/*      $NetBSD: ahb.c,v 1.70 2021/08/07 16:19:10 thorpej Exp $ */

/*-
 * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Charles M. Hannum and by Jason R. Thorpe of the Numerical Aerospace
 * Simulation Facility, NASA Ames Research Center.
 *
 * 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.
 */

/*
 * Originally written by Julian Elischer (julian@tfs.com)
 * for TRW Financial Systems for use under the MACH(2.5) operating system.
 *
 * TRW Financial Systems, in accordance with their agreement with Carnegie
 * Mellon University, makes this software available to CMU to distribute
 * or use in any manner that they see fit as long as this message is kept with
 * the software. For this reason TFS also grants any other persons or
 * organisations permission to use or modify this software.
 *
 * TFS supplies this software to be publicly redistributed
 * on the understanding that TFS is not responsible for the correct
 * functioning of this software in any circumstances.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ahb.c,v 1.70 2021/08/07 16:19:10 thorpej Exp $");

#include "opt_ddb.h"

#undef  AHBDEBUG

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <sys/device.h>
#include <sys/buf.h>
#include <sys/proc.h>

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

#include <dev/scsipi/scsi_all.h>
#include <dev/scsipi/scsipi_all.h>
#include <dev/scsipi/scsiconf.h>

#include <dev/eisa/eisareg.h>
#include <dev/eisa/eisavar.h>
#include <dev/eisa/eisadevs.h>
#include <dev/eisa/ahbreg.h>

#ifndef DDB
#define Debugger() panic("should call debugger here (aha1742.c)")
#endif /* ! DDB */

#define AHB_ECB_MAX     32      /* store up to 32 ECBs at one time */
#define ECB_HASH_SIZE   32      /* hash table size for phystokv */
#define ECB_HASH_SHIFT  9
#define ECB_HASH(x)     ((((long)(x))>>ECB_HASH_SHIFT) & (ECB_HASH_SIZE - 1))

#define AHB_MAXXFER     ((AHB_NSEG - 1) << PGSHIFT)

struct ahb_softc {
        device_t sc_dev;

        bus_space_tag_t sc_iot;
        bus_space_handle_t sc_ioh;
        bus_dma_tag_t sc_dmat;
        void *sc_ih;

        bus_dmamap_t sc_dmamap_ecb;     /* maps the ecbs */
        struct ahb_ecb *sc_ecbs;        /* all our ecbs */

        struct ahb_ecb *sc_ecbhash[ECB_HASH_SIZE];
        TAILQ_HEAD(, ahb_ecb) sc_free_ecb;
        struct ahb_ecb *sc_immed_ecb;   /* an outstanding immediete command */
        int sc_numecbs;

        struct scsipi_adapter sc_adapter;
        struct scsipi_channel sc_channel;
};

/*
 * Offset of an ECB from the beginning of the ECB DMA mapping.
 */
#define AHB_ECB_OFF(e)  (((uintptr_t)(e)) - ((uintptr_t)&sc->sc_ecbs[0]))

struct ahb_probe_data {
        int sc_irq;
        int sc_ist;
        int sc_scsi_dev;
};

static void     ahb_send_mbox(struct ahb_softc *, int, struct ahb_ecb *);
static void     ahb_send_immed(struct ahb_softc *, u_int32_t, struct ahb_ecb *);
static int      ahbintr(void *);
static void     ahb_free_ecb(struct ahb_softc *, struct ahb_ecb *);
static struct   ahb_ecb *ahb_get_ecb(struct ahb_softc *);
static struct   ahb_ecb *ahb_ecb_lookup(struct ahb_softc *, uint32_t);
static void     ahb_done(struct ahb_softc *, struct ahb_ecb *);
static int      ahb_find(bus_space_tag_t, bus_space_handle_t,
                    struct ahb_probe_data *);
static int      ahb_init(struct ahb_softc *);
static void     ahbminphys(struct buf *);
static void     ahb_scsipi_request(struct scsipi_channel *,
                    scsipi_adapter_req_t, void *);
static int      ahb_poll(struct ahb_softc *, struct scsipi_xfer *, int);
static void     ahb_timeout(void *);
static int      ahb_create_ecbs(struct ahb_softc *, struct ahb_ecb *, int);

static int      ahb_init_ecb(struct ahb_softc *, struct ahb_ecb *);

static int      ahbmatch(device_t, cfdata_t, void *);
static void     ahbattach(device_t, device_t, void *);

CFATTACH_DECL_NEW(ahb, sizeof(struct ahb_softc),
    ahbmatch, ahbattach, NULL, NULL);

#define AHB_ABORT_TIMEOUT       2000    /* time to wait for abort (mSec) */

static const struct device_compatible_entry compat_data[] = {
        { .compat = "ADP0000",  .data = EISA_PRODUCT_ADP0000 },
        { .compat = "ADP0001",  .data = EISA_PRODUCT_ADP0001 },
        { .compat = "ADP0002",  .data = EISA_PRODUCT_ADP0002 },
        { .compat = "ADP0400",  .data = EISA_PRODUCT_ADP0400 },
        DEVICE_COMPAT_EOL
};

/*
 * Check the slots looking for a board we recognise
 * If we find one, note its address (slot) and call
 * the actual probe routine to check it out.
 */
static int
ahbmatch(device_t parent, cfdata_t match, void *aux)
{
        struct eisa_attach_args *ea = aux;
        bus_space_tag_t iot = ea->ea_iot;
        bus_space_handle_t ioh;
        int rv;

        if (!eisa_compatible_match(ea, compat_data))
                return (0);

        if (bus_space_map(iot,
            EISA_SLOT_ADDR(ea->ea_slot) + AHB_EISA_SLOT_OFFSET,
            AHB_EISA_IOSIZE, 0, &ioh))
                return (0);

        rv = !ahb_find(iot, ioh, NULL);

        bus_space_unmap(iot, ioh, AHB_EISA_IOSIZE);

        return (rv);
}

/*
 * Attach all the sub-devices we can find
 */
static void
ahbattach(device_t parent, device_t self, void *aux)
{
        struct eisa_attach_args *ea = aux;
        struct ahb_softc *sc = device_private(self);
        const struct device_compatible_entry *dce;
        bus_space_tag_t iot = ea->ea_iot;
        bus_space_handle_t ioh;
        eisa_chipset_tag_t ec = ea->ea_ec;
        eisa_intr_handle_t ih;
        const char *intrstr;
        struct ahb_probe_data apd;
        struct scsipi_adapter *adapt = &sc->sc_adapter;
        struct scsipi_channel *chan = &sc->sc_channel;
        char intrbuf[EISA_INTRSTR_LEN];

        sc->sc_dev = self;

        dce = eisa_compatible_lookup(ea, compat_data);
        KASSERT(dce != NULL);

        aprint_naive("\n");
        aprint_normal(": %s\n", (const char *)dce->data);

        if (bus_space_map(iot,
            EISA_SLOT_ADDR(ea->ea_slot) + AHB_EISA_SLOT_OFFSET,
            AHB_EISA_IOSIZE, 0, &ioh))
                panic("ahbattach: could not map I/O addresses");

        sc->sc_iot = iot;
        sc->sc_ioh = ioh;
        sc->sc_dmat = ea->ea_dmat;
        if (ahb_find(iot, ioh, &apd))
                panic("ahbattach: ahb_find failed!");

        TAILQ_INIT(&sc->sc_free_ecb);

        /*
         * Fill in the scsipi_adapter.
         */
        memset(adapt, 0, sizeof(*adapt));
        adapt->adapt_dev = sc->sc_dev;
        adapt->adapt_nchannels = 1;
        /* adapt_openings initialized below */
        adapt->adapt_max_periph = 4;            /* XXX arbitrary? */
        adapt->adapt_request = ahb_scsipi_request;
        adapt->adapt_minphys = ahbminphys;

        /*
         * Fill in the scsipi_channel.
         */
        memset(chan, 0, sizeof(*chan));
        chan->chan_adapter = adapt;
        chan->chan_bustype = &scsi_bustype;
        chan->chan_channel = 0;
        chan->chan_ntargets = 8;
        chan->chan_nluns = 8;
        chan->chan_id = apd.sc_scsi_dev;

        if (ahb_init(sc) != 0) {
                /* Error during initialization! */
                return;
        }

        if (eisa_intr_map(ec, apd.sc_irq, &ih)) {
                aprint_error_dev(sc->sc_dev, "couldn't map interrupt (%d)\n",
                    apd.sc_irq);
                return;
        }
        intrstr = eisa_intr_string(ec, ih, intrbuf, sizeof(intrbuf));
        sc->sc_ih = eisa_intr_establish(ec, ih, apd.sc_ist, IPL_BIO,
            ahbintr, sc);
        if (sc->sc_ih == NULL) {
                aprint_error_dev(sc->sc_dev, "couldn't establish interrupt");
                if (intrstr != NULL)
                        aprint_error(" at %s", intrstr);
                aprint_error("\n");
                return;
        }
        if (intrstr != NULL) {
                aprint_normal_dev(sc->sc_dev,
                    "interrupting at %s (%s trigger)\n", intrstr,
                    apd.sc_ist == IST_EDGE ? "edge" : "level");
        }

        /*
         * ask the adapter what subunits are present
         */
        config_found(self, &sc->sc_channel, scsiprint, CFARGS_NONE);
}

/*
 * Function to send a command out through a mailbox
 */
static void
ahb_send_mbox(struct ahb_softc *sc, int opcode, struct ahb_ecb *ecb)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int wait = 300; /* 1ms should be enough */

        while (--wait) {
                if ((bus_space_read_1(iot, ioh, G2STAT) & (G2STAT_BUSY | G2STAT_MBOX_EMPTY))
                    == (G2STAT_MBOX_EMPTY))
                        break;
                delay(10);
        }
        if (!wait) {
                printf("%s: board not responding\n", device_xname(sc->sc_dev));
                Debugger();
        }

        bus_space_write_4(iot, ioh, MBOXOUT0, ecb->ecb_dma_addr);
        bus_space_write_1(iot, ioh, ATTN, opcode |
                ecb->xs->xs_periph->periph_target);

        if ((ecb->xs->xs_control & XS_CTL_POLL) == 0)
                callout_reset(&ecb->xs->xs_callout,
                    mstohz(ecb->timeout), ahb_timeout, ecb);
}

/*
 * Function to send an immediate type command to the adapter
 */
static void
ahb_send_immed(struct ahb_softc *sc, u_int32_t cmd, struct ahb_ecb *ecb)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int wait = 100; /* 1 ms enough? */

        while (--wait) {
                if ((bus_space_read_1(iot, ioh, G2STAT) & (G2STAT_BUSY | G2STAT_MBOX_EMPTY))
                    == (G2STAT_MBOX_EMPTY))
                        break;
                delay(10);
        }
        if (!wait) {
                printf("%s: board not responding\n", device_xname(sc->sc_dev));
                Debugger();
        }

        bus_space_write_4(iot, ioh, MBOXOUT0, cmd);
        bus_space_write_1(iot, ioh, G2CNTRL, G2CNTRL_SET_HOST_READY);
        bus_space_write_1(iot, ioh, ATTN, OP_IMMED |
                ecb->xs->xs_periph->periph_target);

        if ((ecb->xs->xs_control & XS_CTL_POLL) == 0)
                callout_reset(&ecb->xs->xs_callout,
                    mstohz(ecb->timeout), ahb_timeout, ecb);
}

/*
 * Catch an interrupt from the adaptor
 */
static int
ahbintr(void *arg)
{
        struct ahb_softc *sc = arg;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        struct ahb_ecb *ecb;
        u_char ahbstat;
        u_int32_t mboxval;

#ifdef  AHBDEBUG
        printf("%s: ahbintr ", device_xname(sc->sc_dev));
#endif /* AHBDEBUG */

        if ((bus_space_read_1(iot, ioh, G2STAT) & G2STAT_INT_PEND) == 0)
                return 0;

        for (;;) {
                /*
                 * First get all the information and then
                 * acknowledge the interrupt
                 */
                ahbstat = bus_space_read_1(iot, ioh, G2INTST);
                mboxval = bus_space_read_4(iot, ioh, MBOXIN0);
                bus_space_write_1(iot, ioh, G2CNTRL, G2CNTRL_CLEAR_EISA_INT);

#ifdef  AHBDEBUG
                printf("status = 0x%x ", ahbstat);
#endif /* AHBDEBUG */

                /*
                 * Process the completed operation
                 */
                switch (ahbstat & G2INTST_INT_STAT) {
                case AHB_ECB_OK:
                case AHB_ECB_RECOVERED:
                case AHB_ECB_ERR:
                        ecb = ahb_ecb_lookup(sc, mboxval);
                        if (!ecb) {
                                aprint_error_dev(sc->sc_dev,
                                    "BAD ECB RETURNED!\n");
                                goto next; /* whatever it was, it'll timeout */
                        }
                        break;

                case AHB_IMMED_ERR:
                        ecb = sc->sc_immed_ecb;
                        sc->sc_immed_ecb = 0;
                        ecb->flags |= ECB_IMMED_FAIL;
                        break;

                case AHB_IMMED_OK:
                        ecb = sc->sc_immed_ecb;
                        sc->sc_immed_ecb = 0;
                        break;

                default:
                        aprint_error_dev(sc->sc_dev,
                            "unexpected interrupt %x\n", ahbstat);
                        goto next;
                }

                callout_stop(&ecb->xs->xs_callout);
                ahb_done(sc, ecb);

        next:
                if ((bus_space_read_1(iot, ioh, G2STAT) & G2STAT_INT_PEND) == 0)
                        return 1;
        }
}

static inline void
ahb_reset_ecb(struct ahb_softc *sc, struct ahb_ecb *ecb)
{

        ecb->flags = 0;
}

/*
 * A ecb (and hence a mbx-out is put onto the
 * free list.
 */
static void
ahb_free_ecb(struct ahb_softc *sc, struct ahb_ecb *ecb)
{
        int s;

        s = splbio();
        ahb_reset_ecb(sc, ecb);
        TAILQ_INSERT_HEAD(&sc->sc_free_ecb, ecb, chain);
        splx(s);
}

/*
 * Create a set of ecbs and add them to the free list.
 */
static int
ahb_init_ecb(struct ahb_softc *sc, struct ahb_ecb *ecb)
{
        bus_dma_tag_t dmat = sc->sc_dmat;
        int hashnum, error;

        /*
         * Create the DMA map for this ECB.
         */
        error = bus_dmamap_create(dmat, AHB_MAXXFER, AHB_NSEG, AHB_MAXXFER,
            0, BUS_DMA_NOWAIT|BUS_DMA_ALLOCNOW, &ecb->dmamap_xfer);
        if (error) {
                aprint_error_dev(sc->sc_dev, "can't create ecb dmamap_xfer\n");
                return (error);
        }

        ecb->ecb_dma_addr = sc->sc_dmamap_ecb->dm_segs[0].ds_addr +
            AHB_ECB_OFF(ecb);

        /*
         * put in the phystokv hash table
         * Never gets taken out.
         */
        hashnum = ECB_HASH(ecb->ecb_dma_addr);
        ecb->nexthash = sc->sc_ecbhash[hashnum];
        sc->sc_ecbhash[hashnum] = ecb;
        ahb_reset_ecb(sc, ecb);
        return (0);
}

static int
ahb_create_ecbs(struct ahb_softc *sc, struct ahb_ecb *ecbstore, int count)
{
        struct ahb_ecb *ecb;
        int i, error;

        memset(ecbstore, 0, sizeof(struct ahb_ecb) * count);
        for (i = 0; i < count; i++) {
                ecb = &ecbstore[i];
                if ((error = ahb_init_ecb(sc, ecb)) != 0) {
                        aprint_error_dev(sc->sc_dev,
                            "unable to initialize ecb, error = %d\n", error);
                        goto out;
                }
                TAILQ_INSERT_TAIL(&sc->sc_free_ecb, ecb, chain);
        }
 out:
        return (i);
}

/*
 * Get a free ecb
 *
 * If there are none, see if we can allocate a new one. If so, put it in the
 * hash table too otherwise either return an error or sleep.
 */
static struct ahb_ecb *
ahb_get_ecb(struct ahb_softc *sc)
{
        struct ahb_ecb *ecb;
        int s;

        s = splbio();
        ecb = TAILQ_FIRST(&sc->sc_free_ecb);
        if (ecb != NULL) {
                TAILQ_REMOVE(&sc->sc_free_ecb, ecb, chain);
                ecb->flags |= ECB_ALLOC;
        }
        splx(s);
        return (ecb);
}

/*
 * Lookup and return the ECB that has the specified DMA address.
 */
static struct ahb_ecb *
ahb_ecb_lookup(struct ahb_softc *sc, uint32_t ecb_phys)
{
        int hashnum = ECB_HASH(ecb_phys);
        struct ahb_ecb *ecb = sc->sc_ecbhash[hashnum];

        while (ecb) {
                if (ecb->ecb_dma_addr == ecb_phys)
                        break;
                ecb = ecb->nexthash;
        }
        return ecb;
}

/*
 * We have a ecb which has been processed by the adaptor, now we look to see
 * how the operation went.
 */
static void
ahb_done(struct ahb_softc *sc, struct ahb_ecb *ecb)
{
        bus_dma_tag_t dmat = sc->sc_dmat;
        struct scsi_sense_data *s1, *s2;
        struct scsipi_xfer *xs = ecb->xs;

        SC_DEBUG(xs->xs_periph, SCSIPI_DB2, ("ahb_done\n"));

        bus_dmamap_sync(dmat, sc->sc_dmamap_ecb,
            AHB_ECB_OFF(ecb), sizeof(struct ahb_ecb),
            BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE);

        /*
         * If we were a data transfer, unload the map that described
         * the data buffer.
         */
        if (xs->datalen) {
                bus_dmamap_sync(dmat, ecb->dmamap_xfer, 0,
                    ecb->dmamap_xfer->dm_mapsize,
                    (xs->xs_control & XS_CTL_DATA_IN) ? BUS_DMASYNC_POSTREAD :
                    BUS_DMASYNC_POSTWRITE);
                bus_dmamap_unload(dmat, ecb->dmamap_xfer);
        }

        /*
         * Otherwise, put the results of the operation
         * into the xfer and call whoever started it
         */
        if ((ecb->flags & ECB_ALLOC) == 0) {
                aprint_error_dev(sc->sc_dev, "exiting ecb not allocated!\n");
                Debugger();
        }
        if (ecb->flags & ECB_IMMED) {
                if (ecb->flags & ECB_IMMED_FAIL)
                        xs->error = XS_DRIVER_STUFFUP;
                goto done;
        }
        if (xs->error == XS_NOERROR) {
                if (ecb->ecb_status.host_stat != HS_OK) {
                        switch (ecb->ecb_status.host_stat) {
                        case HS_TIMED_OUT:      /* No response */
                                xs->error = XS_SELTIMEOUT;
                                break;
                        default:        /* Other scsi protocol messes */
                                printf("%s: host_stat %x\n",
                                    device_xname(sc->sc_dev),
                                    ecb->ecb_status.host_stat);
                                xs->error = XS_DRIVER_STUFFUP;
                        }
                } else if (ecb->ecb_status.target_stat != SCSI_OK) {
                        switch (ecb->ecb_status.target_stat) {
                        case SCSI_CHECK:
                                s1 = &ecb->ecb_sense;
                                s2 = &xs->sense.scsi_sense;
                                *s2 = *s1;
                                xs->error = XS_SENSE;
                                break;
                        case SCSI_BUSY:
                                xs->error = XS_BUSY;
                                break;
                        default:
                                printf("%s: target_stat %x\n",
                                    device_xname(sc->sc_dev),
                                    ecb->ecb_status.target_stat);
                                xs->error = XS_DRIVER_STUFFUP;
                        }
                } else
                        xs->resid = 0;
        }
done:
        ahb_free_ecb(sc, ecb);
        scsipi_done(xs);
}

/*
 * Start the board, ready for normal operation
 */
static int
ahb_find(bus_space_tag_t iot, bus_space_handle_t ioh,
    struct ahb_probe_data *sc)
{
        u_char intdef;
        int i, irq, ist, busid;
        int wait = 1000;        /* 1 sec enough? */

        bus_space_write_1(iot, ioh, PORTADDR, PORTADDR_ENHANCED);

#define NO_NO 1
#ifdef NO_NO
        /*
         * reset board, If it doesn't respond, assume
         * that it's not there.. good for the probe
         */
        bus_space_write_1(iot, ioh, G2CNTRL, G2CNTRL_HARD_RESET);
        delay(1000);
        bus_space_write_1(iot, ioh, G2CNTRL, 0);
        delay(10000);
        while (--wait) {
                if ((bus_space_read_1(iot, ioh, G2STAT) & G2STAT_BUSY) == 0)
                        break;
                delay(1000);
        }
        if (!wait) {
#ifdef  AHBDEBUG
                printf("ahb_find: No answer from aha1742 board\n");
#endif /* AHBDEBUG */
                return ENXIO;
        }
        i = bus_space_read_1(iot, ioh, MBOXIN0);
        if (i) {
                printf("self test failed, val = 0x%x\n", i);
                return EIO;
        }

        /* Set it again, just to be sure. */
        bus_space_write_1(iot, ioh, PORTADDR, PORTADDR_ENHANCED);
#endif

        while (bus_space_read_1(iot, ioh, G2STAT) & G2STAT_INT_PEND) {
                printf(".");
                bus_space_write_1(iot, ioh, G2CNTRL, G2CNTRL_CLEAR_EISA_INT);
                delay(10000);
        }

        intdef = bus_space_read_1(iot, ioh, INTDEF);
        switch (intdef & 0x07) {
        case INT9:
                irq = 9;
                break;
        case INT10:
                irq = 10;
                break;
        case INT11:
                irq = 11;
                break;
        case INT12:
                irq = 12;
                break;
        case INT14:
                irq = 14;
                break;
        case INT15:
                irq = 15;
                break;
        default:
                printf("illegal int setting %x\n", intdef);
                return EIO;
        }

        /*
         * On EISA, edge triggered interrupts are signalled by the rising
         * edge of the interrupt signal, while level tiggered interrupts
         * are signalled so long as the interrupt signal is driven low.
         *
         * So, if the controller is configured for active-high interrupts,
         * that is "edge trigger" in our parlance, while active-low would
         * be "level trigger".
         */
        if (intdef & INTHIGH) {
                ist = IST_EDGE;
        } else {
                ist = IST_LEVEL;
        }

        bus_space_write_1(iot, ioh, INTDEF, (intdef | INTEN));  /* make sure we can interrupt */

        /* who are we on the scsi bus? */
        busid = (bus_space_read_1(iot, ioh, SCSIDEF) & HSCSIID);

        /* if we want to return data, do so now */
        if (sc) {
                sc->sc_irq = irq;
                sc->sc_ist = ist;
                sc->sc_scsi_dev = busid;
        }

        /*
         * Note that we are going and return (to probe)
         */
        return 0;
}

static int
ahb_init(struct ahb_softc *sc)
{
        bus_dma_segment_t seg;
        int i, error, rseg;

#define ECBSIZE         (AHB_ECB_MAX * sizeof(struct ahb_ecb))

        /*
         * Allocate the ECBs.
         */
        if ((error = bus_dmamem_alloc(sc->sc_dmat, ECBSIZE,
            PAGE_SIZE, 0, &seg, 1, &rseg, BUS_DMA_NOWAIT)) != 0) {
                aprint_error_dev(sc->sc_dev,
                    "unable to allocate ecbs, error = %d\n", error);
                return (error);
        }
        if ((error = bus_dmamem_map(sc->sc_dmat, &seg, rseg,
            ECBSIZE, (void **)&sc->sc_ecbs,
            BUS_DMA_NOWAIT|BUS_DMA_COHERENT)) != 0) {
                aprint_error_dev(sc->sc_dev,
                    "unable to map ecbs, error = %d\n", error);
                return (error);
        }

        /*
         * Create and load the DMA map used for the ecbs.
         */
        if ((error = bus_dmamap_create(sc->sc_dmat, ECBSIZE,
            1, ECBSIZE, 0, BUS_DMA_NOWAIT, &sc->sc_dmamap_ecb)) != 0) {
                aprint_error_dev(sc->sc_dev,
                    "unable to create ecb DMA map, error = %d\n", error);
                return (error);
        }
        if ((error = bus_dmamap_load(sc->sc_dmat, sc->sc_dmamap_ecb,
            sc->sc_ecbs, ECBSIZE, NULL, BUS_DMA_NOWAIT)) != 0) {
                aprint_error_dev(sc->sc_dev,
                    "unable to load ecb DMA map, error = %d\n", error);
                return (error);
        }

#undef ECBSIZE

        /*
         * Initialize the ecbs.
         */
        i = ahb_create_ecbs(sc, sc->sc_ecbs, AHB_ECB_MAX);
        if (i == 0) {
                aprint_error_dev(sc->sc_dev, "unable to create ecbs\n");
                return (ENOMEM);
        } else if (i != AHB_ECB_MAX) {
                printf("%s: WARNING: only %d of %d ecbs created\n",
                    device_xname(sc->sc_dev), i, AHB_ECB_MAX);
        }

        sc->sc_adapter.adapt_openings = i;

        return (0);
}

static void
ahbminphys(struct buf *bp)
{

        if (bp->b_bcount > AHB_MAXXFER)
                bp->b_bcount = AHB_MAXXFER;
        minphys(bp);
}

/*
 * start a scsi operation given the command and the data address.  Also needs
 * the unit, target and lu.
 */
static void
ahb_scsipi_request(struct scsipi_channel *chan, scsipi_adapter_req_t req,
    void *arg)
{
        struct scsipi_xfer *xs;
        struct scsipi_periph *periph;
        struct ahb_softc *sc = device_private(chan->chan_adapter->adapt_dev);
        bus_dma_tag_t dmat = sc->sc_dmat;
        struct ahb_ecb *ecb;
        int error, seg, flags, s;

        switch (req) {
        case ADAPTER_REQ_RUN_XFER:
                xs = arg;
                periph = xs->xs_periph;
                flags = xs->xs_control;

                SC_DEBUG(periph, SCSIPI_DB2, ("ahb_scsipi_request\n"));

                /* Get an ECB to use. */
                ecb = ahb_get_ecb(sc);
#ifdef DIAGNOSTIC
                /*
                 * This should never happen as we track the resources
                 * in the mid-layer.
                 */
                if (ecb == NULL) {
                        scsipi_printaddr(periph);
                        printf("unable to allocate ecb\n");
                        panic("ahb_scsipi_request");
                }
#endif

                ecb->xs = xs;
                ecb->timeout = xs->timeout;

                /*
                 * If it's a reset, we need to do an 'immediate'
                 * command, and store its ecb for later
                 * if there is already an immediate waiting,
                 * then WE must wait
                 */
                if (flags & XS_CTL_RESET) {
                        ecb->flags |= ECB_IMMED;
                        if (sc->sc_immed_ecb) {
                                ahb_free_ecb(sc, ecb);
                                xs->error = XS_BUSY;
                                scsipi_done(xs);
                                return;
                        }
                        sc->sc_immed_ecb = ecb;

                        s = splbio();
                        ahb_send_immed(sc, AHB_TARG_RESET, ecb);
                        splx(s);

                        if ((flags & XS_CTL_POLL) == 0)
                                return;

                        /*
                         * If we can't use interrupts, poll on completion
                         */
                        if (ahb_poll(sc, xs, ecb->timeout))
                                ahb_timeout(ecb);
                        return;
                }

                /*
                 * Put all the arguments for the xfer in the ecb
                 */
                if (xs->cmdlen > sizeof(ecb->scsi_cmd)) {
                        aprint_error_dev(sc->sc_dev,
                            "cmdlen %d too large for ECB\n", xs->cmdlen);
                        xs->error = XS_DRIVER_STUFFUP;
                        goto out_bad;
                }
                ecb->opcode = ECB_SCSI_OP;
                ecb->opt1 = ECB_SES /*| ECB_DSB*/ | ECB_ARS;
                ecb->opt2 = periph->periph_lun | ECB_NRB;
                memcpy(&ecb->scsi_cmd, xs->cmd,
                    ecb->scsi_cmd_length = xs->cmdlen);
                ecb->sense_ptr = ecb->ecb_dma_addr +
                    offsetof(struct ahb_ecb, ecb_sense);
                ecb->req_sense_length = sizeof(ecb->ecb_sense);
                ecb->status = ecb->ecb_dma_addr +
                    offsetof(struct ahb_ecb, ecb_status);
                ecb->ecb_status.host_stat = 0x00;
                ecb->ecb_status.target_stat = 0x00;

                if (xs->datalen) {
                        /*
                         * Map the DMA transfer.
                         */
#ifdef TFS
                        if (flags & XS_CTL_DATA_UIO) {
                                error = bus_dmamap_load_uio(sc->sc_dmat,
                                    ecb->dmamap_xfer, (struct uio *)xs->data,
                                    BUS_DMA_NOWAIT);
                        } else
#endif /* TFS */
                        {
                                error = bus_dmamap_load(sc->sc_dmat,
                                    ecb->dmamap_xfer, xs->data, xs->datalen,
                                    NULL, BUS_DMA_NOWAIT);
                        }

                        switch (error) {
                        case 0:
                                break;

                        case ENOMEM:
                        case EAGAIN:
                                xs->error = XS_RESOURCE_SHORTAGE;
                                goto out_bad;

                        default:
                                xs->error = XS_DRIVER_STUFFUP;
                                aprint_error_dev(sc->sc_dev,
                                    "error %d loading DMA map\n", error);
 out_bad:
                                ahb_free_ecb(sc, ecb);
                                scsipi_done(xs);
                                return;
                        }

                        bus_dmamap_sync(dmat, ecb->dmamap_xfer, 0,
                            ecb->dmamap_xfer->dm_mapsize,
                            (flags & XS_CTL_DATA_IN) ? BUS_DMASYNC_PREREAD :
                            BUS_DMASYNC_PREWRITE);

                        /*
                         * Load the hardware scatter/gather map with the
                         * contents of the DMA map.
                         */
                        for (seg = 0; seg < ecb->dmamap_xfer->dm_nsegs; seg++) {
                                ecb->ahb_dma[seg].seg_addr =
                                    ecb->dmamap_xfer->dm_segs[seg].ds_addr;
                                ecb->ahb_dma[seg].seg_len =
                                    ecb->dmamap_xfer->dm_segs[seg].ds_len;
                        }

                        ecb->data_addr = ecb->ecb_dma_addr +
                            offsetof(struct ahb_ecb, ahb_dma);
                        ecb->data_length = ecb->dmamap_xfer->dm_nsegs *
                            sizeof(struct ahb_dma_seg);
                        ecb->opt1 |= ECB_S_G;
                } else {        /* No data xfer, use non S/G values */
                        ecb->data_addr = 0;
                        ecb->data_length = 0;
                }
                ecb->link_addr = 0;

                bus_dmamap_sync(sc->sc_dmat, sc->sc_dmamap_ecb,
                    AHB_ECB_OFF(ecb), sizeof(struct ahb_ecb),
                    BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);

                s = splbio();
                ahb_send_mbox(sc, OP_START_ECB, ecb);
                splx(s);

                if ((flags & XS_CTL_POLL) == 0)
                        return;

                /*
                 * If we can't use interrupts, poll on completion
                 */
                if (ahb_poll(sc, xs, ecb->timeout)) {
                        ahb_timeout(ecb);
                        if (ahb_poll(sc, xs, ecb->timeout))
                                ahb_timeout(ecb);
                }
                return;

        case ADAPTER_REQ_GROW_RESOURCES:
                /* XXX Not supported. */
                return;

        case ADAPTER_REQ_SET_XFER_MODE:
                /* XXX How do we do this? */
                return;
        }
}

/*
 * Function to poll for command completion when in poll mode
 */
static int
ahb_poll(struct ahb_softc *sc, struct scsipi_xfer *xs, int count)
{                               /* in msec  */
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;

        while (count) {
                /*
                 * If we had interrupts enabled, would we
                 * have got an interrupt?
                 */
                if (bus_space_read_1(iot, ioh, G2STAT) & G2STAT_INT_PEND)
                        ahbintr(sc);
                if (xs->xs_status & XS_STS_DONE)
                        return 0;
                delay(1000);
                count--;
        }
        return 1;
}

static void
ahb_timeout(void *arg)
{
        struct ahb_ecb *ecb = arg;
        struct scsipi_xfer *xs = ecb->xs;
        struct scsipi_periph *periph = xs->xs_periph;
        struct ahb_softc *sc =
            device_private(periph->periph_channel->chan_adapter->adapt_dev);
        int s;

        scsipi_printaddr(periph);
        printf("timed out");

        s = splbio();

        if (ecb->flags & ECB_IMMED) {
                printf("\n");
                ecb->flags |= ECB_IMMED_FAIL;
                /* XXX Must reset! */
        } else

        /*
         * If it has been through before, then
         * a previous abort has failed, don't
         * try abort again
         */
        if (ecb->flags & ECB_ABORT) {
                /* abort timed out */
                printf(" AGAIN\n");
                /* XXX Must reset! */
        } else {
                /* abort the operation that has timed out */
                printf("\n");
                ecb->xs->error = XS_TIMEOUT;
                ecb->timeout = AHB_ABORT_TIMEOUT;
                ecb->flags |= ECB_ABORT;
                ahb_send_mbox(sc, OP_ABORT_ECB, ecb);
        }

        splx(s);
}