text: /*
   * sgiseeq.c: Seeq8003 ethernet driver for SGI machines.
   *
   * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
   */
  
  #undef DEBUG
  
  #include <linux/dma-mapping.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/interrupt.h>
  #include <linux/string.h>
  #include <linux/delay.h>
  #include <linux/netdevice.h>
  #include <linux/platform_device.h>
  #include <linux/etherdevice.h>
  #include <linux/skbuff.h>
  
  #include <asm/sgi/hpc3.h>
  #include <asm/sgi/ip22.h>
  #include <asm/sgi/seeq.h>
  
  #include "sgiseeq.h"
  
  static char *sgiseeqstr = "SGI Seeq8003";
  
  /*
   * If you want speed, you do something silly, it always has worked for me.  So,
   * with that in mind, I've decided to make this driver look completely like a
   * stupid Lance from a driver architecture perspective.  Only difference is that
   * here our "ring buffer" looks and acts like a real Lance one does but is
   * laid out like how the HPC DMA and the Seeq want it to.  You'd be surprised
   * how a stupid idea like this can pay off in performance, not to mention
   * making this driver 2,000 times easier to write. ;-)
   */
  
  /* Tune these if we tend to run out often etc. */
  #define SEEQ_RX_BUFFERS  16
  #define SEEQ_TX_BUFFERS  16
  
  #define PKT_BUF_SZ       1584
  
  #define NEXT_RX(i)  (((i) + 1) & (SEEQ_RX_BUFFERS - 1))
  #define NEXT_TX(i)  (((i) + 1) & (SEEQ_TX_BUFFERS - 1))
  #define PREV_RX(i)  (((i) - 1) & (SEEQ_RX_BUFFERS - 1))
  #define PREV_TX(i)  (((i) - 1) & (SEEQ_TX_BUFFERS - 1))
  
  #define TX_BUFFS_AVAIL(sp) ((sp->tx_old <= sp->tx_new) ? \
  			    sp->tx_old + (SEEQ_TX_BUFFERS - 1) - sp->tx_new : \
  			    sp->tx_old - sp->tx_new - 1)
  
  #define VIRT_TO_DMA(sp, v) ((sp)->srings_dma +                                 \
  				  (dma_addr_t)((unsigned long)(v) -            \
  					       (unsigned long)((sp)->rx_desc)))
  
  /* Copy frames shorter than rx_copybreak, otherwise pass on up in
   * a full sized sk_buff.  Value of 100 stolen from tulip.c (!alpha).
   */
  static int rx_copybreak = 100;
  
  #define PAD_SIZE    (128 - sizeof(struct hpc_dma_desc) - sizeof(void *))
  
  struct sgiseeq_rx_desc {
  	volatile struct hpc_dma_desc rdma;
  	u8 padding[PAD_SIZE];
  	struct sk_buff *skb;
  };
  
  struct sgiseeq_tx_desc {
  	volatile struct hpc_dma_desc tdma;
  	u8 padding[PAD_SIZE];
  	struct sk_buff *skb;
  };
  
  /*
   * Warning: This structure is laid out in a certain way because HPC dma
   *          descriptors must be 8-byte aligned.  So don't touch this without
   *          some care.
   */
  struct sgiseeq_init_block { /* Note the name ;-) */
  	struct sgiseeq_rx_desc rxvector[SEEQ_RX_BUFFERS];
  	struct sgiseeq_tx_desc txvector[SEEQ_TX_BUFFERS];
  };
  
  struct sgiseeq_private {
  	struct sgiseeq_init_block *srings;
  	dma_addr_t srings_dma;
  
  	/* Ptrs to the descriptors in uncached space. */
  	struct sgiseeq_rx_desc *rx_desc;
  	struct sgiseeq_tx_desc *tx_desc;
  
  	char *name;
  	struct hpc3_ethregs *hregs;
  	struct sgiseeq_regs *sregs;
  
  	/* Ring entry counters. */
  	unsigned int rx_new, tx_new;
  	unsigned int rx_old, tx_old;
  
  	int is_edlc;
  	unsigned char control;
  	unsigned char mode;
  
  	spinlock_t tx_lock;
  };
  
  static inline void dma_sync_desc_cpu(struct net_device *dev, void *addr)
  {
  	dma_cache_sync(dev->dev.parent, addr, sizeof(struct sgiseeq_rx_desc),
  		       DMA_FROM_DEVICE);
  }
  
  static inline void dma_sync_desc_dev(struct net_device *dev, void *addr)
  {
  	dma_cache_sync(dev->dev.parent, addr, sizeof(struct sgiseeq_rx_desc),
  		       DMA_TO_DEVICE);
  }
  
  static inline void hpc3_eth_reset(struct hpc3_ethregs *hregs)
  {
  	hregs->reset = HPC3_ERST_CRESET | HPC3_ERST_CLRIRQ;
  	udelay(20);
  	hregs->reset = 0;
  }
  
  static inline void reset_hpc3_and_seeq(struct hpc3_ethregs *hregs,
  				       struct sgiseeq_regs *sregs)
  {
  	hregs->rx_ctrl = hregs->tx_ctrl = 0;
  	hpc3_eth_reset(hregs);
  }
  
  #define RSTAT_GO_BITS (SEEQ_RCMD_IGOOD | SEEQ_RCMD_IEOF | SEEQ_RCMD_ISHORT | \
  		       SEEQ_RCMD_IDRIB | SEEQ_RCMD_ICRC)
  
  static inline void seeq_go(struct sgiseeq_private *sp,
  			   struct hpc3_ethregs *hregs,
  			   struct sgiseeq_regs *sregs)
  {
  	sregs->rstat = sp->mode | RSTAT_GO_BITS;
  	hregs->rx_ctrl = HPC3_ERXCTRL_ACTIVE;
  }
  
  static inline void __sgiseeq_set_mac_address(struct net_device *dev)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	struct sgiseeq_regs *sregs = sp->sregs;
  	int i;
  
  	sregs->tstat = SEEQ_TCMD_RB0;
  	for (i = 0; i < 6; i++)
  		sregs->rw.eth_addr[i] = dev->dev_addr[i];
  }
  
  static int sgiseeq_set_mac_address(struct net_device *dev, void *addr)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	struct sockaddr *sa = addr;
  
  	memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
  
  	spin_lock_irq(&sp->tx_lock);
  	__sgiseeq_set_mac_address(dev);
  	spin_unlock_irq(&sp->tx_lock);
  
  	return 0;
  }
  
  #define TCNTINFO_INIT (HPCDMA_EOX | HPCDMA_ETXD)
  #define RCNTCFG_INIT  (HPCDMA_OWN | HPCDMA_EORP | HPCDMA_XIE)
  #define RCNTINFO_INIT (RCNTCFG_INIT | (PKT_BUF_SZ & HPCDMA_BCNT))
  
  static int seeq_init_ring(struct net_device *dev)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	int i;
  
  	netif_stop_queue(dev);
  	sp->rx_new = sp->tx_new = 0;
  	sp->rx_old = sp->tx_old = 0;
  
  	__sgiseeq_set_mac_address(dev);
  
  	/* Setup tx ring. */
  	for(i = 0; i < SEEQ_TX_BUFFERS; i++) {
  		sp->tx_desc[i].tdma.cntinfo = TCNTINFO_INIT;
  		dma_sync_desc_dev(dev, &sp->tx_desc[i]);
  	}
  
  	/* And now the rx ring. */
  	for (i = 0; i < SEEQ_RX_BUFFERS; i++) {
  		if (!sp->rx_desc[i].skb) {
  			dma_addr_t dma_addr;
  			struct sk_buff *skb = netdev_alloc_skb(dev, PKT_BUF_SZ);
  
  			if (skb == NULL)
  				return -ENOMEM;
  			skb_reserve(skb, 2);
  			dma_addr = dma_map_single(dev->dev.parent,
  						  skb->data - 2,
  						  PKT_BUF_SZ, DMA_FROM_DEVICE);
  			sp->rx_desc[i].skb = skb;
  			sp->rx_desc[i].rdma.pbuf = dma_addr;
  		}
  		sp->rx_desc[i].rdma.cntinfo = RCNTINFO_INIT;
  		dma_sync_desc_dev(dev, &sp->rx_desc[i]);
  	}
  	sp->rx_desc[i - 1].rdma.cntinfo |= HPCDMA_EOR;
  	dma_sync_desc_dev(dev, &sp->rx_desc[i - 1]);
  	return 0;
  }
  
  static void seeq_purge_ring(struct net_device *dev)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	int i;
  
  	/* clear tx ring. */
  	for (i = 0; i < SEEQ_TX_BUFFERS; i++) {
  		if (sp->tx_desc[i].skb) {
  			dev_kfree_skb(sp->tx_desc[i].skb);
  			sp->tx_desc[i].skb = NULL;
  		}
  	}
  
  	/* And now the rx ring. */
  	for (i = 0; i < SEEQ_RX_BUFFERS; i++) {
  		if (sp->rx_desc[i].skb) {
  			dev_kfree_skb(sp->rx_desc[i].skb);
  			sp->rx_desc[i].skb = NULL;
  		}
  	}
  }
  
  #ifdef DEBUG
  static struct sgiseeq_private *gpriv;
  static struct net_device *gdev;
  
  static void sgiseeq_dump_rings(void)
  {
  	static int once;
  	struct sgiseeq_rx_desc *r = gpriv->rx_desc;
  	struct sgiseeq_tx_desc *t = gpriv->tx_desc;
  	struct hpc3_ethregs *hregs = gpriv->hregs;
  	int i;
  
  	if (once)
  		return;
  	once++;
  	printk("RING DUMP:\n");
  	for (i = 0; i < SEEQ_RX_BUFFERS; i++) {
  		printk("RX [%d]: @(%p) [%08x,%08x,%08x] ",
  		       i, (&r[i]), r[i].rdma.pbuf, r[i].rdma.cntinfo,
  		       r[i].rdma.pnext);
  		i += 1;
  		printk("-- [%d]: @(%p) [%08x,%08x,%08x]\n",
  		       i, (&r[i]), r[i].rdma.pbuf, r[i].rdma.cntinfo,
  		       r[i].rdma.pnext);
  	}
  	for (i = 0; i < SEEQ_TX_BUFFERS; i++) {
  		printk("TX [%d]: @(%p) [%08x,%08x,%08x] ",
  		       i, (&t[i]), t[i].tdma.pbuf, t[i].tdma.cntinfo,
  		       t[i].tdma.pnext);
  		i += 1;
  		printk("-- [%d]: @(%p) [%08x,%08x,%08x]\n",
  		       i, (&t[i]), t[i].tdma.pbuf, t[i].tdma.cntinfo,
  		       t[i].tdma.pnext);
  	}
  	printk("INFO: [rx_new = %d rx_old=%d] [tx_new = %d tx_old = %d]\n",
  	       gpriv->rx_new, gpriv->rx_old, gpriv->tx_new, gpriv->tx_old);
  	printk("RREGS: rx_cbptr[%08x] rx_ndptr[%08x] rx_ctrl[%08x]\n",
  	       hregs->rx_cbptr, hregs->rx_ndptr, hregs->rx_ctrl);
  	printk("TREGS: tx_cbptr[%08x] tx_ndptr[%08x] tx_ctrl[%08x]\n",
  	       hregs->tx_cbptr, hregs->tx_ndptr, hregs->tx_ctrl);
  }
  #endif
  
  #define TSTAT_INIT_SEEQ (SEEQ_TCMD_IPT|SEEQ_TCMD_I16|SEEQ_TCMD_IC|SEEQ_TCMD_IUF)
  #define TSTAT_INIT_EDLC ((TSTAT_INIT_SEEQ) | SEEQ_TCMD_RB2)
  
  static int init_seeq(struct net_device *dev, struct sgiseeq_private *sp,
  		     struct sgiseeq_regs *sregs)
  {
  	struct hpc3_ethregs *hregs = sp->hregs;
  	int err;
  
  	reset_hpc3_and_seeq(hregs, sregs);
  	err = seeq_init_ring(dev);
  	if (err)
  		return err;
  
  	/* Setup to field the proper interrupt types. */
  	if (sp->is_edlc) {
  		sregs->tstat = TSTAT_INIT_EDLC;
  		sregs->rw.wregs.control = sp->control;
  		sregs->rw.wregs.frame_gap = 0;
  	} else {
  		sregs->tstat = TSTAT_INIT_SEEQ;
  	}
  
  	hregs->rx_ndptr = VIRT_TO_DMA(sp, sp->rx_desc);
  	hregs->tx_ndptr = VIRT_TO_DMA(sp, sp->tx_desc);
  
  	seeq_go(sp, hregs, sregs);
  	return 0;
  }
  
  static void record_rx_errors(struct net_device *dev, unsigned char status)
  {
  	if (status & SEEQ_RSTAT_OVERF ||
  	    status & SEEQ_RSTAT_SFRAME)
  		dev->stats.rx_over_errors++;
  	if (status & SEEQ_RSTAT_CERROR)
  		dev->stats.rx_crc_errors++;
  	if (status & SEEQ_RSTAT_DERROR)
  		dev->stats.rx_frame_errors++;
  	if (status & SEEQ_RSTAT_REOF)
  		dev->stats.rx_errors++;
  }
  
  static inline void rx_maybe_restart(struct sgiseeq_private *sp,
  				    struct hpc3_ethregs *hregs,
  				    struct sgiseeq_regs *sregs)
  {
  	if (!(hregs->rx_ctrl & HPC3_ERXCTRL_ACTIVE)) {
  		hregs->rx_ndptr = VIRT_TO_DMA(sp, sp->rx_desc + sp->rx_new);
  		seeq_go(sp, hregs, sregs);
  	}
  }
  
  static inline void sgiseeq_rx(struct net_device *dev, struct sgiseeq_private *sp,
  			      struct hpc3_ethregs *hregs,
  			      struct sgiseeq_regs *sregs)
  {
  	struct sgiseeq_rx_desc *rd;
  	struct sk_buff *skb = NULL;
  	struct sk_buff *newskb;
  	unsigned char pkt_status;
  	int len = 0;
  	unsigned int orig_end = PREV_RX(sp->rx_new);
  
  	/* Service every received packet. */
  	rd = &sp->rx_desc[sp->rx_new];
  	dma_sync_desc_cpu(dev, rd);
  	while (!(rd->rdma.cntinfo & HPCDMA_OWN)) {
  		len = PKT_BUF_SZ - (rd->rdma.cntinfo & HPCDMA_BCNT) - 3;
  		dma_unmap_single(dev->dev.parent, rd->rdma.pbuf,
  				 PKT_BUF_SZ, DMA_FROM_DEVICE);
  		pkt_status = rd->skb->data[len];
  		if (pkt_status & SEEQ_RSTAT_FIG) {
  			/* Packet is OK. */
  			/* We don't want to receive our own packets */
  			if (!ether_addr_equal(rd->skb->data + 6, dev->dev_addr)) {
  				if (len > rx_copybreak) {
  					skb = rd->skb;
  					newskb = netdev_alloc_skb(dev, PKT_BUF_SZ);
  					if (!newskb) {
  						newskb = skb;
  						skb = NULL;
  						goto memory_squeeze;
  					}
  					skb_reserve(newskb, 2);
  				} else {
  					skb = netdev_alloc_skb_ip_align(dev, len);
  					if (skb)
  						skb_copy_to_linear_data(skb, rd->skb->data, len);
  
  					newskb = rd->skb;
  				}
  memory_squeeze:
  				if (skb) {
  					skb_put(skb, len);
  					skb->protocol = eth_type_trans(skb, dev);
  					netif_rx(skb);
  					dev->stats.rx_packets++;
  					dev->stats.rx_bytes += len;
  				} else {
  					dev->stats.rx_dropped++;
  				}
  			} else {
  				/* Silently drop my own packets */
  				newskb = rd->skb;
  			}
  		} else {
  			record_rx_errors(dev, pkt_status);
  			newskb = rd->skb;
  		}
  		rd->skb = newskb;
  		rd->rdma.pbuf = dma_map_single(dev->dev.parent,
  					       newskb->data - 2,
  					       PKT_BUF_SZ, DMA_FROM_DEVICE);
  
  		/* Return the entry to the ring pool. */
  		rd->rdma.cntinfo = RCNTINFO_INIT;
  		sp->rx_new = NEXT_RX(sp->rx_new);
  		dma_sync_desc_dev(dev, rd);
  		rd = &sp->rx_desc[sp->rx_new];
  		dma_sync_desc_cpu(dev, rd);
  	}
  	dma_sync_desc_cpu(dev, &sp->rx_desc[orig_end]);
  	sp->rx_desc[orig_end].rdma.cntinfo &= ~(HPCDMA_EOR);
  	dma_sync_desc_dev(dev, &sp->rx_desc[orig_end]);
  	dma_sync_desc_cpu(dev, &sp->rx_desc[PREV_RX(sp->rx_new)]);
  	sp->rx_desc[PREV_RX(sp->rx_new)].rdma.cntinfo |= HPCDMA_EOR;
  	dma_sync_desc_dev(dev, &sp->rx_desc[PREV_RX(sp->rx_new)]);
  	rx_maybe_restart(sp, hregs, sregs);
  }
  
  static inline void tx_maybe_reset_collisions(struct sgiseeq_private *sp,
  					     struct sgiseeq_regs *sregs)
  {
  	if (sp->is_edlc) {
  		sregs->rw.wregs.control = sp->control & ~(SEEQ_CTRL_XCNT);
  		sregs->rw.wregs.control = sp->control;
  	}
  }
  
  static inline void kick_tx(struct net_device *dev,
  			   struct sgiseeq_private *sp,
  			   struct hpc3_ethregs *hregs)
  {
  	struct sgiseeq_tx_desc *td;
  	int i = sp->tx_old;
  
  	/* If the HPC aint doin nothin, and there are more packets
  	 * with ETXD cleared and XIU set we must make very certain
  	 * that we restart the HPC else we risk locking up the
  	 * adapter.  The following code is only safe iff the HPCDMA
  	 * is not active!
  	 */
  	td = &sp->tx_desc[i];
  	dma_sync_desc_cpu(dev, td);
  	while ((td->tdma.cntinfo & (HPCDMA_XIU | HPCDMA_ETXD)) ==
  	      (HPCDMA_XIU | HPCDMA_ETXD)) {
  		i = NEXT_TX(i);
  		td = &sp->tx_desc[i];
  		dma_sync_desc_cpu(dev, td);
  	}
  	if (td->tdma.cntinfo & HPCDMA_XIU) {
  		hregs->tx_ndptr = VIRT_TO_DMA(sp, td);
  		hregs->tx_ctrl = HPC3_ETXCTRL_ACTIVE;
  	}
  }
  
  static inline void sgiseeq_tx(struct net_device *dev, struct sgiseeq_private *sp,
  			      struct hpc3_ethregs *hregs,
  			      struct sgiseeq_regs *sregs)
  {
  	struct sgiseeq_tx_desc *td;
  	unsigned long status = hregs->tx_ctrl;
  	int j;
  
  	tx_maybe_reset_collisions(sp, sregs);
  
  	if (!(status & (HPC3_ETXCTRL_ACTIVE | SEEQ_TSTAT_PTRANS))) {
  		/* Oops, HPC detected some sort of error. */
  		if (status & SEEQ_TSTAT_R16)
  			dev->stats.tx_aborted_errors++;
  		if (status & SEEQ_TSTAT_UFLOW)
  			dev->stats.tx_fifo_errors++;
  		if (status & SEEQ_TSTAT_LCLS)
  			dev->stats.collisions++;
  	}
  
  	/* Ack 'em... */
  	for (j = sp->tx_old; j != sp->tx_new; j = NEXT_TX(j)) {
  		td = &sp->tx_desc[j];
  
  		dma_sync_desc_cpu(dev, td);
  		if (!(td->tdma.cntinfo & (HPCDMA_XIU)))
  			break;
  		if (!(td->tdma.cntinfo & (HPCDMA_ETXD))) {
  			if (!(status & HPC3_ETXCTRL_ACTIVE)) {
  				hregs->tx_ndptr = VIRT_TO_DMA(sp, td);
  				hregs->tx_ctrl = HPC3_ETXCTRL_ACTIVE;
  			}
  			break;
  		}
  		dev->stats.tx_packets++;
  		sp->tx_old = NEXT_TX(sp->tx_old);
  		td->tdma.cntinfo &= ~(HPCDMA_XIU | HPCDMA_XIE);
  		td->tdma.cntinfo |= HPCDMA_EOX;
  		if (td->skb) {
  			dev_kfree_skb_any(td->skb);
  			td->skb = NULL;
  		}
  		dma_sync_desc_dev(dev, td);
  	}
  }
  
  static irqreturn_t sgiseeq_interrupt(int irq, void *dev_id)
  {
  	struct net_device *dev = (struct net_device *) dev_id;
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	struct hpc3_ethregs *hregs = sp->hregs;
  	struct sgiseeq_regs *sregs = sp->sregs;
  
  	spin_lock(&sp->tx_lock);
  
  	/* Ack the IRQ and set software state. */
  	hregs->reset = HPC3_ERST_CLRIRQ;
  
  	/* Always check for received packets. */
  	sgiseeq_rx(dev, sp, hregs, sregs);
  
  	/* Only check for tx acks if we have something queued. */
  	if (sp->tx_old != sp->tx_new)
  		sgiseeq_tx(dev, sp, hregs, sregs);
  
  	if ((TX_BUFFS_AVAIL(sp) > 0) && netif_queue_stopped(dev)) {
  		netif_wake_queue(dev);
  	}
  	spin_unlock(&sp->tx_lock);
  
  	return IRQ_HANDLED;
  }
  
  static int sgiseeq_open(struct net_device *dev)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	struct sgiseeq_regs *sregs = sp->sregs;
  	unsigned int irq = dev->irq;
  	int err;
  
  	if (request_irq(irq, sgiseeq_interrupt, 0, sgiseeqstr, dev)) {
  		printk(KERN_ERR "Seeq8003: Can't get irq %d\n", dev->irq);
  		return -EAGAIN;
  	}
  
  	err = init_seeq(dev, sp, sregs);
  	if (err)
  		goto out_free_irq;
  
  	netif_start_queue(dev);
  
  	return 0;
  
  out_free_irq:
  	free_irq(irq, dev);
  
  	return err;
  }
  
  static int sgiseeq_close(struct net_device *dev)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	struct sgiseeq_regs *sregs = sp->sregs;
  	unsigned int irq = dev->irq;
  
  	netif_stop_queue(dev);
  
  	/* Shutdown the Seeq. */
  	reset_hpc3_and_seeq(sp->hregs, sregs);
  	free_irq(irq, dev);
  	seeq_purge_ring(dev);
  
  	return 0;
  }
  
  static inline int sgiseeq_reset(struct net_device *dev)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	struct sgiseeq_regs *sregs = sp->sregs;
  	int err;
  
  	err = init_seeq(dev, sp, sregs);
  	if (err)
  		return err;
  
  	netif_trans_update(dev); /* prevent tx timeout */
  	netif_wake_queue(dev);
  
  	return 0;
  }
  
  static int sgiseeq_start_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	struct hpc3_ethregs *hregs = sp->hregs;
  	unsigned long flags;
  	struct sgiseeq_tx_desc *td;
  	int len, entry;
  
  	spin_lock_irqsave(&sp->tx_lock, flags);
  
  	/* Setup... */
  	len = skb->len;
  	if (len < ETH_ZLEN) {
  		if (skb_padto(skb, ETH_ZLEN)) {
  			spin_unlock_irqrestore(&sp->tx_lock, flags);
  			return NETDEV_TX_OK;
  		}
  		len = ETH_ZLEN;
  	}
  
  	dev->stats.tx_bytes += len;
  	entry = sp->tx_new;
  	td = &sp->tx_desc[entry];
  	dma_sync_desc_cpu(dev, td);
  
  	/* Create entry.  There are so many races with adding a new
  	 * descriptor to the chain:
  	 * 1) Assume that the HPC is off processing a DMA chain while
  	 *    we are changing all of the following.
  	 * 2) Do no allow the HPC to look at a new descriptor until
  	 *    we have completely set up it's state.  This means, do
  	 *    not clear HPCDMA_EOX in the current last descritptor
  	 *    until the one we are adding looks consistent and could
  	 *    be processes right now.
  	 * 3) The tx interrupt code must notice when we've added a new
  	 *    entry and the HPC got to the end of the chain before we
  	 *    added this new entry and restarted it.
  	 */
  	td->skb = skb;
  	td->tdma.pbuf = dma_map_single(dev->dev.parent, skb->data,
  				       len, DMA_TO_DEVICE);
  	td->tdma.cntinfo = (len & HPCDMA_BCNT) |
  	                   HPCDMA_XIU | HPCDMA_EOXP | HPCDMA_XIE | HPCDMA_EOX;
  	dma_sync_desc_dev(dev, td);
  	if (sp->tx_old != sp->tx_new) {
  		struct sgiseeq_tx_desc *backend;
  
  		backend = &sp->tx_desc[PREV_TX(sp->tx_new)];
  		dma_sync_desc_cpu(dev, backend);
  		backend->tdma.cntinfo &= ~HPCDMA_EOX;
  		dma_sync_desc_dev(dev, backend);
  	}
  	sp->tx_new = NEXT_TX(sp->tx_new); /* Advance. */
  
  	/* Maybe kick the HPC back into motion. */
  	if (!(hregs->tx_ctrl & HPC3_ETXCTRL_ACTIVE))
  		kick_tx(dev, sp, hregs);
  
  	if (!TX_BUFFS_AVAIL(sp))
  		netif_stop_queue(dev);
  	spin_unlock_irqrestore(&sp->tx_lock, flags);
  
  	return NETDEV_TX_OK;
  }
  
  static void timeout(struct net_device *dev)
  {
  	printk(KERN_NOTICE "%s: transmit timed out, resetting\n", dev->name);
  	sgiseeq_reset(dev);
  
  	netif_trans_update(dev); /* prevent tx timeout */
  	netif_wake_queue(dev);
  }
  
  static void sgiseeq_set_multicast(struct net_device *dev)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	unsigned char oldmode = sp->mode;
  
  	if(dev->flags & IFF_PROMISC)
  		sp->mode = SEEQ_RCMD_RANY;
  	else if ((dev->flags & IFF_ALLMULTI) || !netdev_mc_empty(dev))
  		sp->mode = SEEQ_RCMD_RBMCAST;
  	else
  		sp->mode = SEEQ_RCMD_RBCAST;
  
  	/* XXX I know this sucks, but is there a better way to reprogram
  	 * XXX the receiver? At least, this shouldn't happen too often.
  	 */
  
  	if (oldmode != sp->mode)
  		sgiseeq_reset(dev);
  }
  
  static inline void setup_tx_ring(struct net_device *dev,
  				 struct sgiseeq_tx_desc *buf,
  				 int nbufs)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	int i = 0;
  
  	while (i < (nbufs - 1)) {
  		buf[i].tdma.pnext = VIRT_TO_DMA(sp, buf + i + 1);
  		buf[i].tdma.pbuf = 0;
  		dma_sync_desc_dev(dev, &buf[i]);
  		i++;
  	}
  	buf[i].tdma.pnext = VIRT_TO_DMA(sp, buf);
  	dma_sync_desc_dev(dev, &buf[i]);
  }
  
  static inline void setup_rx_ring(struct net_device *dev,
  				 struct sgiseeq_rx_desc *buf,
  				 int nbufs)
  {
  	struct sgiseeq_private *sp = netdev_priv(dev);
  	int i = 0;
  
  	while (i < (nbufs - 1)) {
  		buf[i].rdma.pnext = VIRT_TO_DMA(sp, buf + i + 1);
  		buf[i].rdma.pbuf = 0;
  		dma_sync_desc_dev(dev, &buf[i]);
  		i++;
  	}
  	buf[i].rdma.pbuf = 0;
  	buf[i].rdma.pnext = VIRT_TO_DMA(sp, buf);
  	dma_sync_desc_dev(dev, &buf[i]);
  }
  
  static const struct net_device_ops sgiseeq_netdev_ops = {
  	.ndo_open		= sgiseeq_open,
  	.ndo_stop		= sgiseeq_close,
  	.ndo_start_xmit		= sgiseeq_start_xmit,
  	.ndo_tx_timeout		= timeout,
  	.ndo_set_rx_mode	= sgiseeq_set_multicast,
  	.ndo_set_mac_address	= sgiseeq_set_mac_address,
  	.ndo_change_mtu		= eth_change_mtu,
  	.ndo_validate_addr	= eth_validate_addr,
  };
  
  static int sgiseeq_probe(struct platform_device *pdev)
  {
  	struct sgiseeq_platform_data *pd = dev_get_platdata(&pdev->dev);
  	struct hpc3_regs *hpcregs = pd->hpc;
  	struct sgiseeq_init_block *sr;
  	unsigned int irq = pd->irq;
  	struct sgiseeq_private *sp;
  	struct net_device *dev;
  	int err;
  
  	dev = alloc_etherdev(sizeof (struct sgiseeq_private));
  	if (!dev) {
  		err = -ENOMEM;
  		goto err_out;
  	}
  
  	platform_set_drvdata(pdev, dev);
  	sp = netdev_priv(dev);
  
  	/* Make private data page aligned */
  	sr = dma_alloc_noncoherent(&pdev->dev, sizeof(*sp->srings),
  				&sp->srings_dma, GFP_KERNEL);
  	if (!sr) {
  		printk(KERN_ERR "Sgiseeq: Page alloc failed, aborting.\n");
  		err = -ENOMEM;
  		goto err_out_free_dev;
  	}
  	sp->srings = sr;
  	sp->rx_desc = sp->srings->rxvector;
  	sp->tx_desc = sp->srings->txvector;
  	spin_lock_init(&sp->tx_lock);
  
  	/* A couple calculations now, saves many cycles later. */
  	setup_rx_ring(dev, sp->rx_desc, SEEQ_RX_BUFFERS);
  	setup_tx_ring(dev, sp->tx_desc, SEEQ_TX_BUFFERS);
  
  	memcpy(dev->dev_addr, pd->mac, ETH_ALEN);
  
  #ifdef DEBUG
  	gpriv = sp;
  	gdev = dev;
  #endif
  	sp->sregs = (struct sgiseeq_regs *) &hpcregs->eth_ext[0];
  	sp->hregs = &hpcregs->ethregs;
  	sp->name = sgiseeqstr;
  	sp->mode = SEEQ_RCMD_RBCAST;
  
  	/* Setup PIO and DMA transfer timing */
  	sp->hregs->pconfig = 0x161;
  	sp->hregs->dconfig = HPC3_EDCFG_FIRQ | HPC3_EDCFG_FEOP |
  			     HPC3_EDCFG_FRXDC | HPC3_EDCFG_PTO | 0x026;
  
  	/* Setup PIO and DMA transfer timing */
  	sp->hregs->pconfig = 0x161;
  	sp->hregs->dconfig = HPC3_EDCFG_FIRQ | HPC3_EDCFG_FEOP |
  			     HPC3_EDCFG_FRXDC | HPC3_EDCFG_PTO | 0x026;
  
  	/* Reset the chip. */
  	hpc3_eth_reset(sp->hregs);
  
  	sp->is_edlc = !(sp->sregs->rw.rregs.collision_tx[0] & 0xff);
  	if (sp->is_edlc)
  		sp->control = SEEQ_CTRL_XCNT | SEEQ_CTRL_ACCNT |
  			      SEEQ_CTRL_SFLAG | SEEQ_CTRL_ESHORT |
  			      SEEQ_CTRL_ENCARR;
  
  	dev->netdev_ops		= &sgiseeq_netdev_ops;
  	dev->watchdog_timeo	= (200 * HZ) / 1000;
  	dev->irq		= irq;
  
  	if (register_netdev(dev)) {
  		printk(KERN_ERR "Sgiseeq: Cannot register net device, "
  		       "aborting.\n");
  		err = -ENODEV;
  		goto err_out_free_attrs;
  	}
  
  	printk(KERN_INFO "%s: %s %pM\n", dev->name, sgiseeqstr, dev->dev_addr);
  
  	return 0;
  
  err_out_free_attrs:
  	dma_free_attrs(&pdev->dev, sizeof(*sp->srings), sp->srings,
  		       sp->srings_dma, DMA_ATTR_NON_CONSISTENT);
  err_out_free_dev:
  	free_netdev(dev);
  
  err_out:
  	return err;
  }
  
  static int __exit sgiseeq_remove(struct platform_device *pdev)
  {
  	struct net_device *dev = platform_get_drvdata(pdev);
  	struct sgiseeq_private *sp = netdev_priv(dev);
  
  	unregister_netdev(dev);
  	dma_free_noncoherent(&pdev->dev, sizeof(*sp->srings), sp->srings,
  			     sp->srings_dma);
  	free_netdev(dev);
  
  	return 0;
  }
  
  static struct platform_driver sgiseeq_driver = {
  	.probe	= sgiseeq_probe,
  	.remove	= __exit_p(sgiseeq_remove),
  	.driver = {
  		.name	= "sgiseeq",
  	}
  };
  
  module_platform_driver(sgiseeq_driver);
  
  MODULE_DESCRIPTION("SGI Seeq 8003 driver");
  MODULE_AUTHOR("Linux/MIPS Mailing List <linux-mips@linux-mips.org>");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:sgiseeq");
  