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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
 *
 * DISTRIBUTION RELEASE 6.
 *
 * 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.
 */
#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
 * Issues :
 *
 * The other Linux SCSI drivers were written when Linux was Intel PC-only,
 * and specifically for each board rather than each chip.  This makes their
 * adaptation to platforms like the Mac (Some of which use NCR5380's)
 * more difficult than it has to be.
 *
 * Also, many of the SCSI drivers were written before the command queuing
 * routines were implemented, meaning their implementations of queued
 * commands were hacked on rather than designed in from the start.
 *
 * When I designed the Linux SCSI drivers I figured that
 * while having two different SCSI boards in a system might be useful
 * for debugging things, two of the same type wouldn't be used.
 * Well, I was wrong and a number of users have mailed me about running
 * multiple high-performance SCSI boards in a server.
 *
 * Finally, when I get questions from users, I have no idea what
 * revision of my driver they are running.
 *
 * This driver attempts to address these problems :
 * 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.
 *
 * To solve the multiple-boards-in-the-same-system problem,
 * there is a separate instance structure for each instance
 * of a 5380 in the system.  So, multiple NCR5380 drivers will
 * be able to coexist with appropriate changes to the high level
 * SCSI code.
 *
 * A NCR5380_PUBLIC_REVISION macro is provided, with the release
 * number (updated for each public release) printed by the
 * NCR5380_print_options command, which should be called from the
 * wrapper detect function, so that I know what release of the driver
 * users are using.
 *
 * 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 when not running by the interrupt handler,
 * timer, and queue command function.  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 USLEEP
 * was defined, and 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.
 *
 * 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
 *
 * 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);
 *
 * If nothing specific to this implementation needs doing (ie, with external
 * hardware), you must also define
 *
 * NCR5380_queue_command
 * NCR5380_reset
 * NCR5380_abort
 * NCR5380_proc_info
 *
 * to be the global entry points into the specific driver, ie
 * #define NCR5380_queue_command t128_queue_command.
 *
 * If this is not done, the routines will be defined as static functions
 * with the NCR5380* names and the user must provide a globally
 * accessible wrapper function.
 *
 * 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.  Before the specific driver initialization
 * code finishes, NCR5380_print_options should be called.
 */

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)         ((Scsi_Cmnd *)(cmd)->host_scribble)
#define     SET_NEXT(cmd,next)      ((cmd)->host_scribble = (void *)(next))
#define     NEXTADDR(cmd)           ((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.
 */

/* -1 for TAG_NONE is not possible with unsigned char cmd->tag */
#undef TAG_NONE
#define TAG_NONE 0xff

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(void)
{
      int target, lun;
      TAG_ALLOC *ta;

      if (!setup_use_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(Scsi_Cmnd *cmd, int should_be_tagged)
{
      SETUP_HOSTDATA(cmd->device->host);

      if (hostdata->busy[cmd->device->id] & (1 << cmd->device->lun))
            return 1;
      if (!should_be_tagged ||
          !setup_use_tagged_queuing || !cmd->device->tagged_supported)
            return 0;
      if (TagAlloc[cmd->device->id][cmd->device->lun].nr_allocated >=
          TagAlloc[cmd->device->id][cmd->device->lun].queue_size) {
            TAG_PRINTK("scsi%d: target %d lun %d: no free tags\n",
                     H_NO(cmd), cmd->device->id, cmd->device->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(Scsi_Cmnd *cmd, int should_be_tagged)
{
      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 ||
          !setup_use_tagged_queuing || !cmd->device->tagged_supported) {
            cmd->tag = TAG_NONE;
            hostdata->busy[cmd->device->id] |= (1 << cmd->device->lun);
            TAG_PRINTK("scsi%d: target %d lun %d now allocated by untagged "
                     "command\n", H_NO(cmd), cmd->device->id, cmd->device->lun);
      } else {
            TAG_ALLOC *ta = &TagAlloc[cmd->device->id][cmd->device->lun];

            cmd->tag = find_first_zero_bit(ta->allocated, MAX_TAGS);
            set_bit(cmd->tag, ta->allocated);
            ta->nr_allocated++;
            TAG_PRINTK("scsi%d: using tag %d for target %d lun %d "
                     "(now %d tags in use)\n",
                     H_NO(cmd), cmd->tag, cmd->device->id,
                     cmd->device->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(Scsi_Cmnd *cmd)
{
      SETUP_HOSTDATA(cmd->device->host);

      if (cmd->tag == TAG_NONE) {
            hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
            TAG_PRINTK("scsi%d: target %d lun %d untagged cmd finished\n",
                     H_NO(cmd), cmd->device->id, cmd->device->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][cmd->device->lun];
            clear_bit(cmd->tag, ta->allocated);
            ta->nr_allocated--;
            TAG_PRINTK("scsi%d: freed tag %d for target %d lun %d\n",
                     H_NO(cmd), cmd->tag, cmd->device->id, cmd->device->lun);
      }
}


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

      if (!setup_use_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( 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: Scsi_Cmnd *cmd
 *    The command to work on. The first scatter buffer's data are
 *    assumed to be already transfered into ptr/this_residual.
 */

static void merge_contiguous_buffers(Scsi_Cmnd *cmd)
{
      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;) {
            MER_PRINTK("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)
            MER_PRINTK("merged %d buffers from %p, new length %08x\n",
                     cnt, cmd->SCp.ptr, cmd->SCp.this_residual);
#endif
}

/*
 * Function : void initialize_SCp(Scsi_Cmnd *cmd)
 *
 * Purpose : initialize the saved data pointers for cmd to point to the
 *    start of the buffer.
 *
 * Inputs : cmd - Scsi_Cmnd structure to have pointers reset.
 */

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

      if (cmd->use_sg) {
            cmd->SCp.buffer = (struct scatterlist *)cmd->request_buffer;
            cmd->SCp.buffers_residual = cmd->use_sg - 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 = (char *)cmd->request_buffer;
            cmd->SCp.this_residual = cmd->request_bufflen;
      }
}

#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}
};

/*
 * Function : void NCR5380_print(struct Scsi_Host *instance)
 *
 * Purpose : print the SCSI bus signals for debugging purposes
 *
 * Input : instance - which NCR5380
 */

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"}
};

/*
 * Function : void NCR5380_print_phase(struct Scsi_Host *instance)
 *
 * Purpose : print the current SCSI phase for debugging purposes
 *
 * Input : instance - which NCR5380
 */

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);
      }
}

#else /* !NDEBUG */

/* dummies... */
static inline void NCR5380_print(struct Scsi_Host *instance)
{
};
static inline void NCR5380_print_phase(struct Scsi_Host *instance)
{
};

#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/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) {
            INI_PRINTK("scsi : NCR5380_all_init()\n");
            done = 1;
      }
}


/*
 * Function : void NCR58380_print_options (struct Scsi_Host *instance)
 *
 * Purpose : called by probe code indicating the NCR5380 driver
 *         options that were selected.
 *
 * Inputs : instance, pointer to this instance.  Unused.
 */

static void __init NCR5380_print_options(struct Scsi_Host *instance)
{
      printk(" generic options"
#ifdef AUTOSENSE
             " AUTOSENSE"
#endif
#ifdef REAL_DMA
             " REAL DMA"
#endif
#ifdef PARITY
             " PARITY"
#endif
#ifdef SUPPORT_TAGS
             " SCSI-2 TAGGED QUEUING"
#endif
             );
      printk(" generic release=%d", NCR5380_PUBLIC_RELEASE);
}

/*
 * Function : void NCR5380_print_status (struct Scsi_Host *instance)
 *
 * Purpose : print commands in the various queues, called from
 *    NCR5380_abort and NCR5380_debug to aid debugging.
 *
 * Inputs : instance, pointer to this instance.
 */

static void NCR5380_print_status(struct Scsi_Host *instance)
{
      char *pr_bfr;
      char *start;
      int len;

      NCR_PRINT(NDEBUG_ANY);
      NCR_PRINT_PHASE(NDEBUG_ANY);

      pr_bfr = (char *)__get_free_page(GFP_ATOMIC);
      if (!pr_bfr) {
            printk("NCR5380_print_status: no memory for print buffer\n");
            return;
      }
      len = NCR5380_proc_info(instance, pr_bfr, &start, 0, PAGE_SIZE, 0);
      pr_bfr[len] = 0;
      printk("\n%s\n", pr_bfr);
      free_page((unsigned long)pr_bfr);
}


/******************************************/
/*
 * /proc/scsi/[dtc pas16 t128 generic]/[0-ASC_NUM_BOARD_SUPPORTED]
 *
 * *buffer: I/O buffer
 * **start: if inout == FALSE pointer into buffer where user read should start
 * offset: current offset
 * length: length of buffer
 * hostno: Scsi_Host host_no
 * inout: TRUE - user is writing; FALSE - user is reading
 *
 * Return the number of bytes read from or written
*/

#undef SPRINTF
#define SPRINTF(fmt,args...)                                      \
      do {                                                  \
            if (pos + strlen(fmt) + 20 /* slop */ < buffer + length)    \
                  pos += sprintf(pos, fmt , ## args);             \
      } while(0)
static char *lprint_Scsi_Cmnd(Scsi_Cmnd *cmd, char *pos, char *buffer, int length);

static int NCR5380_proc_info(struct Scsi_Host *instance, char *buffer,
                       char **start, off_t offset, int length, int inout)
{
      char *pos = buffer;
      struct NCR5380_hostdata *hostdata;
      Scsi_Cmnd *ptr;
      unsigned long flags;
      off_t begin = 0;
#define check_offset()                          \
      do {                                \
            if (pos - buffer < offset - begin) {      \
                  begin += pos - buffer;        \
                  pos = buffer;                 \
            }                             \
      } while (0)

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

      if (inout)              /* Has data been written to the file ? */
            return -ENOSYS;         /* Currently this is a no-op */
      SPRINTF("NCR5380 core release=%d.\n", NCR5380_PUBLIC_RELEASE);
      check_offset();
      local_irq_save(flags);
      SPRINTF("NCR5380: coroutine is%s running.\n",
            main_running ? "" : "n't");
      check_offset();
      if (!hostdata->connected)
            SPRINTF("scsi%d: no currently connected command\n", HOSTNO);
      else
            pos = lprint_Scsi_Cmnd((Scsi_Cmnd *) hostdata->connected,
                               pos, buffer, length);
      SPRINTF("scsi%d: issue_queue\n", HOSTNO);
      check_offset();
      for (ptr = (Scsi_Cmnd *)hostdata->issue_queue; ptr; ptr = NEXT(ptr)) {
            pos = lprint_Scsi_Cmnd(ptr, pos, buffer, length);
            check_offset();
      }

      SPRINTF("scsi%d: disconnected_queue\n", HOSTNO);
      check_offset();
      for (ptr = (Scsi_Cmnd *) hostdata->disconnected_queue; ptr;
           ptr = NEXT(ptr)) {
            pos = lprint_Scsi_Cmnd(ptr, pos, buffer, length);
            check_offset();
      }

      local_irq_restore(flags);
      *start = buffer + (offset - begin);
      if (pos - buffer < offset - begin)
            return 0;
      else if (pos - buffer - (offset - begin) < length)
            return pos - buffer - (offset - begin);
      return length;
}

static char *lprint_Scsi_Cmnd(Scsi_Cmnd *cmd, char *pos, char *buffer, int length)
{
      int i, s;
      unsigned char *command;
      SPRINTF("scsi%d: destination target %d, lun %d\n",
            H_NO(cmd), cmd->device->id, cmd->device->lun);
      SPRINTF("        command = ");
      command = cmd->cmnd;
      SPRINTF("%2d (0x%02x)", command[0], command[0]);
      for (i = 1, s = COMMAND_SIZE(command[0]); i < s; ++i)
            SPRINTF(" %02x", command[i]);
      SPRINTF("\n");
      return pos;
}


/*
 * Function : void NCR5380_init (struct Scsi_Host *instance)
 *
 * Purpose : initializes *instance and corresponding 5380 chip.
 *
 * Inputs : instance - instantiation of the 5380 driver.
 *
 * Notes : I assume that the host, hostno, and id bits have been
 *    set correctly.  I don't care about the irq and other fields.
 *
 */

static int 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();
#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 = FLAG_CHECK_LAST_BYTE_SENT;

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

#ifndef AUTOSENSE
      if ((instance->cmd_per_lun > 1) || (instance->can_queue > 1))
            printk("scsi%d: WARNING : support for multiple outstanding commands enabled\n"
                   "        without AUTOSENSE option, contingent allegiance conditions may\n"
                   "        be incorrectly cleared.\n", HOSTNO);
#endif /* def AUTOSENSE */

      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;
}

/*
 * Function : int NCR5380_queue_command (Scsi_Cmnd *cmd,
 *    void (*done)(Scsi_Cmnd *))
 *
 * Purpose :  enqueues a SCSI command
 *
 * Inputs : cmd - SCSI command, done - function called on completion, with
 *    a pointer to the command descriptor.
 *
 * Returns : 0
 *
 * Side effects :
 *      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(Scsi_Cmnd *cmd, void (*done)(Scsi_Cmnd *))
{
      SETUP_HOSTDATA(cmd->device->host);
      Scsi_Cmnd *tmp;
      int oldto;
      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);
            done(cmd);
            return 0;
      }
#endif /* (NDEBUG & NDEBUG_NO_WRITE) */

#ifdef NCR5380_STATS
# if 0
      if (!hostdata->connected && !hostdata->issue_queue &&
          !hostdata->disconnected_queue) {
            hostdata->timebase = jiffies;
      }
# endif
# ifdef NCR5380_STAT_LIMIT
      if (cmd->request_bufflen > NCR5380_STAT_LIMIT)
# endif
            switch (cmd->cmnd[0]) {
            case WRITE:
            case WRITE_6:
            case WRITE_10:
                  hostdata->time_write[cmd->device->id] -= (jiffies - hostdata->timebase);
                  hostdata->bytes_write[cmd->device->id] += cmd->request_bufflen;
                  hostdata->pendingw++;
                  break;
            case READ:
            case READ_6:
            case READ_10:
                  hostdata->time_read[cmd->device->id] -= (jiffies - hostdata->timebase);
                  hostdata->bytes_read[cmd->device->id] += cmd->request_bufflen;
                  hostdata->pendingr++;
                  break;
            }
#endif

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

      SET_NEXT(cmd, NULL);
      cmd->scsi_done = done;

      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.
       */

      local_irq_save(flags);
      /* ++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 (!IS_A_TT()) {
            /* perhaps stop command timer here */
            falcon_get_lock();
            /* perhaps restart command timer here */
      }
      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 = (Scsi_Cmnd *)hostdata->issue_queue;
                 NEXT(tmp); tmp = NEXT(tmp))
                  ;
            LIST(cmd, tmp);
            SET_NEXT(tmp, cmd);
      }
      local_irq_restore(flags);

      QU_PRINTK("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() || ((flags >> 8) & 7) >= 6)
            queue_main();
      else
            NCR5380_main(NULL);
      return 0;
}

/*
 * Function : NCR5380_main (void)
 *
 * Purpose : 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.
 *
 * NOTE : NCR5380_main exits with interrupts *disabled*, the caller should
 *  reenable them.  This prevents reentrancy and kernel stack overflow.
 */

static void NCR5380_main(struct work_struct *work)
{
      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) {
                  MAIN_PRINTK("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 = (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 = (Scsi_Cmnd *) hostdata->issue_queue,
                       prev = NULL; tmp; prev = tmp, tmp = NEXT(tmp)) {

#if (NDEBUG & NDEBUG_LISTS)
                        if (prev != tmp)
                              printk("MAIN tmp=%p   target=%d   busy=%d lun=%d\n",
                                     tmp, tmp->device->id, hostdata->busy[tmp->device->id],
                                     tmp->device->lun);
#endif
                        /*  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 << tmp->device->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);
                              falcon_dont_release++;

                              /* 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.
                               */
                              MAIN_PRINTK("scsi%d: main(): command for target %d "
                                        "lun %d removed from issue_queue\n",
                                        HOSTNO, tmp->device->id, tmp->device->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,
                                  (tmp->cmnd[0] == REQUEST_SENSE) ? TAG_NONE :
                                  TAG_NEXT)) {
                                    falcon_dont_release--;
                                    /* release if target did not response! */
                                    falcon_release_lock_if_possible(hostdata);
                                    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
                                    falcon_dont_release--;
                                    local_irq_restore(flags);
                                    MAIN_PRINTK("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);
                  MAIN_PRINTK("scsi%d: main: performing information transfer\n",
                            HOSTNO);
                  NCR5380_information_transfer(instance);
                  MAIN_PRINTK("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, saved_data = 0, overrun = 0, cnt, toPIO;
      unsigned char **data, p;
      volatile int *count;

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

      if (atari_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;
                        DMA_PRINTK("scsi%d: read overrun handled\n", HOSTNO);
                  }
            }
      }

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

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


/*
 * Function : void NCR5380_intr (int irq)
 *
 * Purpose : handle interrupts, reestablishing I_T_L or I_T_L_Q nexuses
 *    from the disconnected queue, and restarting NCR5380_main()
 *    as required.
 *
 * Inputs : int irq, irq that caused this interrupt.
 *
 */

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

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

      /* Look for pending interrupts */
      basr = NCR5380_read(BUS_AND_STATUS_REG);
      INT_PRINTK("scsi%d: BASR=%02x\n", HOSTNO, basr);
      /* dispatch to appropriate routine if found and done=0 */
      if (basr & BASR_IRQ) {
            NCR_PRINT(NDEBUG_INTR);
            if ((NCR5380_read(STATUS_REG) & (SR_SEL|SR_IO)) == (SR_SEL|SR_IO)) {
                  done = 0;
                  ENABLE_IRQ();
                  INT_PRINTK("scsi%d: SEL interrupt\n", HOSTNO);
                  NCR5380_reselect(instance);
                  (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
            } else if (basr & BASR_PARITY_ERROR) {
                  INT_PRINTK("scsi%d: PARITY interrupt\n", HOSTNO);
                  (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
            } else if ((NCR5380_read(STATUS_REG) & SR_RST) == SR_RST) {
                  INT_PRINTK("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))) {

                        INT_PRINTK("scsi%d: PHASE MISM or EOP interrupt\n", HOSTNO);
                        NCR5380_dma_complete( instance );
                        done = 0;
                        ENABLE_IRQ();
                  } else
#endif /* REAL_DMA */
                  {
/* MS: Ignore unknown phase mismatch interrupts (caused by EOP interrupt) */
                        if (basr & BASR_PHASE_MATCH)
                              printk(KERN_NOTICE "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);
                  }
            } /* 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);
      }

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

#ifdef NCR5380_STATS
static void collect_stats(struct NCR5380_hostdata* hostdata, Scsi_Cmnd *cmd)
{
# ifdef NCR5380_STAT_LIMIT
      if (cmd->request_bufflen > NCR5380_STAT_LIMIT)
# endif
            switch (cmd->cmnd[0]) {
            case WRITE:
            case WRITE_6:
            case WRITE_10:
                  hostdata->time_write[cmd->device->id] += (jiffies - hostdata->timebase);
                  /*hostdata->bytes_write[cmd->device->id] += cmd->request_bufflen;*/
                  hostdata->pendingw--;
                  break;
            case READ:
            case READ_6:
            case READ_10:
                  hostdata->time_read[cmd->device->id] += (jiffies - hostdata->timebase);
                  /*hostdata->bytes_read[cmd->device->id] += cmd->request_bufflen;*/
                  hostdata->pendingr--;
                  break;
            }
}
#endif

/*
 * Function : int NCR5380_select (struct Scsi_Host *instance, Scsi_Cmnd *cmd,
 *    int tag);
 *
 * 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, tag - set to TAG_NEXT for
 *    new tag, TAG_NONE for untagged queueing, otherwise set to the tag for
 *    the command that is presently connected.
 *
 * 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, Scsi_Cmnd *cmd, int tag)
{
      SETUP_HOSTDATA(instance);
      unsigned char tmp[3], phase;
      unsigned char *data;
      int len;
      unsigned long timeout;
      unsigned long flags;

      hostdata->restart_select = 0;
      NCR_PRINT(NDEBUG_ARBITRATION);
      ARB_PRINTK("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

      ARB_PRINTK("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);
            ARB_PRINTK("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);
            ARB_PRINTK("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;
      }

      ARB_PRINTK("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);

      SEL_PRINTK("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 + 25;

      /*
       * 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 Kl├╝gere 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");
                  NCR_PRINT(NDEBUG_ANY);
                  NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                  return -1;
            }
            cmd->result = DID_BAD_TARGET << 16;
#ifdef NCR5380_STATS
            collect_stats(hostdata, cmd);
#endif
#ifdef SUPPORT_TAGS
            cmd_free_tag(cmd);
#endif
            cmd->scsi_done(cmd);
            NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
            SEL_PRINTK("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))
            ;

      SEL_PRINTK("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);
      SEL_PRINTK("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

      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 transfered 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))
                  ;

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

            /* Check for phase mismatch */
            if ((tmp & PHASE_MASK) != p) {
                  PIO_PRINTK("scsi%d: phase mismatch\n", HOSTNO);
                  NCR_PRINT_PHASE(NDEBUG_PIO);
                  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);
                        NCR_PRINT(NDEBUG_PIO);
                        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);
                        NCR_PRINT(NDEBUG_PIO);
                        NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE |
                                    ICR_ASSERT_DATA | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
                  }
            } else {
                  NCR_PRINT(NDEBUG_PIO);
                  NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ACK);
            }

            while (NCR5380_read(STATUS_REG) & SR_REQ)
                  ;

            HSH_PRINTK("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);

      PIO_PRINTK("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 transfered 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;
      register unsigned char *d = *data;
      unsigned char tmp;
      unsigned long flags;

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

      if (atari_read_overruns && (p & SR_IO))
            c -= atari_read_overruns;

      DMA_PRINTK("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 (IS_A_TT()) {
            /* 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 (!IS_A_TT()) {
            /* 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);
      }
      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;
      Scsi_Cmnd *cmd = (Scsi_Cmnd *) hostdata->connected;

      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;
                        NCR_PRINT_PHASE(NDEBUG_INFORMATION);
                  }

                  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);
                              INF_PRINTK("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 (!cmd->device->borken &&
                            (transfersize = NCR5380_dma_xfer_len(instance,cmd,phase)) > 31) {
                              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. */
                                    printk(KERN_NOTICE "scsi%d: switching target %d "
                                             "lun %d to slow handshake\n", HOSTNO,
                                             cmd->device->id, cmd->device->lun);
                                    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);
                        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);

                              LNK_PRINTK("scsi%d: target %d lun %d 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 %d "
                                          "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);
                              LNK_PRINTK("scsi%d: target %d lun %d linked request "
                                       "done, calling scsi_done().\n",
                                       HOSTNO, cmd->device->id, cmd->device->lun);
#ifdef NCR5380_STATS
                              collect_stats(hostdata, cmd);
#endif
                              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);
                              /* ++guenther: possible race with Falcon locking */
                              falcon_dont_release++;
                              hostdata->connected = NULL;
                              QU_PRINTK("scsi%d: command for target %d, lun %d "
                                      "completed\n", HOSTNO, cmd->device->id, cmd->device->lun);
#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];
                                    TAG_PRINTK("scsi%d: target %d lun %d 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);

#ifdef AUTOSENSE
                              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);

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

                                    local_irq_save(flags);
                                    LIST(cmd,hostdata->issue_queue);
                                    SET_NEXT(cmd, hostdata->issue_queue);
                                    hostdata->issue_queue = (Scsi_Cmnd *) cmd;
                                    local_irq_restore(flags);
                                    QU_PRINTK("scsi%d: REQUEST SENSE added to head of "
                                            "issue queue\n", H_NO(cmd));
                              } else
#endif /* def AUTOSENSE */
                              {
#ifdef NCR5380_STATS
                                    collect_stats(hostdata, cmd);
#endif
                                    cmd->scsi_done(cmd);
                              }

                              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();

                              falcon_dont_release--;
                              /* ++roman: For Falcon SCSI, release the lock on the
                               * ST-DMA here if no other commands are waiting on the
                               * disconnected queue.
                               */
                              falcon_release_lock_if_possible(hostdata);
                              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;
                                    TAG_PRINTK("scsi%d: target %d lun %d 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);
                              QU_PRINTK("scsi%d: command for target %d lun %d 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();
                              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);

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

                              len = 2;
                              data = extended_msg + 1;
                              phase = PHASE_MSGIN;
                              NCR5380_transfer_pio(instance, &phase, &len, &data);
                              EXT_PRINTK("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);
                                    EXT_PRINTK("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_DEBUG "scsi%d: rejecting message ", HOSTNO);
                                    spi_print_msg(extended_msg);
                                    printk("\n");
                              } else if (tmp != EXTENDED_MESSAGE)
                                    printk(KERN_DEBUG "scsi%d: rejecting unknown "
                                           "message %02x from target %d, lun %d\n",
                                           HOSTNO, tmp, cmd->device->id, cmd->device->lun);
                              else
                                    printk(KERN_DEBUG "scsi%d: rejecting unknown "
                                           "extended message "
                                           "code %02x, length %d from target %d, lun %d\n",
                                           HOSTNO, extended_msg[1], extended_msg[0],
                                           cmd->device->id, cmd->device->lun);


                              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) {
#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;
#ifdef NCR5380_STATS
                              collect_stats(hostdata, cmd);
#endif
                              cmd->scsi_done(cmd);
                              NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
                              falcon_release_lock_if_possible(hostdata);
                              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);
                        NCR_PRINT(NDEBUG_ANY);
                  } /* 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.
 *
 */


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

      /*
       * 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);

      RSL_PRINTK("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))
            ;

      len = 1;
      data = msg;
      phase = PHASE_MSGIN;
      NCR5380_transfer_pio(instance, &phase, &len, &data);

      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);

#ifdef SUPPORT_TAGS
      /* 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];
            TAG_PRINTK("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 = (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
                ) {
                  /* ++guenther: prevent race with falcon_release_lock */
                  falcon_dont_release++;
                  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;
      }

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

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


/*
 * Function : int NCR5380_abort (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 : 0 - success, -1 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(Scsi_Cmnd *cmd)
{
      struct Scsi_Host *instance = cmd->device->host;
      SETUP_HOSTDATA(instance);
      Scsi_Cmnd *tmp, **prev;
      unsigned long flags;

      printk(KERN_NOTICE "scsi%d: aborting command\n", HOSTNO);
      scsi_print_command(cmd);

      NCR5380_print_status(instance);

      local_irq_save(flags);

      if (!IS_A_TT() && !falcon_got_lock)
            printk(KERN_ERR "scsi%d: !!BINGO!! Falcon has no lock in NCR5380_abort\n",
                   HOSTNO);

      ABRT_PRINTK("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) {

            ABRT_PRINTK("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
                  local_irq_restore(flags);
                  cmd->scsi_done(cmd);
                  falcon_release_lock_if_possible(hostdata);
                  return SCSI_ABORT_SUCCESS;
            } else {
/*                local_irq_restore(flags); */
                  printk("scsi%d: abort of connected command failed!\n", HOSTNO);
                  return SCSI_ABORT_ERROR;
            }
      }
#endif

      /*
       * Case 2 : If the command hasn't been issued yet, we simply remove it
       *        from the issue queue.
       */
      for (prev = (Scsi_Cmnd **)&(hostdata->issue_queue),
           tmp = (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;
                  local_irq_restore(flags);
                  ABRT_PRINTK("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);
                  falcon_release_lock_if_possible(hostdata);
                  return SCSI_ABORT_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);
            ABRT_PRINTK("scsi%d: abort failed, command connected.\n", HOSTNO);
            return SCSI_ABORT_SNOOZE;
      }

      /*
       * 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 = (Scsi_Cmnd *) hostdata->disconnected_queue; tmp;
           tmp = NEXT(tmp)) {
            if (cmd == tmp) {
                  local_irq_restore(flags);
                  ABRT_PRINTK("scsi%d: aborting disconnected command.\n", HOSTNO);

                  if (NCR5380_select(instance, cmd, (int)cmd->tag))
                        return SCSI_ABORT_BUSY;

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

                  do_abort(instance);

                  local_irq_save(flags);
                  for (prev = (Scsi_Cmnd **)&(hostdata->disconnected_queue),
                       tmp = (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
                              local_irq_restore(flags);
                              tmp->scsi_done(tmp);
                              falcon_release_lock_if_possible(hostdata);
                              return SCSI_ABORT_SUCCESS;
                        }
                  }
            }
      }

      /*
       * 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.
       */

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

      /* 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.
       */
      falcon_release_lock_if_possible(hostdata);

      return SCSI_ABORT_NOT_RUNNING;
}


/*
 * Function : int NCR5380_reset (Scsi_Cmnd *cmd)
 *
 * Purpose : reset the SCSI bus.
 *
 * Returns : SCSI_RESET_WAKEUP
 *
 */

static int NCR5380_bus_reset(Scsi_Cmnd *cmd)
{
      SETUP_HOSTDATA(cmd->device->host);
      int i;
      unsigned long flags;
#if 1
      Scsi_Cmnd *connected, *disconnected_queue;
#endif

      if (!IS_A_TT() && !falcon_got_lock)
            printk(KERN_ERR "scsi%d: !!BINGO!! Falcon has no lock in NCR5380_reset\n",
                   H_NO(cmd));

      NCR5380_print_status(cmd->device->host);

      /* 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);

#if 1 /* 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 = (Scsi_Cmnd *)hostdata->connected;
      hostdata->connected = NULL;
      disconnected_queue = (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)) {
            ABRT_PRINTK("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)
            ABRT_PRINTK("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 SCSI_RESET_SUCCESS | SCSI_RESET_BUS_RESET;
#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)
            ABRT_PRINTK("scsi%d: reset aborted issued command(s)\n", H_NO(cmd));
      if (hostdata->connected)
            ABRT_PRINTK("scsi%d: reset aborted a connected command\n", H_NO(cmd));
      if (hostdata->disconnected_queue)
            ABRT_PRINTK("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();
#endif
      for (i = 0; i < 8; ++i)
            hostdata->busy[i] = 0;
#ifdef REAL_DMA
      hostdata->dma_len = 0;
#endif
      local_irq_restore(flags);

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

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