drivers/net/tulip/interrupt.c

/*
	drivers/net/tulip/interrupt.c

	Copyright 2000,2001  The Linux Kernel Team
	Written/copyright 1994-2001 by Donald Becker.

	This software may be used and distributed according to the terms
	of the GNU General Public License, incorporated herein by reference.

	Please refer to Documentation/DocBook/tulip-user.{pdf,ps,html}
	for more information on this driver.
        Please submit bugs to http://bugzilla.kernel.org/ .

*/

#include <linux/pci.h>
#include "tulip.h"
#include <linux/etherdevice.h>

int tulip_rx_copybreak;
unsigned int tulip_max_interrupt_work;

#ifdef CONFIG_TULIP_NAPI_HW_MITIGATION
#define MIT_SIZE 15
#define MIT_TABLE 15 /* We use 0 or max */

static unsigned int mit_table[MIT_SIZE+1] =
{
        /*  CRS11 21143 hardware Mitigation Control Interrupt
            We use only RX mitigation we other techniques for
            TX intr. mitigation.

           31    Cycle Size (timer control)
           30:27 TX timer in 16 * Cycle size
           26:24 TX No pkts before Int.
           23:20 RX timer in Cycle size
           19:17 RX No pkts before Int.
           16       Continues Mode (CM)
        */

        0x0,             /* IM disabled */
        0x80150000,      /* RX time = 1, RX pkts = 2, CM = 1 */
        0x80150000,
        0x80270000,
        0x80370000,
        0x80490000,
        0x80590000,
        0x80690000,
        0x807B0000,
        0x808B0000,
        0x809D0000,
        0x80AD0000,
        0x80BD0000,
        0x80CF0000,
        0x80DF0000,
//       0x80FF0000      /* RX time = 16, RX pkts = 7, CM = 1 */
        0x80F10000      /* RX time = 16, RX pkts = 0, CM = 1 */
};
#endif


int tulip_refill_rx(struct net_device *dev)
{
	struct tulip_private *tp = netdev_priv(dev);
	int entry;
	int refilled = 0;

	/* Refill the Rx ring buffers. */
	for (; tp->cur_rx - tp->dirty_rx > 0; tp->dirty_rx++) {
		entry = tp->dirty_rx % RX_RING_SIZE;
		if (tp->rx_buffers[entry].skb == NULL) {
			struct sk_buff *skb;
			dma_addr_t mapping;

			skb = tp->rx_buffers[entry].skb = dev_alloc_skb(PKT_BUF_SZ);
			if (skb == NULL)
				break;

			mapping = pci_map_single(tp->pdev, skb->data, PKT_BUF_SZ,
						 PCI_DMA_FROMDEVICE);
			tp->rx_buffers[entry].mapping = mapping;

			skb->dev = dev;			/* Mark as being used by this device. */
			tp->rx_ring[entry].buffer1 = cpu_to_le32(mapping);
			refilled++;
		}
		tp->rx_ring[entry].status = cpu_to_le32(DescOwned);
	}
	if(tp->chip_id == LC82C168) {
		if(((ioread32(tp->base_addr + CSR5)>>17)&0x07) == 4) {
			/* Rx stopped due to out of buffers,
			 * restart it
			 */
			iowrite32(0x01, tp->base_addr + CSR2);
		}
	}
	return refilled;
}

#ifdef CONFIG_TULIP_NAPI

void oom_timer(unsigned long data)
{
        struct net_device *dev = (struct net_device *)data;
	struct tulip_private *tp = netdev_priv(dev);
	netif_rx_schedule(&tp->napi);
}

int tulip_poll(struct napi_struct *napi, int budget)
{
	struct tulip_private *tp = container_of(napi, struct tulip_private, napi);
	struct net_device *dev = tp->dev;
	int entry = tp->cur_rx % RX_RING_SIZE;
	int work_done = 0;
#ifdef CONFIG_TULIP_NAPI_HW_MITIGATION
	int received = 0;
#endif

#ifdef CONFIG_TULIP_NAPI_HW_MITIGATION

/* that one buffer is needed for mit activation; or might be a
   bug in the ring buffer code; check later -- JHS*/

        if (budget >=RX_RING_SIZE) budget--;
#endif

	if (tulip_debug > 4)
		printk(KERN_DEBUG " In tulip_rx(), entry %d %8.8x.\n", entry,
			   tp->rx_ring[entry].status);

       do {
		if (ioread32(tp->base_addr + CSR5) == 0xffffffff) {
			printk(KERN_DEBUG " In tulip_poll(), hardware disappeared.\n");
			break;
		}
               /* Acknowledge current RX interrupt sources. */
               iowrite32((RxIntr | RxNoBuf), tp->base_addr + CSR5);


               /* If we own the next entry, it is a new packet. Send it up. */
               while ( ! (tp->rx_ring[entry].status & cpu_to_le32(DescOwned))) {
                       s32 status = le32_to_cpu(tp->rx_ring[entry].status);

                       if (tp->dirty_rx + RX_RING_SIZE == tp->cur_rx)
                               break;

                       if (tulip_debug > 5)
                               printk(KERN_DEBUG "%s: In tulip_rx(), entry %d %8.8x.\n",
                                      dev->name, entry, status);

		       if (++work_done >= budget)
                               goto not_done;

                       if ((status & 0x38008300) != 0x0300) {
                               if ((status & 0x38000300) != 0x0300) {
                                /* Ingore earlier buffers. */
                                       if ((status & 0xffff) != 0x7fff) {
                                               if (tulip_debug > 1)
                                                       printk(KERN_WARNING "%s: Oversized Ethernet frame "
                                                              "spanned multiple buffers, status %8.8x!\n",
                                                              dev->name, status);
                                               tp->stats.rx_length_errors++;
                                       }
                               } else if (status & RxDescFatalErr) {
                                /* There was a fatal error. */
                                       if (tulip_debug > 2)
                                               printk(KERN_DEBUG "%s: Receive error, Rx status %8.8x.\n",
                                                      dev->name, status);
                                       tp->stats.rx_errors++; /* end of a packet.*/
                                       if (status & 0x0890) tp->stats.rx_length_errors++;
                                       if (status & 0x0004) tp->stats.rx_frame_errors++;
                                       if (status & 0x0002) tp->stats.rx_crc_errors++;
                                       if (status & 0x0001) tp->stats.rx_fifo_errors++;
                               }
                       } else {
                               /* Omit the four octet CRC from the length. */
                               short pkt_len = ((status >> 16) & 0x7ff) - 4;
                               struct sk_buff *skb;

#ifndef final_version
                               if (pkt_len > 1518) {
                                       printk(KERN_WARNING "%s: Bogus packet size of %d (%#x).\n",
                                              dev->name, pkt_len, pkt_len);
                                       pkt_len = 1518;
                                       tp->stats.rx_length_errors++;
                               }
#endif
                               /* Check if the packet is long enough to accept without copying
                                  to a minimally-sized skbuff. */
                               if (pkt_len < tulip_rx_copybreak
                                   && (skb = dev_alloc_skb(pkt_len + 2)) != NULL) {
                                       skb_reserve(skb, 2);    /* 16 byte align the IP header */
                                       pci_dma_sync_single_for_cpu(tp->pdev,
								   tp->rx_buffers[entry].mapping,
								   pkt_len, PCI_DMA_FROMDEVICE);
#if ! defined(__alpha__)
                                       skb_copy_to_linear_data(skb, tp->rx_buffers[entry].skb->data,
                                                        pkt_len);
                                       skb_put(skb, pkt_len);
#else
                                       memcpy(skb_put(skb, pkt_len),
                                              tp->rx_buffers[entry].skb->data,
                                              pkt_len);
#endif
                                       pci_dma_sync_single_for_device(tp->pdev,
								      tp->rx_buffers[entry].mapping,
								      pkt_len, PCI_DMA_FROMDEVICE);
                               } else {        /* Pass up the skb already on the Rx ring. */
                                       char *temp = skb_put(skb = tp->rx_buffers[entry].skb,
                                                            pkt_len);

#ifndef final_version
                                       if (tp->rx_buffers[entry].mapping !=
                                           le32_to_cpu(tp->rx_ring[entry].buffer1)) {
                                               printk(KERN_ERR "%s: Internal fault: The skbuff addresses "
                                                      "do not match in tulip_rx: %08x vs. %08llx %p / %p.\n",
                                                      dev->name,
                                                      le32_to_cpu(tp->rx_ring[entry].buffer1),
                                                      (unsigned long long)tp->rx_buffers[entry].mapping,
                                                      skb->head, temp);
                                       }
#endif

                                       pci_unmap_single(tp->pdev, tp->rx_buffers[entry].mapping,
                                                        PKT_BUF_SZ, PCI_DMA_FROMDEVICE);

                                       tp->rx_buffers[entry].skb = NULL;
                                       tp->rx_buffers[entry].mapping = 0;
                               }
                               skb->protocol = eth_type_trans(skb, dev);

                               netif_receive_skb(skb);

                               tp->stats.rx_packets++;
                               tp->stats.rx_bytes += pkt_len;
                       }
#ifdef CONFIG_TULIP_NAPI_HW_MITIGATION
		       received++;
#endif

                       entry = (++tp->cur_rx) % RX_RING_SIZE;
                       if (tp->cur_rx - tp->dirty_rx > RX_RING_SIZE/4)
                               tulip_refill_rx(dev);

                }

               /* New ack strategy... irq does not ack Rx any longer
                  hopefully this helps */

               /* Really bad things can happen here... If new packet arrives
                * and an irq arrives (tx or just due to occasionally unset
                * mask), it will be acked by irq handler, but new thread
                * is not scheduled. It is major hole in design.
                * No idea how to fix this if "playing with fire" will fail
                * tomorrow (night 011029). If it will not fail, we won
                * finally: amount of IO did not increase at all. */
       } while ((ioread32(tp->base_addr + CSR5) & RxIntr));

 #ifdef CONFIG_TULIP_NAPI_HW_MITIGATION

          /* We use this simplistic scheme for IM. It's proven by
             real life installations. We can have IM enabled
            continuesly but this would cause unnecessary latency.
            Unfortunely we can't use all the NET_RX_* feedback here.
            This would turn on IM for devices that is not contributing
            to backlog congestion with unnecessary latency.

             We monitor the device RX-ring and have:

             HW Interrupt Mitigation either ON or OFF.

            ON:  More then 1 pkt received (per intr.) OR we are dropping
             OFF: Only 1 pkt received

             Note. We only use min and max (0, 15) settings from mit_table */


          if( tp->flags &  HAS_INTR_MITIGATION) {
                 if( received > 1 ) {
                         if( ! tp->mit_on ) {
                                 tp->mit_on = 1;
                                 iowrite32(mit_table[MIT_TABLE], tp->base_addr + CSR11);
                         }
                  }
                 else {
                         if( tp->mit_on ) {
                                 tp->mit_on = 0;
                                 iowrite32(0, tp->base_addr + CSR11);
                         }
                  }
          }

#endif /* CONFIG_TULIP_NAPI_HW_MITIGATION */

         tulip_refill_rx(dev);

         /* If RX ring is not full we are out of memory. */
         if (tp->rx_buffers[tp->dirty_rx % RX_RING_SIZE].skb == NULL)
		 goto oom;

         /* Remove us from polling list and enable RX intr. */

         netif_rx_complete(napi);
         iowrite32(tulip_tbl[tp->chip_id].valid_intrs, tp->base_addr+CSR7);

         /* The last op happens after poll completion. Which means the following:
          * 1. it can race with disabling irqs in irq handler
          * 2. it can race with dise/enabling irqs in other poll threads
          * 3. if an irq raised after beginning loop, it will be immediately
          *    triggered here.
          *
          * Summarizing: the logic results in some redundant irqs both
          * due to races in masking and due to too late acking of already
          * processed irqs. But it must not result in losing events.
          */

         return work_done;

 not_done:
         if (tp->cur_rx - tp->dirty_rx > RX_RING_SIZE/2 ||
             tp->rx_buffers[tp->dirty_rx % RX_RING_SIZE].skb == NULL)
                 tulip_refill_rx(dev);

         if (tp->rx_buffers[tp->dirty_rx % RX_RING_SIZE].skb == NULL)
		 goto oom;

         return work_done;

 oom:    /* Executed with RX ints disabled */

         /* Start timer, stop polling, but do not enable rx interrupts. */
         mod_timer(&tp->oom_timer, jiffies+1);

         /* Think: timer_pending() was an explicit signature of bug.
          * Timer can be pending now but fired and completed
          * before we did netif_rx_complete(). See? We would lose it. */

         /* remove ourselves from the polling list */
         netif_rx_complete(napi);

         return work_done;
}

#else /* CONFIG_TULIP_NAPI */

static int tulip_rx(struct net_device *dev)
{
	struct tulip_private *tp = netdev_priv(dev);
	int entry = tp->cur_rx % RX_RING_SIZE;
	int rx_work_limit = tp->dirty_rx + RX_RING_SIZE - tp->cur_rx;
	int received = 0;

	if (tulip_debug > 4)
		printk(KERN_DEBUG " In tulip_rx(), entry %d %8.8x.\n", entry,
			   tp->rx_ring[entry].status);
	/* If we own the next entry, it is a new packet. Send it up. */
	while ( ! (tp->rx_ring[entry].status & cpu_to_le32(DescOwned))) {
		s32 status = le32_to_cpu(tp->rx_ring[entry].status);

		if (tulip_debug > 5)
			printk(KERN_DEBUG "%s: In tulip_rx(), entry %d %8.8x.\n",
				   dev->name, entry, status);
		if (--rx_work_limit < 0)
			break;
		if ((status & 0x38008300) != 0x0300) {
			if ((status & 0x38000300) != 0x0300) {
				/* Ingore earlier buffers. */
				if ((status & 0xffff) != 0x7fff) {
					if (tulip_debug > 1)
						printk(KERN_WARNING "%s: Oversized Ethernet frame "
							   "spanned multiple buffers, status %8.8x!\n",
							   dev->name, status);
					tp->stats.rx_length_errors++;
				}
			} else if (status & RxDescFatalErr) {
				/* There was a fatal error. */
				if (tulip_debug > 2)
					printk(KERN_DEBUG "%s: Receive error, Rx status %8.8x.\n",
						   dev->name, status);
				tp->stats.rx_errors++; /* end of a packet.*/
				if (status & 0x0890) tp->stats.rx_length_errors++;
				if (status & 0x0004) tp->stats.rx_frame_errors++;
				if (status & 0x0002) tp->stats.rx_crc_errors++;
				if (status & 0x0001) tp->stats.rx_fifo_errors++;
			}
		} else {
			/* Omit the four octet CRC from the length. */
			short pkt_len = ((status >> 16) & 0x7ff) - 4;
			struct sk_buff *skb;

#ifndef final_version
			if (pkt_len > 1518) {
				printk(KERN_WARNING "%s: Bogus packet size of %d (%#x).\n",
					   dev->name, pkt_len, pkt_len);
				pkt_len = 1518;
				tp->stats.rx_length_errors++;
			}
#endif

			/* Check if the packet is long enough to accept without copying
			   to a minimally-sized skbuff. */
			if (pkt_len < tulip_rx_copybreak
				&& (skb = dev_alloc_skb(pkt_len + 2)) != NULL) {
				skb_reserve(skb, 2);	/* 16 byte align the IP header */
				pci_dma_sync_single_for_cpu(tp->pdev,
							    tp->rx_buffers[entry].mapping,
							    pkt_len, PCI_DMA_FROMDEVICE);
#if ! defined(__alpha__)
				skb_copy_to_linear_data(skb, tp->rx_buffers[entry].skb->data,
						 pkt_len);
				skb_put(skb, pkt_len);
#else
				memcpy(skb_put(skb, pkt_len),
				       tp->rx_buffers[entry].skb->data,
				       pkt_len);
#endif
				pci_dma_sync_single_for_device(tp->pdev,
							       tp->rx_buffers[entry].mapping,
							       pkt_len, PCI_DMA_FROMDEVICE);
			} else { 	/* Pass up the skb already on the Rx ring. */
				char *temp = skb_put(skb = tp->rx_buffers[entry].skb,
						     pkt_len);

#ifndef final_version
				if (tp->rx_buffers[entry].mapping !=
				    le32_to_cpu(tp->rx_ring[entry].buffer1)) {
					printk(KERN_ERR "%s: Internal fault: The skbuff addresses "
					       "do not match in tulip_rx: %08x vs. %Lx %p / %p.\n",
					       dev->name,
					       le32_to_cpu(tp->rx_ring[entry].buffer1),
					       (long long)tp->rx_buffers[entry].mapping,
					       skb->head, temp);
				}
#endif

				pci_unmap_single(tp->pdev, tp->rx_buffers[entry].mapping,
						 PKT_BUF_SZ, PCI_DMA_FROMDEVICE);

				tp->rx_buffers[entry].skb = NULL;
				tp->rx_buffers[entry].mapping = 0;
			}
			skb->protocol = eth_type_trans(skb, dev);

			netif_rx(skb);

			tp->stats.rx_packets++;
			tp->stats.rx_bytes += pkt_len;
		}
		received++;
		entry = (++tp->cur_rx) % RX_RING_SIZE;
	}
	return received;
}
#endif  /* CONFIG_TULIP_NAPI */

static inline unsigned int phy_interrupt (struct net_device *dev)
{
#ifdef __hppa__
	struct tulip_private *tp = netdev_priv(dev);
	int csr12 = ioread32(tp->base_addr + CSR12) & 0xff;

	if (csr12 != tp->csr12_shadow) {
		/* ack interrupt */
		iowrite32(csr12 | 0x02, tp->base_addr + CSR12);
		tp->csr12_shadow = csr12;
		/* do link change stuff */
		spin_lock(&tp->lock);
		tulip_check_duplex(dev);
		spin_unlock(&tp->lock);
		/* clear irq ack bit */
		iowrite32(csr12 & ~0x02, tp->base_addr + CSR12);

		return 1;
	}
#endif

	return 0;
}

/* The interrupt handler does all of the Rx thread work and cleans up
   after the Tx thread. */
irqreturn_t tulip_interrupt(int irq, void *dev_instance)
{
	struct net_device *dev = (struct net_device *)dev_instance;
	struct tulip_private *tp = netdev_priv(dev);
	void __iomem *ioaddr = tp->base_addr;
	int csr5;
	int missed;
	int rx = 0;
	int tx = 0;
	int oi = 0;
	int maxrx = RX_RING_SIZE;
	int maxtx = TX_RING_SIZE;
	int maxoi = TX_RING_SIZE;
#ifdef CONFIG_TULIP_NAPI
	int rxd = 0;
#else
	int entry;
#endif
	unsigned int work_count = tulip_max_interrupt_work;
	unsigned int handled = 0;

	/* Let's see whether the interrupt really is for us */
	csr5 = ioread32(ioaddr + CSR5);

        if (tp->flags & HAS_PHY_IRQ)
	        handled = phy_interrupt (dev);

	if ((csr5 & (NormalIntr|AbnormalIntr)) == 0)
		return IRQ_RETVAL(handled);

	tp->nir++;

	do {

#ifdef CONFIG_TULIP_NAPI

		if (!rxd && (csr5 & (RxIntr | RxNoBuf))) {
			rxd++;
			/* Mask RX intrs and add the device to poll list. */
			iowrite32(tulip_tbl[tp->chip_id].valid_intrs&~RxPollInt, ioaddr + CSR7);
			netif_rx_schedule(&tp->napi);

			if (!(csr5&~(AbnormalIntr|NormalIntr|RxPollInt|TPLnkPass)))
                               break;
		}

               /* Acknowledge the interrupt sources we handle here ASAP
                  the poll function does Rx and RxNoBuf acking */

		iowrite32(csr5 & 0x0001ff3f, ioaddr + CSR5);

#else
		/* Acknowledge all of the current interrupt sources ASAP. */
		iowrite32(csr5 & 0x0001ffff, ioaddr + CSR5);


		if (csr5 & (RxIntr | RxNoBuf)) {
				rx += tulip_rx(dev);
			tulip_refill_rx(dev);
		}

#endif /*  CONFIG_TULIP_NAPI */

		if (tulip_debug > 4)
			printk(KERN_DEBUG "%s: interrupt  csr5=%#8.8x new csr5=%#8.8x.\n",
			       dev->name, csr5, ioread32(ioaddr + CSR5));


		if (csr5 & (TxNoBuf | TxDied | TxIntr | TimerInt)) {
			unsigned int dirty_tx;

			spin_lock(&tp->lock);

			for (dirty_tx = tp->dirty_tx; tp->cur_tx - dirty_tx > 0;
				 dirty_tx++) {
				int entry = dirty_tx % TX_RING_SIZE;
				int status = le32_to_cpu(tp->tx_ring[entry].status);

				if (status < 0)
					break;			/* It still has not been Txed */

				/* Check for Rx filter setup frames. */
				if (tp->tx_buffers[entry].skb == NULL) {
					/* test because dummy frames not mapped */
					if (tp->tx_buffers[entry].mapping)
						pci_unmap_single(tp->pdev,
							 tp->tx_buffers[entry].mapping,
							 sizeof(tp->setup_frame),
							 PCI_DMA_TODEVICE);
					continue;
				}

				if (status & 0x8000) {
					/* There was an major error, log it. */
#ifndef final_version
					if (tulip_debug > 1)
						printk(KERN_DEBUG "%s: Transmit error, Tx status %8.8x.\n",
							   dev->name, status);
#endif
					tp->stats.tx_errors++;
					if (status & 0x4104) tp->stats.tx_aborted_errors++;
					if (status & 0x0C00) tp->stats.tx_carrier_errors++;
					if (status & 0x0200) tp->stats.tx_window_errors++;
					if (status & 0x0002) tp->stats.tx_fifo_errors++;
					if ((status & 0x0080) && tp->full_duplex == 0)
						tp->stats.tx_heartbeat_errors++;
				} else {
					tp->stats.tx_bytes +=
						tp->tx_buffers[entry].skb->len;
					tp->stats.collisions += (status >> 3) & 15;
					tp->stats.tx_packets++;
				}

				pci_unmap_single(tp->pdev, tp->tx_buffers[entry].mapping,
						 tp->tx_buffers[entry].skb->len,
						 PCI_DMA_TODEVICE);

				/* Free the original skb. */
				dev_kfree_skb_irq(tp->tx_buffers[entry].skb);
				tp->tx_buffers[entry].skb = NULL;
				tp->tx_buffers[entry].mapping = 0;
				tx++;
			}

#ifndef final_version
			if (tp->cur_tx - dirty_tx > TX_RING_SIZE) {
				printk(KERN_ERR "%s: Out-of-sync dirty pointer, %d vs. %d.\n",
					   dev->name, dirty_tx, tp->cur_tx);
				dirty_tx += TX_RING_SIZE;
			}
#endif

			if (tp->cur_tx - dirty_tx < TX_RING_SIZE - 2)
				netif_wake_queue(dev);

			tp->dirty_tx = dirty_tx;
			if (csr5 & TxDied) {
				if (tulip_debug > 2)
					printk(KERN_WARNING "%s: The transmitter stopped."
						   "  CSR5 is %x, CSR6 %x, new CSR6 %x.\n",
						   dev->name, csr5, ioread32(ioaddr + CSR6), tp->csr6);
				tulip_restart_rxtx(tp);
			}
			spin_unlock(&tp->lock);
		}

		/* Log errors. */
		if (csr5 & AbnormalIntr) {	/* Abnormal error summary bit. */
			if (csr5 == 0xffffffff)
				break;
			if (csr5 & TxJabber) tp->stats.tx_errors++;
			if (csr5 & TxFIFOUnderflow) {
				if ((tp->csr6 & 0xC000) != 0xC000)
					tp->csr6 += 0x4000;	/* Bump up the Tx threshold */
				else
					tp->csr6 |= 0x00200000;  /* Store-n-forward. */
				/* Restart the transmit process. */
				tulip_restart_rxtx(tp);
				iowrite32(0, ioaddr + CSR1);
			}
			if (csr5 & (RxDied | RxNoBuf)) {
				if (tp->flags & COMET_MAC_ADDR) {
					iowrite32(tp->mc_filter[0], ioaddr + 0xAC);
					iowrite32(tp->mc_filter[1], ioaddr + 0xB0);
				}
			}
			if (csr5 & RxDied) {		/* Missed a Rx frame. */
                                tp->stats.rx_missed_errors += ioread32(ioaddr + CSR8) & 0xffff;
				tp->stats.rx_errors++;
				tulip_start_rxtx(tp);
			}
			/*
			 * NB: t21142_lnk_change() does a del_timer_sync(), so be careful if this
			 * call is ever done under the spinlock
			 */
			if (csr5 & (TPLnkPass | TPLnkFail | 0x08000000)) {
				if (tp->link_change)
					(tp->link_change)(dev, csr5);
			}
			if (csr5 & SystemError) {
				int error = (csr5 >> 23) & 7;
				/* oops, we hit a PCI error.  The code produced corresponds
				 * to the reason:
				 *  0 - parity error
				 *  1 - master abort
				 *  2 - target abort
				 * Note that on parity error, we should do a software reset
				 * of the chip to get it back into a sane state (according
				 * to the 21142/3 docs that is).
				 *   -- rmk
				 */
				printk(KERN_ERR "%s: (%lu) System Error occurred (%d)\n",
					dev->name, tp->nir, error);
			}
			/* Clear all error sources, included undocumented ones! */
			iowrite32(0x0800f7ba, ioaddr + CSR5);
			oi++;
		}
		if (csr5 & TimerInt) {

			if (tulip_debug > 2)
				printk(KERN_ERR "%s: Re-enabling interrupts, %8.8x.\n",
					   dev->name, csr5);
			iowrite32(tulip_tbl[tp->chip_id].valid_intrs, ioaddr + CSR7);
			tp->ttimer = 0;
			oi++;
		}
		if (tx > maxtx || rx > maxrx || oi > maxoi) {
			if (tulip_debug > 1)
				printk(KERN_WARNING "%s: Too much work during an interrupt, "
					   "csr5=0x%8.8x. (%lu) (%d,%d,%d)\n", dev->name, csr5, tp->nir, tx, rx, oi);

                       /* Acknowledge all interrupt sources. */
                        iowrite32(0x8001ffff, ioaddr + CSR5);
                        if (tp->flags & HAS_INTR_MITIGATION) {
                     /* Josip Loncaric at ICASE did extensive experimentation
			to develop a good interrupt mitigation setting.*/
                                iowrite32(0x8b240000, ioaddr + CSR11);
                        } else if (tp->chip_id == LC82C168) {
				/* the LC82C168 doesn't have a hw timer.*/
				iowrite32(0x00, ioaddr + CSR7);
				mod_timer(&tp->timer, RUN_AT(HZ/50));
			} else {
                          /* Mask all interrupting sources, set timer to
				re-enable. */
                                iowrite32(((~csr5) & 0x0001ebef) | AbnormalIntr | TimerInt, ioaddr + CSR7);
                                iowrite32(0x0012, ioaddr + CSR11);
                        }
			break;
		}

		work_count--;
		if (work_count == 0)
			break;

		csr5 = ioread32(ioaddr + CSR5);

#ifdef CONFIG_TULIP_NAPI
		if (rxd)
			csr5 &= ~RxPollInt;
	} while ((csr5 & (TxNoBuf |
			  TxDied |
			  TxIntr |
			  TimerInt |
			  /* Abnormal intr. */
			  RxDied |
			  TxFIFOUnderflow |
			  TxJabber |
			  TPLnkFail |
			  SystemError )) != 0);
#else
	} while ((csr5 & (NormalIntr|AbnormalIntr)) != 0);

	tulip_refill_rx(dev);

	/* check if the card is in suspend mode */
	entry = tp->dirty_rx % RX_RING_SIZE;
	if (tp->rx_buffers[entry].skb == NULL) {
		if (tulip_debug > 1)
			printk(KERN_WARNING "%s: in rx suspend mode: (%lu) (tp->cur_rx = %u, ttimer = %d, rx = %d) go/stay in suspend mode\n", dev->name, tp->nir, tp->cur_rx, tp->ttimer, rx);
		if (tp->chip_id == LC82C168) {
			iowrite32(0x00, ioaddr + CSR7);
			mod_timer(&tp->timer, RUN_AT(HZ/50));
		} else {
			if (tp->ttimer == 0 || (ioread32(ioaddr + CSR11) & 0xffff) == 0) {
				if (tulip_debug > 1)
					printk(KERN_WARNING "%s: in rx suspend mode: (%lu) set timer\n", dev->name, tp->nir);
				iowrite32(tulip_tbl[tp->chip_id].valid_intrs | TimerInt,
					ioaddr + CSR7);
				iowrite32(TimerInt, ioaddr + CSR5);
				iowrite32(12, ioaddr + CSR11);
				tp->ttimer = 1;
			}
		}
	}
#endif /* CONFIG_TULIP_NAPI */

	if ((missed = ioread32(ioaddr + CSR8) & 0x1ffff)) {
		tp->stats.rx_dropped += missed & 0x10000 ? 0x10000 : missed;
	}

	if (tulip_debug > 4)
		printk(KERN_DEBUG "%s: exiting interrupt, csr5=%#4.4x.\n",
			   dev->name, ioread32(ioaddr + CSR5));

	return IRQ_HANDLED;
}