3c527.c

/**
 *	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 do not disable interrupts or acquire any locks; this can
 *      run concurrently with mc32_tx_ring(), and the function itself
 *      is serialised at a higher layer. However, similarly for the
 *      card itself, we must ensure that we update tx_ring_head only
 *      after we've established a valid packet on the tx ring (and
 *      before we let the card "see" it, to prevent it racing with the
 *      irq handler).
 *
 */

static netdev_tx_t mc32_send_packet(struct sk_buff *skb,
				    struct net_device *dev)
{
	struct mc32_local *lp = netdev_priv(dev);
	u32 head = atomic_read(&lp->tx_ring_head);

	volatile struct skb_header *p, *np;

	netif_stop_queue(dev);

	if(atomic_read(&lp->tx_count)==0) {
		return NETDEV_TX_BUSY;
	}

	if (skb_padto(skb, ETH_ZLEN)) {
		netif_wake_queue(dev);
		return NETDEV_TX_OK;
	}

	atomic_dec(&lp->tx_count);

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

	head = next_tx(head);

	/* NP is the buffer we will be loading */
	np=lp->tx_ring[head].p;

	/* We will need this to flush the buffer out */
	lp->tx_ring[head].skb=skb;

	np->length      = unlikely(skb->len < ETH_ZLEN) ? ETH_ZLEN : skb->len;
	np->data	= isa_virt_to_bus(skb->data);
	np->status	= 0;
	np->control     = CONTROL_EOP | CONTROL_EOL;
	wmb();

	/*
	 * The new frame has been setup; we can now
	 * let the interrupt handler and card "see" it
	 */

	atomic_set(&lp->tx_ring_head, head);
	p->control     &= ~CONTROL_EOL;

	netif_wake_queue(dev);
	return NETDEV_TX_OK;
}


/**
 *	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 = netdev_priv(dev);
	volatile struct mc32_stats *st = lp->stats;

	u32 rx_errors=0;

	rx_errors+=dev->stats.rx_crc_errors   +=st->rx_crc_errors;
	                                           st->rx_crc_errors=0;
	rx_errors+=dev->stats.rx_fifo_errors  +=st->rx_overrun_errors;
	                                           st->rx_overrun_errors=0;
	rx_errors+=dev->stats.rx_frame_errors +=st->rx_alignment_errors;
 	                                           st->rx_alignment_errors=0;
	rx_errors+=dev->stats.rx_length_errors+=st->rx_tooshort_errors;
	                                           st->rx_tooshort_errors=0;
	rx_errors+=dev->stats.rx_missed_errors+=st->rx_outofresource_errors;
	                                           st->rx_outofresource_errors=0;
        dev->stats.rx_errors=rx_errors;

	/* Number of packets which saw one collision */
	dev->stats.collisions+=st->dataC[10];
	st->dataC[10]=0;

	/* Number of packets which saw 2--15 collisions */
	dev->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 necessary 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 = netdev_priv(dev);
	volatile struct skb_header *p;
	u16 rx_ring_tail;
	u16 rx_old_tail;
	int x=0;

	rx_old_tail = rx_ring_tail = lp->rx_ring_tail;

	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;

			/* 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=isa_virt_to_bus(newskb->data);
			}
			else
			{
				skb=dev_alloc_skb(length+2);

				if(skb==NULL) {
					dev->stats.rx_dropped++;
					goto dropped;
				}

				skb_reserve(skb,2);
				memcpy(skb_put(skb, length),
				       lp->rx_ring[rx_ring_tail].skb->data, length);
			}

			skb->protocol=eth_type_trans(skb,dev);
 			dev->stats.rx_packets++;
 			dev->stats.rx_bytes += length;
			netif_rx(skb);
		}

	dropped:
		p->length = 1532;
		p->status = 0;

		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;
	}
}


/**
 *	mc32_tx_ring	-	process completed transmits
 *	@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 net_device *dev)
{
	struct mc32_local *lp = netdev_priv(dev);
	volatile struct skb_header *np;

	/*
	 * We rely on head==tail to mean 'queue empty'.
	 * This is why lp->tx_count=TX_RING_LEN-1: in order to prevent
	 * tx_ring_head wrapping to tail and confusing a 'queue empty'
	 * condition with 'queue full'
	 */

	while (lp->tx_ring_tail != atomic_read(&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;
		}
		dev->stats.tx_packets++;
		if(!(np->status & (1<<6))) /* Not COMPLETED_OK */
		{
			dev->stats.tx_errors++;

			switch(np->status&0x0F)
			{
				case 1:
					dev->stats.tx_aborted_errors++;
					break; /* Max collisions */
				case 2:
					dev->stats.tx_fifo_errors++;
					break;
				case 3:
					dev->stats.tx_carrier_errors++;
					break;
				case 4:
					dev->stats.tx_window_errors++;
					break;  /* CTS Lost */
				case 5:
					dev->stats.tx_aborted_errors++;
					break; /* Transmit timeout */
			}
		}
		/* Packets are sent in order - this is
		    basically a FIFO queue of buffers matching
		    the card ring */
		dev->stats.tx_bytes+=lp->tx_ring[t].skb->len;
		dev_kfree_skb_irq(lp->tx_ring[t].skb);
		lp->tx_ring[t].skb=NULL;
		atomic_inc(&lp->tx_count);
		netif_wake_queue(dev);

		lp->tx_ring_tail=t;
	}

}


/**
 *	mc32_interrupt		-	handle an interrupt from a 3c527
 *	@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 irqreturn_t mc32_interrupt(int irq, void *dev_id)
{
	struct net_device *dev = dev_id;
	struct mc32_local *lp;
	int ioaddr, status, boguscount = 0;
	int rx_event = 0;
	int tx_event = 0;

	ioaddr = dev->base_addr;
	lp = netdev_priv(dev);

	/* See whats cooking */

	while((inb(ioaddr+HOST_STATUS)&HOST_STATUS_CWR) && boguscount++<2000)
	{
		status=inb(ioaddr+HOST_CMD);

		pr_debug("Status TX%d RX%d EX%d OV%d BC%d\n",
			(status&7), (status>>3)&7, (status>>6)&1,
			(status>>7)&1, boguscount);

		switch(status&7)
		{
			case 0:
				break;
			case 6: /* TX fail */
			case 2:	/* TX ok */
				tx_event = 1;
				break;
			case 3: /* Halt */
			case 4: /* Abort */
				complete(&lp->xceiver_cmd);
				break;
			default:
				pr_notice("%s: strange tx ack %d\n", dev->name, status&7);
		}
		status>>=3;
		switch(status&7)
		{
			case 0:
				break;
			case 2:	/* RX */
				rx_event=1;
				break;
			case 3: /* Halt */
			case 4: /* Abort */
				complete(&lp->xceiver_cmd);
				break;
			case 6:
				/* Out of RX buffers stat */
				/* Must restart rx */
				dev->stats.rx_dropped++;
				mc32_rx_ring(dev);
				mc32_start_transceiver(dev);
				break;
			default:
				pr_notice("%s: strange rx ack %d\n",
					dev->name, status&7);
		}
		status>>=3;
		if(status&1)
		{
			/*
			 * No thread is waiting: we need to tidy
			 * up ourself.
			 */

			if (lp->cmd_nonblocking) {
				up(&lp->cmd_mutex);
				if (lp->mc_reload_wait)
					mc32_reset_multicast_list(dev);
			}
			else complete(&lp->execution_cmd);
		}
		if(status&2)
		{
			/*
			 *	We get interrupted once per
			 *	counter that is about to overflow.
			 */

			mc32_update_stats(dev);
		}
	}


	/*
	 *	Process the transmit and receive rings
         */

	if(tx_event)
		mc32_tx_ring(dev);

	if(rx_event)
		mc32_rx_ring(dev);

	return IRQ_HANDLED;
}


/**
 *	mc32_close	-	user configuring the 3c527 down
 *	@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 net_device *dev)
{
	struct mc32_local *lp = netdev_priv(dev);
	int ioaddr = dev->base_addr;

	u8 regs;
	u16 one=1;

	lp->xceiver_desired_state = HALTED;
	netif_stop_queue(dev);

	/*
	 *	Send the indications on command (handy debug check)
	 */

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

	/* Shut down the transceiver */

	mc32_halt_transceiver(dev);

	/* Ensure we issue no more commands beyond this point */

	down(&lp->cmd_mutex);

	/* Ok the card is now stopping */

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

	mc32_flush_rx_ring(dev);
	mc32_flush_tx_ring(dev);

	mc32_update_stats(dev);

	return 0;
}


/**
 *	mc32_get_stats		-	hand back stats to network layer
 *	@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 net_device *dev)
{
	mc32_update_stats(dev);
	return &dev->stats;
}


/**
 *	do_mc32_set_multicast_list	-	attempt to update multicasts
 *	@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 net_device *dev, int retry)
{
	struct mc32_local *lp = netdev_priv(dev);
	u16 filt = (1<<2); /* Save Bad Packets, for stats purposes */

	if ((dev->flags&IFF_PROMISC) ||
	    (dev->flags&IFF_ALLMULTI) ||
	    netdev_mc_count(dev) > 10)
		/* Enable promiscuous mode */
		filt |= 1;
	else if (!netdev_mc_empty(dev))
	{
		unsigned char block[62];
		unsigned char *bp;
		struct netdev_hw_addr *ha;

		if(retry==0)
			lp->mc_list_valid = 0;
		if(!lp->mc_list_valid)
		{
			block[1]=0;
			block[0]=netdev_mc_count(dev);
			bp=block+2;

			netdev_for_each_mc_addr(ha, dev) {
				memcpy(bp, ha->addr, 6);
				bp+=6;
			}
			if(mc32_command_nowait(dev, 2, block,
					       2+6*netdev_mc_count(dev))==-1)
			{
				lp->mc_reload_wait = 1;
				return;
			}
			lp->mc_list_valid=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	-	queue multicast list update
 *	@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 net_device *dev)
{
	do_mc32_set_multicast_list(dev,0);
}


/**
 *	mc32_reset_multicast_list	-	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 net_device *dev)
{
	do_mc32_set_multicast_list(dev,1);
}

static void netdev_get_drvinfo(struct net_device *dev,
			       struct ethtool_drvinfo *info)
{
	strcpy(info->driver, DRV_NAME);
	strcpy(info->version, DRV_VERSION);
	sprintf(info->bus_info, "MCA 0x%lx", dev->base_addr);
}

static u32 netdev_get_msglevel(struct net_device *dev)
{
	return mc32_debug;
}

static void netdev_set_msglevel(struct net_device *dev, u32 level)
{
	mc32_debug = level;
}

static const struct ethtool_ops netdev_ethtool_ops = {
	.get_drvinfo		= netdev_get_drvinfo,
	.get_msglevel		= netdev_get_msglevel,
	.set_msglevel		= netdev_set_msglevel,
};

#ifdef MODULE

static struct net_device *this_device;

/**
 *	init_module		-	entry point
 *
 *	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 init_module(void)
{
	this_device = mc32_probe(-1);
	if (IS_ERR(this_device))
		return PTR_ERR(this_device);
	return 0;
}

/**
 *	cleanup_module	-	free resources for an unload
 *
 *	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 __exit cleanup_module(void)
{
	unregister_netdev(this_device);
	cleanup_card(this_device);
	free_netdev(this_device);
}

#endif /* MODULE */