/*      $NetBSD: if_pcn.c,v 1.83 2026/03/29 14:46:04 kre Exp $  */

/*
 * Copyright (c) 2001 Wasabi Systems, Inc.
 * All rights reserved.
 *
 * Written by Jason R. Thorpe for Wasabi Systems, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed for the NetBSD Project by
 *      Wasabi Systems, Inc.
 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``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 WASABI SYSTEMS, INC
 * 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 AMD PCnet-PCI series of Ethernet
 * chips:
 *
 *      * Am79c970 PCnet-PCI Single-Chip Ethernet Controller for PCI
 *        Local Bus
 *
 *      * Am79c970A PCnet-PCI II Single-Chip Full-Duplex Ethernet Controller
 *        for PCI Local Bus
 *
 *      * Am79c971 PCnet-FAST Single-Chip Full-Duplex 10/100Mbps
 *        Ethernet Controller for PCI Local Bus
 *
 *      * Am79c972 PCnet-FAST+ Enhanced 10/100Mbps PCI Ethernet Controller
 *        with OnNow Support
 *
 *      * Am79c973/Am79c975 PCnet-FAST III Single-Chip 10/100Mbps PCI
 *        Ethernet Controller with Integrated PHY
 *
 * This also supports the virtual PCnet-PCI Ethernet interface found
 * in VMware.
 *
 * TODO:
 *
 *      * Split this into bus-specific and bus-independent portions.
 *        The core could also be used for the ILACC (Am79900) 32-bit
 *        Ethernet chip (XXX only if we use an ILACC-compatible SWSTYLE).
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_pcn.c,v 1.83 2026/03/29 14:46:04 kre 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 <sys/rndsource.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 <machine/endian.h>

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

#include <dev/ic/am79900reg.h>
#include <dev/ic/lancereg.h>

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

#include <dev/pci/if_pcnreg.h>

/*
 * Transmit descriptor list size.  This is arbitrary, but allocate
 * enough descriptors for 128 pending transmissions, and 4 segments
 * per packet.  This MUST work out to a power of 2.
 *
 * NOTE: We can't have any more than 512 Tx descriptors, SO BE CAREFUL!
 *
 * So we play a little trick here.  We give each packet up to 16
 * DMA segments, but only allocate the max of 512 descriptors.  The
 * transmit logic can deal with this, we just are hoping to sneak by.
 */
#define PCN_NTXSEGS             16
#define PCN_NTXSEGS_VMWARE      8       /* bug in VMware's emulation */

#define PCN_TXQUEUELEN          128
#define PCN_TXQUEUELEN_MASK     (PCN_TXQUEUELEN - 1)
#define PCN_NTXDESC             512
#define PCN_NTXDESC_MASK        (PCN_NTXDESC - 1)
#define PCN_NEXTTX(x)           (((x) + 1) & PCN_NTXDESC_MASK)
#define PCN_NEXTTXS(x)          (((x) + 1) & PCN_TXQUEUELEN_MASK)

/* Tx interrupt every N + 1 packets. */
#define PCN_TXINTR_MASK         7

/*
 * Receive descriptor list size.  We have one Rx buffer per incoming
 * packet, so this logic is a little simpler.
 */
#define PCN_NRXDESC             128
#define PCN_NRXDESC_MASK        (PCN_NRXDESC - 1)
#define PCN_NEXTRX(x)           (((x) + 1) & PCN_NRXDESC_MASK)

/*
 * Control structures are DMA'd to the PCnet chip.  We allocate them in
 * a single clump that maps to a single DMA segment to make several things
 * easier.
 */
struct pcn_control_data {
        /* The transmit descriptors. */
        struct letmd pcd_txdescs[PCN_NTXDESC];

        /* The receive descriptors. */
        struct lermd pcd_rxdescs[PCN_NRXDESC];

        /* The init block. */
        struct leinit pcd_initblock;
};

#define PCN_CDOFF(x)    offsetof(struct pcn_control_data, x)
#define PCN_CDTXOFF(x)  PCN_CDOFF(pcd_txdescs[(x)])
#define PCN_CDRXOFF(x)  PCN_CDOFF(pcd_rxdescs[(x)])
#define PCN_CDINITOFF   PCN_CDOFF(pcd_initblock)

/*
 * Software state for transmit jobs.
 */
struct pcn_txsoft {
        struct mbuf *txs_mbuf;          /* head of our mbuf chain */
        bus_dmamap_t txs_dmamap;        /* our DMA map */
        int txs_firstdesc;              /* first descriptor in packet */
        int txs_lastdesc;               /* last descriptor in packet */
};

/*
 * Software state for receive jobs.
 */
struct pcn_rxsoft {
        struct mbuf *rxs_mbuf;          /* head of our mbuf chain */
        bus_dmamap_t rxs_dmamap;        /* our DMA map */
};

/*
 * Description of Rx FIFO watermarks for various revisions.
 */
static const char * const pcn_79c970_rcvfw[] = {
        "16 bytes",
        "64 bytes",
        "128 bytes",
        NULL,
};

static const char * const pcn_79c971_rcvfw[] = {
        "16 bytes",
        "64 bytes",
        "112 bytes",
        NULL,
};

/*
 * Description of Tx start points for various revisions.
 */
static const char * const pcn_79c970_xmtsp[] = {
        "8 bytes",
        "64 bytes",
        "128 bytes",
        "248 bytes",
};

static const char * const pcn_79c971_xmtsp[] = {
        "20 bytes",
        "64 bytes",
        "128 bytes",
        "248 bytes",
};

static const char * const pcn_79c971_xmtsp_sram[] = {
        "44 bytes",
        "64 bytes",
        "128 bytes",
        "store-and-forward",
};

/*
 * Description of Tx FIFO watermarks for various revisions.
 */
static const char * const pcn_79c970_xmtfw[] = {
        "16 bytes",
        "64 bytes",
        "128 bytes",
        NULL,
};

static const char * const pcn_79c971_xmtfw[] = {
        "16 bytes",
        "64 bytes",
        "108 bytes",
        NULL,
};

/*
 * Software state per device.
 */
struct pcn_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 */

        /* Points to our media routines, etc. */
        const struct pcn_variant *sc_variant;

        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 pcn_txsoft sc_txsoft[PCN_TXQUEUELEN];
        struct pcn_rxsoft sc_rxsoft[PCN_NRXDESC];

        /* Control data structures */
        struct pcn_control_data *sc_control_data;
#define sc_txdescs      sc_control_data->pcd_txdescs
#define sc_rxdescs      sc_control_data->pcd_rxdescs
#define sc_initblock    sc_control_data->pcd_initblock

#ifdef PCN_EVENT_COUNTERS
        /* Event counters. */
        struct evcnt sc_ev_txdstall;    /* Tx stalled due to no txd */
        struct evcnt sc_ev_txintr;      /* Tx interrupts */
        struct evcnt sc_ev_rxintr;      /* Rx interrupts */
        struct evcnt sc_ev_babl;        /* BABL in pcn_intr() */
        struct evcnt sc_ev_miss;        /* MISS in pcn_intr() */
        struct evcnt sc_ev_merr;        /* MERR in pcn_intr() */

        struct evcnt sc_ev_txseg1;      /* Tx packets w/ 1 segment */
        struct evcnt sc_ev_txseg2;      /* Tx packets w/ 2 segments */
        struct evcnt sc_ev_txseg3;      /* Tx packets w/ 3 segments */
        struct evcnt sc_ev_txseg4;      /* Tx packets w/ 4 segments */
        struct evcnt sc_ev_txseg5;      /* Tx packets w/ 5 segments */
        struct evcnt sc_ev_txsegmore;   /* Tx packets w/ more than 5 segments */
        struct evcnt sc_ev_txcopy;      /* Tx copies required */
#endif /* PCN_EVENT_COUNTERS */

        const char * const *sc_rcvfw_desc;      /* Rx FIFO watermark info */
        int sc_rcvfw;

        const char * const *sc_xmtsp_desc;      /* Tx start point info */
        int sc_xmtsp;

        const char * const *sc_xmtfw_desc;      /* Tx FIFO watermark info */
        int sc_xmtfw;

        int sc_flags;                   /* misc. flags; see below */
        int sc_swstyle;                 /* the software style in use */

        int sc_txfree;                  /* number of free Tx descriptors */
        int sc_txnext;                  /* next ready Tx descriptor */

        int sc_txsfree;                 /* number of free Tx jobs */
        int sc_txsnext;                 /* next free Tx job */
        int sc_txsdirty;                /* dirty Tx jobs */

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

        uint32_t sc_csr5;               /* prototype CSR5 register */
        uint32_t sc_mode;               /* prototype MODE register */

        krndsource_t rnd_source;        /* random source */
};

/* sc_flags */
#define PCN_F_HAS_MII           0x0001  /* has MII */

#ifdef PCN_EVENT_COUNTERS
#define PCN_EVCNT_INCR(ev)      (ev)->ev_count++
#else
#define PCN_EVCNT_INCR(ev)      /* nothing */
#endif

#define PCN_CDTXADDR(sc, x)     ((sc)->sc_cddma + PCN_CDTXOFF((x)))
#define PCN_CDRXADDR(sc, x)     ((sc)->sc_cddma + PCN_CDRXOFF((x)))
#define PCN_CDINITADDR(sc)      ((sc)->sc_cddma + PCN_CDINITOFF)

#define PCN_CDTXSYNC(sc, x, n, ops)                                     \
do {                                                                    \
        int __x, __n;                                                   \
                                                                        \
        __x = (x);                                                      \
        __n = (n);                                                      \
                                                                        \
        /* If it will wrap around, sync to the end of the ring. */      \
        if ((__x + __n) > PCN_NTXDESC) {                                \
                bus_dmamap_sync((sc)->sc_dmat, (sc)->sc_cddmamap,       \
                    PCN_CDTXOFF(__x), sizeof(struct letmd) *            \
                    (PCN_NTXDESC - __x), (ops));                        \
                __n -= (PCN_NTXDESC - __x);                             \
                __x = 0;                                                \
        }                                                               \
                                                                        \
        /* Now sync whatever is left. */                                \
        bus_dmamap_sync((sc)->sc_dmat, (sc)->sc_cddmamap,               \
            PCN_CDTXOFF(__x), sizeof(struct letmd) * __n, (ops));       \
} while (/*CONSTCOND*/0)

#define PCN_CDRXSYNC(sc, x, ops)                                        \
        bus_dmamap_sync((sc)->sc_dmat, (sc)->sc_cddmamap,               \
            PCN_CDRXOFF((x)), sizeof(struct lermd), (ops))

#define PCN_CDINITSYNC(sc, ops)                                         \
        bus_dmamap_sync((sc)->sc_dmat, (sc)->sc_cddmamap,               \
            PCN_CDINITOFF, sizeof(struct leinit), (ops))

#define PCN_INIT_RXDESC(sc, x)                                          \
do {                                                                    \
        struct pcn_rxsoft *__rxs = &(sc)->sc_rxsoft[(x)];               \
        struct lermd *__rmd = &(sc)->sc_rxdescs[(x)];                   \
        struct mbuf *__m = __rxs->rxs_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;                           \
                                                                        \
        if ((sc)->sc_swstyle == LE_B20_SSTYLE_PCNETPCI3) {              \
                __rmd->rmd2 =                                           \
                    htole32(__rxs->rxs_dmamap->dm_segs[0].ds_addr + 2); \
                __rmd->rmd0 = 0;                                        \
        } else {                                                        \
                __rmd->rmd2 = 0;                                        \
                __rmd->rmd0 =                                           \
                    htole32(__rxs->rxs_dmamap->dm_segs[0].ds_addr + 2); \
        }                                                               \
        __rmd->rmd1 = htole32(LE_R1_OWN | LE_R1_ONES |                  \
            (LE_BCNT(MCLBYTES - 2) & LE_R1_BCNT_MASK));                 \
        PCN_CDRXSYNC((sc), (x), BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);\
} while(/*CONSTCOND*/0)

static void     pcn_start(struct ifnet *);
static void     pcn_watchdog(struct ifnet *);
static int      pcn_ioctl(struct ifnet *, u_long, void *);
static int      pcn_init(struct ifnet *);
static void     pcn_stop(struct ifnet *, int);

static bool     pcn_shutdown(device_t, int);

static void     pcn_reset(struct pcn_softc *);
static void     pcn_rxdrain(struct pcn_softc *);
static int      pcn_add_rxbuf(struct pcn_softc *, int);
static void     pcn_tick(void *);

static void     pcn_spnd(struct pcn_softc *);

static void     pcn_set_filter(struct pcn_softc *);

static int      pcn_intr(void *);
static void     pcn_txintr(struct pcn_softc *);
static int      pcn_rxintr(struct pcn_softc *);

static int      pcn_mii_readreg(device_t, int, int, uint16_t *);
static int      pcn_mii_writereg(device_t, int, int, uint16_t);
static void     pcn_mii_statchg(struct ifnet *);

static void     pcn_79c970_mediainit(struct pcn_softc *);
static int      pcn_79c970_mediachange(struct ifnet *);
static void     pcn_79c970_mediastatus(struct ifnet *, struct ifmediareq *);

static void     pcn_79c971_mediainit(struct pcn_softc *);

/*
 * Description of a PCnet-PCI variant.  Used to select media access
 * method, mostly, and to print a nice description of the chip.
 */
static const struct pcn_variant {
        const char *pcv_desc;
        void (*pcv_mediainit)(struct pcn_softc *);
        uint16_t pcv_chipid;
} pcn_variants[] = {
        { "Am79c970 PCnet-PCI",
          pcn_79c970_mediainit,
          PARTID_Am79c970 },

        { "Am79c970A PCnet-PCI II",
          pcn_79c970_mediainit,
          PARTID_Am79c970A },

        { "Am79c971 PCnet-FAST",
          pcn_79c971_mediainit,
          PARTID_Am79c971 },

        { "Am79c972 PCnet-FAST+",
          pcn_79c971_mediainit,
          PARTID_Am79c972 },

        { "Am79c973 PCnet-FAST III",
          pcn_79c971_mediainit,
          PARTID_Am79c973 },

        { "Am79c975 PCnet-FAST III",
          pcn_79c971_mediainit,
          PARTID_Am79c975 },

        { "Unknown PCnet-PCI variant",
          pcn_79c971_mediainit,
          0 },
};

int     pcn_copy_small = 0;

static int      pcn_match(device_t, cfdata_t, void *);
static void     pcn_attach(device_t, device_t, void *);

CFATTACH_DECL_NEW(pcn, sizeof(struct pcn_softc),
    pcn_match, pcn_attach, NULL, NULL);

/*
 * Routines to read and write the PCnet-PCI CSR/BCR space.
 */

static inline uint32_t
pcn_csr_read(struct pcn_softc *sc, int reg)
{

        bus_space_write_4(sc->sc_st, sc->sc_sh, PCN32_RAP, reg);
        return bus_space_read_4(sc->sc_st, sc->sc_sh, PCN32_RDP);
}

static inline void
pcn_csr_write(struct pcn_softc *sc, int reg, uint32_t val)
{

        bus_space_write_4(sc->sc_st, sc->sc_sh, PCN32_RAP, reg);
        bus_space_write_4(sc->sc_st, sc->sc_sh, PCN32_RDP, val);
}

static inline uint32_t
pcn_bcr_read(struct pcn_softc *sc, int reg)
{

        bus_space_write_4(sc->sc_st, sc->sc_sh, PCN32_RAP, reg);
        return bus_space_read_4(sc->sc_st, sc->sc_sh, PCN32_BDP);
}

static inline void
pcn_bcr_write(struct pcn_softc *sc, int reg, uint32_t val)
{

        bus_space_write_4(sc->sc_st, sc->sc_sh, PCN32_RAP, reg);
        bus_space_write_4(sc->sc_st, sc->sc_sh, PCN32_BDP, val);
}

static bool
pcn_is_vmware(const char *enaddr)
{

        /*
         * VMware uses the OUI 00:0c:29 for auto-generated MAC
         * addresses.
         */
        if (enaddr[0] == 0x00 && enaddr[1] == 0x0c && enaddr[2] == 0x29)
                return TRUE;

        /*
         * VMware uses the OUI 00:50:56 for manually-set MAC
         * addresses (and some auto-generated ones).
         */
        if (enaddr[0] == 0x00 && enaddr[1] == 0x50 && enaddr[2] == 0x56)
                return TRUE;

        return FALSE;
}

static const struct pcn_variant *
pcn_lookup_variant(uint16_t chipid)
{
        const struct pcn_variant *pcv;

        for (pcv = pcn_variants; pcv->pcv_chipid != 0; pcv++) {
                if (chipid == pcv->pcv_chipid)
                        return pcv;
        }

        /*
         * This covers unknown chips, which we simply treat like
         * a generic PCnet-FAST.
         */
        return pcv;
}

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

        /*
         * IBM Makes a PCI variant of this card which shows up as a
         * Trident Microsystems 4DWAVE DX (ethernet network, revision 0x25)
         * this card is truly a pcn card, so we have a special case match for
         * it
         */

        if (PCI_VENDOR(pa->pa_id) == PCI_VENDOR_TRIDENT &&
            PCI_PRODUCT(pa->pa_id) == PCI_PRODUCT_TRIDENT_4DWAVE_DX &&
            PCI_CLASS(pa->pa_class) == PCI_CLASS_NETWORK)
                return 1;

        if (PCI_VENDOR(pa->pa_id) != PCI_VENDOR_AMD)
                return 0;

        switch (PCI_PRODUCT(pa->pa_id)) {
        case PCI_PRODUCT_AMD_PCNET_PCI:
                /* Beat if_le_pci.c */
                return 10;
        }

        return 0;
}

static void
pcn_attach(device_t parent, device_t self, void *aux)
{
        struct pcn_softc *sc = device_private(self);
        struct pci_attach_args *pa = aux;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        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 ntxsegs, i, rseg, error;
        uint32_t chipid, reg;
        uint8_t enaddr[ETHER_ADDR_LEN];
        bool is_vmware;
        char intrbuf[PCI_INTRSTR_LEN];

        sc->sc_dev = self;
        callout_init(&sc->sc_tick_ch, 0);
        callout_setfunc(&sc->sc_tick_ch, pcn_tick, sc);

        aprint_normal(": AMD PCnet-PCI Ethernet\n");

        /*
         * Map the device.
         */
        ioh_valid = (pci_mapreg_map(pa, PCN_PCI_CBIO, PCI_MAPREG_TYPE_IO, 0,
            &iot, &ioh, NULL, NULL) == 0);
        memh_valid = (pci_mapreg_map(pa, PCN_PCI_CBMEM,
            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;

        /* Make sure bus mastering is enabled. */
        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(self, "cannot activate %d\n", error);
                return;
        }

        /*
         * Reset the chip to a known state.  This also puts the
         * chip into 32-bit mode.
         */
        pcn_reset(sc);

        /*
         * On some systems with the chip is an on-board device, the
         * EEPROM is not used.  Handle this by reading the MAC address
         * from the CSRs (assuming that boot firmware has written
         * it there).
         */
        if (device_getprop_bool(sc->sc_dev, "am79c970-no-eeprom")) {
                for (i = 0; i < 3; i++) {
                        uint32_t val;
                        val = pcn_csr_read(sc, LE_CSR12 + i);
                        enaddr[2 * i] = val & 0xff;
                        enaddr[2 * i + 1] = (val >> 8) & 0xff;
                }
        } else {
                /*
                 * Read the address ROM 4 bytes at a time; works on
                 * real hardware, and accommodates some emulators which
                 * believe that after pcn_reset(), we are in DWIO mode
                 * where byte access is not supported.
                 */
                for (i = 0; i < ETHER_ADDR_LEN; i+= 4) {
                        uint32_t word;
                        word = bus_space_read_4(sc->sc_st, sc->sc_sh,
                            PCN32_APROM + i);
                        enaddr[i] = word & 0xff;
                        if (i + 1 < ETHER_ADDR_LEN) {
                                enaddr[i + 1] = (word >> 8) & 0xff;
                        }
                        if (i + 2 < ETHER_ADDR_LEN) {
                                enaddr[i + 2] = (word >> 16) & 0xff;
                        }
                        if (i + 3 < ETHER_ADDR_LEN) {
                                enaddr[i + 3] = (word >> 24) & 0xff;
                        }
                }
        }

        /* Check to see if this is a VMware emulated network interface. */
        is_vmware = pcn_is_vmware(enaddr);

        /*
         * Now that the device is mapped, attempt to figure out what
         * kind of chip we have.  Note that IDL has all 32 bits of
         * the chip ID when we're in 32-bit mode.
         */
        chipid = pcn_csr_read(sc, LE_CSR88);
        sc->sc_variant = pcn_lookup_variant(CHIPID_PARTID(chipid));

        aprint_normal_dev(self, "%s rev %d, Ethernet address %s\n",
            sc->sc_variant->pcv_desc, CHIPID_VER(chipid),
            ether_sprintf(enaddr));

        /*
         * VMware has a bug in its network interface emulation; we must
         * limit the number of Tx segments.
         */
        if (is_vmware) {
                device_setprop_bool(sc->sc_dev, "am79c970-vmware-tx-bug", true);
                ntxsegs = PCN_NTXSEGS_VMWARE;
                aprint_verbose_dev(self,
                    "VMware Tx segment count bug detected\n");
        } else {
                ntxsegs = PCN_NTXSEGS;
        }

        /*
         * Map and establish our interrupt.
         */
        if (pci_intr_map(pa, &ih)) {
                aprint_error_dev(self, "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, pcn_intr, sc,
            device_xname(self));
        if (sc->sc_ih == NULL) {
                aprint_error_dev(self, "unable to establish interrupt");
                if (intrstr != NULL)
                        aprint_error(" at %s", intrstr);
                aprint_error("\n");
                return;
        }
        aprint_normal_dev(self, "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 pcn_control_data), PAGE_SIZE, 0, &seg, 1, &rseg,
             0)) != 0) {
                aprint_error_dev(self, "unable to allocate control data, "
                    "error = %d\n", error);
                goto fail_0;
        }

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

        if ((error = bus_dmamap_create(sc->sc_dmat,
             sizeof(struct pcn_control_data), 1,
             sizeof(struct pcn_control_data), 0, 0, &sc->sc_cddmamap)) != 0) {
                aprint_error_dev(self, "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 pcn_control_data), NULL,
             0)) != 0) {
                aprint_error_dev(self,
                    "unable to load control data DMA map, error = %d\n", error);
                goto fail_3;
        }

        /* Create the transmit buffer DMA maps. */
        for (i = 0; i < PCN_TXQUEUELEN; i++) {
                if ((error = bus_dmamap_create(sc->sc_dmat, MCLBYTES,
                     ntxsegs, MCLBYTES, 0, 0,
                     &sc->sc_txsoft[i].txs_dmamap)) != 0) {
                        aprint_error_dev(self,
                            "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 < PCN_NRXDESC; i++) {
                if ((error = bus_dmamap_create(sc->sc_dmat, MCLBYTES, 1,
                     MCLBYTES, 0, 0, &sc->sc_rxsoft[i].rxs_dmamap)) != 0) {
                        aprint_error_dev(self,
                            "unable to create rx DMA map %d, error = %d\n",
                            i, error);
                        goto fail_5;
                }
                sc->sc_rxsoft[i].rxs_mbuf = NULL;
        }

        /* Initialize our media structures. */
        (*sc->sc_variant->pcv_mediainit)(sc);

        /*
         * Initialize FIFO watermark info.
         */
        switch (sc->sc_variant->pcv_chipid) {
        case PARTID_Am79c970:
        case PARTID_Am79c970A:
                sc->sc_rcvfw_desc = pcn_79c970_rcvfw;
                sc->sc_xmtsp_desc = pcn_79c970_xmtsp;
                sc->sc_xmtfw_desc = pcn_79c970_xmtfw;
                break;

        default:
                sc->sc_rcvfw_desc = pcn_79c971_rcvfw;
                /*
                 * Read BCR25 to determine how much SRAM is
                 * on the board.  If > 0, then we the chip
                 * uses different Start Point thresholds.
                 *
                 * Note BCR25 and BCR26 are loaded from the
                 * EEPROM on RST, and unaffected by S_RESET,
                 * so we don't really have to worry about
                 * them except for this.
                 */
                reg = pcn_bcr_read(sc, LE_BCR25) & 0x00ff;
                if (reg != 0)
                        sc->sc_xmtsp_desc = pcn_79c971_xmtsp_sram;
                else
                        sc->sc_xmtsp_desc = pcn_79c971_xmtsp;
                sc->sc_xmtfw_desc = pcn_79c971_xmtfw;
                break;
        }

        /*
         * Set up defaults -- see the tables above for what these
         * values mean.
         *
         * XXX How should we tune RCVFW and XMTFW?
         */
        sc->sc_rcvfw = 1;       /* minimum for full-duplex */
        sc->sc_xmtsp = 1;
        sc->sc_xmtfw = 0;

        ifp = &sc->sc_ethercom.ec_if;
        strcpy(ifp->if_xname, device_xname(self));
        ifp->if_softc = sc;
        ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
        ifp->if_ioctl = pcn_ioctl;
        ifp->if_start = pcn_start;
        ifp->if_watchdog = pcn_watchdog;
        ifp->if_init = pcn_init;
        ifp->if_stop = pcn_stop;
        IFQ_SET_READY(&ifp->if_snd);

        /* Attach the interface. */
        if_attach(ifp);
        if_deferred_start_init(ifp, NULL);
        ether_ifattach(ifp, enaddr);
        rnd_attach_source(&sc->rnd_source, device_xname(self),
            RND_TYPE_NET, RND_FLAG_DEFAULT);

#ifdef PCN_EVENT_COUNTERS
        /* Attach event counters. */
        evcnt_attach_dynamic(&sc->sc_ev_txdstall, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "txdstall");
        evcnt_attach_dynamic(&sc->sc_ev_txintr, EVCNT_TYPE_INTR,
            NULL, device_xname(self), "txintr");
        evcnt_attach_dynamic(&sc->sc_ev_rxintr, EVCNT_TYPE_INTR,
            NULL, device_xname(self), "rxintr");
        evcnt_attach_dynamic(&sc->sc_ev_babl, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "babl");
        evcnt_attach_dynamic(&sc->sc_ev_miss, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "miss");
        evcnt_attach_dynamic(&sc->sc_ev_merr, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "merr");

        evcnt_attach_dynamic(&sc->sc_ev_txseg1, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "txseg1");
        evcnt_attach_dynamic(&sc->sc_ev_txseg2, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "txseg2");
        evcnt_attach_dynamic(&sc->sc_ev_txseg3, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "txseg3");
        evcnt_attach_dynamic(&sc->sc_ev_txseg4, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "txseg4");
        evcnt_attach_dynamic(&sc->sc_ev_txseg5, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "txseg5");
        evcnt_attach_dynamic(&sc->sc_ev_txsegmore, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "txsegmore");
        evcnt_attach_dynamic(&sc->sc_ev_txcopy, EVCNT_TYPE_MISC,
            NULL, device_xname(self), "txcopy");
#endif /* PCN_EVENT_COUNTERS */

        /*
         * Establish power handler with shutdown hook, to make sure
         * the interface is shutdown during reboot.
         */
        if (pmf_device_register1(self, NULL, NULL, pcn_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 < PCN_NRXDESC; i++) {
                if (sc->sc_rxsoft[i].rxs_dmamap != NULL)
                        bus_dmamap_destroy(sc->sc_dmat,
                            sc->sc_rxsoft[i].rxs_dmamap);
        }
 fail_4:
        for (i = 0; i < PCN_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_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 pcn_control_data));
 fail_1:
        bus_dmamem_free(sc->sc_dmat, &seg, rseg);
 fail_0:
        return;
}

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

        pcn_stop(&sc->sc_ethercom.ec_if, 1);
        /* explicitly reset the chip for some onboard one with lazy firmware */
        pcn_reset(sc);

        return true;
}

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

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

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

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

                txs = &sc->sc_txsoft[sc->sc_txsnext];
                dmamap = txs->txs_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) {
                        PCN_EVCNT_INCR(&sc->sc_ev_txcopy);
                        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_rx_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;
                        }
                }

                /*
                 * Ensure we have enough descriptors free to describe
                 * the packet.  Note, we always reserve one descriptor
                 * at the end of the ring as a termination point, to
                 * prevent wrap-around.
                 */
                if (dmamap->dm_nsegs > (sc->sc_txfree - 1)) {
                        /*
                         * Not enough free descriptors to transmit this
                         * packet.
                         */
                        bus_dmamap_unload(sc->sc_dmat, dmamap);
                        m_freem(m);
                        PCN_EVCNT_INCR(&sc->sc_ev_txdstall);
                        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);

#ifdef PCN_EVENT_COUNTERS
                switch (dmamap->dm_nsegs) {
                case 1:
                        PCN_EVCNT_INCR(&sc->sc_ev_txseg1);
                        break;
                case 2:
                        PCN_EVCNT_INCR(&sc->sc_ev_txseg2);
                        break;
                case 3:
                        PCN_EVCNT_INCR(&sc->sc_ev_txseg3);
                        break;
                case 4:
                        PCN_EVCNT_INCR(&sc->sc_ev_txseg4);
                        break;
                case 5:
                        PCN_EVCNT_INCR(&sc->sc_ev_txseg5);
                        break;
                default:
                        PCN_EVCNT_INCR(&sc->sc_ev_txsegmore);
                        break;
                }
#endif /* PCN_EVENT_COUNTERS */

                /*
                 * Initialize the transmit descriptors.
                 */
                if (sc->sc_swstyle == LE_B20_SSTYLE_PCNETPCI3) {
                        for (nexttx = sc->sc_txnext, seg = 0;
                             seg < dmamap->dm_nsegs;
                             seg++, nexttx = PCN_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].tmd0 = 0;
                                sc->sc_txdescs[nexttx].tmd2 =
                                    htole32(dmamap->dm_segs[seg].ds_addr);
                                sc->sc_txdescs[nexttx].tmd1 =
                                    htole32(LE_T1_ONES |
                                    (nexttx == sc->sc_txnext ? 0 : LE_T1_OWN) |
                                    (LE_BCNT(dmamap->dm_segs[seg].ds_len) &
                                     LE_T1_BCNT_MASK));
                                lasttx = nexttx;
                        }
                } else {
                        for (nexttx = sc->sc_txnext, seg = 0;
                             seg < dmamap->dm_nsegs;
                             seg++, nexttx = PCN_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].tmd0 =
                                    htole32(dmamap->dm_segs[seg].ds_addr);
                                sc->sc_txdescs[nexttx].tmd2 = 0;
                                sc->sc_txdescs[nexttx].tmd1 =
                                    htole32(LE_T1_ONES |
                                    (nexttx == sc->sc_txnext ? 0 : LE_T1_OWN) |
                                    (LE_BCNT(dmamap->dm_segs[seg].ds_len) &
                                     LE_T1_BCNT_MASK));
                                lasttx = nexttx;
                        }
                }

                KASSERT(lasttx != -1);
                /* Interrupt on the packet, if appropriate. */
                if ((sc->sc_txsnext & PCN_TXINTR_MASK) == 0)
                        sc->sc_txdescs[lasttx].tmd1 |= htole32(LE_T1_LTINT);

                /* Set `start of packet' and `end of packet' appropriately. */
                sc->sc_txdescs[lasttx].tmd1 |= htole32(LE_T1_ENP);
                sc->sc_txdescs[sc->sc_txnext].tmd1 |=
                    htole32(LE_T1_OWN | LE_T1_STP);

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

                /* Kick the transmitter. */
                pcn_csr_write(sc, LE_CSR0, LE_C0_INEA | LE_C0_TDMD);

                /*
                 * 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;

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

                sc->sc_txsfree--;
                sc->sc_txsnext = PCN_NEXTTXS(sc->sc_txsnext);

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

        if (sc->sc_txfree != ofree) {
                /* Set a watchdog timer in case the chip flakes out. */
                ifp->if_timer = 5;
        }
}

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

        /*
         * Since we're not interrupting every packet, sweep
         * up before we report an error.
         */
        pcn_txintr(sc);

        if (sc->sc_txfree != PCN_NTXDESC) {
                printf("%s: device timeout (txfree %d txsfree %d)\n",
                    device_xname(sc->sc_dev), sc->sc_txfree, sc->sc_txsfree);
                if_statinc(ifp, if_oerrors);

                /* Reset the interface. */
                (void) pcn_init(ifp);
        }

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

/*
 * pcn_ioctl:           [ifnet interface function]
 *
 *      Handle control requests from the operator.
 */
static int
pcn_ioctl(struct ifnet *ifp, u_long cmd, void *data)
{
        int s, error;

        s = splnet();

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

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

        splx(s);
        return error;
}

/*
 * pcn_intr:
 *
 *      Interrupt service routine.
 */
static int
pcn_intr(void *arg)
{
        struct pcn_softc *sc = arg;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        uint32_t csr0;
        int wantinit, handled = 0;

        for (wantinit = 0; wantinit == 0;) {
                csr0 = pcn_csr_read(sc, LE_CSR0);
                if ((csr0 & LE_C0_INTR) == 0)
                        break;

                rnd_add_uint32(&sc->rnd_source, csr0);

                /* ACK the bits and re-enable interrupts. */
                pcn_csr_write(sc, LE_CSR0, csr0 &
                    (LE_C0_INEA | LE_C0_BABL | LE_C0_MISS | LE_C0_MERR |
                        LE_C0_RINT | LE_C0_TINT | LE_C0_IDON));

                handled = 1;

                if (csr0 & LE_C0_RINT) {
                        PCN_EVCNT_INCR(&sc->sc_ev_rxintr);
                        wantinit = pcn_rxintr(sc);
                }

                if (csr0 & LE_C0_TINT) {
                        PCN_EVCNT_INCR(&sc->sc_ev_txintr);
                        pcn_txintr(sc);
                }

                if (csr0 & LE_C0_ERR) {
                        if (csr0 & LE_C0_BABL) {
                                PCN_EVCNT_INCR(&sc->sc_ev_babl);
                                if_statinc(ifp, if_oerrors);
                        }
                        if (csr0 & LE_C0_MISS) {
                                PCN_EVCNT_INCR(&sc->sc_ev_miss);
                                if_statinc(ifp, if_ierrors);
                        }
                        if (csr0 & LE_C0_MERR) {
                                PCN_EVCNT_INCR(&sc->sc_ev_merr);
                                printf("%s: memory error\n",
                                    device_xname(sc->sc_dev));
                                wantinit = 1;
                                break;
                        }
                }

                if ((csr0 & LE_C0_RXON) == 0) {
                        printf("%s: receiver disabled\n",
                            device_xname(sc->sc_dev));
                        if_statinc(ifp, if_ierrors);
                        wantinit = 1;
                }

                if ((csr0 & LE_C0_TXON) == 0) {
                        printf("%s: transmitter disabled\n",
                            device_xname(sc->sc_dev));
                        if_statinc(ifp, if_oerrors);
                        wantinit = 1;
                }
        }

        if (handled) {
                if (wantinit)
                        pcn_init(ifp);

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

        return handled;
}

/*
 * pcn_spnd:
 *
 *      Suspend the chip.
 */
static void
pcn_spnd(struct pcn_softc *sc)
{
        int i;

        pcn_csr_write(sc, LE_CSR5, sc->sc_csr5 | LE_C5_SPND);

        for (i = 0; i < 10000; i++) {
                if (pcn_csr_read(sc, LE_CSR5) & LE_C5_SPND)
                        return;
                delay(5);
        }

        printf("%s: WARNING: chip failed to enter suspended state\n",
            device_xname(sc->sc_dev));
}

/*
 * pcn_txintr:
 *
 *      Helper; handle transmit interrupts.
 */
static void
pcn_txintr(struct pcn_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct pcn_txsoft *txs;
        uint32_t tmd1, tmd2, tmd;
        int i, j;

        /*
         * Go through our Tx list and free mbufs for those
         * frames which have been transmitted.
         */
        for (i = sc->sc_txsdirty; sc->sc_txsfree != PCN_TXQUEUELEN;
             i = PCN_NEXTTXS(i), sc->sc_txsfree++) {
                txs = &sc->sc_txsoft[i];

                PCN_CDTXSYNC(sc, txs->txs_firstdesc, txs->txs_dmamap->dm_nsegs,
                    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);

                tmd1 = le32toh(sc->sc_txdescs[txs->txs_lastdesc].tmd1);
                if (tmd1 & LE_T1_OWN)
                        break;

                /*
                 * Slightly annoying -- we have to loop through the
                 * descriptors we've used looking for ERR, since it
                 * can appear on any descriptor in the chain.
                 */
                for (j = txs->txs_firstdesc;; j = PCN_NEXTTX(j)) {
                        tmd = le32toh(sc->sc_txdescs[j].tmd1);
                        if (tmd & LE_T1_ERR) {
                                if_statinc(ifp, if_oerrors);
                                if (sc->sc_swstyle == LE_B20_SSTYLE_PCNETPCI3)
                                        tmd2 = le32toh(sc->sc_txdescs[j].tmd0);
                                else
                                        tmd2 = le32toh(sc->sc_txdescs[j].tmd2);
                                if (tmd2 & LE_T2_UFLO) {
                                        if (sc->sc_xmtsp < LE_C80_XMTSP_MAX) {
                                                sc->sc_xmtsp++;
                                                printf("%s: transmit "
                                                    "underrun; new threshold: "
                                                    "%s\n",
                                                    device_xname(sc->sc_dev),
                                                    sc->sc_xmtsp_desc[
                                                    sc->sc_xmtsp]);
                                                pcn_spnd(sc);
                                                pcn_csr_write(sc, LE_CSR80,
                                                    LE_C80_RCVFW(sc->sc_rcvfw) |
                                                    LE_C80_XMTSP(sc->sc_xmtsp) |
                                                    LE_C80_XMTFW(sc->sc_xmtfw));
                                                pcn_csr_write(sc, LE_CSR5,
                                                    sc->sc_csr5);
                                        } else {
                                                printf("%s: transmit "
                                                    "underrun\n",
                                                    device_xname(sc->sc_dev));
                                        }
                                } else if (tmd2 & LE_T2_BUFF) {
                                        printf("%s: transmit buffer error\n",
                                            device_xname(sc->sc_dev));
                                }
                                if (tmd2 & LE_T2_LCOL)
                                        if_statinc(ifp, if_collisions);
                                if (tmd2 & LE_T2_RTRY)
                                        if_statadd(ifp, if_collisions, 16);
                                goto next_packet;
                        }
                        if (j == txs->txs_lastdesc)
                                break;
                }
                if (tmd1 & LE_T1_ONE)
                        if_statinc(ifp, if_collisions);
                else if (tmd & LE_T1_MORE) {
                        /* Real number is unknown. */
                        if_statadd(ifp, if_collisions, 2);
                }
                if_statinc(ifp, if_opackets);
 next_packet:
                sc->sc_txfree += txs->txs_dmamap->dm_nsegs;
                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;
        }

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

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

/*
 * pcn_rxintr:
 *
 *      Helper; handle receive interrupts.
 */
static int
pcn_rxintr(struct pcn_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct pcn_rxsoft *rxs;
        struct mbuf *m;
        uint32_t rmd1;
        int i, len;

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

                PCN_CDRXSYNC(sc, i,
                    BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);

                rmd1 = le32toh(sc->sc_rxdescs[i].rmd1);

                if (rmd1 & LE_R1_OWN)
                        break;

                /*
                 * Check for errors and make sure the packet fit into
                 * a single buffer.  We have structured this block of
                 * code the way it is in order to compress it into
                 * one test in the common case (no error).
                 */
                if (__predict_false((rmd1 & (LE_R1_STP | LE_R1_ENP |LE_R1_ERR))
                    != (LE_R1_STP | LE_R1_ENP))) {
                        /* Make sure the packet is in a single buffer. */
                        if ((rmd1 & (LE_R1_STP | LE_R1_ENP)) !=
                            (LE_R1_STP | LE_R1_ENP)) {
                                printf("%s: packet spilled into next buffer\n",
                                    device_xname(sc->sc_dev));
                                return 1;       /* pcn_intr() will re-init */
                        }

                        /*
                         * If the packet had an error, simple recycle the
                         * buffer.
                         */
                        if (rmd1 & LE_R1_ERR) {
                                if_statinc(ifp, if_ierrors);
                                /*
                                 * If we got an overflow error, chances
                                 * are there will be a CRC error.  In
                                 * this case, just print the overflow
                                 * error, and skip the others.
                                 */
                                if (rmd1 & LE_R1_OFLO)
                                        printf("%s: overflow error\n",
                                            device_xname(sc->sc_dev));
                                else {
#define PRINTIT(x, str)                                                 \
                                        if (rmd1 & (x))                 \
                                                printf("%s: %s\n",      \
                                                    device_xname(sc->sc_dev), \
                                                    str);
                                        PRINTIT(LE_R1_FRAM, "framing error");
                                        PRINTIT(LE_R1_CRC, "CRC error");
                                        PRINTIT(LE_R1_BUFF, "buffer error");
                                }
#undef PRINTIT
                                PCN_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.
                 */
                if (sc->sc_swstyle == LE_B20_SSTYLE_PCNETPCI3)
                        len = le32toh(sc->sc_rxdescs[i].rmd0) & LE_R1_BCNT_MASK;
                else
                        len = le32toh(sc->sc_rxdescs[i].rmd2) & LE_R1_BCNT_MASK;

                /*
                 * The LANCE family includes the CRC with every packet;
                 * trim it off here.
                 */
                len -= ETHER_CRC_LEN;

                /*
                 * 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 (pcn_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(rxs->rxs_mbuf, void *), len);
                        PCN_INIT_RXDESC(sc, i);
                        bus_dmamap_sync(sc->sc_dmat, rxs->rxs_dmamap, 0,
                            rxs->rxs_dmamap->dm_mapsize,
                            BUS_DMASYNC_PREREAD);
                } else {
                        m = rxs->rxs_mbuf;
                        if (pcn_add_rxbuf(sc, i) != 0) {
 dropit:
                                if_statinc(ifp, if_ierrors);
                                PCN_INIT_RXDESC(sc, i);
                                bus_dmamap_sync(sc->sc_dmat,
                                    rxs->rxs_dmamap, 0,
                                    rxs->rxs_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;
        return 0;
}

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

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

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

/*
 * pcn_reset:
 *
 *      Perform a soft reset on the PCnet-PCI.
 */
static void
pcn_reset(struct pcn_softc *sc)
{

        /*
         * The PCnet-PCI chip is reset by reading from the
         * RESET register.  Note that while the NE2100 LANCE
         * boards require a write after the read, the PCnet-PCI
         * chips do not require this.
         *
         * Since we don't know if we're in 16-bit or 32-bit
         * mode right now, issue both (it's safe) in the
         * hopes that one will succeed.
         */
        (void) bus_space_read_2(sc->sc_st, sc->sc_sh, PCN16_RESET);
        (void) bus_space_read_4(sc->sc_st, sc->sc_sh, PCN32_RESET);

        /* Wait 1ms for it to finish. */
        delay(1000);

        /*
         * Select 32-bit I/O mode by issuing a 32-bit write to the
         * RDP.  Since the RAP is 0 after a reset, writing a 0
         * to RDP is safe (since it simply clears CSR0).
         */
        bus_space_write_4(sc->sc_st, sc->sc_sh, PCN32_RDP, 0);
}

/*
 * pcn_init:            [ifnet interface function]
 *
 *      Initialize the interface.  Must be called at splnet().
 */
static int
pcn_init(struct ifnet *ifp)
{
        struct pcn_softc *sc = ifp->if_softc;
        struct pcn_rxsoft *rxs;
        const uint8_t *enaddr = CLLADDR(ifp->if_sadl);
        int i, error = 0;
        uint32_t reg;

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

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

        /*
         * On the Am79c970, select SSTYLE 2, and SSTYLE 3 on everything
         * else.
         *
         * XXX It'd be really nice to use SSTYLE 2 on all the chips,
         * because the structure layout is compatible with ILACC,
         * but the burst mode is only available in SSTYLE 3, and
         * burst mode should provide some performance enhancement.
         */
        if (sc->sc_variant->pcv_chipid == PARTID_Am79c970)
                sc->sc_swstyle = LE_B20_SSTYLE_PCNETPCI2;
        else
                sc->sc_swstyle = LE_B20_SSTYLE_PCNETPCI3;
        pcn_bcr_write(sc, LE_BCR20, sc->sc_swstyle);

        /* Initialize the transmit descriptor ring. */
        memset(sc->sc_txdescs, 0, sizeof(sc->sc_txdescs));
        PCN_CDTXSYNC(sc, 0, PCN_NTXDESC,
            BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
        sc->sc_txfree = PCN_NTXDESC;
        sc->sc_txnext = 0;

        /* Initialize the transmit job descriptors. */
        for (i = 0; i < PCN_TXQUEUELEN; i++)
                sc->sc_txsoft[i].txs_mbuf = NULL;
        sc->sc_txsfree = PCN_TXQUEUELEN;
        sc->sc_txsnext = 0;
        sc->sc_txsdirty = 0;

        /*
         * Initialize the receive descriptor and receive job
         * descriptor rings.
         */
        for (i = 0; i < PCN_NRXDESC; i++) {
                rxs = &sc->sc_rxsoft[i];
                if (rxs->rxs_mbuf == NULL) {
                        if ((error = pcn_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.
                                 */
                                pcn_rxdrain(sc);
                                goto out;
                        }
                } else
                        PCN_INIT_RXDESC(sc, i);
        }
        sc->sc_rxptr = 0;

        /* Initialize MODE for the initialization block. */
        sc->sc_mode = 0;
        if (ifp->if_flags & IFF_PROMISC)
                sc->sc_mode |= LE_C15_PROM;
        if ((ifp->if_flags & IFF_BROADCAST) == 0)
                sc->sc_mode |= LE_C15_DRCVBC;

        /*
         * If we have MII, simply select MII in the MODE register,
         * and clear ASEL.  Otherwise, let ASEL stand (for now),
         * and leave PORTSEL alone (it is ignored with ASEL is set).
         */
        if (sc->sc_flags & PCN_F_HAS_MII) {
                pcn_bcr_write(sc, LE_BCR2,
                    pcn_bcr_read(sc, LE_BCR2) & ~LE_B2_ASEL);
                sc->sc_mode |= LE_C15_PORTSEL(PORTSEL_MII);

                /*
                 * Disable MII auto-negotiation.  We handle that in
                 * our own MII layer.
                 */
                pcn_bcr_write(sc, LE_BCR32,
                    pcn_bcr_read(sc, LE_BCR32) | LE_B32_DANAS);
        }

        /*
         * Set the Tx and Rx descriptor ring addresses in the init
         * block, the TLEN and RLEN other fields of the init block
         * MODE register.
         */
        sc->sc_initblock.init_rdra = htole32(PCN_CDRXADDR(sc, 0));
        sc->sc_initblock.init_tdra = htole32(PCN_CDTXADDR(sc, 0));
        sc->sc_initblock.init_mode = htole32(sc->sc_mode |
            (((uint32_t)ffs(PCN_NTXDESC) - 1) << 28) |
            ((ffs(PCN_NRXDESC) - 1) << 20));

        /* Set the station address in the init block. */
        sc->sc_initblock.init_padr[0] = htole32(enaddr[0] |
            (enaddr[1] << 8) | (enaddr[2] << 16) |
            ((uint32_t)enaddr[3] << 24));
        sc->sc_initblock.init_padr[1] = htole32(enaddr[4] |
            (enaddr[5] << 8));

        /* Set the multicast filter in the init block. */
        pcn_set_filter(sc);

        /* Initialize CSR3. */
        pcn_csr_write(sc, LE_CSR3, LE_C3_MISSM | LE_C3_IDONM | LE_C3_DXSUFLO);

        /* Initialize CSR4. */
        pcn_csr_write(sc, LE_CSR4, LE_C4_DMAPLUS | LE_C4_APAD_XMT |
            LE_C4_MFCOM | LE_C4_RCVCCOM | LE_C4_TXSTRTM);

        /* Initialize CSR5. */
        sc->sc_csr5 = LE_C5_LTINTEN | LE_C5_SINTE;
        pcn_csr_write(sc, LE_CSR5, sc->sc_csr5);

        /*
         * If we have an Am79c971 or greater, initialize CSR7.
         *
         * XXX Might be nice to use the MII auto-poll interrupt someday.
         */
        switch (sc->sc_variant->pcv_chipid) {
        case PARTID_Am79c970:
        case PARTID_Am79c970A:
                /* Not available on these chips. */
                break;

        default:
                pcn_csr_write(sc, LE_CSR7, LE_C7_FASTSPNDE);
                break;
        }

        /*
         * On the Am79c970A and greater, initialize BCR18 to
         * enable burst mode.
         *
         * Also enable the "no underflow" option on the Am79c971 and
         * higher, which prevents the chip from generating transmit
         * underflows, yet sill provides decent performance.  Note if
         * chip is not connected to external SRAM, then we still have
         * to handle underflow errors (the NOUFLO bit is ignored in
         * that case).
         */
        reg = pcn_bcr_read(sc, LE_BCR18);
        switch (sc->sc_variant->pcv_chipid) {
        case PARTID_Am79c970:
                break;

        case PARTID_Am79c970A:
                reg |= LE_B18_BREADE | LE_B18_BWRITE;
                break;

        default:
                reg |= LE_B18_BREADE | LE_B18_BWRITE | LE_B18_NOUFLO;
                break;
        }
        pcn_bcr_write(sc, LE_BCR18, reg);

        /*
         * Initialize CSR80 (FIFO thresholds for Tx and Rx).
         */
        pcn_csr_write(sc, LE_CSR80, LE_C80_RCVFW(sc->sc_rcvfw) |
            LE_C80_XMTSP(sc->sc_xmtsp) | LE_C80_XMTFW(sc->sc_xmtfw));

        /*
         * Send the init block to the chip, and wait for it
         * to be processed.
         */
        PCN_CDINITSYNC(sc, BUS_DMASYNC_PREWRITE);
        pcn_csr_write(sc, LE_CSR1, PCN_CDINITADDR(sc) & 0xffff);
        pcn_csr_write(sc, LE_CSR2, (PCN_CDINITADDR(sc) >> 16) & 0xffff);
        pcn_csr_write(sc, LE_CSR0, LE_C0_INIT);
        delay(100);
        for (i = 0; i < 10000; i++) {
                if (pcn_csr_read(sc, LE_CSR0) & LE_C0_IDON)
                        break;
                delay(10);
        }
        PCN_CDINITSYNC(sc, BUS_DMASYNC_POSTWRITE);
        if (i == 10000) {
                printf("%s: timeout processing init block\n",
                    device_xname(sc->sc_dev));
                error = EIO;
                goto out;
        }

        /* Set the media. */
        if ((error = mii_ifmedia_change(&sc->sc_mii)) != 0)
                goto out;

        /* Enable interrupts and external activity (and ACK IDON). */
        pcn_csr_write(sc, LE_CSR0, LE_C0_INEA | LE_C0_STRT | LE_C0_IDON);

        if (sc->sc_flags & PCN_F_HAS_MII) {
                /* 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;
}

/*
 * pcn_rxdrain:
 *
 *      Drain the receive queue.
 */
static void
pcn_rxdrain(struct pcn_softc *sc)
{
        struct pcn_rxsoft *rxs;
        int i;

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

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

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

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

        /* Stop the chip. */
        pcn_csr_write(sc, LE_CSR0, LE_C0_STOP);

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

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

        if (disable)
                pcn_rxdrain(sc);
}

/*
 * pcn_add_rxbuf:
 *
 *      Add a receive buffer to the indicated descriptor.
 */
static int
pcn_add_rxbuf(struct pcn_softc *sc, int idx)
{
        struct pcn_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",
                    device_xname(sc->sc_dev), idx, error);
                panic("pcn_add_rxbuf");
        }

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

        PCN_INIT_RXDESC(sc, idx);

        return 0;
}

/*
 * pcn_set_filter:
 *
 *      Set up the receive filter.
 */
static void
pcn_set_filter(struct pcn_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;

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

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

        sc->sc_initblock.init_ladrf[0] =
            sc->sc_initblock.init_ladrf[1] =
            sc->sc_initblock.init_ladrf[2] =
            sc->sc_initblock.init_ladrf[3] = 0;

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

                crc = ether_crc32_le(enm->enm_addrlo, ETHER_ADDR_LEN);

                /* Just want the 6 most significant bits. */
                crc >>= 26;

                /* Set the corresponding bit in the filter. */
                sc->sc_initblock.init_ladrf[crc >> 4] |=
                    htole16(1 << (crc & 0xf));

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

        ifp->if_flags &= ~IFF_ALLMULTI;
        return;

 allmulti:
        ifp->if_flags |= IFF_ALLMULTI;
        sc->sc_initblock.init_ladrf[0] =
            sc->sc_initblock.init_ladrf[1] =
            sc->sc_initblock.init_ladrf[2] =
            sc->sc_initblock.init_ladrf[3] = 0xffff;
}

/*
 * pcn_79c970_mediainit:
 *
 *      Initialize media for the Am79c970.
 */
static void
pcn_79c970_mediainit(struct pcn_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct mii_data * const mii = &sc->sc_mii;
        const char *sep = "";

        mii->mii_ifp = ifp;

        ifmedia_init(&mii->mii_media, IFM_IMASK, pcn_79c970_mediachange,
            pcn_79c970_mediastatus);

#define ADD(str, m, d)                                                  \
do {                                                                    \
        aprint_normal("%s%s", sep, str);                                \
        ifmedia_add(&mii->mii_media, IFM_ETHER | (m), (d), NULL);       \
        sep = ", ";                                                     \
} while (/*CONSTCOND*/0)

        aprint_normal("%s: ", device_xname(sc->sc_dev));
        ADD("10base5", IFM_10_5, PORTSEL_AUI);
        if (sc->sc_variant->pcv_chipid == PARTID_Am79c970A)
                ADD("10base5-FDX", IFM_10_5 | IFM_FDX, PORTSEL_AUI);
        ADD("10baseT", IFM_10_T, PORTSEL_10T);
        if (sc->sc_variant->pcv_chipid == PARTID_Am79c970A)
                ADD("10baseT-FDX", IFM_10_T | IFM_FDX, PORTSEL_10T);
        ADD("auto", IFM_AUTO, 0);
        if (sc->sc_variant->pcv_chipid == PARTID_Am79c970A)
                ADD("auto-FDX", IFM_AUTO | IFM_FDX, 0);
        aprint_normal("\n");

        ifmedia_set(&mii->mii_media, IFM_ETHER | IFM_AUTO);
}

/*
 * pcn_79c970_mediastatus:      [ifmedia interface function]
 *
 *      Get the current interface media status (Am79c970 version).
 */
static void
pcn_79c970_mediastatus(struct ifnet *ifp, struct ifmediareq *ifmr)
{
        struct pcn_softc *sc = ifp->if_softc;

        /*
         * The currently selected media is always the active media.
         * Note: We have no way to determine what media the AUTO
         * process picked.
         */
        ifmr->ifm_active = sc->sc_mii.mii_media.ifm_media;
}

/*
 * pcn_79c970_mediachange:      [ifmedia interface function]
 *
 *      Set hardware to newly-selected media (Am79c970 version).
 */
static int
pcn_79c970_mediachange(struct ifnet *ifp)
{
        struct pcn_softc *sc = ifp->if_softc;
        uint32_t reg;

        if (IFM_SUBTYPE(sc->sc_mii.mii_media.ifm_media) == IFM_AUTO) {
                /*
                 * CSR15:PORTSEL doesn't matter.  Just set BCR2:ASEL.
                 */
                reg = pcn_bcr_read(sc, LE_BCR2);
                reg |= LE_B2_ASEL;
                pcn_bcr_write(sc, LE_BCR2, reg);
        } else {
                /*
                 * Clear BCR2:ASEL and set the new CSR15:PORTSEL value.
                 */
                reg = pcn_bcr_read(sc, LE_BCR2);
                reg &= ~LE_B2_ASEL;
                pcn_bcr_write(sc, LE_BCR2, reg);

                reg = pcn_csr_read(sc, LE_CSR15);
                reg = (reg & ~LE_C15_PORTSEL(PORTSEL_MASK)) |
                    LE_C15_PORTSEL(sc->sc_mii.mii_media.ifm_cur->ifm_data);
                pcn_csr_write(sc, LE_CSR15, reg);
        }

        if ((sc->sc_mii.mii_media.ifm_media & IFM_FDX) != 0) {
                reg = LE_B9_FDEN;
                if (IFM_SUBTYPE(sc->sc_mii.mii_media.ifm_media) == IFM_10_5)
                        reg |= LE_B9_AUIFD;
                pcn_bcr_write(sc, LE_BCR9, reg);
        } else
                pcn_bcr_write(sc, LE_BCR9, 0);

        return 0;
}

/*
 * pcn_79c971_mediainit:
 *
 *      Initialize media for the Am79c971.
 */
static void
pcn_79c971_mediainit(struct pcn_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct mii_data * const mii = &sc->sc_mii;

        /* We have MII. */
        sc->sc_flags |= PCN_F_HAS_MII;

        /*
         * The built-in 10BASE-T interface is mapped to the MII
         * on the PCNet-FAST.  Unfortunately, there's no EEPROM
         * word that tells us which PHY to use.
         * This driver used to ignore all but the first PHY to
         * answer, but this code was removed to support multiple
         * external PHYs. As the default instance will be the first
         * one to answer, no harm is done by letting the possibly
         * non-connected internal PHY show up.
         */

        /* Initialize our media structures and probe the MII. */
        mii->mii_ifp = ifp;
        mii->mii_readreg = pcn_mii_readreg;
        mii->mii_writereg = pcn_mii_writereg;
        mii->mii_statchg = pcn_mii_statchg;

        sc->sc_ethercom.ec_mii = mii;
        ifmedia_init(&mii->mii_media, 0, 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) {
                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);
}

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

        pcn_bcr_write(sc, LE_BCR33, reg | (phy << PHYAD_SHIFT));
        *val = pcn_bcr_read(sc, LE_BCR34) & LE_B34_MIIMD;
        if (*val == 0xffff)
                return -1;

        return 0;
}

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

        pcn_bcr_write(sc, LE_BCR33, reg | (phy << PHYAD_SHIFT));
        pcn_bcr_write(sc, LE_BCR34, val);

        return 0;
}

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

        if ((sc->sc_mii.mii_media_active & IFM_FDX) != 0)
                pcn_bcr_write(sc, LE_BCR9, LE_B9_FDEN);
        else
                pcn_bcr_write(sc, LE_BCR9, 0);
}