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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, struct pt_regs *pregs);

/* 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)
{
      struct NCR_ESP *esp, *elink;
      struct Scsi_Host *esp_host;

      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 pt_regs *pregs)
{
      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 pt_regs *pregs)
{
      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");

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