/*      $NetBSD: sunscpal.c,v 1.29 2021/08/07 16:19:12 thorpej Exp $    */

/*
* Copyright (c) 2001 Matthew Fredette
* Copyright (c) 1995 David Jones, Gordon W. Ross
* Copyright (c) 1994 Jarle Greipsland
* All rights reserved.
*
* 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.
* 3. The name of the authors may not be used to endorse or promote products
*    derived from this software without specific prior written permission.
* 4. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by
*      David Jones and Gordon Ross
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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.
*/

/*
* This is a machine-independent driver for the Sun "sc"
* SCSI Bus Controller (SBC).
*
* This code should work with any memory-mapped card,
* and can be shared by multiple adapters that address
* the card with different register offset spacings.
* (This can happen on the atari, for example.)
*
* Credits, history:
*
* Matthew Fredette completely copied revision 1.38 of
* ncr5380sbc.c, and then heavily modified it to match
* the Sun sc PAL.  The remaining credits are for
* ncr5380sbc.c:
*
* David Jones is the author of most of the code that now
* appears in this file, and was the architect of the
* current overall structure (MI/MD code separation, etc.)
*
* Gordon Ross integrated the message phase code, added lots of
* comments about what happens when and why (re. SCSI spec.),
* debugged some reentrance problems, and added several new
* "hooks" needed for the Sun3 "si" adapters.
*
* The message in/out code was taken nearly verbatim from
* the aic6360 driver by Jarle Greipsland.
*
* Several other NCR5380 drivers were used for reference
* while developing this driver, including work by:
*   The Alice Group (mac68k port) namely:
*       Allen K. Briggs, Chris P. Caputo, Michael L. Finch,
*       Bradley A. Grantham, and Lawrence A. Kesteloot
*   Michael L. Hitch (amiga drivers: sci.c)
*   Leo Weppelman (atari driver: ncr5380.c)
* There are others too.  Thanks, everyone.
*
* Transliteration to bus_space() performed 9/17/98 by
* John Ruschmeyer ([email protected]) for i386 'nca' driver.
* Thank you all.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sunscpal.c,v 1.29 2021/08/07 16:19:12 thorpej Exp $");

#include "opt_ddb.h"

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

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

#ifdef DDB
#include <ddb/db_output.h>
#endif

#include <dev/ic/sunscpalreg.h>
#include <dev/ic/sunscpalvar.h>

static void     sunscpal_reset_scsibus(struct sunscpal_softc *);
static void     sunscpal_sched(struct sunscpal_softc *);
static void     sunscpal_done(struct sunscpal_softc *);

static int      sunscpal_select(struct sunscpal_softc *, struct sunscpal_req *);
static void     sunscpal_reselect(struct sunscpal_softc *);

static int      sunscpal_msg_in(struct sunscpal_softc *);
static int      sunscpal_msg_out(struct sunscpal_softc *);
static int      sunscpal_data_xfer(struct sunscpal_softc *, int);
static int      sunscpal_command(struct sunscpal_softc *);
static int      sunscpal_status(struct sunscpal_softc *);
static void     sunscpal_machine(struct sunscpal_softc *);

void    sunscpal_abort(struct sunscpal_softc *);
void    sunscpal_cmd_timeout(void *);
/*
* Action flags returned by the info_transfer functions:
* (These determine what happens next.)
*/
#define ACT_CONTINUE    0x00    /* No flags: expect another phase */
#define ACT_DISCONNECT  0x01    /* Target is disconnecting */
#define ACT_CMD_DONE    0x02    /* Need to call scsipi_done() */
#define ACT_RESET_BUS   0x04    /* Need bus reset (cmd timeout) */
#define ACT_WAIT_DMA    0x10    /* Wait for DMA to complete */

/*****************************************************************
* Debugging stuff
*****************************************************************/

#ifndef DDB
/* This is used only in recoverable places. */
#ifndef Debugger
#define Debugger() printf("Debug: sunscpal.c:%d\n", __LINE__)
#endif
#endif

#ifdef  SUNSCPAL_DEBUG

#define SUNSCPAL_DBG_BREAK      1
#define SUNSCPAL_DBG_CMDS       2
#define SUNSCPAL_DBG_DMA        4
int sunscpal_debug = 0;
#define SUNSCPAL_BREAK() \
       do { if (sunscpal_debug & SUNSCPAL_DBG_BREAK) Debugger(); } while (0)
static void sunscpal_show_scsi_cmd(struct scsipi_xfer *);
#ifdef DDB
void    sunscpal_clear_trace(void);
void    sunscpal_show_trace(void);
void    sunscpal_show_req(struct sunscpal_req *);
void    sunscpal_show_state(void);
#endif  /* DDB */
#else   /* SUNSCPAL_DEBUG */

#define SUNSCPAL_BREAK()                /* nada */
#define sunscpal_show_scsi_cmd(xs) /* nada */

#endif  /* SUNSCPAL_DEBUG */

static const char *
phase_names[8] = {
       "DATA_OUT",
       "DATA_IN",
       "COMMAND",
       "STATUS",
       "UNSPEC1",
       "UNSPEC2",
       "MSG_OUT",
       "MSG_IN",
};

#ifdef SUNSCPAL_USE_BUS_DMA
static void sunscpal_dma_alloc(struct sunscpal_softc *);
static void sunscpal_dma_free(struct sunscpal_softc *);
static void sunscpal_dma_setup(struct sunscpal_softc *);
#else
#define sunscpal_dma_alloc(sc) (*sc->sc_dma_alloc)(sc)
#define sunscpal_dma_free(sc) (*sc->sc_dma_free)(sc)
#define sunscpal_dma_setup(sc) (*sc->sc_dma_setup)(sc)
#endif
static void sunscpal_minphys(struct buf *);

/*****************************************************************
* Actual chip control
*****************************************************************/

/*
* XXX: These timeouts might need to be tuned...
*/

/* This one is used when waiting for a phase change. (X100uS.) */
int sunscpal_wait_phase_timo = 1000 * 10 * 300; /* 5 min. */

/* These are used in the following inline functions. */
int sunscpal_wait_req_timo = 1000 * 50; /* X2 = 100 mS. */
int sunscpal_wait_nrq_timo = 1000 * 25; /* X2 =  50 mS. */

static inline int sunscpal_wait_req(struct sunscpal_softc *);
static inline int sunscpal_wait_not_req(struct sunscpal_softc *);
static inline void sunscpal_sched_msgout(struct sunscpal_softc *, int);

/* Return zero on success. */
static inline int sunscpal_wait_req(struct sunscpal_softc *sc)
{
       int timo = sunscpal_wait_req_timo;

       for (;;) {
               if (SUNSCPAL_READ_2(sc, sunscpal_icr) & SUNSCPAL_ICR_REQUEST) {
                       timo = 0;       /* return 0 */
                       break;
               }
               if (--timo < 0)
                       break;  /* return -1 */
               delay(2);
       }
       return timo;
}

/* Return zero on success. */
static inline int sunscpal_wait_not_req(struct sunscpal_softc *sc)
{
       int timo = sunscpal_wait_nrq_timo;

       for (;;) {
               if ((SUNSCPAL_READ_2(sc, sunscpal_icr) &
                   SUNSCPAL_ICR_REQUEST) == 0) {
                       timo = 0;       /* return 0 */
                       break;
               }
               if (--timo < 0)
                       break;  /* return -1 */
               delay(2);
       }
       return timo;
}

/*
* These functions control DMA functions in the chipset independent of
* the host DMA implementation.
*/
static void sunscpal_dma_start(struct sunscpal_softc *);
static void sunscpal_dma_poll(struct sunscpal_softc *);
static void sunscpal_dma_stop(struct sunscpal_softc *);

static void
sunscpal_dma_start(struct sunscpal_softc *sc)
{
       struct sunscpal_req *sr = sc->sc_current;
       int xlen;
       uint16_t icr;

       xlen = sc->sc_reqlen;

       /* Let'er rip! */
       icr = SUNSCPAL_READ_2(sc, sunscpal_icr);
       icr |= SUNSCPAL_ICR_DMA_ENABLE |
           ((xlen & 1) ? 0 : SUNSCPAL_ICR_WORD_MODE) |
           ((sr->sr_flags & SR_IMMED) ? 0 : SUNSCPAL_ICR_INTERRUPT_ENABLE);
       SUNSCPAL_WRITE_2(sc, sunscpal_icr, icr);

       sc->sc_state |= SUNSCPAL_DOINGDMA;

#ifdef  SUNSCPAL_DEBUG
       if (sunscpal_debug & SUNSCPAL_DBG_DMA) {
               printf("%s: started, flags=0x%x\n",
                   __func__, sc->sc_state);
       }
#endif
}

#define ICR_MASK (SUNSCPAL_ICR_PARITY_ERROR | SUNSCPAL_ICR_BUS_ERROR | SUNSCPAL_ICR_INTERRUPT_REQUEST)
#define POLL_TIMO       50000   /* X100 = 5 sec. */

/*
* Poll (spin-wait) for DMA completion.
* Called right after xx_dma_start(), and
* xx_dma_stop() will be called next.
*/
static void
sunscpal_dma_poll(struct sunscpal_softc *sc)
{
       struct sunscpal_req *sr = sc->sc_current;
       int tmo;

       /* Make sure DMA started successfully. */
       if (sc->sc_state & SUNSCPAL_ABORTING)
               return;

       /* Wait for any "DMA complete" or error bits. */
       tmo = POLL_TIMO;
       for (;;) {
               if (SUNSCPAL_READ_2(sc, sunscpal_icr) & ICR_MASK)
                       break;
               if (--tmo <= 0) {
                       printf("sc: DMA timeout (while polling)\n");
                       /* Indicate timeout as MI code would. */
                       sr->sr_flags |= SR_OVERDUE;
                       break;
               }
               delay(100);
       }
       SUNSCPAL_TRACE("sunscpal_dma_poll: waited %d\n", POLL_TIMO - tmo);

#ifdef  SUNSCPAL_DEBUG
       if (sunscpal_debug & SUNSCPAL_DBG_DMA) {
               char buffer[64];
               snprintb(buffer, sizeof(buffer),
                   SUNSCPAL_READ_2(sc, sunscpal_icr), SUNSCPAL_ICR_BITS);
               printf("%s: done, icr=%s\n", __func__, buffer);
       }
#endif
}

static void
sunscpal_dma_stop(struct sunscpal_softc *sc)
{
       struct sunscpal_req *sr = sc->sc_current;
       struct scsipi_xfer *xs = sr->sr_xs;
       int resid, ntrans;
       uint16_t icr;

       if ((sc->sc_state & SUNSCPAL_DOINGDMA) == 0) {
#ifdef  DEBUG
               printf("%s: DMA not running\n", __func__);
#endif
               return;
       }
       sc->sc_state &= ~SUNSCPAL_DOINGDMA;

       /* First, halt the DMA engine. */
       icr = SUNSCPAL_READ_2(sc, sunscpal_icr);
       icr &= ~(SUNSCPAL_ICR_DMA_ENABLE | SUNSCPAL_ICR_WORD_MODE |
           SUNSCPAL_ICR_INTERRUPT_ENABLE);
       SUNSCPAL_WRITE_2(sc, sunscpal_icr, icr);

#ifdef  SUNSCPAL_USE_BUS_DMA
       /*
        * XXX - this function is supposed to be independent of
        * the host's DMA implementation.
        */
{
        sunscpal_dma_handle_t dh = sr->sr_dma_hand;

        /* sync the DMA map: */
        bus_dmamap_sync(sc->sunscpal_dmat, dh->dh_dmamap, 0, dh->dh_maplen,
            ((xs->xs_control & XS_CTL_DATA_OUT) == 0 ?
           BUS_DMASYNC_POSTREAD : BUS_DMASYNC_POSTWRITE));
}
#endif /* SUNSCPAL_USE_BUS_DMA */


       if (icr & (SUNSCPAL_ICR_BUS_ERROR)) {
               char buffer[64];
               snprintb(buffer, sizeof(buffer), SUNSCPAL_ICR_BITS, icr);
               printf("sc: DMA error, icr=%s, reset\n", buffer);
               sr->sr_xs->error = XS_DRIVER_STUFFUP;
               sc->sc_state |= SUNSCPAL_ABORTING;
               goto out;
       }

       /* Note that timeout may have set the error flag. */
       if (sc->sc_state & SUNSCPAL_ABORTING)
               goto out;

       /* XXX: Wait for DMA to actually finish? */

       /*
        * Now try to figure out how much actually transferred
        */

       resid = SUNSCPAL_DMA_COUNT_FLIP(SUNSCPAL_READ_2(sc,
           sunscpal_dma_count));
       ntrans = sc->sc_reqlen - resid;

#ifdef  SUNSCPAL_DEBUG
       if (sunscpal_debug & SUNSCPAL_DBG_DMA) {
               printf("%s: resid=0x%x ntrans=0x%x\n",
                   __func__, resid, ntrans);
       }
#endif

       if (ntrans < sc->sc_min_dma_len) {
               printf("sc: DMA count: 0x%x\n", resid);
               sc->sc_state |= SUNSCPAL_ABORTING;
               goto out;
       }
       if (ntrans > sc->sc_datalen)
               panic("%s: excess transfer", __func__);

       /* Adjust data pointer */
       sc->sc_dataptr += ntrans;
       sc->sc_datalen -= ntrans;

       /*
        * After a read, we may need to clean-up
        * "Left-over bytes" (yuck!)
        */
       if (((xs->xs_control & XS_CTL_DATA_OUT) == 0) &&
           ((icr & SUNSCPAL_ICR_ODD_LENGTH) != 0)) {
#ifdef DEBUG
               printf("sc: Got Left-over bytes!\n");
#endif
               *(sc->sc_dataptr++) = SUNSCPAL_READ_1(sc, sunscpal_data);
               sc->sc_datalen--;
       }

out:
       SUNSCPAL_WRITE_2(sc, sunscpal_dma_count, SUNSCPAL_DMA_COUNT_FLIP(0));

}

/* Ask the target for a MSG_OUT phase. */
static inline void
sunscpal_sched_msgout(struct sunscpal_softc *sc, int msg_code)
{
       /*
        * This controller does not allow you to assert ATN, which
        * will eventually leave us with no option other than to reset
        * the bus.  We keep this function as a placeholder, though,
        * and this printf will eventually go away or get #ifdef'ed:
        */
       printf("%s: trying to schedule 0x%0x\n", __func__, msg_code);
       sc->sc_msgpriq |= msg_code;
}

int
sunscpal_pio_out(struct sunscpal_softc *sc, int phase, int count, uint8_t *data)
{
       int resid;

       resid = count;
       while (resid > 0) {
               if (!SUNSCPAL_BUSY(sc)) {
                       SUNSCPAL_TRACE("pio_out: lost BSY, resid=%d\n", resid);
                       break;
               }
               if (sunscpal_wait_req(sc)) {
                       SUNSCPAL_TRACE("pio_out: no REQ, resid=%d\n", resid);
                       break;
               }
               if (SUNSCPAL_BUS_PHASE(SUNSCPAL_READ_2(sc, sunscpal_icr)) !=
                   phase)
                       break;

               /* Put the data on the bus. */
               if (data) {
                       SUNSCPAL_BYTE_WRITE(sc, phase, *data++);
               } else {
                       SUNSCPAL_BYTE_WRITE(sc, phase, 0);
               }

               --resid;
       }

       return count - resid;
}


int
sunscpal_pio_in(struct sunscpal_softc *sc, int phase, int count, uint8_t *data)
{
       int resid;

       resid = count;
       while (resid > 0) {
               if (!SUNSCPAL_BUSY(sc)) {
                       SUNSCPAL_TRACE("pio_in: lost BSY, resid=%d\n", resid);
                       break;
               }
               if (sunscpal_wait_req(sc)) {
                       SUNSCPAL_TRACE("pio_in: no REQ, resid=%d\n", resid);
                       break;
               }
               /* A phase change is not valid until AFTER REQ rises! */
               if (SUNSCPAL_BUS_PHASE(SUNSCPAL_READ_2(sc, sunscpal_icr)) !=
                   phase)
                       break;

               /* Read the data bus. */
               if (data)
                       *data++ = SUNSCPAL_BYTE_READ(sc, phase);
               else
                       (void)SUNSCPAL_BYTE_READ(sc, phase);

               --resid;
       }

       return count - resid;
}


void
sunscpal_init(struct sunscpal_softc *sc)
{
       int i, j;

#ifdef  SUNSCPAL_DEBUG
       sunscpal_debug_sc = sc;
#endif

       for (i = 0; i < SUNSCPAL_OPENINGS; i++)
               sc->sc_ring[i].sr_xs = NULL;
       for (i = 0; i < 8; i++)
               for (j = 0; j < 8; j++)
                       sc->sc_matrix[i][j] = NULL;

       sc->sc_prevphase = SUNSCPAL_PHASE_INVALID;
       sc->sc_state = SUNSCPAL_IDLE;

       SUNSCPAL_WRITE_2(sc, sunscpal_icr, 0);
       SUNSCPAL_WRITE_2(sc, sunscpal_dma_addr_h, 0);
       SUNSCPAL_WRITE_2(sc, sunscpal_dma_addr_l, 0);
       SUNSCPAL_WRITE_2(sc, sunscpal_dma_count, SUNSCPAL_DMA_COUNT_FLIP(0));

       SUNSCPAL_CLR_INTR(sc);

       /* Another hack (Er.. hook!) for anything that needs it: */
       if (sc->sc_intr_on) {
               SUNSCPAL_TRACE("init: intr ON\n", 0);
               sc->sc_intr_on(sc);
       }
}


static void
sunscpal_reset_scsibus(struct sunscpal_softc *sc)
{

       SUNSCPAL_TRACE("reset_scsibus, cur=0x%x\n", (long)sc->sc_current);

       SUNSCPAL_WRITE_2(sc, sunscpal_icr, SUNSCPAL_ICR_RESET);
       delay(500);
       SUNSCPAL_WRITE_2(sc, sunscpal_icr, 0);

       SUNSCPAL_CLR_INTR(sc);
       /* XXX - Need long delay here! */
       delay(100000);

       /* XXX - Need to cancel disconnected requests. */
}


/*
* Interrupt handler for the SCSI Bus Controller (SBC)
* This may also called for a DMA timeout (at splbio).
*/
int
sunscpal_intr(void *arg)
{
       struct sunscpal_softc *sc = arg;
       int claimed = 0;

       /*
        * Do not touch SBC regs here unless sc_current == NULL
        * or it will complain about "register conflict" errors.
        * Instead, just let sunscpal_machine() deal with it.
        */
       SUNSCPAL_TRACE("intr: top, state=%d\n", sc->sc_state);

       if (sc->sc_state == SUNSCPAL_IDLE) {
               /*
                * Might be reselect.  sunscpal_reselect() will check,
                * and set up the connection if so.  This will verify
                * that sc_current == NULL at the beginning...
                */

               /* Another hack (Er.. hook!) for anything that needs it: */
               if (sc->sc_intr_off) {
                       SUNSCPAL_TRACE("intr: for reselect, intr off\n", 0);
                   sc->sc_intr_off(sc);
               }

               sunscpal_reselect(sc);
       }

       /*
        * The remaining documented interrupt causes are a DMA complete
        * condition.
        *
        * The procedure is to let sunscpal_machine() figure out what
        * to do next.
        */
       if (sc->sc_state & SUNSCPAL_WORKING) {
               SUNSCPAL_TRACE("intr: call machine, cur=0x%x\n",
                   (long)sc->sc_current);
               /* This will usually free-up the nexus. */
               sunscpal_machine(sc);
               SUNSCPAL_TRACE("intr: machine done, cur=0x%x\n",
                   (long)sc->sc_current);
               claimed = 1;
       }

       /* Maybe we can run some commands now... */
       if (sc->sc_state == SUNSCPAL_IDLE) {
               SUNSCPAL_TRACE("intr: call sched, cur=0x%x\n",
                   (long)sc->sc_current);
               sunscpal_sched(sc);
               SUNSCPAL_TRACE("intr: sched done, cur=0x%x\n",
                   (long)sc->sc_current);
       }

       return claimed;
}


/*
* Abort the current command (i.e. due to timeout)
*/
void
sunscpal_abort(struct sunscpal_softc *sc)
{

       /*
        * Finish it now.  If DMA is in progress, we
        * can not call sunscpal_sched_msgout() because
        * that hits the SBC (avoid DMA conflict).
        */

       /* Another hack (Er.. hook!) for anything that needs it: */
       if (sc->sc_intr_off) {
               SUNSCPAL_TRACE("abort: intr off\n", 0);
               sc->sc_intr_off(sc);
       }

       sc->sc_state |= SUNSCPAL_ABORTING;
       if ((sc->sc_state & SUNSCPAL_DOINGDMA) == 0) {
               sunscpal_sched_msgout(sc, SEND_ABORT);
       }
       SUNSCPAL_TRACE("abort: call machine, cur=0x%x\n",
           (long)sc->sc_current);
       sunscpal_machine(sc);
       SUNSCPAL_TRACE("abort: machine done, cur=0x%x\n",
           (long)sc->sc_current);

       /* Another hack (Er.. hook!) for anything that needs it: */
       if (sc->sc_intr_on) {
               SUNSCPAL_TRACE("abort: intr ON\n", 0);
               sc->sc_intr_on(sc);
       }
}

/*
* Timeout handler, scheduled for each SCSI command.
*/
void
sunscpal_cmd_timeout(void *arg)
{
       struct sunscpal_req *sr = arg;
       struct scsipi_xfer *xs;
       struct scsipi_periph *periph;
       struct sunscpal_softc *sc;
       int s;

       s = splbio();

       /* Get all our variables... */
       xs = sr->sr_xs;
       if (xs == NULL) {
               printf("%s: no scsipi_xfer\n", __func__);
               goto out;
       }
       periph = xs->xs_periph;
       sc = device_private(periph->periph_channel->chan_adapter->adapt_dev);

       printf("%s: cmd timeout, targ=%d, lun=%d\n",
           device_xname(sc->sc_dev),
           sr->sr_target, sr->sr_lun);

       /*
        * Mark the overdue job as failed, and arrange for
        * sunscpal_machine to terminate it.  If the victim
        * is the current job, call sunscpal_machine() now.
        * Otherwise arrange for sunscpal_sched() to do it.
        */
       sr->sr_flags |= SR_OVERDUE;
       if (sc->sc_current == sr) {
               SUNSCPAL_TRACE("cmd_tmo: call abort, sr=0x%x\n", (long)sr);
               sunscpal_abort(sc);
       } else {
               /*
                * The driver may be idle, or busy with another job.
                * Arrange for sunscpal_sched() to do the deed.
                */
               SUNSCPAL_TRACE("cmd_tmo: clear matrix, t/l=0x%02x\n",
                   (sr->sr_target << 4) | sr->sr_lun);
               sc->sc_matrix[sr->sr_target][sr->sr_lun] = NULL;
       }

       /*
        * We may have aborted the current job, or may have
        * already been idle. In either case, we should now
        * be idle, so try to start another job.
        */
       if (sc->sc_state == SUNSCPAL_IDLE) {
               SUNSCPAL_TRACE("cmd_tmo: call sched, cur=0x%x\n",
                   (long)sc->sc_current);
               sunscpal_sched(sc);
               SUNSCPAL_TRACE("cmd_tmo: sched done, cur=0x%x\n",
                   (long)sc->sc_current);
       }

out:
       splx(s);
}


/*****************************************************************
* Interface to higher level
*****************************************************************/


/*
* Enter a new SCSI command into the "issue" queue, and
* if there is work to do, start it going.
*
* WARNING:  This can be called recursively!
* (see comment in sunscpal_done)
*/
void
sunscpal_scsipi_request(struct scsipi_channel *chan, scsipi_adapter_req_t req,
   void *arg)
{
       struct scsipi_xfer *xs;
       struct sunscpal_softc *sc;
       struct sunscpal_req *sr;
       int s, i, flags;

       sc = device_private(chan->chan_adapter->adapt_dev);

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

               if (flags & XS_CTL_DATA_UIO)
                       panic("sunscpal: scsi data uio requested");

               s = splbio();

               if (flags & XS_CTL_POLL) {
                       /* Terminate any current command. */
                       sr = sc->sc_current;
                       if (sr != NULL) {
                               printf("%s: polled request aborting %d/%d\n",
                                   device_xname(sc->sc_dev), sr->sr_target,
                                   sr->sr_lun);
                               sunscpal_abort(sc);
                       }
                       if (sc->sc_state != SUNSCPAL_IDLE) {
                               panic("%s: polled request, abort failed",
                                   __func__);
                       }
               }

               /*
                * Find lowest empty slot in ring buffer.
                * XXX: What about "fairness" and cmd order?
                */
               for (i = 0; i < SUNSCPAL_OPENINGS; i++)
                       if (sc->sc_ring[i].sr_xs == NULL)
                               goto new;

               xs->error = XS_RESOURCE_SHORTAGE;
               SUNSCPAL_TRACE("scsipi_cmd: no openings, rv=%d\n", rv);
               goto out;

new:
               /* Create queue entry */
               sr = &sc->sc_ring[i];
               sr->sr_xs = xs;
               sr->sr_target = xs->xs_periph->periph_target;
               sr->sr_lun = xs->xs_periph->periph_lun;
               sr->sr_dma_hand = NULL;
               sr->sr_dataptr = xs->data;
               sr->sr_datalen = xs->datalen;
               sr->sr_flags = (flags & XS_CTL_POLL) ? SR_IMMED : 0;
               sr->sr_status = -1;     /* no value */
               sc->sc_ncmds++;

               SUNSCPAL_TRACE("scsipi_cmd: new sr=0x%x\n", (long)sr);

               if (flags & XS_CTL_POLL) {
                       /* Force this new command to be next. */
                       sc->sc_rr = i;
               }

               /*
                * If we were idle, run some commands...
                */
               if (sc->sc_state == SUNSCPAL_IDLE) {
                       SUNSCPAL_TRACE("scsipi_cmd: call sched, cur=0x%x\n",
                           (long)sc->sc_current);
                       sunscpal_sched(sc);
                       SUNSCPAL_TRACE("scsipi_cmd: sched done, cur=0x%x\n",
                           (long)sc->sc_current);
               }

               if (flags & XS_CTL_POLL) {
                       /* Make sure sunscpal_sched() finished it. */
                       if ((xs->xs_status & XS_STS_DONE) == 0)
                               panic("%s: poll didn't finish", __func__);
               }

out:
               splx(s);
               return;

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

       case ADAPTER_REQ_SET_XFER_MODE:
           {
               /*
                * We don't support Sync, Wide, or Tagged Queueing.
                * Just callback now, to report this.
                */
               struct scsipi_xfer_mode *xm = arg;

               xm->xm_mode = 0;
               xm->xm_period = 0;
               xm->xm_offset = 0;
               scsipi_async_event(chan, ASYNC_EVENT_XFER_MODE, xm);
               return;
           }
       }
}


/*
* POST PROCESSING OF SCSI_CMD (usually current)
* Called by sunscpal_sched(), sunscpal_machine()
*/
static void
sunscpal_done(struct sunscpal_softc *sc)
{
       struct  sunscpal_req *sr;
       struct  scsipi_xfer *xs;

#ifdef  DIAGNOSTIC
       if (sc->sc_state == SUNSCPAL_IDLE)
               panic("%s: state=idle", __func__);
       if (sc->sc_current == NULL)
               panic("%s: current=0", __func__);
#endif

       sr = sc->sc_current;
       xs = sr->sr_xs;

       SUNSCPAL_TRACE("done: top, cur=0x%x\n", (long)sc->sc_current);

       /*
        * Clean up DMA resources for this command.
        */
       if (sr->sr_dma_hand) {
               SUNSCPAL_TRACE("done: dma_free, dh=0x%x\n",
                   (long)sr->sr_dma_hand);
               sunscpal_dma_free(sc);
       }
#ifdef  DIAGNOSTIC
       if (sr->sr_dma_hand)
               panic("%s: DMA free did not", __func__);
#endif

       if (sc->sc_state & SUNSCPAL_ABORTING) {
               SUNSCPAL_TRACE("done: aborting, error=%d\n", xs->error);
               if (xs->error == XS_NOERROR)
                       xs->error = XS_TIMEOUT;
       }

       SUNSCPAL_TRACE("done: check error=%d\n", (long)xs->error);

       /* If error is already set, ignore sr_status value. */
       if (xs->error != XS_NOERROR)
               goto finish;

       SUNSCPAL_TRACE("done: check status=%d\n", sr->sr_status);

       xs->status = sr->sr_status;
       switch (sr->sr_status) {
       case SCSI_OK:   /* 0 */
               break;

       case SCSI_CHECK:
       case SCSI_BUSY:
               xs->error = XS_BUSY;
               break;

       case -1:
               /* This is our "impossible" initial value. */
               /* fallthrough */
       default:
               printf("%s: target %d, bad status=%d\n",
                   device_xname(sc->sc_dev), sr->sr_target, sr->sr_status);
               xs->error = XS_DRIVER_STUFFUP;
               break;
       }

finish:

       SUNSCPAL_TRACE("done: finish, error=%d\n", xs->error);

       /*
        * Dequeue the finished command, but don't clear sc_state until
        * after the call to scsipi_done(), because that may call back to
        * sunscpal_scsi_cmd() - unwanted recursion!
        *
        * Keeping sc->sc_state != idle terminates the recursion.
        */
#ifdef  DIAGNOSTIC
       if ((sc->sc_state & SUNSCPAL_WORKING) == 0)
               panic("%s: bad state", __func__);
#endif

       /* Clear our pointers to the request. */
       sc->sc_current = NULL;
       sc->sc_matrix[sr->sr_target][sr->sr_lun] = NULL;
       callout_stop(&sr->sr_xs->xs_callout);

       /* Make the request free. */
       sr->sr_xs = NULL;
       sc->sc_ncmds--;

       /* Tell common SCSI code it is done. */
       scsipi_done(xs);

       sc->sc_state = SUNSCPAL_IDLE;
       /* Now sunscpal_sched() may be called again. */
}


/*
* Schedule a SCSI operation.  This routine should return
* only after it achieves one of the following conditions:
*      Busy (sc->sc_state != SUNSCPAL_IDLE)
*      No more work can be started.
*/
static void
sunscpal_sched(struct sunscpal_softc *sc)
{
       struct sunscpal_req     *sr;
       struct scsipi_xfer *xs;
       int     target = 0, lun = 0;
       int     error, i;

       /* Another hack (Er.. hook!) for anything that needs it: */
       if (sc->sc_intr_off) {
               SUNSCPAL_TRACE("sched: top, intr off\n", 0);
               sc->sc_intr_off(sc);
       }

next_job:
       /*
        * Grab the next job from queue.  Must be idle.
        */
#ifdef  DIAGNOSTIC
       if (sc->sc_state != SUNSCPAL_IDLE)
               panic("%s: not idle", __func__);
       if (sc->sc_current)
               panic("%s: current set", __func__);
#endif

       /*
        * Always start the search where we last looked.
        */
       i = sc->sc_rr;
       sr = NULL;
       do {
               if (sc->sc_ring[i].sr_xs) {
                       target = sc->sc_ring[i].sr_target;
                       lun = sc->sc_ring[i].sr_lun;
                       if (sc->sc_matrix[target][lun] == NULL) {
                               /*
                                * Do not mark the  target/LUN busy yet,
                                * because reselect may cause some other
                                * job to become the current one, so we
                                * might not actually start this job.
                                * Instead, set sc_matrix later on.
                                */
                               sc->sc_rr = i;
                               sr = &sc->sc_ring[i];
                               break;
                       }
               }
               i++;
               if (i == SUNSCPAL_OPENINGS)
                       i = 0;
       } while (i != sc->sc_rr);

       if (sr == NULL) {
               SUNSCPAL_TRACE("sched: no work, cur=0x%x\n",
                   (long)sc->sc_current);

               /* Another hack (Er.. hook!) for anything that needs it: */
               if (sc->sc_intr_on) {
                       SUNSCPAL_TRACE("sched: ret, intr ON\n", 0);
                       sc->sc_intr_on(sc);
               }

               return;         /* No more work to do. */
       }

       SUNSCPAL_TRACE("sched: select for t/l=0x%02x\n",
           (sr->sr_target << 4) | sr->sr_lun);

       sc->sc_state = SUNSCPAL_WORKING;
       error = sunscpal_select(sc, sr);
       if (sc->sc_current) {
               /* Lost the race!  reselected out from under us! */
               /* Work with the reselected job. */
               if (sr->sr_flags & SR_IMMED) {
                       printf("%s: reselected while polling (abort)\n",
                           device_xname(sc->sc_dev));
                       /* Abort the reselected job. */
                       sc->sc_state |= SUNSCPAL_ABORTING;
                       sc->sc_msgpriq |= SEND_ABORT;
               }
               sr = sc->sc_current;
               xs = sr->sr_xs;
               SUNSCPAL_TRACE("sched: reselect, new sr=0x%x\n", (long)sr);
               goto have_nexus;
       }

       /* Normal selection result.  Target/LUN is now busy. */
       sc->sc_matrix[target][lun] = sr;
       sc->sc_current = sr;    /* connected */
       xs = sr->sr_xs;

       /*
        * Initialize pointers, etc. for this job
        */
       sc->sc_dataptr  = sr->sr_dataptr;
       sc->sc_datalen  = sr->sr_datalen;
       sc->sc_prevphase = SUNSCPAL_PHASE_INVALID;
       sc->sc_msgpriq = SEND_IDENTIFY;
       sc->sc_msgoutq = 0;
       sc->sc_msgout  = 0;

       SUNSCPAL_TRACE("sched: select rv=%d\n", error);

       switch (error) {
       case XS_NOERROR:
               break;

       case XS_BUSY:
               /* XXX - Reset and try again. */
               printf("%s: select found SCSI bus busy, resetting...\n",
                   device_xname(sc->sc_dev));
               sunscpal_reset_scsibus(sc);
               /* fallthrough */
       case XS_SELTIMEOUT:
       default:
               xs->error = error;      /* from select */
               SUNSCPAL_TRACE("sched: call done, sr=0x%x\n", (long)sr);
               sunscpal_done(sc);

               /* Paranoia: clear everything. */
               sc->sc_dataptr = NULL;
               sc->sc_datalen = 0;
               sc->sc_prevphase = SUNSCPAL_PHASE_INVALID;
               sc->sc_msgpriq = 0;
               sc->sc_msgoutq = 0;
               sc->sc_msgout  = 0;

               goto next_job;
       }

       /*
        * Selection was successful.  Normally, this means
        * we are starting a new command.  However, this
        * might be the termination of an overdue job.
        */
       if (sr->sr_flags & SR_OVERDUE) {
               SUNSCPAL_TRACE("sched: overdue, sr=0x%x\n", (long)sr);
               sc->sc_state |= SUNSCPAL_ABORTING;
               sc->sc_msgpriq |= SEND_ABORT;
               goto have_nexus;
       }

       /*
        * OK, we are starting a new command.
        * Initialize and allocate resources for the new command.
        * Device reset is special (only uses MSG_OUT phase).
        * Normal commands start in MSG_OUT phase where we will
        * send and IDENDIFY message, and then expect CMD phase.
        */
#ifdef  SUNSCPAL_DEBUG
       if (sunscpal_debug & SUNSCPAL_DBG_CMDS) {
               printf("%s: begin, target=%d, LUN=%d\n", __func__,
                   xs->xs_periph->periph_target, xs->xs_periph->periph_lun);
               sunscpal_show_scsi_cmd(xs);
       }
#endif
       if (xs->xs_control & XS_CTL_RESET) {
               SUNSCPAL_TRACE("sched: cmd=reset, sr=0x%x\n", (long)sr);
               /* Not an error, so do not set SUNSCPAL_ABORTING */
               sc->sc_msgpriq |= SEND_DEV_RESET;
               goto have_nexus;
       }

#ifdef  DIAGNOSTIC
       if ((xs->xs_control & (XS_CTL_DATA_IN | XS_CTL_DATA_OUT)) == 0) {
               if (sc->sc_dataptr) {
                       printf("%s: ptr but no data in/out flags?\n",
                           device_xname(sc->sc_dev));
                       SUNSCPAL_BREAK();
                       sc->sc_dataptr = NULL;
               }
       }
#endif

       /* Allocate DMA space (maybe) */
       if (sc->sc_dataptr && (sc->sc_flags & SUNSCPAL_DISABLE_DMA) == 0 &&
               (sc->sc_datalen >= sc->sc_min_dma_len))
       {
               SUNSCPAL_TRACE("sched: dma_alloc, len=%d\n", sc->sc_datalen);
               sunscpal_dma_alloc(sc);
       }

       /*
        * Initialization hook called just after select,
        * at the beginning of COMMAND phase.
        * (but AFTER the DMA allocation is done)
        *
        * We need to set up the DMA engine BEFORE the target puts
        * the SCSI bus into any DATA phase.
        */
       if (sr->sr_dma_hand) {
               SUNSCPAL_TRACE("sched: dma_setup, dh=0x%x\n",
                   (long) sr->sr_dma_hand);
           sunscpal_dma_setup(sc);
       }

       /*
        * Schedule a timeout for the job we are starting.
        */
       if ((sr->sr_flags & SR_IMMED) == 0) {
               i = mstohz(xs->timeout);
               SUNSCPAL_TRACE("sched: set timeout=%d\n", i);
               callout_reset(&sr->sr_xs->xs_callout, i,
                   sunscpal_cmd_timeout, sr);
       }

have_nexus:

       SUNSCPAL_TRACE("sched: call machine, cur=0x%x\n",
           (long)sc->sc_current);
       sunscpal_machine(sc);
       SUNSCPAL_TRACE("sched: machine done, cur=0x%x\n",
           (long)sc->sc_current);

       /*
        * What state did sunscpal_machine() leave us in?
        * Hopefully it sometimes completes a job...
        */
       if (sc->sc_state == SUNSCPAL_IDLE)
               goto next_job;

       return;         /* Have work in progress. */
}


/*
*  Reselect handler: checks for reselection, and if we are being
*      reselected, it sets up sc->sc_current.
*
*  We are reselected when:
*      SEL is TRUE
*      IO  is TRUE
*      BSY is FALSE
*/
void
sunscpal_reselect(struct sunscpal_softc *sc)
{

       /*
        * This controller does not implement disconnect/reselect, so
        * we really don't have anything to do here.  We keep this
        * function as a placeholder, though.
        */
}

/*
*  Select target: xs is the transfer that we are selecting for.
*  sc->sc_current should be NULL.
*
*  Returns:
*      sc->sc_current != NULL  ==> we were reselected (race!)
*      XS_NOERROR              ==> selection worked
*      XS_BUSY                 ==> lost arbitration
*      XS_SELTIMEOUT           ==> no response to selection
*/
static int
sunscpal_select(struct sunscpal_softc *sc, struct sunscpal_req *sr)
{
       int timo, target_mask;
       u_short mode;

       /* Check for reselect */
       sunscpal_reselect(sc);
       if (sc->sc_current) {
               SUNSCPAL_TRACE("select: reselect, cur=0x%x\n",
                   (long)sc->sc_current);
               return XS_BUSY; /* reselected */
       }

       /*
        * Select the target.
        */
       target_mask = (1 << sr->sr_target);
       SUNSCPAL_WRITE_1(sc, sunscpal_data, target_mask);
       SUNSCPAL_WRITE_2(sc, sunscpal_icr, SUNSCPAL_ICR_SELECT);

       /*
        * Wait for the target to assert BSY.
        * SCSI spec. says wait for 250 mS.
        */
       for (timo = 25000;;) {
               if (SUNSCPAL_READ_2(sc, sunscpal_icr) & SUNSCPAL_ICR_BUSY)
                       goto success;
               if (--timo <= 0)
                       break;
               delay(10);
       }

       SUNSCPAL_WRITE_1(sc, sunscpal_data, 0);
       SUNSCPAL_WRITE_2(sc, sunscpal_icr, 0);

       SUNSCPAL_TRACE("select: device down, rc=%d\n", XS_SELTIMEOUT);
       return XS_SELTIMEOUT;

success:

       /*
        * The target is now driving BSY, so we can stop
        * driving SEL and the data bus.  We do set up
        * whether or not this target needs parity.
        */
       mode = 0;
       if ((sc->sc_parity_disable & target_mask) == 0)
               mode |= SUNSCPAL_ICR_PARITY_ENABLE;
       SUNSCPAL_WRITE_2(sc, sunscpal_icr, mode);

       return XS_NOERROR;
}

/*****************************************************************
* Functions to handle each info. transfer phase:
*****************************************************************/

/*
* The message system:
*
* This is a revamped message system that now should easier accommodate
* new messages, if necessary.
*
* Currently we accept these messages:
* IDENTIFY (when reselecting)
* COMMAND COMPLETE # (expect bus free after messages marked #)
* NOOP
* MESSAGE REJECT
* SYNCHRONOUS DATA TRANSFER REQUEST
* SAVE DATA POINTER
* RESTORE POINTERS
* DISCONNECT #
*
* We may send these messages in prioritized order:
* BUS DEVICE RESET #           if XS_CTL_RESET & xs->xs_control (or in
*                              weird sits.)
* MESSAGE PARITY ERROR         par. err. during MSGI
* MESSAGE REJECT               If we get a message we don't know how to handle
* ABORT #                      send on errors
* INITIATOR DETECTED ERROR     also on errors (SCSI2) (during info xfer)
* IDENTIFY                     At the start of each transfer
* SYNCHRONOUS DATA TRANSFER REQUEST    if appropriate
* NOOP                         if nothing else fits the bill ...
*/

/*
* Precondition:
* The SCSI bus is already in the MSGI phase and there is a message byte
* on the bus, along with an asserted REQ signal.
*
* Our return value determines whether our caller, sunscpal_machine()
* will expect to see another REQ (and possibly phase change).
*/
static int
sunscpal_msg_in(struct sunscpal_softc *sc)
{
       struct sunscpal_req *sr = sc->sc_current;
       struct scsipi_xfer *xs = sr->sr_xs;
       int n, phase;
       int act_flags;

       act_flags = ACT_CONTINUE;

       if (sc->sc_prevphase == SUNSCPAL_PHASE_MSG_IN) {
               /* This is a continuation of the previous message. */
               n = sc->sc_imp - sc->sc_imess;
               SUNSCPAL_TRACE("msg_in: continuation, n=%d\n", n);
               goto nextbyte;
       }

       /* This is a new MESSAGE IN phase.  Clean up our state. */
       sc->sc_state &= ~SUNSCPAL_DROP_MSGIN;

nextmsg:
       n = 0;
       sc->sc_imp = &sc->sc_imess[n];

nextbyte:
       /*
        * Read a whole message, but don't ack the last byte.  If we reject the
        * message, we have to assert ATN during the message transfer phase
        * itself.
        */
       for (;;) {
               /*
                * Read a message byte.
                * First, check BSY, REQ, phase...
                */
               if (!SUNSCPAL_BUSY(sc)) {
                       SUNSCPAL_TRACE("msg_in: lost BSY, n=%d\n", n);
                       /* XXX - Assume the command completed? */
                       act_flags |= (ACT_DISCONNECT | ACT_CMD_DONE);
                       return act_flags;
               }
               if (sunscpal_wait_req(sc)) {
                       SUNSCPAL_TRACE("msg_in: BSY but no REQ, n=%d\n", n);
                       /* Just let sunscpal_machine() handle it... */
                       return act_flags;
               }
               phase = SUNSCPAL_BUS_PHASE(SUNSCPAL_READ_2(sc, sunscpal_icr));
               if (phase != SUNSCPAL_PHASE_MSG_IN) {
                       /*
                        * Target left MESSAGE IN, probably because it
                        * a) noticed our ATN signal, or
                        * b) ran out of messages.
                        */
                       return act_flags;
               }
               /* Still in MESSAGE IN phase, and REQ is asserted. */
               if ((SUNSCPAL_READ_2(sc, sunscpal_icr) &
                   SUNSCPAL_ICR_PARITY_ERROR) != 0) {
                       sunscpal_sched_msgout(sc, SEND_PARITY_ERROR);
                       sc->sc_state |= SUNSCPAL_DROP_MSGIN;
               }

               /* Gather incoming message bytes if needed. */
               if ((sc->sc_state & SUNSCPAL_DROP_MSGIN) == 0) {
                       if (n >= SUNSCPAL_MAX_MSG_LEN) {
                               sunscpal_sched_msgout(sc, SEND_REJECT);
                               sc->sc_state |= SUNSCPAL_DROP_MSGIN;
                       } else {
                               *sc->sc_imp++ =
                                   SUNSCPAL_READ_1(sc, sunscpal_cmd_stat);
                               n++;
                               /*
                                * This testing is suboptimal, but most
                                * messages will be of the one byte variety, so
                                * it should not affect performance
                                * significantly.
                                */
                               if (n == 1 && MSG_IS1BYTE(sc->sc_imess[0]))
                                       goto have_msg;
                               if (n == 2 && MSG_IS2BYTE(sc->sc_imess[0]))
                                       goto have_msg;
                               if (n >= 3 && MSG_ISEXTENDED(sc->sc_imess[0]) &&
                                       n == sc->sc_imess[1] + 2)
                                       goto have_msg;
                       }
               }

               /*
                * If we reach this spot we're either:
                * a) in the middle of a multi-byte message, or
                * b) dropping bytes.
                */

               if (act_flags != ACT_CONTINUE)
                       return act_flags;

               /* back to nextbyte */
       }

have_msg:
       /* We now have a complete message.  Parse it. */

       switch (sc->sc_imess[0]) {
       case MSG_CMDCOMPLETE:
               SUNSCPAL_TRACE("msg_in: CMDCOMPLETE\n", 0);
               /* Target is about to disconnect. */
               act_flags |= (ACT_DISCONNECT | ACT_CMD_DONE);
               break;

       case MSG_PARITY_ERROR:
               SUNSCPAL_TRACE("msg_in: PARITY_ERROR\n", 0);
               /* Resend the last message. */
               sunscpal_sched_msgout(sc, sc->sc_msgout);
               break;

       case MSG_MESSAGE_REJECT:
               /* The target rejects the last message we sent. */
               SUNSCPAL_TRACE("msg_in: got reject for 0x%x\n", sc->sc_msgout);
               switch (sc->sc_msgout) {
               case SEND_IDENTIFY:
                       /* Really old target controller? */
                       /* XXX ... */
                       break;
               case SEND_INIT_DET_ERR:
                       goto abort;
               }
               break;

       case MSG_NOOP:
               SUNSCPAL_TRACE("msg_in: NOOP\n", 0);
               break;

       case MSG_DISCONNECT:
               SUNSCPAL_TRACE("msg_in: DISCONNECT\n", 0);
               /* Target is about to disconnect. */
               act_flags |= ACT_DISCONNECT;
               if ((xs->xs_periph->periph_quirks & PQUIRK_AUTOSAVE) == 0)
                       break;
               /*FALLTHROUGH*/

       case MSG_SAVEDATAPOINTER:
               SUNSCPAL_TRACE("msg_in: SAVE_PTRS\n", 0);
               sr->sr_dataptr = sc->sc_dataptr;
               sr->sr_datalen = sc->sc_datalen;
               break;

       case MSG_RESTOREPOINTERS:
               SUNSCPAL_TRACE("msg_in: RESTORE_PTRS\n", 0);
               sc->sc_dataptr = sr->sr_dataptr;
               sc->sc_datalen = sr->sr_datalen;
               break;

       case MSG_EXTENDED:
               switch (sc->sc_imess[2]) {
               case MSG_EXT_SDTR:
               case MSG_EXT_WDTR:
                       /* This controller can not do synchronous mode. */
                       goto reject;
               default:
                       printf("%s: unrecognized MESSAGE EXTENDED; "
                           "sending REJECT\n",
                           device_xname(sc->sc_dev));
                       SUNSCPAL_BREAK();
                       goto reject;
               }
               break;

       default:
               SUNSCPAL_TRACE("msg_in: eh? imsg=0x%x\n", sc->sc_imess[0]);
               printf("%s: unrecognized MESSAGE; sending REJECT\n",
                   device_xname(sc->sc_dev));
               SUNSCPAL_BREAK();
               /* FALLTHROUGH */
       reject:
               sunscpal_sched_msgout(sc, SEND_REJECT);
               break;

       abort:
               sc->sc_state |= SUNSCPAL_ABORTING;
               sunscpal_sched_msgout(sc, SEND_ABORT);
               break;
       }

       /* Go get the next message, if any. */
       if (act_flags == ACT_CONTINUE)
               goto nextmsg;

       return act_flags;
}


/*
* The message out (and in) stuff is a bit complicated:
* If the target requests another message (sequence) without
* having changed phase in between it really asks for a
* retransmit, probably due to parity error(s).
* The following messages can be sent:
* IDENTIFY        @ These 4 stem from SCSI command activity
* SDTR            @
* WDTR            @
* DEV_RESET       @
* REJECT if MSGI doesn't make sense
* PARITY_ERROR if parity error while in MSGI
* INIT_DET_ERR if parity error while not in MSGI
* ABORT if INIT_DET_ERR rejected
* NOOP if asked for a message and there's nothing to send
*
* Note that we call this one with (sc_current == NULL)
* when sending ABORT for unwanted reselections.
*/
static int
sunscpal_msg_out(struct sunscpal_softc *sc)
{
       /*
        * This controller does not allow you to assert ATN, which
        * means we will never get the opportunity to send messages to
        * the target (the bus will never enter this MSG_OUT phase).
        * This will eventually leave us with no option other than to
        * reset the bus.  We keep this function as a placeholder,
        * though, and this printf will eventually go away or get
        * #ifdef'ed:
        */
       printf("%s: bus is in MSG_OUT phase?\n", __func__);
       return ACT_CONTINUE | ACT_RESET_BUS;
}

/*
* Handle command phase.
*/
static int
sunscpal_command(struct sunscpal_softc *sc)
{
       struct sunscpal_req *sr = sc->sc_current;
       struct scsipi_xfer *xs = sr->sr_xs;
       int len;

       /* Assume command can be sent in one go. */
       /* XXX: Do this using DMA, and get a phase change intr? */
       len = sunscpal_pio_out(sc, SUNSCPAL_PHASE_COMMAND, xs->cmdlen,
           (uint8_t *)xs->cmd);

       if (len != xs->cmdlen) {
#ifdef  SUNSCPAL_DEBUG
               printf("%s: short transfer: wanted %d got %d.\n",
                   __func__, xs->cmdlen, len);
               sunscpal_show_scsi_cmd(xs);
               SUNSCPAL_BREAK();
#endif
               if (len < 6) {
                       xs->error = XS_DRIVER_STUFFUP;
                       sc->sc_state |= SUNSCPAL_ABORTING;
                       sunscpal_sched_msgout(sc, SEND_ABORT);
               }

       }

       return ACT_CONTINUE;
}


/*
* Handle either data_in or data_out
*/
static int
sunscpal_data_xfer(struct sunscpal_softc *sc, int phase)
{
       struct sunscpal_req *sr = sc->sc_current;
       struct scsipi_xfer *xs = sr->sr_xs;
       int expected_phase;
       int len;

       /*
        * When aborting a command, disallow any data phase.
        */
       if (sc->sc_state & SUNSCPAL_ABORTING) {
               printf("%s: aborting, bus phase=%s (reset)\n",
                   device_xname(sc->sc_dev), phase_names[(phase >> 8) & 7]);
               return ACT_RESET_BUS;   /* XXX */
       }

       /* Validate expected phase (data_in or data_out) */
       expected_phase = (xs->xs_control & XS_CTL_DATA_OUT) ?
           SUNSCPAL_PHASE_DATA_OUT : SUNSCPAL_PHASE_DATA_IN;
       if (phase != expected_phase) {
               printf("%s: data phase error\n", device_xname(sc->sc_dev));
               goto abort;
       }

       /* Make sure we have some data to move. */
       if (sc->sc_datalen <= 0) {
               /* Device needs padding. */
               if (phase == SUNSCPAL_PHASE_DATA_IN)
                       sunscpal_pio_in(sc, phase, 4096, NULL);
               else
                       sunscpal_pio_out(sc, phase, 4096, NULL);
               /* Make sure that caused a phase change. */
               if (SUNSCPAL_BUS_PHASE(SUNSCPAL_READ_2(sc, sunscpal_icr)) ==
                   phase) {
                       /* More than 4k is just too much! */
                       printf("%s: too much data padding\n",
                           device_xname(sc->sc_dev));
                       goto abort;
               }
               return ACT_CONTINUE;
       }

       /*
        * Attempt DMA only if dma_alloc gave us a DMA handle AND
        * there is enough left to transfer so DMA is worth while.
        */
       if (sr->sr_dma_hand && (sc->sc_datalen >= sc->sc_min_dma_len)) {
               /*
                * OK, really start DMA.  Note, the MD start function
                * is responsible for setting the TCMD register, etc.
                * (Acknowledge the phase change there, not here.)
                */
               SUNSCPAL_TRACE("data_xfer: dma_start, dh=0x%x\n",
                   (long)sr->sr_dma_hand);
               sunscpal_dma_start(sc);
               return ACT_WAIT_DMA;
       }

       /*
        * Doing PIO for data transfer.  (Possibly "Pseudo DMA")
        * XXX:  Do PDMA functions need to set tcmd later?
        */
       SUNSCPAL_TRACE("data_xfer: doing PIO, len=%d\n", sc->sc_datalen);
       if (phase == SUNSCPAL_PHASE_DATA_OUT) {
               len = sunscpal_pio_out(sc, phase,
                   sc->sc_datalen, sc->sc_dataptr);
       } else {
               len = sunscpal_pio_in(sc, phase,
                   sc->sc_datalen, sc->sc_dataptr);
       }
       sc->sc_dataptr += len;
       sc->sc_datalen -= len;

       SUNSCPAL_TRACE("data_xfer: did PIO, resid=%d\n", sc->sc_datalen);
       return ACT_CONTINUE;

abort:
       sc->sc_state |= SUNSCPAL_ABORTING;
       sunscpal_sched_msgout(sc, SEND_ABORT);
       return ACT_CONTINUE;
}


static int
sunscpal_status(struct sunscpal_softc *sc)
{
       int len;
       uint8_t status;
       struct sunscpal_req *sr = sc->sc_current;

       len = sunscpal_pio_in(sc, SUNSCPAL_PHASE_STATUS, 1, &status);
       if (len) {
               sr->sr_status = status;
       } else {
               printf("%s: none?\n", __func__);
       }

       return ACT_CONTINUE;
}


/*
* This is the big state machine that follows SCSI phase changes.
* This is somewhat like a co-routine.  It will do a SCSI command,
* and exit if the command is complete, or if it must wait, i.e.
* for DMA to complete or for reselect to resume the job.
*
* The bus must be selected, and we need to know which command is
* being undertaken.
*/
static void
sunscpal_machine(struct sunscpal_softc *sc)
{
       struct sunscpal_req *sr;
       struct scsipi_xfer *xs;
       int act_flags, phase, timo;

#ifdef  DIAGNOSTIC
       if (sc->sc_state == SUNSCPAL_IDLE)
               panic("%s: state=idle", __func__);
       if (sc->sc_current == NULL)
               panic("%s: no current cmd", __func__);
#endif

       sr = sc->sc_current;
       xs = sr->sr_xs;
       act_flags = ACT_CONTINUE;

       /*
        * This will be called by sunscpal_intr() when DMA is
        * complete.  Must stop DMA before touching the PAL or
        * there will be "register conflict" errors.
        */
       if ((sc->sc_state & SUNSCPAL_DOINGDMA) != 0) {
               /* Pick-up where where we left off... */
               goto dma_done;
       }

next_phase:

       if (!SUNSCPAL_BUSY(sc)) {
               /* Unexpected disconnect */
               printf("%s: unexpected disconnect.\n", __func__);
               xs->error = XS_DRIVER_STUFFUP;
               act_flags |= (ACT_DISCONNECT | ACT_CMD_DONE);
               goto do_actions;
       }

       /*
        * Wait for REQ before reading the phase.
        * Need to wait longer than usual here, because
        * some devices are just plain slow...
        */
       timo = sunscpal_wait_phase_timo;
       for (;;) {
               if (SUNSCPAL_READ_2(sc, sunscpal_icr) & SUNSCPAL_ICR_REQUEST)
                       break;
               if (--timo <= 0) {
                       if (sc->sc_state & SUNSCPAL_ABORTING) {
                               printf("%s: no REQ while aborting, reset\n",
                                   device_xname(sc->sc_dev));
                               act_flags |= ACT_RESET_BUS;
                               goto do_actions;
                       }
                       printf("%s: no REQ for next phase, abort\n",
                           device_xname(sc->sc_dev));
                       sc->sc_state |= SUNSCPAL_ABORTING;
                       sunscpal_sched_msgout(sc, SEND_ABORT);
                       goto next_phase;
               }
               delay(100);
       }

       phase = SUNSCPAL_BUS_PHASE(SUNSCPAL_READ_2(sc, sunscpal_icr));
       SUNSCPAL_TRACE("machine: phase=%s\n",
           (long)phase_names[(phase >> 8) & 7]);

       /*
        * We assume that the device knows what it's doing,
        * so any phase is good.
        */

       switch (phase) {

       case SUNSCPAL_PHASE_DATA_OUT:
       case SUNSCPAL_PHASE_DATA_IN:
               act_flags = sunscpal_data_xfer(sc, phase);
               break;

       case SUNSCPAL_PHASE_COMMAND:
               act_flags = sunscpal_command(sc);
               break;

       case SUNSCPAL_PHASE_STATUS:
               act_flags = sunscpal_status(sc);
               break;

       case SUNSCPAL_PHASE_MSG_OUT:
               act_flags = sunscpal_msg_out(sc);
               break;

       case SUNSCPAL_PHASE_MSG_IN:
               act_flags = sunscpal_msg_in(sc);
               break;

       default:
               printf("%s: Unexpected phase 0x%x\n", __func__, phase);
               sc->sc_state |= SUNSCPAL_ABORTING;
               sunscpal_sched_msgout(sc, SEND_ABORT);
               goto next_phase;

       } /* switch */
       sc->sc_prevphase = phase;

do_actions:

       if (act_flags & ACT_WAIT_DMA) {
               act_flags &= ~ACT_WAIT_DMA;
               /* Wait for DMA to complete (polling, or interrupt). */
               if ((sr->sr_flags & SR_IMMED) == 0) {
                       SUNSCPAL_TRACE("machine: wait for DMA intr.\n", 0);
                       return;         /* will resume at dma_done */
               }
               /* Busy-wait for it to finish. */
               SUNSCPAL_TRACE("machine: dma_poll, dh=0x%x\n",
                   (long)sr->sr_dma_hand);
               sunscpal_dma_poll(sc);
dma_done:
               /* Return here after interrupt. */
               if (sr->sr_flags & SR_OVERDUE)
                       sc->sc_state |= SUNSCPAL_ABORTING;
               SUNSCPAL_TRACE("machine: dma_stop, dh=0x%x\n",
                   (long)sr->sr_dma_hand);
               sunscpal_dma_stop(sc);
               SUNSCPAL_CLR_INTR(sc);  /* XXX */
               /*
                * While DMA is running we can not touch the SBC,
                * so various places just set SUNSCPAL_ABORTING and
                * expect us the "kick it" when DMA is done.
                */
               if (sc->sc_state & SUNSCPAL_ABORTING) {
                       sunscpal_sched_msgout(sc, SEND_ABORT);
               }
       }

       /*
        * Check for parity error.
        * XXX - better place to check?
        */
       if (SUNSCPAL_READ_2(sc, sunscpal_icr) & SUNSCPAL_ICR_PARITY_ERROR) {
               printf("%s: parity error!\n", device_xname(sc->sc_dev));
               /* XXX: sc->sc_state |= SUNSCPAL_ABORTING; */
               sunscpal_sched_msgout(sc, SEND_PARITY_ERROR);
       }

       if (act_flags == ACT_CONTINUE)
               goto next_phase;
       /* All other actions "break" from the loop. */

       SUNSCPAL_TRACE("machine: act_flags=0x%x\n", act_flags);

       if (act_flags & ACT_RESET_BUS) {
               act_flags |= ACT_CMD_DONE;
               /*
                * Reset the SCSI bus, usually due to a timeout.
                * The error code XS_TIMEOUT allows retries.
                */
               sc->sc_state |= SUNSCPAL_ABORTING;
               printf("%s: reset SCSI bus for TID=%d LUN=%d\n",
                   device_xname(sc->sc_dev), sr->sr_target, sr->sr_lun);
               sunscpal_reset_scsibus(sc);
       }

       if (act_flags & ACT_CMD_DONE) {
               act_flags |= ACT_DISCONNECT;
               /* Need to call scsipi_done() */
               /* XXX: from the aic6360 driver, but why? */
               if (sc->sc_datalen < 0) {
                       printf("%s: %d extra bytes from %d:%d\n",
                           device_xname(sc->sc_dev), -sc->sc_datalen,
                           sr->sr_target, sr->sr_lun);
                       sc->sc_datalen = 0;
               }
               xs->resid = sc->sc_datalen;
               /* Note: this will clear sc_current */
               SUNSCPAL_TRACE("machine: call done, cur=0x%x\n", (long)sr);
               sunscpal_done(sc);
       }

       if (act_flags & ACT_DISCONNECT) {
               /*
                * The device has dropped BSY (or will soon).
                * We have to wait here for BSY to drop, otherwise
                * the next command may decide we need a bus reset.
                */
               timo = sunscpal_wait_req_timo;  /* XXX */
               for (;;) {
                       if (!SUNSCPAL_BUSY(sc))
                               goto busfree;
                       if (--timo <= 0)
                               break;
                       delay(2);
               }
               /* Device is sitting on the bus! */
               printf("%s: Target %d LUN %d stuck busy, resetting...\n",
                   device_xname(sc->sc_dev), sr->sr_target, sr->sr_lun);
               sunscpal_reset_scsibus(sc);
busfree:
               SUNSCPAL_TRACE("machine: discon, waited %d\n",
                       sunscpal_wait_req_timo - timo);

               SUNSCPAL_WRITE_2(sc, sunscpal_icr, 0);

               if ((act_flags & ACT_CMD_DONE) == 0) {
                       SUNSCPAL_TRACE("machine: discon, cur=0x%x\n", (long)sr);
               }

               /*
                * We may be here due to a disconnect message,
                * in which case we did NOT call sunscpal_done,
                * and we need to clear sc_current.
                */
               sc->sc_state = SUNSCPAL_IDLE;
               sc->sc_current = NULL;

               /* Paranoia: clear everything. */
               sc->sc_dataptr = NULL;
               sc->sc_datalen = 0;
               sc->sc_prevphase = SUNSCPAL_PHASE_INVALID;
               sc->sc_msgpriq = 0;
               sc->sc_msgoutq = 0;
               sc->sc_msgout  = 0;

               /* Our caller will re-enable interrupts. */
       }
}


#ifdef  SUNSCPAL_DEBUG

static void
sunscpal_show_scsi_cmd(struct scsipi_xfer *xs)
{
       uint8_t *b = (uint8_t *)xs->cmd;
       int i = 0;

       scsipi_printaddr(xs->xs_periph);
       if ((xs->xs_control & XS_CTL_RESET) == 0) {
               printf("-");
               while (i < xs->cmdlen) {
                       if (i != 0)
                               printf(",");
                       printf("%x", b[i++]);
               }
               printf("-\n");
       } else {
               printf("-RESET-\n");
       }
}


int sunscpal_traceidx = 0;

#define TRACE_MAX       1024
struct trace_ent {
       char *msg;
       long  val;
} sunscpal_tracebuf[TRACE_MAX];

void
sunscpal_trace(char *msg, long val)
{
       struct trace_ent *tr;
       int s;

       s = splbio();

       tr = &sunscpal_tracebuf[sunscpal_traceidx];

       sunscpal_traceidx++;
       if (sunscpal_traceidx >= TRACE_MAX)
               sunscpal_traceidx = 0;

       tr->msg = msg;
       tr->val = val;

       splx(s);
}

#ifdef  DDB
void
sunscpal_clear_trace(void)
{

       sunscpal_traceidx = 0;
       memset((void *)sunscpal_tracebuf, 0, sizeof(sunscpal_tracebuf));
}

void
sunscpal_show_trace(void)
{
       struct trace_ent *tr;
       int idx;

       idx = sunscpal_traceidx;
       do {
               tr = &sunscpal_tracebuf[idx];
               idx++;
               if (idx >= TRACE_MAX)
                       idx = 0;
               if (tr->msg)
                       db_printf(tr->msg, tr->val);
       } while (idx != sunscpal_traceidx);
}

void
sunscpal_show_req(struct sunscpal_req *sr)
{
       struct scsipi_xfer *xs = sr->sr_xs;

       db_printf("TID=%d ",    sr->sr_target);
       db_printf("LUN=%d ",    sr->sr_lun);
       db_printf("dh=%p ",     sr->sr_dma_hand);
       db_printf("dptr=%p ",   sr->sr_dataptr);
       db_printf("dlen=0x%x ", sr->sr_datalen);
       db_printf("flags=%d ",  sr->sr_flags);
       db_printf("stat=%d ",   sr->sr_status);

       if (xs == NULL) {
               db_printf("(xs=NULL)\n");
               return;
       }
       db_printf("\n");
#ifdef  SCSIDEBUG
       show_scsipi_xs(xs);
#else
       db_printf("xs=%p\n", xs);
#endif
}

void
sunscpal_show_state(void)
{
       struct sunscpal_softc *sc;
       struct sunscpal_req *sr;
       int i, j, k;

       sc = sunscpal_debug_sc;

       if (sc == NULL) {
               db_printf("sunscpal_debug_sc == NULL\n");
               return;
       }

       db_printf("sc_ncmds=%d\n",      sc->sc_ncmds);
       k = -1; /* which is current? */
       for (i = 0; i < SUNSCPAL_OPENINGS; i++) {
               sr = &sc->sc_ring[i];
               if (sr->sr_xs) {
                       if (sr == sc->sc_current)
                               k = i;
                       db_printf("req %d: (sr=%p)", i, sr);
                       sunscpal_show_req(sr);
               }
       }
       db_printf("sc_rr=%d, current=%d\n", sc->sc_rr, k);

       db_printf("Active request matrix:\n");
       for(i = 0; i < 8; i++) {                /* targets */
               for (j = 0; j < 8; j++) {       /* LUN */
                       sr = sc->sc_matrix[i][j];
                       if (sr) {
                               db_printf("TID=%d LUN=%d sr=%p\n", i, j, sr);
                       }
               }
       }

       db_printf("sc_state=0x%x\n",    sc->sc_state);
       db_printf("sc_current=%p\n",    sc->sc_current);
       db_printf("sc_dataptr=%p\n",    sc->sc_dataptr);
       db_printf("sc_datalen=0x%x\n",  sc->sc_datalen);

       db_printf("sc_prevphase=%d\n",  sc->sc_prevphase);
       db_printf("sc_msgpriq=0x%x\n",  sc->sc_msgpriq);
}
#endif  /* DDB */
#endif  /* SUNSCPAL_DEBUG */

void
sunscpal_attach(struct sunscpal_softc *sc, int options)
{

       /*
        * Handle our options.
        */
       aprint_normal(": options=0x%x\n", options);
       sc->sc_parity_disable = (options & SUNSCPAL_OPT_NO_PARITY_CHK);
       if (options & SUNSCPAL_OPT_DISABLE_DMA)
               sc->sc_flags |= SUNSCPAL_DISABLE_DMA;

       /*
        * Fill in the adapter.
        */
       memset(&sc->sc_adapter, 0, sizeof(sc->sc_adapter));
       sc->sc_adapter.adapt_dev = sc->sc_dev;
       sc->sc_adapter.adapt_nchannels = 1;
       sc->sc_adapter.adapt_openings = SUNSCPAL_OPENINGS;
       sc->sc_adapter.adapt_max_periph = 1;
       sc->sc_adapter.adapt_request = sunscpal_scsipi_request;
       sc->sc_adapter.adapt_minphys = sunscpal_minphys;
       if (options & SUNSCPAL_OPT_FORCE_POLLING)
               sc->sc_adapter.adapt_flags |= SCSIPI_ADAPT_POLL_ONLY;

       sc->sc_channel.chan_adapter = &sc->sc_adapter;
       sc->sc_channel.chan_bustype = &scsi_bustype;
       sc->sc_channel.chan_channel = 0;
       sc->sc_channel.chan_ntargets = 8;
       sc->sc_channel.chan_nluns = 8;
       sc->sc_channel.chan_id = 7;

       /*
        * Add reference to adapter so that we drop the reference after
        * config_found() to make sure the adapter is disabled.
        */
       if (scsipi_adapter_addref(&sc->sc_adapter) != 0) {
               aprint_error_dev(sc->sc_dev, "unable to enable controller\n");
               return;
       }

       sunscpal_init(sc);      /* Init chip and driver */
       sunscpal_reset_scsibus(sc);

       /*
        * Ask the adapter what subunits are present
        */
       (void)config_found(sc->sc_dev, &sc->sc_channel, scsiprint, CFARGS_NONE);
       scsipi_adapter_delref(&sc->sc_adapter);
}

int
sunscpal_detach(struct sunscpal_softc *sc, int flags)
{

       return EOPNOTSUPP;
}

static void
sunscpal_minphys(struct buf *bp)
{

       if (bp->b_bcount > SUNSCPAL_MAX_DMA_LEN) {
#ifdef  SUNSCPAL_DEBUG
               if (sunscpal_debug & SUNSCPAL_DBG_DMA) {
                       printf("%s: len = 0x%lx.\n", __func__, bp->b_bcount);
                       Debugger();
               }
#endif
               bp->b_bcount = SUNSCPAL_MAX_DMA_LEN;
       }
       return minphys(bp);
}

#ifdef SUNSCPAL_USE_BUS_DMA

/*
* Allocate a DMA handle and put it in sr->sr_dma_hand.  Prepare
* for DMA transfer.
*/
static void
sunscpal_dma_alloc(struct sunscpal_softc *sc)
{
       struct sunscpal_req *sr = sc->sc_current;
       sunscpal_dma_handle_t dh;
       int i, xlen;
       u_long addr;

#ifdef  DIAGNOSTIC
       if (sr->sr_dma_hand != NULL)
               panic("%s: already have DMA handle", __func__);
#endif

       addr = (u_long)sc->sc_dataptr;
       xlen = sc->sc_datalen;

       /* If the DMA start addr is misaligned then do PIO */
       if ((addr & 1) || (xlen & 1)) {
               printf("%s: misaligned.\n", __func__);
               return;
       }

       /* Make sure our caller checked sc_min_dma_len. */
       if (xlen < sc->sc_min_dma_len)
               panic("%s: xlen=0x%x", __func__, xlen);

       /*
        * Never attempt single transfers of more than 63k, because
        * our count register is only 16 bits.
        * This should never happen since already bounded by minphys().
        * XXX - Should just segment these...
        */
       if (xlen > SUNSCPAL_MAX_DMA_LEN) {
               printf("%s: excessive xlen=0x%x\n", __func__, xlen);
               Debugger();
               sc->sc_datalen = xlen = SUNSCPAL_MAX_DMA_LEN;
       }

       /* Find free DMA handle.  Guaranteed to find one since we have
          as many DMA handles as the driver has processes. */
       for (i = 0; i < SUNSCPAL_OPENINGS; i++) {
               if ((sc->sc_dma_handles[i].dh_flags & SUNSCDH_BUSY) == 0)
                       goto found;
       }
       panic("%s: no free DMA handles.", device_xname(sc->sc_dev));
found:

       dh = &sc->sc_dma_handles[i];
       dh->dh_flags = SUNSCDH_BUSY;
       dh->dh_mapaddr = (uint8_t *)addr;
       dh->dh_maplen  = xlen;
       dh->dh_dvma = 0;

       /* Load the DMA map. */
       if (bus_dmamap_load(sc->sunscpal_dmat, dh->dh_dmamap,
           dh->dh_mapaddr, dh->dh_maplen, NULL, BUS_DMA_NOWAIT) != 0) {
               /* Can't load map */
               printf("%s: can't DMA %p/0x%x\n", __func__,
                   dh->dh_mapaddr, dh->dh_maplen);
               dh->dh_flags = 0;
               return;
       }

       /* success */
       sr->sr_dma_hand = dh;
}

static void
sunscpal_dma_free(struct sunscpal_softc *sc)
{
       struct sunscpal_req *sr = sc->sc_current;
       sunscpal_dma_handle_t dh = sr->sr_dma_hand;

#ifdef  DIAGNOSTIC
       if (dh == NULL)
               panic("%s: no DMA handle", __func__);
#endif

       if (sc->sc_state & SUNSCPAL_DOINGDMA)
               panic("%s: free while in progress", __func__);

       if (dh->dh_flags & SUNSCDH_BUSY) {
               /* XXX - Should separate allocation and mapping. */
               /* Give back the DVMA space. */
               bus_dmamap_unload(sc->sunscpal_dmat, dh->dh_dmamap);
               dh->dh_flags = 0;
       }
       sr->sr_dma_hand = NULL;
}

/*
* This function is called during the SELECT phase that
* precedes a COMMAND phase, in case we need to setup the
* DMA engine before the bus enters a DATA phase.
*
* On the sc version, setup the start address and the count.
*/
static void
sunscpal_dma_setup(struct sunscpal_softc *sc)
{
       struct sunscpal_req *sr = sc->sc_current;
       struct scsipi_xfer *xs = sr->sr_xs;
       sunscpal_dma_handle_t dh = sr->sr_dma_hand;
       long data_pa;
       int xlen;

       /*
        * Get the DVMA mapping for this segment.
        * XXX - Should separate allocation and mapin.
        */
       data_pa = dh->dh_dvma;
       data_pa += (sc->sc_dataptr - dh->dh_mapaddr);
       if (data_pa & 1)
               panic("%s: bad pa=0x%lx", __func__, data_pa);
       xlen = sc->sc_datalen;
       if (xlen & 1)
               panic("%s: bad xlen=0x%x", __func__, xlen);
       sc->sc_reqlen = xlen;   /* XXX: or less? */

#ifdef  SUNSCPAL_DEBUG
       if (sunscpal_debug & SUNSCPAL_DBG_DMA) {
               printf("%s: dh=%p, pa=0x%lx, xlen=0x%x\n",
                   __func__, dh, data_pa, xlen);
       }
#endif

       /* sync the DMA map: */
       bus_dmamap_sync(sc->sunscpal_dmat, dh->dh_dmamap, 0, dh->dh_maplen,
           ((xs->xs_control & XS_CTL_DATA_OUT) == 0 ?
           BUS_DMASYNC_PREREAD : BUS_DMASYNC_PREWRITE));

       /* Load the start address and the count. */
       SUNSCPAL_WRITE_2(sc, sunscpal_dma_addr_h, (data_pa >> 16) & 0xFFFF);
       SUNSCPAL_WRITE_2(sc, sunscpal_dma_addr_l, (data_pa >> 0) & 0xFFFF);
       SUNSCPAL_WRITE_2(sc, sunscpal_dma_count, SUNSCPAL_DMA_COUNT_FLIP(xlen));
}

#endif /* SUNSCPAL_USE_BUS_DMA */