board/MAI/AmigaOneG3SE/enet.c

/*
 * (C) Copyright 2002
 * Adam Kowalczyk, ACK Software Controls Inc. akowalczyk@cogeco.ca
 *
 * Some portions taken from 3c59x.c Written 1996-1999 by Donald Becker.
 *
 * Outline of the program based on eepro100.c which is
 *
 * (C) Copyright 2002
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>
#include <malloc.h>
#include <net.h>
#include <netdev.h>
#include <asm/io.h>
#include <pci.h>

#include "articiaS.h"
#include "memio.h"

/* 3Com Ethernet PCI definitions*/

/* #define PCI_VENDOR_ID_3COM		0x10B7 */
#define PCI_DEVICE_ID_3COM_3C905C	0x9200

/* 3Com Commands, top 5 bits are command and bottom 11 bits are parameters */

#define TotalReset		(0<<11)
#define SelectWindow		(1<<11)
#define StartCoax		(2<<11)
#define RxDisable		(3<<11)
#define RxEnable		(4<<11)
#define RxReset			(5<<11)
#define UpStall			(6<<11)
#define UpUnstall		(6<<11)+1
#define DownStall		(6<<11)+2
#define DownUnstall		(6<<11)+3
#define RxDiscard		(8<<11)
#define TxEnable		(9<<11)
#define TxDisable		(10<<11)
#define TxReset			(11<<11)
#define FakeIntr		(12<<11)
#define AckIntr			(13<<11)
#define SetIntrEnb		(14<<11)
#define SetStatusEnb		(15<<11)
#define SetRxFilter		(16<<11)
#define SetRxThreshold		(17<<11)
#define SetTxThreshold		(18<<11)
#define SetTxStart		(19<<11)
#define StartDMAUp		(20<<11)
#define StartDMADown		(20<<11)+1
#define StatsEnable		(21<<11)
#define StatsDisable		(22<<11)
#define StopCoax		(23<<11)
#define SetFilterBit		(25<<11)

/* The SetRxFilter command accepts the following classes */

#define RxStation		1
#define RxMulticast		2
#define RxBroadcast		4
#define RxProm			8

/* 3Com status word defnitions */

#define IntLatch		0x0001
#define HostError		0x0002
#define TxComplete		0x0004
#define TxAvailable		0x0008
#define RxComplete		0x0010
#define RxEarly			0x0020
#define IntReq			0x0040
#define StatsFull		0x0080
#define DMADone			(1<<8)
#define DownComplete		(1<<9)
#define UpComplete		(1<<10)
#define DMAInProgress		(1<<11)		/* DMA controller is still busy.*/
#define CmdInProgress		(1<<12)		/* EL3_CMD is still busy.*/

/* Polling Registers */

#define DnPoll			0x2d
#define UpPoll			0x3d

/* Register window 0 offets */

#define Wn0EepromCmd		10		/* Window 0: EEPROM command register. */
#define Wn0EepromData		12		/* Window 0: EEPROM results register. */
#define IntrStatus		0x0E		/* Valid in all windows. */

/* Register window 0 EEPROM bits */

#define EEPROM_Read		0x80
#define EEPROM_WRITE		0x40
#define EEPROM_ERASE		0xC0
#define EEPROM_EWENB		0x30		/* Enable erasing/writing for 10 msec. */
#define EEPROM_EWDIS		0x00		/* Disable EWENB before 10 msec timeout. */

/* EEPROM locations. */

#define PhysAddr01		0
#define PhysAddr23		1
#define PhysAddr45		2
#define ModelID			3
#define EtherLink3ID		7
#define IFXcvrIO		8
#define IRQLine			9
#define NodeAddr01		10
#define NodeAddr23		11
#define NodeAddr45		12
#define DriverTune		13
#define Checksum		15

/* Register window 1 offsets, the window used in normal operation */

#define TX_FIFO			0x10
#define RX_FIFOa		0x10
#define RxErrors		0x14
#define RxStatus		0x18
#define Timer			0x1A
#define TxStatus		0x1B
#define TxFree			0x1C		/* Remaining free bytes in Tx buffer. */

/* Register Window 2 */

#define Wn2_ResetOptions	12

/* Register Window 3: MAC/config bits */

#define Wn3_Config		0		/* Internal Configuration */
#define Wn3_MAC_Ctrl		6
#define Wn3_Options		8

#define BFEXT(value, offset, bitcount)					\
	((((unsigned long)(value)) >> (offset)) & ((1 << (bitcount)) - 1))

#define BFINS(lhs, rhs, offset, bitcount)					\
	(((lhs) & ~((((1 << (bitcount)) - 1)) << (offset))) |			\
	(((rhs) & ((1 << (bitcount)) - 1)) << (offset)))

#define RAM_SIZE(v)		BFEXT(v, 0, 3)
#define RAM_WIDTH(v)		BFEXT(v, 3, 1)
#define RAM_SPEED(v)		BFEXT(v, 4, 2)
#define ROM_SIZE(v)		BFEXT(v, 6, 2)
#define RAM_SPLIT(v)		BFEXT(v, 16, 2)
#define XCVR(v)			BFEXT(v, 20, 4)
#define AUTOSELECT(v)		BFEXT(v, 24, 1)

/* Register Window 4: Xcvr/media bits */

#define Wn4_FIFODiag		4
#define Wn4_NetDiag		6
#define Wn4_PhysicalMgmt	8
#define Wn4_Media		10

#define Media_SQE		0x0008		/* Enable SQE error counting for AUI. */
#define Media_10TP		0x00C0		/* Enable link beat and jabber for 10baseT. */
#define Media_Lnk		0x0080		/* Enable just link beat for 100TX/100FX. */
#define Media_LnkBeat		0x0800

/* Register Window 7: Bus Master control */

#define Wn7_MasterAddr		0
#define Wn7_MasterLen		6
#define Wn7_MasterStatus	12

/* Boomerang bus master control registers. */

#define PktStatus		0x20
#define DownListPtr		0x24
#define FragAddr		0x28
#define FragLen			0x2c
#define TxFreeThreshold	0x2f
#define UpPktStatus		0x30
#define UpListPtr		0x38

/* The Rx and Tx descriptor lists. */

#define LAST_FRAG	0x80000000		/* Last Addr/Len pair in descriptor. */
#define DN_COMPLETE	0x00010000		/* This packet has been downloaded */

struct rx_desc_3com {
	u32 next;				/* Last entry points to 0		*/
	u32 status;				/* FSH -> Frame Start Header		*/
	u32 addr;				/* Up to 63 addr/len pairs possible	*/
	u32 length;				/* Set LAST_FRAG to indicate last pair	*/
};

/* Values for the Rx status entry. */

#define RxDComplete		0x00008000
#define RxDError		0x4000
#define IPChksumErr		(1<<25)
#define TCPChksumErr		(1<<26)
#define UDPChksumErr		(1<<27)
#define IPChksumValid		(1<<29)
#define TCPChksumValid		(1<<30)
#define UDPChksumValid		(1<<31)

struct tx_desc_3com {
	u32 next;				/* Last entry points to 0		*/
	u32 status;				/* bits 0:12 length, others see below	*/
	u32 addr;
	u32 length;
};

/* Values for the Tx status entry. */

#define CRCDisable		0x2000
#define TxDComplete		0x8000
#define AddIPChksum		0x02000000
#define AddTCPChksum		0x04000000
#define AddUDPChksum		0x08000000
#define TxIntrUploaded		0x80000000	/* IRQ when in FIFO, but maybe not sent. */

/* XCVR Types */

#define XCVR_10baseT		0
#define XCVR_AUI		1
#define XCVR_10baseTOnly	2
#define XCVR_10base2		3
#define XCVR_100baseTx		4
#define XCVR_100baseFx		5
#define XCVR_MII		6
#define XCVR_NWAY		8
#define XCVR_ExtMII		9
#define XCVR_Default		10		/* I don't think this is correct -> should have been 0x10 if Auto Negotiate */

struct descriptor {				/* A generic descriptor. */
	u32 next;				/* Last entry points to 0		*/
	u32 status;				/* FSH -> Frame Start Header		*/
	u32 addr;				/* Up to 63 addr/len pairs possible	*/
	u32 length;				/* Set LAST_FRAG to indicate last pair	*/
};

/* Misc. definitions */

#define NUM_RX_DESC		PKTBUFSRX * 10
#define NUM_TX_DESC		1		/* Number of TX descriptors   */

#define TOUT_LOOP		1000000

#define ETH_ALEN		6

#define EL3WINDOW(dev, win_num) ETH_OUTW(dev, SelectWindow + (win_num), EL3_CMD)
#define EL3_CMD 0x0e
#define EL3_STATUS 0x0e


#undef ETH_DEBUG

#ifdef ETH_DEBUG
#define PRINTF(fmt,args...)	printf (fmt ,##args)
#else
#define PRINTF(fmt,args...)
#endif


static struct rx_desc_3com *rx_ring;		/* RX descriptor ring		*/
static struct tx_desc_3com *tx_ring;		/* TX descriptor ring		*/
static u8 rx_buffer[NUM_RX_DESC][PKTSIZE_ALIGN];/* storage for the incoming messages	*/
static int rx_next = 0;				/* RX descriptor ring pointer		*/
static int tx_next = 0;				/* TX descriptor ring pointer		*/
static int tx_threshold;

static void  init_rx_ring(struct eth_device* dev);
static void  purge_tx_ring(struct eth_device* dev);

static void  read_hw_addr(struct eth_device* dev, bd_t * bis);

static int eth_3com_init(struct eth_device* dev, bd_t *bis);
static int eth_3com_send(struct eth_device* dev, volatile void *packet, int length);
static int eth_3com_recv(struct eth_device* dev);
static void eth_3com_halt(struct eth_device* dev);

#define io_to_phys(a)	pci_io_to_phys((pci_dev_t)dev->priv, a)
#define phys_to_io(a)	pci_phys_to_io((pci_dev_t)dev->priv, a)
#define mem_to_phys(a)	pci_mem_to_phys((pci_dev_t)dev->priv, a)
#define phys_to_mem(a)	pci_phys_to_mem((pci_dev_t)dev->priv, a)

static inline int ETH_INL(struct eth_device* dev, u_long addr)
{
	__asm__ volatile ("eieio");
	return le32_to_cpu(*(volatile u32 *)io_to_phys(addr + dev->iobase));
}

static inline int ETH_INW(struct eth_device* dev, u_long addr)
{
	__asm__ volatile ("eieio");
	return le16_to_cpu(*(volatile u16 *)io_to_phys(addr + dev->iobase));
}

static inline int ETH_INB(struct eth_device* dev, u_long addr)
{
	__asm__ volatile ("eieio");
	return *(volatile u8 *)io_to_phys(addr + dev->iobase);
}

static inline void ETH_OUTB(struct eth_device* dev, int command, u_long addr)
{
	*(volatile u8 *)io_to_phys(addr + dev->iobase) = command;
	__asm__ volatile ("eieio");
}

static inline void ETH_OUTW(struct eth_device* dev, int command, u_long addr)
{
	*(volatile u16 *)io_to_phys(addr + dev->iobase) = cpu_to_le16(command);
	__asm__ volatile ("eieio");
}

static inline void ETH_OUTL(struct eth_device* dev, int command, u_long addr)
{
	*(volatile u32 *)io_to_phys(addr + dev->iobase) = cpu_to_le32(command);
	__asm__ volatile ("eieio");
}

static inline int ETH_STATUS(struct eth_device* dev)
{
	__asm__ volatile ("eieio");
	return le16_to_cpu(*(volatile u16 *)io_to_phys(EL3_STATUS + dev->iobase));
}

static inline void ETH_CMD(struct eth_device* dev, int command)
{
	*(volatile u16 *)io_to_phys(EL3_CMD + dev->iobase) = cpu_to_le16(command);
	__asm__ volatile ("eieio");
}

/* Command register is always in the same spot in all the register windows */
/* This function issues a command and waits for it so complete by checking the CmdInProgress bit */

static int issue_and_wait(struct eth_device* dev, int command)
{

	int i, status;

	ETH_CMD(dev, command);
	for (i = 0; i < 2000; i++) {
		status = ETH_STATUS(dev);
		/*printf ("Issue: status 0x%4x.\n", status); */
		if (!(status & CmdInProgress))
			return 1;
	}

	/* OK, that didn't work.  Do it the slow way.  One second */
	for (i = 0; i < 100000; i++) {
		status = ETH_STATUS(dev);
		/*printf ("Issue: status 0x%4x.\n", status); */
			return 1;
		udelay(10);
	}
	PRINTF("Ethernet command: 0x%4x did not complete! Status: 0x%4x\n", command, ETH_STATUS(dev) );
	return 0;
}

/* Determine network media type and set up 3com accordingly	      */
/* I think I'm going to start with something known first like 10baseT */

static int auto_negotiate (struct eth_device *dev)
{
	int i;

	EL3WINDOW (dev, 1);

	/* Wait for Auto negotiation to complete */
	for (i = 0; i <= 1000; i++) {
		if (ETH_INW (dev, 2) & 0x04)
			break;
		udelay (100);

		if (i == 1000) {
			PRINTF ("Error: Auto negotiation failed\n");
			return 0;
		}
	}


	return 1;
}

void eth_interrupt (struct eth_device *dev)
{
	u16 status = ETH_STATUS (dev);

	printf ("eth0: status = 0x%04x\n", status);

	if (!(status & IntLatch))
		return;

	if (status & (1 << 6)) {
		ETH_CMD (dev, AckIntr | (1 << 6));
		printf ("Acknowledged Interrupt command\n");
	}

	if (status & DownComplete) {
		ETH_CMD (dev, AckIntr | DownComplete);
		printf ("Acknowledged DownComplete\n");
	}

	if (status & UpComplete) {
		ETH_CMD (dev, AckIntr | UpComplete);
		printf ("Acknowledged UpComplete\n");
	}

	ETH_CMD (dev, AckIntr | IntLatch);
	printf ("Acknowledged IntLatch\n");
}

int eth_3com_initialize (bd_t * bis)
{
	u32 eth_iobase = 0, status;
	int card_number = 0, ret;
	struct eth_device *dev;
	pci_dev_t devno;
	char *s;

	s = getenv ("3com_base");

	/* Find ethernet controller on the PCI bus */

	if ((devno =
	     pci_find_device (PCI_VENDOR_ID_3COM, PCI_DEVICE_ID_3COM_3C905C,
			      0)) < 0) {
		PRINTF ("Error: Cannot find the ethernet device on the PCI bus\n");
		goto Done;
	}

	if (s) {
		unsigned long base = atoi (s);

		pci_write_config_dword (devno, PCI_BASE_ADDRESS_0,
					base | 0x01);
	}

	ret = pci_read_config_dword (devno, PCI_BASE_ADDRESS_0, &eth_iobase);
	eth_iobase &= ~0xf;

	PRINTF ("eth: 3Com Found at Address: 0x%x\n", eth_iobase);

	pci_write_config_dword (devno, PCI_COMMAND,
				PCI_COMMAND_IO | PCI_COMMAND_MEMORY |
				PCI_COMMAND_MASTER);

	/* Check if I/O accesses and Bus Mastering are enabled */

	ret = pci_read_config_dword (devno, PCI_COMMAND, &status);

	if (!(status & PCI_COMMAND_IO)) {
		printf ("Error: Cannot enable IO access.\n");
		goto Done;
	}

	if (!(status & PCI_COMMAND_MEMORY)) {
		printf ("Error: Cannot enable MEMORY access.\n");
		goto Done;
	}

	if (!(status & PCI_COMMAND_MASTER)) {
		printf ("Error: Cannot enable Bus Mastering.\n");
		goto Done;
	}

	dev = (struct eth_device *) malloc (sizeof (*dev));	/*struct eth_device)); */

	sprintf (dev->name, "3Com 3c920c#%d", card_number);
	dev->iobase = eth_iobase;
	dev->priv = (void *) devno;
	dev->init = eth_3com_init;
	dev->halt = eth_3com_halt;
	dev->send = eth_3com_send;
	dev->recv = eth_3com_recv;

	eth_register (dev);

/*	{ */
/*	    char interrupt; */
/*	    devno = pci_find_device(PCI_VENDOR_ID_3COM, PCI_DEVICE_ID_3COM_3C905C, 0); */
/*	    pci_read_config_byte(devno, PCI_INTERRUPT_LINE, &interrupt); */

/*	    printf("Installing eth0 interrupt handler to %d\n", interrupt); */
/*	    irq_install_handler(interrupt, eth_interrupt, dev); */
/*	} */

	card_number++;

	/* Set the latency timer for value */
	s = getenv ("3com_latency");
	if (s) {
		ret = pci_write_config_byte (devno, PCI_LATENCY_TIMER,
					     (unsigned char) atoi (s));
	} else
		ret = pci_write_config_byte (devno, PCI_LATENCY_TIMER, 0x0a);

	read_hw_addr (dev, bis);	/* get the MAC address from Window 2 */

	/* Reset the ethernet controller */

	PRINTF ("Issuing reset command....\n");
	if (!issue_and_wait (dev, TotalReset)) {
		printf ("Error: Cannot reset ethernet controller.\n");
		goto Done;
	} else
		PRINTF ("Ethernet controller reset.\n");

	/* allocate memory for rx and tx rings */

	if (!(rx_ring = memalign (sizeof (struct rx_desc_3com) * NUM_RX_DESC, 16))) {
		PRINTF ("Cannot allocate memory for RX_RING.....\n");
		goto Done;
	}

	if (!(tx_ring = memalign (sizeof (struct tx_desc_3com) * NUM_TX_DESC, 16))) {
		PRINTF ("Cannot allocate memory for TX_RING.....\n");
		goto Done;
	}

Done:
	return status;
}


static int eth_3com_init (struct eth_device *dev, bd_t * bis)
{
	int i, status = 0;
	int tx_cur, loop;
	u16 status_enable, intr_enable;
	struct descriptor *ias_cmd;

	/* Determine what type of network the machine is connected to   */
	/* presently drops the connect to 10Mbps                        */

	if (!auto_negotiate (dev)) {
		printf ("Error: Cannot determine network media.\n");
		goto Done;
	}

	issue_and_wait (dev, TxReset);
	issue_and_wait (dev, RxReset | 0x04);

	/* Switch to register set 7 for normal use. */
	EL3WINDOW (dev, 7);

	/* Initialize Rx and Tx rings */

	init_rx_ring (dev);
	purge_tx_ring (dev);

	ETH_CMD (dev, SetRxFilter | RxStation | RxBroadcast | RxProm);

	issue_and_wait (dev, SetTxStart | 0x07ff);

	/* Below sets which indication bits to be seen. */

	status_enable =
		SetStatusEnb | HostError | DownComplete | UpComplete | (1 <<
									6);
	ETH_CMD (dev, status_enable);

	/* Below sets no bits are to cause an interrupt since this is just polling */

	intr_enable = SetIntrEnb;
/*	intr_enable = SetIntrEnb | (1<<9) | (1<<10) | (1<<6); */
	ETH_CMD (dev, intr_enable);
	ETH_OUTB (dev, 127, UpPoll);

	/* Ack all pending events, and set active indicator mask */

	ETH_CMD (dev, AckIntr | IntLatch | TxAvailable | RxEarly | IntReq);
	ETH_CMD (dev, intr_enable);

	/* Tell the adapter where the RX ring is located */

	issue_and_wait (dev, UpStall);	/* Stall and set the UplistPtr          */
	ETH_OUTL (dev, (u32) & rx_ring[rx_next], UpListPtr);
	ETH_CMD (dev, RxEnable);	/* Enable the receiver.         */
	issue_and_wait (dev, UpUnstall);

	/* Send the Individual Address Setup frame */

	tx_cur = tx_next;
	tx_next = ((tx_next + 1) % NUM_TX_DESC);

	ias_cmd = (struct descriptor *) &tx_ring[tx_cur];
	ias_cmd->status = cpu_to_le32 (1 << 31);	/* set DnIndicate bit.                  */
	ias_cmd->next = 0;
	ias_cmd->addr = cpu_to_le32 ((u32) dev->enetaddr);
	ias_cmd->length = cpu_to_le32 (6 | LAST_FRAG);

	/* Tell the adapter where the TX ring is located */

	ETH_CMD (dev, TxEnable);	/* Enable transmitter.                  */
	issue_and_wait (dev, DownStall);	/* Stall and set the DownListPtr.       */
	ETH_OUTL (dev, (u32) & tx_ring[tx_cur], DownListPtr);
	issue_and_wait (dev, DownUnstall);
	for (i = 0; !(ETH_STATUS (dev) & DownComplete); i++) {
		if (i >= TOUT_LOOP) {
			PRINTF ("TX Ring status (Init):	0x%4x\n",
				le32_to_cpu (tx_ring[tx_cur].status));
			PRINTF ("ETH_STATUS: 0x%x\n", ETH_STATUS (dev));
			goto Done;
		}
	}
	if (ETH_STATUS (dev) & DownComplete) {	/* If DownLoad Complete ACK the bit       */
		ETH_CMD (dev, AckIntr | DownComplete);	/* acknowledge the indication bit       */
		issue_and_wait (dev, DownStall);	/* stall and clear DownListPtr          */
		ETH_OUTL (dev, 0, DownListPtr);
		issue_and_wait (dev, DownUnstall);
	}
	status = 1;
Done:
	return status;
}

int eth_3com_send (struct eth_device *dev, volatile void *packet, int length)
{
	int i, status = 0;
	int tx_cur;

	if (length <= 0) {
		PRINTF ("eth: bad packet size: %d\n", length);
		goto Done;
	}

	tx_cur = tx_next;
	tx_next = (tx_next + 1) % NUM_TX_DESC;

	tx_ring[tx_cur].status = cpu_to_le32 (1 << 31);	/* set DnIndicate bit                   */
	tx_ring[tx_cur].next = 0;
	tx_ring[tx_cur].addr = cpu_to_le32 (((u32) packet));
	tx_ring[tx_cur].length = cpu_to_le32 (length | LAST_FRAG);

	/* Send the packet */

	issue_and_wait (dev, DownStall);	/* stall and set the DownListPtr        */
	ETH_OUTL (dev, (u32) & tx_ring[tx_cur], DownListPtr);
	issue_and_wait (dev, DownUnstall);

	for (i = 0; !(ETH_STATUS (dev) & DownComplete); i++) {
		if (i >= TOUT_LOOP) {
			PRINTF ("TX Ring status (send): 0x%4x\n",
				le32_to_cpu (tx_ring[tx_cur].status));
			goto Done;
		}
	}
	if (ETH_STATUS (dev) & DownComplete) {	/* If DownLoad Complete ACK the bit       */
		ETH_CMD (dev, AckIntr | DownComplete);	/* acknowledge the indication bit       */
		issue_and_wait (dev, DownStall);	/* stall and clear DownListPtr          */
		ETH_OUTL (dev, 0, DownListPtr);
		issue_and_wait (dev, DownUnstall);
	}
	status = 1;
Done:
	return status;
}

void PrintPacket (uchar * packet, int length)
{
	int loop;
	uchar *ptr;

	printf ("Printing packet of length %x.\n\n", length);
	ptr = packet;
	for (loop = 1; loop <= length; loop++) {
		printf ("%2x ", *ptr++);
		if ((loop % 40) == 0)
			printf ("\n");
	}
}

int eth_3com_recv (struct eth_device *dev)
{
	u16 stat = 0;
	u32 status;
	int rx_prev, length = 0;

	while (!(ETH_STATUS (dev) & UpComplete))	/* wait on receipt of packet        */
		;

	status = le32_to_cpu (rx_ring[rx_next].status);	/* packet status                */

	while (status & (1 << 15)) {
		/* A packet has been received */

		if (status & (1 << 15)) {
			/* A valid frame received  */

			length = le32_to_cpu (rx_ring[rx_next].status) & 0x1fff;	/* length is in bits 0 - 12     */

			/* Pass the packet up to the protocol layers */

			NetReceive ((uchar *)
				    le32_to_cpu (rx_ring[rx_next].addr),
				    length);
			rx_ring[rx_next].status = 0;	/* clear the status word        */
			ETH_CMD (dev, AckIntr | UpComplete);
			issue_and_wait (dev, UpUnstall);
		} else if (stat & HostError) {
			/* There was an error */

			printf ("Rx error status:  0x%4x\n", stat);
			init_rx_ring (dev);
			goto Done;
		}

		rx_prev = rx_next;
		rx_next = (rx_next + 1) % NUM_RX_DESC;
		stat = ETH_STATUS (dev);	/* register status      */
		status = le32_to_cpu (rx_ring[rx_next].status);	/* packet status        */
	}
Done:
	return length;
}

void eth_3com_halt (struct eth_device *dev)
{
	if (!(dev->iobase)) {
		goto Done;
	}

	issue_and_wait (dev, DownStall);	/* shut down transmit and receive */
	issue_and_wait (dev, UpStall);
	issue_and_wait (dev, RxDisable);
	issue_and_wait (dev, TxDisable);

/*	free(tx_ring);				/###* release memory allocated to the DPD and UPD rings */
/*	free(rx_ring); */

Done:
	return;
}

static void init_rx_ring (struct eth_device *dev)
{
	int i;

	PRINTF ("Initializing rx_ring. rx_buffer = %p\n", rx_buffer);
	issue_and_wait (dev, UpStall);

	for (i = 0; i < NUM_RX_DESC; i++) {
		rx_ring[i].next =
			cpu_to_le32 (((u32) &
				      rx_ring[(i + 1) % NUM_RX_DESC]));
		rx_ring[i].status = 0;
		rx_ring[i].addr = cpu_to_le32 (((u32) & rx_buffer[i][0]));
		rx_ring[i].length = cpu_to_le32 (PKTSIZE_ALIGN | LAST_FRAG);
	}
	rx_next = 0;
}

static void purge_tx_ring (struct eth_device *dev)
{
	int i;

	PRINTF ("Purging tx_ring.\n");

	tx_next = 0;

	for (i = 0; i < NUM_TX_DESC; i++) {
		tx_ring[i].next = 0;
		tx_ring[i].status = 0;
		tx_ring[i].addr = 0;
		tx_ring[i].length = 0;
	}
}

static void read_hw_addr (struct eth_device *dev, bd_t * bis)
{
	u8 hw_addr[ETH_ALEN];
	unsigned int eeprom[0x40];
	unsigned int checksum = 0;
	int i, j, timer;

	/* First, try the env ... if that works, we're all done! */
	if (eth_getenv_enetaddr("ethaddr", hw_addr))
		goto Done;

	/* Read the station address from the EEPROM. */

	EL3WINDOW (dev, 0);
	for (i = 0; i < 0x40; i++) {
		ETH_OUTW (dev, EEPROM_Read + i, Wn0EepromCmd);
		/* Pause for at least 162 us. for the read to take place. */
		for (timer = 10; timer >= 0; timer--) {
			udelay (162);
			if ((ETH_INW (dev, Wn0EepromCmd) & 0x8000) == 0)
				break;
		}
		eeprom[i] = ETH_INW (dev, Wn0EepromData);
	}

	/* Checksum calculation.  I'm not sure about this part and there seems to be a bug on the 3com side of things */

	for (i = 0; i < 0x21; i++)
		checksum ^= eeprom[i];
	checksum = (checksum ^ (checksum >> 8)) & 0xff;

	if (checksum != 0xbb)
		printf (" *** INVALID EEPROM CHECKSUM %4.4x *** \n",
			checksum);

	for (i = 0, j = 0; i < 3; i++) {
		hw_addr[j++] = (u8) ((eeprom[i + 10] >> 8) & 0xff);
		hw_addr[j++] = (u8) (eeprom[i + 10] & 0xff);
	}

	/*  MAC Address is in window 2, write value from EEPROM to window 2 */

	EL3WINDOW (dev, 2);
	for (i = 0; i < 6; i++)
		ETH_OUTB (dev, hw_addr[i], i);

	for (j = 0; j < ETH_ALEN; j += 2) {
		hw_addr[j] = (u8) (ETH_INW (dev, j) & 0xff);
		hw_addr[j + 1] = (u8) ((ETH_INW (dev, j) >> 8) & 0xff);
	}

	/* Save the result in the environment */
	eth_setenv_enetaddr("ethaddr", hw_addr);

Done:
	memcpy(dev->enetaddr, hw_addr, 6);
	return;
}