source: rtems-libbsd/freebsd/sys/dev/ffec/if_ffec.c @ 95b102f

#include <machine/rtems-bsd-kernel-space.h>

/*-
 * Copyright (c) 2013 Ian Lepore <ian@freebsd.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * Driver for Freescale Fast Ethernet Controller, found on imx-series SoCs among
 * others.  Also works for the ENET Gigibit controller found on imx6 and imx28,
 * but the driver doesn't currently use any of the ENET advanced features other
 * than enabling gigabit.
 *
 * The interface name 'fec' is already taken by netgraph's Fast Etherchannel
 * (netgraph/ng_fec.c), so we use 'ffec'.
 *
 * Requires an FDT entry with at least these properties:
 *   fec: ethernet@02188000 {
 *      compatible = "fsl,imxNN-fec";
 *      reg = <0x02188000 0x4000>;
 *      interrupts = <150 151>;
 *      phy-mode = "rgmii";
 *      phy-disable-preamble; // optional
 *   };
 * The second interrupt number is for IEEE-1588, and is not currently used; it
 * need not be present.  phy-mode must be one of: "mii", "rmii", "rgmii".
 * There is also an optional property, phy-disable-preamble, which if present
 * will disable the preamble bits, cutting the size of each mdio transaction
 * (and thus the busy-wait time) in half.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/endian.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/rman.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/sysctl.h>

#include <machine/bus.h>

#include <net/bpf.h>
#include <net/if.h>
#include <net/ethernet.h>
#include <net/if_dl.h>
#include <net/if_media.h>
#include <net/if_types.h>
#include <net/if_var.h>
#include <net/if_vlan_var.h>

#include <dev/ffec/if_ffecreg.h>
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#include <dev/mii/mii.h>
#include <dev/mii/miivar.h>
#include <rtems/bsd/local/miibus_if.h>

/*
 * There are small differences in the hardware on various SoCs.  Not every SoC
 * we support has its own FECTYPE; most work as GENERIC and only the ones that
 * need different handling get their own entry.  In addition to the types in
 * this list, there are some flags below that can be ORed into the upper bits.
 */
enum {
        FECTYPE_NONE,
        FECTYPE_GENERIC,
        FECTYPE_IMX53,
        FECTYPE_IMX6,
        FECTYPE_MVF,
};

/*
 * Flags that describe general differences between the FEC hardware in various
 * SoCs.  These are ORed into the FECTYPE enum values.
 */
#define FECTYPE_MASK            0x0000ffff
#define FECFLAG_GBE             (0x0001 << 16)

/*
 * Table of supported FDT compat strings and their associated FECTYPE values.
 */
static struct ofw_compat_data compat_data[] = {
        {"fsl,imx51-fec",       FECTYPE_GENERIC},
        {"fsl,imx53-fec",       FECTYPE_IMX53},
        {"fsl,imx6q-fec",       FECTYPE_IMX6 | FECFLAG_GBE},
        {"fsl,mvf600-fec",      FECTYPE_MVF},
        {"fsl,mvf-fec",         FECTYPE_MVF},
        {NULL,                  FECTYPE_NONE},
};

/*
 * Driver data and defines.
 */
#define RX_DESC_COUNT   64
#define RX_DESC_SIZE    (sizeof(struct ffec_hwdesc) * RX_DESC_COUNT)
#define TX_DESC_COUNT   64
#define TX_DESC_SIZE    (sizeof(struct ffec_hwdesc) * TX_DESC_COUNT)

#define WATCHDOG_TIMEOUT_SECS   5
#define STATS_HARVEST_INTERVAL  3

struct ffec_bufmap {
        struct mbuf     *mbuf;
        bus_dmamap_t    map;
};

enum {
        PHY_CONN_UNKNOWN,
        PHY_CONN_MII,
        PHY_CONN_RMII,
        PHY_CONN_RGMII
};

struct ffec_softc {
        device_t                dev;
        device_t                miibus;
        struct mii_data *       mii_softc;
        struct ifnet            *ifp;
        int                     if_flags;
        struct mtx              mtx;
        struct resource         *irq_res;
        struct resource         *mem_res;
        void *                  intr_cookie;
        struct callout          ffec_callout;
        uint8_t                 phy_conn_type;
        uint8_t                 fectype;
        boolean_t               link_is_up;
        boolean_t               is_attached;
        boolean_t               is_detaching;
        int                     tx_watchdog_count;
        int                     stats_harvest_count;

        bus_dma_tag_t           rxdesc_tag;
        bus_dmamap_t            rxdesc_map;
        struct ffec_hwdesc      *rxdesc_ring;
        bus_addr_t              rxdesc_ring_paddr;
        bus_dma_tag_t           rxbuf_tag;
        struct ffec_bufmap      rxbuf_map[RX_DESC_COUNT];
        uint32_t                rx_idx;

        bus_dma_tag_t           txdesc_tag;
        bus_dmamap_t            txdesc_map;
        struct ffec_hwdesc      *txdesc_ring;
        bus_addr_t              txdesc_ring_paddr;
        bus_dma_tag_t           txbuf_tag;
        struct ffec_bufmap      txbuf_map[TX_DESC_COUNT];
        uint32_t                tx_idx_head;
        uint32_t                tx_idx_tail;
        int                     txcount;
};

#define FFEC_LOCK(sc)                   mtx_lock(&(sc)->mtx)
#define FFEC_UNLOCK(sc)                 mtx_unlock(&(sc)->mtx)
#define FFEC_LOCK_INIT(sc)              mtx_init(&(sc)->mtx, \
            device_get_nameunit((sc)->dev), MTX_NETWORK_LOCK, MTX_DEF)
#define FFEC_LOCK_DESTROY(sc)           mtx_destroy(&(sc)->mtx);
#define FFEC_ASSERT_LOCKED(sc)          mtx_assert(&(sc)->mtx, MA_OWNED);
#define FFEC_ASSERT_UNLOCKED(sc)        mtx_assert(&(sc)->mtx, MA_NOTOWNED);

static void ffec_init_locked(struct ffec_softc *sc);
static void ffec_stop_locked(struct ffec_softc *sc);
static void ffec_txstart_locked(struct ffec_softc *sc);
static void ffec_txfinish_locked(struct ffec_softc *sc);

static inline uint16_t
RD2(struct ffec_softc *sc, bus_size_t off)
{

        return (bus_read_2(sc->mem_res, off));
}

static inline void
WR2(struct ffec_softc *sc, bus_size_t off, uint16_t val)
{

        bus_write_2(sc->mem_res, off, val);
}

static inline uint32_t
RD4(struct ffec_softc *sc, bus_size_t off)
{

        return (bus_read_4(sc->mem_res, off));
}

static inline void
WR4(struct ffec_softc *sc, bus_size_t off, uint32_t val)
{

        bus_write_4(sc->mem_res, off, val);
}

static inline uint32_t
next_rxidx(struct ffec_softc *sc, uint32_t curidx)
{

        return ((curidx == RX_DESC_COUNT - 1) ? 0 : curidx + 1);
}

static inline uint32_t
next_txidx(struct ffec_softc *sc, uint32_t curidx)
{

        return ((curidx == TX_DESC_COUNT - 1) ? 0 : curidx + 1);
}

static void
ffec_get1paddr(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
{

        if (error != 0)
                return;
        *(bus_addr_t *)arg = segs[0].ds_addr;
}

static void
ffec_miigasket_setup(struct ffec_softc *sc)
{
        uint32_t ifmode;

        /*
         * We only need the gasket for MII and RMII connections on certain SoCs.
         */

        switch (sc->fectype & FECTYPE_MASK)
        {
        case FECTYPE_IMX53:
                break;
        default:
                return;
        }

        switch (sc->phy_conn_type)
        {
        case PHY_CONN_MII:
                ifmode = 0;
                break;
        case PHY_CONN_RMII:
                ifmode = FEC_MIIGSK_CFGR_IF_MODE_RMII;
                break;
        default:
                return;
        }

        /*
         * Disable the gasket, configure for either MII or RMII, then enable.
         */

        WR2(sc, FEC_MIIGSK_ENR, 0);
        while (RD2(sc, FEC_MIIGSK_ENR) & FEC_MIIGSK_ENR_READY)
                continue;

        WR2(sc, FEC_MIIGSK_CFGR, ifmode);

        WR2(sc, FEC_MIIGSK_ENR, FEC_MIIGSK_ENR_EN);
        while (!(RD2(sc, FEC_MIIGSK_ENR) & FEC_MIIGSK_ENR_READY))
                continue;
}

static boolean_t
ffec_miibus_iowait(struct ffec_softc *sc)
{
        uint32_t timeout;

        for (timeout = 10000; timeout != 0; --timeout)
                if (RD4(sc, FEC_IER_REG) & FEC_IER_MII)
                        return (true);

        return (false);
}

static int
ffec_miibus_readreg(device_t dev, int phy, int reg)
{
        struct ffec_softc *sc;
        int val;

        sc = device_get_softc(dev);

        WR4(sc, FEC_IER_REG, FEC_IER_MII);

        WR4(sc, FEC_MMFR_REG, FEC_MMFR_OP_READ |
            FEC_MMFR_ST_VALUE | FEC_MMFR_TA_VALUE |
            ((phy << FEC_MMFR_PA_SHIFT) & FEC_MMFR_PA_MASK) |
            ((reg << FEC_MMFR_RA_SHIFT) & FEC_MMFR_RA_MASK));

        if (!ffec_miibus_iowait(sc)) {
                device_printf(dev, "timeout waiting for mii read\n");
                return (-1); /* All-ones is a symptom of bad mdio. */
        }

        val = RD4(sc, FEC_MMFR_REG) & FEC_MMFR_DATA_MASK;

        return (val);
}

static int
ffec_miibus_writereg(device_t dev, int phy, int reg, int val)
{
        struct ffec_softc *sc;

        sc = device_get_softc(dev);

        WR4(sc, FEC_IER_REG, FEC_IER_MII);

        WR4(sc, FEC_MMFR_REG, FEC_MMFR_OP_WRITE |
            FEC_MMFR_ST_VALUE | FEC_MMFR_TA_VALUE |
            ((phy << FEC_MMFR_PA_SHIFT) & FEC_MMFR_PA_MASK) |
            ((reg << FEC_MMFR_RA_SHIFT) & FEC_MMFR_RA_MASK) |
            (val & FEC_MMFR_DATA_MASK));

        if (!ffec_miibus_iowait(sc)) {
                device_printf(dev, "timeout waiting for mii write\n");
                return (-1);
        }

        return (0);
}

static void
ffec_miibus_statchg(device_t dev)
{
        struct ffec_softc *sc;
        struct mii_data *mii;
        uint32_t ecr, rcr, tcr;

        /*
         * Called by the MII bus driver when the PHY establishes link to set the
         * MAC interface registers.
         */

        sc = device_get_softc(dev);

        FFEC_ASSERT_LOCKED(sc);

        mii = sc->mii_softc;

        if (mii->mii_media_status & IFM_ACTIVE)
                sc->link_is_up = true;
        else
                sc->link_is_up = false;

        ecr = RD4(sc, FEC_ECR_REG) & ~FEC_ECR_SPEED;
        rcr = RD4(sc, FEC_RCR_REG) & ~(FEC_RCR_RMII_10T | FEC_RCR_RMII_MODE |
            FEC_RCR_RGMII_EN | FEC_RCR_DRT | FEC_RCR_FCE);
        tcr = RD4(sc, FEC_TCR_REG) & ~FEC_TCR_FDEN;

        rcr |= FEC_RCR_MII_MODE; /* Must always be on even for R[G]MII. */
        switch (sc->phy_conn_type) {
        case PHY_CONN_MII:
                break;
        case PHY_CONN_RMII:
                rcr |= FEC_RCR_RMII_MODE;
                break;
        case PHY_CONN_RGMII:
                rcr |= FEC_RCR_RGMII_EN;
                break;
        }

        switch (IFM_SUBTYPE(mii->mii_media_active)) {
        case IFM_1000_T:
        case IFM_1000_SX:
                ecr |= FEC_ECR_SPEED;
                break;
        case IFM_100_TX:
                /* Not-FEC_ECR_SPEED + not-FEC_RCR_RMII_10T means 100TX */
                break;
        case IFM_10_T:
                rcr |= FEC_RCR_RMII_10T;
                break;
        case IFM_NONE:
                sc->link_is_up = false;
                return;
        default:
                sc->link_is_up = false;
                device_printf(dev, "Unsupported media %u\n",
                    IFM_SUBTYPE(mii->mii_media_active));
                return;
        }

        if ((IFM_OPTIONS(mii->mii_media_active) & IFM_FDX) != 0)
                tcr |= FEC_TCR_FDEN;
        else
                rcr |= FEC_RCR_DRT;

        if ((IFM_OPTIONS(mii->mii_media_active) & IFM_FLOW) != 0)
                rcr |= FEC_RCR_FCE;

        WR4(sc, FEC_RCR_REG, rcr);
        WR4(sc, FEC_TCR_REG, tcr);
        WR4(sc, FEC_ECR_REG, ecr);
}

static void
ffec_media_status(struct ifnet * ifp, struct ifmediareq *ifmr)
{
        struct ffec_softc *sc;
        struct mii_data *mii;


        sc = ifp->if_softc;
        mii = sc->mii_softc;
        FFEC_LOCK(sc);
        mii_pollstat(mii);
        ifmr->ifm_active = mii->mii_media_active;
        ifmr->ifm_status = mii->mii_media_status;
        FFEC_UNLOCK(sc);
}

static int
ffec_media_change_locked(struct ffec_softc *sc)
{

        return (mii_mediachg(sc->mii_softc));
}

static int
ffec_media_change(struct ifnet * ifp)
{
        struct ffec_softc *sc;
        int error;

        sc = ifp->if_softc;

        FFEC_LOCK(sc);
        error = ffec_media_change_locked(sc);
        FFEC_UNLOCK(sc);
        return (error);
}

static void ffec_clear_stats(struct ffec_softc *sc)
{

        WR4(sc, FEC_RMON_R_PACKETS, 0);
        WR4(sc, FEC_RMON_R_MC_PKT, 0);
        WR4(sc, FEC_RMON_R_CRC_ALIGN, 0);
        WR4(sc, FEC_RMON_R_UNDERSIZE, 0);
        WR4(sc, FEC_RMON_R_OVERSIZE, 0);
        WR4(sc, FEC_RMON_R_FRAG, 0);
        WR4(sc, FEC_RMON_R_JAB, 0);
        WR4(sc, FEC_RMON_T_PACKETS, 0);
        WR4(sc, FEC_RMON_T_MC_PKT, 0);
        WR4(sc, FEC_RMON_T_CRC_ALIGN, 0);
        WR4(sc, FEC_RMON_T_UNDERSIZE, 0);
        WR4(sc, FEC_RMON_T_OVERSIZE , 0);
        WR4(sc, FEC_RMON_T_FRAG, 0);
        WR4(sc, FEC_RMON_T_JAB, 0);
        WR4(sc, FEC_RMON_T_COL, 0);
}

static void
ffec_harvest_stats(struct ffec_softc *sc)
{
        struct ifnet *ifp;

        /* We don't need to harvest too often. */
        if (++sc->stats_harvest_count < STATS_HARVEST_INTERVAL)
                return;

        /*
         * Try to avoid harvesting unless the IDLE flag is on, but if it has
         * been too long just go ahead and do it anyway, the worst that'll
         * happen is we'll lose a packet count or two as we clear at the end.
         */
        if (sc->stats_harvest_count < (2 * STATS_HARVEST_INTERVAL) &&
            ((RD4(sc, FEC_MIBC_REG) & FEC_MIBC_IDLE) == 0))
                return;

        sc->stats_harvest_count = 0;
        ifp = sc->ifp;

        if_inc_counter(ifp, IFCOUNTER_IPACKETS, RD4(sc, FEC_RMON_R_PACKETS));
        if_inc_counter(ifp, IFCOUNTER_IMCASTS, RD4(sc, FEC_RMON_R_MC_PKT));
        if_inc_counter(ifp, IFCOUNTER_IERRORS,
            RD4(sc, FEC_RMON_R_CRC_ALIGN) + RD4(sc, FEC_RMON_R_UNDERSIZE) +
            RD4(sc, FEC_RMON_R_OVERSIZE) + RD4(sc, FEC_RMON_R_FRAG) +
            RD4(sc, FEC_RMON_R_JAB));

        if_inc_counter(ifp, IFCOUNTER_OPACKETS, RD4(sc, FEC_RMON_T_PACKETS));
        if_inc_counter(ifp, IFCOUNTER_OMCASTS, RD4(sc, FEC_RMON_T_MC_PKT));
        if_inc_counter(ifp, IFCOUNTER_OERRORS,
            RD4(sc, FEC_RMON_T_CRC_ALIGN) + RD4(sc, FEC_RMON_T_UNDERSIZE) +
            RD4(sc, FEC_RMON_T_OVERSIZE) + RD4(sc, FEC_RMON_T_FRAG) +
            RD4(sc, FEC_RMON_T_JAB));

        if_inc_counter(ifp, IFCOUNTER_COLLISIONS, RD4(sc, FEC_RMON_T_COL));

        ffec_clear_stats(sc);
}

static void
ffec_tick(void *arg)
{
        struct ffec_softc *sc;
        struct ifnet *ifp;
        int link_was_up;

        sc = arg;

        FFEC_ASSERT_LOCKED(sc);

        ifp = sc->ifp;

        if (!(ifp->if_drv_flags & IFF_DRV_RUNNING))
            return;

        /*
         * Typical tx watchdog.  If this fires it indicates that we enqueued
         * packets for output and never got a txdone interrupt for them.  Maybe
         * it's a missed interrupt somehow, just pretend we got one.
         */
        if (sc->tx_watchdog_count > 0) {
                if (--sc->tx_watchdog_count == 0) {
                        ffec_txfinish_locked(sc);
                }
        }

        /* Gather stats from hardware counters. */
        ffec_harvest_stats(sc);

        /* Check the media status. */
        link_was_up = sc->link_is_up;
        mii_tick(sc->mii_softc);
        if (sc->link_is_up && !link_was_up)
                ffec_txstart_locked(sc);

        /* Schedule another check one second from now. */
        callout_reset(&sc->ffec_callout, hz, ffec_tick, sc);
}

inline static uint32_t
ffec_setup_txdesc(struct ffec_softc *sc, int idx, bus_addr_t paddr, 
    uint32_t len)
{
        uint32_t nidx;
        uint32_t flags;

        nidx = next_txidx(sc, idx);

        /* Addr/len 0 means we're clearing the descriptor after xmit done. */
        if (paddr == 0 || len == 0) {
                flags = 0;
                --sc->txcount;
        } else {
                flags = FEC_TXDESC_READY | FEC_TXDESC_L | FEC_TXDESC_TC;
                ++sc->txcount;
        }
        if (nidx == 0)
                flags |= FEC_TXDESC_WRAP;

        /*
         * The hardware requires 32-bit physical addresses.  We set up the dma
         * tag to indicate that, so the cast to uint32_t should never lose
         * significant bits.
         */
        sc->txdesc_ring[idx].buf_paddr = (uint32_t)paddr;
        sc->txdesc_ring[idx].flags_len = flags | len; /* Must be set last! */

        return (nidx);
}

static int
ffec_setup_txbuf(struct ffec_softc *sc, int idx, struct mbuf **mp)
{
        struct mbuf * m;
        int error, nsegs;
        struct bus_dma_segment seg;

        if ((m = m_defrag(*mp, M_NOWAIT)) == NULL)
                return (ENOMEM);
        *mp = m;

        error = bus_dmamap_load_mbuf_sg(sc->txbuf_tag, sc->txbuf_map[idx].map,
            m, &seg, &nsegs, 0);
        if (error != 0) {
                return (ENOMEM);
        }
        bus_dmamap_sync(sc->txbuf_tag, sc->txbuf_map[idx].map, 
            BUS_DMASYNC_PREWRITE);

        sc->txbuf_map[idx].mbuf = m;
        ffec_setup_txdesc(sc, idx, seg.ds_addr, seg.ds_len);

        return (0);

}

static void
ffec_txstart_locked(struct ffec_softc *sc)
{
        struct ifnet *ifp;
        struct mbuf *m;
        int enqueued;

        FFEC_ASSERT_LOCKED(sc);

        if (!sc->link_is_up)
                return;

        ifp = sc->ifp;

        if (ifp->if_drv_flags & IFF_DRV_OACTIVE)
                return;

        enqueued = 0;

        for (;;) {
                if (sc->txcount == (TX_DESC_COUNT-1)) {
                        ifp->if_drv_flags |= IFF_DRV_OACTIVE;
                        break;
                }
                IFQ_DRV_DEQUEUE(&ifp->if_snd, m);
                if (m == NULL)
                        break;
                if (ffec_setup_txbuf(sc, sc->tx_idx_head, &m) != 0) {
                        IFQ_DRV_PREPEND(&ifp->if_snd, m);
                        break;
                }
                BPF_MTAP(ifp, m);
                sc->tx_idx_head = next_txidx(sc, sc->tx_idx_head);
                ++enqueued;
        }

        if (enqueued != 0) {
                bus_dmamap_sync(sc->txdesc_tag, sc->txdesc_map, BUS_DMASYNC_PREWRITE);
                WR4(sc, FEC_TDAR_REG, FEC_TDAR_TDAR);
                bus_dmamap_sync(sc->txdesc_tag, sc->txdesc_map, BUS_DMASYNC_POSTWRITE);
                sc->tx_watchdog_count = WATCHDOG_TIMEOUT_SECS;
        }
}

static void
ffec_txstart(struct ifnet *ifp)
{
        struct ffec_softc *sc = ifp->if_softc;

        FFEC_LOCK(sc);
        ffec_txstart_locked(sc);
        FFEC_UNLOCK(sc);
}

static void
ffec_txfinish_locked(struct ffec_softc *sc)
{
        struct ifnet *ifp;
        struct ffec_hwdesc *desc;
        struct ffec_bufmap *bmap;
        boolean_t retired_buffer;

        FFEC_ASSERT_LOCKED(sc);

        /* XXX Can't set PRE|POST right now, but we need both. */
        bus_dmamap_sync(sc->txdesc_tag, sc->txdesc_map, BUS_DMASYNC_PREREAD);
        bus_dmamap_sync(sc->txdesc_tag, sc->txdesc_map, BUS_DMASYNC_POSTREAD);
        ifp = sc->ifp;
        retired_buffer = false;
        while (sc->tx_idx_tail != sc->tx_idx_head) {
                desc = &sc->txdesc_ring[sc->tx_idx_tail];
                if (desc->flags_len & FEC_TXDESC_READY)
                        break;
                retired_buffer = true;
                bmap = &sc->txbuf_map[sc->tx_idx_tail];
                bus_dmamap_sync(sc->txbuf_tag, bmap->map, 
                    BUS_DMASYNC_POSTWRITE);
                bus_dmamap_unload(sc->txbuf_tag, bmap->map);
                m_freem(bmap->mbuf);
                bmap->mbuf = NULL;
                ffec_setup_txdesc(sc, sc->tx_idx_tail, 0, 0);
                sc->tx_idx_tail = next_txidx(sc, sc->tx_idx_tail);
        }

        /*
         * If we retired any buffers, there will be open tx slots available in
         * the descriptor ring, go try to start some new output.
         */
        if (retired_buffer) {
                ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
                ffec_txstart_locked(sc);
        }

        /* If there are no buffers outstanding, muzzle the watchdog. */
        if (sc->tx_idx_tail == sc->tx_idx_head) {
                sc->tx_watchdog_count = 0;
        }
}

inline static uint32_t
ffec_setup_rxdesc(struct ffec_softc *sc, int idx, bus_addr_t paddr)
{
        uint32_t nidx;

        /*
         * The hardware requires 32-bit physical addresses.  We set up the dma
         * tag to indicate that, so the cast to uint32_t should never lose
         * significant bits.
         */
        nidx = next_rxidx(sc, idx);
        sc->rxdesc_ring[idx].buf_paddr = (uint32_t)paddr;
        sc->rxdesc_ring[idx].flags_len = FEC_RXDESC_EMPTY | 
                ((nidx == 0) ? FEC_RXDESC_WRAP : 0);

        return (nidx);
}

static int
ffec_setup_rxbuf(struct ffec_softc *sc, int idx, struct mbuf * m)
{
        int error, nsegs;
        struct bus_dma_segment seg;

        /*
         * We need to leave at least ETHER_ALIGN bytes free at the beginning of
         * the buffer to allow the data to be re-aligned after receiving it (by
         * copying it backwards ETHER_ALIGN bytes in the same buffer).  We also
         * have to ensure that the beginning of the buffer is aligned to the
         * hardware's requirements.
         */
        m_adj(m, roundup(ETHER_ALIGN, FEC_RXBUF_ALIGN));

        error = bus_dmamap_load_mbuf_sg(sc->rxbuf_tag, sc->rxbuf_map[idx].map,
            m, &seg, &nsegs, 0);
        if (error != 0) {
                return (error);
        }

        bus_dmamap_sync(sc->rxbuf_tag, sc->rxbuf_map[idx].map, 
            BUS_DMASYNC_PREREAD);

        sc->rxbuf_map[idx].mbuf = m;
        ffec_setup_rxdesc(sc, idx, seg.ds_addr);
        
        return (0);
}

static struct mbuf *
ffec_alloc_mbufcl(struct ffec_softc *sc)
{
        struct mbuf *m;

        m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
        m->m_pkthdr.len = m->m_len = m->m_ext.ext_size;

        return (m);
}

static void
ffec_rxfinish_onebuf(struct ffec_softc *sc, int len)
{
        struct mbuf *m, *newmbuf;
        struct ffec_bufmap *bmap;
        uint8_t *dst, *src;
        int error;

        /*
         *  First try to get a new mbuf to plug into this slot in the rx ring.
         *  If that fails, drop the current packet and recycle the current
         *  mbuf, which is still mapped and loaded.
         */
        if ((newmbuf = ffec_alloc_mbufcl(sc)) == NULL) {
                if_inc_counter(sc->ifp, IFCOUNTER_IQDROPS, 1);
                ffec_setup_rxdesc(sc, sc->rx_idx, 
                    sc->rxdesc_ring[sc->rx_idx].buf_paddr);
                return;
        }

        /*
         *  Unfortunately, the protocol headers need to be aligned on a 32-bit
         *  boundary for the upper layers.  The hardware requires receive
         *  buffers to be 16-byte aligned.  The ethernet header is 14 bytes,
         *  leaving the protocol header unaligned.  We used m_adj() after
         *  allocating the buffer to leave empty space at the start of the
         *  buffer, now we'll use the alignment agnostic bcopy() routine to
         *  shuffle all the data backwards 2 bytes and adjust m_data.
         *
         *  XXX imx6 hardware is able to do this 2-byte alignment by setting the
         *  SHIFT16 bit in the RACC register.  Older hardware doesn't have that
         *  feature, but for them could we speed this up by copying just the
         *  protocol headers into their own small mbuf then chaining the cluster
         *  to it?  That way we'd only need to copy like 64 bytes or whatever
         *  the biggest header is, instead of the whole 1530ish-byte frame.
         */

        FFEC_UNLOCK(sc);

        bmap = &sc->rxbuf_map[sc->rx_idx];
        len -= ETHER_CRC_LEN;
        bus_dmamap_sync(sc->rxbuf_tag, bmap->map, BUS_DMASYNC_POSTREAD);
        bus_dmamap_unload(sc->rxbuf_tag, bmap->map);
        m = bmap->mbuf;
        bmap->mbuf = NULL;
        m->m_len = len;
        m->m_pkthdr.len = len;
        m->m_pkthdr.rcvif = sc->ifp;

        src = mtod(m, uint8_t*);
        dst = src - ETHER_ALIGN;
        bcopy(src, dst, len);
        m->m_data = dst;
        sc->ifp->if_input(sc->ifp, m);

        FFEC_LOCK(sc);

        if ((error = ffec_setup_rxbuf(sc, sc->rx_idx, newmbuf)) != 0) {
                device_printf(sc->dev, "ffec_setup_rxbuf error %d\n", error);
                /* XXX Now what?  We've got a hole in the rx ring. */
        }

}

static void
ffec_rxfinish_locked(struct ffec_softc *sc)
{
        struct ffec_hwdesc *desc;
        int len;
        boolean_t produced_empty_buffer;

        FFEC_ASSERT_LOCKED(sc);

        /* XXX Can't set PRE|POST right now, but we need both. */
        bus_dmamap_sync(sc->rxdesc_tag, sc->rxdesc_map, BUS_DMASYNC_PREREAD);
        bus_dmamap_sync(sc->rxdesc_tag, sc->rxdesc_map, BUS_DMASYNC_POSTREAD);
        produced_empty_buffer = false;
        for (;;) {
                desc = &sc->rxdesc_ring[sc->rx_idx];
                if (desc->flags_len & FEC_RXDESC_EMPTY)
                        break;
                produced_empty_buffer = true;
                len = (desc->flags_len & FEC_RXDESC_LEN_MASK);
                if (len < 64) {
                        /*
                         * Just recycle the descriptor and continue.           .
                         */
                        ffec_setup_rxdesc(sc, sc->rx_idx,
                            sc->rxdesc_ring[sc->rx_idx].buf_paddr);
                } else if ((desc->flags_len & FEC_RXDESC_L) == 0) {
                        /*
                         * The entire frame is not in this buffer.  Impossible.
                         * Recycle the descriptor and continue.
                         *
                         * XXX what's the right way to handle this? Probably we
                         * should stop/init the hardware because this should
                         * just really never happen when we have buffers bigger
                         * than the maximum frame size.
                         */
                        device_printf(sc->dev, 
                            "fec_rxfinish: received frame without LAST bit set");
                        ffec_setup_rxdesc(sc, sc->rx_idx, 
                            sc->rxdesc_ring[sc->rx_idx].buf_paddr);
                } else if (desc->flags_len & FEC_RXDESC_ERROR_BITS) {
                        /*
                         *  Something went wrong with receiving the frame, we
                         *  don't care what (the hardware has counted the error
                         *  in the stats registers already), we just reuse the
                         *  same mbuf, which is still dma-mapped, by resetting
                         *  the rx descriptor.
                         */
                        ffec_setup_rxdesc(sc, sc->rx_idx, 
                            sc->rxdesc_ring[sc->rx_idx].buf_paddr);
                } else {
                        /*
                         *  Normal case: a good frame all in one buffer.
                         */
                        ffec_rxfinish_onebuf(sc, len);
                }
                sc->rx_idx = next_rxidx(sc, sc->rx_idx);
        }

        if (produced_empty_buffer) {
                bus_dmamap_sync(sc->rxdesc_tag, sc->rxdesc_map, BUS_DMASYNC_PREWRITE);
                WR4(sc, FEC_RDAR_REG, FEC_RDAR_RDAR);
                bus_dmamap_sync(sc->rxdesc_tag, sc->rxdesc_map, BUS_DMASYNC_POSTWRITE);
        }
}

static void
ffec_get_hwaddr(struct ffec_softc *sc, uint8_t *hwaddr)
{
        uint32_t palr, paur, rnd;

        /*
         * Try to recover a MAC address from the running hardware. If there's
         * something non-zero there, assume the bootloader did the right thing
         * and just use it.
         *
         * Otherwise, set the address to a convenient locally assigned address,
         * 'bsd' + random 24 low-order bits.  'b' is 0x62, which has the locally
         * assigned bit set, and the broadcast/multicast bit clear.
         */
        palr = RD4(sc, FEC_PALR_REG);
        paur = RD4(sc, FEC_PAUR_REG) & FEC_PAUR_PADDR2_MASK;
        if ((palr | paur) != 0) {
                hwaddr[0] = palr >> 24;
                hwaddr[1] = palr >> 16;
                hwaddr[2] = palr >>  8;
                hwaddr[3] = palr >>  0;
                hwaddr[4] = paur >> 24;
                hwaddr[5] = paur >> 16;
        } else {
                rnd = arc4random() & 0x00ffffff;
                hwaddr[0] = 'b';
                hwaddr[1] = 's';
                hwaddr[2] = 'd';
                hwaddr[3] = rnd >> 16;
                hwaddr[4] = rnd >>  8;
                hwaddr[5] = rnd >>  0;
        }

        if (bootverbose) {
                device_printf(sc->dev,
                    "MAC address %02x:%02x:%02x:%02x:%02x:%02x:\n",
                    hwaddr[0], hwaddr[1], hwaddr[2], 
                    hwaddr[3], hwaddr[4], hwaddr[5]);
        }
}

static void
ffec_setup_rxfilter(struct ffec_softc *sc)
{
        struct ifnet *ifp;
        struct ifmultiaddr *ifma;
        uint8_t *eaddr;
        uint32_t crc;
        uint64_t ghash, ihash;

        FFEC_ASSERT_LOCKED(sc);

        ifp = sc->ifp;

        /*
         * Set the multicast (group) filter hash.
         */
        if ((ifp->if_flags & IFF_ALLMULTI))
                ghash = 0xffffffffffffffffLLU;
        else {
                ghash = 0;
                if_maddr_rlock(ifp);
                TAILQ_FOREACH(ifma, &sc->ifp->if_multiaddrs, ifma_link) {
                        if (ifma->ifma_addr->sa_family != AF_LINK)
                                continue;
                        /* 6 bits from MSB in LE CRC32 are used for hash. */
                        crc = ether_crc32_le(LLADDR((struct sockaddr_dl *)
                            ifma->ifma_addr), ETHER_ADDR_LEN);
                        ghash |= 1LLU << (((uint8_t *)&crc)[3] >> 2);
                }
                if_maddr_runlock(ifp);
        }
        WR4(sc, FEC_GAUR_REG, (uint32_t)(ghash >> 32));
        WR4(sc, FEC_GALR_REG, (uint32_t)ghash);

        /*
         * Set the individual address filter hash.
         *
         * XXX Is 0 the right value when promiscuous is off?  This hw feature
         * seems to support the concept of MAC address aliases, does such a
         * thing even exist?
         */
        if ((ifp->if_flags & IFF_PROMISC))
                ihash = 0xffffffffffffffffLLU;
        else {
                ihash = 0;
        }
        WR4(sc, FEC_IAUR_REG, (uint32_t)(ihash >> 32));
        WR4(sc, FEC_IALR_REG, (uint32_t)ihash);

        /*
         * Set the primary address.
         */
        eaddr = IF_LLADDR(ifp);
        WR4(sc, FEC_PALR_REG, (eaddr[0] << 24) | (eaddr[1] << 16) |
            (eaddr[2] <<  8) | eaddr[3]);
        WR4(sc, FEC_PAUR_REG, (eaddr[4] << 24) | (eaddr[5] << 16));
}

static void
ffec_stop_locked(struct ffec_softc *sc)
{
        struct ifnet *ifp;
        struct ffec_hwdesc *desc;
        struct ffec_bufmap *bmap;
        int idx;

        FFEC_ASSERT_LOCKED(sc);

        ifp = sc->ifp;
        ifp->if_drv_flags &= ~(IFF_DRV_RUNNING | IFF_DRV_OACTIVE);
        sc->tx_watchdog_count = 0;
        sc->stats_harvest_count = 0;

        /* 
         * Stop the hardware, mask all interrupts, and clear all current
         * interrupt status bits.
         */
        WR4(sc, FEC_ECR_REG, RD4(sc, FEC_ECR_REG) & ~FEC_ECR_ETHEREN);
        WR4(sc, FEC_IEM_REG, 0x00000000);
        WR4(sc, FEC_IER_REG, 0xffffffff);

        /*
         * Stop the media-check callout.  Do not use callout_drain() because
         * we're holding a mutex the callout acquires, and if it's currently
         * waiting to acquire it, we'd deadlock.  If it is waiting now, the
         * ffec_tick() routine will return without doing anything when it sees
         * that IFF_DRV_RUNNING is not set, so avoiding callout_drain() is safe.
         */
        callout_stop(&sc->ffec_callout);

        /*
         * Discard all untransmitted buffers.  Each buffer is simply freed;
         * it's as if the bits were transmitted and then lost on the wire.
         *
         * XXX Is this right?  Or should we use IFQ_DRV_PREPEND() to put them
         * back on the queue for when we get restarted later?
         */
        idx = sc->tx_idx_tail;
        while (idx != sc->tx_idx_head) {
                desc = &sc->txdesc_ring[idx];
                bmap = &sc->txbuf_map[idx];
                if (desc->buf_paddr != 0) {
                        bus_dmamap_unload(sc->txbuf_tag, bmap->map);
                        m_freem(bmap->mbuf);
                        bmap->mbuf = NULL;
                        ffec_setup_txdesc(sc, idx, 0, 0);
                }
                idx = next_txidx(sc, idx);
        }

        /*
         * Discard all unprocessed receive buffers.  This amounts to just
         * pretending that nothing ever got received into them.  We reuse the
         * mbuf already mapped for each desc, simply turning the EMPTY flags
         * back on so they'll get reused when we start up again.
         */
        for (idx = 0; idx < RX_DESC_COUNT; ++idx) {
                desc = &sc->rxdesc_ring[idx];
                ffec_setup_rxdesc(sc, idx, desc->buf_paddr);
        }
}

static void
ffec_init_locked(struct ffec_softc *sc)
{
        struct ifnet *ifp = sc->ifp;
        uint32_t maxbuf, maxfl, regval;

        FFEC_ASSERT_LOCKED(sc);

        /*
         * The hardware has a limit of 0x7ff as the max frame length (see
         * comments for MRBR below), and we use mbuf clusters as receive
         * buffers, and we currently are designed to receive an entire frame
         * into a single buffer.
         *
         * We start with a MCLBYTES-sized cluster, but we have to offset into
         * the buffer by ETHER_ALIGN to make room for post-receive re-alignment,
         * and then that value has to be rounded up to the hardware's DMA
         * alignment requirements, so all in all our buffer is that much smaller
         * than MCLBYTES.
         *
         * The resulting value is used as the frame truncation length and the
         * max buffer receive buffer size for now.  It'll become more complex
         * when we support jumbo frames and receiving fragments of them into
         * separate buffers.
         */
        maxbuf = MCLBYTES - roundup(ETHER_ALIGN, FEC_RXBUF_ALIGN);
        maxfl = min(maxbuf, 0x7ff);

        if (ifp->if_drv_flags & IFF_DRV_RUNNING)
                return;

        /* Mask all interrupts and clear all current interrupt status bits. */
        WR4(sc, FEC_IEM_REG, 0x00000000);
        WR4(sc, FEC_IER_REG, 0xffffffff);

        /*
         * Go set up palr/puar, galr/gaur, ialr/iaur.
         */
        ffec_setup_rxfilter(sc);

        /*
         * TFWR - Transmit FIFO watermark register.
         *
         * Set the transmit fifo watermark register to "store and forward" mode
         * and also set a threshold of 128 bytes in the fifo before transmission
         * of a frame begins (to avoid dma underruns).  Recent FEC hardware
         * supports STRFWD and when that bit is set, the watermark level in the
         * low bits is ignored.  Older hardware doesn't have STRFWD, but writing
         * to that bit is innocuous, and the TWFR bits get used instead.
         */
        WR4(sc, FEC_TFWR_REG, FEC_TFWR_STRFWD | FEC_TFWR_TWFR_128BYTE);

        /* RCR - Receive control register.
         *
         * Set max frame length + clean out anything left from u-boot.
         */
        WR4(sc, FEC_RCR_REG, (maxfl << FEC_RCR_MAX_FL_SHIFT));

        /*
         * TCR - Transmit control register.
         *
         * Clean out anything left from u-boot.  Any necessary values are set in
         * ffec_miibus_statchg() based on the media type.
         */
        WR4(sc, FEC_TCR_REG, 0);
        
        /*
         * OPD - Opcode/pause duration.
         *
         * XXX These magic numbers come from u-boot.
         */
        WR4(sc, FEC_OPD_REG, 0x00010020);

        /*
         * FRSR - Fifo receive start register.
         *
         * This register does not exist on imx6, it is present on earlier
         * hardware. The u-boot code sets this to a non-default value that's 32
         * bytes larger than the default, with no clue as to why.  The default
         * value should work fine, so there's no code to init it here.
         */

        /*
         *  MRBR - Max RX buffer size.
         *
         *  Note: For hardware prior to imx6 this value cannot exceed 0x07ff,
         *  but the datasheet says no such thing for imx6.  On the imx6, setting
         *  this to 2K without setting EN1588 resulted in a crazy runaway
         *  receive loop in the hardware, where every rx descriptor in the ring
         *  had its EMPTY flag cleared, no completion or error flags set, and a
         *  length of zero.  I think maybe you can only exceed it when EN1588 is
         *  set, like maybe that's what enables jumbo frames, because in general
         *  the EN1588 flag seems to be the "enable new stuff" vs. "be legacy-
         *  compatible" flag.
         */
        WR4(sc, FEC_MRBR_REG, maxfl << FEC_MRBR_R_BUF_SIZE_SHIFT);

        /*
         * FTRL - Frame truncation length.
         *
         * Must be greater than or equal to the value set in FEC_RCR_MAXFL.
         */
        WR4(sc, FEC_FTRL_REG, maxfl);

        /*
         * RDSR / TDSR descriptor ring pointers.
         *
         * When we turn on ECR_ETHEREN at the end, the hardware zeroes its
         * internal current descriptor index values for both rings, so we zero
         * our index values as well.
         */
        sc->rx_idx = 0;
        sc->tx_idx_head = sc->tx_idx_tail = 0;
        sc->txcount = 0;
        WR4(sc, FEC_RDSR_REG, sc->rxdesc_ring_paddr);
        WR4(sc, FEC_TDSR_REG, sc->txdesc_ring_paddr);

        /*
         * EIM - interrupt mask register.
         *
         * We always enable the same set of interrupts while running; unlike
         * some drivers there's no need to change the mask on the fly depending
         * on what operations are in progress.
         */
        WR4(sc, FEC_IEM_REG, FEC_IER_TXF | FEC_IER_RXF | FEC_IER_EBERR);

        /*
         * MIBC - MIB control (hardware stats).
         */
        regval = RD4(sc, FEC_MIBC_REG);
        WR4(sc, FEC_MIBC_REG, regval | FEC_MIBC_DIS);
        ffec_clear_stats(sc);
        WR4(sc, FEC_MIBC_REG, regval & ~FEC_MIBC_DIS);

        /*
         * ECR - Ethernet control register.
         *
         * This must happen after all the other config registers are set.  If
         * we're running on little-endian hardware, also set the flag for byte-
         * swapping descriptor ring entries.  This flag doesn't exist on older
         * hardware, but it can be safely set -- the bit position it occupies
         * was unused.
         */
        regval = RD4(sc, FEC_ECR_REG);
#if _BYTE_ORDER == _LITTLE_ENDIAN
        regval |= FEC_ECR_DBSWP;
#endif
        regval |= FEC_ECR_ETHEREN;
        WR4(sc, FEC_ECR_REG, regval);

        ifp->if_drv_flags |= IFF_DRV_RUNNING;

       /*
        * Call mii_mediachg() which will call back into ffec_miibus_statchg() to
        * set up the remaining config registers based on the current media.
        */
        mii_mediachg(sc->mii_softc);
        callout_reset(&sc->ffec_callout, hz, ffec_tick, sc);

        /*
         * Tell the hardware that receive buffers are available.  They were made
         * available in ffec_attach() or ffec_stop().
         */
        WR4(sc, FEC_RDAR_REG, FEC_RDAR_RDAR);
}

static void
ffec_init(void *if_softc)
{
        struct ffec_softc *sc = if_softc;

        FFEC_LOCK(sc);
        ffec_init_locked(sc);
        FFEC_UNLOCK(sc);
}

static void
ffec_intr(void *arg)
{
        struct ffec_softc *sc;
        uint32_t ier;

        sc = arg;

        FFEC_LOCK(sc);

        ier = RD4(sc, FEC_IER_REG);

        if (ier & FEC_IER_TXF) {
                WR4(sc, FEC_IER_REG, FEC_IER_TXF);
                ffec_txfinish_locked(sc);
        }

        if (ier & FEC_IER_RXF) {
                WR4(sc, FEC_IER_REG, FEC_IER_RXF);
                ffec_rxfinish_locked(sc);
        }

        /*
         * We actually don't care about most errors, because the hardware copes
         * with them just fine, discarding the incoming bad frame, or forcing a
         * bad CRC onto an outgoing bad frame, and counting the errors in the
         * stats registers.  The one that really matters is EBERR (DMA bus
         * error) because the hardware automatically clears ECR[ETHEREN] and we
         * have to restart it here.  It should never happen.
         */
        if (ier & FEC_IER_EBERR) {
                WR4(sc, FEC_IER_REG, FEC_IER_EBERR);
                device_printf(sc->dev, 
                    "Ethernet DMA error, restarting controller.\n");
                ffec_stop_locked(sc);
                ffec_init_locked(sc);
        }

        FFEC_UNLOCK(sc);

}

static int
ffec_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
{
        struct ffec_softc *sc;
        struct mii_data *mii;
        struct ifreq *ifr;
        int mask, error;

        sc = ifp->if_softc;
        ifr = (struct ifreq *)data;

        error = 0;
        switch (cmd) {
        case SIOCSIFFLAGS:
                FFEC_LOCK(sc);
                if (ifp->if_flags & IFF_UP) {
                        if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
                                if ((ifp->if_flags ^ sc->if_flags) &
                                    (IFF_PROMISC | IFF_ALLMULTI))
                                        ffec_setup_rxfilter(sc);
                        } else {
                                if (!sc->is_detaching)
                                        ffec_init_locked(sc);
                        }
                } else {
                        if (ifp->if_drv_flags & IFF_DRV_RUNNING)
                                ffec_stop_locked(sc);
                }
                sc->if_flags = ifp->if_flags;
                FFEC_UNLOCK(sc);
                break;

        case SIOCADDMULTI:
        case SIOCDELMULTI:
                if (ifp->if_drv_flags & IFF_DRV_RUNNING) {
                        FFEC_LOCK(sc);
                        ffec_setup_rxfilter(sc);
                        FFEC_UNLOCK(sc);
                }
                break;

        case SIOCSIFMEDIA:
        case SIOCGIFMEDIA:
                mii = sc->mii_softc;
                error = ifmedia_ioctl(ifp, ifr, &mii->mii_media, cmd);
                break;

        case SIOCSIFCAP:
                mask = ifp->if_capenable ^ ifr->ifr_reqcap;
                if (mask & IFCAP_VLAN_MTU) {
                        /* No work to do except acknowledge the change took. */
                        ifp->if_capenable ^= IFCAP_VLAN_MTU;
                }
                break;

        default:
                error = ether_ioctl(ifp, cmd, data);
                break;
        }       

        return (error);
}

static int
ffec_detach(device_t dev)
{
        struct ffec_softc *sc;
        bus_dmamap_t map;
        int idx;

        /*
         * NB: This function can be called internally to unwind a failure to
         * attach. Make sure a resource got allocated/created before destroying.
         */

        sc = device_get_softc(dev);

        if (sc->is_attached) {
                FFEC_LOCK(sc);
                sc->is_detaching = true;
                ffec_stop_locked(sc);
                FFEC_UNLOCK(sc);
                callout_drain(&sc->ffec_callout);
                ether_ifdetach(sc->ifp);
        }

        /* XXX no miibus detach? */

        /* Clean up RX DMA resources and free mbufs. */
        for (idx = 0; idx < RX_DESC_COUNT; ++idx) {
                if ((map = sc->rxbuf_map[idx].map) != NULL) {
                        bus_dmamap_unload(sc->rxbuf_tag, map);
                        bus_dmamap_destroy(sc->rxbuf_tag, map);
                        m_freem(sc->rxbuf_map[idx].mbuf);
                }
        }
        if (sc->rxbuf_tag != NULL)
                bus_dma_tag_destroy(sc->rxbuf_tag);
        if (sc->rxdesc_map != NULL) {
                bus_dmamap_unload(sc->rxdesc_tag, sc->rxdesc_map);
                bus_dmamap_destroy(sc->rxdesc_tag, sc->rxdesc_map);
        }
        if (sc->rxdesc_tag != NULL)
        bus_dma_tag_destroy(sc->rxdesc_tag);

        /* Clean up TX DMA resources. */
        for (idx = 0; idx < TX_DESC_COUNT; ++idx) {
                if ((map = sc->txbuf_map[idx].map) != NULL) {
                        /* TX maps are already unloaded. */
                        bus_dmamap_destroy(sc->txbuf_tag, map);
                }
        }
        if (sc->txbuf_tag != NULL)
                bus_dma_tag_destroy(sc->txbuf_tag);
        if (sc->txdesc_map != NULL) {
                bus_dmamap_unload(sc->txdesc_tag, sc->txdesc_map);
                bus_dmamap_destroy(sc->txdesc_tag, sc->txdesc_map);
        }
        if (sc->txdesc_tag != NULL)
        bus_dma_tag_destroy(sc->txdesc_tag);

        /* Release bus resources. */
        if (sc->intr_cookie)
                bus_teardown_intr(dev, sc->irq_res, sc->intr_cookie);

        if (sc->irq_res != NULL)
                bus_release_resource(dev, SYS_RES_IRQ, 0, sc->irq_res);

        if (sc->mem_res != NULL)
                bus_release_resource(dev, SYS_RES_MEMORY, 0, sc->mem_res);

        FFEC_LOCK_DESTROY(sc);
        return (0);
}

static int
ffec_attach(device_t dev)
{
        struct ffec_softc *sc;
        struct ifnet *ifp = NULL;
        struct mbuf *m;
        phandle_t ofw_node;
        int error, rid;
        uint8_t eaddr[ETHER_ADDR_LEN];
        char phy_conn_name[32];
        uint32_t idx, mscr;

        sc = device_get_softc(dev);
        sc->dev = dev;

        FFEC_LOCK_INIT(sc);

        /*
         * There are differences in the implementation and features of the FEC
         * hardware on different SoCs, so figure out what type we are.
         */
        sc->fectype = ofw_bus_search_compatible(dev, compat_data)->ocd_data;

        /*
         * We have to be told what kind of electrical connection exists between
         * the MAC and PHY or we can't operate correctly.
         */
        if ((ofw_node = ofw_bus_get_node(dev)) == -1) {
                device_printf(dev, "Impossible: Can't find ofw bus node\n");
                error = ENXIO;
                goto out;
        }
        if (OF_searchprop(ofw_node, "phy-mode", 
            phy_conn_name, sizeof(phy_conn_name)) != -1) {
                if (strcasecmp(phy_conn_name, "mii") == 0)
                        sc->phy_conn_type = PHY_CONN_MII;
                else if (strcasecmp(phy_conn_name, "rmii") == 0)
                        sc->phy_conn_type = PHY_CONN_RMII;
                else if (strcasecmp(phy_conn_name, "rgmii") == 0)
                        sc->phy_conn_type = PHY_CONN_RGMII;
        }
        if (sc->phy_conn_type == PHY_CONN_UNKNOWN) {
                device_printf(sc->dev, "No valid 'phy-mode' "
                    "property found in FDT data for device.\n");
#ifndef __rtems__
                error = ENOATTR;
#else /* __rtems__ */
                error = ENXIO;
#endif /* __rtems__ */
                goto out;
        }

        callout_init_mtx(&sc->ffec_callout, &sc->mtx, 0);

        /* Allocate bus resources for accessing the hardware. */
        rid = 0;
        sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, 
            RF_ACTIVE);
        if (sc->mem_res == NULL) {
                device_printf(dev, "could not allocate memory resources.\n");
                error = ENOMEM;
                goto out;
        }
        rid = 0;
        sc->irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
            RF_ACTIVE);
        if (sc->irq_res == NULL) {
                device_printf(dev, "could not allocate interrupt resources.\n");
                error = ENOMEM;
                goto out;
        }

        /*
         * Set up TX descriptor ring, descriptors, and dma maps.
         */
        error = bus_dma_tag_create(
            bus_get_dma_tag(dev),       /* Parent tag. */
            FEC_DESC_RING_ALIGN, 0,     /* alignment, boundary */
            BUS_SPACE_MAXADDR_32BIT,    /* lowaddr */
            BUS_SPACE_MAXADDR,          /* highaddr */
            NULL, NULL,                 /* filter, filterarg */
            TX_DESC_SIZE, 1,            /* maxsize, nsegments */
            TX_DESC_SIZE,               /* maxsegsize */
            0,                          /* flags */
            NULL, NULL,                 /* lockfunc, lockarg */
            &sc->txdesc_tag);
        if (error != 0) {
                device_printf(sc->dev,
                    "could not create TX ring DMA tag.\n");
                goto out;
        }

        error = bus_dmamem_alloc(sc->txdesc_tag, (void**)&sc->txdesc_ring,
            BUS_DMA_COHERENT | BUS_DMA_WAITOK | BUS_DMA_ZERO, &sc->txdesc_map);
        if (error != 0) {
                device_printf(sc->dev,
                    "could not allocate TX descriptor ring.\n");
                goto out;
        }

        error = bus_dmamap_load(sc->txdesc_tag, sc->txdesc_map, sc->txdesc_ring,
            TX_DESC_SIZE, ffec_get1paddr, &sc->txdesc_ring_paddr, 0);
        if (error != 0) {
                device_printf(sc->dev,
                    "could not load TX descriptor ring map.\n");
                goto out;
        }

        error = bus_dma_tag_create(
            bus_get_dma_tag(dev),       /* Parent tag. */
            FEC_TXBUF_ALIGN, 0,         /* alignment, boundary */
            BUS_SPACE_MAXADDR_32BIT,    /* lowaddr */
            BUS_SPACE_MAXADDR,          /* highaddr */
            NULL, NULL,                 /* filter, filterarg */
            MCLBYTES, 1,                /* maxsize, nsegments */
            MCLBYTES,                   /* maxsegsize */
            0,                          /* flags */
            NULL, NULL,                 /* lockfunc, lockarg */
            &sc->txbuf_tag);
        if (error != 0) {
                device_printf(sc->dev,
                    "could not create TX ring DMA tag.\n");
                goto out;
        }

        for (idx = 0; idx < TX_DESC_COUNT; ++idx) {
                error = bus_dmamap_create(sc->txbuf_tag, 0, 
                    &sc->txbuf_map[idx].map);
                if (error != 0) {
                        device_printf(sc->dev,
                            "could not create TX buffer DMA map.\n");
                        goto out;
                }
                ffec_setup_txdesc(sc, idx, 0, 0);
        }

        /*
         * Set up RX descriptor ring, descriptors, dma maps, and mbufs.
         */
        error = bus_dma_tag_create(
            bus_get_dma_tag(dev),       /* Parent tag. */
            FEC_DESC_RING_ALIGN, 0,     /* alignment, boundary */
            BUS_SPACE_MAXADDR_32BIT,    /* lowaddr */
            BUS_SPACE_MAXADDR,          /* highaddr */
            NULL, NULL,                 /* filter, filterarg */
            RX_DESC_SIZE, 1,            /* maxsize, nsegments */
            RX_DESC_SIZE,               /* maxsegsize */
            0,                          /* flags */
            NULL, NULL,                 /* lockfunc, lockarg */
            &sc->rxdesc_tag);
        if (error != 0) {
                device_printf(sc->dev,
                    "could not create RX ring DMA tag.\n");
                goto out;
        }

        error = bus_dmamem_alloc(sc->rxdesc_tag, (void **)&sc->rxdesc_ring, 
            BUS_DMA_COHERENT | BUS_DMA_WAITOK | BUS_DMA_ZERO, &sc->rxdesc_map);
        if (error != 0) {
                device_printf(sc->dev,
                    "could not allocate RX descriptor ring.\n");
                goto out;
        }

        error = bus_dmamap_load(sc->rxdesc_tag, sc->rxdesc_map, sc->rxdesc_ring,
            RX_DESC_SIZE, ffec_get1paddr, &sc->rxdesc_ring_paddr, 0);
        if (error != 0) {
                device_printf(sc->dev,
                    "could not load RX descriptor ring map.\n");
                goto out;
        }

        error = bus_dma_tag_create(
            bus_get_dma_tag(dev),       /* Parent tag. */
            1, 0,                       /* alignment, boundary */
            BUS_SPACE_MAXADDR_32BIT,    /* lowaddr */
            BUS_SPACE_MAXADDR,          /* highaddr */
            NULL, NULL,                 /* filter, filterarg */
            MCLBYTES, 1,                /* maxsize, nsegments */
            MCLBYTES,                   /* maxsegsize */
            0,                          /* flags */
            NULL, NULL,                 /* lockfunc, lockarg */
            &sc->rxbuf_tag);
        if (error != 0) {
                device_printf(sc->dev,
                    "could not create RX buf DMA tag.\n");
                goto out;
        }

        for (idx = 0; idx < RX_DESC_COUNT; ++idx) {
                error = bus_dmamap_create(sc->rxbuf_tag, 0, 
                    &sc->rxbuf_map[idx].map);
                if (error != 0) {
                        device_printf(sc->dev,
                            "could not create RX buffer DMA map.\n");
                        goto out;
                }
                if ((m = ffec_alloc_mbufcl(sc)) == NULL) {
                        device_printf(dev, "Could not alloc mbuf\n");
                        error = ENOMEM;
                        goto out;
                }
                if ((error = ffec_setup_rxbuf(sc, idx, m)) != 0) {
                        device_printf(sc->dev,
                            "could not create new RX buffer.\n");
                        goto out;
                }
        }

        /* Try to get the MAC address from the hardware before resetting it. */
        ffec_get_hwaddr(sc, eaddr);

        /* Reset the hardware.  Disables all interrupts. */
        WR4(sc, FEC_ECR_REG, FEC_ECR_RESET);

        /* Setup interrupt handler. */
        error = bus_setup_intr(dev, sc->irq_res, INTR_TYPE_NET | INTR_MPSAFE,
            NULL, ffec_intr, sc, &sc->intr_cookie);
        if (error != 0) {
                device_printf(dev, "could not setup interrupt handler.\n");
                goto out;
        }

        /*
         * Set up the PHY control register.
         *
         * Speed formula for ENET is md_clock = mac_clock / ((N + 1) * 2).
         * Speed formula for FEC is  md_clock = mac_clock / (N * 2)
         *
         * XXX - Revisit this...
         *
         * For a Wandboard imx6 (ENET) I was originally using 4, but the uboot
         * code uses 10.  Both values seem to work, but I suspect many modern
         * PHY parts can do mdio at speeds far above the standard 2.5 MHz.
         *
         * Different imx manuals use confusingly different terminology (things
         * like "system clock" and "internal module clock") with examples that
         * use frequencies that have nothing to do with ethernet, giving the
         * vague impression that maybe the clock in question is the periphclock
         * or something.  In fact, on an imx53 development board (FEC),
         * measuring the mdio clock at the pin on the PHY and playing with
         * various divisors showed that the root speed was 66 MHz (clk_ipg_root
         * aka periphclock) and 13 was the right divisor.
         *
         * All in all, it seems likely that 13 is a safe divisor for now,
         * because if we really do need to base it on the peripheral clock
         * speed, then we need a platform-independant get-clock-freq API.
         */
        mscr = 13 << FEC_MSCR_MII_SPEED_SHIFT;
        if (OF_hasprop(ofw_node, "phy-disable-preamble")) {
                mscr |= FEC_MSCR_DIS_PRE;
                if (bootverbose)
                        device_printf(dev, "PHY preamble disabled\n");
        }
        WR4(sc, FEC_MSCR_REG, mscr);

        /* Set up the ethernet interface. */
        sc->ifp = ifp = if_alloc(IFT_ETHER);

        ifp->if_softc = sc;
        if_initname(ifp, device_get_name(dev), device_get_unit(dev));
        ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
        ifp->if_capabilities = IFCAP_VLAN_MTU;
        ifp->if_capenable = ifp->if_capabilities;
        ifp->if_start = ffec_txstart;
        ifp->if_ioctl = ffec_ioctl;
        ifp->if_init = ffec_init;
        IFQ_SET_MAXLEN(&ifp->if_snd, TX_DESC_COUNT - 1);
        ifp->if_snd.ifq_drv_maxlen = TX_DESC_COUNT - 1;
        IFQ_SET_READY(&ifp->if_snd);
        ifp->if_hdrlen = sizeof(struct ether_vlan_header);

#if 0 /* XXX The hardware keeps stats we could use for these. */
        ifp->if_linkmib = &sc->mibdata;
        ifp->if_linkmiblen = sizeof(sc->mibdata);
#endif

        /* Set up the miigasket hardware (if any). */
        ffec_miigasket_setup(sc);

        /* Attach the mii driver. */
        error = mii_attach(dev, &sc->miibus, ifp, ffec_media_change,
            ffec_media_status, BMSR_DEFCAPMASK, MII_PHY_ANY, MII_OFFSET_ANY,
            (sc->fectype & FECTYPE_MVF) ? MIIF_FORCEANEG : 0);
        if (error != 0) {
                device_printf(dev, "PHY attach failed\n");
                goto out;
        }
        sc->mii_softc = device_get_softc(sc->miibus);

        /* All ready to run, attach the ethernet interface. */
        ether_ifattach(ifp, eaddr);
        sc->is_attached = true;

        error = 0;
out:

        if (error != 0)
                ffec_detach(dev);

        return (error);
}

static int
ffec_probe(device_t dev)
{
        uintptr_t fectype;

        if (!ofw_bus_status_okay(dev))
                return (ENXIO);

        fectype = ofw_bus_search_compatible(dev, compat_data)->ocd_data;
        if (fectype == FECTYPE_NONE)
                return (ENXIO);

        device_set_desc(dev, (fectype & FECFLAG_GBE) ?
            "Freescale Gigabit Ethernet Controller" :
            "Freescale Fast Ethernet Controller");

        return (BUS_PROBE_DEFAULT);
}


static device_method_t ffec_methods[] = {
        /* Device interface. */
        DEVMETHOD(device_probe,         ffec_probe),
        DEVMETHOD(device_attach,        ffec_attach),
        DEVMETHOD(device_detach,        ffec_detach),

/*
        DEVMETHOD(device_shutdown,      ffec_shutdown),
        DEVMETHOD(device_suspend,       ffec_suspend),
        DEVMETHOD(device_resume,        ffec_resume),
*/

        /* MII interface. */
        DEVMETHOD(miibus_readreg,       ffec_miibus_readreg),
        DEVMETHOD(miibus_writereg,      ffec_miibus_writereg),
        DEVMETHOD(miibus_statchg,       ffec_miibus_statchg),

        DEVMETHOD_END
};

static driver_t ffec_driver = {
        "ffec",
        ffec_methods,
        sizeof(struct ffec_softc)
};

static devclass_t ffec_devclass;

DRIVER_MODULE(ffec, simplebus, ffec_driver, ffec_devclass, 0, 0);
DRIVER_MODULE(miibus, ffec, miibus_driver, miibus_devclass, 0, 0);

MODULE_DEPEND(ffec, ether, 1, 1, 1);
MODULE_DEPEND(ffec, miibus, 1, 1, 1);