patch-2.2.19 linux/drivers/net/3c527.c

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diff -u --new-file --recursive --exclude-from /usr/src/exclude v2.2.18/drivers/net/3c527.c linux/drivers/net/3c527.c
@@ -1,9 +1,8 @@
-
-/* 3c527.c: 3Com Etherlink/MC32 driver for Linux
+/* 3c527.c: 3Com Etherlink/MC32 driver for Linux 2.2
  *
  *	(c) Copyright 1998 Red Hat Software Inc
- *	Written by Alan Cox.
- *	Further debugging by Carl Drougge.
+ *	Written by Alan Cox. 
+ *      Modified by Richard Procter (rnp@netlink.co.nz)
  *
  *	Based on skeleton.c written 1993-94 by Donald Becker and ne2.c
  *	(for the MCA stuff) written by Wim Dumon.
@@ -12,26 +11,70 @@
  *	documentation.
  *
  *	This software may be used and distributed according to the terms
- *	of the GNU Public License, incorporated herein by reference.
+ *	of the GNU General Public License, incorporated herein by reference.
  *
  */
 
 static const char *version =
-	"3c527.c:v0.08 2000/02/22 Alan Cox (alan@redhat.com)\n";
+	"3c527.c:v0.5 1999/09/16 Alan Cox (alan@redhat.com)\n";
 
-/*
- *	Things you need
- *	o	The databook.
- *
- *	Traps for the unwary
+/**
+ * DOC: Traps for the unwary
  *
  *	The diagram (Figure 1-1) and the POS summary disagree with the
  *	"Interrupt Level" section in the manual.
  *
+ *	The manual contradicts itself when describing the minimum number 
+ *	buffers in the 'configure lists' command. 
+ *	My card accepts a buffer config of 4/4. 
+ *
+ *	Setting the SAV BP bit does not save bad packets, but
+ *	only enables RX on-card stats collection. 
+ *
  *	The documentation in places seems to miss things. In actual fact
  *	I've always eventually found everything is documented, it just
  *	requires careful study.
- */
+ *
+ * DOC: Theory Of Operation
+ *
+ *	The 3com 3c527 is a 32bit MCA bus mastering adapter with a large
+ *	amount of on board intelligence that housekeeps a somewhat dumber
+ *	Intel NIC. For performance we want to keep the transmit queue deep
+ *	as the card can transmit packets while fetching others from main
+ *	memory by bus master DMA. Transmission and reception are driven by
+ *	circular buffer queues.
+ *
+ *	The mailboxes can be used for controlling how the card traverses
+ *	its buffer rings, but are used only for inital setup in this
+ *	implementation.  The exec mailbox allows a variety of commands to
+ *	be executed. Each command must complete before the next is
+ *	executed. Primarily we use the exec mailbox for controlling the
+ *	multicast lists.  We have to do a certain amount of interesting
+ *	hoop jumping as the multicast list changes can occur in interrupt
+ *	state when the card has an exec command pending. We defer such
+ *	events until the command completion interrupt.
+ *
+ *	A copy break scheme (taken from 3c59x.c) is employed whereby
+ *	received frames exceeding a configurable length are passed
+ *	directly to the higher networking layers without incuring a copy,
+ *	in what amounts to a time/space trade-off.
+ *	 
+ *	The card also keeps a large amount of statistical information
+ *	on-board. In a perfect world, these could be used safely at no
+ *	cost. However, lacking information to the contrary, processing
+ *	them without races would involve so much extra complexity as to
+ *	make it unworthwhile to do so. In the end, a hybrid SW/HW
+ *	implementation was made necessary --- see mc32_update_stats().  
+ *
+ * DOC: Notes
+ *	
+ *	It should be possible to use two or more cards, but at this stage
+ *	only by loading two copies of the same module.
+ *
+ *	The on-board 82586 NIC has trouble receiving multiple
+ *	back-to-back frames and so is likely to drop packets from fast
+ *	senders.
+**/
 
 #include <linux/module.h>
 
@@ -56,6 +99,7 @@
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/skbuff.h>
+#include <linux/if_ether.h>
 
 #include "3c527.h"
 
@@ -69,23 +113,36 @@
 #ifndef NET_DEBUG
 #define NET_DEBUG 2
 #endif
+
+#undef DEBUG_IRQ
+
 static unsigned int mc32_debug = NET_DEBUG;
 
 /* The number of low I/O ports used by the ethercard. */
-#define NETCARD_IO_EXTENT	8
+#define MC32_IO_EXTENT	8
 
+/* As implemented, values must be a power-of-2 -- 4/8/16/32 */ 
+#define TX_RING_LEN     32       /* Typically the card supports 37  */
+#define RX_RING_LEN     8        /*     "       "        "          */
+
+/* Copy break point, see above for details. 
+ * Setting to > 1512 effectively disables this feature.	*/	    
+#define RX_COPYBREAK    200      /* Value from 3c59x.c */
+
+/* Issue the 82586 workaround command - this is for "busy lans", but
+ * basically means for all lans now days - has a performance (latency) 
+ * cost, but best set. */ 
+static const int WORKAROUND_82586=1;
 
-struct mc32_mailbox
+/* Pointers to buffers and their on-card records */
+struct mc32_ring_desc 
 {
-	u16	mbox __attribute((packed));
-	u16	data[1] __attribute((packed));
+  volatile struct skb_header *p;                    
+  struct sk_buff *skb;          
 };
 
-/* Information that need to be kept for each board. */
-
-#define TX_RING_MAX	16	/* Typically the card supports 37 */
-#define RX_RING_MAX	32	/*        "     "       "         */
 
+/* Information that needs to be kept for each board. */
 struct mc32_local 
 {
 	struct net_device_stats net_stats;
@@ -93,25 +150,28 @@
 	volatile struct mc32_mailbox *rx_box;
 	volatile struct mc32_mailbox *tx_box;
 	volatile struct mc32_mailbox *exec_box;
-	volatile u16 *stats;
-	u16 tx_chain;
-	u16 rx_chain;
-	u16 tx_len;
-	u16 rx_len;
+        volatile struct mc32_stats *stats;    /* Start of on-card statistics */
+        u16 tx_chain;           /* Transmit list start offset */
+	u16 rx_chain;           /* Receive list start offset */
+        u16 tx_len;             /* Transmit list count */ 
+        u16 rx_len;             /* Receive list count */
+
 	u32 base;
-	u16 rx_halted;
-	u16 tx_halted;
-	u16 rx_pending;		/* ring due a service */
 	u16 exec_pending;
 	u16 mc_reload_wait;	/* a multicast load request is pending */
-	atomic_t tx_count;		/* buffers left */
+	u32 mc_list_valid;	/* True when the mclist is set */
+	u16 xceiver_state;      /* Current transceiver state. bitmapped */ 
+	u16 desired_state;      /* The state we want the transceiver to be in */ 
+	atomic_t tx_count;	/* buffers left */
 	struct wait_queue *event;
-	struct sk_buff *tx_skb[TX_RING_MAX];	/* Transmit ring */
-	u16 tx_skb_top;
-	u16 tx_skb_end;
-	struct sk_buff *rx_skb[RX_RING_MAX];	/* Receive ring */
-	void *rx_ptr[RX_RING_MAX];		/* Data pointers */
-	u32 mc_list_valid;			/* True when the mclist is set */
+
+	struct mc32_ring_desc tx_ring[TX_RING_LEN];	/* Host Transmit ring */
+	struct mc32_ring_desc rx_ring[RX_RING_LEN];	/* Host Receive ring */
+
+	u16 tx_ring_tail;       /* index to tx de-queue end */
+	u16 tx_ring_head;       /* index to tx en-queue end */
+
+	u16 rx_ring_tail;       /* index to rx de-queue end */ 
 };
 
 /* The station (ethernet) address prefix, used for a sanity check. */
@@ -124,18 +184,25 @@
 	char		*name;
 };
 
-static struct mca_adapters_t mc32_adapters[] __initdata = {
+const struct mca_adapters_t mc32_adapters[] = {
 	{ 0x0041, "3COM EtherLink MC/32" },
 	{ 0x8EF5, "IBM High Performance Lan Adapter" },
 	{ 0x0000, NULL }
 };
 
 
-/* Index to functions, as function prototypes. */
+/* Macros for ring index manipulations */ 
+static inline u16 next_rx(u16 rx) { return (rx+1)&(RX_RING_LEN-1); };
+static inline u16 prev_rx(u16 rx) { return (rx-1)&(RX_RING_LEN-1); };
 
+static inline u16 next_tx(u16 tx) { return (tx+1)&(TX_RING_LEN-1); };
+
+
+/* Index to functions, as function prototypes. */
 extern int mc32_probe(struct device *dev);
 
 static int	mc32_probe1(struct device *dev, int ioaddr);
+static int      mc32_command(struct device *dev, u16 cmd, void *data, int len);
 static int	mc32_open(struct device *dev);
 static int	mc32_send_packet(struct sk_buff *skb, struct device *dev);
 static void	mc32_interrupt(int irq, void *dev_id, struct pt_regs *regs);
@@ -144,12 +211,14 @@
 static void	mc32_set_multicast_list(struct device *dev);
 static void	mc32_reset_multicast_list(struct device *dev);
 
-/*
- * Check for a network adaptor of this type, and return '0' iff one exists.
- * If dev->base_addr == 0, probe all likely locations.
- * If dev->base_addr == 1, always return failure.
- * If dev->base_addr == 2, allocate space for the device and return success
- * (detachable devices only).
+/**
+ * mc32_probe:
+ * @dev: device to probe
+ *
+ * Because MCA bus is a real bus and we can scan for cards we could do a
+ * single scan for all boards here. Right now we use the passed in device
+ * structure and scan for only one board. This needs fixing for modules
+ * in paticular.
  */
 
 __initfunc(int mc32_probe(struct device *dev))
@@ -183,15 +252,21 @@
 	return -ENODEV;
 }
 
-/*
- * This is the real probe routine. Linux has a history of friendly device
- * probes on the ISA bus. A good device probes avoids doing writes, and
- * verifies that the correct device exists and functions.
+/**
+ * mc32_probe1:
+ * @dev:  Device structure to fill in
+ * @slot: The MCA bus slot being used by this card
+ *
+ * Decode the slot data and configure the card structures. Having done this we
+ * can reset the card and configure it. The card does a full self test cycle
+ * in firmware so we have to wait for it to return and post us either a 
+ * failure case or some addresses we use to find the board internals.
  */
+
 __initfunc(static int mc32_probe1(struct device *dev, int slot))
 {
 	static unsigned version_printed = 0;
-	int i;
+	int i, err;
 	u8 POS;
 	u32 base;
 	struct mc32_local *lp;
@@ -224,7 +299,7 @@
 		"82586 initialisation failure",
 		"Adapter list configuration error"
 	};
-	
+
 	/* Time to play MCA games */
 
 	if (mc32_debug  &&  version_printed++ == 0)
@@ -327,20 +402,21 @@
 	 *	Grab the IRQ
 	 */
 
-	if(request_irq(dev->irq, &mc32_interrupt, 0, cardname, dev))
-	{
-		printk("%s: unable to get IRQ %d.\n",
-				   dev->name, dev->irq);
-		return -EAGAIN;
+	i = request_irq(dev->irq, &mc32_interrupt, SA_SHIRQ, dev->name, dev); 
+	if(i) {
+		printk("%s: unable to get IRQ %d.\n", dev->name, dev->irq);
+		return i; 
 	}
 
+	request_region(dev->base_addr, MC32_IO_EXTENT, cardname);
+
 	/* Initialize the device structure. */
 	if (dev->priv == NULL) {
 		dev->priv = kmalloc(sizeof(struct mc32_local), GFP_KERNEL);
-		if (dev->priv == NULL)
+		if (dev->priv == NULL)	
 		{
-			free_irq(dev->irq, dev);
-			return -ENOMEM;
+			err = -ENOMEM;
+			goto err_exit_irq; 
 		}
 	}
 
@@ -358,8 +434,8 @@
 		if(i==1000)
 		{
 			printk("%s: failed to boot adapter.\n", dev->name);
-			free_irq(dev->irq, dev);
-			return -ENODEV;
+			err = -ENODEV; 
+			goto err_exit_free;
 		}
 		udelay(1000);
 		if(inb(dev->base_addr+2)&(1<<5))
@@ -373,8 +449,8 @@
 				base<0x0A?" test failure":"");
 		else
 			printk("%s: unknown failure %d.\n", dev->name, base);
-		free_irq(dev->irq, dev);
-		return -ENODEV;
+		err = -ENODEV; 
+		goto err_exit_free;
 	}
 	
 	base=0;
@@ -389,8 +465,8 @@
 			if(n>100)
 			{
 				printk(KERN_ERR "%s: mailbox read fail (%d).\n", dev->name, i);
-				free_irq(dev->irq, dev);
-				return -ENODEV;
+				err = -ENODEV;
+				goto err_exit_free;
 			}
 		}
 
@@ -399,11 +475,11 @@
 	
 	lp->exec_box=bus_to_virt(dev->mem_start+base);
 	
-	base=lp->exec_box->data[1]<<16|lp->exec_box->data[0];
+	base=lp->exec_box->data[1]<<16|lp->exec_box->data[0];  
 	
 	lp->base = dev->mem_start+base;
 	
-	lp->rx_box=bus_to_virt(lp->base + lp->exec_box->data[2]);
+	lp->rx_box=bus_to_virt(lp->base + lp->exec_box->data[2]); 
 	lp->tx_box=bus_to_virt(lp->base + lp->exec_box->data[3]);
 	
 	lp->stats = bus_to_virt(lp->base + lp->exec_box->data[5]);
@@ -412,74 +488,77 @@
 	 *	Descriptor chains (card relative)
 	 */
 	 
-	lp->tx_chain 		= lp->exec_box->data[8];
-	lp->rx_chain 		= lp->exec_box->data[10];
-	lp->tx_len 		= lp->exec_box->data[9];
-	lp->rx_len 		= lp->exec_box->data[11];
-	
-	printk("%s: %d RX buffers, %d TX buffers. Base of 0x%08X.\n",
-		dev->name, lp->rx_len, lp->tx_len, lp->base);
+	lp->tx_chain 		= lp->exec_box->data[8];   /* Transmit list start offset */
+	lp->rx_chain 		= lp->exec_box->data[10];  /* Receive list start offset */
+	lp->tx_len 		= lp->exec_box->data[9];   /* Transmit list count */ 
+	lp->rx_len 		= lp->exec_box->data[11];  /* Receive list count */
 	
-	if(lp->tx_len >TX_RING_MAX)
-		lp->tx_len = TX_RING_MAX;
-		
+	printk("%s: Firmware Rev %d. %d RX buffers, %d TX buffers. Base of 0x%08X.\n",
+		dev->name, lp->exec_box->data[12], lp->rx_len, lp->tx_len, lp->base);
+
 	dev->open		= mc32_open;
 	dev->stop		= mc32_close;
 	dev->hard_start_xmit	= mc32_send_packet;
 	dev->get_stats		= mc32_get_stats;
 	dev->set_multicast_list = mc32_set_multicast_list;
 	
-	lp->rx_halted		= 1;
-	lp->tx_halted		= 1;
-	lp->rx_pending		= 0;
+	lp->xceiver_state = HALTED; 
+	
+	lp->tx_ring_tail=lp->tx_ring_head=0;
 
 	/* Fill in the fields of the device structure with ethernet values. */
 	ether_setup(dev);
+	
 	return 0;
+
+err_exit_free:
+	kfree(dev->priv);
+err_exit_irq:
+	free_irq(dev->irq, dev);
+	release_region(dev->base_addr, MC32_IO_EXTENT);
+	return err;
 }
 
 
-/*
- *	Polled command stuff 
+/**
+ *	mc32_ready_poll:
+ *	@dev:	The device to wait for
+ *	
+ *	Wait until the card becomes ready to accept a command via the
+ *	command register. This tells us nothing about the completion
+ *	status of any pending commands and takes very little time at all.
  */
  
-static void mc32_ring_poll(struct device *dev)
+static void mc32_ready_poll(struct device *dev)
 {
 	int ioaddr = dev->base_addr;
 	while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
 }
 
 
-/*
- *	Send exec commands. This requires a bit of explaining.
+/**
+ *	mc32_command_nowait:
+ *	@dev: The 3c527 to issue the command to
+ *	@cmd: The command word to write to the mailbox
+ *	@data: A data block if the command expects one
+ *	@len: Length of the data block
  *
- *	You feed the card a command, you wait, it interrupts you get a 
- *	reply. All well and good. The complication arises because you use
- *	commands for filter list changes which come in at bh level from things
- *	like IPV6 group stuff.
- *
- *	We have a simple state machine
- *
- *	0	- nothing issued
- *	1	- command issued, wait reply
- *	2	- reply waiting - reader then goes to state 0
- *	3	- command issued, trash reply. In which case the irq
- *		  takes it back to state 0
- */
- 
-
-/*
- *	Send command from interrupt state
+ *	Send a command from interrupt state. If there is a command
+ *	currently being executed then we return an error of -1. It simply
+ *	isn't viable to wait around as commands may be slow. Providing we
+ *	get in, we busy wait for the board to become ready to accept the
+ *	command and issue it. We do not wait for the command to complete
+ *	--- the card will interrupt us when it's done.
  */
 
 static int mc32_command_nowait(struct device *dev, u16 cmd, void *data, int len)
 {
 	struct mc32_local *lp = (struct mc32_local *)dev->priv;
 	int ioaddr = dev->base_addr;
-	
+
 	if(lp->exec_pending)
 		return -1;
-		
+	
 	lp->exec_pending=3;
 	lp->exec_box->mbox=0;
 	lp->exec_box->mbox=cmd;
@@ -493,9 +572,35 @@
 }
 
 
-/*
- *	Send command and block for results. On completion spot and reissue
- *	multicasts
+/**
+ *	mc32_command: 
+ *	@dev: The 3c527 card to issue the command to
+ *	@cmd: The command word to write to the mailbox
+ *	@data: A data block if the command expects one
+ *	@len: Length of the data block
+ *
+ *	Sends exec commands in a user context. This permits us to wait around
+ *	for the replies and also to wait for the command buffer to complete
+ *	from a previous command before we execute our command. After our 
+ *	command completes we will complete any pending multicast reload
+ *	we blocked off by hogging the exec buffer.
+ *
+ *	You feed the card a command, you wait, it interrupts you get a 
+ *	reply. All well and good. The complication arises because you use
+ *	commands for filter list changes which come in at bh level from things
+ *	like IPV6 group stuff.
+ *
+ *	We have a simple state machine
+ *
+ *	0	- nothing issued
+ *
+ *	1	- command issued, wait reply
+ *
+ *	2	- reply waiting - reader then goes to state 0
+ *
+ *	3	- command issued, trash reply. In which case the irq
+ *		  takes it back to state 0
+ *
  */
   
 static int mc32_command(struct device *dev, u16 cmd, void *data, int len)
@@ -531,207 +636,311 @@
 	/* Send the command */
 	while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
 	outb(1<<6, ioaddr+HOST_CMD);	
-	
+
 	save_flags(flags);
 	cli();
+
 	while(lp->exec_pending!=2)
 		sleep_on(&lp->event);
 	lp->exec_pending=0;
 	restore_flags(flags);
 	
-	 
-	if(lp->exec_box->data[0]&(1<<13))
+	if(lp->exec_box->mbox&(1<<13))
 		ret = -1;
+
 	/*
 	 *	A multicast set got blocked - do it now
 	 */
 		
 	if(lp->mc_reload_wait)
+	{
 		mc32_reset_multicast_list(dev);
+	}
 
 	return ret;
 }
 
 
-/*
- *	RX abort
- */
- 
-static void mc32_rx_abort(struct device *dev)
-{
-	struct mc32_local *lp = (struct mc32_local *)dev->priv;
-	int ioaddr = dev->base_addr;
+/**
+ *	mc32_start_transceiver: 
+ *	@dev: The 3c527 card to issue the command to
+ *
+ *	This may be called from the interrupt state, where it is used
+ *	to restart the rx ring if the card runs out of rx buffers. 
+ *	
+ * 	First, we check if it's ok to start the transceiver. We then show
+ * 	the card where to start in the rx ring and issue the
+ * 	commands to start reception and transmission. We don't wait
+ * 	around for these to complete.
+ */ 
 
-	while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
-	
-	lp->rx_box->mbox=0;
-	outb(3<<3, ioaddr+HOST_CMD);	/* Suspend reception */
-}
+static void mc32_start_transceiver(struct device *dev) {
 
- 
-/*
- *	RX enable
- */
- 
-static void mc32_rx_begin(struct device *dev)
-{
 	struct mc32_local *lp = (struct mc32_local *)dev->priv;
 	int ioaddr = dev->base_addr;
-	
-	while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
-	
-	lp->rx_box->mbox=0;
-	outb(1<<3, ioaddr+HOST_CMD);	/* GO */
-	mc32_ring_poll(dev);	
-	
-	lp->rx_halted=0;
-	lp->rx_pending=0;
-}
 
-static void mc32_tx_abort(struct device *dev)
-{
-	struct mc32_local *lp = (struct mc32_local *)dev->priv;
-	int ioaddr = dev->base_addr;
-	
-	while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
-	
+	/* Ignore RX overflow on device closure */ 
+	if (lp->desired_state==HALTED)  
+		return; 
+
+	mc32_ready_poll(dev); 
+
 	lp->tx_box->mbox=0;
-	outb(3, ioaddr+HOST_CMD);	/* Suspend */
-	
-	/* Ring empty */
-	
-	atomic_set(&lp->tx_count, lp->tx_len);
+	lp->rx_box->mbox=0;
+
+	/* Give the card the offset to the post-EOL-bit RX descriptor */ 
+	lp->rx_box->data[0]=lp->rx_ring[prev_rx(lp->rx_ring_tail)].p->next; 
+
+	outb(HOST_CMD_START_RX, ioaddr+HOST_CMD);      
+
+	mc32_ready_poll(dev); 
+	outb(HOST_CMD_RESTRT_TX, ioaddr+HOST_CMD);   /* card ignores this on RX restart */ 
 	
-	/* Flush */
-	if(lp->tx_skb_top!=lp->tx_skb_end)
-	{
-		int i;
-		if(lp->tx_skb_top<=lp->tx_skb_end)
-		{
-			for(i=lp->tx_skb_top;i<lp->tx_skb_end;i++)
-			{
-				dev_kfree_skb(lp->tx_skb[i]);
-				lp->tx_skb[i]=NULL;
-			}
-		}
-		else
-		{
-			for(i=lp->tx_skb_end;i<TX_RING_MAX;i++)
-			{
-				dev_kfree_skb(lp->tx_skb[i]);
-				lp->tx_skb[i]=NULL;
-			}
-			for(i=0;i<lp->tx_skb_top;i++)
-			{
-				dev_kfree_skb(lp->tx_skb[i]);
-				lp->tx_skb[i]=NULL;
-			}
-		}
-	}
-	lp->tx_skb_top=lp->tx_skb_end=0;
+	/* We are not interrupted on start completion */ 
+	lp->xceiver_state=RUNNING; 
 }
 
-/*
- *	TX enable
- */
- 
-static void mc32_tx_begin(struct device *dev)
+
+/**
+ *	mc32_halt_transceiver: 
+ *	@dev: The 3c527 card to issue the command to
+ *
+ *	We issue the commands to halt the card's transceiver. In fact,
+ *	after some experimenting we now simply tell the card to
+ *	suspend. When issuing aborts occasionally odd things happened.
+ *
+ *	We then sleep until the card has notified us that both rx and
+ *	tx have been suspended.
+ */ 
+
+static void mc32_halt_transceiver(struct device *dev) 
 {
 	struct mc32_local *lp = (struct mc32_local *)dev->priv;
 	int ioaddr = dev->base_addr;
-	
-	while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
-	
+	unsigned long flags;
+
+	mc32_ready_poll(dev);	
+
 	lp->tx_box->mbox=0;
-#if 0	
-	outb(5, ioaddr+HOST_CMD);	/* GO */
-	printk("TX=>5\n");
-	mc32_ring_poll(dev);	
-	if(lp->tx_box->mbox&(1<<13))
-		printk("TX begin error!\n");
-#endif		
-	lp->tx_halted=0;
-}
+	lp->rx_box->mbox=0;
 
-	
-/*
- *	Load the rx ring
+	outb(HOST_CMD_SUSPND_RX, ioaddr+HOST_CMD);			
+	mc32_ready_poll(dev); 
+	outb(HOST_CMD_SUSPND_TX, ioaddr+HOST_CMD);	
+		
+	save_flags(flags);
+	cli();
+		
+	while(lp->xceiver_state!=HALTED) 
+		sleep_on(&lp->event); 
+		
+	restore_flags(flags);	
+} 
+
+
+/**
+ *	mc32_load_rx_ring:
+ *	@dev: 3c527 to build the ring for
+ *
+ *	This initalises the on-card and driver datastructures to
+ *	the point where mc32_start_transceiver() can be called.
+ *
+ *	The card sets up the receive ring for us. We are required to use the
+ *	ring it provides although we can change the size of the ring.
+ *
+ * 	We allocate an sk_buff for each ring entry in turn and
+ * 	initalise its house-keeping info. At the same time, we read
+ * 	each 'next' pointer in our rx_ring array. This reduces slow
+ * 	shared-memory reads and makes it easy to access predecessor
+ * 	descriptors.
+ *
+ *	We then set the end-of-list bit for the last entry so that the
+ * 	card will know when it has run out of buffers.
  */
- 
+	 
 static int mc32_load_rx_ring(struct device *dev)
 {
 	struct mc32_local *lp = (struct mc32_local *)dev->priv;
 	int i;
-	u16 base;
+	u16 rx_base;
 	volatile struct skb_header *p;
 	
-	base = lp->rx_box->data[0];
-	
-	/* Fix me - should use card size - also fix flush ! */ 
+	rx_base=lp->rx_chain;
 
-	for(i=0;i<RX_RING_MAX;i++)
+	for(i=0;i<RX_RING_LEN;i++)
 	{
-		lp->rx_skb[i]=alloc_skb(1532, GFP_KERNEL);
-		if(lp->rx_skb[i]==NULL)
+		lp->rx_ring[i].skb=alloc_skb(1532, GFP_KERNEL);
+		skb_reserve(lp->rx_ring[i].skb, 18);  
+
+		if(lp->rx_ring[i].skb==NULL)
 		{
 			for(;i>=0;i--)
-				kfree_skb(lp->rx_skb[i]);
+				kfree_skb(lp->rx_ring[i].skb);
 			return -ENOBUFS;
 		}
-		lp->rx_ptr[i]=lp->rx_skb[i]->data+18;
 		
-		p=bus_to_virt(lp->base+base);
+		p=bus_to_virt(lp->base+rx_base);
+				
 		p->control=0;
-		p->data = virt_to_bus(lp->rx_ptr[i]);
+		p->data=virt_to_bus(lp->rx_ring[i].skb->data);
 		p->status=0;
-		p->length = 1532;
-		base = p->next;
+		p->length=1532;
+	
+		lp->rx_ring[i].p=p; 
+		rx_base=p->next; 
 	}
-	p->control = (1<<6);
-	lp->rx_box->mbox = 0;
+
+	lp->rx_ring[i-1].p->control |= CONTROL_EOL;
+
+	lp->rx_ring_tail=0;
+
 	return 0;
 }	
 
-static void mc32_flush_rx_ring(struct mc32_local *lp)
-{
-	int i;
-	for(i=0;i<RX_RING_MAX;i++)
-		kfree_skb(lp->rx_skb[i]);
-}
 
-static void mc32_flush_tx_ring(struct mc32_local *lp)
+/**
+ *	mc32_flush_rx_ring:
+ *	@lp: Local data of 3c527 to flush the rx ring of
+ *
+ *	Free the buffer for each ring slot. This may be called 
+ *      before mc32_load_rx_ring(), eg. on error in mc32_open().
+ */
+
+static void mc32_flush_rx_ring(struct device *dev)
 {
-	int i;
+	struct mc32_local *lp = (struct mc32_local *)dev->priv;
 	
-	if(lp->tx_skb_top <= lp->tx_skb_end)
+	struct sk_buff *skb;
+	int i; 
+
+	for(i=0; i < RX_RING_LEN; i++) 
+	{ 
+		skb = lp->rx_ring[i].skb;
+		if (skb!=NULL) {
+			kfree_skb(skb);
+			skb=NULL; 
+		}
+		lp->rx_ring[i].p=NULL; 
+	} 
+}
+
+
+/**
+ *	mc32_load_tx_ring: 
+ *	@dev: The 3c527 card to issue the command to
+ *
+ *	This sets up the host transmit data-structures. 
+ *
+ *	First, we obtain from the card it's current postion in the tx
+ *	ring, so that we will know where to begin transmitting
+ *	packets.
+ * 	
+ * 	Then, we read the 'next' pointers from the on-card tx ring into
+ *  	our tx_ring array to reduce slow shared-mem reads. Finally, we
+ * 	intitalise the tx house keeping variables.
+ * 
+ */ 
+
+static void mc32_load_tx_ring(struct device *dev)
+{ 
+	struct mc32_local *lp = (struct mc32_local *)dev->priv;
+	volatile struct skb_header *p;
+	int i; 
+	u16 tx_base;
+
+	tx_base=lp->tx_box->data[0]; 
+
+	for(i=0;i<lp->tx_len;i++) 
 	{
-		for(i=lp->tx_skb_top;i<lp->tx_skb_end;i++)
-			dev_kfree_skb(lp->tx_skb[i]);
+		p=bus_to_virt(lp->base+tx_base);
+		lp->tx_ring[i].p=p; 
+		lp->tx_ring[i].skb=NULL;
+
+		tx_base=p->next;
 	}
-	else
+
+	/* -1 so that tx_ring_head cannot "lap" tx_ring_tail,           */
+	/* which would be bad news for mc32_tx_ring as cur. implemented */ 
+
+	atomic_set(&lp->tx_count, TX_RING_LEN-1); 
+	lp->tx_ring_head=lp->tx_ring_tail=0; 
+} 
+
+
+/**
+ *	mc32_flush_tx_ring:
+ *	@lp: Local data of 3c527 to flush the tx ring of
+ *
+ *	We have to consider two cases here. We want to free the pending
+ *	buffers only. If the ring buffer head is past the start then the
+ *	ring segment we wish to free wraps through zero. The tx ring 
+ *	house-keeping variables are then reset.
+ */
+
+static void mc32_flush_tx_ring(struct device *dev)
+{
+	struct mc32_local *lp = (struct mc32_local *)dev->priv;
+	
+	if(lp->tx_ring_tail!=lp->tx_ring_head)
 	{
-		for(i=0;i<lp->tx_skb_end;i++)
-			dev_kfree_skb(lp->tx_skb[i]);
-		for(i=lp->tx_skb_top;i<TX_RING_MAX;i++)
-			dev_kfree_skb(lp->tx_skb[i]);
+		int i;	
+		if(lp->tx_ring_tail < lp->tx_ring_head)
+		{
+			for(i=lp->tx_ring_tail;i<lp->tx_ring_head;i++)
+			{
+				dev_kfree_skb(lp->tx_ring[i].skb);
+				lp->tx_ring[i].skb=NULL;
+				lp->tx_ring[i].p=NULL; 
+			}
+		}
+		else
+		{
+			for(i=lp->tx_ring_tail; i<TX_RING_LEN; i++) 
+			{
+				dev_kfree_skb(lp->tx_ring[i].skb);
+				lp->tx_ring[i].skb=NULL;
+				lp->tx_ring[i].p=NULL; 
+			}
+			for(i=0; i<lp->tx_ring_head; i++) 
+			{
+				dev_kfree_skb(lp->tx_ring[i].skb);
+				lp->tx_ring[i].skb=NULL;
+				lp->tx_ring[i].p=NULL; 
+			}
+		}
 	}
+	
+	atomic_set(&lp->tx_count, 0); 
+	lp->tx_ring_tail=lp->tx_ring_head=0;
 }
  	
-/*
- * Open/initialize the board. This is called (in the current kernel)
- * sometime after booting when the 'ifconfig' program is run.
+
+/**
+ *	mc32_open
+ *	@dev: device to open
+ *
+ *	The user is trying to bring the card into ready state. This requires
+ *	a brief dialogue with the card. Firstly we enable interrupts and then
+ *	'indications'. Without these enabled the card doesn't bother telling
+ *	us what it has done. This had me puzzled for a week.
+ *
+ *	We configure the number of card descriptors, then load the network
+ *	address and multicast filters. Turn on the workaround mode. This
+ *	works around a bug in the 82586 - it asks the firmware to do
+ *	so. It has a performance (latency) hit but is needed on busy
+ *	[read most] lans. We load the ring with buffers then we kick it
+ *	all off.
  */
 
 static int mc32_open(struct device *dev)
 {
 	int ioaddr = dev->base_addr;
-	u16 zero_word=0;
+	struct mc32_local *lp = (struct mc32_local *)dev->priv;
 	u8 one=1;
 	u8 regs;
-	
-	dev->tbusy = 0;
-	dev->interrupt = 0;
-	dev->start = 1;
+	u16 descnumbuffs[2] = {TX_RING_LEN, RX_RING_LEN};
+
+	MOD_INC_USE_COUNT;
 
 	/*
 	 *	Interrupts enabled
@@ -748,49 +957,84 @@
 
 	mc32_command(dev, 4, &one, 2);
 
-	 	
 	/*
-	 *	Send the command sequence "abort, resume" for RX and TX.
-	 *	The abort cleans up the buffer chains if needed.
+	 *	Poke it to make sure it's really dead. 
 	 */
 
-	mc32_rx_abort(dev);
-	mc32_tx_abort(dev);
-	
+	mc32_halt_transceiver(dev); 
+	mc32_flush_tx_ring(dev); 
+
+	/* 
+	 *	Ask card to set up on-card descriptors to our spec 
+	 */ 
+
+	if(mc32_command(dev, 8, descnumbuffs, 4)) { 
+		printk("%s: %s rejected our buffer configuration!\n",
+	 	       dev->name, cardname);
+		mc32_close(dev); 
+		return -ENOBUFS; 
+	}
+	
+	/* Report new configuration */ 
+	mc32_command(dev, 6, NULL, 0); 
+
+	lp->tx_chain 		= lp->exec_box->data[8];   /* Transmit list start offset */
+	lp->rx_chain 		= lp->exec_box->data[10];  /* Receive list start offset */
+	lp->tx_len 		= lp->exec_box->data[9];   /* Transmit list count */ 
+	lp->rx_len 		= lp->exec_box->data[11];  /* Receive list count */
+ 
 	/* Set Network Address */
 	mc32_command(dev, 1, dev->dev_addr, 6);
 	
 	/* Set the filters */
 	mc32_set_multicast_list(dev);
+		   
+	if (WORKAROUND_82586) { 
+		u16 zero_word=0;
+		mc32_command(dev, 0x0D, &zero_word, 2);   /* 82586 bug workaround on  */
+	}
+
+	mc32_load_tx_ring(dev);
 	
-	/* Issue the 82586 workaround command - this is for "busy lans",
-	   but basically means for all lans now days - has a performance
-	   cost but best set */
-	   
-	mc32_command(dev, 0x0D, &zero_word, 2); /* 82586 bug workaround on */
-	
-	/* Load the ring we just initialised */
-	
-	if(mc32_load_rx_ring(dev))
+	if(mc32_load_rx_ring(dev)) 
 	{
 		mc32_close(dev);
 		return -ENOBUFS;
 	}
+
+	lp->desired_state = RUNNING; 
 	
-	/* And the resume command goes last */
-	
-	mc32_rx_begin(dev);
-	mc32_tx_begin(dev);
-	
-	MOD_INC_USE_COUNT;
+	/* And finally, set the ball rolling... */
+
+	mc32_start_transceiver(dev);
+
+	dev->tbusy = 0;
+	dev->interrupt = 0;
+	dev->start = 1;
 
 	return 0;
 }
 
+
+/**
+ *	mc32_send_packet:
+ *	@skb: buffer to transmit
+ *	@dev: 3c527 to send it out of
+ *
+ *	Transmit a buffer. This normally means throwing the buffer onto
+ *	the transmit queue as the queue is quite large. If the queue is
+ *	full then we set tx_busy and return. Once the interrupt handler
+ *	gets messages telling it to reclaim transmit queue entries we will
+ *	clear tx_busy and the kernel will start calling this again.
+ *
+ *	We use cli rather than spinlocks. Since I have no access to an SMP
+ *	MCA machine I don't plan to change it. It is probably the top 
+ *	performance hit for this driver on SMP however.
+ */
+
 static int mc32_send_packet(struct sk_buff *skb, struct device *dev)
 {
 	struct mc32_local *lp = (struct mc32_local *)dev->priv;
-	int ioaddr = dev->base_addr;
 
 	if (dev->tbusy) {
 		/*
@@ -817,9 +1061,7 @@
 	}
 	else 
 	{
-		unsigned long flags;
-		
-		u16 tx_head;
+		unsigned long flags;	       
 		volatile struct skb_header *p, *np;
 
 		save_flags(flags);
@@ -832,159 +1074,303 @@
 			return 1;
 		}
 
-		tx_head = lp->tx_box->data[0];
-		atomic_dec(&lp->tx_count);
+		atomic_dec(&lp->tx_count); 
 
-		/* We will need this to flush the buffer out */
-		
-		lp->tx_skb[lp->tx_skb_end] = skb;
-		lp->tx_skb_end++;
-		lp->tx_skb_end&=(TX_RING_MAX-1);
-		
-		/* TX suspend - shouldnt be needed but apparently is.
-		   This is a research item ... */
-		   
-		while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
-		lp->tx_box->mbox=0;
-		outb(3, ioaddr+HOST_CMD);
-		
-		/* Transmit now stopped */
 		/* P is the last sending/sent buffer as a pointer */
-		p=(struct skb_header *)bus_to_virt(lp->base+tx_head);
+		p=lp->tx_ring[lp->tx_ring_head].p; 
 		
+		lp->tx_ring_head=next_tx(lp->tx_ring_head); 
+
 		/* NP is the buffer we will be loading */
-		np=(struct skb_header *)bus_to_virt(lp->base+p->next);
-		
-		np->control	|= (1<<6);	/* EOL */
-		wmb();
-				
-		np->length	= skb->len;
+		np=lp->tx_ring[lp->tx_ring_head].p; 
 
-		if(np->length < 60)
-			np->length = 60;
+	        /* We will need this to flush the buffer out */
+		lp->tx_ring[lp->tx_ring_head].skb=skb;
+   	   
+		np->length = (skb->len < ETH_ZLEN) ? ETH_ZLEN : skb->len; 
 			
 		np->data	= virt_to_bus(skb->data);
-		np->status	= 0;
-		np->control	= (1<<7)|(1<<6);	/* EOP EOL */
-		wmb();
-		
-		p->status	= 0;
-		p->control	&= ~(1<<6);
+   		np->status	= 0;
+		np->control     = CONTROL_EOP | CONTROL_EOL;     
+	        wmb();
 		
-		dev->tbusy	= 0;			/* Keep feeding me */		
-		
-		while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
-		lp->tx_box->mbox=0;
-		outb(5, ioaddr+HOST_CMD);		/* Restart TX */
-		restore_flags(flags);
+		p->control     &= ~CONTROL_EOL;     /* Clear EOL on p */ 
+	   
+       	        dev->tbusy	= 0;	       /* Keep feeding me */		
+	
+	        restore_flags(flags);
 	}
 	return 0;
 }
 
+
+/**
+ *	mc32_update_stats:
+ *	@dev: 3c527 to service
+ *
+ * 
+ *	Query and reset the on-card stats. There's the small possibility
+ *	of a race here, which would result in an underestimation of
+ *	actual errors. As such, we'd prefer to keep all our stats
+ *	collection in software. As a rule, we do. However it can't be
+ *	used for rx errors and collisions as, by default, the card discards
+ *	bad rx packets. 
+ *
+ *	Setting the SAV BP in the rx filter command supposedly
+ *	stops this behaviour. However, testing shows that it only seems to
+ *	enable the collation of on-card rx statistics --- the driver
+ *	never sees an RX descriptor with an error status set.
+ *
+ */
+
 static void mc32_update_stats(struct device *dev)
 {
-}
+	struct mc32_local *lp = (struct mc32_local *)dev->priv;
+	volatile struct mc32_stats *st = lp->stats; 
+
+	u32 rx_errors=0; 
+      
+	rx_errors+=lp->net_stats.rx_crc_errors   +=st->rx_crc_errors;         
+	                                           st->rx_crc_errors=0;
+	rx_errors+=lp->net_stats.rx_fifo_errors  +=st->rx_overrun_errors;   
+	                                           st->rx_overrun_errors=0; 
+	rx_errors+=lp->net_stats.rx_frame_errors +=st->rx_alignment_errors; 
+ 	                                           st->rx_alignment_errors=0;
+	rx_errors+=lp->net_stats.rx_length_errors+=st->rx_tooshort_errors; 
+	                                           st->rx_tooshort_errors=0;
+	rx_errors+=lp->net_stats.rx_missed_errors+=st->rx_outofresource_errors;
+	                                           st->rx_outofresource_errors=0; 
+        lp->net_stats.rx_errors=rx_errors; 
+						   
+	/* Number of packets which saw one collision */
+	lp->net_stats.collisions+=st->dataC[10];
+	st->dataC[10]=0; 
+
+	/* Number of packets which saw 2--15 collisions */ 
+	lp->net_stats.collisions+=st->dataC[11]; 
+	st->dataC[11]=0; 
+}	
 
 
+/**
+ *	mc32_rx_ring:
+ *	@dev: 3c527 that needs its receive ring processing
+ *
+ *
+ *	We have received one or more indications from the card that a
+ *	receive has completed. The buffer ring thus contains dirty
+ *	entries. We walk the ring by iterating over the circular rx_ring
+ *	array, starting at the next dirty buffer (which happens to be the
+ *	one we finished up at last time around).
+ *
+ *	For each completed packet, we will either copy it and pass it up
+ * 	the stack or, if the packet is near MTU sized, we allocate
+ *	another buffer and flip the old one up the stack.
+ * 
+ *	We must succeed in keeping a buffer on the ring. If neccessary we
+ *	will toss a received packet rather than lose a ring entry. Once
+ *	the first uncompleted descriptor is found, we move the
+ *	End-Of-List bit to include the buffers just processed.
+ *
+ */
+
 static void mc32_rx_ring(struct device *dev)
 {
-	struct mc32_local *lp=dev->priv;
-	int ioaddr = dev->base_addr;
-	int x=0;
+	struct mc32_local *lp=dev->priv;		
 	volatile struct skb_header *p;
-	u16 base;
-	u16 top;
+	u16 rx_ring_tail = lp->rx_ring_tail;
+	u16 rx_old_tail = rx_ring_tail; 
+
+	int x=0;
 	
-	top = base = lp->rx_box->data[0];
 	do
-	{
-		p=(struct skb_header *)bus_to_virt(base+lp->base);
-		if(!(p->status & (1<<7)))
+	{ 
+		p=lp->rx_ring[rx_ring_tail].p; 
+
+		if(!(p->status & (1<<7))) { /* Not COMPLETED */ 
 			break;
-		if(p->status & (1<<6))
-		{
-			u16 length = p->length;
-			struct sk_buff *skb=dev_alloc_skb(length+2);
-			if(skb!=NULL)
+		} 
+		if(p->status & (1<<6)) /* COMPLETED_OK */
+		{		        
+
+			u16 length=p->length;
+			struct sk_buff *skb; 
+			struct sk_buff *newskb; 
+
+			/* Try to save time by avoiding a copy on big frames */
+
+			if ((length > RX_COPYBREAK) 
+			    && ((newskb=dev_alloc_skb(1532)) != NULL)) 
+			{ 
+				skb=lp->rx_ring[rx_ring_tail].skb;
+				skb_put(skb, length);
+				
+				skb_reserve(newskb,18); 
+				lp->rx_ring[rx_ring_tail].skb=newskb;  
+				p->data=virt_to_bus(newskb->data);  
+			} 
+			else 
 			{
+				skb=dev_alloc_skb(length+2);  
+
+				if(skb==NULL) {
+					lp->net_stats.rx_dropped++; 
+					goto dropped; 
+				}
+
 				skb_reserve(skb,2);
-				/*printk("Frame at %p\n", bus_to_virt(p->data)); */
 				memcpy(skb_put(skb, length),
-					bus_to_virt(p->data), length);
-				skb->protocol=eth_type_trans(skb,dev);
-				skb->dev=dev;
-				lp->net_stats.rx_packets++;
-				lp->net_stats.rx_bytes+=skb->len;
-				netif_rx(skb);
-			}
-			else
-				lp->net_stats.rx_dropped++;
-		}
-		else
-		{
-			lp->net_stats.rx_errors++;
-			switch(p->status&0x0F)
-			{
-				case 1:
-					lp->net_stats.rx_crc_errors++;break;
-				case 2:
-					lp->net_stats.rx_fifo_errors++;break;
-				case 3:
-					lp->net_stats.rx_frame_errors++;break;
-				case 4:
-					lp->net_stats.rx_missed_errors++;break;
-				case 5:
-					lp->net_stats.rx_length_errors++;break;
+				       lp->rx_ring[rx_ring_tail].skb->data, length);
 			}
+			
+			skb->protocol=eth_type_trans(skb,dev); 
+			skb->dev=dev; 
+ 			lp->net_stats.rx_packets++; 
+ 			lp->net_stats.rx_bytes+=skb->len; 
+			netif_rx(skb); 
 		}
-		p->length = 1532;
-		p->control &= ~(1<<6);
+
+	dropped:
+		p->length = 1532; 
 		p->status = 0;
-		base = p->next;
+		
+		rx_ring_tail=next_rx(rx_ring_tail); 
+	}
+        while(x++<48);  
+
+	/* If there was actually a frame to be processed, place the EOL bit */ 
+	/* at the descriptor prior to the one to be filled next */ 
+
+	if (rx_ring_tail != rx_old_tail) 
+	{ 
+		lp->rx_ring[prev_rx(rx_ring_tail)].p->control |=  CONTROL_EOL; 
+		lp->rx_ring[prev_rx(rx_old_tail)].p->control  &= ~CONTROL_EOL; 
+
+		lp->rx_ring_tail=rx_ring_tail; 
 	}
-	while(x++<48);
-	
-	/*
-	 *	Restart ring processing
-	 */	
-	
-	while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
-	lp->rx_box->mbox=0;
-	lp->rx_box->data[0] = top;
-	outb(1<<3, ioaddr+HOST_CMD);	
-	lp->rx_halted = 0;
 }
 
 
-/*
- * The typical workload of the driver:
- *   Handle the network interface interrupts.
+/**
+ *	mc32_tx_ring:
+ *	@dev: 3c527 that needs its transmit ring processing
+ *
+ *
+ *	This operates in a similar fashion to mc32_rx_ring. We iterate
+ *	over the transmit ring. For each descriptor which has been
+ *	processed by the card, we free its associated buffer and note
+ *	any errors. This continues until the transmit ring is emptied
+ *	or we reach a descriptor that hasn't yet been processed by the
+ *	card.
+ * 
+ */
+
+static void mc32_tx_ring(struct device *dev) {
+
+  struct mc32_local *lp=(struct mc32_local *)dev->priv;
+  volatile struct skb_header *np;
+
+  /* NB: lp->tx_count=TX_RING_LEN-1 so that tx_ring_head cannot "lap" tail here */
+
+  while (lp->tx_ring_tail != lp->tx_ring_head)  
+  {   
+	  u16 t; 
+
+	  t=next_tx(lp->tx_ring_tail); 
+	  np=lp->tx_ring[t].p; 
+
+	  if(!(np->status & (1<<7))) { /* Not COMPLETED */ 
+		  break; 
+	  } 
+
+	  lp->net_stats.tx_packets++;
+
+	  if(!(np->status & (1<<6))) /* Not COMPLETED_OK */
+	  {
+		  lp->net_stats.tx_errors++;   
+
+		  switch(np->status&0x0F)
+		  {
+		  case 1:
+			  lp->net_stats.tx_aborted_errors++;break; /* Max collisions */ 
+		  case 2:
+			  lp->net_stats.tx_fifo_errors++;break;
+		  case 3:
+			  lp->net_stats.tx_carrier_errors++;break;
+		  case 4:
+			  lp->net_stats.tx_window_errors++;break;  /* CTS Lost */ 
+		  case 5:
+			  lp->net_stats.tx_aborted_errors++;break; /* Transmit timeout */ 
+		  }
+	  }
+	  
+	  
+	  /* Packets are sent in order - this is
+	     basically a FIFO queue of buffers matching
+	     the card ring */
+	  lp->net_stats.tx_bytes+=lp->tx_ring[t].skb->len;
+	  dev_kfree_skb(lp->tx_ring[t].skb);
+	  lp->tx_ring[t].skb=NULL;
+	  atomic_inc(&lp->tx_count);
+	  dev->tbusy=0;
+	  mark_bh(NET_BH);
+
+	  lp->tx_ring_tail=t; 
+  }
+
+} 
+
+
+/**
+ *	mc32_interrupt:
+ *	@irq: Interrupt number
+ *	@dev_id: 3c527 that requires servicing
+ *	@regs: Registers (unused)
+ *
+ *
+ *	An interrupt is raised whenever the 3c527 writes to the command
+ *	register. This register contains the message it wishes to send us
+ *	packed into a single byte field. We keep reading status entries
+ *	until we have processed all the control items, but simply count
+ *	transmit and receive reports. When all reports are in we empty the
+ *	transceiver rings as appropriate. This saves the overhead of
+ *	multiple command requests.
+ *
+ *	Because MCA is level-triggered, we shouldn't miss indications.
+ *	Therefore, we needn't ask the card to suspend interrupts within
+ *	this handler. The card receives an implicit acknowledgment of the
+ *	current interrupt when we read the command register.
+ *
  */
+
 static void mc32_interrupt(int irq, void *dev_id, struct pt_regs * regs)
 {
 	struct device *dev = dev_id;
 	struct mc32_local *lp;
 	int ioaddr, status, boguscount = 0;
+	int rx_event = 0;
+	int tx_event = 0; 
 	
 	if (dev == NULL) {
 		printk(KERN_WARNING "%s: irq %d for unknown device.\n", cardname, irq);
 		return;
 	}
-	dev->interrupt = 1;
 
+	dev->interrupt = 1;
+ 
 	ioaddr = dev->base_addr;
 	lp = (struct mc32_local *)dev->priv;
 
 	/* See whats cooking */
-	
-	while((inb(ioaddr+2)&(1<<5)) && boguscount++<2000)
+
+	while((inb(ioaddr+HOST_STATUS)&HOST_STATUS_CWR) && boguscount++<2000)
 	{
 		status=inb(ioaddr+HOST_CMD);
 
 #ifdef DEBUG_IRQ		
-		printk("Status TX%d RX%d EX%d OV%d\n",
+		printk("Status TX%d RX%d EX%d OV%d BC%d\n",
 			(status&7), (status>>3)&7, (status>>6)&1,
-			(status>>7)&1);
+			(status>>7)&1, boguscount);
 #endif
 			
 		switch(status&7)
@@ -992,33 +1378,16 @@
 			case 0:
 				break;
 			case 6: /* TX fail */
-				lp->net_stats.tx_errors++;
 			case 2:	/* TX ok */
-				lp->net_stats.tx_packets++;
-				/* Packets are sent in order - this is
-				   basically a FIFO queue of buffers matching
-				   the card ring */
-				lp->net_stats.tx_bytes+=lp->tx_skb[lp->tx_skb_top]->len;
-				dev_kfree_skb(lp->tx_skb[lp->tx_skb_top]);
-				lp->tx_skb[lp->tx_skb_top]=NULL;
-				lp->tx_skb_top++;
-				lp->tx_skb_top&=(TX_RING_MAX-1);
-				atomic_inc(&lp->tx_count);
-				dev->tbusy=0;
-				mark_bh(NET_BH);
+				tx_event = 1; 
 				break;
 			case 3: /* Halt */
 			case 4: /* Abort */
-				lp->tx_halted=1;
-				wake_up(&lp->event);
-				break;
-			case 5:
-				lp->tx_halted=0;
+				lp->xceiver_state |= TX_HALTED; 
 				wake_up(&lp->event);
 				break;
 			default:
-				printk("%s: strange tx ack %d\n", 
-					dev->name, status&7);
+				printk("%s: strange tx ack %d\n", dev->name, status&7);
 		}
 		status>>=3;
 		switch(status&7)
@@ -1026,155 +1395,199 @@
 			case 0:
 				break;
 			case 2:	/* RX */
-				lp->rx_pending=1;
-				if(!lp->rx_halted)
-				{
-					/*
-					 *	Halt ring receive
-					 */
-					while(!(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR));
-					outb(3<<3, ioaddr+HOST_CMD);
-				}
+				rx_event=1; 
 				break;
-			case 3:
-			case 4:
-				lp->rx_halted=1;
-				wake_up(&lp->event);
-				break;
-			case 5:
-				lp->rx_halted=0;
+			case 3: /* Halt */
+			case 4: /* Abort */
+				lp->xceiver_state |= RX_HALTED;
 				wake_up(&lp->event);
 				break;
 			case 6:
 				/* Out of RX buffers stat */
+				/* Must restart rx */
 				lp->net_stats.rx_dropped++;
-				lp->rx_pending=1;
-				/* Must restart */
-				lp->rx_halted=1;
+				mc32_rx_ring(dev); 
+				mc32_start_transceiver(dev); 
 				break;
 			default:
 				printk("%s: strange rx ack %d\n", 
-					dev->name, status&7);
-			
+					dev->name, status&7);			
 		}
 		status>>=3;
 		if(status&1)
 		{
+
 			/* 0=no 1=yes 2=replied, get cmd, 3 = wait reply & dump it */
-			if(lp->exec_pending!=3)
+			
+			if(lp->exec_pending!=3) {
 				lp->exec_pending=2;
-			else
-				lp->exec_pending=0;
-			wake_up(&lp->event);
+				wake_up(&lp->event);
+			}
+			else 
+			{				
+			  	lp->exec_pending=0;
+
+				/* A new multicast set may have been
+				   blocked while the old one was
+				   running. If so, do it now. */
+				   
+				if (lp->mc_reload_wait) 
+					mc32_reset_multicast_list(dev);
+				else 
+					wake_up(&lp->event);			       
+			}
 		}
 		if(status&2)
 		{
 			/*
-			 *	Update the stats as soon as
-			 *	we have it flagged and can 
-			 *	send an immediate reply (CRR set)
+			 *	We get interrupted once per
+			 *	counter that is about to overflow. 
 			 */
-			 
-			if(inb(ioaddr+HOST_STATUS)&HOST_STATUS_CRR)
-			{
-				mc32_update_stats(dev);
-				outb(0, ioaddr+HOST_CMD);
-			}
+
+			mc32_update_stats(dev);			
 		}
 	}
-	
+
+
 	/*
-	 *	Process and restart the receive ring. This has some state
-	 *	as we must halt the ring to process it and halting the ring
-	 *	might not occur in the same IRQ handling loop as we issue
-	 *	the halt.
-	 */
+	 *	Process the transmit and receive rings 
+         */
+
+	if(tx_event) 
+		mc32_tx_ring(dev);
 	 
-	if(lp->rx_pending && lp->rx_halted)
-	{
+	if(rx_event) 
 		mc32_rx_ring(dev);
-		lp->rx_pending = 0;
-	}
-	dev->interrupt = 0;
+
+	dev->interrupt = 0;	
+
 	return;
 }
 
 
-/* The inverse routine to mc32_open(). */
+/**
+ *	mc32_close:
+ *	@dev: 3c527 card to shut down
+ *
+ *	The 3c527 is a bus mastering device. We must be careful how we
+ *	shut it down. It may also be running shared interrupt so we have
+ *	to be sure to silence it properly
+ *
+ *	We indicate that the card is closing to the rest of the
+ *	driver.  Otherwise, it is possible that the card may run out
+ *	of receive buffers and restart the transceiver while we're
+ *	trying to close it.
+ * 
+ *	We abort any receive and transmits going on and then wait until
+ *	any pending exec commands have completed in other code threads.
+ *	In theory we can't get here while that is true, in practice I am
+ *	paranoid
+ *
+ *	We turn off the interrupt enable for the board to be sure it can't
+ *	intefere with other devices.
+ */
 
 static int mc32_close(struct device *dev)
 {
 	struct mc32_local *lp = (struct mc32_local *)dev->priv;
+
 	int ioaddr = dev->base_addr;
 	u8 regs;
 	u16 one=1;
 
+	dev->tbusy = 1;
+	dev->start = 0;
+
+	lp->desired_state = HALTED;
+
 	/*
 	 *	Send the indications on command (handy debug check)
 	 */
 
 	mc32_command(dev, 4, &one, 2);
 
-	/* Abort RX and Abort TX */
-	
-	mc32_rx_abort(dev);	
-	mc32_tx_abort(dev);
+	/* Shut down the transceiver */
+
+	mc32_halt_transceiver(dev); 
 	
 	/* Catch any waiting commands */
 	
 	while(lp->exec_pending==1)
 		sleep_on(&lp->event);
-		
+	       
 	/* Ok the card is now stopping */	
 	
 	regs=inb(ioaddr+HOST_CTRL);
 	regs&=~HOST_CTRL_INTE;
 	outb(regs, ioaddr+HOST_CTRL);
 
-	mc32_flush_rx_ring(lp);
-	mc32_flush_tx_ring(lp);
-	
-	dev->tbusy = 1;
-	dev->start = 0;
-
-	/* Update the statistics here. */
+	mc32_flush_rx_ring(dev);
+	mc32_flush_tx_ring(dev);
+		
+	mc32_update_stats(dev); 
 
 	MOD_DEC_USE_COUNT;
 
 	return 0;
-
 }
 
-/*
- * Get the current statistics.
- * This may be called with the card open or closed.
+
+/**
+ *	mc32_get_stats:
+ *	@dev: The 3c527 card to handle
+ *
+ *	We've collected all the stats we can in software already. Now
+ *	it's time to update those kept on-card and return the lot. 
+ * 
  */
 
 static struct net_device_stats *mc32_get_stats(struct device *dev)
 {
-	struct mc32_local *lp = (struct mc32_local *)dev->priv;
+	struct mc32_local *lp;
+	
+	mc32_update_stats(dev); 
+
+	lp = (struct mc32_local *)dev->priv;
+
 	return &lp->net_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.
+
+/**
+ *	do_mc32_set_multicast_list:
+ *	@dev: 3c527 device to load the list on
+ *	@retry: indicates this is not the first call. 
+ *
+ *
+ * 	Actually set or clear the multicast filter for this adaptor. The
+ *	locking issues are handled by this routine. We have to track
+ *	state as it may take multiple calls to get the command sequence
+ *	completed. We just keep trying to schedule the loads until we
+ *	manage to process them all.
+ * 
+ *	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. 
+ *
+ *	See mc32_update_stats() regards setting the SAV BP bit. 
+ *
  */
+
 static void do_mc32_set_multicast_list(struct device *dev, int retry)
 {
 	struct mc32_local *lp = (struct mc32_local *)dev->priv;
-	u16 filt;
+	u16 filt = (1<<2); /* Save Bad Packets, for stats purposes */ 
 
 	if (dev->flags&IFF_PROMISC)
 		/* Enable promiscuous mode */
-		filt = 1;
+		filt |= 1;
 	else if((dev->flags&IFF_ALLMULTI) || dev->mc_count > 10)
 	{
 		dev->flags|=IFF_PROMISC;
-		filt = 1;
+		filt |= 1;
 	}
 	else if(dev->mc_count)
 	{
@@ -1183,9 +1596,7 @@
 		struct dev_mc_list *dmc=dev->mc_list;
 		
 		int i;
-		
-		filt = 0;
-		
+	       
 		if(retry==0)
 			lp->mc_list_valid = 0;
 		if(!lp->mc_list_valid)
@@ -1208,21 +1619,41 @@
 			lp->mc_list_valid=1;
 		}
 	}
-	else 
-	{
-		filt = 0;
-	}
-	if(mc32_command_nowait(dev, 0, &filt, 2)==-1)
+	
+	if(mc32_command_nowait(dev, 0, &filt, 2)==-1) 
 	{
 		lp->mc_reload_wait = 1;
+	} 
+	else { 
+		lp->mc_reload_wait = 0;
 	}
 }
 
+
+/**
+ *	mc32_set_multicast_list:
+ *	@dev: The 3c527 to use
+ *
+ *	Commence loading the multicast list. This is called when the kernel
+ *	changes the lists. It will override any pending list we are trying to
+ *	load.
+ */
+
 static void mc32_set_multicast_list(struct device *dev)
 {
 	do_mc32_set_multicast_list(dev,0);
 }
 
+
+/**
+ *	mc32_reset_multicast_list:
+ *	@dev: The 3c527 to use
+ *
+ *	Attempt the next step in loading the multicast lists. If this attempt
+ *	fails to complete then it will be scheduled and this function called
+ *	again later from elsewhere.
+ */
+
 static void mc32_reset_multicast_list(struct device *dev)
 {
 	do_mc32_set_multicast_list(dev,1);
@@ -1237,6 +1668,14 @@
 	0, 0,  /* I/O address, IRQ */
 	0, 0, 0, NULL, mc32_probe };
 
+/**
+ *	init_module:
+ *
+ *	Probe and locate a 3c527 card. This really should probe and locate
+ *	all the 3c527 cards in the machine not just one of them. Yes you can
+ *	insmod multiple modules for now but it's a hack.
+ */
+
 int init_module(void)
 {
 	int result;
@@ -1247,6 +1686,17 @@
 	return 0;
 }
 
+/**
+ *	cleanup_module:
+ *
+ *	Unloading time. We release the MCA bus resources and the interrupt
+ *	at which point everything is ready to unload. The card must be stopped
+ *	at this point or we would not have been called. When we unload we
+ *	leave the card stopped but not totally shut down. When the card is
+ *	initialized it must be rebooted or the rings reloaded before any
+ *	transmit operations are allowed to start scribbling into memory.
+ */
+
 void cleanup_module(void)
 {
 	int slot;
@@ -1256,8 +1706,6 @@
 
 	/*
 	 * If we don't do this, we can't re-insmod it later.
-	 * Release irq/dma here, when you have jumpered versions and
-	 * allocate them in mc32_probe1().
 	 */
 	 
 	if (this_device.priv)
@@ -1269,6 +1717,7 @@
 		kfree_s(this_device.priv, sizeof(struct mc32_local));
 	}
 	free_irq(this_device.irq, &this_device);
+	release_region(this_device.base_addr, MC32_IO_EXTENT);
 }
 
 #endif /* MODULE */

FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)