u-boot-megous/drivers/net/ne2000_base.c

/*
Ported to U-Boot by Christian Pellegrin <chri@ascensit.com>

Based on sources from the Linux kernel (pcnet_cs.c, 8390.h) and
eCOS(if_dp83902a.c, if_dp83902a.h). Both of these 2 wonderful world
are GPL, so this is, of course, GPL.

==========================================================================

dev/if_dp83902a.c

Ethernet device driver for NS DP83902a ethernet controller

==========================================================================
####ECOSGPLCOPYRIGHTBEGIN####
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Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

eCos is free software; you can redistribute it and/or modify it under
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eCos 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.

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with eCos; if not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

As a special exception, if other files instantiate templates or use macros
or inline functions from this file, or you compile this file and link it
with other works to produce a work based on this file, this file does not
by itself cause the resulting work to be covered by the GNU General Public
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this file might be covered by the GNU General Public License.

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-------------------------------------------
####ECOSGPLCOPYRIGHTEND####
####BSDCOPYRIGHTBEGIN####

-------------------------------------------

Portions of this software may have been derived from OpenBSD or other sources,
and are covered by the appropriate copyright disclaimers included herein.

-------------------------------------------

####BSDCOPYRIGHTEND####
==========================================================================
#####DESCRIPTIONBEGIN####

Author(s):	gthomas
Contributors:	gthomas, jskov, rsandifo
Date:		2001-06-13
Purpose:
Description:

FIXME:		Will fail if pinged with large packets (1520 bytes)
Add promisc config
Add SNMP

####DESCRIPTIONEND####

==========================================================================
*/

#include <common.h>
#include <command.h>
#include <net.h>
#include <malloc.h>

#define mdelay(n)	udelay((n)*1000)
/* forward definition of function used for the uboot interface */
void uboot_push_packet_len(int len);
void uboot_push_tx_done(int key, int val);

/* NE2000 base header file */
#include "ne2000_base.h"

#if defined(CONFIG_DRIVER_AX88796L)
/* AX88796L support */
#include "ax88796.h"
#else
/* Basic NE2000 chip support */
#include "ne2000.h"
#endif

static dp83902a_priv_data_t nic; /* just one instance of the card supported */

static bool
dp83902a_init(void)
{
	dp83902a_priv_data_t *dp = &nic;
	u8* base;
#if defined(NE2000_BASIC_INIT)
	int i;
#endif

	DEBUG_FUNCTION();

	base = dp->base;
	if (!base)
		return false;	/* No device found */

	DEBUG_LINE();

#if defined(NE2000_BASIC_INIT)
	/* AX88796L doesn't need */
	/* Prepare ESA */
	DP_OUT(base, DP_CR, DP_CR_NODMA | DP_CR_PAGE1);	/* Select page 1 */
	/* Use the address from the serial EEPROM */
	for (i = 0; i < 6; i++)
		DP_IN(base, DP_P1_PAR0+i, dp->esa[i]);
	DP_OUT(base, DP_CR, DP_CR_NODMA | DP_CR_PAGE0);	/* Select page 0 */

	printf("NE2000 - %s ESA: %02x:%02x:%02x:%02x:%02x:%02x\n",
		"eeprom",
		dp->esa[0],
		dp->esa[1],
		dp->esa[2],
		dp->esa[3],
		dp->esa[4],
		dp->esa[5] );

#endif	/* NE2000_BASIC_INIT */
	return true;
}

static void
dp83902a_stop(void)
{
	dp83902a_priv_data_t *dp = &nic;
	u8 *base = dp->base;

	DEBUG_FUNCTION();

	DP_OUT(base, DP_CR, DP_CR_PAGE0 | DP_CR_NODMA | DP_CR_STOP);	/* Brutal */
	DP_OUT(base, DP_ISR, 0xFF);		/* Clear any pending interrupts */
	DP_OUT(base, DP_IMR, 0x00);		/* Disable all interrupts */

	dp->running = false;
}

/*
 * This function is called to "start up" the interface. It may be called
 * multiple times, even when the hardware is already running. It will be
 * called whenever something "hardware oriented" changes and should leave
 * the hardware ready to send/receive packets.
 */
static void
dp83902a_start(u8 * enaddr)
{
	dp83902a_priv_data_t *dp = &nic;
	u8 *base = dp->base;
	int i;

	DEBUG_FUNCTION();

	DP_OUT(base, DP_CR, DP_CR_PAGE0 | DP_CR_NODMA | DP_CR_STOP); /* Brutal */
	DP_OUT(base, DP_DCR, DP_DCR_INIT);
	DP_OUT(base, DP_RBCH, 0);		/* Remote byte count */
	DP_OUT(base, DP_RBCL, 0);
	DP_OUT(base, DP_RCR, DP_RCR_MON);	/* Accept no packets */
	DP_OUT(base, DP_TCR, DP_TCR_LOCAL);	/* Transmitter [virtually] off */
	DP_OUT(base, DP_TPSR, dp->tx_buf1);	/* Transmitter start page */
	dp->tx1 = dp->tx2 = 0;
	dp->tx_next = dp->tx_buf1;
	dp->tx_started = false;
	dp->running = true;
	DP_OUT(base, DP_PSTART, dp->rx_buf_start); /* Receive ring start page */
	DP_OUT(base, DP_BNDRY, dp->rx_buf_end - 1); /* Receive ring boundary */
	DP_OUT(base, DP_PSTOP, dp->rx_buf_end);	/* Receive ring end page */
	dp->rx_next = dp->rx_buf_start - 1;
	dp->running = true;
	DP_OUT(base, DP_ISR, 0xFF);		/* Clear any pending interrupts */
	DP_OUT(base, DP_IMR, DP_IMR_All);	/* Enable all interrupts */
	DP_OUT(base, DP_CR, DP_CR_NODMA | DP_CR_PAGE1 | DP_CR_STOP);	/* Select page 1 */
	DP_OUT(base, DP_P1_CURP, dp->rx_buf_start);	/* Current page - next free page for Rx */
	dp->running = true;
	for (i = 0; i < ETHER_ADDR_LEN; i++) {
		/* FIXME */
		/*((vu_short*)( base + ((DP_P1_PAR0 + i) * 2) +
		 * 0x1400)) = enaddr[i];*/
		DP_OUT(base, DP_P1_PAR0+i, enaddr[i]);
	}
	/* Enable and start device */
	DP_OUT(base, DP_CR, DP_CR_PAGE0 | DP_CR_NODMA | DP_CR_START);
	DP_OUT(base, DP_TCR, DP_TCR_NORMAL); /* Normal transmit operations */
	DP_OUT(base, DP_RCR, DP_RCR_AB); /* Accept broadcast, no errors, no multicast */
	dp->running = true;
}

/*
 * This routine is called to start the transmitter. It is split out from the
 * data handling routine so it may be called either when data becomes first
 * available or when an Tx interrupt occurs
 */

static void
dp83902a_start_xmit(int start_page, int len)
{
	dp83902a_priv_data_t *dp = (dp83902a_priv_data_t *) &nic;
	u8 *base = dp->base;

	DEBUG_FUNCTION();

#if DEBUG & 1
	printf("Tx pkt %d len %d\n", start_page, len);
	if (dp->tx_started)
		printf("TX already started?!?\n");
#endif

	DP_OUT(base, DP_ISR, (DP_ISR_TxP | DP_ISR_TxE));
	DP_OUT(base, DP_CR, DP_CR_PAGE0 | DP_CR_NODMA | DP_CR_START);
	DP_OUT(base, DP_TBCL, len & 0xFF);
	DP_OUT(base, DP_TBCH, len >> 8);
	DP_OUT(base, DP_TPSR, start_page);
	DP_OUT(base, DP_CR, DP_CR_NODMA | DP_CR_TXPKT | DP_CR_START);

	dp->tx_started = true;
}

/*
 * This routine is called to send data to the hardware. It is known a-priori
 * that there is free buffer space (dp->tx_next).
 */
static void
dp83902a_send(u8 *data, int total_len, u32 key)
{
	struct dp83902a_priv_data *dp = (struct dp83902a_priv_data *) &nic;
	u8 *base = dp->base;
	int len, start_page, pkt_len, i, isr;
#if DEBUG & 4
	int dx;
#endif

	DEBUG_FUNCTION();

	len = pkt_len = total_len;
	if (pkt_len < IEEE_8023_MIN_FRAME)
		pkt_len = IEEE_8023_MIN_FRAME;

	start_page = dp->tx_next;
	if (dp->tx_next == dp->tx_buf1) {
		dp->tx1 = start_page;
		dp->tx1_len = pkt_len;
		dp->tx1_key = key;
		dp->tx_next = dp->tx_buf2;
	} else {
		dp->tx2 = start_page;
		dp->tx2_len = pkt_len;
		dp->tx2_key = key;
		dp->tx_next = dp->tx_buf1;
	}

#if DEBUG & 5
	printf("TX prep page %d len %d\n", start_page, pkt_len);
#endif

	DP_OUT(base, DP_ISR, DP_ISR_RDC);	/* Clear end of DMA */
	{
		/*
		 * Dummy read. The manual sez something slightly different,
		 * but the code is extended a bit to do what Hitachi's monitor
		 * does (i.e., also read data).
		 */

		u16 tmp;
		int len = 1;

		DP_OUT(base, DP_RSAL, 0x100 - len);
		DP_OUT(base, DP_RSAH, (start_page - 1) & 0xff);
		DP_OUT(base, DP_RBCL, len);
		DP_OUT(base, DP_RBCH, 0);
		DP_OUT(base, DP_CR, DP_CR_PAGE0 | DP_CR_RDMA | DP_CR_START);
		DP_IN_DATA(dp->data, tmp);
	}

#ifdef CYGHWR_NS_DP83902A_PLF_BROKEN_TX_DMA
	/*
	 * Stall for a bit before continuing to work around random data
	 * corruption problems on some platforms.
	 */
	CYGACC_CALL_IF_DELAY_US(1);
#endif

	/* Send data to device buffer(s) */
	DP_OUT(base, DP_RSAL, 0);
	DP_OUT(base, DP_RSAH, start_page);
	DP_OUT(base, DP_RBCL, pkt_len & 0xFF);
	DP_OUT(base, DP_RBCH, pkt_len >> 8);
	DP_OUT(base, DP_CR, DP_CR_WDMA | DP_CR_START);

	/* Put data into buffer */
#if DEBUG & 4
	printf(" sg buf %08lx len %08x\n ", (u32)data, len);
	dx = 0;
#endif
	while (len > 0) {
#if DEBUG & 4
		printf(" %02x", *data);
		if (0 == (++dx % 16)) printf("\n ");
#endif

		DP_OUT_DATA(dp->data, *data++);
		len--;
	}
#if DEBUG & 4
	printf("\n");
#endif
	if (total_len < pkt_len) {
#if DEBUG & 4
		printf("  + %d bytes of padding\n", pkt_len - total_len);
#endif
		/* Padding to 802.3 length was required */
		for (i = total_len; i < pkt_len;) {
			i++;
			DP_OUT_DATA(dp->data, 0);
		}
	}

#ifdef CYGHWR_NS_DP83902A_PLF_BROKEN_TX_DMA
	/*
	 * After last data write, delay for a bit before accessing the
	 * device again, or we may get random data corruption in the last
	 * datum (on some platforms).
	 */
	CYGACC_CALL_IF_DELAY_US(1);
#endif

	/* Wait for DMA to complete */
	do {
		DP_IN(base, DP_ISR, isr);
	} while ((isr & DP_ISR_RDC) == 0);

	/* Then disable DMA */
	DP_OUT(base, DP_CR, DP_CR_PAGE0 | DP_CR_NODMA | DP_CR_START);

	/* Start transmit if not already going */
	if (!dp->tx_started) {
		if (start_page == dp->tx1) {
			dp->tx_int = 1; /* Expecting interrupt from BUF1 */
		} else {
			dp->tx_int = 2; /* Expecting interrupt from BUF2 */
		}
		dp83902a_start_xmit(start_page, pkt_len);
	}
}

/*
 * This function is called when a packet has been received. It's job is
 * to prepare to unload the packet from the hardware. Once the length of
 * the packet is known, the upper layer of the driver can be told. When
 * the upper layer is ready to unload the packet, the internal function
 * 'dp83902a_recv' will be called to actually fetch it from the hardware.
 */
static void
dp83902a_RxEvent(void)
{
	struct dp83902a_priv_data *dp = (struct dp83902a_priv_data *) &nic;
	u8 *base = dp->base;
	u8 rsr;
	u8 rcv_hdr[4];
	int i, len, pkt, cur;

	DEBUG_FUNCTION();

	DP_IN(base, DP_RSR, rsr);
	while (true) {
		/* Read incoming packet header */
		DP_OUT(base, DP_CR, DP_CR_PAGE1 | DP_CR_NODMA | DP_CR_START);
		DP_IN(base, DP_P1_CURP, cur);
		DP_OUT(base, DP_P1_CR, DP_CR_PAGE0 | DP_CR_NODMA | DP_CR_START);
		DP_IN(base, DP_BNDRY, pkt);

		pkt += 1;
		if (pkt == dp->rx_buf_end)
			pkt = dp->rx_buf_start;

		if (pkt == cur) {
			break;
		}
		DP_OUT(base, DP_RBCL, sizeof(rcv_hdr));
		DP_OUT(base, DP_RBCH, 0);
		DP_OUT(base, DP_RSAL, 0);
		DP_OUT(base, DP_RSAH, pkt);
		if (dp->rx_next == pkt) {
			if (cur == dp->rx_buf_start)
				DP_OUT(base, DP_BNDRY, dp->rx_buf_end - 1);
			else
				DP_OUT(base, DP_BNDRY, cur - 1); /* Update pointer */
			return;
		}
		dp->rx_next = pkt;
		DP_OUT(base, DP_ISR, DP_ISR_RDC); /* Clear end of DMA */
		DP_OUT(base, DP_CR, DP_CR_RDMA | DP_CR_START);
#ifdef CYGHWR_NS_DP83902A_PLF_BROKEN_RX_DMA
		CYGACC_CALL_IF_DELAY_US(10);
#endif

		/* read header (get data size)*/
		for (i = 0; i < sizeof(rcv_hdr);) {
			DP_IN_DATA(dp->data, rcv_hdr[i++]);
		}

#if DEBUG & 5
		printf("rx hdr %02x %02x %02x %02x\n",
			rcv_hdr[0], rcv_hdr[1], rcv_hdr[2], rcv_hdr[3]);
#endif
		len = ((rcv_hdr[3] << 8) | rcv_hdr[2]) - sizeof(rcv_hdr);

		/* data read */
		uboot_push_packet_len(len);

		if (rcv_hdr[1] == dp->rx_buf_start)
			DP_OUT(base, DP_BNDRY, dp->rx_buf_end - 1);
		else
			DP_OUT(base, DP_BNDRY, rcv_hdr[1] - 1); /* Update pointer */
	}
}

/*
 * This function is called as a result of the "eth_drv_recv()" call above.
 * It's job is to actually fetch data for a packet from the hardware once
 * memory buffers have been allocated for the packet. Note that the buffers
 * may come in pieces, using a scatter-gather list. This allows for more
 * efficient processing in the upper layers of the stack.
 */
static void
dp83902a_recv(u8 *data, int len)
{
	struct dp83902a_priv_data *dp = (struct dp83902a_priv_data *) &nic;
	u8 *base = dp->base;
	int i, mlen;
	u8 saved_char = 0;
	bool saved;
#if DEBUG & 4
	int dx;
#endif

	DEBUG_FUNCTION();

#if DEBUG & 5
	printf("Rx packet %d length %d\n", dp->rx_next, len);
#endif

	/* Read incoming packet data */
	DP_OUT(base, DP_CR, DP_CR_PAGE0 | DP_CR_NODMA | DP_CR_START);
	DP_OUT(base, DP_RBCL, len & 0xFF);
	DP_OUT(base, DP_RBCH, len >> 8);
	DP_OUT(base, DP_RSAL, 4);		/* Past header */
	DP_OUT(base, DP_RSAH, dp->rx_next);
	DP_OUT(base, DP_ISR, DP_ISR_RDC); /* Clear end of DMA */
	DP_OUT(base, DP_CR, DP_CR_RDMA | DP_CR_START);
#ifdef CYGHWR_NS_DP83902A_PLF_BROKEN_RX_DMA
	CYGACC_CALL_IF_DELAY_US(10);
#endif

	saved = false;
	for (i = 0; i < 1; i++) {
		if (data) {
			mlen = len;
#if DEBUG & 4
			printf(" sg buf %08lx len %08x \n", (u32) data, mlen);
			dx = 0;
#endif
			while (0 < mlen) {
				/* Saved byte from previous loop? */
				if (saved) {
					*data++ = saved_char;
					mlen--;
					saved = false;
					continue;
				}

				{
					u8 tmp;
					DP_IN_DATA(dp->data, tmp);
#if DEBUG & 4
					printf(" %02x", tmp);
					if (0 == (++dx % 16)) printf("\n ");
#endif
					*data++ = tmp;;
					mlen--;
				}
			}
#if DEBUG & 4
			printf("\n");
#endif
		}
	}
}

static void
dp83902a_TxEvent(void)
{
	struct dp83902a_priv_data *dp = (struct dp83902a_priv_data *) &nic;
	u8 *base = dp->base;
	u8 tsr;
	u32 key;

	DEBUG_FUNCTION();

	DP_IN(base, DP_TSR, tsr);
	if (dp->tx_int == 1) {
		key = dp->tx1_key;
		dp->tx1 = 0;
	} else {
		key = dp->tx2_key;
		dp->tx2 = 0;
	}
	/* Start next packet if one is ready */
	dp->tx_started = false;
	if (dp->tx1) {
		dp83902a_start_xmit(dp->tx1, dp->tx1_len);
		dp->tx_int = 1;
	} else if (dp->tx2) {
		dp83902a_start_xmit(dp->tx2, dp->tx2_len);
		dp->tx_int = 2;
	} else {
		dp->tx_int = 0;
	}
	/* Tell higher level we sent this packet */
	uboot_push_tx_done(key, 0);
}

/*
 * Read the tally counters to clear them. Called in response to a CNT
 * interrupt.
 */
static void
dp83902a_ClearCounters(void)
{
	struct dp83902a_priv_data *dp = (struct dp83902a_priv_data *) &nic;
	u8 *base = dp->base;
	u8 cnt1, cnt2, cnt3;

	DP_IN(base, DP_FER, cnt1);
	DP_IN(base, DP_CER, cnt2);
	DP_IN(base, DP_MISSED, cnt3);
	DP_OUT(base, DP_ISR, DP_ISR_CNT);
}

/*
 * Deal with an overflow condition. This code follows the procedure set
 * out in section 7.0 of the datasheet.
 */
static void
dp83902a_Overflow(void)
{
	struct dp83902a_priv_data *dp = (struct dp83902a_priv_data *)&nic;
	u8 *base = dp->base;
	u8 isr;

	/* Issue a stop command and wait 1.6ms for it to complete. */
	DP_OUT(base, DP_CR, DP_CR_STOP | DP_CR_NODMA);
	CYGACC_CALL_IF_DELAY_US(1600);

	/* Clear the remote byte counter registers. */
	DP_OUT(base, DP_RBCL, 0);
	DP_OUT(base, DP_RBCH, 0);

	/* Enter loopback mode while we clear the buffer. */
	DP_OUT(base, DP_TCR, DP_TCR_LOCAL);
	DP_OUT(base, DP_CR, DP_CR_START | DP_CR_NODMA);

	/*
	 * Read in as many packets as we can and acknowledge any and receive
	 * interrupts. Since the buffer has overflowed, a receive event of
	 * some kind will have occured.
	 */
	dp83902a_RxEvent();
	DP_OUT(base, DP_ISR, DP_ISR_RxP|DP_ISR_RxE);

	/* Clear the overflow condition and leave loopback mode. */
	DP_OUT(base, DP_ISR, DP_ISR_OFLW);
	DP_OUT(base, DP_TCR, DP_TCR_NORMAL);

	/*
	 * If a transmit command was issued, but no transmit event has occured,
	 * restart it here.
	 */
	DP_IN(base, DP_ISR, isr);
	if (dp->tx_started && !(isr & (DP_ISR_TxP|DP_ISR_TxE))) {
		DP_OUT(base, DP_CR, DP_CR_NODMA | DP_CR_TXPKT | DP_CR_START);
	}
}

static void
dp83902a_poll(void)
{
	struct dp83902a_priv_data *dp = (struct dp83902a_priv_data *) &nic;
	u8 *base = dp->base;
	u8 isr;

	DP_OUT(base, DP_CR, DP_CR_NODMA | DP_CR_PAGE0 | DP_CR_START);
	DP_IN(base, DP_ISR, isr);
	while (0 != isr) {
		/*
		 * The CNT interrupt triggers when the MSB of one of the error
		 * counters is set. We don't much care about these counters, but
		 * we should read their values to reset them.
		 */
		if (isr & DP_ISR_CNT) {
			dp83902a_ClearCounters();
		}
		/*
		 * Check for overflow. It's a special case, since there's a
		 * particular procedure that must be followed to get back into
		 * a running state.a
		 */
		if (isr & DP_ISR_OFLW) {
			dp83902a_Overflow();
		} else {
			/*
			 * Other kinds of interrupts can be acknowledged simply by
			 * clearing the relevant bits of the ISR. Do that now, then
			 * handle the interrupts we care about.
			 */
			DP_OUT(base, DP_ISR, isr);	/* Clear set bits */
			if (!dp->running) break;	/* Is this necessary? */
			/*
			 * Check for tx_started on TX event since these may happen
			 * spuriously it seems.
			 */
			if (isr & (DP_ISR_TxP|DP_ISR_TxE) && dp->tx_started) {
				dp83902a_TxEvent();
			}
			if (isr & (DP_ISR_RxP|DP_ISR_RxE)) {
				dp83902a_RxEvent();
			}
		}
		DP_IN(base, DP_ISR, isr);
	}
}


/* U-boot specific routines */
static u8 *pbuf = NULL;

static int pkey = -1;
static int initialized = 0;

void uboot_push_packet_len(int len) {
	PRINTK("pushed len = %d\n", len);
	if (len >= 2000) {
		printf("NE2000: packet too big\n");
		return;
	}
	dp83902a_recv(&pbuf[0], len);

	/*Just pass it to the upper layer*/
	NetReceive(&pbuf[0], len);
}

void uboot_push_tx_done(int key, int val) {
	PRINTK("pushed key = %d\n", key);
	pkey = key;
}

int eth_init(bd_t *bd) {
	int r;
	u8 dev_addr[6];
	char ethaddr[20];

	PRINTK("### eth_init\n");

	if (!pbuf) {
		pbuf = malloc(2000);
		if (!pbuf) {
			printf("Cannot allocate rx buffer\n");
			return -1;
		}
	}

#ifdef CONFIG_DRIVER_NE2000_CCR
	{
		vu_char *p = (vu_char *) CONFIG_DRIVER_NE2000_CCR;

		PRINTK("CCR before is %x\n", *p);
		*p = CONFIG_DRIVER_NE2000_VAL;
		PRINTK("CCR after is %x\n", *p);
	}
#endif

	nic.base = (u8 *) CONFIG_DRIVER_NE2000_BASE;

	r = get_prom(dev_addr, nic.base);
	if (!r)
		return -1;

	sprintf (ethaddr, "%02X:%02X:%02X:%02X:%02X:%02X",
		 dev_addr[0], dev_addr[1],
		 dev_addr[2], dev_addr[3],
		 dev_addr[4], dev_addr[5]) ;
	PRINTK("Set environment from HW MAC addr = \"%s\"\n", ethaddr);
	setenv ("ethaddr", ethaddr);

	nic.data = nic.base + DP_DATA;
	nic.tx_buf1 = START_PG;
	nic.tx_buf2 = START_PG2;
	nic.rx_buf_start = RX_START;
	nic.rx_buf_end = RX_END;

	if (dp83902a_init() == false)
		return -1;

	dp83902a_start(dev_addr);
	initialized = 1;

	return 0;
}

void eth_halt() {

	PRINTK("### eth_halt\n");
	if(initialized)
		dp83902a_stop();
	initialized = 0;
}

int eth_rx() {
	dp83902a_poll();
	return 1;
}

int eth_send(volatile void *packet, int length) {
	int tmo;

	PRINTK("### eth_send\n");

	pkey = -1;

	dp83902a_send((u8 *) packet, length, 666);
	tmo = get_timer (0) + TOUT * CONFIG_SYS_HZ;
	while(1) {
		dp83902a_poll();
		if (pkey != -1) {
			PRINTK("Packet sucesfully sent\n");
			return 0;
		}
		if (get_timer (0) >= tmo) {
			printf("transmission error (timoeut)\n");
			return 0;
		}

	}
	return 0;
}