/*      $NetBSD: if_le_ebus.c,v 1.26 2024/07/05 04:31:49 rin Exp $      */

/*-
 * Copyright (c) 2010 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code was written by Alessandro Forin and Neil Pittman
 * at Microsoft Research and contributed to The NetBSD Foundation
 * by Microsoft Corporation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_le_ebus.c,v 1.26 2024/07/05 04:31:49 rin Exp $");

#include "opt_inet.h"



#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/syslog.h>
#include <sys/socket.h>
#include <sys/device.h>
#include <sys/ioctl.h>
#include <sys/errno.h>

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

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

#include <sys/rndsource.h>

#include <emips/ebus/ebusvar.h>
#include <emips/emips/machdep.h>
#include <machine/emipsreg.h>

extern paddr_t kvtophys(vaddr_t);

struct bufmap {
        struct mbuf *mbuf;
        paddr_t phys;
};

struct enic_softc {
        device_t sc_dev;                /* base device glue */
        struct  ethercom sc_ethercom;   /* Ethernet common part */
        struct  ifmedia sc_media;       /* our supported media */

        struct _Enic *sc_regs;          /* hw registers */

        int     sc_havecarrier;         /* carrier status */
        void    *sc_sh;                 /* shutdownhook cookie */
        int inited;

        int sc_no_rd;
        int sc_n_recv;
        int sc_recv_h;
        /* BUGBUG really should be malloc-ed */
#define SC_MAX_N_RECV 64
        struct bufmap sc_recv[SC_MAX_N_RECV];

        int sc_no_td;
        int sc_n_xmit;
        int sc_xmit_h;
        /* BUGBUG really should be malloc-ed */
#define SC_MAX_N_XMIT 16
        struct bufmap sc_xmit[SC_MAX_N_XMIT];
        bool sc_txbusy;

#if DEBUG
        int xhit;
        int xmiss;
        int tfull;
        int tfull2;
        int brh;
        int rf;
        int bxh;

        int it;
#endif

        uint8_t sc_enaddr[ETHER_ADDR_LEN];
        uint8_t sc_pad[2];
        krndsource_t    rnd_source;
};

void enic_reset(struct ifnet *);
int enic_init(struct ifnet *);
void enic_stop(struct ifnet *, int);
void enic_start(struct ifnet *);
void enic_shutdown(void *);
void enic_watchdog(struct ifnet *);
int enic_mediachange(struct ifnet *);
void enic_mediastatus(struct ifnet *, struct ifmediareq *);
int enic_ioctl(struct ifnet *, u_long, void *);
int enic_intr(void *, void *);
void enic_rint(struct enic_softc *, uint32_t, paddr_t);
void enic_tint(struct enic_softc *, uint32_t, paddr_t);
void enic_kill_xmit(struct enic_softc *);
void enic_post_recv(struct enic_softc *, struct mbuf *);
void enic_refill(struct enic_softc *);
static int enic_gethwinfo(struct enic_softc *);
int enic_put(struct enic_softc *, struct mbuf **);

static int enic_match(device_t, cfdata_t, void *);
static void enic_attach(device_t, device_t, void *);

CFATTACH_DECL_NEW(enic_emips, sizeof(struct enic_softc),
    enic_match, enic_attach, NULL, NULL);

int
enic_match(device_t parent, cfdata_t cf, void *aux)
{
        struct ebus_attach_args *d = aux;
        /* donno yet */
        struct _Enic *et = (struct _Enic *)d->ia_vaddr;

        if (strcmp("enic", d->ia_name) != 0)
                return 0;
        if ((et == NULL) || (et->Tag != PMTTAG_ETHERNET))
                return 0;
        return 1;
}

void
enic_attach(device_t parent, device_t self, void *aux)
{
        struct enic_softc *sc = device_private(self);
        struct ebus_attach_args *ia = aux;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;

        sc->sc_regs = (struct _Enic *)(ia->ia_vaddr);
#if DEBUG
        printf(" virt=%p ", (void *)sc->sc_regs);
#endif

        /* Get the MAC and the depth of the FIFOs */
        if (!enic_gethwinfo(sc)) {
                printf(" <cannot get hw info> DISABLED.\n");
                /*
                 * NB: caveat maintainer: make sure what we
                 * did NOT do below does not hurt the system
                 */
                return;
        }

        sc->sc_dev = self;
        sc->sc_no_td = 0;
        sc->sc_havecarrier = 1; /* BUGBUG */
        sc->sc_recv_h = 0;
        sc->sc_xmit_h = 0;
        /* uhmm do I need to do this? */
        memset(sc->sc_recv, 0, sizeof sc->sc_recv);
        memset(sc->sc_xmit, 0, sizeof sc->sc_xmit);

        /* Initialize ifnet structure. */
        strcpy(ifp->if_xname, device_xname(sc->sc_dev));
        ifp->if_softc = sc;
        ifp->if_start = enic_start;
        ifp->if_ioctl = enic_ioctl;
        ifp->if_watchdog = enic_watchdog;
        ifp->if_init = enic_init;
        ifp->if_stop = enic_stop;
        ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
        IFQ_SET_READY(&ifp->if_snd);

        /* Initialize ifmedia structures. */
        sc->sc_ethercom.ec_ifmedia = &sc->sc_media;
        ifmedia_init(&sc->sc_media, 0, enic_mediachange, enic_mediastatus);
        ifmedia_add(&sc->sc_media, IFM_ETHER | IFM_MANUAL, 0, NULL);
        ifmedia_set(&sc->sc_media, IFM_ETHER | IFM_MANUAL);

        /* Make sure the chip is stopped. */
        enic_stop(ifp, 0);
        sc->inited = 0;

        /* Get the mac address and print it */
        printf(": eNIC [%d %d], address %s\n",
            sc->sc_n_recv, sc->sc_n_xmit, ether_sprintf(sc->sc_enaddr));

        /* claim 802.1q capability */
#if 0
        sc->sc_ethercom.ec_capabilities |= ETHERCAP_VLAN_MTU;
#endif

        /* Attach the interface. */
        if_attach(ifp);
        if_deferred_start_init(ifp, NULL);
        ether_ifattach(ifp, sc->sc_enaddr);

        sc->sc_sh = shutdownhook_establish(enic_shutdown, ifp);
        if (sc->sc_sh == NULL)
                panic("enic_attach: cannot establish shutdown hook");

        rnd_attach_source(&sc->rnd_source, device_xname(sc->sc_dev),
                          RND_TYPE_NET, RND_FLAG_DEFAULT);

        ebus_intr_establish(parent, (void *)ia->ia_cookie, IPL_NET,
            enic_intr, sc);
}

/*
 * Beware: does not work while the nic is running
 */
static int enic_gethwinfo(struct enic_softc *sc)
{
        uint8_t buffer[8];      /* 64bits max */
        PENIC_INFO hw = (PENIC_INFO)buffer;
        paddr_t phys = kvtophys((vaddr_t)&buffer[0]), phys2;
        int i;

        /*
         * First thing first, get the MAC address
         */
        memset(buffer, 0, sizeof buffer);
        buffer[0] = ENIC_CMD_GET_ADDRESS;
        buffer[3] = ENIC_CMD_GET_ADDRESS;       /* bswap bug */
        sc->sc_regs->SizeAndFlags = (sizeof buffer) | ES_F_CMD;
        sc->sc_regs->BufferAddressHi32 = 0;
        sc->sc_regs->BufferAddressLo32 = phys; /* go! */

        for (i = 0; i < 100; i++) {
                DELAY(100);
                if ((sc->sc_regs->Control & EC_OF_EMPTY) == 0)
                        break;
        }
        if (i == 100)
                return 0;

        phys2 = sc->sc_regs->BufferAddressLo32;
        if (phys2 != phys) {
                printf("enic uhu? %llx != %llx?\n",
                    (long long)phys, (long long)phys2);
                return 0;
        }
        memcpy(sc->sc_enaddr, buffer, ETHER_ADDR_LEN);

        /*
         * Next get the HW parameters
         */
        memset(buffer, 0, sizeof buffer);
        buffer[0] = ENIC_CMD_GET_INFO;
        buffer[3] = ENIC_CMD_GET_INFO;  /* bswap bug */
        sc->sc_regs->SizeAndFlags = (sizeof buffer) | ES_F_CMD;
        sc->sc_regs->BufferAddressHi32 = 0;
        sc->sc_regs->BufferAddressLo32 = phys; /* go! */

        for (i = 0; i < 100; i++) {
                DELAY(100);
                if ((sc->sc_regs->Control & EC_OF_EMPTY) == 0)
                        break;
        }
        if (i == 100)
                return 0;

        phys2 = sc->sc_regs->BufferAddressLo32;
        if (phys2 != phys) {
                printf("enic uhu2? %llx != %llx?\n",
                    (long long)phys, (long long)phys2);
                return 0;
        }
#if 0
        printf("enic: hwinfo: %x %x %x %x %x %x \n",
            hw->InputFifoSize, hw->OutputFifoSize, hw->CompletionFifoSize,
            hw->ErrorCount, hw->FramesDropped, hw->Reserved);
#endif

        /*
         * Get FIFO depths and cap them
         */
        sc->sc_n_recv = hw->InputFifoSize;
        if (sc->sc_n_recv > SC_MAX_N_RECV)
                sc->sc_n_recv = SC_MAX_N_RECV;
        if (sc->sc_n_recv == 0) { /* sanity and compat with old hw/simulator */
                sc->sc_n_recv = 8;
                sc->sc_n_xmit = 4;
        } else {
                sc->sc_n_xmit = hw->OutputFifoSize;
                if (sc->sc_n_xmit > SC_MAX_N_XMIT)
                        sc->sc_n_xmit = SC_MAX_N_XMIT;
        }

        return 1;
}

void
enic_reset(struct ifnet *ifp)
{
        int s;

        s = splnet();
        enic_stop(ifp, 0);
        enic_init(ifp);
        splx(s);
}

void
enic_stop(struct ifnet *ifp, int suspend)
{
        struct enic_softc *sc = ifp->if_softc;

#if 0
        printf("enic_stop %x\n", sc->sc_regs->Control);
#endif

        /*
         * NB: only "ifconfig down" says suspend=1 (then "up" calls init)
         * Could simply set RXDIS in this case
         */
        sc->inited = 2;
        sc->sc_regs->Control = EC_RESET;
        sc->sc_no_rd = 0; /* they are gone */
        sc->sc_no_td = 0; /* they are gone */
}

void
enic_shutdown(void *arg)
{
        struct ifnet *ifp = arg;

        enic_stop(ifp, 0);
}

void
enic_kill_xmit(struct enic_softc *sc)
{
        int i;
        struct mbuf *m;

        for (i = 0; i < sc->sc_n_xmit; i++) {
                if ((m = sc->sc_xmit[i].mbuf) != NULL) {
                        sc->sc_xmit[i].mbuf = NULL;
                        sc->sc_xmit[i].phys = ~0;
                        m_freem(m);
                }
        }
        sc->sc_no_td = 0;
        sc->sc_xmit_h = 0;
}

void
enic_post_recv(struct enic_softc *sc, struct mbuf *m)
{
        int i, waitmode = M_DONTWAIT;
        paddr_t phys;

#define rpostone(_p_) \
    sc->sc_regs->SizeAndFlags = ES_F_RECV | MCLBYTES; \
    sc->sc_regs->BufferAddressHi32 = 0; \
    sc->sc_regs->BufferAddressLo32 = _p_;
#define tpostone(_p_,_s_) \
    sc->sc_regs->SizeAndFlags = ES_F_XMIT | (_s_); \
    sc->sc_regs->BufferAddressHi32 = 0; \
    sc->sc_regs->BufferAddressLo32 = _p_;

        /* Operational reload? */
        if (m != NULL) {
                /* But is the hw ready for it */
                if (sc->sc_regs->Control & EC_IF_FULL)
                        goto no_room;
                /* Yes, find a spot. Include empty q case. */
                for (i = sc->sc_recv_h; i < sc->sc_n_recv; i++)
                        if (sc->sc_recv[i].mbuf == NULL)
                                goto found;
                for (i = 0; i < sc->sc_recv_h; i++)
                        if (sc->sc_recv[i].mbuf == NULL)
                                goto found;
                /* no spot, drop it (sigh) */
 no_room:
#if DEBUG
                sc->rf++;
#endif
                m_freem(m);
                return;
 found:
                phys = kvtophys((vaddr_t)m->m_data);
                sc->sc_recv[i].mbuf = m;
                sc->sc_recv[i].phys = phys;
                rpostone(phys);
                sc->sc_no_rd++;
                return;
        }

        /* Repost after reset? */
        if (sc->inited) {
                /* order doesnt matter, might as well keep it clean */
                int j = 0;
                sc->sc_recv_h = 0;
                for (i = 0; i < sc->sc_n_recv; i++)
                        if ((m = sc->sc_recv[i].mbuf) != NULL) {
                                phys = sc->sc_recv[i].phys;
                                sc->sc_recv[i].mbuf = NULL;
                                sc->sc_recv[i].phys = ~0;
                                sc->sc_recv[j].mbuf = m;
                                sc->sc_recv[j].phys = phys;
#if DEBUG
                                if (sc->sc_regs->Control & EC_IF_FULL)
                                        printf("?uhu? postrecv full? %d\n",
                                            sc->sc_no_rd);
#endif
                                sc->sc_no_rd++;
                                rpostone(phys);
                                j++;
                        }
                /* Any holes left? */
                sc->inited = 1;
                if (j >= sc->sc_n_recv)
                        return; /* no, we are done */
                /* continue on with the loop below */
                i = j; m = NULL;
                goto fillem;
        }

        /* Initial refill, we can wait */
        waitmode = M_WAIT;
        sc->sc_recv_h = 0;
        memset(sc->sc_recv, 0, sizeof(sc->sc_recv[0]) * sc->sc_n_recv);
        i = 0;
 fillem:
        for (; i < sc->sc_n_recv; i++) {
                MGETHDR(m, waitmode, MT_DATA);
                if (m == 0)
                        break;
                m_set_rcvif(m, &sc->sc_ethercom.ec_if);
                m->m_pkthdr.len = 0;

                MCLGET(m, waitmode);
                if ((m->m_flags & M_EXT) == 0)
                        break;

                /*
                 * This offset aligns IP/TCP headers and helps performance
                 */
#if 1
#define ADJUST_MBUF_OFFSET(_m_) { \
        (_m_)->m_data += 2; \
        (_m_)->m_len -= 2; \
}
#else
#define ADJUST_MBUF_OFFSET(_m_)
#endif

                m->m_len = MCLBYTES;

                ADJUST_MBUF_OFFSET(m);
                phys = kvtophys((vaddr_t)m->m_data);
                sc->sc_recv[i].mbuf = m;
                sc->sc_recv[i].phys = phys;
#if DEBUG
                if (sc->sc_regs->Control & EC_IF_FULL)
                        printf("?uhu? postrecv2 full? %d\n", sc->sc_no_rd);
#endif
                sc->sc_no_rd++;
                rpostone(phys);
                m = NULL;
        }

        m_freem(m);
        sc->inited = 1;
}

void enic_refill(struct enic_softc *sc)
{
        struct mbuf *m;
        int waitmode = M_DONTWAIT;

        MGETHDR(m, waitmode, MT_DATA);
        if (m == NULL)
                return;
        m_set_rcvif(m, &sc->sc_ethercom.ec_if);
        m->m_pkthdr.len = 0;

        MCLGET(m, waitmode);
        if ((m->m_flags & M_EXT) == 0) {
                m_freem(m);
                return;
        }

        m->m_len = MCLBYTES;
        ADJUST_MBUF_OFFSET(m);

        enic_post_recv(sc, m);
}

int
enic_init(struct ifnet *ifp)
{
        struct enic_softc *sc = ifp->if_softc;
        uint32_t ctl;

        /* no need to init many times unless we are in reset */
        if (sc->inited != 1) {

                /* Cancel all xmit buffers */
                enic_kill_xmit(sc);

                /* Re-post all recv buffers */
                enic_post_recv(sc, NULL);
        }

        /* Start the eNIC */
        ifp->if_flags |= IFF_RUNNING;
        sc->sc_txbusy = false;
        ifp->if_timer = 0;
        ctl = sc->sc_regs->Control | EC_INTEN;
        ctl &= ~EC_RXDIS;
        sc->sc_regs->Control = ctl;
#if 0
        printf("enic_init <- %x\n", ctl);
#endif

        if_schedule_deferred_start(ifp);

        return 0;
}


void
enic_watchdog(struct ifnet *ifp)
{
        struct enic_softc *sc = ifp->if_softc;

#if 0
        printf("enic_watch ctl=%x\n", sc->sc_regs->Control);
#endif
        log(LOG_ERR, "%s: device timeout\n", device_xname(sc->sc_dev));
        if_statinc(ifp, if_oerrors);

        enic_reset(ifp);
}

int
enic_mediachange(struct ifnet *ifp)
{
#if 0
        struct enic_softc *sc = ifp->if_softc;
#endif
        /* more code here.. */

        return 0;
}

void
enic_mediastatus(struct ifnet *ifp, struct ifmediareq *ifmr)
{
        struct enic_softc *sc = ifp->if_softc;

        if ((ifp->if_flags & IFF_UP) == 0)
                return;

        ifmr->ifm_status = IFM_AVALID;
        if (sc->sc_havecarrier)
                ifmr->ifm_status |= IFM_ACTIVE;

        /* more code here someday.. */
}

/*
 * Process an ioctl request.
 */
int
enic_ioctl(struct ifnet *ifp, u_long cmd, void *data)
{
        int s, error = 0;

        s = splnet();

        switch (cmd) {
        default:
                error = ether_ioctl(ifp, cmd, data);
                if (cmd == SIOCSIFADDR) {
                        /*
                         * hackattack: NFS does not turn us back
                         * on after a stop. So.
                         */
#if 0
                        printf("enic_ioctl(%lx)\n", cmd);
#endif
                        enic_init(ifp);
                }
                if (error != ENETRESET)
                        break;
                error = 0;
                if (cmd != SIOCADDMULTI && cmd != SIOCDELMULTI)
                        break;
                if (ifp->if_flags & IFF_RUNNING) {
                        enic_reset(ifp);
                }
                break;
        }
        splx(s);

        return error;
}

int
enic_intr(void *cookie, void *f)
{
        struct enic_softc *sc = cookie;
        uint32_t isr, saf, hi, lo, fl;

        isr = sc->sc_regs->Control;

        /* Make sure there is one and that we should take it */
        if ((isr & (EC_INTEN | EC_DONE)) != (EC_INTEN | EC_DONE))
                return 0;

        if (isr & EC_ERROR) {
                printf("%s: internal error\n", device_xname(sc->sc_dev));
                enic_reset(&sc->sc_ethercom.ec_if);
                return 1;
        }

        /*
         * pull out all completed buffers
         */
        while ((isr & EC_OF_EMPTY) == 0) {

                /* beware, order matters */
                saf = sc->sc_regs->SizeAndFlags;
                hi  = sc->sc_regs->BufferAddressHi32; /* BUGBUG 64bit */
                lo  = sc->sc_regs->BufferAddressLo32; /* this pops the fifo */
                __USE(hi);

                fl = saf & (ES_F_MASK &~ ES_F_DONE);
                if (fl == ES_F_RECV)
                        enic_rint(sc, saf, lo);
                else if (fl == ES_F_XMIT)
                        enic_tint(sc, saf, lo);
                else {
                        /*
                         * we do not currently expect or care for
                         * command completions?
                         */
                        if (fl != ES_F_CMD)
                                printf("%s: invalid saf=x%x (lo=%x)\n",
                                    device_xname(sc->sc_dev), saf, lo);
                }

                isr = sc->sc_regs->Control;
        }

        rnd_add_uint32(&sc->rnd_source, isr);

        return 1;
}

void
enic_rint(struct enic_softc *sc, uint32_t saf, paddr_t phys)
{
        struct mbuf *m;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        int len = saf & ES_S_MASK, i;

        /* Find what buffer it is. Should be the first. */
        for (i = sc->sc_recv_h; i < sc->sc_n_recv; i++)
                if (sc->sc_recv[i].phys == phys)
                        goto found;
        for (i = 0; i < sc->sc_recv_h; i++)
                if (sc->sc_recv[i].phys == phys)
                        goto found;

        /* uhu?? */
        printf("%s: bad recv phys %llx\n", device_xname(sc->sc_dev),
            (long long)phys);
        if_statinc(ifp, if_ierrors);
        return;

        /* got it, pop it */
 found:
        sc->sc_no_rd--;
        m = sc->sc_recv[i].mbuf;
        sc->sc_recv[i].mbuf = NULL;
        sc->sc_recv[i].phys = ~0;
        if (i == sc->sc_recv_h) { /* should be */
                sc->sc_recv_h = (++i == sc->sc_n_recv) ? 0 : i;
        }
#if DEBUG
        else
                sc->brh++;
#endif

        if (len <= sizeof(struct ether_header) ||
            len > ((sc->sc_ethercom.ec_capenable & ETHERCAP_VLAN_MTU) ?
                ETHER_VLAN_ENCAP_LEN + ETHERMTU + sizeof(struct ether_header) :
                ETHERMTU + sizeof(struct ether_header))) {
                if_statinc(ifp, if_ierrors);

                /* reuse it */
                enic_post_recv(sc, m);
                return;
        }

        /* Adjust size */
        m->m_pkthdr.len = len;
        m->m_len = len; /* recheck */

        /* Pass the packet up. */
        if_percpuq_enqueue(ifp->if_percpuq, m);

        /* Need to refill now */
        enic_refill(sc);
}

void enic_tint(struct enic_softc *sc, uint32_t saf, paddr_t phys)
{
        struct mbuf *m;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        int i;

#if DEBUG
        sc->it = 1;
#endif

        /* BUGBUG should there be a per-buffer error bit in SAF? */

        /* Find what buffer it is. Should be the first. */
        for (i = sc->sc_xmit_h; i < sc->sc_n_xmit; i++)
                if (sc->sc_xmit[i].phys == phys)
                        goto found;
        for (i = 0; i < sc->sc_xmit_h; i++)
                if (sc->sc_xmit[i].phys == phys)
                        goto found;

        /* uhu?? */
        printf("%s: bad xmit phys %llx\n", device_xname(sc->sc_dev),
            (long long)phys);
        if_statinc(ifp, if_oerrors);
        return;

        /* got it, pop it */
 found:
        m = sc->sc_xmit[i].mbuf;
        sc->sc_xmit[i].mbuf = NULL;
        sc->sc_xmit[i].phys = ~0;
        if (i == sc->sc_xmit_h) { /* should be */
                sc->sc_xmit_h = (++i == sc->sc_n_xmit) ? 0 : i;
        }
#if DEBUG
        else
                sc->bxh++;
#endif
        m_freem(m);
        if_statinc(ifp, if_opackets);

        if (--sc->sc_no_td == 0)
                ifp->if_timer = 0;

        sc->sc_txbusy = false;
        if_schedule_deferred_start(ifp);
#if DEBUG
        sc->it = 1;
#endif
}

/*
 * Setup output on interface.
 * Get another datagram to send off of the interface queue, and map it to the
 * interface before starting the output.
 * Called only at splnet or interrupt level.
 */
void
enic_start(struct ifnet *ifp)
{
        struct enic_softc *sc = ifp->if_softc;
        struct mbuf *m;
        int len, ix, s;
        paddr_t phys;

#if DEBUG
        sc->it = 0;
#endif

#if 0
        printf("enic_start(%x)\n", ifp->if_flags);
#endif

        if ((ifp->if_flags & IFF_RUNNING) == 0)
                return;

        s = splnet();   /* I know, I dont trust people.. */

        ix = sc->sc_xmit_h;
        for (;;) {

                /* Anything to do? */
                IFQ_POLL(&ifp->if_snd, m);
                if (m == NULL)
                        break;

                /* find a spot, if any */
                for (; ix < sc->sc_n_xmit; ix++)
                        if (sc->sc_xmit[ix].mbuf == NULL)
                                goto found;
                for (ix = 0; ix < sc->sc_xmit_h; ix++)
                        if (sc->sc_xmit[ix].mbuf == NULL)
                                goto found;
                /* oh well */
                sc->sc_txbusy = true;
#if DEBUG
                sc->tfull++;
#endif
                break;

 found:
                IFQ_DEQUEUE(&ifp->if_snd, m);
                if (m == NULL)
                        break;

                /*
                 * If BPF is listening on this interface, let it see the packet
                 * before we commit it to the wire.
                 */
                bpf_mtap(ifp, m, BPF_D_OUT);

                /*
                 * Copy the mbuf chain into a contiguous transmit buffer.
                 */
                len = enic_put(sc, &m);
                if (len == 0)
                        break;  /* sanity */
                if (len > (ETHERMTU + sizeof(struct ether_header))) {
                        printf("enic? tlen %d > %d\n",
                            len, ETHERMTU + sizeof(struct ether_header));
                        len = ETHERMTU + sizeof(struct ether_header);
                }

                ifp->if_timer = 5;

                /*
                 * Remember and post the buffer
                 */
                phys = kvtophys((vaddr_t)m->m_data);
                sc->sc_xmit[ix].mbuf = m;
                sc->sc_xmit[ix].phys = phys;

                sc->sc_no_td++;

                tpostone(phys, len);

                if (sc->sc_regs->Control & EC_IF_FULL) {
                        sc->sc_txbusy = true;
#if DEBUG
                        sc->tfull2++;
#endif
                        break;
                }

                ix++;
        }

        splx(s);
}

int enic_put(struct enic_softc *sc, struct mbuf **pm)
{
        struct mbuf *n, *m = *pm, *mm;
        int len, tlen = 0, xlen = m->m_pkthdr.len;
        uint8_t *cp;

#if 0
        /* drop garbage */
        tlen = xlen;
        for (; m; m = n) {
                len = m->m_len;
                if (len == 0) {
                        n = m_free(m);
                        if (m == *pm)
                                *pm = n;
                        continue;
                }
                tlen -= len;
                KASSERT(m != m->m_next);
                n = m->m_next;
                if (tlen <= 0)
                        break;
        }

        /*
         * We might be done:
         * (a) empty chain (b) only one segment (c) bad chain
         */
        if (((m = *pm) == NULL) || (tlen > 0))
                xlen = 0;
#endif

        if ((xlen == 0) || (xlen <= m->m_len)) {
#if DEBUG
                sc->xhit++;
#endif
                return xlen;
        }

        /* Nope, true chain. Copy to contig :-(( */
        tlen = xlen;
        MGETHDR(n, M_NOWAIT, MT_DATA);
        if (n == NULL)
                goto Bad;
        m_set_rcvif(n, &sc->sc_ethercom.ec_if);
        n->m_pkthdr.len = tlen;

        MCLGET(n, M_NOWAIT);
        if ((n->m_flags & M_EXT) == 0) {
                m_freem(n);
                goto Bad;
        }

        n->m_len = tlen;
        cp = mtod(n, uint8_t *);
        for (; m && tlen; m = mm) {

                len = m->m_len;
                if (len > tlen)
                        len = tlen;
                if (len)
                        memcpy(cp, mtod(m, void *), len);

                cp += len;
                tlen -= len;
                mm = m_free(m);

        }

        *pm = n;
#if DEBUG
        sc->xmiss++;
#endif
        return (xlen);

 Bad:
        printf("enic_put: no mem?\n");
        m_freem(m);
        return 0;
}