[PATCH] EDAC: atomic scrub operations

[linux-2.6] / drivers / scsi / esp.c

/* $Id: esp.c,v 1.101 2002/01/15 06:48:55 davem Exp $
 * esp.c:  EnhancedScsiProcessor Sun SCSI driver code.
 *
 * Copyright (C) 1995, 1998 David S. Miller (davem@caip.rutgers.edu)
 */

/* TODO:
 *
 * 1) Maybe disable parity checking in config register one for SCSI1
 *    targets.  (Gilmore says parity error on the SBus can lock up
 *    old sun4c's)
 * 2) Add support for DMA2 pipelining.
 * 3) Add tagged queueing.
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/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
};

/* The master ring of all esp hosts we are managing in this driver. */
static struct esp *espchain;
static DEFINE_SPINLOCK(espchain_lock);
static int esps_running = 0;

/* 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 void esp_chain_add(struct esp *esp)
{
        spin_lock_irq(&espchain_lock);
        if (espchain) {
                struct esp *elink = espchain;
                while (elink->next)
                        elink = elink->next;
                elink->next = esp;
        } else {
                espchain = esp;
        }
        esp->next = NULL;
        spin_unlock_irq(&espchain_lock);
}

static void esp_chain_del(struct esp *esp)
{
        spin_lock_irq(&espchain_lock);
        if (espchain == esp) {
                espchain = esp->next;
        } else {
                struct esp *elink = espchain;
                while (elink->next != esp)
                        elink = elink->next;
                elink->next = esp->next;
        }
        esp->next = NULL;
        spin_unlock_irq(&espchain_lock);
}

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,
                        SA_SHIRQ, "ESP SCSI", esp)) {
                printk("esp%d: Cannot acquire irq line\n",
                       esp->esp_id);
                return -1;
        }

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

        return 0;
}

static void __init esp_get_scsi_id(struct esp *esp)
{
        struct sbus_dev *sdev = esp->sdev;

        esp->scsi_id = prom_getintdefault(esp->prom_node,
                                          "initiator-id",
                                          -1);
        if (esp->scsi_id == -1)
                esp->scsi_id = prom_getintdefault(esp->prom_node,
                                                  "scsi-initiator-id",
                                                  -1);
        if (esp->scsi_id == -1)
                esp->scsi_id = (sdev->bus == NULL) ? 7 :
                        prom_getintdefault(sdev->bus->prom_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 sbus_dev *esp_dev,
                                 struct sbus_dev *espdma, struct sbus_bus *sbus,
                                 int id, int hme)
{
        struct Scsi_Host *esp_host = scsi_register(tpnt, sizeof(struct esp));
        struct esp *esp;
        
        if (!esp_host) {
                printk("ESP: Cannot register SCSI host\n");
                return -1;
        }
        if (hme)
                esp_host->max_id = 16;
        esp = (struct esp *) esp_host->hostdata;
        esp->ehost = esp_host;
        esp->sdev = esp_dev;
        esp->esp_id = id;
        esp->prom_node = esp_dev->prom_node;
        prom_getstring(esp->prom_node, "name", esp->prom_name,
                       sizeof(esp->prom_name));

        esp_chain_add(esp);
        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);

        return 0;

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:
        esp_chain_del(esp);
        scsi_unregister(esp_host);
        return -1;
}

/* Detecting ESP chips on the machine.  This is the simple and easy
 * version.
 */

#ifdef CONFIG_SUN4

#include <asm/sun4paddr.h>

static int __init esp_detect(struct scsi_host_template *tpnt)
{
        static struct sbus_dev esp_dev;
        int esps_in_use = 0;

        espchain = NULL;

        if (sun4_esp_physaddr) {
                memset (&esp_dev, 0, sizeof(esp_dev));
                esp_dev.reg_addrs[0].phys_addr = sun4_esp_physaddr;
                esp_dev.irqs[0] = 4;
                esp_dev.resource[0].start = sun4_esp_physaddr;
                esp_dev.resource[0].end = sun4_esp_physaddr + ESP_REG_SIZE - 1;
                esp_dev.resource[0].flags = IORESOURCE_IO;

                if (!detect_one_esp(tpnt, &esp_dev, NULL, NULL, 0, 0))
                        esps_in_use++;
                printk("ESP: Total of 1 ESP hosts found, %d actually in use.\n", esps_in_use);
                esps_running =  esps_in_use;
        }
        return esps_in_use;
}

#else /* !CONFIG_SUN4 */

static int __init esp_detect(struct scsi_host_template *tpnt)
{
        struct sbus_bus *sbus;
        struct sbus_dev *esp_dev, *sbdev_iter;
        int nesps = 0, esps_in_use = 0;

        espchain = 0;
        if (!sbus_root) {
#ifdef CONFIG_PCI
                return 0;
#else
                panic("No SBUS in esp_detect()");
#endif
        }
        for_each_sbus(sbus) {
                for_each_sbusdev(sbdev_iter, sbus) {
                        struct sbus_dev *espdma = NULL;
                        int hme = 0;

                        /* Is it an esp sbus device? */
                        esp_dev = sbdev_iter;
                        if (strcmp(esp_dev->prom_name, "esp") &&
                            strcmp(esp_dev->prom_name, "SUNW,esp")) {
                                if (!strcmp(esp_dev->prom_name, "SUNW,fas")) {
                                        hme = 1;
                                        espdma = esp_dev;
                                } else {
                                        if (!esp_dev->child ||
                                            (strcmp(esp_dev->prom_name, "espdma") &&
                                             strcmp(esp_dev->prom_name, "dma")))
                                                continue; /* nope... */
                                        espdma = esp_dev;
                                        esp_dev = esp_dev->child;
                                        if (strcmp(esp_dev->prom_name, "esp") &&
                                            strcmp(esp_dev->prom_name, "SUNW,esp"))
                                                continue; /* how can this happen? */
                                }
                        }
                        
                        if (detect_one_esp(tpnt, esp_dev, espdma, sbus, nesps++, hme) < 0)
                                continue;
                                
                        esps_in_use++;
                } /* for each sbusdev */
        } /* for each sbus */
        printk("ESP: Total of %d ESP hosts found, %d actually in use.\n", nesps,
               esps_in_use);
        esps_running = esps_in_use;
        return esps_in_use;
}

#endif /* !CONFIG_SUN4 */

/*
 */
static int esp_release(struct Scsi_Host *host)
{
        struct esp *esp = (struct esp *) host->hostdata;

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

        free_irq(esp->ehost->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;
        esp_chain_del(esp);

        return 0;
}

/* 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;

        if (inout)
                return -EINVAL; /* not yet */

        for_each_esp(esp) {
                if (esp->ehost == host)
                        break;
        }
        if (!esp)
                return -EINVAL;

        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->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->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;

        (void) esp_do_resetbus(esp);

        spin_unlock_irq(esp->ehost->host_lock);

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

        spin_lock_irq(esp->ehost->host_lock);

        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 cmd1 = sp->cmnd[0];
        u8 cmd2 = sp->data_cmnd[0];

        /* These cases are for spinning up a disk and
         * waiting for that spinup to complete.
         */
        if (cmd1 == START_STOP ||
            cmd2 == START_STOP)
                return 0;

        if (cmd1 == TEST_UNIT_READY ||
            cmd2 == 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 (cmd1 == MODE_SENSE ||
                    cmd2 == 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 driver_template = {
        .proc_name              = "esp",
        .proc_info              = esp_proc_info,
        .name                   = "Sun ESP 100/100a/200",
        .detect                 = esp_detect,
        .slave_alloc            = esp_slave_alloc,
        .slave_destroy          = esp_slave_destroy,
        .release                = esp_release,
        .info                   = esp_info,
        .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,
};

#include "scsi_module.c"

MODULE_DESCRIPTION("EnhancedScsiProcessor Sun SCSI driver");
MODULE_AUTHOR("David S. Miller (davem@redhat.com)");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);