/* sun3lance.c: Ethernet driver for SUN3 Lance chip */
/*

  Sun3 Lance ethernet driver, by Sam Creasey (sammy@users.qual.net).
  This driver is a part of the linux kernel, and is thus distributed
  under the GNU General Public License.

  The values used in LANCE_OBIO and LANCE_IRQ seem to be empirically
  true for the correct IRQ and address of the lance registers.  They
  have not been widely tested, however.  What we probably need is a
  "proper" way to search for a device in the sun3's prom, but, alas,
  linux has no such thing.

  This driver is largely based on atarilance.c, by Roman Hodek.  Other
  sources of inspiration were the NetBSD sun3 am7990 driver, and the
  linux sparc lance driver (sunlance.c).

  There are more assumptions made throughout this driver, it almost
  certainly still needs work, but it does work at least for RARP/BOOTP and
  mounting the root NFS filesystem.

*/

static const char version[] =
"sun3lance.c: v1.2 1/12/2001  Sam Creasey (sammy@sammy.net)\n";

#include <linux/module.h>
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/bitops.h>
#include <linux/pgtable.h>

#include <asm/cacheflush.h>
#include <asm/setup.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/dvma.h>
#include <asm/idprom.h>
#include <asm/machines.h>

#ifdef CONFIG_SUN3
#include <asm/sun3mmu.h>
#else
#include <asm/sun3xprom.h>
#endif

/* sun3/60 addr/irq for the lance chip.  If your sun is different,
   change this. */
#define LANCE_OBIO 0x120000
#define LANCE_IRQ IRQ_AUTO_3

/* Debug level:
 *  0 = silent, print only serious errors
 *  1 = normal, print error messages
 *  2 = debug, print debug infos
 *  3 = debug, print even more debug infos (packet data)
 */

#define LANCE_DEBUG     0

#ifdef LANCE_DEBUG
static int lance_debug = LANCE_DEBUG;
#else
static int lance_debug = 1;
#endif
module_param(lance_debug, int, 0);
MODULE_PARM_DESC(lance_debug, "SUN3 Lance debug level (0-3)");
MODULE_DESCRIPTION("Sun3/Sun3x on-board LANCE Ethernet driver");
MODULE_LICENSE("GPL");

#define DPRINTK(n,a) \
        do {  \
                if (lance_debug >= n)  \
                        printk a; \
        } while( 0 )


/* we're only using 32k of memory, so we use 4 TX
   buffers and 16 RX buffers.  These values are expressed as log2. */

#define TX_LOG_RING_SIZE                        3
#define RX_LOG_RING_SIZE                        5

/* These are the derived values */

#define TX_RING_SIZE                    (1 << TX_LOG_RING_SIZE)
#define TX_RING_LEN_BITS                (TX_LOG_RING_SIZE << 5)
#define TX_RING_MOD_MASK                (TX_RING_SIZE - 1)

#define RX_RING_SIZE                    (1 << RX_LOG_RING_SIZE)
#define RX_RING_LEN_BITS                (RX_LOG_RING_SIZE << 5)
#define RX_RING_MOD_MASK                (RX_RING_SIZE - 1)

/* Definitions for packet buffer access: */
#define PKT_BUF_SZ              1544

/* Get the address of a packet buffer corresponding to a given buffer head */
#define PKTBUF_ADDR(head)       (void *)((unsigned long)(MEM) | (head)->base)


/* The LANCE Rx and Tx ring descriptors. */
struct lance_rx_head {
        unsigned short  base;           /* Low word of base addr */
        volatile unsigned char  flag;
        unsigned char  base_hi; /* High word of base addr (unused) */
        short buf_length;       /* This length is 2s complement! */
        volatile short msg_length;      /* This length is "normal". */
};

struct lance_tx_head {
        unsigned short base;            /* Low word of base addr */
        volatile unsigned char  flag;
        unsigned char base_hi;  /* High word of base addr (unused) */
        short length;           /* Length is 2s complement! */
        volatile short misc;
};

/* The LANCE initialization block, described in databook. */
struct lance_init_block {
        unsigned short  mode;           /* Pre-set mode */
        unsigned char   hwaddr[6];      /* Physical ethernet address */
        unsigned int    filter[2];      /* Multicast filter (unused). */
        /* Receive and transmit ring base, along with length bits. */
        unsigned short rdra;
        unsigned short rlen;
        unsigned short tdra;
        unsigned short tlen;
        unsigned short pad[4]; /* is thie needed? */
};

/* The whole layout of the Lance shared memory */
struct lance_memory {
        struct lance_init_block init;
        struct lance_tx_head    tx_head[TX_RING_SIZE];
        struct lance_rx_head    rx_head[RX_RING_SIZE];
        char   rx_data[RX_RING_SIZE][PKT_BUF_SZ];
        char   tx_data[TX_RING_SIZE][PKT_BUF_SZ];
};

/* The driver's private device structure */

struct lance_private {
        volatile unsigned short *iobase;
        struct lance_memory     *mem;
        int new_rx, new_tx;     /* The next free ring entry */
        int old_tx, old_rx;     /* ring entry to be processed */
/* These two must be longs for set_bit() */
        long        tx_full;
        long        lock;
};

/* I/O register access macros */

#define MEM     lp->mem
#define DREG    lp->iobase[0]
#define AREG    lp->iobase[1]
#define REGA(a) (*( AREG = (a), &DREG ))

/* Definitions for the Lance */

/* tx_head flags */
#define TMD1_ENP                0x01    /* end of packet */
#define TMD1_STP                0x02    /* start of packet */
#define TMD1_DEF                0x04    /* deferred */
#define TMD1_ONE                0x08    /* one retry needed */
#define TMD1_MORE               0x10    /* more than one retry needed */
#define TMD1_ERR                0x40    /* error summary */
#define TMD1_OWN                0x80    /* ownership (set: chip owns) */

#define TMD1_OWN_CHIP   TMD1_OWN
#define TMD1_OWN_HOST   0

/* tx_head misc field */
#define TMD3_TDR                0x03FF  /* Time Domain Reflectometry counter */
#define TMD3_RTRY               0x0400  /* failed after 16 retries */
#define TMD3_LCAR               0x0800  /* carrier lost */
#define TMD3_LCOL               0x1000  /* late collision */
#define TMD3_UFLO               0x4000  /* underflow (late memory) */
#define TMD3_BUFF               0x8000  /* buffering error (no ENP) */

/* rx_head flags */
#define RMD1_ENP                0x01    /* end of packet */
#define RMD1_STP                0x02    /* start of packet */
#define RMD1_BUFF               0x04    /* buffer error */
#define RMD1_CRC                0x08    /* CRC error */
#define RMD1_OFLO               0x10    /* overflow */
#define RMD1_FRAM               0x20    /* framing error */
#define RMD1_ERR                0x40    /* error summary */
#define RMD1_OWN                0x80    /* ownership (set: ship owns) */

#define RMD1_OWN_CHIP   RMD1_OWN
#define RMD1_OWN_HOST   0

/* register names */
#define CSR0    0               /* mode/status */
#define CSR1    1               /* init block addr (low) */
#define CSR2    2               /* init block addr (high) */
#define CSR3    3               /* misc */
#define CSR8    8               /* address filter */
#define CSR15   15              /* promiscuous mode */

/* CSR0 */
/* (R=readable, W=writeable, S=set on write, C=clear on write) */
#define CSR0_INIT       0x0001          /* initialize (RS) */
#define CSR0_STRT       0x0002          /* start (RS) */
#define CSR0_STOP       0x0004          /* stop (RS) */
#define CSR0_TDMD       0x0008          /* transmit demand (RS) */
#define CSR0_TXON       0x0010          /* transmitter on (R) */
#define CSR0_RXON       0x0020          /* receiver on (R) */
#define CSR0_INEA       0x0040          /* interrupt enable (RW) */
#define CSR0_INTR       0x0080          /* interrupt active (R) */
#define CSR0_IDON       0x0100          /* initialization done (RC) */
#define CSR0_TINT       0x0200          /* transmitter interrupt (RC) */
#define CSR0_RINT       0x0400          /* receiver interrupt (RC) */
#define CSR0_MERR       0x0800          /* memory error (RC) */
#define CSR0_MISS       0x1000          /* missed frame (RC) */
#define CSR0_CERR       0x2000          /* carrier error (no heartbeat :-) (RC) */
#define CSR0_BABL       0x4000          /* babble: tx-ed too many bits (RC) */
#define CSR0_ERR        0x8000          /* error (RC) */

/* CSR3 */
#define CSR3_BCON       0x0001          /* byte control */
#define CSR3_ACON       0x0002          /* ALE control */
#define CSR3_BSWP       0x0004          /* byte swap (1=big endian) */

/***************************** Prototypes *****************************/

static int lance_probe( struct net_device *dev);
static int lance_open( struct net_device *dev );
static void lance_init_ring( struct net_device *dev );
static netdev_tx_t lance_start_xmit(struct sk_buff *skb,
                                    struct net_device *dev);
static irqreturn_t lance_interrupt( int irq, void *dev_id);
static int lance_rx( struct net_device *dev );
static int lance_close( struct net_device *dev );
static void set_multicast_list( struct net_device *dev );

/************************* End of Prototypes **************************/

static struct net_device * __init sun3lance_probe(void)
{
        struct net_device *dev;
        static int found;
        int err = -ENODEV;

        if (!MACH_IS_SUN3 && !MACH_IS_SUN3X)
                return ERR_PTR(-ENODEV);

        /* check that this machine has an onboard lance */
        switch(idprom->id_machtype) {
        case SM_SUN3|SM_3_50:
        case SM_SUN3|SM_3_60:
        case SM_SUN3X|SM_3_80:
                /* these machines have lance */
                break;

        default:
                return ERR_PTR(-ENODEV);
        }

        if (found)
                return ERR_PTR(-ENODEV);

        dev = alloc_etherdev(sizeof(struct lance_private));
        if (!dev)
                return ERR_PTR(-ENOMEM);

        if (!lance_probe(dev))
                goto out;

        err = register_netdev(dev);
        if (err)
                goto out1;
        found = 1;
        return dev;

out1:
#ifdef CONFIG_SUN3
        iounmap((void __iomem *)dev->base_addr);
#endif
out:
        free_netdev(dev);
        return ERR_PTR(err);
}

static const struct net_device_ops lance_netdev_ops = {
        .ndo_open               = lance_open,
        .ndo_stop               = lance_close,
        .ndo_start_xmit         = lance_start_xmit,
        .ndo_set_rx_mode        = set_multicast_list,
        .ndo_set_mac_address    = NULL,
        .ndo_validate_addr      = eth_validate_addr,
};

static int __init lance_probe( struct net_device *dev)
{
        unsigned long ioaddr;

        struct lance_private    *lp;
        static int              did_version;
        volatile unsigned short *ioaddr_probe;
        unsigned short tmp1, tmp2;

#ifdef CONFIG_SUN3
        ioaddr = (unsigned long)ioremap(LANCE_OBIO, PAGE_SIZE);
        if (!ioaddr)
                return 0;
#else
        ioaddr = SUN3X_LANCE;
#endif

        /* test to see if there's really a lance here */
        /* (CSRO_INIT shouldn't be readable) */

        ioaddr_probe = (volatile unsigned short *)ioaddr;
        tmp1 = ioaddr_probe[0];
        tmp2 = ioaddr_probe[1];

        ioaddr_probe[1] = CSR0;
        ioaddr_probe[0] = CSR0_INIT | CSR0_STOP;

        if(ioaddr_probe[0] != CSR0_STOP) {
                ioaddr_probe[0] = tmp1;
                ioaddr_probe[1] = tmp2;

#ifdef CONFIG_SUN3
                iounmap((void __iomem *)ioaddr);
#endif
                return 0;
        }

        lp = netdev_priv(dev);

        /* XXX - leak? */
        MEM = dvma_malloc_align(sizeof(struct lance_memory), 0x10000);
        if (!MEM) {
#ifdef CONFIG_SUN3
                iounmap((void __iomem *)ioaddr);
#endif
                printk(KERN_WARNING "SUN3 Lance couldn't allocate DVMA memory\n");
                return 0;
        }

        lp->iobase = (volatile unsigned short *)ioaddr;
        dev->base_addr = (unsigned long)ioaddr; /* informational only */

        REGA(CSR0) = CSR0_STOP;

        if (request_irq(LANCE_IRQ, lance_interrupt, 0, "SUN3 Lance", dev) < 0) {
#ifdef CONFIG_SUN3
                iounmap((void __iomem *)ioaddr);
#endif
                dvma_free((void *)MEM);
                printk(KERN_WARNING "SUN3 Lance unable to allocate IRQ\n");
                return 0;
        }
        dev->irq = (unsigned short)LANCE_IRQ;


        printk("%s: SUN3 Lance at io %#lx, mem %#lx, irq %d, hwaddr ",
                   dev->name,
                   (unsigned long)ioaddr,
                   (unsigned long)MEM,
                   dev->irq);

        /* copy in the ethernet address from the prom */
        eth_hw_addr_set(dev, idprom->id_ethaddr);

        /* tell the card it's ether address, bytes swapped */
        MEM->init.hwaddr[0] = dev->dev_addr[1];
        MEM->init.hwaddr[1] = dev->dev_addr[0];
        MEM->init.hwaddr[2] = dev->dev_addr[3];
        MEM->init.hwaddr[3] = dev->dev_addr[2];
        MEM->init.hwaddr[4] = dev->dev_addr[5];
        MEM->init.hwaddr[5] = dev->dev_addr[4];

        printk("%pM\n", dev->dev_addr);

        MEM->init.mode = 0x0000;
        MEM->init.filter[0] = 0x00000000;
        MEM->init.filter[1] = 0x00000000;
        MEM->init.rdra = dvma_vtob(MEM->rx_head);
        MEM->init.rlen    = (RX_LOG_RING_SIZE << 13) |
                (dvma_vtob(MEM->rx_head) >> 16);
        MEM->init.tdra = dvma_vtob(MEM->tx_head);
        MEM->init.tlen    = (TX_LOG_RING_SIZE << 13) |
                (dvma_vtob(MEM->tx_head) >> 16);

        DPRINTK(2, ("initaddr: %08lx rx_ring: %08lx tx_ring: %08lx\n",
               dvma_vtob(&(MEM->init)), dvma_vtob(MEM->rx_head),
               (dvma_vtob(MEM->tx_head))));

        if (did_version++ == 0)
                printk( version );

        dev->netdev_ops = &lance_netdev_ops;
//      KLUDGE -- REMOVE ME
        set_bit(__LINK_STATE_PRESENT, &dev->state);


        return 1;
}

static int lance_open( struct net_device *dev )
{
        struct lance_private *lp = netdev_priv(dev);
        int i;

        DPRINTK( 2, ( "%s: lance_open()\n", dev->name ));

        REGA(CSR0) = CSR0_STOP;

        lance_init_ring(dev);

        /* From now on, AREG is kept to point to CSR0 */
        REGA(CSR0) = CSR0_INIT;

        i = 1000000;
        while (--i > 0)
                if (DREG & CSR0_IDON)
                        break;
        if (i <= 0 || (DREG & CSR0_ERR)) {
                DPRINTK( 2, ( "lance_open(): opening %s failed, i=%d, csr0=%04x\n",
                                          dev->name, i, DREG ));
                DREG = CSR0_STOP;
                return -EIO;
        }

        DREG = CSR0_IDON | CSR0_STRT | CSR0_INEA;

        netif_start_queue(dev);

        DPRINTK( 2, ( "%s: LANCE is open, csr0 %04x\n", dev->name, DREG ));

        return 0;
}


/* Initialize the LANCE Rx and Tx rings. */

static void lance_init_ring( struct net_device *dev )
{
        struct lance_private *lp = netdev_priv(dev);
        int i;

        lp->lock = 0;
        lp->tx_full = 0;
        lp->new_rx = lp->new_tx = 0;
        lp->old_rx = lp->old_tx = 0;

        for( i = 0; i < TX_RING_SIZE; i++ ) {
                MEM->tx_head[i].base = dvma_vtob(MEM->tx_data[i]);
                MEM->tx_head[i].flag = 0;
                MEM->tx_head[i].base_hi =
                        (dvma_vtob(MEM->tx_data[i])) >>16;
                MEM->tx_head[i].length = 0;
                MEM->tx_head[i].misc = 0;
        }

        for( i = 0; i < RX_RING_SIZE; i++ ) {
                MEM->rx_head[i].base = dvma_vtob(MEM->rx_data[i]);
                MEM->rx_head[i].flag = RMD1_OWN_CHIP;
                MEM->rx_head[i].base_hi =
                        (dvma_vtob(MEM->rx_data[i])) >> 16;
                MEM->rx_head[i].buf_length = -PKT_BUF_SZ | 0xf000;
                MEM->rx_head[i].msg_length = 0;
        }

        /* tell the card it's ether address, bytes swapped */
        MEM->init.hwaddr[0] = dev->dev_addr[1];
        MEM->init.hwaddr[1] = dev->dev_addr[0];
        MEM->init.hwaddr[2] = dev->dev_addr[3];
        MEM->init.hwaddr[3] = dev->dev_addr[2];
        MEM->init.hwaddr[4] = dev->dev_addr[5];
        MEM->init.hwaddr[5] = dev->dev_addr[4];

        MEM->init.mode = 0x0000;
        MEM->init.filter[0] = 0x00000000;
        MEM->init.filter[1] = 0x00000000;
        MEM->init.rdra = dvma_vtob(MEM->rx_head);
        MEM->init.rlen    = (RX_LOG_RING_SIZE << 13) |
                (dvma_vtob(MEM->rx_head) >> 16);
        MEM->init.tdra = dvma_vtob(MEM->tx_head);
        MEM->init.tlen    = (TX_LOG_RING_SIZE << 13) |
                (dvma_vtob(MEM->tx_head) >> 16);


        /* tell the lance the address of its init block */
        REGA(CSR1) = dvma_vtob(&(MEM->init));
        REGA(CSR2) = dvma_vtob(&(MEM->init)) >> 16;

#ifdef CONFIG_SUN3X
        REGA(CSR3) = CSR3_BSWP | CSR3_ACON | CSR3_BCON;
#else
        REGA(CSR3) = CSR3_BSWP;
#endif

}


static netdev_tx_t
lance_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct lance_private *lp = netdev_priv(dev);
        int entry, len;
        struct lance_tx_head *head;
        unsigned long flags;

        DPRINTK( 1, ( "%s: transmit start.\n",
                      dev->name));

        /* Transmitter timeout, serious problems. */
        if (netif_queue_stopped(dev)) {
                int tickssofar = jiffies - dev_trans_start(dev);
                if (tickssofar < HZ/5)
                        return NETDEV_TX_BUSY;

                DPRINTK( 1, ( "%s: transmit timed out, status %04x, resetting.\n",
                                          dev->name, DREG ));
                DREG = CSR0_STOP;
                /*
                 * Always set BSWP after a STOP as STOP puts it back into
                 * little endian mode.
                 */
                REGA(CSR3) = CSR3_BSWP;
                dev->stats.tx_errors++;

                if(lance_debug >= 2) {
                        int i;
                        printk("Ring data: old_tx %d new_tx %d%s new_rx %d\n",
                               lp->old_tx, lp->new_tx,
                               lp->tx_full ? " (full)" : "",
                               lp->new_rx );
                        for( i = 0 ; i < RX_RING_SIZE; i++ )
                                printk( "rx #%d: base=%04x blen=%04x mlen=%04x\n",
                                        i, MEM->rx_head[i].base,
                                        -MEM->rx_head[i].buf_length,
                                        MEM->rx_head[i].msg_length);
                        for( i = 0 ; i < TX_RING_SIZE; i++ )
                                printk("tx #%d: base=%04x len=%04x misc=%04x\n",
                                       i, MEM->tx_head[i].base,
                                       -MEM->tx_head[i].length,
                                       MEM->tx_head[i].misc );
                }

                lance_init_ring(dev);
                REGA( CSR0 ) = CSR0_INEA | CSR0_INIT | CSR0_STRT;

                netif_start_queue(dev);

                return NETDEV_TX_OK;
        }


        /* Block a timer-based transmit from overlapping.  This could better be
           done with atomic_swap(1, dev->tbusy), but set_bit() works as well. */

        /* Block a timer-based transmit from overlapping with us by
           stopping the queue for a bit... */

        netif_stop_queue(dev);

        if (test_and_set_bit( 0, (void*)&lp->lock ) != 0) {
                printk( "%s: tx queue lock!.\n", dev->name);
                /* don't clear dev->tbusy flag. */
                return NETDEV_TX_BUSY;
        }

        AREG = CSR0;
        DPRINTK( 2, ( "%s: lance_start_xmit() called, csr0 %4.4x.\n",
                                  dev->name, DREG ));

#ifdef CONFIG_SUN3X
        /* this weirdness doesn't appear on sun3... */
        if(!(DREG & CSR0_INIT)) {
                DPRINTK( 1, ("INIT not set, reinitializing...\n"));
                REGA( CSR0 ) = CSR0_STOP;
                lance_init_ring(dev);
                REGA( CSR0 ) = CSR0_INIT | CSR0_STRT;
        }
#endif

        /* Fill in a Tx ring entry */
#if 0
        if (lance_debug >= 2) {
                printk( "%s: TX pkt %d type 0x%04x"
                        " from %s to %s"
                        " data at 0x%08x len %d\n",
                        dev->name, lp->new_tx, ((u_short *)skb->data)[6],
                        DEV_ADDR(&skb->data[6]), DEV_ADDR(skb->data),
                        (int)skb->data, (int)skb->len );
        }
#endif
        /* We're not prepared for the int until the last flags are set/reset.
         * And the int may happen already after setting the OWN_CHIP... */
        local_irq_save(flags);

        /* Mask to ring buffer boundary. */
        entry = lp->new_tx;
        head  = &(MEM->tx_head[entry]);

        /* Caution: the write order is important here, set the "ownership" bits
         * last.
         */

        /* the sun3's lance needs it's buffer padded to the minimum
           size */
        len = (ETH_ZLEN < skb->len) ? skb->len : ETH_ZLEN;

//      head->length = -len;
        head->length = (-len) | 0xf000;
        head->misc = 0;

        skb_copy_from_linear_data(skb, PKTBUF_ADDR(head), skb->len);
        if (len != skb->len)
                memset(PKTBUF_ADDR(head) + skb->len, 0, len-skb->len);

        head->flag = TMD1_OWN_CHIP | TMD1_ENP | TMD1_STP;
        lp->new_tx = (lp->new_tx + 1) & TX_RING_MOD_MASK;
        dev->stats.tx_bytes += skb->len;

        /* Trigger an immediate send poll. */
        REGA(CSR0) = CSR0_INEA | CSR0_TDMD | CSR0_STRT;
        AREG = CSR0;
        DPRINTK( 2, ( "%s: lance_start_xmit() exiting, csr0 %4.4x.\n",
                                  dev->name, DREG ));
        dev_kfree_skb(skb);

        lp->lock = 0;
        if ((MEM->tx_head[(entry+1) & TX_RING_MOD_MASK].flag & TMD1_OWN) ==
            TMD1_OWN_HOST)
                netif_start_queue(dev);

        local_irq_restore(flags);

        return NETDEV_TX_OK;
}

/* The LANCE interrupt handler. */

static irqreturn_t lance_interrupt( int irq, void *dev_id)
{
        struct net_device *dev = dev_id;
        struct lance_private *lp = netdev_priv(dev);
        int csr0;

 still_more:
        flush_cache_all();

        AREG = CSR0;
        csr0 = DREG;

        /* ack interrupts */
        DREG = csr0 & (CSR0_TINT | CSR0_RINT | CSR0_IDON);

        /* clear errors */
        if(csr0 & CSR0_ERR)
                DREG = CSR0_BABL | CSR0_MERR | CSR0_CERR | CSR0_MISS;


        DPRINTK( 2, ( "%s: interrupt  csr0=%04x new csr=%04x.\n",
                      dev->name, csr0, DREG ));

        if (csr0 & CSR0_TINT) {                 /* Tx-done interrupt */
                int old_tx = lp->old_tx;

//              if(lance_debug >= 3) {
//                      int i;
//
//                      printk("%s: tx int\n", dev->name);
//
//                      for(i = 0; i < TX_RING_SIZE; i++)
//                              printk("ring %d flag=%04x\n", i,
//                                     MEM->tx_head[i].flag);
//              }

                while( old_tx != lp->new_tx) {
                        struct lance_tx_head *head = &(MEM->tx_head[old_tx]);

                        DPRINTK(3, ("on tx_ring %d\n", old_tx));

                        if (head->flag & TMD1_OWN_CHIP)
                                break; /* It still hasn't been Txed */

                        if (head->flag & TMD1_ERR) {
                                int status = head->misc;
                                dev->stats.tx_errors++;
                                if (status & TMD3_RTRY) dev->stats.tx_aborted_errors++;
                                if (status & TMD3_LCAR) dev->stats.tx_carrier_errors++;
                                if (status & TMD3_LCOL) dev->stats.tx_window_errors++;
                                if (status & (TMD3_UFLO | TMD3_BUFF)) {
                                        dev->stats.tx_fifo_errors++;
                                        printk("%s: Tx FIFO error\n",
                                               dev->name);
                                        REGA(CSR0) = CSR0_STOP;
                                        REGA(CSR3) = CSR3_BSWP;
                                        lance_init_ring(dev);
                                        REGA(CSR0) = CSR0_STRT | CSR0_INEA;
                                        return IRQ_HANDLED;
                                }
                        } else if(head->flag & (TMD1_ENP | TMD1_STP)) {

                                head->flag &= ~(TMD1_ENP | TMD1_STP);
                                if(head->flag & (TMD1_ONE | TMD1_MORE))
                                        dev->stats.collisions++;

                                dev->stats.tx_packets++;
                                DPRINTK(3, ("cleared tx ring %d\n", old_tx));
                        }
                        old_tx = (old_tx +1) & TX_RING_MOD_MASK;
                }

                lp->old_tx = old_tx;
        }


        if (netif_queue_stopped(dev)) {
                /* The ring is no longer full, clear tbusy. */
                netif_start_queue(dev);
                netif_wake_queue(dev);
        }

        if (csr0 & CSR0_RINT)                   /* Rx interrupt */
                lance_rx( dev );

        /* Log misc errors. */
        if (csr0 & CSR0_BABL) dev->stats.tx_errors++; /* Tx babble. */
        if (csr0 & CSR0_MISS) dev->stats.rx_errors++; /* Missed a Rx frame. */
        if (csr0 & CSR0_MERR) {
                DPRINTK( 1, ( "%s: Bus master arbitration failure (?!?), "
                              "status %04x.\n", dev->name, csr0 ));
                /* Restart the chip. */
                REGA(CSR0) = CSR0_STOP;
                REGA(CSR3) = CSR3_BSWP;
                lance_init_ring(dev);
                REGA(CSR0) = CSR0_STRT | CSR0_INEA;
        }


    /* Clear any other interrupt, and set interrupt enable. */
//      DREG = CSR0_BABL | CSR0_CERR | CSR0_MISS | CSR0_MERR |
//                 CSR0_IDON | CSR0_INEA;

        REGA(CSR0) = CSR0_INEA;

        if(DREG & (CSR0_RINT | CSR0_TINT)) {
             DPRINTK(2, ("restarting interrupt, csr0=%#04x\n", DREG));
             goto still_more;
        }

        DPRINTK( 2, ( "%s: exiting interrupt, csr0=%#04x.\n",
                                  dev->name, DREG ));
        return IRQ_HANDLED;
}

/* get packet, toss into skbuff */
static int lance_rx( struct net_device *dev )
{
        struct lance_private *lp = netdev_priv(dev);
        int entry = lp->new_rx;

        /* If we own the next entry, it's a new packet. Send it up. */
        while( (MEM->rx_head[entry].flag & RMD1_OWN) == RMD1_OWN_HOST ) {
                struct lance_rx_head *head = &(MEM->rx_head[entry]);
                int status = head->flag;

                if (status != (RMD1_ENP|RMD1_STP)) {  /* There was an error. */
                        /* There is a tricky error noted by John Murphy,
                           <murf@perftech.com> to Russ Nelson: Even with
                           full-sized buffers it's possible for a jabber packet to use two
                           buffers, with only the last correctly noting the error. */
                        if (status & RMD1_ENP)  /* Only count a general error at the */
                                dev->stats.rx_errors++; /* end of a packet.*/
                        if (status & RMD1_FRAM) dev->stats.rx_frame_errors++;
                        if (status & RMD1_OFLO) dev->stats.rx_over_errors++;
                        if (status & RMD1_CRC) dev->stats.rx_crc_errors++;
                        if (status & RMD1_BUFF) dev->stats.rx_fifo_errors++;
                        head->flag &= (RMD1_ENP|RMD1_STP);
                } else {
                        /* Malloc up new buffer, compatible with net-3. */
//                      short pkt_len = head->msg_length;// & 0xfff;
                        short pkt_len = (head->msg_length & 0xfff) - 4;
                        struct sk_buff *skb;

                        if (pkt_len < 60) {
                                printk( "%s: Runt packet!\n", dev->name );
                                dev->stats.rx_errors++;
                        }
                        else {
                                skb = netdev_alloc_skb(dev, pkt_len + 2);
                                if (!skb) {
                                        dev->stats.rx_dropped++;
                                        head->msg_length = 0;
                                        head->flag |= RMD1_OWN_CHIP;
                                        lp->new_rx = (lp->new_rx+1) &
                                             RX_RING_MOD_MASK;
                                }

#if 0
                                if (lance_debug >= 3) {
                                        u_char *data = PKTBUF_ADDR(head);
                                        printk("%s: RX pkt %d type 0x%04x"
                                               " from %pM to %pM",
                                               dev->name, lp->new_tx, ((u_short *)data)[6],
                                               &data[6], data);

                                        printk(" data %02x %02x %02x %02x %02x %02x %02x %02x "
                                               "len %d at %08x\n",
                                               data[15], data[16], data[17], data[18],
                                               data[19], data[20], data[21], data[22],
                                               pkt_len, data);
                                }
#endif
                                if (lance_debug >= 3) {
                                        u_char *data = PKTBUF_ADDR(head);
                                        printk( "%s: RX pkt %d type 0x%04x len %d\n ", dev->name, entry, ((u_short *)data)[6], pkt_len);
                                }


                                skb_reserve( skb, 2 );  /* 16 byte align */
                                skb_put( skb, pkt_len );        /* Make room */
                                skb_copy_to_linear_data(skb,
                                                 PKTBUF_ADDR(head),
                                                 pkt_len);

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

//              head->buf_length = -PKT_BUF_SZ | 0xf000;
                head->msg_length = 0;
                head->flag = RMD1_OWN_CHIP;

                entry = lp->new_rx = (lp->new_rx +1) & RX_RING_MOD_MASK;
        }

        /* From lance.c (Donald Becker): */
        /* We should check that at least two ring entries are free.
           If not, we should free one and mark stats->rx_dropped++. */

        return 0;
}


static int lance_close( struct net_device *dev )
{
        struct lance_private *lp = netdev_priv(dev);

        netif_stop_queue(dev);

        AREG = CSR0;

        DPRINTK( 2, ( "%s: Shutting down ethercard, status was %2.2x.\n",
                                  dev->name, DREG ));

        /* We stop the LANCE here -- it occasionally polls
           memory if we don't. */
        DREG = CSR0_STOP;
        return 0;
}


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

/* completely untested on a sun3 */
static void set_multicast_list( struct net_device *dev )
{
        struct lance_private *lp = netdev_priv(dev);

        if(netif_queue_stopped(dev))
                /* Only possible if board is already started */
                return;

        /* We take the simple way out and always enable promiscuous mode. */
        DREG = CSR0_STOP; /* Temporarily stop the lance. */

        if (dev->flags & IFF_PROMISC) {
                /* Log any net taps. */
                DPRINTK( 3, ( "%s: Promiscuous mode enabled.\n", dev->name ));
                REGA( CSR15 ) = 0x8000; /* Set promiscuous mode */
        } else {
                short multicast_table[4];
                int num_addrs = netdev_mc_count(dev);
                int i;
                /* We don't use the multicast table, but rely on upper-layer
                 * filtering. */
                memset( multicast_table, (num_addrs == 0) ? 0 : -1,
                                sizeof(multicast_table) );
                for( i = 0; i < 4; i++ )
                        REGA( CSR8+i ) = multicast_table[i];
                REGA( CSR15 ) = 0; /* Unset promiscuous mode */
        }

        /*
         * Always set BSWP after a STOP as STOP puts it back into
         * little endian mode.
         */
        REGA( CSR3 ) = CSR3_BSWP;

        /* Resume normal operation and reset AREG to CSR0 */
        REGA( CSR0 ) = CSR0_IDON | CSR0_INEA | CSR0_STRT;
}


static struct net_device *sun3lance_dev;

static int __init sun3lance_init(void)
{
        sun3lance_dev = sun3lance_probe();
        return PTR_ERR_OR_ZERO(sun3lance_dev);
}
module_init(sun3lance_init);

static void __exit sun3lance_cleanup(void)
{
        unregister_netdev(sun3lance_dev);
#ifdef CONFIG_SUN3
        iounmap((void __iomem *)sun3lance_dev->base_addr);
#endif
        free_netdev(sun3lance_dev);
}
module_exit(sun3lance_cleanup);