Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 948 insertions, 0 deletions

diff --git a/drivers/net/znet.c b/drivers/net/znet.c
new file mode 100644
index 000000000000..3ac047bc727d
--- /dev/null
+++ b/drivers/net/znet.c
@@ -0,0 +1,948 @@
+/* znet.c: An Zenith Z-Note ethernet driver for linux. */
+
+/*
+	Written by Donald Becker.
+
+	The author may be reached as becker@scyld.com.
+	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.
+ */
+
+/* 10/2002
+
+   o Resurected for Linux 2.5+ by Marc Zyngier <maz@wild-wind.fr.eu.org> :
+
+   - Removed strange DMA snooping in znet_sent_packet, which lead to
+     TX buffer corruption on my laptop.
+   - Use init_etherdev stuff.
+   - Use kmalloc-ed DMA buffers.
+   - Use as few global variables as possible.
+   - Use proper resources management.
+   - Use wireless/i82593.h as much as possible (structure, constants)
+   - Compiles as module or build-in.
+   - Now survives unplugging/replugging cable.
+
+   Some code was taken from wavelan_cs.
+   
+   Tested on a vintage Zenith Z-Note 433Lnp+. Probably broken on
+   anything else. Testers (and detailed bug reports) are welcome :-).
+
+   o TODO :
+
+   - Properly handle multicast
+   - Understand why some traffic patterns add a 1s latency...
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/if_arp.h>
+#include <linux/bitops.h>
+
+#include <asm/system.h>
+#include <asm/io.h>
+#include <asm/dma.h>
+
+/* This include could be elsewhere, since it is not wireless specific */
+#include "wireless/i82593.h"
+
+static char version[] __initdata = "znet.c:v1.02 9/23/94 becker@scyld.com\n";
+
+#ifndef ZNET_DEBUG
+#define ZNET_DEBUG 1
+#endif
+static unsigned int znet_debug = ZNET_DEBUG;
+module_param (znet_debug, int, 0);
+MODULE_PARM_DESC (znet_debug, "ZNet debug level");
+MODULE_LICENSE("GPL");
+
+/* 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 RX_BUF_SIZE 8192
+#define TX_BUF_SIZE 8192
+#define DMA_BUF_SIZE (RX_BUF_SIZE + 16)	/* 8k + 16 bytes for trailers */
+
+#define TX_TIMEOUT	10
+
+struct znet_private {
+	int rx_dma, tx_dma;
+	struct net_device_stats stats;
+	spinlock_t lock;
+	short sia_base, sia_size, io_size;
+	struct i82593_conf_block i593_init;
+	/* 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 net_device *znet_dev;
+
+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;
+};
+
+static int	znet_open(struct net_device *dev);
+static int	znet_send_packet(struct sk_buff *skb, struct net_device *dev);
+static irqreturn_t znet_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+static void	znet_rx(struct net_device *dev);
+static int	znet_close(struct net_device *dev);
+static struct net_device_stats *net_get_stats(struct net_device *dev);
+static void hardware_init(struct net_device *dev);
+static void update_stop_hit(short ioaddr, unsigned short rx_stop_offset);
+static void znet_tx_timeout (struct net_device *dev);
+
+/* Request needed resources */
+static int znet_request_resources (struct net_device *dev)
+{
+	struct znet_private *znet = dev->priv;
+	unsigned long flags;
+		
+	if (request_irq (dev->irq, &znet_interrupt, 0, "ZNet", dev))
+		goto failed;
+	if (request_dma (znet->rx_dma, "ZNet rx"))
+		goto free_irq;
+	if (request_dma (znet->tx_dma, "ZNet tx"))
+		goto free_rx_dma;
+	if (!request_region (znet->sia_base, znet->sia_size, "ZNet SIA"))
+		goto free_tx_dma;
+	if (!request_region (dev->base_addr, znet->io_size, "ZNet I/O"))
+		goto free_sia;
+
+	return 0;				/* Happy ! */
+
+ free_sia:
+	release_region (znet->sia_base, znet->sia_size);
+ free_tx_dma:
+	flags = claim_dma_lock();
+	free_dma (znet->tx_dma);
+	release_dma_lock (flags);
+ free_rx_dma:
+	flags = claim_dma_lock();
+	free_dma (znet->rx_dma);
+	release_dma_lock (flags);
+ free_irq:
+	free_irq (dev->irq, dev);
+ failed:
+	return -1;
+}
+
+static void znet_release_resources (struct net_device *dev)
+{
+	struct znet_private *znet = dev->priv;
+	unsigned long flags;
+		
+	release_region (znet->sia_base, znet->sia_size);
+	release_region (dev->base_addr, znet->io_size);
+	flags = claim_dma_lock();
+	free_dma (znet->tx_dma);
+	free_dma (znet->rx_dma);
+	release_dma_lock (flags);
+	free_irq (dev->irq, dev);
+}
+
+/* Keep the magical SIA stuff in a single function... */
+static void znet_transceiver_power (struct net_device *dev, int on)
+{
+	struct znet_private *znet = dev->priv;
+	unsigned char v;
+
+	/* Turn on/off the 82501 SIA, using zenith-specific magic. */
+	/* Select LAN control register */
+	outb(0x10, znet->sia_base);
+
+	if (on)
+		v = inb(znet->sia_base + 1) | 0x84;
+	else
+		v = inb(znet->sia_base + 1) & ~0x84;
+		
+	outb(v, znet->sia_base+1); /* Turn on/off LAN power (bit 2). */
+}
+
+/* Init the i82593, with current promisc/mcast configuration.
+   Also used from hardware_init. */
+static void znet_set_multicast_list (struct net_device *dev)
+{
+	struct znet_private *znet = dev->priv;
+	short ioaddr = dev->base_addr;
+	struct i82593_conf_block *cfblk = &znet->i593_init;
+
+	memset(cfblk, 0x00, sizeof(struct i82593_conf_block));
+	
+        /* 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. */
+
+	/* maz : Rewritten to take advantage of the wanvelan includes.
+	   At least we have names, not just blind values */
+	
+	/* Byte 0 */
+	cfblk->fifo_limit = 10;	/* = 16 B rx and 80 B tx fifo thresholds */
+	cfblk->forgnesi = 0;	/* 0=82C501, 1=AMD7992B compatibility */
+	cfblk->fifo_32 = 1;
+	cfblk->d6mod = 0;  	/* Run in i82593 advanced mode */
+	cfblk->throttle_enb = 1;
+
+	/* Byte 1 */
+	cfblk->throttle = 8;	/* Continuous w/interrupts, 128-clock DMA. */
+	cfblk->cntrxint = 0;	/* enable continuous mode receive interrupts */
+	cfblk->contin = 1;	/* enable continuous mode */
+
+	/* Byte 2 */
+	cfblk->addr_len = ETH_ALEN;
+	cfblk->acloc = 1;	/* Disable source addr insertion by i82593 */
+	cfblk->preamb_len = 2;	/* 8 bytes preamble */
+	cfblk->loopback = 0;	/* Loopback off */
+  
+	/* Byte 3 */
+	cfblk->lin_prio = 0;	/* Default priorities & backoff methods. */
+	cfblk->tbofstop = 0;
+	cfblk->exp_prio = 0;
+	cfblk->bof_met = 0;
+  
+	/* Byte 4 */
+	cfblk->ifrm_spc = 6;	/* 96 bit times interframe spacing */
+	
+	/* Byte 5 */
+	cfblk->slottim_low = 0; /* 512 bit times slot time (low) */
+	
+	/* Byte 6 */
+	cfblk->slottim_hi = 2;	/* 512 bit times slot time (high) */
+	cfblk->max_retr = 15;	/* 15 collisions retries */
+	
+	/* Byte 7 */
+	cfblk->prmisc = ((dev->flags & IFF_PROMISC) ? 1 : 0); /* Promiscuous mode */
+	cfblk->bc_dis = 0;	/* Enable broadcast reception */
+	cfblk->crs_1 = 0;	/* Don't transmit without carrier sense */
+	cfblk->nocrc_ins = 0;	/* i82593 generates CRC */
+	cfblk->crc_1632 = 0;	/* 32-bit Autodin-II CRC */
+	cfblk->crs_cdt = 0;	/* CD not to be interpreted as CS */
+	
+	/* Byte 8 */
+	cfblk->cs_filter = 0;  	/* CS is recognized immediately */
+	cfblk->crs_src = 0;	/* External carrier sense */
+	cfblk->cd_filter = 0;  	/* CD is recognized immediately */
+	
+	/* Byte 9 */
+	cfblk->min_fr_len = ETH_ZLEN >> 2; /* Minimum frame length */
+	
+	/* Byte A */
+	cfblk->lng_typ = 1;	/* Type/length checks OFF */
+	cfblk->lng_fld = 1; 	/* Disable 802.3 length field check */
+	cfblk->rxcrc_xf = 1;	/* Don't transfer CRC to memory */
+	cfblk->artx = 1;	/* Disable automatic retransmission */
+	cfblk->sarec = 1;	/* Disable source addr trig of CD */
+	cfblk->tx_jabber = 0;	/* Disable jabber jam sequence */
+	cfblk->hash_1 = 1; 	/* Use bits 0-5 in mc address hash */
+	cfblk->lbpkpol = 0; 	/* Loopback pin active high */
+	
+	/* Byte B */
+	cfblk->fdx = 0;		/* Disable full duplex operation */
+	
+	/* Byte C */
+	cfblk->dummy_6 = 0x3f; 	/* all ones, Default multicast addresses & backoff. */
+	cfblk->mult_ia = 0;	/* No multiple individual addresses */
+	cfblk->dis_bof = 0;	/* Disable the backoff algorithm ?! */
+	
+	/* Byte D */
+	cfblk->dummy_1 = 1; 	/* set to 1 */
+	cfblk->tx_ifs_retrig = 3; /* Hmm... Disabled */
+	cfblk->mc_all = (dev->mc_list || (dev->flags&IFF_ALLMULTI));/* multicast all mode */
+	cfblk->rcv_mon = 0;	/* Monitor mode disabled */
+	cfblk->frag_acpt = 0;	/* Do not accept fragments */
+	cfblk->tstrttrs = 0;	/* No start transmission threshold */
+	
+	/* Byte E */
+	cfblk->fretx = 1;	/* FIFO automatic retransmission */
+	cfblk->runt_eop = 0;	/* drop "runt" packets */
+	cfblk->hw_sw_pin = 0;	/* ?? */
+	cfblk->big_endn = 0;	/* Big Endian ? no... */
+	cfblk->syncrqs = 1;	/* Synchronous DRQ deassertion... */
+	cfblk->sttlen = 1;  	/* 6 byte status registers */
+	cfblk->rx_eop = 0;  	/* Signal EOP on packet reception */
+	cfblk->tx_eop = 0;  	/* Signal EOP on packet transmission */
+
+	/* Byte F */
+	cfblk->rbuf_size = RX_BUF_SIZE >> 12; /* Set receive buffer size */
+	cfblk->rcvstop = 1; 	/* Enable Receive Stop Register */
+
+	if (znet_debug > 2) {
+		int i;
+		unsigned char *c;
+
+		for (i = 0, c = (char *) cfblk; i < sizeof (*cfblk); i++)
+			printk ("%02X ", c[i]);
+		printk ("\n");
+	}
+	
+	*znet->tx_cur++ = sizeof(struct i82593_conf_block);
+	memcpy(znet->tx_cur, cfblk, sizeof(struct i82593_conf_block));
+	znet->tx_cur += sizeof(struct i82593_conf_block)/2;
+	outb(OP0_CONFIGURE | CR0_CHNL, ioaddr);
+
+	/* XXX FIXME maz : Add multicast addresses here, so having a
+	 * multicast address configured isn't equal to IFF_ALLMULTI */
+}
+
+/* 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. */
+
+static int __init znet_probe (void)
+{
+	int i;
+	struct netidblk *netinfo;
+	struct znet_private *znet;
+	struct net_device *dev;
+	char *p;
+	int err = -ENOMEM;
+
+	/* This code scans the region 0xf0000 to 0xfffff for a "NETIDBLK". */
+	for(p = (char *)phys_to_virt(0xf0000); p < (char *)phys_to_virt(0x100000); p++)
+		if (*p == 'N'  &&  strncmp(p, "NETIDBLK", 8) == 0)
+			break;
+
+	if (p >= (char *)phys_to_virt(0x100000)) {
+		if (znet_debug > 1)
+			printk(KERN_INFO "No Z-Note ethernet adaptor found.\n");
+		return -ENODEV;
+	}
+
+	dev = alloc_etherdev(sizeof(struct znet_private));
+	if (!dev)
+		return -ENOMEM;
+
+	SET_MODULE_OWNER (dev);
+
+	znet = dev->priv;
+
+	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(KERN_INFO "%s", version);
+
+	znet->rx_dma = netinfo->dma1;
+	znet->tx_dma = netinfo->dma2;
+	spin_lock_init(&znet->lock);
+	znet->sia_base = 0xe6;	/* Magic address for the 82501 SIA */
+	znet->sia_size = 2;
+	/* maz: Despite the '593 being advertised above as using a
+	 * single 8bits I/O port, this driver does many 16bits
+	 * access. So set io_size accordingly */
+	znet->io_size  = 2;
+
+	if (!(znet->rx_start = kmalloc (DMA_BUF_SIZE, GFP_KERNEL | GFP_DMA)))
+		goto free_dev;
+	if (!(znet->tx_start = kmalloc (DMA_BUF_SIZE, GFP_KERNEL | GFP_DMA)))
+		goto free_rx;
+
+	if (!dma_page_eq (znet->rx_start, znet->rx_start + (RX_BUF_SIZE/2-1)) ||
+	    !dma_page_eq (znet->tx_start, znet->tx_start + (TX_BUF_SIZE/2-1))) {
+		printk (KERN_WARNING "tx/rx crossing DMA frontiers, giving up\n");
+		goto free_tx;
+	}
+	
+	znet->rx_end = znet->rx_start + RX_BUF_SIZE/2;
+	znet->tx_buf_len = TX_BUF_SIZE/2;
+	znet->tx_end = znet->tx_start + znet->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 = &znet_set_multicast_list;
+	dev->tx_timeout = znet_tx_timeout;
+	dev->watchdog_timeo = TX_TIMEOUT;
+	err = register_netdev(dev);
+	if (err)
+		goto free_tx;
+	znet_dev = dev;
+	return 0;
+
+ free_tx:
+	kfree(znet->tx_start);
+ free_rx:
+	kfree(znet->rx_start);
+ free_dev:
+	free_netdev(dev);
+	return err;
+}
+
+
+static int znet_open(struct net_device *dev)
+{
+	int ioaddr = dev->base_addr;
+
+	if (znet_debug > 2)
+		printk(KERN_DEBUG "%s: znet_open() called.\n", dev->name);
+
+	/* These should never fail.  You can't add devices to a sealed box! */
+	if (znet_request_resources (dev)) {
+		printk(KERN_WARNING "%s: Not opened -- resource busy?!?\n", dev->name);
+		return -EBUSY;
+	}
+
+	znet_transceiver_power (dev, 1);
+	
+	/* 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. */
+
+	/* maz : Well, I'm getting every time the following message
+	 * without the delay on a 486@33. This machine is much too
+	 * fast... :-) So maybe the Crynwr driver wasn't wrong after
+	 * all, even if the message is completly harmless on my
+	 * setup. */
+	mdelay (50);
+	
+	/* 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);
+
+	hardware_init(dev);
+	netif_start_queue (dev);
+
+	return 0;
+}
+
+
+static void znet_tx_timeout (struct net_device *dev)
+{
+	int ioaddr = dev->base_addr;
+	ushort event, tx_status, rx_offset, state;
+
+	outb (CR0_STATUS_0, ioaddr);
+	event = inb (ioaddr);
+	outb (CR0_STATUS_1, ioaddr);
+	tx_status = inw (ioaddr);
+	outb (CR0_STATUS_2, ioaddr);
+	rx_offset = inw (ioaddr);
+	outb (CR0_STATUS_3, 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 == TX_LOST_CRS)
+		printk (KERN_WARNING "%s: Tx carrier error, check transceiver cable.\n",
+			dev->name);
+	outb (OP0_RESET, ioaddr);
+	hardware_init (dev);
+	netif_wake_queue (dev);
+}
+
+static int znet_send_packet(struct sk_buff *skb, struct net_device *dev)
+{
+	int ioaddr = dev->base_addr;
+	struct znet_private *znet = dev->priv;
+	unsigned long flags;
+	short length = skb->len;
+
+	if (znet_debug > 4)
+		printk(KERN_DEBUG "%s: ZNet_send_packet.\n", dev->name);
+
+	if (length < ETH_ZLEN) {
+		skb = skb_padto(skb, ETH_ZLEN);
+		if (skb == NULL)
+			return 0;
+		length = ETH_ZLEN;
+	}
+	
+	netif_stop_queue (dev);
+	
+	/* Check that the part hasn't reset itself, probably from suspend. */
+	outb(CR0_STATUS_0, ioaddr);
+	if (inw(ioaddr) == 0x0010 &&
+	    inw(ioaddr) == 0x0000 &&
+	    inw(ioaddr) == 0x0010) {
+		if (znet_debug > 1)
+			printk (KERN_WARNING "%s : waking up\n", dev->name);
+		hardware_init(dev);
+		znet_transceiver_power (dev, 1);
+	}
+
+	if (1) {
+		unsigned char *buf = (void *)skb->data;
+		ushort *tx_link = znet->tx_cur - 1;
+		ushort rnd_len = (length + 1)>>1;
+		
+		znet->stats.tx_bytes+=length;
+
+		if (znet->tx_cur >= znet->tx_end)
+		  znet->tx_cur = znet->tx_start;
+		*znet->tx_cur++ = length;
+		if (znet->tx_cur + rnd_len + 1 > znet->tx_end) {
+			int semi_cnt = (znet->tx_end - znet->tx_cur)<<1; /* Cvrt to byte cnt. */
+			memcpy(znet->tx_cur, buf, semi_cnt);
+			rnd_len -= semi_cnt>>1;
+			memcpy(znet->tx_start, buf + semi_cnt, length - semi_cnt);
+			znet->tx_cur = znet->tx_start + rnd_len;
+		} else {
+			memcpy(znet->tx_cur, buf, skb->len);
+			znet->tx_cur += rnd_len;
+		}
+		*znet->tx_cur++ = 0;
+
+		spin_lock_irqsave(&znet->lock, flags);
+		{
+			*tx_link = OP0_TRANSMIT | CR0_CHNL;
+			/* Is this always safe to do? */
+			outb(OP0_TRANSMIT | CR0_CHNL, ioaddr);
+		}
+		spin_unlock_irqrestore (&znet->lock, flags);
+
+		dev->trans_start = jiffies;
+		netif_start_queue (dev);
+
+		if (znet_debug > 4)
+		  printk(KERN_DEBUG "%s: Transmitter queued, length %d.\n", dev->name, length);
+	}
+	dev_kfree_skb(skb); 
+	return 0;
+}
+
+/* The ZNET interrupt handler. */
+static irqreturn_t znet_interrupt(int irq, void *dev_id, struct pt_regs * regs)
+{
+	struct net_device *dev = dev_id;
+	struct znet_private *znet = dev->priv;
+	int ioaddr;
+	int boguscnt = 20;
+	int handled = 0;
+
+	if (dev == NULL) {
+		printk(KERN_WARNING "znet_interrupt(): IRQ %d for unknown device.\n", irq);
+		return IRQ_NONE;
+	}
+
+	spin_lock (&znet->lock);
+	
+	ioaddr = dev->base_addr;
+
+	outb(CR0_STATUS_0, ioaddr);
+	do {
+		ushort status = inb(ioaddr);
+		if (znet_debug > 5) {
+			ushort result, rx_ptr, running;
+			outb(CR0_STATUS_1, ioaddr);
+			result = inw(ioaddr);
+			outb(CR0_STATUS_2, ioaddr);
+			rx_ptr = inw(ioaddr);
+			outb(CR0_STATUS_3, 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 & SR0_INTERRUPT) == 0)
+			break;
+
+		handled = 1;
+
+		if ((status & SR0_EVENT_MASK) == SR0_TRANSMIT_DONE ||
+		    (status & SR0_EVENT_MASK) == SR0_RETRANSMIT_DONE ||
+		    (status & SR0_EVENT_MASK) == SR0_TRANSMIT_NO_CRC_DONE) {
+			int tx_status;
+			outb(CR0_STATUS_1, ioaddr);
+			tx_status = inw(ioaddr);
+			/* It's undocumented, but tx_status seems to match the i82586. */
+			if (tx_status & TX_OK) {
+				znet->stats.tx_packets++;
+				znet->stats.collisions += tx_status & TX_NCOL_MASK;
+			} else {
+				if (tx_status & (TX_LOST_CTS | TX_LOST_CRS))
+					znet->stats.tx_carrier_errors++;
+				if (tx_status & TX_UND_RUN)
+					znet->stats.tx_fifo_errors++;
+				if (!(tx_status & TX_HRT_BEAT))
+					znet->stats.tx_heartbeat_errors++;
+				if (tx_status & TX_MAX_COL)
+					znet->stats.tx_aborted_errors++;
+				/* ...and the catch-all. */
+				if ((tx_status | (TX_LOST_CRS | TX_LOST_CTS | TX_UND_RUN | TX_HRT_BEAT | TX_MAX_COL)) != (TX_LOST_CRS | TX_LOST_CTS | TX_UND_RUN | TX_HRT_BEAT | TX_MAX_COL))
+					znet->stats.tx_errors++;
+
+				/* Transceiver may be stuck if cable
+				 * was removed while emiting a
+				 * packet. Flip it off, then on to
+				 * reset it. This is very empirical,
+				 * but it seems to work. */
+				
+				znet_transceiver_power (dev, 0);
+				znet_transceiver_power (dev, 1);
+			}
+			netif_wake_queue (dev);
+		}
+
+		if ((status & SR0_RECEPTION) ||
+		    (status & SR0_EVENT_MASK) == SR0_STOP_REG_HIT) {
+			znet_rx(dev);
+		}
+		/* Clear the interrupts we've handled. */
+		outb(CR0_INT_ACK, ioaddr);
+	} while (boguscnt--);
+
+	spin_unlock (&znet->lock);
+	
+	return IRQ_RETVAL(handled);
+}
+
+static void znet_rx(struct net_device *dev)
+{
+	struct znet_private *znet = 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(CR0_STATUS_2, ioaddr);
+	cur_frame_end_offset = inw(ioaddr);
+
+	if (cur_frame_end_offset == znet->rx_cur - znet->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 (znet->rx_start + cur_frame_end_offset != znet->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(znet->rx_end, znet->rx_start, 8);
+			cur_frame_end_offset += (RX_BUF_SIZE/2);
+		}
+		cur_frame_end = znet->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 = znet->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 & RX_RCV_OK)) { /* There was an error. */
+			znet->stats.rx_errors++;
+			if (status & RX_CRC_ERR) znet->stats.rx_crc_errors++;
+			if (status & RX_ALG_ERR) znet->stats.rx_frame_errors++;
+#if 0
+			if (status & 0x0200) znet->stats.rx_over_errors++; /* Wrong. */
+			if (status & 0x0100) znet->stats.rx_fifo_errors++;
+#else
+			/* maz : Wild guess... */
+			if (status & RX_OVRRUN) znet->stats.rx_over_errors++;
+#endif
+			if (status & RX_SRT_FRM) znet->stats.rx_length_errors++;
+		} else if (pkt_len > 1536) {
+			znet->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);
+				znet->stats.rx_dropped++;
+				break;
+			}
+			skb->dev = dev;
+
+			if (&znet->rx_cur[(pkt_len+1)>>1] > znet->rx_end) {
+				int semi_cnt = (znet->rx_end - znet->rx_cur)<<1;
+				memcpy(skb_put(skb,semi_cnt), znet->rx_cur, semi_cnt);
+				memcpy(skb_put(skb,pkt_len-semi_cnt), znet->rx_start,
+					   pkt_len - semi_cnt);
+			} else {
+				memcpy(skb_put(skb,pkt_len), znet->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);
+		  dev->last_rx = jiffies;
+		  znet->stats.rx_packets++;
+		  znet->stats.rx_bytes += pkt_len;
+		}
+		znet->rx_cur = this_rfp_ptr;
+		if (znet->rx_cur >= znet->rx_end)
+			znet->rx_cur -= RX_BUF_SIZE/2;
+		update_stop_hit(ioaddr, (znet->rx_cur - znet->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 = znet->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 net_device *dev)
+{
+	int ioaddr = dev->base_addr;
+
+	netif_stop_queue (dev);
+
+	outb(OP0_RESET, ioaddr);			/* CMD0_RESET */
+
+	if (znet_debug > 1)
+		printk(KERN_DEBUG "%s: Shutting down ethercard.\n", dev->name);
+	/* Turn off transceiver power. */
+	znet_transceiver_power (dev, 0);
+	
+	znet_release_resources (dev);
+	
+	return 0;
+}
+
+/* Get the current statistics.	This may be called with the card open or
+   closed. */
+static struct net_device_stats *net_get_stats(struct net_device *dev)
+{
+	struct znet_private *znet = dev->priv;
+
+	return &znet->stats;
+}
+
+static void show_dma(struct net_device *dev)
+{
+	short ioaddr = dev->base_addr;
+	unsigned char stat = inb (ioaddr);
+	struct znet_private *znet = dev->priv;
+	unsigned long flags;
+	short dma_port = ((znet->tx_dma&3)<<2) + IO_DMA2_BASE;
+	unsigned addr = inb(dma_port);
+	short residue;
+
+	addr |= inb(dma_port) << 8;
+	residue = get_dma_residue(znet->tx_dma);
+		
+	if (znet_debug > 1) {
+		flags=claim_dma_lock();
+		printk(KERN_DEBUG "Stat:%02x Addr: %04x cnt:%3x\n",
+		       stat, addr<<1, residue);
+		release_dma_lock(flags);
+	}
+}
+
+/* Initialize the hardware.  We have to do this when the board is open()ed
+   or when we come out of suspend mode. */
+static void hardware_init(struct net_device *dev)
+{
+	unsigned long flags;
+	short ioaddr = dev->base_addr;
+	struct znet_private *znet = dev->priv;
+
+	znet->rx_cur = znet->rx_start;
+	znet->tx_cur = znet->tx_start;
+
+	/* Reset the chip, and start it up. */
+	outb(OP0_RESET, ioaddr);
+
+	flags=claim_dma_lock();
+	disable_dma(znet->rx_dma); 		/* reset by an interrupting task. */
+	clear_dma_ff(znet->rx_dma);
+	set_dma_mode(znet->rx_dma, DMA_RX_MODE);
+	set_dma_addr(znet->rx_dma, (unsigned int) znet->rx_start);
+	set_dma_count(znet->rx_dma, RX_BUF_SIZE);
+	enable_dma(znet->rx_dma);
+	/* Now set up the Tx channel. */
+	disable_dma(znet->tx_dma);
+	clear_dma_ff(znet->tx_dma);
+	set_dma_mode(znet->tx_dma, DMA_TX_MODE);
+	set_dma_addr(znet->tx_dma, (unsigned int) znet->tx_start);
+	set_dma_count(znet->tx_dma, znet->tx_buf_len<<1);
+	enable_dma(znet->tx_dma);
+	release_dma_lock(flags);
+	
+	if (znet_debug > 1)
+	  printk(KERN_DEBUG "%s: Initializing the i82593, rx buf %p tx buf %p\n",
+			 dev->name, znet->rx_start,znet->tx_start);
+	/* Do an empty configure command, just like the Crynwr driver.  This
+	   resets to chip to its default values. */
+	*znet->tx_cur++ = 0;
+	*znet->tx_cur++ = 0;
+	show_dma(dev);
+	outb(OP0_CONFIGURE | CR0_CHNL, ioaddr);
+
+	znet_set_multicast_list (dev);
+
+	*znet->tx_cur++ = 6;
+	memcpy(znet->tx_cur, dev->dev_addr, 6);
+	znet->tx_cur += 3;
+	show_dma(dev);
+	outb(OP0_IA_SETUP | CR0_CHNL, ioaddr);
+	show_dma(dev);
+
+	update_stop_hit(ioaddr, 8192);
+	if (znet_debug > 1)  printk(KERN_DEBUG "enabling Rx.\n");
+	outb(OP0_RCV_ENABLE, ioaddr);
+	netif_start_queue (dev);
+}
+
+static void update_stop_hit(short ioaddr, unsigned short rx_stop_offset)
+{
+	outb(OP0_SWIT_TO_PORT_1 | CR0_CHNL, ioaddr);
+	if (znet_debug > 5)
+	  printk(KERN_DEBUG "Updating stop hit with value %02x.\n",
+			 (rx_stop_offset >> 6) | CR1_STOP_REG_UPDATE);
+	outb((rx_stop_offset >> 6) | CR1_STOP_REG_UPDATE, ioaddr);
+	outb(OP1_SWIT_TO_PORT_0, ioaddr);
+}
+
+static __exit void znet_cleanup (void)
+{
+	if (znet_dev) {
+		struct znet_private *znet = znet_dev->priv;
+
+		unregister_netdev (znet_dev);
+		kfree (znet->rx_start);
+		kfree (znet->tx_start);
+		free_netdev (znet_dev);
+	}
+}
+
+module_init (znet_probe);
+module_exit (znet_cleanup);