path: root/drivers/net/ariadne.c

/*
 *  Amiga Linux/m68k Ariadne Ethernet Driver
 *
 *  © Copyright 1995-2003 by Geert Uytterhoeven (geert@linux-m68k.org)
 *			     Peter De Schrijver (p2@mind.be)
 *
 *  ---------------------------------------------------------------------------
 *
 *  This program is based on
 *
 *	lance.c:	An AMD LANCE ethernet driver for linux.
 *			Written 1993-94 by Donald Becker.
 *
 *	Am79C960:	PCnet(tm)-ISA Single-Chip Ethernet Controller
 *			Advanced Micro Devices
 *			Publication #16907, Rev. B, Amendment/0, May 1994
 *
 *	MC68230:	Parallel Interface/Timer (PI/T)
 *			Motorola Semiconductors, December, 1983
 *
 *  ---------------------------------------------------------------------------
 *
 *  This file is subject to the terms and conditions of the GNU General Public
 *  License.  See the file COPYING in the main directory of the Linux
 *  distribution for more details.
 *
 *  ---------------------------------------------------------------------------
 *
 *  The Ariadne is a Zorro-II board made by Village Tronic. It contains:
 *
 *	- an Am79C960 PCnet-ISA Single-Chip Ethernet Controller with both
 *	  10BASE-2 (thin coax) and 10BASE-T (UTP) connectors
 *
 *	- an MC68230 Parallel Interface/Timer configured as 2 parallel ports
 */

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

#include <asm/amigaints.h>
#include <asm/amigahw.h>
#include <asm/irq.h>

#include "ariadne.h"


#ifdef ARIADNE_DEBUG
int ariadne_debug = ARIADNE_DEBUG;
#else
int ariadne_debug = 1;
#endif


    /*
     *	Macros to Fix Endianness problems
     */

				/* Swap the Bytes in a WORD */
#define swapw(x)	(((x>>8)&0x00ff)|((x<<8)&0xff00))
				/* Get the Low BYTE in a WORD */
#define lowb(x)		(x&0xff)
				/* Get the Swapped High WORD in a LONG */
#define swhighw(x)	((((x)>>8)&0xff00)|(((x)>>24)&0x00ff))
				/* Get the Swapped Low WORD in a LONG */
#define swloww(x)	((((x)<<8)&0xff00)|(((x)>>8)&0x00ff))


    /*
     *	Transmit/Receive Ring Definitions
     */

#define TX_RING_SIZE	5
#define RX_RING_SIZE	16

#define PKT_BUF_SIZE	1520


    /*
     *	Private Device Data
     */

struct ariadne_private {
    volatile struct TDRE *tx_ring[TX_RING_SIZE];
    volatile struct RDRE *rx_ring[RX_RING_SIZE];
    volatile u_short *tx_buff[TX_RING_SIZE];
    volatile u_short *rx_buff[RX_RING_SIZE];
    int cur_tx, cur_rx;			/* The next free ring entry */
    int dirty_tx;			/* The ring entries to be free()ed. */
    struct net_device_stats stats;
    char tx_full;
};


    /*
     *	Structure Created in the Ariadne's RAM Buffer
     */

struct lancedata {
    struct TDRE tx_ring[TX_RING_SIZE];
    struct RDRE rx_ring[RX_RING_SIZE];
    u_short tx_buff[TX_RING_SIZE][PKT_BUF_SIZE/sizeof(u_short)];
    u_short rx_buff[RX_RING_SIZE][PKT_BUF_SIZE/sizeof(u_short)];
};

static int ariadne_open(struct net_device *dev);
static void ariadne_init_ring(struct net_device *dev);
static int ariadne_start_xmit(struct sk_buff *skb, struct net_device *dev);
static void ariadne_tx_timeout(struct net_device *dev);
static int ariadne_rx(struct net_device *dev);
static void ariadne_reset(struct net_device *dev);
static irqreturn_t ariadne_interrupt(int irq, void *data, struct pt_regs *fp);
static int ariadne_close(struct net_device *dev);
static struct net_device_stats *ariadne_get_stats(struct net_device *dev);
#ifdef HAVE_MULTICAST
static void set_multicast_list(struct net_device *dev);
#endif


static void memcpyw(volatile u_short *dest, u_short *src, int len)
{
    while (len >= 2) {
	*(dest++) = *(src++);
	len -= 2;
    }
    if (len == 1)
	*dest = (*(u_char *)src)<<8;
}


static int __devinit ariadne_init_one(struct zorro_dev *z,
				      const struct zorro_device_id *ent);
static void __devexit ariadne_remove_one(struct zorro_dev *z);


static struct zorro_device_id ariadne_zorro_tbl[] __devinitdata = {
    { ZORRO_PROD_VILLAGE_TRONIC_ARIADNE },
    { 0 }
};

static struct zorro_driver ariadne_driver = {
    .name	= "ariadne",
    .id_table	= ariadne_zorro_tbl,
    .probe	= ariadne_init_one,
    .remove	= __devexit_p(ariadne_remove_one),
};

static int __devinit ariadne_init_one(struct zorro_dev *z,
				      const struct zorro_device_id *ent)
{
    unsigned long board = z->resource.start;
    unsigned long base_addr = board+ARIADNE_LANCE;
    unsigned long mem_start = board+ARIADNE_RAM;
    struct resource *r1, *r2;
    struct net_device *dev;
    struct ariadne_private *priv;
    int err;

    r1 = request_mem_region(base_addr, sizeof(struct Am79C960), "Am79C960");
    if (!r1)
	return -EBUSY;
    r2 = request_mem_region(mem_start, ARIADNE_RAM_SIZE, "RAM");
    if (!r2) {
	release_resource(r1);
	return -EBUSY;
    }

    dev = alloc_etherdev(sizeof(struct ariadne_private));
    if (dev == NULL) {
	release_resource(r1);
	release_resource(r2);
	return -ENOMEM;
    }

    SET_MODULE_OWNER(dev);
    priv = netdev_priv(dev);

    r1->name = dev->name;
    r2->name = dev->name;

    dev->dev_addr[0] = 0x00;
    dev->dev_addr[1] = 0x60;
    dev->dev_addr[2] = 0x30;
    dev->dev_addr[3] = (z->rom.er_SerialNumber>>16) & 0xff;
    dev->dev_addr[4] = (z->rom.er_SerialNumber>>8) & 0xff;
    dev->dev_addr[5] = z->rom.er_SerialNumber & 0xff;
    dev->base_addr = ZTWO_VADDR(base_addr);
    dev->mem_start = ZTWO_VADDR(mem_start);
    dev->mem_end = dev->mem_start+ARIADNE_RAM_SIZE;

    dev->open = &ariadne_open;
    dev->stop = &ariadne_close;
    dev->hard_start_xmit = &ariadne_start_xmit;
    dev->tx_timeout = &ariadne_tx_timeout;
    dev->watchdog_timeo = 5*HZ;
    dev->get_stats = &ariadne_get_stats;
    dev->set_multicast_list = &set_multicast_list;

    err = register_netdev(dev);
    if (err) {
	release_resource(r1);
	release_resource(r2);
	free_netdev(dev);
	return err;
    }
    zorro_set_drvdata(z, dev);

    printk(KERN_INFO "%s: Ariadne at 0x%08lx, Ethernet Address "
	   "%02x:%02x:%02x:%02x:%02x:%02x\n", dev->name, board,
	   dev->dev_addr[0], dev->dev_addr[1], dev->dev_addr[2],
	   dev->dev_addr[3], dev->dev_addr[4], dev->dev_addr[5]);

    return 0;
}


static int ariadne_open(struct net_device *dev)
{
    volatile struct Am79C960 *lance = (struct Am79C960*)dev->base_addr;
    u_short in;
    u_long version;
    int i;

    /* Reset the LANCE */
    in = lance->Reset;

    /* Stop the LANCE */
    lance->RAP = CSR0;		/* PCnet-ISA Controller Status */
    lance->RDP = STOP;

    /* Check the LANCE version */
    lance->RAP = CSR88;		/* Chip ID */
    version = swapw(lance->RDP);
    lance->RAP = CSR89;		/* Chip ID */
    version |= swapw(lance->RDP)<<16;
    if ((version & 0x00000fff) != 0x00000003) {
	printk(KERN_WARNING "ariadne_open: Couldn't find AMD Ethernet Chip\n");
	return -EAGAIN;
    }
    if ((version & 0x0ffff000) != 0x00003000) {
	printk(KERN_WARNING "ariadne_open: Couldn't find Am79C960 (Wrong part "
	       "number = %ld)\n", (version & 0x0ffff000)>>12);
	return -EAGAIN;
    }
#if 0
    printk(KERN_DEBUG "ariadne_open: Am79C960 (PCnet-ISA) Revision %ld\n",
	   (version & 0xf0000000)>>28);
#endif

    ariadne_init_ring(dev);

    /* Miscellaneous Stuff */
    lance->RAP = CSR3;		/* Interrupt Masks and Deferral Control */
    lance->RDP = 0x0000;
    lance->RAP = CSR4;		/* Test and Features Control */
    lance->RDP = DPOLL|APAD_XMT|MFCOM|RCVCCOM|TXSTRTM|JABM;

    /* Set the Multicast Table */
    lance->RAP = CSR8;		/* Logical Address Filter, LADRF[15:0] */
    lance->RDP = 0x0000;
    lance->RAP = CSR9;		/* Logical Address Filter, LADRF[31:16] */
    lance->RDP = 0x0000;
    lance->RAP = CSR10;		/* Logical Address Filter, LADRF[47:32] */
    lance->RDP = 0x0000;
    lance->RAP = CSR11;		/* Logical Address Filter, LADRF[63:48] */
    lance->RDP = 0x0000;

    /* Set the Ethernet Hardware Address */
    lance->RAP = CSR12;		/* Physical Address Register, PADR[15:0] */
    lance->RDP = ((u_short *)&dev->dev_addr[0])[0];
    lance->RAP = CSR13;		/* Physical Address Register, PADR[31:16] */
    lance->RDP = ((u_short *)&dev->dev_addr[0])[1];
    lance->RAP = CSR14;		/* Physical Address Register, PADR[47:32] */
    lance->RDP = ((u_short *)&dev->dev_addr[0])[2];

    /* Set the Init Block Mode */
    lance->RAP = CSR15;		/* Mode Register */
    lance->RDP = 0x0000;

    /* Set the Transmit Descriptor Ring Pointer */
    lance->RAP = CSR30;		/* Base Address of Transmit Ring */
    lance->RDP = swloww(ARIADNE_RAM+offsetof(struct lancedata, tx_ring));
    lance->RAP = CSR31;		/* Base Address of transmit Ring */
    lance->RDP = swhighw(ARIADNE_RAM+offsetof(struct lancedata, tx_ring));

    /* Set the Receive Descriptor Ring Pointer */
    lance->RAP = CSR24;		/* Base Address of Receive Ring */
    lance->RDP = swloww(ARIADNE_RAM+offsetof(struct lancedata, rx_ring));
    lance->RAP = CSR25;		/* Base Address of Receive Ring */
    lance->RDP = swhighw(ARIADNE_RAM+offsetof(struct lancedata, rx_ring));

    /* Set the Number of RX and TX Ring Entries */
    lance->RAP = CSR76;		/* Receive Ring Length */
    lance->RDP = swapw(((u_short)-RX_RING_SIZE));
    lance->RAP = CSR78;		/* Transmit Ring Length */
    lance->RDP = swapw(((u_short)-TX_RING_SIZE));

    /* Enable Media Interface Port Auto Select (10BASE-2/10BASE-T) */
    lance->RAP = ISACSR2;	/* Miscellaneous Configuration */
    lance->IDP = ASEL;

    /* LED Control */
    lance->RAP = ISACSR5;	/* LED1 Status */
    lance->IDP = PSE|XMTE;
    lance->RAP = ISACSR6;	/* LED2 Status */
    lance->IDP = PSE|COLE;
    lance->RAP = ISACSR7;	/* LED3 Status */
    lance->IDP = PSE|RCVE;

    netif_start_queue(dev);

    i = request_irq(IRQ_AMIGA_PORTS, ariadne_interrupt, SA_SHIRQ,
                    dev->name, dev);
    if (i) return i;

    lance->RAP = CSR0;		/* PCnet-ISA Controller Status */
    lance->RDP = INEA|STRT;

    return 0;
}


static void ariadne_init_ring(struct net_device *dev)
{
    struct ariadne_private *priv = netdev_priv(dev);
    volatile struct lancedata *lancedata = (struct lancedata *)dev->mem_start;
    int i;

    netif_stop_queue(dev);

    priv->tx_full = 0;
    priv->cur_rx = priv->cur_tx = 0;
    priv->dirty_tx = 0;

    /* Set up TX Ring */
    for (i = 0; i < TX_RING_SIZE; i++) {
	volatile struct TDRE *t = &lancedata->tx_ring[i];
	t->TMD0 = swloww(ARIADNE_RAM+offsetof(struct lancedata, tx_buff[i]));
	t->TMD1 = swhighw(ARIADNE_RAM+offsetof(struct lancedata, tx_buff[i])) |
		  TF_STP | TF_ENP;
	t->TMD2 = swapw((u_short)-PKT_BUF_SIZE);
	t->TMD3 = 0;
	priv->tx_ring[i] = &lancedata->tx_ring[i];
	priv->tx_buff[i] = lancedata->tx_buff[i];
#if 0
	printk(KERN_DEBUG "TX Entry %2d at %p, Buf at %p\n", i,
	       &lancedata->tx_ring[i], lancedata->tx_buff[i]);
#endif
    }

    /* Set up RX Ring */
    for (i = 0; i < RX_RING_SIZE; i++) {
	volatile struct RDRE *r = &lancedata->rx_ring[i];
	r->RMD0 = swloww(ARIADNE_RAM+offsetof(struct lancedata, rx_buff[i]));
	r->RMD1 = swhighw(ARIADNE_RAM+offsetof(struct lancedata, rx_buff[i])) |
		  RF_OWN;
	r->RMD2 = swapw((u_short)-PKT_BUF_SIZE);
	r->RMD3 = 0x0000;
	priv->rx_ring[i] = &lancedata->rx_ring[i];
	priv->rx_buff[i] = lancedata->rx_buff[i];
#if 0
	printk(KERN_DEBUG "RX Entry %2d at %p, Buf at %p\n", i,
	       &lancedata->rx_ring[i], lancedata->rx_buff[i]);
#endif
    }
}


static int ariadne_close(struct net_device *dev)
{
    struct ariadne_private *priv = netdev_priv(dev);
    volatile struct Am79C960 *lance = (struct Am79C960*)dev->base_addr;

    netif_stop_queue(dev);

    lance->RAP = CSR112;	/* Missed Frame Count */
    priv->stats.rx_missed_errors = swapw(lance->RDP);
    lance->RAP = CSR0;		/* PCnet-ISA Controller Status */

    if (ariadne_debug > 1) {
	printk(KERN_DEBUG "%s: Shutting down ethercard, status was %2.2x.\n",
	       dev->name, lance->RDP);
	printk(KERN_DEBUG "%s: %lu packets missed\n", dev->name,
	       priv->stats.rx_missed_errors);
    }

    /* We stop the LANCE here -- it occasionally polls memory if we don't. */
    lance->RDP = STOP;

    free_irq(IRQ_AMIGA_PORTS, dev);

    return 0;
}


static inline void ariadne_reset(struct net_device *dev)
{
    volatile struct Am79C960 *lance = (struct Am79C960*)dev->base_addr;

    lance->RAP = CSR0;	/* PCnet-ISA Controller Status */
    lance->RDP = STOP;
    ariadne_init_ring(dev);
    lance->RDP = INEA|STRT;
    netif_start_queue(dev);
}


static irqreturn_t ariadne_interrupt(int irq, void *data, struct pt_regs *fp)
{
    struct net_device *dev = (struct net_device *)data;
    volatile struct Am79C960 *lance = (struct Am79C960*)dev->base_addr;
    struct ariadne_private *priv;
    int csr0, boguscnt;
    int handled = 0;

    if (dev == NULL) {
	printk(KERN_WARNING "ariadne_interrupt(): irq for unknown device.\n");
	return IRQ_NONE;
    }

    lance->RAP = CSR0;			/* PCnet-ISA Controller Status */

    if (!(lance->RDP & INTR))		/* Check if any interrupt has been */
	return IRQ_NONE;		/* generated by the board. */

    priv = netdev_priv(dev);

    boguscnt = 10;
    while ((csr0 = lance->RDP) & (ERR|RINT|TINT) && --boguscnt >= 0) {
	/* Acknowledge all of the current interrupt sources ASAP. */
	lance->RDP = csr0 & ~(INEA|TDMD|STOP|STRT|INIT);

#if 0
	if (ariadne_debug > 5) {
	    printk(KERN_DEBUG "%s: interrupt  csr0=%#2.2x new csr=%#2.2x.",
		   dev->name, csr0, lance->RDP);
	    printk("[");
	    if (csr0 & INTR)
		printk(" INTR");
	    if (csr0 & INEA)
		printk(" INEA");
	    if (csr0 & RXON)
		printk(" RXON");
	    if (csr0 & TXON)
		printk(" TXON");
	    if (csr0 & TDMD)
		printk(" TDMD");
	    if (csr0 & STOP)
		printk(" STOP");
	    if (csr0 & STRT)
		printk(" STRT");
	    if (csr0 & INIT)
		printk(" INIT");
	    if (csr0 & ERR)
		printk(" ERR");
	    if (csr0 & BABL)
		printk(" BABL");
	    if (csr0 & CERR)
		printk(" CERR");
	    if (csr0 & MISS)
		printk(" MISS");
	    if (csr0 & MERR)
		printk(" MERR");
	    if (csr0 & RINT)
		printk(" RINT");
	    if (csr0 & TINT)
		printk(" TINT");
	    if (csr0 & IDON)
		printk(" IDON");
	    printk(" ]\n");
	}
#endif

	if (csr0 & RINT) {	/* Rx interrupt */
	    handled = 1;
	    ariadne_rx(dev);
	}

	if (csr0 & TINT) {	/* Tx-done interrupt */
	    int dirty_tx = priv->dirty_tx;

	    handled = 1;
	    while (dirty_tx < priv->cur_tx) {
		int entry = dirty_tx % TX_RING_SIZE;
		int status = lowb(priv->tx_ring[entry]->TMD1);

		if (status & TF_OWN)
		    break;	/* It still hasn't been Txed */

		priv->tx_ring[entry]->TMD1 &= 0xff00;

		if (status & TF_ERR) {
		    /* There was an major error, log it. */
		    int err_status = priv->tx_ring[entry]->TMD3;
		    priv->stats.tx_errors++;
		    if (err_status & EF_RTRY)
			priv->stats.tx_aborted_errors++;
		    if (err_status & EF_LCAR)
			priv->stats.tx_carrier_errors++;
		    if (err_status & EF_LCOL)
			priv->stats.tx_window_errors++;
		    if (err_status & EF_UFLO) {
			/* Ackk!  On FIFO errors the Tx unit is turned off! */
			priv->stats.tx_fifo_errors++;
			/* Remove this verbosity later! */
			printk(KERN_ERR "%s: Tx FIFO error! Status %4.4x.\n",
			       dev->name, csr0);
			/* Restart the chip. */
			lance->RDP = STRT;
		    }
		} else {
		    if (status & (TF_MORE|TF_ONE))
			priv->stats.collisions++;
		    priv->stats.tx_packets++;
		}
		dirty_tx++;
	    }

#ifndef final_version
	    if (priv->cur_tx - dirty_tx >= TX_RING_SIZE) {
		printk(KERN_ERR "out-of-sync dirty pointer, %d vs. %d, "
		       "full=%d.\n", dirty_tx, priv->cur_tx, priv->tx_full);
		dirty_tx += TX_RING_SIZE;
	    }
#endif

	    if (priv->tx_full && netif_queue_stopped(dev) &&
		dirty_tx > priv->cur_tx - TX_RING_SIZE + 2) {
		/* The ring is no longer full. */
		priv->tx_full = 0;
		netif_wake_queue(dev);
	    }

	    priv->dirty_tx = dirty_tx;
	}

	/* Log misc errors. */
	if (csr0 & BABL) {
	    handled = 1;
	    priv->stats.tx_errors++;	/* Tx babble. */
	}
	if (csr0 & MISS) {
	    handled = 1;
	    priv->stats.rx_errors++;	/* Missed a Rx frame. */
	}
	if (csr0 & MERR) {
	    handled = 1;
	    printk(KERN_ERR "%s: Bus master arbitration failure, status "
		   "%4.4x.\n", dev->name, csr0);
	    /* Restart the chip. */
	    lance->RDP = STRT;
	}
    }

    /* Clear any other interrupt, and set interrupt enable. */
    lance->RAP = CSR0;		/* PCnet-ISA Controller Status */
    lance->RDP = INEA|BABL|CERR|MISS|MERR|IDON;

#if 0
    if (ariadne_debug > 4)
	printk(KERN_DEBUG "%s: exiting interrupt, csr%d=%#4.4x.\n", dev->name,
	       lance->RAP, lance->RDP);
#endif
    return IRQ_RETVAL(handled);
}


static void ariadne_tx_timeout(struct net_device *dev)
{
    volatile struct Am79C960 *lance = (struct Am79C960*)dev->base_addr;

    printk(KERN_ERR "%s: transmit timed out, status %4.4x, resetting.\n",
	   dev->name, lance->RDP);
    ariadne_reset(dev);
    netif_wake_queue(dev);
}


static int ariadne_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
    struct ariadne_private *priv = netdev_priv(dev);
    volatile struct Am79C960 *lance = (struct Am79C960*)dev->base_addr;
    int entry;
    unsigned long flags;
    int len = skb->len;

#if 0
    if (ariadne_debug > 3) {
	lance->RAP = CSR0;	/* PCnet-ISA Controller Status */
	printk(KERN_DEBUG "%s: ariadne_start_xmit() called, csr0 %4.4x.\n",
	       dev->name, lance->RDP);
	lance->RDP = 0x0000;
    }
#endif

    /* FIXME: is the 79C960 new enough to do its own padding right ? */
    if (skb->len < ETH_ZLEN)
    {
    	skb = skb_padto(skb, ETH_ZLEN);
    	if (skb == NULL)
    	    return 0;
    	len = ETH_ZLEN;
    }

    /* Fill in a Tx ring entry */

#if 0
    printk(KERN_DEBUG "TX pkt type 0x%04x from ", ((u_short *)skb->data)[6]);
    {
	int i;
	u_char *ptr = &((u_char *)skb->data)[6];
	for (i = 0; i < 6; i++)
	    printk("%02x", ptr[i]);
    }
    printk(" to ");
    {
	int i;
	u_char *ptr = (u_char *)skb->data;
	for (i = 0; i < 6; i++)
	    printk("%02x", ptr[i]);
    }
    printk(" data 0x%08x len %d\n", (int)skb->data, (int)skb->len);
#endif

    local_irq_save(flags);

    entry = priv->cur_tx % TX_RING_SIZE;

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

    priv->tx_ring[entry]->TMD2 = swapw((u_short)-skb->len);
    priv->tx_ring[entry]->TMD3 = 0x0000;
    memcpyw(priv->tx_buff[entry], (u_short *)skb->data, len);

#if 0
    {
	int i, len;

	len = skb->len > 64 ? 64 : skb->len;
	len >>= 1;
	for (i = 0; i < len; i += 8) {
	    int j;
	    printk(KERN_DEBUG "%04x:", i);
	    for (j = 0; (j < 8) && ((i+j) < len); j++) {
		if (!(j & 1))
		    printk(" ");
		printk("%04x", priv->tx_buff[entry][i+j]);
	    }
	    printk("\n");
	}
    }
#endif

    priv->tx_ring[entry]->TMD1 = (priv->tx_ring[entry]->TMD1&0xff00)|TF_OWN|TF_STP|TF_ENP;

    dev_kfree_skb(skb);

    priv->cur_tx++;
    if ((priv->cur_tx >= TX_RING_SIZE) && (priv->dirty_tx >= TX_RING_SIZE)) {

#if 0
	printk(KERN_DEBUG "*** Subtracting TX_RING_SIZE from cur_tx (%d) and "
	       "dirty_tx (%d)\n", priv->cur_tx, priv->dirty_tx);
#endif

	priv->cur_tx -= TX_RING_SIZE;
	priv->dirty_tx -= TX_RING_SIZE;
    }

    /* Trigger an immediate send poll. */
    lance->RAP = CSR0;		/* PCnet-ISA Controller Status */
    lance->RDP = INEA|TDMD;

    dev->trans_start = jiffies;

    if (lowb(priv->tx_ring[(entry+1) % TX_RING_SIZE]->TMD1) != 0) {
	netif_stop_queue(dev);
	priv->tx_full = 1;
    }
    local_irq_restore(flags);

    return 0;
}


static int ariadne_rx(struct net_device *dev)
{
    struct ariadne_private *priv = netdev_priv(dev);
    int entry = priv->cur_rx % RX_RING_SIZE;
    int i;

    /* If we own the next entry, it's a new packet. Send it up. */
    while (!(lowb(priv->rx_ring[entry]->RMD1) & RF_OWN)) {
	int status = lowb(priv->rx_ring[entry]->RMD1);

	if (status != (RF_STP|RF_ENP)) {	/* 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 & RF_ENP)
		/* Only count a general error at the end of a packet.*/
		priv->stats.rx_errors++;
	    if (status & RF_FRAM)
		priv->stats.rx_frame_errors++;
	    if (status & RF_OFLO)
		priv->stats.rx_over_errors++;
	    if (status & RF_CRC)
		priv->stats.rx_crc_errors++;
	    if (status & RF_BUFF)
		priv->stats.rx_fifo_errors++;
	    priv->rx_ring[entry]->RMD1 &= 0xff00|RF_STP|RF_ENP;
	} else {
	    /* Malloc up new buffer, compatible with net-3. */
	    short pkt_len = swapw(priv->rx_ring[entry]->RMD3);
	    struct sk_buff *skb;

	    skb = dev_alloc_skb(pkt_len+2);
	    if (skb == NULL) {
		printk(KERN_WARNING "%s: Memory squeeze, deferring packet.\n",
		       dev->name);
		for (i = 0; i < RX_RING_SIZE; i++)
		    if (lowb(priv->rx_ring[(entry+i) % RX_RING_SIZE]->RMD1) & RF_OWN)
			break;

		if (i > RX_RING_SIZE-2) {
		    priv->stats.rx_dropped++;
		    priv->rx_ring[entry]->RMD1 |= RF_OWN;
		    priv->cur_rx++;
		}
		break;
	    }


	    skb->dev = dev;
	    skb_reserve(skb,2);		/* 16 byte align */
	    skb_put(skb,pkt_len);	/* Make room */
	    eth_copy_and_sum(skb, (char *)priv->rx_buff[entry], pkt_len,0);
	    skb->protocol=eth_type_trans(skb,dev);
#if 0
	    printk(KERN_DEBUG "RX pkt type 0x%04x from ",
		   ((u_short *)skb->data)[6]);
	    {
		int i;
		u_char *ptr = &((u_char *)skb->data)[6];
		for (i = 0; i < 6; i++)
		    printk("%02x", ptr[i]);
	    }
	    printk(" to ");
	    {
		int i;
		u_char *ptr = (u_char *)skb->data;
		for (i = 0; i < 6; i++)
		    printk("%02x", ptr[i]);
	    }
	    printk(" data 0x%08x len %d\n", (int)skb->data, (int)skb->len);
#endif

	    netif_rx(skb);
	    dev->last_rx = jiffies;
	    priv->stats.rx_packets++;
	    priv->stats.rx_bytes += pkt_len;
	}

	priv->rx_ring[entry]->RMD1 |= RF_OWN;
	entry = (++priv->cur_rx) % RX_RING_SIZE;
    }

    priv->cur_rx = priv->cur_rx % RX_RING_SIZE;

    /* 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 struct net_device_stats *ariadne_get_stats(struct net_device *dev)
{
    struct ariadne_private *priv = netdev_priv(dev);
    volatile struct Am79C960 *lance = (struct Am79C960*)dev->base_addr;
    short saved_addr;
    unsigned long flags;

    local_irq_save(flags);
    saved_addr = lance->RAP;
    lance->RAP = CSR112;		/* Missed Frame Count */
    priv->stats.rx_missed_errors = swapw(lance->RDP);
    lance->RAP = saved_addr;
    local_irq_restore(flags);

    return &priv->stats;
}


/* 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.
 */
static void set_multicast_list(struct net_device *dev)
{
    volatile struct Am79C960 *lance = (struct Am79C960*)dev->base_addr;

    if (!netif_running(dev))
	return;

    netif_stop_queue(dev);

    /* We take the simple way out and always enable promiscuous mode. */
    lance->RAP = CSR0;			/* PCnet-ISA Controller Status */
    lance->RDP = STOP;			/* Temporarily stop the lance. */
    ariadne_init_ring(dev);

    if (dev->flags & IFF_PROMISC) {
	/* Log any net taps. */
	printk(KERN_INFO "%s: Promiscuous mode enabled.\n", dev->name);
	lance->RAP = CSR15;		/* Mode Register */
	lance->RDP = PROM;		/* Set promiscuous mode */
    } else {
	short multicast_table[4];
	int num_addrs = dev->mc_count;
	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++) {
	    lance->RAP = CSR8+(i<<8);	/* Logical Address Filter */
	    lance->RDP = swapw(multicast_table[i]);
	}
	lance->RAP = CSR15;		/* Mode Register */
	lance->RDP = 0x0000;		/* Unset promiscuous mode */
    }

    lance->RAP = CSR0;			/* PCnet-ISA Controller Status */
    lance->RDP = INEA|STRT|IDON;	/* Resume normal operation. */

    netif_wake_queue(dev);
}


static void __devexit ariadne_remove_one(struct zorro_dev *z)
{
    struct net_device *dev = zorro_get_drvdata(z);

    unregister_netdev(dev);
    release_mem_region(ZTWO_PADDR(dev->base_addr), sizeof(struct Am79C960));
    release_mem_region(ZTWO_PADDR(dev->mem_start), ARIADNE_RAM_SIZE);
    free_netdev(dev);
}

static int __init ariadne_init_module(void)
{
    return zorro_register_driver(&ariadne_driver);
}

static void __exit ariadne_cleanup_module(void)
{
    zorro_unregister_driver(&ariadne_driver);
}

module_init(ariadne_init_module);
module_exit(ariadne_cleanup_module);

MODULE_LICENSE("GPL");