/*      $NetBSD: seagate.c,v 1.77 2022/09/25 17:11:48 thorpej Exp $     */

/*
 * ST01/02, Future Domain TMC-885, TMC-950 SCSI driver
 *
 * Copyright 1994, Charles M. Hannum (mycroft@ai.mit.edu)
 * Copyright 1994, Kent Palmkvist (kentp@isy.liu.se)
 * Copyright 1994, Robert Knier (rknier@qgraph.com)
 * Copyright 1992, 1994 Drew Eckhardt (drew@colorado.edu)
 * Copyright 1994, Julian Elischer (julian@tfs.com)
 *
 * Others that has contributed by example code is
 *              Glen Overby (overby@cray.com)
 *              Tatu Yllnen
 *              Brian E Litzinger
 *
 * 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 DEVELOPERS ``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 DEVELOPERS 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.
 */

/*
 * kentp  940307 alpha version based on newscsi-03 version of Julians SCSI-code
 * kentp  940314 Added possibility to not use messages
 * rknier 940331 Added fast transfer code
 * rknier 940407 Added assembler coded data transfers
 */

/*
 * What should really be done:
 *
 * Add missing tests for timeouts
 * Restructure interrupt enable/disable code (runs to long with int disabled)
 * Find bug? giving problem with tape status
 * Add code to handle Future Domain 840, 841, 880 and 881
 * adjust timeouts (startup is very slow)
 * add code to use tagged commands in SCSI2
 * Add code to handle slow devices better (sleep if device not disconnecting)
 * Fix unnecessary interrupts
 */

/*
 * Note to users trying to share a disk between DOS and unix:
 * The ST01/02 is a translating host-adapter. It is not giving DOS
 * the same number of heads/tracks/sectors as specified by the disk.
 * It is therefore important to look at what numbers DOS thinks the
 * disk has. Use these to disklabel your disk in an appropriate manner
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: seagate.c,v 1.77 2022/09/25 17:11:48 thorpej Exp $");

#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/queue.h>
#include <sys/kmem.h>

#include <sys/intr.h>
#include <machine/pio.h>

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

#include <dev/isa/isareg.h>
#include <dev/isa/isavar.h>     /* XXX USES ISA HOLE DIRECTLY */

#define SEA_SCB_MAX     32      /* allow maximally 8 scsi control blocks */
#define SCB_TABLE_SIZE  8       /* start with 8 scb entries in table */
#define BLOCK_SIZE      512     /* size of READ/WRITE areas on SCSI card */

/*
 * defining SEA_BLINDTRANSFER will make DATA IN and DATA OUT to be done with
 * blind transfers, i.e. no check is done for scsi phase changes. This will
 * result in data loss if the scsi device does not send its data using
 * BLOCK_SIZE bytes at a time.
 * If SEA_BLINDTRANSFER defined and SEA_ASSEMBLER also defined will result in
 * the use of blind transfers coded in assembler. SEA_ASSEMBLER is no good
 * without SEA_BLINDTRANSFER defined.
 */
#define SEA_BLINDTRANSFER       /* do blind transfers */
#define SEA_ASSEMBLER           /* Use assembly code for fast transfers */

/*
 * defining SEA_NOMSGS causes messages not to be used (thereby disabling
 * disconnects)
 */
#undef  SEA_NOMSGS

/*
 * defining SEA_NODATAOUT makes dataout phase being aborted
 */
#undef  SEA_NODATAOUT

/* Debugging definitions. Should not be used unless you want a lot of
   printouts even under normal conditions */

#undef  SEA_DEBUGQUEUE          /* Display info about queue-lengths */

/******************************* board definitions **************************/
/*
 * CONTROL defines
 */
#define CMD_RST         0x01            /* scsi reset */
#define CMD_SEL         0x02            /* scsi select */
#define CMD_BSY         0x04            /* scsi busy */
#define CMD_ATTN        0x08            /* scsi attention */
#define CMD_START_ARB   0x10            /* start arbitration bit */
#define CMD_EN_PARITY   0x20            /* enable scsi parity generation */
#define CMD_INTR        0x40            /* enable scsi interrupts */
#define CMD_DRVR_ENABLE 0x80            /* scsi enable */

/*
 * STATUS
 */
#define STAT_BSY        0x01            /* scsi busy */
#define STAT_MSG        0x02            /* scsi msg */
#define STAT_IO         0x04            /* scsi I/O */
#define STAT_CD         0x08            /* scsi C/D */
#define STAT_REQ        0x10            /* scsi req */
#define STAT_SEL        0x20            /* scsi select */
#define STAT_PARITY     0x40            /* parity error bit */
#define STAT_ARB_CMPL   0x80            /* arbitration complete bit */

/*
 * REQUESTS
 */
#define PH_DATAOUT      (0)
#define PH_DATAIN       (STAT_IO)
#define PH_CMD          (STAT_CD)
#define PH_STAT         (STAT_CD | STAT_IO)
#define PH_MSGOUT       (STAT_MSG | STAT_CD)
#define PH_MSGIN        (STAT_MSG | STAT_CD | STAT_IO)

#define PH_MASK         (STAT_MSG | STAT_CD | STAT_IO)

#define PH_INVALID      0xff

#define SEA_RAMOFFSET   0x00001800

#define BASE_CMD        (CMD_INTR | CMD_EN_PARITY)

#define SEAGATE         1       /* Seagate ST0[12] */
#define FDOMAIN         2       /* Future Domain TMC-{885,950} */
#define FDOMAIN840      3       /* Future Domain TMC-{84[01],88[01]} */

/******************************************************************************/

/* scsi control block used to keep info about a scsi command */
struct sea_scb {
        u_char *data;                   /* position in data buffer so far */
        int datalen;                    /* bytes remaining to transfer */
        TAILQ_ENTRY(sea_scb) chain;
        struct scsipi_xfer *xs;         /* the scsipi_xfer for this cmd */
        int flags;                      /* status of the instruction */
#define SCB_FREE        0
#define SCB_ACTIVE      1
#define SCB_ABORTED     2
#define SCB_TIMEOUT     4
#define SCB_ERROR       8
};

/*
 * data structure describing current status of the scsi bus. One for each
 * controller card.
 */
struct sea_softc {
        device_t sc_dev;
        void *sc_ih;

        int type;                       /* board type */
        void *  maddr;                  /* Base address for card */
        void *  maddr_cr_sr;            /* Address of control and status reg */
        void *  maddr_dr;               /* Address of data register */

        struct scsipi_adapter sc_adapter;
        struct scsipi_channel sc_channel;

        TAILQ_HEAD(, sea_scb) free_list, ready_list, nexus_list;
        struct sea_scb *nexus;          /* currently connected command */
        int numscbs;                    /* number of scsi control blocks */
        struct sea_scb scb[SCB_TABLE_SIZE];

        int our_id;                     /* our scsi id */
        u_char our_id_mask;
        volatile u_char busy[8];        /* index=target, bit=lun, Keep track of
                                           busy luns at device target */
};

/* flag showing if main routine is running. */
static volatile int main_running = 0;

#define STATUS  (*(volatile u_char *)sea->maddr_cr_sr)
#define CONTROL STATUS
#define DATA    (*(volatile u_char *)sea->maddr_dr)

/*
 * These are "special" values for the tag parameter passed to sea_select
 * Not implemented right now.
 */
#define TAG_NEXT        -1      /* Use next free tag */
#define TAG_NONE        -2      /*
                                 * Establish I_T_L nexus instead of I_T_L_Q
                                 * even on SCSI-II devices.
                                 */

typedef struct {
        const char *signature;
        int offset, length;
        int type;
} BiosSignature;

/*
 * Signatures for automatic recognition of board type
 */
static const BiosSignature signatures[] = {
{"ST01 v1.7  (C) Copyright 1987 Seagate", 15, 37, SEAGATE},
{"SCSI BIOS 2.00  (C) Copyright 1987 Seagate", 15, 40, SEAGATE},

/*
 * The following two lines are NOT mistakes. One detects ROM revision
 * 3.0.0, the other 3.2. Since seagate has only one type of SCSI adapter,
 * and this is not going to change, the "SEAGATE" and "SCSI" together
 * are probably "good enough"
 */
{"SEAGATE SCSI BIOS ", 16, 17, SEAGATE},
{"SEAGATE SCSI BIOS ", 17, 17, SEAGATE},

/*
 * However, future domain makes several incompatible SCSI boards, so specific
 * signatures must be used.
 */
{"FUTURE DOMAIN CORP. (C) 1986-1989 V5.0C2/14/89", 5, 45, FDOMAIN},
{"FUTURE DOMAIN CORP. (C) 1986-1989 V6.0A7/28/89", 5, 46, FDOMAIN},
{"FUTURE DOMAIN CORP. (C) 1986-1990 V6.0105/31/90",5, 47, FDOMAIN},
{"FUTURE DOMAIN CORP. (C) 1986-1990 V6.0209/18/90",5, 47, FDOMAIN},
{"FUTURE DOMAIN CORP. (C) 1986-1990 V7.009/18/90", 5, 46, FDOMAIN},
{"FUTURE DOMAIN CORP. (C) 1992 V8.00.004/02/92",   5, 44, FDOMAIN},
{"FUTURE DOMAIN TMC-950",                          5, 21, FDOMAIN},
};

#define nsignatures     (sizeof(signatures) / sizeof(signatures[0]))

#ifdef notdef
static const char *bases[] = {
        (char *) 0xc8000, (char *) 0xca000, (char *) 0xcc000,
        (char *) 0xce000, (char *) 0xdc000, (char *) 0xde000
};

#define nbases          (sizeof(bases) / sizeof(bases[0]))
#endif

int seaintr(void *);
void sea_scsipi_request(struct scsipi_channel *, scsipi_adapter_req_t, void *);
void sea_timeout(void *);
void sea_done(struct sea_softc *, struct sea_scb *);
struct sea_scb *sea_get_scb(struct sea_softc *, int);
void sea_free_scb(struct sea_softc *, struct sea_scb *, int);
static void sea_main(void);
static void sea_information_transfer(struct sea_softc *);
int sea_poll(struct sea_softc *, struct scsipi_xfer *, int);
void sea_init(struct sea_softc *);
void sea_send_scb(struct sea_softc *sea, struct sea_scb *scb);
void sea_reselect(struct sea_softc *sea);
int sea_select(struct sea_softc *sea, struct sea_scb *scb);
int sea_transfer_pio(struct sea_softc *sea, u_char *phase,
    int *count, u_char **data);
int sea_abort(struct sea_softc *, struct sea_scb *scb);

void    sea_grow_scb(struct sea_softc *);

int     seaprobe(device_t, cfdata_t, void *);
void    seaattach(device_t, device_t, void *);

CFATTACH_DECL_NEW(sea, sizeof(struct sea_softc),
    seaprobe, seaattach, NULL, NULL);

extern struct cfdriver sea_cd;

#ifdef SEA_DEBUGQUEUE
void
sea_queue_length(struct sea_softc *sea)
{
        struct sea_scb *scb;
        int connected, issued, disconnected;

        connected = sea->nexus ? 1 : 0;
        for (scb = sea->ready_list.tqh_first, issued = 0; scb;
            scb = scb->chain.tqe_next, issued++);
        for (scb = sea->nexus_list.tqh_first, disconnected = 0; scb;
            scb = scb->chain.tqe_next, disconnected++);
        printf("%s: length: %d/%d/%d\n", device_xname(sea->sc_dev), connected,
            issued, disconnected);
}
#endif

/*
 * Check if the device can be found at the port given and if so, detect the
 * type the type of board.  Set it up ready for further work. Takes the isa_dev
 * structure from autoconf as an argument.
 * Returns 1 if card recognized, 0 if errors.
 */
int
seaprobe(device_t parent, cfdata_t match, void *aux)
{
        struct isa_attach_args *ia = aux;
        int i, type = 0;
        void *maddr;

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

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

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

        /* XXX XXX XXX */
        maddr = ISA_HOLE_VADDR(ia->ia_iomem[0].ir_addr);

        /* check board type */  /* No way to define this through config */
        for (i = 0; i < nsignatures; i++)
                if (!memcmp((char *)maddr + signatures[i].offset,
                    signatures[i].signature, signatures[i].length)) {
                        type = signatures[i].type;
                        break;
                }

        /* Find controller and data memory addresses */
        switch (type) {
        case SEAGATE:
        case FDOMAIN840:
        case FDOMAIN:
                break;
        default:
#ifdef SEA_DEBUG
                printf("seaprobe: board type unknown at address %p\n", maddr);
#endif
                return 0;
        }

        ia->ia_niomem = 1;
        ia->ia_iomem[0].ir_size = 0x2000;

        ia->ia_nirq = 1;

        ia->ia_nio = 0;
        ia->ia_ndrq = 0;

        return 1;
}

/*
 * Attach all sub-devices we can find
 */
void
seaattach(device_t parent, device_t self, void *aux)
{
        struct isa_attach_args *ia = aux;
        struct sea_softc *sea = device_private(self);
        struct scsipi_adapter *adapt = &sea->sc_adapter;
        struct scsipi_channel *chan = &sea->sc_channel;
        int i;

        aprint_naive("\n");
        sea->sc_dev = self;

        /* XXX XXX XXX */
        sea->maddr = ISA_HOLE_VADDR(ia->ia_iomem[0].ir_addr);

        /* check board type */  /* No way to define this through config */
        for (i = 0; i < nsignatures; i++)
                if (!memcmp((char *)sea->maddr + signatures[i].offset,
                    signatures[i].signature, signatures[i].length)) {
                        sea->type = signatures[i].type;
                        break;
                }

        /* Find controller and data memory addresses */
        switch (sea->type) {
        case SEAGATE:
        case FDOMAIN840:
                sea->maddr_cr_sr =
                    (void *) (((u_char *)sea->maddr) + 0x1a00);
                sea->maddr_dr =
                    (void *) (((u_char *)sea->maddr) + 0x1c00);
                break;
        case FDOMAIN:
                sea->maddr_cr_sr =
                    (void *) (((u_char *)sea->maddr) + 0x1c00);
                sea->maddr_dr =
                    (void *) (((u_char *)sea->maddr) + 0x1e00);
                break;
        default:
#ifdef DEBUG
                printf("%s: board type unknown at address %p\n",
                    device_xname(sea->sc_dev), sea->maddr);
#endif
                return;
        }

        /* Test controller RAM (works the same way on future domain cards?) */
        *((u_char *)sea->maddr + SEA_RAMOFFSET) = 0xa5;
        *((u_char *)sea->maddr + SEA_RAMOFFSET + 1) = 0x5a;

        if ((*((u_char *)sea->maddr + SEA_RAMOFFSET) != 0xa5) ||
            (*((u_char *)sea->maddr + SEA_RAMOFFSET + 1) != 0x5a)) {
                aprint_error_dev(sea->sc_dev, "board RAM failure\n");
                return;
        }

        sea_init(sea);

        /*
         * Fill in the scsipi_adapter.
         */
        memset(adapt, 0, sizeof(*adapt));
        adapt->adapt_dev = sea->sc_dev;
        adapt->adapt_nchannels = 1;
        adapt->adapt_openings = sea->numscbs;
        adapt->adapt_max_periph = 1;
        adapt->adapt_request = sea_scsipi_request;
        adapt->adapt_minphys = minphys;

        /*
         * 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 = sea->our_id;
        chan->chan_flags = SCSIPI_CHAN_CANGROW;

        aprint_normal("\n");

        sea->sc_ih = isa_intr_establish(ia->ia_ic, ia->ia_irq[0].ir_irq,
            IST_EDGE, IPL_BIO, seaintr, sea);

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

/*
 * Catch an interrupt from the adaptor
 */
int
seaintr(void *arg)
{
        struct sea_softc *sea = arg;

#ifdef DEBUG    /* extra overhead, and only needed for intr debugging */
        if ((STATUS & STAT_PARITY) == 0 &&
            (STATUS & (STAT_SEL | STAT_IO)) != (STAT_SEL | STAT_IO))
                return 0;
#endif

loop:
        /* dispatch to appropriate routine if found and done=0 */
        /* should check to see that this card really caused the interrupt */

        if (STATUS & STAT_PARITY) {
                /* Parity error interrupt */
                aprint_error_dev(sea->sc_dev, "parity error\n");
                return 1;
        }

        if ((STATUS & (STAT_SEL | STAT_IO)) == (STAT_SEL | STAT_IO)) {
                /* Reselect interrupt */
                sea_reselect(sea);
                if (!main_running)
                        sea_main();
                goto loop;
        }

        return 1;
}

/*
 * Setup data structures, and reset the board and the SCSI bus.
 */
void
sea_init(struct sea_softc *sea)
{
        int i;

        /* Reset the scsi bus (I don't know if this is needed */
        CONTROL = BASE_CMD | CMD_DRVR_ENABLE | CMD_RST;
        delay(25);      /* hold reset for at least 25 microseconds */
        CONTROL = BASE_CMD;
        delay(10);      /* wait a Bus Clear Delay (800 ns + bus free delay (800 ns) */

        /* Set our id (don't know anything about this) */
        switch (sea->type) {
        case SEAGATE:
                sea->our_id = 7;
                break;
        case FDOMAIN:
        case FDOMAIN840:
                sea->our_id = 6;
                break;
        }
        sea->our_id_mask = 1 << sea->our_id;

        /* init fields used by our routines */
        sea->nexus = 0;
        TAILQ_INIT(&sea->ready_list);
        TAILQ_INIT(&sea->nexus_list);
        TAILQ_INIT(&sea->free_list);
        for (i = 0; i < 8; i++)
                sea->busy[i] = 0x00;

        /* link up the free list of scbs */
        sea->numscbs = SCB_TABLE_SIZE;
        for (i = 0; i < SCB_TABLE_SIZE; i++) {
                TAILQ_INSERT_TAIL(&sea->free_list, &sea->scb[i], chain);
        }
}

/*
 * start a scsi operation given the command and the data address. Also needs
 * the unit, target and lu.
 */
void
sea_scsipi_request(struct scsipi_channel *chan, scsipi_adapter_req_t req,
    void *arg)
{
        struct scsipi_xfer *xs;
        struct scsipi_periph *periph __diagused;
        struct sea_softc *sea = device_private(chan->chan_adapter->adapt_dev);
        struct sea_scb *scb;
        int flags;
        int s;

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

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

                /* XXX Reset not implemented. */
                if (flags & XS_CTL_RESET) {
                        printf("%s: resetting\n", device_xname(sea->sc_dev));
                        xs->error = XS_DRIVER_STUFFUP;
                        scsipi_done(xs);
                        return;
                }

                /* Get an SCB to use. */
                scb = sea_get_scb(sea, flags);
#ifdef DIAGNOSTIC
                /*
                 * This should never happen as we track the resources
                 * in the mid-layer.
                 */
                if (scb == NULL) {
                        scsipi_printaddr(periph);
                        printf("unable to allocate scb\n");
                        panic("sea_scsipi_request");
                }
#endif

                scb->flags = SCB_ACTIVE;
                scb->xs = xs;

                /*
                 * Put all the arguments for the xfer in the scb
                 */
                scb->datalen = xs->datalen;
                scb->data = xs->data;

#ifdef SEA_DEBUGQUEUE
                sea_queue_length(sea);
#endif

                s = splbio();

                sea_send_scb(sea, scb);

                if ((flags & XS_CTL_POLL) == 0) {
                        callout_reset(&scb->xs->xs_callout,
                            mstohz(xs->timeout), sea_timeout, scb);
                        splx(s);
                        return;
                }

                splx(s);

                /*
                 * If we can't use interrupts, poll on completion
                 */
                if (sea_poll(sea, xs, xs->timeout)) {
                        sea_timeout(scb);
                        if (sea_poll(sea, xs, 2000))
                                sea_timeout(scb);
                }
                return;

        case ADAPTER_REQ_GROW_RESOURCES:
                sea_grow_scb(sea);
                return;

        case ADAPTER_REQ_SET_XFER_MODE:
            {
                struct scsipi_xfer_mode *xm = arg;

                /*
                 * We don't support sync or wide or tagged queueing,
                 * so announce that now.
                 */
                xm->xm_mode = 0;
                xm->xm_period = 0;
                xm->xm_offset = 0;
                scsipi_async_event(chan, ASYNC_EVENT_XFER_MODE, xm);
                return;
            }
        }
}

/*
 * Get a free scb. If there are none, see if we can allocate a new one.  If so,
 * put it in the hash table too; otherwise return an error or sleep.
 */
struct sea_scb *
sea_get_scb(struct sea_softc *sea, int flags)
{
        int s;
        struct sea_scb *scb;

        s = splbio();
        if ((scb = TAILQ_FIRST(&sea->free_list)) != NULL)
                TAILQ_REMOVE(&sea->free_list, scb, chain);
        splx(s);

        return (scb);
}

/*
 * Try to send this command to the board. Because this board does not use any
 * mailboxes, this routine simply adds the command to the queue held by the
 * sea_softc structure.
 * A check is done to see if the command contains a REQUEST_SENSE command, and
 * if so the command is put first in the queue, otherwise the command is added
 * to the end of the queue. ?? Not correct ??
 */
void
sea_send_scb(struct sea_softc *sea, struct sea_scb *scb)
{

        TAILQ_INSERT_TAIL(&sea->ready_list, scb, chain);
        /* Try to do some work on the card. */
        if (!main_running)
                sea_main();
}

/*
 * Coroutine that runs as long as more work can be done on the seagate host
 * adapter in a system.  Both sea_scsi_cmd and sea_intr will try to start it in
 * case it is not running.
 */

void
sea_main(void)
{
        struct sea_softc *sea;
        struct sea_scb *scb;
        int done;
        int unit;
        int s;

        main_running = 1;

        /*
         * This should not be run with interrupts disabled, but use the splx
         * code instead.
         */
loop:
        done = 1;
        for (unit = 0; unit < sea_cd.cd_ndevs; unit++) {
                sea = device_lookup_private(&sea_cd, unit);
                if (!sea)
                        continue;
                s = splbio();
                if (!sea->nexus) {
                        /*
                         * Search through the ready_list for a command
                         * destined for a target that's not busy.
                         */
                        for (scb = sea->ready_list.tqh_first; scb;
                            scb = scb->chain.tqe_next) {
                                if ((sea->busy[scb->xs->xs_periph->periph_target] &
                                    (1 << scb->xs->xs_periph->periph_lun)))
                                        continue;

                                /* target/lun is not busy */
                                TAILQ_REMOVE(&sea->ready_list, scb, chain);

                                /* Re-enable interrupts. */
                                splx(s);

                                /*
                                 * Attempt to establish an I_T_L nexus.
                                 * On success, sea->nexus is set.
                                 * On failure, we must add the command
                                 * back to the issue queue so we can
                                 * keep trying.
                                 */

                                /*
                                 * REQUEST_SENSE commands are issued
                                 * without tagged queueing, even on
                                 * SCSI-II devices because the
                                 * contingent alligence condition
                                 * exists for the entire unit.
                                 */

                                /*
                                 * First check that if any device has
                                 * tried a reconnect while we have done
                                 * other things with interrupts
                                 * disabled.
                                 */

                                if ((STATUS & (STAT_SEL | STAT_IO)) ==
                                    (STAT_SEL | STAT_IO)) {
                                        sea_reselect(sea);
                                        s = splbio();
                                        break;
                                }
                                if (sea_select(sea, scb)) {
                                        s = splbio();
                                        TAILQ_INSERT_HEAD(&sea->ready_list,
                                            scb, chain);
                                } else {
                                        s = splbio();
                                        break;
                                }
                        }
                        if (!sea->nexus) {
                                /* check for reselection phase */
                                if ((STATUS & (STAT_SEL | STAT_IO)) ==
                                    (STAT_SEL | STAT_IO)) {
                                        sea_reselect(sea);
                                }
                        }
                } /* if (!sea->nexus) */

                splx(s);
                if (sea->nexus) {       /* we are connected. Do the task */
                        sea_information_transfer(sea);
                        done = 0;
                } else
                        break;
        } /* for instance */

        if (!done)
                goto loop;

        main_running = 0;
}

/*
 * Allocate an scb and add it to the free list.
 * We are called at splbio.
 */
void
sea_grow_scb(struct sea_softc *sea)
{
        struct sea_scb *scb;

        if (sea->numscbs == SEA_SCB_MAX) {
                sea->sc_channel.chan_flags &= ~SCSIPI_CHAN_CANGROW;
                return;
        }

        scb = kmem_zalloc(sizeof(*scb), KM_NOSLEEP);
        if (scb == NULL)
                return;

        TAILQ_INSERT_TAIL(&sea->free_list, scb, chain);
        sea->numscbs++;
        sea->sc_adapter.adapt_openings++;
}
void
sea_free_scb(struct sea_softc *sea, struct sea_scb *scb, int flags)
{
        int s;

        s = splbio();
        scb->flags = SCB_FREE;
        TAILQ_INSERT_HEAD(&sea->free_list, scb, chain);
        splx(s);
}

void
sea_timeout(void *arg)
{
        struct sea_scb *scb = arg;
        struct scsipi_xfer *xs = scb->xs;
        struct scsipi_periph *periph = xs->xs_periph;
        struct sea_softc *sea =
            device_private(periph->periph_channel->chan_adapter->adapt_dev);
        int s;

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

        s = splbio();

        /*
         * If it has been through before, then
         * a previous abort has failed, don't
         * try abort again
         */
        if (scb->flags & SCB_ABORTED) {
                /* abort timed out */
                printf(" AGAIN\n");
                scb->xs->xs_retries = 0;
                scb->flags |= SCB_ABORTED;
                sea_done(sea, scb);
        } else {
                /* abort the operation that has timed out */
                printf("\n");
                scb->flags |= SCB_ABORTED;
                sea_abort(sea, scb);
                /* 2 secs for the abort */
                if ((xs->xs_control & XS_CTL_POLL) == 0)
                        callout_reset(&scb->xs->xs_callout, 2 * hz,
                            sea_timeout, scb);
        }

        splx(s);
}

void
sea_reselect(struct sea_softc *sea)
{
        u_char target_mask;
        int i;
        u_char lun, phase;
        u_char msg[3];
        int len;
        u_char *data;
        struct sea_scb *scb;
        int abort = 0;

        if (!((target_mask = STATUS) & STAT_SEL)) {
                printf("%s: wrong state 0x%x\n", device_xname(sea->sc_dev),
                    target_mask);
                return;
        }

        /* wait for a device to win the reselection phase */
        /* signals this by asserting the I/O signal */
        for (i = 10; i && (STATUS & (STAT_SEL | STAT_IO | STAT_BSY)) !=
            (STAT_SEL | STAT_IO | 0); i--);
        /* !! Check for timeout here */
        /* the data bus contains original initiator id ORed with target id */
        target_mask = DATA;
        /* see that we really are the initiator */
        if (!(target_mask & sea->our_id_mask)) {
                printf("%s: polled reselection was not for me: 0x%x\n",
                    device_xname(sea->sc_dev), target_mask);
                return;
        }
        /* find target who won */
        target_mask &= ~sea->our_id_mask;
        /* host responds by asserting the BSY signal */
        CONTROL = BASE_CMD | CMD_DRVR_ENABLE | CMD_BSY;
        /* target should respond by deasserting the SEL signal */
        for (i = 50000; i && (STATUS & STAT_SEL); i++);
        /* remove the busy status */
        CONTROL = BASE_CMD | CMD_DRVR_ENABLE;
        /* we are connected. Now we wait for the MSGIN condition */
        for (i = 50000; i && !(STATUS & STAT_REQ); i--);
        /* !! Add timeout check here */
        /* hope we get an IDENTIFY message */
        len = 3;
        data = msg;
        phase = PH_MSGIN;
        sea_transfer_pio(sea, &phase, &len, &data);

        if (!MSG_ISIDENTIFY(msg[0])) {
                printf("%s: expecting IDENTIFY message, got 0x%x\n",
                    device_xname(sea->sc_dev), msg[0]);
                abort = 1;
                scb = NULL;
        } else {
                lun = msg[0] & 0x07;

                /*
                 * Find the command corresponding to the I_T_L or I_T_L_Q nexus
                 * we just reestablished, and remove it from the disconnected
                 * queue.
                 */
                for (scb = sea->nexus_list.tqh_first; scb;
                    scb = scb->chain.tqe_next)
                        if (target_mask == (1 << scb->xs->xs_periph->periph_target) &&
                            lun == scb->xs->xs_periph->periph_lun) {
                                TAILQ_REMOVE(&sea->nexus_list, scb,
                                    chain);
                                break;
                        }
                if (!scb) {
                        printf("%s: target %02x lun %d not disconnected\n",
                            device_xname(sea->sc_dev), target_mask, lun);
                        /*
                         * Since we have an established nexus that we can't do
                         * anything with, we must abort it.
                         */
                        abort = 1;
                }
        }

        if (abort) {
                msg[0] = MSG_ABORT;
                len = 1;
                data = msg;
                phase = PH_MSGOUT;
                CONTROL = BASE_CMD | CMD_ATTN;
                sea_transfer_pio(sea, &phase, &len, &data);
        } else
                sea->nexus = scb;

        return;
}

/*
 * Transfer data in given phase using polled I/O.
 */
int
sea_transfer_pio(struct sea_softc *sea, u_char *phase, int *count, u_char **data)
{
        u_char p = *phase, tmp;
        int c = *count;
        u_char *d = *data;
        int timeout;

        do {
                /*
                 * Wait for assertion of REQ, after which the phase bits will
                 * be valid.
                 */
                for (timeout = 0; timeout < 50000; timeout++)
                        if ((tmp = STATUS) & STAT_REQ)
                                break;
                if (!(tmp & STAT_REQ)) {
                        printf("%s: timeout waiting for STAT_REQ\n",
                            device_xname(sea->sc_dev));
                        break;
                }

                /*
                 * Check for phase mismatch.  Reached if the target decides
                 * that it has finished the transfer.
                 */
                if (sea->type == FDOMAIN840)
                        tmp = ((tmp & 0x08) >> 2) |
                              ((tmp & 0x02) << 2) |
                               (tmp & 0xf5);
                if ((tmp & PH_MASK) != p)
                        break;

                /* Do actual transfer from SCSI bus to/from memory. */
                if (!(p & STAT_IO))
                        DATA = *d;
                else
                        *d = DATA;
                ++d;

                /*
                 * The SCSI standard suggests that in MSGOUT phase, the
                 * initiator should drop ATN on the last byte of the message
                 * phase after REQ has been asserted for the handshake but
                 * before the initiator raises ACK.
                 * Don't know how to accomplish this on the ST01/02.
                 */

#if 0
                /*
                 * XXX
                 * The st01 code doesn't wait for STAT_REQ to be deasserted.
                 * Is this ok?
                 */
                for (timeout = 0; timeout < 200000L; timeout++)
                        if (!(STATUS & STAT_REQ))
                                break;
                if (STATUS & STAT_REQ)
                        printf("%s: timeout on wait for !STAT_REQ",
                            device_xname(sea->sc_dev));
#endif
        } while (--c);

        *count = c;
        *data = d;
        tmp = STATUS;
        if (tmp & STAT_REQ)
                *phase = tmp & PH_MASK;
        else
                *phase = PH_INVALID;

        if (c && (*phase != p))
                return -1;
        return 0;
}

/*
 * Establish I_T_L or I_T_L_Q nexus for new or existing command including
 * ARBITRATION, SELECTION, and initial message out for IDENTIFY and queue
 * messages.  Return -1 if selection could not execute for some reason, 0 if
 * selection succeded or failed because the target did not respond.
 */
int
sea_select(struct sea_softc *sea, struct sea_scb *scb)
{
        u_char msg[3], phase;
        u_char *data;
        int len;
        int timeout;

        CONTROL = BASE_CMD;
        DATA = sea->our_id_mask;
        CONTROL = (BASE_CMD & ~CMD_INTR) | CMD_START_ARB;

        /* wait for arbitration to complete */
        for (timeout = 0; timeout < 3000000L; timeout++)
                if (STATUS & STAT_ARB_CMPL)
                        break;
        if (!(STATUS & STAT_ARB_CMPL)) {
                if (STATUS & STAT_SEL) {
                        printf("%s: arbitration lost\n", device_xname(sea->sc_dev));
                        scb->flags |= SCB_ERROR;
                } else {
                        printf("%s: arbitration timeout\n",
                            device_xname(sea->sc_dev));
                        scb->flags |= SCB_TIMEOUT;
                }
                CONTROL = BASE_CMD;
                return -1;
        }

        delay(2);
        DATA = (u_char)((1 << scb->xs->xs_periph->periph_target) |
                sea->our_id_mask);
        CONTROL =
#ifdef SEA_NOMSGS
            (BASE_CMD & ~CMD_INTR) | CMD_DRVR_ENABLE | CMD_SEL;
#else
            (BASE_CMD & ~CMD_INTR) | CMD_DRVR_ENABLE | CMD_SEL | CMD_ATTN;
#endif
        delay(1);

        /* wait for a bsy from target */
        for (timeout = 0; timeout < 2000000L; timeout++)
                if (STATUS & STAT_BSY)
                        break;
        if (!(STATUS & STAT_BSY)) {
                /* should return some error to the higher level driver */
                CONTROL = BASE_CMD;
                scb->flags |= SCB_TIMEOUT;
                return 0;
        }

        /* Try to make the target to take a message from us */
#ifdef SEA_NOMSGS
        CONTROL = (BASE_CMD & ~CMD_INTR) | CMD_DRVR_ENABLE;
#else
        CONTROL = (BASE_CMD & ~CMD_INTR) | CMD_DRVR_ENABLE | CMD_ATTN;
#endif
        delay(1);

        /* should start a msg_out phase */
        for (timeout = 0; timeout < 2000000L; timeout++)
                if (STATUS & STAT_REQ)
                        break;
        /* Remove ATN. */
        CONTROL = BASE_CMD | CMD_DRVR_ENABLE;
        if (!(STATUS & STAT_REQ)) {
                /*
                 * This should not be taken as an error, but more like an
                 * unsupported feature!  Should set a flag indicating that the
                 * target don't support messages, and continue without failure.
                 * (THIS IS NOT AN ERROR!)
                 */
        } else {
                msg[0] = MSG_IDENTIFY(scb->xs->xs_periph->periph_lun, 1);
                len = 1;
                data = msg;
                phase = PH_MSGOUT;
                /* Should do test on result of sea_transfer_pio(). */
                sea_transfer_pio(sea, &phase, &len, &data);
        }
        if (!(STATUS & STAT_BSY))
                printf("%s: after successful arbitrate: no STAT_BSY!\n",
                    device_xname(sea->sc_dev));

        sea->nexus = scb;
        sea->busy[scb->xs->xs_periph->periph_target] |=
            1 << scb->xs->xs_periph->periph_lun;
        /* This assignment should depend on possibility to send a message to target. */
        CONTROL = BASE_CMD | CMD_DRVR_ENABLE;
        /* XXX Reset pointer in command? */
        return 0;
}

/*
 * Send an abort to the target.  Return 1 success, 0 on failure.
 */
int
sea_abort(struct sea_softc *sea, struct sea_scb *scb)
{
        struct sea_scb *tmp;
        u_char msg, phase, *msgptr;
        int len;

        /*
         * If the command hasn't been issued yet, we simply remove it from the
         * issue queue
         * XXX Could avoid this loop.
         */
        for (tmp = sea->ready_list.tqh_first; tmp; tmp = tmp->chain.tqe_next)
                if (scb == tmp) {
                        TAILQ_REMOVE(&sea->ready_list, scb, chain);
                        /* XXX Set some type of error result for operation. */
                        return 1;
                }

        /*
         * If any commands are connected, we're going to fail the abort and let
         * the high level SCSI driver retry at a later time or issue a reset.
         */
        if (sea->nexus)
                return 0;

        /*
         * If the command is currently disconnected from the bus, and there are
         * no connected commands, we reconnect the I_T_L or I_T_L_Q nexus
         * associated with it, go into message out, and send an abort message.
         */
        for (tmp = sea->nexus_list.tqh_first; tmp;
            tmp = tmp->chain.tqe_next)
                if (scb == tmp) {
                        if (sea_select(sea, scb))
                                return 0;

                        msg = MSG_ABORT;
                        msgptr = &msg;
                        len = 1;
                        phase = PH_MSGOUT;
                        CONTROL = BASE_CMD | CMD_ATTN;
                        sea_transfer_pio(sea, &phase, &len, &msgptr);

                        for (tmp = sea->nexus_list.tqh_first; tmp;
                            tmp = tmp->chain.tqe_next)
                                if (scb == tmp) {
                                        TAILQ_REMOVE(&sea->nexus_list,
                                            scb, chain);
                                        /* XXX Set some type of error result
                                           for the operation. */
                                        return 1;
                                }
                }

        /* Command not found in any queue; race condition? */
        return 1;
}

void
sea_done(struct sea_softc *sea, struct sea_scb *scb)
{
        struct scsipi_xfer *xs = scb->xs;

        callout_stop(&scb->xs->xs_callout);

        xs->resid = scb->datalen;

        /* XXXX need to get status */
        if (scb->flags == SCB_ACTIVE) {
                xs->resid = 0;
        } else {
                if (scb->flags & (SCB_TIMEOUT | SCB_ABORTED))
                        xs->error = XS_TIMEOUT;
                if (scb->flags & SCB_ERROR)
                        xs->error = XS_DRIVER_STUFFUP;
        }
        sea_free_scb(sea, scb, xs->xs_control);
        scsipi_done(xs);
}

/*
 * Wait for completion of command in polled mode.
 */
int
sea_poll(struct sea_softc *sea, struct scsipi_xfer *xs, int count)
{
        int s;

        while (count) {
                /* try to do something */
                s = splbio();
                if (!main_running)
                        sea_main();
                splx(s);
                if (xs->xs_status & XS_STS_DONE)
                        return 0;
                delay(1000);
                count--;
        }
        return 1;
}

/*
 * Do the transfer.  We know we are connected.  Update the flags, and call
 * sea_done() when task accomplished.  Dialog controlled by the target.
 */
void
sea_information_transfer(struct sea_softc *sea)
{
        int timeout;
        u_char msgout = MSG_NOOP;
        int len;
        int s;
        u_char *data;
        u_char phase, tmp, old_phase = PH_INVALID;
        struct sea_scb *scb = sea->nexus;
        int loop;

        for (timeout = 0; timeout < 10000000L; timeout++) {
                tmp = STATUS;
                if (tmp & STAT_PARITY)
                        printf("%s: parity error detected\n",
                            device_xname(sea->sc_dev));
                if (!(tmp & STAT_BSY)) {
                        for (loop = 0; loop < 20; loop++)
                                if ((tmp = STATUS) & STAT_BSY)
                                        break;
                        if (!(tmp & STAT_BSY)) {
                                printf("%s: !STAT_BSY unit in data transfer!\n",
                                    device_xname(sea->sc_dev));
                                s = splbio();
                                sea->nexus = NULL;
                                scb->flags = SCB_ERROR;
                                splx(s);
                                sea_done(sea, scb);
                                return;
                        }
                }

                /* we only have a valid SCSI phase when REQ is asserted */
                if (!(tmp & STAT_REQ))
                        continue;

                if (sea->type == FDOMAIN840)
                        tmp = ((tmp & 0x08) >> 2) |
                              ((tmp & 0x02) << 2) |
                               (tmp & 0xf5);
                phase = tmp & PH_MASK;
                if (phase != old_phase)
                        old_phase = phase;

                switch (phase) {
                case PH_DATAOUT:
#ifdef SEA_NODATAOUT
                        printf("%s: SEA_NODATAOUT set, attempted DATAOUT aborted\n",
                            device_xname(sea->sc_dev));
                        msgout = MSG_ABORT;
                        CONTROL = BASE_CMD | CMD_ATTN;
                        break;
#endif
                case PH_DATAIN:
                        if (!scb->data)
                                printf("no data address!\n");
#ifdef SEA_BLINDTRANSFER
                        if (scb->datalen && !(scb->datalen % BLOCK_SIZE)) {
                                while (scb->datalen) {
                                        for (loop = 0; loop < 50000; loop++)
                                                if ((tmp = STATUS) & STAT_REQ)
                                                        break;
                                        if (!(tmp & STAT_REQ)) {
                                                printf("%s: timeout waiting for STAT_REQ\n",
                                                    device_xname(sea->sc_dev));
                                                /* XXX Do something? */
                                        }
                                        if (sea->type == FDOMAIN840)
                                                tmp = ((tmp & 0x08) >> 2) |
                                                      ((tmp & 0x02) << 2) |
                                                       (tmp & 0xf5);
                                        if ((tmp & PH_MASK) != phase)
                                                break;
                                        if (!(phase & STAT_IO)) {
#ifdef SEA_ASSEMBLER
                                                void *junk;
                                                __asm("cld\n\t\
                                                    rep\n\t\
                                                    movsl" :
                                                    "=S" (scb->data),
                                                    "=c" (len),
                                                    "=D" (junk) :
                                                    "0" (scb->data),
                                                    "1" (BLOCK_SIZE >> 2),
                                                    "2" (sea->maddr_dr));
#else
                                                for (len = BLOCK_SIZE;
                                                    len; len--)
                                                        DATA = *(scb->data++);
#endif
                                        } else {
#ifdef SEA_ASSEMBLER
                                                void *junk;
                                                __asm("cld\n\t\
                                                    rep\n\t\
                                                    movsl" :
                                                    "=D" (scb->data),
                                                    "=c" (len),
                                                    "=S" (junk) :
                                                    "0" (scb->data),
                                                    "1" (BLOCK_SIZE >> 2),
                                                    "2" (sea->maddr_dr));
#else
                                                for (len = BLOCK_SIZE;
                                                    len; len--)
                                                        *(scb->data++) = DATA;
#endif
                                        }
                                        scb->datalen -= BLOCK_SIZE;
                                }
                        }
#endif
                        if (scb->datalen)
                                sea_transfer_pio(sea, &phase, &scb->datalen,
                                    &scb->data);
                        break;
                case PH_MSGIN:
                        /* Multibyte messages should not be present here. */
                        len = 1;
                        data = &tmp;
                        sea_transfer_pio(sea, &phase, &len, &data);
                        /* scb->MessageIn = tmp; */

                        switch (tmp) {
                        case MSG_ABORT:
                                scb->flags = SCB_ABORTED;
                                printf("sea: command aborted by target\n");
                                CONTROL = BASE_CMD;
                                sea_done(sea, scb);
                                return;
                        case MSG_CMDCOMPLETE:
                                s = splbio();
                                sea->nexus = NULL;
                                splx(s);
                                sea->busy[scb->xs->xs_periph->periph_target] &=
                                    ~(1 << scb->xs->xs_periph->periph_lun);
                                CONTROL = BASE_CMD;
                                sea_done(sea, scb);
                                return;
                        case MSG_MESSAGE_REJECT:
                                printf("%s: message_reject received\n",
                                    device_xname(sea->sc_dev));
                                break;
                        case MSG_DISCONNECT:
                                s = splbio();
                                TAILQ_INSERT_TAIL(&sea->nexus_list,
                                    scb, chain);
                                sea->nexus = NULL;
                                CONTROL = BASE_CMD;
                                splx(s);
                                return;
                        case MSG_SAVEDATAPOINTER:
                        case MSG_RESTOREPOINTERS:
                                /* save/restore of pointers are ignored */
                                break;
                        default:
                                /*
                                 * This should be handled in the pio data
                                 * transfer phase, as the ATN should be raised
                                 * before ACK goes false when rejecting a
                                 * message.
                                 */
                                printf("%s: unknown message in: %x\n",
                                    device_xname(sea->sc_dev), tmp);
                                break;
                        } /* switch (tmp) */
                        break;
                case PH_MSGOUT:
                        len = 1;
                        data = &msgout;
                        /* sea->last_message = msgout; */
                        sea_transfer_pio(sea, &phase, &len, &data);
                        if (msgout == MSG_ABORT) {
                                printf("%s: sent message abort to target\n",
                                    device_xname(sea->sc_dev));
                                s = splbio();
                                sea->busy[scb->xs->xs_periph->periph_target] &=
                                    ~(1 << scb->xs->xs_periph->periph_lun);
                                sea->nexus = NULL;
                                scb->flags = SCB_ABORTED;
                                splx(s);
                                /* enable interrupt from scsi */
                                sea_done(sea, scb);
                                return;
                        }
                        msgout = MSG_NOOP;
                        break;
                case PH_CMD:
                        len = scb->xs->cmdlen;
                        data = (char *) scb->xs->cmd;
                        sea_transfer_pio(sea, &phase, &len, &data);
                        break;
                case PH_STAT:
                        len = 1;
                        data = &tmp;
                        sea_transfer_pio(sea, &phase, &len, &data);
                        scb->xs->status = tmp;
                        break;
                default:
                        printf("sea: unknown phase\n");
                } /* switch (phase) */
        } /* for (...) */

        /* If we get here we have got a timeout! */
        printf("%s: timeout in data transfer\n", device_xname(sea->sc_dev));
        scb->flags = SCB_TIMEOUT;
        /* XXX Should I clear scsi-bus state? */
        sea_done(sea, scb);
}