/*
 * Device driver for the SYMBIOS/LSILOGIC 53C8XX and 53C1010 family 
 * of PCI-SCSI IO processors.
 *
 * Copyright (C) 1999-2001  Gerard Roudier <groudier@free.fr>
 * Copyright (c) 2003-2005  Matthew Wilcox <matthew@wil.cx>
 *
 * This driver is derived from the Linux sym53c8xx driver.
 * Copyright (C) 1998-2000  Gerard Roudier
 *
 * The sym53c8xx driver is derived from the ncr53c8xx driver that had been 
 * a port of the FreeBSD ncr driver to Linux-1.2.13.
 *
 * The original ncr driver has been written for 386bsd and FreeBSD by
 *         Wolfgang Stanglmeier        <wolf@cologne.de>
 *         Stefan Esser                <se@mi.Uni-Koeln.de>
 * Copyright (C) 1994  Wolfgang Stanglmeier
 *
 * Other major contributions:
 *
 * NVRAM detection and reading.
 * Copyright (C) 1997 Richard Waltham <dormouse@farsrobt.demon.co.uk>
 *
 *-----------------------------------------------------------------------------
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/slab.h>
#include <asm/param.h>          /* for timeouts in units of HZ */

#include "sym_glue.h"
#include "sym_nvram.h"

#if 0
#define SYM_DEBUG_GENERIC_SUPPORT
#endif

/*
 *  Needed function prototypes.
 */
static void sym_int_ma (struct sym_hcb *np);
static void sym_int_sir(struct sym_hcb *);
static struct sym_ccb *sym_alloc_ccb(struct sym_hcb *np);
static struct sym_ccb *sym_ccb_from_dsa(struct sym_hcb *np, u32 dsa);
static void sym_alloc_lcb_tags (struct sym_hcb *np, u_char tn, u_char ln);
static void sym_complete_error (struct sym_hcb *np, struct sym_ccb *cp);
static void sym_complete_ok (struct sym_hcb *np, struct sym_ccb *cp);
static int sym_compute_residual(struct sym_hcb *np, struct sym_ccb *cp);

/*
 *  Print a buffer in hexadecimal format with a ".\n" at end.
 */
static void sym_printl_hex(u_char *p, int n)
{
        while (n-- > 0)
                printf (" %x", *p++);
        printf (".\n");
}

static void sym_print_msg(struct sym_ccb *cp, char *label, u_char *msg)
{
        sym_print_addr(cp->cmd, "%s: ", label);

        spi_print_msg(msg);
        printf("\n");
}

static void sym_print_nego_msg(struct sym_hcb *np, int target, char *label, u_char *msg)
{
        struct sym_tcb *tp = &np->target[target];
        dev_info(&tp->starget->dev, "%s: ", label);

        spi_print_msg(msg);
        printf("\n");
}

/*
 *  Print something that tells about extended errors.
 */
void sym_print_xerr(struct scsi_cmnd *cmd, int x_status)
{
        if (x_status & XE_PARITY_ERR) {
                sym_print_addr(cmd, "unrecovered SCSI parity error.\n");
        }
        if (x_status & XE_EXTRA_DATA) {
                sym_print_addr(cmd, "extraneous data discarded.\n");
        }
        if (x_status & XE_BAD_PHASE) {
                sym_print_addr(cmd, "illegal scsi phase (4/5).\n");
        }
        if (x_status & XE_SODL_UNRUN) {
                sym_print_addr(cmd, "ODD transfer in DATA OUT phase.\n");
        }
        if (x_status & XE_SWIDE_OVRUN) {
                sym_print_addr(cmd, "ODD transfer in DATA IN phase.\n");
        }
}

/*
 *  Return a string for SCSI BUS mode.
 */
static char *sym_scsi_bus_mode(int mode)
{
        switch(mode) {
        case SMODE_HVD: return "HVD";
        case SMODE_SE:  return "SE";
        case SMODE_LVD: return "LVD";
        }
        return "??";
}

/*
 *  Soft reset the chip.
 *
 *  Raising SRST when the chip is running may cause 
 *  problems on dual function chips (see below).
 *  On the other hand, LVD devices need some delay 
 *  to settle and report actual BUS mode in STEST4.
 */
static void sym_chip_reset (struct sym_hcb *np)
{
        OUTB(np, nc_istat, SRST);
        INB(np, nc_mbox1);
        udelay(10);
        OUTB(np, nc_istat, 0);
        INB(np, nc_mbox1);
        udelay(2000);   /* For BUS MODE to settle */
}

/*
 *  Really soft reset the chip.:)
 *
 *  Some 896 and 876 chip revisions may hang-up if we set 
 *  the SRST (soft reset) bit at the wrong time when SCRIPTS 
 *  are running.
 *  So, we need to abort the current operation prior to 
 *  soft resetting the chip.
 */
static void sym_soft_reset (struct sym_hcb *np)
{
        u_char istat = 0;
        int i;

        if (!(np->features & FE_ISTAT1) || !(INB(np, nc_istat1) & SCRUN))
                goto do_chip_reset;

        OUTB(np, nc_istat, CABRT);
        for (i = 100000 ; i ; --i) {
                istat = INB(np, nc_istat);
                if (istat & SIP) {
                        INW(np, nc_sist);
                }
                else if (istat & DIP) {
                        if (INB(np, nc_dstat) & ABRT)
                                break;
                }
                udelay(5);
        }
        OUTB(np, nc_istat, 0);
        if (!i)
                printf("%s: unable to abort current chip operation, "
                       "ISTAT=0x%02x.\n", sym_name(np), istat);
do_chip_reset:
        sym_chip_reset(np);
}

/*
 *  Start reset process.
 *
 *  The interrupt handler will reinitialize the chip.
 */
static void sym_start_reset(struct sym_hcb *np)
{
        sym_reset_scsi_bus(np, 1);
}
 
int sym_reset_scsi_bus(struct sym_hcb *np, int enab_int)
{
        u32 term;
        int retv = 0;

        sym_soft_reset(np);     /* Soft reset the chip */
        if (enab_int)
                OUTW(np, nc_sien, RST);
        /*
         *  Enable Tolerant, reset IRQD if present and 
         *  properly set IRQ mode, prior to resetting the bus.
         */
        OUTB(np, nc_stest3, TE);
        OUTB(np, nc_dcntl, (np->rv_dcntl & IRQM));
        OUTB(np, nc_scntl1, CRST);
        INB(np, nc_mbox1);
        udelay(200);

        if (!SYM_SETUP_SCSI_BUS_CHECK)
                goto out;
        /*
         *  Check for no terminators or SCSI bus shorts to ground.
         *  Read SCSI data bus, data parity bits and control signals.
         *  We are expecting RESET to be TRUE and other signals to be 
         *  FALSE.
         */
        term =  INB(np, nc_sstat0);
        term =  ((term & 2) << 7) + ((term & 1) << 17); /* rst sdp0 */
        term |= ((INB(np, nc_sstat2) & 0x01) << 26) |   /* sdp1     */
                ((INW(np, nc_sbdl) & 0xff)   << 9)  |   /* d7-0     */
                ((INW(np, nc_sbdl) & 0xff00) << 10) |   /* d15-8    */
                INB(np, nc_sbcl);       /* req ack bsy sel atn msg cd io    */

        if (!np->maxwide)
                term &= 0x3ffff;

        if (term != (2<<7)) {
                printf("%s: suspicious SCSI data while resetting the BUS.\n",
                        sym_name(np));
                printf("%s: %sdp0,d7-0,rst,req,ack,bsy,sel,atn,msg,c/d,i/o = "
                        "0x%lx, expecting 0x%lx\n",
                        sym_name(np),
                        (np->features & FE_WIDE) ? "dp1,d15-8," : "",
                        (u_long)term, (u_long)(2<<7));
                if (SYM_SETUP_SCSI_BUS_CHECK == 1)
                        retv = 1;
        }
out:
        OUTB(np, nc_scntl1, 0);
        return retv;
}

/*
 *  Select SCSI clock frequency
 */
static void sym_selectclock(struct sym_hcb *np, u_char scntl3)
{
        /*
         *  If multiplier not present or not selected, leave here.
         */
        if (np->multiplier <= 1) {
                OUTB(np, nc_scntl3, scntl3);
                return;
        }

        if (sym_verbose >= 2)
                printf ("%s: enabling clock multiplier\n", sym_name(np));

        OUTB(np, nc_stest1, DBLEN);        /* Enable clock multiplier */
        /*
         *  Wait for the LCKFRQ bit to be set if supported by the chip.
         *  Otherwise wait 50 micro-seconds (at least).
         */
        if (np->features & FE_LCKFRQ) {
                int i = 20;
                while (!(INB(np, nc_stest4) & LCKFRQ) && --i > 0)
                        udelay(20);
                if (!i)
                        printf("%s: the chip cannot lock the frequency\n",
                                sym_name(np));
        } else {
                INB(np, nc_mbox1);
                udelay(50+10);
        }
        OUTB(np, nc_stest3, HSC);               /* Halt the scsi clock  */
        OUTB(np, nc_scntl3, scntl3);
        OUTB(np, nc_stest1, (DBLEN|DBLSEL));/* Select clock multiplier  */
        OUTB(np, nc_stest3, 0x00);              /* Restart scsi clock   */
}


/*
 *  Determine the chip's clock frequency.
 *
 *  This is essential for the negotiation of the synchronous 
 *  transfer rate.
 *
 *  Note: we have to return the correct value.
 *  THERE IS NO SAFE DEFAULT VALUE.
 *
 *  Most NCR/SYMBIOS boards are delivered with a 40 Mhz clock.
 *  53C860 and 53C875 rev. 1 support fast20 transfers but 
 *  do not have a clock doubler and so are provided with a 
 *  80 MHz clock. All other fast20 boards incorporate a doubler 
 *  and so should be delivered with a 40 MHz clock.
 *  The recent fast40 chips (895/896/895A/1010) use a 40 Mhz base 
 *  clock and provide a clock quadrupler (160 Mhz).
 */

/*
 *  calculate SCSI clock frequency (in KHz)
 */
static unsigned getfreq (struct sym_hcb *np, int gen)
{
        unsigned int ms = 0;
        unsigned int f;

        /*
         * Measure GEN timer delay in order 
         * to calculate SCSI clock frequency
         *
         * This code will never execute too
         * many loop iterations (if DELAY is 
         * reasonably correct). It could get
         * too low a delay (too high a freq.)
         * if the CPU is slow executing the 
         * loop for some reason (an NMI, for
         * example). For this reason we will
         * if multiple measurements are to be 
         * performed trust the higher delay 
         * (lower frequency returned).
         */
        OUTW(np, nc_sien, 0);   /* mask all scsi interrupts */
        INW(np, nc_sist);       /* clear pending scsi interrupt */
        OUTB(np, nc_dien, 0);   /* mask all dma interrupts */
        INW(np, nc_sist);       /* another one, just to be sure :) */
        /*
         * The C1010-33 core does not report GEN in SIST,
         * if this interrupt is masked in SIEN.
         * I don't know yet if the C1010-66 behaves the same way.
         */
        if (np->features & FE_C10) {
                OUTW(np, nc_sien, GEN);
                OUTB(np, nc_istat1, SIRQD);
        }
        OUTB(np, nc_scntl3, 4);    /* set pre-scaler to divide by 3 */
        OUTB(np, nc_stime1, 0);    /* disable general purpose timer */
        OUTB(np, nc_stime1, gen);  /* set to nominal delay of 1<<gen * 125us */
        while (!(INW(np, nc_sist) & GEN) && ms++ < 100000)
                udelay(1000/4);    /* count in 1/4 of ms */
        OUTB(np, nc_stime1, 0);    /* disable general purpose timer */
        /*
         * Undo C1010-33 specific settings.
         */
        if (np->features & FE_C10) {
                OUTW(np, nc_sien, 0);
                OUTB(np, nc_istat1, 0);
        }
        /*
         * set prescaler to divide by whatever 0 means
         * 0 ought to choose divide by 2, but appears
         * to set divide by 3.5 mode in my 53c810 ...
         */
        OUTB(np, nc_scntl3, 0);

        /*
         * adjust for prescaler, and convert into KHz 
         */
        f = ms ? ((1 << gen) * (4340*4)) / ms : 0;

        /*
         * The C1010-33 result is biased by a factor 
         * of 2/3 compared to earlier chips.
         */
        if (np->features & FE_C10)
                f = (f * 2) / 3;

        if (sym_verbose >= 2)
                printf ("%s: Delay (GEN=%d): %u msec, %u KHz\n",
                        sym_name(np), gen, ms/4, f);

        return f;
}

static unsigned sym_getfreq (struct sym_hcb *np)
{
        u_int f1, f2;
        int gen = 8;

        getfreq (np, gen);      /* throw away first result */
        f1 = getfreq (np, gen);
        f2 = getfreq (np, gen);
        if (f1 > f2) f1 = f2;           /* trust lower result   */
        return f1;
}

/*
 *  Get/probe chip SCSI clock frequency
 */
static void sym_getclock (struct sym_hcb *np, int mult)
{
        unsigned char scntl3 = np->sv_scntl3;
        unsigned char stest1 = np->sv_stest1;
        unsigned f1;

        np->multiplier = 1;
        f1 = 40000;
        /*
         *  True with 875/895/896/895A with clock multiplier selected
         */
        if (mult > 1 && (stest1 & (DBLEN+DBLSEL)) == DBLEN+DBLSEL) {
                if (sym_verbose >= 2)
                        printf ("%s: clock multiplier found\n", sym_name(np));
                np->multiplier = mult;
        }

        /*
         *  If multiplier not found or scntl3 not 7,5,3,
         *  reset chip and get frequency from general purpose timer.
         *  Otherwise trust scntl3 BIOS setting.
         */
        if (np->multiplier != mult || (scntl3 & 7) < 3 || !(scntl3 & 1)) {
                OUTB(np, nc_stest1, 0);         /* make sure doubler is OFF */
                f1 = sym_getfreq (np);

                if (sym_verbose)
                        printf ("%s: chip clock is %uKHz\n", sym_name(np), f1);

                if      (f1 <   45000)          f1 =  40000;
                else if (f1 <   55000)          f1 =  50000;
                else                            f1 =  80000;

                if (f1 < 80000 && mult > 1) {
                        if (sym_verbose >= 2)
                                printf ("%s: clock multiplier assumed\n",
                                        sym_name(np));
                        np->multiplier  = mult;
                }
        } else {
                if      ((scntl3 & 7) == 3)     f1 =  40000;
                else if ((scntl3 & 7) == 5)     f1 =  80000;
                else                            f1 = 160000;

                f1 /= np->multiplier;
        }

        /*
         *  Compute controller synchronous parameters.
         */
        f1              *= np->multiplier;
        np->clock_khz   = f1;
}

/*
 *  Get/probe PCI clock frequency
 */
static int sym_getpciclock (struct sym_hcb *np)
{
        int f = 0;

        /*
         *  For now, we only need to know about the actual 
         *  PCI BUS clock frequency for C1010-66 chips.
         */
#if 1
        if (np->features & FE_66MHZ) {
#else
        if (1) {
#endif
                OUTB(np, nc_stest1, SCLK); /* Use the PCI clock as SCSI clock */
                f = sym_getfreq(np);
                OUTB(np, nc_stest1, 0);
        }
        np->pciclk_khz = f;

        return f;
}

/*
 *  SYMBIOS chip clock divisor table.
 *
 *  Divisors are multiplied by 10,000,000 in order to make 
 *  calculations more simple.
 */
#define _5M 5000000
static const u32 div_10M[] = {2*_5M, 3*_5M, 4*_5M, 6*_5M, 8*_5M, 12*_5M, 16*_5M};

/*
 *  Get clock factor and sync divisor for a given 
 *  synchronous factor period.
 */
static int 
sym_getsync(struct sym_hcb *np, u_char dt, u_char sfac, u_char *divp, u_char *fakp)
{
        u32     clk = np->clock_khz;    /* SCSI clock frequency in kHz  */
        int     div = np->clock_divn;   /* Number of divisors supported */
        u32     fak;                    /* Sync factor in sxfer         */
        u32     per;                    /* Period in tenths of ns       */
        u32     kpc;                    /* (per * clk)                  */
        int     ret;

        /*
         *  Compute the synchronous period in tenths of nano-seconds
         */
        if (dt && sfac <= 9)    per = 125;
        else if (sfac <= 10)    per = 250;
        else if (sfac == 11)    per = 303;
        else if (sfac == 12)    per = 500;
        else                    per = 40 * sfac;
        ret = per;

        kpc = per * clk;
        if (dt)
                kpc <<= 1;

        /*
         *  For earliest C10 revision 0, we cannot use extra 
         *  clocks for the setting of the SCSI clocking.
         *  Note that this limits the lowest sync data transfer 
         *  to 5 Mega-transfers per second and may result in
         *  using higher clock divisors.
         */
#if 1
        if ((np->features & (FE_C10|FE_U3EN)) == FE_C10) {
                /*
                 *  Look for the lowest clock divisor that allows an 
                 *  output speed not faster than the period.
                 */
                while (div > 0) {
                        --div;
                        if (kpc > (div_10M[div] << 2)) {
                                ++div;
                                break;
                        }
                }
                fak = 0;                        /* No extra clocks */
                if (div == np->clock_divn) {    /* Are we too fast ? */
                        ret = -1;
                }
                *divp = div;
                *fakp = fak;
                return ret;
        }
#endif

        /*
         *  Look for the greatest clock divisor that allows an 
         *  input speed faster than the period.
         */
        while (div-- > 0)
                if (kpc >= (div_10M[div] << 2)) break;

        /*
         *  Calculate the lowest clock factor that allows an output 
         *  speed not faster than the period, and the max output speed.
         *  If fak >= 1 we will set both XCLKH_ST and XCLKH_DT.
         *  If fak >= 2 we will also set XCLKS_ST and XCLKS_DT.
         */
        if (dt) {
                fak = (kpc - 1) / (div_10M[div] << 1) + 1 - 2;
                /* ret = ((2+fak)*div_10M[div])/np->clock_khz; */
        } else {
                fak = (kpc - 1) / div_10M[div] + 1 - 4;
                /* ret = ((4+fak)*div_10M[div])/np->clock_khz; */
        }

        /*
         *  Check against our hardware limits, or bugs :).
         */
        if (fak > 2) {
                fak = 2;
                ret = -1;
        }

        /*
         *  Compute and return sync parameters.
         */
        *divp = div;
        *fakp = fak;

        return ret;
}

/*
 *  SYMBIOS chips allow burst lengths of 2, 4, 8, 16, 32, 64,
 *  128 transfers. All chips support at least 16 transfers 
 *  bursts. The 825A, 875 and 895 chips support bursts of up 
 *  to 128 transfers and the 895A and 896 support bursts of up
 *  to 64 transfers. All other chips support up to 16 
 *  transfers bursts.
 *
 *  For PCI 32 bit data transfers each transfer is a DWORD.
 *  It is a QUADWORD (8 bytes) for PCI 64 bit data transfers.
 *
 *  We use log base 2 (burst length) as internal code, with 
 *  value 0 meaning "burst disabled".
 */

/*
 *  Burst length from burst code.
 */
#define burst_length(bc) (!(bc))? 0 : 1 << (bc)

/*
 *  Burst code from io register bits.
 */
#define burst_code(dmode, ctest4, ctest5) \
        (ctest4) & 0x80? 0 : (((dmode) & 0xc0) >> 6) + ((ctest5) & 0x04) + 1

/*
 *  Set initial io register bits from burst code.
 */
static inline void sym_init_burst(struct sym_hcb *np, u_char bc)
{
        np->rv_ctest4   &= ~0x80;
        np->rv_dmode    &= ~(0x3 << 6);
        np->rv_ctest5   &= ~0x4;

        if (!bc) {
                np->rv_ctest4   |= 0x80;
        }
        else {
                --bc;
                np->rv_dmode    |= ((bc & 0x3) << 6);
                np->rv_ctest5   |= (bc & 0x4);
        }
}

/*
 *  Save initial settings of some IO registers.
 *  Assumed to have been set by BIOS.
 *  We cannot reset the chip prior to reading the 
 *  IO registers, since informations will be lost.
 *  Since the SCRIPTS processor may be running, this 
 *  is not safe on paper, but it seems to work quite 
 *  well. :)
 */
static void sym_save_initial_setting (struct sym_hcb *np)
{
        np->sv_scntl0   = INB(np, nc_scntl0) & 0x0a;
        np->sv_scntl3   = INB(np, nc_scntl3) & 0x07;
        np->sv_dmode    = INB(np, nc_dmode)  & 0xce;
        np->sv_dcntl    = INB(np, nc_dcntl)  & 0xa8;
        np->sv_ctest3   = INB(np, nc_ctest3) & 0x01;
        np->sv_ctest4   = INB(np, nc_ctest4) & 0x80;
        np->sv_gpcntl   = INB(np, nc_gpcntl);
        np->sv_stest1   = INB(np, nc_stest1);
        np->sv_stest2   = INB(np, nc_stest2) & 0x20;
        np->sv_stest4   = INB(np, nc_stest4);
        if (np->features & FE_C10) {    /* Always large DMA fifo + ultra3 */
                np->sv_scntl4   = INB(np, nc_scntl4);
                np->sv_ctest5   = INB(np, nc_ctest5) & 0x04;
        }
        else
                np->sv_ctest5   = INB(np, nc_ctest5) & 0x24;
}

/*
 *  Set SCSI BUS mode.
 *  - LVD capable chips (895/895A/896/1010) report the current BUS mode
 *    through the STEST4 IO register.
 *  - For previous generation chips (825/825A/875), the user has to tell us
 *    how to check against HVD, since a 100% safe algorithm is not possible.
 */
static void sym_set_bus_mode(struct sym_hcb *np, struct sym_nvram *nvram)
{
        if (np->scsi_mode)
                return;

        np->scsi_mode = SMODE_SE;
        if (np->features & (FE_ULTRA2|FE_ULTRA3))
                np->scsi_mode = (np->sv_stest4 & SMODE);
        else if (np->features & FE_DIFF) {
                if (SYM_SETUP_SCSI_DIFF == 1) {
                        if (np->sv_scntl3) {
                                if (np->sv_stest2 & 0x20)
                                        np->scsi_mode = SMODE_HVD;
                        } else if (nvram->type == SYM_SYMBIOS_NVRAM) {
                                if (!(INB(np, nc_gpreg) & 0x08))
                                        np->scsi_mode = SMODE_HVD;
                        }
                } else if (SYM_SETUP_SCSI_DIFF == 2)
                        np->scsi_mode = SMODE_HVD;
        }
        if (np->scsi_mode == SMODE_HVD)
                np->rv_stest2 |= 0x20;
}

/*
 *  Prepare io register values used by sym_start_up() 
 *  according to selected and supported features.
 */
static int sym_prepare_setting(struct Scsi_Host *shost, struct sym_hcb *np, struct sym_nvram *nvram)
{
        struct sym_data *sym_data = shost_priv(shost);
        struct pci_dev *pdev = sym_data->pdev;
        u_char  burst_max;
        u32     period;
        int i;

        np->maxwide = (np->features & FE_WIDE) ? 1 : 0;

        /*
         *  Guess the frequency of the chip's clock.
         */
        if      (np->features & (FE_ULTRA3 | FE_ULTRA2))
                np->clock_khz = 160000;
        else if (np->features & FE_ULTRA)
                np->clock_khz = 80000;
        else
                np->clock_khz = 40000;

        /*
         *  Get the clock multiplier factor.
         */
        if      (np->features & FE_QUAD)
                np->multiplier  = 4;
        else if (np->features & FE_DBLR)
                np->multiplier  = 2;
        else
                np->multiplier  = 1;

        /*
         *  Measure SCSI clock frequency for chips 
         *  it may vary from assumed one.
         */
        if (np->features & FE_VARCLK)
                sym_getclock(np, np->multiplier);

        /*
         * Divisor to be used for async (timer pre-scaler).
         */
        i = np->clock_divn - 1;
        while (--i >= 0) {
                if (10ul * SYM_CONF_MIN_ASYNC * np->clock_khz > div_10M[i]) {
                        ++i;
                        break;
                }
        }
        np->rv_scntl3 = i+1;

        /*
         * The C1010 uses hardwired divisors for async.
         * So, we just throw away, the async. divisor.:-)
         */
        if (np->features & FE_C10)
                np->rv_scntl3 = 0;

        /*
         * Minimum synchronous period factor supported by the chip.
         * Btw, 'period' is in tenths of nanoseconds.
         */
        period = (4 * div_10M[0] + np->clock_khz - 1) / np->clock_khz;

        if      (period <= 250)         np->minsync = 10;
        else if (period <= 303)         np->minsync = 11;
        else if (period <= 500)         np->minsync = 12;
        else                            np->minsync = (period + 40 - 1) / 40;

        /*
         * Check against chip SCSI standard support (SCSI-2,ULTRA,ULTRA2).
         */
        if      (np->minsync < 25 &&
                 !(np->features & (FE_ULTRA|FE_ULTRA2|FE_ULTRA3)))
                np->minsync = 25;
        else if (np->minsync < 12 &&
                 !(np->features & (FE_ULTRA2|FE_ULTRA3)))
                np->minsync = 12;

        /*
         * Maximum synchronous period factor supported by the chip.
         */
        period = (11 * div_10M[np->clock_divn - 1]) / (4 * np->clock_khz);
        np->maxsync = period > 2540 ? 254 : period / 10;

        /*
         * If chip is a C1010, guess the sync limits in DT mode.
         */
        if ((np->features & (FE_C10|FE_ULTRA3)) == (FE_C10|FE_ULTRA3)) {
                if (np->clock_khz == 160000) {
                        np->minsync_dt = 9;
                        np->maxsync_dt = 50;
                        np->maxoffs_dt = nvram->type ? 62 : 31;
                }
        }
        
        /*
         *  64 bit addressing  (895A/896/1010) ?
         */
        if (np->features & FE_DAC) {
                if (!use_dac(np))
                        np->rv_ccntl1 |= (DDAC);
                else if (SYM_CONF_DMA_ADDRESSING_MODE == 1)
                        np->rv_ccntl1 |= (XTIMOD | EXTIBMV);
                else if (SYM_CONF_DMA_ADDRESSING_MODE == 2)
                        np->rv_ccntl1 |= (0 | EXTIBMV);
        }

        /*
         *  Phase mismatch handled by SCRIPTS (895A/896/1010) ?
         */
        if (np->features & FE_NOPM)
                np->rv_ccntl0   |= (ENPMJ);

        /*
         *  C1010-33 Errata: Part Number:609-039638 (rev. 1) is fixed.
         *  In dual channel mode, contention occurs if internal cycles
         *  are used. Disable internal cycles.
         */
        if (pdev->device == PCI_DEVICE_ID_LSI_53C1010_33 &&
            pdev->revision < 0x1)
                np->rv_ccntl0   |=  DILS;

        /*
         *  Select burst length (dwords)
         */
        burst_max       = SYM_SETUP_BURST_ORDER;
        if (burst_max == 255)
                burst_max = burst_code(np->sv_dmode, np->sv_ctest4,
                                       np->sv_ctest5);
        if (burst_max > 7)
                burst_max = 7;
        if (burst_max > np->maxburst)
                burst_max = np->maxburst;

        /*
         *  DEL 352 - 53C810 Rev x11 - Part Number 609-0392140 - ITEM 2.
         *  This chip and the 860 Rev 1 may wrongly use PCI cache line 
         *  based transactions on LOAD/STORE instructions. So we have 
         *  to prevent these chips from using such PCI transactions in 
         *  this driver. The generic ncr driver that does not use 
         *  LOAD/STORE instructions does not need this work-around.
         */
        if ((pdev->device == PCI_DEVICE_ID_NCR_53C810 &&
             pdev->revision >= 0x10 && pdev->revision <= 0x11) ||
            (pdev->device == PCI_DEVICE_ID_NCR_53C860 &&
             pdev->revision <= 0x1))
                np->features &= ~(FE_WRIE|FE_ERL|FE_ERMP);

        /*
         *  Select all supported special features.
         *  If we are using on-board RAM for scripts, prefetch (PFEN) 
         *  does not help, but burst op fetch (BOF) does.
         *  Disabling PFEN makes sure BOF will be used.
         */
        if (np->features & FE_ERL)
                np->rv_dmode    |= ERL;         /* Enable Read Line */
        if (np->features & FE_BOF)
                np->rv_dmode    |= BOF;         /* Burst Opcode Fetch */
        if (np->features & FE_ERMP)
                np->rv_dmode    |= ERMP;        /* Enable Read Multiple */
#if 1
        if ((np->features & FE_PFEN) && !np->ram_ba)
#else
        if (np->features & FE_PFEN)
#endif
                np->rv_dcntl    |= PFEN;        /* Prefetch Enable */
        if (np->features & FE_CLSE)
                np->rv_dcntl    |= CLSE;        /* Cache Line Size Enable */
        if (np->features & FE_WRIE)
                np->rv_ctest3   |= WRIE;        /* Write and Invalidate */
        if (np->features & FE_DFS)
                np->rv_ctest5   |= DFS;         /* Dma Fifo Size */

        /*
         *  Select some other
         */
        np->rv_ctest4   |= MPEE; /* Master parity checking */
        np->rv_scntl0   |= 0x0a; /*  full arb., ena parity, par->ATN  */

        /*
         *  Get parity checking, host ID and verbose mode from NVRAM
         */
        np->myaddr = 255;
        np->scsi_mode = 0;
        sym_nvram_setup_host(shost, np, nvram);

        /*
         *  Get SCSI addr of host adapter (set by bios?).
         */
        if (np->myaddr == 255) {
                np->myaddr = INB(np, nc_scid) & 0x07;
                if (!np->myaddr)
                        np->myaddr = SYM_SETUP_HOST_ID;
        }

        /*
         *  Prepare initial io register bits for burst length
         */
        sym_init_burst(np, burst_max);

        sym_set_bus_mode(np, nvram);

        /*
         *  Set LED support from SCRIPTS.
         *  Ignore this feature for boards known to use a 
         *  specific GPIO wiring and for the 895A, 896 
         *  and 1010 that drive the LED directly.
         */
        if ((SYM_SETUP_SCSI_LED || 
             (nvram->type == SYM_SYMBIOS_NVRAM ||
              (nvram->type == SYM_TEKRAM_NVRAM &&
               pdev->device == PCI_DEVICE_ID_NCR_53C895))) &&
            !(np->features & FE_LEDC) && !(np->sv_gpcntl & 0x01))
                np->features |= FE_LED0;

        /*
         *  Set irq mode.
         */
        switch(SYM_SETUP_IRQ_MODE & 3) {
        case 2:
                np->rv_dcntl    |= IRQM;
                break;
        case 1:
                np->rv_dcntl    |= (np->sv_dcntl & IRQM);
                break;
        default:
                break;
        }

        /*
         *  Configure targets according to driver setup.
         *  If NVRAM present get targets setup from NVRAM.
         */
        for (i = 0 ; i < SYM_CONF_MAX_TARGET ; i++) {
                struct sym_tcb *tp = &np->target[i];

                tp->usrflags |= (SYM_DISC_ENABLED | SYM_TAGS_ENABLED);
                tp->usrtags = SYM_SETUP_MAX_TAG;
                tp->usr_width = np->maxwide;
                tp->usr_period = 9;

                sym_nvram_setup_target(tp, i, nvram);

                if (!tp->usrtags)
                        tp->usrflags &= ~SYM_TAGS_ENABLED;
        }

        /*
         *  Let user know about the settings.
         */
        printf("%s: %s, ID %d, Fast-%d, %s, %s\n", sym_name(np),
                sym_nvram_type(nvram), np->myaddr,
                (np->features & FE_ULTRA3) ? 80 : 
                (np->features & FE_ULTRA2) ? 40 : 
                (np->features & FE_ULTRA)  ? 20 : 10,
                sym_scsi_bus_mode(np->scsi_mode),
                (np->rv_scntl0 & 0xa)   ? "parity checking" : "NO parity");
        /*
         *  Tell him more on demand.
         */
        if (sym_verbose) {
                printf("%s: %s IRQ line driver%s\n",
                        sym_name(np),
                        np->rv_dcntl & IRQM ? "totem pole" : "open drain",
                        np->ram_ba ? ", using on-chip SRAM" : "");
                printf("%s: using %s firmware.\n", sym_name(np), np->fw_name);
                if (np->features & FE_NOPM)
                        printf("%s: handling phase mismatch from SCRIPTS.\n", 
                               sym_name(np));
        }
        /*
         *  And still more.
         */
        if (sym_verbose >= 2) {
                printf ("%s: initial SCNTL3/DMODE/DCNTL/CTEST3/4/5 = "
                        "(hex) %02x/%02x/%02x/%02x/%02x/%02x\n",
                        sym_name(np), np->sv_scntl3, np->sv_dmode, np->sv_dcntl,
                        np->sv_ctest3, np->sv_ctest4, np->sv_ctest5);

                printf ("%s: final   SCNTL3/DMODE/DCNTL/CTEST3/4/5 = "
                        "(hex) %02x/%02x/%02x/%02x/%02x/%02x\n",
                        sym_name(np), np->rv_scntl3, np->rv_dmode, np->rv_dcntl,
                        np->rv_ctest3, np->rv_ctest4, np->rv_ctest5);
        }

        return 0;
}

/*
 *  Test the pci bus snoop logic :-(
 *
 *  Has to be called with interrupts disabled.
 */
#ifdef CONFIG_SCSI_SYM53C8XX_MMIO
static int sym_regtest(struct sym_hcb *np)
{
        register volatile u32 data;
        /*
         *  chip registers may NOT be cached.
         *  write 0xffffffff to a read only register area,
         *  and try to read it back.
         */
        data = 0xffffffff;
        OUTL(np, nc_dstat, data);
        data = INL(np, nc_dstat);
#if 1
        if (data == 0xffffffff) {
#else
        if ((data & 0xe2f0fffd) != 0x02000080) {
#endif
                printf ("CACHE TEST FAILED: reg dstat-sstat2 readback %x.\n",
                        (unsigned) data);
                return 0x10;
        }
        return 0;
}
#else
static inline int sym_regtest(struct sym_hcb *np)
{
        return 0;

}
#endif

static int sym_snooptest(struct sym_hcb *np)
{
        u32 sym_rd, sym_wr, sym_bk, host_rd, host_wr, pc, dstat;
        int i, err;

        err = sym_regtest(np);
        if (err)
                return err;
restart_test:
        /*
         *  Enable Master Parity Checking as we intend 
         *  to enable it for normal operations.
         */
        OUTB(np, nc_ctest4, (np->rv_ctest4 & MPEE));
        /*
         *  init
         */
        pc  = SCRIPTZ_BA(np, snooptest);
        host_wr = 1;
        sym_wr  = 2;
        /*
         *  Set memory and register.
         */
        np->scratch = cpu_to_scr(host_wr);
        OUTL(np, nc_temp, sym_wr);
        /*
         *  Start script (exchange values)
         */
        OUTL(np, nc_dsa, np->hcb_ba);
        OUTL_DSP(np, pc);
        /*
         *  Wait 'til done (with timeout)
         */
        for (i=0; i<SYM_SNOOP_TIMEOUT; i++)
                if (INB(np, nc_istat) & (INTF|SIP|DIP))
                        break;
        if (i>=SYM_SNOOP_TIMEOUT) {
                printf ("CACHE TEST FAILED: timeout.\n");
                return (0x20);
        }
        /*
         *  Check for fatal DMA errors.
         */
        dstat = INB(np, nc_dstat);
#if 1   /* Band aiding for broken hardwares that fail PCI parity */
        if ((dstat & MDPE) && (np->rv_ctest4 & MPEE)) {
                printf ("%s: PCI DATA PARITY ERROR DETECTED - "
                        "DISABLING MASTER DATA PARITY CHECKING.\n",
                        sym_name(np));
                np->rv_ctest4 &= ~MPEE;
                goto restart_test;
        }
#endif
        if (dstat & (MDPE|BF|IID)) {
                printf ("CACHE TEST FAILED: DMA error (dstat=0x%02x).", dstat);
                return (0x80);
        }
        /*
         *  Save termination position.
         */
        pc = INL(np, nc_dsp);
        /*
         *  Read memory and register.
         */
        host_rd = scr_to_cpu(np->scratch);
        sym_rd  = INL(np, nc_scratcha);
        sym_bk  = INL(np, nc_temp);
        /*
         *  Check termination position.
         */
        if (pc != SCRIPTZ_BA(np, snoopend)+8) {
                printf ("CACHE TEST FAILED: script execution failed.\n");
                printf ("start=%08lx, pc=%08lx, end=%08lx\n", 
                        (u_long) SCRIPTZ_BA(np, snooptest), (u_long) pc,
                        (u_long) SCRIPTZ_BA(np, snoopend) +8);
                return (0x40);
        }
        /*
         *  Show results.
         */
        if (host_wr != sym_rd) {
                printf ("CACHE TEST FAILED: host wrote %d, chip read %d.\n",
                        (int) host_wr, (int) sym_rd);
                err |= 1;
        }
        if (host_rd != sym_wr) {
                printf ("CACHE TEST FAILED: chip wrote %d, host read %d.\n",
                        (int) sym_wr, (int) host_rd);
                err |= 2;
        }
        if (sym_bk != sym_wr) {
                printf ("CACHE TEST FAILED: chip wrote %d, read back %d.\n",
                        (int) sym_wr, (int) sym_bk);
                err |= 4;
        }

        return err;
}

/*
 *  log message for real hard errors
 *
 *  sym0 targ 0?: ERROR (ds:si) (so-si-sd) (sx/s3/s4) @ name (dsp:dbc).
 *            reg: r0 r1 r2 r3 r4 r5 r6 ..... rf.
 *
 *  exception register:
 *      ds:     dstat
 *      si:     sist
 *
 *  SCSI bus lines:
 *      so:     control lines as driven by chip.
 *      si:     control lines as seen by chip.
 *      sd:     scsi data lines as seen by chip.
 *
 *  wide/fastmode:
 *      sx:     sxfer  (see the manual)
 *      s3:     scntl3 (see the manual)
 *      s4:     scntl4 (see the manual)
 *
 *  current script command:
 *      dsp:    script address (relative to start of script).
 *      dbc:    first word of script command.
 *
 *  First 24 register of the chip:
 *      r0..rf
 */
static void sym_log_hard_error(struct Scsi_Host *shost, u_short sist, u_char dstat)
{
        struct sym_hcb *np = sym_get_hcb(shost);
        u32     dsp;
        int     script_ofs;
        int     script_size;
        char    *script_name;
        u_char  *script_base;
        int     i;

        dsp     = INL(np, nc_dsp);

        if      (dsp > np->scripta_ba &&
                 dsp <= np->scripta_ba + np->scripta_sz) {
                script_ofs      = dsp - np->scripta_ba;
                script_size     = np->scripta_sz;
                script_base     = (u_char *) np->scripta0;
                script_name     = "scripta";
        }
        else if (np->scriptb_ba < dsp && 
                 dsp <= np->scriptb_ba + np->scriptb_sz) {
                script_ofs      = dsp - np->scriptb_ba;
                script_size     = np->scriptb_sz;
                script_base     = (u_char *) np->scriptb0;
                script_name     = "scriptb";
        } else {
                script_ofs      = dsp;
                script_size     = 0;
                script_base     = NULL;
                script_name     = "mem";
        }

        printf ("%s:%d: ERROR (%x:%x) (%x-%x-%x) (%x/%x/%x) @ (%s %x:%08x).\n",
                sym_name(np), (unsigned)INB(np, nc_sdid)&0x0f, dstat, sist,
                (unsigned)INB(np, nc_socl), (unsigned)INB(np, nc_sbcl),
                (unsigned)INB(np, nc_sbdl), (unsigned)INB(np, nc_sxfer),
                (unsigned)INB(np, nc_scntl3),
                (np->features & FE_C10) ?  (unsigned)INB(np, nc_scntl4) : 0,
                script_name, script_ofs,   (unsigned)INL(np, nc_dbc));

        if (((script_ofs & 3) == 0) &&
            (unsigned)script_ofs < script_size) {
                printf ("%s: script cmd = %08x\n", sym_name(np),
                        scr_to_cpu((int) *(u32 *)(script_base + script_ofs)));
        }

        printf("%s: regdump:", sym_name(np));
        for (i = 0; i < 24; i++)
                printf(" %02x", (unsigned)INB_OFF(np, i));
        printf(".\n");

        /*
         *  PCI BUS error.
         */
        if (dstat & (MDPE|BF))
                sym_log_bus_error(shost);
}

void sym_dump_registers(struct Scsi_Host *shost)
{
        struct sym_hcb *np = sym_get_hcb(shost);
        u_short sist;
        u_char dstat;

        sist = INW(np, nc_sist);
        dstat = INB(np, nc_dstat);
        sym_log_hard_error(shost, sist, dstat);
}

static struct sym_chip sym_dev_table[] = {
 {PCI_DEVICE_ID_NCR_53C810, 0x0f, "810", 4, 8, 4, 64,
 FE_ERL}
 ,
#ifdef SYM_DEBUG_GENERIC_SUPPORT
 {PCI_DEVICE_ID_NCR_53C810, 0xff, "810a", 4,  8, 4, 1,
 FE_BOF}
 ,
#else
 {PCI_DEVICE_ID_NCR_53C810, 0xff, "810a", 4,  8, 4, 1,
 FE_CACHE_SET|FE_LDSTR|FE_PFEN|FE_BOF}
 ,
#endif
 {PCI_DEVICE_ID_NCR_53C815, 0xff, "815", 4,  8, 4, 64,
 FE_BOF|FE_ERL}
 ,
 {PCI_DEVICE_ID_NCR_53C825, 0x0f, "825", 6,  8, 4, 64,
 FE_WIDE|FE_BOF|FE_ERL|FE_DIFF}
 ,
 {PCI_DEVICE_ID_NCR_53C825, 0xff, "825a", 6,  8, 4, 2,
 FE_WIDE|FE_CACHE0_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|FE_RAM|FE_DIFF}
 ,
 {PCI_DEVICE_ID_NCR_53C860, 0xff, "860", 4,  8, 5, 1,
 FE_ULTRA|FE_CACHE_SET|FE_BOF|FE_LDSTR|FE_PFEN}
 ,
 {PCI_DEVICE_ID_NCR_53C875, 0x01, "875", 6, 16, 5, 2,
 FE_WIDE|FE_ULTRA|FE_CACHE0_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_DIFF|FE_VARCLK}
 ,
 {PCI_DEVICE_ID_NCR_53C875, 0xff, "875", 6, 16, 5, 2,
 FE_WIDE|FE_ULTRA|FE_DBLR|FE_CACHE0_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_DIFF|FE_VARCLK}
 ,
 {PCI_DEVICE_ID_NCR_53C875J, 0xff, "875J", 6, 16, 5, 2,
 FE_WIDE|FE_ULTRA|FE_DBLR|FE_CACHE0_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_DIFF|FE_VARCLK}
 ,
 {PCI_DEVICE_ID_NCR_53C885, 0xff, "885", 6, 16, 5, 2,
 FE_WIDE|FE_ULTRA|FE_DBLR|FE_CACHE0_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_DIFF|FE_VARCLK}
 ,
#ifdef SYM_DEBUG_GENERIC_SUPPORT
 {PCI_DEVICE_ID_NCR_53C895, 0xff, "895", 6, 31, 7, 2,
 FE_WIDE|FE_ULTRA2|FE_QUAD|FE_CACHE_SET|FE_BOF|FE_DFS|
 FE_RAM|FE_LCKFRQ}
 ,
#else
 {PCI_DEVICE_ID_NCR_53C895, 0xff, "895", 6, 31, 7, 2,
 FE_WIDE|FE_ULTRA2|FE_QUAD|FE_CACHE_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_LCKFRQ}
 ,
#endif
 {PCI_DEVICE_ID_NCR_53C896, 0xff, "896", 6, 31, 7, 4,
 FE_WIDE|FE_ULTRA2|FE_QUAD|FE_CACHE_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_RAM8K|FE_64BIT|FE_DAC|FE_IO256|FE_NOPM|FE_LEDC|FE_LCKFRQ}
 ,
 {PCI_DEVICE_ID_LSI_53C895A, 0xff, "895a", 6, 31, 7, 4,
 FE_WIDE|FE_ULTRA2|FE_QUAD|FE_CACHE_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_RAM8K|FE_DAC|FE_IO256|FE_NOPM|FE_LEDC|FE_LCKFRQ}
 ,
 {PCI_DEVICE_ID_LSI_53C875A, 0xff, "875a", 6, 31, 7, 4,
 FE_WIDE|FE_ULTRA|FE_QUAD|FE_CACHE_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_DAC|FE_IO256|FE_NOPM|FE_LEDC|FE_LCKFRQ}
 ,
 {PCI_DEVICE_ID_LSI_53C1010_33, 0x00, "1010-33", 6, 31, 7, 8,
 FE_WIDE|FE_ULTRA3|FE_QUAD|FE_CACHE_SET|FE_BOF|FE_DFBC|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_RAM8K|FE_64BIT|FE_DAC|FE_IO256|FE_NOPM|FE_LEDC|FE_CRC|
 FE_C10}
 ,
 {PCI_DEVICE_ID_LSI_53C1010_33, 0xff, "1010-33", 6, 31, 7, 8,
 FE_WIDE|FE_ULTRA3|FE_QUAD|FE_CACHE_SET|FE_BOF|FE_DFBC|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_RAM8K|FE_64BIT|FE_DAC|FE_IO256|FE_NOPM|FE_LEDC|FE_CRC|
 FE_C10|FE_U3EN}
 ,
 {PCI_DEVICE_ID_LSI_53C1010_66, 0xff, "1010-66", 6, 31, 7, 8,
 FE_WIDE|FE_ULTRA3|FE_QUAD|FE_CACHE_SET|FE_BOF|FE_DFBC|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_RAM8K|FE_64BIT|FE_DAC|FE_IO256|FE_NOPM|FE_LEDC|FE_66MHZ|FE_CRC|
 FE_C10|FE_U3EN}
 ,
 {PCI_DEVICE_ID_LSI_53C1510, 0xff, "1510d", 6, 31, 7, 4,
 FE_WIDE|FE_ULTRA2|FE_QUAD|FE_CACHE_SET|FE_BOF|FE_DFS|FE_LDSTR|FE_PFEN|
 FE_RAM|FE_IO256|FE_LEDC}
};

#define sym_num_devs (ARRAY_SIZE(sym_dev_table))

/*
 *  Look up the chip table.
 *
 *  Return a pointer to the chip entry if found, 
 *  zero otherwise.
 */
struct sym_chip *
sym_lookup_chip_table (u_short device_id, u_char revision)
{
        struct  sym_chip *chip;
        int     i;

        for (i = 0; i < sym_num_devs; i++) {
                chip = &sym_dev_table[i];
                if (device_id != chip->device_id)
                        continue;
                if (revision > chip->revision_id)
                        continue;
                return chip;
        }

        return NULL;
}

#if SYM_CONF_DMA_ADDRESSING_MODE == 2
/*
 *  Lookup the 64 bit DMA segments map.
 *  This is only used if the direct mapping 
 *  has been unsuccessful.
 */
int sym_lookup_dmap(struct sym_hcb *np, u32 h, int s)
{
        int i;

        if (!use_dac(np))
                goto weird;

        /* Look up existing mappings */
        for (i = SYM_DMAP_SIZE-1; i > 0; i--) {
                if (h == np->dmap_bah[i])
                        return i;
        }
        /* If direct mapping is free, get it */
        if (!np->dmap_bah[s])
                goto new;
        /* Collision -> lookup free mappings */
        for (s = SYM_DMAP_SIZE-1; s > 0; s--) {
                if (!np->dmap_bah[s])
                        goto new;
        }
weird:
        panic("sym: ran out of 64 bit DMA segment registers");
        return -1;
new:
        np->dmap_bah[s] = h;
        np->dmap_dirty = 1;
        return s;
}

/*
 *  Update IO registers scratch C..R so they will be 
 *  in sync. with queued CCB expectations.
 */
static void sym_update_dmap_regs(struct sym_hcb *np)
{
        int o, i;

        if (!np->dmap_dirty)
                return;
        o = offsetof(struct sym_reg, nc_scrx[0]);
        for (i = 0; i < SYM_DMAP_SIZE; i++) {
                OUTL_OFF(np, o, np->dmap_bah[i]);
                o += 4;
        }
        np->dmap_dirty = 0;
}
#endif

/* Enforce all the fiddly SPI rules and the chip limitations */
static void sym_check_goals(struct sym_hcb *np, struct scsi_target *starget,
                struct sym_trans *goal)
{
        if (!spi_support_wide(starget))
                goal->width = 0;

        if (!spi_support_sync(starget)) {
                goal->iu = 0;
                goal->dt = 0;
                goal->qas = 0;
                goal->offset = 0;
                return;
        }

        if (spi_support_dt(starget)) {
                if (spi_support_dt_only(starget))
                        goal->dt = 1;

                if (goal->offset == 0)
                        goal->dt = 0;
        } else {
                goal->dt = 0;
        }

        /* Some targets fail to properly negotiate DT in SE mode */
        if ((np->scsi_mode != SMODE_LVD) || !(np->features & FE_U3EN))
                goal->dt = 0;

        if (goal->dt) {
                /* all DT transfers must be wide */
                goal->width = 1;
                if (goal->offset > np->maxoffs_dt)
                        goal->offset = np->maxoffs_dt;
                if (goal->period < np->minsync_dt)
                        goal->period = np->minsync_dt;
                if (goal->period > np->maxsync_dt)
                        goal->period = np->maxsync_dt;
        } else {
                goal->iu = goal->qas = 0;
                if (goal->offset > np->maxoffs)
                        goal->offset = np->maxoffs;
                if (goal->period < np->minsync)
                        goal->period = np->minsync;
                if (goal->period > np->maxsync)
                        goal->period = np->maxsync;
        }
}

/*
 *  Prepare the next negotiation message if needed.
 *
 *  Fill in the part of message buffer that contains the 
 *  negotiation and the nego_status field of the CCB.
 *  Returns the size of the message in bytes.
 */
static int sym_prepare_nego(struct sym_hcb *np, struct sym_ccb *cp, u_char *msgptr)
{
        struct sym_tcb *tp = &np->target[cp->target];
        struct scsi_target *starget = tp->starget;
        struct sym_trans *goal = &tp->tgoal;
        int msglen = 0;
        int nego;

        sym_check_goals(np, starget, goal);

        /*
         * Many devices implement PPR in a buggy way, so only use it if we
         * really want to.
         */
        if (goal->renego == NS_PPR || (goal->offset &&
            (goal->iu || goal->dt || goal->qas || (goal->period < 0xa)))) {
                nego = NS_PPR;
        } else if (goal->renego == NS_WIDE || goal->width) {
                nego = NS_WIDE;
        } else if (goal->renego == NS_SYNC || goal->offset) {
                nego = NS_SYNC;
        } else {
                goal->check_nego = 0;
                nego = 0;
        }

        switch (nego) {
        case NS_SYNC:
                msglen += spi_populate_sync_msg(msgptr + msglen, goal->period,
                                goal->offset);
                break;
        case NS_WIDE:
                msglen += spi_populate_width_msg(msgptr + msglen, goal->width);
                break;
        case NS_PPR:
                msglen += spi_populate_ppr_msg(msgptr + msglen, goal->period,
                                goal->offset, goal->width,
                                (goal->iu ? PPR_OPT_IU : 0) |
                                        (goal->dt ? PPR_OPT_DT : 0) |
                                        (goal->qas ? PPR_OPT_QAS : 0));
                break;
        }

        cp->nego_status = nego;

        if (nego) {
                tp->nego_cp = cp; /* Keep track a nego will be performed */
                if (DEBUG_FLAGS & DEBUG_NEGO) {
                        sym_print_nego_msg(np, cp->target, 
                                          nego == NS_SYNC ? "sync msgout" :
                                          nego == NS_WIDE ? "wide msgout" :
                                          "ppr msgout", msgptr);
                }
        }

        return msglen;
}

/*
 *  Insert a job into the start queue.
 */
void sym_put_start_queue(struct sym_hcb *np, struct sym_ccb *cp)
{
        u_short qidx;

#ifdef SYM_CONF_IARB_SUPPORT
        /*
         *  If the previously queued CCB is not yet done, 
         *  set the IARB hint. The SCRIPTS will go with IARB 
         *  for this job when starting the previous one.
         *  We leave devices a chance to win arbitration by 
         *  not using more than 'iarb_max' consecutive 
         *  immediate arbitrations.
         */
        if (np->last_cp && np->iarb_count < np->iarb_max) {
                np->last_cp->host_flags |= HF_HINT_IARB;
                ++np->iarb_count;
        }
        else
                np->iarb_count = 0;
        np->last_cp = cp;
#endif

#if   SYM_CONF_DMA_ADDRESSING_MODE == 2
        /*
         *  Make SCRIPTS aware of the 64 bit DMA 
         *  segment registers not being up-to-date.
         */
        if (np->dmap_dirty)
                cp->host_xflags |= HX_DMAP_DIRTY;
#endif

        /*
         *  Insert first the idle task and then our job.
         *  The MBs should ensure proper ordering.
         */
        qidx = np->squeueput + 2;
        if (qidx >= MAX_QUEUE*2) qidx = 0;

        np->squeue [qidx]          = cpu_to_scr(np->idletask_ba);
        MEMORY_WRITE_BARRIER();
        np->squeue [np->squeueput] = cpu_to_scr(cp->ccb_ba);

        np->squeueput = qidx;

        if (DEBUG_FLAGS & DEBUG_QUEUE)
                scmd_printk(KERN_DEBUG, cp->cmd, "queuepos=%d\n",
                                                        np->squeueput);

        /*
         *  Script processor may be waiting for reselect.
         *  Wake it up.
         */
        MEMORY_WRITE_BARRIER();
        OUTB(np, nc_istat, SIGP|np->istat_sem);
}

#ifdef SYM_OPT_HANDLE_DEVICE_QUEUEING
/*
 *  Start next ready-to-start CCBs.
 */
void sym_start_next_ccbs(struct sym_hcb *np, struct sym_lcb *lp, int maxn)
{
        SYM_QUEHEAD *qp;
        struct sym_ccb *cp;

        /* 
         *  Paranoia, as usual. :-)
         */
        assert(!lp->started_tags || !lp->started_no_tag);

        /*
         *  Try to start as many commands as asked by caller.
         *  Prevent from having both tagged and untagged 
         *  commands queued to the device at the same time.
         */
        while (maxn--) {
                qp = sym_remque_head(&lp->waiting_ccbq);
                if (!qp)
                        break;
                cp = sym_que_entry(qp, struct sym_ccb, link2_ccbq);
                if (cp->tag != NO_TAG) {
                        if (lp->started_no_tag ||
                            lp->started_tags >= lp->started_max) {
                                sym_insque_head(qp, &lp->waiting_ccbq);
                                break;
                        }
                        lp->itlq_tbl[cp->tag] = cpu_to_scr(cp->ccb_ba);
                        lp->head.resel_sa =
                                cpu_to_scr(SCRIPTA_BA(np, resel_tag));
                        ++lp->started_tags;
                } else {
                        if (lp->started_no_tag || lp->started_tags) {
                                sym_insque_head(qp, &lp->waiting_ccbq);
                                break;
                        }
                        lp->head.itl_task_sa = cpu_to_scr(cp->ccb_ba);
                        lp->head.resel_sa =
                              cpu_to_scr(SCRIPTA_BA(np, resel_no_tag));
                        ++lp->started_no_tag;
                }
                cp->started = 1;
                sym_insque_tail(qp, &lp->started_ccbq);
                sym_put_start_queue(np, cp);
        }
}
#endif /* SYM_OPT_HANDLE_DEVICE_QUEUEING */

/*
 *  The chip may have completed jobs. Look at the DONE QUEUE.
 *
 *  On paper, memory read barriers may be needed here to 
 *  prevent out of order LOADs by the CPU from having 
 *  prefetched stale data prior to DMA having occurred.
 */
static int sym_wakeup_done (struct sym_hcb *np)
{
        struct sym_ccb *cp;
        int i, n;
        u32 dsa;

        n = 0;
        i = np->dqueueget;

        /* MEMORY_READ_BARRIER(); */
        while (1) {
                dsa = scr_to_cpu(np->dqueue[i]);
                if (!dsa)
                        break;
                np->dqueue[i] = 0;
                if ((i = i+2) >= MAX_QUEUE*2)
                        i = 0;

                cp = sym_ccb_from_dsa(np, dsa);
                if (cp) {
                        MEMORY_READ_BARRIER();
                        sym_complete_ok (np, cp);
                        ++n;
                }
                else
                        printf ("%s: bad DSA (%x) in done queue.\n",
                                sym_name(np), (u_int) dsa);
        }
        np->dqueueget = i;

        return n;
}

/*
 *  Complete all CCBs queued to the COMP queue.
 *
 *  These CCBs are assumed:
 *  - Not to be referenced either by devices or 
 *    SCRIPTS-related queues and datas.
 *  - To have to be completed with an error condition 
 *    or requeued.
 *
 *  The device queue freeze count is incremented 
 *  for each CCB that does not prevent this.
 *  This function is called when all CCBs involved 
 *  in error handling/recovery have been reaped.
 */
static void sym_flush_comp_queue(struct sym_hcb *np, int cam_status)
{
        SYM_QUEHEAD *qp;
        struct sym_ccb *cp;

        while ((qp = sym_remque_head(&np->comp_ccbq)) != NULL) {
                struct scsi_cmnd *cmd;
                cp = sym_que_entry(qp, struct sym_ccb, link_ccbq);
                sym_insque_tail(&cp->link_ccbq, &np->busy_ccbq);
                /* Leave quiet CCBs waiting for resources */
                if (cp->host_status == HS_WAIT)
                        continue;
                cmd = cp->cmd;
                if (cam_status)
                        sym_set_cam_status(cmd, cam_status);
#ifdef SYM_OPT_HANDLE_DEVICE_QUEUEING
                if (sym_get_cam_status(cmd) == DID_SOFT_ERROR) {
                        struct sym_tcb *tp = &np->target[cp->target];
                        struct sym_lcb *lp = sym_lp(tp, cp->lun);
                        if (lp) {
                                sym_remque(&cp->link2_ccbq);
                                sym_insque_tail(&cp->link2_ccbq,
                                                &lp->waiting_ccbq);
                                if (cp->started) {
                                        if (cp->tag != NO_TAG)
                                                --lp->started_tags;
                                        else
                                                --lp->started_no_tag;
                                }
                        }
                        cp->started = 0;
                        continue;
                }
#endif
                sym_free_ccb(np, cp);
                sym_xpt_done(np, cmd);
        }
}

/*
 *  Complete all active CCBs with error.
 *  Used on CHIP/SCSI RESET.
 */
static void sym_flush_busy_queue (struct sym_hcb *np, int cam_status)
{
        /*
         *  Move all active CCBs to the COMP queue 
         *  and flush this queue.
         */
        sym_que_splice(&np->busy_ccbq, &np->comp_ccbq);
        sym_que_init(&np->busy_ccbq);
        sym_flush_comp_queue(np, cam_status);
}

/*
 *  Start chip.
 *
 *  'reason' means:
 *     0: initialisation.
 *     1: SCSI BUS RESET delivered or received.
 *     2: SCSI BUS MODE changed.
 */
void sym_start_up(struct Scsi_Host *shost, int reason)
{
        struct sym_data *sym_data = shost_priv(shost);
        struct pci_dev *pdev = sym_data->pdev;
        struct sym_hcb *np = sym_data->ncb;
        int     i;
        u32     phys;

        /*
         *  Reset chip if asked, otherwise just clear fifos.
         */
        if (reason == 1)
                sym_soft_reset(np);
        else {
                OUTB(np, nc_stest3, TE|CSF);
                OUTONB(np, nc_ctest3, CLF);
        }
 
        /*
         *  Clear Start Queue
         */
        phys = np->squeue_ba;
        for (i = 0; i < MAX_QUEUE*2; i += 2) {
                np->squeue[i]   = cpu_to_scr(np->idletask_ba);
                np->squeue[i+1] = cpu_to_scr(phys + (i+2)*4);
        }
        np->squeue[MAX_QUEUE*2-1] = cpu_to_scr(phys);

        /*
         *  Start at first entry.
         */
        np->squeueput = 0;

        /*
         *  Clear Done Queue
         */
        phys = np->dqueue_ba;
        for (i = 0; i < MAX_QUEUE*2; i += 2) {
                np->dqueue[i]   = 0;
                np->dqueue[i+1] = cpu_to_scr(phys + (i+2)*4);
        }
        np->dqueue[MAX_QUEUE*2-1] = cpu_to_scr(phys);

        /*
         *  Start at first entry.
         */
        np->dqueueget = 0;

        /*
         *  Install patches in scripts.
         *  This also let point to first position the start 
         *  and done queue pointers used from SCRIPTS.
         */
        np->fw_patch(shost);

        /*
         *  Wakeup all pending jobs.
         */
        sym_flush_busy_queue(np, DID_RESET);

        /*
         *  Init chip.
         */
        OUTB(np, nc_istat,  0x00);                      /*  Remove Reset, abort */
        INB(np, nc_mbox1);
        udelay(2000); /* The 895 needs time for the bus mode to settle */

        OUTB(np, nc_scntl0, np->rv_scntl0 | 0xc0);
                                        /*  full arb., ena parity, par->ATN  */
        OUTB(np, nc_scntl1, 0x00);              /*  odd parity, and remove CRST!! */

        sym_selectclock(np, np->rv_scntl3);     /* Select SCSI clock */

        OUTB(np, nc_scid  , RRE|np->myaddr);    /* Adapter SCSI address */
        OUTW(np, nc_respid, 1ul<<np->myaddr);   /* Id to respond to */
        OUTB(np, nc_istat , SIGP        );              /*  Signal Process */
        OUTB(np, nc_dmode , np->rv_dmode);              /* Burst length, dma mode */
        OUTB(np, nc_ctest5, np->rv_ctest5);     /* Large fifo + large burst */

        OUTB(np, nc_dcntl , NOCOM|np->rv_dcntl);        /* Protect SFBR */
        OUTB(np, nc_ctest3, np->rv_ctest3);     /* Write and invalidate */
        OUTB(np, nc_ctest4, np->rv_ctest4);     /* Master parity checking */

        /* Extended Sreq/Sack filtering not supported on the C10 */
        if (np->features & FE_C10)
                OUTB(np, nc_stest2, np->rv_stest2);
        else
                OUTB(np, nc_stest2, EXT|np->rv_stest2);

        OUTB(np, nc_stest3, TE);                        /* TolerANT enable */
        OUTB(np, nc_stime0, 0x0c);                      /* HTH disabled  STO 0.25 sec */

        /*
         *  For now, disable AIP generation on C1010-66.
         */
        if (pdev->device == PCI_DEVICE_ID_LSI_53C1010_66)
                OUTB(np, nc_aipcntl1, DISAIP);

        /*
         *  C10101 rev. 0 errata.
         *  Errant SGE's when in narrow. Write bits 4 & 5 of
         *  STEST1 register to disable SGE. We probably should do 
         *  that from SCRIPTS for each selection/reselection, but 
         *  I just don't want. :)
         */
        if (pdev->device == PCI_DEVICE_ID_LSI_53C1010_33 &&
            pdev->revision < 1)
                OUTB(np, nc_stest1, INB(np, nc_stest1) | 0x30);

        /*
         *  DEL 441 - 53C876 Rev 5 - Part Number 609-0392787/2788 - ITEM 2.
         *  Disable overlapped arbitration for some dual function devices, 
         *  regardless revision id (kind of post-chip-design feature. ;-))
         */
        if (pdev->device == PCI_DEVICE_ID_NCR_53C875)
                OUTB(np, nc_ctest0, (1<<5));
        else if (pdev->device == PCI_DEVICE_ID_NCR_53C896)
                np->rv_ccntl0 |= DPR;

        /*
         *  Write CCNTL0/CCNTL1 for chips capable of 64 bit addressing 
         *  and/or hardware phase mismatch, since only such chips 
         *  seem to support those IO registers.
         */
        if (np->features & (FE_DAC|FE_NOPM)) {
                OUTB(np, nc_ccntl0, np->rv_ccntl0);
                OUTB(np, nc_ccntl1, np->rv_ccntl1);
        }

#if     SYM_CONF_DMA_ADDRESSING_MODE == 2
        /*
         *  Set up scratch C and DRS IO registers to map the 32 bit 
         *  DMA address range our data structures are located in.
         */
        if (use_dac(np)) {
                np->dmap_bah[0] = 0;    /* ??? */
                OUTL(np, nc_scrx[0], np->dmap_bah[0]);
                OUTL(np, nc_drs, np->dmap_bah[0]);
        }
#endif

        /*
         *  If phase mismatch handled by scripts (895A/896/1010),
         *  set PM jump addresses.
         */
        if (np->features & FE_NOPM) {
                OUTL(np, nc_pmjad1, SCRIPTB_BA(np, pm_handle));
                OUTL(np, nc_pmjad2, SCRIPTB_BA(np, pm_handle));
        }

        /*
         *    Enable GPIO0 pin for writing if LED support from SCRIPTS.
         *    Also set GPIO5 and clear GPIO6 if hardware LED control.
         */
        if (np->features & FE_LED0)
                OUTB(np, nc_gpcntl, INB(np, nc_gpcntl) & ~0x01);
        else if (np->features & FE_LEDC)
                OUTB(np, nc_gpcntl, (INB(np, nc_gpcntl) & ~0x41) | 0x20);

        /*
         *      enable ints
         */
        OUTW(np, nc_sien , STO|HTH|MA|SGE|UDC|RST|PAR);
        OUTB(np, nc_dien , MDPE|BF|SSI|SIR|IID);

        /*
         *  For 895/6 enable SBMC interrupt and save current SCSI bus mode.
         *  Try to eat the spurious SBMC interrupt that may occur when 
         *  we reset the chip but not the SCSI BUS (at initialization).
         */
        if (np->features & (FE_ULTRA2|FE_ULTRA3)) {
                OUTONW(np, nc_sien, SBMC);
                if (reason == 0) {
                        INB(np, nc_mbox1);
                        mdelay(100);
                        INW(np, nc_sist);
                }
                np->scsi_mode = INB(np, nc_stest4) & SMODE;
        }

        /*
         *  Fill in target structure.
         *  Reinitialize usrsync.
         *  Reinitialize usrwide.
         *  Prepare sync negotiation according to actual SCSI bus mode.
         */
        for (i=0;i<SYM_CONF_MAX_TARGET;i++) {
                struct sym_tcb *tp = &np->target[i];

                tp->to_reset  = 0;
                tp->head.sval = 0;
                tp->head.wval = np->rv_scntl3;
                tp->head.uval = 0;
                if (tp->lun0p)
                        tp->lun0p->to_clear = 0;
                if (tp->lunmp) {
                        int ln;

                        for (ln = 1; ln < SYM_CONF_MAX_LUN; ln++)
                                if (tp->lunmp[ln])
                                        tp->lunmp[ln]->to_clear = 0;
                }
        }

        /*
         *  Download SCSI SCRIPTS to on-chip RAM if present,
         *  and start script processor.
         *  We do the download preferently from the CPU.
         *  For platforms that may not support PCI memory mapping,
         *  we use simple SCRIPTS that performs MEMORY MOVEs.
         */
        phys = SCRIPTA_BA(np, init);
        if (np->ram_ba) {
                if (sym_verbose >= 2)
                        printf("%s: Downloading SCSI SCRIPTS.\n", sym_name(np));
                memcpy_toio(np->s.ramaddr, np->scripta0, np->scripta_sz);
                if (np->features & FE_RAM8K) {
                        memcpy_toio(np->s.ramaddr + 4096, np->scriptb0, np->scriptb_sz);
                        phys = scr_to_cpu(np->scr_ram_seg);
                        OUTL(np, nc_mmws, phys);
                        OUTL(np, nc_mmrs, phys);
                        OUTL(np, nc_sfs,  phys);
                        phys = SCRIPTB_BA(np, start64);
                }
        }

        np->istat_sem = 0;

        OUTL(np, nc_dsa, np->hcb_ba);
        OUTL_DSP(np, phys);

        /*
         *  Notify the XPT about the RESET condition.
         */
        if (reason != 0)
                sym_xpt_async_bus_reset(np);
}

/*
 *  Switch trans mode for current job and its target.
 */
static void sym_settrans(struct sym_hcb *np, int target, u_char opts, u_char ofs,
                         u_char per, u_char wide, u_char div, u_char fak)
{
        SYM_QUEHEAD *qp;
        u_char sval, wval, uval;
        struct sym_tcb *tp = &np->target[target];

        assert(target == (INB(np, nc_sdid) & 0x0f));

        sval = tp->head.sval;
        wval = tp->head.wval;
        uval = tp->head.uval;

#if 0
        printf("XXXX sval=%x wval=%x uval=%x (%x)\n", 
                sval, wval, uval, np->rv_scntl3);
#endif
        /*
         *  Set the offset.
         */
        if (!(np->features & FE_C10))
                sval = (sval & ~0x1f) | ofs;
        else
                sval = (sval & ~0x3f) | ofs;

        /*
         *  Set the sync divisor and extra clock factor.
         */
        if (ofs != 0) {
                wval = (wval & ~0x70) | ((div+1) << 4);
                if (!(np->features & FE_C10))
                        sval = (sval & ~0xe0) | (fak << 5);
                else {
                        uval = uval & ~(XCLKH_ST|XCLKH_DT|XCLKS_ST|XCLKS_DT);
                        if (fak >= 1) uval |= (XCLKH_ST|XCLKH_DT);
                        if (fak >= 2) uval |= (XCLKS_ST|XCLKS_DT);
                }
        }

        /*
         *  Set the bus width.
         */
        wval = wval & ~EWS;
        if (wide != 0)
                wval |= EWS;

        /*
         *  Set misc. ultra enable bits.
         */
        if (np->features & FE_C10) {
                uval = uval & ~(U3EN|AIPCKEN);
                if (opts)       {
                        assert(np->features & FE_U3EN);
                        uval |= U3EN;
                }
        } else {
                wval = wval & ~ULTRA;

                if (per <= 12)  wval |= ULTRA;
        }

        /*
         *   Stop there if sync parameters are unchanged.
         */
        if (tp->head.sval == sval && 
            tp->head.wval == wval &&
            tp->head.uval == uval)
                return;
        tp->head.sval = sval;
        tp->head.wval = wval;
        tp->head.uval = uval;

        /*
         *  Disable extended Sreq/Sack filtering if per < 50.
         *  Not supported on the C1010.
         */
        if (per < 50 && !(np->features & FE_C10))
                OUTOFFB(np, nc_stest2, EXT);

        /*
         *  set actual value and sync_status
         */
        OUTB(np, nc_sxfer,  tp->head.sval);
        OUTB(np, nc_scntl3, tp->head.wval);

        if (np->features & FE_C10) {
                OUTB(np, nc_scntl4, tp->head.uval);
        }

        /*
         *  patch ALL busy ccbs of this target.
         */
        FOR_EACH_QUEUED_ELEMENT(&np->busy_ccbq, qp) {
                struct sym_ccb *cp;
                cp = sym_que_entry(qp, struct sym_ccb, link_ccbq);
                if (cp->target != target)
                        continue;
                cp->phys.select.sel_scntl3 = tp->head.wval;
                cp->phys.select.sel_sxfer  = tp->head.sval;
                if (np->features & FE_C10) {
                        cp->phys.select.sel_scntl4 = tp->head.uval;
                }
        }
}

static void sym_announce_transfer_rate(struct sym_tcb *tp)
{
        struct scsi_target *starget = tp->starget;

        if (tp->tprint.period != spi_period(starget) ||
            tp->tprint.offset != spi_offset(starget) ||
            tp->tprint.width != spi_width(starget) ||
            tp->tprint.iu != spi_iu(starget) ||
            tp->tprint.dt != spi_dt(starget) ||
            tp->tprint.qas != spi_qas(starget) ||
            !tp->tprint.check_nego) {
                tp->tprint.period = spi_period(starget);
                tp->tprint.offset = spi_offset(starget);
                tp->tprint.width = spi_width(starget);
                tp->tprint.iu = spi_iu(starget);
                tp->tprint.dt = spi_dt(starget);
                tp->tprint.qas = spi_qas(starget);
                tp->tprint.check_nego = 1;

                spi_display_xfer_agreement(starget);
        }
}

/*
 *  We received a WDTR.
 *  Let everything be aware of the changes.
 */
static void sym_setwide(struct sym_hcb *np, int target, u_char wide)
{
        struct sym_tcb *tp = &np->target[target];
        struct scsi_target *starget = tp->starget;

        sym_settrans(np, target, 0, 0, 0, wide, 0, 0);

        if (wide)
                tp->tgoal.renego = NS_WIDE;
        else
                tp->tgoal.renego = 0;
        tp->tgoal.check_nego = 0;
        tp->tgoal.width = wide;
        spi_offset(starget) = 0;
        spi_period(starget) = 0;
        spi_width(starget) = wide;
        spi_iu(starget) = 0;
        spi_dt(starget) = 0;
        spi_qas(starget) = 0;

        if (sym_verbose >= 3)
                sym_announce_transfer_rate(tp);
}

/*
 *  We received a SDTR.
 *  Let everything be aware of the changes.
 */
static void
sym_setsync(struct sym_hcb *np, int target,
            u_char ofs, u_char per, u_char div, u_char fak)
{
        struct sym_tcb *tp = &np->target[target];
        struct scsi_target *starget = tp->starget;
        u_char wide = (tp->head.wval & EWS) ? BUS_16_BIT : BUS_8_BIT;

        sym_settrans(np, target, 0, ofs, per, wide, div, fak);

        if (wide)
                tp->tgoal.renego = NS_WIDE;
        else if (ofs)
                tp->tgoal.renego = NS_SYNC;
        else
                tp->tgoal.renego = 0;
        spi_period(starget) = per;
        spi_offset(starget) = ofs;
        spi_iu(starget) = spi_dt(starget) = spi_qas(starget) = 0;

        if (!tp->tgoal.dt && !tp->tgoal.iu && !tp->tgoal.qas) {
                tp->tgoal.period = per;
                tp->tgoal.offset = ofs;
                tp->tgoal.check_nego = 0;
        }

        sym_announce_transfer_rate(tp);
}

/*
 *  We received a PPR.
 *  Let everything be aware of the changes.
 */
static void 
sym_setpprot(struct sym_hcb *np, int target, u_char opts, u_char ofs,
             u_char per, u_char wide, u_char div, u_char fak)
{
        struct sym_tcb *tp = &np->target[target];
        struct scsi_target *starget = tp->starget;

        sym_settrans(np, target, opts, ofs, per, wide, div, fak);

        if (wide || ofs)
                tp->tgoal.renego = NS_PPR;
        else
                tp->tgoal.renego = 0;
        spi_width(starget) = tp->tgoal.width = wide;
        spi_period(starget) = tp->tgoal.period = per;
        spi_offset(starget) = tp->tgoal.offset = ofs;
        spi_iu(starget) = tp->tgoal.iu = !!(opts & PPR_OPT_IU);
        spi_dt(starget) = tp->tgoal.dt = !!(opts & PPR_OPT_DT);
        spi_qas(starget) = tp->tgoal.qas = !!(opts & PPR_OPT_QAS);
        tp->tgoal.check_nego = 0;

        sym_announce_transfer_rate(tp);
}

/*
 *  generic recovery from scsi interrupt
 *
 *  The doc says that when the chip gets an SCSI interrupt,
 *  it tries to stop in an orderly fashion, by completing 
 *  an instruction fetch that had started or by flushing 
 *  the DMA fifo for a write to memory that was executing.
 *  Such a fashion is not enough to know if the instruction 
 *  that was just before the current DSP value has been 
 *  executed or not.
 *
 *  There are some small SCRIPTS sections that deal with 
 *  the start queue and the done queue that may break any 
 *  assomption from the C code if we are interrupted 
 *  inside, so we reset if this happens. Btw, since these 
 *  SCRIPTS sections are executed while the SCRIPTS hasn't 
 *  started SCSI operations, it is very unlikely to happen.
 *
 *  All the driver data structures are supposed to be 
 *  allocated from the same 4 GB memory window, so there 
 *  is a 1 to 1 relationship between DSA and driver data 
 *  structures. Since we are careful :) to invalidate the 
 *  DSA when we complete a command or when the SCRIPTS 
 *  pushes a DSA into a queue, we can trust it when it 
 *  points to a CCB.
 */
static void sym_recover_scsi_int (struct sym_hcb *np, u_char hsts)
{
        u32     dsp     = INL(np, nc_dsp);
        u32     dsa     = INL(np, nc_dsa);
        struct sym_ccb *cp      = sym_ccb_from_dsa(np, dsa);

        /*
         *  If we haven't been interrupted inside the SCRIPTS 
         *  critical pathes, we can safely restart the SCRIPTS 
         *  and trust the DSA value if it matches a CCB.
         */
        if ((!(dsp > SCRIPTA_BA(np, getjob_begin) &&
               dsp < SCRIPTA_BA(np, getjob_end) + 1)) &&
            (!(dsp > SCRIPTA_BA(np, ungetjob) &&
               dsp < SCRIPTA_BA(np, reselect) + 1)) &&
            (!(dsp > SCRIPTB_BA(np, sel_for_abort) &&
               dsp < SCRIPTB_BA(np, sel_for_abort_1) + 1)) &&
            (!(dsp > SCRIPTA_BA(np, done) &&
               dsp < SCRIPTA_BA(np, done_end) + 1))) {
                OUTB(np, nc_ctest3, np->rv_ctest3 | CLF); /* clear dma fifo  */
                OUTB(np, nc_stest3, TE|CSF);            /* clear scsi fifo */
                /*
                 *  If we have a CCB, let the SCRIPTS call us back for 
                 *  the handling of the error with SCRATCHA filled with 
                 *  STARTPOS. This way, we will be able to freeze the 
                 *  device queue and requeue awaiting IOs.
                 */
                if (cp) {
                        cp->host_status = hsts;
                        OUTL_DSP(np, SCRIPTA_BA(np, complete_error));
                }
                /*
                 *  Otherwise just restart the SCRIPTS.
                 */
                else {
                        OUTL(np, nc_dsa, 0xffffff);
                        OUTL_DSP(np, SCRIPTA_BA(np, start));
                }
        }
        else
                goto reset_all;

        return;

reset_all:
        sym_start_reset(np);
}

/*
 *  chip exception handler for selection timeout
 */
static void sym_int_sto (struct sym_hcb *np)
{
        u32 dsp = INL(np, nc_dsp);

        if (DEBUG_FLAGS & DEBUG_TINY) printf ("T");

        if (dsp == SCRIPTA_BA(np, wf_sel_done) + 8)
                sym_recover_scsi_int(np, HS_SEL_TIMEOUT);
        else
                sym_start_reset(np);
}

/*
 *  chip exception handler for unexpected disconnect
 */
static void sym_int_udc (struct sym_hcb *np)
{
        printf ("%s: unexpected disconnect\n", sym_name(np));
        sym_recover_scsi_int(np, HS_UNEXPECTED);
}

/*
 *  chip exception handler for SCSI bus mode change
 *
 *  spi2-r12 11.2.3 says a transceiver mode change must 
 *  generate a reset event and a device that detects a reset 
 *  event shall initiate a hard reset. It says also that a
 *  device that detects a mode change shall set data transfer 
 *  mode to eight bit asynchronous, etc...
 *  So, just reinitializing all except chip should be enough.
 */
static void sym_int_sbmc(struct Scsi_Host *shost)
{
        struct sym_hcb *np = sym_get_hcb(shost);
        u_char scsi_mode = INB(np, nc_stest4) & SMODE;

        /*
         *  Notify user.
         */
        printf("%s: SCSI BUS mode change from %s to %s.\n", sym_name(np),
                sym_scsi_bus_mode(np->scsi_mode), sym_scsi_bus_mode(scsi_mode));

        /*
         *  Should suspend command processing for a few seconds and 
         *  reinitialize all except the chip.
         */
        sym_start_up(shost, 2);
}

/*
 *  chip exception handler for SCSI parity error.
 *
 *  When the chip detects a SCSI parity error and is 
 *  currently executing a (CH)MOV instruction, it does 
 *  not interrupt immediately, but tries to finish the 
 *  transfer of the current scatter entry before 
 *  interrupting. The following situations may occur:
 *
 *  - The complete scatter entry has been transferred 
 *    without the device having changed phase.
 *    The chip will then interrupt with the DSP pointing 
 *    to the instruction that follows the MOV.
 *
 *  - A phase mismatch occurs before the MOV finished 
 *    and phase errors are to be handled by the C code.
 *    The chip will then interrupt with both PAR and MA 
 *    conditions set.
 *
 *  - A phase mismatch occurs before the MOV finished and 
 *    phase errors are to be handled by SCRIPTS.
 *    The chip will load the DSP with the phase mismatch 
 *    JUMP address and interrupt the host processor.
 */
static void sym_int_par (struct sym_hcb *np, u_short sist)
{
        u_char  hsts    = INB(np, HS_PRT);
        u32     dsp     = INL(np, nc_dsp);
        u32     dbc     = INL(np, nc_dbc);
        u32     dsa     = INL(np, nc_dsa);
        u_char  sbcl    = INB(np, nc_sbcl);
        u_char  cmd     = dbc >> 24;
        int phase       = cmd & 7;
        struct sym_ccb *cp      = sym_ccb_from_dsa(np, dsa);

        if (printk_ratelimit())
                printf("%s: SCSI parity error detected: SCR1=%d DBC=%x SBCL=%x\n",
                        sym_name(np), hsts, dbc, sbcl);

        /*
         *  Check that the chip is connected to the SCSI BUS.
         */
        if (!(INB(np, nc_scntl1) & ISCON)) {
                sym_recover_scsi_int(np, HS_UNEXPECTED);
                return;
        }

        /*
         *  If the nexus is not clearly identified, reset the bus.
         *  We will try to do better later.
         */
        if (!cp)
                goto reset_all;

        /*
         *  Check instruction was a MOV, direction was INPUT and 
         *  ATN is asserted.
         */
        if ((cmd & 0xc0) || !(phase & 1) || !(sbcl & 0x8))
                goto reset_all;

        /*
         *  Keep track of the parity error.
         */
        OUTONB(np, HF_PRT, HF_EXT_ERR);
        cp->xerr_status |= XE_PARITY_ERR;

        /*
         *  Prepare the message to send to the device.
         */
        np->msgout[0] = (phase == 7) ? M_PARITY : M_ID_ERROR;

        /*
         *  If the old phase was DATA IN phase, we have to deal with
         *  the 3 situations described above.
         *  For other input phases (MSG IN and STATUS), the device 
         *  must resend the whole thing that failed parity checking 
         *  or signal error. So, jumping to dispatcher should be OK.
         */
        if (phase == 1 || phase == 5) {
                /* Phase mismatch handled by SCRIPTS */
                if (dsp == SCRIPTB_BA(np, pm_handle))
                        OUTL_DSP(np, dsp);
                /* Phase mismatch handled by the C code */
                else if (sist & MA)
                        sym_int_ma (np);
                /* No phase mismatch occurred */
                else {
                        sym_set_script_dp (np, cp, dsp);
                        OUTL_DSP(np, SCRIPTA_BA(np, dispatch));
                }
        }
        else if (phase == 7)    /* We definitely cannot handle parity errors */
#if 1                           /* in message-in phase due to the relection  */
                goto reset_all; /* path and various message anticipations.   */
#else
                OUTL_DSP(np, SCRIPTA_BA(np, clrack));
#endif
        else
                OUTL_DSP(np, SCRIPTA_BA(np, dispatch));
        return;

reset_all:
        sym_start_reset(np);
        return;
}

/*
 *  chip exception handler for phase errors.
 *
 *  We have to construct a new transfer descriptor,
 *  to transfer the rest of the current block.
 */
static void sym_int_ma (struct sym_hcb *np)
{
        u32     dbc;
        u32     rest;
        u32     dsp;
        u32     dsa;
        u32     nxtdsp;
        u32     *vdsp;
        u32     oadr, olen;
        u32     *tblp;
        u32     newcmd;
        u_int   delta;
        u_char  cmd;
        u_char  hflags, hflags0;
        struct  sym_pmc *pm;
        struct sym_ccb *cp;

        dsp     = INL(np, nc_dsp);
        dbc     = INL(np, nc_dbc);
        dsa     = INL(np, nc_dsa);

        cmd     = dbc >> 24;
        rest    = dbc & 0xffffff;
        delta   = 0;

        /*
         *  locate matching cp if any.
         */
        cp = sym_ccb_from_dsa(np, dsa);

        /*
         *  Donnot take into account dma fifo and various buffers in 
         *  INPUT phase since the chip flushes everything before 
         *  raising the MA interrupt for interrupted INPUT phases.
         *  For DATA IN phase, we will check for the SWIDE later.
         */
        if ((cmd & 7) != 1 && (cmd & 7) != 5) {
                u_char ss0, ss2;

                if (np->features & FE_DFBC)
                        delta = INW(np, nc_dfbc);
                else {
                        u32 dfifo;

                        /*
                         * Read DFIFO, CTEST[4-6] using 1 PCI bus ownership.
                         */
                        dfifo = INL(np, nc_dfifo);

                        /*
                         *  Calculate remaining bytes in DMA fifo.
                         *  (CTEST5 = dfifo >> 16)
                         */
                        if (dfifo & (DFS << 16))
                                delta = ((((dfifo >> 8) & 0x300) |
                                          (dfifo & 0xff)) - rest) & 0x3ff;
                        else
                                delta = ((dfifo & 0xff) - rest) & 0x7f;
                }

                /*
                 *  The data in the dma fifo has not been transfered to
                 *  the target -> add the amount to the rest
                 *  and clear the data.
                 *  Check the sstat2 register in case of wide transfer.
                 */
                rest += delta;
                ss0  = INB(np, nc_sstat0);
                if (ss0 & OLF) rest++;
                if (!(np->features & FE_C10))
                        if (ss0 & ORF) rest++;
                if (cp && (cp->phys.select.sel_scntl3 & EWS)) {
                        ss2 = INB(np, nc_sstat2);
                        if (ss2 & OLF1) rest++;
                        if (!(np->features & FE_C10))
                                if (ss2 & ORF1) rest++;
                }

                /*
                 *  Clear fifos.
                 */
                OUTB(np, nc_ctest3, np->rv_ctest3 | CLF);       /* dma fifo  */
                OUTB(np, nc_stest3, TE|CSF);            /* scsi fifo */
        }

        /*
         *  log the information
         */
        if (DEBUG_FLAGS & (DEBUG_TINY|DEBUG_PHASE))
                printf ("P%x%x RL=%d D=%d ", cmd&7, INB(np, nc_sbcl)&7,
                        (unsigned) rest, (unsigned) delta);

        /*
         *  try to find the interrupted script command,
         *  and the address at which to continue.
         */
        vdsp    = NULL;
        nxtdsp  = 0;
        if      (dsp >  np->scripta_ba &&
                 dsp <= np->scripta_ba + np->scripta_sz) {
                vdsp = (u32 *)((char*)np->scripta0 + (dsp-np->scripta_ba-8));
                nxtdsp = dsp;
        }
        else if (dsp >  np->scriptb_ba &&
                 dsp <= np->scriptb_ba + np->scriptb_sz) {
                vdsp = (u32 *)((char*)np->scriptb0 + (dsp-np->scriptb_ba-8));
                nxtdsp = dsp;
        }

        /*
         *  log the information
         */
        if (DEBUG_FLAGS & DEBUG_PHASE) {
                printf ("\nCP=%p DSP=%x NXT=%x VDSP=%p CMD=%x ",
                        cp, (unsigned)dsp, (unsigned)nxtdsp, vdsp, cmd);
        }

        if (!vdsp) {
                printf ("%s: interrupted SCRIPT address not found.\n", 
                        sym_name (np));
                goto reset_all;
        }

        if (!cp) {
                printf ("%s: SCSI phase error fixup: CCB already dequeued.\n", 
                        sym_name (np));
                goto reset_all;
        }

        /*
         *  get old startaddress and old length.
         */
        oadr = scr_to_cpu(vdsp[1]);

        if (cmd & 0x10) {       /* Table indirect */
                tblp = (u32 *) ((char*) &cp->phys + oadr);
                olen = scr_to_cpu(tblp[0]);
                oadr = scr_to_cpu(tblp[1]);
        } else {
                tblp = (u32 *) 0;
                olen = scr_to_cpu(vdsp[0]) & 0xffffff;
        }

        if (DEBUG_FLAGS & DEBUG_PHASE) {
                printf ("OCMD=%x\nTBLP=%p OLEN=%x OADR=%x\n",
                        (unsigned) (scr_to_cpu(vdsp[0]) >> 24),
                        tblp,
                        (unsigned) olen,
                        (unsigned) oadr);
        }

        /*
         *  check cmd against assumed interrupted script command.
         *  If dt data phase, the MOVE instruction hasn't bit 4 of 
         *  the phase.
         */
        if (((cmd & 2) ? cmd : (cmd & ~4)) != (scr_to_cpu(vdsp[0]) >> 24)) {
                sym_print_addr(cp->cmd,
                        "internal error: cmd=%02x != %02x=(vdsp[0] >> 24)\n",
                        cmd, scr_to_cpu(vdsp[0]) >> 24);

                goto reset_all;
        }

        /*
         *  if old phase not dataphase, leave here.
         */
        if (cmd & 2) {
                sym_print_addr(cp->cmd,
                        "phase change %x-%x %d@%08x resid=%d.\n",
                        cmd&7, INB(np, nc_sbcl)&7, (unsigned)olen,
                        (unsigned)oadr, (unsigned)rest);
                goto unexpected_phase;
        }

        /*
         *  Choose the correct PM save area.
         *
         *  Look at the PM_SAVE SCRIPT if you want to understand 
         *  this stuff. The equivalent code is implemented in 
         *  SCRIPTS for the 895A, 896 and 1010 that are able to 
         *  handle PM from the SCRIPTS processor.
         */
        hflags0 = INB(np, HF_PRT);
        hflags = hflags0;

        if (hflags & (HF_IN_PM0 | HF_IN_PM1 | HF_DP_SAVED)) {
                if (hflags & HF_IN_PM0)
                        nxtdsp = scr_to_cpu(cp->phys.pm0.ret);
                else if (hflags & HF_IN_PM1)
                        nxtdsp = scr_to_cpu(cp->phys.pm1.ret);

                if (hflags & HF_DP_SAVED)
                        hflags ^= HF_ACT_PM;
        }

        if (!(hflags & HF_ACT_PM)) {
                pm = &cp->phys.pm0;
                newcmd = SCRIPTA_BA(np, pm0_data);
        }
        else {
                pm = &cp->phys.pm1;
                newcmd = SCRIPTA_BA(np, pm1_data);
        }

        hflags &= ~(HF_IN_PM0 | HF_IN_PM1 | HF_DP_SAVED);
        if (hflags != hflags0)
                OUTB(np, HF_PRT, hflags);

        /*
         *  fillin the phase mismatch context
         */
        pm->sg.addr = cpu_to_scr(oadr + olen - rest);
        pm->sg.size = cpu_to_scr(rest);
        pm->ret     = cpu_to_scr(nxtdsp);

        /*
         *  If we have a SWIDE,
         *  - prepare the address to write the SWIDE from SCRIPTS,
         *  - compute the SCRIPTS address to restart from,
         *  - move current data pointer context by one byte.
         */
        nxtdsp = SCRIPTA_BA(np, dispatch);
        if ((cmd & 7) == 1 && cp && (cp->phys.select.sel_scntl3 & EWS) &&
            (INB(np, nc_scntl2) & WSR)) {
                u32 tmp;

                /*
                 *  Set up the table indirect for the MOVE
                 *  of the residual byte and adjust the data 
                 *  pointer context.
                 */
                tmp = scr_to_cpu(pm->sg.addr);
                cp->phys.wresid.addr = cpu_to_scr(tmp);
                pm->sg.addr = cpu_to_scr(tmp + 1);
                tmp = scr_to_cpu(pm->sg.size);
                cp->phys.wresid.size = cpu_to_scr((tmp&0xff000000) | 1);
                pm->sg.size = cpu_to_scr(tmp - 1);

                /*
                 *  If only the residual byte is to be moved, 
                 *  no PM context is needed.
                 */
                if ((tmp&0xffffff) == 1)
                        newcmd = pm->ret;

                /*
                 *  Prepare the address of SCRIPTS that will 
                 *  move the residual byte to memory.
                 */
                nxtdsp = SCRIPTB_BA(np, wsr_ma_helper);
        }

        if (DEBUG_FLAGS & DEBUG_PHASE) {
                sym_print_addr(cp->cmd, "PM %x %x %x / %x %x %x.\n",
                        hflags0, hflags, newcmd,
                        (unsigned)scr_to_cpu(pm->sg.addr),
                        (unsigned)scr_to_cpu(pm->sg.size),
                        (unsigned)scr_to_cpu(pm->ret));
        }

        /*
         *  Restart the SCRIPTS processor.
         */
        sym_set_script_dp (np, cp, newcmd);
        OUTL_DSP(np, nxtdsp);
        return;

        /*
         *  Unexpected phase changes that occurs when the current phase 
         *  is not a DATA IN or DATA OUT phase are due to error conditions.
         *  Such event may only happen when the SCRIPTS is using a 
         *  multibyte SCSI MOVE.
         *
         *  Phase change                Some possible cause
         *
         *  COMMAND  --> MSG IN SCSI parity error detected by target.
         *  COMMAND  --> STATUS Bad command or refused by target.
         *  MSG OUT  --> MSG IN     Message rejected by target.
         *  MSG OUT  --> COMMAND    Bogus target that discards extended
         *                      negotiation messages.
         *
         *  The code below does not care of the new phase and so 
         *  trusts the target. Why to annoy it ?
         *  If the interrupted phase is COMMAND phase, we restart at
         *  dispatcher.
         *  If a target does not get all the messages after selection, 
         *  the code assumes blindly that the target discards extended 
         *  messages and clears the negotiation status.
         *  If the target does not want all our response to negotiation,
         *  we force a SIR_NEGO_PROTO interrupt (it is a hack that avoids 
         *  bloat for such a should_not_happen situation).
         *  In all other situation, we reset the BUS.
         *  Are these assumptions reasonable ? (Wait and see ...)
         */
unexpected_phase:
        dsp -= 8;
        nxtdsp = 0;

        switch (cmd & 7) {
        case 2: /* COMMAND phase */
                nxtdsp = SCRIPTA_BA(np, dispatch);
                break;
#if 0
        case 3: /* STATUS  phase */
                nxtdsp = SCRIPTA_BA(np, dispatch);
                break;
#endif
        case 6: /* MSG OUT phase */
                /*
                 *  If the device may want to use untagged when we want 
                 *  tagged, we prepare an IDENTIFY without disc. granted, 
                 *  since we will not be able to handle reselect.
                 *  Otherwise, we just don't care.
                 */
                if      (dsp == SCRIPTA_BA(np, send_ident)) {
                        if (cp->tag != NO_TAG && olen - rest <= 3) {
                                cp->host_status = HS_BUSY;
                                np->msgout[0] = IDENTIFY(0, cp->lun);
                                nxtdsp = SCRIPTB_BA(np, ident_break_atn);
                        }
                        else
                                nxtdsp = SCRIPTB_BA(np, ident_break);
                }
                else if (dsp == SCRIPTB_BA(np, send_wdtr) ||
                         dsp == SCRIPTB_BA(np, send_sdtr) ||
                         dsp == SCRIPTB_BA(np, send_ppr)) {
                        nxtdsp = SCRIPTB_BA(np, nego_bad_phase);
                        if (dsp == SCRIPTB_BA(np, send_ppr)) {
                                struct scsi_device *dev = cp->cmd->device;
                                dev->ppr = 0;
                        }
                }
                break;
#if 0
        case 7: /* MSG IN  phase */
                nxtdsp = SCRIPTA_BA(np, clrack);
                break;
#endif
        }

        if (nxtdsp) {
                OUTL_DSP(np, nxtdsp);
                return;
        }

reset_all:
        sym_start_reset(np);
}

/*
 *  chip interrupt handler
 *
 *  In normal situations, interrupt conditions occur one at 
 *  a time. But when something bad happens on the SCSI BUS, 
 *  the chip may raise several interrupt flags before 
 *  stopping and interrupting the CPU. The additionnal 
 *  interrupt flags are stacked in some extra registers 
 *  after the SIP and/or DIP flag has been raised in the 
 *  ISTAT. After the CPU has read the interrupt condition 
 *  flag from SIST or DSTAT, the chip unstacks the other 
 *  interrupt flags and sets the corresponding bits in 
 *  SIST or DSTAT. Since the chip starts stacking once the 
 *  SIP or DIP flag is set, there is a small window of time 
 *  where the stacking does not occur.
 *
 *  Typically, multiple interrupt conditions may happen in 
 *  the following situations:
 *
 *  - SCSI parity error + Phase mismatch  (PAR|MA)
 *    When an parity error is detected in input phase 
 *    and the device switches to msg-in phase inside a 
 *    block MOV.
 *  - SCSI parity error + Unexpected disconnect (PAR|UDC)
 *    When a stupid device does not want to handle the 
 *    recovery of an SCSI parity error.
 *  - Some combinations of STO, PAR, UDC, ...
 *    When using non compliant SCSI stuff, when user is 
 *    doing non compliant hot tampering on the BUS, when 
 *    something really bad happens to a device, etc ...
 *
 *  The heuristic suggested by SYMBIOS to handle 
 *  multiple interrupts is to try unstacking all 
 *  interrupts conditions and to handle them on some 
 *  priority based on error severity.
 *  This will work when the unstacking has been 
 *  successful, but we cannot be 100 % sure of that, 
 *  since the CPU may have been faster to unstack than 
 *  the chip is able to stack. Hmmm ... But it seems that 
 *  such a situation is very unlikely to happen.
 *
 *  If this happen, for example STO caught by the CPU 
 *  then UDC happenning before the CPU have restarted 
 *  the SCRIPTS, the driver may wrongly complete the 
 *  same command on UDC, since the SCRIPTS didn't restart 
 *  and the DSA still points to the same command.
 *  We avoid this situation by setting the DSA to an 
 *  invalid value when the CCB is completed and before 
 *  restarting the SCRIPTS.
 *
 *  Another issue is that we need some section of our 
 *  recovery procedures to be somehow uninterruptible but 
 *  the SCRIPTS processor does not provides such a 
 *  feature. For this reason, we handle recovery preferently 
 *  from the C code and check against some SCRIPTS critical 
 *  sections from the C code.
 *
 *  Hopefully, the interrupt handling of the driver is now 
 *  able to resist to weird BUS error conditions, but donnot 
 *  ask me for any guarantee that it will never fail. :-)
 *  Use at your own decision and risk.
 */

irqreturn_t sym_interrupt(struct Scsi_Host *shost)
{
        struct sym_data *sym_data = shost_priv(shost);
        struct sym_hcb *np = sym_data->ncb;
        struct pci_dev *pdev = sym_data->pdev;
        u_char  istat, istatc;
        u_char  dstat;
        u_short sist;

        /*
         *  interrupt on the fly ?
         *  (SCRIPTS may still be running)
         *
         *  A `dummy read' is needed to ensure that the 
         *  clear of the INTF flag reaches the device 
         *  and that posted writes are flushed to memory
         *  before the scanning of the DONE queue.
         *  Note that SCRIPTS also (dummy) read to memory 
         *  prior to deliver the INTF interrupt condition.
         */
        istat = INB(np, nc_istat);
        if (istat & INTF) {
                OUTB(np, nc_istat, (istat & SIGP) | INTF | np->istat_sem);
                istat |= INB(np, nc_istat);             /* DUMMY READ */
                if (DEBUG_FLAGS & DEBUG_TINY) printf ("F ");
                sym_wakeup_done(np);
        }

        if (!(istat & (SIP|DIP)))
                return (istat & INTF) ? IRQ_HANDLED : IRQ_NONE;

#if 0   /* We should never get this one */
        if (istat & CABRT)
                OUTB(np, nc_istat, CABRT);
#endif

        /*
         *  PAR and MA interrupts may occur at the same time,
         *  and we need to know of both in order to handle 
         *  this situation properly. We try to unstack SCSI 
         *  interrupts for that reason. BTW, I dislike a LOT 
         *  such a loop inside the interrupt routine.
         *  Even if DMA interrupt stacking is very unlikely to 
         *  happen, we also try unstacking these ones, since 
         *  this has no performance impact.
         */
        sist    = 0;
        dstat   = 0;
        istatc  = istat;
        do {
                if (istatc & SIP)
                        sist  |= INW(np, nc_sist);
                if (istatc & DIP)
                        dstat |= INB(np, nc_dstat);
                istatc = INB(np, nc_istat);
                istat |= istatc;

                /* Prevent deadlock waiting on a condition that may
                 * never clear. */
                if (unlikely(sist == 0xffff && dstat == 0xff)) {
                        if (pci_channel_offline(pdev))
                                return IRQ_NONE;
                }
        } while (istatc & (SIP|DIP));

        if (DEBUG_FLAGS & DEBUG_TINY)
                printf ("<%d|%x:%x|%x:%x>",
                        (int)INB(np, nc_scr0),
                        dstat,sist,
                        (unsigned)INL(np, nc_dsp),
                        (unsigned)INL(np, nc_dbc));
        /*
         *  On paper, a memory read barrier may be needed here to 
         *  prevent out of order LOADs by the CPU from having 
         *  prefetched stale data prior to DMA having occurred.
         *  And since we are paranoid ... :)
         */
        MEMORY_READ_BARRIER();

        /*
         *  First, interrupts we want to service cleanly.
         *
         *  Phase mismatch (MA) is the most frequent interrupt 
         *  for chip earlier than the 896 and so we have to service 
         *  it as quickly as possible.
         *  A SCSI parity error (PAR) may be combined with a phase 
         *  mismatch condition (MA).
         *  Programmed interrupts (SIR) are used to call the C code 
         *  from SCRIPTS.
         *  The single step interrupt (SSI) is not used in this 
         *  driver.
         */
        if (!(sist  & (STO|GEN|HTH|SGE|UDC|SBMC|RST)) &&
            !(dstat & (MDPE|BF|ABRT|IID))) {
                if      (sist & PAR)    sym_int_par (np, sist);
                else if (sist & MA)     sym_int_ma (np);
                else if (dstat & SIR)   sym_int_sir(np);
                else if (dstat & SSI)   OUTONB_STD();
                else                    goto unknown_int;
                return IRQ_HANDLED;
        }

        /*
         *  Now, interrupts that donnot happen in normal 
         *  situations and that we may need to recover from.
         *
         *  On SCSI RESET (RST), we reset everything.
         *  On SCSI BUS MODE CHANGE (SBMC), we complete all 
         *  active CCBs with RESET status, prepare all devices 
         *  for negotiating again and restart the SCRIPTS.
         *  On STO and UDC, we complete the CCB with the corres- 
         *  ponding status and restart the SCRIPTS.
         */
        if (sist & RST) {
                printf("%s: SCSI BUS reset detected.\n", sym_name(np));
                sym_start_up(shost, 1);
                return IRQ_HANDLED;
        }

        OUTB(np, nc_ctest3, np->rv_ctest3 | CLF);       /* clear dma fifo  */
        OUTB(np, nc_stest3, TE|CSF);            /* clear scsi fifo */

        if (!(sist  & (GEN|HTH|SGE)) &&
            !(dstat & (MDPE|BF|ABRT|IID))) {
                if      (sist & SBMC)   sym_int_sbmc(shost);
                else if (sist & STO)    sym_int_sto (np);
                else if (sist & UDC)    sym_int_udc (np);
                else                    goto unknown_int;
                return IRQ_HANDLED;
        }

        /*
         *  Now, interrupts we are not able to recover cleanly.
         *
         *  Log message for hard errors.
         *  Reset everything.
         */

        sym_log_hard_error(shost, sist, dstat);

        if ((sist & (GEN|HTH|SGE)) ||
                (dstat & (MDPE|BF|ABRT|IID))) {
                sym_start_reset(np);
                return IRQ_HANDLED;
        }

unknown_int:
        /*
         *  We just miss the cause of the interrupt. :(
         *  Print a message. The timeout will do the real work.
         */
        printf( "%s: unknown interrupt(s) ignored, "
                "ISTAT=0x%x DSTAT=0x%x SIST=0x%x\n",
                sym_name(np), istat, dstat, sist);
        return IRQ_NONE;
}

/*
 *  Dequeue from the START queue all CCBs that match 
 *  a given target/lun/task condition (-1 means all),
 *  and move them from the BUSY queue to the COMP queue 
 *  with DID_SOFT_ERROR status condition.
 *  This function is used during error handling/recovery.
 *  It is called with SCRIPTS not running.
 */
static int 
sym_dequeue_from_squeue(struct sym_hcb *np, int i, int target, int lun, int task)
{
        int j;
        struct sym_ccb *cp;

        /*
         *  Make sure the starting index is within range.
         */
        assert((i >= 0) && (i < 2*MAX_QUEUE));

        /*
         *  Walk until end of START queue and dequeue every job 
         *  that matches the target/lun/task condition.
         */
        j = i;
        while (i != np->squeueput) {
                cp = sym_ccb_from_dsa(np, scr_to_cpu(np->squeue[i]));
                assert(cp);
#ifdef SYM_CONF_IARB_SUPPORT
                /* Forget hints for IARB, they may be no longer relevant */
                cp->host_flags &= ~HF_HINT_IARB;
#endif
                if ((target == -1 || cp->target == target) &&