dev/dc/if_dc.c

/*
 * Copyright (c) 1997, 1998, 1999
 *	Bill Paul <wpaul@ee.columbia.edu>.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Bill Paul.
 * 4. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL Bill Paul OR THE VOICES IN HIS HEAD
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $FreeBSD$
 */

/*
 * DEC "tulip" clone ethernet driver. Supports the DEC/Intel 21143
 * series chips and several workalikes including the following:
 *
 * Macronix 98713/98715/98725 PMAC (www.macronix.com)
 * Macronix/Lite-On 82c115 PNIC II (www.macronix.com)
 * Lite-On 82c168/82c169 PNIC (www.litecom.com)
 * ASIX Electronics AX88140A (www.asix.com.tw)
 * ASIX Electronics AX88141 (www.asix.com.tw)
 * ADMtek AL981 (www.admtek.com.tw)
 * ADMtek AN985 (www.admtek.com.tw)
 * Davicom DM9100, DM9102, DM9102A (www.davicom8.com)
 *
 * Datasheets for the 21143 are available at developer.intel.com.
 * Datasheets for the clone parts can be found at their respective sites.
 * (Except for the PNIC; see www.freebsd.org/~wpaul/PNIC/pnic.ps.gz.)
 * The PNIC II is essentially a Macronix 98715A chip; the only difference
 * worth noting is that its multicast hash table is only 128 bits wide
 * instead of 512.
 *
 * Written by Bill Paul <wpaul@ee.columbia.edu>
 * Electrical Engineering Department
 * Columbia University, New York City
 */

/*
 * The Intel 21143 is the successor to the DEC 21140. It is basically
 * the same as the 21140 but with a few new features. The 21143 supports
 * three kinds of media attachments:
 *
 * o MII port, for 10Mbps and 100Mbps support and NWAY
 *   autonegotiation provided by an external PHY.
 * o SYM port, for symbol mode 100Mbps support.
 * o 10baseT port.
 * o AUI/BNC port.
 *
 * The 100Mbps SYM port and 10baseT port can be used together in
 * combination with the internal NWAY support to create a 10/100
 * autosensing configuration.
 *
 * Knowing which media is available on a given card is tough: you're
 * supposed to go slogging through the EEPROM looking for media
 * description structures. Unfortunately, some card vendors that use
 * the 21143 don't obey the DEC SROM spec correctly, which means that
 * what you find in the EEPROM may not agree with reality. Fortunately,
 * the 21143 provides us a way to get around this issue: lurking in
 * PCI configuration space is the Configuration Wake-Up Command Register.
 * This register is loaded with a value from the EEPROM when wake on LAN
 * mode is enabled; this value tells us quite clearly what kind of media
 * is attached to the NIC. The main purpose of this register is to tell
 * the NIC what media to scan when in wake on LAN mode, however by
 * forcibly enabling wake on LAN mode, we can use to learn what kind of
 * media a given NIC has available and adapt ourselves accordingly.
 *
 * Of course, if the media description blocks in the EEPROM are bogus.
 * what are the odds that the CWUC aren't bogus as well, right? Well,
 * the CWUC value is more likely to be correct since wake on LAN mode
 * won't work correctly without it, and wake on LAN is a big selling
 * point these days. It's also harder to screw up a single byte than
 * a whole media descriptor block.
 *
 * Note that not all tulip workalikes are handled in this driver: we only
 * deal with those which are relatively well behaved. The Winbond is
 * handled separately due to its different register offsets and the
 * special handling needed for its various bugs. The PNIC is handled
 * here, but I'm not thrilled about it.
 *
 * All of the workalike chips use some form of MII transceiver support
 * with the exception of the Macronix chips, which also have a SYM port.
 * The ASIX AX88140A is also documented to have a SYM port, but all
 * the cards I've seen use an MII transceiver, probably because the
 * AX88140A doesn't support internal NWAY.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sockio.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/socket.h>

#include <net/if.h>
#include <net/if_arp.h>
#include <net/ethernet.h>
#include <net/if_dl.h>
#include <net/if_media.h>

#include <net/bpf.h>

#include "opt_bdg.h"
#ifdef BRIDGE
#include <net/bridge.h>
#endif

#include <vm/vm.h>              /* for vtophys */
#include <vm/pmap.h>            /* for vtophys */
#include <machine/clock.h>      /* for DELAY */
#include <machine/bus_pio.h>
#include <machine/bus_memio.h>
#include <machine/bus.h>
#include <machine/resource.h>
#include <sys/bus.h>
#include <sys/rman.h>

#include <dev/mii/mii.h>
#include <dev/mii/miivar.h>

#include <pci/pcireg.h>
#include <pci/pcivar.h>

#define DC_USEIOSPACE

#include <pci/if_dcreg.h>

/* "controller miibus0" required.  See GENERIC if you get errors here. */
#include "miibus_if.h"

#ifndef lint
static const char rcsid[] =
  "$FreeBSD$";
#endif

/*
 * Various supported device vendors/types and their names.
 */
static struct dc_type dc_devs[] = {
	{ DC_VENDORID_DEC, DC_DEVICEID_21143,
		"Intel 21143 10/100BaseTX" },
	{ DC_VENDORID_DAVICOM, DC_DEVICEID_DM9100,
		"Davicom DM9100 10/100BaseTX" },
	{ DC_VENDORID_DAVICOM, DC_DEVICEID_DM9102,
		"Davicom DM9102 10/100BaseTX" },
	{ DC_VENDORID_DAVICOM, DC_DEVICEID_DM9102,
		"Davicom DM9102A 10/100BaseTX" },
	{ DC_VENDORID_ADMTEK, DC_DEVICEID_AL981,
		"ADMtek AL981 10/100BaseTX" },
	{ DC_VENDORID_ADMTEK, DC_DEVICEID_AN985,
		"ADMtek AN985 10/100BaseTX" },
	{ DC_VENDORID_ASIX, DC_DEVICEID_AX88140A,
		"ASIX AX88140A 10/100BaseTX" },
	{ DC_VENDORID_ASIX, DC_DEVICEID_AX88140A,
		"ASIX AX88141 10/100BaseTX" },
	{ DC_VENDORID_MX, DC_DEVICEID_98713,
		"Macronix 98713 10/100BaseTX" },
	{ DC_VENDORID_MX, DC_DEVICEID_98713,
		"Macronix 98713A 10/100BaseTX" },
	{ DC_VENDORID_CP, DC_DEVICEID_98713_CP,
		"Compex RL100-TX 10/100BaseTX" },
	{ DC_VENDORID_CP, DC_DEVICEID_98713_CP,
		"Compex RL100-TX 10/100BaseTX" },
	{ DC_VENDORID_MX, DC_DEVICEID_987x5,
		"Macronix 98715/98715A 10/100BaseTX" },
	{ DC_VENDORID_MX, DC_DEVICEID_987x5,
		"Macronix 98725 10/100BaseTX" },
	{ DC_VENDORID_LO, DC_DEVICEID_82C115,
		"LC82C115 PNIC II 10/100BaseTX" },
	{ DC_VENDORID_LO, DC_DEVICEID_82C168,
		"82c168 PNIC 10/100BaseTX" },
	{ DC_VENDORID_LO, DC_DEVICEID_82C168,
		"82c169 PNIC 10/100BaseTX" },
	{ 0, 0, NULL }
};

static int dc_probe		__P((device_t));
static int dc_attach		__P((device_t));
static int dc_detach		__P((device_t));
static void dc_acpi		__P((device_t));
static struct dc_type *dc_devtype	__P((device_t));
static int dc_newbuf		__P((struct dc_softc *, int, struct mbuf *));
static int dc_encap		__P((struct dc_softc *, struct mbuf *,
					u_int32_t *));
static int dc_coal		__P((struct dc_softc *, struct mbuf **));
static void dc_pnic_rx_bug_war	__P((struct dc_softc *, int));
static int dc_rx_resync		__P((struct dc_softc *));
static void dc_rxeof		__P((struct dc_softc *));
static void dc_txeof		__P((struct dc_softc *));
static void dc_tick		__P((void *));
static void dc_intr		__P((void *));
static void dc_start		__P((struct ifnet *));
static int dc_ioctl		__P((struct ifnet *, u_long, caddr_t));
static void dc_init		__P((void *));
static void dc_stop		__P((struct dc_softc *));
static void dc_watchdog		__P((struct ifnet *));
static void dc_shutdown		__P((device_t));
static int dc_ifmedia_upd	__P((struct ifnet *));
static void dc_ifmedia_sts	__P((struct ifnet *, struct ifmediareq *));

static void dc_delay		__P((struct dc_softc *));
static void dc_eeprom_idle	__P((struct dc_softc *));
static void dc_eeprom_putbyte	__P((struct dc_softc *, int));
static void dc_eeprom_getword	__P((struct dc_softc *, int, u_int16_t *));
static void dc_eeprom_getword_pnic
				__P((struct dc_softc *, int, u_int16_t *));
static void dc_read_eeprom	__P((struct dc_softc *, caddr_t, int,
							int, int));

static void dc_mii_writebit	__P((struct dc_softc *, int));
static int dc_mii_readbit	__P((struct dc_softc *));
static void dc_mii_sync		__P((struct dc_softc *));
static void dc_mii_send		__P((struct dc_softc *, u_int32_t, int));
static int dc_mii_readreg	__P((struct dc_softc *, struct dc_mii_frame *));
static int dc_mii_writereg	__P((struct dc_softc *, struct dc_mii_frame *));
static int dc_miibus_readreg	__P((device_t, int, int));
static int dc_miibus_writereg	__P((device_t, int, int, int));
static void dc_miibus_statchg	__P((device_t));
static void dc_miibus_mediainit	__P((device_t));

static void dc_setcfg		__P((struct dc_softc *, int));
static u_int32_t dc_crc_le	__P((struct dc_softc *, caddr_t));
static u_int32_t dc_crc_be	__P((caddr_t));
static void dc_setfilt_21143	__P((struct dc_softc *));
static void dc_setfilt_asix	__P((struct dc_softc *));
static void dc_setfilt_admtek	__P((struct dc_softc *));

static void dc_setfilt		__P((struct dc_softc *));

static void dc_reset		__P((struct dc_softc *));
static int dc_list_rx_init	__P((struct dc_softc *));
static int dc_list_tx_init	__P((struct dc_softc *));

#ifdef DC_USEIOSPACE
#define DC_RES			SYS_RES_IOPORT
#define DC_RID			DC_PCI_CFBIO
#else
#define DC_RES			SYS_RES_MEMORY
#define DC_RID			DC_PCI_CFBMA
#endif

static device_method_t dc_methods[] = {
	/* Device interface */
	DEVMETHOD(device_probe,		dc_probe),
	DEVMETHOD(device_attach,	dc_attach),
	DEVMETHOD(device_detach,	dc_detach),
	DEVMETHOD(device_shutdown,	dc_shutdown),

	/* bus interface */
	DEVMETHOD(bus_print_child,	bus_generic_print_child),
	DEVMETHOD(bus_driver_added,	bus_generic_driver_added),

	/* MII interface */
	DEVMETHOD(miibus_readreg,	dc_miibus_readreg),
	DEVMETHOD(miibus_writereg,	dc_miibus_writereg),
	DEVMETHOD(miibus_statchg,	dc_miibus_statchg),
	DEVMETHOD(miibus_mediainit,	dc_miibus_mediainit),

	{ 0, 0 }
};

static driver_t dc_driver = {
	"dc",
	dc_methods,
	sizeof(struct dc_softc)
};

static devclass_t dc_devclass;

DRIVER_MODULE(if_dc, pci, dc_driver, dc_devclass, 0, 0);
DRIVER_MODULE(miibus, dc, miibus_driver, miibus_devclass, 0, 0);

#define DC_SETBIT(sc, reg, x)				\
	CSR_WRITE_4(sc, reg, CSR_READ_4(sc, reg) | (x))

#define DC_CLRBIT(sc, reg, x)				\
	CSR_WRITE_4(sc, reg, CSR_READ_4(sc, reg) & ~(x))

#define SIO_SET(x)	DC_SETBIT(sc, DC_SIO, (x))
#define SIO_CLR(x)	DC_CLRBIT(sc, DC_SIO, (x))

static void dc_delay(sc)
	struct dc_softc		*sc;
{
	int			idx;

	for (idx = (300 / 33) + 1; idx > 0; idx--)
		CSR_READ_4(sc, DC_BUSCTL);
}

static void dc_eeprom_idle(sc)
	struct dc_softc		*sc;
{
	register int		i;

	CSR_WRITE_4(sc, DC_SIO, DC_SIO_EESEL);
	dc_delay(sc);
	DC_SETBIT(sc, DC_SIO, DC_SIO_ROMCTL_READ);
	dc_delay(sc);
	DC_CLRBIT(sc, DC_SIO, DC_SIO_EE_CLK);
	dc_delay(sc);
	DC_SETBIT(sc, DC_SIO, DC_SIO_EE_CS);
	dc_delay(sc);

	for (i = 0; i < 25; i++) {
		DC_CLRBIT(sc, DC_SIO, DC_SIO_EE_CLK);
		dc_delay(sc);
		DC_SETBIT(sc, DC_SIO, DC_SIO_EE_CLK);
		dc_delay(sc);
	}

	DC_CLRBIT(sc, DC_SIO, DC_SIO_EE_CLK);
	dc_delay(sc);
	DC_CLRBIT(sc, DC_SIO, DC_SIO_EE_CS);
	dc_delay(sc);
	CSR_WRITE_4(sc, DC_SIO, 0x00000000);

	return;
}

/*
 * Send a read command and address to the EEPROM, check for ACK.
 */
static void dc_eeprom_putbyte(sc, addr)
	struct dc_softc		*sc;
	int			addr;
{
	register int		d, i;

	/*
	 * The AN985 has a 93C66 EEPROM on it instead of
	 * a 93C46. It uses a different bit sequence for
	 * specifying the "read" opcode.
	 */
	if (DC_IS_CENTAUR(sc))
		d = addr | (DC_EECMD_READ << 2);
	else
		d = addr | DC_EECMD_READ;

	/*
	 * Feed in each bit and strobe the clock.
	 */
	for (i = 0x400; i; i >>= 1) {
		if (d & i) {
			SIO_SET(DC_SIO_EE_DATAIN);
		} else {
			SIO_CLR(DC_SIO_EE_DATAIN);
		}
		dc_delay(sc);
		SIO_SET(DC_SIO_EE_CLK);
		dc_delay(sc);
		SIO_CLR(DC_SIO_EE_CLK);
		dc_delay(sc);
	}

	return;
}

/*
 * Read a word of data stored in the EEPROM at address 'addr.'
 * The PNIC 82c168/82c169 has its own non-standard way to read
 * the EEPROM.
 */
static void dc_eeprom_getword_pnic(sc, addr, dest)
	struct dc_softc		*sc;
	int			addr;
	u_int16_t		*dest;
{
	register int		i;
	u_int32_t		r;

	CSR_WRITE_4(sc, DC_PN_SIOCTL, DC_PN_EEOPCODE_READ|addr);

	for (i = 0; i < DC_TIMEOUT; i++) {
		DELAY(1);
		r = CSR_READ_4(sc, DC_SIO);
		if (!(r & DC_PN_SIOCTL_BUSY)) {
			*dest = (u_int16_t)(r & 0xFFFF);
			return;
		}
	}

	return;
}

/*
 * Read a word of data stored in the EEPROM at address 'addr.'
 */
static void dc_eeprom_getword(sc, addr, dest)
	struct dc_softc		*sc;
	int			addr;
	u_int16_t		*dest;
{
	register int		i;
	u_int16_t		word = 0;

	/* Force EEPROM to idle state. */
	dc_eeprom_idle(sc);

	/* Enter EEPROM access mode. */
	CSR_WRITE_4(sc, DC_SIO, DC_SIO_EESEL);
	dc_delay(sc);
	DC_SETBIT(sc, DC_SIO,  DC_SIO_ROMCTL_READ);
	dc_delay(sc);
	DC_CLRBIT(sc, DC_SIO, DC_SIO_EE_CLK);
	dc_delay(sc);
	DC_SETBIT(sc, DC_SIO, DC_SIO_EE_CS);
	dc_delay(sc);

	/*
	 * Send address of word we want to read.
	 */
	dc_eeprom_putbyte(sc, addr);

	/*
	 * Start reading bits from EEPROM.
	 */
	for (i = 0x8000; i; i >>= 1) {
		SIO_SET(DC_SIO_EE_CLK);
		dc_delay(sc);
		if (CSR_READ_4(sc, DC_SIO) & DC_SIO_EE_DATAOUT)
			word |= i;
		dc_delay(sc);
		SIO_CLR(DC_SIO_EE_CLK);
		dc_delay(sc);
	}

	/* Turn off EEPROM access mode. */
	dc_eeprom_idle(sc);

	*dest = word;

	return;
}

/*
 * Read a sequence of words from the EEPROM.
 */
static void dc_read_eeprom(sc, dest, off, cnt, swap)
	struct dc_softc		*sc;
	caddr_t			dest;
	int			off;
	int			cnt;
	int			swap;
{
	int			i;
	u_int16_t		word = 0, *ptr;

	for (i = 0; i < cnt; i++) {
		if (DC_IS_PNIC(sc))
			dc_eeprom_getword_pnic(sc, off + i, &word);
		else
			dc_eeprom_getword(sc, off + i, &word);
		ptr = (u_int16_t *)(dest + (i * 2));
		if (swap)
			*ptr = ntohs(word);
		else
			*ptr = word;
	}

	return;
}

/*
 * The following two routines are taken from the Macronix 98713
 * Application Notes pp.19-21.
 */
/*
 * Write a bit to the MII bus.
 */
static void dc_mii_writebit(sc, bit)
	struct dc_softc		*sc;
	int			bit;
{
	if (bit)
		CSR_WRITE_4(sc, DC_SIO,
		    DC_SIO_ROMCTL_WRITE|DC_SIO_MII_DATAOUT);
	else
		CSR_WRITE_4(sc, DC_SIO, DC_SIO_ROMCTL_WRITE);

	DC_SETBIT(sc, DC_SIO, DC_SIO_MII_CLK);
	DC_CLRBIT(sc, DC_SIO, DC_SIO_MII_CLK);

	return;
}

/*
 * Read a bit from the MII bus.
 */
static int dc_mii_readbit(sc)
	struct dc_softc		*sc;
{
	CSR_WRITE_4(sc, DC_SIO, DC_SIO_ROMCTL_READ|DC_SIO_MII_DIR);
	CSR_READ_4(sc, DC_SIO);
	DC_SETBIT(sc, DC_SIO, DC_SIO_MII_CLK);
	DC_CLRBIT(sc, DC_SIO, DC_SIO_MII_CLK);
	if (CSR_READ_4(sc, DC_SIO) & DC_SIO_MII_DATAIN)
		return(1);

	return(0);
}

/*
 * Sync the PHYs by setting data bit and strobing the clock 32 times.
 */
static void dc_mii_sync(sc)
	struct dc_softc		*sc;
{
	register int		i;

	CSR_WRITE_4(sc, DC_SIO, DC_SIO_ROMCTL_WRITE);

	for (i = 0; i < 32; i++)
		dc_mii_writebit(sc, 1);

	return;
}

/*
 * Clock a series of bits through the MII.
 */
static void dc_mii_send(sc, bits, cnt)
	struct dc_softc		*sc;
	u_int32_t		bits;
	int			cnt;
{
	int			i;

	for (i = (0x1 << (cnt - 1)); i; i >>= 1)
		dc_mii_writebit(sc, bits & i);
}

/*
 * Read an PHY register through the MII.
 */
static int dc_mii_readreg(sc, frame)
	struct dc_softc		*sc;
	struct dc_mii_frame	*frame;

{
	int			i, ack, s;

	s = splimp();

	/*
	 * Set up frame for RX.
	 */
	frame->mii_stdelim = DC_MII_STARTDELIM;
	frame->mii_opcode = DC_MII_READOP;
	frame->mii_turnaround = 0;
	frame->mii_data = 0;

	/*
	 * Sync the PHYs.
	 */
	dc_mii_sync(sc);

	/*
	 * Send command/address info.
	 */
	dc_mii_send(sc, frame->mii_stdelim, 2);
	dc_mii_send(sc, frame->mii_opcode, 2);
	dc_mii_send(sc, frame->mii_phyaddr, 5);
	dc_mii_send(sc, frame->mii_regaddr, 5);

#ifdef notdef
	/* Idle bit */
	dc_mii_writebit(sc, 1);
	dc_mii_writebit(sc, 0);
#endif

	/* Check for ack */
	ack = dc_mii_readbit(sc);

	/*
	 * Now try reading data bits. If the ack failed, we still
	 * need to clock through 16 cycles to keep the PHY(s) in sync.
	 */
	if (ack) {
		for(i = 0; i < 16; i++) {
			dc_mii_readbit(sc);
		}
		goto fail;
	}

	for (i = 0x8000; i; i >>= 1) {
		if (!ack) {
			if (dc_mii_readbit(sc))
				frame->mii_data |= i;
		}
	}

fail:

	dc_mii_writebit(sc, 0);
	dc_mii_writebit(sc, 0);

	splx(s);

	if (ack)
		return(1);
	return(0);
}

/*
 * Write to a PHY register through the MII.
 */
static int dc_mii_writereg(sc, frame)
	struct dc_softc		*sc;
	struct dc_mii_frame	*frame;

{
	int			s;

	s = splimp();
	/*
	 * Set up frame for TX.
	 */

	frame->mii_stdelim = DC_MII_STARTDELIM;
	frame->mii_opcode = DC_MII_WRITEOP;
	frame->mii_turnaround = DC_MII_TURNAROUND;

	/*
	 * Sync the PHYs.
	 */
	dc_mii_sync(sc);

	dc_mii_send(sc, frame->mii_stdelim, 2);
	dc_mii_send(sc, frame->mii_opcode, 2);
	dc_mii_send(sc, frame->mii_phyaddr, 5);
	dc_mii_send(sc, frame->mii_regaddr, 5);
	dc_mii_send(sc, frame->mii_turnaround, 2);
	dc_mii_send(sc, frame->mii_data, 16);

	/* Idle bit. */
	dc_mii_writebit(sc, 0);
	dc_mii_writebit(sc, 0);

	splx(s);

	return(0);
}

static int dc_miibus_readreg(dev, phy, reg)
	device_t		dev;
	int			phy, reg;
{
	struct dc_mii_frame	frame;
	struct dc_softc		*sc;
	int			i, rval, phy_reg;

	sc = device_get_softc(dev);
	bzero((char *)&frame, sizeof(frame));

	/*
	 * Note: both the AL981 and AN985 have internal PHYs,
	 * however the AL981 provides direct access to the PHY
	 * registers while the AN985 uses a serial MII interface.
	 * The AN985's MII interface is also buggy in that you
	 * can read from any MII address (0 to 31), but only address 1
	 * behaves normally. To deal with both cases, we pretend
	 * that the PHY is at MII address 1.
	 */
	if (DC_IS_ADMTEK(sc) && phy != DC_ADMTEK_PHYADDR)
		return(0);

	if (sc->dc_pmode == DC_PMODE_SYM) {
		if (phy == (MII_NPHY - 1)) {
			switch(reg) {
			case MII_BMSR:
			/*
			 * Fake something to make the probe
			 * code think there's a PHY here.
			 */
				return(BMSR_MEDIAMASK);
				break;
			case MII_PHYIDR1:
				if (DC_IS_PNIC(sc))
					return(DC_VENDORID_LO);
				return(DC_VENDORID_DEC);
				break;
			case MII_PHYIDR2:
				if (DC_IS_PNIC(sc))
					return(DC_DEVICEID_82C168);
				return(DC_DEVICEID_21143);
				break;
			default:
				return(0);
				break;
			}
		} else
			return(0);
	}

	if (DC_IS_PNIC(sc)) {
		CSR_WRITE_4(sc, DC_PN_MII, DC_PN_MIIOPCODE_READ |
		    (phy << 23) | (reg << 18));
		for (i = 0; i < DC_TIMEOUT; i++) {
			DELAY(1);
			rval = CSR_READ_4(sc, DC_PN_MII);
			if (!(rval & DC_PN_MII_BUSY)) {
				rval &= 0xFFFF;
				return(rval == 0xFFFF ? 0 : rval);
			}
		}
		return(0);
	}

	if (DC_IS_COMET(sc)) {
		switch(reg) {
		case MII_BMCR:
			phy_reg = DC_AL_BMCR;
			break;
		case MII_BMSR:
			phy_reg = DC_AL_BMSR;
			break;
		case MII_PHYIDR1:
			phy_reg = DC_AL_VENID;
			break;
		case MII_PHYIDR2:
			phy_reg = DC_AL_DEVID;
			break;
		case MII_ANAR:
			phy_reg = DC_AL_ANAR;
			break;
		case MII_ANLPAR:
			phy_reg = DC_AL_LPAR;
			break;
		case MII_ANER:
			phy_reg = DC_AL_ANER;
			break;
		default:
			printf("dc%d: phy_read: bad phy register %x\n",
			    sc->dc_unit, reg);
			return(0);
			break;
		}

		rval = CSR_READ_4(sc, phy_reg) & 0x0000FFFF;

		if (rval == 0xFFFF)
			return(0);
		return(rval);
	}

	frame.mii_phyaddr = phy;
	frame.mii_regaddr = reg;
	phy_reg = CSR_READ_4(sc, DC_NETCFG);
	CSR_WRITE_4(sc, DC_NETCFG, phy_reg & ~DC_NETCFG_PORTSEL);
	dc_mii_readreg(sc, &frame);
	CSR_WRITE_4(sc, DC_NETCFG, phy_reg);

	return(frame.mii_data);
}

static int dc_miibus_writereg(dev, phy, reg, data)
	device_t		dev;
	int			phy, reg, data;
{
	struct dc_softc		*sc;
	struct dc_mii_frame	frame;
	int			i, phy_reg;

	sc = device_get_softc(dev);
	bzero((char *)&frame, sizeof(frame));

	if (DC_IS_ADMTEK(sc) && phy != DC_ADMTEK_PHYADDR)
		return(0);

	if (DC_IS_PNIC(sc)) {
		CSR_WRITE_4(sc, DC_PN_MII, DC_PN_MIIOPCODE_WRITE |
		    (phy << 23) | (reg << 10) | data);
		for (i = 0; i < DC_TIMEOUT; i++) {
			if (!(CSR_READ_4(sc, DC_PN_MII) & DC_PN_MII_BUSY))
				break;
		}
		return(0);
	}

	if (DC_IS_COMET(sc)) {
		switch(reg) {
		case MII_BMCR:
			phy_reg = DC_AL_BMCR;
			break;
		case MII_BMSR:
			phy_reg = DC_AL_BMSR;
			break;
		case MII_PHYIDR1:
			phy_reg = DC_AL_VENID;
			break;
		case MII_PHYIDR2:
			phy_reg = DC_AL_DEVID;
			break;
		case MII_ANAR:
			phy_reg = DC_AL_ANAR;
			break;
		case MII_ANLPAR:
			phy_reg = DC_AL_LPAR;
			break;
		case MII_ANER:
			phy_reg = DC_AL_ANER;
			break;
		default:
			printf("dc%d: phy_write: bad phy register %x\n",
			    sc->dc_unit, reg);
			return(0);
			break;
		}

		CSR_WRITE_4(sc, phy_reg, data);
		return(0);
	}

	frame.mii_phyaddr = phy;
	frame.mii_regaddr = reg;
	frame.mii_data = data;

	phy_reg = CSR_READ_4(sc, DC_NETCFG);
	CSR_WRITE_4(sc, DC_NETCFG, phy_reg & ~DC_NETCFG_PORTSEL);
	dc_mii_writereg(sc, &frame);
	CSR_WRITE_4(sc, DC_NETCFG, phy_reg);

	return(0);
}

static void dc_miibus_statchg(dev)
	device_t		dev;
{
	struct dc_softc		*sc;
	struct mii_data		*mii;
	struct ifmedia		*ifm;

	sc = device_get_softc(dev);
	if (DC_IS_ADMTEK(sc))
		return;
	mii = device_get_softc(sc->dc_miibus);
	ifm = &mii->mii_media;
	if (DC_IS_DAVICOM(sc) &&
	    IFM_SUBTYPE(ifm->ifm_media) == IFM_homePNA) {
		dc_setcfg(sc, ifm->ifm_media);
		sc->dc_if_media = ifm->ifm_media;
	} else {
		dc_setcfg(sc, mii->mii_media_active);
		sc->dc_if_media = mii->mii_media_active;
	}

	return;
}

/*
 * Special support for DM9102A cards with HomePNA PHYs. Note:
 * with the Davicom DM9102A/DM9801 eval board that I have, it seems
 * to be impossible to talk to the management interface of the DM9801
 * PHY (its MDIO pin is not connected to anything). Consequently,
 * the driver has to just 'know' about the additional mode and deal
 * with it itself. *sigh*
 */
static void dc_miibus_mediainit(dev)
	device_t		dev;
{
	struct dc_softc		*sc;
	struct mii_data		*mii;
	struct ifmedia		*ifm;
	int			rev;

	rev = pci_read_config(dev, DC_PCI_CFRV, 4) & 0xFF;

	sc = device_get_softc(dev);
	mii = device_get_softc(sc->dc_miibus);
	ifm = &mii->mii_media;

	if (DC_IS_DAVICOM(sc) && rev >= DC_REVISION_DM9102A)
		ifmedia_add(ifm, IFM_ETHER|IFM_homePNA, 0, NULL);

	return;
}

#define DC_POLY		0xEDB88320
#define DC_BITS		9
#define DC_BITS_PNIC_II	7

static u_int32_t dc_crc_le(sc, addr)
	struct dc_softc		*sc;
	caddr_t			addr;
{
	u_int32_t		idx, bit, data, crc;

	/* Compute CRC for the address value. */
	crc = 0xFFFFFFFF; /* initial value */

	for (idx = 0; idx < 6; idx++) {
		for (data = *addr++, bit = 0; bit < 8; bit++, data >>= 1)
			crc = (crc >> 1) ^ (((crc ^ data) & 1) ? DC_POLY : 0);
	}

	/* The hash table on the PNIC II is only 128 bits wide. */
	if (DC_IS_PNICII(sc))
		return (crc & ((1 << DC_BITS_PNIC_II) - 1));

	return (crc & ((1 << DC_BITS) - 1));
}

/*
 * Calculate CRC of a multicast group address, return the lower 6 bits.
 */
static u_int32_t dc_crc_be(addr)
	caddr_t			addr;
{
	u_int32_t		crc, carry;
	int			i, j;
	u_int8_t		c;

	/* Compute CRC for the address value. */
	crc = 0xFFFFFFFF; /* initial value */

	for (i = 0; i < 6; i++) {
		c = *(addr + i);
		for (j = 0; j < 8; j++) {
			carry = ((crc & 0x80000000) ? 1 : 0) ^ (c & 0x01);
			crc <<= 1;
			c >>= 1;
			if (carry)
				crc = (crc ^ 0x04c11db6) | carry;
		}
	}

	/* return the filter bit position */
	return((crc >> 26) & 0x0000003F);
}

/*
 * 21143-style RX filter setup routine. Filter programming is done by
 * downloading a special setup frame into the TX engine. 21143, Macronix,
 * PNIC, PNIC II and Davicom chips are programmed this way.
 *
 * We always program the chip using 'hash perfect' mode, i.e. one perfect
 * address (our node address) and a 512-bit hash filter for multicast
 * frames. We also sneak the broadcast address into the hash filter since
 * we need that too.
 */
void dc_setfilt_21143(sc)
	struct dc_softc		*sc;
{
	struct dc_desc		*sframe;
	u_int32_t		h, *sp;
	struct ifmultiaddr	*ifma;
	struct ifnet		*ifp;
	int			i;

	ifp = &sc->arpcom.ac_if;

	i = sc->dc_cdata.dc_tx_prod;
	DC_INC(sc->dc_cdata.dc_tx_prod, DC_TX_LIST_CNT);
	sc->dc_cdata.dc_tx_cnt++;
	sframe = &sc->dc_ldata->dc_tx_list[i];
	sp = (u_int32_t *)&sc->dc_cdata.dc_sbuf;
	bzero((char *)sp, DC_SFRAME_LEN);

	sframe->dc_data = vtophys(&sc->dc_cdata.dc_sbuf);
	sframe->dc_ctl = DC_SFRAME_LEN | DC_TXCTL_SETUP | DC_TXCTL_TLINK |
	    DC_FILTER_HASHPERF | DC_TXCTL_FINT;

	sc->dc_cdata.dc_tx_chain[i] = (struct mbuf *)&sc->dc_cdata.dc_sbuf;

	/* If we want promiscuous mode, set the allframes bit. */
	if (ifp->if_flags & IFF_PROMISC)
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_RX_PROMISC);
	else
		DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_RX_PROMISC);

	if (ifp->if_flags & IFF_ALLMULTI)
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_RX_ALLMULTI);
	else
		DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_RX_ALLMULTI);

	for (ifma = ifp->if_multiaddrs.lh_first; ifma != NULL;
	    ifma = ifma->ifma_link.le_next) {
		if (ifma->ifma_addr->sa_family != AF_LINK)
			continue;
		h = dc_crc_le(sc,
		    LLADDR((struct sockaddr_dl *)ifma->ifma_addr));
		sp[h >> 4] |= 1 << (h & 0xF);
	}

	if (ifp->if_flags & IFF_BROADCAST) {
		h = dc_crc_le(sc, (caddr_t)&etherbroadcastaddr);
		sp[h >> 4] |= 1 << (h & 0xF);
	}

	/* Set our MAC address */
	sp[39] = ((u_int16_t *)sc->arpcom.ac_enaddr)[0];
	sp[40] = ((u_int16_t *)sc->arpcom.ac_enaddr)[1];
	sp[41] = ((u_int16_t *)sc->arpcom.ac_enaddr)[2];

	sframe->dc_status = DC_TXSTAT_OWN;
	CSR_WRITE_4(sc, DC_TXSTART, 0xFFFFFFFF);

	/*
	 * The PNIC takes an exceedingly long time to process its
	 * setup frame; wait 10ms after posting the setup frame
	 * before proceeding, just so it has time to swallow its
	 * medicine.
	 */
	DELAY(10000);

	ifp->if_timer = 5;

	return;
}

void dc_setfilt_admtek(sc)
	struct dc_softc		*sc;
{
	struct ifnet		*ifp;
	int			h = 0;
	u_int32_t		hashes[2] = { 0, 0 };
	struct ifmultiaddr	*ifma;

	ifp = &sc->arpcom.ac_if;

	/* Init our MAC address */
	CSR_WRITE_4(sc, DC_AL_PAR0, *(u_int32_t *)(&sc->arpcom.ac_enaddr[0]));
	CSR_WRITE_4(sc, DC_AL_PAR1, *(u_int32_t *)(&sc->arpcom.ac_enaddr[4]));

	/* If we want promiscuous mode, set the allframes bit. */
	if (ifp->if_flags & IFF_PROMISC)
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_RX_PROMISC);
	else
		DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_RX_PROMISC);

	if (ifp->if_flags & IFF_ALLMULTI)
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_RX_ALLMULTI);
	else
		DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_RX_ALLMULTI);

	/* first, zot all the existing hash bits */
	CSR_WRITE_4(sc, DC_AL_MAR0, 0);
	CSR_WRITE_4(sc, DC_AL_MAR1, 0);

	/*
	 * If we're already in promisc or allmulti mode, we
	 * don't have to bother programming the multicast filter.
	 */
	if (ifp->if_flags & (IFF_PROMISC|IFF_ALLMULTI))
		return;

	/* now program new ones */
	for (ifma = ifp->if_multiaddrs.lh_first; ifma != NULL;
	    ifma = ifma->ifma_link.le_next) {
		if (ifma->ifma_addr->sa_family != AF_LINK)
			continue;
		h = dc_crc_be(LLADDR((struct sockaddr_dl *)ifma->ifma_addr));
		if (h < 32)
			hashes[0] |= (1 << h);
		else
			hashes[1] |= (1 << (h - 32));
	}

	CSR_WRITE_4(sc, DC_AL_MAR0, hashes[0]);
	CSR_WRITE_4(sc, DC_AL_MAR1, hashes[1]);

	return;
}

void dc_setfilt_asix(sc)
	struct dc_softc		*sc;
{
	struct ifnet		*ifp;
	int			h = 0;
	u_int32_t		hashes[2] = { 0, 0 };
	struct ifmultiaddr	*ifma;

	ifp = &sc->arpcom.ac_if;

        /* Init our MAC address */
        CSR_WRITE_4(sc, DC_AX_FILTIDX, DC_AX_FILTIDX_PAR0);
        CSR_WRITE_4(sc, DC_AX_FILTDATA,
	    *(u_int32_t *)(&sc->arpcom.ac_enaddr[0]));
        CSR_WRITE_4(sc, DC_AX_FILTIDX, DC_AX_FILTIDX_PAR1);
        CSR_WRITE_4(sc, DC_AX_FILTDATA,
	    *(u_int32_t *)(&sc->arpcom.ac_enaddr[4]));

	/* If we want promiscuous mode, set the allframes bit. */
	if (ifp->if_flags & IFF_PROMISC)
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_RX_PROMISC);
	else
		DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_RX_PROMISC);

	if (ifp->if_flags & IFF_ALLMULTI)
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_RX_ALLMULTI);
	else
		DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_RX_ALLMULTI);

	/*
	 * The ASIX chip has a special bit to enable reception
	 * of broadcast frames.
	 */
	if (ifp->if_flags & IFF_BROADCAST)
		DC_SETBIT(sc, DC_NETCFG, DC_AX_NETCFG_RX_BROAD);
	else
		DC_CLRBIT(sc, DC_NETCFG, DC_AX_NETCFG_RX_BROAD);

	/* first, zot all the existing hash bits */
	CSR_WRITE_4(sc, DC_AX_FILTIDX, DC_AX_FILTIDX_MAR0);
	CSR_WRITE_4(sc, DC_AX_FILTDATA, 0);
	CSR_WRITE_4(sc, DC_AX_FILTIDX, DC_AX_FILTIDX_MAR1);
	CSR_WRITE_4(sc, DC_AX_FILTDATA, 0);

	/*
	 * If we're already in promisc or allmulti mode, we
	 * don't have to bother programming the multicast filter.
	 */
	if (ifp->if_flags & (IFF_PROMISC|IFF_ALLMULTI))
		return;

	/* now program new ones */
	for (ifma = ifp->if_multiaddrs.lh_first; ifma != NULL;
	    ifma = ifma->ifma_link.le_next) {
		if (ifma->ifma_addr->sa_family != AF_LINK)
			continue;
		h = dc_crc_be(LLADDR((struct sockaddr_dl *)ifma->ifma_addr));
		if (h < 32)
			hashes[0] |= (1 << h);
		else
			hashes[1] |= (1 << (h - 32));
	}

	CSR_WRITE_4(sc, DC_AX_FILTIDX, DC_AX_FILTIDX_MAR0);
	CSR_WRITE_4(sc, DC_AX_FILTDATA, hashes[0]);
	CSR_WRITE_4(sc, DC_AX_FILTIDX, DC_AX_FILTIDX_MAR1);
	CSR_WRITE_4(sc, DC_AX_FILTDATA, hashes[1]);

	return;
}

static void dc_setfilt(sc)
	struct dc_softc		*sc;
{
	if (DC_IS_INTEL(sc) || DC_IS_MACRONIX(sc) || DC_IS_PNIC(sc) ||
	    DC_IS_PNICII(sc) || DC_IS_DAVICOM(sc))
		dc_setfilt_21143(sc);

	if (DC_IS_ASIX(sc))
		dc_setfilt_asix(sc);

	if (DC_IS_ADMTEK(sc))
		dc_setfilt_admtek(sc);

	return;
}

/*
 * In order to fiddle with the
 * 'full-duplex' and '100Mbps' bits in the netconfig register, we
 * first have to put the transmit and/or receive logic in the idle state.
 */
static void dc_setcfg(sc, media)
	struct dc_softc		*sc;
	int			media;
{
	int			i, restart = 0;
	u_int32_t		isr;

	if (IFM_SUBTYPE(media) == IFM_NONE)
		return;

	if (CSR_READ_4(sc, DC_NETCFG) & (DC_NETCFG_TX_ON|DC_NETCFG_RX_ON)) {
		restart = 1;
		DC_CLRBIT(sc, DC_NETCFG, (DC_NETCFG_TX_ON|DC_NETCFG_RX_ON));

		for (i = 0; i < DC_TIMEOUT; i++) {
			DELAY(10);
			isr = CSR_READ_4(sc, DC_ISR);
			if (isr & DC_ISR_TX_IDLE ||
			    (isr & DC_ISR_RX_STATE) == DC_RXSTATE_STOPPED)
				break;
		}

		if (i == DC_TIMEOUT)
			printf("dc%d: failed to force tx and "
				"rx to idle state\n", sc->dc_unit);

	}

	if (IFM_SUBTYPE(media) == IFM_100_TX) {
		DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_SPEEDSEL);
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_HEARTBEAT);
		if (sc->dc_pmode == DC_PMODE_MII) {
			DC_SETBIT(sc, DC_WATCHDOG, DC_WDOG_JABBERDIS);
			DC_CLRBIT(sc, DC_NETCFG, (DC_NETCFG_PCS|
			    DC_NETCFG_PORTSEL|DC_NETCFG_SCRAMBLER));
			if (sc->dc_type == DC_TYPE_98713)
				DC_SETBIT(sc, DC_NETCFG, (DC_NETCFG_PCS|
				    DC_NETCFG_SCRAMBLER));
			if (!DC_IS_DAVICOM(sc))
				DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_PORTSEL);
			DC_CLRBIT(sc, DC_10BTCTRL, 0xFFFF);
		} else {
			if (DC_IS_PNIC(sc)) {
				DC_PN_GPIO_SETBIT(sc, DC_PN_GPIO_SPEEDSEL);
				DC_PN_GPIO_SETBIT(sc, DC_PN_GPIO_100TX_LOOP);
				DC_SETBIT(sc, DC_PN_NWAY, DC_PN_NWAY_SPEEDSEL);
			}
			DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_PORTSEL|
			    DC_NETCFG_PCS|DC_NETCFG_SCRAMBLER);
		}
	}

	if (IFM_SUBTYPE(media) == IFM_10_T) {
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_SPEEDSEL);
		DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_HEARTBEAT);
		if (sc->dc_pmode == DC_PMODE_MII) {
			DC_SETBIT(sc, DC_WATCHDOG, DC_WDOG_JABBERDIS);
			DC_CLRBIT(sc, DC_NETCFG, (DC_NETCFG_PCS|
			    DC_NETCFG_PORTSEL|DC_NETCFG_SCRAMBLER));
			if (sc->dc_type == DC_TYPE_98713)
				DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_PCS);
			if (!DC_IS_DAVICOM(sc))
				DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_PORTSEL);
			DC_CLRBIT(sc, DC_10BTCTRL, 0xFFFF);
		} else {
			if (DC_IS_PNIC(sc)) {
				DC_PN_GPIO_CLRBIT(sc, DC_PN_GPIO_SPEEDSEL);
				DC_PN_GPIO_SETBIT(sc, DC_PN_GPIO_100TX_LOOP);
				DC_CLRBIT(sc, DC_PN_NWAY, DC_PN_NWAY_SPEEDSEL);
			}
			DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_PORTSEL);
			DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_SCRAMBLER);
			DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_PCS);
		}
	}

	/*
	 * If this is a Davicom DM9102A card with a DM9801 HomePNA
	 * PHY and we want HomePNA mode, set the portsel bit to turn
	 * on the external MII port.
	 */
	if (DC_IS_DAVICOM(sc)) {
		if (IFM_SUBTYPE(media) == IFM_homePNA) {
			DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_PORTSEL);
			sc->dc_link = 1;
		} else {
			DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_PORTSEL);
		}
	}

	if ((media & IFM_GMASK) == IFM_FDX) {
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_FULLDUPLEX);
		if (sc->dc_pmode == DC_PMODE_SYM && DC_IS_PNIC(sc))
			DC_SETBIT(sc, DC_PN_NWAY, DC_PN_NWAY_DUPLEX);
	} else {
		DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_FULLDUPLEX);
		if (sc->dc_pmode == DC_PMODE_SYM && DC_IS_PNIC(sc))
			DC_CLRBIT(sc, DC_PN_NWAY, DC_PN_NWAY_DUPLEX);
	}

	if (restart)
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_TX_ON|DC_NETCFG_RX_ON);

	return;
}

static void dc_reset(sc)
	struct dc_softc		*sc;
{
	register int		i;

	DC_SETBIT(sc, DC_BUSCTL, DC_BUSCTL_RESET);

	for (i = 0; i < DC_TIMEOUT; i++) {
		DELAY(10);
		if (!(CSR_READ_4(sc, DC_BUSCTL) & DC_BUSCTL_RESET))
			break;
	}

	if (DC_IS_ASIX(sc) || DC_IS_ADMTEK(sc)) {
		DELAY(10000);
		DC_CLRBIT(sc, DC_BUSCTL, DC_BUSCTL_RESET);
		i = 0;
	}

	if (i == DC_TIMEOUT)
		printf("dc%d: reset never completed!\n", sc->dc_unit);

	/* Wait a little while for the chip to get its brains in order. */
	DELAY(1000);

	CSR_WRITE_4(sc, DC_IMR, 0x00000000);
	CSR_WRITE_4(sc, DC_BUSCTL, 0x00000000);
	CSR_WRITE_4(sc, DC_NETCFG, 0x00000000);

	/*
	 * Bring the SIA out of reset. In some cases, it looks
	 * like failing to unreset the SIA soon enough gets it
	 * into a state where it will never come out of reset
	 * until we reset the whole chip again.
	 */
	if (DC_IS_INTEL(sc))
		DC_SETBIT(sc, DC_SIARESET, DC_SIA_RESET);

        return;
}

static struct dc_type *dc_devtype(dev)
	device_t		dev;
{
	struct dc_type		*t;
	u_int32_t		rev;

	t = dc_devs;

	while(t->dc_name != NULL) {
		if ((pci_get_vendor(dev) == t->dc_vid) &&
		    (pci_get_device(dev) == t->dc_did)) {
			/* Check the PCI revision */
			rev = pci_read_config(dev, DC_PCI_CFRV, 4) & 0xFF;
			if (t->dc_did == DC_DEVICEID_98713 &&
			    rev >= DC_REVISION_98713A)
				t++;
			if (t->dc_did == DC_DEVICEID_98713_CP &&
			    rev >= DC_REVISION_98713A)
				t++;
			if (t->dc_did == DC_DEVICEID_987x5 &&
			    rev >= DC_REVISION_98725)
				t++;
			if (t->dc_did == DC_DEVICEID_AX88140A &&
			    rev >= DC_REVISION_88141)
				t++;
			if (t->dc_did == DC_DEVICEID_82C168 &&
			    rev >= DC_REVISION_82C169)
				t++;
			if (t->dc_did == DC_DEVICEID_DM9102 &&
			    rev >= DC_REVISION_DM9102A)
				t++;
			return(t);
		}
		t++;
	}

	return(NULL);
}

/*
 * Probe for a 21143 or clone chip. Check the PCI vendor and device
 * IDs against our list and return a device name if we find a match.
 * We do a little bit of extra work to identify the exact type of
 * chip. The MX98713 and MX98713A have the same PCI vendor/device ID,
 * but different revision IDs. The same is true for 98715/98715A
 * chips and the 98725, as well as the ASIX and ADMtek chips. In some
 * cases, the exact chip revision affects driver behavior.
 */
static int dc_probe(dev)
	device_t		dev;
{
	struct dc_type		*t;

	t = dc_devtype(dev);

	if (t != NULL) {
		device_set_desc(dev, t->dc_name);
		return(0);
	}

	return(ENXIO);
}

static void dc_acpi(dev)
	device_t		dev;
{
	u_int32_t		r, cptr;
	int			unit;

	unit = device_get_unit(dev);

	/* Find the location of the capabilities block */
	cptr = pci_read_config(dev, DC_PCI_CCAP, 4) & 0xFF;

	r = pci_read_config(dev, cptr, 4) & 0xFF;
	if (r == 0x01) {

		r = pci_read_config(dev, cptr + 4, 4);
		if (r & DC_PSTATE_D3) {
			u_int32_t		iobase, membase, irq;

			/* Save important PCI config data. */
			iobase = pci_read_config(dev, DC_PCI_CFBIO, 4);
			membase = pci_read_config(dev, DC_PCI_CFBMA, 4);
			irq = pci_read_config(dev, DC_PCI_CFIT, 4);

			/* Reset the power state. */
			printf("dc%d: chip is in D%d power mode "
			    "-- setting to D0\n", unit, r & DC_PSTATE_D3);
			r &= 0xFFFFFFFC;
			pci_write_config(dev, cptr + 4, r, 4);

			/* Restore PCI config data. */
			pci_write_config(dev, DC_PCI_CFBIO, iobase, 4);
			pci_write_config(dev, DC_PCI_CFBMA, membase, 4);
			pci_write_config(dev, DC_PCI_CFIT, irq, 4);
		}
	}
	return;
}

/*
 * Attach the interface. Allocate softc structures, do ifmedia
 * setup and ethernet/BPF attach.
 */
static int dc_attach(dev)
	device_t		dev;
{
	int			s;
	u_char			eaddr[ETHER_ADDR_LEN];
	u_int32_t		command;
	struct dc_softc		*sc;
	struct ifnet		*ifp;
	u_int32_t		revision;
	int			unit, error = 0, rid, mac_offset;

	s = splimp();

	sc = device_get_softc(dev);
	unit = device_get_unit(dev);
	bzero(sc, sizeof(struct dc_softc));

	/*
	 * Handle power management nonsense.
	 */
	dc_acpi(dev);

	/*
	 * Map control/status registers.
	 */
	command = pci_read_config(dev, PCI_COMMAND_STATUS_REG, 4);
	command |= (PCIM_CMD_PORTEN|PCIM_CMD_MEMEN|PCIM_CMD_BUSMASTEREN);
	pci_write_config(dev, PCI_COMMAND_STATUS_REG, command, 4);
	command = pci_read_config(dev, PCI_COMMAND_STATUS_REG, 4);

#ifdef DC_USEIOSPACE
	if (!(command & PCIM_CMD_PORTEN)) {
		printf("dc%d: failed to enable I/O ports!\n", unit);
		error = ENXIO;
		goto fail;
	}
#else
	if (!(command & PCIM_CMD_MEMEN)) {
		printf("dc%d: failed to enable memory mapping!\n", unit);
		error = ENXIO;
		goto fail;
	}
#endif

	rid = DC_RID;
	sc->dc_res = bus_alloc_resource(dev, DC_RES, &rid,
	    0, ~0, 1, RF_ACTIVE);

	if (sc->dc_res == NULL) {
		printf("dc%d: couldn't map ports/memory\n", unit);
		error = ENXIO;
		goto fail;
	}

	sc->dc_btag = rman_get_bustag(sc->dc_res);
	sc->dc_bhandle = rman_get_bushandle(sc->dc_res);

	/* Allocate interrupt */
	rid = 0;
	sc->dc_irq = bus_alloc_resource(dev, SYS_RES_IRQ, &rid, 0, ~0, 1,
	    RF_SHAREABLE | RF_ACTIVE);

	if (sc->dc_irq == NULL) {
		printf("dc%d: couldn't map interrupt\n", unit);
		bus_release_resource(dev, DC_RES, DC_RID, sc->dc_res);
		error = ENXIO;
		goto fail;
	}

	error = bus_setup_intr(dev, sc->dc_irq, INTR_TYPE_NET,
	    dc_intr, sc, &sc->dc_intrhand);

	if (error) {
		bus_release_resource(dev, SYS_RES_IRQ, 0, sc->dc_irq);
		bus_release_resource(dev, DC_RES, DC_RID, sc->dc_res);
		printf("dc%d: couldn't set up irq\n", unit);
		goto fail;
	}

	/* Need this info to decide on a chip type. */
	sc->dc_info = dc_devtype(dev);
	revision = pci_read_config(dev, DC_PCI_CFRV, 4) & 0x000000FF;

	switch(sc->dc_info->dc_did) {
	case DC_DEVICEID_21143:
		sc->dc_type = DC_TYPE_21143;
		sc->dc_flags |= DC_TX_POLL|DC_TX_USE_TX_INTR;
		sc->dc_flags |= DC_REDUCED_MII_POLL;
		break;
	case DC_DEVICEID_DM9100:
	case DC_DEVICEID_DM9102:
		sc->dc_type = DC_TYPE_DM9102;
		sc->dc_flags |= DC_TX_COALESCE|DC_TX_USE_TX_INTR;
		sc->dc_flags |= DC_REDUCED_MII_POLL;
		sc->dc_pmode = DC_PMODE_MII;
		break;
	case DC_DEVICEID_AL981:
		sc->dc_type = DC_TYPE_AL981;
		sc->dc_flags |= DC_TX_USE_TX_INTR;
		sc->dc_flags |= DC_TX_ADMTEK_WAR;
		sc->dc_pmode = DC_PMODE_MII;
		break;
	case DC_DEVICEID_AN985:
		sc->dc_type = DC_TYPE_AN985;
		sc->dc_flags |= DC_TX_USE_TX_INTR;
		sc->dc_flags |= DC_TX_ADMTEK_WAR;
		sc->dc_pmode = DC_PMODE_MII;
		break;
	case DC_DEVICEID_98713:
	case DC_DEVICEID_98713_CP:
		if (revision < DC_REVISION_98713A) {
			sc->dc_type = DC_TYPE_98713;
			sc->dc_flags |= DC_REDUCED_MII_POLL;
		}
		if (revision >= DC_REVISION_98713A)
			sc->dc_type = DC_TYPE_98713A;
		sc->dc_flags |= DC_TX_POLL|DC_TX_USE_TX_INTR;
		break;
	case DC_DEVICEID_987x5:
		sc->dc_type = DC_TYPE_987x5;
		sc->dc_flags |= DC_TX_POLL|DC_TX_USE_TX_INTR;
		break;
	case DC_DEVICEID_82C115:
		sc->dc_type = DC_TYPE_PNICII;
		sc->dc_flags |= DC_TX_POLL|DC_TX_USE_TX_INTR;
		break;
	case DC_DEVICEID_82C168:
		sc->dc_type = DC_TYPE_PNIC;
		sc->dc_flags |= DC_TX_STORENFWD|DC_TX_INTR_ALWAYS;
		sc->dc_flags |= DC_PNIC_RX_BUG_WAR;
		sc->dc_pnic_rx_buf = malloc(DC_RXLEN * 5, M_DEVBUF, M_NOWAIT);
		if (revision < DC_REVISION_82C169)
			sc->dc_pmode = DC_PMODE_SYM;
		break;
	case DC_DEVICEID_AX88140A:
		sc->dc_type = DC_TYPE_ASIX;
		sc->dc_flags |= DC_TX_USE_TX_INTR|DC_TX_INTR_FIRSTFRAG;
		sc->dc_flags |= DC_REDUCED_MII_POLL;
		sc->dc_pmode = DC_PMODE_MII;
		break;
	default:
		printf("dc%d: unknown device: %x\n", sc->dc_unit,
		    sc->dc_info->dc_did);
		break;
	}

	/* Save the cache line size. */
	if (DC_IS_DAVICOM(sc))
		sc->dc_cachesize = 0;
	else
		sc->dc_cachesize = pci_read_config(dev,
		    DC_PCI_CFLT, 4) & 0xFF;

	/* Reset the adapter. */
	dc_reset(sc);

	/* Take 21143 out of snooze mode */
	if (DC_IS_INTEL(sc)) {
		command = pci_read_config(dev, DC_PCI_CFDD, 4);
		command &= ~(DC_CFDD_SNOOZE_MODE|DC_CFDD_SLEEP_MODE);
		pci_write_config(dev, DC_PCI_CFDD, command, 4);
	}

	/*
	 * Try to learn something about the supported media.
	 * We know that ASIX and ADMtek and Davicom devices
	 * will *always* be using MII media, so that's a no-brainer.
	 * The tricky ones are the Macronix/PNIC II and the
	 * Intel 21143.
	 */
	if (DC_IS_INTEL(sc)) {
		u_int32_t		media, cwuc;
		cwuc = pci_read_config(dev, DC_PCI_CWUC, 4);
		cwuc |= DC_CWUC_FORCE_WUL;
		pci_write_config(dev, DC_PCI_CWUC, cwuc, 4);
		DELAY(10000);
		media = pci_read_config(dev, DC_PCI_CWUC, 4);
		cwuc &= ~DC_CWUC_FORCE_WUL;
		pci_write_config(dev, DC_PCI_CWUC, cwuc, 4);
		DELAY(10000);
		if (media & DC_CWUC_MII_ABILITY)
			sc->dc_pmode = DC_PMODE_MII;
		if (media & DC_CWUC_SYM_ABILITY)
			sc->dc_pmode = DC_PMODE_SYM;
		/*
		 * If none of the bits are set, then this NIC
		 * isn't meant to support 'wake up LAN' mode.
		 * This is usually only the case on multiport
		 * cards, and these cards almost always have
		 * MII transceivers.
		 */
		if (media == 0)
			sc->dc_pmode = DC_PMODE_MII;
	} else if (DC_IS_MACRONIX(sc) || DC_IS_PNICII(sc)) {
		if (sc->dc_type == DC_TYPE_98713)
			sc->dc_pmode = DC_PMODE_MII;
		else
			sc->dc_pmode = DC_PMODE_SYM;
	} else if (!sc->dc_pmode)
		sc->dc_pmode = DC_PMODE_MII;

	/*
	 * Get station address from the EEPROM.
	 */
	switch(sc->dc_type) {
	case DC_TYPE_98713:
	case DC_TYPE_98713A:
	case DC_TYPE_987x5:
	case DC_TYPE_PNICII:
		dc_read_eeprom(sc, (caddr_t)&mac_offset,
		    (DC_EE_NODEADDR_OFFSET / 2), 1, 0);
		dc_read_eeprom(sc, (caddr_t)&eaddr, (mac_offset / 2), 3, 0);
		break;
	case DC_TYPE_PNIC:
		dc_read_eeprom(sc, (caddr_t)&eaddr, 0, 3, 1);
		break;
	case DC_TYPE_DM9102:
	case DC_TYPE_21143:
	case DC_TYPE_ASIX:
		dc_read_eeprom(sc, (caddr_t)&eaddr, DC_EE_NODEADDR, 3, 0);
		break;
	case DC_TYPE_AL981:
	case DC_TYPE_AN985:
		dc_read_eeprom(sc, (caddr_t)&eaddr, DC_AL_EE_NODEADDR, 3, 0);
		break;
	default:
		dc_read_eeprom(sc, (caddr_t)&eaddr, DC_EE_NODEADDR, 3, 0);
		break;
	}

	/*
	 * A 21143 or clone chip was detected. Inform the world.
	 */
	printf("dc%d: Ethernet address: %6D\n", unit, eaddr, ":");

	sc->dc_unit = unit;
	bcopy(eaddr, (char *)&sc->arpcom.ac_enaddr, ETHER_ADDR_LEN);

	sc->dc_ldata = contigmalloc(sizeof(struct dc_list_data), M_DEVBUF,
	    M_NOWAIT, 0, 0xffffffff, PAGE_SIZE, 0);

	if (sc->dc_ldata == NULL) {
		printf("dc%d: no memory for list buffers!\n", unit);
		bus_teardown_intr(dev, sc->dc_irq, sc->dc_intrhand);
		bus_release_resource(dev, SYS_RES_IRQ, 0, sc->dc_irq);
		bus_release_resource(dev, DC_RES, DC_RID, sc->dc_res);
		error = ENXIO;
		goto fail;
	}

	bzero(sc->dc_ldata, sizeof(struct dc_list_data));

	ifp = &sc->arpcom.ac_if;
	ifp->if_softc = sc;
	ifp->if_unit = unit;
	ifp->if_name = "dc";
	ifp->if_mtu = ETHERMTU;
	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
	ifp->if_ioctl = dc_ioctl;
	ifp->if_output = ether_output;
	ifp->if_start = dc_start;
	ifp->if_watchdog = dc_watchdog;
	ifp->if_init = dc_init;
	ifp->if_baudrate = 10000000;
	ifp->if_snd.ifq_maxlen = DC_TX_LIST_CNT - 1;

	/*
	 * Do MII setup.
	 */
	error = mii_phy_probe(dev, &sc->dc_miibus,
	    dc_ifmedia_upd, dc_ifmedia_sts);

	if (error && DC_IS_INTEL(sc)) {
		sc->dc_pmode = DC_PMODE_SYM;
		mii_phy_probe(dev, &sc->dc_miibus,
		    dc_ifmedia_upd, dc_ifmedia_sts);
		error = 0;
	}

	if (error) {
		printf("dc%d: MII without any PHY!\n", sc->dc_unit);
		bus_teardown_intr(dev, sc->dc_irq, sc->dc_intrhand);
		bus_release_resource(dev, SYS_RES_IRQ, 0, sc->dc_irq);
		bus_release_resource(dev, DC_RES, DC_RID, sc->dc_res);
		error = ENXIO;
		goto fail;
	}

	/*
	 * Call MI attach routines.
	 */
	if_attach(ifp);
	ether_ifattach(ifp);
	callout_handle_init(&sc->dc_stat_ch);

	bpfattach(ifp, DLT_EN10MB, sizeof(struct ether_header));

#ifdef __alpha__
        sc->dc_srm_media = 0;

	/* Remember the SRM console media setting */
	if (DC_IS_INTEL(sc)) {
		command = pci_read_config(dev, DC_PCI_CFDD, 4);
		command &= ~(DC_CFDD_SNOOZE_MODE|DC_CFDD_SLEEP_MODE);
		switch ((command >> 8) & 0xff) {
		case 3:
			sc->dc_srm_media = IFM_10_T;
			break;
		case 4:
			sc->dc_srm_media = IFM_10_T | IFM_FDX;
			break;
		case 5:
			sc->dc_srm_media = IFM_100_TX;
			break;
		case 6:
			sc->dc_srm_media = IFM_100_TX | IFM_FDX;
			break;
		}
		if (sc->dc_srm_media)
			sc->dc_srm_media |= IFM_ACTIVE | IFM_ETHER;
	}
#endif


fail:
	splx(s);

	return(error);
}

static int dc_detach(dev)
	device_t		dev;
{
	struct dc_softc		*sc;
	struct ifnet		*ifp;
	int			s;

	s = splimp();

	sc = device_get_softc(dev);
	ifp = &sc->arpcom.ac_if;

	dc_stop(sc);
	if_detach(ifp);

	bus_generic_detach(dev);
	device_delete_child(dev, sc->dc_miibus);

	bus_teardown_intr(dev, sc->dc_irq, sc->dc_intrhand);
	bus_release_resource(dev, SYS_RES_IRQ, 0, sc->dc_irq);
	bus_release_resource(dev, DC_RES, DC_RID, sc->dc_res);

	contigfree(sc->dc_ldata, sizeof(struct dc_list_data), M_DEVBUF);
	if (sc->dc_pnic_rx_buf != NULL)
		free(sc->dc_pnic_rx_buf, M_DEVBUF);

	splx(s);

	return(0);
}

/*
 * Initialize the transmit descriptors.
 */
static int dc_list_tx_init(sc)
	struct dc_softc		*sc;
{
	struct dc_chain_data	*cd;
	struct dc_list_data	*ld;
	int			i;

	cd = &sc->dc_cdata;
	ld = sc->dc_ldata;
	for (i = 0; i < DC_TX_LIST_CNT; i++) {
		if (i == (DC_TX_LIST_CNT - 1)) {
			ld->dc_tx_list[i].dc_next =
			    vtophys(&ld->dc_tx_list[0]);
		} else {
			ld->dc_tx_list[i].dc_next =
			    vtophys(&ld->dc_tx_list[i + 1]);
		}
		cd->dc_tx_chain[i] = NULL;
		ld->dc_tx_list[i].dc_data = 0;
		ld->dc_tx_list[i].dc_ctl = 0;
	}

	cd->dc_tx_prod = cd->dc_tx_cons = cd->dc_tx_cnt = 0;

	return(0);
}


/*
 * Initialize the RX descriptors and allocate mbufs for them. Note that
 * we arrange the descriptors in a closed ring, so that the last descriptor
 * points back to the first.
 */
static int dc_list_rx_init(sc)
	struct dc_softc		*sc;
{
	struct dc_chain_data	*cd;
	struct dc_list_data	*ld;
	int			i;

	cd = &sc->dc_cdata;
	ld = sc->dc_ldata;

	for (i = 0; i < DC_RX_LIST_CNT; i++) {
		if (dc_newbuf(sc, i, NULL) == ENOBUFS)
			return(ENOBUFS);
		if (i == (DC_RX_LIST_CNT - 1)) {
			ld->dc_rx_list[i].dc_next =
			    vtophys(&ld->dc_rx_list[0]);
		} else {
			ld->dc_rx_list[i].dc_next =
			    vtophys(&ld->dc_rx_list[i + 1]);
		}
	}

	cd->dc_rx_prod = 0;

	return(0);
}

/*
 * Initialize an RX descriptor and attach an MBUF cluster.
 */
static int dc_newbuf(sc, i, m)
	struct dc_softc		*sc;
	int			i;
	struct mbuf		*m;
{
	struct mbuf		*m_new = NULL;
	struct dc_desc		*c;

	c = &sc->dc_ldata->dc_rx_list[i];

	if (m == NULL) {
		MGETHDR(m_new, M_DONTWAIT, MT_DATA);
		if (m_new == NULL) {
			printf("dc%d: no memory for rx list "
			    "-- packet dropped!\n", sc->dc_unit);
			return(ENOBUFS);
		}

		MCLGET(m_new, M_DONTWAIT);
		if (!(m_new->m_flags & M_EXT)) {
			printf("dc%d: no memory for rx list "
			    "-- packet dropped!\n", sc->dc_unit);
			m_freem(m_new);
			return(ENOBUFS);
		}
		m_new->m_len = m_new->m_pkthdr.len = MCLBYTES;
	} else {
		m_new = m;
		m_new->m_len = m_new->m_pkthdr.len = MCLBYTES;
		m_new->m_data = m_new->m_ext.ext_buf;
	}

	m_adj(m_new, sizeof(u_int64_t));

	/*
	 * If this is a PNIC chip, zero the buffer. This is part
	 * of the workaround for the receive bug in the 82c168 and
	 * 82c169 chips.
	 */
	if (sc->dc_flags & DC_PNIC_RX_BUG_WAR)
		bzero((char *)mtod(m_new, char *), m_new->m_len);

	sc->dc_cdata.dc_rx_chain[i] = m_new;
	c->dc_data = vtophys(mtod(m_new, caddr_t));
	c->dc_ctl = DC_RXCTL_RLINK | DC_RXLEN;
	c->dc_status = DC_RXSTAT_OWN;

	return(0);
}

/*
 * Grrrrr.
 * The PNIC chip has a terrible bug in it that manifests itself during
 * periods of heavy activity. The exact mode of failure if difficult to
 * pinpoint: sometimes it only happens in promiscuous mode, sometimes it
 * will happen on slow machines. The bug is that sometimes instead of
 * uploading one complete frame during reception, it uploads what looks
 * like the entire contents of its FIFO memory. The frame we want is at
 * the end of the whole mess, but we never know exactly how much data has
 * been uploaded, so salvaging the frame is hard.
 *
 * There is only one way to do it reliably, and it's disgusting.
 * Here's what we know:
 *
 * - We know there will always be somewhere between one and three extra
 *   descriptors uploaded.
 *
 * - We know the desired received frame will always be at the end of the
 *   total data upload.
 *
 * - We know the size of the desired received frame because it will be
 *   provided in the length field of the status word in the last descriptor.
 *
 * Here's what we do:
 *
 * - When we allocate buffers for the receive ring, we bzero() them.
 *   This means that we know that the buffer contents should be all
 *   zeros, except for data uploaded by the chip.
 *
 * - We also force the PNIC chip to upload frames that include the
 *   ethernet CRC at the end.
 *
 * - We gather all of the bogus frame data into a single buffer.
 *
 * - We then position a pointer at the end of this buffer and scan
 *   backwards until we encounter the first non-zero byte of data.
 *   This is the end of the received frame. We know we will encounter
 *   some data at the end of the frame because the CRC will always be
 *   there, so even if the sender transmits a packet of all zeros,
 *   we won't be fooled.
 *
 * - We know the size of the actual received frame, so we subtract
 *   that value from the current pointer location. This brings us
 *   to the start of the actual received packet.
 *
 * - We copy this into an mbuf and pass it on, along with the actual
 *   frame length.
 *
 * The performance hit is tremendous, but it beats dropping frames all
 * the time.
 */

#define DC_WHOLEFRAME	(DC_RXSTAT_FIRSTFRAG|DC_RXSTAT_LASTFRAG)
static void dc_pnic_rx_bug_war(sc, idx)
	struct dc_softc		*sc;
	int			idx;
{
	struct dc_desc		*cur_rx;
	struct dc_desc		*c = NULL;
	struct mbuf		*m = NULL;
	unsigned char		*ptr;
	int			i, total_len;
	u_int32_t		rxstat = 0;

	i = sc->dc_pnic_rx_bug_save;
	cur_rx = &sc->dc_ldata->dc_rx_list[idx];
	ptr = sc->dc_pnic_rx_buf;
	bzero(ptr, sizeof(DC_RXLEN * 5));

	/* Copy all the bytes from the bogus buffers. */
	while (1) {
		c = &sc->dc_ldata->dc_rx_list[i];
		rxstat = c->dc_status;
		m = sc->dc_cdata.dc_rx_chain[i];
		bcopy(mtod(m, char *), ptr, DC_RXLEN);
		ptr += DC_RXLEN;
		/* If this is the last buffer, break out. */
		if (i == idx || rxstat & DC_RXSTAT_LASTFRAG)
			break;
		dc_newbuf(sc, i, m);
		DC_INC(i, DC_RX_LIST_CNT);
	}

	/* Find the length of the actual receive frame. */
	total_len = DC_RXBYTES(rxstat);

	/* Scan backwards until we hit a non-zero byte. */
	while(*ptr == 0x00)
		ptr--;

	/* Round off. */
	if ((uintptr_t)(ptr) & 0x3)
		ptr -= 1;

	/* Now find the start of the frame. */
	ptr -= total_len;
	if (ptr < sc->dc_pnic_rx_buf)
		ptr = sc->dc_pnic_rx_buf;

	/*
	 * Now copy the salvaged frame to the last mbuf and fake up
	 * the status word to make it look like a successful
 	 * frame reception.
	 */
	dc_newbuf(sc, i, m);
	bcopy(ptr, mtod(m, char *), total_len);
	cur_rx->dc_status = rxstat | DC_RXSTAT_FIRSTFRAG;

	return;
}

/*
 * This routine searches the RX ring for dirty descriptors in the
 * event that the rxeof routine falls out of sync with the chip's
 * current descriptor pointer. This may happen sometimes as a result
 * of a "no RX buffer available" condition that happens when the chip
 * consumes all of the RX buffers before the driver has a chance to
 * process the RX ring. This routine may need to be called more than
 * once to bring the driver back in sync with the chip, however we
 * should still be getting RX DONE interrupts to drive the search
 * for new packets in the RX ring, so we should catch up eventually.
 */
static int dc_rx_resync(sc)
	struct dc_softc		*sc;
{
	int			i, pos;
	struct dc_desc		*cur_rx;

	pos = sc->dc_cdata.dc_rx_prod;

	for (i = 0; i < DC_RX_LIST_CNT; i++) {
		cur_rx = &sc->dc_ldata->dc_rx_list[pos];
		if (!(cur_rx->dc_status & DC_RXSTAT_OWN))
			break;
		DC_INC(pos, DC_RX_LIST_CNT);
	}

	/* If the ring really is empty, then just return. */
	if (i == DC_RX_LIST_CNT)
		return(0);

	/* We've fallen behing the chip: catch it. */
	sc->dc_cdata.dc_rx_prod = pos;

	return(EAGAIN);
}

/*
 * A frame has been uploaded: pass the resulting mbuf chain up to
 * the higher level protocols.
 */
static void dc_rxeof(sc)
	struct dc_softc		*sc;
{
        struct ether_header	*eh;
        struct mbuf		*m;
        struct ifnet		*ifp;
	struct dc_desc		*cur_rx;
	int			i, total_len = 0;
	u_int32_t		rxstat;

	ifp = &sc->arpcom.ac_if;
	i = sc->dc_cdata.dc_rx_prod;

	while(!(sc->dc_ldata->dc_rx_list[i].dc_status & DC_RXSTAT_OWN)) {
		struct mbuf		*m0 = NULL;

		cur_rx = &sc->dc_ldata->dc_rx_list[i];
		rxstat = cur_rx->dc_status;
		m = sc->dc_cdata.dc_rx_chain[i];
		total_len = DC_RXBYTES(rxstat);

		if (sc->dc_flags & DC_PNIC_RX_BUG_WAR) {
			if ((rxstat & DC_WHOLEFRAME) != DC_WHOLEFRAME) {
				if (rxstat & DC_RXSTAT_FIRSTFRAG)
					sc->dc_pnic_rx_bug_save = i;
				if ((rxstat & DC_RXSTAT_LASTFRAG) == 0) {
					DC_INC(i, DC_RX_LIST_CNT);
					continue;
				}
				dc_pnic_rx_bug_war(sc, i);
				rxstat = cur_rx->dc_status;
				total_len = DC_RXBYTES(rxstat);
			}
		}

		sc->dc_cdata.dc_rx_chain[i] = NULL;

		/*
		 * If an error occurs, update stats, clear the
		 * status word and leave the mbuf cluster in place:
		 * it should simply get re-used next time this descriptor
	 	 * comes up in the ring.
		 */
		if (rxstat & DC_RXSTAT_RXERR) {
			ifp->if_ierrors++;
			if (rxstat & DC_RXSTAT_COLLSEEN)
				ifp->if_collisions++;
			dc_newbuf(sc, i, m);
			if (rxstat & DC_RXSTAT_CRCERR) {
				DC_INC(i, DC_RX_LIST_CNT);
				continue;
			} else {
				dc_init(sc);
				return;
			}
		}

		/* No errors; receive the packet. */
		total_len -= ETHER_CRC_LEN;

		m0 = m_devget(mtod(m, char *) - ETHER_ALIGN,
		    total_len + ETHER_ALIGN, 0, ifp, NULL);
		dc_newbuf(sc, i, m);
		DC_INC(i, DC_RX_LIST_CNT);
		if (m0 == NULL) {
			ifp->if_ierrors++;
			continue;
		}
		m_adj(m0, ETHER_ALIGN);
		m = m0;

		ifp->if_ipackets++;
		eh = mtod(m, struct ether_header *);

		/* Handle BPF listeners. Let the BPF user see the packet */
		if (ifp->if_bpf)
			bpf_mtap(ifp, m);

#ifdef BRIDGE
		if (do_bridge) {
			struct ifnet *bdg_ifp ;
			bdg_ifp = bridge_in(m);
			if (bdg_ifp != BDG_LOCAL && bdg_ifp != BDG_DROP)
				bdg_forward(&m, bdg_ifp);
			if (((bdg_ifp != BDG_LOCAL) && (bdg_ifp != BDG_BCAST) &&			    (bdg_ifp != BDG_MCAST)) || bdg_ifp == BDG_DROP) {
				m_freem(m);
				continue;
			}
		}

	eh = mtod(m, struct ether_header *);
#endif

		/* Don't pass it up to the ether_input() layer unless it's
		 * a broadcast packet, multicast packet, matches our ethernet
		 * address or the interface is in promiscuous mode.
		 */
		if (ifp->if_bpf) {
			if (ifp->if_flags & IFF_PROMISC &&
				(bcmp(eh->ether_dhost, sc->arpcom.ac_enaddr,
				    ETHER_ADDR_LEN) &&
				    (eh->ether_dhost[0] & 1) == 0)) {
				m_freem(m);
				continue;
			}
		}

		/* Remove header from mbuf and pass it on. */
		m_adj(m, sizeof(struct ether_header));
		ether_input(ifp, eh, m);
	}

	sc->dc_cdata.dc_rx_prod = i;

	return;
}

/*
 * A frame was downloaded to the chip. It's safe for us to clean up
 * the list buffers.
 */

static void dc_txeof(sc)
	struct dc_softc		*sc;
{
	struct dc_desc		*cur_tx = NULL;
	struct ifnet		*ifp;
	int			idx;

	ifp = &sc->arpcom.ac_if;

	/* Clear the timeout timer. */
	ifp->if_timer = 0;

	/*
	 * Go through our tx list and free mbufs for those
	 * frames that have been transmitted.
	 */
	idx = sc->dc_cdata.dc_tx_cons;
	while(idx != sc->dc_cdata.dc_tx_prod) {
		u_int32_t		txstat;

		cur_tx = &sc->dc_ldata->dc_tx_list[idx];
		txstat = cur_tx->dc_status;

		if (txstat & DC_TXSTAT_OWN)
			break;

		if (!(cur_tx->dc_ctl & DC_TXCTL_LASTFRAG) ||
		    cur_tx->dc_ctl & DC_TXCTL_SETUP) {
			sc->dc_cdata.dc_tx_cnt--;
			if (cur_tx->dc_ctl & DC_TXCTL_SETUP) {
				/*
				 * Yes, the PNIC is so brain damaged
				 * that it will sometimes generate a TX
				 * underrun error while DMAing the RX
				 * filter setup frame. If we detect this,
				 * we have to send the setup frame again,
				 * or else the filter won't be programmed
				 * correctly.
				 */
				if (DC_IS_PNIC(sc)) {
					if (txstat & DC_TXSTAT_ERRSUM)
						dc_setfilt(sc);
				}
				sc->dc_cdata.dc_tx_chain[idx] = NULL;
			}
			DC_INC(idx, DC_TX_LIST_CNT);
			continue;
		}

		if (/*sc->dc_type == DC_TYPE_21143 &&*/
		    sc->dc_pmode == DC_PMODE_MII &&
		    ((txstat & 0xFFFF) & ~(DC_TXSTAT_ERRSUM|
		    DC_TXSTAT_NOCARRIER|DC_TXSTAT_CARRLOST)))
			txstat &= ~DC_TXSTAT_ERRSUM;

		if (txstat & DC_TXSTAT_ERRSUM) {
			ifp->if_oerrors++;
			if (txstat & DC_TXSTAT_EXCESSCOLL)
				ifp->if_collisions++;
			if (txstat & DC_TXSTAT_LATECOLL)
				ifp->if_collisions++;
			if (!(txstat & DC_TXSTAT_UNDERRUN)) {
				dc_init(sc);
				return;
			}
		}

		ifp->if_collisions += (txstat & DC_TXSTAT_COLLCNT) >> 3;

		ifp->if_opackets++;
		if (sc->dc_cdata.dc_tx_chain[idx] != NULL) {
			m_freem(sc->dc_cdata.dc_tx_chain[idx]);
			sc->dc_cdata.dc_tx_chain[idx] = NULL;
		}

		sc->dc_cdata.dc_tx_cnt--;
		DC_INC(idx, DC_TX_LIST_CNT);
	}

	sc->dc_cdata.dc_tx_cons = idx;
	if (cur_tx != NULL)
		ifp->if_flags &= ~IFF_OACTIVE;

	return;
}

static void dc_tick(xsc)
	void			*xsc;
{
	struct dc_softc		*sc;
	struct mii_data		*mii;
	struct ifnet		*ifp;
	int			s;
	u_int32_t		r;

	s = splimp();

	sc = xsc;
	ifp = &sc->arpcom.ac_if;
	mii = device_get_softc(sc->dc_miibus);

	if (sc->dc_flags & DC_REDUCED_MII_POLL) {
		r = CSR_READ_4(sc, DC_ISR);
		if (DC_IS_INTEL(sc)) {
			if (r & DC_ISR_LINKFAIL)
				sc->dc_link = 0;
			if (sc->dc_link == 0)
				mii_tick(mii);
		} else {
			if ((r & DC_ISR_RX_STATE) == DC_RXSTATE_WAIT &&
			    sc->dc_cdata.dc_tx_prod == 0)
				mii_tick(mii);
		}
	} else
		mii_tick(mii);

	/*
	 * When the init routine completes, we expect to be able to send
	 * packets right away, and in fact the network code will send a
	 * gratuitous ARP the moment the init routine marks the interface
	 * as running. However, even though the MAC may have been initialized,
	 * there may be a delay of a few seconds before the PHY completes
	 * autonegotiation and the link is brought up. Any transmissions
	 * made during that delay will be lost. Dealing with this is tricky:
	 * we can't just pause in the init routine while waiting for the
	 * PHY to come ready since that would bring the whole system to
	 * a screeching halt for several seconds.
	 *
	 * What we do here is prevent the TX start routine from sending
	 * any packets until a link has been established. After the
	 * interface has been initialized, the tick routine will poll
	 * the state of the PHY until the IFM_ACTIVE flag is set. Until
	 * that time, packets will stay in the send queue, and once the
	 * link comes up, they will be flushed out to the wire.
	 */
	if (!sc->dc_link) {
		mii_pollstat(mii);
		if (mii->mii_media_status & IFM_ACTIVE &&
		    IFM_SUBTYPE(mii->mii_media_active) != IFM_NONE) {
			sc->dc_link++;
			if (ifp->if_snd.ifq_head != NULL)
				dc_start(ifp);
		}
	}

	sc->dc_stat_ch = timeout(dc_tick, sc, hz);

	splx(s);

	return;
}

static void dc_intr(arg)
	void			*arg;
{
	struct dc_softc		*sc;
	struct ifnet		*ifp;
	u_int32_t		status;

	sc = arg;
	ifp = &sc->arpcom.ac_if;

	/* Supress unwanted interrupts */
	if (!(ifp->if_flags & IFF_UP)) {
		if (CSR_READ_4(sc, DC_ISR) & DC_INTRS)
			dc_stop(sc);
		return;
	}

	/* Disable interrupts. */
	CSR_WRITE_4(sc, DC_IMR, 0x00000000);

	while((status = CSR_READ_4(sc, DC_ISR)) & DC_INTRS) {

		CSR_WRITE_4(sc, DC_ISR, status);

		if (status & DC_ISR_RX_OK) {
			int		curpkts;
			curpkts = ifp->if_ipackets;
			dc_rxeof(sc);
			if (curpkts == ifp->if_ipackets) {
				while(dc_rx_resync(sc))
					dc_rxeof(sc);
			}
		}

		if (status & (DC_ISR_TX_OK|DC_ISR_TX_NOBUF))
			dc_txeof(sc);

		if (status & DC_ISR_TX_IDLE) {
			dc_txeof(sc);
			if (sc->dc_cdata.dc_tx_cnt) {
				DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_TX_ON);
				CSR_WRITE_4(sc, DC_TXSTART, 0xFFFFFFFF);
			}
		}

		if (status & DC_ISR_TX_UNDERRUN) {
			u_int32_t		cfg;

			printf("dc%d: TX underrun -- ", sc->dc_unit);
			if (DC_IS_DAVICOM(sc) || DC_IS_INTEL(sc))
				dc_init(sc);
			cfg = CSR_READ_4(sc, DC_NETCFG);
			cfg &= ~DC_NETCFG_TX_THRESH;
			if (sc->dc_txthresh == DC_TXTHRESH_160BYTES) {
				printf("using store and forward mode\n");
				DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_STORENFWD);
			} else if (sc->dc_flags & DC_TX_STORENFWD) {
				printf("resetting\n");
			} else {
				sc->dc_txthresh += 0x4000;
				printf("increasing TX threshold\n");
				CSR_WRITE_4(sc, DC_NETCFG, cfg);
				DC_SETBIT(sc, DC_NETCFG, sc->dc_txthresh);
				DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_STORENFWD);
			}
		}

		if ((status & DC_ISR_RX_WATDOGTIMEO)
		    || (status & DC_ISR_RX_NOBUF)) {
			int		curpkts;
			curpkts = ifp->if_ipackets;
			dc_rxeof(sc);
			if (curpkts == ifp->if_ipackets) {
				while(dc_rx_resync(sc))
					dc_rxeof(sc);
			}
		}

		if (status & DC_ISR_BUS_ERR) {
			dc_reset(sc);
			dc_init(sc);
		}
	}

	/* Re-enable interrupts. */
	CSR_WRITE_4(sc, DC_IMR, DC_INTRS);

	if (ifp->if_snd.ifq_head != NULL)
		dc_start(ifp);

	return;
}

/*
 * Encapsulate an mbuf chain in a descriptor by coupling the mbuf data
 * pointers to the fragment pointers.
 */
static int dc_encap(sc, m_head, txidx)
	struct dc_softc		*sc;
	struct mbuf		*m_head;
	u_int32_t		*txidx;
{
	struct dc_desc		*f = NULL;
	struct mbuf		*m;
	int			frag, cur, cnt = 0;

	/*
 	 * Start packing the mbufs in this chain into
	 * the fragment pointers. Stop when we run out
 	 * of fragments or hit the end of the mbuf chain.
	 */
	m = m_head;
	cur = frag = *txidx;

	for (m = m_head; m != NULL; m = m->m_next) {
		if (m->m_len != 0) {
			if (sc->dc_flags & DC_TX_ADMTEK_WAR) {
				if (*txidx != sc->dc_cdata.dc_tx_prod &&
				    frag == (DC_TX_LIST_CNT - 1))
					return(ENOBUFS);
			}
			if ((DC_TX_LIST_CNT -
			    (sc->dc_cdata.dc_tx_cnt + cnt)) < 5)
				return(ENOBUFS);

			f = &sc->dc_ldata->dc_tx_list[frag];
			f->dc_ctl = DC_TXCTL_TLINK | m->m_len;
			if (cnt == 0) {
				f->dc_status = 0;
				f->dc_ctl |= DC_TXCTL_FIRSTFRAG;
			} else
				f->dc_status = DC_TXSTAT_OWN;
			f->dc_data = vtophys(mtod(m, vm_offset_t));
			cur = frag;
			DC_INC(frag, DC_TX_LIST_CNT);
			cnt++;
		}
	}

	if (m != NULL)
		return(ENOBUFS);

	sc->dc_cdata.dc_tx_cnt += cnt;
	sc->dc_cdata.dc_tx_chain[cur] = m_head;
	sc->dc_ldata->dc_tx_list[cur].dc_ctl |= DC_TXCTL_LASTFRAG;
	if (sc->dc_flags & DC_TX_INTR_FIRSTFRAG)
		sc->dc_ldata->dc_tx_list[*txidx].dc_ctl |= DC_TXCTL_FINT;
	if (sc->dc_flags & DC_TX_INTR_ALWAYS)
		sc->dc_ldata->dc_tx_list[cur].dc_ctl |= DC_TXCTL_FINT;
	if (sc->dc_flags & DC_TX_USE_TX_INTR && sc->dc_cdata.dc_tx_cnt > 64)
		sc->dc_ldata->dc_tx_list[cur].dc_ctl |= DC_TXCTL_FINT;
	sc->dc_ldata->dc_tx_list[*txidx].dc_status = DC_TXSTAT_OWN;
	*txidx = frag;

	return(0);
}

/*
 * Coalesce an mbuf chain into a single mbuf cluster buffer.
 * Needed for some really badly behaved chips that just can't
 * do scatter/gather correctly.
 */
static int dc_coal(sc, m_head)
	struct dc_softc		*sc;
	struct mbuf		**m_head;
{
        struct mbuf		*m_new, *m;

	m = *m_head;
	MGETHDR(m_new, M_DONTWAIT, MT_DATA);
	if (m_new == NULL) {
		printf("dc%d: no memory for tx list", sc->dc_unit);
		return(ENOBUFS);
	}
	if (m->m_pkthdr.len > MHLEN) {
		MCLGET(m_new, M_DONTWAIT);
		if (!(m_new->m_flags & M_EXT)) {
			m_freem(m_new);
			printf("dc%d: no memory for tx list", sc->dc_unit);
			return(ENOBUFS);
		}
	}
	m_copydata(m, 0, m->m_pkthdr.len, mtod(m_new, caddr_t));
	m_new->m_pkthdr.len = m_new->m_len = m->m_pkthdr.len;
	m_freem(m);
	*m_head = m_new;

	return(0);
}

/*
 * Main transmit routine. To avoid having to do mbuf copies, we put pointers
 * to the mbuf data regions directly in the transmit lists. We also save a
 * copy of the pointers since the transmit list fragment pointers are
 * physical addresses.
 */

static void dc_start(ifp)
	struct ifnet		*ifp;
{
	struct dc_softc		*sc;
	struct mbuf		*m_head = NULL;
	int			idx;

	sc = ifp->if_softc;

	if (!sc->dc_link)
		return;

	if (ifp->if_flags & IFF_OACTIVE)
		return;

	idx = sc->dc_cdata.dc_tx_prod;

	while(sc->dc_cdata.dc_tx_chain[idx] == NULL) {
		IF_DEQUEUE(&ifp->if_snd, m_head);
		if (m_head == NULL)
			break;

		if (sc->dc_flags & DC_TX_COALESCE) {
			if (dc_coal(sc, &m_head)) {
				IF_PREPEND(&ifp->if_snd, m_head);
				ifp->if_flags |= IFF_OACTIVE;
				break;
			}
		}

		if (dc_encap(sc, m_head, &idx)) {
			IF_PREPEND(&ifp->if_snd, m_head);
			ifp->if_flags |= IFF_OACTIVE;
			break;
		}

		/*
		 * If there's a BPF listener, bounce a copy of this frame
		 * to him.
		 */
		if (ifp->if_bpf)
			bpf_mtap(ifp, m_head);
	}

	/* Transmit */
	sc->dc_cdata.dc_tx_prod = idx;
	if (!(sc->dc_flags & DC_TX_POLL))
		CSR_WRITE_4(sc, DC_TXSTART, 0xFFFFFFFF);

	/*
	 * Set a timeout in case the chip goes out to lunch.
	 */
	ifp->if_timer = 5;

	return;
}

static void dc_init(xsc)
	void			*xsc;
{
	struct dc_softc		*sc = xsc;
	struct ifnet		*ifp = &sc->arpcom.ac_if;
	struct mii_data		*mii;
	int			s;

	s = splimp();

	mii = device_get_softc(sc->dc_miibus);

	/*
	 * Cancel pending I/O and free all RX/TX buffers.
	 */
	dc_stop(sc);
	dc_reset(sc);

	/*
	 * Set cache alignment and burst length.
	 */
	if (DC_IS_ASIX(sc) || DC_IS_DAVICOM(sc))
		CSR_WRITE_4(sc, DC_BUSCTL, 0);
	else
		CSR_WRITE_4(sc, DC_BUSCTL, DC_BUSCTL_MRME|DC_BUSCTL_MRLE);
	if (DC_IS_DAVICOM(sc) || DC_IS_INTEL(sc)) {
		DC_SETBIT(sc, DC_BUSCTL, DC_BURSTLEN_USECA);
	} else {
		DC_SETBIT(sc, DC_BUSCTL, DC_BURSTLEN_16LONG);
	}
	if (sc->dc_flags & DC_TX_POLL)
		DC_SETBIT(sc, DC_BUSCTL, DC_TXPOLL_1);
	switch(sc->dc_cachesize) {
	case 32:
		DC_SETBIT(sc, DC_BUSCTL, DC_CACHEALIGN_32LONG);
		break;
	case 16:
		DC_SETBIT(sc, DC_BUSCTL, DC_CACHEALIGN_16LONG);
		break;
	case 8:
		DC_SETBIT(sc, DC_BUSCTL, DC_CACHEALIGN_8LONG);
		break;
	case 0:
	default:
		DC_SETBIT(sc, DC_BUSCTL, DC_CACHEALIGN_NONE);
		break;
	}

	if (sc->dc_flags & DC_TX_STORENFWD)
		DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_STORENFWD);
	else {
		if (sc->dc_txthresh == DC_TXTHRESH_160BYTES) {
			DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_STORENFWD);
		} else {
			DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_STORENFWD);
			DC_SETBIT(sc, DC_NETCFG, sc->dc_txthresh);
		}
	}

	DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_NO_RXCRC);
	DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_TX_BACKOFF);

	if (DC_IS_MACRONIX(sc) || DC_IS_PNICII(sc)) {
		/*
		 * The app notes for the 98713 and 98715A say that
		 * in order to have the chips operate properly, a magic
		 * number must be written to CSR16. Macronix does not
		 * document the meaning of these bits so there's no way
		 * to know exactly what they do. The 98713 has a magic
		 * number all its own; the rest all use a different one.
		 */
		DC_CLRBIT(sc, DC_MX_MAGICPACKET, 0xFFFF0000);
		if (sc->dc_type == DC_TYPE_98713)
			DC_SETBIT(sc, DC_MX_MAGICPACKET, DC_MX_MAGIC_98713);
		else
			DC_SETBIT(sc, DC_MX_MAGICPACKET, DC_MX_MAGIC_98715);
	}

	DC_CLRBIT(sc, DC_NETCFG, DC_NETCFG_TX_THRESH);
	DC_SETBIT(sc, DC_NETCFG, DC_TXTHRESH_72BYTES);

	/* Init circular RX list. */
	if (dc_list_rx_init(sc) == ENOBUFS) {
		printf("dc%d: initialization failed: no "
		    "memory for rx buffers\n", sc->dc_unit);
		dc_stop(sc);
		(void)splx(s);
		return;
	}

	/*
	 * Init tx descriptors.
	 */
	dc_list_tx_init(sc);

	/*
	 * Load the address of the RX list.
	 */
	CSR_WRITE_4(sc, DC_RXADDR, vtophys(&sc->dc_ldata->dc_rx_list[0]));
	CSR_WRITE_4(sc, DC_TXADDR, vtophys(&sc->dc_ldata->dc_tx_list[0]));

	/*
	 * Enable interrupts.
	 */
	CSR_WRITE_4(sc, DC_IMR, DC_INTRS);
	CSR_WRITE_4(sc, DC_ISR, 0xFFFFFFFF);

	/* Enable transmitter. */
	DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_TX_ON);

	/*
	 * Load the RX/multicast filter. We do this sort of late
	 * because the filter programming scheme on the 21143 and
	 * some clones requires DMAing a setup frame via the TX
	 * engine, and we need the transmitter enabled for that.
	 */
	dc_setfilt(sc);

	/* Enable receiver. */
	DC_SETBIT(sc, DC_NETCFG, DC_NETCFG_RX_ON);
	CSR_WRITE_4(sc, DC_RXSTART, 0xFFFFFFFF);

	mii_mediachg(mii);
	dc_setcfg(sc, sc->dc_if_media);

	ifp->if_flags |= IFF_RUNNING;
	ifp->if_flags &= ~IFF_OACTIVE;

	(void)splx(s);

	sc->dc_stat_ch = timeout(dc_tick, sc, hz);

#ifdef __alpha__
        if(sc->dc_srm_media) {
		struct ifreq ifr;

		ifr.ifr_media = sc->dc_srm_media;
		ifmedia_ioctl(ifp, &ifr, &mii->mii_media, SIOCSIFMEDIA);
		sc->dc_srm_media = 0;
	}
#endif
	return;
}

/*
 * Set media options.
 */
static int dc_ifmedia_upd(ifp)
	struct ifnet		*ifp;
{
	struct dc_softc		*sc;
	struct mii_data		*mii;
	struct ifmedia		*ifm;

	sc = ifp->if_softc;
	mii = device_get_softc(sc->dc_miibus);
	mii_mediachg(mii);
	ifm = &mii->mii_media;

	if (DC_IS_DAVICOM(sc) &&
	    IFM_SUBTYPE(ifm->ifm_media) == IFM_homePNA)
		dc_setcfg(sc, ifm->ifm_media);
	else
		sc->dc_link = 0;

	return(0);
}

/*
 * Report current media status.
 */
static void dc_ifmedia_sts(ifp, ifmr)
	struct ifnet		*ifp;
	struct ifmediareq	*ifmr;
{
	struct dc_softc		*sc;
	struct mii_data		*mii;
	struct ifmedia		*ifm;

	sc = ifp->if_softc;
	mii = device_get_softc(sc->dc_miibus);
	mii_pollstat(mii);
	ifm = &mii->mii_media;
	if (DC_IS_DAVICOM(sc)) {
		if (IFM_SUBTYPE(ifm->ifm_media) == IFM_homePNA) {
			ifmr->ifm_active = ifm->ifm_media;
			ifmr->ifm_status = 0;
			return;
		}
	}
	ifmr->ifm_active = mii->mii_media_active;
	ifmr->ifm_status = mii->mii_media_status;

	return;
}

static int dc_ioctl(ifp, command, data)
	struct ifnet		*ifp;
	u_long			command;
	caddr_t			data;
{
	struct dc_softc		*sc = ifp->if_softc;
	struct ifreq		*ifr = (struct ifreq *) data;
	struct mii_data		*mii;
	int			s, error = 0;

	s = splimp();

	switch(command) {
	case SIOCSIFADDR:
	case SIOCGIFADDR:
	case SIOCSIFMTU:
		error = ether_ioctl(ifp, command, data);
		break;
	case SIOCSIFFLAGS:
		if (ifp->if_flags & IFF_UP) {
			if (ifp->if_flags & IFF_RUNNING &&
			    ifp->if_flags & IFF_PROMISC &&
			    !(sc->dc_if_flags & IFF_PROMISC)) {
				dc_setfilt(sc);
			} else if (ifp->if_flags & IFF_RUNNING &&
			    !(ifp->if_flags & IFF_PROMISC) &&
			    sc->dc_if_flags & IFF_PROMISC) {
				dc_setfilt(sc);
			} else if (!(ifp->if_flags & IFF_RUNNING)) {
				sc->dc_txthresh = 0;
				dc_init(sc);
			}
		} else {
			if (ifp->if_flags & IFF_RUNNING)
				dc_stop(sc);
		}
		sc->dc_if_flags = ifp->if_flags;
		error = 0;
		break;
	case SIOCADDMULTI:
	case SIOCDELMULTI:
		dc_setfilt(sc);
		error = 0;
		break;
	case SIOCGIFMEDIA:
	case SIOCSIFMEDIA:
		mii = device_get_softc(sc->dc_miibus);
		error = ifmedia_ioctl(ifp, ifr, &mii->mii_media, command);
#ifdef __alpha__
		if (sc->dc_srm_media)
			sc->dc_srm_media = 0;
#endif
		break;
	default:
		error = EINVAL;
		break;
	}

	(void)splx(s);

	return(error);
}

static void dc_watchdog(ifp)
	struct ifnet		*ifp;
{
	struct dc_softc		*sc;

	sc = ifp->if_softc;

	ifp->if_oerrors++;
	printf("dc%d: watchdog timeout\n", sc->dc_unit);

	dc_stop(sc);
	dc_reset(sc);
	dc_init(sc);

	if (ifp->if_snd.ifq_head != NULL)
		dc_start(ifp);

	return;
}

/*
 * Stop the adapter and free any mbufs allocated to the
 * RX and TX lists.
 */
static void dc_stop(sc)
	struct dc_softc		*sc;
{
	register int		i;
	struct ifnet		*ifp;

	ifp = &sc->arpcom.ac_if;
	ifp->if_timer = 0;

	untimeout(dc_tick, sc, sc->dc_stat_ch);

	DC_CLRBIT(sc, DC_NETCFG, (DC_NETCFG_RX_ON|DC_NETCFG_TX_ON));
	CSR_WRITE_4(sc, DC_IMR, 0x00000000);
	CSR_WRITE_4(sc, DC_TXADDR, 0x00000000);
	CSR_WRITE_4(sc, DC_RXADDR, 0x00000000);
	sc->dc_link = 0;

	/*
	 * Free data in the RX lists.
	 */
	for (i = 0; i < DC_RX_LIST_CNT; i++) {
		if (sc->dc_cdata.dc_rx_chain[i] != NULL) {
			m_freem(sc->dc_cdata.dc_rx_chain[i]);
			sc->dc_cdata.dc_rx_chain[i] = NULL;
		}
	}
	bzero((char *)&sc->dc_ldata->dc_rx_list,
		sizeof(sc->dc_ldata->dc_rx_list));

	/*
	 * Free the TX list buffers.
	 */
	for (i = 0; i < DC_TX_LIST_CNT; i++) {
		if (sc->dc_cdata.dc_tx_chain[i] != NULL) {
			if (sc->dc_ldata->dc_tx_list[i].dc_ctl &
			    DC_TXCTL_SETUP) {
				sc->dc_cdata.dc_tx_chain[i] = NULL;
				continue;
			}
			m_freem(sc->dc_cdata.dc_tx_chain[i]);
			sc->dc_cdata.dc_tx_chain[i] = NULL;
		}
	}

	bzero((char *)&sc->dc_ldata->dc_tx_list,
		sizeof(sc->dc_ldata->dc_tx_list));

	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);

	return;
}

/*
 * Stop all chip I/O so that the kernel's probe routines don't
 * get confused by errant DMAs when rebooting.
 */
static void dc_shutdown(dev)
	device_t		dev;
{
	struct dc_softc		*sc;

	sc = device_get_softc(dev);

	dc_stop(sc);

	return;
}