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[netbsd-mini2440.git] / sys / arch / mips / atheros / dev / if_ae.c

/* $Id: if_ae.c,v 1.16 2009/11/12 19:18:55 dyoung Exp $ */
/*-
 * Copyright (c) 2006 Urbana-Champaign Independent Media Center.
 * Copyright (c) 2006 Garrett D'Amore.
 * All rights reserved.
 *
 * This code was written by Garrett D'Amore for the Champaign-Urbana
 * Community Wireless Network Project.
 *
 * 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 acknowledgements:
 *      This product includes software developed by the Urbana-Champaign
 *      Independent Media Center.
 *      This product includes software developed by Garrett D'Amore.
 * 4. Urbana-Champaign Independent Media Center's name and Garrett
 *    D'Amore's name may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE URBANA-CHAMPAIGN INDEPENDENT
 * MEDIA CENTER AND GARRETT D'AMORE ``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 URBANA-CHAMPAIGN INDEPENDENT
 * MEDIA CENTER OR GARRETT D'AMORE 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.
 */
/*-
 * Copyright (c) 1998, 1999, 2000, 2002 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; and by Charles M. Hannum.
 *
 * 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.
 *
 * 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 onboard ethernet MAC found on the AR5312
 * chip's AHB bus.
 *
 * This device is very simliar to the tulip in most regards, and
 * the code is directly derived from NetBSD's tulip.c.  However, it
 * is different enough that it did not seem to be a good idea to
 * add further complexity to the tulip driver, so we have our own.
 *
 * Also tulip has a lot of complexity in it for various parts/options
 * that we don't need, and on these little boxes with only ~8MB RAM, we
 * don't want any extra bloat.
 */

/*
 * TODO:
 *
 * 1) Find out about BUS_MODE_ALIGN16B.  This chip can apparently align
 *    inbound packets on a half-word boundary, which would make life easier
 *    for TCP/IP.  (Aligning IP headers on a word.)
 *
 * 2) There is stuff in original tulip to shut down the device when reacting
 *    to a a change in link status.  Is that needed.
 *
 * 3) Test with variety of 10/100 HDX/FDX scenarios.
 *
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_ae.c,v 1.15 2008/11/07 00:20:02 dyoung Exp $");

#include "bpfilter.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.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 <machine/endian.h>

#include <uvm/uvm_extern.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

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

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

#include <mips/atheros/include/arbusvar.h>
#include <mips/atheros/dev/aereg.h>
#include <mips/atheros/dev/aevar.h>

static const struct {
        u_int32_t txth_opmode;          /* OPMODE bits */
        const char *txth_name;          /* name of mode */
} ae_txthresh[] = {
        { OPMODE_TR_32,         "32 words" },
        { OPMODE_TR_64,         "64 words" },
        { OPMODE_TR_128,        "128 words" },
        { OPMODE_TR_256,        "256 words" },
        { OPMODE_SF,            "store and forward mode" },
        { 0,                    NULL },
};

static int      ae_match(device_t, struct cfdata *, void *);
static void     ae_attach(device_t, device_t, void *);
static int      ae_detach(device_t, int);
static int      ae_activate(device_t, enum devact);

static int      ae_ifflags_cb(struct ethercom *);
static void     ae_reset(struct ae_softc *);
static void     ae_idle(struct ae_softc *, u_int32_t);

static void     ae_start(struct ifnet *);
static void     ae_watchdog(struct ifnet *);
static int      ae_ioctl(struct ifnet *, u_long, void *);
static int      ae_init(struct ifnet *);
static void     ae_stop(struct ifnet *, int);

static void     ae_shutdown(void *);

static void     ae_rxdrain(struct ae_softc *);
static int      ae_add_rxbuf(struct ae_softc *, int);

static int      ae_enable(struct ae_softc *);
static void     ae_disable(struct ae_softc *);
static void     ae_power(int, void *);

static void     ae_filter_setup(struct ae_softc *);

static int      ae_intr(void *);
static void     ae_rxintr(struct ae_softc *);
static void     ae_txintr(struct ae_softc *);

static void     ae_mii_tick(void *);
static void     ae_mii_statchg(device_t);

static int      ae_mii_readreg(device_t, int, int);
static void     ae_mii_writereg(device_t, int, int, int);

#ifdef AE_DEBUG
#define DPRINTF(sc, x)  if ((sc)->sc_ethercom.ec_if.if_flags & IFF_DEBUG) \
                                printf x
#else
#define DPRINTF(sc, x)  /* nothing */
#endif

#ifdef AE_STATS
static void     ae_print_stats(struct ae_softc *);
#endif

CFATTACH_DECL(ae, sizeof(struct ae_softc),
    ae_match, ae_attach, ae_detach, ae_activate);

/*
 * ae_match:
 *
 *      Check for a device match.
 */
int
ae_match(device_t parent, struct cfdata *cf, void *aux)
{
        struct arbus_attach_args *aa = aux;

        if (strcmp(aa->aa_name, cf->cf_name) == 0)
                return 1;

        return 0;

}

/*
 * ae_attach:
 *
 *      Attach an ae interface to the system.
 */
void
ae_attach(device_t parent, device_t self, void *aux)
{
        const uint8_t *enaddr;
        prop_data_t ea;
        struct ae_softc *sc = device_private(self);
        struct arbus_attach_args *aa = aux;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        int i, error;

        callout_init(&sc->sc_tick_callout, 0);

        printf(": Atheros AR531X 10/100 Ethernet\n");

        /*
         * Try to get MAC address.
         */
        ea = prop_dictionary_get(device_properties(&sc->sc_dev), "mac-addr");
        if (ea == NULL) {
                printf("%s: unable to get mac-addr property\n",
                    sc->sc_dev.dv_xname);
                return;
        }
        KASSERT(prop_object_type(ea) == PROP_TYPE_DATA);
        KASSERT(prop_data_size(ea) == ETHER_ADDR_LEN);
        enaddr = prop_data_data_nocopy(ea);

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

        sc->sc_cirq = aa->aa_cirq;
        sc->sc_mirq = aa->aa_mirq;
        sc->sc_st = aa->aa_bst;
        sc->sc_dmat = aa->aa_dmat;

        SIMPLEQ_INIT(&sc->sc_txfreeq);
        SIMPLEQ_INIT(&sc->sc_txdirtyq);

        /*
         * Map registers.
         */
        sc->sc_size = aa->aa_size;
        if ((error = bus_space_map(sc->sc_st, aa->aa_addr, sc->sc_size, 0,
            &sc->sc_sh)) != 0) {
                printf("%s: unable to map registers, error = %d\n",
                    sc->sc_dev.dv_xname, error);
                goto fail_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 ae_control_data), PAGE_SIZE, 0, &sc->sc_cdseg,
            1, &sc->sc_cdnseg, 0)) != 0) {
                printf("%s: unable to allocate control data, error = %d\n",
                    sc->sc_dev.dv_xname, error);
                goto fail_1;
        }

        if ((error = bus_dmamem_map(sc->sc_dmat, &sc->sc_cdseg, sc->sc_cdnseg,
            sizeof(struct ae_control_data), (void **)&sc->sc_control_data,
            BUS_DMA_COHERENT)) != 0) {
                printf("%s: unable to map control data, error = %d\n",
                    sc->sc_dev.dv_xname, error);
                goto fail_2;
        }

        if ((error = bus_dmamap_create(sc->sc_dmat,
            sizeof(struct ae_control_data), 1,
            sizeof(struct ae_control_data), 0, 0, &sc->sc_cddmamap)) != 0) {
                printf("%s: unable to create control data DMA map, "
                    "error = %d\n", sc->sc_dev.dv_xname, error);
                goto fail_3;
        }

        if ((error = bus_dmamap_load(sc->sc_dmat, sc->sc_cddmamap,
            sc->sc_control_data, sizeof(struct ae_control_data), NULL,
            0)) != 0) {
                printf("%s: unable to load control data DMA map, error = %d\n",
                    sc->sc_dev.dv_xname, error);
                goto fail_4;
        }

        /*
         * Create the transmit buffer DMA maps.
         */
        for (i = 0; i < AE_TXQUEUELEN; i++) {
                if ((error = bus_dmamap_create(sc->sc_dmat, MCLBYTES,
                    AE_NTXSEGS, MCLBYTES, 0, 0,
                    &sc->sc_txsoft[i].txs_dmamap)) != 0) {
                        printf("%s: unable to create tx DMA map %d, "
                            "error = %d\n", sc->sc_dev.dv_xname, i, error);
                        goto fail_5;
                }
        }

        /*
         * Create the receive buffer DMA maps.
         */
        for (i = 0; i < AE_NRXDESC; i++) {
                if ((error = bus_dmamap_create(sc->sc_dmat, MCLBYTES, 1,
                    MCLBYTES, 0, 0, &sc->sc_rxsoft[i].rxs_dmamap)) != 0) {
                        printf("%s: unable to create rx DMA map %d, "
                            "error = %d\n", sc->sc_dev.dv_xname, i, error);
                        goto fail_6;
                }
                sc->sc_rxsoft[i].rxs_mbuf = NULL;
        }

        /*
         * Reset the chip to a known state.
         */
        ae_reset(sc);

        /*
         * From this point forward, the attachment cannot fail.  A failure
         * before this point releases all resources that may have been
         * allocated.
         */
        sc->sc_flags |= AE_ATTACHED;

        /*
         * Initialize our media structures.  This may probe the MII, if
         * present.
         */
        sc->sc_mii.mii_ifp = ifp;
        sc->sc_mii.mii_readreg = ae_mii_readreg;
        sc->sc_mii.mii_writereg = ae_mii_writereg;
        sc->sc_mii.mii_statchg = ae_mii_statchg;
        sc->sc_ethercom.ec_mii = &sc->sc_mii;
        ifmedia_init(&sc->sc_mii.mii_media, 0, ether_mediachange,
            ether_mediastatus);
        mii_attach(&sc->sc_dev, &sc->sc_mii, 0xffffffff, MII_PHY_ANY,
            MII_OFFSET_ANY, 0);

        if (LIST_FIRST(&sc->sc_mii.mii_phys) == NULL) {
                ifmedia_add(&sc->sc_mii.mii_media, IFM_ETHER|IFM_NONE, 0, NULL);
                ifmedia_set(&sc->sc_mii.mii_media, IFM_ETHER|IFM_NONE);
        } else
                ifmedia_set(&sc->sc_mii.mii_media, IFM_ETHER|IFM_AUTO);

        sc->sc_tick = ae_mii_tick;

        strcpy(ifp->if_xname, sc->sc_dev.dv_xname);
        ifp->if_softc = sc;
        ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
        sc->sc_if_flags = ifp->if_flags;
        ifp->if_ioctl = ae_ioctl;
        ifp->if_start = ae_start;
        ifp->if_watchdog = ae_watchdog;
        ifp->if_init = ae_init;
        ifp->if_stop = ae_stop;
        IFQ_SET_READY(&ifp->if_snd);

        /*
         * We can support 802.1Q VLAN-sized frames.
         */
        sc->sc_ethercom.ec_capabilities |= ETHERCAP_VLAN_MTU;

        /*
         * Attach the interface.
         */
        if_attach(ifp);
        ether_ifattach(ifp, enaddr);
        ether_set_ifflags_cb(&sc->sc_ethercom, ae_ifflags_cb);

#if NRND > 0
        rnd_attach_source(&sc->sc_rnd_source, sc->sc_dev.dv_xname,
            RND_TYPE_NET, 0);
#endif

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

        /*
         * Add a suspend hook to make sure we come back up after a
         * resume.
         */
        sc->sc_powerhook = powerhook_establish(sc->sc_dev.dv_xname,
            ae_power, sc);
        if (sc->sc_powerhook == NULL)
                printf("%s: WARNING: unable to establish power hook\n",
                    sc->sc_dev.dv_xname);
        return;

        /*
         * Free any resources we've allocated during the failed attach
         * attempt.  Do this in reverse order and fall through.
         */
 fail_6:
        for (i = 0; i < AE_NRXDESC; i++) {
                if (sc->sc_rxsoft[i].rxs_dmamap != NULL)
                        bus_dmamap_destroy(sc->sc_dmat,
                            sc->sc_rxsoft[i].rxs_dmamap);
        }
 fail_5:
        for (i = 0; i < AE_TXQUEUELEN; i++) {
                if (sc->sc_txsoft[i].txs_dmamap != NULL)
                        bus_dmamap_destroy(sc->sc_dmat,
                            sc->sc_txsoft[i].txs_dmamap);
        }
        bus_dmamap_unload(sc->sc_dmat, sc->sc_cddmamap);
 fail_4:
        bus_dmamap_destroy(sc->sc_dmat, sc->sc_cddmamap);
 fail_3:
        bus_dmamem_unmap(sc->sc_dmat, (void *)sc->sc_control_data,
            sizeof(struct ae_control_data));
 fail_2:
        bus_dmamem_free(sc->sc_dmat, &sc->sc_cdseg, sc->sc_cdnseg);
 fail_1:
        bus_space_unmap(sc->sc_st, sc->sc_sh, sc->sc_size);
 fail_0:
        return;
}

/*
 * ae_activate:
 *
 *      Handle device activation/deactivation requests.
 */
int
ae_activate(device_t self, enum devact act)
{
        struct ae_softc *sc = device_private(self);

        switch (act) {
        case DVACT_DEACTIVATE:
                if_deactivate(&sc->sc_ethercom.ec_if);
                return 0;
        default:
                return EOPNOTSUPP;
        }
}

/*
 * ae_detach:
 *
 *      Detach a device interface.
 */
int
ae_detach(device_t self, int flags)
{
        struct ae_softc *sc = device_private(self);
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct ae_rxsoft *rxs;
        struct ae_txsoft *txs;
        int i;

        /*
         * Succeed now if there isn't any work to do.
         */
        if ((sc->sc_flags & AE_ATTACHED) == 0)
                return (0);

        /* Unhook our tick handler. */
        if (sc->sc_tick)
                callout_stop(&sc->sc_tick_callout);

        /* Detach all PHYs */
        mii_detach(&sc->sc_mii, MII_PHY_ANY, MII_OFFSET_ANY);

        /* Delete all remaining media. */
        ifmedia_delete_instance(&sc->sc_mii.mii_media, IFM_INST_ANY);

#if NRND > 0
        rnd_detach_source(&sc->sc_rnd_source);
#endif
        ether_ifdetach(ifp);
        if_detach(ifp);

        for (i = 0; i < AE_NRXDESC; i++) {
                rxs = &sc->sc_rxsoft[i];
                if (rxs->rxs_mbuf != NULL) {
                        bus_dmamap_unload(sc->sc_dmat, rxs->rxs_dmamap);
                        m_freem(rxs->rxs_mbuf);
                        rxs->rxs_mbuf = NULL;
                }
                bus_dmamap_destroy(sc->sc_dmat, rxs->rxs_dmamap);
        }
        for (i = 0; i < AE_TXQUEUELEN; i++) {
                txs = &sc->sc_txsoft[i];
                if (txs->txs_mbuf != NULL) {
                        bus_dmamap_unload(sc->sc_dmat, txs->txs_dmamap);
                        m_freem(txs->txs_mbuf);
                        txs->txs_mbuf = NULL;
                }
                bus_dmamap_destroy(sc->sc_dmat, txs->txs_dmamap);
        }
        bus_dmamap_unload(sc->sc_dmat, sc->sc_cddmamap);
        bus_dmamap_destroy(sc->sc_dmat, sc->sc_cddmamap);
        bus_dmamem_unmap(sc->sc_dmat, (void *)sc->sc_control_data,
            sizeof(struct ae_control_data));
        bus_dmamem_free(sc->sc_dmat, &sc->sc_cdseg, sc->sc_cdnseg);

        shutdownhook_disestablish(sc->sc_sdhook);
        powerhook_disestablish(sc->sc_powerhook);

        bus_space_unmap(sc->sc_st, sc->sc_sh, sc->sc_size);


        return (0);
}

/*
 * ae_shutdown:
 *
 *      Make sure the interface is stopped at reboot time.
 */
static void
ae_shutdown(void *arg)
{
        struct ae_softc *sc = arg;

        ae_stop(&sc->sc_ethercom.ec_if, 1);
}

/*
 * ae_start:            [ifnet interface function]
 *
 *      Start packet transmission on the interface.
 */
static void
ae_start(struct ifnet *ifp)
{
        struct ae_softc *sc = ifp->if_softc;
        struct mbuf *m0, *m;
        struct ae_txsoft *txs, *last_txs = NULL;
        bus_dmamap_t dmamap;
        int error, firsttx, nexttx, lasttx = 1, ofree, seg;

        DPRINTF(sc, ("%s: ae_start: sc_flags 0x%08x, if_flags 0x%08x\n",
            sc->sc_dev.dv_xname, sc->sc_flags, ifp->if_flags));


        if ((ifp->if_flags & (IFF_RUNNING|IFF_OACTIVE)) != IFF_RUNNING)
                return;

        /*
         * Remember the previous number of free descriptors and
         * the first descriptor we'll use.
         */
        ofree = sc->sc_txfree;
        firsttx = sc->sc_txnext;

        DPRINTF(sc, ("%s: ae_start: txfree %d, txnext %d\n",
            sc->sc_dev.dv_xname, ofree, firsttx));

        /*
         * Loop through the send queue, setting up transmit descriptors
         * until we drain the queue, or use up all available transmit
         * descriptors.
         */
        while ((txs = SIMPLEQ_FIRST(&sc->sc_txfreeq)) != NULL &&
               sc->sc_txfree != 0) {
                /*
                 * Grab a packet off the queue.
                 */
                IFQ_POLL(&ifp->if_snd, m0);
                if (m0 == NULL)
                        break;
                m = NULL;

                dmamap = txs->txs_dmamap;

                /*
                 * Load the DMA map.  If this fails, the packet either
                 * didn't fit in the alloted number of segments, or we were
                 * short on resources.  In this case, we'll copy and try
                 * again.
                 */
                if (((mtod(m0, uintptr_t) & 3) != 0) ||
                    bus_dmamap_load_mbuf(sc->sc_dmat, dmamap, m0,
                      BUS_DMA_WRITE|BUS_DMA_NOWAIT) != 0) {
                        MGETHDR(m, M_DONTWAIT, MT_DATA);
                        if (m == NULL) {
                                printf("%s: unable to allocate Tx mbuf\n",
                                    sc->sc_dev.dv_xname);
                                break;
                        }
                        MCLAIM(m, &sc->sc_ethercom.ec_tx_mowner);
                        if (m0->m_pkthdr.len > MHLEN) {
                                MCLGET(m, M_DONTWAIT);
                                if ((m->m_flags & M_EXT) == 0) {
                                        printf("%s: unable to allocate Tx "
                                            "cluster\n", sc->sc_dev.dv_xname);
                                        m_freem(m);
                                        break;
                                }
                        }
                        m_copydata(m0, 0, m0->m_pkthdr.len, mtod(m, void *));
                        m->m_pkthdr.len = m->m_len = m0->m_pkthdr.len;
                        error = bus_dmamap_load_mbuf(sc->sc_dmat, dmamap,
                            m, BUS_DMA_WRITE|BUS_DMA_NOWAIT);
                        if (error) {
                                printf("%s: unable to load Tx buffer, "
                                    "error = %d\n", sc->sc_dev.dv_xname,
                                    error);
                                break;
                        }
                }

                /*
                 * Ensure we have enough descriptors free to describe
                 * the packet.
                 */
                if (dmamap->dm_nsegs > sc->sc_txfree) {
                        /*
                         * Not enough free descriptors to transmit this
                         * packet.  We haven't committed to anything yet,
                         * so just unload the DMA map, put the packet
                         * back on the queue, and punt.  Notify the upper
                         * layer that there are no more slots left.
                         *
                         * XXX We could allocate an mbuf and copy, but
                         * XXX it is worth it?
                         */
                        ifp->if_flags |= IFF_OACTIVE;
                        bus_dmamap_unload(sc->sc_dmat, dmamap);
                        if (m != NULL)
                                m_freem(m);
                        break;
                }

                IFQ_DEQUEUE(&ifp->if_snd, m0);
                if (m != NULL) {
                        m_freem(m0);
                        m0 = m;
                }

                /*
                 * WE ARE NOW COMMITTED TO TRANSMITTING THE PACKET.
                 */

                /* Sync the DMA map. */
                bus_dmamap_sync(sc->sc_dmat, dmamap, 0, dmamap->dm_mapsize,
                    BUS_DMASYNC_PREWRITE);

                /*
                 * Initialize the transmit descriptors.
                 */
                for (nexttx = sc->sc_txnext, seg = 0;
                     seg < dmamap->dm_nsegs;
                     seg++, nexttx = AE_NEXTTX(nexttx)) {
                        /*
                         * If this is the first descriptor we're
                         * enqueueing, don't set the OWN bit just
                         * yet.  That could cause a race condition.
                         * We'll do it below.
                         */
                        sc->sc_txdescs[nexttx].ad_status =
                            (nexttx == firsttx) ? 0 : ADSTAT_OWN;
                        sc->sc_txdescs[nexttx].ad_bufaddr1 =
                            dmamap->dm_segs[seg].ds_addr;
                        sc->sc_txdescs[nexttx].ad_ctl =
                            (dmamap->dm_segs[seg].ds_len <<
                                ADCTL_SIZE1_SHIFT) |
                                (nexttx == (AE_NTXDESC - 1) ?
                                    ADCTL_ER : 0);
                        lasttx = nexttx;
                }

                KASSERT(lasttx != -1);

                /* Set `first segment' and `last segment' appropriately. */
                sc->sc_txdescs[sc->sc_txnext].ad_ctl |= ADCTL_Tx_FS;
                sc->sc_txdescs[lasttx].ad_ctl |= ADCTL_Tx_LS;

#ifdef AE_DEBUG
                if (ifp->if_flags & IFF_DEBUG) {
                        printf("     txsoft %p transmit chain:\n", txs);
                        for (seg = sc->sc_txnext;; seg = AE_NEXTTX(seg)) {
                                printf("     descriptor %d:\n", seg);
                                printf("       ad_status:   0x%08x\n",
                                    sc->sc_txdescs[seg].ad_status);
                                printf("       ad_ctl:      0x%08x\n",
                                    sc->sc_txdescs[seg].ad_ctl);
                                printf("       ad_bufaddr1: 0x%08x\n",
                                    sc->sc_txdescs[seg].ad_bufaddr1);
                                printf("       ad_bufaddr2: 0x%08x\n",
                                    sc->sc_txdescs[seg].ad_bufaddr2);
                                if (seg == lasttx)
                                        break;
                        }
                }
#endif

                /* Sync the descriptors we're using. */
                AE_CDTXSYNC(sc, sc->sc_txnext, dmamap->dm_nsegs,
                    BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);

                /*
                 * Store a pointer to the packet so we can free it later,
                 * and remember what txdirty will be once the packet is
                 * done.
                 */
                txs->txs_mbuf = m0;
                txs->txs_firstdesc = sc->sc_txnext;
                txs->txs_lastdesc = lasttx;
                txs->txs_ndescs = dmamap->dm_nsegs;

                /* Advance the tx pointer. */
                sc->sc_txfree -= dmamap->dm_nsegs;
                sc->sc_txnext = nexttx;

                SIMPLEQ_REMOVE_HEAD(&sc->sc_txfreeq, txs_q);
                SIMPLEQ_INSERT_TAIL(&sc->sc_txdirtyq, txs, txs_q);

                last_txs = txs;

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

        if (txs == NULL || sc->sc_txfree == 0) {
                /* No more slots left; notify upper layer. */
                ifp->if_flags |= IFF_OACTIVE;
        }

        if (sc->sc_txfree != ofree) {
                DPRINTF(sc, ("%s: packets enqueued, IC on %d, OWN on %d\n",
                    sc->sc_dev.dv_xname, lasttx, firsttx));
                /*
                 * Cause a transmit interrupt to happen on the
                 * last packet we enqueued.
                 */
                sc->sc_txdescs[lasttx].ad_ctl |= ADCTL_Tx_IC;
                AE_CDTXSYNC(sc, lasttx, 1,
                    BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);

                /*
                 * The entire packet chain is set up.  Give the
                 * first descriptor to the chip now.
                 */
                sc->sc_txdescs[firsttx].ad_status |= ADSTAT_OWN;
                AE_CDTXSYNC(sc, firsttx, 1,
                    BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);

                /* Wake up the transmitter. */
                /* XXX USE AUTOPOLLING? */
                AE_WRITE(sc, CSR_TXPOLL, TXPOLL_TPD);
                AE_BARRIER(sc);

                /* Set a watchdog timer in case the chip flakes out. */
                ifp->if_timer = 5;
        }
}

/*
 * ae_watchdog: [ifnet interface function]
 *
 *      Watchdog timer handler.
 */
static void
ae_watchdog(struct ifnet *ifp)
{
        struct ae_softc *sc = ifp->if_softc;
        int doing_transmit;

        doing_transmit = (! SIMPLEQ_EMPTY(&sc->sc_txdirtyq));

        if (doing_transmit) {
                printf("%s: transmit timeout\n", sc->sc_dev.dv_xname);
                ifp->if_oerrors++;
        }
        else
                printf("%s: spurious watchdog timeout\n", sc->sc_dev.dv_xname);

        (void) ae_init(ifp);

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

/* If the interface is up and running, only modify the receive
 * filter when changing to/from promiscuous mode.  Otherwise return
 * ENETRESET so that ether_ioctl will reset the chip.
 */
static int
ae_ifflags_cb(struct ethercom *ec)
{
        struct ifnet *ifp = &ec->ec_if;
        struct ae_softc *sc = ifp->if_softc;
        int change = ifp->if_flags ^ sc->sc_if_flags;

        if ((change & ~(IFF_CANTCHANGE|IFF_DEBUG)) != 0)
                return ENETRESET;
        else if ((change & IFF_PROMISC) != 0)
                ae_filter_setup(sc);
        return 0;
}

/*
 * ae_ioctl:            [ifnet interface function]
 *
 *      Handle control requests from the operator.
 */
static int
ae_ioctl(struct ifnet *ifp, u_long cmd, void *data)
{
        struct ae_softc *sc = ifp->if_softc;
        int s, error;

        s = splnet();

        error = ether_ioctl(ifp, cmd, data);
        if (error == ENETRESET) {
                if (ifp->if_flags & IFF_RUNNING) {
                        /*
                         * Multicast list has changed.  Set the
                         * hardware filter accordingly.
                         */
                        ae_filter_setup(sc);
                }
                error = 0;
        }

        /* Try to get more packets going. */
        if (AE_IS_ENABLED(sc))
                ae_start(ifp);

        sc->sc_if_flags = ifp->if_flags;
        splx(s);
        return (error);
}

/*
 * ae_intr:
 *
 *      Interrupt service routine.
 */
int
ae_intr(void *arg)
{
        struct ae_softc *sc = arg;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        u_int32_t status, rxstatus, txstatus;
        int handled = 0, txthresh;

        DPRINTF(sc, ("%s: ae_intr\n", sc->sc_dev.dv_xname));

#ifdef DEBUG
        if (AE_IS_ENABLED(sc) == 0)
                panic("%s: ae_intr: not enabled", sc->sc_dev.dv_xname);
#endif

        /*
         * If the interface isn't running, the interrupt couldn't
         * possibly have come from us.
         */
        if ((ifp->if_flags & IFF_RUNNING) == 0 ||
            !device_is_active(&sc->sc_dev)) {
                printf("spurious?!?\n");
                return (0);
        }

        for (;;) {
                status = AE_READ(sc, CSR_STATUS);
                if (status) {
                        AE_WRITE(sc, CSR_STATUS, status);
                        AE_BARRIER(sc);
                }

                if ((status & sc->sc_inten) == 0)
                        break;

                handled = 1;

                rxstatus = status & sc->sc_rxint_mask;
                txstatus = status & sc->sc_txint_mask;

                if (rxstatus) {
                        /* Grab new any new packets. */
                        ae_rxintr(sc);

                        if (rxstatus & STATUS_RU) {
                                printf("%s: receive ring overrun\n",
                                    sc->sc_dev.dv_xname);
                                /* Get the receive process going again. */
                                AE_WRITE(sc, CSR_RXPOLL, RXPOLL_RPD);
                                AE_BARRIER(sc);
                                break;
                        }
                }

                if (txstatus) {
                        /* Sweep up transmit descriptors. */
                        ae_txintr(sc);

                        if (txstatus & STATUS_TJT)
                                printf("%s: transmit jabber timeout\n",
                                    sc->sc_dev.dv_xname);

                        if (txstatus & STATUS_UNF) {
                                /*
                                 * Increase our transmit threshold if
                                 * another is available.
                                 */
                                txthresh = sc->sc_txthresh + 1;
                                if (ae_txthresh[txthresh].txth_name != NULL) {
                                        uint32_t opmode;
                                        /* Idle the transmit process. */
                                        opmode = AE_READ(sc, CSR_OPMODE);
                                        ae_idle(sc, OPMODE_ST);

                                        sc->sc_txthresh = txthresh;
                                        opmode &=
                                            ~(OPMODE_TR|OPMODE_SF);
                                        opmode |=
                                            ae_txthresh[txthresh].txth_opmode;
                                        printf("%s: transmit underrun; new "
                                            "threshold: %s\n",
                                            sc->sc_dev.dv_xname,
                                            ae_txthresh[txthresh].txth_name);

                                        /*
                                         * Set the new threshold and restart
                                         * the transmit process.
                                         */
                                        AE_WRITE(sc, CSR_OPMODE, opmode);
                                        AE_BARRIER(sc);
                                }
                                        /*
                                         * XXX Log every Nth underrun from
                                         * XXX now on?
                                         */
                        }
                }

                if (status & (STATUS_TPS|STATUS_RPS)) {
                        if (status & STATUS_TPS)
                                printf("%s: transmit process stopped\n",
                                    sc->sc_dev.dv_xname);
                        if (status & STATUS_RPS)
                                printf("%s: receive process stopped\n",
                                    sc->sc_dev.dv_xname);
                        (void) ae_init(ifp);
                        break;
                }

                if (status & STATUS_SE) {
                        const char *str;

                        if (status & STATUS_TX_ABORT)
                                str = "tx abort";
                        else if (status & STATUS_RX_ABORT)
                                str = "rx abort";
                        else
                                str = "unknown error";

                        printf("%s: fatal system error: %s\n",
                            sc->sc_dev.dv_xname, str);
                        (void) ae_init(ifp);
                        break;
                }

                /*
                 * Not handled:
                 *
                 *      Transmit buffer unavailable -- normal
                 *      condition, nothing to do, really.
                 *
                 *      General purpose timer experied -- we don't
                 *      use the general purpose timer.
                 *
                 *      Early receive interrupt -- not available on
                 *      all chips, we just use RI.  We also only
                 *      use single-segment receive DMA, so this
                 *      is mostly useless.
                 */
        }

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

#if NRND > 0
        if (handled)
                rnd_add_uint32(&sc->sc_rnd_source, status);
#endif
        return (handled);
}

/*
 * ae_rxintr:
 *
 *      Helper; handle receive interrupts.
 */
static void
ae_rxintr(struct ae_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct ether_header *eh;
        struct ae_rxsoft *rxs;
        struct mbuf *m;
        u_int32_t rxstat;
        int i, len;

        for (i = sc->sc_rxptr;; i = AE_NEXTRX(i)) {
                rxs = &sc->sc_rxsoft[i];

                AE_CDRXSYNC(sc, i,
                    BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE);

                rxstat = sc->sc_rxdescs[i].ad_status;

                if (rxstat & ADSTAT_OWN) {
                        /*
                         * We have processed all of the receive buffers.
                         */
                        break;
                }

                /*
                 * If any collisions were seen on the wire, count one.
                 */
                if (rxstat & ADSTAT_Rx_CS)
                        ifp->if_collisions++;

                /*
                 * If an error occurred, update stats, clear the status
                 * word, and leave the packet buffer in place.  It will
                 * simply be reused the next time the ring comes around.
                 * If 802.1Q VLAN MTU is enabled, ignore the Frame Too Long
                 * error.
                 */
                if (rxstat & ADSTAT_ES &&
                    ((sc->sc_ethercom.ec_capenable & ETHERCAP_VLAN_MTU) == 0 ||
                     (rxstat & (ADSTAT_Rx_DE | ADSTAT_Rx_RF |
                                ADSTAT_Rx_DB | ADSTAT_Rx_CE)) != 0)) {
#define PRINTERR(bit, str)                                              \
                        if (rxstat & (bit))                             \
                                printf("%s: receive error: %s\n",       \
                                    sc->sc_dev.dv_xname, str)
                        ifp->if_ierrors++;
                        PRINTERR(ADSTAT_Rx_DE, "descriptor error");
                        PRINTERR(ADSTAT_Rx_RF, "runt frame");
                        PRINTERR(ADSTAT_Rx_TL, "frame too long");
                        PRINTERR(ADSTAT_Rx_RE, "MII error");
                        PRINTERR(ADSTAT_Rx_DB, "dribbling bit");
                        PRINTERR(ADSTAT_Rx_CE, "CRC error");
#undef PRINTERR
                        AE_INIT_RXDESC(sc, i);
                        continue;
                }

                bus_dmamap_sync(sc->sc_dmat, rxs->rxs_dmamap, 0,
                    rxs->rxs_dmamap->dm_mapsize, BUS_DMASYNC_POSTREAD);

                /*
                 * No errors; receive the packet.  Note the chip
                 * includes the CRC with every packet.
                 */
                len = ADSTAT_Rx_LENGTH(rxstat) - ETHER_CRC_LEN;

                /*
                 * XXX: the Atheros part can align on half words.  what
                 * is the performance implication of this?  Probably
                 * minimal, and we should use it...
                 */
#ifdef __NO_STRICT_ALIGNMENT
                /*
                 * Allocate a new mbuf cluster.  If that fails, we are
                 * out of memory, and must drop the packet and recycle
                 * the buffer that's already attached to this descriptor.
                 */
                m = rxs->rxs_mbuf;
                if (ae_add_rxbuf(sc, i) != 0) {
                        ifp->if_ierrors++;
                        AE_INIT_RXDESC(sc, i);
                        bus_dmamap_sync(sc->sc_dmat, rxs->rxs_dmamap, 0,
                            rxs->rxs_dmamap->dm_mapsize, BUS_DMASYNC_PREREAD);
                        continue;
                }
#else
                /*
                 * The chip's receive buffers must be 4-byte aligned.
                 * But this means that the data after the Ethernet header
                 * is misaligned.  We must allocate a new buffer and
                 * copy the data, shifted forward 2 bytes.
                 */
                MGETHDR(m, M_DONTWAIT, MT_DATA);
                if (m == NULL) {
 dropit:
                        ifp->if_ierrors++;
                        AE_INIT_RXDESC(sc, i);
                        bus_dmamap_sync(sc->sc_dmat, rxs->rxs_dmamap, 0,
                            rxs->rxs_dmamap->dm_mapsize, BUS_DMASYNC_PREREAD);
                        continue;
                }
                MCLAIM(m, &sc->sc_ethercom.ec_rx_mowner);
                if (len > (MHLEN - 2)) {
                        MCLGET(m, M_DONTWAIT);
                        if ((m->m_flags & M_EXT) == 0) {
                                m_freem(m);
                                goto dropit;
                        }
                }
                m->m_data += 2;

                /*
                 * Note that we use clusters for incoming frames, so the
                 * buffer is virtually contiguous.
                 */
                memcpy(mtod(m, void *), mtod(rxs->rxs_mbuf, void *), len);

                /* Allow the receive descriptor to continue using its mbuf. */
                AE_INIT_RXDESC(sc, i);
                bus_dmamap_sync(sc->sc_dmat, rxs->rxs_dmamap, 0,
                    rxs->rxs_dmamap->dm_mapsize, BUS_DMASYNC_PREREAD);
#endif /* __NO_STRICT_ALIGNMENT */

                ifp->if_ipackets++;
                eh = mtod(m, struct ether_header *);
                m->m_pkthdr.rcvif = ifp;
                m->m_pkthdr.len = m->m_len = len;

#if NBPFILTER > 0
                /*
                 * Pass this up to any BPF listeners, but only
                 * pass it up the stack if its for us.
                 */
                if (ifp->if_bpf)
                        bpf_mtap(ifp->if_bpf, m);
#endif /* NBPFILTER > 0 */

                /* Pass it on. */
                (*ifp->if_input)(ifp, m);
        }

        /* Update the receive pointer. */
        sc->sc_rxptr = i;
}

/*
 * ae_txintr:
 *
 *      Helper; handle transmit interrupts.
 */
static void
ae_txintr(struct ae_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct ae_txsoft *txs;
        u_int32_t txstat;

        DPRINTF(sc, ("%s: ae_txintr: sc_flags 0x%08x\n",
            sc->sc_dev.dv_xname, sc->sc_flags));

        ifp->if_flags &= ~IFF_OACTIVE;

        /*
         * Go through our Tx list and free mbufs for those
         * frames that have been transmitted.
         */
        while ((txs = SIMPLEQ_FIRST(&sc->sc_txdirtyq)) != NULL) {
                AE_CDTXSYNC(sc, txs->txs_lastdesc,
                    txs->txs_ndescs,
                    BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE);

#ifdef AE_DEBUG
                if (ifp->if_flags & IFF_DEBUG) {
                        int i;
                        printf("    txsoft %p transmit chain:\n", txs);
                        for (i = txs->txs_firstdesc;; i = AE_NEXTTX(i)) {
                                printf("     descriptor %d:\n", i);
                                printf("       ad_status:   0x%08x\n",
                                    sc->sc_txdescs[i].ad_status);
                                printf("       ad_ctl:      0x%08x\n",
                                    sc->sc_txdescs[i].ad_ctl);
                                printf("       ad_bufaddr1: 0x%08x\n",
                                    sc->sc_txdescs[i].ad_bufaddr1);
                                printf("       ad_bufaddr2: 0x%08x\n",
                                    sc->sc_txdescs[i].ad_bufaddr2);
                                if (i == txs->txs_lastdesc)
                                        break;
                        }
                }
#endif

                txstat = sc->sc_txdescs[txs->txs_lastdesc].ad_status;
                if (txstat & ADSTAT_OWN)
                        break;

                SIMPLEQ_REMOVE_HEAD(&sc->sc_txdirtyq, txs_q);

                sc->sc_txfree += txs->txs_ndescs;

                bus_dmamap_sync(sc->sc_dmat, txs->txs_dmamap,
                    0, txs->txs_dmamap->dm_mapsize,
                    BUS_DMASYNC_POSTWRITE);
                bus_dmamap_unload(sc->sc_dmat, txs->txs_dmamap);
                m_freem(txs->txs_mbuf);
                txs->txs_mbuf = NULL;

                SIMPLEQ_INSERT_TAIL(&sc->sc_txfreeq, txs, txs_q);

                /*
                 * Check for errors and collisions.
                 */
#ifdef AE_STATS
                if (txstat & ADSTAT_Tx_UF)
                        sc->sc_stats.ts_tx_uf++;
                if (txstat & ADSTAT_Tx_TO)
                        sc->sc_stats.ts_tx_to++;
                if (txstat & ADSTAT_Tx_EC)
                        sc->sc_stats.ts_tx_ec++;
                if (txstat & ADSTAT_Tx_LC)
                        sc->sc_stats.ts_tx_lc++;
#endif

                if (txstat & (ADSTAT_Tx_UF|ADSTAT_Tx_TO))
                        ifp->if_oerrors++;

                if (txstat & ADSTAT_Tx_EC)
                        ifp->if_collisions += 16;
                else
                        ifp->if_collisions += ADSTAT_Tx_COLLISIONS(txstat);
                if (txstat & ADSTAT_Tx_LC)
                        ifp->if_collisions++;

                ifp->if_opackets++;
        }

        /*
         * If there are no more pending transmissions, cancel the watchdog
         * timer.
         */
        if (txs == NULL)
                ifp->if_timer = 0;
}

#ifdef AE_STATS
void
ae_print_stats(struct ae_softc *sc)
{

        printf("%s: tx_uf %lu, tx_to %lu, tx_ec %lu, tx_lc %lu\n",
            sc->sc_dev.dv_xname,
            sc->sc_stats.ts_tx_uf, sc->sc_stats.ts_tx_to,
            sc->sc_stats.ts_tx_ec, sc->sc_stats.ts_tx_lc);
}
#endif

/*
 * ae_reset:
 *
 *      Perform a soft reset on the chip.
 */
void
ae_reset(struct ae_softc *sc)
{
        int i;

        AE_WRITE(sc, CSR_BUSMODE, BUSMODE_SWR);
        AE_BARRIER(sc);

        /*
         * The chip doesn't take itself out of reset automatically.
         * We need to do so after 2us.
         */
        delay(10);
        AE_WRITE(sc, CSR_BUSMODE, 0);
        AE_BARRIER(sc);

        for (i = 0; i < 1000; i++) {
                /*
                 * Wait a bit for the reset to complete before peeking
                 * at the chip again.
                 */
                delay(10);
                if (AE_ISSET(sc, CSR_BUSMODE, BUSMODE_SWR) == 0)
                        break;
        }

        if (AE_ISSET(sc, CSR_BUSMODE, BUSMODE_SWR))
                printf("%s: reset failed to complete\n", sc->sc_dev.dv_xname);

        delay(1000);
}

/*
 * ae_init:             [ ifnet interface function ]
 *
 *      Initialize the interface.  Must be called at splnet().
 */
static int
ae_init(struct ifnet *ifp)
{
        struct ae_softc *sc = ifp->if_softc;
        struct ae_txsoft *txs;
        struct ae_rxsoft *rxs;
        const uint8_t *enaddr;
        int i, error = 0;

        if ((error = ae_enable(sc)) != 0)
                goto out;

        /*
         * Cancel any pending I/O.
         */
        ae_stop(ifp, 0);

        /*
         * Reset the chip to a known state.
         */
        ae_reset(sc);

        /*
         * Initialize the BUSMODE register.
         */
        AE_WRITE(sc, CSR_BUSMODE,
            /* XXX: not sure if this is a good thing or not... */
            //BUSMODE_ALIGN_16B |
            BUSMODE_BAR | BUSMODE_BLE | BUSMODE_PBL_4LW);
        AE_BARRIER(sc);

        /*
         * Initialize the transmit descriptor ring.
         */
        memset(sc->sc_txdescs, 0, sizeof(sc->sc_txdescs));
        for (i = 0; i < AE_NTXDESC; i++) {
                sc->sc_txdescs[i].ad_ctl = 0;
                sc->sc_txdescs[i].ad_bufaddr2 =
                    AE_CDTXADDR(sc, AE_NEXTTX(i));
        }
        sc->sc_txdescs[AE_NTXDESC - 1].ad_ctl |= ADCTL_ER;
        AE_CDTXSYNC(sc, 0, AE_NTXDESC,
            BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
        sc->sc_txfree = AE_NTXDESC;
        sc->sc_txnext = 0;

        /*
         * Initialize the transmit job descriptors.
         */
        SIMPLEQ_INIT(&sc->sc_txfreeq);
        SIMPLEQ_INIT(&sc->sc_txdirtyq);
        for (i = 0; i < AE_TXQUEUELEN; i++) {
                txs = &sc->sc_txsoft[i];
                txs->txs_mbuf = NULL;
                SIMPLEQ_INSERT_TAIL(&sc->sc_txfreeq, txs, txs_q);
        }

        /*
         * Initialize the receive descriptor and receive job
         * descriptor rings.
         */
        for (i = 0; i < AE_NRXDESC; i++) {
                rxs = &sc->sc_rxsoft[i];
                if (rxs->rxs_mbuf == NULL) {
                        if ((error = ae_add_rxbuf(sc, i)) != 0) {
                                printf("%s: unable to allocate or map rx "
                                    "buffer %d, error = %d\n",
                                    sc->sc_dev.dv_xname, i, error);
                                /*
                                 * XXX Should attempt to run with fewer receive
                                 * XXX buffers instead of just failing.
                                 */
                                ae_rxdrain(sc);
                                goto out;
                        }
                } else
                        AE_INIT_RXDESC(sc, i);
        }
        sc->sc_rxptr = 0;

        /*
         * Initialize the interrupt mask and enable interrupts.
         */
        /* normal interrupts */
        sc->sc_inten =  STATUS_TI | STATUS_TU | STATUS_RI | STATUS_NIS;

        /* abnormal interrupts */
        sc->sc_inten |= STATUS_TPS | STATUS_TJT | STATUS_UNF |
            STATUS_RU | STATUS_RPS | STATUS_SE | STATUS_AIS;

        sc->sc_rxint_mask = STATUS_RI|STATUS_RU;
        sc->sc_txint_mask = STATUS_TI|STATUS_UNF|STATUS_TJT;

        sc->sc_rxint_mask &= sc->sc_inten;
        sc->sc_txint_mask &= sc->sc_inten;

        AE_WRITE(sc, CSR_INTEN, sc->sc_inten);
        AE_WRITE(sc, CSR_STATUS, 0xffffffff);

        /*
         * Give the transmit and receive rings to the chip.
         */
        AE_WRITE(sc, CSR_TXLIST, AE_CDTXADDR(sc, sc->sc_txnext));
        AE_WRITE(sc, CSR_RXLIST, AE_CDRXADDR(sc, sc->sc_rxptr));
        AE_BARRIER(sc);

        /*
         * Set the station address.
         */
        enaddr = CLLADDR(ifp->if_sadl);
        AE_WRITE(sc, CSR_MACHI, enaddr[5] << 16 | enaddr[4]);
        AE_WRITE(sc, CSR_MACLO, enaddr[3] << 24 | enaddr[2] << 16 |
                enaddr[1] << 8 | enaddr[0]);
        AE_BARRIER(sc);

        /*
         * Set the receive filter.  This will start the transmit and
         * receive processes.
         */
        ae_filter_setup(sc);

        /*
         * Set the current media.
         */
        if ((error = ether_mediachange(ifp)) != 0)
                goto out;

        /*
         * Start the mac.
         */
        AE_SET(sc, CSR_MACCTL, MACCTL_RE | MACCTL_TE);
        AE_BARRIER(sc);

        /*
         * Write out the opmode.
         */
        AE_WRITE(sc, CSR_OPMODE, OPMODE_SR | OPMODE_ST |
            ae_txthresh[sc->sc_txthresh].txth_opmode);
        /*
         * Start the receive process.
         */
        AE_WRITE(sc, CSR_RXPOLL, RXPOLL_RPD);
        AE_BARRIER(sc);

        if (sc->sc_tick != NULL) {
                /* Start the one second clock. */
                callout_reset(&sc->sc_tick_callout, hz >> 3, sc->sc_tick, sc);
        }

        /*
         * Note that the interface is now running.
         */
        ifp->if_flags |= IFF_RUNNING;
        ifp->if_flags &= ~IFF_OACTIVE;
        sc->sc_if_flags = ifp->if_flags;

 out:
        if (error) {
                ifp->if_flags &= ~(IFF_RUNNING | IFF_OACTIVE);
                ifp->if_timer = 0;
                printf("%s: interface not running\n", sc->sc_dev.dv_xname);
        }
        return (error);
}

/*
 * ae_enable:
 *
 *      Enable the chip.
 */
static int
ae_enable(struct ae_softc *sc)
{

        if (AE_IS_ENABLED(sc) == 0) {
                sc->sc_ih = arbus_intr_establish(sc->sc_cirq, sc->sc_mirq,
                    ae_intr, sc);
                if (sc->sc_ih == NULL) {
                        printf("%s: unable to establish interrupt\n",
                            sc->sc_dev.dv_xname);
                        return (EIO);
                }
                sc->sc_flags |= AE_ENABLED;
        }
        return (0);
}

/*
 * ae_disable:
 *
 *      Disable the chip.
 */
static void
ae_disable(struct ae_softc *sc)
{

        if (AE_IS_ENABLED(sc)) {
                arbus_intr_disestablish(sc->sc_ih);
                sc->sc_flags &= ~AE_ENABLED;
        }
}

/*
 * ae_power:
 *
 *      Power management (suspend/resume) hook.
 */
static void
ae_power(int why, void *arg)
{
        struct ae_softc *sc = arg;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        int s;

        printf("power called: %d, %x\n", why, (uint32_t)arg);
        s = splnet();
        switch (why) {
        case PWR_STANDBY:
                /* do nothing! */
                break;
        case PWR_SUSPEND:
                ae_stop(ifp, 0);
                ae_disable(sc);
                break;
        case PWR_RESUME:
                if (ifp->if_flags & IFF_UP) {
                        ae_enable(sc);
                        ae_init(ifp);
                }
                break;
        case PWR_SOFTSUSPEND:
        case PWR_SOFTSTANDBY:
        case PWR_SOFTRESUME:
                break;
        }
        splx(s);
}

/*
 * ae_rxdrain:
 *
 *      Drain the receive queue.
 */
static void
ae_rxdrain(struct ae_softc *sc)
{
        struct ae_rxsoft *rxs;
        int i;

        for (i = 0; i < AE_NRXDESC; i++) {
                rxs = &sc->sc_rxsoft[i];
                if (rxs->rxs_mbuf != NULL) {
                        bus_dmamap_unload(sc->sc_dmat, rxs->rxs_dmamap);
                        m_freem(rxs->rxs_mbuf);
                        rxs->rxs_mbuf = NULL;
                }
        }
}

/*
 * ae_stop:             [ ifnet interface function ]
 *
 *      Stop transmission on the interface.
 */
static void
ae_stop(struct ifnet *ifp, int disable)
{
        struct ae_softc *sc = ifp->if_softc;
        struct ae_txsoft *txs;

        if (sc->sc_tick != NULL) {
                /* Stop the one second clock. */
                callout_stop(&sc->sc_tick_callout);
        }

        /* Down the MII. */
        mii_down(&sc->sc_mii);

        /* Disable interrupts. */
        AE_WRITE(sc, CSR_INTEN, 0);

        /* Stop the transmit and receive processes. */
        AE_WRITE(sc, CSR_OPMODE, 0);
        AE_WRITE(sc, CSR_RXLIST, 0);
        AE_WRITE(sc, CSR_TXLIST, 0);
        AE_CLR(sc, CSR_MACCTL, MACCTL_TE | MACCTL_RE);
        AE_BARRIER(sc);

        /*
         * Release any queued transmit buffers.
         */
        while ((txs = SIMPLEQ_FIRST(&sc->sc_txdirtyq)) != NULL) {
                SIMPLEQ_REMOVE_HEAD(&sc->sc_txdirtyq, txs_q);
                if (txs->txs_mbuf != NULL) {
                        bus_dmamap_unload(sc->sc_dmat, txs->txs_dmamap);
                        m_freem(txs->txs_mbuf);
                        txs->txs_mbuf = NULL;
                }
                SIMPLEQ_INSERT_TAIL(&sc->sc_txfreeq, txs, txs_q);
        }

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

        if (disable) {
                ae_rxdrain(sc);
                ae_disable(sc);
        }

        /*
         * Reset the chip (needed on some flavors to actually disable it).
         */
        ae_reset(sc);
}

/*
 * ae_add_rxbuf:
 *
 *      Add a receive buffer to the indicated descriptor.
 */
static int
ae_add_rxbuf(struct ae_softc *sc, int idx)
{
        struct ae_rxsoft *rxs = &sc->sc_rxsoft[idx];
        struct mbuf *m;
        int error;

        MGETHDR(m, M_DONTWAIT, MT_DATA);
        if (m == NULL)
                return (ENOBUFS);

        MCLAIM(m, &sc->sc_ethercom.ec_rx_mowner);
        MCLGET(m, M_DONTWAIT);
        if ((m->m_flags & M_EXT) == 0) {
                m_freem(m);
                return (ENOBUFS);
        }

        if (rxs->rxs_mbuf != NULL)
                bus_dmamap_unload(sc->sc_dmat, rxs->rxs_dmamap);

        rxs->rxs_mbuf = m;

        error = bus_dmamap_load(sc->sc_dmat, rxs->rxs_dmamap,
            m->m_ext.ext_buf, m->m_ext.ext_size, NULL,
            BUS_DMA_READ|BUS_DMA_NOWAIT);
        if (error) {
                printf("%s: can't load rx DMA map %d, error = %d\n",
                    sc->sc_dev.dv_xname, idx, error);
                panic("ae_add_rxbuf");  /* XXX */
        }

        bus_dmamap_sync(sc->sc_dmat, rxs->rxs_dmamap, 0,
            rxs->rxs_dmamap->dm_mapsize, BUS_DMASYNC_PREREAD);

        AE_INIT_RXDESC(sc, idx);

        return (0);
}

/*
 * ae_filter_setup:
 *
 *      Set the chip's receive filter.
 */
static void
ae_filter_setup(struct ae_softc *sc)
{
        struct ethercom *ec = &sc->sc_ethercom;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct ether_multi *enm;
        struct ether_multistep step;
        uint32_t hash, mchash[2];
        uint32_t macctl = 0;

        /*
         * If the chip is running, we need to reset the interface,
         * and will revisit here (with IFF_RUNNING) clear.  The
         * chip seems to really not like to have its multicast
         * filter programmed without a reset.
         */
        if (ifp->if_flags & IFF_RUNNING) {
                (void) ae_init(ifp);
                return;
        }

        DPRINTF(sc, ("%s: ae_filter_setup: sc_flags 0x%08x\n",
            sc->sc_dev.dv_xname, sc->sc_flags));

        macctl = AE_READ(sc, CSR_MACCTL);
        macctl &= ~(MACCTL_PR | MACCTL_PM);
        macctl |= MACCTL_HASH;
        macctl |= MACCTL_HBD;
        macctl |= MACCTL_PR;

        if (ifp->if_flags & IFF_PROMISC) {
                macctl |= MACCTL_PR;
                goto allmulti;
        }

        mchash[0] = mchash[1] = 0;

        ETHER_FIRST_MULTI(step, ec, enm);
        while (enm != NULL) {
                if (memcmp(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;
                }

                /* Verify whether we use big or little endian hashes */
                hash = ether_crc32_be(enm->enm_addrlo, ETHER_ADDR_LEN) & 0x3f;
                mchash[hash >> 5] |= 1 << (hash & 0x1f);
                ETHER_NEXT_MULTI(step, enm);
        }
        ifp->if_flags &= ~IFF_ALLMULTI;
        goto setit;

 allmulti:
        ifp->if_flags |= IFF_ALLMULTI;
        mchash[0] = mchash[1] = 0xffffffff;
        macctl |= MACCTL_PM;

 setit:
        AE_WRITE(sc, CSR_HTHI, mchash[0]);
        AE_WRITE(sc, CSR_HTHI, mchash[1]);

        AE_WRITE(sc, CSR_MACCTL, macctl);
        AE_BARRIER(sc);

        DPRINTF(sc, ("%s: ae_filter_setup: returning %x\n",
                    sc->sc_dev.dv_xname, macctl));
}

/*
 * ae_idle:
 *
 *      Cause the transmit and/or receive processes to go idle.
 */
void
ae_idle(struct ae_softc *sc, u_int32_t bits)
{
        static const char * const txstate_names[] = {
                "STOPPED",
                "RUNNING - FETCH",
                "RUNNING - WAIT",
                "RUNNING - READING",
                "-- RESERVED --",
                "RUNNING - SETUP",
                "SUSPENDED",
                "RUNNING - CLOSE",
        };
        static const char * const rxstate_names[] = {
                "STOPPED",
                "RUNNING - FETCH",
                "RUNNING - CHECK",
                "RUNNING - WAIT",
                "SUSPENDED",
                "RUNNING - CLOSE",
                "RUNNING - FLUSH",
                "RUNNING - QUEUE",
        };

        u_int32_t csr, ackmask = 0;
        int i;

        if (bits & OPMODE_ST)
                ackmask |= STATUS_TPS;

        if (bits & OPMODE_SR)
                ackmask |= STATUS_RPS;

        AE_CLR(sc, CSR_OPMODE, bits);

        for (i = 0; i < 1000; i++) {
                if (AE_ISSET(sc, CSR_STATUS, ackmask) == ackmask)
                        break;
                delay(10);
        }

        csr = AE_READ(sc, CSR_STATUS);
        if ((csr & ackmask) != ackmask) {
                if ((bits & OPMODE_ST) != 0 && (csr & STATUS_TPS) == 0 &&
                    (csr & STATUS_TS) != STATUS_TS_STOPPED) {
                        printf("%s: transmit process failed to idle: "
                            "state %s\n", sc->sc_dev.dv_xname,
                            txstate_names[(csr & STATUS_TS) >> 20]);
                }
                if ((bits & OPMODE_SR) != 0 && (csr & STATUS_RPS) == 0 &&
                    (csr & STATUS_RS) != STATUS_RS_STOPPED) {
                        printf("%s: receive process failed to idle: "
                            "state %s\n", sc->sc_dev.dv_xname,
                            rxstate_names[(csr & STATUS_RS) >> 17]);
                }
        }
}

/*****************************************************************************
 * Support functions for MII-attached media.
 *****************************************************************************/

/*
 * ae_mii_tick:
 *
 *      One second timer, used to tick the MII.
 */
static void
ae_mii_tick(void *arg)
{
        struct ae_softc *sc = arg;
        int s;

        if (!device_is_active(&sc->sc_dev))
                return;

        s = splnet();
        mii_tick(&sc->sc_mii);
        splx(s);

        callout_reset(&sc->sc_tick_callout, hz, sc->sc_tick, sc);
}

/*
 * ae_mii_statchg:      [mii interface function]
 *
 *      Callback from PHY when media changes.
 */
static void
ae_mii_statchg(device_t self)
{
        struct ae_softc *sc = device_private(self);
        uint32_t        macctl, flowc;

        //opmode = AE_READ(sc, CSR_OPMODE);
        macctl = AE_READ(sc, CSR_MACCTL);

        /* XXX: do we need to do this? */
        /* Idle the transmit and receive processes. */
        //ae_idle(sc, OPMODE_ST|OPMODE_SR);

        if (sc->sc_mii.mii_media_active & IFM_FDX) {
                flowc = FLOWC_FCE;
                macctl &= ~MACCTL_DRO;
                macctl |= MACCTL_FDX;
        } else {
                flowc = 0;      /* cannot do flow control in HDX */
                macctl |= MACCTL_DRO;
                macctl &= ~MACCTL_FDX;
        }

        AE_WRITE(sc, CSR_FLOWC, flowc);
        AE_WRITE(sc, CSR_MACCTL, macctl);

        /* restore operational mode */
        //AE_WRITE(sc, CSR_OPMODE, opmode);
        AE_BARRIER(sc);
}

/*
 * ae_mii_readreg:
 *
 *      Read a PHY register.
 */
static int
ae_mii_readreg(device_t self, int phy, int reg)
{
        struct ae_softc *sc = device_private(self);
        uint32_t        addr;
        int             i;

        addr = (phy << MIIADDR_PHY_SHIFT) | (reg << MIIADDR_REG_SHIFT);
        AE_WRITE(sc, CSR_MIIADDR, addr);
        AE_BARRIER(sc);
        for (i = 0; i < 100000000; i++) {
                if ((AE_READ(sc, CSR_MIIADDR) & MIIADDR_BUSY) == 0)
                        break;
        }

        return (AE_READ(sc, CSR_MIIDATA) & 0xffff);
}

/*
 * ae_mii_writereg:
 *
 *      Write a PHY register.
 */
static void
ae_mii_writereg(device_t self, int phy, int reg, int val)
{
        struct ae_softc *sc = device_private(self);
        uint32_t        addr;
        int             i;

        /* write the data register */
        AE_WRITE(sc, CSR_MIIDATA, val);

        /* write the address to latch it in */
        addr = (phy << MIIADDR_PHY_SHIFT) | (reg << MIIADDR_REG_SHIFT) |
            MIIADDR_WRITE;
        AE_WRITE(sc, CSR_MIIADDR, addr);
        AE_BARRIER(sc);

        for (i = 0; i < 100000000; i++) {
                if ((AE_READ(sc, CSR_MIIADDR) & MIIADDR_BUSY) == 0)
                        break;
        }
}