znet.c

讲述linux的初始化过程

		*zn.tx_cur++ = length;
		if (zn.tx_cur + rnd_len + 1 > zn.tx_end) {
			int semi_cnt = (zn.tx_end - zn.tx_cur)<<1; /* Cvrt to byte cnt. */
			memcpy(zn.tx_cur, buf, semi_cnt);
			rnd_len -= semi_cnt>>1;
			memcpy(zn.tx_start, buf + semi_cnt, length - semi_cnt);
			zn.tx_cur = zn.tx_start + rnd_len;
		} else {
			memcpy(zn.tx_cur, buf, skb->len);
			zn.tx_cur += rnd_len;
		}
		*zn.tx_cur++ = 0;

		spin_lock_irqsave(&lp->lock, flags);
		{
			*tx_link = CMD0_TRANSMIT + CMD0_CHNL_1;
			/* Is this always safe to do? */
			outb(CMD0_TRANSMIT + CMD0_CHNL_1,ioaddr);
		}
		spin_unlock_irqrestore (&lp->lock, flags);

		dev->trans_start = jiffies;
		netif_start_queue (dev);

		if (znet_debug > 4)
		  printk(KERN_DEBUG "%s: Transmitter queued, length %d.\n", dev->name, length);
	}
	dev_kfree_skb(skb); 
	return 0;
}

/* The ZNET interrupt handler. */
static void	znet_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
	struct net_device *dev = dev_id;
	struct net_local *lp = (struct net_local *)dev->priv;
	int ioaddr;
	int boguscnt = 20;

	if (dev == NULL) {
		printk(KERN_WARNING "znet_interrupt(): IRQ %d for unknown device.\n", irq);
		return;
	}

	spin_lock (&lp->lock);
	
	ioaddr = dev->base_addr;

	outb(CMD0_STAT0, ioaddr);
	do {
		ushort status = inb(ioaddr);
		if (znet_debug > 5) {
			ushort result, rx_ptr, running;
			outb(CMD0_STAT1, ioaddr);
			result = inw(ioaddr);
			outb(CMD0_STAT2, ioaddr);
			rx_ptr = inw(ioaddr);
			outb(CMD0_STAT3, ioaddr);
			running = inb(ioaddr);
			printk(KERN_DEBUG "%s: interrupt, status %02x, %04x %04x %02x serial %d.\n",
				 dev->name, status, result, rx_ptr, running, boguscnt);
		}
		if ((status & 0x80) == 0)
			break;

		if ((status & 0x0F) == 4) {	/* Transmit done. */
			int tx_status;
			outb(CMD0_STAT1, ioaddr);
			tx_status = inw(ioaddr);
			/* It's undocumented, but tx_status seems to match the i82586. */
			if (tx_status & 0x2000) {
				lp->stats.tx_packets++;
				lp->stats.collisions += tx_status & 0xf;
			} else {
				if (tx_status & 0x0600)  lp->stats.tx_carrier_errors++;
				if (tx_status & 0x0100)  lp->stats.tx_fifo_errors++;
				if (!(tx_status & 0x0040)) lp->stats.tx_heartbeat_errors++;
				if (tx_status & 0x0020)  lp->stats.tx_aborted_errors++;
				/* ...and the catch-all. */
				if ((tx_status | 0x0760) != 0x0760)
				  lp->stats.tx_errors++;
			}
			netif_wake_queue (dev);
		}

		if ((status & 0x40)
			|| (status & 0x0f) == 11) {
			znet_rx(dev);
		}
		/* Clear the interrupts we've handled. */
		outb(CMD0_ACK,ioaddr);
	} while (boguscnt--);

	spin_unlock (&lp->lock);
	
	return;
}

static void znet_rx(struct net_device *dev)
{
	struct net_local *lp = (struct net_local *)dev->priv;
	int ioaddr = dev->base_addr;
	int boguscount = 1;
	short next_frame_end_offset = 0; 		/* Offset of next frame start. */
	short *cur_frame_end;
	short cur_frame_end_offset;

	outb(CMD0_STAT2, ioaddr);
	cur_frame_end_offset = inw(ioaddr);

	if (cur_frame_end_offset == zn.rx_cur - zn.rx_start) {
		printk(KERN_WARNING "%s: Interrupted, but nothing to receive, offset %03x.\n",
			   dev->name, cur_frame_end_offset);
		return;
	}

	/* Use same method as the Crynwr driver: construct a forward list in
	   the same area of the backwards links we now have.  This allows us to
	   pass packets to the upper layers in the order they were received --
	   important for fast-path sequential operations. */
	 while (zn.rx_start + cur_frame_end_offset != zn.rx_cur
			&& ++boguscount < 5) {
		unsigned short hi_cnt, lo_cnt, hi_status, lo_status;
		int count, status;

		if (cur_frame_end_offset < 4) {
			/* Oh no, we have a special case: the frame trailer wraps around
			   the end of the ring buffer.  We've saved space at the end of
			   the ring buffer for just this problem. */
			memcpy(zn.rx_end, zn.rx_start, 8);
			cur_frame_end_offset += (RX_BUF_SIZE/2);
		}
		cur_frame_end = zn.rx_start + cur_frame_end_offset - 4;

		lo_status = *cur_frame_end++;
		hi_status = *cur_frame_end++;
		status = ((hi_status & 0xff) << 8) + (lo_status & 0xff);
		lo_cnt = *cur_frame_end++;
		hi_cnt = *cur_frame_end++;
		count = ((hi_cnt & 0xff) << 8) + (lo_cnt & 0xff);

		if (znet_debug > 5)
		  printk(KERN_DEBUG "Constructing trailer at location %03x, %04x %04x %04x %04x"
				 " count %#x status %04x.\n",
				 cur_frame_end_offset<<1, lo_status, hi_status, lo_cnt, hi_cnt,
				 count, status);
		cur_frame_end[-4] = status;
		cur_frame_end[-3] = next_frame_end_offset;
		cur_frame_end[-2] = count;
		next_frame_end_offset = cur_frame_end_offset;
		cur_frame_end_offset -= ((count + 1)>>1) + 3;
		if (cur_frame_end_offset < 0)
		  cur_frame_end_offset += RX_BUF_SIZE/2;
	};

	/* Now step  forward through the list. */
	do {
		ushort *this_rfp_ptr = zn.rx_start + next_frame_end_offset;
		int status = this_rfp_ptr[-4];
		int pkt_len = this_rfp_ptr[-2];
	  
		if (znet_debug > 5)
		  printk(KERN_DEBUG "Looking at trailer ending at %04x status %04x length %03x"
				 " next %04x.\n", next_frame_end_offset<<1, status, pkt_len,
				 this_rfp_ptr[-3]<<1);
		/* Once again we must assume that the i82586 docs apply. */
		if ( ! (status & 0x2000)) {				/* There was an error. */
			lp->stats.rx_errors++;
			if (status & 0x0800) lp->stats.rx_crc_errors++;
			if (status & 0x0400) lp->stats.rx_frame_errors++;
			if (status & 0x0200) lp->stats.rx_over_errors++; /* Wrong. */
			if (status & 0x0100) lp->stats.rx_fifo_errors++;
			if (status & 0x0080) lp->stats.rx_length_errors++;
		} else if (pkt_len > 1536) {
			lp->stats.rx_length_errors++;
		} else {
			/* Malloc up new buffer. */
			struct sk_buff *skb;

			skb = dev_alloc_skb(pkt_len);
			if (skb == NULL) {
				if (znet_debug)
				  printk(KERN_WARNING "%s: Memory squeeze, dropping packet.\n", dev->name);
				lp->stats.rx_dropped++;
				break;
			}
			skb->dev = dev;

			if (&zn.rx_cur[(pkt_len+1)>>1] > zn.rx_end) {
				int semi_cnt = (zn.rx_end - zn.rx_cur)<<1;
				memcpy(skb_put(skb,semi_cnt), zn.rx_cur, semi_cnt);
				memcpy(skb_put(skb,pkt_len-semi_cnt), zn.rx_start,
					   pkt_len - semi_cnt);
			} else {
				memcpy(skb_put(skb,pkt_len), zn.rx_cur, pkt_len);
				if (znet_debug > 6) {
					unsigned int *packet = (unsigned int *) skb->data;
					printk(KERN_DEBUG "Packet data is %08x %08x %08x %08x.\n", packet[0],
						   packet[1], packet[2], packet[3]);
				}
		  }
		  skb->protocol=eth_type_trans(skb,dev);
		  netif_rx(skb);
		  lp->stats.rx_packets++;
		}
		zn.rx_cur = this_rfp_ptr;
		if (zn.rx_cur >= zn.rx_end)
			zn.rx_cur -= RX_BUF_SIZE/2;
		update_stop_hit(ioaddr, (zn.rx_cur - zn.rx_start)<<1);
		next_frame_end_offset = this_rfp_ptr[-3];
		if (next_frame_end_offset == 0)		/* Read all the frames? */
			break;			/* Done for now */
		this_rfp_ptr = zn.rx_start + next_frame_end_offset;
	} while (--boguscount);

	/* If any worth-while packets have been received, dev_rint()
	   has done a mark_bh(INET_BH) for us and will work on them
	   when we get to the bottom-half routine. */
	return;
}

/* The inverse routine to znet_open(). */
static int znet_close(struct net_device *dev)
{
	unsigned long flags;
	int ioaddr = dev->base_addr;

	netif_stop_queue (dev);

	outb(CMD0_RESET, ioaddr);			/* CMD0_RESET */

	flags=claim_dma_lock();
	disable_dma(zn.rx_dma);
	disable_dma(zn.tx_dma);
	release_dma_lock(flags);

	free_irq(dev->irq, dev);

	if (znet_debug > 1)
		printk(KERN_DEBUG "%s: Shutting down ethercard.\n", dev->name);
	/* Turn off transceiver power. */
	outb(0x10, 0xe6);					/* Select LAN control register */
	outb(inb(0xe7) & ~0x84, 0xe7);		/* Turn on LAN power (bit 2). */

	return 0;
}

/* Get the current statistics.	This may be called with the card open or
   closed. */
static struct net_device_stats *net_get_stats(struct net_device *dev)
{
		struct net_local *lp = (struct net_local *)dev->priv;

		return &lp->stats;
}

/* Set or clear the multicast filter for this adaptor.
   As a side effect this routine must also initialize the device parameters.
   This is taken advantage of in open().

   N.B. that we change i593_init[] in place.  This (properly) makes the
   mode change persistent, but must be changed if this code is moved to
   a multiple adaptor environment.
 */
static void set_multicast_list(struct net_device *dev)
{
	short ioaddr = dev->base_addr;

	if (dev->flags&IFF_PROMISC) {
		/* Enable promiscuous mode */
		i593_init[7] &= ~3;		i593_init[7] |= 1;
		i593_init[13] &= ~8;	i593_init[13] |= 8;
	} else if (dev->mc_list || (dev->flags&IFF_ALLMULTI)) {
		/* Enable accept-all-multicast mode */
		i593_init[7] &= ~3;		i593_init[7] |= 0;
		i593_init[13] &= ~8;	i593_init[13] |= 8;
	} else {					/* Enable normal mode. */
		i593_init[7] &= ~3;		i593_init[7] |= 0;
		i593_init[13] &= ~8;	i593_init[13] |= 0;
	}
	*zn.tx_cur++ = sizeof(i593_init);
	memcpy(zn.tx_cur, i593_init, sizeof(i593_init));
	zn.tx_cur += sizeof(i593_init)/2;
	outb(CMD0_CONFIGURE+CMD0_CHNL_1, ioaddr);
#ifdef not_tested
	if (num_addrs > 0) {
		int addrs_len = 6*num_addrs;
		*zn.tx_cur++ = addrs_len;
		memcpy(zn.tx_cur, addrs, addrs_len);
		outb(CMD0_MULTICAST_LIST+CMD0_CHNL_1, ioaddr);
		zn.tx_cur += addrs_len>>1;
	}
#endif
}

void show_dma(void)
{
	unsigned long flags;
	short dma_port = ((zn.tx_dma&3)<<2) + IO_DMA2_BASE;
	unsigned addr = inb(dma_port);
	addr |= inb(dma_port) << 8;

	flags=claim_dma_lock();
	printk("Addr: %04x cnt:%3x...", addr<<1, get_dma_residue(zn.tx_dma));
	release_dma_lock(flags);
}

/* Initialize the hardware.  We have to do this when the board is open()ed
   or when we come out of suspend mode. */
static void hardware_init(struct net_device *dev)
{
	unsigned long flags;
	short ioaddr = dev->base_addr;

	zn.rx_cur = zn.rx_start;
	zn.tx_cur = zn.tx_start;

	/* Reset the chip, and start it up. */
	outb(CMD0_RESET, ioaddr);

	flags=claim_dma_lock();
	disable_dma(zn.rx_dma); 		/* reset by an interrupting task. */
	clear_dma_ff(zn.rx_dma);
	set_dma_mode(zn.rx_dma, DMA_RX_MODE);
	set_dma_addr(zn.rx_dma, (unsigned int) zn.rx_start);
	set_dma_count(zn.rx_dma, RX_BUF_SIZE);
	enable_dma(zn.rx_dma);
	/* Now set up the Tx channel. */
	disable_dma(zn.tx_dma);
	clear_dma_ff(zn.tx_dma);
	set_dma_mode(zn.tx_dma, DMA_TX_MODE);
	set_dma_addr(zn.tx_dma, (unsigned int) zn.tx_start);
	set_dma_count(zn.tx_dma, zn.tx_buf_len<<1);
	enable_dma(zn.tx_dma);
	release_dma_lock(flags);
	
	if (znet_debug > 1)
	  printk(KERN_DEBUG "%s: Initializing the i82593, tx buf %p... ", dev->name,
			 zn.tx_start);
	/* Do an empty configure command, just like the Crynwr driver.  This
	   resets to chip to its default values. */
	*zn.tx_cur++ = 0;
	*zn.tx_cur++ = 0;
	printk("stat:%02x ", inb(ioaddr)); show_dma();
	outb(CMD0_CONFIGURE+CMD0_CHNL_1, ioaddr);
	*zn.tx_cur++ = sizeof(i593_init);
	memcpy(zn.tx_cur, i593_init, sizeof(i593_init));
	zn.tx_cur += sizeof(i593_init)/2;
	printk("stat:%02x ", inb(ioaddr)); show_dma();
	outb(CMD0_CONFIGURE+CMD0_CHNL_1, ioaddr);
	*zn.tx_cur++ = 6;
	memcpy(zn.tx_cur, dev->dev_addr, 6);
	zn.tx_cur += 3;
	printk("stat:%02x ", inb(ioaddr)); show_dma();
	outb(CMD0_IA_SETUP + CMD0_CHNL_1, ioaddr);
	printk("stat:%02x ", inb(ioaddr)); show_dma();

	update_stop_hit(ioaddr, 8192);
	if (znet_debug > 1)  printk("enabling Rx.\n");
	outb(CMD0_Rx_ENABLE+CMD0_CHNL_0, ioaddr);
	netif_start_queue (dev);
}

static void update_stop_hit(short ioaddr, unsigned short rx_stop_offset)
{
	outb(CMD0_PORT_1, ioaddr);
	if (znet_debug > 5)
	  printk(KERN_DEBUG "Updating stop hit with value %02x.\n",
			 (rx_stop_offset >> 6) | 0x80);
	outb((rx_stop_offset >> 6) | 0x80, ioaddr);
	outb(CMD1_PORT_0, ioaddr);
}

/*
 * Local variables:
 *  compile-command: "gcc -D__KERNEL__ -I/usr/src/linux/net/inet -Wall -Wstrict-prototypes -O6 -m486 -c znet.c"
 *  version-control: t
 *  kept-new-versions: 5
 *  c-indent-level: 4
 *  tab-width: 4
 * End:
 */