/*      $NetBSD: if_ste.c,v 1.66 2024/06/29 12:11:12 riastradh Exp $    */

/*-
 * Copyright (c) 2001 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe.
 *
 * 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 Sundance Tech. ST-201 10/100
 * Ethernet controller.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_ste.c,v 1.66 2024/06/29 12:11:12 riastradh Exp $");


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/device.h>
#include <sys/queue.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_media.h>
#include <net/if_ether.h>

#include <net/bpf.h>

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

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

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

#include <dev/pci/if_stereg.h>

/*
 * Transmit descriptor list size.
 */
#define STE_NTXDESC             256
#define STE_NTXDESC_MASK        (STE_NTXDESC - 1)
#define STE_NEXTTX(x)           (((x) + 1) & STE_NTXDESC_MASK)

/*
 * Receive descriptor list size.
 */
#define STE_NRXDESC             128
#define STE_NRXDESC_MASK        (STE_NRXDESC - 1)
#define STE_NEXTRX(x)           (((x) + 1) & STE_NRXDESC_MASK)

/*
 * Control structures are DMA'd to the ST-201 chip.  We allocate them in
 * a single clump that maps to a single DMA segment to make several things
 * easier.
 */
struct ste_control_data {
        /*
         * The transmit descriptors.
         */
        struct ste_tfd scd_txdescs[STE_NTXDESC];

        /*
         * The receive descriptors.
         */
        struct ste_rfd scd_rxdescs[STE_NRXDESC];
};

#define STE_CDOFF(x)    offsetof(struct ste_control_data, x)
#define STE_CDTXOFF(x)  STE_CDOFF(scd_txdescs[(x)])
#define STE_CDRXOFF(x)  STE_CDOFF(scd_rxdescs[(x)])

/*
 * Software state for transmit and receive jobs.
 */
struct ste_descsoft {
        struct mbuf *ds_mbuf;           /* head of our mbuf chain */
        bus_dmamap_t ds_dmamap;         /* our DMA map */
};

/*
 * Software state per device.
 */
struct ste_softc {
        device_t sc_dev;                /* generic device information */
        bus_space_tag_t sc_st;          /* bus space tag */
        bus_space_handle_t sc_sh;       /* bus space handle */
        bus_dma_tag_t sc_dmat;          /* bus DMA tag */
        struct ethercom sc_ethercom;    /* ethernet common data */

        void *sc_ih;                    /* interrupt cookie */

        struct mii_data sc_mii;         /* MII/media information */

        callout_t sc_tick_ch;           /* tick callout */

        bus_dmamap_t sc_cddmamap;       /* control data DMA map */
#define sc_cddma        sc_cddmamap->dm_segs[0].ds_addr

        /*
         * Software state for transmit and receive descriptors.
         */
        struct ste_descsoft sc_txsoft[STE_NTXDESC];
        struct ste_descsoft sc_rxsoft[STE_NRXDESC];

        /*
         * Control data structures.
         */
        struct ste_control_data *sc_control_data;
#define sc_txdescs      sc_control_data->scd_txdescs
#define sc_rxdescs      sc_control_data->scd_rxdescs

        int     sc_txpending;           /* number of Tx requests pending */
        int     sc_txdirty;             /* first dirty Tx descriptor */
        int     sc_txlast;              /* last used Tx descriptor */

        int     sc_rxptr;               /* next ready Rx descriptor/descsoft */

        int     sc_txthresh;            /* Tx threshold */
        uint32_t sc_DMACtrl;            /* prototype DMACtrl register */
        uint16_t sc_IntEnable;          /* prototype IntEnable register */
        uint16_t sc_MacCtrl0;           /* prototype MacCtrl0 register */
        uint8_t sc_ReceiveMode;         /* prototype ReceiveMode register */

        bool    sc_enable_phy0;         /* access to phy #0 allowed */
};

#define STE_CDTXADDR(sc, x)     ((sc)->sc_cddma + STE_CDTXOFF((x)))
#define STE_CDRXADDR(sc, x)     ((sc)->sc_cddma + STE_CDRXOFF((x)))

#define STE_CDTXSYNC(sc, x, ops)                                        \
        bus_dmamap_sync((sc)->sc_dmat, (sc)->sc_cddmamap,               \
            STE_CDTXOFF((x)), sizeof(struct ste_tfd), (ops))

#define STE_CDRXSYNC(sc, x, ops)                                        \
        bus_dmamap_sync((sc)->sc_dmat, (sc)->sc_cddmamap,               \
            STE_CDRXOFF((x)), sizeof(struct ste_rfd), (ops))

#define STE_INIT_RXDESC(sc, x)                                          \
do {                                                                    \
        struct ste_descsoft *__ds = &(sc)->sc_rxsoft[(x)];              \
        struct ste_rfd *__rfd = &(sc)->sc_rxdescs[(x)];                 \
        struct mbuf *__m = __ds->ds_mbuf;                               \
                                                                        \
        /*                                                              \
         * Note: We scoot the packet forward 2 bytes in the buffer      \
         * so that the payload after the Ethernet header is aligned     \
         * to a 4-byte boundary.                                        \
         */                                                             \
        __m->m_data = __m->m_ext.ext_buf + 2;                           \
        __rfd->rfd_frag.frag_addr =                                     \
            htole32(__ds->ds_dmamap->dm_segs[0].ds_addr + 2);           \
        __rfd->rfd_frag.frag_len = htole32((MCLBYTES - 2) | FRAG_LAST); \
        __rfd->rfd_next = htole32(STE_CDRXADDR((sc), STE_NEXTRX((x)))); \
        __rfd->rfd_status = 0;                                          \
        STE_CDRXSYNC((sc), (x), BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE); \
} while (/*CONSTCOND*/0)

#define STE_TIMEOUT 1000

static void     ste_start(struct ifnet *);
static void     ste_watchdog(struct ifnet *);
static int      ste_ioctl(struct ifnet *, u_long, void *);
static int      ste_init(struct ifnet *);
static void     ste_stop(struct ifnet *, int);

static bool     ste_shutdown(device_t, int);

static void     ste_reset(struct ste_softc *, uint32_t);
static void     ste_setthresh(struct ste_softc *);
static void     ste_txrestart(struct ste_softc *, uint8_t);
static void     ste_rxdrain(struct ste_softc *);
static int      ste_add_rxbuf(struct ste_softc *, int);
static void     ste_read_eeprom(struct ste_softc *, int, uint16_t *);
static void     ste_tick(void *);

static void     ste_stats_update(struct ste_softc *);

static void     ste_set_filter(struct ste_softc *);

static int      ste_intr(void *);
static void     ste_txintr(struct ste_softc *);
static void     ste_rxintr(struct ste_softc *);

static int      ste_mii_readreg(device_t, int, int, uint16_t *);
static int      ste_mii_writereg(device_t, int, int, uint16_t);
static void     ste_mii_statchg(struct ifnet *);

static int      ste_match(device_t, cfdata_t, void *);
static void     ste_attach(device_t, device_t, void *);

int     ste_copy_small = 0;

CFATTACH_DECL_NEW(ste, sizeof(struct ste_softc),
    ste_match, ste_attach, NULL, NULL);

static uint32_t ste_mii_bitbang_read(device_t);
static void     ste_mii_bitbang_write(device_t, uint32_t);

static const struct mii_bitbang_ops ste_mii_bitbang_ops = {
        ste_mii_bitbang_read,
        ste_mii_bitbang_write,
        {
                PC_MgmtData,            /* MII_BIT_MDO */
                PC_MgmtData,            /* MII_BIT_MDI */
                PC_MgmtClk,             /* MII_BIT_MDC */
                PC_MgmtDir,             /* MII_BIT_DIR_HOST_PHY */
                0,                      /* MII_BIT_DIR_PHY_HOST */
        }
};

/*
 * Devices supported by this driver.
 */
struct ste_product {
        pci_vendor_id_t         ste_vendor;
        pci_product_id_t        ste_product;
        const char              *ste_name;
        const struct ste_product *ste_subs;
};

static const struct ste_product ste_dlink_products[] = {
        { PCI_VENDOR_DLINK,             0x1002,
          "D-Link DFE-550TX 10/100 Ethernet",
          NULL },

        { PCI_VENDOR_DLINK,             0x1003,
          "D-Link DFE-550FX Ethernet",
          NULL },

        { PCI_VENDOR_DLINK,             0x1012,
          "D-Link DFE-580TX 4-port 10/100 Ethernet",
          NULL },

        { PCI_VENDOR_DLINK,             0x1040,
          "D-Link DFE-530TXS 10/100 Ethernet",
          NULL },

        { 0,                            0,
          NULL,
          NULL },
};

static const struct ste_product ste_products[] = {
        { PCI_VENDOR_SUNDANCETI,        PCI_PRODUCT_SUNDANCETI_IP100A,
          "IC Plus Corp. IP00A 10/100 Fast Ethernet Adapter",
          NULL },

        { PCI_VENDOR_SUNDANCETI,        PCI_PRODUCT_SUNDANCETI_ST201,
          "Sundance ST-201 10/100 Ethernet",
          NULL },

        { PCI_VENDOR_DLINK,             PCI_PRODUCT_DLINK_DL1002,
          "D-Link DL-1002 10/100 Ethernet",
          ste_dlink_products },

        { 0,                            0,
          NULL,
          NULL },
};

static const struct ste_product *
ste_lookup_table(pcireg_t pci_id, const struct ste_product * const products)
{
        const struct ste_product *sp;

        for (sp = products; sp->ste_name != NULL; sp++) {
                if (PCI_VENDOR(pci_id) == sp->ste_vendor &&
                    PCI_PRODUCT(pci_id) == sp->ste_product)
                        return (sp);
        }
        return (NULL);
}

static const struct ste_product *
ste_lookup(const struct pci_attach_args *pa)
{
        const struct ste_product *sp;

        sp = ste_lookup_table(pa->pa_id, ste_products);
        if (sp && sp->ste_subs) {
                const pcireg_t subsys =
                    pci_conf_read(pa->pa_pc, pa->pa_tag, PCI_SUBSYS_ID_REG);
                const struct ste_product *ssp =
                    ste_lookup_table(subsys, sp->ste_subs);
                if (ssp)
                        sp = ssp;
        }
        return (sp);
}

static int
ste_match(device_t parent, cfdata_t cf, void *aux)
{
        struct pci_attach_args *pa = aux;

        if (ste_lookup(pa) != NULL)
                return (1);

        return (0);
}

static void
ste_attach(device_t parent, device_t self, void *aux)
{
        struct ste_softc *sc = device_private(self);
        struct pci_attach_args *pa = aux;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct mii_data * const mii = &sc->sc_mii;
        pci_chipset_tag_t pc = pa->pa_pc;
        pci_intr_handle_t ih;
        const char *intrstr = NULL;
        bus_space_tag_t iot, memt;
        bus_space_handle_t ioh, memh;
        bus_dma_segment_t seg;
        int ioh_valid, memh_valid;
        int i, rseg, error;
        const struct ste_product *sp;
        uint8_t enaddr[ETHER_ADDR_LEN];
        uint16_t myea[ETHER_ADDR_LEN / 2];
        char intrbuf[PCI_INTRSTR_LEN];

        sc->sc_dev = self;

        callout_init(&sc->sc_tick_ch, 0);
        callout_setfunc(&sc->sc_tick_ch, ste_tick, sc);

        sp = ste_lookup(pa);
        if (sp == NULL) {
                printf("\n");
                panic("ste_attach: impossible");
        }

        printf(": %s\n", sp->ste_name);

        /*
         * Map the device.
         */
        ioh_valid = (pci_mapreg_map(pa, STE_PCI_IOBA,
            PCI_MAPREG_TYPE_IO, 0,
            &iot, &ioh, NULL, NULL) == 0);
        memh_valid = (pci_mapreg_map(pa, STE_PCI_MMBA,
            PCI_MAPREG_TYPE_MEM | PCI_MAPREG_MEM_TYPE_32BIT, 0,
            &memt, &memh, NULL, NULL) == 0);

        if (memh_valid) {
                sc->sc_st = memt;
                sc->sc_sh = memh;
        } else if (ioh_valid) {
                sc->sc_st = iot;
                sc->sc_sh = ioh;
        } else {
                aprint_error_dev(self, "unable to map device registers\n");
                return;
        }

        sc->sc_dmat = pa->pa_dmat;

        /* Enable bus mastering. */
        pci_conf_write(pc, pa->pa_tag, PCI_COMMAND_STATUS_REG,
            pci_conf_read(pc, pa->pa_tag, PCI_COMMAND_STATUS_REG) |
            PCI_COMMAND_MASTER_ENABLE);

        /* power up chip */
        if ((error = pci_activate(pa->pa_pc, pa->pa_tag, self,
            NULL)) && error != EOPNOTSUPP) {
                aprint_error_dev(sc->sc_dev, "cannot activate %d\n", error);
                return;
        }

        /*
         * Map and establish our interrupt.
         */
        if (pci_intr_map(pa, &ih)) {
                aprint_error_dev(sc->sc_dev, "unable to map interrupt\n");
                return;
        }
        intrstr = pci_intr_string(pc, ih, intrbuf, sizeof(intrbuf));
        sc->sc_ih = pci_intr_establish_xname(pc, ih, IPL_NET, ste_intr, sc,
            device_xname(self));
        if (sc->sc_ih == NULL) {
                aprint_error_dev(sc->sc_dev, "unable to establish interrupt");
                if (intrstr != NULL)
                        aprint_error(" at %s", intrstr);
                aprint_error("\n");
                return;
        }
        aprint_normal_dev(sc->sc_dev, "interrupting at %s\n", intrstr);

        /*
         * Allocate the control data structures, and create and load the
         * DMA map for it.
         */
        if ((error = bus_dmamem_alloc(sc->sc_dmat,
            sizeof(struct ste_control_data), PAGE_SIZE, 0, &seg, 1, &rseg,
            0)) != 0) {
                aprint_error_dev(sc->sc_dev,
                    "unable to allocate control data, error = %d\n", error);
                goto fail_0;
        }

        if ((error = bus_dmamem_map(sc->sc_dmat, &seg, rseg,
            sizeof(struct ste_control_data), (void **)&sc->sc_control_data,
            BUS_DMA_COHERENT)) != 0) {
                aprint_error_dev(sc->sc_dev,
                    "unable to map control data, error = %d\n", error);
                goto fail_1;
        }

        if ((error = bus_dmamap_create(sc->sc_dmat,
            sizeof(struct ste_control_data), 1,
            sizeof(struct ste_control_data), 0, 0, &sc->sc_cddmamap)) != 0) {
                aprint_error_dev(sc->sc_dev,
                    "unable to create control data DMA map, error = %d\n",
                    error);
                goto fail_2;
        }

        if ((error = bus_dmamap_load(sc->sc_dmat, sc->sc_cddmamap,
            sc->sc_control_data, sizeof(struct ste_control_data), NULL,
            0)) != 0) {
                aprint_error_dev(sc->sc_dev,
                    "unable to load control data DMA map, error = %d\n",
                    error);
                goto fail_3;
        }

        /*
         * Create the transmit buffer DMA maps.
         */
        for (i = 0; i < STE_NTXDESC; i++) {
                if ((error = bus_dmamap_create(sc->sc_dmat, MCLBYTES,
                    STE_NTXFRAGS, MCLBYTES, 0, 0,
                    &sc->sc_txsoft[i].ds_dmamap)) != 0) {
                        aprint_error_dev(sc->sc_dev,
                            "unable to create tx DMA map %d, error = %d\n", i,
                            error);
                        goto fail_4;
                }
        }

        /*
         * Create the receive buffer DMA maps.
         */
        for (i = 0; i < STE_NRXDESC; i++) {
                if ((error = bus_dmamap_create(sc->sc_dmat, MCLBYTES, 1,
                    MCLBYTES, 0, 0, &sc->sc_rxsoft[i].ds_dmamap)) != 0) {
                        aprint_error_dev(sc->sc_dev,
                            "unable to create rx DMA map %d, error = %d\n", i,
                            error);
                        goto fail_5;
                }
                sc->sc_rxsoft[i].ds_mbuf = NULL;
        }

        /*
         * Reset the chip to a known state.
         */
        ste_reset(sc, AC_GlobalReset | AC_RxReset | AC_TxReset | AC_DMA |
            AC_FIFO | AC_Network | AC_Host | AC_AutoInit | AC_RstOut);

        /*
         * Read the Ethernet address from the EEPROM.
         */
        for (i = 0; i < 3; i++) {
                ste_read_eeprom(sc, STE_EEPROM_StationAddress0 + i, &myea[i]);
                myea[i] = le16toh(myea[i]);
        }
        memcpy(enaddr, myea, sizeof(enaddr));

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

        /*
         * Initialize our media structures and probe the MII.
         */
        mii->mii_ifp = ifp;
        mii->mii_readreg = ste_mii_readreg;
        mii->mii_writereg = ste_mii_writereg;
        mii->mii_statchg = ste_mii_statchg;
        sc->sc_ethercom.ec_mii = mii;
        ifmedia_init(&mii->mii_media, IFM_IMASK, ether_mediachange,
            ether_mediastatus);
        mii_attach(sc->sc_dev, mii, 0xffffffff, MII_PHY_ANY,
            MII_OFFSET_ANY, 0);
        if (LIST_FIRST(&mii->mii_phys) == NULL) {
                /*
                 * It seems that some variants of this chip "ghost" the
                 * single PHY at #0 and #1.  We will try probing the MII
                 * first while ignoring #0 access.  If we find the PHY,
                 * great!  If not, un-ignore #0 and try probing *just*
                 * #0 to see if we can find it.
                 */
                sc->sc_enable_phy0 = true;
                mii_attach(sc->sc_dev, mii, 0xffffffff, 0,
                    MII_OFFSET_ANY, 0);
        }
        if (LIST_FIRST(&mii->mii_phys) == NULL) {
                ifmedia_add(&mii->mii_media, IFM_ETHER | IFM_NONE, 0, NULL);
                ifmedia_set(&mii->mii_media, IFM_ETHER | IFM_NONE);
        } else
                ifmedia_set(&mii->mii_media, IFM_ETHER | IFM_AUTO);

        ifp = &sc->sc_ethercom.ec_if;
        strlcpy(ifp->if_xname, device_xname(sc->sc_dev), IFNAMSIZ);
        ifp->if_softc = sc;
        ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
        ifp->if_ioctl = ste_ioctl;
        ifp->if_start = ste_start;
        ifp->if_watchdog = ste_watchdog;
        ifp->if_init = ste_init;
        ifp->if_stop = ste_stop;
        IFQ_SET_READY(&ifp->if_snd);

        /*
         * Default the transmit threshold to 128 bytes.
         */
        sc->sc_txthresh = 128;

        /*
         * Disable MWI if the PCI layer tells us to.
         */
        sc->sc_DMACtrl = 0;
        if ((pa->pa_flags & PCI_FLAGS_MWI_OKAY) == 0)
                sc->sc_DMACtrl |= DC_MWIDisable;

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

        /*
         * Attach the interface.
         */
        if_attach(ifp);
        if_deferred_start_init(ifp, NULL);
        ether_ifattach(ifp, enaddr);

        /*
         * Make sure the interface is shutdown during reboot.
         */
        if (pmf_device_register1(self, NULL, NULL, ste_shutdown))
                pmf_class_network_register(self, ifp);
        else
                aprint_error_dev(self, "couldn't establish power handler\n");

        return;

        /*
         * Free any resources we've allocated during the failed attach
         * attempt.  Do this in reverse order and fall through.
         */
 fail_5:
        for (i = 0; i < STE_NRXDESC; i++) {
                if (sc->sc_rxsoft[i].ds_dmamap != NULL)
                        bus_dmamap_destroy(sc->sc_dmat,
                            sc->sc_rxsoft[i].ds_dmamap);
        }
 fail_4:
        for (i = 0; i < STE_NTXDESC; i++) {
                if (sc->sc_txsoft[i].ds_dmamap != NULL)
                        bus_dmamap_destroy(sc->sc_dmat,
                            sc->sc_txsoft[i].ds_dmamap);
        }
        bus_dmamap_unload(sc->sc_dmat, sc->sc_cddmamap);
 fail_3:
        bus_dmamap_destroy(sc->sc_dmat, sc->sc_cddmamap);
 fail_2:
        bus_dmamem_unmap(sc->sc_dmat, (void *)sc->sc_control_data,
            sizeof(struct ste_control_data));
 fail_1:
        bus_dmamem_free(sc->sc_dmat, &seg, rseg);
 fail_0:
        return;
}

/*
 * ste_shutdown:
 *
 *      Make sure the interface is stopped at reboot time.
 */
static bool
ste_shutdown(device_t self, int howto)
{
        struct ste_softc *sc;

        sc = device_private(self);
        ste_stop(&sc->sc_ethercom.ec_if, 1);

        return true;
}

static void
ste_dmahalt_wait(struct ste_softc *sc)
{
        int i;

        for (i = 0; i < STE_TIMEOUT; i++) {
                delay(2);
                if ((bus_space_read_4(sc->sc_st, sc->sc_sh, STE_DMACtrl) &
                     DC_DMAHaltBusy) == 0)
                        break;
        }

        if (i == STE_TIMEOUT)
                printf("%s: DMA halt timed out\n", device_xname(sc->sc_dev));
}

/*
 * ste_start:           [ifnet interface function]
 *
 *      Start packet transmission on the interface.
 */
static void
ste_start(struct ifnet *ifp)
{
        struct ste_softc *sc = ifp->if_softc;
        struct mbuf *m0, *m;
        struct ste_descsoft *ds;
        struct ste_tfd *tfd;
        bus_dmamap_t dmamap;
        int error, olasttx, nexttx, opending, seg, totlen;

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

        /*
         * Remember the previous number of pending transmissions
         * and the current last descriptor in the list.
         */
        opending = sc->sc_txpending;
        olasttx = sc->sc_txlast;

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

                /*
                 * Get the last and next available transmit descriptor.
                 */
                nexttx = STE_NEXTTX(sc->sc_txlast);
                tfd = &sc->sc_txdescs[nexttx];
                ds = &sc->sc_txsoft[nexttx];

                dmamap = ds->ds_dmamap;

                /*
                 * Load the DMA map.  If this fails, the packet either
                 * didn't fit in the allotted number of segments, or we
                 * were short on resources.  In this case, we'll copy
                 * and try again.
                 */
                if (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",
                                    device_xname(sc->sc_dev));
                                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",
                                            device_xname(sc->sc_dev));
                                        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", device_xname(sc->sc_dev),
                                    error);
                                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 fragment list. */
                for (totlen = 0, seg = 0; seg < dmamap->dm_nsegs; seg++) {
                        tfd->tfd_frags[seg].frag_addr =
                            htole32(dmamap->dm_segs[seg].ds_addr);
                        tfd->tfd_frags[seg].frag_len =
                            htole32(dmamap->dm_segs[seg].ds_len);
                        totlen += dmamap->dm_segs[seg].ds_len;
                }
                tfd->tfd_frags[seg - 1].frag_len |= htole32(FRAG_LAST);

                /* Initialize the descriptor. */
                tfd->tfd_next = htole32(STE_CDTXADDR(sc, nexttx));
                tfd->tfd_control = htole32(TFD_FrameId(nexttx) | (totlen & 3));

                /* Sync the descriptor. */
                STE_CDTXSYNC(sc, nexttx,
                    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.
                 */
                ds->ds_mbuf = m0;

                /* Advance the tx pointer. */
                sc->sc_txpending++;
                sc->sc_txlast = nexttx;

                /*
                 * Pass the packet to any BPF listeners.
                 */
                bpf_mtap(ifp, m0, BPF_D_OUT);
        }

        if (sc->sc_txpending != opending) {
                /*
                 * We enqueued packets.  If the transmitter was idle,
                 * reset the txdirty pointer.
                 */
                if (opending == 0)
                        sc->sc_txdirty = STE_NEXTTX(olasttx);

                /*
                 * Cause a descriptor interrupt to happen on the
                 * last packet we enqueued, and also cause the
                 * DMA engine to wait after is has finished processing
                 * it.
                 */
                sc->sc_txdescs[sc->sc_txlast].tfd_next = 0;
                sc->sc_txdescs[sc->sc_txlast].tfd_control |=
                    htole32(TFD_TxDMAIndicate);
                STE_CDTXSYNC(sc, sc->sc_txlast,
                    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

                /*
                 * Link up the new chain of descriptors to the
                 * last.
                 */
                sc->sc_txdescs[olasttx].tfd_next =
                    htole32(STE_CDTXADDR(sc, STE_NEXTTX(olasttx)));
                STE_CDTXSYNC(sc, olasttx,
                    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

                /*
                 * Kick the transmit DMA logic.  Note that since we're
                 * using auto-polling, reading the Tx desc pointer will
                 * give it the nudge it needs to get going.
                 */
                if (bus_space_read_4(sc->sc_st, sc->sc_sh,
                    STE_TxDMAListPtr) == 0) {
                        bus_space_write_4(sc->sc_st, sc->sc_sh,
                            STE_DMACtrl, DC_TxDMAHalt);
                        ste_dmahalt_wait(sc);
                        bus_space_write_4(sc->sc_st, sc->sc_sh,
                            STE_TxDMAListPtr,
                            STE_CDTXADDR(sc, STE_NEXTTX(olasttx)));
                        bus_space_write_4(sc->sc_st, sc->sc_sh,
                            STE_DMACtrl, DC_TxDMAResume);
                }

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

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

        printf("%s: device timeout\n", device_xname(sc->sc_dev));
        if_statinc(ifp, if_oerrors);

        ste_txintr(sc);
        ste_rxintr(sc);
        (void) ste_init(ifp);

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

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

        s = splnet();

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

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

        splx(s);
        return (error);
}

/*
 * ste_intr:
 *
 *      Interrupt service routine.
 */
static int
ste_intr(void *arg)
{
        struct ste_softc *sc = arg;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        uint16_t isr;
        uint8_t txstat;
        int wantinit;

        if ((bus_space_read_2(sc->sc_st, sc->sc_sh, STE_IntStatus) &
             IS_InterruptStatus) == 0)
                return (0);

        for (wantinit = 0; wantinit == 0;) {
                isr = bus_space_read_2(sc->sc_st, sc->sc_sh, STE_IntStatusAck);
                if ((isr & sc->sc_IntEnable) == 0)
                        break;

                /* Receive interrupts. */
                if (isr & IE_RxDMAComplete)
                        ste_rxintr(sc);

                /* Transmit interrupts. */
                if (isr & (IE_TxDMAComplete | IE_TxComplete))
                        ste_txintr(sc);

                /* Statistics overflow. */
                if (isr & IE_UpdateStats)
                        ste_stats_update(sc);

                /* Transmission errors. */
                if (isr & IE_TxComplete) {
                        for (;;) {
                                txstat = bus_space_read_1(sc->sc_st, sc->sc_sh,
                                    STE_TxStatus);
                                if ((txstat & TS_TxComplete) == 0)
                                        break;
                                if (txstat & TS_TxUnderrun) {
                                        sc->sc_txthresh += 32;
                                        if (sc->sc_txthresh > 0x1ffc)
                                                sc->sc_txthresh = 0x1ffc;
                                        printf("%s: transmit underrun, new "
                                            "threshold: %d bytes\n",
                                            device_xname(sc->sc_dev),
                                            sc->sc_txthresh);
                                        ste_reset(sc, AC_TxReset | AC_DMA |
                                            AC_FIFO | AC_Network);
                                        ste_setthresh(sc);
                                        bus_space_write_1(sc->sc_st, sc->sc_sh,
                                            STE_TxDMAPollPeriod, 127);
                                        ste_txrestart(sc,
                                            bus_space_read_1(sc->sc_st,
                                                sc->sc_sh, STE_TxFrameId));
                                }
                                if (txstat & TS_TxReleaseError) {
                                        printf("%s: Tx FIFO release error\n",
                                            device_xname(sc->sc_dev));
                                        wantinit = 1;
                                }
                                if (txstat & TS_MaxCollisions) {
                                        printf("%s: excessive collisions\n",
                                            device_xname(sc->sc_dev));
                                        wantinit = 1;
                                }
                                if (txstat & TS_TxStatusOverflow) {
                                        printf("%s: status overflow\n",
                                            device_xname(sc->sc_dev));
                                        wantinit = 1;
                                }
                                bus_space_write_2(sc->sc_st, sc->sc_sh,
                                    STE_TxStatus, 0);
                        }
                }

                /* Host interface errors. */
                if (isr & IE_HostError) {
                        printf("%s: Host interface error\n",
                            device_xname(sc->sc_dev));
                        wantinit = 1;
                }
        }

        if (wantinit)
                ste_init(ifp);

        bus_space_write_2(sc->sc_st, sc->sc_sh, STE_IntEnable,
            sc->sc_IntEnable);

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

        return (1);
}

/*
 * ste_txintr:
 *
 *      Helper; handle transmit interrupts.
 */
static void
ste_txintr(struct ste_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct ste_descsoft *ds;
        uint32_t control;
        int i;

        /*
         * Go through our Tx list and free mbufs for those
         * frames which have been transmitted.
         */
        for (i = sc->sc_txdirty; sc->sc_txpending != 0;
             i = STE_NEXTTX(i), sc->sc_txpending--) {
                ds = &sc->sc_txsoft[i];

                STE_CDTXSYNC(sc, i,
                    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);

                control = le32toh(sc->sc_txdescs[i].tfd_control);
                if ((control & TFD_TxDMAComplete) == 0)
                        break;

                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;
        }

        /* Update the dirty transmit buffer pointer. */
        sc->sc_txdirty = i;

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

/*
 * ste_rxintr:
 *
 *      Helper; handle receive interrupts.
 */
static void
ste_rxintr(struct ste_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct ste_descsoft *ds;
        struct mbuf *m;
        uint32_t status;
        int i, len;

        for (i = sc->sc_rxptr;; i = STE_NEXTRX(i)) {
                ds = &sc->sc_rxsoft[i];

                STE_CDRXSYNC(sc, i,
                    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);

                status = le32toh(sc->sc_rxdescs[i].rfd_status);

                if ((status & RFD_RxDMAComplete) == 0)
                        break;

                /*
                 * If the packet had an error, simply recycle the
                 * buffer.  Note, we count the error later in the
                 * periodic stats update.
                 */
                if (status & RFD_RxFrameError) {
                        STE_INIT_RXDESC(sc, i);
                        continue;
                }

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

                /*
                 * No errors; receive the packet.  Note, we have
                 * configured the chip to not include the CRC at
                 * the end of the packet.
                 */
                len = RFD_RxDMAFrameLen(status);

                /*
                 * If the packet is small enough to fit in a
                 * single header mbuf, allocate one and copy
                 * the data into it.  This greatly reduces
                 * memory consumption when we receive lots
                 * of small packets.
                 *
                 * Otherwise, we add a new buffer to the receive
                 * chain.  If this fails, we drop the packet and
                 * recycle the old buffer.
                 */
                if (ste_copy_small != 0 && len <= (MHLEN - 2)) {
                        MGETHDR(m, M_DONTWAIT, MT_DATA);
                        if (m == NULL)
                                goto dropit;
                        MCLAIM(m, &sc->sc_ethercom.ec_rx_mowner);
                        m->m_data += 2;
                        memcpy(mtod(m, void *),
                            mtod(ds->ds_mbuf, void *), len);
                        STE_INIT_RXDESC(sc, i);
                        bus_dmamap_sync(sc->sc_dmat, ds->ds_dmamap, 0,
                            ds->ds_dmamap->dm_mapsize,
                            BUS_DMASYNC_PREREAD);
                } else {
                        m = ds->ds_mbuf;
                        if (ste_add_rxbuf(sc, i) != 0) {
 dropit:
                                if_statinc(ifp, if_ierrors);
                                STE_INIT_RXDESC(sc, i);
                                bus_dmamap_sync(sc->sc_dmat,
                                    ds->ds_dmamap, 0,
                                    ds->ds_dmamap->dm_mapsize,
                                    BUS_DMASYNC_PREREAD);
                                continue;
                        }
                }

                m_set_rcvif(m, ifp);
                m->m_pkthdr.len = m->m_len = len;

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

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

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

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

        callout_schedule(&sc->sc_tick_ch, hz);
}

/*
 * ste_stats_update:
 *
 *      Read the ST-201 statistics counters.
 */
static void
ste_stats_update(struct ste_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        bus_space_tag_t st = sc->sc_st;
        bus_space_handle_t sh = sc->sc_sh;

        (void) bus_space_read_2(st, sh, STE_OctetsReceivedOk0);
        (void) bus_space_read_2(st, sh, STE_OctetsReceivedOk1);

        (void) bus_space_read_2(st, sh, STE_OctetsTransmittedOk0);
        (void) bus_space_read_2(st, sh, STE_OctetsTransmittedOk1);

        net_stat_ref_t nsr = IF_STAT_GETREF(ifp);

        if_statadd_ref(ifp, nsr, if_opackets,
            (u_int) bus_space_read_2(st, sh, STE_FramesTransmittedOK));

        (void) bus_space_read_2(st, sh, STE_FramesReceivedOK);

        if_statadd_ref(ifp, nsr, if_collisions,
            (u_int) bus_space_read_1(st, sh, STE_LateCollisions) +
            (u_int) bus_space_read_1(st, sh, STE_MultipleColFrames) +
            (u_int) bus_space_read_1(st, sh, STE_SingleColFrames));

        (void) bus_space_read_1(st, sh, STE_FramesWDeferredXmt);

        if_statadd_ref(ifp, nsr, if_ierrors,
            (u_int) bus_space_read_1(st, sh, STE_FramesLostRxErrors));

        if_statadd_ref(ifp, nsr, if_oerrors,
            (u_int) bus_space_read_1(st, sh, STE_FramesWExDeferral) +
            (u_int) bus_space_read_1(st, sh, STE_FramesXbortXSColls) +
            bus_space_read_1(st, sh, STE_CarrierSenseErrors));

        IF_STAT_PUTREF(ifp);

        (void) bus_space_read_1(st, sh, STE_BcstFramesXmtdOk);
        (void) bus_space_read_1(st, sh, STE_BcstFramesRcvdOk);
        (void) bus_space_read_1(st, sh, STE_McstFramesXmtdOk);
        (void) bus_space_read_1(st, sh, STE_McstFramesRcvdOk);
}

/*
 * ste_reset:
 *
 *      Perform a soft reset on the ST-201.
 */
static void
ste_reset(struct ste_softc *sc, uint32_t rstbits)
{
        uint32_t ac;
        int i;

        ac = bus_space_read_4(sc->sc_st, sc->sc_sh, STE_AsicCtrl);

        bus_space_write_4(sc->sc_st, sc->sc_sh, STE_AsicCtrl, ac | rstbits);

        delay(50000);

        for (i = 0; i < STE_TIMEOUT; i++) {
                delay(1000);
                if ((bus_space_read_4(sc->sc_st, sc->sc_sh, STE_AsicCtrl) &
                     AC_ResetBusy) == 0)
                        break;
        }

        if (i == STE_TIMEOUT)
                printf("%s: reset failed to complete\n",
                    device_xname(sc->sc_dev));

        delay(1000);
}

/*
 * ste_setthresh:
 *
 *      set the various transmit threshold registers
 */
static void
ste_setthresh(struct ste_softc *sc)
{
        /* set the TX threhold */
        bus_space_write_2(sc->sc_st, sc->sc_sh,
            STE_TxStartThresh, sc->sc_txthresh);
        /* Urgent threshold: set to sc_txthresh / 2 */
        bus_space_write_1(sc->sc_st, sc->sc_sh, STE_TxDMAUrgentThresh,
            sc->sc_txthresh >> 6);
        /* Burst threshold: use default value (256 bytes) */
}

/*
 * restart TX at the given frame ID in the transmitter ring
 */
static void
ste_txrestart(struct ste_softc *sc, uint8_t id)
{
        uint32_t control;

        STE_CDTXSYNC(sc, id, BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
        control = le32toh(sc->sc_txdescs[id].tfd_control);
        control &= ~TFD_TxDMAComplete;
        sc->sc_txdescs[id].tfd_control = htole32(control);
        STE_CDTXSYNC(sc, id, BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);

        bus_space_write_4(sc->sc_st, sc->sc_sh, STE_TxDMAListPtr, 0);
        bus_space_write_2(sc->sc_st, sc->sc_sh, STE_MacCtrl1, MC1_TxEnable);
        bus_space_write_4(sc->sc_st, sc->sc_sh, STE_DMACtrl, DC_TxDMAHalt);
        ste_dmahalt_wait(sc);
        bus_space_write_4(sc->sc_st, sc->sc_sh, STE_TxDMAListPtr,
            STE_CDTXADDR(sc, id));
        bus_space_write_4(sc->sc_st, sc->sc_sh, STE_DMACtrl, DC_TxDMAResume);
}

/*
 * ste_init:            [ ifnet interface function ]
 *
 *      Initialize the interface.  Must be called at splnet().
 */
static int
ste_init(struct ifnet *ifp)
{
        struct ste_softc *sc = ifp->if_softc;
        bus_space_tag_t st = sc->sc_st;
        bus_space_handle_t sh = sc->sc_sh;
        struct ste_descsoft *ds;
        int i, error = 0;

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

        /*
         * Reset the chip to a known state.
         */
        ste_reset(sc, AC_GlobalReset | AC_RxReset | AC_TxReset | AC_DMA |
            AC_FIFO | AC_Network | AC_Host | AC_AutoInit | AC_RstOut);

        /*
         * Initialize the transmit descriptor ring.
         */
        memset(sc->sc_txdescs, 0, sizeof(sc->sc_txdescs));
        sc->sc_txpending = 0;
        sc->sc_txdirty = 0;
        sc->sc_txlast = STE_NTXDESC - 1;

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

        /* Set the station address. */
        for (i = 0; i < ETHER_ADDR_LEN; i++)
                bus_space_write_1(st, sh, STE_StationAddress0 + 1,
                    CLLADDR(ifp->if_sadl)[i]);

        /* Set up the receive filter. */
        ste_set_filter(sc);

        /*
         * Give the receive ring to the chip.
         */
        bus_space_write_4(st, sh, STE_RxDMAListPtr,
            STE_CDRXADDR(sc, sc->sc_rxptr));

        /*
         * We defer giving the transmit ring to the chip until we
         * transmit the first packet.
         */

        /*
         * Initialize the Tx auto-poll period.  It's OK to make this number
         * large (127 is the max) -- we explicitly kick the transmit engine
         * when there's actually a packet.  We are using auto-polling only
         * to make the interface to the transmit engine not suck.
         */
        bus_space_write_1(sc->sc_st, sc->sc_sh, STE_TxDMAPollPeriod, 127);

        /* ..and the Rx auto-poll period. */
        bus_space_write_1(st, sh, STE_RxDMAPollPeriod, 64);

        /* Initialize the Tx start threshold. */
        ste_setthresh(sc);

        /* Set the FIFO release threshold to 512 bytes. */
        bus_space_write_1(st, sh, STE_TxReleaseThresh, 512 >> 4);

        /* Set maximum packet size for VLAN. */
        if (sc->sc_ethercom.ec_capenable & ETHERCAP_VLAN_MTU)
                bus_space_write_2(st, sh, STE_MaxFrameSize, ETHER_MAX_LEN + 4);
        else
                bus_space_write_2(st, sh, STE_MaxFrameSize, ETHER_MAX_LEN);

        /*
         * Initialize the interrupt mask.
         */
        sc->sc_IntEnable = IE_HostError | IE_TxComplete | IE_UpdateStats |
            IE_TxDMAComplete | IE_RxDMAComplete;

        bus_space_write_2(st, sh, STE_IntStatus, 0xffff);
        bus_space_write_2(st, sh, STE_IntEnable, sc->sc_IntEnable);

        /*
         * Start the receive DMA engine.
         */
        bus_space_write_4(st, sh, STE_DMACtrl, sc->sc_DMACtrl | DC_RxDMAResume);

        /*
         * Initialize MacCtrl0 -- do it before setting the media,
         * as setting the media will actually program the register.
         */
        sc->sc_MacCtrl0 = MC0_IFSSelect(0);
        if (sc->sc_ethercom.ec_capenable & ETHERCAP_VLAN_MTU)
                sc->sc_MacCtrl0 |= MC0_RcvLargeFrames;

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

        /*
         * Start the MAC.
         */
        bus_space_write_2(st, sh, STE_MacCtrl1,
            MC1_StatisticsEnable | MC1_TxEnable | MC1_RxEnable);

        /*
         * Start the one second MII clock.
         */
        callout_schedule(&sc->sc_tick_ch, hz);

        /*
         * ...all done!
         */
        ifp->if_flags |= IFF_RUNNING;

 out:
        if (error)
                printf("%s: interface not running\n", device_xname(sc->sc_dev));
        return (error);
}

/*
 * ste_drain:
 *
 *      Drain the receive queue.
 */
static void
ste_rxdrain(struct ste_softc *sc)
{
        struct ste_descsoft *ds;
        int i;

        for (i = 0; i < STE_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;
                }
        }
}

/*
 * ste_stop:            [ ifnet interface function ]
 *
 *      Stop transmission on the interface.
 */
static void
ste_stop(struct ifnet *ifp, int disable)
{
        struct ste_softc *sc = ifp->if_softc;
        struct ste_descsoft *ds;
        int i;

        /*
         * Stop the one second clock.
         */
        callout_stop(&sc->sc_tick_ch);

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

        /*
         * Disable interrupts.
         */
        bus_space_write_2(sc->sc_st, sc->sc_sh, STE_IntEnable, 0);

        /*
         * Stop receiver, transmitter, and stats update.
         */
        bus_space_write_2(sc->sc_st, sc->sc_sh, STE_MacCtrl1,
            MC1_StatisticsDisable | MC1_TxDisable | MC1_RxDisable);

        /*
         * Stop the transmit and receive DMA.
         */
        bus_space_write_4(sc->sc_st, sc->sc_sh, STE_DMACtrl,
            DC_RxDMAHalt | DC_TxDMAHalt);
        ste_dmahalt_wait(sc);

        /*
         * Release any queued transmit buffers.
         */
        for (i = 0; i < STE_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;
                }
        }

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

        if (disable)
                ste_rxdrain(sc);
}

static int
ste_eeprom_wait(struct ste_softc *sc)
{
        int i;

        for (i = 0; i < STE_TIMEOUT; i++) {
                delay(1000);
                if ((bus_space_read_2(sc->sc_st, sc->sc_sh, STE_EepromCtrl) &
                     EC_EepromBusy) == 0)
                        return (0);
        }
        return (1);
}

/*
 * ste_read_eeprom:
 *
 *      Read data from the serial EEPROM.
 */
static void
ste_read_eeprom(struct ste_softc *sc, int offset, uint16_t *data)
{

        if (ste_eeprom_wait(sc))
                printf("%s: EEPROM failed to come ready\n",
                    device_xname(sc->sc_dev));

        bus_space_write_2(sc->sc_st, sc->sc_sh, STE_EepromCtrl,
            EC_EepromAddress(offset) | EC_EepromOpcode(EC_OP_R));
        if (ste_eeprom_wait(sc))
                printf("%s: EEPROM read timed out\n",
                    device_xname(sc->sc_dev));
        *data = bus_space_read_2(sc->sc_st, sc->sc_sh, STE_EepromData);
}

/*
 * ste_add_rxbuf:
 *
 *      Add a receive buffer to the indicated descriptor.
 */
static int
ste_add_rxbuf(struct ste_softc *sc, int idx)
{
        struct ste_descsoft *ds = &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 (ds->ds_mbuf != NULL)
                bus_dmamap_unload(sc->sc_dmat, ds->ds_dmamap);

        ds->ds_mbuf = m;

        error = bus_dmamap_load(sc->sc_dmat, ds->ds_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",
                    device_xname(sc->sc_dev), idx, error);
                panic("ste_add_rxbuf");         /* XXX */
        }

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

        STE_INIT_RXDESC(sc, idx);

        return (0);
}

/*
 * ste_set_filter:
 *
 *      Set up the receive filter.
 */
static void
ste_set_filter(struct ste_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 crc;
        uint16_t mchash[4];

        sc->sc_ReceiveMode = RM_ReceiveUnicast;
        if (ifp->if_flags & IFF_BROADCAST)
                sc->sc_ReceiveMode |= RM_ReceiveBroadcast;

        if (ifp->if_flags & IFF_PROMISC) {
                sc->sc_ReceiveMode |= RM_ReceiveAllFrames;
                goto allmulti;
        }

        /*
         * Set up the multicast address filter by passing all multicast
         * addresses through a CRC generator, and then using the low-order
         * 6 bits as an index into the 64 bit multicast hash table.  The
         * high order bits select the register, while the rest of the bits
         * select the bit within the register.
         */

        memset(mchash, 0, sizeof(mchash));

        ETHER_LOCK(ec);
        ETHER_FIRST_MULTI(step, ec, enm);
        if (enm == NULL) {
                ETHER_UNLOCK(ec);
                goto done;
        }

        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.)
                         */
                        ETHER_UNLOCK(ec);
                        goto allmulti;
                }

                crc = ether_crc32_be(enm->enm_addrlo, ETHER_ADDR_LEN);

                /* Just want the 6 least significant bits. */
                crc &= 0x3f;

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

                ETHER_NEXT_MULTI(step, enm);
        }
        ETHER_UNLOCK(ec);

        sc->sc_ReceiveMode |= RM_ReceiveMulticastHash;

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

 allmulti:
        ifp->if_flags |= IFF_ALLMULTI;
        sc->sc_ReceiveMode |= RM_ReceiveMulticast;

 done:
        if ((ifp->if_flags & IFF_ALLMULTI) == 0) {
                /*
                 * Program the multicast hash table.
                 */
                bus_space_write_2(sc->sc_st, sc->sc_sh, STE_HashTable0,
                    mchash[0]);
                bus_space_write_2(sc->sc_st, sc->sc_sh, STE_HashTable1,
                    mchash[1]);
                bus_space_write_2(sc->sc_st, sc->sc_sh, STE_HashTable2,
                    mchash[2]);
                bus_space_write_2(sc->sc_st, sc->sc_sh, STE_HashTable3,
                    mchash[3]);
        }

        bus_space_write_1(sc->sc_st, sc->sc_sh, STE_ReceiveMode,
            sc->sc_ReceiveMode);
}

/*
 * ste_mii_readreg:     [mii interface function]
 *
 *      Read a PHY register on the MII of the ST-201.
 */
static int
ste_mii_readreg(device_t self, int phy, int reg, uint16_t *val)
{
        struct ste_softc *sc = device_private(self);

        if (phy == 0 && !sc->sc_enable_phy0)
                return EIO;

        return mii_bitbang_readreg(self, &ste_mii_bitbang_ops, phy, reg, val);
}

/*
 * ste_mii_writereg:    [mii interface function]
 *
 *      Write a PHY register on the MII of the ST-201.
 */
static int
ste_mii_writereg(device_t self, int phy, int reg, uint16_t val)
{
        struct ste_softc *sc = device_private(self);

        if (phy == 0 && !sc->sc_enable_phy0)
                return EIO;

        return mii_bitbang_writereg(self, &ste_mii_bitbang_ops, phy, reg, val);
}

/*
 * ste_mii_statchg:     [mii interface function]
 *
 *      Callback from MII layer when media changes.
 */
static void
ste_mii_statchg(struct ifnet *ifp)
{
        struct ste_softc *sc = ifp->if_softc;

        if (sc->sc_mii.mii_media_active & IFM_FDX)
                sc->sc_MacCtrl0 |= MC0_FullDuplexEnable;
        else
                sc->sc_MacCtrl0 &= ~MC0_FullDuplexEnable;

        /* XXX 802.1x flow-control? */

        bus_space_write_2(sc->sc_st, sc->sc_sh, STE_MacCtrl0, sc->sc_MacCtrl0);
}

/*
 * ste_mii_bitbang_read: [mii bit-bang interface function]
 *
 *      Read the MII serial port for the MII bit-bang module.
 */
static uint32_t
ste_mii_bitbang_read(device_t self)
{
        struct ste_softc *sc = device_private(self);

        return (bus_space_read_1(sc->sc_st, sc->sc_sh, STE_PhyCtrl));
}

/*
 * ste_mii_bitbang_write: [mii big-bang interface function]
 *
 *      Write the MII serial port for the MII bit-bang module.
 */
static void
ste_mii_bitbang_write(device_t self, uint32_t val)
{
        struct ste_softc *sc = device_private(self);

        bus_space_write_1(sc->sc_st, sc->sc_sh, STE_PhyCtrl, val);
}