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[linux-2.6/zen-sources.git] / drivers / scsi / NCR53C9x.c

/* NCR53C9x.c:  Generic SCSI driver code for NCR53C9x chips.
 *
 * Originally esp.c : EnhancedScsiProcessor Sun SCSI driver code.
 *
 * Copyright (C) 1995, 1998 David S. Miller (davem@caip.rutgers.edu)
 *
 * Most DMA dependencies put in driver specific files by 
 * Jesper Skov (jskov@cygnus.co.uk)
 *
 * Set up to use esp_read/esp_write (preprocessor macros in NCR53c9x.h) by
 * Tymm Twillman (tymm@coe.missouri.edu)
 */

/* TODO:
 *
 * 1) Maybe disable parity checking in config register one for SCSI1
 *    targets.  (Gilmore says parity error on the SBus can lock up
 *    old sun4c's)
 * 2) Add support for DMA2 pipelining.
 * 3) Add tagged queueing.
 * 4) Maybe change use of "esp" to something more "NCR"'ish.
 */

#include <linux/module.h>

#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>

#include "scsi.h"
#include <scsi/scsi_host.h>
#include "NCR53C9x.h"

#include <asm/system.h>
#include <asm/ptrace.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/irq.h>

/* Command phase enumeration. */
enum {
        not_issued    = 0x00,  /* Still in the issue_SC queue.          */

        /* Various forms of selecting a target. */
#define in_slct_mask    0x10
        in_slct_norm  = 0x10,  /* ESP is arbitrating, normal selection  */
        in_slct_stop  = 0x11,  /* ESP will select, then stop with IRQ   */
        in_slct_msg   = 0x12,  /* select, then send a message           */
        in_slct_tag   = 0x13,  /* select and send tagged queue msg      */
        in_slct_sneg  = 0x14,  /* select and acquire sync capabilities  */

        /* Any post selection activity. */
#define in_phases_mask  0x20
        in_datain     = 0x20,  /* Data is transferring from the bus     */
        in_dataout    = 0x21,  /* Data is transferring to the bus       */
        in_data_done  = 0x22,  /* Last DMA data operation done (maybe)  */
        in_msgin      = 0x23,  /* Eating message from target            */
        in_msgincont  = 0x24,  /* Eating more msg bytes from target     */
        in_msgindone  = 0x25,  /* Decide what to do with what we got    */
        in_msgout     = 0x26,  /* Sending message to target             */
        in_msgoutdone = 0x27,  /* Done sending msg out                  */
        in_cmdbegin   = 0x28,  /* Sending cmd after abnormal selection  */
        in_cmdend     = 0x29,  /* Done sending slow cmd                 */
        in_status     = 0x2a,  /* Was in status phase, finishing cmd    */
        in_freeing    = 0x2b,  /* freeing the bus for cmd cmplt or disc */
        in_the_dark   = 0x2c,  /* Don't know what bus phase we are in   */

        /* Special states, ie. not normal bus transitions... */
#define in_spec_mask    0x80
        in_abortone   = 0x80,  /* Aborting one command currently        */
        in_abortall   = 0x81,  /* Blowing away all commands we have     */
        in_resetdev   = 0x82,  /* SCSI target reset in progress         */
        in_resetbus   = 0x83,  /* SCSI bus reset in progress            */
        in_tgterror   = 0x84,  /* Target did something stupid           */
};

enum {
        /* Zero has special meaning, see skipahead[12]. */
/*0*/   do_never,

/*1*/   do_phase_determine,
/*2*/   do_reset_bus,
/*3*/   do_reset_complete,
/*4*/   do_work_bus,
/*5*/   do_intr_end
};

/* The master ring of all esp hosts we are managing in this driver. */
static struct NCR_ESP *espchain;
int nesps = 0, esps_in_use = 0, esps_running = 0;

irqreturn_t esp_intr(int irq, void *dev_id);

/* Debugging routines */
static struct esp_cmdstrings {
        unchar cmdchar;
        char *text;
} esp_cmd_strings[] = {
        /* Miscellaneous */
        { ESP_CMD_NULL, "ESP_NOP", },
        { ESP_CMD_FLUSH, "FIFO_FLUSH", },
        { ESP_CMD_RC, "RSTESP", },
        { ESP_CMD_RS, "RSTSCSI", },
        /* Disconnected State Group */
        { ESP_CMD_RSEL, "RESLCTSEQ", },
        { ESP_CMD_SEL, "SLCTNATN", },
        { ESP_CMD_SELA, "SLCTATN", },
        { ESP_CMD_SELAS, "SLCTATNSTOP", },
        { ESP_CMD_ESEL, "ENSLCTRESEL", },
        { ESP_CMD_DSEL, "DISSELRESEL", },
        { ESP_CMD_SA3, "SLCTATN3", },
        { ESP_CMD_RSEL3, "RESLCTSEQ", },
        /* Target State Group */
        { ESP_CMD_SMSG, "SNDMSG", },
        { ESP_CMD_SSTAT, "SNDSTATUS", },
        { ESP_CMD_SDATA, "SNDDATA", },
        { ESP_CMD_DSEQ, "DISCSEQ", },
        { ESP_CMD_TSEQ, "TERMSEQ", },
        { ESP_CMD_TCCSEQ, "TRGTCMDCOMPSEQ", },
        { ESP_CMD_DCNCT, "DISC", },
        { ESP_CMD_RMSG, "RCVMSG", },
        { ESP_CMD_RCMD, "RCVCMD", },
        { ESP_CMD_RDATA, "RCVDATA", },
        { ESP_CMD_RCSEQ, "RCVCMDSEQ", },
        /* Initiator State Group */
        { ESP_CMD_TI, "TRANSINFO", },
        { ESP_CMD_ICCSEQ, "INICMDSEQCOMP", },
        { ESP_CMD_MOK, "MSGACCEPTED", },
        { ESP_CMD_TPAD, "TPAD", },
        { ESP_CMD_SATN, "SATN", },
        { ESP_CMD_RATN, "RATN", },
};
#define NUM_ESP_COMMANDS  ((sizeof(esp_cmd_strings)) / (sizeof(struct esp_cmdstrings)))

/* Print textual representation of an ESP command */
static inline void esp_print_cmd(unchar espcmd)
{
        unchar dma_bit = espcmd & ESP_CMD_DMA;
        int i;

        espcmd &= ~dma_bit;
        for(i=0; i<NUM_ESP_COMMANDS; i++)
                if(esp_cmd_strings[i].cmdchar == espcmd)
                        break;
        if(i==NUM_ESP_COMMANDS)
                printk("ESP_Unknown");
        else
                printk("%s%s", esp_cmd_strings[i].text,
                       ((dma_bit) ? "+DMA" : ""));
}

/* Print the status register's value */
static inline void esp_print_statreg(unchar statreg)
{
        unchar phase;

        printk("STATUS<");
        phase = statreg & ESP_STAT_PMASK;
        printk("%s,", (phase == ESP_DOP ? "DATA-OUT" :
                       (phase == ESP_DIP ? "DATA-IN" :
                        (phase == ESP_CMDP ? "COMMAND" :
                         (phase == ESP_STATP ? "STATUS" :
                          (phase == ESP_MOP ? "MSG-OUT" :
                           (phase == ESP_MIP ? "MSG_IN" :
                            "unknown")))))));
        if(statreg & ESP_STAT_TDONE)
                printk("TRANS_DONE,");
        if(statreg & ESP_STAT_TCNT)
                printk("TCOUNT_ZERO,");
        if(statreg & ESP_STAT_PERR)
                printk("P_ERROR,");
        if(statreg & ESP_STAT_SPAM)
                printk("SPAM,");
        if(statreg & ESP_STAT_INTR)
                printk("IRQ,");
        printk(">");
}

/* Print the interrupt register's value */
static inline void esp_print_ireg(unchar intreg)
{
        printk("INTREG< ");
        if(intreg & ESP_INTR_S)
                printk("SLCT_NATN ");
        if(intreg & ESP_INTR_SATN)
                printk("SLCT_ATN ");
        if(intreg & ESP_INTR_RSEL)
                printk("RSLCT ");
        if(intreg & ESP_INTR_FDONE)
                printk("FDONE ");
        if(intreg & ESP_INTR_BSERV)
                printk("BSERV ");
        if(intreg & ESP_INTR_DC)
                printk("DISCNCT ");
        if(intreg & ESP_INTR_IC)
                printk("ILL_CMD ");
        if(intreg & ESP_INTR_SR)
                printk("SCSI_BUS_RESET ");
        printk(">");
}

/* Print the sequence step registers contents */
static inline void esp_print_seqreg(unchar stepreg)
{
        stepreg &= ESP_STEP_VBITS;
        printk("STEP<%s>",
               (stepreg == ESP_STEP_ASEL ? "SLCT_ARB_CMPLT" :
                (stepreg == ESP_STEP_SID ? "1BYTE_MSG_SENT" :
                 (stepreg == ESP_STEP_NCMD ? "NOT_IN_CMD_PHASE" :
                  (stepreg == ESP_STEP_PPC ? "CMD_BYTES_LOST" :
                   (stepreg == ESP_STEP_FINI4 ? "CMD_SENT_OK" :
                    "UNKNOWN"))))));
}

static char *phase_string(int phase)
{
        switch(phase) {
        case not_issued:
                return "UNISSUED";
        case in_slct_norm:
                return "SLCTNORM";
        case in_slct_stop:
                return "SLCTSTOP";
        case in_slct_msg:
                return "SLCTMSG";
        case in_slct_tag:
                return "SLCTTAG";
        case in_slct_sneg:
                return "SLCTSNEG";
        case in_datain:
                return "DATAIN";
        case in_dataout:
                return "DATAOUT";
        case in_data_done:
                return "DATADONE";
        case in_msgin:
                return "MSGIN";
        case in_msgincont:
                return "MSGINCONT";
        case in_msgindone:
                return "MSGINDONE";
        case in_msgout:
                return "MSGOUT";
        case in_msgoutdone:
                return "MSGOUTDONE";
        case in_cmdbegin:
                return "CMDBEGIN";
        case in_cmdend:
                return "CMDEND";
        case in_status:
                return "STATUS";
        case in_freeing:
                return "FREEING";
        case in_the_dark:
                return "CLUELESS";
        case in_abortone:
                return "ABORTONE";
        case in_abortall:
                return "ABORTALL";
        case in_resetdev:
                return "RESETDEV";
        case in_resetbus:
                return "RESETBUS";
        case in_tgterror:
                return "TGTERROR";
        default:
                return "UNKNOWN";
        };
}

#ifdef DEBUG_STATE_MACHINE
static inline void esp_advance_phase(Scsi_Cmnd *s, int newphase)
{
        ESPLOG(("<%s>", phase_string(newphase)));
        s->SCp.sent_command = s->SCp.phase;
        s->SCp.phase = newphase;
}
#else
#define esp_advance_phase(__s, __newphase) \
        (__s)->SCp.sent_command = (__s)->SCp.phase; \
        (__s)->SCp.phase = (__newphase);
#endif

#ifdef DEBUG_ESP_CMDS
static inline void esp_cmd(struct NCR_ESP *esp, struct ESP_regs *eregs,
                           unchar cmd)
{
        esp->espcmdlog[esp->espcmdent] = cmd;
        esp->espcmdent = (esp->espcmdent + 1) & 31;
        esp_write(eregs->esp_cmnd, cmd);
}
#else
#define esp_cmd(__esp, __eregs, __cmd)  esp_write((__eregs)->esp_cmnd, (__cmd))
#endif

/* How we use the various Linux SCSI data structures for operation.
 *
 * struct scsi_cmnd:
 *
 *   We keep track of the syncronous capabilities of a target
 *   in the device member, using sync_min_period and
 *   sync_max_offset.  These are the values we directly write
 *   into the ESP registers while running a command.  If offset
 *   is zero the ESP will use asynchronous transfers.
 *   If the borken flag is set we assume we shouldn't even bother
 *   trying to negotiate for synchronous transfer as this target
 *   is really stupid.  If we notice the target is dropping the
 *   bus, and we have been allowing it to disconnect, we clear
 *   the disconnect flag.
 */

/* Manipulation of the ESP command queues.  Thanks to the aha152x driver
 * and its author, Juergen E. Fischer, for the methods used here.
 * Note that these are per-ESP queues, not global queues like
 * the aha152x driver uses.
 */
static inline void append_SC(Scsi_Cmnd **SC, Scsi_Cmnd *new_SC)
{
        Scsi_Cmnd *end;

        new_SC->host_scribble = (unsigned char *) NULL;
        if(!*SC)
                *SC = new_SC;
        else {
                for(end=*SC;end->host_scribble;end=(Scsi_Cmnd *)end->host_scribble)
                        ;
                end->host_scribble = (unsigned char *) new_SC;
        }
}

static inline void prepend_SC(Scsi_Cmnd **SC, Scsi_Cmnd *new_SC)
{
        new_SC->host_scribble = (unsigned char *) *SC;
        *SC = new_SC;
}

static inline Scsi_Cmnd *remove_first_SC(Scsi_Cmnd **SC)
{
        Scsi_Cmnd *ptr;

        ptr = *SC;
        if(ptr)
                *SC = (Scsi_Cmnd *) (*SC)->host_scribble;
        return ptr;
}

static inline Scsi_Cmnd *remove_SC(Scsi_Cmnd **SC, int target, int lun)
{
        Scsi_Cmnd *ptr, *prev;

        for(ptr = *SC, prev = NULL;
            ptr && ((ptr->device->id != target) || (ptr->device->lun != lun));
            prev = ptr, ptr = (Scsi_Cmnd *) ptr->host_scribble)
                ;
        if(ptr) {
                if(prev)
                        prev->host_scribble=ptr->host_scribble;
                else
                        *SC=(Scsi_Cmnd *)ptr->host_scribble;
        }
        return ptr;
}

/* Resetting various pieces of the ESP scsi driver chipset */

/* Reset the ESP chip, _not_ the SCSI bus. */
static void esp_reset_esp(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        int family_code, version, i;
        volatile int trash;

        /* Now reset the ESP chip */
        esp_cmd(esp, eregs, ESP_CMD_RC);
        esp_cmd(esp, eregs, ESP_CMD_NULL | ESP_CMD_DMA);
        if(esp->erev == fast)
                esp_write(eregs->esp_cfg2, ESP_CONFIG2_FENAB);
        esp_cmd(esp, eregs, ESP_CMD_NULL | ESP_CMD_DMA);

        /* This is the only point at which it is reliable to read
         * the ID-code for a fast ESP chip variant.
         */
        esp->max_period = ((35 * esp->ccycle) / 1000);
        if(esp->erev == fast) {
                char *erev2string[] = {
                        "Emulex FAS236",
                        "Emulex FPESP100A",
                        "fast",
                        "QLogic FAS366",
                        "Emulex FAS216",
                        "Symbios Logic 53CF9x-2",
                        "unknown!"
                };
                        
                version = esp_read(eregs->esp_uid);
                family_code = (version & 0xf8) >> 3;
                if(family_code == 0x02) {
                        if ((version & 7) == 2)
                                esp->erev = fas216;     
                        else
                                esp->erev = fas236;
                } else if(family_code == 0x0a)
                        esp->erev = fas366; /* Version is usually '5'. */
                else if(family_code == 0x00) {
                        if ((version & 7) == 2)
                                esp->erev = fas100a; /* NCR53C9X */
                        else
                                esp->erev = espunknown;
                } else if(family_code == 0x14) {
                        if ((version & 7) == 2)
                                esp->erev = fsc;
                        else
                                esp->erev = espunknown;
                } else if(family_code == 0x00) {
                        if ((version & 7) == 2)
                                esp->erev = fas100a; /* NCR53C9X */
                        else
                                esp->erev = espunknown;
                } else
                        esp->erev = espunknown;
                ESPLOG(("esp%d: FAST chip is %s (family=%d, version=%d)\n",
                        esp->esp_id, erev2string[esp->erev - fas236],
                        family_code, (version & 7)));

                esp->min_period = ((4 * esp->ccycle) / 1000);
        } else {
                esp->min_period = ((5 * esp->ccycle) / 1000);
        }

        /* Reload the configuration registers */
        esp_write(eregs->esp_cfact, esp->cfact);
        esp->prev_stp = 0;
        esp_write(eregs->esp_stp, 0);
        esp->prev_soff = 0;
        esp_write(eregs->esp_soff, 0);
        esp_write(eregs->esp_timeo, esp->neg_defp);
        esp->max_period = (esp->max_period + 3)>>2;
        esp->min_period = (esp->min_period + 3)>>2;

        esp_write(eregs->esp_cfg1, esp->config1);
        switch(esp->erev) {
        case esp100:
                /* nothing to do */
                break;
        case esp100a:
                esp_write(eregs->esp_cfg2, esp->config2);
                break;
        case esp236:
                /* Slow 236 */
                esp_write(eregs->esp_cfg2, esp->config2);
                esp->prev_cfg3 = esp->config3[0];
                esp_write(eregs->esp_cfg3, esp->prev_cfg3);
                break;
        case fas366:
                panic("esp: FAS366 support not present, please notify "
                      "jongk@cs.utwente.nl");
                break;
        case fas216:
        case fas236:
        case fsc:
                /* Fast ESP variants */
                esp_write(eregs->esp_cfg2, esp->config2);
                for(i=0; i<8; i++)
                        esp->config3[i] |= ESP_CONFIG3_FCLK;
                esp->prev_cfg3 = esp->config3[0];
                esp_write(eregs->esp_cfg3, esp->prev_cfg3);
                if(esp->diff)
                        esp->radelay = 0;
                else
                        esp->radelay = 16;
                /* Different timeout constant for these chips */
                esp->neg_defp =
                        FSC_NEG_DEFP(esp->cfreq,
                                     (esp->cfact == ESP_CCF_F0 ?
                                      ESP_CCF_F7 + 1 : esp->cfact));
                esp_write(eregs->esp_timeo, esp->neg_defp);
                /* Enable Active Negotiation if possible */
                if((esp->erev == fsc) && !esp->diff)
                        esp_write(eregs->esp_cfg4, ESP_CONFIG4_EAN);
                break;
        case fas100a:
                /* Fast 100a */
                esp_write(eregs->esp_cfg2, esp->config2);
                for(i=0; i<8; i++)
                        esp->config3[i] |= ESP_CONFIG3_FCLOCK;
                esp->prev_cfg3 = esp->config3[0];
                esp_write(eregs->esp_cfg3, esp->prev_cfg3);
                esp->radelay = 32;
                break;
        default:
                panic("esp: what could it be... I wonder...");
                break;
        };

        /* Eat any bitrot in the chip */
        trash = esp_read(eregs->esp_intrpt);
        udelay(100);
}

/* This places the ESP into a known state at boot time. */
void esp_bootup_reset(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        volatile unchar trash;

        /* Reset the DMA */
        if(esp->dma_reset)
                esp->dma_reset(esp);

        /* Reset the ESP */
        esp_reset_esp(esp, eregs);

        /* Reset the SCSI bus, but tell ESP not to generate an irq */
        esp_write(eregs->esp_cfg1, (esp_read(eregs->esp_cfg1) | ESP_CONFIG1_SRRDISAB));
        esp_cmd(esp, eregs, ESP_CMD_RS);
        udelay(400);
        esp_write(eregs->esp_cfg1, esp->config1);

        /* Eat any bitrot in the chip and we are done... */
        trash = esp_read(eregs->esp_intrpt);
}

/* Allocate structure and insert basic data such as SCSI chip frequency
 * data and a pointer to the device
 */
struct NCR_ESP* esp_allocate(struct scsi_host_template *tpnt, void *esp_dev,
                             int hotplug)
{
        struct NCR_ESP *esp, *elink;
        struct Scsi_Host *esp_host;

        if (hotplug)
                esp_host = scsi_host_alloc(tpnt, sizeof(struct NCR_ESP));
        else
                esp_host = scsi_register(tpnt, sizeof(struct NCR_ESP));
        if(!esp_host)
                panic("Cannot register ESP SCSI host");
        esp = (struct NCR_ESP *) esp_host->hostdata;
        if(!esp)
                panic("No esp in hostdata");
        esp->ehost = esp_host;
        esp->edev = esp_dev;
        esp->esp_id = nesps++;

        /* Set bitshift value (only used on Amiga with multiple ESPs) */
        esp->shift = 2;

        /* Put into the chain of esp chips detected */
        if(espchain) {
                elink = espchain;
                while(elink->next) elink = elink->next;
                elink->next = esp;
        } else {
                espchain = esp;
        }
        esp->next = NULL;

        return esp;
}

void esp_deallocate(struct NCR_ESP *esp)
{
        struct NCR_ESP *elink;

        if(espchain == esp) {
                espchain = NULL;
        } else {
                for(elink = espchain; elink && (elink->next != esp); elink = elink->next);
                if(elink) 
                        elink->next = esp->next;
        }
        nesps--;
}

/* Complete initialization of ESP structure and device
 * Caller must have initialized appropriate parts of the ESP structure
 * between the call to esp_allocate and this function.
 */
void esp_initialize(struct NCR_ESP *esp)
{
        struct ESP_regs *eregs = esp->eregs;
        unsigned int fmhz;
        unchar ccf;
        int i;
        
        /* Check out the clock properties of the chip. */

        /* This is getting messy but it has to be done
         * correctly or else you get weird behavior all
         * over the place.  We are trying to basically
         * figure out three pieces of information.
         *
         * a) Clock Conversion Factor
         *
         *    This is a representation of the input
         *    crystal clock frequency going into the
         *    ESP on this machine.  Any operation whose
         *    timing is longer than 400ns depends on this
         *    value being correct.  For example, you'll
         *    get blips for arbitration/selection during
         *    high load or with multiple targets if this
         *    is not set correctly.
         *
         * b) Selection Time-Out
         *
         *    The ESP isn't very bright and will arbitrate
         *    for the bus and try to select a target
         *    forever if you let it.  This value tells
         *    the ESP when it has taken too long to
         *    negotiate and that it should interrupt
         *    the CPU so we can see what happened.
         *    The value is computed as follows (from
         *    NCR/Symbios chip docs).
         *
         *          (Time Out Period) *  (Input Clock)
         *    STO = ----------------------------------
         *          (8192) * (Clock Conversion Factor)
         *
         *    You usually want the time out period to be
         *    around 250ms, I think we'll set it a little
         *    bit higher to account for fully loaded SCSI
         *    bus's and slow devices that don't respond so
         *    quickly to selection attempts. (yeah, I know
         *    this is out of spec. but there is a lot of
         *    buggy pieces of firmware out there so bite me)
         *
         * c) Imperical constants for synchronous offset
         *    and transfer period register values
         *
         *    This entails the smallest and largest sync
         *    period we could ever handle on this ESP.
         */
        
        fmhz = esp->cfreq;

        if(fmhz <= (5000000))
                ccf = 0;
        else
                ccf = (((5000000 - 1) + (fmhz))/(5000000));
        if(!ccf || ccf > 8) {
                /* If we can't find anything reasonable,
                 * just assume 20MHZ.  This is the clock
                 * frequency of the older sun4c's where I've
                 * been unable to find the clock-frequency
                 * PROM property.  All other machines provide
                 * useful values it seems.
                 */
                ccf = ESP_CCF_F4;
                fmhz = (20000000);
        }
        if(ccf==(ESP_CCF_F7+1))
                esp->cfact = ESP_CCF_F0;
        else if(ccf == ESP_CCF_NEVER)
                esp->cfact = ESP_CCF_F2;
        else
                esp->cfact = ccf;
        esp->cfreq = fmhz;
        esp->ccycle = ESP_MHZ_TO_CYCLE(fmhz);
        esp->ctick = ESP_TICK(ccf, esp->ccycle);
        esp->neg_defp = ESP_NEG_DEFP(fmhz, ccf);
        esp->sync_defp = SYNC_DEFP_SLOW;

        printk("SCSI ID %d Clk %dMHz CCF=%d TOut %d ",
               esp->scsi_id, (esp->cfreq / 1000000),
               ccf, (int) esp->neg_defp);

        /* Fill in ehost data */
        esp->ehost->base = (unsigned long)eregs;
        esp->ehost->this_id = esp->scsi_id;
        esp->ehost->irq = esp->irq;

        /* SCSI id mask */
        esp->scsi_id_mask = (1 << esp->scsi_id);

        /* Probe the revision of this esp */
        esp->config1 = (ESP_CONFIG1_PENABLE | (esp->scsi_id & 7));
        esp->config2 = (ESP_CONFIG2_SCSI2ENAB | ESP_CONFIG2_REGPARITY);
        esp_write(eregs->esp_cfg2, esp->config2);
        if((esp_read(eregs->esp_cfg2) & ~(ESP_CONFIG2_MAGIC)) !=
           (ESP_CONFIG2_SCSI2ENAB | ESP_CONFIG2_REGPARITY)) {
                printk("NCR53C90(esp100)\n");
                esp->erev = esp100;
        } else {
                esp->config2 = 0;
                esp_write(eregs->esp_cfg2, 0);
                esp_write(eregs->esp_cfg3, 5);
                if(esp_read(eregs->esp_cfg3) != 5) {
                        printk("NCR53C90A(esp100a)\n");
                        esp->erev = esp100a;
                } else {
                        int target;

                        for(target=0; target<8; target++)
                                esp->config3[target] = 0;
                        esp->prev_cfg3 = 0;
                        esp_write(eregs->esp_cfg3, 0);
                        if(ccf > ESP_CCF_F5) {
                                printk("NCR53C9XF(espfast)\n");
                                esp->erev = fast;
                                esp->sync_defp = SYNC_DEFP_FAST;
                        } else {
                                printk("NCR53C9x(esp236)\n");
                                esp->erev = esp236;
                        }
                }
        }                               

        /* Initialize the command queues */
        esp->current_SC = NULL;
        esp->disconnected_SC = NULL;
        esp->issue_SC = NULL;

        /* Clear the state machines. */
        esp->targets_present = 0;
        esp->resetting_bus = 0;
        esp->snip = 0;

        init_waitqueue_head(&esp->reset_queue);

        esp->fas_premature_intr_workaround = 0;
        for(i = 0; i < 32; i++)
                esp->espcmdlog[i] = 0;
        esp->espcmdent = 0;
        for(i = 0; i < 16; i++) {
                esp->cur_msgout[i] = 0;
                esp->cur_msgin[i] = 0;
        }
        esp->prevmsgout = esp->prevmsgin = 0;
        esp->msgout_len = esp->msgin_len = 0;

        /* Clear the one behind caches to hold unmatchable values. */
        esp->prev_soff = esp->prev_stp = esp->prev_cfg3 = 0xff;

        /* Reset the thing before we try anything... */
        esp_bootup_reset(esp, eregs);

        esps_in_use++;
}

/* The info function will return whatever useful
 * information the developer sees fit.  If not provided, then
 * the name field will be used instead.
 */
const char *esp_info(struct Scsi_Host *host)
{
        struct NCR_ESP *esp;

        esp = (struct NCR_ESP *) host->hostdata;
        switch(esp->erev) {
        case esp100:
                return "ESP100 (NCR53C90)";
        case esp100a:
                return "ESP100A (NCR53C90A)";
        case esp236:
                return "ESP236 (NCR53C9x)";
        case fas216:
                return "Emulex FAS216";
        case fas236:
                return "Emulex FAS236";
        case fas366:
                return "QLogic FAS366";
        case fas100a:
                return "FPESP100A";
        case fsc:
                return "Symbios Logic 53CF9x-2";
        default:
                panic("Bogon ESP revision");
        };
}

/* From Wolfgang Stanglmeier's NCR scsi driver. */
struct info_str
{
        char *buffer;
        int length;
        int offset;
        int pos;
};

static void copy_mem_info(struct info_str *info, char *data, int len)
{
        if (info->pos + len > info->length)
                len = info->length - info->pos;

        if (info->pos + len < info->offset) {
                info->pos += len;
                return;
        }
        if (info->pos < info->offset) {
                data += (info->offset - info->pos);
                len  -= (info->offset - info->pos);
        }

        if (len > 0) {
                memcpy(info->buffer + info->pos, data, len);
                info->pos += len;
        }
}

static int copy_info(struct info_str *info, char *fmt, ...)
{
        va_list args;
        char buf[81];
        int len;

        va_start(args, fmt);
        len = vsprintf(buf, fmt, args);
        va_end(args);

        copy_mem_info(info, buf, len);
        return len;
}

static int esp_host_info(struct NCR_ESP *esp, char *ptr, off_t offset, int len)
{
        struct scsi_device *sdev;
        struct info_str info;
        int i;

        info.buffer     = ptr;
        info.length     = len;
        info.offset     = offset;
        info.pos        = 0;

        copy_info(&info, "ESP Host Adapter:\n");
        copy_info(&info, "\tESP Model\t\t");
        switch(esp->erev) {
        case esp100:
                copy_info(&info, "ESP100 (NCR53C90)\n");
                break;
        case esp100a:
                copy_info(&info, "ESP100A (NCR53C90A)\n");
                break;
        case esp236:
                copy_info(&info, "ESP236 (NCR53C9x)\n");
                break;
        case fas216:
                copy_info(&info, "Emulex FAS216\n");
                break;
        case fas236:
                copy_info(&info, "Emulex FAS236\n");
                break;
        case fas100a:
                copy_info(&info, "FPESP100A\n");
                break;
        case fast:
                copy_info(&info, "Generic FAST\n");
                break;
        case fas366:
                copy_info(&info, "QLogic FAS366\n");
                break;
        case fsc:
                copy_info(&info, "Symbios Logic 53C9x-2\n");
                break;
        case espunknown:
        default:
                copy_info(&info, "Unknown!\n");
                break;
        };
        copy_info(&info, "\tLive Targets\t\t[ ");
        for(i = 0; i < 15; i++) {
                if(esp->targets_present & (1 << i))
                        copy_info(&info, "%d ", i);
        }
        copy_info(&info, "]\n\n");
        
        /* Now describe the state of each existing target. */
        copy_info(&info, "Target #\tconfig3\t\tSync Capabilities\tDisconnect\n");

        shost_for_each_device(sdev, esp->ehost) {
                struct esp_device *esp_dev = sdev->hostdata;
                uint id = sdev->id;

                if (!(esp->targets_present & (1 << id)))
                        continue;

                copy_info(&info, "%d\t\t", id);
                copy_info(&info, "%08lx\t", esp->config3[id]);
                copy_info(&info, "[%02lx,%02lx]\t\t\t",
                        esp_dev->sync_max_offset,
                        esp_dev->sync_min_period);
                copy_info(&info, "%s\n", esp_dev->disconnect ? "yes" : "no");
        }

        return info.pos > info.offset? info.pos - info.offset : 0;
}

/* ESP proc filesystem code. */
int esp_proc_info(struct Scsi_Host *shost, char *buffer, char **start, off_t offset, int length,
                  int inout)
{
        struct NCR_ESP *esp = (struct NCR_ESP *)shost->hostdata;

        if(inout)
                return -EINVAL; /* not yet */
        if(start)
                *start = buffer;
        return esp_host_info(esp, buffer, offset, length);
}

static void esp_get_dmabufs(struct NCR_ESP *esp, Scsi_Cmnd *sp)
{
        if(sp->use_sg == 0) {
                sp->SCp.this_residual = sp->request_bufflen;
                sp->SCp.buffer = (struct scatterlist *) sp->request_buffer;
                sp->SCp.buffers_residual = 0;
                if (esp->dma_mmu_get_scsi_one)
                        esp->dma_mmu_get_scsi_one(esp, sp);
                else
                        sp->SCp.ptr =
                                (char *) virt_to_phys(sp->request_buffer);
        } else {
                sp->SCp.buffer = (struct scatterlist *) sp->request_buffer;
                sp->SCp.buffers_residual = sp->use_sg - 1;
                sp->SCp.this_residual = sp->SCp.buffer->length;
                if (esp->dma_mmu_get_scsi_sgl)
                        esp->dma_mmu_get_scsi_sgl(esp, sp);
                else
                        sp->SCp.ptr =
                                (char *) virt_to_phys((page_address(sp->SCp.buffer->page) + sp->SCp.buffer->offset));
        }
}

static void esp_release_dmabufs(struct NCR_ESP *esp, Scsi_Cmnd *sp)
{
        if(sp->use_sg == 0) {
                if (esp->dma_mmu_release_scsi_one)
                        esp->dma_mmu_release_scsi_one(esp, sp);
        } else {
                if (esp->dma_mmu_release_scsi_sgl)
                        esp->dma_mmu_release_scsi_sgl(esp, sp);
        }
}

static void esp_restore_pointers(struct NCR_ESP *esp, Scsi_Cmnd *sp)
{
        struct esp_pointers *ep = &esp->data_pointers[scmd_id(sp)];

        sp->SCp.ptr = ep->saved_ptr;
        sp->SCp.buffer = ep->saved_buffer;
        sp->SCp.this_residual = ep->saved_this_residual;
        sp->SCp.buffers_residual = ep->saved_buffers_residual;
}

static void esp_save_pointers(struct NCR_ESP *esp, Scsi_Cmnd *sp)
{
        struct esp_pointers *ep = &esp->data_pointers[scmd_id(sp)];

        ep->saved_ptr = sp->SCp.ptr;
        ep->saved_buffer = sp->SCp.buffer;
        ep->saved_this_residual = sp->SCp.this_residual;
        ep->saved_buffers_residual = sp->SCp.buffers_residual;
}

/* Some rules:
 *
 *   1) Never ever panic while something is live on the bus.
 *      If there is to be any chance of syncing the disks this
 *      rule is to be obeyed.
 *
 *   2) Any target that causes a foul condition will no longer
 *      have synchronous transfers done to it, no questions
 *      asked.
 *
 *   3) Keep register accesses to a minimum.  Think about some
 *      day when we have Xbus machines this is running on and
 *      the ESP chip is on the other end of the machine on a
 *      different board from the cpu where this is running.
 */

/* Fire off a command.  We assume the bus is free and that the only
 * case where we could see an interrupt is where we have disconnected
 * commands active and they are trying to reselect us.
 */
static inline void esp_check_cmd(struct NCR_ESP *esp, Scsi_Cmnd *sp)
{
        switch(sp->cmd_len) {
        case 6:
        case 10:
        case 12:
                esp->esp_slowcmd = 0;
                break;

        default:
                esp->esp_slowcmd = 1;
                esp->esp_scmdleft = sp->cmd_len;
                esp->esp_scmdp = &sp->cmnd[0];
                break;
        };
}

static inline void build_sync_nego_msg(struct NCR_ESP *esp, int period, int offset)
{
        esp->cur_msgout[0] = EXTENDED_MESSAGE;
        esp->cur_msgout[1] = 3;
        esp->cur_msgout[2] = EXTENDED_SDTR;
        esp->cur_msgout[3] = period;
        esp->cur_msgout[4] = offset;
        esp->msgout_len = 5;
}

static void esp_exec_cmd(struct NCR_ESP *esp)
{
        struct ESP_regs *eregs = esp->eregs;
        struct esp_device *esp_dev;
        Scsi_Cmnd *SCptr;
        struct scsi_device *SDptr;
        volatile unchar *cmdp = esp->esp_command;
        unsigned char the_esp_command;
        int lun, target;
        int i;

        /* Hold off if we have disconnected commands and
         * an IRQ is showing...
         */
        if(esp->disconnected_SC && esp->dma_irq_p(esp))
                return;

        /* Grab first member of the issue queue. */
        SCptr = esp->current_SC = remove_first_SC(&esp->issue_SC);

        /* Safe to panic here because current_SC is null. */
        if(!SCptr)
                panic("esp: esp_exec_cmd and issue queue is NULL");

        SDptr = SCptr->device;
        esp_dev = SDptr->hostdata;
        lun = SCptr->device->lun;
        target = SCptr->device->id;

        esp->snip = 0;
        esp->msgout_len = 0;

        /* Send it out whole, or piece by piece?   The ESP
         * only knows how to automatically send out 6, 10,
         * and 12 byte commands.  I used to think that the
         * Linux SCSI code would never throw anything other
         * than that to us, but then again there is the
         * SCSI generic driver which can send us anything.
         */
        esp_check_cmd(esp, SCptr);

        /* If arbitration/selection is successful, the ESP will leave
         * ATN asserted, causing the target to go into message out
         * phase.  The ESP will feed the target the identify and then
         * the target can only legally go to one of command,
         * datain/out, status, or message in phase, or stay in message
         * out phase (should we be trying to send a sync negotiation
         * message after the identify).  It is not allowed to drop
         * BSY, but some buggy targets do and we check for this
         * condition in the selection complete code.  Most of the time
         * we'll make the command bytes available to the ESP and it
         * will not interrupt us until it finishes command phase, we
         * cannot do this for command sizes the ESP does not
         * understand and in this case we'll get interrupted right
         * when the target goes into command phase.
         *
         * It is absolutely _illegal_ in the presence of SCSI-2 devices
         * to use the ESP select w/o ATN command.  When SCSI-2 devices are
         * present on the bus we _must_ always go straight to message out
         * phase with an identify message for the target.  Being that
         * selection attempts in SCSI-1 w/o ATN was an option, doing SCSI-2
         * selections should not confuse SCSI-1 we hope.
         */

        if(esp_dev->sync) {
                /* this targets sync is known */
#ifdef CONFIG_SCSI_MAC_ESP
do_sync_known:
#endif
                if(esp_dev->disconnect)
                        *cmdp++ = IDENTIFY(1, lun);
                else
                        *cmdp++ = IDENTIFY(0, lun);

                if(esp->esp_slowcmd) {
                        the_esp_command = (ESP_CMD_SELAS | ESP_CMD_DMA);
                        esp_advance_phase(SCptr, in_slct_stop);
                } else {
                        the_esp_command = (ESP_CMD_SELA | ESP_CMD_DMA);
                        esp_advance_phase(SCptr, in_slct_norm);
                }
        } else if(!(esp->targets_present & (1<<target)) || !(esp_dev->disconnect)) {
                /* After the bootup SCSI code sends both the
                 * TEST_UNIT_READY and INQUIRY commands we want
                 * to at least attempt allowing the device to
                 * disconnect.
                 */
                ESPMISC(("esp: Selecting device for first time. target=%d "
                         "lun=%d\n", target, SCptr->device->lun));
                if(!SDptr->borken && !esp_dev->disconnect)
                        esp_dev->disconnect = 1;

                *cmdp++ = IDENTIFY(0, lun);
                esp->prevmsgout = NOP;
                esp_advance_phase(SCptr, in_slct_norm);
                the_esp_command = (ESP_CMD_SELA | ESP_CMD_DMA);

                /* Take no chances... */
                esp_dev->sync_max_offset = 0;
                esp_dev->sync_min_period = 0;
        } else {
                int toshiba_cdrom_hwbug_wkaround = 0;

#ifdef CONFIG_SCSI_MAC_ESP
                /* Never allow synchronous transfers (disconnect OK) on
                 * Macintosh. Well, maybe later when we figured out how to 
                 * do DMA on the machines that support it ...
                 */
                esp_dev->disconnect = 1;
                esp_dev->sync_max_offset = 0;
                esp_dev->sync_min_period = 0;
                esp_dev->sync = 1;
                esp->snip = 0;
                goto do_sync_known;
#endif
                /* We've talked to this guy before,
                 * but never negotiated.  Let's try
                 * sync negotiation.
                 */
                if(!SDptr->borken) {
                        if((SDptr->type == TYPE_ROM) &&
                           (!strncmp(SDptr->vendor, "TOSHIBA", 7))) {
                                /* Nice try sucker... */
                                ESPMISC(("esp%d: Disabling sync for buggy "
                                         "Toshiba CDROM.\n", esp->esp_id));
                                toshiba_cdrom_hwbug_wkaround = 1;
                                build_sync_nego_msg(esp, 0, 0);
                        } else {
                                build_sync_nego_msg(esp, esp->sync_defp, 15);
                        }
                } else {
                        build_sync_nego_msg(esp, 0, 0);
                }
                esp_dev->sync = 1;
                esp->snip = 1;

                /* A fix for broken SCSI1 targets, when they disconnect
                 * they lock up the bus and confuse ESP.  So disallow
                 * disconnects for SCSI1 targets for now until we
                 * find a better fix.
                 *
                 * Addendum: This is funny, I figured out what was going
                 *           on.  The blotzed SCSI1 target would disconnect,
                 *           one of the other SCSI2 targets or both would be
                 *           disconnected as well.  The SCSI1 target would
                 *           stay disconnected long enough that we start
                 *           up a command on one of the SCSI2 targets.  As
                 *           the ESP is arbitrating for the bus the SCSI1
                 *           target begins to arbitrate as well to reselect
                 *           the ESP.  The SCSI1 target refuses to drop it's
                 *           ID bit on the data bus even though the ESP is
                 *           at ID 7 and is the obvious winner for any
                 *           arbitration.  The ESP is a poor sport and refuses
                 *           to lose arbitration, it will continue indefinitely
                 *           trying to arbitrate for the bus and can only be
                 *           stopped via a chip reset or SCSI bus reset.
                 *           Therefore _no_ disconnects for SCSI1 targets
                 *           thank you very much. ;-)
                 */
                if(((SDptr->scsi_level < 3) && (SDptr->type != TYPE_TAPE)) ||
                   toshiba_cdrom_hwbug_wkaround || SDptr->borken) {
                        ESPMISC((KERN_INFO "esp%d: Disabling DISCONNECT for target %d "
                                 "lun %d\n", esp->esp_id, SCptr->device->id, SCptr->device->lun));
                        esp_dev->disconnect = 0;
                        *cmdp++ = IDENTIFY(0, lun);
                } else {
                        *cmdp++ = IDENTIFY(1, lun);
                }

                /* ESP fifo is only so big...
                 * Make this look like a slow command.
                 */
                esp->esp_slowcmd = 1;
                esp->esp_scmdleft = SCptr->cmd_len;
                esp->esp_scmdp = &SCptr->cmnd[0];

                the_esp_command = (ESP_CMD_SELAS | ESP_CMD_DMA);
                esp_advance_phase(SCptr, in_slct_msg);
        }

        if(!esp->esp_slowcmd)
                for(i = 0; i < SCptr->cmd_len; i++)
                        *cmdp++ = SCptr->cmnd[i];

        esp_write(eregs->esp_busid, (target & 7));
        if (esp->prev_soff != esp_dev->sync_max_offset ||
            esp->prev_stp  != esp_dev->sync_min_period ||
            (esp->erev > esp100a &&
             esp->prev_cfg3 != esp->config3[target])) {
                esp->prev_soff = esp_dev->sync_max_offset;
                esp_write(eregs->esp_soff, esp->prev_soff);
                esp->prev_stp = esp_dev->sync_min_period;
                esp_write(eregs->esp_stp, esp->prev_stp); 
                if(esp->erev > esp100a) {
                        esp->prev_cfg3 = esp->config3[target];
                        esp_write(eregs->esp_cfg3, esp->prev_cfg3);
                }
        }
        i = (cmdp - esp->esp_command);

        /* Set up the DMA and ESP counters */
        if(esp->do_pio_cmds){
                int j = 0;

                /* 
                 * XXX MSch:
                 *
                 * It seems this is required, at least to clean up
                 * after failed commands when using PIO mode ...
                 */
                esp_cmd(esp, eregs, ESP_CMD_FLUSH);

                for(;j<i;j++)
                        esp_write(eregs->esp_fdata, esp->esp_command[j]);
                the_esp_command &= ~ESP_CMD_DMA;

                /* Tell ESP to "go". */
                esp_cmd(esp, eregs, the_esp_command);
        } else {
                /* Set up the ESP counters */
                esp_write(eregs->esp_tclow, i);
                esp_write(eregs->esp_tcmed, 0);
                esp->dma_init_write(esp, esp->esp_command_dvma, i);

                /* Tell ESP to "go". */
                esp_cmd(esp, eregs, the_esp_command);
        }
}

/* Queue a SCSI command delivered from the mid-level Linux SCSI code. */
int esp_queue(Scsi_Cmnd *SCpnt, void (*done)(Scsi_Cmnd *))
{
        struct NCR_ESP *esp;

        /* Set up func ptr and initial driver cmd-phase. */
        SCpnt->scsi_done = done;
        SCpnt->SCp.phase = not_issued;

        esp = (struct NCR_ESP *) SCpnt->device->host->hostdata;

        if(esp->dma_led_on)
                esp->dma_led_on(esp);

        /* We use the scratch area. */
        ESPQUEUE(("esp_queue: target=%d lun=%d ", SCpnt->device->id, SCpnt->lun));
        ESPDISC(("N<%02x,%02x>", SCpnt->device->id, SCpnt->lun));

        esp_get_dmabufs(esp, SCpnt);
        esp_save_pointers(esp, SCpnt); /* FIXME for tag queueing */

        SCpnt->SCp.Status           = CHECK_CONDITION;
        SCpnt->SCp.Message          = 0xff;
        SCpnt->SCp.sent_command     = 0;

        /* Place into our queue. */
        if(SCpnt->cmnd[0] == REQUEST_SENSE) {
                ESPQUEUE(("RQSENSE\n"));
                prepend_SC(&esp->issue_SC, SCpnt);
        } else {
                ESPQUEUE(("\n"));
                append_SC(&esp->issue_SC, SCpnt);
        }

        /* Run it now if we can. */
        if(!esp->current_SC && !esp->resetting_bus)
                esp_exec_cmd(esp);

        return 0;
}

/* Dump driver state. */
static void esp_dump_cmd(Scsi_Cmnd *SCptr)
{
        ESPLOG(("[tgt<%02x> lun<%02x> "
                "pphase<%s> cphase<%s>]",
                SCptr->device->id, SCptr->device->lun,
                phase_string(SCptr->SCp.sent_command),
                phase_string(SCptr->SCp.phase)));
}

static void esp_dump_state(struct NCR_ESP *esp, 
                           struct ESP_regs *eregs)
{
        Scsi_Cmnd *SCptr = esp->current_SC;
#ifdef DEBUG_ESP_CMDS
        int i;
#endif

        ESPLOG(("esp%d: dumping state\n", esp->esp_id));
        
        /* Print DMA status */
        esp->dma_dump_state(esp);

        ESPLOG(("esp%d: SW [sreg<%02x> sstep<%02x> ireg<%02x>]\n",
                esp->esp_id, esp->sreg, esp->seqreg, esp->ireg));
        ESPLOG(("esp%d: HW reread [sreg<%02x> sstep<%02x> ireg<%02x>]\n",
                esp->esp_id, esp_read(eregs->esp_status), esp_read(eregs->esp_sstep),
                esp_read(eregs->esp_intrpt)));
#ifdef DEBUG_ESP_CMDS
        printk("esp%d: last ESP cmds [", esp->esp_id);
        i = (esp->espcmdent - 1) & 31;
        printk("<");
        esp_print_cmd(esp->espcmdlog[i]);
        printk(">");
        i = (i - 1) & 31;
        printk("<");
        esp_print_cmd(esp->espcmdlog[i]);
        printk(">");
        i = (i - 1) & 31;
        printk("<");
        esp_print_cmd(esp->espcmdlog[i]);
        printk(">");
        i = (i - 1) & 31;
        printk("<");
        esp_print_cmd(esp->espcmdlog[i]);
        printk(">");
        printk("]\n");
#endif /* (DEBUG_ESP_CMDS) */

        if(SCptr) {
                ESPLOG(("esp%d: current command ", esp->esp_id));
                esp_dump_cmd(SCptr);
        }
        ESPLOG(("\n"));
        SCptr = esp->disconnected_SC;
        ESPLOG(("esp%d: disconnected ", esp->esp_id));
        while(SCptr) {
                esp_dump_cmd(SCptr);
                SCptr = (Scsi_Cmnd *) SCptr->host_scribble;
        }
        ESPLOG(("\n"));
}

/* Abort a command.  The host_lock is acquired by caller. */
int esp_abort(Scsi_Cmnd *SCptr)
{
        struct NCR_ESP *esp = (struct NCR_ESP *) SCptr->device->host->hostdata;
        struct ESP_regs *eregs = esp->eregs;
        int don;

        ESPLOG(("esp%d: Aborting command\n", esp->esp_id));
        esp_dump_state(esp, eregs);

        /* Wheee, if this is the current command on the bus, the
         * best we can do is assert ATN and wait for msgout phase.
         * This should even fix a hung SCSI bus when we lose state
         * in the driver and timeout because the eventual phase change
         * will cause the ESP to (eventually) give an interrupt.
         */
        if(esp->current_SC == SCptr) {
                esp->cur_msgout[0] = ABORT;
                esp->msgout_len = 1;
                esp->msgout_ctr = 0;
                esp_cmd(esp, eregs, ESP_CMD_SATN);
                return SUCCESS;
        }

        /* If it is still in the issue queue then we can safely
         * call the completion routine and report abort success.
         */
        don = esp->dma_ports_p(esp);
        if(don) {
                esp->dma_ints_off(esp);
                synchronize_irq(esp->irq);
        }
        if(esp->issue_SC) {
                Scsi_Cmnd **prev, *this;
                for(prev = (&esp->issue_SC), this = esp->issue_SC;
                    this;
                    prev = (Scsi_Cmnd **) &(this->host_scribble),
                    this = (Scsi_Cmnd *) this->host_scribble) {
                        if(this == SCptr) {
                                *prev = (Scsi_Cmnd *) this->host_scribble;
                                this->host_scribble = NULL;
                                esp_release_dmabufs(esp, this);
                                this->result = DID_ABORT << 16;
                                this->done(this);
                                if(don)
                                        esp->dma_ints_on(esp);
                                return SUCCESS;
                        }
                }
        }

        /* Yuck, the command to abort is disconnected, it is not
         * worth trying to abort it now if something else is live
         * on the bus at this time.  So, we let the SCSI code wait
         * a little bit and try again later.
         */
        if(esp->current_SC) {
                if(don)
                        esp->dma_ints_on(esp);
                return FAILED;
        }

        /* It's disconnected, we have to reconnect to re-establish
         * the nexus and tell the device to abort.  However, we really
         * cannot 'reconnect' per se.  Don't try to be fancy, just
         * indicate failure, which causes our caller to reset the whole
         * bus.
         */

        if(don)
                esp->dma_ints_on(esp);
        return FAILED;
}

/* We've sent ESP_CMD_RS to the ESP, the interrupt had just
 * arrived indicating the end of the SCSI bus reset.  Our job
 * is to clean out the command queues and begin re-execution
 * of SCSI commands once more.
 */
static int esp_finish_reset(struct NCR_ESP *esp,
                            struct ESP_regs *eregs)
{
        Scsi_Cmnd *sp = esp->current_SC;

        /* Clean up currently executing command, if any. */
        if (sp != NULL) {
                esp_release_dmabufs(esp, sp);
                sp->result = (DID_RESET << 16);
                sp->scsi_done(sp);
                esp->current_SC = NULL;
        }

        /* Clean up disconnected queue, they have been invalidated
         * by the bus reset.
         */
        if (esp->disconnected_SC) {
                while((sp = remove_first_SC(&esp->disconnected_SC)) != NULL) {
                        esp_release_dmabufs(esp, sp);
                        sp->result = (DID_RESET << 16);
                        sp->scsi_done(sp);
                }
        }

        /* SCSI bus reset is complete. */
        esp->resetting_bus = 0;
        wake_up(&esp->reset_queue);

        /* Ok, now it is safe to get commands going once more. */
        if(esp->issue_SC)
                esp_exec_cmd(esp);

        return do_intr_end;
}

static int esp_do_resetbus(struct NCR_ESP *esp,
                           struct ESP_regs *eregs)
{
        ESPLOG(("esp%d: Resetting scsi bus\n", esp->esp_id));
        esp->resetting_bus = 1;
        esp_cmd(esp, eregs, ESP_CMD_RS);

        return do_intr_end;
}

/* Reset ESP chip, reset hanging bus, then kill active and
 * disconnected commands for targets without soft reset.
 *
 * The host_lock is acquired by caller.
 */
int esp_reset(Scsi_Cmnd *SCptr)
{
        struct NCR_ESP *esp = (struct NCR_ESP *) SCptr->device->host->hostdata;

        spin_lock_irq(esp->ehost->host_lock);
        (void) esp_do_resetbus(esp, esp->eregs);
        spin_unlock_irq(esp->ehost->host_lock);

        wait_event(esp->reset_queue, (esp->resetting_bus == 0));

        return SUCCESS;
}

/* Internal ESP done function. */
static void esp_done(struct NCR_ESP *esp, int error)
{
        Scsi_Cmnd *done_SC;

        if(esp->current_SC) {
                done_SC = esp->current_SC;
                esp->current_SC = NULL;
                esp_release_dmabufs(esp, done_SC);
                done_SC->result = error;
                done_SC->scsi_done(done_SC);

                /* Bus is free, issue any commands in the queue. */
                if(esp->issue_SC && !esp->current_SC)
                        esp_exec_cmd(esp);
        } else {
                /* Panic is safe as current_SC is null so we may still
                 * be able to accept more commands to sync disk buffers.
                 */
                ESPLOG(("panicing\n"));
                panic("esp: done() called with NULL esp->current_SC");
        }
}

/* Wheee, ESP interrupt engine. */  

/* Forward declarations. */
static int esp_do_phase_determine(struct NCR_ESP *esp, 
                                  struct ESP_regs *eregs);
static int esp_do_data_finale(struct NCR_ESP *esp, struct ESP_regs *eregs);
static int esp_select_complete(struct NCR_ESP *esp, struct ESP_regs *eregs);
static int esp_do_status(struct NCR_ESP *esp, struct ESP_regs *eregs);
static int esp_do_msgin(struct NCR_ESP *esp, struct ESP_regs *eregs);
static int esp_do_msgindone(struct NCR_ESP *esp, struct ESP_regs *eregs);
static int esp_do_msgout(struct NCR_ESP *esp, struct ESP_regs *eregs);
static int esp_do_cmdbegin(struct NCR_ESP *esp, struct ESP_regs *eregs);

#define sreg_datainp(__sreg)  (((__sreg) & ESP_STAT_PMASK) == ESP_DIP)
#define sreg_dataoutp(__sreg) (((__sreg) & ESP_STAT_PMASK) == ESP_DOP)

/* We try to avoid some interrupts by jumping ahead and see if the ESP
 * has gotten far enough yet.  Hence the following.
 */
static inline int skipahead1(struct NCR_ESP *esp, struct ESP_regs *eregs,
                             Scsi_Cmnd *scp, int prev_phase, int new_phase)
{
        if(scp->SCp.sent_command != prev_phase)
                return 0;

        if(esp->dma_irq_p(esp)) {
                /* Yes, we are able to save an interrupt. */
                esp->sreg = (esp_read(eregs->esp_status) & ~(ESP_STAT_INTR));
                esp->ireg = esp_read(eregs->esp_intrpt);
                if(!(esp->ireg & ESP_INTR_SR))
                        return 0;
                else
                        return do_reset_complete;
        }
        /* Ho hum, target is taking forever... */
        scp->SCp.sent_command = new_phase; /* so we don't recurse... */
        return do_intr_end;
}

static inline int skipahead2(struct NCR_ESP *esp,
                             struct ESP_regs *eregs,
                             Scsi_Cmnd *scp, int prev_phase1, int prev_phase2,
                             int new_phase)
{
        if(scp->SCp.sent_command != prev_phase1 &&
           scp->SCp.sent_command != prev_phase2)
                return 0;
        if(esp->dma_irq_p(esp)) {
                /* Yes, we are able to save an interrupt. */
                esp->sreg = (esp_read(eregs->esp_status) & ~(ESP_STAT_INTR));
                esp->ireg = esp_read(eregs->esp_intrpt);
                if(!(esp->ireg & ESP_INTR_SR))
                        return 0;
                else
                        return do_reset_complete;
        }
        /* Ho hum, target is taking forever... */
        scp->SCp.sent_command = new_phase; /* so we don't recurse... */
        return do_intr_end;
}

/* Misc. esp helper macros. */
#define esp_setcount(__eregs, __cnt) \
        esp_write((__eregs)->esp_tclow, ((__cnt) & 0xff)); \
        esp_write((__eregs)->esp_tcmed, (((__cnt) >> 8) & 0xff))

#define esp_getcount(__eregs) \
        ((esp_read((__eregs)->esp_tclow)&0xff) | \
         ((esp_read((__eregs)->esp_tcmed)&0xff) << 8))

#define fcount(__esp, __eregs) \
        (esp_read((__eregs)->esp_fflags) & ESP_FF_FBYTES)

#define fnzero(__esp, __eregs) \
        (esp_read((__eregs)->esp_fflags) & ESP_FF_ONOTZERO)

/* XXX speculative nops unnecessary when continuing amidst a data phase
 * XXX even on esp100!!!  another case of flooding the bus with I/O reg
 * XXX writes...
 */
#define esp_maybe_nop(__esp, __eregs) \
        if((__esp)->erev == esp100) \
                esp_cmd((__esp), (__eregs), ESP_CMD_NULL)

#define sreg_to_dataphase(__sreg) \
        ((((__sreg) & ESP_STAT_PMASK) == ESP_DOP) ? in_dataout : in_datain)

/* The ESP100 when in synchronous data phase, can mistake a long final
 * REQ pulse from the target as an extra byte, it places whatever is on
 * the data lines into the fifo.  For now, we will assume when this
 * happens that the target is a bit quirky and we don't want to
 * be talking synchronously to it anyways.  Regardless, we need to
 * tell the ESP to eat the extraneous byte so that we can proceed
 * to the next phase.
 */
static inline int esp100_sync_hwbug(struct NCR_ESP *esp, struct ESP_regs *eregs,
                                    Scsi_Cmnd *sp, int fifocnt)
{
        /* Do not touch this piece of code. */
        if((!(esp->erev == esp100)) ||
           (!(sreg_datainp((esp->sreg = esp_read(eregs->esp_status))) && !fifocnt) &&
            !(sreg_dataoutp(esp->sreg) && !fnzero(esp, eregs)))) {
                if(sp->SCp.phase == in_dataout)
                        esp_cmd(esp, eregs, ESP_CMD_FLUSH);
                return 0;
        } else {
                /* Async mode for this guy. */
                build_sync_nego_msg(esp, 0, 0);

                /* Ack the bogus byte, but set ATN first. */
                esp_cmd(esp, eregs, ESP_CMD_SATN);
                esp_cmd(esp, eregs, ESP_CMD_MOK);
                return 1;
        }
}

/* This closes the window during a selection with a reselect pending, because
 * we use DMA for the selection process the FIFO should hold the correct
 * contents if we get reselected during this process.  So we just need to
 * ack the possible illegal cmd interrupt pending on the esp100.
 */
static inline int esp100_reconnect_hwbug(struct NCR_ESP *esp,
                                         struct ESP_regs *eregs)
{
        volatile unchar junk;

        if(esp->erev != esp100)
                return 0;
        junk = esp_read(eregs->esp_intrpt);

        if(junk & ESP_INTR_SR)
                return 1;
        return 0;
}

/* This verifies the BUSID bits during a reselection so that we know which
 * target is talking to us.
 */
static inline int reconnect_target(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        int it, me = esp->scsi_id_mask, targ = 0;

        if(2 != fcount(esp, eregs))
                return -1;
        it = esp_read(eregs->esp_fdata);
        if(!(it & me))
                return -1;
        it &= ~me;
        if(it & (it - 1))
                return -1;
        while(!(it & 1))
                targ++, it >>= 1;
        return targ;
}

/* This verifies the identify from the target so that we know which lun is
 * being reconnected.
 */
static inline int reconnect_lun(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        int lun;

        if((esp->sreg & ESP_STAT_PMASK) != ESP_MIP)
                return -1;
        lun = esp_read(eregs->esp_fdata);

        /* Yes, you read this correctly.  We report lun of zero
         * if we see parity error.  ESP reports parity error for
         * the lun byte, and this is the only way to hope to recover
         * because the target is connected.
         */
        if(esp->sreg & ESP_STAT_PERR)
                return 0;

        /* Check for illegal bits being set in the lun. */
        if((lun & 0x40) || !(lun & 0x80))
                return -1;

        return lun & 7;
}

/* This puts the driver in a state where it can revitalize a command that
 * is being continued due to reselection.
 */
static inline void esp_connect(struct NCR_ESP *esp, struct ESP_regs *eregs,
                               Scsi_Cmnd *sp)
{
        struct scsi_device *dp = sp->device;
        struct esp_device *esp_dev = dp->hostdata;

        if(esp->prev_soff  != esp_dev->sync_max_offset ||
           esp->prev_stp   != esp_dev->sync_min_period ||
           (esp->erev > esp100a &&
            esp->prev_cfg3 != esp->config3[scmd_id(sp)])) {
                esp->prev_soff = esp_dev->sync_max_offset;
                esp_write(eregs->esp_soff, esp->prev_soff);
                esp->prev_stp = esp_dev->sync_min_period;
                esp_write(eregs->esp_stp, esp->prev_stp);
                if(esp->erev > esp100a) {
                        esp->prev_cfg3 = esp->config3[scmd_id(sp)];
                        esp_write(eregs->esp_cfg3, esp->prev_cfg3);
                } 
        }
        esp->current_SC = sp;
}

/* This will place the current working command back into the issue queue
 * if we are to receive a reselection amidst a selection attempt.
 */
static inline void esp_reconnect(struct NCR_ESP *esp, Scsi_Cmnd *sp)
{
        if(!esp->disconnected_SC)
                ESPLOG(("esp%d: Weird, being reselected but disconnected "
                        "command queue is empty.\n", esp->esp_id));
        esp->snip = 0;
        esp->current_SC = NULL;
        sp->SCp.phase = not_issued;
        append_SC(&esp->issue_SC, sp);
}

/* Begin message in phase. */
static int esp_do_msgin(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        esp_cmd(esp, eregs, ESP_CMD_FLUSH);
        esp_maybe_nop(esp, eregs);
        esp_cmd(esp, eregs, ESP_CMD_TI);
        esp->msgin_len = 1;
        esp->msgin_ctr = 0;
        esp_advance_phase(esp->current_SC, in_msgindone);
        return do_work_bus;
}

static inline void advance_sg(struct NCR_ESP *esp, Scsi_Cmnd *sp)
{
        ++sp->SCp.buffer;
        --sp->SCp.buffers_residual;
        sp->SCp.this_residual = sp->SCp.buffer->length;
        if (esp->dma_advance_sg)
                esp->dma_advance_sg (sp);
        else
                sp->SCp.ptr = (char *) virt_to_phys((page_address(sp->SCp.buffer->page) + sp->SCp.buffer->offset));

}

/* Please note that the way I've coded these routines is that I _always_
 * check for a disconnect during any and all information transfer
 * phases.  The SCSI standard states that the target _can_ cause a BUS
 * FREE condition by dropping all MSG/CD/IO/BSY signals.  Also note
 * that during information transfer phases the target controls every
 * change in phase, the only thing the initiator can do is "ask" for
 * a message out phase by driving ATN true.  The target can, and sometimes
 * will, completely ignore this request so we cannot assume anything when
 * we try to force a message out phase to abort/reset a target.  Most of
 * the time the target will eventually be nice and go to message out, so
 * we may have to hold on to our state about what we want to tell the target
 * for some period of time.
 */

/* I think I have things working here correctly.  Even partial transfers
 * within a buffer or sub-buffer should not upset us at all no matter
 * how bad the target and/or ESP fucks things up.
 */
static int esp_do_data(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        Scsi_Cmnd *SCptr = esp->current_SC;
        int thisphase, hmuch;

        ESPDATA(("esp_do_data: "));
        esp_maybe_nop(esp, eregs);
        thisphase = sreg_to_dataphase(esp->sreg);
        esp_advance_phase(SCptr, thisphase);
        ESPDATA(("newphase<%s> ", (thisphase == in_datain) ? "DATAIN" : "DATAOUT"));
        hmuch = esp->dma_can_transfer(esp, SCptr);

        /*
         * XXX MSch: cater for PIO transfer here; PIO used if hmuch == 0
         */
        if (hmuch) {    /* DMA */
                /*
                 * DMA
                 */
                ESPDATA(("hmuch<%d> ", hmuch));
                esp->current_transfer_size = hmuch;
                esp_setcount(eregs, (esp->fas_premature_intr_workaround ?
                                     (hmuch + 0x40) : hmuch));
                esp->dma_setup(esp, (__u32)((unsigned long)SCptr->SCp.ptr), 
                               hmuch, (thisphase == in_datain));
                ESPDATA(("DMA|TI --> do_intr_end\n"));
                esp_cmd(esp, eregs, ESP_CMD_DMA | ESP_CMD_TI);
                return do_intr_end;
                /*
                 * end DMA
                 */
        } else {
                /*
                 * PIO
                 */
                int oldphase, i = 0; /* or where we left off last time ?? esp->current_data ?? */
                int fifocnt = 0;
                unsigned char *p = phys_to_virt((unsigned long)SCptr->SCp.ptr);

                oldphase = esp_read(eregs->esp_status) & ESP_STAT_PMASK;

                /*
                 * polled transfer; ugly, can we make this happen in a DRQ 
                 * interrupt handler ??
                 * requires keeping track of state information in host or 
                 * command struct!
                 * Problem: I've never seen a DRQ happen on Mac, not even
                 * with ESP_CMD_DMA ...
                 */

                /* figure out how much needs to be transferred */
                hmuch = SCptr->SCp.this_residual;
                ESPDATA(("hmuch<%d> pio ", hmuch));
                esp->current_transfer_size = hmuch;

                /* tell the ESP ... */
                esp_setcount(eregs, hmuch);

                /* loop */
                while (hmuch) {
                        int j, fifo_stuck = 0, newphase;
                        unsigned long timeout;
#if 0
                        unsigned long flags;
#endif
#if 0
                        if ( i % 10 )
                                ESPDATA(("\r"));
                        else
                                ESPDATA(( /*"\n"*/ "\r"));
#endif
#if 0
                        local_irq_save(flags);
#endif
                        if(thisphase == in_datain) {
                                /* 'go' ... */ 
                                esp_cmd(esp, eregs, ESP_CMD_TI);

                                /* wait for data */
                                timeout = 1000000;
                                while (!((esp->sreg=esp_read(eregs->esp_status)) & ESP_STAT_INTR) && --timeout)
                                        udelay(2);
                                if (timeout == 0)
                                        printk("DRQ datain timeout! \n");

                                newphase = esp->sreg & ESP_STAT_PMASK;

                                /* see how much we got ... */
                                fifocnt = (esp_read(eregs->esp_fflags) & ESP_FF_FBYTES);

                                if (!fifocnt)
                                        fifo_stuck++;
                                else
                                        fifo_stuck = 0;

                                ESPDATA(("\rgot %d st %x ph %x", fifocnt, esp->sreg, newphase));

                                /* read fifo */
                                for(j=0;j<fifocnt;j++)
                                        p[i++] = esp_read(eregs->esp_fdata);

                                ESPDATA(("(%d) ", i));

                                /* how many to go ?? */
                                hmuch -= fifocnt;

                                /* break if status phase !! */
                                if(newphase == ESP_STATP) {
                                        /* clear int. */
                                        esp->ireg = esp_read(eregs->esp_intrpt);
                                        break;
                                }
                        } else {
#define MAX_FIFO 8
                                /* how much will fit ? */
                                int this_count = MAX_FIFO - fifocnt;
                                if (this_count > hmuch)
                                        this_count = hmuch;

                                /* fill fifo */
                                for(j=0;j<this_count;j++)
                                        esp_write(eregs->esp_fdata, p[i++]);

                                /* how many left if this goes out ?? */
                                hmuch -= this_count;

                                /* 'go' ... */ 
                                esp_cmd(esp, eregs, ESP_CMD_TI);

                                /* wait for 'got it' */
                                timeout = 1000000;
                                while (!((esp->sreg=esp_read(eregs->esp_status)) & ESP_STAT_INTR) && --timeout)
                                        udelay(2);
                                if (timeout == 0)
                                        printk("DRQ dataout timeout!  \n");

                                newphase = esp->sreg & ESP_STAT_PMASK;

                                /* need to check how much was sent ?? */
                                fifocnt = (esp_read(eregs->esp_fflags) & ESP_FF_FBYTES);

                                ESPDATA(("\rsent %d st %x ph %x", this_count - fifocnt, esp->sreg, newphase));

                                ESPDATA(("(%d) ", i));

                                /* break if status phase !! */
                                if(newphase == ESP_STATP) {
                                        /* clear int. */
                                        esp->ireg = esp_read(eregs->esp_intrpt);
                                        break;
                                }

                        }

                        /* clear int. */
                        esp->ireg = esp_read(eregs->esp_intrpt);

                        ESPDATA(("ir %x ... ", esp->ireg));

                        if (hmuch == 0)
                                ESPDATA(("done! \n"));

#if 0
                        local_irq_restore(flags);
#endif

                        /* check new bus phase */
                        if (newphase != oldphase && i < esp->current_transfer_size) {
                                /* something happened; disconnect ?? */
                                ESPDATA(("phase change, dropped out with %d done ... ", i));
                                break;
                        }

                        /* check int. status */
                        if (esp->ireg & ESP_INTR_DC) {
                                /* disconnect */
                                ESPDATA(("disconnect; %d transferred ... ", i));
                                break;
                        } else if (esp->ireg & ESP_INTR_FDONE) {
                                /* function done */
                                ESPDATA(("function done; %d transferred ... ", i));
                                break;
                        }

                        /* XXX fixme: bail out on stall */
                        if (fifo_stuck > 10) {
                                /* we're stuck */
                                ESPDATA(("fifo stall; %d transferred ... ", i));
                                break;
                        }
                }

                ESPDATA(("\n"));
                /* check successful completion ?? */

                if (thisphase == in_dataout)
                        hmuch += fifocnt; /* stuck?? adjust data pointer ...*/

                /* tell do_data_finale how much was transferred */
                esp->current_transfer_size -= hmuch;

                /* still not completely sure on this one ... */         
                return /*do_intr_end*/ do_work_bus /*do_phase_determine*/ ;

                /*
                 * end PIO
                 */
        }
        return do_intr_end;
}

/* See how successful the data transfer was. */
static int esp_do_data_finale(struct NCR_ESP *esp,
                              struct ESP_regs *eregs)
{
        Scsi_Cmnd *SCptr = esp->current_SC;
        struct esp_device *esp_dev = SCptr->device->hostdata;
        int bogus_data = 0, bytes_sent = 0, fifocnt, ecount = 0;

        if(esp->dma_led_off)
                esp->dma_led_off(esp);

        ESPDATA(("esp_do_data_finale: "));

        if(SCptr->SCp.phase == in_datain) {
                if(esp->sreg & ESP_STAT_PERR) {
                        /* Yuck, parity error.  The ESP asserts ATN
                         * so that we can go to message out phase
                         * immediately and inform the target that
                         * something bad happened.
                         */
                        ESPLOG(("esp%d: data bad parity detected.\n",
                                esp->esp_id));
                        esp->cur_msgout[0] = INITIATOR_ERROR;
                        esp->msgout_len = 1;
                }
                if(esp->dma_drain)
                        esp->dma_drain(esp);
        }
        if(esp->dma_invalidate)
                esp->dma_invalidate(esp);

        /* This could happen for the above parity error case. */
        if(!(esp->ireg == ESP_INTR_BSERV)) {
                /* Please go to msgout phase, please please please... */
                ESPLOG(("esp%d: !BSERV after data, probably to msgout\n",
                        esp->esp_id));
                return esp_do_phase_determine(esp, eregs);
        }       

        /* Check for partial transfers and other horrible events. */
        fifocnt = (esp_read(eregs->esp_fflags) & ESP_FF_FBYTES);
        ecount = esp_getcount(eregs);
        if(esp->fas_premature_intr_workaround)
                ecount -= 0x40;
        bytes_sent = esp->current_transfer_size;

        ESPDATA(("trans_sz=%d, ", bytes_sent));
        if(!(esp->sreg & ESP_STAT_TCNT))
                bytes_sent -= ecount;
        if(SCptr->SCp.phase == in_dataout)
                bytes_sent -= fifocnt;

        ESPDATA(("bytes_sent=%d (ecount=%d, fifocnt=%d), ", bytes_sent,
                 ecount, fifocnt));

        /* If we were in synchronous mode, check for peculiarities. */
        if(esp_dev->sync_max_offset)
                bogus_data = esp100_sync_hwbug(esp, eregs, SCptr, fifocnt);
        else
                esp_cmd(esp, eregs, ESP_CMD_FLUSH);

        /* Until we are sure of what has happened, we are certainly
         * in the dark.
         */
        esp_advance_phase(SCptr, in_the_dark);

        /* Check for premature interrupt condition. Can happen on FAS2x6
         * chips. QLogic recommends a workaround by overprogramming the
         * transfer counters, but this makes doing scatter-gather impossible.
         * Until there is a way to disable scatter-gather for a single target,
         * and not only for the entire host adapter as it is now, the workaround
         * is way to expensive performance wise.
         * Instead, it turns out that when this happens the target has disconnected
         * already but it doesn't show in the interrupt register. Compensate for
         * that here to try and avoid a SCSI bus reset.
         */
        if(!esp->fas_premature_intr_workaround && (fifocnt == 1) &&
           sreg_dataoutp(esp->sreg)) {
                ESPLOG(("esp%d: Premature interrupt, enabling workaround\n",
                        esp->esp_id));
#if 0
                /* Disable scatter-gather operations, they are not possible
                 * when using this workaround.
                 */
                esp->ehost->sg_tablesize = 0;
                esp->ehost->use_clustering = ENABLE_CLUSTERING;
                esp->fas_premature_intr_workaround = 1;
                bytes_sent = 0;
                if(SCptr->use_sg) {
                        ESPLOG(("esp%d: Aborting scatter-gather operation\n",
                                esp->esp_id));
                        esp->cur_msgout[0] = ABORT;
                        esp->msgout_len = 1;
                        esp->msgout_ctr = 0;
                        esp_cmd(esp, eregs, ESP_CMD_SATN);
                        esp_setcount(eregs, 0xffff);
                        esp_cmd(esp, eregs, ESP_CMD_NULL);
                        esp_cmd(esp, eregs, ESP_CMD_TPAD | ESP_CMD_DMA);
                        return do_intr_end;
                }
#else
                /* Just set the disconnected bit. That's what appears to
                 * happen anyway. The state machine will pick it up when
                 * we return.
                 */
                esp->ireg |= ESP_INTR_DC;
#endif
        }

        if(bytes_sent < 0) {
                /* I've seen this happen due to lost state in this
                 * driver.  No idea why it happened, but allowing
                 * this value to be negative caused things to
                 * lock up.  This allows greater chance of recovery.
                 * In fact every time I've seen this, it has been
                 * a driver bug without question.
                 */
                ESPLOG(("esp%d: yieee, bytes_sent < 0!\n", esp->esp_id));
                ESPLOG(("esp%d: csz=%d fifocount=%d ecount=%d\n",
                        esp->esp_id,
                        esp->current_transfer_size, fifocnt, ecount));
                ESPLOG(("esp%d: use_sg=%d ptr=%p this_residual=%d\n",
                        esp->esp_id,
                        SCptr->use_sg, SCptr->SCp.ptr, SCptr->SCp.this_residual));
                ESPLOG(("esp%d: Forcing async for target %d\n", esp->esp_id, 
                        SCptr->device->id));
                SCptr->device->borken = 1;
                esp_dev->sync = 0;
                bytes_sent = 0;
        }

        /* Update the state of our transfer. */
        SCptr->SCp.ptr += bytes_sent;
        SCptr->SCp.this_residual -= bytes_sent;
        if(SCptr->SCp.this_residual < 0) {
                /* shit */
                ESPLOG(("esp%d: Data transfer overrun.\n", esp->esp_id));
                SCptr->SCp.this_residual = 0;
        }

        /* Maybe continue. */
        if(!bogus_data) {
                ESPDATA(("!bogus_data, "));
                /* NO MATTER WHAT, we advance the scatterlist,
                 * if the target should decide to disconnect
                 * in between scatter chunks (which is common)
                 * we could die horribly!  I used to have the sg
                 * advance occur only if we are going back into
                 * (or are staying in) a data phase, you can
                 * imagine the hell I went through trying to
                 * figure this out.
                 */
                if(!SCptr->SCp.this_residual && SCptr->SCp.buffers_residual)
                        advance_sg(esp, SCptr);
#ifdef DEBUG_ESP_DATA
                if(sreg_datainp(esp->sreg) || sreg_dataoutp(esp->sreg)) {
                        ESPDATA(("to more data\n"));
                } else {
                        ESPDATA(("to new phase\n"));
                }
#endif
                return esp_do_phase_determine(esp, eregs);
        }
        /* Bogus data, just wait for next interrupt. */
        ESPLOG(("esp%d: bogus_data during end of data phase\n",
                esp->esp_id));
        return do_intr_end;
}

/* We received a non-good status return at the end of
 * running a SCSI command.  This is used to decide if
 * we should clear our synchronous transfer state for
 * such a device when that happens.
 *
 * The idea is that when spinning up a disk or rewinding
 * a tape, we don't want to go into a loop re-negotiating
 * synchronous capabilities over and over.
 */
static int esp_should_clear_sync(Scsi_Cmnd *sp)
{
        unchar cmd = sp->cmnd[0];

        /* These cases are for spinning up a disk and
         * waiting for that spinup to complete.
         */
        if(cmd == START_STOP)
                return 0;

        if(cmd == TEST_UNIT_READY)
                return 0;

        /* One more special case for SCSI tape drives,
         * this is what is used to probe the device for
         * completion of a rewind or tape load operation.
         */
        if(sp->device->type == TYPE_TAPE && cmd == MODE_SENSE)
                return 0;

        return 1;
}

/* Either a command is completing or a target is dropping off the bus
 * to continue the command in the background so we can do other work.
 */
static int esp_do_freebus(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        Scsi_Cmnd *SCptr = esp->current_SC;
        int rval;

        rval = skipahead2(esp, eregs, SCptr, in_status, in_msgindone, in_freeing);
        if(rval)
                return rval;

        if(esp->ireg != ESP_INTR_DC) {
                ESPLOG(("esp%d: Target will not disconnect\n", esp->esp_id));
                return do_reset_bus; /* target will not drop BSY... */
        }
        esp->msgout_len = 0;
        esp->prevmsgout = NOP;
        if(esp->prevmsgin == COMMAND_COMPLETE) {
                struct esp_device *esp_dev = SCptr->device->hostdata;
                /* Normal end of nexus. */
                if(esp->disconnected_SC)
                        esp_cmd(esp, eregs, ESP_CMD_ESEL);

                if(SCptr->SCp.Status != GOOD &&
                   SCptr->SCp.Status != CONDITION_GOOD &&
                   ((1<<scmd_id(SCptr)) & esp->targets_present) &&
                   esp_dev->sync && esp_dev->sync_max_offset) {
                        /* SCSI standard says that the synchronous capabilities
                         * should be renegotiated at this point.  Most likely
                         * we are about to request sense from this target
                         * in which case we want to avoid using sync
                         * transfers until we are sure of the current target
                         * state.
                         */
                        ESPMISC(("esp: Status <%d> for target %d lun %d\n",
                                 SCptr->SCp.Status, SCptr->device->id, SCptr->device->lun));

                        /* But don't do this when spinning up a disk at
                         * boot time while we poll for completion as it
                         * fills up the console with messages.  Also, tapes
                         * can report not ready many times right after
                         * loading up a tape.
                         */
                        if(esp_should_clear_sync(SCptr) != 0)
                                esp_dev->sync = 0;
                }
                ESPDISC(("F<%02x,%02x>", SCptr->device->id, SCptr->device->lun));
                esp_done(esp, ((SCptr->SCp.Status & 0xff) |
                               ((SCptr->SCp.Message & 0xff)<<8) |
                               (DID_OK << 16)));
        } else if(esp->prevmsgin == DISCONNECT) {
                /* Normal disconnect. */
                esp_cmd(esp, eregs, ESP_CMD_ESEL);
                ESPDISC(("D<%02x,%02x>", SCptr->device->id, SCptr->device->lun));
                append_SC(&esp->disconnected_SC, SCptr);
                esp->current_SC = NULL;
                if(esp->issue_SC)
                        esp_exec_cmd(esp);
        } else {
                /* Driver bug, we do not expect a disconnect here
                 * and should not have advanced the state engine
                 * to in_freeing.
                 */
                ESPLOG(("esp%d: last msg not disc and not cmd cmplt.\n",
                        esp->esp_id));
                return do_reset_bus;
        }
        return do_intr_end;
}

/* When a reselect occurs, and we cannot find the command to
 * reconnect to in our queues, we do this.
 */
static int esp_bad_reconnect(struct NCR_ESP *esp)
{
        Scsi_Cmnd *sp;

        ESPLOG(("esp%d: Eieeee, reconnecting unknown command!\n",
                esp->esp_id));
        ESPLOG(("QUEUE DUMP\n"));
        sp = esp->issue_SC;
        ESPLOG(("esp%d: issue_SC[", esp->esp_id));
        while(sp) {
                ESPLOG(("<%02x,%02x>", sp->device->id, sp->device->lun));
                sp = (Scsi_Cmnd *) sp->host_scribble;
        }
        ESPLOG(("]\n"));
        sp = esp->current_SC;
        ESPLOG(("esp%d: current_SC[", esp->esp_id));
        while(sp) {
                ESPLOG(("<%02x,%02x>", sp->device->id, sp->device->lun));
                sp = (Scsi_Cmnd *) sp->host_scribble;
        }
        ESPLOG(("]\n"));
        sp = esp->disconnected_SC;
        ESPLOG(("esp%d: disconnected_SC[", esp->esp_id));
        while(sp) {
                ESPLOG(("<%02x,%02x>", sp->device->id, sp->device->lun));
                sp = (Scsi_Cmnd *) sp->host_scribble;
        }
        ESPLOG(("]\n"));
        return do_reset_bus;
}

/* Do the needy when a target tries to reconnect to us. */
static int esp_do_reconnect(struct NCR_ESP *esp, 
                            struct ESP_regs *eregs)
{
        int lun, target;
        Scsi_Cmnd *SCptr;

        /* Check for all bogus conditions first. */
        target = reconnect_target(esp, eregs);
        if(target < 0) {
                ESPDISC(("bad bus bits\n"));
                return do_reset_bus;
        }
        lun = reconnect_lun(esp, eregs);
        if(lun < 0) {
                ESPDISC(("target=%2x, bad identify msg\n", target));
                return do_reset_bus;
        }

        /* Things look ok... */
        ESPDISC(("R<%02x,%02x>", target, lun));

        esp_cmd(esp, eregs, ESP_CMD_FLUSH);
        if(esp100_reconnect_hwbug(esp, eregs))
                return do_reset_bus;
        esp_cmd(esp, eregs, ESP_CMD_NULL);

        SCptr = remove_SC(&esp->disconnected_SC, (unchar) target, (unchar) lun);
        if(!SCptr)
                return esp_bad_reconnect(esp);

        esp_connect(esp, eregs, SCptr);
        esp_cmd(esp, eregs, ESP_CMD_MOK);

        /* Reconnect implies a restore pointers operation. */
        esp_restore_pointers(esp, SCptr);

        esp->snip = 0;
        esp_advance_phase(SCptr, in_the_dark);
        return do_intr_end;
}

/* End of NEXUS (hopefully), pick up status + message byte then leave if
 * all goes well.
 */
static int esp_do_status(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        Scsi_Cmnd *SCptr = esp->current_SC;
        int intr, rval;

        rval = skipahead1(esp, eregs, SCptr, in_the_dark, in_status);
        if(rval)
                return rval;

        intr = esp->ireg;
        ESPSTAT(("esp_do_status: "));
        if(intr != ESP_INTR_DC) {
                int message_out = 0; /* for parity problems */

                /* Ack the message. */
                ESPSTAT(("ack msg, "));
                esp_cmd(esp, eregs, ESP_CMD_MOK);

                if(esp->dma_poll)
                        esp->dma_poll(esp, (unsigned char *) esp->esp_command);

                ESPSTAT(("got something, "));
                /* ESP chimes in with one of
                 *
                 * 1) function done interrupt:
                 *      both status and message in bytes
                 *      are available
                 *
                 * 2) bus service interrupt:
                 *      only status byte was acquired
                 *
                 * 3) Anything else:
                 *      can't happen, but we test for it
                 *      anyways
                 *
                 * ALSO: If bad parity was detected on either
                 *       the status _or_ the message byte then
                 *       the ESP has asserted ATN on the bus
                 *       and we must therefore wait for the
                 *       next phase change.
                 */
                if(intr & ESP_INTR_FDONE) {
                        /* We got it all, hallejulia. */
                        ESPSTAT(("got both, "));
                        SCptr->SCp.Status = esp->esp_command[0];
                        SCptr->SCp.Message = esp->esp_command[1];
                        esp->prevmsgin = SCptr->SCp.Message;
                        esp->cur_msgin[0] = SCptr->SCp.Message;
                        if(esp->sreg & ESP_STAT_PERR) {
                                /* There was bad parity for the
                                 * message byte, the status byte
                                 * was ok.
                                 */
                                message_out = MSG_PARITY_ERROR;
                        }
                } else if(intr == ESP_INTR_BSERV) {
                        /* Only got status byte. */
                        ESPLOG(("esp%d: got status only, ", esp->esp_id));
                        if(!(esp->sreg & ESP_STAT_PERR)) {
                                SCptr->SCp.Status = esp->esp_command[0];
                                SCptr->SCp.Message = 0xff;
                        } else {
                                /* The status byte had bad parity.
                                 * we leave the scsi_pointer Status
                                 * field alone as we set it to a default
                                 * of CHECK_CONDITION in esp_queue.
                                 */
                                message_out = INITIATOR_ERROR;
                        }
                } else {
                        /* This shouldn't happen ever. */
                        ESPSTAT(("got bolixed\n"));
                        esp_advance_phase(SCptr, in_the_dark);
                        return esp_do_phase_determine(esp, eregs);
                }

                if(!message_out) {
                        ESPSTAT(("status=%2x msg=%2x, ", SCptr->SCp.Status,
                                SCptr->SCp.Message));
                        if(SCptr->SCp.Message == COMMAND_COMPLETE) {
                                ESPSTAT(("and was COMMAND_COMPLETE\n"));
                                esp_advance_phase(SCptr, in_freeing);
                                return esp_do_freebus(esp, eregs);
                        } else {
                                ESPLOG(("esp%d: and _not_ COMMAND_COMPLETE\n",
                                        esp->esp_id));
                                esp->msgin_len = esp->msgin_ctr = 1;
                                esp_advance_phase(SCptr, in_msgindone);
                                return esp_do_msgindone(esp, eregs);
                        }
                } else {
                        /* With luck we'll be able to let the target
                         * know that bad parity happened, it will know
                         * which byte caused the problems and send it
                         * again.  For the case where the status byte
                         * receives bad parity, I do not believe most
                         * targets recover very well.  We'll see.
                         */
                        ESPLOG(("esp%d: bad parity somewhere mout=%2x\n",
                                esp->esp_id, message_out));
                        esp->cur_msgout[0] = message_out;
                        esp->msgout_len = esp->msgout_ctr = 1;
                        esp_advance_phase(SCptr, in_the_dark);
                        return esp_do_phase_determine(esp, eregs);
                }
        } else {
                /* If we disconnect now, all hell breaks loose. */
                ESPLOG(("esp%d: whoops, disconnect\n", esp->esp_id));
                esp_advance_phase(SCptr, in_the_dark);
                return esp_do_phase_determine(esp, eregs);
        }
}

static int esp_enter_status(struct NCR_ESP *esp,
                            struct ESP_regs *eregs)
{
        unchar thecmd = ESP_CMD_ICCSEQ;

        esp_cmd(esp, eregs, ESP_CMD_FLUSH);

        if(esp->do_pio_cmds) {
                esp_advance_phase(esp->current_SC, in_status);
                esp_cmd(esp, eregs, thecmd);
                while(!(esp_read(esp->eregs->esp_status) & ESP_STAT_INTR));
                esp->esp_command[0] = esp_read(eregs->esp_fdata);
                while(!(esp_read(esp->eregs->esp_status) & ESP_STAT_INTR));
                esp->esp_command[1] = esp_read(eregs->esp_fdata);
        } else {
                esp->esp_command[0] = esp->esp_command[1] = 0xff;
                esp_write(eregs->esp_tclow, 2);
                esp_write(eregs->esp_tcmed, 0);
                esp->dma_init_read(esp, esp->esp_command_dvma, 2);
                thecmd |= ESP_CMD_DMA;
                esp_cmd(esp, eregs, thecmd);
                esp_advance_phase(esp->current_SC, in_status);
        }

        return esp_do_status(esp, eregs);
}

static int esp_disconnect_amidst_phases(struct NCR_ESP *esp,
                                        struct ESP_regs *eregs)
{
        Scsi_Cmnd *sp = esp->current_SC;
        struct esp_device *esp_dev = sp->device->hostdata;

        /* This means real problems if we see this
         * here.  Unless we were actually trying
         * to force the device to abort/reset.
         */
        ESPLOG(("esp%d: Disconnect amidst phases, ", esp->esp_id));
        ESPLOG(("pphase<%s> cphase<%s>, ",
                phase_string(sp->SCp.phase),
                phase_string(sp->SCp.sent_command)));

        if(esp->disconnected_SC)
                esp_cmd(esp, eregs, ESP_CMD_ESEL);

        switch(esp->cur_msgout[0]) {
        default:
                /* We didn't expect this to happen at all. */
                ESPLOG(("device is bolixed\n"));
                esp_advance_phase(sp, in_tgterror);
                esp_done(esp, (DID_ERROR << 16));
                break;

        case BUS_DEVICE_RESET:
                ESPLOG(("device reset successful\n"));
                esp_dev->sync_max_offset = 0;
                esp_dev->sync_min_period = 0;
                esp_dev->sync = 0;
                esp_advance_phase(sp, in_resetdev);
                esp_done(esp, (DID_RESET << 16));
                break;

        case ABORT:
                ESPLOG(("device abort successful\n"));
                esp_advance_phase(sp, in_abortone);
                esp_done(esp, (DID_ABORT << 16));
                break;

        };
        return do_intr_end;
}

static int esp_enter_msgout(struct NCR_ESP *esp,
                            struct ESP_regs *eregs)
{
        esp_advance_phase(esp->current_SC, in_msgout);
        return esp_do_msgout(esp, eregs);
}

static int esp_enter_msgin(struct NCR_ESP *esp,
                           struct ESP_regs *eregs)
{
        esp_advance_phase(esp->current_SC, in_msgin);
        return esp_do_msgin(esp, eregs);
}

static int esp_enter_cmd(struct NCR_ESP *esp,
                         struct ESP_regs *eregs)
{
        esp_advance_phase(esp->current_SC, in_cmdbegin);
        return esp_do_cmdbegin(esp, eregs);
}

static int esp_enter_badphase(struct NCR_ESP *esp,
                              struct ESP_regs *eregs)
{
        ESPLOG(("esp%d: Bizarre bus phase %2x.\n", esp->esp_id,
                esp->sreg & ESP_STAT_PMASK));
        return do_reset_bus;
}

typedef int (*espfunc_t)(struct NCR_ESP *,
                         struct ESP_regs *);

static espfunc_t phase_vector[] = {
        esp_do_data,            /* ESP_DOP */
        esp_do_data,            /* ESP_DIP */
        esp_enter_cmd,          /* ESP_CMDP */
        esp_enter_status,       /* ESP_STATP */
        esp_enter_badphase,     /* ESP_STAT_PMSG */
        esp_enter_badphase,     /* ESP_STAT_PMSG | ESP_STAT_PIO */
        esp_enter_msgout,       /* ESP_MOP */
        esp_enter_msgin,        /* ESP_MIP */
};

/* The target has control of the bus and we have to see where it has
 * taken us.
 */
static int esp_do_phase_determine(struct NCR_ESP *esp,
                                  struct ESP_regs *eregs)
{
        if ((esp->ireg & ESP_INTR_DC) != 0)
                return esp_disconnect_amidst_phases(esp, eregs);
        return phase_vector[esp->sreg & ESP_STAT_PMASK](esp, eregs);
}

/* First interrupt after exec'ing a cmd comes here. */
static int esp_select_complete(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        Scsi_Cmnd *SCptr = esp->current_SC;
        struct esp_device *esp_dev = SCptr->device->hostdata;
        int cmd_bytes_sent, fcnt;

        fcnt = (esp_read(eregs->esp_fflags) & ESP_FF_FBYTES);
        cmd_bytes_sent = esp->dma_bytes_sent(esp, fcnt);
        if(esp->dma_invalidate)
                esp->dma_invalidate(esp);

        /* Let's check to see if a reselect happened
         * while we we're trying to select.  This must
         * be checked first.
         */
        if(esp->ireg == (ESP_INTR_RSEL | ESP_INTR_FDONE)) {
                esp_reconnect(esp, SCptr);
                return esp_do_reconnect(esp, eregs);
        }

        /* Looks like things worked, we should see a bus service &
         * a function complete interrupt at this point.  Note we
         * are doing a direct comparison because we don't want to
         * be fooled into thinking selection was successful if
         * ESP_INTR_DC is set, see below.
         */
        if(esp->ireg == (ESP_INTR_FDONE | ESP_INTR_BSERV)) {
                /* target speaks... */
                esp->targets_present |= (1<<scmd_id(SCptr));

                /* What if the target ignores the sdtr? */
                if(esp->snip)
                        esp_dev->sync = 1;

                /* See how far, if at all, we got in getting
                 * the information out to the target.
                 */
                switch(esp->seqreg) {
                default:

                case ESP_STEP_ASEL:
                        /* Arbitration won, target selected, but
                         * we are in some phase which is not command
                         * phase nor is it message out phase.
                         *
                         * XXX We've confused the target, obviously.
                         * XXX So clear it's state, but we also end
                         * XXX up clearing everyone elses.  That isn't
                         * XXX so nice.  I'd like to just reset this
                         * XXX target, but if I cannot even get it's
                         * XXX attention and finish selection to talk
                         * XXX to it, there is not much more I can do.
                         * XXX If we have a loaded bus we're going to
                         * XXX spend the next second or so renegotiating
                         * XXX for synchronous transfers.
                         */
                        ESPLOG(("esp%d: STEP_ASEL for tgt %d\n",
                                esp->esp_id, SCptr->device->id));

                case ESP_STEP_SID:
                        /* Arbitration won, target selected, went
                         * to message out phase, sent one message
                         * byte, then we stopped.  ATN is asserted
                         * on the SCSI bus and the target is still
                         * there hanging on.  This is a legal
                         * sequence step if we gave the ESP a select
                         * and stop command.
                         *
                         * XXX See above, I could set the borken flag
                         * XXX in the device struct and retry the
                         * XXX command.  But would that help for
                         * XXX tagged capable targets?
                         */

                case ESP_STEP_NCMD:
                        /* Arbitration won, target selected, maybe
                         * sent the one message byte in message out
                         * phase, but we did not go to command phase
                         * in the end.  Actually, we could have sent
                         * only some of the message bytes if we tried
                         * to send out the entire identify and tag
                         * message using ESP_CMD_SA3.
                         */
                        cmd_bytes_sent = 0;
                        break;

                case ESP_STEP_PPC:
                        /* No, not the powerPC pinhead.  Arbitration
                         * won, all message bytes sent if we went to
                         * message out phase, went to command phase
                         * but only part of the command was sent.
                         *
                         * XXX I've seen this, but usually in conjunction
                         * XXX with a gross error which appears to have
                         * XXX occurred between the time I told the
                         * XXX ESP to arbitrate and when I got the
                         * XXX interrupt.  Could I have misloaded the
                         * XXX command bytes into the fifo?  Actually,
                         * XXX I most likely missed a phase, and therefore
                         * XXX went into never never land and didn't even
                         * XXX know it.  That was the old driver though.
                         * XXX What is even more peculiar is that the ESP
                         * XXX showed the proper function complete and
                         * XXX bus service bits in the interrupt register.
                         */

                case ESP_STEP_FINI4:
                case ESP_STEP_FINI5:
                case ESP_STEP_FINI6:
                case ESP_STEP_FINI7:
                        /* Account for the identify message */
                        if(SCptr->SCp.phase == in_slct_norm)
                                cmd_bytes_sent -= 1;
                };
                esp_cmd(esp, eregs, ESP_CMD_NULL);

                /* Be careful, we could really get fucked during synchronous
                 * data transfers if we try to flush the fifo now.
                 */
                if(!fcnt && /* Fifo is empty and... */
                   /* either we are not doing synchronous transfers or... */
                   (!esp_dev->sync_max_offset ||
                    /* We are not going into data in phase. */
                    ((esp->sreg & ESP_STAT_PMASK) != ESP_DIP)))
                        esp_cmd(esp, eregs, ESP_CMD_FLUSH); /* flush is safe */

                /* See how far we got if this is not a slow command. */
                if(!esp->esp_slowcmd) {
                        if(cmd_bytes_sent < 0)
                                cmd_bytes_sent = 0;
                        if(cmd_bytes_sent != SCptr->cmd_len) {
                                /* Crapola, mark it as a slowcmd
                                 * so that we have some chance of
                                 * keeping the command alive with
                                 * good luck.
                                 *
                                 * XXX Actually, if we didn't send it all
                                 * XXX this means either we didn't set things
                                 * XXX up properly (driver bug) or the target
                                 * XXX or the ESP detected parity on one of
                                 * XXX the command bytes.  This makes much
                                 * XXX more sense, and therefore this code
                                 * XXX should be changed to send out a
                                 * XXX parity error message or if the status
                                 * XXX register shows no parity error then
                                 * XXX just expect the target to bring the
                                 * XXX bus into message in phase so that it
                                 * XXX can send us the parity error message.
                                 * XXX SCSI sucks...
                                 */
                                esp->esp_slowcmd = 1;
                                esp->esp_scmdp = &(SCptr->cmnd[cmd_bytes_sent]);
                                esp->esp_scmdleft = (SCptr->cmd_len - cmd_bytes_sent);
                        }
                }

                /* Now figure out where we went. */
                esp_advance_phase(SCptr, in_the_dark);
                return esp_do_phase_determine(esp, eregs);
        }

        /* Did the target even make it? */
        if(esp->ireg == ESP_INTR_DC) {
                /* wheee... nobody there or they didn't like
                 * what we told it to do, clean up.
                 */

                /* If anyone is off the bus, but working on
                 * a command in the background for us, tell
                 * the ESP to listen for them.
                 */
                if(esp->disconnected_SC)
                        esp_cmd(esp, eregs, ESP_CMD_ESEL);

                if(((1<<SCptr->device->id) & esp->targets_present) &&
                   esp->seqreg && esp->cur_msgout[0] == EXTENDED_MESSAGE &&
                   (SCptr->SCp.phase == in_slct_msg ||
                    SCptr->SCp.phase == in_slct_stop)) {
                        /* shit */
                        esp->snip = 0;
                        ESPLOG(("esp%d: Failed synchronous negotiation for target %d "
                                "lun %d\n", esp->esp_id, SCptr->device->id, SCptr->device->lun));
                        esp_dev->sync_max_offset = 0;
                        esp_dev->sync_min_period = 0;
                        esp_dev->sync = 1; /* so we don't negotiate again */

                        /* Run the command again, this time though we
                         * won't try to negotiate for synchronous transfers.
                         *
                         * XXX I'd like to do something like send an
                         * XXX INITIATOR_ERROR or ABORT message to the
                         * XXX target to tell it, "Sorry I confused you,
                         * XXX please come back and I will be nicer next
                         * XXX time".  But that requires having the target
                         * XXX on the bus, and it has dropped BSY on us.
                         */
                        esp->current_SC = NULL;
                        esp_advance_phase(SCptr, not_issued);
                        prepend_SC(&esp->issue_SC, SCptr);
                        esp_exec_cmd(esp);
                        return do_intr_end;
                }

                /* Ok, this is normal, this is what we see during boot
                 * or whenever when we are scanning the bus for targets.
                 * But first make sure that is really what is happening.
                 */
                if(((1<<SCptr->device->id) & esp->targets_present)) {
                        ESPLOG(("esp%d: Warning, live target %d not responding to "
                                "selection.\n", esp->esp_id, SCptr->device->id));

                        /* This _CAN_ happen.  The SCSI standard states that
                         * the target is to _not_ respond to selection if
                         * _it_ detects bad parity on the bus for any reason.
                         * Therefore, we assume that if we've talked successfully
                         * to this target before, bad parity is the problem.
                         */
                        esp_done(esp, (DID_PARITY << 16));
                } else {
                        /* Else, there really isn't anyone there. */
                        ESPMISC(("esp: selection failure, maybe nobody there?\n"));
                        ESPMISC(("esp: target %d lun %d\n",
                                 SCptr->device->id, SCptr->device->lun));
                        esp_done(esp, (DID_BAD_TARGET << 16));
                }
                return do_intr_end;
        }


        ESPLOG(("esp%d: Selection failure.\n", esp->esp_id));
        printk("esp%d: Currently -- ", esp->esp_id);
        esp_print_ireg(esp->ireg);
        printk(" ");
        esp_print_statreg(esp->sreg);
        printk(" ");
        esp_print_seqreg(esp->seqreg);
        printk("\n");
        printk("esp%d: New -- ", esp->esp_id);
        esp->sreg = esp_read(eregs->esp_status);
        esp->seqreg = esp_read(eregs->esp_sstep);
        esp->ireg = esp_read(eregs->esp_intrpt);
        esp_print_ireg(esp->ireg);
        printk(" ");
        esp_print_statreg(esp->sreg);
        printk(" ");
        esp_print_seqreg(esp->seqreg);
        printk("\n");
        ESPLOG(("esp%d: resetting bus\n", esp->esp_id));
        return do_reset_bus; /* ugh... */
}

/* Continue reading bytes for msgin phase. */
static int esp_do_msgincont(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        if(esp->ireg & ESP_INTR_BSERV) {
                /* in the right phase too? */
                if((esp->sreg & ESP_STAT_PMASK) == ESP_MIP) {
                        /* phew... */
                        esp_cmd(esp, eregs, ESP_CMD_TI);
                        esp_advance_phase(esp->current_SC, in_msgindone);
                        return do_intr_end;
                }

                /* We changed phase but ESP shows bus service,
                 * in this case it is most likely that we, the
                 * hacker who has been up for 20hrs straight
                 * staring at the screen, drowned in coffee
                 * smelling like retched cigarette ashes
                 * have miscoded something..... so, try to
                 * recover as best we can.
                 */
                ESPLOG(("esp%d: message in mis-carriage.\n", esp->esp_id));
        }
        esp_advance_phase(esp->current_SC, in_the_dark);
        return do_phase_determine;
}

static int check_singlebyte_msg(struct NCR_ESP *esp,
                                struct ESP_regs *eregs)
{
        esp->prevmsgin = esp->cur_msgin[0];
        if(esp->cur_msgin[0] & 0x80) {
                /* wheee... */
                ESPLOG(("esp%d: target sends identify amidst phases\n",
                        esp->esp_id));
                esp_advance_phase(esp->current_SC, in_the_dark);
                return 0;
        } else if(((esp->cur_msgin[0] & 0xf0) == 0x20) ||
                  (esp->cur_msgin[0] == EXTENDED_MESSAGE)) {
                esp->msgin_len = 2;
                esp_advance_phase(esp->current_SC, in_msgincont);
                return 0;
        }
        esp_advance_phase(esp->current_SC, in_the_dark);
        switch(esp->cur_msgin[0]) {
        default:
                /* We don't want to hear about it. */
                ESPLOG(("esp%d: msg %02x which we don't know about\n", esp->esp_id,
                        esp->cur_msgin[0]));
                return MESSAGE_REJECT;

        case NOP:
                ESPLOG(("esp%d: target %d sends a nop\n", esp->esp_id,
                        esp->current_SC->device->id));
                return 0;

        case RESTORE_POINTERS:
                /* In this case we might also have to backup the
                 * "slow command" pointer.  It is rare to get such
                 * a save/restore pointer sequence so early in the
                 * bus transition sequences, but cover it.
                 */
                if(esp->esp_slowcmd) {
                        esp->esp_scmdleft = esp->current_SC->cmd_len;
                        esp->esp_scmdp = &esp->current_SC->cmnd[0];
                }
                esp_restore_pointers(esp, esp->current_SC);
                return 0;

        case SAVE_POINTERS:
                esp_save_pointers(esp, esp->current_SC);
                return 0;

        case COMMAND_COMPLETE:
        case DISCONNECT:
                /* Freeing the bus, let it go. */
                esp->current_SC->SCp.phase = in_freeing;
                return 0;

        case MESSAGE_REJECT:
                ESPMISC(("msg reject, "));
                if(esp->prevmsgout == EXTENDED_MESSAGE) {
                        struct esp_device *esp_dev = esp->current_SC->device->hostdata;

                        /* Doesn't look like this target can
                         * do synchronous or WIDE transfers.
                         */
                        ESPSDTR(("got reject, was trying nego, clearing sync/WIDE\n"));
                        esp_dev->sync = 1;
                        esp_dev->wide = 1;
                        esp_dev->sync_min_period = 0;
                        esp_dev->sync_max_offset = 0;
                        return 0;
                } else {
                        ESPMISC(("not sync nego, sending ABORT\n"));
                        return ABORT;
                }
        };
}

/* Target negotiates for synchronous transfers before we do, this
 * is legal although very strange.  What is even funnier is that
 * the SCSI2 standard specifically recommends against targets doing
 * this because so many initiators cannot cope with this occurring.
 */
static int target_with_ants_in_pants(struct NCR_ESP *esp,
                                     Scsi_Cmnd *SCptr,
                                     struct esp_device *esp_dev)
{
        if(esp_dev->sync || SCptr->device->borken) {
                /* sorry, no can do */
                ESPSDTR(("forcing to async, "));
                build_sync_nego_msg(esp, 0, 0);
                esp_dev->sync = 1;
                esp->snip = 1;
                ESPLOG(("esp%d: hoping for msgout\n", esp->esp_id));
                esp_advance_phase(SCptr, in_the_dark);
                return EXTENDED_MESSAGE;
        }

        /* Ok, we'll check them out... */
        return 0;
}

static void sync_report(struct NCR_ESP *esp)
{
        int msg3, msg4;
        char *type;

        msg3 = esp->cur_msgin[3];
        msg4 = esp->cur_msgin[4];
        if(msg4) {
                int hz = 1000000000 / (msg3 * 4);
                int integer = hz / 1000000;
                int fraction = (hz - (integer * 1000000)) / 10000;
                if((msg3 * 4) < 200) {
                        type = "FAST";
                } else {
                        type = "synchronous";
                }

                /* Do not transform this back into one big printk
                 * again, it triggers a bug in our sparc64-gcc272
                 * sibling call optimization.  -DaveM
                 */
                ESPLOG((KERN_INFO "esp%d: target %d ",
                        esp->esp_id, esp->current_SC->device->id));
                ESPLOG(("[period %dns offset %d %d.%02dMHz ",
                        (int) msg3 * 4, (int) msg4,
                        integer, fraction));
                ESPLOG(("%s SCSI%s]\n", type,
                        (((msg3 * 4) < 200) ? "-II" : "")));
        } else {
                ESPLOG((KERN_INFO "esp%d: target %d asynchronous\n",
                        esp->esp_id, esp->current_SC->device->id));
        }
}

static int check_multibyte_msg(struct NCR_ESP *esp,
                               struct ESP_regs *eregs)
{
        Scsi_Cmnd *SCptr = esp->current_SC;
        struct esp_device *esp_dev = SCptr->device->hostdata;
        unchar regval = 0;
        int message_out = 0;

        ESPSDTR(("chk multibyte msg: "));
        if(esp->cur_msgin[2] == EXTENDED_SDTR) {
                int period = esp->cur_msgin[3];
                int offset = esp->cur_msgin[4];

                ESPSDTR(("is sync nego response, "));
                if(!esp->snip) {
                        int rval;

                        /* Target negotiates first! */
                        ESPSDTR(("target jumps the gun, "));
                        message_out = EXTENDED_MESSAGE; /* we must respond */
                        rval = target_with_ants_in_pants(esp, SCptr, esp_dev);
                        if(rval)
                                return rval;
                }

                ESPSDTR(("examining sdtr, "));

                /* Offset cannot be larger than ESP fifo size. */
                if(offset > 15) {
                        ESPSDTR(("offset too big %2x, ", offset));
                        offset = 15;
                        ESPSDTR(("sending back new offset\n"));
                        build_sync_nego_msg(esp, period, offset);
                        return EXTENDED_MESSAGE;
                }

                if(offset && period > esp->max_period) {
                        /* Yeee, async for this slow device. */
                        ESPSDTR(("period too long %2x, ", period));
                        build_sync_nego_msg(esp, 0, 0);
                        ESPSDTR(("hoping for msgout\n"));
                        esp_advance_phase(esp->current_SC, in_the_dark);
                        return EXTENDED_MESSAGE;
                } else if (offset && period < esp->min_period) {
                        ESPSDTR(("period too short %2x, ", period));
                        period = esp->min_period;
                        if(esp->erev > esp236)
                                regval = 4;
                        else
                                regval = 5;
                } else if(offset) {
                        int tmp;

                        ESPSDTR(("period is ok, "));
                        tmp = esp->ccycle / 1000;
                        regval = (((period << 2) + tmp - 1) / tmp);
                        if(regval && (esp->erev > esp236)) {
                                if(period >= 50)
                                        regval--;
                        }
                }

                if(offset) {
                        unchar bit;

                        esp_dev->sync_min_period = (regval & 0x1f);
                        esp_dev->sync_max_offset = (offset | esp->radelay);
                        if(esp->erev > esp236) {
                                if(esp->erev == fas100a)
                                        bit = ESP_CONFIG3_FAST;
                                else
                                        bit = ESP_CONFIG3_FSCSI;
                                if(period < 50)
                                        esp->config3[SCptr->device->id] |= bit;
                                else
                                        esp->config3[SCptr->device->id] &= ~bit;
                                esp->prev_cfg3 = esp->config3[SCptr->device->id];
                                esp_write(eregs->esp_cfg3, esp->prev_cfg3);
                        }
                        esp->prev_soff = esp_dev->sync_min_period;
                        esp_write(eregs->esp_soff, esp->prev_soff);
                        esp->prev_stp = esp_dev->sync_max_offset;
                        esp_write(eregs->esp_stp, esp->prev_stp);

                        ESPSDTR(("soff=%2x stp=%2x cfg3=%2x\n",
                                esp_dev->sync_max_offset,
                                esp_dev->sync_min_period,
                                esp->config3[scmd_id(SCptr)]));

                        esp->snip = 0;
                } else if(esp_dev->sync_max_offset) {
                        unchar bit;

                        /* back to async mode */
                        ESPSDTR(("unaccaptable sync nego, forcing async\n"));
                        esp_dev->sync_max_offset = 0;
                        esp_dev->sync_min_period = 0;
                        esp->prev_soff = 0;
                        esp_write(eregs->esp_soff, 0);
                        esp->prev_stp = 0;
                        esp_write(eregs->esp_stp, 0);
                        if(esp->erev > esp236) {
                                if(esp->erev == fas100a)
                                        bit = ESP_CONFIG3_FAST;
                                else
                                        bit = ESP_CONFIG3_FSCSI;
                                esp->config3[SCptr->device->id] &= ~bit;
                                esp->prev_cfg3 = esp->config3[SCptr->device->id];
                                esp_write(eregs->esp_cfg3, esp->prev_cfg3);
                        }
                }

                sync_report(esp);

                ESPSDTR(("chk multibyte msg: sync is known, "));
                esp_dev->sync = 1;

                if(message_out) {
                        ESPLOG(("esp%d: sending sdtr back, hoping for msgout\n",
                                esp->esp_id));
                        build_sync_nego_msg(esp, period, offset);
                        esp_advance_phase(SCptr, in_the_dark);
                        return EXTENDED_MESSAGE;
                }

                ESPSDTR(("returning zero\n"));
                esp_advance_phase(SCptr, in_the_dark); /* ...or else! */
                return 0;
        } else if(esp->cur_msgin[2] == EXTENDED_WDTR) {
                ESPLOG(("esp%d: AIEEE wide msg received\n", esp->esp_id));
                message_out = MESSAGE_REJECT;
        } else if(esp->cur_msgin[2] == EXTENDED_MODIFY_DATA_POINTER) {
                ESPLOG(("esp%d: rejecting modify data ptr msg\n", esp->esp_id));
                message_out = MESSAGE_REJECT;
        }
        esp_advance_phase(SCptr, in_the_dark);
        return message_out;
}

static int esp_do_msgindone(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        Scsi_Cmnd *SCptr = esp->current_SC;
        int message_out = 0, it = 0, rval;

        rval = skipahead1(esp, eregs, SCptr, in_msgin, in_msgindone);
        if(rval)
                return rval;
        if(SCptr->SCp.sent_command != in_status) {
                if(!(esp->ireg & ESP_INTR_DC)) {
                        if(esp->msgin_len && (esp->sreg & ESP_STAT_PERR)) {
                                message_out = MSG_PARITY_ERROR;
                                esp_cmd(esp, eregs, ESP_CMD_FLUSH);
                        } else if((it = (esp_read(eregs->esp_fflags) & ESP_FF_FBYTES))!=1) {
                                /* We certainly dropped the ball somewhere. */
                                message_out = INITIATOR_ERROR;
                                esp_cmd(esp, eregs, ESP_CMD_FLUSH);
                        } else if(!esp->msgin_len) {
                                it = esp_read(eregs->esp_fdata);
                                esp_advance_phase(SCptr, in_msgincont);
                        } else {
                                /* it is ok and we want it */
                                it = esp->cur_msgin[esp->msgin_ctr] =
                                        esp_read(eregs->esp_fdata);
                                esp->msgin_ctr++;
                        }
                } else {
                        esp_advance_phase(SCptr, in_the_dark);
                        return do_work_bus;
                }
        } else {
                it = esp->cur_msgin[0];
        }
        if(!message_out && esp->msgin_len) {
                if(esp->msgin_ctr < esp->msgin_len) {
                        esp_advance_phase(SCptr, in_msgincont);
                } else if(esp->msgin_len == 1) {
                        message_out = check_singlebyte_msg(esp, eregs);
                } else if(esp->msgin_len == 2) {
                        if(esp->cur_msgin[0] == EXTENDED_MESSAGE) {
                                if((it+2) >= 15) {
                                        message_out = MESSAGE_REJECT;
                                } else {
                                        esp->msgin_len = (it + 2);
                                        esp_advance_phase(SCptr, in_msgincont);
                                }
                        } else {
                                message_out = MESSAGE_REJECT; /* foo on you */
                        }
                } else {
                        message_out = check_multibyte_msg(esp, eregs);
                }
        }
        if(message_out < 0) {
                return -message_out;
        } else if(message_out) {
                if(((message_out != 1) &&
                    ((message_out < 0x20) || (message_out & 0x80))))
                        esp->msgout_len = 1;
                esp->cur_msgout[0] = message_out;
                esp_cmd(esp, eregs, ESP_CMD_SATN);
                esp_advance_phase(SCptr, in_the_dark);
                esp->msgin_len = 0;
        }
        esp->sreg = esp_read(eregs->esp_status);
        esp->sreg &= ~(ESP_STAT_INTR);
        if((esp->sreg & (ESP_STAT_PMSG|ESP_STAT_PCD)) == (ESP_STAT_PMSG|ESP_STAT_PCD))
                esp_cmd(esp, eregs, ESP_CMD_MOK);
        if((SCptr->SCp.sent_command == in_msgindone) &&
            (SCptr->SCp.phase == in_freeing))
                return esp_do_freebus(esp, eregs);
        return do_intr_end;
}

static int esp_do_cmdbegin(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        unsigned char tmp;
        Scsi_Cmnd *SCptr = esp->current_SC;

        esp_advance_phase(SCptr, in_cmdend);
        esp_cmd(esp, eregs, ESP_CMD_FLUSH);
        tmp = *esp->esp_scmdp++;
        esp->esp_scmdleft--;
        esp_write(eregs->esp_fdata, tmp);
        esp_cmd(esp, eregs, ESP_CMD_TI);
        return do_intr_end;
}

static int esp_do_cmddone(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        esp_cmd(esp, eregs, ESP_CMD_NULL);
        if(esp->ireg & ESP_INTR_BSERV) {
                esp_advance_phase(esp->current_SC, in_the_dark);
                return esp_do_phase_determine(esp, eregs);
        }
        ESPLOG(("esp%d: in do_cmddone() but didn't get BSERV interrupt.\n",
                esp->esp_id));
        return do_reset_bus;
}

static int esp_do_msgout(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        esp_cmd(esp, eregs, ESP_CMD_FLUSH);
        switch(esp->msgout_len) {
        case 1:
                esp_write(eregs->esp_fdata, esp->cur_msgout[0]);
                esp_cmd(esp, eregs, ESP_CMD_TI);
                break;

        case 2:
                if(esp->do_pio_cmds){
                        esp_write(eregs->esp_fdata, esp->cur_msgout[0]);
                        esp_write(eregs->esp_fdata, esp->cur_msgout[1]);
                        esp_cmd(esp, eregs, ESP_CMD_TI);
                } else {
                        esp->esp_command[0] = esp->cur_msgout[0];
                        esp->esp_command[1] = esp->cur_msgout[1];
                        esp->dma_setup(esp, esp->esp_command_dvma, 2, 0);
                        esp_setcount(eregs, 2);
                        esp_cmd(esp, eregs, ESP_CMD_DMA | ESP_CMD_TI);
                }
                break;

        case 4:
                esp->snip = 1;
                if(esp->do_pio_cmds){
                        esp_write(eregs->esp_fdata, esp->cur_msgout[0]);
                        esp_write(eregs->esp_fdata, esp->cur_msgout[1]);
                        esp_write(eregs->esp_fdata, esp->cur_msgout[2]);
                        esp_write(eregs->esp_fdata, esp->cur_msgout[3]);
                        esp_cmd(esp, eregs, ESP_CMD_TI);
                } else {
                        esp->esp_command[0] = esp->cur_msgout[0];
                        esp->esp_command[1] = esp->cur_msgout[1];
                        esp->esp_command[2] = esp->cur_msgout[2];
                        esp->esp_command[3] = esp->cur_msgout[3];
                        esp->dma_setup(esp, esp->esp_command_dvma, 4, 0);
                        esp_setcount(eregs, 4);
                        esp_cmd(esp, eregs, ESP_CMD_DMA | ESP_CMD_TI);
                }
                break;

        case 5:
                esp->snip = 1;
                if(esp->do_pio_cmds){
                        esp_write(eregs->esp_fdata, esp->cur_msgout[0]);
                        esp_write(eregs->esp_fdata, esp->cur_msgout[1]);
                        esp_write(eregs->esp_fdata, esp->cur_msgout[2]);
                        esp_write(eregs->esp_fdata, esp->cur_msgout[3]);
                        esp_write(eregs->esp_fdata, esp->cur_msgout[4]);
                        esp_cmd(esp, eregs, ESP_CMD_TI);
                } else {
                        esp->esp_command[0] = esp->cur_msgout[0];
                        esp->esp_command[1] = esp->cur_msgout[1];
                        esp->esp_command[2] = esp->cur_msgout[2];
                        esp->esp_command[3] = esp->cur_msgout[3];
                        esp->esp_command[4] = esp->cur_msgout[4];
                        esp->dma_setup(esp, esp->esp_command_dvma, 5, 0);
                        esp_setcount(eregs, 5);
                        esp_cmd(esp, eregs, ESP_CMD_DMA | ESP_CMD_TI);
                }
                break;

        default:
                /* whoops */
                ESPMISC(("bogus msgout sending NOP\n"));
                esp->cur_msgout[0] = NOP;
                esp_write(eregs->esp_fdata, esp->cur_msgout[0]);
                esp->msgout_len = 1;
                esp_cmd(esp, eregs, ESP_CMD_TI);
                break;
        }
        esp_advance_phase(esp->current_SC, in_msgoutdone);
        return do_intr_end;
}

static int esp_do_msgoutdone(struct NCR_ESP *esp, 
                             struct ESP_regs *eregs)
{
        if((esp->msgout_len > 1) && esp->dma_barrier)
                esp->dma_barrier(esp);

        if(!(esp->ireg & ESP_INTR_DC)) {
                esp_cmd(esp, eregs, ESP_CMD_NULL);
                switch(esp->sreg & ESP_STAT_PMASK) {
                case ESP_MOP:
                        /* whoops, parity error */
                        ESPLOG(("esp%d: still in msgout, parity error assumed\n",
                                esp->esp_id));
                        if(esp->msgout_len > 1)
                                esp_cmd(esp, eregs, ESP_CMD_SATN);
                        esp_advance_phase(esp->current_SC, in_msgout);
                        return do_work_bus;

                case ESP_DIP:
                        break;

                default:
                        if(!fcount(esp, eregs) &&
                           !(((struct esp_device *)esp->current_SC->device->hostdata)->sync_max_offset))
                                esp_cmd(esp, eregs, ESP_CMD_FLUSH);
                        break;

                };
        }

        /* If we sent out a synchronous negotiation message, update
         * our state.
         */
        if(esp->cur_msgout[2] == EXTENDED_MESSAGE &&
           esp->cur_msgout[4] == EXTENDED_SDTR) {
                esp->snip = 1; /* anal retentiveness... */
        }

        esp->prevmsgout = esp->cur_msgout[0];
        esp->msgout_len = 0;
        esp_advance_phase(esp->current_SC, in_the_dark);
        return esp_do_phase_determine(esp, eregs);
}

static int esp_bus_unexpected(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        ESPLOG(("esp%d: command in weird state %2x\n",
                esp->esp_id, esp->current_SC->SCp.phase));
        return do_reset_bus;
}

static espfunc_t bus_vector[] = {
        esp_do_data_finale,
        esp_do_data_finale,
        esp_bus_unexpected,
        esp_do_msgin,
        esp_do_msgincont,
        esp_do_msgindone,
        esp_do_msgout,
        esp_do_msgoutdone,
        esp_do_cmdbegin,
        esp_do_cmddone,
        esp_do_status,
        esp_do_freebus,
        esp_do_phase_determine,
        esp_bus_unexpected,
        esp_bus_unexpected,
        esp_bus_unexpected,
};

/* This is the second tier in our dual-level SCSI state machine. */
static int esp_work_bus(struct NCR_ESP *esp, struct ESP_regs *eregs)
{
        Scsi_Cmnd *SCptr = esp->current_SC;
        unsigned int phase;

        ESPBUS(("esp_work_bus: "));
        if(!SCptr) {
                ESPBUS(("reconnect\n"));
                return esp_do_reconnect(esp, eregs);
        }
        phase = SCptr->SCp.phase;
        if ((phase & 0xf0) == in_phases_mask)
                return bus_vector[(phase & 0x0f)](esp, eregs);
        else if((phase & 0xf0) == in_slct_mask)
                return esp_select_complete(esp, eregs);
        else
                return esp_bus_unexpected(esp, eregs);
}

static espfunc_t isvc_vector[] = {
        NULL,
        esp_do_phase_determine,
        esp_do_resetbus,
        esp_finish_reset,
        esp_work_bus
};

/* Main interrupt handler for an esp adapter. */
void esp_handle(struct NCR_ESP *esp)
{
        struct ESP_regs *eregs;
        Scsi_Cmnd *SCptr;
        int what_next = do_intr_end;
        eregs = esp->eregs;
        SCptr = esp->current_SC;

        if(esp->dma_irq_entry)
                esp->dma_irq_entry(esp);

        /* Check for errors. */
        esp->sreg = esp_read(eregs->esp_status);
        esp->sreg &= (~ESP_STAT_INTR);
        esp->seqreg = (esp_read(eregs->esp_sstep) & ESP_STEP_VBITS);
        esp->ireg = esp_read(eregs->esp_intrpt);   /* Unlatch intr and stat regs */
        ESPIRQ(("handle_irq: [sreg<%02x> sstep<%02x> ireg<%02x>]\n",
                esp->sreg, esp->seqreg, esp->ireg));
        if(esp->sreg & (ESP_STAT_SPAM)) {
                /* Gross error, could be due to one of:
                 *
                 * - top of fifo overwritten, could be because
                 *   we tried to do a synchronous transfer with
                 *   an offset greater than ESP fifo size
                 *
                 * - top of command register overwritten
                 *
                 * - DMA setup to go in one direction, SCSI
                 *   bus points in the other, whoops
                 *
                 * - weird phase change during asynchronous
                 *   data phase while we are initiator
                 */
                ESPLOG(("esp%d: Gross error sreg=%2x\n", esp->esp_id, esp->sreg));

                /* If a command is live on the bus we cannot safely
                 * reset the bus, so we'll just let the pieces fall
                 * where they may.  Here we are hoping that the
                 * target will be able to cleanly go away soon
                 * so we can safely reset things.
                 */
                if(!SCptr) {
                        ESPLOG(("esp%d: No current cmd during gross error, "
                                "resetting bus\n", esp->esp_id));
                        what_next = do_reset_bus;
                        goto state_machine;
                }
        }

        /* No current cmd is only valid at this point when there are
         * commands off the bus or we are trying a reset.
         */
        if(!SCptr && !esp->disconnected_SC && !(esp->ireg & ESP_INTR_SR)) {
                /* Panic is safe, since current_SC is null. */
                ESPLOG(("esp%d: no command in esp_handle()\n", esp->esp_id));
                panic("esp_handle: current_SC == penguin within interrupt!");
        }

        if(esp->ireg & (ESP_INTR_IC)) {
                /* Illegal command fed to ESP.  Outside of obvious
                 * software bugs that could cause this, there is
                 * a condition with ESP100 where we can confuse the
                 * ESP into an erroneous illegal command interrupt
                 * because it does not scrape the FIFO properly
                 * for reselection.  See esp100_reconnect_hwbug()
                 * to see how we try very hard to avoid this.
                 */
                ESPLOG(("esp%d: invalid command\n", esp->esp_id));

                esp_dump_state(esp, eregs);

                if(SCptr) {
                        /* Devices with very buggy firmware can drop BSY
                         * during a scatter list interrupt when using sync
                         * mode transfers.  We continue the transfer as
                         * expected, the target drops the bus, the ESP
                         * gets confused, and we get a illegal command
                         * interrupt because the bus is in the disconnected
                         * state now and ESP_CMD_TI is only allowed when
                         * a nexus is alive on the bus.
                         */
                        ESPLOG(("esp%d: Forcing async and disabling disconnect for "
                                "target %d\n", esp->esp_id, SCptr->device->id));
                        SCptr->device->borken = 1; /* foo on you */
                }

                what_next = do_reset_bus;
        } else if(!(esp->ireg & ~(ESP_INTR_FDONE | ESP_INTR_BSERV | ESP_INTR_DC))) {
                int phase;

                if(SCptr) {
                        phase = SCptr->SCp.phase;
                        if(phase & in_phases_mask) {
                                what_next = esp_work_bus(esp, eregs);
                        } else if(phase & in_slct_mask) {
                                what_next = esp_select_complete(esp, eregs);
                        } else {
                                ESPLOG(("esp%d: interrupt for no good reason...\n",
                                        esp->esp_id));
                                what_next = do_intr_end;
                        }
                } else {
                        ESPLOG(("esp%d: BSERV or FDONE or DC while SCptr==NULL\n",
                                esp->esp_id));
                        what_next = do_reset_bus;
                }
        } else if(esp->ireg & ESP_INTR_SR) {
                ESPLOG(("esp%d: SCSI bus reset interrupt\n", esp->esp_id));
                what_next = do_reset_complete;
        } else if(esp->ireg & (ESP_INTR_S | ESP_INTR_SATN)) {
                ESPLOG(("esp%d: AIEEE we have been selected by another initiator!\n",
                        esp->esp_id));
                what_next = do_reset_bus;
        } else if(esp->ireg & ESP_INTR_RSEL) {
                if(!SCptr) {
                        /* This is ok. */
                        what_next = esp_do_reconnect(esp, eregs);
                } else if(SCptr->SCp.phase & in_slct_mask) {
                        /* Only selection code knows how to clean
                         * up properly.
                         */
                        ESPDISC(("Reselected during selection attempt\n"));
                        what_next = esp_select_complete(esp, eregs);
                } else {
                        ESPLOG(("esp%d: Reselected while bus is busy\n",
                                esp->esp_id));
                        what_next = do_reset_bus;
                }
        }

        /* This is tier-one in our dual level SCSI state machine. */
state_machine:
        while(what_next != do_intr_end) {
                if (what_next >= do_phase_determine &&
                    what_next < do_intr_end)
                        what_next = isvc_vector[what_next](esp, eregs);
                else {
                        /* state is completely lost ;-( */
                        ESPLOG(("esp%d: interrupt engine loses state, resetting bus\n",
                                esp->esp_id));
                        what_next = do_reset_bus;
                }
        }
        if(esp->dma_irq_exit)
                esp->dma_irq_exit(esp);
}

#ifndef CONFIG_SMP
irqreturn_t esp_intr(int irq, void *dev_id)
{
        struct NCR_ESP *esp;
        unsigned long flags;
        int again;
        struct Scsi_Host *dev = dev_id;

        /* Handle all ESP interrupts showing at this IRQ level. */
        spin_lock_irqsave(dev->host_lock, flags);
repeat:
        again = 0;
        for_each_esp(esp) {
#ifndef __mips__            
                if(((esp)->irq & 0xff) == irq) {
#endif              
                        if(esp->dma_irq_p(esp)) {
                                again = 1;

                                esp->dma_ints_off(esp);

                                ESPIRQ(("I%d(", esp->esp_id));
                                esp_handle(esp);
                                ESPIRQ((")"));

                                esp->dma_ints_on(esp);
                        }
#ifndef __mips__                    
                }
#endif      
        }
        if(again)
                goto repeat;
        spin_unlock_irqrestore(dev->host_lock, flags);
        return IRQ_HANDLED;
}
#else
/* For SMP we only service one ESP on the list list at our IRQ level! */
irqreturn_t esp_intr(int irq, void *dev_id)
{
        struct NCR_ESP *esp;
        unsigned long flags;
        struct Scsi_Host *dev = dev_id;
        
        /* Handle all ESP interrupts showing at this IRQ level. */
        spin_lock_irqsave(dev->host_lock, flags);
        for_each_esp(esp) {
                if(((esp)->irq & 0xf) == irq) {
                        if(esp->dma_irq_p(esp)) {
                                esp->dma_ints_off(esp);

                                ESPIRQ(("I[%d:%d](",
                                        smp_processor_id(), esp->esp_id));
                                esp_handle(esp);
                                ESPIRQ((")"));

                                esp->dma_ints_on(esp);
                                goto out;
                        }
                }
        }
out:
        spin_unlock_irqrestore(dev->host_lock, flags);
        return IRQ_HANDLED;
}
#endif

int esp_slave_alloc(struct scsi_device *SDptr)
{
        struct esp_device *esp_dev =
                kmalloc(sizeof(struct esp_device), GFP_ATOMIC);

        if (!esp_dev)
                return -ENOMEM;
        memset(esp_dev, 0, sizeof(struct esp_device));
        SDptr->hostdata = esp_dev;
        return 0;
}

void esp_slave_destroy(struct scsi_device *SDptr)
{
        struct NCR_ESP *esp = (struct NCR_ESP *) SDptr->host->hostdata;

        esp->targets_present &= ~(1 << sdev_id(SDptr));
        kfree(SDptr->hostdata);
        SDptr->hostdata = NULL;
}

#ifdef MODULE
int init_module(void) { return 0; }
void cleanup_module(void) {}
void esp_release(void)
{
        esps_in_use--;
        esps_running = esps_in_use;
}
#endif

EXPORT_SYMBOL(esp_abort);
EXPORT_SYMBOL(esp_allocate);
EXPORT_SYMBOL(esp_deallocate);
EXPORT_SYMBOL(esp_initialize);
EXPORT_SYMBOL(esp_intr);
EXPORT_SYMBOL(esp_queue);
EXPORT_SYMBOL(esp_reset);
EXPORT_SYMBOL(esp_slave_alloc);
EXPORT_SYMBOL(esp_slave_destroy);
EXPORT_SYMBOL(esps_in_use);

MODULE_LICENSE("GPL");