransmit this packet' (due to collision) and 'transmit next

        packet' commands must be started by hand.

        The station address is stored in a standard bit-serial EEPROM which must be

        read (ughh) by the device driver.  (Provisions have been made for

        substituting a 74S288 PROM, but I haven't gotten reports of any models

        using it.)  Unlike built-in devices, a pocket adapter can temporarily lose

        power without indication to the device driver.  The major effect is that

        the station address, receive filter (promiscuous, etc.) and transceiver

        must be reset.

        The controller itself has 16 registers, some of which use only the lower

        bits.  The registers are read and written 4 bits at a time.  The four bit

        register address is presented on the data lines along with a few additional

        timing and control bits.  The data is then read from status port or written

        to the data port.

        Correction: the controller has two banks of 16 registers.  The second

        bank contains only the multicast filter table (now used) and the EEPROM

        access registers.

        Since the bulk data transfer of the actual packets through the slow

        parallel port dominates the driver's running time, four distinct data

        (non-register) transfer modes are provided by the adapter, two in each

        direction.  In the first mode timing for the nibble transfers is

        provided through the data port.  In the second mode the same timing is

        provided through the control port.  In either case the data is read from

        the status port and written to the data port, just as it is accessing

        registers.

        In addition to the basic data transfer methods, several more are modes are

        created by adding some delay by doing multiple reads of the data to allow

        it to stabilize.  This delay seems to be needed on most machines.

        The data transfer mode is stored in the 'dev->if_port' field.  Its default

        value is '4'.  It may be overridden at boot-time using the third parameter

        to the "ether=..." initialization.

        The header file <atp.h> provides inline functions that encapsulate the

        register and data access methods.  These functions are hand-tuned to

        generate reasonable object code.  This header file also documents my

        interpretations of the device registers.

*/

#include <linux/config.h>

#ifdef MODULE

#include <linux/module.h>

#include <linux/version.h>

#else

#define MOD_INC_USE_COUNT

#define MOD_DEC_USE_COUNT

#endif

#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 <asm/io.h>

#include <asm/dma.h>

#include <linux/errno.h>

#include <linux/netdevice.h>

#include <linux/etherdevice.h>

#include <linux/skbuff.h>

#include "atp.h"

/* Kernel compatibility defines, common to David Hind's PCMCIA package.

   This is only in the support-all-kernels source code. */

#include <linux/version.h>              /* Evil, but neccessary */

#if defined (LINUX_VERSION_CODE) && LINUX_VERSION_CODE < 0x10300

#define RUN_AT(x) (x)                   /* What to put in timer->expires.  */

#define DEV_ALLOC_SKB(len) alloc_skb(len, GFP_ATOMIC)

#define virt_to_bus(addr)  ((unsigned long)addr)

#define bus_to_virt(addr) ((void*)addr)

#else  /* 1.3.0 and later */

#define RUN_AT(x) (jiffies + (x))

#define DEV_ALLOC_SKB(len) dev_alloc_skb(len + 2)

#endif

#if defined (LINUX_VERSION_CODE) && LINUX_VERSION_CODE < 0x10338

#ifdef MODULE

#if !defined(CONFIG_MODVERSIONS) && !defined(__NO_VERSION__)

char kernel_version[] = UTS_RELEASE;

#endif

#else

#undef MOD_INC_USE_COUNT

#define MOD_INC_USE_COUNT

#undef MOD_DEC_USE_COUNT

#define MOD_DEC_USE_COUNT

#endif

#endif /* 1.3.38 */

#if (LINUX_VERSION_CODE >= 0x10344)

#define NEW_MULTICAST

#include <linux/delay.h>

#endif

#ifdef SA_SHIRQ

#define FREE_IRQ(irqnum, dev) free_irq(irqnum, dev)

#define REQUEST_IRQ(i,h,f,n, instance) request_irq(i,h,f,n, instance)

#define IRQ(irq, dev_id, pt_regs) (irq, dev_id, pt_regs)

#else

#define FREE_IRQ(irqnum, dev) free_irq(irqnum)

#define REQUEST_IRQ(i,h,f,n, instance) request_irq(i,h,f,n)

#define IRQ(irq, dev_id, pt_regs) (irq, pt_regs)

#endif

/* End of kernel compatibility defines. */

/* use 0 for production, 1 for verification, >2 for debug */

#ifndef NET_DEBUG

#define NET_DEBUG 1

#endif

static unsigned int net_debug = NET_DEBUG;

/* The number of low I/O ports used by the ethercard. */

#define ETHERCARD_TOTAL_SIZE    3

/* Sequence to switch an 8012 from printer mux to ethernet mode. */

static char mux_8012[] = { 0xff, 0xf7, 0xff, 0xfb, 0xf3, 0xfb, 0xff, 0xf7,};

/* This code, written by wwc@super.org, resets the adapter every

   TIMED_CHECKER ticks.  This recovers from an unknown error which

   hangs the device. */

#define TIMED_CHECKER (HZ/4)

#ifdef TIMED_CHECKER

#include <linux/timer.h>

static void atp_timed_checker(unsigned long ignored);

#endif

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

extern int atp_init(struct device *dev);

static int atp_probe1(struct device *dev, short ioaddr);

static void get_node_ID(struct device *dev);

static unsigned short eeprom_op(short ioaddr, unsigned int cmd);

static int net_open(struct device *dev);

static void hardware_init(struct device *dev);

static void write_packet(short ioaddr, int length, unsigned char *packet, int mode);

static void trigger_send(short ioaddr, int length);

static int      net_send_packet(struct sk_buff *skb, struct device *dev);

static void net_interrupt IRQ(int irq, void *dev_id, struct pt_regs *regs);

static void net_rx(struct device *dev);

static void read_block(short ioaddr, int length, unsigned char *buffer, int data_mode);

static int net_close(struct device *dev);

static struct enet_statistics *net_get_stats(struct device *dev);

#ifdef NEW_MULTICAST

static void set_rx_mode_8002(struct device *dev);

static void set_rx_mode_8012(struct device *dev);

#else

static void set_rx_mode_8002(struct device *dev, int num_addrs, void *addrs);

static void set_rx_mode_8012(struct device *dev, int num_addrs, void *addrs);

#endif

/* A list of all installed ATP devices, for removing the driver module. */

static struct device *root_atp_dev = NULL;

/* Check for a network adapter 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

atp_init(struct device *dev)

{

        int *port, ports[] = {0x378, 0x278, 0x3bc, 0};

        int base_addr = dev ? dev->base_addr : 0;

        if (base_addr > 0x1ff)          /* Check a single specified location. */

                return atp_probe1(dev, base_addr);

        else if (base_addr == 1)        /* Don't probe at all. */

                return ENXIO;

        for (port = ports; *port; port++) {

                int ioaddr = *port;

                outb(0x57, ioaddr + PAR_DATA);

                if (inb(ioaddr + PAR_DATA) != 0x57)

                        continue;

                if (atp_probe1(dev, ioaddr) == 0)

                        return 0;

        }

        return ENODEV;

}

static int atp_probe1(struct device *dev, short ioaddr)

{

        struct net_local *lp;

        int saved_ctrl_reg, status, i;

        outb(0xff, ioaddr + PAR_DATA);

        /* Save the original value of the Control register, in case we guessed

           wrong. */

        saved_ctrl_reg = inb(ioaddr + PAR_CONTROL);

        /* IRQEN=0, SLCTB=high INITB=high, AUTOFDB=high, STBB=high. */

        outb(0x04, ioaddr + PAR_CONTROL);

        /* Turn off the printer multiplexer on the 8012. */

        for (i = 0; i < 8; i++)

                outb(mux_8012[i], ioaddr + PAR_DATA);

        write_reg_high(ioaddr, CMR1, CMR1h_RESET);

        eeprom_delay(2048);

        status = read_nibble(ioaddr, CMR1);

        if ((status & 0x78) != 0x08) {

                /* The pocket adapter probe failed, restore the control register. */

                outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);

                return 1;

        }

        status = read_nibble(ioaddr, CMR2_h);

        if ((status & 0x78) != 0x10) {

                outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);

                return 1;

        }

        dev = init_etherdev(dev, sizeof(struct net_local));

        /* Find the IRQ used by triggering an interrupt. */

        write_reg_byte(ioaddr, CMR2, 0x01);                     /* No accept mode, IRQ out. */

        write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);  /* Enable Tx and Rx. */

        /* Omit autoIRQ routine for now. Use "table lookup" instead.  Uhgggh. */

        if (ioaddr == 0x378)

                dev->irq = 7;

        else

                dev->irq = 5;

        write_reg_high(ioaddr, CMR1, CMR1h_TxRxOFF); /* Disable Tx and Rx units. */

        write_reg(ioaddr, CMR2, CMR2_NULL);

        dev->base_addr = ioaddr;

        /* Read the station address PROM.  */

        get_node_ID(dev);

        printk("%s: Pocket adapter found at %#3lx, IRQ %d, SAPROM "

                   "%02X:%02X:%02X:%02X:%02X:%02X.\n", dev->name, dev->base_addr,

                   dev->irq, dev->dev_addr[0], dev->dev_addr[1], dev->dev_addr[2],

                   dev->dev_addr[3], dev->dev_addr[4], dev->dev_addr[5]);

        /* Reset the ethernet hardware and activate the printer pass-through. */

    write_reg_high(ioaddr, CMR1, CMR1h_RESET | CMR1h_MUX);

        if (net_debug)

                printk(version);

        /* Initialize the device structure. */

        ether_setup(dev);

        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));

        lp = (struct net_local *)dev->priv;

        lp->chip_type = RTL8002;

        lp->addr_mode = CMR2h_Normal;

        lp->next_module = root_atp_dev;

        root_atp_dev = dev;

        /* For the ATP adapter the "if_port" is really the data transfer mode. */

        dev->if_port = (dev->mem_start & 0xf) ? (dev->mem_start & 0x7) : 4;

        if (dev->mem_end & 0xf)

                net_debug = dev->mem_end & 7;

        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 =

          lp->chip_type == RTL8002 ? &set_rx_mode_8002 : &set_rx_mode_8012;

        return 0;

}

/* Read the station address PROM, usually a word-wide EEPROM. */

static void get_node_ID(struct device *dev)

{

        short ioaddr = dev->base_addr;

        int sa_offset = 0;

        int i;

        write_reg(ioaddr, CMR2, CMR2_EEPROM);     /* Point to the EEPROM control registers. */

        /* Some adapters have the station address at offset 15 instead of offset

           zero.  Check for it, and fix it if needed. */

        if (eeprom_op(ioaddr, EE_READ(0)) == 0xffff)

                sa_offset = 15;

        for (i = 0; i < 3; i++)

                ((unsigned short *)dev->dev_addr)[i] =

                        ntohs(eeprom_op(ioaddr, EE_READ(sa_offset + i)));

        write_reg(ioaddr, CMR2, CMR2_NULL);

}

/*

  An EEPROM read command starts by shifting out 0x60+address, and then

  shifting in the serial data. See the NatSemi databook for details.

 *                 ________________

 * CS : __|

 *                         ___     ___

 * CLK: ______|   |___|   |

 *               __ _______ _______

 * DI :  __X_______X_______X

 * DO :  _________X_______X

 */

static unsigned short eeprom_op(short ioaddr, unsigned int cmd)

{

        unsigned eedata_out = 0;

        int num_bits = EE_CMD_SIZE;

        while (--num_bits >= 0) {

                char outval = test_bit(num_bits, &cmd) ? EE_DATA_WRITE : 0;

                write_reg_high(ioaddr, PROM_CMD, outval | EE_CLK_LOW);

                eeprom_delay(5);

                write_reg_high(ioaddr, PROM_CMD, outval | EE_CLK_HIGH);

                eedata_out <<= 1;

                if (read_nibble(ioaddr, PROM_DATA) & EE_DATA_READ)

                        eedata_out++;

                eeprom_delay(5);

        }

        write_reg_high(ioaddr, PROM_CMD, EE_CLK_LOW & ~EE_CS);

        return eedata_out;

}

/* Open/initialize the board.  This is called (in the current kernel)

   sometime after booting when the 'ifconfig' program is run.

   This routine sets 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.

   This is an attachable device: if there is no dev->priv entry then it wasn't

   probed for at boot-time, and we need to probe for it again.

   */

static int net_open(struct device *dev)

{

        struct net_local *lp = (struct net_local *)dev->priv;

        /* The interrupt line is turned off (tri-stated) when the device isn't in

           use.  That's especially important for "attached" interfaces where the

           port or interrupt may be shared. */

#ifndef SA_SHIRQ

        if (irq2dev_map[dev->irq] != 0

                || (irq2dev_map[dev->irq] = dev) == 0

                || REQUEST_IRQ(dev->irq, &net_interrupt, 0, "ATP", dev)) {

                return -EAGAIN;

        }

#else

        if (request_irq(dev->irq, &net_interrupt, 0, "ATP Ethernet", dev))

                return -EAGAIN;

#endif

        MOD_INC_USE_COUNT;

        hardware_init(dev);

        dev->start = 1;

        init_timer(&lp->timer);

        lp->timer.expires = RUN_AT(TIMED_CHECKER);

        lp->timer.data = (unsigned long)dev;

        lp->timer.function = &atp_timed_checker;    /* timer handler */

        add_timer(&lp->timer);

        return 0;

}

/* This routine resets the hardware.  We initialize everything, assuming that

   the hardware may have been temporarily detached. */

static void hardware_init(struct device *dev)

{

        struct net_local *lp = (struct net_local *)dev->priv;

        int ioaddr = dev->base_addr;

    int i;

        /* Turn off the printer multiplexer on the 8012. */

        for (i = 0; i < 8; i++)

                outb(mux_8012[i], ioaddr + PAR_DATA);

        write_reg_high(ioaddr, CMR1, CMR1h_RESET);

    for (i = 0; i < 6; i++)

                write_reg_byte(ioaddr, PAR0 + i, dev->dev_addr[i]);

        write_reg_high(ioaddr, CMR2, lp->addr_mode);

        if (net_debug > 2) {

                printk("%s: Reset: current Rx mode %d.\n", dev->name,

                           (read_nibble(ioaddr, CMR2_h) >> 3) & 0x0f);

        }

    write_reg(ioaddr, CMR2, CMR2_IRQOUT);

    write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);

        /* Enable the interrupt line from the serial port. */

        outb(Ctrl_SelData + Ctrl_IRQEN, ioaddr + PAR_CONTROL);

        /* Unmask the interesting interrupts. */

    write_reg(ioaddr, IMR, ISR_RxOK | ISR_TxErr | ISR_TxOK);

    write_reg_high(ioaddr, IMR, ISRh_RxErr);

        lp->tx_unit_busy = 0;

    lp->pac_cnt_in_tx_buf = 0;

        lp->saved_tx_size = 0;

        dev->tbusy = 0;

        dev->interrupt = 0;

}

static void trigger_send(short ioaddr, int length)

{

        write_reg_byte(ioaddr, TxCNT0, length & 0xff);

        write_reg(ioaddr, TxCNT1, length >> 8);

        write_reg(ioaddr, CMR1, CMR1_Xmit);

}

static void write_packet(short ioaddr, int length, unsigned char *packet, int data_mode)

{

    length = (length + 1) & ~1;         /* Round up to word length. */

    outb(EOC+MAR, ioaddr + PAR_DATA);

    if ((data_mode & 1) == 0) {

                /* Write the packet out, starting with the write addr. */

                outb(WrAddr+MAR, ioaddr + PAR_DATA);

                do {

                        write_byte_mode0(ioaddr, *packet++);

                } while (--length > 0) ;

    } else {

                /* Write the packet out in slow mode. */

                unsigned char outbyte = *packet++;

                outb(Ctrl_LNibWrite + Ctrl_IRQEN, ioaddr + PAR_CONTROL);

                outb(WrAddr+MAR, ioaddr + PAR_DATA);

                outb((outbyte & 0x0f)|0x40, ioaddr + PAR_DATA);

                outb(outbyte & 0x0f, ioaddr + PAR_DATA);

                outbyte >>= 4;

                outb(outbyte & 0x0f, ioaddr + PAR_DATA);

                outb(Ctrl_HNibWrite + Ctrl_IRQEN, ioaddr + PAR_CONTROL);

                while (--length > 0)

                        write_byte_mode1(ioaddr, *packet++);

    }

    /* Terminate the Tx frame.  End of write: ECB. */

    outb(0xff, ioaddr + PAR_DATA);

    outb(Ctrl_HNibWrite | Ctrl_SelData | Ctrl_IRQEN, ioaddr + PAR_CONTROL);

}

static int

net_send_packet(struct sk_buff *skb, struct device *dev)

{

        struct net_local *lp = (struct net_local *)dev->priv;

        int ioaddr = dev->base_addr;

#ifndef final_version

        if (skb == NULL || skb->len <= 0) {

                printk("%s: Obsolete driver layer request made: skbuff==NULL.\n",

                           dev->name);

                dev_tint(dev);

                return 0;

        }

#endif

        /* Use transmit-while-tbusy as a crude error timer. */

        if (set_bit(0, (void*)&dev->tbusy) != 0) {

                if (jiffies - dev->trans_start < TX_TIMEOUT)

                        return 1;

                printk("%s: transmit timed out, %s?\n", dev->name,

                           inb(ioaddr + PAR_CONTROL) & 0x10 ? "network cable problem"

                           :  "IRQ conflict");

                lp->stats.tx_errors++;

                /* Try to restart the adapter. */

                hardware_init(dev);

                dev->tbusy=0;

                dev->trans_start = jiffies;

                return 1;

        } else {

                short length = ETH_ZLEN < skb->len ? skb->len : ETH_ZLEN;

                unsigned char *buf = skb->data;

                int flags;

                /* Disable interrupts by writing 0x00 to the Interrupt Mask Register.

                   This sequence must not be interrupted by an incoming packet. */

                save_flags(flags);

                cli();

                write_reg(ioaddr, IMR, 0);

                write_reg_high(ioaddr, IMR, 0);

                restore_flags(flags);

                write_packet(ioaddr, length, buf, dev->if_port);

                lp->pac_cnt_in_tx_buf++;

                if (lp->tx_unit_busy == 0) {

                        trigger_send(ioaddr, length);

                        lp->saved_tx_size = 0;                           /* Redundant */

                        lp->re_tx = 0;

                        lp->tx_unit_busy = 1;

                } else

                        lp->saved_tx_size = length;

                dev->trans_start = jiffies;

                /* Re-enable the LPT interrupts. */

                write_reg(ioaddr, IMR, ISR_RxOK | ISR_TxErr | ISR_TxOK);

                write_reg_high(ioaddr, IMR, ISRh_RxErr);

        }

        dev_kfree_skb (skb, FREE_WRITE);

        return 0;

}

/* The typical workload of the driver:

   Handle the network interface interrupts. */

static void

net_interrupt IRQ(int irq, void *dev_instance, struct pt_regs * regs)

{

#ifdef SA_SHIRQ

        struct device *dev = (struct device *)dev_instance;

#else

        struct device *dev = (struct device *)(irq2dev_map[irq]);

#endif

        struct net_local *lp;

        int ioaddr, status, boguscount = 20;

        static int num_tx_since_rx = 0;

        if (dev == NULL) {

                printk ("ATP_interrupt(): irq %d for unknown device.\n", irq);

                return;

        }

        dev->interrupt = 1;

        ioaddr = dev->base_addr;

        lp = (struct net_local *)dev->priv;

        /* Disable additional spurious interrupts. */

        outb(Ctrl_SelData, ioaddr + PAR_CONTROL);

        /* The adapter's output is currently the IRQ line, switch it to data. */

        write_reg(ioaddr, CMR2, CMR2_NULL);

        write_reg(ioaddr, IMR, 0);

        if (net_debug > 5) printk("%s: In interrupt ", dev->name);

    while (--boguscount > 0) {

                status = read_nibble(ioaddr, ISR);

                if (net_debug > 5) printk("loop status %02x..", status);

                if (status & (ISR_RxOK<<3)) {

                        write_reg(ioaddr, ISR, ISR_RxOK); /* Clear the Rx interrupt. */

                        do {

                                int read_status = read_nibble(ioaddr, CMR1);

                                if (net_debug > 6)

                                        printk("handling Rx packet %02x..", read_status);

                                /* We acknowledged the normal Rx interrupt, so if the interrupt

                                   is still outstanding we must have a Rx error. */

                                if (read_status & (CMR1_IRQ << 3)) { /* Overrun. */

                                        lp->stats.rx_over_errors++;

                                        /* Set to no-accept mode long enough to remove a packet. */

                                        write_reg_high(ioaddr, CMR2, CMR2h_OFF);

                                        net_rx(dev);

                                        /* Clear the interrupt and return to normal Rx mode. */

                                        write_reg_high(ioaddr, ISR, ISRh_RxErr);

                                        write_reg_high(ioaddr, CMR2, lp->addr_mode);

                                } else if ((read_status & (CMR1_BufEnb << 3)) == 0) {

                                        net_rx(dev);

                                        dev->last_rx = jiffies;

                                        num_tx_since_rx = 0;

                                } else

                                        break;

                        } while (--boguscount > 0);

                } else if (status & ((ISR_TxErr + ISR_TxOK)<<3)) {

                        if (net_debug > 6)  printk("handling Tx done..");

                        /* Clear the Tx interrupt.  We should check for too many failures

                           and reinitialize the adapter. */

                        write_reg(ioaddr, ISR, ISR_TxErr + ISR_TxOK);

                        if (status & (ISR_TxErr<<3)) {

                                lp->stats.collisions++;

                                if (++lp->re_tx > 15) {

                                        lp->stats.tx_aborted_errors++;

                                        hardware_init(dev);

                                        break;

                                }

                                /* Attempt to retransmit. */

                                if (net_debug > 6)  printk("attempting to ReTx");

                                write_reg(ioaddr, CMR1, CMR1_ReXmit + CMR1_Xmit);

                        } else {

                                /* Finish up the transmit. */

                                lp->stats.tx_packets++;

                                lp->pac_cnt_in_tx_buf--;

                                if ( lp->saved_tx_size) {

                                        trigger_send(ioaddr, lp->saved_tx_size);

                                        lp->saved_tx_size = 0;

                                        lp->re_tx = 0;

                                } else

                                        lp->tx_unit_busy = 0;

                                dev->tbusy = 0;

                                mark_bh(NET_BH);        /* Inform upper layers. */

                        }

                        num_tx_since_rx++;

                } else if (num_tx_since_rx > 8

                                   && jiffies > dev->last_rx + 100) {

                        if (net_debug > 2)

                                printk("%s: Missed packet? No Rx after %d Tx and %ld jiffies"

                                           " status %02x  CMR1 %02x.\n", dev->name,

                                           num_tx_since_rx, jiffies - dev->last_rx, status,

                                           (read_nibble(ioaddr, CMR1) >> 3) & 15);