/*	$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);
}