atari_NCR5380: Introduce FLAG_TAGGED_QUEUING

[cascardo/linux.git] / drivers / scsi / atari_NCR5380.c

/*
 * NCR 5380 generic driver routines.  These should make it *trivial*
 *      to implement 5380 SCSI drivers under Linux with a non-trantor
 *      architecture.
 *
 *      Note that these routines also work with NR53c400 family chips.
 *
 * Copyright 1993, Drew Eckhardt
 *      Visionary Computing
 *      (Unix and Linux consulting and custom programming)
 *      drew@colorado.edu
 *      +1 (303) 666-5836
 *
 * For more information, please consult
 *
 * NCR 5380 Family
 * SCSI Protocol Controller
 * Databook
 *
 * NCR Microelectronics
 * 1635 Aeroplaza Drive
 * Colorado Springs, CO 80916
 * 1+ (719) 578-3400
 * 1+ (800) 334-5454
 */

/*
 * ++roman: To port the 5380 driver to the Atari, I had to do some changes in
 * this file, too:
 *
 *  - Some of the debug statements were incorrect (undefined variables and the
 *    like). I fixed that.
 *
 *  - In information_transfer(), I think a #ifdef was wrong. Looking at the
 *    possible DMA transfer size should also happen for REAL_DMA. I added this
 *    in the #if statement.
 *
 *  - When using real DMA, information_transfer() should return in a DATAOUT
 *    phase after starting the DMA. It has nothing more to do.
 *
 *  - The interrupt service routine should run main after end of DMA, too (not
 *    only after RESELECTION interrupts). Additionally, it should _not_ test
 *    for more interrupts after running main, since a DMA process may have
 *    been started and interrupts are turned on now. The new int could happen
 *    inside the execution of NCR5380_intr(), leading to recursive
 *    calls.
 *
 *  - I've added a function merge_contiguous_buffers() that tries to
 *    merge scatter-gather buffers that are located at contiguous
 *    physical addresses and can be processed with the same DMA setup.
 *    Since most scatter-gather operations work on a page (4K) of
 *    4 buffers (1K), in more than 90% of all cases three interrupts and
 *    DMA setup actions are saved.
 *
 * - I've deleted all the stuff for AUTOPROBE_IRQ, REAL_DMA_POLL, PSEUDO_DMA
 *    and USLEEP, because these were messing up readability and will never be
 *    needed for Atari SCSI.
 *
 * - I've revised the NCR5380_main() calling scheme (relax the 'main_running'
 *   stuff), and 'main' is executed in a bottom half if awoken by an
 *   interrupt.
 *
 * - The code was quite cluttered up by "#if (NDEBUG & NDEBUG_*) printk..."
 *   constructs. In my eyes, this made the source rather unreadable, so I
 *   finally replaced that by the *_PRINTK() macros.
 *
 */

/*
 * Further development / testing that should be done :
 * 1.  Test linked command handling code after Eric is ready with
 *     the high level code.
 */

/* Adapted for the sun3 by Sam Creasey. */

#include <scsi/scsi_dbg.h>
#include <scsi/scsi_transport_spi.h>

#if (NDEBUG & NDEBUG_LISTS)
#define LIST(x, y)                                              \
        do {                                                    \
                printk("LINE:%d   Adding %p to %p\n",           \
                       __LINE__, (void*)(x), (void*)(y));       \
                if ((x) == (y))                                 \
                        udelay(5);                              \
        } while (0)
#define REMOVE(w, x, y, z)                                      \
        do {                                                    \
                printk("LINE:%d   Removing: %p->%p  %p->%p \n", \
                       __LINE__, (void*)(w), (void*)(x),        \
                       (void*)(y), (void*)(z));                 \
                if ((x) == (y))                                 \
                        udelay(5);                              \
        } while (0)
#else
#define LIST(x,y)
#define REMOVE(w,x,y,z)
#endif

#ifndef notyet
#undef LINKED
#endif

/*
 * Design
 *
 * This is a generic 5380 driver.  To use it on a different platform,
 * one simply writes appropriate system specific macros (ie, data
 * transfer - some PC's will use the I/O bus, 68K's must use
 * memory mapped) and drops this file in their 'C' wrapper.
 *
 * As far as command queueing, two queues are maintained for
 * each 5380 in the system - commands that haven't been issued yet,
 * and commands that are currently executing.  This means that an
 * unlimited number of commands may be queued, letting
 * more commands propagate from the higher driver levels giving higher
 * throughput.  Note that both I_T_L and I_T_L_Q nexuses are supported,
 * allowing multiple commands to propagate all the way to a SCSI-II device
 * while a command is already executing.
 *
 *
 * Issues specific to the NCR5380 :
 *
 * When used in a PIO or pseudo-dma mode, the NCR5380 is a braindead
 * piece of hardware that requires you to sit in a loop polling for
 * the REQ signal as long as you are connected.  Some devices are
 * brain dead (ie, many TEXEL CD ROM drives) and won't disconnect
 * while doing long seek operations.
 *
 * The workaround for this is to keep track of devices that have
 * disconnected.  If the device hasn't disconnected, for commands that
 * should disconnect, we do something like
 *
 * while (!REQ is asserted) { sleep for N usecs; poll for M usecs }
 *
 * Some tweaking of N and M needs to be done.  An algorithm based
 * on "time to data" would give the best results as long as short time
 * to datas (ie, on the same track) were considered, however these
 * broken devices are the exception rather than the rule and I'd rather
 * spend my time optimizing for the normal case.
 *
 * Architecture :
 *
 * At the heart of the design is a coroutine, NCR5380_main,
 * which is started from a workqueue for each NCR5380 host in the
 * system.  It attempts to establish I_T_L or I_T_L_Q nexuses by
 * removing the commands from the issue queue and calling
 * NCR5380_select() if a nexus is not established.
 *
 * Once a nexus is established, the NCR5380_information_transfer()
 * phase goes through the various phases as instructed by the target.
 * if the target goes into MSG IN and sends a DISCONNECT message,
 * the command structure is placed into the per instance disconnected
 * queue, and NCR5380_main tries to find more work.  If the target is
 * idle for too long, the system will try to sleep.
 *
 * If a command has disconnected, eventually an interrupt will trigger,
 * calling NCR5380_intr()  which will in turn call NCR5380_reselect
 * to reestablish a nexus.  This will run main if necessary.
 *
 * On command termination, the done function will be called as
 * appropriate.
 *
 * SCSI pointers are maintained in the SCp field of SCSI command
 * structures, being initialized after the command is connected
 * in NCR5380_select, and set as appropriate in NCR5380_information_transfer.
 * Note that in violation of the standard, an implicit SAVE POINTERS operation
 * is done, since some BROKEN disks fail to issue an explicit SAVE POINTERS.
 */

/*
 * Using this file :
 * This file a skeleton Linux SCSI driver for the NCR 5380 series
 * of chips.  To use it, you write an architecture specific functions
 * and macros and include this file in your driver.
 *
 * These macros control options :
 * AUTOSENSE - if defined, REQUEST SENSE will be performed automatically
 *      for commands that return with a CHECK CONDITION status.
 *
 * DIFFERENTIAL - if defined, NCR53c81 chips will use external differential
 *      transceivers.
 *
 * LINKED - if defined, linked commands are supported.
 *
 * REAL_DMA - if defined, REAL DMA is used during the data transfer phases.
 *
 * SUPPORT_TAGS - if defined, SCSI-2 tagged queuing is used where possible
 *
 * These macros MUST be defined :
 *
 * NCR5380_read(register)  - read from the specified register
 *
 * NCR5380_write(register, value) - write to the specific register
 *
 * NCR5380_implementation_fields  - additional fields needed for this
 *      specific implementation of the NCR5380
 *
 * Either real DMA *or* pseudo DMA may be implemented
 * REAL functions :
 * NCR5380_REAL_DMA should be defined if real DMA is to be used.
 * Note that the DMA setup functions should return the number of bytes
 *      that they were able to program the controller for.
 *
 * Also note that generic i386/PC versions of these macros are
 *      available as NCR5380_i386_dma_write_setup,
 *      NCR5380_i386_dma_read_setup, and NCR5380_i386_dma_residual.
 *
 * NCR5380_dma_write_setup(instance, src, count) - initialize
 * NCR5380_dma_read_setup(instance, dst, count) - initialize
 * NCR5380_dma_residual(instance); - residual count
 *
 * PSEUDO functions :
 * NCR5380_pwrite(instance, src, count)
 * NCR5380_pread(instance, dst, count);
 *
 * The generic driver is initialized by calling NCR5380_init(instance),
 * after setting the appropriate host specific fields and ID.  If the
 * driver wishes to autoprobe for an IRQ line, the NCR5380_probe_irq(instance,
 * possible) function may be used.
 */

static struct Scsi_Host *first_instance = NULL;
static struct scsi_host_template *the_template = NULL;

/* Macros ease life... :-) */
#define SETUP_HOSTDATA(in)                              \
    struct NCR5380_hostdata *hostdata =                 \
        (struct NCR5380_hostdata *)(in)->hostdata
#define HOSTDATA(in) ((struct NCR5380_hostdata *)(in)->hostdata)

#define NEXT(cmd)               ((struct scsi_cmnd *)(cmd)->host_scribble)
#define SET_NEXT(cmd,next)      ((cmd)->host_scribble = (void *)(next))
#define NEXTADDR(cmd)           ((struct scsi_cmnd **)&(cmd)->host_scribble)

#define HOSTNO          instance->host_no
#define H_NO(cmd)       (cmd)->device->host->host_no

#ifdef SUPPORT_TAGS

/*
 * Functions for handling tagged queuing
 * =====================================
 *
 * ++roman (01/96): Now I've implemented SCSI-2 tagged queuing. Some notes:
 *
 * Using consecutive numbers for the tags is no good idea in my eyes. There
 * could be wrong re-usings if the counter (8 bit!) wraps and some early
 * command has been preempted for a long time. My solution: a bitfield for
 * remembering used tags.
 *
 * There's also the problem that each target has a certain queue size, but we
 * cannot know it in advance :-( We just see a QUEUE_FULL status being
 * returned. So, in this case, the driver internal queue size assumption is
 * reduced to the number of active tags if QUEUE_FULL is returned by the
 * target. The command is returned to the mid-level, but with status changed
 * to BUSY, since --as I've seen-- the mid-level can't handle QUEUE_FULL
 * correctly.
 *
 * We're also not allowed running tagged commands as long as an untagged
 * command is active. And REQUEST SENSE commands after a contingent allegiance
 * condition _must_ be untagged. To keep track whether an untagged command has
 * been issued, the host->busy array is still employed, as it is without
 * support for tagged queuing.
 *
 * One could suspect that there are possible race conditions between
 * is_lun_busy(), cmd_get_tag() and cmd_free_tag(). But I think this isn't the
 * case: is_lun_busy() and cmd_get_tag() are both called from NCR5380_main(),
 * which already guaranteed to be running at most once. It is also the only
 * place where tags/LUNs are allocated. So no other allocation can slip
 * between that pair, there could only happen a reselection, which can free a
 * tag, but that doesn't hurt. Only the sequence in cmd_free_tag() becomes
 * important: the tag bit must be cleared before 'nr_allocated' is decreased.
 */

typedef struct {
        DECLARE_BITMAP(allocated, MAX_TAGS);
        int nr_allocated;
        int queue_size;
} TAG_ALLOC;

static TAG_ALLOC TagAlloc[8][8];        /* 8 targets and 8 LUNs */


static void __init init_tags(struct NCR5380_hostdata *hostdata)
{
        int target, lun;
        TAG_ALLOC *ta;

        if (!(hostdata->flags & FLAG_TAGGED_QUEUING))
                return;

        for (target = 0; target < 8; ++target) {
                for (lun = 0; lun < 8; ++lun) {
                        ta = &TagAlloc[target][lun];
                        bitmap_zero(ta->allocated, MAX_TAGS);
                        ta->nr_allocated = 0;
                        /* At the beginning, assume the maximum queue size we could
                         * support (MAX_TAGS). This value will be decreased if the target
                         * returns QUEUE_FULL status.
                         */
                        ta->queue_size = MAX_TAGS;
                }
        }
}


/* Check if we can issue a command to this LUN: First see if the LUN is marked
 * busy by an untagged command. If the command should use tagged queuing, also
 * check that there is a free tag and the target's queue won't overflow. This
 * function should be called with interrupts disabled to avoid race
 * conditions.
 */

static int is_lun_busy(struct scsi_cmnd *cmd, int should_be_tagged)
{
        u8 lun = cmd->device->lun;
        SETUP_HOSTDATA(cmd->device->host);

        if (hostdata->busy[cmd->device->id] & (1 << lun))
                return 1;
        if (!should_be_tagged ||
            !(hostdata->flags & FLAG_TAGGED_QUEUING) ||
            !cmd->device->tagged_supported)
                return 0;
        if (TagAlloc[cmd->device->id][lun].nr_allocated >=
            TagAlloc[cmd->device->id][lun].queue_size) {
                dprintk(NDEBUG_TAGS, "scsi%d: target %d lun %d: no free tags\n",
                           H_NO(cmd), cmd->device->id, lun);
                return 1;
        }
        return 0;
}


/* Allocate a tag for a command (there are no checks anymore, check_lun_busy()
 * must be called before!), or reserve the LUN in 'busy' if the command is
 * untagged.
 */

static void cmd_get_tag(struct scsi_cmnd *cmd, int should_be_tagged)
{
        u8 lun = cmd->device->lun;
        SETUP_HOSTDATA(cmd->device->host);

        /* If we or the target don't support tagged queuing, allocate the LUN for
         * an untagged command.
         */
        if (!should_be_tagged ||
            !(hostdata->flags & FLAG_TAGGED_QUEUING) ||
            !cmd->device->tagged_supported) {
                cmd->tag = TAG_NONE;
                hostdata->busy[cmd->device->id] |= (1 << lun);
                dprintk(NDEBUG_TAGS, "scsi%d: target %d lun %d now allocated by untagged "
                           "command\n", H_NO(cmd), cmd->device->id, lun);
        } else {
                TAG_ALLOC *ta = &TagAlloc[cmd->device->id][lun];

                cmd->tag = find_first_zero_bit(ta->allocated, MAX_TAGS);
                set_bit(cmd->tag, ta->allocated);
                ta->nr_allocated++;
                dprintk(NDEBUG_TAGS, "scsi%d: using tag %d for target %d lun %d "
                           "(now %d tags in use)\n",
                           H_NO(cmd), cmd->tag, cmd->device->id,
                           lun, ta->nr_allocated);
        }
}


/* Mark the tag of command 'cmd' as free, or in case of an untagged command,
 * unlock the LUN.
 */

static void cmd_free_tag(struct scsi_cmnd *cmd)
{
        u8 lun = cmd->device->lun;
        SETUP_HOSTDATA(cmd->device->host);

        if (cmd->tag == TAG_NONE) {
                hostdata->busy[cmd->device->id] &= ~(1 << lun);
                dprintk(NDEBUG_TAGS, "scsi%d: target %d lun %d untagged cmd finished\n",
                           H_NO(cmd), cmd->device->id, lun);
        } else if (cmd->tag >= MAX_TAGS) {
                printk(KERN_NOTICE "scsi%d: trying to free bad tag %d!\n",
                       H_NO(cmd), cmd->tag);
        } else {
                TAG_ALLOC *ta = &TagAlloc[cmd->device->id][lun];
                clear_bit(cmd->tag, ta->allocated);
                ta->nr_allocated--;
                dprintk(NDEBUG_TAGS, "scsi%d: freed tag %d for target %d lun %d\n",
                           H_NO(cmd), cmd->tag, cmd->device->id, lun);
        }
}


static void free_all_tags(struct NCR5380_hostdata *hostdata)
{
        int target, lun;
        TAG_ALLOC *ta;

        if (!(hostdata->flags & FLAG_TAGGED_QUEUING))
                return;

        for (target = 0; target < 8; ++target) {
                for (lun = 0; lun < 8; ++lun) {
                        ta = &TagAlloc[target][lun];
                        bitmap_zero(ta->allocated, MAX_TAGS);
                        ta->nr_allocated = 0;
                }
        }
}

#endif /* SUPPORT_TAGS */


/*
 * Function: void merge_contiguous_buffers( struct scsi_cmnd *cmd )
 *
 * Purpose: Try to merge several scatter-gather requests into one DMA
 *    transfer. This is possible if the scatter buffers lie on
 *    physical contiguous addresses.
 *
 * Parameters: struct scsi_cmnd *cmd
 *    The command to work on. The first scatter buffer's data are
 *    assumed to be already transferred into ptr/this_residual.
 */

static void merge_contiguous_buffers(struct scsi_cmnd *cmd)
{
#if !defined(CONFIG_SUN3)
        unsigned long endaddr;
#if (NDEBUG & NDEBUG_MERGING)
        unsigned long oldlen = cmd->SCp.this_residual;
        int cnt = 1;
#endif

        for (endaddr = virt_to_phys(cmd->SCp.ptr + cmd->SCp.this_residual - 1) + 1;
             cmd->SCp.buffers_residual &&
             virt_to_phys(sg_virt(&cmd->SCp.buffer[1])) == endaddr;) {
                dprintk(NDEBUG_MERGING, "VTOP(%p) == %08lx -> merging\n",
                           page_address(sg_page(&cmd->SCp.buffer[1])), endaddr);
#if (NDEBUG & NDEBUG_MERGING)
                ++cnt;
#endif
                ++cmd->SCp.buffer;
                --cmd->SCp.buffers_residual;
                cmd->SCp.this_residual += cmd->SCp.buffer->length;
                endaddr += cmd->SCp.buffer->length;
        }
#if (NDEBUG & NDEBUG_MERGING)
        if (oldlen != cmd->SCp.this_residual)
                dprintk(NDEBUG_MERGING, "merged %d buffers from %p, new length %08x\n",
                           cnt, cmd->SCp.ptr, cmd->SCp.this_residual);
#endif
#endif /* !defined(CONFIG_SUN3) */
}

/**
 * initialize_SCp - init the scsi pointer field
 * @cmd: command block to set up
 *
 * Set up the internal fields in the SCSI command.
 */

static inline void initialize_SCp(struct scsi_cmnd *cmd)
{
        /*
         * Initialize the Scsi Pointer field so that all of the commands in the
         * various queues are valid.
         */

        if (scsi_bufflen(cmd)) {
                cmd->SCp.buffer = scsi_sglist(cmd);
                cmd->SCp.buffers_residual = scsi_sg_count(cmd) - 1;
                cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
                cmd->SCp.this_residual = cmd->SCp.buffer->length;
                /* ++roman: Try to merge some scatter-buffers if they are at
                 * contiguous physical addresses.
                 */
                merge_contiguous_buffers(cmd);
        } else {
                cmd->SCp.buffer = NULL;
                cmd->SCp.buffers_residual = 0;
                cmd->SCp.ptr = NULL;
                cmd->SCp.this_residual = 0;
        }
}

#include <linux/delay.h>

#if NDEBUG
static struct {
        unsigned char mask;
        const char *name;
} signals[] = {
        { SR_DBP, "PARITY"}, { SR_RST, "RST" }, { SR_BSY, "BSY" },
        { SR_REQ, "REQ" }, { SR_MSG, "MSG" }, { SR_CD,  "CD" }, { SR_IO, "IO" },
        { SR_SEL, "SEL" }, {0, NULL}
}, basrs[] = {
        {BASR_ATN, "ATN"}, {BASR_ACK, "ACK"}, {0, NULL}
}, icrs[] = {
        {ICR_ASSERT_RST, "ASSERT RST"},{ICR_ASSERT_ACK, "ASSERT ACK"},
        {ICR_ASSERT_BSY, "ASSERT BSY"}, {ICR_ASSERT_SEL, "ASSERT SEL"},
        {ICR_ASSERT_ATN, "ASSERT ATN"}, {ICR_ASSERT_DATA, "ASSERT DATA"},
        {0, NULL}
}, mrs[] = {
        {MR_BLOCK_DMA_MODE, "MODE BLOCK DMA"}, {MR_TARGET, "MODE TARGET"},
        {MR_ENABLE_PAR_CHECK, "MODE PARITY CHECK"}, {MR_ENABLE_PAR_INTR,
        "MODE PARITY INTR"}, {MR_ENABLE_EOP_INTR,"MODE EOP INTR"},
        {MR_MONITOR_BSY, "MODE MONITOR BSY"},
        {MR_DMA_MODE, "MODE DMA"}, {MR_ARBITRATE, "MODE ARBITRATION"},
        {0, NULL}
};

/**
 * NCR5380_print - print scsi bus signals
 * @instance: adapter state to dump
 *
 * Print the SCSI bus signals for debugging purposes
 */

static void NCR5380_print(struct Scsi_Host *instance)
{
        unsigned char status, data, basr, mr, icr, i;
        unsigned long flags;

        local_irq_save(flags);
        data = NCR5380_read(CURRENT_SCSI_DATA_REG);
        status = NCR5380_read(STATUS_REG);
        mr = NCR5380_read(MODE_REG);
        icr = NCR5380_read(INITIATOR_COMMAND_REG);
        basr = NCR5380_read(BUS_AND_STATUS_REG);
        local_irq_restore(flags);
        printk("STATUS_REG: %02x ", status);
        for (i = 0; signals[i].mask; ++i)
                if (status & signals[i].mask)
                        printk(",%s", signals[i].name);
        printk("\nBASR: %02x ", basr);
        for (i = 0; basrs[i].mask; ++i)
                if (basr & basrs[i].mask)
                        printk(",%s", basrs[i].name);
        printk("\nICR: %02x ", icr);
        for (i = 0; icrs[i].mask; ++i)
                if (icr & icrs[i].mask)
                        printk(",%s", icrs[i].name);
        printk("\nMODE: %02x ", mr);
        for (i = 0; mrs[i].mask; ++i)
                if (mr & mrs[i].mask)
                        printk(",%s", mrs[i].name);
        printk("\n");
}

static struct {
        unsigned char value;
        const char *name;
} phases[] = {
        {PHASE_DATAOUT, "DATAOUT"}, {PHASE_DATAIN, "DATAIN"}, {PHASE_CMDOUT, "CMDOUT"},
        {PHASE_STATIN, "STATIN"}, {PHASE_MSGOUT, "MSGOUT"}, {PHASE_MSGIN, "MSGIN"},
        {PHASE_UNKNOWN, "UNKNOWN"}
};

/**
 * NCR5380_print_phase - show SCSI phase
 * @instance: adapter to dump
 *
 * Print the current SCSI phase for debugging purposes
 *
 * Locks: none
 */

static void NCR5380_print_phase(struct Scsi_Host *instance)
{
        unsigned char status;
        int i;

        status = NCR5380_read(STATUS_REG);
        if (!(status & SR_REQ))
                printk(KERN_DEBUG "scsi%d: REQ not asserted, phase unknown.\n", HOSTNO);
        else {
                for (i = 0; (phases[i].value != PHASE_UNKNOWN) &&
                     (phases[i].value != (status & PHASE_MASK)); ++i)
                        ;
                printk(KERN_DEBUG "scsi%d: phase %s\n", HOSTNO, phases[i].name);
        }
}

#endif

/*
 * ++roman: New scheme of calling NCR5380_main()
 *
 * If we're not in an interrupt, we can call our main directly, it cannot be
 * already running. Else, we queue it on a task queue, if not 'main_running'
 * tells us that a lower level is already executing it. This way,
 * 'main_running' needs not be protected in a special way.
 *
 * queue_main() is a utility function for putting our main onto the task
 * queue, if main_running is false. It should be called only from a
 * interrupt or bottom half.
 */

#include <linux/gfp.h>
#include <linux/workqueue.h>
#include <linux/interrupt.h>

static volatile int main_running;
static DECLARE_WORK(NCR5380_tqueue, NCR5380_main);

static inline void queue_main(void)
{
        if (!main_running) {
                /* If in interrupt and NCR5380_main() not already running,
                   queue it on the 'immediate' task queue, to be processed
                   immediately after the current interrupt processing has
                   finished. */
                schedule_work(&NCR5380_tqueue);
        }
        /* else: nothing to do: the running NCR5380_main() will pick up
           any newly queued command. */
}


static inline void NCR5380_all_init(void)
{
        static int done = 0;
        if (!done) {
                dprintk(NDEBUG_INIT, "scsi : NCR5380_all_init()\n");
                done = 1;
        }
}

/**
 * NCR58380_info - report driver and host information
 * @instance: relevant scsi host instance
 *
 * For use as the host template info() handler.
 *
 * Locks: none
 */

static const char *NCR5380_info(struct Scsi_Host *instance)
{
        struct NCR5380_hostdata *hostdata = shost_priv(instance);

        return hostdata->info;
}

static void prepare_info(struct Scsi_Host *instance)
{
        struct NCR5380_hostdata *hostdata = shost_priv(instance);

        snprintf(hostdata->info, sizeof(hostdata->info),
                 "%s, io_port 0x%lx, n_io_port %d, "
                 "base 0x%lx, irq %d, "
                 "can_queue %d, cmd_per_lun %d, "
                 "sg_tablesize %d, this_id %d, "
                 "flags { %s}, "
                 "options { %s} ",
                 instance->hostt->name, instance->io_port, instance->n_io_port,
                 instance->base, instance->irq,
                 instance->can_queue, instance->cmd_per_lun,
                 instance->sg_tablesize, instance->this_id,
                 hostdata->flags & FLAG_TAGGED_QUEUING ? "TAGGED_QUEUING " : "",
#ifdef DIFFERENTIAL
                 "DIFFERENTIAL "
#endif
#ifdef REAL_DMA
                 "REAL_DMA "
#endif
#ifdef PARITY
                 "PARITY "
#endif
#ifdef SUPPORT_TAGS
                 "SUPPORT_TAGS "
#endif
                 "");
}

/**
 * NCR5380_print_status - dump controller info
 * @instance: controller to dump
 *
 * Print commands in the various queues, called from NCR5380_abort
 * to aid debugging.
 */

static void lprint_Scsi_Cmnd(struct scsi_cmnd *cmd)
{
        int i, s;
        unsigned char *command;
        printk("scsi%d: destination target %d, lun %llu\n",
                H_NO(cmd), cmd->device->id, cmd->device->lun);
        printk(KERN_CONT "        command = ");
        command = cmd->cmnd;
        printk(KERN_CONT "%2d (0x%02x)", command[0], command[0]);
        for (i = 1, s = COMMAND_SIZE(command[0]); i < s; ++i)
                printk(KERN_CONT " %02x", command[i]);
        printk("\n");
}

static void NCR5380_print_status(struct Scsi_Host *instance)
{
        struct NCR5380_hostdata *hostdata;
        struct scsi_cmnd *ptr;
        unsigned long flags;

        NCR5380_dprint(NDEBUG_ANY, instance);
        NCR5380_dprint_phase(NDEBUG_ANY, instance);

        hostdata = (struct NCR5380_hostdata *)instance->hostdata;

        local_irq_save(flags);
        printk("NCR5380: coroutine is%s running.\n",
                main_running ? "" : "n't");
        if (!hostdata->connected)
                printk("scsi%d: no currently connected command\n", HOSTNO);
        else
                lprint_Scsi_Cmnd((struct scsi_cmnd *) hostdata->connected);
        printk("scsi%d: issue_queue\n", HOSTNO);
        for (ptr = (struct scsi_cmnd *)hostdata->issue_queue; ptr; ptr = NEXT(ptr))
                lprint_Scsi_Cmnd(ptr);

        printk("scsi%d: disconnected_queue\n", HOSTNO);
        for (ptr = (struct scsi_cmnd *) hostdata->disconnected_queue; ptr;
             ptr = NEXT(ptr))
                lprint_Scsi_Cmnd(ptr);

        local_irq_restore(flags);
        printk("\n");
}

static void show_Scsi_Cmnd(struct scsi_cmnd *cmd, struct seq_file *m)
{
        int i, s;
        unsigned char *command;
        seq_printf(m, "scsi%d: destination target %d, lun %llu\n",
                H_NO(cmd), cmd->device->id, cmd->device->lun);
        seq_printf(m, "        command = ");
        command = cmd->cmnd;
        seq_printf(m, "%2d (0x%02x)", command[0], command[0]);
        for (i = 1, s = COMMAND_SIZE(command[0]); i < s; ++i)
                seq_printf(m, " %02x", command[i]);
        seq_printf(m, "\n");
}

static int __maybe_unused NCR5380_show_info(struct seq_file *m,
                                            struct Scsi_Host *instance)
{
        struct NCR5380_hostdata *hostdata;
        struct scsi_cmnd *ptr;
        unsigned long flags;

        hostdata = (struct NCR5380_hostdata *)instance->hostdata;

        local_irq_save(flags);
        seq_printf(m, "NCR5380: coroutine is%s running.\n",
                main_running ? "" : "n't");
        if (!hostdata->connected)
                seq_printf(m, "scsi%d: no currently connected command\n", HOSTNO);
        else
                show_Scsi_Cmnd((struct scsi_cmnd *) hostdata->connected, m);
        seq_printf(m, "scsi%d: issue_queue\n", HOSTNO);
        for (ptr = (struct scsi_cmnd *)hostdata->issue_queue; ptr; ptr = NEXT(ptr))
                show_Scsi_Cmnd(ptr, m);

        seq_printf(m, "scsi%d: disconnected_queue\n", HOSTNO);
        for (ptr = (struct scsi_cmnd *) hostdata->disconnected_queue; ptr;
             ptr = NEXT(ptr))
                show_Scsi_Cmnd(ptr, m);

        local_irq_restore(flags);
        return 0;
}

/**
 * NCR5380_init - initialise an NCR5380
 * @instance: adapter to configure
 * @flags: control flags
 *
 * Initializes *instance and corresponding 5380 chip,
 * with flags OR'd into the initial flags value.
 *
 * Notes : I assume that the host, hostno, and id bits have been
 * set correctly. I don't care about the irq and other fields.
 *
 * Returns 0 for success
 */

static int __init NCR5380_init(struct Scsi_Host *instance, int flags)
{
        int i;
        SETUP_HOSTDATA(instance);

        NCR5380_all_init();

        hostdata->aborted = 0;
        hostdata->id_mask = 1 << instance->this_id;
        hostdata->id_higher_mask = 0;
        for (i = hostdata->id_mask; i <= 0x80; i <<= 1)
                if (i > hostdata->id_mask)
                        hostdata->id_higher_mask |= i;
        for (i = 0; i < 8; ++i)
                hostdata->busy[i] = 0;
#ifdef SUPPORT_TAGS
        init_tags(hostdata);
#endif
#if defined (REAL_DMA)
        hostdata->dma_len = 0;
#endif
        hostdata->targets_present = 0;
        hostdata->connected = NULL;
        hostdata->issue_queue = NULL;
        hostdata->disconnected_queue = NULL;
        hostdata->flags = flags;

        if (!the_template) {
                the_template = instance->hostt;
                first_instance = instance;
        }

        prepare_info(instance);

        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
        NCR5380_write(MODE_REG, MR_BASE);
        NCR5380_write(TARGET_COMMAND_REG, 0);
        NCR5380_write(SELECT_ENABLE_REG, 0);

        return 0;
}

/**
 * NCR5380_exit - remove an NCR5380
 * @instance: adapter to remove
 *
 * Assumes that no more work can be queued (e.g. by NCR5380_intr).
 */

static void NCR5380_exit(struct Scsi_Host *instance)
{
        cancel_work_sync(&NCR5380_tqueue);
}

/**
 * NCR5380_queue_command - queue a command
 * @instance: the relevant SCSI adapter
 * @cmd: SCSI command
 *
 * cmd is added to the per instance issue_queue, with minor
 * twiddling done to the host specific fields of cmd.  If the
 * main coroutine is not running, it is restarted.
 */

static int NCR5380_queue_command(struct Scsi_Host *instance,
                                 struct scsi_cmnd *cmd)
{
        struct NCR5380_hostdata *hostdata = shost_priv(instance);
        struct scsi_cmnd *tmp;
        unsigned long flags;

#if (NDEBUG & NDEBUG_NO_WRITE)
        switch (cmd->cmnd[0]) {
        case WRITE_6:
        case WRITE_10:
                printk(KERN_NOTICE "scsi%d: WRITE attempted with NO_WRITE debugging flag set\n",
                       H_NO(cmd));
                cmd->result = (DID_ERROR << 16);
                cmd->scsi_done(cmd);
                return 0;
        }
#endif /* (NDEBUG & NDEBUG_NO_WRITE) */

        /*
         * We use the host_scribble field as a pointer to the next command
         * in a queue
         */

        SET_NEXT(cmd, NULL);
        cmd->result = 0;

        /*
         * Insert the cmd into the issue queue. Note that REQUEST SENSE
         * commands are added to the head of the queue since any command will
         * clear the contingent allegiance condition that exists and the
         * sense data is only guaranteed to be valid while the condition exists.
         */

        /* ++guenther: now that the issue queue is being set up, we can lock ST-DMA.
         * Otherwise a running NCR5380_main may steal the lock.
         * Lock before actually inserting due to fairness reasons explained in
         * atari_scsi.c. If we insert first, then it's impossible for this driver
         * to release the lock.
         * Stop timer for this command while waiting for the lock, or timeouts
         * may happen (and they really do), and it's no good if the command doesn't
         * appear in any of the queues.
         * ++roman: Just disabling the NCR interrupt isn't sufficient here,
         * because also a timer int can trigger an abort or reset, which would
         * alter queues and touch the lock.
         */
        if (!NCR5380_acquire_dma_irq(instance))
                return SCSI_MLQUEUE_HOST_BUSY;

        local_irq_save(flags);

        /*
         * Insert the cmd into the issue queue. Note that REQUEST SENSE
         * commands are added to the head of the queue since any command will
         * clear the contingent allegiance condition that exists and the
         * sense data is only guaranteed to be valid while the condition exists.
         */

        if (!(hostdata->issue_queue) || (cmd->cmnd[0] == REQUEST_SENSE)) {
                LIST(cmd, hostdata->issue_queue);
                SET_NEXT(cmd, hostdata->issue_queue);
                hostdata->issue_queue = cmd;
        } else {
                for (tmp = (struct scsi_cmnd *)hostdata->issue_queue;
                     NEXT(tmp); tmp = NEXT(tmp))
                        ;
                LIST(cmd, tmp);
                SET_NEXT(tmp, cmd);
        }
        local_irq_restore(flags);

        dprintk(NDEBUG_QUEUES, "scsi%d: command added to %s of queue\n", H_NO(cmd),
                  (cmd->cmnd[0] == REQUEST_SENSE) ? "head" : "tail");

        /* If queue_command() is called from an interrupt (real one or bottom
         * half), we let queue_main() do the job of taking care about main. If it
         * is already running, this is a no-op, else main will be queued.
         *
         * If we're not in an interrupt, we can call NCR5380_main()
         * unconditionally, because it cannot be already running.
         */
        if (in_interrupt() || irqs_disabled())
                queue_main();
        else
                NCR5380_main(NULL);
        return 0;
}

static inline void maybe_release_dma_irq(struct Scsi_Host *instance)
{
        struct NCR5380_hostdata *hostdata = shost_priv(instance);

        /* Caller does the locking needed to set & test these data atomically */
        if (!hostdata->disconnected_queue &&
            !hostdata->issue_queue &&
            !hostdata->connected &&
            !hostdata->retain_dma_intr)
                NCR5380_release_dma_irq(instance);
}

/**
 * NCR5380_main - NCR state machines
 *
 * NCR5380_main is a coroutine that runs as long as more work can
 * be done on the NCR5380 host adapters in a system.  Both
 * NCR5380_queue_command() and NCR5380_intr() will try to start it
 * in case it is not running.
 *
 * Locks: called as its own thread with no locks held.
 */

static void NCR5380_main(struct work_struct *work)
{
        struct scsi_cmnd *tmp, *prev;
        struct Scsi_Host *instance = first_instance;
        struct NCR5380_hostdata *hostdata = HOSTDATA(instance);
        int done;
        unsigned long flags;

        /*
         * We run (with interrupts disabled) until we're sure that none of
         * the host adapters have anything that can be done, at which point
         * we set main_running to 0 and exit.
         *
         * Interrupts are enabled before doing various other internal
         * instructions, after we've decided that we need to run through
         * the loop again.
         *
         * this should prevent any race conditions.
         *
         * ++roman: Just disabling the NCR interrupt isn't sufficient here,
         * because also a timer int can trigger an abort or reset, which can
         * alter queues and touch the Falcon lock.
         */

        /* Tell int handlers main() is now already executing.  Note that
           no races are possible here. If an int comes in before
           'main_running' is set here, and queues/executes main via the
           task queue, it doesn't do any harm, just this instance of main
           won't find any work left to do. */
        if (main_running)
                return;
        main_running = 1;

        local_save_flags(flags);
        do {
                local_irq_disable();    /* Freeze request queues */
                done = 1;

                if (!hostdata->connected) {
                        dprintk(NDEBUG_MAIN, "scsi%d: not connected\n", HOSTNO);
                        /*
                         * Search through the issue_queue for a command destined
                         * for a target that's not busy.
                         */
#if (NDEBUG & NDEBUG_LISTS)
                        for (tmp = (struct scsi_cmnd *) hostdata->issue_queue, prev = NULL;
                             tmp && (tmp != prev); prev = tmp, tmp = NEXT(tmp))
                                ;
                        /*printk("%p  ", tmp);*/
                        if ((tmp == prev) && tmp)
                                printk(" LOOP\n");
                        /* else printk("\n"); */
#endif
                        for (tmp = (struct scsi_cmnd *) hostdata->issue_queue,
                             prev = NULL; tmp; prev = tmp, tmp = NEXT(tmp)) {
                                u8 lun = tmp->device->lun;

                                dprintk(NDEBUG_LISTS,
                                        "MAIN tmp=%p target=%d busy=%d lun=%d\n",
                                        tmp, scmd_id(tmp), hostdata->busy[scmd_id(tmp)],
                                        lun);
                                /*  When we find one, remove it from the issue queue. */
                                /* ++guenther: possible race with Falcon locking */
                                if (
#ifdef SUPPORT_TAGS
                                    !is_lun_busy( tmp, tmp->cmnd[0] != REQUEST_SENSE)
#else
                                    !(hostdata->busy[tmp->device->id] & (1 << lun))
#endif
                                    ) {
                                        /* ++guenther: just to be sure, this must be atomic */
                                        local_irq_disable();
                                        if (prev) {
                                                REMOVE(prev, NEXT(prev), tmp, NEXT(tmp));
                                                SET_NEXT(prev, NEXT(tmp));
                                        } else {
                                                REMOVE(-1, hostdata->issue_queue, tmp, NEXT(tmp));
                                                hostdata->issue_queue = NEXT(tmp);
                                        }
                                        SET_NEXT(tmp, NULL);
                                        hostdata->retain_dma_intr++;

                                        /* reenable interrupts after finding one */
                                        local_irq_restore(flags);

                                        /*
                                         * Attempt to establish an I_T_L nexus here.
                                         * On success, instance->hostdata->connected is set.
                                         * On failure, we must add the command back to the
                                         *   issue queue so we can keep trying.
                                         */
                                        dprintk(NDEBUG_MAIN, "scsi%d: main(): command for target %d "
                                                    "lun %d removed from issue_queue\n",
                                                    HOSTNO, tmp->device->id, lun);
                                        /*
                                         * REQUEST SENSE commands are issued without tagged
                                         * queueing, even on SCSI-II devices because the
                                         * contingent allegiance condition exists for the
                                         * entire unit.
                                         */
                                        /* ++roman: ...and the standard also requires that
                                         * REQUEST SENSE command are untagged.
                                         */

#ifdef SUPPORT_TAGS
                                        cmd_get_tag(tmp, tmp->cmnd[0] != REQUEST_SENSE);
#endif
                                        if (!NCR5380_select(instance, tmp)) {
                                                local_irq_disable();
                                                hostdata->retain_dma_intr--;
                                                /* release if target did not response! */
                                                maybe_release_dma_irq(instance);
                                                local_irq_restore(flags);
                                                break;
                                        } else {
                                                local_irq_disable();
                                                LIST(tmp, hostdata->issue_queue);
                                                SET_NEXT(tmp, hostdata->issue_queue);
                                                hostdata->issue_queue = tmp;
#ifdef SUPPORT_TAGS
                                                cmd_free_tag(tmp);
#endif
                                                hostdata->retain_dma_intr--;
                                                local_irq_restore(flags);
                                                dprintk(NDEBUG_MAIN, "scsi%d: main(): select() failed, "
                                                            "returned to issue_queue\n", HOSTNO);
                                                if (hostdata->connected)
                                                        break;
                                        }
                                } /* if target/lun/target queue is not busy */
                        } /* for issue_queue */
                } /* if (!hostdata->connected) */

                if (hostdata->connected
#ifdef REAL_DMA
                    && !hostdata->dma_len
#endif
                    ) {
                        local_irq_restore(flags);
                        dprintk(NDEBUG_MAIN, "scsi%d: main: performing information transfer\n",
                                    HOSTNO);
                        NCR5380_information_transfer(instance);
                        dprintk(NDEBUG_MAIN, "scsi%d: main: done set false\n", HOSTNO);
                        done = 0;
                }
        } while (!done);

        /* Better allow ints _after_ 'main_running' has been cleared, else
           an interrupt could believe we'll pick up the work it left for
           us, but we won't see it anymore here... */
        main_running = 0;
        local_irq_restore(flags);
}


#ifdef REAL_DMA
/*
 * Function : void NCR5380_dma_complete (struct Scsi_Host *instance)
 *
 * Purpose : Called by interrupt handler when DMA finishes or a phase
 *      mismatch occurs (which would finish the DMA transfer).
 *
 * Inputs : instance - this instance of the NCR5380.
 *
 */

static void NCR5380_dma_complete(struct Scsi_Host *instance)
{
        SETUP_HOSTDATA(instance);
        int transfered;
        unsigned char **data;
        volatile int *count;
        int saved_data = 0, overrun = 0;
        unsigned char p;

        if (!hostdata->connected) {
                printk(KERN_WARNING "scsi%d: received end of DMA interrupt with "
                       "no connected cmd\n", HOSTNO);
                return;
        }

        if (hostdata->read_overruns) {
                p = hostdata->connected->SCp.phase;
                if (p & SR_IO) {
                        udelay(10);
                        if ((NCR5380_read(BUS_AND_STATUS_REG) &
                             (BASR_PHASE_MATCH|BASR_ACK)) ==
                            (BASR_PHASE_MATCH|BASR_ACK)) {
                                saved_data = NCR5380_read(INPUT_DATA_REG);
                                overrun = 1;
                                dprintk(NDEBUG_DMA, "scsi%d: read overrun handled\n", HOSTNO);
                        }
                }
        }

        dprintk(NDEBUG_DMA, "scsi%d: real DMA transfer complete, basr 0x%X, sr 0x%X\n",
                   HOSTNO, NCR5380_read(BUS_AND_STATUS_REG),
                   NCR5380_read(STATUS_REG));

#if defined(CONFIG_SUN3)
        if ((sun3scsi_dma_finish(rq_data_dir(hostdata->connected->request)))) {
                pr_err("scsi%d: overrun in UDC counter -- not prepared to deal with this!\n",
                       instance->host_no);
                BUG();
        }

        /* make sure we're not stuck in a data phase */
        if ((NCR5380_read(BUS_AND_STATUS_REG) & (BASR_PHASE_MATCH | BASR_ACK)) ==
            (BASR_PHASE_MATCH | BASR_ACK)) {
                pr_err("scsi%d: BASR %02x\n", instance->host_no,
                       NCR5380_read(BUS_AND_STATUS_REG));
                pr_err("scsi%d: bus stuck in data phase -- probably a single byte overrun!\n",
                       instance->host_no);
                BUG();
        }
#endif

        (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
        NCR5380_write(MODE_REG, MR_BASE);
        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

        transfered = hostdata->dma_len - NCR5380_dma_residual(instance);
        hostdata->dma_len = 0;

        data = (unsigned char **)&hostdata->connected->SCp.ptr;
        count = &hostdata->connected->SCp.this_residual;
        *data += transfered;
        *count -= transfered;

        if (hostdata->read_overruns) {
                int cnt, toPIO;

                if ((NCR5380_read(STATUS_REG) & PHASE_MASK) == p && (p & SR_IO)) {
                        cnt = toPIO = hostdata->read_overruns;
                        if (overrun) {
                                dprintk(NDEBUG_DMA, "Got an input overrun, using saved byte\n");
                                *(*data)++ = saved_data;
                                (*count)--;
                                cnt--;
                                toPIO--;
                        }
                        dprintk(NDEBUG_DMA, "Doing %d-byte PIO to 0x%08lx\n", cnt, (long)*data);
                        NCR5380_transfer_pio(instance, &p, &cnt, data);
                        *count -= toPIO - cnt;
                }
        }
}
#endif /* REAL_DMA */


/**
 * NCR5380_intr - generic NCR5380 irq handler
 * @irq: interrupt number
 * @dev_id: device info
 *
 * Handle interrupts, reestablishing I_T_L or I_T_L_Q nexuses
 * from the disconnected queue, and restarting NCR5380_main()
 * as required.
 */

static irqreturn_t NCR5380_intr(int irq, void *dev_id)
{
        struct Scsi_Host *instance = first_instance;
        int done = 1, handled = 0;
        unsigned char basr;

        dprintk(NDEBUG_INTR, "scsi%d: NCR5380 irq triggered\n", HOSTNO);

        /* Look for pending interrupts */
        basr = NCR5380_read(BUS_AND_STATUS_REG);
        dprintk(NDEBUG_INTR, "scsi%d: BASR=%02x\n", HOSTNO, basr);
        /* dispatch to appropriate routine if found and done=0 */
        if (basr & BASR_IRQ) {
                NCR5380_dprint(NDEBUG_INTR, instance);
                if ((NCR5380_read(STATUS_REG) & (SR_SEL|SR_IO)) == (SR_SEL|SR_IO)) {
                        done = 0;
                        dprintk(NDEBUG_INTR, "scsi%d: SEL interrupt\n", HOSTNO);
                        NCR5380_reselect(instance);
                        (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
                } else if (basr & BASR_PARITY_ERROR) {
                        dprintk(NDEBUG_INTR, "scsi%d: PARITY interrupt\n", HOSTNO);
                        (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
                } else if ((NCR5380_read(STATUS_REG) & SR_RST) == SR_RST) {
                        dprintk(NDEBUG_INTR, "scsi%d: RESET interrupt\n", HOSTNO);
                        (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
                } else {
                        /*
                         * The rest of the interrupt conditions can occur only during a
                         * DMA transfer
                         */

#if defined(REAL_DMA)
                        /*
                         * We should only get PHASE MISMATCH and EOP interrupts if we have
                         * DMA enabled, so do a sanity check based on the current setting
                         * of the MODE register.
                         */

                        if ((NCR5380_read(MODE_REG) & MR_DMA_MODE) &&
                            ((basr & BASR_END_DMA_TRANSFER) ||
                             !(basr & BASR_PHASE_MATCH))) {

                                dprintk(NDEBUG_INTR, "scsi%d: PHASE MISM or EOP interrupt\n", HOSTNO);
                                NCR5380_dma_complete( instance );
                                done = 0;
                        } else
#endif /* REAL_DMA */
                        {
/* MS: Ignore unknown phase mismatch interrupts (caused by EOP interrupt) */
                                if (basr & BASR_PHASE_MATCH)
                                        dprintk(NDEBUG_INTR, "scsi%d: unknown interrupt, "
                                               "BASR 0x%x, MR 0x%x, SR 0x%x\n",
                                               HOSTNO, basr, NCR5380_read(MODE_REG),
                                               NCR5380_read(STATUS_REG));
                                (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
#ifdef SUN3_SCSI_VME
                                dregs->csr |= CSR_DMA_ENABLE;
#endif
                        }
                } /* if !(SELECTION || PARITY) */
                handled = 1;
        } /* BASR & IRQ */ else {
                printk(KERN_NOTICE "scsi%d: interrupt without IRQ bit set in BASR, "
                       "BASR 0x%X, MR 0x%X, SR 0x%x\n", HOSTNO, basr,
                       NCR5380_read(MODE_REG), NCR5380_read(STATUS_REG));
                (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
#ifdef SUN3_SCSI_VME
                dregs->csr |= CSR_DMA_ENABLE;
#endif
        }

        if (!done) {
                dprintk(NDEBUG_INTR, "scsi%d: in int routine, calling main\n", HOSTNO);
                /* Put a call to NCR5380_main() on the queue... */
                queue_main();
        }
        return IRQ_RETVAL(handled);
}

/*
 * Function : int NCR5380_select(struct Scsi_Host *instance,
 *                               struct scsi_cmnd *cmd)
 *
 * Purpose : establishes I_T_L or I_T_L_Q nexus for new or existing command,
 *      including ARBITRATION, SELECTION, and initial message out for
 *      IDENTIFY and queue messages.
 *
 * Inputs : instance - instantiation of the 5380 driver on which this
 *      target lives, cmd - SCSI command to execute.
 *
 * Returns : -1 if selection could not execute for some reason,
 *      0 if selection succeeded or failed because the target
 *      did not respond.
 *
 * Side effects :
 *      If bus busy, arbitration failed, etc, NCR5380_select() will exit
 *              with registers as they should have been on entry - ie
 *              SELECT_ENABLE will be set appropriately, the NCR5380
 *              will cease to drive any SCSI bus signals.
 *
 *      If successful : I_T_L or I_T_L_Q nexus will be established,
 *              instance->connected will be set to cmd.
 *              SELECT interrupt will be disabled.
 *
 *      If failed (no target) : cmd->scsi_done() will be called, and the
 *              cmd->result host byte set to DID_BAD_TARGET.
 */

static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
{
        SETUP_HOSTDATA(instance);
        unsigned char tmp[3], phase;
        unsigned char *data;
        int len;
        unsigned long timeout;
        unsigned long flags;

        hostdata->restart_select = 0;
        NCR5380_dprint(NDEBUG_ARBITRATION, instance);
        dprintk(NDEBUG_ARBITRATION, "scsi%d: starting arbitration, id = %d\n", HOSTNO,
                   instance->this_id);

        /*
         * Set the phase bits to 0, otherwise the NCR5380 won't drive the
         * data bus during SELECTION.
         */

        local_irq_save(flags);
        if (hostdata->connected) {
                local_irq_restore(flags);
                return -1;
        }
        NCR5380_write(TARGET_COMMAND_REG, 0);

        /*
         * Start arbitration.
         */

        NCR5380_write(OUTPUT_DATA_REG, hostdata->id_mask);
        NCR5380_write(MODE_REG, MR_ARBITRATE);

        local_irq_restore(flags);

        /* Wait for arbitration logic to complete */
#if defined(NCR_TIMEOUT)
        {
                unsigned long timeout = jiffies + 2*NCR_TIMEOUT;

                while (!(NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_PROGRESS) &&
                       time_before(jiffies, timeout) && !hostdata->connected)
                        ;
                if (time_after_eq(jiffies, timeout)) {
                        printk("scsi : arbitration timeout at %d\n", __LINE__);
                        NCR5380_write(MODE_REG, MR_BASE);
                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                        return -1;
                }
        }
#else /* NCR_TIMEOUT */
        while (!(NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_PROGRESS) &&
               !hostdata->connected)
                ;
#endif

        dprintk(NDEBUG_ARBITRATION, "scsi%d: arbitration complete\n", HOSTNO);

        if (hostdata->connected) {
                NCR5380_write(MODE_REG, MR_BASE);
                return -1;
        }
        /*
         * The arbitration delay is 2.2us, but this is a minimum and there is
         * no maximum so we can safely sleep for ceil(2.2) usecs to accommodate
         * the integral nature of udelay().
         *
         */

        udelay(3);

        /* Check for lost arbitration */
        if ((NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST) ||
            (NCR5380_read(CURRENT_SCSI_DATA_REG) & hostdata->id_higher_mask) ||
            (NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST) ||
            hostdata->connected) {
                NCR5380_write(MODE_REG, MR_BASE);
                dprintk(NDEBUG_ARBITRATION, "scsi%d: lost arbitration, deasserting MR_ARBITRATE\n",
                           HOSTNO);
                return -1;
        }

        /* after/during arbitration, BSY should be asserted.
           IBM DPES-31080 Version S31Q works now */
        /* Tnx to Thomas_Roesch@m2.maus.de for finding this! (Roman) */
        NCR5380_write(INITIATOR_COMMAND_REG,
                      ICR_BASE | ICR_ASSERT_SEL | ICR_ASSERT_BSY);

        if ((NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST) ||
            hostdata->connected) {
                NCR5380_write(MODE_REG, MR_BASE);
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                dprintk(NDEBUG_ARBITRATION, "scsi%d: lost arbitration, deasserting ICR_ASSERT_SEL\n",
                           HOSTNO);
                return -1;
        }

        /*
         * Again, bus clear + bus settle time is 1.2us, however, this is
         * a minimum so we'll udelay ceil(1.2)
         */

#ifdef CONFIG_ATARI_SCSI_TOSHIBA_DELAY
        /* ++roman: But some targets (see above :-) seem to need a bit more... */
        udelay(15);
#else
        udelay(2);
#endif

        if (hostdata->connected) {
                NCR5380_write(MODE_REG, MR_BASE);
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                return -1;
        }

        dprintk(NDEBUG_ARBITRATION, "scsi%d: won arbitration\n", HOSTNO);

        /*
         * Now that we have won arbitration, start Selection process, asserting
         * the host and target ID's on the SCSI bus.
         */

        NCR5380_write(OUTPUT_DATA_REG, (hostdata->id_mask | (1 << cmd->device->id)));

        /*
         * Raise ATN while SEL is true before BSY goes false from arbitration,
         * since this is the only way to guarantee that we'll get a MESSAGE OUT
         * phase immediately after selection.
         */

        NCR5380_write(INITIATOR_COMMAND_REG, (ICR_BASE | ICR_ASSERT_BSY |
                      ICR_ASSERT_DATA | ICR_ASSERT_ATN | ICR_ASSERT_SEL ));
        NCR5380_write(MODE_REG, MR_BASE);

        /*
         * Reselect interrupts must be turned off prior to the dropping of BSY,
         * otherwise we will trigger an interrupt.
         */

        if (hostdata->connected) {
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                return -1;
        }

        NCR5380_write(SELECT_ENABLE_REG, 0);

        /*
         * The initiator shall then wait at least two deskew delays and release
         * the BSY signal.
         */
        udelay(1);        /* wingel -- wait two bus deskew delay >2*45ns */

        /* Reset BSY */
        NCR5380_write(INITIATOR_COMMAND_REG, (ICR_BASE | ICR_ASSERT_DATA |
                      ICR_ASSERT_ATN | ICR_ASSERT_SEL));

        /*
         * Something weird happens when we cease to drive BSY - looks
         * like the board/chip is letting us do another read before the
         * appropriate propagation delay has expired, and we're confusing
         * a BSY signal from ourselves as the target's response to SELECTION.
         *
         * A small delay (the 'C++' frontend breaks the pipeline with an
         * unnecessary jump, making it work on my 386-33/Trantor T128, the
         * tighter 'C' code breaks and requires this) solves the problem -
         * the 1 us delay is arbitrary, and only used because this delay will
         * be the same on other platforms and since it works here, it should
         * work there.
         *
         * wingel suggests that this could be due to failing to wait
         * one deskew delay.
         */

        udelay(1);

        dprintk(NDEBUG_SELECTION, "scsi%d: selecting target %d\n", HOSTNO, cmd->device->id);

        /*
         * The SCSI specification calls for a 250 ms timeout for the actual
         * selection.
         */

        timeout = jiffies + (250 * HZ / 1000);

        /*
         * XXX very interesting - we're seeing a bounce where the BSY we
         * asserted is being reflected / still asserted (propagation delay?)
         * and it's detecting as true.  Sigh.
         */

#if 0
        /* ++roman: If a target conformed to the SCSI standard, it wouldn't assert
         * IO while SEL is true. But again, there are some disks out the in the
         * world that do that nevertheless. (Somebody claimed that this announces
         * reselection capability of the target.) So we better skip that test and
         * only wait for BSY... (Famous german words: Der Klügere gibt nach :-)
         */

        while (time_before(jiffies, timeout) &&
               !(NCR5380_read(STATUS_REG) & (SR_BSY | SR_IO)))
                ;

        if ((NCR5380_read(STATUS_REG) & (SR_SEL | SR_IO)) == (SR_SEL | SR_IO)) {
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                NCR5380_reselect(instance);
                printk(KERN_ERR "scsi%d: reselection after won arbitration?\n",
                       HOSTNO);
                NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                return -1;
        }
#else
        while (time_before(jiffies, timeout) && !(NCR5380_read(STATUS_REG) & SR_BSY))
                ;
#endif

        /*
         * No less than two deskew delays after the initiator detects the
         * BSY signal is true, it shall release the SEL signal and may
         * change the DATA BUS.                                     -wingel
         */

        udelay(1);

        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);

        if (!(NCR5380_read(STATUS_REG) & SR_BSY)) {
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                if (hostdata->targets_present & (1 << cmd->device->id)) {
                        printk(KERN_ERR "scsi%d: weirdness\n", HOSTNO);
                        if (hostdata->restart_select)
                                printk(KERN_NOTICE "\trestart select\n");
                        NCR5380_dprint(NDEBUG_ANY, instance);
                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                        return -1;
                }
                cmd->result = DID_BAD_TARGET << 16;
#ifdef SUPPORT_TAGS
                cmd_free_tag(cmd);
#endif
                cmd->scsi_done(cmd);
                NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                dprintk(NDEBUG_SELECTION, "scsi%d: target did not respond within 250ms\n", HOSTNO);
                NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                return 0;
        }

        hostdata->targets_present |= (1 << cmd->device->id);

        /*
         * Since we followed the SCSI spec, and raised ATN while SEL
         * was true but before BSY was false during selection, the information
         * transfer phase should be a MESSAGE OUT phase so that we can send the
         * IDENTIFY message.
         *
         * If SCSI-II tagged queuing is enabled, we also send a SIMPLE_QUEUE_TAG
         * message (2 bytes) with a tag ID that we increment with every command
         * until it wraps back to 0.
         *
         * XXX - it turns out that there are some broken SCSI-II devices,
         *           which claim to support tagged queuing but fail when more than
         *           some number of commands are issued at once.
         */

        /* Wait for start of REQ/ACK handshake */
        while (!(NCR5380_read(STATUS_REG) & SR_REQ))
                ;

        dprintk(NDEBUG_SELECTION, "scsi%d: target %d selected, going into MESSAGE OUT phase.\n",
                   HOSTNO, cmd->device->id);
        tmp[0] = IDENTIFY(1, cmd->device->lun);

#ifdef SUPPORT_TAGS
        if (cmd->tag != TAG_NONE) {
                tmp[1] = hostdata->last_message = SIMPLE_QUEUE_TAG;
                tmp[2] = cmd->tag;
                len = 3;
        } else
                len = 1;
#else
        len = 1;
        cmd->tag = 0;
#endif /* SUPPORT_TAGS */

        /* Send message(s) */
        data = tmp;
        phase = PHASE_MSGOUT;
        NCR5380_transfer_pio(instance, &phase, &len, &data);
        dprintk(NDEBUG_SELECTION, "scsi%d: nexus established.\n", HOSTNO);
        /* XXX need to handle errors here */
        hostdata->connected = cmd;
#ifndef SUPPORT_TAGS
        hostdata->busy[cmd->device->id] |= (1 << cmd->device->lun);
#endif
#ifdef SUN3_SCSI_VME
        dregs->csr |= CSR_INTR;
#endif

        initialize_SCp(cmd);

        return 0;
}

/*
 * Function : int NCR5380_transfer_pio (struct Scsi_Host *instance,
 *      unsigned char *phase, int *count, unsigned char **data)
 *
 * Purpose : transfers data in given phase using polled I/O
 *
 * Inputs : instance - instance of driver, *phase - pointer to
 *      what phase is expected, *count - pointer to number of
 *      bytes to transfer, **data - pointer to data pointer.
 *
 * Returns : -1 when different phase is entered without transferring
 *      maximum number of bytes, 0 if all bytes are transferred or exit
 *      is in same phase.
 *
 *      Also, *phase, *count, *data are modified in place.
 *
 * XXX Note : handling for bus free may be useful.
 */

/*
 * Note : this code is not as quick as it could be, however it
 * IS 100% reliable, and for the actual data transfer where speed
 * counts, we will always do a pseudo DMA or DMA transfer.
 */

static int NCR5380_transfer_pio(struct Scsi_Host *instance,
                                unsigned char *phase, int *count,
                                unsigned char **data)
{
        register unsigned char p = *phase, tmp;
        register int c = *count;
        register unsigned char *d = *data;

        /*
         * The NCR5380 chip will only drive the SCSI bus when the
         * phase specified in the appropriate bits of the TARGET COMMAND
         * REGISTER match the STATUS REGISTER
         */

        NCR5380_write(TARGET_COMMAND_REG, PHASE_SR_TO_TCR(p));

        do {
                /*
                 * Wait for assertion of REQ, after which the phase bits will be
                 * valid
                 */
                while (!((tmp = NCR5380_read(STATUS_REG)) & SR_REQ))
                        ;

                dprintk(NDEBUG_HANDSHAKE, "scsi%d: REQ detected\n", HOSTNO);

                /* Check for phase mismatch */
                if ((tmp & PHASE_MASK) != p) {
                        dprintk(NDEBUG_PIO, "scsi%d: phase mismatch\n", HOSTNO);
                        NCR5380_dprint_phase(NDEBUG_PIO, instance);
                        break;
                }

                /* Do actual transfer from SCSI bus to / from memory */
                if (!(p & SR_IO))
                        NCR5380_write(OUTPUT_DATA_REG, *d);
                else
                        *d = NCR5380_read(CURRENT_SCSI_DATA_REG);

                ++d;

                /*
                 * The SCSI standard suggests that in MSGOUT phase, the initiator
                 * should drop ATN on the last byte of the message phase
                 * after REQ has been asserted for the handshake but before
                 * the initiator raises ACK.
                 */

                if (!(p & SR_IO)) {
                        if (!((p & SR_MSG) && c > 1)) {
                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA);
                                NCR5380_dprint(NDEBUG_PIO, instance);
                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE |
                                              ICR_ASSERT_DATA | ICR_ASSERT_ACK);
                        } else {
                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE |
                                              ICR_ASSERT_DATA | ICR_ASSERT_ATN);
                                NCR5380_dprint(NDEBUG_PIO, instance);
                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE |
                                              ICR_ASSERT_DATA | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
                        }
                } else {
                        NCR5380_dprint(NDEBUG_PIO, instance);
                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ACK);
                }

                while (NCR5380_read(STATUS_REG) & SR_REQ)
                        ;

                dprintk(NDEBUG_HANDSHAKE, "scsi%d: req false, handshake complete\n", HOSTNO);

                /*
                 * We have several special cases to consider during REQ/ACK handshaking :
                 * 1.  We were in MSGOUT phase, and we are on the last byte of the
                 *      message.  ATN must be dropped as ACK is dropped.
                 *
                 * 2.  We are in a MSGIN phase, and we are on the last byte of the
                 *      message.  We must exit with ACK asserted, so that the calling
                 *      code may raise ATN before dropping ACK to reject the message.
                 *
                 * 3.  ACK and ATN are clear and the target may proceed as normal.
                 */
                if (!(p == PHASE_MSGIN && c == 1)) {
                        if (p == PHASE_MSGOUT && c > 1)
                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
                        else
                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                }
        } while (--c);

        dprintk(NDEBUG_PIO, "scsi%d: residual %d\n", HOSTNO, c);

        *count = c;
        *data = d;
        tmp = NCR5380_read(STATUS_REG);
        /* The phase read from the bus is valid if either REQ is (already)
         * asserted or if ACK hasn't been released yet. The latter is the case if
         * we're in MSGIN and all wanted bytes have been received.
         */
        if ((tmp & SR_REQ) || (p == PHASE_MSGIN && c == 0))
                *phase = tmp & PHASE_MASK;
        else
                *phase = PHASE_UNKNOWN;

        if (!c || (*phase == p))
                return 0;
        else
                return -1;
}

/*
 * Function : do_abort (Scsi_Host *host)
 *
 * Purpose : abort the currently established nexus.  Should only be
 *      called from a routine which can drop into a
 *
 * Returns : 0 on success, -1 on failure.
 */

static int do_abort(struct Scsi_Host *host)
{
        unsigned char tmp, *msgptr, phase;
        int len;

        /* Request message out phase */
        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);

        /*
         * Wait for the target to indicate a valid phase by asserting
         * REQ.  Once this happens, we'll have either a MSGOUT phase
         * and can immediately send the ABORT message, or we'll have some
         * other phase and will have to source/sink data.
         *
         * We really don't care what value was on the bus or what value
         * the target sees, so we just handshake.
         */

        while (!((tmp = NCR5380_read(STATUS_REG)) & SR_REQ))
                ;

        NCR5380_write(TARGET_COMMAND_REG, PHASE_SR_TO_TCR(tmp));

        if ((tmp & PHASE_MASK) != PHASE_MSGOUT) {
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN |
                              ICR_ASSERT_ACK);
                while (NCR5380_read(STATUS_REG) & SR_REQ)
                        ;
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
        }

        tmp = ABORT;
        msgptr = &tmp;
        len = 1;
        phase = PHASE_MSGOUT;
        NCR5380_transfer_pio(host, &phase, &len, &msgptr);

        /*
         * If we got here, and the command completed successfully,
         * we're about to go into bus free state.
         */

        return len ? -1 : 0;
}

#if defined(REAL_DMA)
/*
 * Function : int NCR5380_transfer_dma (struct Scsi_Host *instance,
 *      unsigned char *phase, int *count, unsigned char **data)
 *
 * Purpose : transfers data in given phase using either real
 *      or pseudo DMA.
 *
 * Inputs : instance - instance of driver, *phase - pointer to
 *      what phase is expected, *count - pointer to number of
 *      bytes to transfer, **data - pointer to data pointer.
 *
 * Returns : -1 when different phase is entered without transferring
 *      maximum number of bytes, 0 if all bytes or transferred or exit
 *      is in same phase.
 *
 *      Also, *phase, *count, *data are modified in place.
 *
 */


static int NCR5380_transfer_dma(struct Scsi_Host *instance,
                                unsigned char *phase, int *count,
                                unsigned char **data)
{
        SETUP_HOSTDATA(instance);
        register int c = *count;
        register unsigned char p = *phase;
        unsigned long flags;

#if defined(CONFIG_SUN3)
        /* sanity check */
        if (!sun3_dma_setup_done) {
                pr_err("scsi%d: transfer_dma without setup!\n",
                       instance->host_no);
                BUG();
        }
        hostdata->dma_len = c;

        dprintk(NDEBUG_DMA, "scsi%d: initializing DMA for %s, %d bytes %s %p\n",
                instance->host_no, (p & SR_IO) ? "reading" : "writing",
                c, (p & SR_IO) ? "to" : "from", *data);

        /* netbsd turns off ints here, why not be safe and do it too */
        local_irq_save(flags);

        /* send start chain */
        sun3scsi_dma_start(c, *data);

        if (p & SR_IO) {
                NCR5380_write(TARGET_COMMAND_REG, 1);
                NCR5380_read(RESET_PARITY_INTERRUPT_REG);
                NCR5380_write(INITIATOR_COMMAND_REG, 0);
                NCR5380_write(MODE_REG,
                              (NCR5380_read(MODE_REG) | MR_DMA_MODE | MR_ENABLE_EOP_INTR));
                NCR5380_write(START_DMA_INITIATOR_RECEIVE_REG, 0);
        } else {
                NCR5380_write(TARGET_COMMAND_REG, 0);
                NCR5380_read(RESET_PARITY_INTERRUPT_REG);
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_ASSERT_DATA);
                NCR5380_write(MODE_REG,
                              (NCR5380_read(MODE_REG) | MR_DMA_MODE | MR_ENABLE_EOP_INTR));
                NCR5380_write(START_DMA_SEND_REG, 0);
        }

#ifdef SUN3_SCSI_VME
        dregs->csr |= CSR_DMA_ENABLE;
#endif

        local_irq_restore(flags);

        sun3_dma_active = 1;

#else /* !defined(CONFIG_SUN3) */
        register unsigned char *d = *data;
        unsigned char tmp;

        if ((tmp = (NCR5380_read(STATUS_REG) & PHASE_MASK)) != p) {
                *phase = tmp;
                return -1;
        }

        if (hostdata->read_overruns && (p & SR_IO))
                c -= hostdata->read_overruns;

        dprintk(NDEBUG_DMA, "scsi%d: initializing DMA for %s, %d bytes %s %p\n",
                   HOSTNO, (p & SR_IO) ? "reading" : "writing",
                   c, (p & SR_IO) ? "to" : "from", d);

        NCR5380_write(TARGET_COMMAND_REG, PHASE_SR_TO_TCR(p));

#ifdef REAL_DMA
        NCR5380_write(MODE_REG, MR_BASE | MR_DMA_MODE | MR_ENABLE_EOP_INTR | MR_MONITOR_BSY);
#endif /* def REAL_DMA  */

        if (!(hostdata->flags & FLAG_LATE_DMA_SETUP)) {
                /* On the Medusa, it is a must to initialize the DMA before
                 * starting the NCR. This is also the cleaner way for the TT.
                 */
                local_irq_save(flags);
                hostdata->dma_len = (p & SR_IO) ?
                        NCR5380_dma_read_setup(instance, d, c) :
                        NCR5380_dma_write_setup(instance, d, c);
                local_irq_restore(flags);
        }

        if (p & SR_IO)
                NCR5380_write(START_DMA_INITIATOR_RECEIVE_REG, 0);
        else {
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA);
                NCR5380_write(START_DMA_SEND_REG, 0);
        }

        if (hostdata->flags & FLAG_LATE_DMA_SETUP) {
                /* On the Falcon, the DMA setup must be done after the last */
                /* NCR access, else the DMA setup gets trashed!
                 */
                local_irq_save(flags);
                hostdata->dma_len = (p & SR_IO) ?
                        NCR5380_dma_read_setup(instance, d, c) :
                        NCR5380_dma_write_setup(instance, d, c);
                local_irq_restore(flags);
        }
#endif /* !defined(CONFIG_SUN3) */

        return 0;
}
#endif /* defined(REAL_DMA) */

/*
 * Function : NCR5380_information_transfer (struct Scsi_Host *instance)
 *
 * Purpose : run through the various SCSI phases and do as the target
 *      directs us to.  Operates on the currently connected command,
 *      instance->connected.
 *
 * Inputs : instance, instance for which we are doing commands
 *
 * Side effects : SCSI things happen, the disconnected queue will be
 *      modified if a command disconnects, *instance->connected will
 *      change.
 *
 * XXX Note : we need to watch for bus free or a reset condition here
 *      to recover from an unexpected bus free condition.
 */

static void NCR5380_information_transfer(struct Scsi_Host *instance)
{
        SETUP_HOSTDATA(instance);
        unsigned long flags;
        unsigned char msgout = NOP;
        int sink = 0;
        int len;
#if defined(REAL_DMA)
        int transfersize;
#endif
        unsigned char *data;
        unsigned char phase, tmp, extended_msg[10], old_phase = 0xff;
        struct scsi_cmnd *cmd = (struct scsi_cmnd *) hostdata->connected;

#ifdef SUN3_SCSI_VME
        dregs->csr |= CSR_INTR;
#endif

        while (1) {
                tmp = NCR5380_read(STATUS_REG);
                /* We only have a valid SCSI phase when REQ is asserted */
                if (tmp & SR_REQ) {
                        phase = (tmp & PHASE_MASK);
                        if (phase != old_phase) {
                                old_phase = phase;
                                NCR5380_dprint_phase(NDEBUG_INFORMATION, instance);
                        }
#if defined(CONFIG_SUN3)
                        if (phase == PHASE_CMDOUT) {
#if defined(REAL_DMA)
                                void *d;
                                unsigned long count;

                                if (!cmd->SCp.this_residual && cmd->SCp.buffers_residual) {
                                        count = cmd->SCp.buffer->length;
                                        d = sg_virt(cmd->SCp.buffer);
                                } else {
                                        count = cmd->SCp.this_residual;
                                        d = cmd->SCp.ptr;
                                }
                                /* this command setup for dma yet? */
                                if ((count >= DMA_MIN_SIZE) && (sun3_dma_setup_done != cmd)) {
                                        if (cmd->request->cmd_type == REQ_TYPE_FS) {
                                                sun3scsi_dma_setup(d, count,
                                                                   rq_data_dir(cmd->request));
                                                sun3_dma_setup_done = cmd;
                                        }
                                }
#endif
#ifdef SUN3_SCSI_VME
                                dregs->csr |= CSR_INTR;
#endif
                        }
#endif /* CONFIG_SUN3 */

                        if (sink && (phase != PHASE_MSGOUT)) {
                                NCR5380_write(TARGET_COMMAND_REG, PHASE_SR_TO_TCR(tmp));

                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN |
                                              ICR_ASSERT_ACK);
                                while (NCR5380_read(STATUS_REG) & SR_REQ)
                                        ;
                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE |
                                              ICR_ASSERT_ATN);
                                sink = 0;
                                continue;
                        }

                        switch (phase) {
                        case PHASE_DATAOUT:
#if (NDEBUG & NDEBUG_NO_DATAOUT)
                                printk("scsi%d: NDEBUG_NO_DATAOUT set, attempted DATAOUT "
                                       "aborted\n", HOSTNO);
                                sink = 1;
                                do_abort(instance);
                                cmd->result = DID_ERROR << 16;
                                cmd->scsi_done(cmd);
                                return;
#endif
                        case PHASE_DATAIN:
                                /*
                                 * If there is no room left in the current buffer in the
                                 * scatter-gather list, move onto the next one.
                                 */

                                if (!cmd->SCp.this_residual && cmd->SCp.buffers_residual) {
                                        ++cmd->SCp.buffer;
                                        --cmd->SCp.buffers_residual;
                                        cmd->SCp.this_residual = cmd->SCp.buffer->length;
                                        cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
                                        /* ++roman: Try to merge some scatter-buffers if
                                         * they are at contiguous physical addresses.
                                         */
                                        merge_contiguous_buffers(cmd);
                                        dprintk(NDEBUG_INFORMATION, "scsi%d: %d bytes and %d buffers left\n",
                                                   HOSTNO, cmd->SCp.this_residual,
                                                   cmd->SCp.buffers_residual);
                                }

                                /*
                                 * The preferred transfer method is going to be
                                 * PSEUDO-DMA for systems that are strictly PIO,
                                 * since we can let the hardware do the handshaking.
                                 *
                                 * For this to work, we need to know the transfersize
                                 * ahead of time, since the pseudo-DMA code will sit
                                 * in an unconditional loop.
                                 */

                                /* ++roman: I suggest, this should be
                                 *   #if def(REAL_DMA)
                                 * instead of leaving REAL_DMA out.
                                 */

#if defined(REAL_DMA)
                                if (
#if !defined(CONFIG_SUN3)
                                    !cmd->device->borken &&
#endif
                                    (transfersize = NCR5380_dma_xfer_len(instance, cmd, phase)) >= DMA_MIN_SIZE) {
                                        len = transfersize;
                                        cmd->SCp.phase = phase;
                                        if (NCR5380_transfer_dma(instance, &phase,
                                            &len, (unsigned char **)&cmd->SCp.ptr)) {
                                                /*
                                                 * If the watchdog timer fires, all future
                                                 * accesses to this device will use the
                                                 * polled-IO. */
                                                scmd_printk(KERN_INFO, cmd,
                                                        "switching to slow handshake\n");
                                                cmd->device->borken = 1;
                                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE |
                                                        ICR_ASSERT_ATN);
                                                sink = 1;
                                                do_abort(instance);
                                                cmd->result = DID_ERROR << 16;
                                                cmd->scsi_done(cmd);
                                                /* XXX - need to source or sink data here, as appropriate */
                                        } else {
#ifdef REAL_DMA
                                                /* ++roman: When using real DMA,
                                                 * information_transfer() should return after
                                                 * starting DMA since it has nothing more to
                                                 * do.
                                                 */
                                                return;
#else
                                                cmd->SCp.this_residual -= transfersize - len;
#endif
                                        }
                                } else
#endif /* defined(REAL_DMA) */
                                        NCR5380_transfer_pio(instance, &phase,
                                                             (int *)&cmd->SCp.this_residual,
                                                             (unsigned char **)&cmd->SCp.ptr);
#if defined(CONFIG_SUN3) && defined(REAL_DMA)
                                /* if we had intended to dma that command clear it */
                                if (sun3_dma_setup_done == cmd)
                                        sun3_dma_setup_done = NULL;
#endif
                                break;
                        case PHASE_MSGIN:
                                len = 1;
                                data = &tmp;
                                NCR5380_write(SELECT_ENABLE_REG, 0);    /* disable reselects */
                                NCR5380_transfer_pio(instance, &phase, &len, &data);
                                cmd->SCp.Message = tmp;

                                switch (tmp) {
                                /*
                                 * Linking lets us reduce the time required to get the
                                 * next command out to the device, hopefully this will
                                 * mean we don't waste another revolution due to the delays
                                 * required by ARBITRATION and another SELECTION.
                                 *
                                 * In the current implementation proposal, low level drivers
                                 * merely have to start the next command, pointed to by
                                 * next_link, done() is called as with unlinked commands.
                                 */
#ifdef LINKED
                                case LINKED_CMD_COMPLETE:
                                case LINKED_FLG_CMD_COMPLETE:
                                        /* Accept message by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

                                        dprintk(NDEBUG_LINKED, "scsi%d: target %d lun %llu linked command "
                                                   "complete.\n", HOSTNO, cmd->device->id, cmd->device->lun);

                                        /* Enable reselect interrupts */
                                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                                        /*
                                         * Sanity check : A linked command should only terminate
                                         * with one of these messages if there are more linked
                                         * commands available.
                                         */

                                        if (!cmd->next_link) {
                                                 printk(KERN_NOTICE "scsi%d: target %d lun %llu "
                                                        "linked command complete, no next_link\n",
                                                        HOSTNO, cmd->device->id, cmd->device->lun);
                                                sink = 1;
                                                do_abort(instance);
                                                return;
                                        }

                                        initialize_SCp(cmd->next_link);
                                        /* The next command is still part of this process; copy it
                                         * and don't free it! */
                                        cmd->next_link->tag = cmd->tag;
                                        cmd->result = cmd->SCp.Status | (cmd->SCp.Message << 8);
                                        dprintk(NDEBUG_LINKED, "scsi%d: target %d lun %llu linked request "
                                                   "done, calling scsi_done().\n",
                                                   HOSTNO, cmd->device->id, cmd->device->lun);
                                        cmd->scsi_done(cmd);
                                        cmd = hostdata->connected;
                                        break;
#endif /* def LINKED */
                                case ABORT:
                                case COMMAND_COMPLETE:
                                        /* Accept message by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                                        dprintk(NDEBUG_QUEUES, "scsi%d: command for target %d, lun %llu "
                                                  "completed\n", HOSTNO, cmd->device->id, cmd->device->lun);

                                        local_irq_save(flags);
                                        hostdata->retain_dma_intr++;
                                        hostdata->connected = NULL;
#ifdef SUPPORT_TAGS
                                        cmd_free_tag(cmd);
                                        if (status_byte(cmd->SCp.Status) == QUEUE_FULL) {
                                                /* Turn a QUEUE FULL status into BUSY, I think the
                                                 * mid level cannot handle QUEUE FULL :-( (The
                                                 * command is retried after BUSY). Also update our
                                                 * queue size to the number of currently issued
                                                 * commands now.
                                                 */
                                                /* ++Andreas: the mid level code knows about
                                                   QUEUE_FULL now. */
                                                TAG_ALLOC *ta = &TagAlloc[cmd->device->id][cmd->device->lun];
                                                dprintk(NDEBUG_TAGS, "scsi%d: target %d lun %llu returned "
                                                           "QUEUE_FULL after %d commands\n",
                                                           HOSTNO, cmd->device->id, cmd->device->lun,
                                                           ta->nr_allocated);
                                                if (ta->queue_size > ta->nr_allocated)
                                                        ta->nr_allocated = ta->queue_size;
                                        }
#else
                                        hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
#endif
                                        /* Enable reselect interrupts */
                                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);

                                        /*
                                         * I'm not sure what the correct thing to do here is :
                                         *
                                         * If the command that just executed is NOT a request
                                         * sense, the obvious thing to do is to set the result
                                         * code to the values of the stored parameters.
                                         *
                                         * If it was a REQUEST SENSE command, we need some way to
                                         * differentiate between the failure code of the original
                                         * and the failure code of the REQUEST sense - the obvious
                                         * case is success, where we fall through and leave the
                                         * result code unchanged.
                                         *
                                         * The non-obvious place is where the REQUEST SENSE failed
                                         */

                                        if (cmd->cmnd[0] != REQUEST_SENSE)
                                                cmd->result = cmd->SCp.Status | (cmd->SCp.Message << 8);
                                        else if (status_byte(cmd->SCp.Status) != GOOD)
                                                cmd->result = (cmd->result & 0x00ffff) | (DID_ERROR << 16);

                                        if ((cmd->cmnd[0] == REQUEST_SENSE) &&
                                                hostdata->ses.cmd_len) {
                                                scsi_eh_restore_cmnd(cmd, &hostdata->ses);
                                                hostdata->ses.cmd_len = 0 ;
                                        }

                                        if ((cmd->cmnd[0] != REQUEST_SENSE) &&
                                            (status_byte(cmd->SCp.Status) == CHECK_CONDITION)) {
                                                scsi_eh_prep_cmnd(cmd, &hostdata->ses, NULL, 0, ~0);

                                                dprintk(NDEBUG_AUTOSENSE, "scsi%d: performing request sense\n", HOSTNO);

                                                LIST(cmd,hostdata->issue_queue);
                                                SET_NEXT(cmd, hostdata->issue_queue);
                                                hostdata->issue_queue = (struct scsi_cmnd *) cmd;
                                                dprintk(NDEBUG_QUEUES, "scsi%d: REQUEST SENSE added to head of "
                                                          "issue queue\n", H_NO(cmd));
                                        } else {
                                                cmd->scsi_done(cmd);
                                        }

                                        local_irq_restore(flags);

                                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                                        /*
                                         * Restore phase bits to 0 so an interrupted selection,
                                         * arbitration can resume.
                                         */
                                        NCR5380_write(TARGET_COMMAND_REG, 0);

                                        while ((NCR5380_read(STATUS_REG) & SR_BSY) && !hostdata->connected)
                                                barrier();

                                        local_irq_save(flags);
                                        hostdata->retain_dma_intr--;
                                        /* ++roman: For Falcon SCSI, release the lock on the
                                         * ST-DMA here if no other commands are waiting on the
                                         * disconnected queue.
                                         */
                                        maybe_release_dma_irq(instance);
                                        local_irq_restore(flags);
                                        return;
                                case MESSAGE_REJECT:
                                        /* Accept message by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                                        /* Enable reselect interrupts */
                                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                                        switch (hostdata->last_message) {
                                        case HEAD_OF_QUEUE_TAG:
                                        case ORDERED_QUEUE_TAG:
                                        case SIMPLE_QUEUE_TAG:
                                                /* The target obviously doesn't support tagged
                                                 * queuing, even though it announced this ability in
                                                 * its INQUIRY data ?!? (maybe only this LUN?) Ok,
                                                 * clear 'tagged_supported' and lock the LUN, since
                                                 * the command is treated as untagged further on.
                                                 */
                                                cmd->device->tagged_supported = 0;
                                                hostdata->busy[cmd->device->id] |= (1 << cmd->device->lun);
                                                cmd->tag = TAG_NONE;
                                                dprintk(NDEBUG_TAGS, "scsi%d: target %d lun %llu rejected "
                                                           "QUEUE_TAG message; tagged queuing "
                                                           "disabled\n",
                                                           HOSTNO, cmd->device->id, cmd->device->lun);
                                                break;
                                        }
                                        break;
                                case DISCONNECT:
                                        /* Accept message by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                                        local_irq_save(flags);
                                        cmd->device->disconnect = 1;
                                        LIST(cmd,hostdata->disconnected_queue);
                                        SET_NEXT(cmd, hostdata->disconnected_queue);
                                        hostdata->connected = NULL;
                                        hostdata->disconnected_queue = cmd;
                                        local_irq_restore(flags);
                                        dprintk(NDEBUG_QUEUES, "scsi%d: command for target %d lun %llu was "
                                                  "moved from connected to the "
                                                  "disconnected_queue\n", HOSTNO,
                                                  cmd->device->id, cmd->device->lun);
                                        /*
                                         * Restore phase bits to 0 so an interrupted selection,
                                         * arbitration can resume.
                                         */
                                        NCR5380_write(TARGET_COMMAND_REG, 0);

                                        /* Enable reselect interrupts */
                                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                                        /* Wait for bus free to avoid nasty timeouts */
                                        while ((NCR5380_read(STATUS_REG) & SR_BSY) && !hostdata->connected)
                                                barrier();
#ifdef SUN3_SCSI_VME
                                        dregs->csr |= CSR_DMA_ENABLE;
#endif
                                        return;
                                        /*
                                         * The SCSI data pointer is *IMPLICITLY* saved on a disconnect
                                         * operation, in violation of the SCSI spec so we can safely
                                         * ignore SAVE/RESTORE pointers calls.
                                         *
                                         * Unfortunately, some disks violate the SCSI spec and
                                         * don't issue the required SAVE_POINTERS message before
                                         * disconnecting, and we have to break spec to remain
                                         * compatible.
                                         */
                                case SAVE_POINTERS:
                                case RESTORE_POINTERS:
                                        /* Accept message by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                                        /* Enable reselect interrupts */
                                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                                        break;
                                case EXTENDED_MESSAGE:
                                        /*
                                         * Extended messages are sent in the following format :
                                         * Byte
                                         * 0            EXTENDED_MESSAGE == 1
                                         * 1            length (includes one byte for code, doesn't
                                         *              include first two bytes)
                                         * 2            code
                                         * 3..length+1  arguments
                                         *
                                         * Start the extended message buffer with the EXTENDED_MESSAGE
                                         * byte, since spi_print_msg() wants the whole thing.
                                         */
                                        extended_msg[0] = EXTENDED_MESSAGE;
                                        /* Accept first byte by clearing ACK */
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

                                        dprintk(NDEBUG_EXTENDED, "scsi%d: receiving extended message\n", HOSTNO);

                                        len = 2;
                                        data = extended_msg + 1;
                                        phase = PHASE_MSGIN;
                                        NCR5380_transfer_pio(instance, &phase, &len, &data);
                                        dprintk(NDEBUG_EXTENDED, "scsi%d: length=%d, code=0x%02x\n", HOSTNO,
                                                   (int)extended_msg[1], (int)extended_msg[2]);

                                        if (!len && extended_msg[1] <=
                                            (sizeof(extended_msg) - 1)) {
                                                /* Accept third byte by clearing ACK */
                                                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                                                len = extended_msg[1] - 1;
                                                data = extended_msg + 3;
                                                phase = PHASE_MSGIN;

                                                NCR5380_transfer_pio(instance, &phase, &len, &data);
                                                dprintk(NDEBUG_EXTENDED, "scsi%d: message received, residual %d\n",
                                                           HOSTNO, len);

                                                switch (extended_msg[2]) {
                                                case EXTENDED_SDTR:
                                                case EXTENDED_WDTR:
                                                case EXTENDED_MODIFY_DATA_POINTER:
                                                case EXTENDED_EXTENDED_IDENTIFY:
                                                        tmp = 0;
                                                }
                                        } else if (len) {
                                                printk(KERN_NOTICE "scsi%d: error receiving "
                                                       "extended message\n", HOSTNO);
                                                tmp = 0;
                                        } else {
                                                printk(KERN_NOTICE "scsi%d: extended message "
                                                           "code %02x length %d is too long\n",
                                                           HOSTNO, extended_msg[2], extended_msg[1]);
                                                tmp = 0;
                                        }
                                        /* Fall through to reject message */

                                        /*
                                         * If we get something weird that we aren't expecting,
                                         * reject it.
                                         */
                                default:
                                        if (!tmp) {
                                                printk(KERN_INFO "scsi%d: rejecting message ",
                                                       instance->host_no);
                                                spi_print_msg(extended_msg);
                                                printk("\n");
                                        } else if (tmp != EXTENDED_MESSAGE)
                                                scmd_printk(KERN_INFO, cmd,
                                                            "rejecting unknown message %02x\n",
                                                            tmp);
                                        else
                                                scmd_printk(KERN_INFO, cmd,
                                                            "rejecting unknown extended message code %02x, length %d\n",
                                                            extended_msg[1], extended_msg[0]);

                                        msgout = MESSAGE_REJECT;
                                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
                                        break;
                                } /* switch (tmp) */
                                break;
                        case PHASE_MSGOUT:
                                len = 1;
                                data = &msgout;
                                hostdata->last_message = msgout;
                                NCR5380_transfer_pio(instance, &phase, &len, &data);
                                if (msgout == ABORT) {
                                        local_irq_save(flags);
#ifdef SUPPORT_TAGS
                                        cmd_free_tag(cmd);
#else
                                        hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
#endif
                                        hostdata->connected = NULL;
                                        cmd->result = DID_ERROR << 16;
                                        NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                                        maybe_release_dma_irq(instance);
                                        local_irq_restore(flags);
                                        cmd->scsi_done(cmd);
                                        return;
                                }
                                msgout = NOP;
                                break;
                        case PHASE_CMDOUT:
                                len = cmd->cmd_len;
                                data = cmd->cmnd;
                                /*
                                 * XXX for performance reasons, on machines with a
                                 * PSEUDO-DMA architecture we should probably
                                 * use the dma transfer function.
                                 */
                                NCR5380_transfer_pio(instance, &phase, &len, &data);
                                break;
                        case PHASE_STATIN:
                                len = 1;
                                data = &tmp;
                                NCR5380_transfer_pio(instance, &phase, &len, &data);
                                cmd->SCp.Status = tmp;
                                break;
                        default:
                                printk("scsi%d: unknown phase\n", HOSTNO);
                                NCR5380_dprint(NDEBUG_ANY, instance);
                        } /* switch(phase) */
                } /* if (tmp * SR_REQ) */
        } /* while (1) */
}

/*
 * Function : void NCR5380_reselect (struct Scsi_Host *instance)
 *
 * Purpose : does reselection, initializing the instance->connected
 *      field to point to the scsi_cmnd for which the I_T_L or I_T_L_Q
 *      nexus has been reestablished,
 *
 * Inputs : instance - this instance of the NCR5380.
 *
 */


/* it might eventually prove necessary to do a dma setup on
   reselection, but it doesn't seem to be needed now -- sam */

static void NCR5380_reselect(struct Scsi_Host *instance)
{
        SETUP_HOSTDATA(instance);
        unsigned char target_mask;
        unsigned char lun;
#ifdef SUPPORT_TAGS
        unsigned char tag;
#endif
        unsigned char msg[3];
        int __maybe_unused len;
        unsigned char __maybe_unused *data, __maybe_unused phase;
        struct scsi_cmnd *tmp = NULL, *prev;

        /*
         * Disable arbitration, etc. since the host adapter obviously
         * lost, and tell an interrupted NCR5380_select() to restart.
         */

        NCR5380_write(MODE_REG, MR_BASE);
        hostdata->restart_select = 1;

        target_mask = NCR5380_read(CURRENT_SCSI_DATA_REG) & ~(hostdata->id_mask);

        dprintk(NDEBUG_RESELECTION, "scsi%d: reselect\n", HOSTNO);

        /*
         * At this point, we have detected that our SCSI ID is on the bus,
         * SEL is true and BSY was false for at least one bus settle delay
         * (400 ns).
         *
         * We must assert BSY ourselves, until the target drops the SEL
         * signal.
         */

        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_BSY);

        while (NCR5380_read(STATUS_REG) & SR_SEL)
                ;
        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

        /*
         * Wait for target to go into MSGIN.
         */

        while (!(NCR5380_read(STATUS_REG) & SR_REQ))
                ;

#if defined(CONFIG_SUN3) && defined(REAL_DMA)
        /* acknowledge toggle to MSGIN */
        NCR5380_write(TARGET_COMMAND_REG, PHASE_SR_TO_TCR(PHASE_MSGIN));

        /* peek at the byte without really hitting the bus */
        msg[0] = NCR5380_read(CURRENT_SCSI_DATA_REG);
#else
        len = 1;
        data = msg;
        phase = PHASE_MSGIN;
        NCR5380_transfer_pio(instance, &phase, &len, &data);
#endif

        if (!(msg[0] & 0x80)) {
                printk(KERN_DEBUG "scsi%d: expecting IDENTIFY message, got ", HOSTNO);
                spi_print_msg(msg);
                do_abort(instance);
                return;
        }
        lun = (msg[0] & 0x07);

#if defined(SUPPORT_TAGS) && !defined(CONFIG_SUN3)
        /* If the phase is still MSGIN, the target wants to send some more
         * messages. In case it supports tagged queuing, this is probably a
         * SIMPLE_QUEUE_TAG for the I_T_L_Q nexus.
         */
        tag = TAG_NONE;
        if (phase == PHASE_MSGIN && (hostdata->flags & FLAG_TAGGED_QUEUING)) {
                /* Accept previous IDENTIFY message by clearing ACK */
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                len = 2;
                data = msg + 1;
                if (!NCR5380_transfer_pio(instance, &phase, &len, &data) &&
                    msg[1] == SIMPLE_QUEUE_TAG)
                        tag = msg[2];
                dprintk(NDEBUG_TAGS, "scsi%d: target mask %02x, lun %d sent tag %d at "
                           "reselection\n", HOSTNO, target_mask, lun, tag);
        }
#endif

        /*
         * Find the command corresponding to the I_T_L or I_T_L_Q  nexus we
         * just reestablished, and remove it from the disconnected queue.
         */

        for (tmp = (struct scsi_cmnd *) hostdata->disconnected_queue, prev = NULL;
             tmp; prev = tmp, tmp = NEXT(tmp)) {
                if ((target_mask == (1 << tmp->device->id)) && (lun == tmp->device->lun)
#ifdef SUPPORT_TAGS
                    && (tag == tmp->tag)
#endif
                    ) {
                        if (prev) {
                                REMOVE(prev, NEXT(prev), tmp, NEXT(tmp));
                                SET_NEXT(prev, NEXT(tmp));
                        } else {
                                REMOVE(-1, hostdata->disconnected_queue, tmp, NEXT(tmp));
                                hostdata->disconnected_queue = NEXT(tmp);
                        }
                        SET_NEXT(tmp, NULL);
                        break;
                }
        }

        if (!tmp) {
                printk(KERN_WARNING "scsi%d: warning: target bitmask %02x lun %d "
#ifdef SUPPORT_TAGS
                       "tag %d "
#endif
                       "not in disconnected_queue.\n",
                       HOSTNO, target_mask, lun
#ifdef SUPPORT_TAGS
                       , tag
#endif
                        );
                /*
                 * Since we have an established nexus that we can't do anything
                 * with, we must abort it.
                 */
                do_abort(instance);
                return;
        }

#if defined(CONFIG_SUN3) && defined(REAL_DMA)
        /* engage dma setup for the command we just saw */
        {
                void *d;
                unsigned long count;

                if (!tmp->SCp.this_residual && tmp->SCp.buffers_residual) {
                        count = tmp->SCp.buffer->length;
                        d = sg_virt(tmp->SCp.buffer);
                } else {
                        count = tmp->SCp.this_residual;
                        d = tmp->SCp.ptr;
                }
                /* setup this command for dma if not already */
                if ((count >= DMA_MIN_SIZE) && (sun3_dma_setup_done != tmp)) {
                        sun3scsi_dma_setup(d, count, rq_data_dir(tmp->request));
                        sun3_dma_setup_done = tmp;
                }
        }

        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ACK);
#endif

        /* Accept message by clearing ACK */
        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

#if defined(SUPPORT_TAGS) && defined(CONFIG_SUN3)
        /* If the phase is still MSGIN, the target wants to send some more
         * messages. In case it supports tagged queuing, this is probably a
         * SIMPLE_QUEUE_TAG for the I_T_L_Q nexus.
         */
        tag = TAG_NONE;
        if (phase == PHASE_MSGIN && setup_use_tagged_queuing) {
                /* Accept previous IDENTIFY message by clearing ACK */
                NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
                len = 2;
                data = msg + 1;
                if (!NCR5380_transfer_pio(instance, &phase, &len, &data) &&
                    msg[1] == SIMPLE_QUEUE_TAG)
                        tag = msg[2];
                dprintk(NDEBUG_TAGS, "scsi%d: target mask %02x, lun %d sent tag %d at reselection\n"
                        HOSTNO, target_mask, lun, tag);
        }
#endif

        hostdata->connected = tmp;
        dprintk(NDEBUG_RESELECTION, "scsi%d: nexus established, target = %d, lun = %llu, tag = %d\n",
                   HOSTNO, tmp->device->id, tmp->device->lun, tmp->tag);
}


/*
 * Function : int NCR5380_abort (struct scsi_cmnd *cmd)
 *
 * Purpose : abort a command
 *
 * Inputs : cmd - the scsi_cmnd to abort, code - code to set the
 *      host byte of the result field to, if zero DID_ABORTED is
 *      used.
 *
 * Returns : SUCCESS - success, FAILED on failure.
 *
 * XXX - there is no way to abort the command that is currently
 *       connected, you have to wait for it to complete.  If this is
 *       a problem, we could implement longjmp() / setjmp(), setjmp()
 *       called where the loop started in NCR5380_main().
 */

static
int NCR5380_abort(struct scsi_cmnd *cmd)
{
        struct Scsi_Host *instance = cmd->device->host;
        SETUP_HOSTDATA(instance);
        struct scsi_cmnd *tmp, **prev;
        unsigned long flags;

        scmd_printk(KERN_NOTICE, cmd, "aborting command\n");

        NCR5380_print_status(instance);

        local_irq_save(flags);

        dprintk(NDEBUG_ABORT, "scsi%d: abort called basr 0x%02x, sr 0x%02x\n", HOSTNO,
                    NCR5380_read(BUS_AND_STATUS_REG),
                    NCR5380_read(STATUS_REG));

#if 1
        /*
         * Case 1 : If the command is the currently executing command,
         * we'll set the aborted flag and return control so that
         * information transfer routine can exit cleanly.
         */

        if (hostdata->connected == cmd) {

                dprintk(NDEBUG_ABORT, "scsi%d: aborting connected command\n", HOSTNO);
                /*
                 * We should perform BSY checking, and make sure we haven't slipped
                 * into BUS FREE.
                 */

                /*      NCR5380_write(INITIATOR_COMMAND_REG, ICR_ASSERT_ATN); */
                /*
                 * Since we can't change phases until we've completed the current
                 * handshake, we have to source or sink a byte of data if the current
                 * phase is not MSGOUT.
                 */

                /*
                 * Return control to the executing NCR drive so we can clear the
                 * aborted flag and get back into our main loop.
                 */

                if (do_abort(instance) == 0) {
                        hostdata->aborted = 1;
                        hostdata->connected = NULL;
                        cmd->result = DID_ABORT << 16;
#ifdef SUPPORT_TAGS
                        cmd_free_tag(cmd);
#else
                        hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
#endif
                        maybe_release_dma_irq(instance);
                        local_irq_restore(flags);
                        cmd->scsi_done(cmd);
                        return SUCCESS;
                } else {
                        local_irq_restore(flags);
                        printk("scsi%d: abort of connected command failed!\n", HOSTNO);
                        return FAILED;
                }
        }
#endif

        /*
         * Case 2 : If the command hasn't been issued yet, we simply remove it
         *          from the issue queue.
         */
        for (prev = (struct scsi_cmnd **)&(hostdata->issue_queue),
             tmp = (struct scsi_cmnd *)hostdata->issue_queue;
             tmp; prev = NEXTADDR(tmp), tmp = NEXT(tmp)) {
                if (cmd == tmp) {
                        REMOVE(5, *prev, tmp, NEXT(tmp));
                        (*prev) = NEXT(tmp);
                        SET_NEXT(tmp, NULL);
                        tmp->result = DID_ABORT << 16;
                        maybe_release_dma_irq(instance);
                        local_irq_restore(flags);
                        dprintk(NDEBUG_ABORT, "scsi%d: abort removed command from issue queue.\n",
                                    HOSTNO);
                        /* Tagged queuing note: no tag to free here, hasn't been assigned
                         * yet... */
                        tmp->scsi_done(tmp);
                        return SUCCESS;
                }
        }

        /*
         * Case 3 : If any commands are connected, we're going to fail the abort
         *          and let the high level SCSI driver retry at a later time or
         *          issue a reset.
         *
         *          Timeouts, and therefore aborted commands, will be highly unlikely
         *          and handling them cleanly in this situation would make the common
         *          case of noresets less efficient, and would pollute our code.  So,
         *          we fail.
         */

        if (hostdata->connected) {
                local_irq_restore(flags);
                dprintk(NDEBUG_ABORT, "scsi%d: abort failed, command connected.\n", HOSTNO);
                return FAILED;
        }

        /*
         * Case 4: If the command is currently disconnected from the bus, and
         *      there are no connected commands, we reconnect the I_T_L or
         *      I_T_L_Q nexus associated with it, go into message out, and send
         *      an abort message.
         *
         * This case is especially ugly. In order to reestablish the nexus, we
         * need to call NCR5380_select().  The easiest way to implement this
         * function was to abort if the bus was busy, and let the interrupt
         * handler triggered on the SEL for reselect take care of lost arbitrations
         * where necessary, meaning interrupts need to be enabled.
         *
         * When interrupts are enabled, the queues may change - so we
         * can't remove it from the disconnected queue before selecting it
         * because that could cause a failure in hashing the nexus if that
         * device reselected.
         *
         * Since the queues may change, we can't use the pointers from when we
         * first locate it.
         *
         * So, we must first locate the command, and if NCR5380_select()
         * succeeds, then issue the abort, relocate the command and remove
         * it from the disconnected queue.
         */

        for (tmp = (struct scsi_cmnd *) hostdata->disconnected_queue; tmp;
             tmp = NEXT(tmp)) {
                if (cmd == tmp) {
                        local_irq_restore(flags);
                        dprintk(NDEBUG_ABORT, "scsi%d: aborting disconnected command.\n", HOSTNO);

                        if (NCR5380_select(instance, cmd))
                                return FAILED;

                        dprintk(NDEBUG_ABORT, "scsi%d: nexus reestablished.\n", HOSTNO);

                        do_abort(instance);

                        local_irq_save(flags);
                        for (prev = (struct scsi_cmnd **)&(hostdata->disconnected_queue),
                             tmp = (struct scsi_cmnd *)hostdata->disconnected_queue;
                             tmp; prev = NEXTADDR(tmp), tmp = NEXT(tmp)) {
                                if (cmd == tmp) {
                                        REMOVE(5, *prev, tmp, NEXT(tmp));
                                        *prev = NEXT(tmp);
                                        SET_NEXT(tmp, NULL);
                                        tmp->result = DID_ABORT << 16;
                                        /* We must unlock the tag/LUN immediately here, since the
                                         * target goes to BUS FREE and doesn't send us another
                                         * message (COMMAND_COMPLETE or the like)
                                         */
#ifdef SUPPORT_TAGS
                                        cmd_free_tag(tmp);
#else
                                        hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
#endif
                                        maybe_release_dma_irq(instance);
                                        local_irq_restore(flags);
                                        tmp->scsi_done(tmp);
                                        return SUCCESS;
                                }
                        }
                }
        }

        /* Maybe it is sufficient just to release the ST-DMA lock... (if
         * possible at all) At least, we should check if the lock could be
         * released after the abort, in case it is kept due to some bug.
         */
        maybe_release_dma_irq(instance);
        local_irq_restore(flags);

        /*
         * Case 5 : If we reached this point, the command was not found in any of
         *          the queues.
         *
         * We probably reached this point because of an unlikely race condition
         * between the command completing successfully and the abortion code,
         * so we won't panic, but we will notify the user in case something really
         * broke.
         */

        printk(KERN_INFO "scsi%d: warning : SCSI command probably completed successfully before abortion\n", HOSTNO);

        return FAILED;
}


/*
 * Function : int NCR5380_reset (struct scsi_cmnd *cmd)
 *
 * Purpose : reset the SCSI bus.
 *
 * Returns : SUCCESS or FAILURE
 *
 */

static int NCR5380_bus_reset(struct scsi_cmnd *cmd)
{
        struct Scsi_Host *instance = cmd->device->host;
        struct NCR5380_hostdata *hostdata = shost_priv(instance);
        int i;
        unsigned long flags;
#if defined(RESET_RUN_DONE)
        struct scsi_cmnd *connected, *disconnected_queue;
#endif

        NCR5380_print_status(instance);

        /* get in phase */
        NCR5380_write(TARGET_COMMAND_REG,
                      PHASE_SR_TO_TCR(NCR5380_read(STATUS_REG)));
        /* assert RST */
        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_RST);
        udelay(40);
        /* reset NCR registers */
        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
        NCR5380_write(MODE_REG, MR_BASE);
        NCR5380_write(TARGET_COMMAND_REG, 0);
        NCR5380_write(SELECT_ENABLE_REG, 0);
        /* ++roman: reset interrupt condition! otherwise no interrupts don't get
         * through anymore ... */
        (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);

        /* MSch 20140115 - looking at the generic NCR5380 driver, all of this
         * should go.
         * Catch-22: if we don't clear all queues, the SCSI driver lock will
         * not be reset by atari_scsi_reset()!
         */

#if defined(RESET_RUN_DONE)
        /* XXX Should now be done by midlevel code, but it's broken XXX */
        /* XXX see below                                            XXX */

        /* MSch: old-style reset: actually abort all command processing here */

        /* After the reset, there are no more connected or disconnected commands
         * and no busy units; to avoid problems with re-inserting the commands
         * into the issue_queue (via scsi_done()), the aborted commands are
         * remembered in local variables first.
         */
        local_irq_save(flags);
        connected = (struct scsi_cmnd *)hostdata->connected;
        hostdata->connected = NULL;
        disconnected_queue = (struct scsi_cmnd *)hostdata->disconnected_queue;
        hostdata->disconnected_queue = NULL;
#ifdef SUPPORT_TAGS
        free_all_tags();
#endif
        for (i = 0; i < 8; ++i)
                hostdata->busy[i] = 0;
#ifdef REAL_DMA
        hostdata->dma_len = 0;
#endif
        local_irq_restore(flags);

        /* In order to tell the mid-level code which commands were aborted,
         * set the command status to DID_RESET and call scsi_done() !!!
         * This ultimately aborts processing of these commands in the mid-level.
         */

        if ((cmd = connected)) {
                dprintk(NDEBUG_ABORT, "scsi%d: reset aborted a connected command\n", H_NO(cmd));
                cmd->result = (cmd->result & 0xffff) | (DID_RESET << 16);
                cmd->scsi_done(cmd);
        }

        for (i = 0; (cmd = disconnected_queue); ++i) {
                disconnected_queue = NEXT(cmd);
                SET_NEXT(cmd, NULL);
                cmd->result = (cmd->result & 0xffff) | (DID_RESET << 16);
                cmd->scsi_done(cmd);
        }
        if (i > 0)
                dprintk(NDEBUG_ABORT, "scsi: reset aborted %d disconnected command(s)\n", i);

        /* The Falcon lock should be released after a reset...
         */
        /* ++guenther: moved to atari_scsi_reset(), to prevent a race between
         * unlocking and enabling dma interrupt.
         */
/*      falcon_release_lock_if_possible( hostdata );*/

        /* since all commands have been explicitly terminated, we need to tell
         * the midlevel code that the reset was SUCCESSFUL, and there is no
         * need to 'wake up' the commands by a request_sense
         */
        return SUCCESS;
#else /* 1 */

        /* MSch: new-style reset handling: let the mid-level do what it can */

        /* ++guenther: MID-LEVEL IS STILL BROKEN.
         * Mid-level is supposed to requeue all commands that were active on the
         * various low-level queues. In fact it does this, but that's not enough
         * because all these commands are subject to timeout. And if a timeout
         * happens for any removed command, *_abort() is called but all queues
         * are now empty. Abort then gives up the falcon lock, which is fatal,
         * since the mid-level will queue more commands and must have the lock
         * (it's all happening inside timer interrupt handler!!).
         * Even worse, abort will return NOT_RUNNING for all those commands not
         * on any queue, so they won't be retried ...
         *
         * Conclusion: either scsi.c disables timeout for all resetted commands
         * immediately, or we lose!  As of linux-2.0.20 it doesn't.
         */

        /* After the reset, there are no more connected or disconnected commands
         * and no busy units; so clear the low-level status here to avoid
         * conflicts when the mid-level code tries to wake up the affected
         * commands!
         */

        if (hostdata->issue_queue)
                dprintk(NDEBUG_ABORT, "scsi%d: reset aborted issued command(s)\n", H_NO(cmd));
        if (hostdata->connected)
                dprintk(NDEBUG_ABORT, "scsi%d: reset aborted a connected command\n", H_NO(cmd));
        if (hostdata->disconnected_queue)
                dprintk(NDEBUG_ABORT, "scsi%d: reset aborted disconnected command(s)\n", H_NO(cmd));

        local_irq_save(flags);
        hostdata->issue_queue = NULL;
        hostdata->connected = NULL;
        hostdata->disconnected_queue = NULL;
#ifdef SUPPORT_TAGS
        free_all_tags(hostdata);
#endif
        for (i = 0; i < 8; ++i)
                hostdata->busy[i] = 0;
#ifdef REAL_DMA
        hostdata->dma_len = 0;
#endif

        maybe_release_dma_irq(instance);
        local_irq_restore(flags);

        /* we did no complete reset of all commands, so a wakeup is required */
        return SUCCESS;
#endif /* 1 */
}