NetBSD/sys/dev/ic/smc83c170.c

/*	$NetBSD: smc83c170.c,v 1.7 1998/08/08 23:51:40 mycroft Exp $	*/

/*-
 * Copyright (c) 1998 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center.
 *
 * 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 the NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 THE FOUNDATION OR CONTRIBUTORS
 * 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.
 */

/*
 * Device driver for the Standard Microsystems Corp. 83C170
 * Ethernet PCI Integrated Controller (EPIC/100).
 */

#include "opt_inet.h"
#include "opt_ns.h"
#include "bpfilter.h"

#include <sys/param.h>
#include <sys/systm.h> 
#include <sys/mbuf.h>   
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/device.h>
 
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_media.h>
#include <net/if_ether.h>

#if NBPFILTER > 0 
#include <net/bpf.h>
#endif 

#ifdef INET
#include <netinet/in.h> 
#include <netinet/if_inarp.h>
#endif

#ifdef NS
#include <netns/ns.h>
#include <netns/ns_if.h>
#endif

#include <machine/bus.h>
#include <machine/intr.h>

#include <dev/ic/smc83c170reg.h>
#include <dev/ic/smc83c170var.h>

void	epic_start __P((struct ifnet *));
void	epic_watchdog __P((struct ifnet *));
int	epic_ioctl __P((struct ifnet *, u_long, caddr_t));

void	epic_shutdown __P((void *));

void	epic_reset __P((struct epic_softc *));
void	epic_init __P((struct epic_softc *));
void	epic_stop __P((struct epic_softc *));
int	epic_add_rxbuf __P((struct epic_softc *, int));
void	epic_read_eeprom __P((struct epic_softc *, int, int, u_int16_t *));
void	epic_set_mchash __P((struct epic_softc *));
void	epic_fixup_clock_source __P((struct epic_softc *));

/*
 * Fudge the incoming packets by this much, to ensure the data after
 * the Ethernet header is aligned.
 */
#define	RX_ALIGNMENT_FUDGE	2

/* XXX Should be somewhere else. */
#define	ETHER_MIN_LEN		60

#define	INTMASK	(INTSTAT_FATAL_INT | INTSTAT_TXU | \
	    INTSTAT_TXC | INTSTAT_RQE | INTSTAT_RCC)

/*
 * Attach an EPIC interface to the system.
 */
void
epic_attach(sc)
	struct epic_softc *sc;
{
	bus_space_tag_t st = sc->sc_st;
	bus_space_handle_t sh = sc->sc_sh;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
	int i, rseg, error, attach_stage;
	bus_dma_segment_t seg;
	u_int8_t enaddr[ETHER_ADDR_LEN], devname[12 + 1];
	u_int16_t myea[ETHER_ADDR_LEN / 2], mydevname[6];

	attach_stage = 0;

	/*
	 * Allocate the control data structures, and create and load the
	 * DMA map for it.
	 */
	if ((error = bus_dmamem_alloc(sc->sc_dmat,
	    sizeof(struct epic_control_data), NBPG, 0, &seg, 1, &rseg,
	    BUS_DMA_NOWAIT)) != 0) {
		printf("%s: unable to allocate control data, error = %d\n",
		    sc->sc_dev.dv_xname, error);
		goto fail;
	}

	attach_stage = 1;

	if ((error = bus_dmamem_map(sc->sc_dmat, &seg, rseg,
	    sizeof(struct epic_control_data), (caddr_t *)&sc->sc_control_data,
	    BUS_DMA_NOWAIT|BUS_DMA_COHERENT)) != 0) {
		printf("%s: unable to map control data, error = %d\n",
		    sc->sc_dev.dv_xname, error);
		goto fail;
	}

	attach_stage = 2;

	if ((error = bus_dmamap_create(sc->sc_dmat,
	    sizeof(struct epic_control_data), 1,
	    sizeof(struct epic_control_data), 0, BUS_DMA_NOWAIT,
	    &sc->sc_cddmamap)) != 0) {
		printf("%s: unable to create control data DMA map, "
		    "error = %d\n", sc->sc_dev.dv_xname, error);
		goto fail;
	}

	attach_stage = 3;

	if ((error = bus_dmamap_load(sc->sc_dmat, sc->sc_cddmamap,
	    sc->sc_control_data, sizeof(struct epic_control_data), NULL,
	    BUS_DMA_NOWAIT)) != 0) {
		printf("%s: unable to load control data DMA map, error = %d\n",
		    sc->sc_dev.dv_xname, error);
		goto fail;
	}

	attach_stage = 4;

	/*
	 * Create the transmit buffer DMA maps.
	 */
	for (i = 0; i < EPIC_NTXDESC; i++) {
		if ((error = bus_dmamap_create(sc->sc_dmat, MCLBYTES,
		    EPIC_NFRAGS, MCLBYTES, 0, BUS_DMA_NOWAIT,
		    &sc->sc_txsoft[i].ds_dmamap)) != 0) {
			printf("%s: unable to create tx DMA map %d, "
			    "error = %d\n", sc->sc_dev.dv_xname, i, error);
			goto fail;
		}
	}

	attach_stage = 5;

	/*
	 * Create the recieve buffer DMA maps.
	 */
	for (i = 0; i < EPIC_NRXDESC; i++) {
		if ((error = bus_dmamap_create(sc->sc_dmat, MCLBYTES, 1,
		    MCLBYTES, 0, BUS_DMA_NOWAIT,
		    &sc->sc_rxsoft[i].ds_dmamap)) != 0) {
			printf("%s: unable to create rx DMA map %d, "
			    "error = %d\n", sc->sc_dev.dv_xname, i, error);
			goto fail;
		}
	}

	attach_stage = 6;

	/*
	 * Pre-allocate the receive buffers.
	 */
	for (i = 0; i < EPIC_NRXDESC; i++) {
		if ((error = epic_add_rxbuf(sc, i)) != 0) {
			printf("%s: unable to allocate or map rx buffer %d\n,"
			    " error = %d\n", sc->sc_dev.dv_xname, i, error);
			goto fail;
		}
	}

	attach_stage = 7;

	/*
	 * Bring the chip out of low-power mode and reset it to a known state.
	 */
	bus_space_write_4(st, sh, EPIC_GENCTL, 0);
	epic_reset(sc);

	/*
	 * Read the Ethernet address from the EEPROM.
	 */
	epic_read_eeprom(sc, 0, (sizeof(myea) / sizeof(myea[0])), myea);
	bcopy(myea, enaddr, sizeof(myea));

	/*
	 * ...and the device name.
	 */
	epic_read_eeprom(sc, 0x2c, (sizeof(mydevname) / sizeof(mydevname[0])),
	    mydevname);
	bcopy(mydevname, devname, sizeof(mydevname));
	devname[sizeof(mydevname)] = '\0';
	for (i = sizeof(mydevname) - 1; i >= 0; i--) {
		if (devname[i] == ' ')
			devname[i] = '\0';
		else
			break;
	}

	printf("%s: %s, Ethernet address %s\n", sc->sc_dev.dv_xname,
	    devname, ether_sprintf(enaddr));

	ifp = &sc->sc_ethercom.ec_if;
	strcpy(ifp->if_xname, sc->sc_dev.dv_xname);
	ifp->if_softc = sc;
	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
	ifp->if_ioctl = epic_ioctl;
	ifp->if_start = epic_start;
	ifp->if_watchdog = epic_watchdog;

	/*
	 * Attach the interface.
	 */
	if_attach(ifp);
	ether_ifattach(ifp, enaddr);
#if NBPFILTER > 0
	bpfattach(&sc->sc_ethercom.ec_if.if_bpf, ifp, DLT_EN10MB,
	    sizeof(struct ether_header));
#endif

	/*
	 * Make sure the interface is shutdown during reboot.
	 */
	sc->sc_sdhook = shutdownhook_establish(epic_shutdown, sc);
	if (sc->sc_sdhook == NULL)
		printf("%s: WARNING: unable to establish shutdown hook\n",
		    sc->sc_dev.dv_xname);
	return;

 fail:
	/*
	 * Free any resources we've allocated during the failed attach
	 * attempt.  Do this in reverse order and fall through.
	 */
	switch (attach_stage) {
	case 7:
		for (i = 0; i < EPIC_NRXDESC; i++) {
			if (sc->sc_rxsoft[i].ds_mbuf != NULL) {
				bus_dmamap_unload(sc->sc_dmat,
				    sc->sc_rxsoft[i].ds_dmamap);
				m_freem(sc->sc_rxsoft[i].ds_mbuf);
			}
		}
		/* FALLTHROUGH */

	case 6:
		for (i = 0; i < EPIC_NRXDESC; i++)
			bus_dmamap_destroy(sc->sc_dmat,
			    sc->sc_rxsoft[i].ds_dmamap);
		/* FALLTHROUGH */

	case 5:
		for (i = 0; i < EPIC_NTXDESC; i++)
			bus_dmamap_destroy(sc->sc_dmat,
			    sc->sc_txsoft[i].ds_dmamap);
		/* FALLTHROUGH */

	case 4:
		bus_dmamap_unload(sc->sc_dmat, sc->sc_cddmamap);
		/* FALLTHROUGH */

	case 3:
		bus_dmamap_destroy(sc->sc_dmat, sc->sc_cddmamap);
		/* FALLTHROUGH */

	case 2:
		bus_dmamem_unmap(sc->sc_dmat, (caddr_t)sc->sc_control_data,
		    sizeof(struct epic_control_data));
		/* FALLTHROUGH */

	case 1:
		bus_dmamem_free(sc->sc_dmat, &seg, rseg);
		break;
	}
}

/*
 * Shutdown hook.  Make sure the interface is stopped at reboot.
 */
void
epic_shutdown(arg)
	void *arg;
{
	struct epic_softc *sc = arg;

	epic_stop(sc);
}

/*
 * Start packet transmission on the interface.
 * [ifnet interface function]
 */
void
epic_start(ifp)
	struct ifnet *ifp;
{
	struct epic_softc *sc = ifp->if_softc;
	struct epic_txdesc *txd;
	struct epic_descsoft *ds;
	struct epic_fraglist *fr;
	bus_dmamap_t dmamap;
	struct mbuf *m0;
	int nexttx, seg, error, txqueued;

	txqueued = 0;

	/*
	 * Loop through the send queue, setting up transmit descriptors
	 * until we drain the queue, or use up all available transmit
	 * descriptors.
	 */
	while (ifp->if_snd.ifq_head != NULL &&
	    sc->sc_txpending < EPIC_NTXDESC) {
		/*
		 * Grab a packet off the queue.
		 */
		IF_DEQUEUE(&ifp->if_snd, m0);

		/*
		 * Get the last and next available transmit descriptor.
		 */
		nexttx = EPIC_NEXTTX(sc->sc_txlast);
		txd = &sc->sc_control_data->ecd_txdescs[nexttx];
		fr = &sc->sc_control_data->ecd_txfrags[nexttx];
		ds = &sc->sc_txsoft[nexttx];
		dmamap = ds->ds_dmamap;

 loadmap:
		/*
		 * Load the DMA map with the packet.
		 */
		error = bus_dmamap_load_mbuf(sc->sc_dmat, dmamap, m0,
		    BUS_DMA_NOWAIT);
		switch (error) {
		case 0:
			/* Success. */
			break;

		case EFBIG:
		    {
			struct mbuf *mn;

			/*
			 * We ran out of segments.  We have to recopy this
			 * mbuf chain first.  Bail out if we can't get the
			 * new buffers.
			 */
			printf("%s: too many segments, ", sc->sc_dev.dv_xname);

			MGETHDR(mn, M_DONTWAIT, MT_DATA);
			if (mn == NULL) {
				m_freem(m0);
				printf("aborting\n");
				goto out;
			}
			if (m0->m_pkthdr.len > MHLEN) {
				MCLGET(mn, M_DONTWAIT);
				if ((mn->m_flags & M_EXT) == 0) {
					m_freem(mn);
					m_freem(m0);
					printf("aborting\n");
					goto out;
				}
			}
			m_copydata(m0, 0, m0->m_pkthdr.len, mtod(mn, caddr_t));
			mn->m_pkthdr.len = mn->m_len = m0->m_pkthdr.len;
			m_freem(m0);
			m0 = mn;
			printf("retrying\n");
			goto loadmap;
		    }
		
		default:
			/*
			 * Some other problem; report it.
			 */
			printf("%s: can't load mbuf chain, error = %d\n",
			    sc->sc_dev.dv_xname, error);
			m_freem(m0);
			goto out;
		}

		/*
		 * Initialize the fraglist.
		 */
		fr->ef_nfrags = dmamap->dm_nsegs;
		for (seg = 0; seg < dmamap->dm_nsegs; seg++) {
			fr->ef_frags[seg].ef_addr =
			    dmamap->dm_segs[seg].ds_addr;
			fr->ef_frags[seg].ef_length =
			    dmamap->dm_segs[seg].ds_len;
		}

		bus_dmamap_sync(sc->sc_dmat, dmamap, 0, dmamap->dm_mapsize,
		    BUS_DMASYNC_PREWRITE);

		/*
		 * Store a pointer to the packet so we can free it later.
		 */
		ds->ds_mbuf = m0;

		/*
		 * Finish setting up the new transmit descriptor: set the
		 * packet length and give it to the EPIC.
		 */
		txd->et_txlength = max(m0->m_pkthdr.len, ETHER_MIN_LEN);
		txd->et_txstatus = ET_TXSTAT_OWNER;

		/*
		 * Committed; advance the lasttx pointer.  If nothing was
		 * previously queued, reset the dirty pointer.
		 */
		sc->sc_txlast = nexttx;
		if (sc->sc_txpending == 0)
			sc->sc_txdirty = nexttx;

		sc->sc_txpending++;

		txqueued = 1;

#if NBPFILTER > 0
		/*
		 * Pass the packet to any BPF listeners.
		 */
		if (ifp->if_bpf)
			bpf_mtap(ifp->if_bpf, m0);
#endif
	}

 out:
	/*
	 * We're finished.  If we added more packets, make sure the
	 * transmit DMA engine is running.
	 */
	if (txqueued) {
		bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_COMMAND,
		    COMMAND_TXQUEUED);

		/*
		 * Set a 5 second watchdog timer.
		 */
		ifp->if_timer = 5;
	}
}

/*
 * Watchdog timer handler.
 * [ifnet interface function]
 */
void
epic_watchdog(ifp)
	struct ifnet *ifp;
{
	struct epic_softc *sc = ifp->if_softc;

	printf("%s: device timeout\n", sc->sc_dev.dv_xname);
	ifp->if_oerrors++;

	epic_init(sc);
}

/*
 * Handle control requests from the operator.
 * [ifnet interface function]
 */
int
epic_ioctl(ifp, cmd, data)
	struct ifnet *ifp;
	u_long cmd;
	caddr_t data;
{
	struct epic_softc *sc = ifp->if_softc;
	struct ifreq *ifr = (struct ifreq *)data;
	struct ifaddr *ifa = (struct ifaddr *)data;
	int s, error = 0;

	s = splnet();

	switch (cmd) {
	case SIOCSIFADDR:
		ifp->if_flags |= IFF_UP;

		switch (ifa->ifa_addr->sa_family) {
#ifdef INET
		case AF_INET:
			epic_init(sc);
			arp_ifinit(ifp, ifa);
			break;
#endif /* INET */
#ifdef NS
		case AF_NS:
		    {
			struct ns_addr *ina = &IA_SNS(ifa)->sns_addr;

			if (ns_nullhost(*ina))
				ina->x_host = *(union ns_host *)
				    LLADDR(ifp->if_sadl);
			else
				bcopy(ina->x_host.c_host, LLADDR(ifp->if_sadl),
				    ifp->if_addrlen);
			/* Set new address. */
			epic_init(sc);
			break;
		    }
#endif /* NS */
		default:
			epic_init(sc);
			break;
		}
		break;

	case SIOCSIFMTU:
		if (ifr->ifr_mtu > ETHERMTU)
			error = EINVAL;
		else
			ifp->if_mtu = ifr->ifr_mtu;
		break;

	case SIOCSIFFLAGS:
		if ((ifp->if_flags & IFF_UP) == 0 &&
		    (ifp->if_flags & IFF_RUNNING) != 0) {
			/*
			 * If interface is marked down and it is running, then
			 * stop it.
			 */
			epic_stop(sc);
			ifp->if_flags &= ~IFF_RUNNING;
		} else if ((ifp->if_flags & IFF_UP) != 0 &&
			   (ifp->if_flags & IFF_RUNNING) == 0) {
			/*
			 * If interfase it marked up and it is stopped, then
			 * start it.
			 */
			epic_init(sc);
		} else {
			/*
			 * Reset the interface to pick up changes in any other
			 * flags that affect the hardware state.
			 */
			epic_init(sc);
		}
		break;

	case SIOCADDMULTI:
	case SIOCDELMULTI:
		error = (cmd == SIOCADDMULTI) ?
		    ether_addmulti(ifr, &sc->sc_ethercom) :
		    ether_delmulti(ifr, &sc->sc_ethercom);

		if (error == ENETRESET) {
			/*
			 * Multicast list has changed; set the hardware filter
			 * accordingly.
			 */
			epic_init(sc);
			error = 0;
		}
		break;

	default:
		error = EINVAL;
		break;
	}

	splx(s);
	return (error);
}

/*
 * Interrupt handler.
 */
int
epic_intr(arg)
	void *arg;
{
	struct epic_softc *sc = arg;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
	struct ether_header *eh;
	struct epic_rxdesc *rxd;
	struct epic_txdesc *txd;
	struct epic_descsoft *ds;
	struct mbuf *m;
	u_int32_t intstat;
	int i, len, claimed = 0, error;

 top:
	/*
	 * Get the interrupt status from the EPIC.
	 */
	intstat = bus_space_read_4(sc->sc_st, sc->sc_sh, EPIC_INTSTAT);
	if ((intstat & INTSTAT_INT_ACTV) == 0)
		return (claimed);

	claimed = 1;

	/*
	 * Acknowledge the interrupt.
	 */
	bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_INTSTAT,
	    intstat & INTMASK);

	/*
	 * Check for receive interrupts.
	 */
	if (intstat & (INTSTAT_RCC | INTSTAT_RQE)) {
		for (i = sc->sc_rxptr;; i = EPIC_NEXTRX(i)) {
			rxd = &sc->sc_control_data->ecd_rxdescs[i];
			ds = &sc->sc_rxsoft[i];
			m = ds->ds_mbuf;
			error = 0;

			if (rxd->er_rxstatus & ER_RXSTAT_OWNER) {
				/*
				 * We have processed all of the
				 * receive buffers.
				 */
				break;
			}

			bus_dmamap_sync(sc->sc_dmat, ds->ds_dmamap, 0,
			    ds->ds_dmamap->dm_mapsize, BUS_DMASYNC_POSTREAD);

			/*
			 * Make sure the packet arrived intact.
			 */
			if ((rxd->er_rxstatus & ER_RXSTAT_PKTINTACT) == 0) {
#if 1
				if (rxd->er_rxstatus & ER_RXSTAT_CRCERROR)
					printf("%s: CRC error\n",
					    sc->sc_dev.dv_xname);
				if (rxd->er_rxstatus & ER_RXSTAT_ALIGNERROR)
					printf("%s: alignment error\n",
					    sc->sc_dev.dv_xname);
#endif
				ifp->if_ierrors++;
				error = 1;
			}

			/*
			 * Add a new buffer to the receive chain.  If this
			 * fails, the old buffer is recycled.
			 */
			if (epic_add_rxbuf(sc, i) == 0) {
				/*
				 * We wanted to reset the buffer, but
				 * didn't want to pass it on up.
				 */
				if (error) {
					m_freem(m);
					continue;
				}

				len = rxd->er_buflength;
				if (len < sizeof(struct ether_header)) {
					m_freem(m);
					continue;
				}

				m->m_pkthdr.rcvif = ifp;
				m->m_pkthdr.len = m->m_len = len;
				eh = mtod(m, struct ether_header *);
#if NBPFILTER > 0
				/*
				 * Pass this up to any BPF listeners.
				 */
				if (ifp->if_bpf) {
					bpf_mtap(ifp->if_bpf, m);

					/*
					 * Only pass this up the stack
					 * if it's for us.
					 */
					if ((ifp->if_flags & IFF_PROMISC) &&
					    bcmp(LLADDR(ifp->if_sadl),
						 eh->ether_dhost,
						 ETHER_ADDR_LEN) != 0 &&
					    (rxd->er_rxstatus &
					     (ER_RXSTAT_BCAST|ER_RXSTAT_MCAST))
					     == 0) {
						m_freem(m);
						continue;
					}
				}
#endif /* NPBFILTER > 0 */
				m->m_data += sizeof(struct ether_header);
				m->m_len -= sizeof(struct ether_header);
				m->m_pkthdr.len = m->m_len;
				ether_input(ifp, eh, m);
			}
		}
		
		/*
		 * Update the recieve pointer.
		 */
		sc->sc_rxptr = i;

		/*
		 * Check for receive queue underflow.
		 */
		if (intstat & INTSTAT_RQE) {
			printf("%s: receiver queue empty\n",
			    sc->sc_dev.dv_xname);
			/*
			 * Ring is already built; just restart the
			 * receiver.
			 */
			bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_PRCDAR,
			    sc->sc_cddma + EPIC_CDOFF(ecd_rxdescs[0]));
			bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_COMMAND,
			    COMMAND_RXQUEUED | COMMAND_START_RX);
		}
	}

	/*
	 * Check for transmission complete interrupts.
	 */
	if (intstat & (INTSTAT_TXC | INTSTAT_TXU)) {
		for (i = sc->sc_txdirty;; i = EPIC_NEXTTX(i)) {
			txd = &sc->sc_control_data->ecd_txdescs[i];
			ds = &sc->sc_txsoft[i];

			if (sc->sc_txpending == 0 ||
			    (txd->et_txstatus & ET_TXSTAT_OWNER) != 0)
				break;

			if (ds->ds_mbuf != NULL) {
				bus_dmamap_sync(sc->sc_dmat, ds->ds_dmamap,
				    0, ds->ds_dmamap->dm_mapsize,
				    BUS_DMASYNC_POSTWRITE);
				bus_dmamap_unload(sc->sc_dmat, ds->ds_dmamap);
				m_freem(ds->ds_mbuf);
				ds->ds_mbuf = NULL;
			}
			sc->sc_txpending--;

			/*
			 * Check for errors and collisions.
			 */
			if ((txd->et_txstatus & ET_TXSTAT_PACKETTX) == 0)
				ifp->if_oerrors++;
			ifp->if_collisions +=
			    TXSTAT_COLLISIONS(txd->et_txstatus);
			if (txd->et_txstatus & ET_TXSTAT_CARSENSELOST) {
#if 1
				printf("%s: lost carrier\n",
				    sc->sc_dev.dv_xname);
#endif
				/* XXX clear "active" but in media data */
			}
		}
		
		/*
		 * Update the dirty transmit buffer pointer.
		 */
		sc->sc_txdirty = i;

		/*
		 * Cancel the watchdog timer if there are no pending
		 * transmissions.
		 */
		if (sc->sc_txpending == 0)
			ifp->if_timer = 0;

		/*
		 * Kick the transmitter after a DMA underrun.
		 */
		if (intstat & INTSTAT_TXU) {
			printf("%s: transmit underrun\n", sc->sc_dev.dv_xname);
			bus_space_write_4(sc->sc_st, sc->sc_sh,
			    EPIC_COMMAND, COMMAND_TXUGO);
			if (sc->sc_txpending)
				bus_space_write_4(sc->sc_st, sc->sc_sh,
				    EPIC_COMMAND, COMMAND_TXQUEUED);
		}

		/*
		 * Try to get more packets going.
		 */
		epic_start(ifp);
	}

	/*
	 * Check for fatal interrupts.
	 */
	if (intstat & INTSTAT_FATAL_INT) {
		printf("%s: fatal error, resetting\n", sc->sc_dev.dv_xname);
		epic_init(sc);
	}

	/*
	 * Check for more interrupts.
	 */
	goto top;
}

/*
 * Fixup the clock source on the EPIC.
 */
void
epic_fixup_clock_source(sc)
	struct epic_softc *sc;
{
	int i;

	/*
	 * According to SMC Application Note 7-15, the EPIC's clock
	 * source is incorrect following a reset.  This manifests itself
	 * as failure to recognize when host software has written to
	 * a register on the EPIC.  The appnote recommends issuing at
	 * least 16 consecutive writes to the CLOCK TEST bit to correctly
	 * configure the clock source.
	 */
	for (i = 0; i < 16; i++)
		bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_TEST,
		    TEST_CLOCKTEST);
}

/*
 * Perform a soft reset on the EPIC.
 */
void
epic_reset(sc)
	struct epic_softc *sc;
{

	epic_fixup_clock_source(sc);

	bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_GENCTL, 0);
	delay(100);
	bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_GENCTL, GENCTL_SOFTRESET);
	delay(100);

	epic_fixup_clock_source(sc);
}

/*
 * Initialize the interface.  Must be called at splnet().
 */
void
epic_init(sc)
	struct epic_softc *sc;
{
	bus_space_tag_t st = sc->sc_st;
	bus_space_handle_t sh = sc->sc_sh;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
	u_int8_t *enaddr = LLADDR(ifp->if_sadl);
	struct epic_txdesc *txd;
	struct epic_rxdesc *rxd;
	u_int32_t genctl, reg0;
	int i;

	/*
	 * Cancel any pending I/O.
	 */
	epic_stop(sc);

	/*
	 * Reset the EPIC to a known state.
	 */
	epic_reset(sc);

	/*
	 * Magical mystery initialization.
	 */
	bus_space_write_4(st, sh, EPIC_TXTEST, 0);

	/*
	 * Initialize the EPIC genctl register:
	 *
	 *	- 64 byte receive FIFO threshold
	 *	- automatic advance to next receive frame
	 */
	genctl = GENCTL_RX_FIFO_THRESH0 | GENCTL_ONECOPY;
	bus_space_write_4(st, sh, EPIC_GENCTL, genctl);

	/*
	 * Reset the MII bus and PHY.
	 */
	reg0 = bus_space_read_4(st, sh, EPIC_NVCTL);
	bus_space_write_4(st, sh, EPIC_NVCTL, reg0 | NVCTL_GPIO1 | NVCTL_GPOE1);
	bus_space_write_4(st, sh, EPIC_MIICFG, MIICFG_ENASER);
	bus_space_write_4(st, sh, EPIC_GENCTL, genctl | GENCTL_RESET_PHY);
	delay(100);
	bus_space_write_4(st, sh, EPIC_GENCTL, genctl);
	delay(100);
	bus_space_write_4(st, sh, EPIC_NVCTL, reg0);

	/*
	 * Initialize Ethernet address.
	 */
	reg0 = enaddr[1] << 8 | enaddr[0];
	bus_space_write_4(st, sh, EPIC_LAN0, reg0);
	reg0 = enaddr[3] << 8 | enaddr[2];
	bus_space_write_4(st, sh, EPIC_LAN1, reg0);
	reg0 = enaddr[5] << 8 | enaddr[4];
	bus_space_write_4(st, sh, EPIC_LAN2, reg0);

	/*
	 * Set up the multicast hash table.
	 */
	epic_set_mchash(sc);

	/*
	 * Initialize receive control.  Remember the external buffer
	 * size setting.
	 */
	reg0 = bus_space_read_4(st, sh, EPIC_RXCON) &
	    (RXCON_EXTBUFSIZESEL1 | RXCON_EXTBUFSIZESEL0);
	reg0 |= (RXCON_RXMULTICAST | RXCON_RXBROADCAST);
	if (ifp->if_flags & IFF_PROMISC)
		reg0 |= RXCON_PROMISCMODE;
	bus_space_write_4(st, sh, EPIC_RXCON, reg0);

	/*
	 * XXX Media (full-duplex in TXCON).
	 */

	/*
	 * Initialize the transmit descriptors.
	 */
	txd = sc->sc_control_data->ecd_txdescs;
	bzero(txd, sizeof(sc->sc_control_data->ecd_txdescs));
	for (i = 0; i < EPIC_NTXDESC; i++) {
		txd[i].et_control = ET_TXCTL_LASTDESC | ET_TXCTL_IAF |
		    ET_TXCTL_FRAGLIST;
		txd[i].et_bufaddr = sc->sc_cddma + EPIC_CDOFF(ecd_txfrags[i]);
		txd[i].et_nextdesc = sc->sc_cddma +
		    EPIC_CDOFF(ecd_txdescs[(i + 1) & EPIC_NTXDESC_MASK]);
	}

	/*
	 * Initialize the receive descriptors.  Note the buffers
	 * and control word have already been initialized; we only
	 * need to initialize the ring.
	 */
	rxd = sc->sc_control_data->ecd_rxdescs;
	for (i = 0; i < EPIC_NRXDESC; i++) {
		rxd[i].er_nextdesc = sc->sc_cddma +
		    EPIC_CDOFF(ecd_rxdescs[(i + 1) & EPIC_NRXDESC_MASK]);
	}

	/*
	 * Initialize the interrupt mask and enable interrupts.
	 */
	bus_space_write_4(st, sh, EPIC_INTMASK, INTMASK);
	bus_space_write_4(st, sh, EPIC_GENCTL, genctl | GENCTL_INTENA);

	/*
	 * Give the transmit and receive rings to the EPIC.
	 */
	bus_space_write_4(st, sh, EPIC_PTCDAR,
	    sc->sc_cddma + EPIC_CDOFF(ecd_txdescs[0]));
	bus_space_write_4(st, sh, EPIC_PRCDAR,
	    sc->sc_cddma + EPIC_CDOFF(ecd_rxdescs[0]));

	/*
	 * Initialize our ring pointers.  txlast it initialized to
	 * the end of the list so that it will wrap around to the
	 * first descriptor when the first packet is transmitted.
	 */
	sc->sc_txpending = 0;
	sc->sc_txdirty = 0;
	sc->sc_txlast = EPIC_NTXDESC - 1;

	sc->sc_rxptr = 0;

	/*
	 * Set the EPIC in motion.
	 */
	bus_space_write_4(st, sh, EPIC_COMMAND,
	    COMMAND_RXQUEUED | COMMAND_START_RX);

	/*
	 * ...all done!
	 */
	ifp->if_flags |= IFF_RUNNING;
	ifp->if_flags &= ~IFF_OACTIVE;
}

/*
 * Stop transmission on the interface.
 */
void
epic_stop(sc)
	struct epic_softc *sc;
{
	bus_space_tag_t st = sc->sc_st;
	bus_space_handle_t sh = sc->sc_sh;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
	struct epic_descsoft *ds;
	u_int32_t reg;
	int i;

	/* Paranoia... */
	epic_fixup_clock_source(sc);

	/*
	 * Disable interrupts.
	 */
	reg = bus_space_read_4(st, sh, EPIC_GENCTL);
	bus_space_write_4(st, sh, EPIC_GENCTL, reg & ~GENCTL_INTENA);
	bus_space_write_4(st, sh, EPIC_INTMASK, 0);

	/*
	 * Stop the DMA engine and take the receiver off-line.
	 */
	bus_space_write_4(st, sh, EPIC_COMMAND, COMMAND_STOP_RDMA |
	    COMMAND_STOP_TDMA | COMMAND_STOP_RX);

	/*
	 * Release any queued transmit buffers.
	 */
	for (i = 0; i < EPIC_NTXDESC; i++) {
		ds = &sc->sc_txsoft[i];
		if (ds->ds_mbuf != NULL) {
			bus_dmamap_unload(sc->sc_dmat, ds->ds_dmamap);
			m_freem(ds->ds_mbuf);
			ds->ds_mbuf = NULL;
		}
	}
	sc->sc_txpending = 0;

	/*
	 * Release the receive buffers, then reallocate/reinitialize.
	 */
	for (i = 0; i < EPIC_NRXDESC; i++) {
		ds = &sc->sc_rxsoft[i];
		if (ds->ds_mbuf != NULL) {
			bus_dmamap_unload(sc->sc_dmat, ds->ds_dmamap);
			m_freem(ds->ds_mbuf);
			ds->ds_mbuf = NULL;
		}
		if (epic_add_rxbuf(sc, i) != 0) {
			/*
			 * This "can't happen" - we're at splnet()
			 * and we just freed the buffer we need
			 * above.
			 */
			panic("epic_stop: no buffers!");
		}
	}

	/*
	 * Mark the interface down and cancel the watchdog timer.
	 */
	ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
	ifp->if_timer = 0;
}

/*
 * Read the EPIC Serial EEPROM.
 */
void
epic_read_eeprom(sc, word, wordcnt, data)
	struct epic_softc *sc;
	int word, wordcnt;
	u_int16_t *data;
{
	bus_space_tag_t st = sc->sc_st;
	bus_space_handle_t sh = sc->sc_sh;
	u_int16_t reg;
	int i, x;

#define	EEPROM_WAIT_READY(st, sh) \
	while ((bus_space_read_4((st), (sh), EPIC_EECTL) & EECTL_EERDY) == 0) \
		/* nothing */

	/*
	 * Enable the EEPROM.
	 */
	bus_space_write_4(st, sh, EPIC_EECTL, EECTL_ENABLE);
	EEPROM_WAIT_READY(st, sh);

	for (i = 0; i < wordcnt; i++) {
		/* Send CHIP SELECT for one clock tick. */
		bus_space_write_4(st, sh, EPIC_EECTL, EECTL_ENABLE|EECTL_EECS);
		EEPROM_WAIT_READY(st, sh);

		/* Shift in the READ opcode. */
		for (x = 3; x > 0; x--) {
			reg = EECTL_ENABLE|EECTL_EECS;
			if (EPIC_EEPROM_OPC_READ & (1 << (x - 1)))
				reg |= EECTL_EEDI;
			bus_space_write_4(st, sh, EPIC_EECTL, reg);
			EEPROM_WAIT_READY(st, sh);
			bus_space_write_4(st, sh, EPIC_EECTL, reg|EECTL_EESK);
			EEPROM_WAIT_READY(st, sh);
			bus_space_write_4(st, sh, EPIC_EECTL, reg);
			EEPROM_WAIT_READY(st, sh);
		}

		/* Shift in address. */
		for (x = 6; x > 0; x--) {
			reg = EECTL_ENABLE|EECTL_EECS;
			if ((word + i) & (1 << (x - 1)))
				reg |= EECTL_EEDI; 
			bus_space_write_4(st, sh, EPIC_EECTL, reg);
			EEPROM_WAIT_READY(st, sh);
			bus_space_write_4(st, sh, EPIC_EECTL, reg|EECTL_EESK);
			EEPROM_WAIT_READY(st, sh);
			bus_space_write_4(st, sh, EPIC_EECTL, reg);
			EEPROM_WAIT_READY(st, sh);
		}

		/* Shift out data. */
		reg = EECTL_ENABLE|EECTL_EECS;
		data[i] = 0;
		for (x = 16; x > 0; x--) {
			bus_space_write_4(st, sh, EPIC_EECTL, reg|EECTL_EESK);
			EEPROM_WAIT_READY(st, sh);
			if (bus_space_read_4(st, sh, EPIC_EECTL) & EECTL_EEDO)
				data[i] |= (1 << (x - 1));
			bus_space_write_4(st, sh, EPIC_EECTL, reg);
			EEPROM_WAIT_READY(st, sh);
		}

		/* Clear CHIP SELECT. */
		bus_space_write_4(st, sh, EPIC_EECTL, EECTL_ENABLE);
		EEPROM_WAIT_READY(st, sh);
	}

	/*
	 * Disable the EEPROM.
	 */
	bus_space_write_4(st, sh, EPIC_EECTL, 0);

#undef EEPROM_WAIT_READY
}

/*
 * Add a receive buffer to the indicated descriptor.
 */
int
epic_add_rxbuf(sc, idx)	
	struct epic_softc *sc;
	int idx;
{
	struct epic_rxdesc *rxd = &sc->sc_control_data->ecd_rxdescs[idx];
	struct epic_descsoft *ds = &sc->sc_rxsoft[idx];
	struct mbuf *m, *oldm;
	int error = 0;

	oldm = ds->ds_mbuf;

	MGETHDR(m, M_DONTWAIT, MT_DATA);
	if (m != NULL) {
		MCLGET(m, M_DONTWAIT);
		if ((m->m_flags & M_EXT) == 0) {
			error = ENOMEM;
			m_freem(m);
			if (oldm == NULL)
				return (error);
			m = oldm;
			m->m_data = m->m_ext.ext_buf;
		}
	} else {
		error = ENOMEM;
		if (oldm == NULL)
			return (error);
		m = oldm;
		m->m_data = m->m_ext.ext_buf;
	}

	ds->ds_mbuf = m;

	/*
	 * Set up the DMA map for this receive buffer.
	 */
	if (m != oldm) {
		if (oldm != NULL)
			bus_dmamap_unload(sc->sc_dmat, ds->ds_dmamap);
		error = bus_dmamap_load(sc->sc_dmat, ds->ds_dmamap,
		    m->m_ext.ext_buf, m->m_ext.ext_size, NULL, BUS_DMA_NOWAIT);
		if (error) {
			printf("%s: can't load rx buffer, error = %d\n",
			    sc->sc_dev.dv_xname, error);
			panic("epic_add_rxbuf");	/* XXX */
		}
	}

	bus_dmamap_sync(sc->sc_dmat, ds->ds_dmamap, 0,
	    ds->ds_dmamap->dm_mapsize, BUS_DMASYNC_PREREAD);

	/*
	 * Move the data pointer up so that the incoming packet
	 * will be 32-bit aligned.
	 */
	m->m_data += RX_ALIGNMENT_FUDGE;

	/*
	 * Initialize the receive descriptor.
	 */
	rxd->er_bufaddr = ds->ds_dmamap->dm_segs[0].ds_addr +
	    RX_ALIGNMENT_FUDGE;
	rxd->er_buflength = m->m_ext.ext_size - RX_ALIGNMENT_FUDGE;
	rxd->er_control = 0;
	rxd->er_rxstatus = ER_RXSTAT_OWNER;

	return (error);
}

/*
 * Set the EPIC multicast hash table.
 */
void
epic_set_mchash(sc)
	struct epic_softc *sc;
{
	struct ethercom *ec = &sc->sc_ethercom;
	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
	struct ether_multi *enm;
	struct ether_multistep step;
	u_int8_t *cp;
	u_int32_t crc, mchash[4];
	int len;
	static const u_int32_t crctab[] = {
		0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
		0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
		0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
		0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
	};

	/*
	 * Set up the multicast address filter by passing all multicast
	 * addresses through a CRC generator, and then using the high-order
	 * 6 bits as an index into the 64 bit multicast hash table (only
	 * the lower 16 bits of each 32 bit multicast hash register are
	 * valid).  The high order bit selects the register, while the
	 * rest of the bits select the bit within the register.
	 */

	if (ifp->if_flags & IFF_PROMISC)
		goto allmulti;

#if 1 /* XXX thorpej - hardware bug in 10Mb mode */
	goto allmulti;
#endif

	mchash[0] = mchash[1] = mchash[2] = mchash[3] = 0;

	ETHER_FIRST_MULTI(step, ec, enm);
	while (enm != NULL) {
		if (bcmp(enm->enm_addrlo, enm->enm_addrhi, ETHER_ADDR_LEN)) {
			/*
			 * We must listen to a range of multicast addresses.
			 * For now, just accept all multicasts, rather than
			 * trying to set only those filter bits needed to match
			 * the range.  (At this time, the only use of address
			 * ranges is for IP multicast routing, for which the
			 * range is big enough to require all bits set.)
			 */
			goto allmulti;
		}

		cp = enm->enm_addrlo;
		crc = 0xffffffff;
		for (len = sizeof(enm->enm_addrlo); --len >= 0;) {
			crc ^= *cp++;
			crc = (crc >> 4) ^ crctab[crc & 0xf];
			crc = (crc >> 4) ^ crctab[crc & 0xf];
		}
		/* Just want the 6 most significant bits. */
		crc >>= 26;

		/* Set the corresponding bit in the hash table. */
		mchash[crc >> 4] |= 1 << (crc & 0xf);

		ETHER_NEXT_MULTI(step, enm);
	}

	ifp->if_flags &= ~IFF_ALLMULTI;
	goto sethash;

 allmulti:
	ifp->if_flags |= IFF_ALLMULTI;
	mchash[0] = mchash[1] = mchash[2] = mchash[3] = 0xffff;

 sethash:
	bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_MC0, mchash[0]);
	bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_MC1, mchash[1]);
	bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_MC2, mchash[2]);
	bus_space_write_4(sc->sc_st, sc->sc_sh, EPIC_MC3, mchash[3]);
}