/*      $NetBSD: if_el.c,v 1.102 2022/09/17 17:15:02 thorpej Exp $      */

/*
 * Copyright (c) 1994, Matthew E. Kimmel.  Permission is hereby granted
 * to use, copy, modify and distribute this software provided that both
 * the copyright notice and this permission notice appear in all copies
 * of the software, derivative works or modified versions, and any
 * portions thereof.
 */

/*
 * 3COM Etherlink 3C501 device driver
 */

/*
 * Bugs/possible improvements:
 *      - Does not currently support DMA
 *      - Does not currently support multicasts
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_el.c,v 1.102 2022/09/17 17:15:02 thorpej Exp $");

#include "opt_inet.h"

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

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/bpf.h>

#include <net/if_ether.h>

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

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

#include <dev/isa/isavar.h>
#include <dev/isa/if_elreg.h>

/* for debugging convenience */
#ifdef EL_DEBUG
#define DPRINTF(x) printf x
#else
#define DPRINTF(x)
#endif

/*
 * per-line info and status
 */
struct el_softc {
        device_t sc_dev;
        void *sc_ih;

        struct ethercom sc_ethercom;    /* ethernet common */
        bus_space_tag_t sc_iot;         /* bus space identifier */
        bus_space_handle_t sc_ioh;      /* i/o handle */
        bool sc_txbusy;                 /* transmitter is busy */

        krndsource_t rnd_source;
};

/*
 * prototypes
 */
static int      elintr(void *);
static void     elinit(struct el_softc *);
static int      elioctl(struct ifnet *, u_long, void *);
static void     elstart(struct ifnet *);
static void     elwatchdog(struct ifnet *);
static void     elreset(struct el_softc *);
static void     elstop(struct el_softc *);
static int      el_xmit(struct el_softc *);
static void     elread(struct el_softc *, int);
static struct mbuf *elget(struct el_softc *sc, int);
static inline void el_hardreset(struct el_softc *);

static int      elprobe(device_t, cfdata_t, void *);
static void     elattach(device_t, device_t, void *);

CFATTACH_DECL_NEW(el, sizeof(struct el_softc),
    elprobe, elattach, NULL, NULL);

/*
 * Probe routine.
 *
 * See if the card is there and at the right place.
 * (XXX - cgd -- needs help)
 */
static int
elprobe(device_t parent, cfdata_t match, void *aux)
{
        struct isa_attach_args *ia = aux;
        bus_space_tag_t iot = ia->ia_iot;
        bus_space_handle_t ioh;
        int iobase;
        uint8_t station_addr[ETHER_ADDR_LEN];
        uint8_t i;
        int rval;

        rval = 0;

        if (ia->ia_nio < 1)
                return (0);
        if (ia->ia_nirq < 1)
                return (0);

        if (ISA_DIRECT_CONFIG(ia))
                return (0);

        iobase = ia->ia_io[0].ir_addr;

        if (ia->ia_io[0].ir_addr == ISA_UNKNOWN_PORT)
                return (0);
        if (ia->ia_irq[0].ir_irq == ISA_UNKNOWN_IRQ)
                return (0);

        /* First check the base. */
        if (iobase < 0x200 || iobase > 0x3f0)
                return 0;

        /* Map i/o space. */
        if (bus_space_map(iot, iobase, 16, 0, &ioh))
                return 0;

        /*
         * Now attempt to grab the station address from the PROM and see if it
         * contains the 3com vendor code.
         */
        DPRINTF(("Probing 3c501 at 0x%x...\n", iobase));

        /* Reset the board. */
        DPRINTF(("Resetting board...\n"));
        bus_space_write_1(iot, ioh, EL_AC, EL_AC_RESET);
        delay(5);
        bus_space_write_1(iot, ioh, EL_AC, 0);

        /* Now read the address. */
        DPRINTF(("Reading station address...\n"));
        for (i = 0; i < ETHER_ADDR_LEN; i++) {
                bus_space_write_1(iot, ioh, EL_GPBL, i);
                station_addr[i] = bus_space_read_1(iot, ioh, EL_EAW);
        }
        DPRINTF(("Address is %s\n", ether_sprintf(station_addr)));

        /*
         * If the vendor code is ok, return a 1.  We'll assume that whoever
         * configured this system is right about the IRQ.
         */
        if (station_addr[0] != 0x02 || station_addr[1] != 0x60 ||
            station_addr[2] != 0x8c) {
                DPRINTF(("Bad vendor code.\n"));
                goto out;
        }
        DPRINTF(("Vendor code ok.\n"));

        ia->ia_nio = 1;
        ia->ia_io[0].ir_size = 16;

        ia->ia_nirq = 1;

        ia->ia_niomem = 0;
        ia->ia_ndrq = 0;

        rval = 1;

 out:
        bus_space_unmap(iot, ioh, 16);
        return rval;
}

/*
 * Attach the interface to the kernel data structures.  By the time this is
 * called, we know that the card exists at the given I/O address.  We still
 * assume that the IRQ given is correct.
 */
static void
elattach(device_t parent, device_t self, void *aux)
{
        struct el_softc *sc = device_private(self);
        struct isa_attach_args *ia = aux;
        bus_space_tag_t iot = ia->ia_iot;
        bus_space_handle_t ioh;
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        uint8_t myaddr[ETHER_ADDR_LEN];
        uint8_t i;

        sc->sc_dev = self;

        printf("\n");

        DPRINTF(("Attaching %s...\n", device_xname(sc->sc_dev)));

        /* Map i/o space. */
        if (bus_space_map(iot, ia->ia_io[0].ir_addr, 16, 0, &ioh)) {
                aprint_error_dev(self, "can't map i/o space\n");
                return;
        }

        sc->sc_iot = iot;
        sc->sc_ioh = ioh;

        /* Reset the board. */
        bus_space_write_1(iot, ioh, EL_AC, EL_AC_RESET);
        delay(5);
        bus_space_write_1(iot, ioh, EL_AC, 0);

        /* Now read the address. */
        for (i = 0; i < ETHER_ADDR_LEN; i++) {
                bus_space_write_1(iot, ioh, EL_GPBL, i);
                myaddr[i] = bus_space_read_1(iot, ioh, EL_EAW);
        }

        /* Stop the board. */
        elstop(sc);

        /* Initialize ifnet structure. */
        strlcpy(ifp->if_xname, device_xname(sc->sc_dev), IFNAMSIZ);
        ifp->if_softc = sc;
        ifp->if_start = elstart;
        ifp->if_ioctl = elioctl;
        ifp->if_watchdog = elwatchdog;
        ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX;
        IFQ_SET_READY(&ifp->if_snd);

        /* Now we can attach the interface. */
        DPRINTF(("Attaching interface...\n"));
        if_attach(ifp);
        ether_ifattach(ifp, myaddr);

        /* Print out some information for the user. */
        printf("%s: address %s\n", device_xname(self), ether_sprintf(myaddr));

        sc->sc_ih = isa_intr_establish(ia->ia_ic, ia->ia_irq[0].ir_irq,
            IST_EDGE, IPL_NET, elintr, sc);

        DPRINTF(("Attaching to random...\n"));
        rnd_attach_source(&sc->rnd_source, device_xname(sc->sc_dev),
                          RND_TYPE_NET, RND_FLAG_DEFAULT);

        DPRINTF(("elattach() finished.\n"));
}

/*
 * Reset interface.
 */
static void
elreset(struct el_softc *sc)
{
        int s;

        DPRINTF(("elreset()\n"));
        s = splnet();
        elstop(sc);
        elinit(sc);
        splx(s);
}

/*
 * Stop interface.
 */
static void
elstop(struct el_softc *sc)
{

        bus_space_write_1(sc->sc_iot, sc->sc_ioh, EL_AC, 0);
}

/*
 * Do a hardware reset of the board, and upload the ethernet address again in
 * case the board forgets.
 */
static inline void
el_hardreset(struct el_softc *sc)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int i;

        bus_space_write_1(iot, ioh, EL_AC, EL_AC_RESET);
        delay(5);
        bus_space_write_1(iot, ioh, EL_AC, 0);

        for (i = 0; i < ETHER_ADDR_LEN; i++)
                bus_space_write_1(iot, ioh, i,
                    CLLADDR(sc->sc_ethercom.ec_if.if_sadl)[i]);
}

/*
 * Initialize interface.
 */
static void
elinit(struct el_softc *sc)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;

        /* First, reset the board. */
        el_hardreset(sc);

        /* Configure rx. */
        DPRINTF(("Configuring rx...\n"));
        if (ifp->if_flags & IFF_PROMISC)
                bus_space_write_1(iot, ioh, EL_RXC,
                    EL_RXC_AGF | EL_RXC_DSHORT | EL_RXC_DDRIB |
                    EL_RXC_DOFLOW | EL_RXC_PROMISC);
        else
                bus_space_write_1(iot, ioh, EL_RXC,
                    EL_RXC_AGF | EL_RXC_DSHORT | EL_RXC_DDRIB |
                    EL_RXC_DOFLOW | EL_RXC_ABROAD);
        bus_space_write_1(iot, ioh, EL_RBC, 0);

        /* Configure TX. */
        DPRINTF(("Configuring tx...\n"));
        bus_space_write_1(iot, ioh, EL_TXC, 0);

        /* Start reception. */
        DPRINTF(("Starting reception...\n"));
        bus_space_write_1(iot, ioh, EL_AC, EL_AC_IRQE | EL_AC_RX);

        /* Set flags appropriately. */
        ifp->if_flags |= IFF_RUNNING;
        sc->sc_txbusy = false;

        /* And start output. */
        elstart(ifp);
}

/*
 * Start output on interface.  Get datagrams from the queue and output them,
 * giving the receiver a chance between datagrams.  Call only from splnet or
 * interrupt level!
 */
static void
elstart(struct ifnet *ifp)
{
        struct el_softc *sc = ifp->if_softc;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        struct mbuf *m, *m0;
        int s, i, off, retries;

        DPRINTF(("elstart()...\n"));
        s = splnet();

        /* Don't do anything if output is active. */
        if (sc->sc_txbusy) {
                splx(s);
                return;
        }

        sc->sc_txbusy = true;

        /*
         * The main loop.  They warned me against endless loops, but would I
         * listen?  NOOO....
         */
        for (;;) {
                /* Dequeue the next datagram. */
                IFQ_DEQUEUE(&ifp->if_snd, m0);

                /* If there's nothing to send, return. */
                if (m0 == 0)
                        break;

                /* Give the packet to the bpf, if any. */
                bpf_mtap(ifp, m0, BPF_D_OUT);

                /* Disable the receiver. */
                bus_space_write_1(iot, ioh, EL_AC, EL_AC_HOST);
                bus_space_write_1(iot, ioh, EL_RBC, 0);

                /* Transfer datagram to board. */
                DPRINTF(("el: xfr pkt length=%d...\n", m0->m_pkthdr.len));
                off = EL_BUFSIZ - uimax(m0->m_pkthdr.len,
                    ETHER_MIN_LEN - ETHER_CRC_LEN);
#ifdef DIAGNOSTIC
                if ((off & 0xffff) != off)
                        printf("%s: bogus off 0x%x\n",
                            device_xname(sc->sc_dev), off);
#endif
                bus_space_write_1(iot, ioh, EL_GPBL, off & 0xff);
                bus_space_write_1(iot, ioh, EL_GPBH, (off >> 8) & 0xff);

                /* Copy the datagram to the buffer. */
                for (m = m0; m != 0; m = m->m_next)
                        bus_space_write_multi_1(iot, ioh, EL_BUF,
                            mtod(m, uint8_t *), m->m_len);
                for (i = 0;
                    i < ETHER_MIN_LEN - ETHER_CRC_LEN - m0->m_pkthdr.len; i++)
                        bus_space_write_1(iot, ioh, EL_BUF, 0);

                m_freem(m0);

                /* Now transmit the datagram. */
                retries = 0;
                for (;;) {
                        bus_space_write_1(iot, ioh, EL_GPBL, off & 0xff);
                        bus_space_write_1(iot, ioh, EL_GPBH, (off >> 8) & 0xff);
                        if (el_xmit(sc)) {
                                if_statinc(ifp, if_oerrors);
                                break;
                        }
                        /* Check out status. */
                        i = bus_space_read_1(iot, ioh, EL_TXS);
                        DPRINTF(("tx status=0x%x\n", i));
                        if ((i & EL_TXS_READY) == 0) {
                                DPRINTF(("el: err txs=%x\n", i));
                                if (i & (EL_TXS_COLL | EL_TXS_COLL16)) {
                                        if_statinc(ifp, if_collisions);
                                        if ((i & EL_TXC_DCOLL16) == 0 &&
                                            retries < 15) {
                                                retries++;
                                                bus_space_write_1(iot, ioh,
                                                    EL_AC, EL_AC_HOST);
                                        }
                                } else {
                                        if_statinc(ifp, if_oerrors);
                                        break;
                                }
                        } else {
                                if_statinc(ifp, if_opackets);
                                break;
                        }
                }

                /*
                 * Now give the card a chance to receive.
                 * Gotta love 3c501s...
                 */
                (void)bus_space_read_1(iot, ioh, EL_AS);
                bus_space_write_1(iot, ioh, EL_AC, EL_AC_IRQE | EL_AC_RX);
                splx(s);
                /* (Maybe) interrupt here. */
                s = splnet();
        }

        (void)bus_space_read_1(iot, ioh, EL_AS);
        bus_space_write_1(iot, ioh, EL_AC, EL_AC_IRQE | EL_AC_RX);
        sc->sc_txbusy = false;
        splx(s);
}

/*
 * This function actually attempts to transmit a datagram downloaded to the
 * board.  Call at splnet or interrupt, after downloading data!  Returns 0 on
 * success, non-0 on failure.
 */
static int
el_xmit(struct el_softc *sc)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int i;

        /*
         * XXX
         * This busy-waits for the tx completion.  Can we get an interrupt
         * instead?
         */

        DPRINTF(("el: xmit..."));
        bus_space_write_1(iot, ioh, EL_AC, EL_AC_TXFRX);
        i = 20000;
        while ((bus_space_read_1(iot, ioh, EL_AS) & EL_AS_TXBUSY) && (i > 0))
                i--;
        if (i == 0) {
                DPRINTF(("tx not ready\n"));
                return -1;
        }
        DPRINTF(("%d cycles.\n", 20000 - i));
        return 0;
}

/*
 * Controller interrupt.
 */
static int
elintr(void *arg)
{
        struct el_softc *sc = arg;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        uint8_t rxstat;
        int len;

        DPRINTF(("elintr: "));

        /* Check board status. */
        if ((bus_space_read_1(iot, ioh, EL_AS) & EL_AS_RXBUSY) != 0) {
                (void)bus_space_read_1(iot, ioh, EL_RXC);
                bus_space_write_1(iot, ioh, EL_AC, EL_AC_IRQE | EL_AC_RX);
                return 0;
        }

        for (;;) {
                rxstat = bus_space_read_1(iot, ioh, EL_RXS);
                if (rxstat & EL_RXS_STALE)
                        break;

                /* If there's an overflow, reinit the board. */
                if ((rxstat & EL_RXS_NOFLOW) == 0) {
                        DPRINTF(("overflow.\n"));
                        el_hardreset(sc);
                        /* Put board back into receive mode. */
                        if (sc->sc_ethercom.ec_if.if_flags & IFF_PROMISC)
                                bus_space_write_1(iot, ioh, EL_RXC,
                                    EL_RXC_AGF | EL_RXC_DSHORT | EL_RXC_DDRIB |
                                    EL_RXC_DOFLOW | EL_RXC_PROMISC);
                        else
                                bus_space_write_1(iot, ioh, EL_RXC,
                                    EL_RXC_AGF | EL_RXC_DSHORT | EL_RXC_DDRIB |
                                    EL_RXC_DOFLOW | EL_RXC_ABROAD);
                        (void)bus_space_read_1(iot, ioh, EL_AS);
                        bus_space_write_1(iot, ioh, EL_RBC, 0);
                        break;
                }

                /* Incoming packet. */
                len = bus_space_read_1(iot, ioh, EL_RBL);
                len |= bus_space_read_1(iot, ioh, EL_RBH) << 8;
                DPRINTF(("receive len=%d rxstat=%x ", len, rxstat));
                bus_space_write_1(iot, ioh, EL_AC, EL_AC_HOST);

                /* Pass data up to upper levels. */
                elread(sc, len);

                /* Is there another packet? */
                if ((bus_space_read_1(iot, ioh, EL_AS) & EL_AS_RXBUSY) != 0)
                        break;

                rnd_add_uint32(&sc->rnd_source, rxstat);

                DPRINTF(("<rescan> "));
        }

        (void)bus_space_read_1(iot, ioh, EL_RXC);
        bus_space_write_1(iot, ioh, EL_AC, EL_AC_IRQE | EL_AC_RX);
        return 1;
}

/*
 * Pass a packet to the higher levels.
 */
static void
elread(struct el_softc *sc, int len)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        struct mbuf *m;

        if (len <= sizeof(struct ether_header) ||
            len > ETHER_MAX_LEN) {
                printf("%s: invalid packet size %d; dropping\n",
                    device_xname(sc->sc_dev), len);
                if_statinc(ifp, if_ierrors);
                return;
        }

        /* Pull packet off interface. */
        m = elget(sc, len);
        if (m == 0) {
                if_statinc(ifp, if_ierrors);
                return;
        }

        if_percpuq_enqueue(ifp->if_percpuq, m);
}

/*
 * Pull read data off a interface.  Len is length of data, with local net
 * header stripped.  We copy the data into mbufs.  When full cluster sized
 * units are present we copy into clusters.
 */
static struct mbuf *
elget(struct el_softc *sc, int totlen)
{
        struct ifnet *ifp = &sc->sc_ethercom.ec_if;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        struct mbuf *m, *m0, *newm;
        int len;

        MGETHDR(m0, M_DONTWAIT, MT_DATA);
        if (m0 == 0)
                return (0);
        m_set_rcvif(m0, ifp);
        m0->m_pkthdr.len = totlen;
        len = MHLEN;
        m = m0;

        bus_space_write_1(iot, ioh, EL_GPBL, 0);
        bus_space_write_1(iot, ioh, EL_GPBH, 0);

        while (totlen > 0) {
                if (totlen >= MINCLSIZE) {
                        MCLGET(m, M_DONTWAIT);
                        if ((m->m_flags & M_EXT) == 0)
                                goto bad;
                        len = MCLBYTES;
                }

                m->m_len = len = uimin(totlen, len);
                bus_space_read_multi_1(iot, ioh, EL_BUF, mtod(m, uint8_t *), len);

                totlen -= len;
                if (totlen > 0) {
                        MGET(newm, M_DONTWAIT, MT_DATA);
                        if (newm == 0)
                                goto bad;
                        len = MLEN;
                        m = m->m_next = newm;
                }
        }

        bus_space_write_1(iot, ioh, EL_RBC, 0);
        bus_space_write_1(iot, ioh, EL_AC, EL_AC_RX);

        return (m0);

bad:
        m_freem(m0);
        return (0);
}

/*
 * Process an ioctl request. This code needs some work - it looks pretty ugly.
 */
static int
elioctl(struct ifnet *ifp, u_long cmd, void *data)
{
        struct el_softc *sc = ifp->if_softc;
        struct ifaddr *ifa = (struct ifaddr *)data;
        int s, error = 0;

        s = splnet();

        switch (cmd) {

        case SIOCINITIFADDR:
                ifp->if_flags |= IFF_UP;

                elinit(sc);
                switch (ifa->ifa_addr->sa_family) {
#ifdef INET
                case AF_INET:
                        arp_ifinit(ifp, ifa);
                        break;
#endif
                default:
                        break;
                }
                break;

        case SIOCSIFFLAGS:
                if ((error = ifioctl_common(ifp, cmd, data)) != 0)
                        break;
                /* XXX re-use ether_ioctl() */
                switch (ifp->if_flags & (IFF_UP|IFF_RUNNING)) {
                case IFF_RUNNING:
                        /*
                         * If interface is marked down and it is running, then
                         * stop it.
                         */
                        elstop(sc);
                        ifp->if_flags &= ~IFF_RUNNING;
                        break;
                case IFF_UP:
                        /*
                         * If interface is marked up and it is stopped, then
                         * start it.
                         */
                        elinit(sc);
                        break;
                default:
                        /*
                         * Some other important flag might have changed, so
                         * reset.
                         */
                        elreset(sc);
                        break;
                }
                break;

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

        splx(s);
        return error;
}

/*
 * Device timeout routine.
 */
static void
elwatchdog(struct ifnet *ifp)
{
        struct el_softc *sc = ifp->if_softc;

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

        elreset(sc);
}