patch-2.3.36 linux/drivers/net/arcnet/arcnet.c

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diff -u --recursive --new-file v2.3.35/linux/drivers/net/arcnet/arcnet.c linux/drivers/net/arcnet/arcnet.c
@@ -0,0 +1,1052 @@
+/*
+ * Linux ARCnet driver - device-independent routines
+ * 
+ * Written 1997 by David Woodhouse.
+ * Written 1994-1999 by Avery Pennarun.
+ * Written 1999 by Martin Mares <mj@suse.cz>.
+ * Derived from skeleton.c by Donald Becker.
+ *
+ * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)
+ *  for sponsoring the further development of this driver.
+ *
+ * **********************
+ *
+ * The original copyright was as follows:
+ *
+ * skeleton.c Written 1993 by Donald Becker.
+ * Copyright 1993 United States Government as represented by the
+ * Director, National Security Agency.  This software may only be used
+ * and distributed according to the terms of the GNU Public License as
+ * modified by SRC, incorporated herein by reference.
+ *
+ * **********************
+ * 
+ * The change log is now in a file called ChangeLog in this directory.
+ *
+ * Sources:
+ *  - Crynwr arcnet.com/arcether.com packet drivers.
+ *  - arcnet.c v0.00 dated 1/1/94 and apparently by 
+ *     Donald Becker - it didn't work :)
+ *  - skeleton.c v0.05 dated 11/16/93 by Donald Becker
+ *     (from Linux Kernel 1.1.45)
+ *  - RFC's 1201 and 1051 - re: TCP/IP over ARCnet
+ *  - The official ARCnet COM9026 data sheets (!) thanks to
+ *     Ken Cornetet <kcornete@nyx10.cs.du.edu>
+ *  - The official ARCnet COM20020 data sheets.
+ *  - Information on some more obscure ARCnet controller chips, thanks
+ *     to the nice people at SMSC.
+ *  - net/inet/eth.c (from kernel 1.1.50) for header-building info.
+ *  - Alternate Linux ARCnet source by V.Shergin <vsher@sao.stavropol.su>
+ *  - Textual information and more alternate source from Joachim Koenig
+ *     <jojo@repas.de>
+ */
+
+#define VERSION "arcnet: v3.91 BETA 99/12/18 - by Avery Pennarun et al.\n"
+
+#include <linux/module.h>
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/delay.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <net/arp.h>
+#include <linux/init.h>
+#include <linux/arcdevice.h>
+
+
+/* "do nothing" functions for protocol drivers */
+static void null_rx(struct net_device *dev, int bufnum,
+		    struct archdr *pkthdr, int length);
+static int null_build_header(struct sk_buff *skb, unsigned short type,
+			     uint8_t daddr);
+static int null_prepare_tx(struct net_device *dev, struct archdr *pkt,
+			   int length, int bufnum);
+
+
+/*
+ * one ArcProto per possible proto ID.  None of the elements of
+ * arc_proto_map are allowed to be NULL; they will get set to
+ * arc_proto_default instead.  It also must not be NULL; if you would like
+ * to set it to NULL, set it to &arc_proto_null instead.
+ */
+struct ArcProto *arc_proto_map[256], *arc_proto_default, *arc_bcast_proto;
+
+struct ArcProto arc_proto_null =
+{
+	'?',
+	XMTU,
+	null_rx,
+	null_build_header,
+	null_prepare_tx
+};
+
+
+/* Exported function prototypes */
+int arcnet_debug = ARCNET_DEBUG;
+
+EXPORT_SYMBOL(arc_proto_map);
+EXPORT_SYMBOL(arc_proto_default);
+EXPORT_SYMBOL(arc_bcast_proto);
+EXPORT_SYMBOL(arc_proto_null);
+EXPORT_SYMBOL(arcnet_unregister_proto);
+EXPORT_SYMBOL(arcnet_debug);
+EXPORT_SYMBOL(arcdev_setup);
+EXPORT_SYMBOL(arcnet_interrupt);
+
+/* Internal function prototypes */
+static int arcnet_open(struct net_device *dev);
+static int arcnet_close(struct net_device *dev);
+static int arcnet_send_packet(struct sk_buff *skb, struct net_device *dev);
+static int arcnet_header(struct sk_buff *skb, struct net_device *dev,
+			 unsigned short type, void *daddr, void *saddr,
+			 unsigned len);
+static int arcnet_rebuild_header(struct sk_buff *skb);
+static struct net_device_stats *arcnet_get_stats(struct net_device *dev);
+static int go_tx(struct net_device *dev);
+
+void __init arcnet_init(void)
+{
+	static int arcnet_inited __initdata = 0;
+	int count;
+
+	if (arcnet_inited++)
+		return;
+
+	printk(VERSION);
+
+#ifdef ALPHA_WARNING
+	BUGLVL(D_EXTRA) {
+		printk("arcnet: ***\n"
+		"arcnet: * Read arcnet.txt for important release notes!\n"
+		       "arcnet: *\n"
+		       "arcnet: * This is an ALPHA version! (Last stable release: v3.02)  E-mail\n"
+		       "arcnet: * me if you have any questions, comments, or bug reports.\n"
+		       "arcnet: ***\n");
+	}
+#endif
+
+	/* initialize the protocol map */
+	arc_proto_default = arc_bcast_proto = &arc_proto_null;
+	for (count = 0; count < 256; count++)
+		arc_proto_map[count] = arc_proto_default;
+
+	BUGLVL(D_DURING)
+	    printk("arcnet: struct sizes: %d %d %d %d %d\n",
+		 sizeof(struct arc_hardware), sizeof(struct arc_rfc1201),
+		sizeof(struct arc_rfc1051), sizeof(struct arc_eth_encap),
+		   sizeof(struct archdr));
+
+#ifdef CONFIG_ARCNET		/* We're not built as a module */
+	printk("arcnet: Available protocols:");
+#ifdef CONFIG_ARCNET_1201
+	printk(" RFC1201");
+	arcnet_rfc1201_init();
+#endif
+#ifdef CONFIG_ARCNET_1051
+	printk(" RFC1051");
+	arcnet_rfc1051_init();
+#endif
+#ifdef CONFIG_ARCNET_RAW
+	printk(" RAW");
+	arcnet_raw_init();
+#endif
+	printk("\n");
+#ifdef CONFIG_ARCNET_COM90xx
+	com90xx_probe(NULL);
+#endif
+#ifdef CONFIG_ARCNET_COM20020_PCI
+	com20020pci_probe_all();
+#endif
+#endif
+}
+
+
+#ifdef MODULE
+
+static int debug = ARCNET_DEBUG;
+MODULE_PARM(debug, "i");
+
+int __init init_module(void)
+{
+	arcnet_debug = debug;
+	arcnet_init();
+	return 0;
+}
+
+void cleanup_module(void)
+{
+}
+
+#endif
+
+
+/*
+ * Dump the contents of an sk_buff
+ */
+#if ARCNET_DEBUG_MAX & D_SKB
+void arcnet_dump_skb(struct net_device *dev, struct sk_buff *skb, char *desc)
+{
+	int i;
+	long flags;
+
+	save_flags(flags);
+	cli();
+	printk(KERN_DEBUG "%6s: skb dump (%s) follows:", dev->name, desc);
+	for (i = 0; i < skb->len; i++) {
+		if (i % 16 == 0)
+			printk("\n" KERN_DEBUG "[%04X] ", i);
+		printk("%02X ", ((u_char *) skb->data)[i]);
+	}
+	printk("\n");
+	restore_flags(flags);
+}
+
+EXPORT_SYMBOL(arcnet_dump_skb);
+#endif
+
+
+/*
+ * Dump the contents of an ARCnet buffer
+ */
+#if (ARCNET_DEBUG_MAX & (D_RX | D_TX))
+void arcnet_dump_packet(struct net_device *dev, int bufnum, char *desc)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	int i, length;
+	long flags;
+	static uint8_t buf[512];
+
+	save_flags(flags);
+	cli();
+
+	lp->hw.copy_from_card(dev, bufnum, 0, buf, 512);
+
+	/* if the offset[0] byte is nonzero, this is a 256-byte packet */
+	length = (buf[2] ? 256 : 512);
+
+	printk(KERN_DEBUG "%6s: packet dump (%s) follows:", dev->name, desc);
+	for (i = 0; i < length; i++) {
+		if (i % 16 == 0)
+			printk("\n" KERN_DEBUG "[%04X] ", i);
+		printk("%02X ", buf[i]);
+	}
+	printk("\n");
+
+	restore_flags(flags);
+}
+
+EXPORT_SYMBOL(arcnet_dump_packet);
+#endif
+
+
+/*
+ * Unregister a protocol driver from the arc_proto_map.  Protocol drivers
+ * are responsible for registering themselves, but the unregister routine
+ * is pretty generic so we'll do it here.
+ */
+void arcnet_unregister_proto(struct ArcProto *proto)
+{
+	int count;
+
+	if (arc_proto_default == proto)
+		arc_proto_default = &arc_proto_null;
+	if (arc_bcast_proto == proto)
+		arc_bcast_proto = arc_proto_default;
+
+	for (count = 0; count < 256; count++) {
+		if (arc_proto_map[count] == proto)
+			arc_proto_map[count] = arc_proto_default;
+	}
+}
+
+
+/*
+ * Add a buffer to the queue.  Only the interrupt handler is allowed to do
+ * this, unless interrupts are disabled.
+ * 
+ * Note: we don't check for a full queue, since there aren't enough buffers
+ * to more than fill it.
+ */
+static void release_arcbuf(struct net_device *dev, int bufnum)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	int i;
+
+	lp->buf_queue[lp->first_free_buf++] = bufnum;
+	lp->first_free_buf %= 5;
+
+	BUGLVL(D_DURING) {
+		BUGMSG(D_DURING, "release_arcbuf: freed #%d; buffer queue is now: ",
+		       bufnum);
+		for (i = lp->next_buf; i != lp->first_free_buf; i = ++i % 5)
+			BUGMSG2(D_DURING, "#%d ", lp->buf_queue[i]);
+		BUGMSG2(D_DURING, "\n");
+	}
+}
+
+
+/*
+ * Get a buffer from the queue.  If this returns -1, there are no buffers
+ * available.
+ */
+static int get_arcbuf(struct net_device *dev)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	int buf = -1, i;
+
+	if (!atomic_dec_and_test(&lp->buf_lock))	/* already in this function */
+		BUGMSG(D_NORMAL, "get_arcbuf: overlap (%d)!\n", lp->buf_lock.counter);
+	else {			/* we can continue */
+		if (lp->next_buf >= 5)
+			lp->next_buf -= 5;
+
+		if (lp->next_buf == lp->first_free_buf)
+			BUGMSG(D_NORMAL, "get_arcbuf: BUG: no buffers are available??\n");
+		else {
+			buf = lp->buf_queue[lp->next_buf++];
+			lp->next_buf %= 5;
+		}
+	}
+
+
+	BUGLVL(D_DURING) {
+		BUGMSG(D_DURING, "get_arcbuf: got #%d; buffer queue is now: ", buf);
+		for (i = lp->next_buf; i != lp->first_free_buf; i = ++i % 5)
+			BUGMSG2(D_DURING, "#%d ", lp->buf_queue[i]);
+		BUGMSG2(D_DURING, "\n");
+	}
+
+	atomic_inc(&lp->buf_lock);
+	return buf;
+}
+
+
+static int choose_mtu(void)
+{
+	int count, mtu = 65535;
+
+	/* choose the smallest MTU of all available encaps */
+	for (count = 0; count < 256; count++) {
+		if (arc_proto_map[count] != &arc_proto_null
+		    && arc_proto_map[count]->mtu < mtu) {
+			mtu = arc_proto_map[count]->mtu;
+		}
+	}
+
+	return mtu == 65535 ? XMTU : mtu;
+}
+
+
+/* Setup a struct device for ARCnet. */
+void arcdev_setup(struct net_device *dev)
+{
+	dev->type = ARPHRD_ARCNET;
+	dev->hard_header_len = sizeof(struct archdr);
+	dev->mtu = choose_mtu();
+
+	dev->addr_len = 1;
+	dev->tx_queue_len = 30;
+	dev->broadcast[0] = 0x00;	/* for us, broadcasts are address 0 */
+
+	/* New-style flags. */
+	dev->flags = IFF_BROADCAST;
+
+	/*
+	 * Put in this stuff here, so we don't have to export the symbols to
+	 * the chipset drivers.
+	 */
+	dev->open = arcnet_open;
+	dev->stop = arcnet_close;
+	dev->hard_start_xmit = arcnet_send_packet;
+	dev->get_stats = arcnet_get_stats;
+	dev->hard_header = arcnet_header;
+	dev->rebuild_header = arcnet_rebuild_header;
+
+	dev_init_buffers(dev);
+}
+
+
+/*
+ * Open/initialize the board.  This is called sometime after booting when
+ * the 'ifconfig' program is run.
+ *
+ * This routine should set everything up anew at each open, even registers
+ * that "should" only need to be set once at boot, so that there is
+ * non-reboot way to recover if something goes wrong.
+ */
+static int arcnet_open(struct net_device *dev)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	int count, newmtu;
+
+	BUGLVL(D_PROTO) {
+		int count;
+		BUGMSG(D_PROTO, "protocol map (default is '%c'): ",
+		       arc_proto_default->suffix);
+		for (count = 0; count < 256; count++)
+			BUGMSG2(D_PROTO, "%c", arc_proto_map[count]->suffix);
+		BUGMSG2(D_PROTO, "\n");
+	}
+
+
+	BUGMSG(D_INIT, "arcnet_open: resetting card.\n");
+
+	/* try to put the card in a defined state - if it fails the first
+	 * time, actually reset it.
+	 */
+	if (ARCRESET(0) && ARCRESET(1))
+		return -ENODEV;
+
+	dev->tbusy = 0;
+	dev->interrupt = 0;
+	dev->start = 0;
+
+	newmtu = choose_mtu();
+	if (newmtu < dev->mtu)
+		dev->mtu = newmtu;
+
+	/* autodetect the encapsulation for each host. */
+	memset(lp->default_proto, 0, sizeof(lp->default_proto));
+
+	/* the broadcast address is special - use the 'bcast' protocol */
+	for (count = 0; count < 256; count++) {
+		if (arc_proto_map[count] == arc_bcast_proto) {
+			lp->default_proto[0] = count;
+			break;
+		}
+	}
+
+	/* initialize buffers */
+	atomic_set(&lp->buf_lock, 1);
+	lp->next_buf = lp->first_free_buf = 0;
+	release_arcbuf(dev, 0);
+	release_arcbuf(dev, 1);
+	release_arcbuf(dev, 2);
+	release_arcbuf(dev, 3);
+	lp->cur_tx = lp->next_tx = -1;
+	lp->cur_rx = -1;
+
+	lp->rfc1201.sequence = 1;
+
+	/* bring up the hardware driver */
+	ARCOPEN(1);
+
+	if (dev->dev_addr[0] == 0)
+		BUGMSG(D_NORMAL, "WARNING!  Station address 00 is reserved "
+		       "for broadcasts!\n");
+	else if (dev->dev_addr[0] == 255)
+		BUGMSG(D_NORMAL, "WARNING!  Station address FF may confuse "
+		       "DOS networking programs!\n");
+
+	if (ASTATUS() & RESETflag)
+		ACOMMAND(CFLAGScmd | RESETclear);
+
+	/* we're started */
+	dev->start = 1;
+
+	/* make sure we're ready to receive IRQ's. */
+	AINTMASK(0);
+	udelay(1);		/* give it time to set the mask before
+				 * we reset it again. (may not even be
+				 * necessary)
+				 */
+	lp->intmask = NORXflag | RECONflag;
+	AINTMASK(lp->intmask);
+
+	return 0;
+}
+
+
+/* The inverse routine to arcnet_open - shuts down the card. */
+static int arcnet_close(struct net_device *dev)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+
+	/* flush TX and disable RX */
+	AINTMASK(0);
+	ACOMMAND(NOTXcmd);	/* stop transmit */
+	ACOMMAND(NORXcmd);	/* disable receive */
+	mdelay(1);
+
+	dev->tbusy = 1;
+	dev->start = 0;
+	dev->interrupt = 0;
+
+	/* shut down the card */
+	ARCOPEN(0);
+
+	return 0;
+}
+
+
+static int arcnet_header(struct sk_buff *skb, struct net_device *dev,
+			 unsigned short type, void *daddr, void *saddr,
+			 unsigned len)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	uint8_t _daddr, proto_num;
+	struct ArcProto *proto;
+
+	BUGMSG(D_DURING,
+	    "create header from %d to %d; protocol %d (%Xh); size %u.\n",
+	       saddr ? *(uint8_t *) saddr : -1,
+	       daddr ? *(uint8_t *) daddr : -1,
+	       type, type, len);
+
+	if (len != skb->len)
+		BUGMSG(D_NORMAL, "arcnet_header: Yikes!  skb->len(%d) != len(%d)!\n",
+		       skb->len, len);
+
+	/*
+	 * if the dest addr isn't provided, we can't choose an encapsulation!
+	 * Store the packet type (eg. ETH_P_IP) for now, and we'll push on a
+	 * real header when we do rebuild_header. 
+	 */
+	if (!daddr) {
+		*(uint16_t *) skb_push(skb, 2) = type;
+		if (skb->nh.raw - skb->mac.raw != 2)
+			BUGMSG(D_NORMAL, "arcnet_header: Yikes!  diff (%d) is not 2!\n",
+			       skb->nh.raw - skb->mac.raw);
+		return -2;	/* return error -- can't transmit yet! */
+	}
+	/* otherwise, we can just add the header as usual. */
+	_daddr = *(uint8_t *) daddr;
+	proto_num = lp->default_proto[_daddr];
+	proto = arc_proto_map[proto_num];
+	BUGMSG(D_DURING, "building header for %02Xh using protocol '%c'\n",
+	       proto_num, proto->suffix);
+	if (proto == &arc_proto_null && arc_bcast_proto != proto) {
+		BUGMSG(D_DURING, "actually, let's use '%c' instead.\n",
+		       arc_bcast_proto->suffix);
+		proto = arc_bcast_proto;
+	}
+	return proto->build_header(skb, type, _daddr);
+}
+
+
+/* 
+ * Rebuild the ARCnet hard header. This is called after an ARP (or in the
+ * future other address resolution) has completed on this sk_buff. We now
+ * let ARP fill in the destination field.
+ */
+static int arcnet_rebuild_header(struct sk_buff *skb)
+{
+	struct net_device *dev = skb->dev;
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	int status = 0;		/* default is failure */
+	unsigned short type;
+	uint8_t daddr;
+
+	if (skb->nh.raw - skb->mac.raw != 2) {
+		BUGMSG(D_NORMAL,
+		     "rebuild_header: shouldn't be here! (hdrsize=%d)\n",
+		       skb->nh.raw - skb->mac.raw);
+		return 0;
+	}
+	type = *(uint16_t *) skb_pull(skb, 2);
+
+	if (type == ETH_P_IP) {
+#ifdef CONFIG_INET
+		BUGMSG(D_DURING, "rebuild header for ethernet protocol %Xh\n", type);
+		status = arp_find(&daddr, skb) ? 1 : 0;
+		BUGMSG(D_DURING, " rebuilt: dest is %d; protocol %Xh\n",
+		       daddr, type);
+#endif
+	} else {
+		BUGMSG(D_NORMAL,
+		       "I don't understand ethernet protocol %Xh addresses!\n", type);
+		lp->stats.tx_errors++;
+		lp->stats.tx_aborted_errors++;
+	}
+
+	/* if we couldn't resolve the address... give up. */
+	if (!status)
+		return 0;
+
+	/* add the _real_ header this time! */
+	arc_proto_map[lp->default_proto[daddr]]->build_header(skb, type, daddr);
+
+	return 1;		/* success */
+}
+
+
+
+/* Called by the kernel in order to transmit a packet. */
+static int arcnet_send_packet(struct sk_buff *skb, struct net_device *dev)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	struct archdr *pkt;
+	struct arc_rfc1201 *soft;
+	struct ArcProto *proto;
+	int txbuf;
+
+	BUGMSG(D_DURING,
+	       "transmit requested (status=%Xh, txbufs=%d/%d, len=%d)\n",
+	       ASTATUS(), lp->cur_tx, lp->next_tx, skb->len);
+
+	if (dev->tbusy) {
+		/*
+		 * If we get here, some higher level has decided we are broken.
+		 * There should really be a "kick me" function call instead. 
+		 */
+		unsigned long flags;
+		int tickssofar = jiffies - dev->trans_start, status = ASTATUS();
+
+		if (tickssofar < TX_TIMEOUT) {
+			BUGMSG(D_DURING, "premature kickme! (status=%Xh ticks=%d)\n",
+			       status, tickssofar);
+			return 1;	/* means "try again" */
+		}
+		save_flags(flags);
+		cli();
+
+		if (status & TXFREEflag) {	/* transmit _DID_ finish */
+			BUGMSG(D_NORMAL, "tx timeout - missed IRQ? (status=%Xh, ticks=%d, mask=%Xh, dest=%02Xh)\n",
+			       status, tickssofar, lp->intmask, lp->lasttrans_dest);
+			lp->stats.tx_errors++;
+		} else {
+			BUGMSG(D_EXTRA, "tx timed out (status=%Xh, tickssofar=%d, intmask=%Xh, dest=%02Xh)\n",
+			       status, tickssofar, lp->intmask, lp->lasttrans_dest);
+			lp->stats.tx_errors++;
+			lp->stats.tx_aborted_errors++;
+
+			ACOMMAND(NOTXcmd | (lp->cur_tx << 3));
+		}
+
+		/*
+		 * interrupt handler will set dev->tbusy = 0 when it notices the
+		 * transmit has been canceled.
+		 */
+
+		/* make sure we didn't miss a TX IRQ */
+		AINTMASK(0);
+		lp->intmask |= TXFREEflag;
+		AINTMASK(lp->intmask);
+
+		restore_flags(flags);
+		return 1;
+	}
+	pkt = (struct archdr *) skb->data;
+	soft = &pkt->soft.rfc1201;
+	proto = arc_proto_map[soft->proto];
+
+	BUGLVL(D_SKB) arcnet_dump_skb(dev, skb, "tx");
+
+	/* fits in one packet? */
+	if (skb->len - ARC_HDR_SIZE > XMTU && !proto->continue_tx) {
+		BUGMSG(D_NORMAL, "fixme: packet too large: compensating badly!\n");
+		dev_kfree_skb(skb);
+		return 0;	/* don't try again */
+	}
+	/*
+	 * 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 (test_and_set_bit(0, (int *) &dev->tbusy)) {
+		BUGMSG(D_NORMAL, "transmitter called with busy bit set! "
+		       "(status=%Xh, tickssofar=%ld)\n",
+		       ASTATUS(), jiffies - dev->trans_start);
+		lp->stats.tx_errors++;
+		lp->stats.tx_fifo_errors++;
+		return 0;	/* don't try again */
+	}
+	AINTMASK(0);
+
+	txbuf = get_arcbuf(dev);
+	if (txbuf != -1) {
+		if (proto->prepare_tx(dev, pkt, skb->len, txbuf)) {
+			/* done right away */
+			lp->stats.tx_bytes += skb->len;
+			dev_kfree_skb(skb);
+		} else {
+			/* do it the 'split' way */
+			lp->outgoing.proto = proto;
+			lp->outgoing.skb = skb;
+			lp->outgoing.pkt = pkt;
+
+			if (!proto->continue_tx)
+				BUGMSG(D_NORMAL, "bug! prep_tx==0, but no continue_tx!\n");
+			else if (proto->continue_tx(dev, txbuf)) {
+				BUGMSG(D_NORMAL,
+				       "bug! continue_tx finished the first time! "
+				       "(proto='%c')\n", proto->suffix);
+			}
+		}
+
+		lp->next_tx = txbuf;
+	} else
+		dev_kfree_skb(skb);
+
+	/* make sure we didn't ignore a TX IRQ while we were in here */
+	AINTMASK(0);
+	lp->intmask |= TXFREEflag;
+	AINTMASK(lp->intmask);
+
+	return 0;		/* no need to try again */
+}
+
+
+/*
+ * Actually start transmitting a packet that was loaded into a buffer
+ * by prepare_tx.  This should _only_ be called by the interrupt handler.
+ */
+static int go_tx(struct net_device *dev)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+
+	BUGMSG(D_DURING, "go_tx: status=%Xh, intmask=%Xh, next_tx=%d, cur_tx=%d\n",
+	       ASTATUS(), lp->intmask, lp->next_tx, lp->cur_tx);
+
+	if (lp->cur_tx != -1 || lp->next_tx == -1)
+		return 0;
+
+	BUGLVL(D_TX) arcnet_dump_packet(dev, lp->next_tx, "go_tx");
+
+	lp->cur_tx = lp->next_tx;
+	lp->next_tx = -1;
+
+	/* start sending */
+	ACOMMAND(TXcmd | (lp->cur_tx << 3));
+
+	dev->trans_start = jiffies;
+	lp->stats.tx_packets++;
+	lp->lasttrans_dest = lp->lastload_dest;
+	lp->lastload_dest = 0;
+	lp->intmask |= TXFREEflag;
+
+	return 1;
+}
+
+
+/*
+ * The typical workload of the driver: Handle the network interface
+ * interrupts. Establish which device needs attention, and call the correct
+ * chipset interrupt handler.
+ */
+void arcnet_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct net_device *dev = dev_id;
+	struct arcnet_local *lp;
+	int recbuf, status, didsomething, boguscount;
+
+	BUGMSG(D_DURING, "\n");
+
+	if (dev == NULL) {
+		BUGMSG(D_DURING, "arcnet: irq %d for unknown device.\n", irq);
+		return;
+	}
+	BUGMSG(D_DURING, "in arcnet_interrupt\n");
+
+	lp = (struct arcnet_local *) dev->priv;
+	if (!lp) {
+		BUGMSG(D_DURING, "arcnet: irq ignored due to missing lp.\n");
+		return;
+	}
+	/*
+	 * RESET flag was enabled - if !dev->start, we must clear it right
+	 * away (but nothing else).
+	 */
+	if (!dev->start) {
+		if (ASTATUS() & RESETflag)
+			ACOMMAND(CFLAGScmd | RESETclear);
+		AINTMASK(0);
+		return;
+	}
+	if (dev->interrupt) {
+		BUGMSG(D_NORMAL, "DRIVER PROBLEM!  Nested arcnet interrupts!\n");
+		return;		/* don't even try. */
+	}
+	dev->interrupt = 1;
+
+	BUGMSG(D_DURING, "in arcnet_inthandler (status=%Xh, intmask=%Xh)\n",
+	       ASTATUS(), lp->intmask);
+
+	boguscount = 3;
+	do {
+		status = ASTATUS();
+		didsomething = 0;
+
+		/*
+		 * RESET flag was enabled - card is resetting and if RX is
+		 * disabled, it's NOT because we just got a packet.
+		 * 
+		 * The card is in an undefined state.  Clear it out and start over.
+		 */
+		if (status & RESETflag) {
+			BUGMSG(D_NORMAL, "spurious reset (status=%Xh)\n", status);
+			arcnet_close(dev);
+			arcnet_open(dev);
+
+			/* get out of the interrupt handler! */
+			break;
+		}
+		/* 
+		 * RX is inhibited - we must have received something. Prepare to
+		 * receive into the next buffer.
+		 * 
+		 * We don't actually copy the received packet from the card until
+		 * after the transmit handler runs (and possibly launches the next
+		 * tx); this should improve latency slightly if we get both types
+		 * of interrupts at once. 
+		 */
+		recbuf = -1;
+		if (status & lp->intmask & NORXflag) {
+			recbuf = lp->cur_rx;
+			BUGMSG(D_DURING, "Buffer #%d: receive irq (status=%Xh)\n",
+			       recbuf, status);
+
+			lp->cur_rx = get_arcbuf(dev);
+			if (lp->cur_rx != -1) {
+				BUGMSG(D_DURING, "enabling receive to buffer #%d\n",
+				       lp->cur_rx);
+				ACOMMAND(RXcmd | (lp->cur_rx << 3) | RXbcasts);
+			}
+			didsomething++;
+		}
+		/* a transmit finished, and we're interested in it. */
+		if (status & lp->intmask & TXFREEflag) {
+			lp->intmask &= ~TXFREEflag;
+
+			BUGMSG(D_DURING, "TX IRQ (stat=%Xh)\n", status);
+
+			if (lp->cur_tx != -1 && !(status & TXACKflag)) {
+				if (lp->lasttrans_dest != 0) {
+					BUGMSG(D_EXTRA, "transmit was not acknowledged! "
+					    "(status=%Xh, dest=%02Xh)\n",
+					     status, lp->lasttrans_dest);
+					lp->stats.tx_errors++;
+					lp->stats.tx_carrier_errors++;
+				} else {
+					BUGMSG(D_DURING,
+					       "broadcast was not acknowledged; that's normal "
+					    "(status=%Xh, dest=%02Xh)\n",
+					     status, lp->lasttrans_dest);
+				}
+			}
+			if (lp->cur_tx != -1)
+				release_arcbuf(dev, lp->cur_tx);
+
+			lp->cur_tx = -1;
+			didsomething++;
+
+			/* send another packet if there is one */
+			go_tx(dev);
+
+			/* continue a split packet, if any */
+			if (lp->outgoing.proto && lp->outgoing.proto->continue_tx) {
+				int txbuf = get_arcbuf(dev);
+				if (txbuf != -1) {
+					if (lp->outgoing.proto->continue_tx(dev, txbuf)) {
+						/* that was the last segment */
+						lp->stats.tx_bytes += lp->outgoing.skb->len;
+						dev_kfree_skb(lp->outgoing.skb);
+						lp->outgoing.proto = NULL;
+					}
+					lp->next_tx = txbuf;
+				}
+			}
+			/* inform upper layers of idleness, if necessary */
+			if (lp->cur_tx == -1) {
+				dev->tbusy = 0;
+				mark_bh(NET_BH);
+			}
+		}
+		/* now process the received packet, if any */
+		if (recbuf != -1) {
+			BUGLVL(D_RX) arcnet_dump_packet(dev, recbuf, "rx irq");
+
+			arcnet_rx(dev, recbuf);
+			release_arcbuf(dev, recbuf);
+
+			didsomething++;
+		}
+		if (status & lp->intmask & RECONflag) {
+			ACOMMAND(CFLAGScmd | CONFIGclear);
+			lp->stats.tx_carrier_errors++;
+
+			BUGMSG(D_RECON, "Network reconfiguration detected (status=%Xh)\n",
+			       status);
+
+			/* is the RECON info empty or old? */
+			if (!lp->first_recon || !lp->last_recon ||
+			    jiffies - lp->last_recon > HZ * 10) {
+				if (lp->network_down)
+					BUGMSG(D_NORMAL, "reconfiguration detected: cabling restored?\n");
+				lp->first_recon = lp->last_recon = jiffies;
+				lp->num_recons = lp->network_down = 0;
+
+				BUGMSG(D_DURING, "recon: clearing counters.\n");
+			} else {	/* add to current RECON counter */
+				lp->last_recon = jiffies;
+				lp->num_recons++;
+
+				BUGMSG(D_DURING, "recon: counter=%d, time=%lds, net=%d\n",
+				       lp->num_recons,
+				 (lp->last_recon - lp->first_recon) / HZ,
+				       lp->network_down);
+
+				/* if network is marked up;
+				 * and first_recon and last_recon are 60+ apart;
+				 * and the average no. of recons counted is
+				 *    > RECON_THRESHOLD/min;
+				 * then print a warning message.
+				 */
+				if (!lp->network_down
+				    && (lp->last_recon - lp->first_recon) <= HZ * 60
+				  && lp->num_recons >= RECON_THRESHOLD) {
+					lp->network_down = 1;
+					BUGMSG(D_NORMAL, "many reconfigurations detected: cabling problem?\n");
+				} else if (!lp->network_down
+					   && lp->last_recon - lp->first_recon > HZ * 60) {
+					/* reset counters if we've gone for over a minute. */
+					lp->first_recon = lp->last_recon;
+					lp->num_recons = 1;
+				}
+			}
+		} else if (lp->network_down && jiffies - lp->last_recon > HZ * 10) {
+			if (lp->network_down)
+				BUGMSG(D_NORMAL, "cabling restored?\n");
+			lp->first_recon = lp->last_recon = 0;
+			lp->num_recons = lp->network_down = 0;
+
+			BUGMSG(D_DURING, "not recon: clearing counters anyway.\n");
+		}
+	}
+	while (--boguscount && didsomething);
+
+	BUGMSG(D_DURING, "arcnet_interrupt complete (status=%Xh, count=%d)\n",
+	       ASTATUS(), boguscount);
+	BUGMSG(D_DURING, "\n");
+
+
+	AINTMASK(0);
+	udelay(1);
+	AINTMASK(lp->intmask);
+
+	dev->interrupt = 0;
+}
+
+
+/*
+ * This is a generic packet receiver that calls arcnet??_rx depending on the
+ * protocol ID found.
+ */
+void arcnet_rx(struct net_device *dev, int bufnum)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	struct archdr pkt;
+	struct arc_rfc1201 *soft;
+	int length, ofs;
+
+	soft = &pkt.soft.rfc1201;
+
+	lp->hw.copy_from_card(dev, bufnum, 0, &pkt, sizeof(ARC_HDR_SIZE));
+	if (pkt.hard.offset[0]) {
+		ofs = pkt.hard.offset[0];
+		length = 256 - ofs;
+	} else {
+		ofs = pkt.hard.offset[1];
+		length = 512 - ofs;
+	}
+
+	/* get the full header, if possible */
+	if (sizeof(pkt.soft) < length)
+		lp->hw.copy_from_card(dev, bufnum, ofs, soft, sizeof(pkt.soft));
+	else {
+		memset(&pkt.soft, 0, sizeof(pkt.soft));
+		lp->hw.copy_from_card(dev, bufnum, ofs, soft, length);
+	}
+
+	BUGMSG(D_DURING, "Buffer #%d: received packet from %02Xh to %02Xh "
+	       "(%d+4 bytes)\n",
+	       bufnum, pkt.hard.source, pkt.hard.dest, length);
+
+	lp->stats.rx_packets++;
+	lp->stats.rx_bytes += length + ARC_HDR_SIZE;
+
+	/* call the right receiver for the protocol */
+	if (arc_proto_map[soft->proto] != &arc_proto_null) {
+		BUGLVL(D_PROTO) {
+			struct ArcProto
+			*oldp = arc_proto_map[lp->default_proto[pkt.hard.source]],
+			*newp = arc_proto_map[soft->proto];
+
+			if (oldp != newp) {
+				BUGMSG(D_PROTO,
+				       "got protocol %02Xh; encap for host %02Xh is now '%c'"
+				       " (was '%c')\n", soft->proto, pkt.hard.source,
+				       newp->suffix, oldp->suffix);
+			}
+		}
+
+		/* broadcasts will always be done with the last-used encap. */
+		lp->default_proto[0] = soft->proto;
+
+		/* in striking contrast, the following isn't a hack. */
+		lp->default_proto[pkt.hard.source] = soft->proto;
+	}
+	/* call the protocol-specific receiver. */
+	arc_proto_map[soft->proto]->rx(dev, bufnum, &pkt, length);
+
+	/*
+	 * If any worthwhile packets have been received, a mark_bh(NET_BH) has
+	 * been done by netif_rx and Linux will handle them after we return.
+	 */
+}
+
+
+
+/* 
+ * Get the current statistics.  This may be called with the card open or
+ * closed.
+ */
+static struct net_device_stats *arcnet_get_stats(struct net_device *dev)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	return &lp->stats;
+}
+
+
+static void null_rx(struct net_device *dev, int bufnum,
+		    struct archdr *pkthdr, int length)
+{
+	BUGMSG(D_PROTO,
+	"rx: don't know how to deal with proto %02Xh from host %02Xh.\n",
+	       pkthdr->soft.rfc1201.proto, pkthdr->hard.source);
+}
+
+
+static int null_build_header(struct sk_buff *skb, unsigned short type,
+			     uint8_t daddr)
+{
+	struct net_device *dev = skb->dev;
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+
+	BUGMSG(D_PROTO,
+	       "tx: can't build header for encap %02Xh; load a protocol driver.\n",
+	       lp->default_proto[daddr]);
+
+	/* always fails */
+	return 0;
+}
+
+
+/* the "do nothing" prepare_tx function warns that there's nothing to do. */
+static int null_prepare_tx(struct net_device *dev, struct archdr *pkt,
+			   int length, int bufnum)
+{
+	struct arcnet_local *lp = (struct arcnet_local *) dev->priv;
+	struct arc_hardware newpkt;
+
+	BUGMSG(D_PROTO, "tx: no encap for this host; load a protocol driver.\n");
+
+	/* send a packet to myself -- will never get received, of course */
+	newpkt.source = newpkt.dest = dev->dev_addr[0];
+
+	/* only one byte of actual data (and it's random) */
+	newpkt.offset[0] = 0xFF;
+
+	lp->hw.copy_to_card(dev, bufnum, 0, &newpkt, ARC_HDR_SIZE);
+
+	return 1;		/* done */
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)