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/* znet.c: An Zenith Z-Note ethernet driver for linux. */

static const char *version = "znet.c:v1.02 9/23/94 becker@cesdis.gsfc.nasa.gov\n";

/*

        Written by Donald Becker.

        The author may be reached as becker@cesdis.gsfc.nasa.gov.

        This driver is based on the Linux skeleton driver.  The copyright of the

        skeleton driver is held by the United States Government, as represented

        by DIRNSA, and it is released under the GPL.

        Thanks to Mike Hollick for alpha testing and suggestions.

  References:

           The Crynwr packet driver.

          "82593 CSMA/CD Core LAN Controller" Intel datasheet, 1992

          Intel Microcommunications Databook, Vol. 1, 1990.

    As usual with Intel, the documentation is incomplete and inaccurate.

        I had to read the Crynwr packet driver to figure out how to actually

        use the i82593, and guess at what register bits matched the loosely

        related i82586.

                                        Theory of Operation

        The i82593 used in the Zenith Z-Note series operates using two(!) slave

        DMA     channels, one interrupt, and one 8-bit I/O port.

        While there     several ways to configure '593 DMA system, I chose the one

        that seemed commensurate with the highest system performance in the face

        of moderate interrupt latency: Both DMA channels are configured as

        recirculating ring buffers, with one channel (#0) dedicated to Rx and

        the other channel (#1) to Tx and configuration.  (Note that this is

        different than the Crynwr driver, where the Tx DMA channel is initialized

        before each operation.  That approach simplifies operation and Tx error

        recovery, but requires additional I/O in normal operation and precludes

        transmit buffer chaining.)

        Both rings are set to 8192 bytes using {TX,RX}_RING_SIZE.  This provides

        a reasonable ring size for Rx, while simplifying DMA buffer allocation --

        DMA buffers must not cross a 128K boundary.  (In truth the size selection

        was influenced by my lack of '593 documentation.  I thus was constrained

        to use the Crynwr '593 initialization table, which sets the Rx ring size

        to 8K.)

        Despite my usual low opinion about Intel-designed parts, I must admit

        that the bulk data handling of the i82593 is a good design for

        an integrated system, like a laptop, where using two slave DMA channels

        doesn't pose a problem.  I still take issue with using only a single I/O

        port.  In the same controlled environment there are essentially no

        limitations on I/O space, and using multiple locations would eliminate

        the     need for multiple operations when looking at status registers,

        setting the Rx ring boundary, or switching to promiscuous mode.

        I also question Zenith's selection of the '593: one of the advertised

        advantages of earlier Intel parts was that if you figured out the magic

        initialization incantation you could use the same part on many different

        network types.  Zenith's use of the "FriendlyNet" (sic) connector rather

        than an on-board transceiver leads me to believe that they were planning

        to take advantage of this.  But, uhmmm, the '593 omits all but ethernet

        functionality from the serial subsystem.

 */

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/string.h>

#include <linux/ptrace.h>

#include <linux/errno.h>

#include <linux/interrupt.h>

#include <linux/ioport.h>

#include <asm/system.h>

#include <asm/bitops.h>

#include <asm/io.h>

#include <asm/dma.h>

#include <linux/netdevice.h>

#include <linux/etherdevice.h>

#include <linux/skbuff.h>

#include <linux/if_arp.h>

#ifndef ZNET_DEBUG

#define ZNET_DEBUG 1

#endif

static unsigned int znet_debug = ZNET_DEBUG;

/* The DMA modes we need aren't in <dma.h>. */

#define DMA_RX_MODE             0x14    /* Auto init, I/O to mem, ++, demand. */

#define DMA_TX_MODE             0x18    /* Auto init, Mem to I/O, ++, demand. */

#define dma_page_eq(ptr1, ptr2) ((long)(ptr1)>>17 == (long)(ptr2)>>17)

#define DMA_BUF_SIZE 8192

#define RX_BUF_SIZE 8192

#define TX_BUF_SIZE 8192

/* Commands to the i82593 channel 0. */

#define CMD0_CHNL_0                     0x00

#define CMD0_CHNL_1                     0x10            /* Switch to channel 1. */

#define CMD0_NOP (CMD0_CHNL_0)

#define CMD0_PORT_1     CMD0_CHNL_1

#define CMD1_PORT_0     1

#define CMD0_IA_SETUP           1

#define CMD0_CONFIGURE          2

#define CMD0_MULTICAST_LIST 3

#define CMD0_TRANSMIT           4

#define CMD0_DUMP                       6

#define CMD0_DIAGNOSE           7

#define CMD0_Rx_ENABLE          8

#define CMD0_Rx_DISABLE         10

#define CMD0_Rx_STOP            11

#define CMD0_RETRANSMIT         12

#define CMD0_ABORT                      13

#define CMD0_RESET                      14

#define CMD0_ACK 0x80

#define CMD0_STAT0 (0 << 5)

#define CMD0_STAT1 (1 << 5)

#define CMD0_STAT2 (2 << 5)

#define CMD0_STAT3 (3 << 5)

#define net_local znet_private

struct znet_private {

        int rx_dma, tx_dma;

        struct enet_statistics stats;

        /* The starting, current, and end pointers for the packet buffers. */

        ushort *rx_start, *rx_cur, *rx_end;

        ushort *tx_start, *tx_cur, *tx_end;

        ushort tx_buf_len;                      /* Tx buffer length, in words. */

};

/* Only one can be built-in;-> */

static struct znet_private zn;

static ushort dma_buffer1[DMA_BUF_SIZE/2];

static ushort dma_buffer2[DMA_BUF_SIZE/2];

static ushort dma_buffer3[DMA_BUF_SIZE/2 + 8];

/* The configuration block.  What an undocumented nightmare.  The first

   set of values are those suggested (without explanation) for ethernet

   in the Intel 82586 databook.  The rest appear to be completely undocumented,

   except for cryptic notes in the Crynwr packet driver.  This driver uses

   the Crynwr values verbatim. */

static unsigned char i593_init[] = {

  0xAA,                                 /* 0: 16-byte input & 80-byte output FIFO. */

                                                /*        threshold, 96-byte FIFO, 82593 mode. */

  0x88,                                 /* 1: Continuous w/interrupts, 128-clock DMA.*/

  0x2E,                                 /* 2: 8-byte preamble, NO address insertion, */

                                                /*        6-byte Ethernet address, loopback off.*/

  0x00,                                 /* 3: Default priorities & backoff methods. */

  0x60,                                 /* 4: 96-bit interframe spacing. */

  0x00,                                 /* 5: 512-bit slot time (low-order). */

  0xF2,                                 /* 6: Slot time (high-order), 15 COLL retries. */

  0x00,                                 /* 7: Promisc-off, broadcast-on, default CRC. */

  0x00,                                 /* 8: Default carrier-sense, collision-detect. */

  0x40,                                 /* 9: 64-byte minimum frame length. */

  0x5F,                                 /* A: Type/length checks OFF, no CRC input,

                                                   "jabber" termination, etc. */

  0x00,                                 /* B: Full-duplex disabled. */

  0x3F,                                 /* C: Default multicast addresses & backoff. */

  0x07,                                 /* D: Default IFS retriggering. */

  0x31,                                 /* E: Internal retransmit, drop "runt" packets,

                                                   synchr. DRQ deassertion, 6 status bytes. */

  0x22,                                 /* F: Receive ring-buffer size (8K),

                                                   receive-stop register enable. */

};

struct netidblk {

        char magic[8];          /* The magic number (string) "NETIDBLK" */

        unsigned char netid[8]; /* The physical station address */

        char nettype, globalopt;

        char vendor[8];         /* The machine vendor and product name. */

        char product[8];

        char irq1, irq2;                /* Interrupts, only one is currently used.      */

        char dma1, dma2;

        short dma_mem_misc[8];          /* DMA buffer locations (unused in Linux). */

        short iobase1, iosize1;

        short iobase2, iosize2;         /* Second iobase unused. */

        char driver_options;                    /* Misc. bits */

        char pad;

};

int znet_probe(struct device *dev);

static int      znet_open(struct device *dev);

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

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

static void     znet_rx(struct device *dev);

static int      znet_close(struct device *dev);

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

static void set_multicast_list(struct device *dev);

static void hardware_init(struct device *dev);

static void update_stop_hit(short ioaddr, unsigned short rx_stop_offset);

#ifdef notdef

static struct sigaction znet_sigaction = { &znet_interrupt, 0, 0, NULL, };

#endif

/* The Z-Note probe is pretty easy.  The NETIDBLK exists in the safe-to-probe

   BIOS area.  We just scan for the signature, and pull the vital parameters

   out of the structure. */

int znet_probe(struct device *dev)

{

        int i;

        struct netidblk *netinfo;

        char *p;

        /* This code scans the region 0xf0000 to 0xfffff for a "NETIDBLK". */

        for(p = (char *)0xf0000; p < (char *)0x100000; p++)

                if (*p == 'N'  &&  strncmp(p, "NETIDBLK", 8) == 0)

                        break;

        if (p >= (char *)0x100000) {

                if (znet_debug > 1)

                        printk(KERN_INFO "No Z-Note ethernet adaptor found.\n");

                return ENODEV;

        }

        netinfo = (struct netidblk *)p;

        dev->base_addr = netinfo->iobase1;

        dev->irq = netinfo->irq1;

        printk(KERN_INFO "%s: ZNET at %#3lx,", dev->name, dev->base_addr);

        /* The station address is in the "netidblk" at 0x0f0000. */

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

                printk(" %2.2x", dev->dev_addr[i] = netinfo->netid[i]);

        printk(", using IRQ %d DMA %d and %d.\n", dev->irq, netinfo->dma1,

                netinfo->dma2);

        if (znet_debug > 1) {

                printk(KERN_INFO "%s: vendor '%16.16s' IRQ1 %d IRQ2 %d DMA1 %d DMA2 %d.\n",

                           dev->name, netinfo->vendor,

                           netinfo->irq1, netinfo->irq2,

                           netinfo->dma1, netinfo->dma2);

                printk(KERN_INFO "%s: iobase1 %#x size %d iobase2 %#x size %d net type %2.2x.\n",

                           dev->name, netinfo->iobase1, netinfo->iosize1,

                           netinfo->iobase2, netinfo->iosize2, netinfo->nettype);

        }

        if (znet_debug > 0)

                printk("%s%s", KERN_INFO, version);

        dev->priv = (void *) &zn;

        zn.rx_dma = netinfo->dma1;

        zn.tx_dma = netinfo->dma2;

        /* These should never fail.  You can't add devices to a sealed box! */

        if (request_irq(dev->irq, &znet_interrupt, 0, "ZNet", NULL)

                || request_dma(zn.rx_dma,"ZNet rx")

                || request_dma(zn.tx_dma,"ZNet tx")) {

                printk(KERN_WARNING "%s: Not opened -- resource busy?!?\n", dev->name);

                return EBUSY;

        }

        irq2dev_map[dev->irq] = dev;

        /* Allocate buffer memory.      We can cross a 128K boundary, so we

           must be careful about the allocation.  It's easiest to waste 8K. */

        if (dma_page_eq(dma_buffer1, &dma_buffer1[RX_BUF_SIZE/2-1]))

          zn.rx_start = dma_buffer1;

        else

          zn.rx_start = dma_buffer2;

        if (dma_page_eq(dma_buffer3, &dma_buffer3[RX_BUF_SIZE/2-1]))

          zn.tx_start = dma_buffer3;

        else

          zn.tx_start = dma_buffer2;

        zn.rx_end = zn.rx_start + RX_BUF_SIZE/2;

        zn.tx_buf_len = TX_BUF_SIZE/2;

        zn.tx_end = zn.tx_start + zn.tx_buf_len;

        /* The ZNET-specific entries in the device structure. */

        dev->open = &znet_open;

        dev->hard_start_xmit = &znet_send_packet;

        dev->stop = &znet_close;

        dev->get_stats  = net_get_stats;

        dev->set_multicast_list = &set_multicast_list;

        /* Fill in the 'dev' with ethernet-generic values. */

        ether_setup(dev);

        return 0;

}

static int znet_open(struct device *dev)

{

        int ioaddr = dev->base_addr;

        if (znet_debug > 2)

                printk(KERN_DEBUG "%s: znet_open() called.\n", dev->name);

        /* Turn on the 82501 SIA, using zenith-specific magic. */

        outb(0x10, 0xe6);                                       /* Select LAN control register */

        outb(inb(0xe7) | 0x84, 0xe7);           /* Turn on LAN power (bit 2). */

        /* According to the Crynwr driver we should wait 50 msec. for the

           LAN clock to stabilize.  My experiments indicates that the '593 can

           be initialized immediately.  The delay is probably needed for the

           DC-to-DC converter to come up to full voltage, and for the oscillator

           to be spot-on at 20Mhz before transmitting.

           Until this proves to be a problem we rely on the higher layers for the

           delay and save allocating a timer entry. */

        /* This follows the packet driver's lead, and checks for success. */

        if (inb(ioaddr) != 0x10 && inb(ioaddr) != 0x00)

                printk(KERN_WARNING "%s: Problem turning on the transceiver power.\n",

                           dev->name);

        dev->tbusy = 0;

        dev->interrupt = 0;

        hardware_init(dev);

        dev->start = 1;

        return 0;

}

static int znet_send_packet(struct sk_buff *skb, struct device *dev)

{

        int ioaddr = dev->base_addr;

        if (znet_debug > 4)

                printk(KERN_DEBUG "%s: ZNet_send_packet(%ld).\n", dev->name, dev->tbusy);

        /* Transmitter timeout, likely just recovery after suspending the machine. */

        if (dev->tbusy) {

                ushort event, tx_status, rx_offset, state;

                int tickssofar = jiffies - dev->trans_start;

                if (tickssofar < 10)

                        return 1;

                outb(CMD0_STAT0, ioaddr); event = inb(ioaddr);

                outb(CMD0_STAT1, ioaddr); tx_status = inw(ioaddr);

                outb(CMD0_STAT2, ioaddr); rx_offset = inw(ioaddr);

                outb(CMD0_STAT3, ioaddr); state = inb(ioaddr);

                printk(KERN_WARNING "%s: transmit timed out, status %02x %04x %04x %02x,"

                           " resetting.\n", dev->name, event, tx_status, rx_offset, state);

                if (tx_status == 0x0400)

                  printk(KERN_WARNING "%s: Tx carrier error, check transceiver cable.\n",

                                 dev->name);

                outb(CMD0_RESET, ioaddr);

                hardware_init(dev);

        }

        if (skb == NULL) {

                dev_tint(dev);

                return 0;

        }

        /* Check that the part hasn't reset itself, probably from suspend. */

        outb(CMD0_STAT0, ioaddr);

        if (inw(ioaddr) == 0x0010

                && inw(ioaddr) == 0x0000

                && inw(ioaddr) == 0x0010)

          hardware_init(dev);

        /* Block a timer-based transmit from overlapping.  This could better be

           done with atomic_swap(1, dev->tbusy), but set_bit() works as well. */

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

                printk(KERN_WARNING "%s: Transmitter access conflict.\n", dev->name);

        else {

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

                unsigned char *buf = (void *)skb->data;

                ushort *tx_link = zn.tx_cur - 1;

                ushort rnd_len = (length + 1)>>1;

                {

                        short dma_port = ((zn.tx_dma&3)<<2) + IO_DMA2_BASE;

                        unsigned addr = inb(dma_port);

                        addr |= inb(dma_port) << 8;

                        addr <<= 1;

                        if (((int)zn.tx_cur & 0x1ffff) != addr)

                          printk(KERN_WARNING "Address mismatch at Tx: %#x vs %#x.\n",

                                         (int)zn.tx_cur & 0xffff, addr);

                        zn.tx_cur = (ushort *)(((int)zn.tx_cur & 0xfe0000) | addr);

                }

                if (zn.tx_cur >= zn.tx_end)

                  zn.tx_cur = zn.tx_start;

                *zn.tx_cur++ = length;

                if (zn.tx_cur + rnd_len + 1 > zn.tx_end) {

                        int semi_cnt = (zn.tx_end - zn.tx_cur)<<1; /* Cvrt to byte cnt. */

                        memcpy(zn.tx_cur, buf, semi_cnt);

                        rnd_len -= semi_cnt>>1;

                        memcpy(zn.tx_start, buf + semi_cnt, length - semi_cnt);

                        zn.tx_cur = zn.tx_start + rnd_len;

                } else {

                        memcpy(zn.tx_cur, buf, skb->len);

                        zn.tx_cur += rnd_len;

                }

                *zn.tx_cur++ = 0;

                cli(); {

                        *tx_link = CMD0_TRANSMIT + CMD0_CHNL_1;

                        /* Is this always safe to do? */

                        outb(CMD0_TRANSMIT + CMD0_CHNL_1,ioaddr);

                } sti();

                dev->trans_start = jiffies;

                if (znet_debug > 4)

                  printk(KERN_DEBUG "%s: Transmitter queued, length %d.\n", dev->name, length);

        }

        dev_kfree_skb(skb, FREE_WRITE);

        return 0;

}

/* The ZNET interrupt handler. */

static void     znet_interrupt(int irq, void *dev_id, struct pt_regs * regs)

{

        struct device *dev = irq2dev_map[irq];

        int ioaddr;

        int boguscnt = 20;

        if (dev == NULL) {

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

                return;

        }

        dev->interrupt = 1;

        ioaddr = dev->base_addr;

        outb(CMD0_STAT0, ioaddr);

        do {

                ushort status = inb(ioaddr);

                if (znet_debug > 5) {

                        ushort result, rx_ptr, running;

                        outb(CMD0_STAT1, ioaddr);

                        result = inw(ioaddr);

                        outb(CMD0_STAT2, ioaddr);

                        rx_ptr = inw(ioaddr);

                        outb(CMD0_STAT3, ioaddr);

                        running = inb(ioaddr);

                        printk(KERN_DEBUG "%s: interrupt, status %02x, %04x %04x %02x serial %d.\n",

                                 dev->name, status, result, rx_ptr, running, boguscnt);

                }

                if ((status & 0x80) == 0)

                        break;

                if ((status & 0x0F) == 4) {     /* Transmit done. */

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

                        int tx_status;

                        outb(CMD0_STAT1, ioaddr);

                        tx_status = inw(ioaddr);

                        /* It's undocumented, but tx_status seems to match the i82586. */

                        if (tx_status & 0x2000) {

                                lp->stats.tx_packets++;

                                lp->stats.collisions += tx_status & 0xf;

                        } else {

                                if (tx_status & 0x0600)  lp->stats.tx_carrier_errors++;

                                if (tx_status & 0x0100)  lp->stats.tx_fifo_errors++;

                                if (!(tx_status & 0x0040)) lp->stats.tx_heartbeat_errors++;

                                if (tx_status & 0x0020)  lp->stats.tx_aborted_errors++;

                                /* ...and the catch-all. */

                                if ((tx_status | 0x0760) != 0x0760)

                                  lp->stats.tx_errors++;

                        }

                        dev->tbusy = 0;

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

                }

                if ((status & 0x40)

                        || (status & 0x0f) == 11) {

                        znet_rx(dev);

                }

                /* Clear the interrupts we've handled. */

                outb(CMD0_ACK,ioaddr);

        } while (boguscnt--);

        dev->interrupt = 0;

        return;

}

static void znet_rx(struct device *dev)

{

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

        int ioaddr = dev->base_addr;

        int boguscount = 1;

        short next_frame_end_offset = 0;                 /* Offset of next frame start. */

        short *cur_frame_end;

        short cur_frame_end_offset;

        outb(CMD0_STAT2, ioaddr);

        cur_frame_end_offset = inw(ioaddr);

        if (cur_frame_end_offset == zn.rx_cur - zn.rx_start) {

                printk(KERN_WARNING "%s: Interrupted, but nothing to receive, offset %03x.\n",

                           dev->name, cur_frame_end_offset);

                return;

        }

        /* Use same method as the Crynwr driver: construct a forward list in

           the same area of the backwards links we now have.  This allows us to

           pass packets to the upper layers in the order they were received --

           important for fast-path sequential operations. */

         while (zn.rx_start + cur_frame_end_offset != zn.rx_cur

                        && ++boguscount < 5) {

                unsigned short hi_cnt, lo_cnt, hi_status, lo_status;

                int count, status;

                if (cur_frame_end_offset < 4) {

                        /* Oh no, we have a special case: the frame trailer wraps around

                           the end of the ring buffer.  We've saved space at the end of

                           the ring buffer for just this problem. */

                        memcpy(zn.rx_end, zn.rx_start, 8);

                        cur_frame_end_offset += (RX_BUF_SIZE/2);

                }

                cur_frame_end = zn.rx_start + cur_frame_end_offset - 4;

                lo_status = *cur_frame_end++;

                hi_status = *cur_frame_end++;

                status = ((hi_status & 0xff) << 8) + (lo_status & 0xff);

                lo_cnt = *cur_frame_end++;

                hi_cnt = *cur_frame_end++;

                count = ((hi_cnt & 0xff) << 8) + (lo_cnt & 0xff);

                if (znet_debug > 5)

                  printk(KERN_DEBUG "Constructing trailer at location %03x, %04x %04x %04x %04x"

                                 " count %#x status %04x.\n",

                                 cur_frame_end_offset<<1, lo_status, hi_status, lo_cnt, hi_cnt,

                                 count, status);

                cur_frame_end[-4] = status;

                cur_frame_end[-3] = next_frame_end_offset;

                cur_frame_end[-2] = count;

                next_frame_end_offset = cur_frame_end_offset;

                cur_frame_end_offset -= ((count + 1)>>1) + 3;

                if (cur_frame_end_offset < 0)

                  cur_frame_end_offset += RX_BUF_SIZE/2;

        };

        /* Now step  forward through the list. */

        do {

                ushort *this_rfp_ptr = zn.rx_start + next_frame_end_offset;

                int status = this_rfp_ptr[-4];

                int pkt_len = this_rfp_ptr[-2];

                if (znet_debug > 5)

                  printk(KERN_DEBUG "Looking at trailer ending at %04x status %04x length %03x"

                                 " next %04x.\n", next_frame_end_offset<<1, status, pkt_len,

                                 this_rfp_ptr[-3]<<1);

                /* Once again we must assume that the i82586 docs apply. */

                if ( ! (status & 0x2000)) {                             /* There was an error. */

                        lp->stats.rx_errors++;

                        if (status & 0x0800) lp->stats.rx_crc_errors++;

                        if (status & 0x0400) lp->stats.rx_frame_errors++;

                        if (status & 0x0200) lp->stats.rx_over_errors++; /* Wrong. */

                        if (status & 0x0100) lp->stats.rx_fifo_errors++;

                        if (status & 0x0080) lp->stats.rx_length_errors++;

                } else if (pkt_len > 1536) {

                        lp->stats.rx_length_errors++;

                } else {

                        /* Malloc up new buffer. */

                        struct sk_buff *skb;

                        skb = dev_alloc_skb(pkt_len);

                        if (skb == NULL) {

                                if (znet_debug)

                                  printk(KERN_WARNING "%s: Memory squeeze, dropping packet.\n", dev->name);

                                lp->stats.rx_dropped++;

                                break;

                        }

                        skb->dev = dev;

                        if (&zn.rx_cur[(pkt_len+1)>>1] > zn.rx_end) {

                                int semi_cnt = (zn.rx_end - zn.rx_cur)<<1;

                                memcpy(skb_put(skb,semi_cnt), zn.rx_cur, semi_cnt);

                                memcpy(skb_put(skb,pkt_len-semi_cnt), zn.rx_start,

                                           pkt_len - semi_cnt);

                        } else {

                                memcpy(skb_put(skb,pkt_len), zn.rx_cur, pkt_len);

                                if (znet_debug > 6) {

                                        unsigned int *packet = (unsigned int *) skb->data;

                                        printk(KERN_DEBUG "Packet data is %08x %08x %08x %08x.\n", packet[0],

                                                   packet[1], packet[2], packet[3]);

                                }

                  }

                  skb->protocol=eth_type_trans(skb,dev);

                  netif_rx(skb);

                  lp->stats.rx_packets++;

                }

                zn.rx_cur = this_rfp_ptr;

                if (zn.rx_cur >= zn.rx_end)

                        zn.rx_cur -= RX_BUF_SIZE/2;

                update_stop_hit(ioaddr, (zn.rx_cur - zn.rx_start)<<1);

                next_frame_end_offset = this_rfp_ptr[-3];

                if (next_frame_end_offset == 0)          /* Read all the frames? */

                        break;                  /* Done for now */

                this_rfp_ptr = zn.rx_start + next_frame_end_offset;

        } while (--boguscount);

        /* 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. */

        return;

}

/* The inverse routine to znet_open(). */

static int znet_close(struct device *dev)

{

        int ioaddr = dev->base_addr;

        dev->tbusy = 1;

        dev->start = 0;

        outb(CMD0_RESET, ioaddr);                       /* CMD0_RESET */

        disable_dma(zn.rx_dma);

        disable_dma(zn.tx_dma);

        free_irq(dev->irq, NULL);

        if (znet_debug > 1)

                printk(KERN_DEBUG "%s: Shutting down ethercard.\n", dev->name);

        /* Turn off transceiver power. */

        outb(0x10, 0xe6);                                       /* Select LAN control register */

        outb(inb(0xe7) & ~0x84, 0xe7);          /* Turn on LAN power (bit 2). */

        return 0;

}

/* Get the current statistics.  This may be called with the card open or

   closed. */

static struct enet_statistics *net_get_stats(struct device *dev)

{

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

                return &lp->stats;

}

/* Set or clear the multicast filter for this adaptor.

   As a side effect this routine must also initialize the device parameters.

   This is taken advantage of in open().

   N.B. that we change i593_init[] in place.  This (properly) makes the

   mode change persistent, but must be changed if this code is moved to

   a multiple adaptor environment.

 */

static void set_multicast_list(struct device *dev)

{

        short ioaddr = dev->base_addr;

        if (dev->flags&IFF_PROMISC) {

                /* Enable promiscuous mode */

                i593_init[7] &= ~3;             i593_init[7] |= 1;

                i593_init[13] &= ~8;    i593_init[13] |= 8;

        } else if (dev->mc_list || (dev->flags&IFF_ALLMULTI)) {