3c527.c

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 *	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 net_device *dev, u16 cmd, void *data, int len)
{
	struct mc32_local *lp = (struct mc32_local *)dev->priv;
	int ioaddr = dev->base_addr;
	unsigned long flags;
	int ret = 0;
	
	/*
	 *	Wait for a command
	 */
	 
	save_flags(flags);
	cli();
	 
	while(lp->exec_pending)
		sleep_on(&lp->event);
		
	/*
	 *	Issue mine
	 */

	lp->exec_pending=1;
	
	restore_flags(flags);
	
	lp->exec_box->mbox=0;
	lp->exec_box->mbox=cmd;
	memcpy((void *)lp->exec_box->data, data, len);
	barrier();	/* the memcpy forgot the volatile so be sure */

	/* 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->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;
}


/**
 *	mc32_start_transceiver	-	tell board to restart tx/rx
 *	@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.
 */ 

static void mc32_start_transceiver(struct net_device *dev) {

	struct mc32_local *lp = (struct mc32_local *)dev->priv;
	int ioaddr = dev->base_addr;

	/* Ignore RX overflow on device closure */ 
	if (lp->desired_state==HALTED)  
		return; 

	mc32_ready_poll(dev); 

	lp->tx_box->mbox=0;
	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 */ 
	
	/* We are not interrupted on start completion */ 
	lp->xceiver_state=RUNNING; 
}


/**
 *	mc32_halt_transceiver	-	tell board to stop tx/rx
 *	@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 net_device *dev) 
{
	struct mc32_local *lp = (struct mc32_local *)dev->priv;
	int ioaddr = dev->base_addr;
	unsigned long flags;

	mc32_ready_poll(dev);	

	lp->tx_box->mbox=0;
	lp->rx_box->mbox=0;

	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	-	load the ring of receive buffers
 *	@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 net_device *dev)
{
	struct mc32_local *lp = (struct mc32_local *)dev->priv;
	int i;
	u16 rx_base;
	volatile struct skb_header *p;
	
	rx_base=lp->rx_chain;

	for(i=0;i<RX_RING_LEN;i++)
	{
		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_ring[i].skb);
			return -ENOBUFS;
		}
		
		p=bus_to_virt(lp->base+rx_base);
				
		p->control=0;
		p->data=virt_to_bus(lp->rx_ring[i].skb->data);
		p->status=0;
		p->length=1532;
	
		lp->rx_ring[i].p=p; 
		rx_base=p->next; 
	}

	lp->rx_ring[i-1].p->control |= CONTROL_EOL;

	lp->rx_ring_tail=0;

	return 0;
}	


/**
 *	mc32_flush_rx_ring	-	free the ring of receive buffers
 *	@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 net_device *dev)
{
	struct mc32_local *lp = (struct mc32_local *)dev->priv;
	
	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	-	load transmit 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 net_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++) 
	{
		p=bus_to_virt(lp->base+tx_base);
		lp->tx_ring[i].p=p; 
		lp->tx_ring[i].skb=NULL;

		tx_base=p->next;
	}

	/* -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 	-	free transmit 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 net_device *dev)
{
	struct mc32_local *lp = (struct mc32_local *)dev->priv;
	
	if(lp->tx_ring_tail!=lp->tx_ring_head)
	{
		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;
}
 	

/**
 *	mc32_open	-	handle 'up' of card
 *	@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 net_device *dev)
{
	int ioaddr = dev->base_addr;
	struct mc32_local *lp = (struct mc32_local *)dev->priv;
	u8 one=1;
	u8 regs;
	u16 descnumbuffs[2] = {TX_RING_LEN, RX_RING_LEN};

	/*
	 *	Interrupts enabled
	 */

	regs=inb(ioaddr+HOST_CTRL);
	regs|=HOST_CTRL_INTE;
	outb(regs, ioaddr+HOST_CTRL);
	

	/*
	 *	Send the indications on command
	 */

	mc32_command(dev, 4, &one, 2);

	/*
	 *	Poke it to make sure it's really dead. 
	 */

	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);
	
	if(mc32_load_rx_ring(dev)) 
	{
		mc32_close(dev);
		return -ENOBUFS;
	}

	lp->desired_state = RUNNING; 
	
	/* And finally, set the ball rolling... */
	mc32_start_transceiver(dev);

	netif_start_queue(dev);

	return 0;
}


/**
 *	mc32_timeout	-	handle a timeout from the network layer
 *	@dev: 3c527 that timed out
 *
 *	Handle a timeout on transmit from the 3c527. This normally means
 *	bad things as the hardware handles cable timeouts and mess for
 *	us.
 *
 */

static void mc32_timeout(struct net_device *dev)
{
	printk(KERN_WARNING "%s: transmit timed out?\n", dev->name);
	/* Try to restart the adaptor. */
	netif_wake_queue(dev);
}


/**
 *	mc32_send_packet	-	queue a frame for transmit
 *	@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 net_device *dev)
{
	struct mc32_local *lp = (struct mc32_local *)dev->priv;
	unsigned long flags;

	volatile struct skb_header *p, *np;

	netif_stop_queue(dev);

	save_flags(flags);
	cli();
		
	if(atomic_read(&lp->tx_count)==0)
	{
		restore_flags(flags);
		return 1;
	}

	atomic_dec(&lp->tx_count); 

	/* P is the last sending/sent buffer as a pointer */
	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=lp->tx_ring[lp->tx_ring_head].p; 

	/* 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     = CONTROL_EOP | CONTROL_EOL;     
	wmb();
		
	p->control     &= ~CONTROL_EOL;     /* Clear EOL on p */ 
	
	restore_flags(flags);

	netif_wake_queue(dev);
	return 0;
}


/**
 *	mc32_update_stats	-	pull off the on board statistics
 *	@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 net_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	-	process the receive 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 net_device *dev)
{
	struct mc32_local *lp=dev->priv;		
	volatile struct skb_header *p;
	u16 rx_ring_tail = lp->rx_ring_tail;
	u16 rx_old_tail = rx_ring_tail; 

	int x=0;
	
	do
	{ 
		p=lp->rx_ring[rx_ring_tail].p; 

		if(!(p->status & (1<<7))) { /* Not COMPLETED */ 
			break;
		} 
		if(p->status & (1<<6)) /* COMPLETED_OK */
		{		        

			u16 length=p->length;
			struct sk_buff *skb; 
			struct sk_buff *newskb;