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esp.c

/* esp.c: ESP Sun SCSI driver.
 *
 * Copyright (C) 1995, 1998, 2006 David S. Miller (davem@davemloft.net)
 */

/* 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.
 */

#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/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/module.h>

#include "esp.h"

#include <asm/sbus.h>
#include <asm/dma.h>
#include <asm/system.h>
#include <asm/ptrace.h>
#include <asm/pgtable.h>
#include <asm/oplib.h>
#include <asm/io.h>
#include <asm/irq.h>
#ifndef __sparc_v9__
#include <asm/machines.h>
#include <asm/idprom.h>
#endif

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>

#define DRV_VERSION "1.101"

#define DEBUG_ESP
/* #define DEBUG_ESP_HME */
/* #define DEBUG_ESP_DATA */
/* #define DEBUG_ESP_QUEUE */
/* #define DEBUG_ESP_DISCONNECT */
/* #define DEBUG_ESP_STATUS */
/* #define DEBUG_ESP_PHASES */
/* #define DEBUG_ESP_WORKBUS */
/* #define DEBUG_STATE_MACHINE */
/* #define DEBUG_ESP_CMDS */
/* #define DEBUG_ESP_IRQS */
/* #define DEBUG_SDTR */
/* #define DEBUG_ESP_SG */

/* Use the following to sprinkle debugging messages in a way which
 * suits you if combinations of the above become too verbose when
 * trying to track down a specific problem.
 */
/* #define DEBUG_ESP_MISC */

#if defined(DEBUG_ESP)
#define ESPLOG(foo)  printk foo
#else
#define ESPLOG(foo)
#endif /* (DEBUG_ESP) */

#if defined(DEBUG_ESP_HME)
#define ESPHME(foo)  printk foo
#else
#define ESPHME(foo)
#endif

#if defined(DEBUG_ESP_DATA)
#define ESPDATA(foo)  printk foo
#else
#define ESPDATA(foo)
#endif

#if defined(DEBUG_ESP_QUEUE)
#define ESPQUEUE(foo)  printk foo
#else
#define ESPQUEUE(foo)
#endif

#if defined(DEBUG_ESP_DISCONNECT)
#define ESPDISC(foo)  printk foo
#else
#define ESPDISC(foo)
#endif

#if defined(DEBUG_ESP_STATUS)
#define ESPSTAT(foo)  printk foo
#else
#define ESPSTAT(foo)
#endif

#if defined(DEBUG_ESP_PHASES)
#define ESPPHASE(foo)  printk foo
#else
#define ESPPHASE(foo)
#endif

#if defined(DEBUG_ESP_WORKBUS)
#define ESPBUS(foo)  printk foo
#else
#define ESPBUS(foo)
#endif

#if defined(DEBUG_ESP_IRQS)
#define ESPIRQ(foo)  printk foo
#else
#define ESPIRQ(foo)
#endif

#if defined(DEBUG_SDTR)
#define ESPSDTR(foo)  printk foo
#else
#define ESPSDTR(foo)
#endif

#if defined(DEBUG_ESP_MISC)
#define ESPMISC(foo)  printk foo
#else
#define ESPMISC(foo)
#endif

/* 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
};

/* Forward declarations. */
static irqreturn_t esp_intr(int irq, void *dev_id, struct pt_regs *pregs);

/* Debugging routines */
struct esp_cmdstrings {
      u8 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(u8 espcmd)
{
      u8 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(u8 statreg)
{
      u8 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(u8 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(u8 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(struct 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 esp *esp, u8 cmd)
{
      esp->espcmdlog[esp->espcmdent] = cmd;
      esp->espcmdent = (esp->espcmdent + 1) & 31;
      sbus_writeb(cmd, esp->eregs + ESP_CMD);
}
#else
#define esp_cmd(__esp, __cmd) \
      sbus_writeb((__cmd), ((__esp)->eregs) + ESP_CMD)
#endif

#define ESP_INTSOFF(__dregs)  \
      sbus_writel(sbus_readl((__dregs)+DMA_CSR)&~(DMA_INT_ENAB), (__dregs)+DMA_CSR)
#define ESP_INTSON(__dregs)   \
      sbus_writel(sbus_readl((__dregs)+DMA_CSR)|DMA_INT_ENAB, (__dregs)+DMA_CSR)
#define ESP_IRQ_P(__dregs)    \
      (sbus_readl((__dregs)+DMA_CSR) & (DMA_HNDL_INTR|DMA_HNDL_ERROR))

/* How we use the various Linux SCSI data structures for operation.
 *
 * struct scsi_cmnd:
 *
 *   We keep track of the synchronous 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(struct scsi_cmnd **SC, struct scsi_cmnd *new_SC)
{
      struct scsi_cmnd *end;

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

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

static inline struct scsi_cmnd *remove_first_SC(struct scsi_cmnd **SC)
{
      struct scsi_cmnd *ptr;
      ptr = *SC;
      if (ptr)
            *SC = (struct scsi_cmnd *) (*SC)->host_scribble;
      return ptr;
}

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

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

/* Resetting various pieces of the ESP scsi driver chipset/buses. */
static void esp_reset_dma(struct esp *esp)
{
      int can_do_burst16, can_do_burst32, can_do_burst64;
      int can_do_sbus64;
      u32 tmp;

      can_do_burst16 = (esp->bursts & DMA_BURST16) != 0;
      can_do_burst32 = (esp->bursts & DMA_BURST32) != 0;
      can_do_burst64 = 0;
      can_do_sbus64 = 0;
      if (sbus_can_dma_64bit(esp->sdev))
            can_do_sbus64 = 1;
      if (sbus_can_burst64(esp->sdev))
            can_do_burst64 = (esp->bursts & DMA_BURST64) != 0;

      /* Punt the DVMA into a known state. */
      if (esp->dma->revision != dvmahme) {
            tmp = sbus_readl(esp->dregs + DMA_CSR);
            sbus_writel(tmp | DMA_RST_SCSI, esp->dregs + DMA_CSR);
            sbus_writel(tmp & ~DMA_RST_SCSI, esp->dregs + DMA_CSR);
      }
      switch (esp->dma->revision) {
      case dvmahme:
            /* This is the HME DVMA gate array. */

            sbus_writel(DMA_RESET_FAS366, esp->dregs + DMA_CSR);
            sbus_writel(DMA_RST_SCSI, esp->dregs + DMA_CSR);

            esp->prev_hme_dmacsr = (DMA_PARITY_OFF|DMA_2CLKS|DMA_SCSI_DISAB|DMA_INT_ENAB);
            esp->prev_hme_dmacsr &= ~(DMA_ENABLE|DMA_ST_WRITE|DMA_BRST_SZ);

            if (can_do_burst64)
                  esp->prev_hme_dmacsr |= DMA_BRST64;
            else if (can_do_burst32)
                  esp->prev_hme_dmacsr |= DMA_BRST32;

            if (can_do_sbus64) {
                  esp->prev_hme_dmacsr |= DMA_SCSI_SBUS64;
                  sbus_set_sbus64(esp->sdev, esp->bursts);
            }

            /* This chip is horrible. */
            while (sbus_readl(esp->dregs + DMA_CSR) & DMA_PEND_READ)
                  udelay(1);

            sbus_writel(0, esp->dregs + DMA_CSR);
            sbus_writel(esp->prev_hme_dmacsr, esp->dregs + DMA_CSR);

            /* This is necessary to avoid having the SCSI channel
             * engine lock up on us.
             */
            sbus_writel(0, esp->dregs + DMA_ADDR);

            break;
      case dvmarev2:
            /* This is the gate array found in the sun4m
             * NCR SBUS I/O subsystem.
             */
            if (esp->erev != esp100) {
                  tmp = sbus_readl(esp->dregs + DMA_CSR);
                  sbus_writel(tmp | DMA_3CLKS, esp->dregs + DMA_CSR);
            }
            break;
      case dvmarev3:
            tmp = sbus_readl(esp->dregs + DMA_CSR);
            tmp &= ~DMA_3CLKS;
            tmp |= DMA_2CLKS;
            if (can_do_burst32) {
                  tmp &= ~DMA_BRST_SZ;
                  tmp |= DMA_BRST32;
            }
            sbus_writel(tmp, esp->dregs + DMA_CSR);
            break;
      case dvmaesc1:
            /* This is the DMA unit found on SCSI/Ether cards. */
            tmp = sbus_readl(esp->dregs + DMA_CSR);
            tmp |= DMA_ADD_ENABLE;
            tmp &= ~DMA_BCNT_ENAB;
            if (!can_do_burst32 && can_do_burst16) {
                  tmp |= DMA_ESC_BURST;
            } else {
                  tmp &= ~(DMA_ESC_BURST);
            }
            sbus_writel(tmp, esp->dregs + DMA_CSR);
            break;
      default:
            break;
      };
      ESP_INTSON(esp->dregs);
}

/* Reset the ESP chip, _not_ the SCSI bus. */
static void __init esp_reset_esp(struct esp *esp)
{
      u8 family_code, version;
      int i;

      /* Now reset the ESP chip */
      esp_cmd(esp, ESP_CMD_RC);
      esp_cmd(esp, ESP_CMD_NULL | ESP_CMD_DMA);
      esp_cmd(esp, ESP_CMD_NULL | ESP_CMD_DMA);

      /* Reload the configuration registers */
      sbus_writeb(esp->cfact, esp->eregs + ESP_CFACT);
      esp->prev_stp = 0;
      sbus_writeb(esp->prev_stp, esp->eregs + ESP_STP);
      esp->prev_soff = 0;
      sbus_writeb(esp->prev_soff, esp->eregs + ESP_SOFF);
      sbus_writeb(esp->neg_defp, esp->eregs + ESP_TIMEO);

      /* This is the only point at which it is reliable to read
       * the ID-code for a fast ESP chip variants.
       */
      esp->max_period = ((35 * esp->ccycle) / 1000);
      if (esp->erev == fast) {
            version = sbus_readb(esp->eregs + ESP_UID);
            family_code = (version & 0xf8) >> 3;
            if (family_code == 0x02)
                  esp->erev = fas236;
            else if (family_code == 0x0a)
                  esp->erev = fashme; /* Version is usually '5'. */
            else
                  esp->erev = fas100a;
            ESPMISC(("esp%d: FAST chip is %s (family=%d, version=%d)\n",
                   esp->esp_id,
                   (esp->erev == fas236) ? "fas236" :
                   ((esp->erev == fas100a) ? "fas100a" :
                    "fasHME"), family_code, (version & 7)));

            esp->min_period = ((4 * esp->ccycle) / 1000);
      } else {
            esp->min_period = ((5 * esp->ccycle) / 1000);
      }
      esp->max_period = (esp->max_period + 3)>>2;
      esp->min_period = (esp->min_period + 3)>>2;

      sbus_writeb(esp->config1, esp->eregs + ESP_CFG1);
      switch (esp->erev) {
      case esp100:
            /* nothing to do */
            break;
      case esp100a:
            sbus_writeb(esp->config2, esp->eregs + ESP_CFG2);
            break;
      case esp236:
            /* Slow 236 */
            sbus_writeb(esp->config2, esp->eregs + ESP_CFG2);
            esp->prev_cfg3 = esp->config3[0];
            sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_CFG3);
            break;
      case fashme:
            esp->config2 |= (ESP_CONFIG2_HME32 | ESP_CONFIG2_HMEFENAB);
            /* fallthrough... */
      case fas236:
            /* Fast 236 or HME */
            sbus_writeb(esp->config2, esp->eregs + ESP_CFG2);
            for (i = 0; i < 16; i++) {
                  if (esp->erev == fashme) {
                        u8 cfg3;

                        cfg3 = ESP_CONFIG3_FCLOCK | ESP_CONFIG3_OBPUSH;
                        if (esp->scsi_id >= 8)
                              cfg3 |= ESP_CONFIG3_IDBIT3;
                        esp->config3[i] |= cfg3;
                  } else {
                        esp->config3[i] |= ESP_CONFIG3_FCLK;
                  }
            }
            esp->prev_cfg3 = esp->config3[0];
            sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_CFG3);
            if (esp->erev == fashme) {
                  esp->radelay = 80;
            } else {
                  if (esp->diff)
                        esp->radelay = 0;
                  else
                        esp->radelay = 96;
            }
            break;
      case fas100a:
            /* Fast 100a */
            sbus_writeb(esp->config2, esp->eregs + ESP_CFG2);
            for (i = 0; i < 16; i++)
                  esp->config3[i] |= ESP_CONFIG3_FCLOCK;
            esp->prev_cfg3 = esp->config3[0];
            sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_CFG3);
            esp->radelay = 32;
            break;
      default:
            panic("esp: what could it be... I wonder...");
            break;
      };

      /* Eat any bitrot in the chip */
      sbus_readb(esp->eregs + ESP_INTRPT);
      udelay(100);
}

/* This places the ESP into a known state at boot time. */
static void __init esp_bootup_reset(struct esp *esp)
{
      u8 tmp;

      /* Reset the DMA */
      esp_reset_dma(esp);

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

      /* Reset the SCSI bus, but tell ESP not to generate an irq */
      tmp = sbus_readb(esp->eregs + ESP_CFG1);
      tmp |= ESP_CONFIG1_SRRDISAB;
      sbus_writeb(tmp, esp->eregs + ESP_CFG1);

      esp_cmd(esp, ESP_CMD_RS);
      udelay(400);

      sbus_writeb(esp->config1, esp->eregs + ESP_CFG1);

      /* Eat any bitrot in the chip and we are done... */
      sbus_readb(esp->eregs + ESP_INTRPT);
}

static int __init esp_find_dvma(struct esp *esp, struct sbus_dev *dma_sdev)
{
      struct sbus_dev *sdev = esp->sdev;
      struct sbus_dma *dma;

      if (dma_sdev != NULL) {
            for_each_dvma(dma) {
                  if (dma->sdev == dma_sdev)
                        break;
            }
      } else {
            for_each_dvma(dma) {
                  /* If allocated already, can't use it. */
                  if (dma->allocated)
                        continue;

                  if (dma->sdev == NULL)
                        break;

                  /* If bus + slot are the same and it has the
                   * correct OBP name, it's ours.
                   */
                  if (sdev->bus == dma->sdev->bus &&
                      sdev->slot == dma->sdev->slot &&
                      (!strcmp(dma->sdev->prom_name, "dma") ||
                       !strcmp(dma->sdev->prom_name, "espdma")))
                        break;
            }
      }

      /* If we don't know how to handle the dvma,
       * do not use this device.
       */
      if (dma == NULL) {
            printk("Cannot find dvma for ESP%d's SCSI\n", esp->esp_id);
            return -1;
      }
      if (dma->allocated) {
            printk("esp%d: can't use my espdma\n", esp->esp_id);
            return -1;
      }
      dma->allocated = 1;
      esp->dma = dma;
      esp->dregs = dma->regs;

      return 0;
}

static int __init esp_map_regs(struct esp *esp, int hme)
{
      struct sbus_dev *sdev = esp->sdev;
      struct resource *res;

      /* On HME, two reg sets exist, first is DVMA,
       * second is ESP registers.
       */
      if (hme)
            res = &sdev->resource[1];
      else
            res = &sdev->resource[0];

      esp->eregs = sbus_ioremap(res, 0, ESP_REG_SIZE, "ESP Registers");

      if (esp->eregs == 0)
            return -1;
      return 0;
}

static int __init esp_map_cmdarea(struct esp *esp)
{
      struct sbus_dev *sdev = esp->sdev;

      esp->esp_command = sbus_alloc_consistent(sdev, 16,
                                     &esp->esp_command_dvma);
      if (esp->esp_command == NULL ||
          esp->esp_command_dvma == 0)
            return -1;
      return 0;
}

static int __init esp_register_irq(struct esp *esp)
{
      esp->ehost->irq = esp->irq = esp->sdev->irqs[0];

      /* We used to try various overly-clever things to
       * reduce the interrupt processing overhead on
       * sun4c/sun4m when multiple ESP's shared the
       * same IRQ.  It was too complex and messy to
       * sanely maintain.
       */
      if (request_irq(esp->ehost->irq, esp_intr,
                  IRQF_SHARED, "ESP SCSI", esp)) {
            printk("esp%d: Cannot acquire irq line\n",
                   esp->esp_id);
            return -1;
      }

      printk("esp%d: IRQ %d ", esp->esp_id,
             esp->ehost->irq);

      return 0;
}

static void __init esp_get_scsi_id(struct esp *esp)
{
      struct sbus_dev *sdev = esp->sdev;
      struct device_node *dp = sdev->ofdev.node;

      esp->scsi_id = of_getintprop_default(dp,
                                   "initiator-id",
                                   -1);
      if (esp->scsi_id == -1)
            esp->scsi_id = of_getintprop_default(dp,
                                         "scsi-initiator-id",
                                         -1);
      if (esp->scsi_id == -1)
            esp->scsi_id = (sdev->bus == NULL) ? 7 :
                  of_getintprop_default(sdev->bus->ofdev.node,
                                    "scsi-initiator-id",
                                    7);
      esp->ehost->this_id = esp->scsi_id;
      esp->scsi_id_mask = (1 << esp->scsi_id);

}

static void __init esp_get_clock_params(struct esp *esp)
{
      struct sbus_dev *sdev = esp->sdev;
      int prom_node = esp->prom_node;
      int sbus_prom_node;
      unsigned int fmhz;
      u8 ccf;

      if (sdev != NULL && sdev->bus != NULL)
            sbus_prom_node = sdev->bus->prom_node;
      else
            sbus_prom_node = 0;

      /* 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 = prom_getintdefault(prom_node, "clock-frequency", -1);
      if (fmhz == -1)
            fmhz = (!sbus_prom_node) ? 0 :
                  prom_getintdefault(sbus_prom_node, "clock-frequency", -1);

      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->raw_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 CCYC=%d CCF=%d TOut %d ",
             esp->scsi_id, (fmhz / 1000000),
             (int)esp->ccycle, (int)ccf, (int) esp->neg_defp);
}

static void __init esp_get_bursts(struct esp *esp, struct sbus_dev *dma)
{
      struct sbus_dev *sdev = esp->sdev;
      u8 bursts;

      bursts = prom_getintdefault(esp->prom_node, "burst-sizes", 0xff);

      if (dma) {
            u8 tmp = prom_getintdefault(dma->prom_node,
                                  "burst-sizes", 0xff);
            if (tmp != 0xff)
                  bursts &= tmp;
      }

      if (sdev->bus) {
            u8 tmp = prom_getintdefault(sdev->bus->prom_node,
                                  "burst-sizes", 0xff);
            if (tmp != 0xff)
                  bursts &= tmp;
      }

      if (bursts == 0xff ||
          (bursts & DMA_BURST16) == 0 ||
          (bursts & DMA_BURST32) == 0)
            bursts = (DMA_BURST32 - 1);

      esp->bursts = bursts;
}

static void __init esp_get_revision(struct esp *esp)
{
      u8 tmp;

      esp->config1 = (ESP_CONFIG1_PENABLE | (esp->scsi_id & 7));
      esp->config2 = (ESP_CONFIG2_SCSI2ENAB | ESP_CONFIG2_REGPARITY);
      sbus_writeb(esp->config2, esp->eregs + ESP_CFG2);

      tmp = sbus_readb(esp->eregs + ESP_CFG2);
      tmp &= ~ESP_CONFIG2_MAGIC;
      if (tmp != (ESP_CONFIG2_SCSI2ENAB | ESP_CONFIG2_REGPARITY)) {
            /* If what we write to cfg2 does not come back, cfg2
             * is not implemented, therefore this must be a plain
             * esp100.
             */
            esp->erev = esp100;
            printk("NCR53C90(esp100)\n");
      } else {
            esp->config2 = 0;
            esp->prev_cfg3 = esp->config3[0] = 5;
            sbus_writeb(esp->config2, esp->eregs + ESP_CFG2);
            sbus_writeb(0, esp->eregs + ESP_CFG3);
            sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_CFG3);

            tmp = sbus_readb(esp->eregs + ESP_CFG3);
            if (tmp != 5) {
                  /* The cfg2 register is implemented, however
                   * cfg3 is not, must be esp100a.
                   */
                  esp->erev = esp100a;
                  printk("NCR53C90A(esp100a)\n");
            } else {
                  int target;

                  for (target = 0; target < 16; target++)
                        esp->config3[target] = 0;
                  esp->prev_cfg3 = 0;
                  sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_CFG3);

                  /* All of cfg{1,2,3} implemented, must be one of
                   * the fas variants, figure out which one.
                   */
                  if (esp->raw_cfact > ESP_CCF_F5) {
                        esp->erev = fast;
                        esp->sync_defp = SYNC_DEFP_FAST;
                        printk("NCR53C9XF(espfast)\n");
                  } else {
                        esp->erev = esp236;
                        printk("NCR53C9x(esp236)\n");
                  }
                  esp->config2 = 0;
                  sbus_writeb(esp->config2, esp->eregs + ESP_CFG2);
            }
      }
}

static void __init esp_init_swstate(struct esp *esp)
{
      int i;

      /* Command queues... */
      esp->current_SC = NULL;
      esp->disconnected_SC = NULL;
      esp->issue_SC = NULL;

      /* Target and current command state... */
      esp->targets_present = 0;
      esp->resetting_bus = 0;
      esp->snip = 0;

      init_waitqueue_head(&esp->reset_queue);

      /* Debugging... */
      for(i = 0; i < 32; i++)
            esp->espcmdlog[i] = 0;
      esp->espcmdent = 0;

      /* MSG phase state... */
      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;
      esp->prev_hme_dmacsr = 0xffffffff;
}

static int __init detect_one_esp(struct scsi_host_template *tpnt,
                         struct device *dev,
                         struct sbus_dev *esp_dev,
                         struct sbus_dev *espdma,
                         struct sbus_bus *sbus,
                         int hme)
{
      static int instance;
      struct Scsi_Host *esp_host = scsi_host_alloc(tpnt, sizeof(struct esp));
      struct esp *esp;
      
      if (!esp_host)
            return -ENOMEM;

      if (hme)
            esp_host->max_id = 16;
      esp = (struct esp *) esp_host->hostdata;
      esp->ehost = esp_host;
      esp->sdev = esp_dev;
      esp->esp_id = instance;
      esp->prom_node = esp_dev->prom_node;
      prom_getstring(esp->prom_node, "name", esp->prom_name,
                   sizeof(esp->prom_name));

      if (esp_find_dvma(esp, espdma) < 0)
            goto fail_unlink;
      if (esp_map_regs(esp, hme) < 0) {
            printk("ESP registers unmappable");
            goto fail_dvma_release;
      }
      if (esp_map_cmdarea(esp) < 0) {
            printk("ESP DVMA transport area unmappable");
            goto fail_unmap_regs;
      }
      if (esp_register_irq(esp) < 0)
            goto fail_unmap_cmdarea;

      esp_get_scsi_id(esp);

      esp->diff = prom_getbool(esp->prom_node, "differential");
      if (esp->diff)
            printk("Differential ");

      esp_get_clock_params(esp);
      esp_get_bursts(esp, espdma);
      esp_get_revision(esp);
      esp_init_swstate(esp);

      esp_bootup_reset(esp);

      if (scsi_add_host(esp_host, dev))
            goto fail_free_irq;

      dev_set_drvdata(&esp_dev->ofdev.dev, esp);

      scsi_scan_host(esp_host);
      instance++;

      return 0;

fail_free_irq:
      free_irq(esp->ehost->irq, esp);

fail_unmap_cmdarea:
      sbus_free_consistent(esp->sdev, 16,
                       (void *) esp->esp_command,
                       esp->esp_command_dvma);

fail_unmap_regs:
      sbus_iounmap(esp->eregs, ESP_REG_SIZE);

fail_dvma_release:
      esp->dma->allocated = 0;

fail_unlink:
      scsi_host_put(esp_host);
      return -1;
}

/* Detecting ESP chips on the machine.  This is the simple and easy
 * version.
 */
static int __devexit esp_remove_common(struct esp *esp)
{
      unsigned int irq = esp->ehost->irq;

      scsi_remove_host(esp->ehost);

      ESP_INTSOFF(esp->dregs);
#if 0
      esp_reset_dma(esp);
      esp_reset_esp(esp);
#endif

      free_irq(irq, esp);
      sbus_free_consistent(esp->sdev, 16,
                       (void *) esp->esp_command, esp->esp_command_dvma);
      sbus_iounmap(esp->eregs, ESP_REG_SIZE);
      esp->dma->allocated = 0;

      scsi_host_put(esp->ehost);

      return 0;
}


#ifdef CONFIG_SUN4

#include <asm/sun4paddr.h>

static struct sbus_dev sun4_esp_dev;

static int __init esp_sun4_probe(struct scsi_host_template *tpnt)
{
      if (sun4_esp_physaddr) {
            memset(&sun4_esp_dev, 0, sizeof(sun4_esp_dev));
            sun4_esp_dev.reg_addrs[0].phys_addr = sun4_esp_physaddr;
            sun4_esp_dev.irqs[0] = 4;
            sun4_esp_dev.resource[0].start = sun4_esp_physaddr;
            sun4_esp_dev.resource[0].end =
                  sun4_esp_physaddr + ESP_REG_SIZE - 1;
            sun4_esp_dev.resource[0].flags = IORESOURCE_IO;

            return detect_one_esp(tpnt, NULL,
                              &sun4_esp_dev, NULL, NULL, 0);
      }
      return 0;
}

static int __devexit esp_sun4_remove(void)
{
      struct of_device *dev = &sun4_esp_dev.ofdev;
      struct esp *esp = dev_get_drvdata(&dev->dev);

      return esp_remove_common(esp);
}

#else /* !CONFIG_SUN4 */

static int __devinit esp_sbus_probe(struct of_device *dev, const struct of_device_id *match)
{
      struct sbus_dev *sdev = to_sbus_device(&dev->dev);
      struct device_node *dp = dev->node;
      struct sbus_dev *dma_sdev = NULL;
      int hme = 0;

      if (dp->parent &&
          (!strcmp(dp->parent->name, "espdma") ||
           !strcmp(dp->parent->name, "dma")))
            dma_sdev = sdev->parent;
      else if (!strcmp(dp->name, "SUNW,fas")) {
            dma_sdev = sdev;
            hme = 1;
      }

      return detect_one_esp(match->data, &dev->dev,
                        sdev, dma_sdev, sdev->bus, hme);
}

static int __devexit esp_sbus_remove(struct of_device *dev)
{
      struct esp *esp = dev_get_drvdata(&dev->dev);

      return esp_remove_common(esp);
}

#endif /* !CONFIG_SUN4 */

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

      esp = (struct esp *) host->hostdata;
      switch (esp->erev) {
      case esp100:
            return "Sparc ESP100 (NCR53C90)";
      case esp100a:
            return "Sparc ESP100A (NCR53C90A)";
      case esp236:
            return "Sparc ESP236";
      case fas236:
            return "Sparc ESP236-FAST";
      case fashme:
            return "Sparc ESP366-HME";
      case fas100a:
            return "Sparc ESP100A-FAST";
      default:
            return "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 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, "Sparc ESP Host Adapter:\n");
      copy_info(&info, "\tPROM node\t\t%08x\n", (unsigned int) esp->prom_node);
      copy_info(&info, "\tPROM name\t\t%s\n", esp->prom_name);
      copy_info(&info, "\tESP Model\t\t");
      switch (esp->erev) {
      case esp100:
            copy_info(&info, "ESP100\n");
            break;
      case esp100a:
            copy_info(&info, "ESP100A\n");
            break;
      case esp236:
            copy_info(&info, "ESP236\n");
            break;
      case fas236:
            copy_info(&info, "FAS236\n");
            break;
      case fas100a:
            copy_info(&info, "FAS100A\n");
            break;
      case fast:
            copy_info(&info, "FAST\n");
            break;
      case fashme:
            copy_info(&info, "Happy Meal FAS\n");
            break;
      case espunknown:
      default:
            copy_info(&info, "Unknown!\n");
            break;
      };
      copy_info(&info, "\tDMA Revision\t\t");
      switch (esp->dma->revision) {
      case dvmarev0:
            copy_info(&info, "Rev 0\n");
            break;
      case dvmaesc1:
            copy_info(&info, "ESC Rev 1\n");
            break;
      case dvmarev1:
            copy_info(&info, "Rev 1\n");
            break;
      case dvmarev2:
            copy_info(&info, "Rev 2\n");
            break;
      case dvmarev3:
            copy_info(&info, "Rev 3\n");
            break;
      case dvmarevplus:
            copy_info(&info, "Rev 1+\n");
            break;
      case dvmahme:
            copy_info(&info, "Rev HME/FAS\n");
            break;
      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\tWide\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\t\t",
                  esp_dev->disconnect ? "yes" : "no");
            copy_info(&info, "%s\n",
                  (esp->config3[id] & ESP_CONFIG3_EWIDE) ? "yes" : "no");
      }
      return info.pos > info.offset? info.pos - info.offset : 0;
}

/* ESP proc filesystem code. */
static int esp_proc_info(struct Scsi_Host *host, char *buffer, char **start, off_t offset,
                   int length, int inout)
{
      struct esp *esp = (struct esp *) host->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 esp *esp, struct 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 (sp->request_bufflen) {
                  sp->SCp.have_data_in = sbus_map_single(esp->sdev, sp->SCp.buffer,
                                                 sp->SCp.this_residual,
                                                 sp->sc_data_direction);
                  sp->SCp.ptr = (char *) ((unsigned long)sp->SCp.have_data_in);
            } else {
                  sp->SCp.ptr = NULL;
            }
      } else {
            sp->SCp.buffer = (struct scatterlist *) sp->request_buffer;
            sp->SCp.buffers_residual = sbus_map_sg(esp->sdev,
                                           sp->SCp.buffer,
                                           sp->use_sg,
                                           sp->sc_data_direction);
            sp->SCp.this_residual = sg_dma_len(sp->SCp.buffer);
            sp->SCp.ptr = (char *) ((unsigned long)sg_dma_address(sp->SCp.buffer));
      }
}

static void esp_release_dmabufs(struct esp *esp, struct scsi_cmnd *sp)
{
      if (sp->use_sg) {
            sbus_unmap_sg(esp->sdev, sp->request_buffer, sp->use_sg,
                        sp->sc_data_direction);
      } else if (sp->request_bufflen) {
            sbus_unmap_single(esp->sdev,
                          sp->SCp.have_data_in,
                          sp->request_bufflen,
                          sp->sc_data_direction);
      }
}

static void esp_restore_pointers(struct esp *esp, struct scsi_cmnd *sp)
{
      struct esp_pointers *ep = &esp->data_pointers[sp->device->id];

      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 esp *esp, struct scsi_cmnd *sp)
{
      struct esp_pointers *ep = &esp->data_pointers[sp->device->id];

      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 esp *esp, struct 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 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;
}

/* SIZE is in bits, currently HME only supports 16 bit wide transfers. */
static inline void build_wide_nego_msg(struct esp *esp, int size)
{
      esp->cur_msgout[0] = EXTENDED_MESSAGE;
      esp->cur_msgout[1] = 2;
      esp->cur_msgout[2] = EXTENDED_WDTR;
      switch (size) {
      case 32:
            esp->cur_msgout[3] = 2;
            break;
      case 16:
            esp->cur_msgout[3] = 1;
            break;
      case 8:
      default:
            esp->cur_msgout[3] = 0;
            break;
      };

      esp->msgout_len = 4;
}

static void esp_exec_cmd(struct esp *esp)
{
      struct scsi_cmnd *SCptr;
      struct scsi_device *SDptr;
      struct esp_device *esp_dev;
      volatile u8 *cmdp = esp->esp_command;
      u8 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_IRQ_P(esp->dregs))
            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 */
#ifndef __sparc_v9__
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 {
            /* Sorry, I have had way too many problems with
             * various CDROM devices on ESP. -DaveM
             */
            int cdrom_hwbug_wkaround = 0;

#ifndef __sparc_v9__
            /* Never allow disconnects or synchronous transfers on
             * SparcStation1 and SparcStation1+.  Allowing those
             * to be enabled seems to lockup the machine completely.
             */
            if ((idprom->id_machtype == (SM_SUN4C | SM_4C_SS1)) ||
                (idprom->id_machtype == (SM_SUN4C | SM_4C_SS1PLUS))) {
                  /* But we are nice and allow tapes and removable
                   * disks (but not CDROMs) to disconnect.
                   */
                  if(SDptr->type == TYPE_TAPE ||
                     (SDptr->type != TYPE_ROM && SDptr->removable))
                        esp_dev->disconnect = 1;
                  else
                        esp_dev->disconnect = 0;
                  esp_dev->sync_max_offset = 0;
                  esp_dev->sync_min_period = 0;
                  esp_dev->sync = 1;
                  esp->snip = 0;
                  goto do_sync_known;
            }
#endif /* !(__sparc_v9__) */

            /* We've talked to this guy before,
             * but never negotiated.  Let's try,
             * need to attempt WIDE first, before
             * sync nego, as per SCSI 2 standard.
             */
            if (esp->erev == fashme && !esp_dev->wide) {
                  if (!SDptr->borken &&
                     SDptr->type != TYPE_ROM &&
                     SDptr->removable == 0) {
                        build_wide_nego_msg(esp, 16);
                        esp_dev->wide = 1;
                        esp->wnip = 1;
                        goto after_nego_msg_built;
                  } else {
                        esp_dev->wide = 1;
                        /* Fall through and try sync. */
                  }
            }

            if (!SDptr->borken) {
                  if ((SDptr->type == TYPE_ROM)) {
                        /* Nice try sucker... */
                        ESPMISC(("esp%d: Disabling sync for buggy "
                               "CDROM.\n", esp->esp_id));
                        cdrom_hwbug_wkaround = 1;
                        build_sync_nego_msg(esp, 0, 0);
                  } else if (SDptr->removable != 0) {
                        ESPMISC(("esp%d: Not negotiating sync/wide but "
                               "allowing disconnect for removable media.\n",
                               esp->esp_id));
                        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;

after_nego_msg_built:
            /* 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) &&
                SDptr->removable == 0) ||
                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];

      /* HME sucks... */
      if (esp->erev == fashme)
            sbus_writeb((target & 0xf) | (ESP_BUSID_RESELID | ESP_BUSID_CTR32BIT),
                      esp->eregs + ESP_BUSID);
      else
            sbus_writeb(target & 7, esp->eregs + ESP_BUSID);
      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->prev_stp = esp_dev->sync_min_period;
            sbus_writeb(esp->prev_soff, esp->eregs + ESP_SOFF);
            sbus_writeb(esp->prev_stp, esp->eregs + ESP_STP);
            if (esp->erev > esp100a) {
                  esp->prev_cfg3 = esp->config3[target];
                  sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_CFG3);
            }
      }
      i = (cmdp - esp->esp_command);

      if (esp->erev == fashme) {
            esp_cmd(esp, ESP_CMD_FLUSH); /* Grrr! */

            /* Set up the DMA and HME counters */
            sbus_writeb(i, esp->eregs + ESP_TCLOW);
            sbus_writeb(0, esp->eregs + ESP_TCMED);
            sbus_writeb(0, esp->eregs + FAS_RLO);
            sbus_writeb(0, esp->eregs + FAS_RHI);
            esp_cmd(esp, the_esp_command);

            /* Talk about touchy hardware... */
            esp->prev_hme_dmacsr = ((esp->prev_hme_dmacsr |
                               (DMA_SCSI_DISAB | DMA_ENABLE)) &
                              ~(DMA_ST_WRITE));
            sbus_writel(16, esp->dregs + DMA_COUNT);
            sbus_writel(esp->esp_command_dvma, esp->dregs + DMA_ADDR);
            sbus_writel(esp->prev_hme_dmacsr, esp->dregs + DMA_CSR);
      } else {
            u32 tmp;

            /* Set up the DMA and ESP counters */
            sbus_writeb(i, esp->eregs + ESP_TCLOW);
            sbus_writeb(0, esp->eregs + ESP_TCMED);
            tmp = sbus_readl(esp->dregs + DMA_CSR);
            tmp &= ~DMA_ST_WRITE;
            tmp |= DMA_ENABLE;
            sbus_writel(tmp, esp->dregs + DMA_CSR);
            if (esp->dma->revision == dvmaesc1) {
                  if (i) /* Workaround ESC gate array SBUS rerun bug. */
                        sbus_writel(PAGE_SIZE, esp->dregs + DMA_COUNT);
            }
            sbus_writel(esp->esp_command_dvma, esp->dregs + DMA_ADDR);

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

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

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

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

      esp = (struct esp *) SCpnt->device->host->hostdata;
      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(struct 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 esp *esp)
{
      struct scsi_cmnd *SCptr = esp->current_SC;
#ifdef DEBUG_ESP_CMDS
      int i;
#endif

      ESPLOG(("esp%d: dumping state\n", esp->esp_id));
      ESPLOG(("esp%d: dma -- cond_reg<%08x> addr<%08x>\n",
            esp->esp_id,
            sbus_readl(esp->dregs + DMA_CSR),
            sbus_readl(esp->dregs + DMA_ADDR)));
      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,
            sbus_readb(esp->eregs + ESP_STATUS),
            sbus_readb(esp->eregs + ESP_SSTEP),
            sbus_readb(esp->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 = (struct scsi_cmnd *) SCptr->host_scribble;
      }
      ESPLOG(("\n"));
}

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

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

      /* 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, 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 = (sbus_readl(esp->dregs + DMA_CSR) & DMA_INT_ENAB);
      if (don) {
            ESP_INTSOFF(esp->dregs);
      }
      if (esp->issue_SC) {
            struct scsi_cmnd **prev, *this;
            for (prev = (&esp->issue_SC), this = esp->issue_SC;
                 this != NULL;
                 prev = (struct scsi_cmnd **) &(this->host_scribble),
                       this = (struct scsi_cmnd *) this->host_scribble) {

                  if (this == SCptr) {
                        *prev = (struct scsi_cmnd *) this->host_scribble;
                        this->host_scribble = NULL;

                        esp_release_dmabufs(esp, this);
                        this->result = DID_ABORT << 16;
                        this->scsi_done(this);

                        if (don)
                              ESP_INTSON(esp->dregs);

                        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_INTSON(esp->dregs);
            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_INTSON(esp->dregs);

      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 esp *esp)
{
      struct scsi_cmnd *sp = esp->current_SC;

      /* Clean up currently executing command, if any. */
      if (sp != NULL) {
            esp->current_SC = NULL;

            esp_release_dmabufs(esp, sp);
            sp->result = (DID_RESET << 16);

            sp->scsi_done(sp);
      }

      /* 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 esp *esp)
{
      ESPLOG(("esp%d: Resetting scsi bus\n", esp->esp_id));
      esp->resetting_bus = 1;
      esp_cmd(esp, 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.
 */
static int esp_reset(struct scsi_cmnd *SCptr)
{
      struct esp *esp = (struct esp *) SCptr->device->host->hostdata;

      spin_lock_irq(esp->ehost->host_lock);
      (void) esp_do_resetbus(esp);
      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 esp *esp, int error)
{
      struct scsi_cmnd *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);

}

/* Wheee, ESP interrupt engine. */  

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

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

/* Read any bytes found in the FAS366 fifo, storing them into
 * the ESP driver software state structure.
 */
static void hme_fifo_read(struct esp *esp)
{
      u8 count = 0;
      u8 status = esp->sreg;

      /* Cannot safely frob the fifo for these following cases, but
       * we must always read the fifo when the reselect interrupt
       * is pending.
       */
      if (((esp->ireg & ESP_INTR_RSEL) == 0)    &&
          (sreg_datainp(status)           ||
           sreg_dataoutp(status)          ||
           (esp->current_SC &&
            esp->current_SC->SCp.phase == in_data_done))) {
            ESPHME(("<wkaround_skipped>"));
      } else {
            unsigned long fcnt = sbus_readb(esp->eregs + ESP_FFLAGS) & ESP_FF_FBYTES;

            /* The HME stores bytes in multiples of 2 in the fifo. */
            ESPHME(("hme_fifo[fcnt=%d", (int)fcnt));
            while (fcnt) {
                  esp->hme_fifo_workaround_buffer[count++] =
                        sbus_readb(esp->eregs + ESP_FDATA);
                  esp->hme_fifo_workaround_buffer[count++] =
                        sbus_readb(esp->eregs + ESP_FDATA);
                  ESPHME(("<%02x,%02x>", esp->hme_fifo_workaround_buffer[count-2], esp->hme_fifo_workaround_buffer[count-1]));
                  fcnt--;
            }
            if (sbus_readb(esp->eregs + ESP_STATUS2) & ESP_STAT2_F1BYTE) {
                  ESPHME(("<poke_byte>"));
                  sbus_writeb(0, esp->eregs + ESP_FDATA);
                  esp->hme_fifo_workaround_buffer[count++] =
                        sbus_readb(esp->eregs + ESP_FDATA);
                  ESPHME(("<%02x,0x00>", esp->hme_fifo_workaround_buffer[count-1]));
                  ESPHME(("CMD_FLUSH"));
                  esp_cmd(esp, ESP_CMD_FLUSH);
            } else {
                  ESPHME(("no_xtra_byte"));
            }
      }
      ESPHME(("wkarnd_cnt=%d]", (int)count));
      esp->hme_fifo_workaround_count = count;
}

static inline void hme_fifo_push(struct esp *esp, u8 *bytes, u8 count)
{
      esp_cmd(esp, ESP_CMD_FLUSH);
      while (count) {
            u8 tmp = *bytes++;
            sbus_writeb(tmp, esp->eregs + ESP_FDATA);
            sbus_writeb(0, esp->eregs + ESP_FDATA);
            count--;
      }
}

/* 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 esp *esp, struct scsi_cmnd *scp,
                       int prev_phase, int new_phase)
{
      if (scp->SCp.sent_command != prev_phase)
            return 0;
      if (ESP_IRQ_P(esp->dregs)) {
            /* Yes, we are able to save an interrupt. */
            if (esp->erev == fashme)
                  esp->sreg2 = sbus_readb(esp->eregs + ESP_STATUS2);
            esp->sreg = (sbus_readb(esp->eregs + ESP_STATUS) & ~(ESP_STAT_INTR));
            esp->ireg = sbus_readb(esp->eregs + ESP_INTRPT);
            if (esp->erev == fashme) {
                  /* This chip is really losing. */
                  ESPHME(("HME["));
                  /* Must latch fifo before reading the interrupt
                   * register else garbage ends up in the FIFO
                   * which confuses the driver utterly.
                   * Happy Meal indeed....
                   */
                  ESPHME(("fifo_workaround]"));
                  if (!(esp->sreg2 & ESP_STAT2_FEMPTY) ||
                      (esp->sreg2 & ESP_STAT2_F1BYTE))
                        hme_fifo_read(esp);
            }
            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 esp *esp, struct 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_IRQ_P(esp->dregs)) {
            /* Yes, we are able to save an interrupt. */
            if (esp->erev == fashme)
                  esp->sreg2 = sbus_readb(esp->eregs + ESP_STATUS2);
            esp->sreg = (sbus_readb(esp->eregs + ESP_STATUS) & ~(ESP_STAT_INTR));
            esp->ireg = sbus_readb(esp->eregs + ESP_INTRPT);
            if (esp->erev == fashme) {
                  /* This chip is really losing. */
                  ESPHME(("HME["));

                  /* Must latch fifo before reading the interrupt
                   * register else garbage ends up in the FIFO
                   * which confuses the driver utterly.
                   * Happy Meal indeed....
                   */
                  ESPHME(("fifo_workaround]"));
                  if (!(esp->sreg2 & ESP_STAT2_FEMPTY) ||
                      (esp->sreg2 & ESP_STAT2_F1BYTE))
                        hme_fifo_read(esp);
            }
            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;
}

/* Now some dma helpers. */
static void dma_setup(struct esp *esp, __u32 addr, int count, int write)
{
      u32 nreg = sbus_readl(esp->dregs + DMA_CSR);

      if (write)
            nreg |= DMA_ST_WRITE;
      else
            nreg &= ~(DMA_ST_WRITE);
      nreg |= DMA_ENABLE;
      sbus_writel(nreg, esp->dregs + DMA_CSR);
      if (esp->dma->revision == dvmaesc1) {
            /* This ESC gate array sucks! */
            __u32 src = addr;
            __u32 dest = src + count;

            if (dest & (PAGE_SIZE - 1))
                  count = PAGE_ALIGN(count);
            sbus_writel(count, esp->dregs + DMA_COUNT);
      }
      sbus_writel(addr, esp->dregs + DMA_ADDR);
}

static void dma_drain(struct esp *esp)
{
      u32 tmp;

      if (esp->dma->revision == dvmahme)
            return;
      if ((tmp = sbus_readl(esp->dregs + DMA_CSR)) & DMA_FIFO_ISDRAIN) {
            switch (esp->dma->revision) {
            default:
                  tmp |= DMA_FIFO_STDRAIN;
                  sbus_writel(tmp, esp->dregs + DMA_CSR);

            case dvmarev3:
            case dvmaesc1:
                  while (sbus_readl(esp->dregs + DMA_CSR) & DMA_FIFO_ISDRAIN)
                        udelay(1);
            };
      }
}

static void dma_invalidate(struct esp *esp)
{
      u32 tmp;

      if (esp->dma->revision == dvmahme) {
            sbus_writel(DMA_RST_SCSI, esp->dregs + DMA_CSR);

            esp->prev_hme_dmacsr = ((esp->prev_hme_dmacsr |
                               (DMA_PARITY_OFF | DMA_2CLKS |
                                DMA_SCSI_DISAB | DMA_INT_ENAB)) &
                              ~(DMA_ST_WRITE | DMA_ENABLE));

            sbus_writel(0, esp->dregs + DMA_CSR);
            sbus_writel(esp->prev_hme_dmacsr, esp->dregs + DMA_CSR);

            /* This is necessary to avoid having the SCSI channel
             * engine lock up on us.
             */
            sbus_writel(0, esp->dregs + DMA_ADDR);
      } else {
            while ((tmp = sbus_readl(esp->dregs + DMA_CSR)) & DMA_PEND_READ)
                  udelay(1);

            tmp &= ~(DMA_ENABLE | DMA_ST_WRITE | DMA_BCNT_ENAB);
            tmp |= DMA_FIFO_INV;
            sbus_writel(tmp, esp->dregs + DMA_CSR);
            tmp &= ~DMA_FIFO_INV;
            sbus_writel(tmp, esp->dregs + DMA_CSR);
      }
}

static inline void dma_flashclear(struct esp *esp)
{
      dma_drain(esp);
      dma_invalidate(esp);
}

static int dma_can_transfer(struct esp *esp, struct scsi_cmnd *sp)
{
      __u32 base, end, sz;

      if (esp->dma->revision == dvmarev3) {
            sz = sp->SCp.this_residual;
            if (sz > 0x1000000)
                  sz = 0x1000000;
      } else {
            base = ((__u32)((unsigned long)sp->SCp.ptr));
            base &= (0x1000000 - 1);
            end = (base + sp->SCp.this_residual);
            if (end > 0x1000000)
                  end = 0x1000000;
            sz = (end - base);
      }
      return sz;
}

/* Misc. esp helper macros. */
#define esp_setcount(__eregs, __cnt, __hme) \
      sbus_writeb(((__cnt)&0xff), (__eregs) + ESP_TCLOW); \
      sbus_writeb((((__cnt)>>8)&0xff), (__eregs) + ESP_TCMED); \
      if (__hme) { \
            sbus_writeb((((__cnt)>>16)&0xff), (__eregs) + FAS_RLO); \
            sbus_writeb(0, (__eregs) + FAS_RHI); \
      }

#define esp_getcount(__eregs, __hme) \
      ((sbus_readb((__eregs) + ESP_TCLOW)&0xff) | \
       ((sbus_readb((__eregs) + ESP_TCMED)&0xff) << 8) | \
         ((__hme) ? sbus_readb((__eregs) + FAS_RLO) << 16 : 0))

#define fcount(__esp) \
      (((__esp)->erev == fashme) ? \
        (__esp)->hme_fifo_workaround_count : \
        sbus_readb(((__esp)->eregs) + ESP_FFLAGS) & ESP_FF_FBYTES)

#define fnzero(__esp) \
      (((__esp)->erev == fashme) ? 0 : \
       sbus_readb(((__esp)->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) \
      if ((__esp)->erev == esp100) \
            esp_cmd((__esp), 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 int esp100_sync_hwbug(struct esp *esp, struct scsi_cmnd *sp, int fifocnt)
{
      /* Do not touch this piece of code. */
      if ((!(esp->erev == esp100)) ||
          (!(sreg_datainp((esp->sreg = sbus_readb(esp->eregs + ESP_STATUS))) &&
             !fifocnt) &&
           !(sreg_dataoutp(esp->sreg) && !fnzero(esp)))) {
            if (sp->SCp.phase == in_dataout)
                  esp_cmd(esp, 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, ESP_CMD_SATN);
            esp_cmd(esp, 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 esp *esp)
{
      u8 tmp;

      if (esp->erev != esp100)
            return 0;
      tmp = sbus_readb(esp->eregs + ESP_INTRPT);
      if (tmp & 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 esp *esp)
{
      int it, me = esp->scsi_id_mask, targ = 0;

      if (2 != fcount(esp))
            return -1;
      if (esp->erev == fashme) {
            /* HME does not latch it's own BUS ID bits during
             * a reselection.  Also the target number is given
             * as an unsigned char, not as a sole bit number
             * like the other ESP's do.
             * Happy Meal indeed....
             */
            targ = esp->hme_fifo_workaround_buffer[0];
      } else {
            it = sbus_readb(esp->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 esp *esp)
{
      int lun;

      if ((esp->sreg & ESP_STAT_PMASK) != ESP_MIP)
            return -1;
      if (esp->erev == fashme)
            lun = esp->hme_fifo_workaround_buffer[1];
      else
            lun = sbus_readb(esp->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 esp *esp, struct scsi_cmnd *sp)
{
      struct esp_device *esp_dev = sp->device->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[sp->device->id])) {
            esp->prev_soff = esp_dev->sync_max_offset;
            esp->prev_stp = esp_dev->sync_min_period;
            sbus_writeb(esp->prev_soff, esp->eregs + ESP_SOFF);
            sbus_writeb(esp->prev_stp, esp->eregs + ESP_STP);
            if (esp->erev > esp100a) {
                  esp->prev_cfg3 = esp->config3[sp->device->id];
                  sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_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 esp *esp, struct 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 esp *esp)
{
      /* Must be very careful with the fifo on the HME */
      if ((esp->erev != fashme) ||
          !(sbus_readb(esp->eregs + ESP_STATUS2) & ESP_STAT2_FEMPTY))
            esp_cmd(esp, ESP_CMD_FLUSH);
      esp_maybe_nop(esp);
      esp_cmd(esp, ESP_CMD_TI);
      esp->msgin_len = 1;
      esp->msgin_ctr = 0;
      esp_advance_phase(esp->current_SC, in_msgindone);
      return do_work_bus;
}

/* This uses various DMA csr fields and the fifo flags count value to
 * determine how many bytes were successfully sent/received by the ESP.
 */
static inline int esp_bytes_sent(struct esp *esp, int fifo_count)
{
      int rval = sbus_readl(esp->dregs + DMA_ADDR) - esp->esp_command_dvma;

      if (esp->dma->revision == dvmarev1)
            rval -= (4 - ((sbus_readl(esp->dregs + DMA_CSR) & DMA_READ_AHEAD)>>11));
      return rval - fifo_count;
}

static inline void advance_sg(struct scsi_cmnd *sp)
{
      ++sp->SCp.buffer;
      --sp->SCp.buffers_residual;
      sp->SCp.this_residual = sg_dma_len(sp->SCp.buffer);
      sp->SCp.ptr = (char *)((unsigned long)sg_dma_address(sp->SCp.buffer));
}

/* 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 esp *esp)
{
      struct scsi_cmnd *SCptr = esp->current_SC;
      int thisphase, hmuch;

      ESPDATA(("esp_do_data: "));
      esp_maybe_nop(esp);
      thisphase = sreg_to_dataphase(esp->sreg);
      esp_advance_phase(SCptr, thisphase);
      ESPDATA(("newphase<%s> ", (thisphase == in_datain) ? "DATAIN" : "DATAOUT"));
      hmuch = dma_can_transfer(esp, SCptr);
      if (hmuch > (64 * 1024) && (esp->erev != fashme))
            hmuch = (64 * 1024);
      ESPDATA(("hmuch<%d> ", hmuch));
      esp->current_transfer_size = hmuch;

      if (esp->erev == fashme) {
            u32 tmp = esp->prev_hme_dmacsr;

            /* Always set the ESP count registers first. */
            esp_setcount(esp->eregs, hmuch, 1);

            /* Get the DMA csr computed. */
            tmp |= (DMA_SCSI_DISAB | DMA_ENABLE);
            if (thisphase == in_datain)
                  tmp |= DMA_ST_WRITE;
            else
                  tmp &= ~(DMA_ST_WRITE);
            esp->prev_hme_dmacsr = tmp;

            ESPDATA(("DMA|TI --> do_intr_end\n"));
            if (thisphase == in_datain) {
                  sbus_writel(hmuch, esp->dregs + DMA_COUNT);
                  esp_cmd(esp, ESP_CMD_DMA | ESP_CMD_TI);
            } else {
                  esp_cmd(esp, ESP_CMD_DMA | ESP_CMD_TI);
                  sbus_writel(hmuch, esp->dregs + DMA_COUNT);
            }
            sbus_writel((__u32)((unsigned long)SCptr->SCp.ptr), esp->dregs+DMA_ADDR);
            sbus_writel(esp->prev_hme_dmacsr, esp->dregs + DMA_CSR);
      } else {
            esp_setcount(esp->eregs, hmuch, 0);
            dma_setup(esp, ((__u32)((unsigned long)SCptr->SCp.ptr)),
                    hmuch, (thisphase == in_datain));
            ESPDATA(("DMA|TI --> do_intr_end\n"));
            esp_cmd(esp, ESP_CMD_DMA | ESP_CMD_TI);
      }
      return do_intr_end;
}

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

      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;
            }
            dma_drain(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);
      }     

      /* Check for partial transfers and other horrible events.
       * Note, here we read the real fifo flags register even
       * on HME broken adapters because we skip the HME fifo
       * workaround code in esp_handle() if we are doing data
       * phase things.  We don't want to fuck directly with
       * the fifo like that, especially if doing synchronous
       * transfers!  Also, will need to double the count on
       * HME if we are doing wide transfers, as the HME fifo
       * will move and count 16-bit quantities during wide data.
       * SMCC _and_ Qlogic can both bite me.
       */
      fifocnt = (sbus_readb(esp->eregs + ESP_FFLAGS) & ESP_FF_FBYTES);
      if (esp->erev != fashme)
            ecount = esp_getcount(esp->eregs, 0);
      bytes_sent = esp->current_transfer_size;

      ESPDATA(("trans_sz(%d), ", bytes_sent));
      if (esp->erev == fashme) {
            if (!(esp->sreg & ESP_STAT_TCNT)) {
                  ecount = esp_getcount(esp->eregs, 1);
                  bytes_sent -= ecount;
            }

            /* Always subtract any cruft remaining in the FIFO. */
            if (esp->prev_cfg3 & ESP_CONFIG3_EWIDE)
                  fifocnt <<= 1;
            if (SCptr->SCp.phase == in_dataout)
                  bytes_sent -= fifocnt;

            /* I have an IBM disk which exhibits the following
             * behavior during writes to it.  It disconnects in
             * the middle of a partial transfer, the current sglist
             * buffer is 1024 bytes, the disk stops data transfer
             * at 512 bytes.
             *
             * However the FAS366 reports that 32 more bytes were
             * transferred than really were.  This is precisely
             * the size of a fully loaded FIFO in wide scsi mode.
             * The FIFO state recorded indicates that it is empty.
             *
             * I have no idea if this is a bug in the FAS366 chip
             * or a bug in the firmware on this IBM disk.  In any
             * event the following seems to be a good workaround.  -DaveM
             */
            if (bytes_sent != esp->current_transfer_size &&
                SCptr->SCp.phase == in_dataout) {
                  int mask = (64 - 1);

                  if ((esp->prev_cfg3 & ESP_CONFIG3_EWIDE) == 0)
                        mask >>= 1;

                  if (bytes_sent & mask)
                        bytes_sent -= (bytes_sent & mask);
            }
      } else {
            if (!(esp->sreg & ESP_STAT_TCNT))
                  bytes_sent -= ecount;
            if (SCptr->SCp.phase == in_dataout)
                  bytes_sent -= fifocnt;
      }

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

      /* If we were in synchronous mode, check for peculiarities. */
      if (esp->erev == fashme) {
            if (esp_dev->sync_max_offset) {
                  if (SCptr->SCp.phase == in_dataout)
                        esp_cmd(esp, ESP_CMD_FLUSH);
            } else {
                  esp_cmd(esp, ESP_CMD_FLUSH);
            }
      } else {
            if (esp_dev->sync_max_offset)
                  bogus_data = esp100_sync_hwbug(esp, SCptr, fifocnt);
            else
                  esp_cmd(esp, ESP_CMD_FLUSH);
      }

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

      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->use_sg && !SCptr->SCp.this_residual)
                  advance_sg(SCptr);
            if (sreg_datainp(esp->sreg) || sreg_dataoutp(esp->sreg)) {
                  ESPDATA(("to more data\n"));
                  return esp_do_data(esp);
            }
            ESPDATA(("to new phase\n"));
            return esp_do_phase_determine(esp);
      }
      /* 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(struct scsi_cmnd *sp)
{
      u8 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) {
            if (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 esp *esp)
{
      struct scsi_cmnd *SCptr = esp->current_SC;
      struct esp_device *esp_dev = SCptr->device->hostdata;
      int rval;

      rval = skipahead2(esp, 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) {
            /* Normal end of nexus. */
            if (esp->disconnected_SC || (esp->erev == fashme))
                  esp_cmd(esp, ESP_CMD_ESEL);

            if (SCptr->SCp.Status != GOOD &&
                SCptr->SCp.Status != CONDITION_GOOD &&
                ((1<<SCptr->device->id) & 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, 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 esp *esp)
{
      struct 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 = (struct scsi_cmnd *) sp->host_scribble;
      }
      ESPLOG(("]\n"));
      sp = esp->current_SC;
      ESPLOG(("esp%d: current_SC[", esp->esp_id));
      if (sp)
            ESPLOG(("<%02x,%02x>", sp->device->id, sp->device->lun));
      else
            ESPLOG(("<NULL>"));
      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 = (struct 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 esp *esp)
{
      int lun, target;
      struct scsi_cmnd *SCptr;

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

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

      /* Must not flush FIFO or DVMA on HME. */
      if (esp->erev != fashme) {
            esp_cmd(esp, ESP_CMD_FLUSH);
            if (esp100_reconnect_hwbug(esp))
                  return do_reset_bus;
            esp_cmd(esp, ESP_CMD_NULL);
      }

      SCptr = remove_SC(&esp->disconnected_SC, (u8) target, (u8) lun);
      if (!SCptr)
            return esp_bad_reconnect(esp);

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

      if (esp->erev == fashme)
            sbus_writeb(((SCptr->device->id & 0xf) |
                       (ESP_BUSID_RESELID | ESP_BUSID_CTR32BIT)),
                      esp->eregs + ESP_BUSID);

      /* 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 esp *esp)
{
      struct scsi_cmnd *SCptr = esp->current_SC;
      int intr, rval;

      rval = skipahead1(esp, 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, ESP_CMD_MOK);

            if (esp->erev != fashme) {
                  dma_flashclear(esp);

                  /* Wait till the first bits settle. */
                  while (esp->esp_command[0] == 0xff)
                        udelay(1);
            } else {
                  esp->esp_command[0] = esp->hme_fifo_workaround_buffer[0];
                  esp->esp_command[1] = esp->hme_fifo_workaround_buffer[1];
            }

            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);
            }

            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);
                  } 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);
                  }
            } 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);
            }
      } 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);
      }
}

static int esp_enter_status(struct esp *esp)
{
      u8 thecmd = ESP_CMD_ICCSEQ;

      esp_cmd(esp, ESP_CMD_FLUSH);
      if (esp->erev != fashme) {
            u32 tmp;

            esp->esp_command[0] = esp->esp_command[1] = 0xff;
            sbus_writeb(2, esp->eregs + ESP_TCLOW);
            sbus_writeb(0, esp->eregs + ESP_TCMED);
            tmp = sbus_readl(esp->dregs + DMA_CSR);
            tmp |= (DMA_ST_WRITE | DMA_ENABLE);
            sbus_writel(tmp, esp->dregs + DMA_CSR);
            if (esp->dma->revision == dvmaesc1)
                  sbus_writel(0x100, esp->dregs + DMA_COUNT);
            sbus_writel(esp->esp_command_dvma, esp->dregs + DMA_ADDR);
            thecmd |= ESP_CMD_DMA;
      }
      esp_cmd(esp, thecmd);
      esp_advance_phase(esp->current_SC, in_status);

      return esp_do_status(esp);
}

static int esp_disconnect_amidst_phases(struct esp *esp)
{
      struct 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 != NULL || (esp->erev == fashme))
            esp_cmd(esp, 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 esp *esp)
{
      esp_advance_phase(esp->current_SC, in_msgout);
      return esp_do_msgout(esp);
}

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

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

static int esp_enter_badphase(struct esp *esp)
{
      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 esp *);

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 esp *esp)
{
      if ((esp->ireg & ESP_INTR_DC) != 0)
            return esp_disconnect_amidst_phases(esp);
      return phase_vector[esp->sreg & ESP_STAT_PMASK](esp);
}

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

      if (esp->erev != fashme)
            esp->seqreg = (sbus_readb(esp->eregs + ESP_SSTEP) & ESP_STEP_VBITS);

      if (esp->erev == fashme)
            fcnt = esp->hme_fifo_workaround_count;
      else
            fcnt = (sbus_readb(esp->eregs + ESP_FFLAGS) & ESP_FF_FBYTES);

      cmd_bytes_sent = esp_bytes_sent(esp, fcnt);
      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);
      }

      /* 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<<SCptr->device->id);

            /* 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;
            };

            if (esp->erev != fashme)
                  esp_cmd(esp, ESP_CMD_NULL);

            /* Be careful, we could really get fucked during synchronous
             * data transfers if we try to flush the fifo now.
             */
            if ((esp->erev != fashme) && /* not a Happy Meal and... */
                !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, 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);
      }

      /* 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, ESP_CMD_ESEL);

            if (((1<<SCptr->device->id) & esp->targets_present) &&
                esp->seqreg != 0 &&
                (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 = sbus_readb(esp->eregs + ESP_STATUS);
      esp->seqreg = sbus_readb(esp->eregs + ESP_SSTEP);
      esp->ireg = sbus_readb(esp->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 esp *esp)
{
      if (esp->ireg & ESP_INTR_BSERV) {
            /* in the right phase too? */
            if ((esp->sreg & ESP_STAT_PMASK) == ESP_MIP) {
                  /* phew... */
                  esp_cmd(esp, 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 esp *esp)
{
      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 esp *esp,
                             struct 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 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 ((esp->erev == fashme) &&
                (esp->config3[esp->current_SC->device->id] & ESP_CONFIG3_EWIDE)) {
                  type = "FAST-WIDE";
                  integer <<= 1;
                  fraction <<= 1;
            } else 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 esp *esp)
{
      struct scsi_cmnd *SCptr = esp->current_SC;
      struct esp_device *esp_dev = SCptr->device->hostdata;
      u8 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 == fas100a ||
                              esp->erev == fas236  ||
                              esp->erev == fashme))) {
                        if (period >= 50)
                              regval--;
                  }
            }

            if (offset) {
                  u8 bit;

                  esp_dev->sync_min_period = (regval & 0x1f);
                  esp_dev->sync_max_offset = (offset | esp->radelay);
                  if (esp->erev == fas100a || esp->erev == fas236 || esp->erev == fashme) {
                        if ((esp->erev == fas100a) || (esp->erev == fashme))
                              bit = ESP_CONFIG3_FAST;
                        else
                              bit = ESP_CONFIG3_FSCSI;
                        if (period < 50) {
                              /* On FAS366, if using fast-20 synchronous transfers
                               * we need to make sure the REQ/ACK assert/deassert
                               * control bits are clear.
                               */
                              if (esp->erev == fashme)
                                    esp_dev->sync_max_offset &= ~esp->radelay;
                              esp->config3[SCptr->device->id] |= bit;
                        } else {
                              esp->config3[SCptr->device->id] &= ~bit;
                        }
                        esp->prev_cfg3 = esp->config3[SCptr->device->id];
                        sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_CFG3);
                  }
                  esp->prev_soff = esp_dev->sync_max_offset;
                  esp->prev_stp = esp_dev->sync_min_period;
                  sbus_writeb(esp->prev_soff, esp->eregs + ESP_SOFF);
                  sbus_writeb(esp->prev_stp, esp->eregs + ESP_STP);
                  ESPSDTR(("soff=%2x stp=%2x cfg3=%2x\n",
                         esp_dev->sync_max_offset,
                         esp_dev->sync_min_period,
                         esp->config3[SCptr->device->id]));

                  esp->snip = 0;
            } else if (esp_dev->sync_max_offset) {
                  u8 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->prev_stp = 0;
                  sbus_writeb(esp->prev_soff, esp->eregs + ESP_SOFF);
                  sbus_writeb(esp->prev_stp, esp->eregs + ESP_STP);
                  if (esp->erev == fas100a || esp->erev == fas236 || esp->erev == fashme) {
                        if ((esp->erev == fas100a) || (esp->erev == fashme))
                              bit = ESP_CONFIG3_FAST;
                        else
                              bit = ESP_CONFIG3_FSCSI;
                        esp->config3[SCptr->device->id] &= ~bit;
                        esp->prev_cfg3 = esp->config3[SCptr->device->id];
                        sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_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) {
            int size = 8 << esp->cur_msgin[3];

            esp->wnip = 0;
            if (esp->erev != fashme) {
                  ESPLOG(("esp%d: AIEEE wide msg received and not HME.\n",
                        esp->esp_id));
                  message_out = MESSAGE_REJECT;
            } else if (size > 16) {
                  ESPLOG(("esp%d: AIEEE wide transfer for %d size "
                        "not supported.\n", esp->esp_id, size));
                  message_out = MESSAGE_REJECT;
            } else {
                  /* Things look good; let's see what we got. */
                  if (size == 16) {
                        /* Set config 3 register for this target. */
                        esp->config3[SCptr->device->id] |= ESP_CONFIG3_EWIDE;
                  } else {
                        /* Just make sure it was one byte sized. */
                        if (size != 8) {
                              ESPLOG(("esp%d: Aieee, wide nego of %d size.\n",
                                    esp->esp_id, size));
                              message_out = MESSAGE_REJECT;
                              goto finish;
                        }
                        /* Pure paranoia. */
                        esp->config3[SCptr->device->id] &= ~(ESP_CONFIG3_EWIDE);
                  }
                  esp->prev_cfg3 = esp->config3[SCptr->device->id];
                  sbus_writeb(esp->prev_cfg3, esp->eregs + ESP_CFG3);

                  /* Regardless, next try for sync transfers. */
                  build_sync_nego_msg(esp, esp->sync_defp, 15);
                  esp_dev->sync = 1;
                  esp->snip = 1;
                  message_out = EXTENDED_MESSAGE;
            }
      } 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;
      }
finish:
      esp_advance_phase(SCptr, in_the_dark);
      return message_out;
}

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

      rval = skipahead1(esp, 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, ESP_CMD_FLUSH);
                  } else if (esp->erev != fashme &&
                    (it = (sbus_readb(esp->eregs + ESP_FFLAGS) & ESP_FF_FBYTES)) != 1) {
                        /* We certainly dropped the ball somewhere. */
                        message_out = INITIATOR_ERROR;
                        esp_cmd(esp, ESP_CMD_FLUSH);
                  } else if (!esp->msgin_len) {
                        if (esp->erev == fashme)
                              it = esp->hme_fifo_workaround_buffer[0];
                        else
                              it = sbus_readb(esp->eregs + ESP_FDATA);
                        esp_advance_phase(SCptr, in_msgincont);
                  } else {
                        /* it is ok and we want it */
                        if (esp->erev == fashme)
                              it = esp->cur_msgin[esp->msgin_ctr] =
                                    esp->hme_fifo_workaround_buffer[0];
                        else
                              it = esp->cur_msgin[esp->msgin_ctr] =
                                    sbus_readb(esp->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);
            } 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);
            }
      }
      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, ESP_CMD_SATN);
            esp_advance_phase(SCptr, in_the_dark);
            esp->msgin_len = 0;
      }
      esp->sreg = sbus_readb(esp->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, ESP_CMD_MOK);
      if ((SCptr->SCp.sent_command == in_msgindone) &&
          (SCptr->SCp.phase == in_freeing))
            return esp_do_freebus(esp);
      return do_intr_end;
}

static int esp_do_cmdbegin(struct esp *esp)
{
      struct scsi_cmnd *SCptr = esp->current_SC;

      esp_advance_phase(SCptr, in_cmdend);
      if (esp->erev == fashme) {
            u32 tmp = sbus_readl(esp->dregs + DMA_CSR);
            int i;

            for (i = 0; i < esp->esp_scmdleft; i++)
                  esp->esp_command[i] = *esp->esp_scmdp++;
            esp->esp_scmdleft = 0;
            esp_cmd(esp, ESP_CMD_FLUSH);
            esp_setcount(esp->eregs, i, 1);
            esp_cmd(esp, (ESP_CMD_DMA | ESP_CMD_TI));
            tmp |= (DMA_SCSI_DISAB | DMA_ENABLE);
            tmp &= ~(DMA_ST_WRITE);
            sbus_writel(i, esp->dregs + DMA_COUNT);
            sbus_writel(esp->esp_command_dvma, esp->dregs + DMA_ADDR);
            sbus_writel(tmp, esp->dregs + DMA_CSR);
      } else {
            u8 tmp;

            esp_cmd(esp, ESP_CMD_FLUSH);
            tmp = *esp->esp_scmdp++;
            esp->esp_scmdleft--;
            sbus_writeb(tmp, esp->eregs + ESP_FDATA);
            esp_cmd(esp, ESP_CMD_TI);
      }
      return do_intr_end;
}

static int esp_do_cmddone(struct esp *esp)
{
      if (esp->erev == fashme)
            dma_invalidate(esp);
      else
            esp_cmd(esp, ESP_CMD_NULL);

      if (esp->ireg & ESP_INTR_BSERV) {
            esp_advance_phase(esp->current_SC, in_the_dark);
            return esp_do_phase_determine(esp);
      }

      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 esp *esp)
{
      esp_cmd(esp, ESP_CMD_FLUSH);
      switch (esp->msgout_len) {
      case 1:
            if (esp->erev == fashme)
                  hme_fifo_push(esp, &esp->cur_msgout[0], 1);
            else
                  sbus_writeb(esp->cur_msgout[0], esp->eregs + ESP_FDATA);

            esp_cmd(esp, ESP_CMD_TI);
            break;

      case 2:
            esp->esp_command[0] = esp->cur_msgout[0];
            esp->esp_command[1] = esp->cur_msgout[1];

            if (esp->erev == fashme) {
                  hme_fifo_push(esp, &esp->cur_msgout[0], 2);
                  esp_cmd(esp, ESP_CMD_TI);
            } else {
                  dma_setup(esp, esp->esp_command_dvma, 2, 0);
                  esp_setcount(esp->eregs, 2, 0);
                  esp_cmd(esp, ESP_CMD_DMA | ESP_CMD_TI);
            }
            break;

      case 4:
            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->snip = 1;

            if (esp->erev == fashme) {
                  hme_fifo_push(esp, &esp->cur_msgout[0], 4);
                  esp_cmd(esp, ESP_CMD_TI);
            } else {
                  dma_setup(esp, esp->esp_command_dvma, 4, 0);
                  esp_setcount(esp->eregs, 4, 0);
                  esp_cmd(esp, ESP_CMD_DMA | ESP_CMD_TI);
            }
            break;

      case 5:
            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->snip = 1;

            if (esp->erev == fashme) {
                  hme_fifo_push(esp, &esp->cur_msgout[0], 5);
                  esp_cmd(esp, ESP_CMD_TI);
            } else {
                  dma_setup(esp, esp->esp_command_dvma, 5, 0);
                  esp_setcount(esp->eregs, 5, 0);
                  esp_cmd(esp, ESP_CMD_DMA | ESP_CMD_TI);
            }
            break;

      default:
            /* whoops */
            ESPMISC(("bogus msgout sending NOP\n"));
            esp->cur_msgout[0] = NOP;

            if (esp->erev == fashme) {
                  hme_fifo_push(esp, &esp->cur_msgout[0], 1);
            } else {
                  sbus_writeb(esp->cur_msgout[0], esp->eregs + ESP_FDATA);
            }

            esp->msgout_len = 1;
            esp_cmd(esp, ESP_CMD_TI);
            break;
      };

      esp_advance_phase(esp->current_SC, in_msgoutdone);
      return do_intr_end;
}

static int esp_do_msgoutdone(struct esp *esp)
{
      if (esp->msgout_len > 1) {
            /* XXX HME/FAS ATN deassert workaround required,
             * XXX no DMA flushing, only possible ESP_CMD_FLUSH
             * XXX to kill the fifo.
             */
            if (esp->erev != fashme) {
                  u32 tmp;

                  while ((tmp = sbus_readl(esp->dregs + DMA_CSR)) & DMA_PEND_READ)
                        udelay(1);
                  tmp &= ~DMA_ENABLE;
                  sbus_writel(tmp, esp->dregs + DMA_CSR);
                  dma_invalidate(esp);
            } else {
                  esp_cmd(esp, ESP_CMD_FLUSH);
            }
      }
      if (!(esp->ireg & ESP_INTR_DC)) {
            if (esp->erev != fashme)
                  esp_cmd(esp, 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, ESP_CMD_SATN);
                  esp_advance_phase(esp->current_SC, in_msgout);
                  return do_work_bus;

            case ESP_DIP:
                  break;

            default:
                  /* Happy Meal fifo is touchy... */
                  if ((esp->erev != fashme) &&
                      !fcount(esp) &&
                      !(((struct esp_device *)esp->current_SC->device->hostdata)->sync_max_offset))
                        esp_cmd(esp, ESP_CMD_FLUSH);
                  break;

            };
      } else {
            ESPLOG(("esp%d: disconnect, resetting bus\n", esp->esp_id));
            return do_reset_bus;
      }

      /* 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);
}

static int esp_bus_unexpected(struct esp *esp)
{
      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 esp *esp)
{
      struct scsi_cmnd *SCptr = esp->current_SC;
      unsigned int phase;

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

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. */
static void esp_handle(struct esp *esp)
{
      struct scsi_cmnd *SCptr;
      int what_next = do_intr_end;

      SCptr = esp->current_SC;

      /* Check for errors. */
      esp->sreg = sbus_readb(esp->eregs + ESP_STATUS);
      esp->sreg &= (~ESP_STAT_INTR);
      if (esp->erev == fashme) {
            esp->sreg2 = sbus_readb(esp->eregs + ESP_STATUS2);
            esp->seqreg = (sbus_readb(esp->eregs + ESP_SSTEP) & ESP_STEP_VBITS);
      }

      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;
            }
      }

      if (sbus_readl(esp->dregs + DMA_CSR) & DMA_HNDL_ERROR) {
            /* A DMA gate array error.  Here we must
             * be seeing one of two things.  Either the
             * virtual to physical address translation
             * on the SBUS could not occur, else the
             * translation it did get pointed to a bogus
             * page.  Ho hum...
             */
            ESPLOG(("esp%d: DMA error %08x\n", esp->esp_id,
                  sbus_readl(esp->dregs + DMA_CSR)));

            /* DMA gate array itself must be reset to clear the
             * error condition.
             */
            esp_reset_dma(esp);

            what_next = do_reset_bus;
            goto state_machine;
      }

      esp->ireg = sbus_readb(esp->eregs + ESP_INTRPT);   /* Unlatch intr reg */

      if (esp->erev == fashme) {
            /* This chip is really losing. */
            ESPHME(("HME["));

            ESPHME(("sreg2=%02x,", esp->sreg2));
            /* Must latch fifo before reading the interrupt
             * register else garbage ends up in the FIFO
             * which confuses the driver utterly.
             */
            if (!(esp->sreg2 & ESP_STAT2_FEMPTY) ||
                (esp->sreg2 & ESP_STAT2_F1BYTE)) {
                  ESPHME(("fifo_workaround]"));
                  hme_fifo_read(esp);
            } else {
                  ESPHME(("no_fifo_workaround]"));
            }
      }

      /* 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);

            if (SCptr != NULL) {
                  /* 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))) {
            if (SCptr) {
                  unsigned int phase = SCptr->SCp.phase;

                  if (phase & in_phases_mask) {
                        what_next = esp_work_bus(esp);
                  } else if (phase & in_slct_mask) {
                        what_next = esp_select_complete(esp);
                  } 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 == NULL) {
                  /* This is ok. */
                  what_next = esp_do_reconnect(esp);
            } 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);
            } 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);
            } else {
                  /* state is completely lost ;-( */
                  ESPLOG(("esp%d: interrupt engine loses state, resetting bus\n",
                        esp->esp_id));
                  what_next = do_reset_bus;
            }
      }
}

/* Service only the ESP described by dev_id. */
static irqreturn_t esp_intr(int irq, void *dev_id, struct pt_regs *pregs)
{
      struct esp *esp = dev_id;
      unsigned long flags;

      spin_lock_irqsave(esp->ehost->host_lock, flags);
      if (ESP_IRQ_P(esp->dregs)) {
            ESP_INTSOFF(esp->dregs);

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

            ESP_INTSON(esp->dregs);
      }
      spin_unlock_irqrestore(esp->ehost->host_lock, flags);

      return IRQ_HANDLED;
}

static 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;
}

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

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

static struct scsi_host_template esp_template = {
      .module                 = THIS_MODULE,
      .name             = "esp",
      .info             = esp_info,
      .slave_alloc            = esp_slave_alloc,
      .slave_destroy          = esp_slave_destroy,
      .queuecommand           = esp_queue,
      .eh_abort_handler = esp_abort,
      .eh_bus_reset_handler   = esp_reset,
      .can_queue        = 7,
      .this_id          = 7,
      .sg_tablesize           = SG_ALL,
      .cmd_per_lun            = 1,
      .use_clustering         = ENABLE_CLUSTERING,
      .proc_name        = "esp",
      .proc_info        = esp_proc_info,
};

#ifndef CONFIG_SUN4
static struct of_device_id esp_match[] = {
      {
            .name = "SUNW,esp",
            .data = &esp_template,
      },
      {
            .name = "SUNW,fas",
            .data = &esp_template,
      },
      {
            .name = "esp",
            .data = &esp_template,
      },
      {},
};
MODULE_DEVICE_TABLE(of, esp_match);

static struct of_platform_driver esp_sbus_driver = {
      .name       = "esp",
      .match_table      = esp_match,
      .probe            = esp_sbus_probe,
      .remove           = __devexit_p(esp_sbus_remove),
};
#endif

static int __init esp_init(void)
{
#ifdef CONFIG_SUN4
      return esp_sun4_probe(&esp_template);
#else
      return of_register_driver(&esp_sbus_driver, &sbus_bus_type);
#endif
}

static void __exit esp_exit(void)
{
#ifdef CONFIG_SUN4
      esp_sun4_remove();
#else
      of_unregister_driver(&esp_sbus_driver);
#endif
}

MODULE_DESCRIPTION("ESP Sun SCSI driver");
MODULE_AUTHOR("David S. Miller (davem@davemloft.net)");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);

module_init(esp_init);
module_exit(esp_exit);

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