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esp_scsi.c

/* esp_scsi.c: ESP SCSI driver.
 *
 * Copyright (C) 2007 David S. Miller (davem@davemloft.net)
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/list.h>
#include <linux/completion.h>
#include <linux/kallsyms.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/irqreturn.h>

#include <asm/irq.h>
#include <asm/io.h>
#include <asm/dma.h>

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

#include "esp_scsi.h"

#define DRV_MODULE_NAME       "esp"
#define PFX DRV_MODULE_NAME   ": "
#define DRV_VERSION           "2.000"
#define DRV_MODULE_RELDATE    "April 19, 2007"

/* SCSI bus reset settle time in seconds.  */
static int esp_bus_reset_settle = 3;

static u32 esp_debug;
#define ESP_DEBUG_INTR        0x00000001
#define ESP_DEBUG_SCSICMD     0x00000002
#define ESP_DEBUG_RESET       0x00000004
#define ESP_DEBUG_MSGIN       0x00000008
#define ESP_DEBUG_MSGOUT      0x00000010
#define ESP_DEBUG_CMDDONE     0x00000020
#define ESP_DEBUG_DISCONNECT  0x00000040
#define ESP_DEBUG_DATASTART   0x00000080
#define ESP_DEBUG_DATADONE    0x00000100
#define ESP_DEBUG_RECONNECT   0x00000200
#define ESP_DEBUG_AUTOSENSE   0x00000400

#define esp_log_intr(f, a...) \
do {  if (esp_debug & ESP_DEBUG_INTR) \
            printk(f, ## a); \
} while (0)

#define esp_log_reset(f, a...) \
do {  if (esp_debug & ESP_DEBUG_RESET) \
            printk(f, ## a); \
} while (0)

#define esp_log_msgin(f, a...) \
do {  if (esp_debug & ESP_DEBUG_MSGIN) \
            printk(f, ## a); \
} while (0)

#define esp_log_msgout(f, a...) \
do {  if (esp_debug & ESP_DEBUG_MSGOUT) \
            printk(f, ## a); \
} while (0)

#define esp_log_cmddone(f, a...) \
do {  if (esp_debug & ESP_DEBUG_CMDDONE) \
            printk(f, ## a); \
} while (0)

#define esp_log_disconnect(f, a...) \
do {  if (esp_debug & ESP_DEBUG_DISCONNECT) \
            printk(f, ## a); \
} while (0)

#define esp_log_datastart(f, a...) \
do {  if (esp_debug & ESP_DEBUG_DATASTART) \
            printk(f, ## a); \
} while (0)

#define esp_log_datadone(f, a...) \
do {  if (esp_debug & ESP_DEBUG_DATADONE) \
            printk(f, ## a); \
} while (0)

#define esp_log_reconnect(f, a...) \
do {  if (esp_debug & ESP_DEBUG_RECONNECT) \
            printk(f, ## a); \
} while (0)

#define esp_log_autosense(f, a...) \
do {  if (esp_debug & ESP_DEBUG_AUTOSENSE) \
            printk(f, ## a); \
} while (0)

#define esp_read8(REG)        esp->ops->esp_read8(esp, REG)
#define esp_write8(VAL,REG)   esp->ops->esp_write8(esp, VAL, REG)

static void esp_log_fill_regs(struct esp *esp,
                        struct esp_event_ent *p)
{
      p->sreg = esp->sreg;
      p->seqreg = esp->seqreg;
      p->sreg2 = esp->sreg2;
      p->ireg = esp->ireg;
      p->select_state = esp->select_state;
      p->event = esp->event;
}

void scsi_esp_cmd(struct esp *esp, u8 val)
{
      struct esp_event_ent *p;
      int idx = esp->esp_event_cur;

      p = &esp->esp_event_log[idx];
      p->type = ESP_EVENT_TYPE_CMD;
      p->val = val;
      esp_log_fill_regs(esp, p);

      esp->esp_event_cur = (idx + 1) & (ESP_EVENT_LOG_SZ - 1);

      esp_write8(val, ESP_CMD);
}
EXPORT_SYMBOL(scsi_esp_cmd);

static void esp_event(struct esp *esp, u8 val)
{
      struct esp_event_ent *p;
      int idx = esp->esp_event_cur;

      p = &esp->esp_event_log[idx];
      p->type = ESP_EVENT_TYPE_EVENT;
      p->val = val;
      esp_log_fill_regs(esp, p);

      esp->esp_event_cur = (idx + 1) & (ESP_EVENT_LOG_SZ - 1);

      esp->event = val;
}

static void esp_dump_cmd_log(struct esp *esp)
{
      int idx = esp->esp_event_cur;
      int stop = idx;

      printk(KERN_INFO PFX "esp%d: Dumping command log\n",
             esp->host->unique_id);
      do {
            struct esp_event_ent *p = &esp->esp_event_log[idx];

            printk(KERN_INFO PFX "esp%d: ent[%d] %s ",
                   esp->host->unique_id, idx,
                   p->type == ESP_EVENT_TYPE_CMD ? "CMD" : "EVENT");

            printk("val[%02x] sreg[%02x] seqreg[%02x] "
                   "sreg2[%02x] ireg[%02x] ss[%02x] event[%02x]\n",
                   p->val, p->sreg, p->seqreg,
                   p->sreg2, p->ireg, p->select_state, p->event);

            idx = (idx + 1) & (ESP_EVENT_LOG_SZ - 1);
      } while (idx != stop);
}

static void esp_flush_fifo(struct esp *esp)
{
      scsi_esp_cmd(esp, ESP_CMD_FLUSH);
      if (esp->rev == ESP236) {
            int lim = 1000;

            while (esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES) {
                  if (--lim == 0) {
                        printk(KERN_ALERT PFX "esp%d: ESP_FF_BYTES "
                               "will not clear!\n",
                               esp->host->unique_id);
                        break;
                  }
                  udelay(1);
            }
      }
}

static void hme_read_fifo(struct esp *esp)
{
      int fcnt = esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES;
      int idx = 0;

      while (fcnt--) {
            esp->fifo[idx++] = esp_read8(ESP_FDATA);
            esp->fifo[idx++] = esp_read8(ESP_FDATA);
      }
      if (esp->sreg2 & ESP_STAT2_F1BYTE) {
            esp_write8(0, ESP_FDATA);
            esp->fifo[idx++] = esp_read8(ESP_FDATA);
            scsi_esp_cmd(esp, ESP_CMD_FLUSH);
      }
      esp->fifo_cnt = idx;
}

static void esp_set_all_config3(struct esp *esp, u8 val)
{
      int i;

      for (i = 0; i < ESP_MAX_TARGET; i++)
            esp->target[i].esp_config3 = val;
}

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

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

      /* Reload the configuration registers */
      esp_write8(esp->cfact, ESP_CFACT);

      esp->prev_stp = 0;
      esp_write8(esp->prev_stp, ESP_STP);

      esp->prev_soff = 0;
      esp_write8(esp->prev_soff, ESP_SOFF);

      esp_write8(esp->neg_defp, ESP_TIMEO);

      /* This is the only point at which it is reliable to read
       * the ID-code for a fast ESP chip variants.
       */
      esp->max_period = ((35 * esp->ccycle) / 1000);
      if (esp->rev == FAST) {
            version = esp_read8(ESP_UID);
            family_code = (version & 0xf8) >> 3;
            if (family_code == 0x02)
                  esp->rev = FAS236;
            else if (family_code == 0x0a)
                  esp->rev = FASHME; /* Version is usually '5'. */
            else
                  esp->rev = FAS100A;
            esp->min_period = ((4 * esp->ccycle) / 1000);
      } else {
            esp->min_period = ((5 * esp->ccycle) / 1000);
      }
      esp->max_period = (esp->max_period + 3)>>2;
      esp->min_period = (esp->min_period + 3)>>2;

      esp_write8(esp->config1, ESP_CFG1);
      switch (esp->rev) {
      case ESP100:
            /* nothing to do */
            break;

      case ESP100A:
            esp_write8(esp->config2, ESP_CFG2);
            break;

      case ESP236:
            /* Slow 236 */
            esp_write8(esp->config2, ESP_CFG2);
            esp->prev_cfg3 = esp->target[0].esp_config3;
            esp_write8(esp->prev_cfg3, ESP_CFG3);
            break;

      case FASHME:
            esp->config2 |= (ESP_CONFIG2_HME32 | ESP_CONFIG2_HMEFENAB);
            /* fallthrough... */

      case FAS236:
            /* Fast 236 or HME */
            esp_write8(esp->config2, ESP_CFG2);
            if (esp->rev == FASHME) {
                  u8 cfg3 = esp->target[0].esp_config3;

                  cfg3 |= ESP_CONFIG3_FCLOCK | ESP_CONFIG3_OBPUSH;
                  if (esp->scsi_id >= 8)
                        cfg3 |= ESP_CONFIG3_IDBIT3;
                  esp_set_all_config3(esp, cfg3);
            } else {
                  u32 cfg3 = esp->target[0].esp_config3;

                  cfg3 |= ESP_CONFIG3_FCLK;
                  esp_set_all_config3(esp, cfg3);
            }
            esp->prev_cfg3 = esp->target[0].esp_config3;
            esp_write8(esp->prev_cfg3, ESP_CFG3);
            if (esp->rev == FASHME) {
                  esp->radelay = 80;
            } else {
                  if (esp->flags & ESP_FLAG_DIFFERENTIAL)
                        esp->radelay = 0;
                  else
                        esp->radelay = 96;
            }
            break;

      case FAS100A:
            /* Fast 100a */
            esp_write8(esp->config2, ESP_CFG2);
            esp_set_all_config3(esp,
                            (esp->target[0].esp_config3 |
                             ESP_CONFIG3_FCLOCK));
            esp->prev_cfg3 = esp->target[0].esp_config3;
            esp_write8(esp->prev_cfg3, ESP_CFG3);
            esp->radelay = 32;
            break;

      default:
            break;
      }

      /* Eat any bitrot in the chip */
      esp_read8(ESP_INTRPT);
      udelay(100);
}

static void esp_map_dma(struct esp *esp, struct scsi_cmnd *cmd)
{
      struct esp_cmd_priv *spriv = ESP_CMD_PRIV(cmd);
      struct scatterlist *sg = scsi_sglist(cmd);
      int dir = cmd->sc_data_direction;
      int total, i;

      if (dir == DMA_NONE)
            return;

      spriv->u.num_sg = esp->ops->map_sg(esp, sg, scsi_sg_count(cmd), dir);
      spriv->cur_residue = sg_dma_len(sg);
      spriv->cur_sg = sg;

      total = 0;
      for (i = 0; i < spriv->u.num_sg; i++)
            total += sg_dma_len(&sg[i]);
      spriv->tot_residue = total;
}

static dma_addr_t esp_cur_dma_addr(struct esp_cmd_entry *ent,
                           struct scsi_cmnd *cmd)
{
      struct esp_cmd_priv *p = ESP_CMD_PRIV(cmd);

      if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
            return ent->sense_dma +
                  (ent->sense_ptr - cmd->sense_buffer);
      }

      return sg_dma_address(p->cur_sg) +
            (sg_dma_len(p->cur_sg) -
             p->cur_residue);
}

static unsigned int esp_cur_dma_len(struct esp_cmd_entry *ent,
                            struct scsi_cmnd *cmd)
{
      struct esp_cmd_priv *p = ESP_CMD_PRIV(cmd);

      if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
            return SCSI_SENSE_BUFFERSIZE -
                  (ent->sense_ptr - cmd->sense_buffer);
      }
      return p->cur_residue;
}

static void esp_advance_dma(struct esp *esp, struct esp_cmd_entry *ent,
                      struct scsi_cmnd *cmd, unsigned int len)
{
      struct esp_cmd_priv *p = ESP_CMD_PRIV(cmd);

      if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
            ent->sense_ptr += len;
            return;
      }

      p->cur_residue -= len;
      p->tot_residue -= len;
      if (p->cur_residue < 0 || p->tot_residue < 0) {
            printk(KERN_ERR PFX "esp%d: Data transfer overflow.\n",
                   esp->host->unique_id);
            printk(KERN_ERR PFX "esp%d: cur_residue[%d] tot_residue[%d] "
                   "len[%u]\n",
                   esp->host->unique_id,
                   p->cur_residue, p->tot_residue, len);
            p->cur_residue = 0;
            p->tot_residue = 0;
      }
      if (!p->cur_residue && p->tot_residue) {
            p->cur_sg++;
            p->cur_residue = sg_dma_len(p->cur_sg);
      }
}

static void esp_unmap_dma(struct esp *esp, struct scsi_cmnd *cmd)
{
      struct esp_cmd_priv *spriv = ESP_CMD_PRIV(cmd);
      int dir = cmd->sc_data_direction;

      if (dir == DMA_NONE)
            return;

      esp->ops->unmap_sg(esp, scsi_sglist(cmd), spriv->u.num_sg, dir);
}

static void esp_save_pointers(struct esp *esp, struct esp_cmd_entry *ent)
{
      struct scsi_cmnd *cmd = ent->cmd;
      struct esp_cmd_priv *spriv = ESP_CMD_PRIV(cmd);

      if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
            ent->saved_sense_ptr = ent->sense_ptr;
            return;
      }
      ent->saved_cur_residue = spriv->cur_residue;
      ent->saved_cur_sg = spriv->cur_sg;
      ent->saved_tot_residue = spriv->tot_residue;
}

static void esp_restore_pointers(struct esp *esp, struct esp_cmd_entry *ent)
{
      struct scsi_cmnd *cmd = ent->cmd;
      struct esp_cmd_priv *spriv = ESP_CMD_PRIV(cmd);

      if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
            ent->sense_ptr = ent->saved_sense_ptr;
            return;
      }
      spriv->cur_residue = ent->saved_cur_residue;
      spriv->cur_sg = ent->saved_cur_sg;
      spriv->tot_residue = ent->saved_tot_residue;
}

static void esp_check_command_len(struct esp *esp, struct scsi_cmnd *cmd)
{
      if (cmd->cmd_len == 6 ||
          cmd->cmd_len == 10 ||
          cmd->cmd_len == 12) {
            esp->flags &= ~ESP_FLAG_DOING_SLOWCMD;
      } else {
            esp->flags |= ESP_FLAG_DOING_SLOWCMD;
      }
}

static void esp_write_tgt_config3(struct esp *esp, int tgt)
{
      if (esp->rev > ESP100A) {
            u8 val = esp->target[tgt].esp_config3;

            if (val != esp->prev_cfg3) {
                  esp->prev_cfg3 = val;
                  esp_write8(val, ESP_CFG3);
            }
      }
}

static void esp_write_tgt_sync(struct esp *esp, int tgt)
{
      u8 off = esp->target[tgt].esp_offset;
      u8 per = esp->target[tgt].esp_period;

      if (off != esp->prev_soff) {
            esp->prev_soff = off;
            esp_write8(off, ESP_SOFF);
      }
      if (per != esp->prev_stp) {
            esp->prev_stp = per;
            esp_write8(per, ESP_STP);
      }
}

static u32 esp_dma_length_limit(struct esp *esp, u32 dma_addr, u32 dma_len)
{
      if (esp->rev == FASHME) {
            /* Arbitrary segment boundaries, 24-bit counts.  */
            if (dma_len > (1U << 24))
                  dma_len = (1U << 24);
      } else {
            u32 base, end;

            /* ESP chip limits other variants by 16-bits of transfer
             * count.  Actually on FAS100A and FAS236 we could get
             * 24-bits of transfer count by enabling ESP_CONFIG2_FENAB
             * in the ESP_CFG2 register but that causes other unwanted
             * changes so we don't use it currently.
             */
            if (dma_len > (1U << 16))
                  dma_len = (1U << 16);

            /* All of the DMA variants hooked up to these chips
             * cannot handle crossing a 24-bit address boundary.
             */
            base = dma_addr & ((1U << 24) - 1U);
            end = base + dma_len;
            if (end > (1U << 24))
                  end = (1U <<24);
            dma_len = end - base;
      }
      return dma_len;
}

static int esp_need_to_nego_wide(struct esp_target_data *tp)
{
      struct scsi_target *target = tp->starget;

      return spi_width(target) != tp->nego_goal_width;
}

static int esp_need_to_nego_sync(struct esp_target_data *tp)
{
      struct scsi_target *target = tp->starget;

      /* When offset is zero, period is "don't care".  */
      if (!spi_offset(target) && !tp->nego_goal_offset)
            return 0;

      if (spi_offset(target) == tp->nego_goal_offset &&
          spi_period(target) == tp->nego_goal_period)
            return 0;

      return 1;
}

static int esp_alloc_lun_tag(struct esp_cmd_entry *ent,
                       struct esp_lun_data *lp)
{
      if (!ent->tag[0]) {
            /* Non-tagged, slot already taken?  */
            if (lp->non_tagged_cmd)
                  return -EBUSY;

            if (lp->hold) {
                  /* We are being held by active tagged
                   * commands.
                   */
                  if (lp->num_tagged)
                        return -EBUSY;

                  /* Tagged commands completed, we can unplug
                   * the queue and run this untagged command.
                   */
                  lp->hold = 0;
            } else if (lp->num_tagged) {
                  /* Plug the queue until num_tagged decreases
                   * to zero in esp_free_lun_tag.
                   */
                  lp->hold = 1;
                  return -EBUSY;
            }

            lp->non_tagged_cmd = ent;
            return 0;
      } else {
            /* Tagged command, see if blocked by a
             * non-tagged one.
             */
            if (lp->non_tagged_cmd || lp->hold)
                  return -EBUSY;
      }

      BUG_ON(lp->tagged_cmds[ent->tag[1]]);

      lp->tagged_cmds[ent->tag[1]] = ent;
      lp->num_tagged++;

      return 0;
}

static void esp_free_lun_tag(struct esp_cmd_entry *ent,
                       struct esp_lun_data *lp)
{
      if (ent->tag[0]) {
            BUG_ON(lp->tagged_cmds[ent->tag[1]] != ent);
            lp->tagged_cmds[ent->tag[1]] = NULL;
            lp->num_tagged--;
      } else {
            BUG_ON(lp->non_tagged_cmd != ent);
            lp->non_tagged_cmd = NULL;
      }
}

/* When a contingent allegiance conditon is created, we force feed a
 * REQUEST_SENSE command to the device to fetch the sense data.  I
 * tried many other schemes, relying on the scsi error handling layer
 * to send out the REQUEST_SENSE automatically, but this was difficult
 * to get right especially in the presence of applications like smartd
 * which use SG_IO to send out their own REQUEST_SENSE commands.
 */
static void esp_autosense(struct esp *esp, struct esp_cmd_entry *ent)
{
      struct scsi_cmnd *cmd = ent->cmd;
      struct scsi_device *dev = cmd->device;
      int tgt, lun;
      u8 *p, val;

      tgt = dev->id;
      lun = dev->lun;


      if (!ent->sense_ptr) {
            esp_log_autosense("esp%d: Doing auto-sense for "
                          "tgt[%d] lun[%d]\n",
                          esp->host->unique_id, tgt, lun);

            ent->sense_ptr = cmd->sense_buffer;
            ent->sense_dma = esp->ops->map_single(esp,
                                          ent->sense_ptr,
                                          SCSI_SENSE_BUFFERSIZE,
                                          DMA_FROM_DEVICE);
      }
      ent->saved_sense_ptr = ent->sense_ptr;

      esp->active_cmd = ent;

      p = esp->command_block;
      esp->msg_out_len = 0;

      *p++ = IDENTIFY(0, lun);
      *p++ = REQUEST_SENSE;
      *p++ = ((dev->scsi_level <= SCSI_2) ?
            (lun << 5) : 0);
      *p++ = 0;
      *p++ = 0;
      *p++ = SCSI_SENSE_BUFFERSIZE;
      *p++ = 0;

      esp->select_state = ESP_SELECT_BASIC;

      val = tgt;
      if (esp->rev == FASHME)
            val |= ESP_BUSID_RESELID | ESP_BUSID_CTR32BIT;
      esp_write8(val, ESP_BUSID);

      esp_write_tgt_sync(esp, tgt);
      esp_write_tgt_config3(esp, tgt);

      val = (p - esp->command_block);

      if (esp->rev == FASHME)
            scsi_esp_cmd(esp, ESP_CMD_FLUSH);
      esp->ops->send_dma_cmd(esp, esp->command_block_dma,
                         val, 16, 0, ESP_CMD_DMA | ESP_CMD_SELA);
}

static struct esp_cmd_entry *find_and_prep_issuable_command(struct esp *esp)
{
      struct esp_cmd_entry *ent;

      list_for_each_entry(ent, &esp->queued_cmds, list) {
            struct scsi_cmnd *cmd = ent->cmd;
            struct scsi_device *dev = cmd->device;
            struct esp_lun_data *lp = dev->hostdata;

            if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
                  ent->tag[0] = 0;
                  ent->tag[1] = 0;
                  return ent;
            }

            if (!scsi_populate_tag_msg(cmd, &ent->tag[0])) {
                  ent->tag[0] = 0;
                  ent->tag[1] = 0;
            }

            if (esp_alloc_lun_tag(ent, lp) < 0)
                  continue;

            return ent;
      }

      return NULL;
}

static void esp_maybe_execute_command(struct esp *esp)
{
      struct esp_target_data *tp;
      struct esp_lun_data *lp;
      struct scsi_device *dev;
      struct scsi_cmnd *cmd;
      struct esp_cmd_entry *ent;
      int tgt, lun, i;
      u32 val, start_cmd;
      u8 *p;

      if (esp->active_cmd ||
          (esp->flags & ESP_FLAG_RESETTING))
            return;

      ent = find_and_prep_issuable_command(esp);
      if (!ent)
            return;

      if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
            esp_autosense(esp, ent);
            return;
      }

      cmd = ent->cmd;
      dev = cmd->device;
      tgt = dev->id;
      lun = dev->lun;
      tp = &esp->target[tgt];
      lp = dev->hostdata;

      list_del(&ent->list);
      list_add(&ent->list, &esp->active_cmds);

      esp->active_cmd = ent;

      esp_map_dma(esp, cmd);
      esp_save_pointers(esp, ent);

      esp_check_command_len(esp, cmd);

      p = esp->command_block;

      esp->msg_out_len = 0;
      if (tp->flags & ESP_TGT_CHECK_NEGO) {
            /* Need to negotiate.  If the target is broken
             * go for synchronous transfers and non-wide.
             */
            if (tp->flags & ESP_TGT_BROKEN) {
                  tp->flags &= ~ESP_TGT_DISCONNECT;
                  tp->nego_goal_period = 0;
                  tp->nego_goal_offset = 0;
                  tp->nego_goal_width = 0;
                  tp->nego_goal_tags = 0;
            }

            /* If the settings are not changing, skip this.  */
            if (spi_width(tp->starget) == tp->nego_goal_width &&
                spi_period(tp->starget) == tp->nego_goal_period &&
                spi_offset(tp->starget) == tp->nego_goal_offset) {
                  tp->flags &= ~ESP_TGT_CHECK_NEGO;
                  goto build_identify;
            }

            if (esp->rev == FASHME && esp_need_to_nego_wide(tp)) {
                  esp->msg_out_len =
                        spi_populate_width_msg(&esp->msg_out[0],
                                           (tp->nego_goal_width ?
                                          1 : 0));
                  tp->flags |= ESP_TGT_NEGO_WIDE;
            } else if (esp_need_to_nego_sync(tp)) {
                  esp->msg_out_len =
                        spi_populate_sync_msg(&esp->msg_out[0],
                                          tp->nego_goal_period,
                                          tp->nego_goal_offset);
                  tp->flags |= ESP_TGT_NEGO_SYNC;
            } else {
                  tp->flags &= ~ESP_TGT_CHECK_NEGO;
            }

            /* Process it like a slow command.  */
            if (tp->flags & (ESP_TGT_NEGO_WIDE | ESP_TGT_NEGO_SYNC))
                  esp->flags |= ESP_FLAG_DOING_SLOWCMD;
      }

build_identify:
      /* If we don't have a lun-data struct yet, we're probing
       * so do not disconnect.  Also, do not disconnect unless
       * we have a tag on this command.
       */
      if (lp && (tp->flags & ESP_TGT_DISCONNECT) && ent->tag[0])
            *p++ = IDENTIFY(1, lun);
      else
            *p++ = IDENTIFY(0, lun);

      if (ent->tag[0] && esp->rev == ESP100) {
            /* ESP100 lacks select w/atn3 command, use select
             * and stop instead.
             */
            esp->flags |= ESP_FLAG_DOING_SLOWCMD;
      }

      if (!(esp->flags & ESP_FLAG_DOING_SLOWCMD)) {
            start_cmd = ESP_CMD_DMA | ESP_CMD_SELA;
            if (ent->tag[0]) {
                  *p++ = ent->tag[0];
                  *p++ = ent->tag[1];

                  start_cmd = ESP_CMD_DMA | ESP_CMD_SA3;
            }

            for (i = 0; i < cmd->cmd_len; i++)
                  *p++ = cmd->cmnd[i];

            esp->select_state = ESP_SELECT_BASIC;
      } else {
            esp->cmd_bytes_left = cmd->cmd_len;
            esp->cmd_bytes_ptr = &cmd->cmnd[0];

            if (ent->tag[0]) {
                  for (i = esp->msg_out_len - 1;
                       i >= 0; i--)
                        esp->msg_out[i + 2] = esp->msg_out[i];
                  esp->msg_out[0] = ent->tag[0];
                  esp->msg_out[1] = ent->tag[1];
                  esp->msg_out_len += 2;
            }

            start_cmd = ESP_CMD_DMA | ESP_CMD_SELAS;
            esp->select_state = ESP_SELECT_MSGOUT;
      }
      val = tgt;
      if (esp->rev == FASHME)
            val |= ESP_BUSID_RESELID | ESP_BUSID_CTR32BIT;
      esp_write8(val, ESP_BUSID);

      esp_write_tgt_sync(esp, tgt);
      esp_write_tgt_config3(esp, tgt);

      val = (p - esp->command_block);

      if (esp_debug & ESP_DEBUG_SCSICMD) {
            printk("ESP: tgt[%d] lun[%d] scsi_cmd [ ", tgt, lun);
            for (i = 0; i < cmd->cmd_len; i++)
                  printk("%02x ", cmd->cmnd[i]);
            printk("]\n");
      }

      if (esp->rev == FASHME)
            scsi_esp_cmd(esp, ESP_CMD_FLUSH);
      esp->ops->send_dma_cmd(esp, esp->command_block_dma,
                         val, 16, 0, start_cmd);
}

static struct esp_cmd_entry *esp_get_ent(struct esp *esp)
{
      struct list_head *head = &esp->esp_cmd_pool;
      struct esp_cmd_entry *ret;

      if (list_empty(head)) {
            ret = kzalloc(sizeof(struct esp_cmd_entry), GFP_ATOMIC);
      } else {
            ret = list_entry(head->next, struct esp_cmd_entry, list);
            list_del(&ret->list);
            memset(ret, 0, sizeof(*ret));
      }
      return ret;
}

static void esp_put_ent(struct esp *esp, struct esp_cmd_entry *ent)
{
      list_add(&ent->list, &esp->esp_cmd_pool);
}

static void esp_cmd_is_done(struct esp *esp, struct esp_cmd_entry *ent,
                      struct scsi_cmnd *cmd, unsigned int result)
{
      struct scsi_device *dev = cmd->device;
      int tgt = dev->id;
      int lun = dev->lun;

      esp->active_cmd = NULL;
      esp_unmap_dma(esp, cmd);
      esp_free_lun_tag(ent, dev->hostdata);
      cmd->result = result;

      if (ent->eh_done) {
            complete(ent->eh_done);
            ent->eh_done = NULL;
      }

      if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
            esp->ops->unmap_single(esp, ent->sense_dma,
                               SCSI_SENSE_BUFFERSIZE, DMA_FROM_DEVICE);
            ent->sense_ptr = NULL;

            /* Restore the message/status bytes to what we actually
             * saw originally.  Also, report that we are providing
             * the sense data.
             */
            cmd->result = ((DRIVER_SENSE << 24) |
                         (DID_OK << 16) |
                         (COMMAND_COMPLETE << 8) |
                         (SAM_STAT_CHECK_CONDITION << 0));

            ent->flags &= ~ESP_CMD_FLAG_AUTOSENSE;
            if (esp_debug & ESP_DEBUG_AUTOSENSE) {
                  int i;

                  printk("esp%d: tgt[%d] lun[%d] AUTO SENSE[ ",
                         esp->host->unique_id, tgt, lun);
                  for (i = 0; i < 18; i++)
                        printk("%02x ", cmd->sense_buffer[i]);
                  printk("]\n");
            }
      }

      cmd->scsi_done(cmd);

      list_del(&ent->list);
      esp_put_ent(esp, ent);

      esp_maybe_execute_command(esp);
}

static unsigned int compose_result(unsigned int status, unsigned int message,
                           unsigned int driver_code)
{
      return (status | (message << 8) | (driver_code << 16));
}

static void esp_event_queue_full(struct esp *esp, struct esp_cmd_entry *ent)
{
      struct scsi_device *dev = ent->cmd->device;
      struct esp_lun_data *lp = dev->hostdata;

      scsi_track_queue_full(dev, lp->num_tagged - 1);
}

static int esp_queuecommand(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
{
      struct scsi_device *dev = cmd->device;
      struct esp *esp = shost_priv(dev->host);
      struct esp_cmd_priv *spriv;
      struct esp_cmd_entry *ent;

      ent = esp_get_ent(esp);
      if (!ent)
            return SCSI_MLQUEUE_HOST_BUSY;

      ent->cmd = cmd;

      cmd->scsi_done = done;

      spriv = ESP_CMD_PRIV(cmd);
      spriv->u.dma_addr = ~(dma_addr_t)0x0;

      list_add_tail(&ent->list, &esp->queued_cmds);

      esp_maybe_execute_command(esp);

      return 0;
}

static int esp_check_gross_error(struct esp *esp)
{
      if (esp->sreg & ESP_STAT_SPAM) {
            /* Gross Error, could be one of:
             * - top of fifo overwritten
             * - top of command register overwritten
             * - DMA programmed with wrong direction
             * - improper phase change
             */
            printk(KERN_ERR PFX "esp%d: Gross error sreg[%02x]\n",
                   esp->host->unique_id, esp->sreg);
            /* XXX Reset the chip. XXX */
            return 1;
      }
      return 0;
}

static int esp_check_spur_intr(struct esp *esp)
{
      switch (esp->rev) {
      case ESP100:
      case ESP100A:
            /* The interrupt pending bit of the status register cannot
             * be trusted on these revisions.
             */
            esp->sreg &= ~ESP_STAT_INTR;
            break;

      default:
            if (!(esp->sreg & ESP_STAT_INTR)) {
                  esp->ireg = esp_read8(ESP_INTRPT);
                  if (esp->ireg & ESP_INTR_SR)
                        return 1;

                  /* If the DMA is indicating interrupt pending and the
                   * ESP is not, the only possibility is a DMA error.
                   */
                  if (!esp->ops->dma_error(esp)) {
                        printk(KERN_ERR PFX "esp%d: Spurious irq, "
                               "sreg=%x.\n",
                               esp->host->unique_id, esp->sreg);
                        return -1;
                  }

                  printk(KERN_ERR PFX "esp%d: DMA error\n",
                         esp->host->unique_id);

                  /* XXX Reset the chip. XXX */
                  return -1;
            }
            break;
      }

      return 0;
}

static void esp_schedule_reset(struct esp *esp)
{
      esp_log_reset("ESP: esp_schedule_reset() from %p\n",
                  __builtin_return_address(0));
      esp->flags |= ESP_FLAG_RESETTING;
      esp_event(esp, ESP_EVENT_RESET);
}

/* In order to avoid having to add a special half-reconnected state
 * into the driver we just sit here and poll through the rest of
 * the reselection process to get the tag message bytes.
 */
static struct esp_cmd_entry *esp_reconnect_with_tag(struct esp *esp,
                                        struct esp_lun_data *lp)
{
      struct esp_cmd_entry *ent;
      int i;

      if (!lp->num_tagged) {
            printk(KERN_ERR PFX "esp%d: Reconnect w/num_tagged==0\n",
                   esp->host->unique_id);
            return NULL;
      }

      esp_log_reconnect("ESP: reconnect tag, ");

      for (i = 0; i < ESP_QUICKIRQ_LIMIT; i++) {
            if (esp->ops->irq_pending(esp))
                  break;
      }
      if (i == ESP_QUICKIRQ_LIMIT) {
            printk(KERN_ERR PFX "esp%d: Reconnect IRQ1 timeout\n",
                   esp->host->unique_id);
            return NULL;
      }

      esp->sreg = esp_read8(ESP_STATUS);
      esp->ireg = esp_read8(ESP_INTRPT);

      esp_log_reconnect("IRQ(%d:%x:%x), ",
                    i, esp->ireg, esp->sreg);

      if (esp->ireg & ESP_INTR_DC) {
            printk(KERN_ERR PFX "esp%d: Reconnect, got disconnect.\n",
                   esp->host->unique_id);
            return NULL;
      }

      if ((esp->sreg & ESP_STAT_PMASK) != ESP_MIP) {
            printk(KERN_ERR PFX "esp%d: Reconnect, not MIP sreg[%02x].\n",
                   esp->host->unique_id, esp->sreg);
            return NULL;
      }

      /* DMA in the tag bytes... */
      esp->command_block[0] = 0xff;
      esp->command_block[1] = 0xff;
      esp->ops->send_dma_cmd(esp, esp->command_block_dma,
                         2, 2, 1, ESP_CMD_DMA | ESP_CMD_TI);

      /* ACK the msssage.  */
      scsi_esp_cmd(esp, ESP_CMD_MOK);

      for (i = 0; i < ESP_RESELECT_TAG_LIMIT; i++) {
            if (esp->ops->irq_pending(esp)) {
                  esp->sreg = esp_read8(ESP_STATUS);
                  esp->ireg = esp_read8(ESP_INTRPT);
                  if (esp->ireg & ESP_INTR_FDONE)
                        break;
            }
            udelay(1);
      }
      if (i == ESP_RESELECT_TAG_LIMIT) {
            printk(KERN_ERR PFX "esp%d: Reconnect IRQ2 timeout\n",
                   esp->host->unique_id);
            return NULL;
      }
      esp->ops->dma_drain(esp);
      esp->ops->dma_invalidate(esp);

      esp_log_reconnect("IRQ2(%d:%x:%x) tag[%x:%x]\n",
                    i, esp->ireg, esp->sreg,
                    esp->command_block[0],
                    esp->command_block[1]);

      if (esp->command_block[0] < SIMPLE_QUEUE_TAG ||
          esp->command_block[0] > ORDERED_QUEUE_TAG) {
            printk(KERN_ERR PFX "esp%d: Reconnect, bad tag "
                   "type %02x.\n",
                   esp->host->unique_id, esp->command_block[0]);
            return NULL;
      }

      ent = lp->tagged_cmds[esp->command_block[1]];
      if (!ent) {
            printk(KERN_ERR PFX "esp%d: Reconnect, no entry for "
                   "tag %02x.\n",
                   esp->host->unique_id, esp->command_block[1]);
            return NULL;
      }

      return ent;
}

static int esp_reconnect(struct esp *esp)
{
      struct esp_cmd_entry *ent;
      struct esp_target_data *tp;
      struct esp_lun_data *lp;
      struct scsi_device *dev;
      int target, lun;

      BUG_ON(esp->active_cmd);
      if (esp->rev == FASHME) {
            /* FASHME puts the target and lun numbers directly
             * into the fifo.
             */
            target = esp->fifo[0];
            lun = esp->fifo[1] & 0x7;
      } else {
            u8 bits = esp_read8(ESP_FDATA);

            /* Older chips put the lun directly into the fifo, but
             * the target is given as a sample of the arbitration
             * lines on the bus at reselection time.  So we should
             * see the ID of the ESP and the one reconnecting target
             * set in the bitmap.
             */
            if (!(bits & esp->scsi_id_mask))
                  goto do_reset;
            bits &= ~esp->scsi_id_mask;
            if (!bits || (bits & (bits - 1)))
                  goto do_reset;

            target = ffs(bits) - 1;
            lun = (esp_read8(ESP_FDATA) & 0x7);

            scsi_esp_cmd(esp, ESP_CMD_FLUSH);
            if (esp->rev == ESP100) {
                  u8 ireg = esp_read8(ESP_INTRPT);
                  /* This chip has a bug during reselection that can
                   * cause a spurious illegal-command interrupt, which
                   * we simply ACK here.  Another possibility is a bus
                   * reset so we must check for that.
                   */
                  if (ireg & ESP_INTR_SR)
                        goto do_reset;
            }
            scsi_esp_cmd(esp, ESP_CMD_NULL);
      }

      esp_write_tgt_sync(esp, target);
      esp_write_tgt_config3(esp, target);

      scsi_esp_cmd(esp, ESP_CMD_MOK);

      if (esp->rev == FASHME)
            esp_write8(target | ESP_BUSID_RESELID | ESP_BUSID_CTR32BIT,
                     ESP_BUSID);

      tp = &esp->target[target];
      dev = __scsi_device_lookup_by_target(tp->starget, lun);
      if (!dev) {
            printk(KERN_ERR PFX "esp%d: Reconnect, no lp "
                   "tgt[%u] lun[%u]\n",
                   esp->host->unique_id, target, lun);
            goto do_reset;
      }
      lp = dev->hostdata;

      ent = lp->non_tagged_cmd;
      if (!ent) {
            ent = esp_reconnect_with_tag(esp, lp);
            if (!ent)
                  goto do_reset;
      }

      esp->active_cmd = ent;

      if (ent->flags & ESP_CMD_FLAG_ABORT) {
            esp->msg_out[0] = ABORT_TASK_SET;
            esp->msg_out_len = 1;
            scsi_esp_cmd(esp, ESP_CMD_SATN);
      }

      esp_event(esp, ESP_EVENT_CHECK_PHASE);
      esp_restore_pointers(esp, ent);
      esp->flags |= ESP_FLAG_QUICKIRQ_CHECK;
      return 1;

do_reset:
      esp_schedule_reset(esp);
      return 0;
}

static int esp_finish_select(struct esp *esp)
{
      struct esp_cmd_entry *ent;
      struct scsi_cmnd *cmd;
      u8 orig_select_state;

      orig_select_state = esp->select_state;

      /* No longer selecting.  */
      esp->select_state = ESP_SELECT_NONE;

      esp->seqreg = esp_read8(ESP_SSTEP) & ESP_STEP_VBITS;
      ent = esp->active_cmd;
      cmd = ent->cmd;

      if (esp->ops->dma_error(esp)) {
            /* If we see a DMA error during or as a result of selection,
             * all bets are off.
             */
            esp_schedule_reset(esp);
            esp_cmd_is_done(esp, ent, cmd, (DID_ERROR << 16));
            return 0;
      }

      esp->ops->dma_invalidate(esp);

      if (esp->ireg == (ESP_INTR_RSEL | ESP_INTR_FDONE)) {
            struct esp_target_data *tp = &esp->target[cmd->device->id];

            /* Carefully back out of the selection attempt.  Release
             * resources (such as DMA mapping & TAG) and reset state (such
             * as message out and command delivery variables).
             */
            if (!(ent->flags & ESP_CMD_FLAG_AUTOSENSE)) {
                  esp_unmap_dma(esp, cmd);
                  esp_free_lun_tag(ent, cmd->device->hostdata);
                  tp->flags &= ~(ESP_TGT_NEGO_SYNC | ESP_TGT_NEGO_WIDE);
                  esp->flags &= ~ESP_FLAG_DOING_SLOWCMD;
                  esp->cmd_bytes_ptr = NULL;
                  esp->cmd_bytes_left = 0;
            } else {
                  esp->ops->unmap_single(esp, ent->sense_dma,
                                     SCSI_SENSE_BUFFERSIZE,
                                     DMA_FROM_DEVICE);
                  ent->sense_ptr = NULL;
            }

            /* Now that the state is unwound properly, put back onto
             * the issue queue.  This command is no longer active.
             */
            list_del(&ent->list);
            list_add(&ent->list, &esp->queued_cmds);
            esp->active_cmd = NULL;

            /* Return value ignored by caller, it directly invokes
             * esp_reconnect().
             */
            return 0;
      }

      if (esp->ireg == ESP_INTR_DC) {
            struct scsi_device *dev = cmd->device;

            /* Disconnect.  Make sure we re-negotiate sync and
             * wide parameters if this target starts responding
             * again in the future.
             */
            esp->target[dev->id].flags |= ESP_TGT_CHECK_NEGO;

            scsi_esp_cmd(esp, ESP_CMD_ESEL);
            esp_cmd_is_done(esp, ent, cmd, (DID_BAD_TARGET << 16));
            return 1;
      }

      if (esp->ireg == (ESP_INTR_FDONE | ESP_INTR_BSERV)) {
            /* Selection successful.  On pre-FAST chips we have
             * to do a NOP and possibly clean out the FIFO.
             */
            if (esp->rev <= ESP236) {
                  int fcnt = esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES;

                  scsi_esp_cmd(esp, ESP_CMD_NULL);

                  if (!fcnt &&
                      (!esp->prev_soff ||
                       ((esp->sreg & ESP_STAT_PMASK) != ESP_DIP)))
                        esp_flush_fifo(esp);
            }

            /* If we are doing a slow command, negotiation, etc.
             * we'll do the right thing as we transition to the
             * next phase.
             */
            esp_event(esp, ESP_EVENT_CHECK_PHASE);
            return 0;
      }

      printk("ESP: Unexpected selection completion ireg[%x].\n",
             esp->ireg);
      esp_schedule_reset(esp);
      return 0;
}

static int esp_data_bytes_sent(struct esp *esp, struct esp_cmd_entry *ent,
                         struct scsi_cmnd *cmd)
{
      int fifo_cnt, ecount, bytes_sent, flush_fifo;

      fifo_cnt = esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES;
      if (esp->prev_cfg3 & ESP_CONFIG3_EWIDE)
            fifo_cnt <<= 1;

      ecount = 0;
      if (!(esp->sreg & ESP_STAT_TCNT)) {
            ecount = ((unsigned int)esp_read8(ESP_TCLOW) |
                    (((unsigned int)esp_read8(ESP_TCMED)) << 8));
            if (esp->rev == FASHME)
                  ecount |= ((unsigned int)esp_read8(FAS_RLO)) << 16;
      }

      bytes_sent = esp->data_dma_len;
      bytes_sent -= ecount;

      if (!(ent->flags & ESP_CMD_FLAG_WRITE))
            bytes_sent -= fifo_cnt;

      flush_fifo = 0;
      if (!esp->prev_soff) {
            /* Synchronous data transfer, always flush fifo. */
            flush_fifo = 1;
      } else {
            if (esp->rev == ESP100) {
                  u32 fflags, phase;

                  /* ESP100 has a chip bug where in the synchronous data
                   * phase it can mistake a final long REQ pulse from the
                   * target as an extra data byte.  Fun.
                   *
                   * To detect this case we resample the status register
                   * and fifo flags.  If we're still in a data phase and
                   * we see spurious chunks in the fifo, we return error
                   * to the caller which should reset and set things up
                   * such that we only try future transfers to this
                   * target in synchronous mode.
                   */
                  esp->sreg = esp_read8(ESP_STATUS);
                  phase = esp->sreg & ESP_STAT_PMASK;
                  fflags = esp_read8(ESP_FFLAGS);

                  if ((phase == ESP_DOP &&
                       (fflags & ESP_FF_ONOTZERO)) ||
                      (phase == ESP_DIP &&
                       (fflags & ESP_FF_FBYTES)))
                        return -1;
            }
            if (!(ent->flags & ESP_CMD_FLAG_WRITE))
                  flush_fifo = 1;
      }

      if (flush_fifo)
            esp_flush_fifo(esp);

      return bytes_sent;
}

static void esp_setsync(struct esp *esp, struct esp_target_data *tp,
                  u8 scsi_period, u8 scsi_offset,
                  u8 esp_stp, u8 esp_soff)
{
      spi_period(tp->starget) = scsi_period;
      spi_offset(tp->starget) = scsi_offset;
      spi_width(tp->starget) = (tp->flags & ESP_TGT_WIDE) ? 1 : 0;

      if (esp_soff) {
            esp_stp &= 0x1f;
            esp_soff |= esp->radelay;
            if (esp->rev >= FAS236) {
                  u8 bit = ESP_CONFIG3_FSCSI;
                  if (esp->rev >= FAS100A)
                        bit = ESP_CONFIG3_FAST;

                  if (scsi_period < 50) {
                        if (esp->rev == FASHME)
                              esp_soff &= ~esp->radelay;
                        tp->esp_config3 |= bit;
                  } else {
                        tp->esp_config3 &= ~bit;
                  }
                  esp->prev_cfg3 = tp->esp_config3;
                  esp_write8(esp->prev_cfg3, ESP_CFG3);
            }
      }

      tp->esp_period = esp->prev_stp = esp_stp;
      tp->esp_offset = esp->prev_soff = esp_soff;

      esp_write8(esp_soff, ESP_SOFF);
      esp_write8(esp_stp, ESP_STP);

      tp->flags &= ~(ESP_TGT_NEGO_SYNC | ESP_TGT_CHECK_NEGO);

      spi_display_xfer_agreement(tp->starget);
}

static void esp_msgin_reject(struct esp *esp)
{
      struct esp_cmd_entry *ent = esp->active_cmd;
      struct scsi_cmnd *cmd = ent->cmd;
      struct esp_target_data *tp;
      int tgt;

      tgt = cmd->device->id;
      tp = &esp->target[tgt];

      if (tp->flags & ESP_TGT_NEGO_WIDE) {
            tp->flags &= ~(ESP_TGT_NEGO_WIDE | ESP_TGT_WIDE);

            if (!esp_need_to_nego_sync(tp)) {
                  tp->flags &= ~ESP_TGT_CHECK_NEGO;
                  scsi_esp_cmd(esp, ESP_CMD_RATN);
            } else {
                  esp->msg_out_len =
                        spi_populate_sync_msg(&esp->msg_out[0],
                                          tp->nego_goal_period,
                                          tp->nego_goal_offset);
                  tp->flags |= ESP_TGT_NEGO_SYNC;
                  scsi_esp_cmd(esp, ESP_CMD_SATN);
            }
            return;
      }

      if (tp->flags & ESP_TGT_NEGO_SYNC) {
            tp->flags &= ~(ESP_TGT_NEGO_SYNC | ESP_TGT_CHECK_NEGO);
            tp->esp_period = 0;
            tp->esp_offset = 0;
            esp_setsync(esp, tp, 0, 0, 0, 0);
            scsi_esp_cmd(esp, ESP_CMD_RATN);
            return;
      }

      esp->msg_out[0] = ABORT_TASK_SET;
      esp->msg_out_len = 1;
      scsi_esp_cmd(esp, ESP_CMD_SATN);
}

static void esp_msgin_sdtr(struct esp *esp, struct esp_target_data *tp)
{
      u8 period = esp->msg_in[3];
      u8 offset = esp->msg_in[4];
      u8 stp;

      if (!(tp->flags & ESP_TGT_NEGO_SYNC))
            goto do_reject;

      if (offset > 15)
            goto do_reject;

      if (offset) {
            int rounded_up, one_clock;

            if (period > esp->max_period) {
                  period = offset = 0;
                  goto do_sdtr;
            }
            if (period < esp->min_period)
                  goto do_reject;

            one_clock = esp->ccycle / 1000;
            rounded_up = (period << 2);
            rounded_up = (rounded_up + one_clock - 1) / one_clock;
            stp = rounded_up;
            if (stp && esp->rev >= FAS236) {
                  if (stp >= 50)
                        stp--;
            }
      } else {
            stp = 0;
      }

      esp_setsync(esp, tp, period, offset, stp, offset);
      return;

do_reject:
      esp->msg_out[0] = MESSAGE_REJECT;
      esp->msg_out_len = 1;
      scsi_esp_cmd(esp, ESP_CMD_SATN);
      return;

do_sdtr:
      tp->nego_goal_period = period;
      tp->nego_goal_offset = offset;
      esp->msg_out_len =
            spi_populate_sync_msg(&esp->msg_out[0],
                              tp->nego_goal_period,
                              tp->nego_goal_offset);
      scsi_esp_cmd(esp, ESP_CMD_SATN);
}

static void esp_msgin_wdtr(struct esp *esp, struct esp_target_data *tp)
{
      int size = 8 << esp->msg_in[3];
      u8 cfg3;

      if (esp->rev != FASHME)
            goto do_reject;

      if (size != 8 && size != 16)
            goto do_reject;

      if (!(tp->flags & ESP_TGT_NEGO_WIDE))
            goto do_reject;

      cfg3 = tp->esp_config3;
      if (size == 16) {
            tp->flags |= ESP_TGT_WIDE;
            cfg3 |= ESP_CONFIG3_EWIDE;
      } else {
            tp->flags &= ~ESP_TGT_WIDE;
            cfg3 &= ~ESP_CONFIG3_EWIDE;
      }
      tp->esp_config3 = cfg3;
      esp->prev_cfg3 = cfg3;
      esp_write8(cfg3, ESP_CFG3);

      tp->flags &= ~ESP_TGT_NEGO_WIDE;

      spi_period(tp->starget) = 0;
      spi_offset(tp->starget) = 0;
      if (!esp_need_to_nego_sync(tp)) {
            tp->flags &= ~ESP_TGT_CHECK_NEGO;
            scsi_esp_cmd(esp, ESP_CMD_RATN);
      } else {
            esp->msg_out_len =
                  spi_populate_sync_msg(&esp->msg_out[0],
                                    tp->nego_goal_period,
                                    tp->nego_goal_offset);
            tp->flags |= ESP_TGT_NEGO_SYNC;
            scsi_esp_cmd(esp, ESP_CMD_SATN);
      }
      return;

do_reject:
      esp->msg_out[0] = MESSAGE_REJECT;
      esp->msg_out_len = 1;
      scsi_esp_cmd(esp, ESP_CMD_SATN);
}

static void esp_msgin_extended(struct esp *esp)
{
      struct esp_cmd_entry *ent = esp->active_cmd;
      struct scsi_cmnd *cmd = ent->cmd;
      struct esp_target_data *tp;
      int tgt = cmd->device->id;

      tp = &esp->target[tgt];
      if (esp->msg_in[2] == EXTENDED_SDTR) {
            esp_msgin_sdtr(esp, tp);
            return;
      }
      if (esp->msg_in[2] == EXTENDED_WDTR) {
            esp_msgin_wdtr(esp, tp);
            return;
      }

      printk("ESP: Unexpected extended msg type %x\n",
             esp->msg_in[2]);

      esp->msg_out[0] = ABORT_TASK_SET;
      esp->msg_out_len = 1;
      scsi_esp_cmd(esp, ESP_CMD_SATN);
}

/* Analyze msgin bytes received from target so far.  Return non-zero
 * if there are more bytes needed to complete the message.
 */
static int esp_msgin_process(struct esp *esp)
{
      u8 msg0 = esp->msg_in[0];
      int len = esp->msg_in_len;

      if (msg0 & 0x80) {
            /* Identify */
            printk("ESP: Unexpected msgin identify\n");
            return 0;
      }

      switch (msg0) {
      case EXTENDED_MESSAGE:
            if (len == 1)
                  return 1;
            if (len < esp->msg_in[1] + 2)
                  return 1;
            esp_msgin_extended(esp);
            return 0;

      case IGNORE_WIDE_RESIDUE: {
            struct esp_cmd_entry *ent;
            struct esp_cmd_priv *spriv;
            if (len == 1)
                  return 1;

            if (esp->msg_in[1] != 1)
                  goto do_reject;

            ent = esp->active_cmd;
            spriv = ESP_CMD_PRIV(ent->cmd);

            if (spriv->cur_residue == sg_dma_len(spriv->cur_sg)) {
                  spriv->cur_sg--;
                  spriv->cur_residue = 1;
            } else
                  spriv->cur_residue++;
            spriv->tot_residue++;
            return 0;
      }
      case NOP:
            return 0;
      case RESTORE_POINTERS:
            esp_restore_pointers(esp, esp->active_cmd);
            return 0;
      case SAVE_POINTERS:
            esp_save_pointers(esp, esp->active_cmd);
            return 0;

      case COMMAND_COMPLETE:
      case DISCONNECT: {
            struct esp_cmd_entry *ent = esp->active_cmd;

            ent->message = msg0;
            esp_event(esp, ESP_EVENT_FREE_BUS);
            esp->flags |= ESP_FLAG_QUICKIRQ_CHECK;
            return 0;
      }
      case MESSAGE_REJECT:
            esp_msgin_reject(esp);
            return 0;

      default:
      do_reject:
            esp->msg_out[0] = MESSAGE_REJECT;
            esp->msg_out_len = 1;
            scsi_esp_cmd(esp, ESP_CMD_SATN);
            return 0;
      }
}

static int esp_process_event(struct esp *esp)
{
      int write;

again:
      write = 0;
      switch (esp->event) {
      case ESP_EVENT_CHECK_PHASE:
            switch (esp->sreg & ESP_STAT_PMASK) {
            case ESP_DOP:
                  esp_event(esp, ESP_EVENT_DATA_OUT);
                  break;
            case ESP_DIP:
                  esp_event(esp, ESP_EVENT_DATA_IN);
                  break;
            case ESP_STATP:
                  esp_flush_fifo(esp);
                  scsi_esp_cmd(esp, ESP_CMD_ICCSEQ);
                  esp_event(esp, ESP_EVENT_STATUS);
                  esp->flags |= ESP_FLAG_QUICKIRQ_CHECK;
                  return 1;

            case ESP_MOP:
                  esp_event(esp, ESP_EVENT_MSGOUT);
                  break;

            case ESP_MIP:
                  esp_event(esp, ESP_EVENT_MSGIN);
                  break;

            case ESP_CMDP:
                  esp_event(esp, ESP_EVENT_CMD_START);
                  break;

            default:
                  printk("ESP: Unexpected phase, sreg=%02x\n",
                         esp->sreg);
                  esp_schedule_reset(esp);
                  return 0;
            }
            goto again;
            break;

      case ESP_EVENT_DATA_IN:
            write = 1;
            /* fallthru */

      case ESP_EVENT_DATA_OUT: {
            struct esp_cmd_entry *ent = esp->active_cmd;
            struct scsi_cmnd *cmd = ent->cmd;
            dma_addr_t dma_addr = esp_cur_dma_addr(ent, cmd);
            unsigned int dma_len = esp_cur_dma_len(ent, cmd);

            if (esp->rev == ESP100)
                  scsi_esp_cmd(esp, ESP_CMD_NULL);

            if (write)
                  ent->flags |= ESP_CMD_FLAG_WRITE;
            else
                  ent->flags &= ~ESP_CMD_FLAG_WRITE;

            dma_len = esp_dma_length_limit(esp, dma_addr, dma_len);
            esp->data_dma_len = dma_len;

            if (!dma_len) {
                  printk(KERN_ERR PFX "esp%d: DMA length is zero!\n",
                         esp->host->unique_id);
                  printk(KERN_ERR PFX "esp%d: cur adr[%08llx] len[%08x]\n",
                         esp->host->unique_id,
                         (unsigned long long)esp_cur_dma_addr(ent, cmd),
                         esp_cur_dma_len(ent, cmd));
                  esp_schedule_reset(esp);
                  return 0;
            }

            esp_log_datastart("ESP: start data addr[%08llx] len[%u] "
                          "write(%d)\n",
                          (unsigned long long)dma_addr, dma_len, write);

            esp->ops->send_dma_cmd(esp, dma_addr, dma_len, dma_len,
                               write, ESP_CMD_DMA | ESP_CMD_TI);
            esp_event(esp, ESP_EVENT_DATA_DONE);
            break;
      }
      case ESP_EVENT_DATA_DONE: {
            struct esp_cmd_entry *ent = esp->active_cmd;
            struct scsi_cmnd *cmd = ent->cmd;
            int bytes_sent;

            if (esp->ops->dma_error(esp)) {
                  printk("ESP: data done, DMA error, resetting\n");
                  esp_schedule_reset(esp);
                  return 0;
            }

            if (ent->flags & ESP_CMD_FLAG_WRITE) {
                  /* XXX parity errors, etc. XXX */

                  esp->ops->dma_drain(esp);
            }
            esp->ops->dma_invalidate(esp);

            if (esp->ireg != ESP_INTR_BSERV) {
                  /* We should always see exactly a bus-service
                   * interrupt at the end of a successful transfer.
                   */
                  printk("ESP: data done, not BSERV, resetting\n");
                  esp_schedule_reset(esp);
                  return 0;
            }

            bytes_sent = esp_data_bytes_sent(esp, ent, cmd);

            esp_log_datadone("ESP: data done flgs[%x] sent[%d]\n",
                         ent->flags, bytes_sent);

            if (bytes_sent < 0) {
                  /* XXX force sync mode for this target XXX */
                  esp_schedule_reset(esp);
                  return 0;
            }

            esp_advance_dma(esp, ent, cmd, bytes_sent);
            esp_event(esp, ESP_EVENT_CHECK_PHASE);
            goto again;
            break;
      }

      case ESP_EVENT_STATUS: {
            struct esp_cmd_entry *ent = esp->active_cmd;

            if (esp->ireg & ESP_INTR_FDONE) {
                  ent->status = esp_read8(ESP_FDATA);
                  ent->message = esp_read8(ESP_FDATA);
                  scsi_esp_cmd(esp, ESP_CMD_MOK);
            } else if (esp->ireg == ESP_INTR_BSERV) {
                  ent->status = esp_read8(ESP_FDATA);
                  ent->message = 0xff;
                  esp_event(esp, ESP_EVENT_MSGIN);
                  return 0;
            }

            if (ent->message != COMMAND_COMPLETE) {
                  printk("ESP: Unexpected message %x in status\n",
                         ent->message);
                  esp_schedule_reset(esp);
                  return 0;
            }

            esp_event(esp, ESP_EVENT_FREE_BUS);
            esp->flags |= ESP_FLAG_QUICKIRQ_CHECK;
            break;
      }
      case ESP_EVENT_FREE_BUS: {
            struct esp_cmd_entry *ent = esp->active_cmd;
            struct scsi_cmnd *cmd = ent->cmd;

            if (ent->message == COMMAND_COMPLETE ||
                ent->message == DISCONNECT)
                  scsi_esp_cmd(esp, ESP_CMD_ESEL);

            if (ent->message == COMMAND_COMPLETE) {
                  esp_log_cmddone("ESP: Command done status[%x] "
                              "message[%x]\n",
                              ent->status, ent->message);
                  if (ent->status == SAM_STAT_TASK_SET_FULL)
                        esp_event_queue_full(esp, ent);

                  if (ent->status == SAM_STAT_CHECK_CONDITION &&
                      !(ent->flags & ESP_CMD_FLAG_AUTOSENSE)) {
                        ent->flags |= ESP_CMD_FLAG_AUTOSENSE;
                        esp_autosense(esp, ent);
                  } else {
                        esp_cmd_is_done(esp, ent, cmd,
                                    compose_result(ent->status,
                                                 ent->message,
                                                 DID_OK));
                  }
            } else if (ent->message == DISCONNECT) {
                  esp_log_disconnect("ESP: Disconnecting tgt[%d] "
                                 "tag[%x:%x]\n",
                                 cmd->device->id,
                                 ent->tag[0], ent->tag[1]);

                  esp->active_cmd = NULL;
                  esp_maybe_execute_command(esp);
            } else {
                  printk("ESP: Unexpected message %x in freebus\n",
                         ent->message);
                  esp_schedule_reset(esp);
                  return 0;
            }
            if (esp->active_cmd)
                  esp->flags |= ESP_FLAG_QUICKIRQ_CHECK;
            break;
      }
      case ESP_EVENT_MSGOUT: {
            scsi_esp_cmd(esp, ESP_CMD_FLUSH);

            if (esp_debug & ESP_DEBUG_MSGOUT) {
                  int i;
                  printk("ESP: Sending message [ ");
                  for (i = 0; i < esp->msg_out_len; i++)
                        printk("%02x ", esp->msg_out[i]);
                  printk("]\n");
            }

            if (esp->rev == FASHME) {
                  int i;

                  /* Always use the fifo.  */
                  for (i = 0; i < esp->msg_out_len; i++) {
                        esp_write8(esp->msg_out[i], ESP_FDATA);
                        esp_write8(0, ESP_FDATA);
                  }
                  scsi_esp_cmd(esp, ESP_CMD_TI);
            } else {
                  if (esp->msg_out_len == 1) {
                        esp_write8(esp->msg_out[0], ESP_FDATA);
                        scsi_esp_cmd(esp, ESP_CMD_TI);
                  } else {
                        /* Use DMA. */
                        memcpy(esp->command_block,
                               esp->msg_out,
                               esp->msg_out_len);

                        esp->ops->send_dma_cmd(esp,
                                           esp->command_block_dma,
                                           esp->msg_out_len,
                                           esp->msg_out_len,
                                           0,
                                           ESP_CMD_DMA|ESP_CMD_TI);
                  }
            }
            esp_event(esp, ESP_EVENT_MSGOUT_DONE);
            break;
      }
      case ESP_EVENT_MSGOUT_DONE:
            if (esp->rev == FASHME) {
                  scsi_esp_cmd(esp, ESP_CMD_FLUSH);
            } else {
                  if (esp->msg_out_len > 1)
                        esp->ops->dma_invalidate(esp);
            }

            if (!(esp->ireg & ESP_INTR_DC)) {
                  if (esp->rev != FASHME)
                        scsi_esp_cmd(esp, ESP_CMD_NULL);
            }
            esp_event(esp, ESP_EVENT_CHECK_PHASE);
            goto again;
      case ESP_EVENT_MSGIN:
            if (esp->ireg & ESP_INTR_BSERV) {
                  if (esp->rev == FASHME) {
                        if (!(esp_read8(ESP_STATUS2) &
                              ESP_STAT2_FEMPTY))
                              scsi_esp_cmd(esp, ESP_CMD_FLUSH);
                  } else {
                        scsi_esp_cmd(esp, ESP_CMD_FLUSH);
                        if (esp->rev == ESP100)
                              scsi_esp_cmd(esp, ESP_CMD_NULL);
                  }
                  scsi_esp_cmd(esp, ESP_CMD_TI);
                  esp->flags |= ESP_FLAG_QUICKIRQ_CHECK;
                  return 1;
            }
            if (esp->ireg & ESP_INTR_FDONE) {
                  u8 val;

                  if (esp->rev == FASHME)
                        val = esp->fifo[0];
                  else
                        val = esp_read8(ESP_FDATA);
                  esp->msg_in[esp->msg_in_len++] = val;

                  esp_log_msgin("ESP: Got msgin byte %x\n", val);

                  if (!esp_msgin_process(esp))
                        esp->msg_in_len = 0;

                  if (esp->rev == FASHME)
                        scsi_esp_cmd(esp, ESP_CMD_FLUSH);

                  scsi_esp_cmd(esp, ESP_CMD_MOK);

                  if (esp->event != ESP_EVENT_FREE_BUS)
                        esp_event(esp, ESP_EVENT_CHECK_PHASE);
            } else {
                  printk("ESP: MSGIN neither BSERV not FDON, resetting");
                  esp_schedule_reset(esp);
                  return 0;
            }
            break;
      case ESP_EVENT_CMD_START:
            memcpy(esp->command_block, esp->cmd_bytes_ptr,
                   esp->cmd_bytes_left);
            if (esp->rev == FASHME)
                  scsi_esp_cmd(esp, ESP_CMD_FLUSH);
            esp->ops->send_dma_cmd(esp, esp->command_block_dma,
                               esp->cmd_bytes_left, 16, 0,
                               ESP_CMD_DMA | ESP_CMD_TI);
            esp_event(esp, ESP_EVENT_CMD_DONE);
            esp->flags |= ESP_FLAG_QUICKIRQ_CHECK;
            break;
      case ESP_EVENT_CMD_DONE:
            esp->ops->dma_invalidate(esp);
            if (esp->ireg & ESP_INTR_BSERV) {
                  esp_event(esp, ESP_EVENT_CHECK_PHASE);
                  goto again;
            }
            esp_schedule_reset(esp);
            return 0;
            break;

      case ESP_EVENT_RESET:
            scsi_esp_cmd(esp, ESP_CMD_RS);
            break;

      default:
            printk("ESP: Unexpected event %x, resetting\n",
                   esp->event);
            esp_schedule_reset(esp);
            return 0;
            break;
      }
      return 1;
}

static void esp_reset_cleanup_one(struct esp *esp, struct esp_cmd_entry *ent)
{
      struct scsi_cmnd *cmd = ent->cmd;

      esp_unmap_dma(esp, cmd);
      esp_free_lun_tag(ent, cmd->device->hostdata);
      cmd->result = DID_RESET << 16;

      if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
            esp->ops->unmap_single(esp, ent->sense_dma,
                               SCSI_SENSE_BUFFERSIZE, DMA_FROM_DEVICE);
            ent->sense_ptr = NULL;
      }

      cmd->scsi_done(cmd);
      list_del(&ent->list);
      esp_put_ent(esp, ent);
}

static void esp_clear_hold(struct scsi_device *dev, void *data)
{
      struct esp_lun_data *lp = dev->hostdata;

      BUG_ON(lp->num_tagged);
      lp->hold = 0;
}

static void esp_reset_cleanup(struct esp *esp)
{
      struct esp_cmd_entry *ent, *tmp;
      int i;

      list_for_each_entry_safe(ent, tmp, &esp->queued_cmds, list) {
            struct scsi_cmnd *cmd = ent->cmd;

            list_del(&ent->list);
            cmd->result = DID_RESET << 16;
            cmd->scsi_done(cmd);
            esp_put_ent(esp, ent);
      }

      list_for_each_entry_safe(ent, tmp, &esp->active_cmds, list) {
            if (ent == esp->active_cmd)
                  esp->active_cmd = NULL;
            esp_reset_cleanup_one(esp, ent);
      }

      BUG_ON(esp->active_cmd != NULL);

      /* Force renegotiation of sync/wide transfers.  */
      for (i = 0; i < ESP_MAX_TARGET; i++) {
            struct esp_target_data *tp = &esp->target[i];

            tp->esp_period = 0;
            tp->esp_offset = 0;
            tp->esp_config3 &= ~(ESP_CONFIG3_EWIDE |
                             ESP_CONFIG3_FSCSI |
                             ESP_CONFIG3_FAST);
            tp->flags &= ~ESP_TGT_WIDE;
            tp->flags |= ESP_TGT_CHECK_NEGO;

            if (tp->starget)
                  __starget_for_each_device(tp->starget, NULL,
                                      esp_clear_hold);
      }
      esp->flags &= ~ESP_FLAG_RESETTING;
}

/* Runs under host->lock */
static void __esp_interrupt(struct esp *esp)
{
      int finish_reset, intr_done;
      u8 phase;

      esp->sreg = esp_read8(ESP_STATUS);

      if (esp->flags & ESP_FLAG_RESETTING) {
            finish_reset = 1;
      } else {
            if (esp_check_gross_error(esp))
                  return;

            finish_reset = esp_check_spur_intr(esp);
            if (finish_reset < 0)
                  return;
      }

      esp->ireg = esp_read8(ESP_INTRPT);

      if (esp->ireg & ESP_INTR_SR)
            finish_reset = 1;

      if (finish_reset) {
            esp_reset_cleanup(esp);
            if (esp->eh_reset) {
                  complete(esp->eh_reset);
                  esp->eh_reset = NULL;
            }
            return;
      }

      phase = (esp->sreg & ESP_STAT_PMASK);
      if (esp->rev == FASHME) {
            if (((phase != ESP_DIP && phase != ESP_DOP) &&
                 esp->select_state == ESP_SELECT_NONE &&
                 esp->event != ESP_EVENT_STATUS &&
                 esp->event != ESP_EVENT_DATA_DONE) ||
                (esp->ireg & ESP_INTR_RSEL)) {
                  esp->sreg2 = esp_read8(ESP_STATUS2);
                  if (!(esp->sreg2 & ESP_STAT2_FEMPTY) ||
                      (esp->sreg2 & ESP_STAT2_F1BYTE))
                        hme_read_fifo(esp);
            }
      }

      esp_log_intr("ESP: intr sreg[%02x] seqreg[%02x] "
                 "sreg2[%02x] ireg[%02x]\n",
                 esp->sreg, esp->seqreg, esp->sreg2, esp->ireg);

      intr_done = 0;

      if (esp->ireg & (ESP_INTR_S | ESP_INTR_SATN | ESP_INTR_IC)) {
            printk("ESP: unexpected IREG %02x\n", esp->ireg);
            if (esp->ireg & ESP_INTR_IC)
                  esp_dump_cmd_log(esp);

            esp_schedule_reset(esp);
      } else {
            if (!(esp->ireg & ESP_INTR_RSEL)) {
                  /* Some combination of FDONE, BSERV, DC.  */
                  if (esp->select_state != ESP_SELECT_NONE)
                        intr_done = esp_finish_select(esp);
            } else if (esp->ireg & ESP_INTR_RSEL) {
                  if (esp->active_cmd)
                        (void) esp_finish_select(esp);
                  intr_done = esp_reconnect(esp);
            }
      }
      while (!intr_done)
            intr_done = esp_process_event(esp);
}

irqreturn_t scsi_esp_intr(int irq, void *dev_id)
{
      struct esp *esp = dev_id;
      unsigned long flags;
      irqreturn_t ret;

      spin_lock_irqsave(esp->host->host_lock, flags);
      ret = IRQ_NONE;
      if (esp->ops->irq_pending(esp)) {
            ret = IRQ_HANDLED;
            for (;;) {
                  int i;

                  __esp_interrupt(esp);
                  if (!(esp->flags & ESP_FLAG_QUICKIRQ_CHECK))
                        break;
                  esp->flags &= ~ESP_FLAG_QUICKIRQ_CHECK;

                  for (i = 0; i < ESP_QUICKIRQ_LIMIT; i++) {
                        if (esp->ops->irq_pending(esp))
                              break;
                  }
                  if (i == ESP_QUICKIRQ_LIMIT)
                        break;
            }
      }
      spin_unlock_irqrestore(esp->host->host_lock, flags);

      return ret;
}
EXPORT_SYMBOL(scsi_esp_intr);

static void esp_get_revision(struct esp *esp)
{
      u8 val;

      esp->config1 = (ESP_CONFIG1_PENABLE | (esp->scsi_id & 7));
      esp->config2 = (ESP_CONFIG2_SCSI2ENAB | ESP_CONFIG2_REGPARITY);
      esp_write8(esp->config2, ESP_CFG2);

      val = esp_read8(ESP_CFG2);
      val &= ~ESP_CONFIG2_MAGIC;
      if (val != (ESP_CONFIG2_SCSI2ENAB | ESP_CONFIG2_REGPARITY)) {
            /* If what we write to cfg2 does not come back, cfg2 is not
             * implemented, therefore this must be a plain esp100.
             */
            esp->rev = ESP100;
      } else {
            esp->config2 = 0;
            esp_set_all_config3(esp, 5);
            esp->prev_cfg3 = 5;
            esp_write8(esp->config2, ESP_CFG2);
            esp_write8(0, ESP_CFG3);
            esp_write8(esp->prev_cfg3, ESP_CFG3);

            val = esp_read8(ESP_CFG3);
            if (val != 5) {
                  /* The cfg2 register is implemented, however
                   * cfg3 is not, must be esp100a.
                   */
                  esp->rev = ESP100A;
            } else {
                  esp_set_all_config3(esp, 0);
                  esp->prev_cfg3 = 0;
                  esp_write8(esp->prev_cfg3, ESP_CFG3);

                  /* All of cfg{1,2,3} implemented, must be one of
                   * the fas variants, figure out which one.
                   */
                  if (esp->cfact == 0 || esp->cfact > ESP_CCF_F5) {
                        esp->rev = FAST;
                        esp->sync_defp = SYNC_DEFP_FAST;
                  } else {
                        esp->rev = ESP236;
                  }
                  esp->config2 = 0;
                  esp_write8(esp->config2, ESP_CFG2);
            }
      }
}

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

      INIT_LIST_HEAD(&esp->queued_cmds);
      INIT_LIST_HEAD(&esp->active_cmds);
      INIT_LIST_HEAD(&esp->esp_cmd_pool);

      /* Start with a clear state, domain validation (via ->slave_configure,
       * spi_dv_device()) will attempt to enable SYNC, WIDE, and tagged
       * commands.
       */
      for (i = 0 ; i < ESP_MAX_TARGET; i++) {
            esp->target[i].flags = 0;
            esp->target[i].nego_goal_period = 0;
            esp->target[i].nego_goal_offset = 0;
            esp->target[i].nego_goal_width = 0;
            esp->target[i].nego_goal_tags = 0;
      }
}

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

      /* Reset the DMA */
      esp->ops->reset_dma(esp);

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

      /* Reset the SCSI bus, but tell ESP not to generate an irq */
      val = esp_read8(ESP_CFG1);
      val |= ESP_CONFIG1_SRRDISAB;
      esp_write8(val, ESP_CFG1);

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

      esp_write8(esp->config1, ESP_CFG1);

      /* Eat any bitrot in the chip and we are done... */
      esp_read8(ESP_INTRPT);
}

static void esp_set_clock_params(struct esp *esp)
{
      int fmhz;
      u8 ccf;

      /* This is getting messy but it has to be done correctly or else
       * you get weird behavior all over the place.  We are trying to
       * basically figure out three pieces of information.
       *
       * a) Clock Conversion Factor
       *
       *    This is a representation of the input crystal clock frequency
       *    going into the ESP on this machine.  Any operation whose timing
       *    is longer than 400ns depends on this value being correct.  For
       *    example, you'll get blips for arbitration/selection during high
       *    load or with multiple targets if this is not set correctly.
       *
       * b) Selection Time-Out
       *
       *    The ESP isn't very bright and will arbitrate for the bus and try
       *    to select a target forever if you let it.  This value tells the
       *    ESP when it has taken too long to negotiate and that it should
       *    interrupt the CPU so we can see what happened.  The value is
       *    computed as follows (from NCR/Symbios chip docs).
       *
       *          (Time Out Period) *  (Input Clock)
       *    STO = ----------------------------------
       *          (8192) * (Clock Conversion Factor)
       *
       *    We use a time out period of 250ms (ESP_BUS_TIMEOUT).
       *
       * c) Imperical constants for synchronous offset and transfer period
         *    register values
       *
       *    This entails the smallest and largest sync period we could ever
       *    handle on this ESP.
       */
      fmhz = esp->cfreq;

      ccf = ((fmhz / 1000000) + 4) / 5;
      if (ccf == 1)
            ccf = 2;

      /* If we can't find anything reasonable, just assume 20MHZ.
       * This is the clock frequency of the older sun4c's where I've
       * been unable to find the clock-frequency PROM property.  All
       * other machines provide useful values it seems.
       */
      if (fmhz <= 5000000 || ccf < 1 || ccf > 8) {
            fmhz = 20000000;
            ccf = 4;
      }

      esp->cfact = (ccf == 8 ? 0 : ccf);
      esp->cfreq = fmhz;
      esp->ccycle = ESP_MHZ_TO_CYCLE(fmhz);
      esp->ctick = ESP_TICK(ccf, esp->ccycle);
      esp->neg_defp = ESP_NEG_DEFP(fmhz, ccf);
      esp->sync_defp = SYNC_DEFP_SLOW;
}

static const char *esp_chip_names[] = {
      "ESP100",
      "ESP100A",
      "ESP236",
      "FAS236",
      "FAS100A",
      "FAST",
      "FASHME",
};

static struct scsi_transport_template *esp_transport_template;

int scsi_esp_register(struct esp *esp, struct device *dev)
{
      static int instance;
      int err;

      esp->host->transportt = esp_transport_template;
      esp->host->max_lun = ESP_MAX_LUN;
      esp->host->cmd_per_lun = 2;
      esp->host->unique_id = instance;

      esp_set_clock_params(esp);

      esp_get_revision(esp);

      esp_init_swstate(esp);

      esp_bootup_reset(esp);

      printk(KERN_INFO PFX "esp%u, regs[%1p:%1p] irq[%u]\n",
             esp->host->unique_id, esp->regs, esp->dma_regs,
             esp->host->irq);
      printk(KERN_INFO PFX "esp%u is a %s, %u MHz (ccf=%u), SCSI ID %u\n",
             esp->host->unique_id, esp_chip_names[esp->rev],
             esp->cfreq / 1000000, esp->cfact, esp->scsi_id);

      /* Let the SCSI bus reset settle. */
      ssleep(esp_bus_reset_settle);

      err = scsi_add_host(esp->host, dev);
      if (err)
            return err;

      instance++;

      scsi_scan_host(esp->host);

      return 0;
}
EXPORT_SYMBOL(scsi_esp_register);

void scsi_esp_unregister(struct esp *esp)
{
      scsi_remove_host(esp->host);
}
EXPORT_SYMBOL(scsi_esp_unregister);

static int esp_slave_alloc(struct scsi_device *dev)
{
      struct esp *esp = shost_priv(dev->host);
      struct esp_target_data *tp = &esp->target[dev->id];
      struct esp_lun_data *lp;

      lp = kzalloc(sizeof(*lp), GFP_KERNEL);
      if (!lp)
            return -ENOMEM;
      dev->hostdata = lp;

      tp->starget = dev->sdev_target;

      spi_min_period(tp->starget) = esp->min_period;
      spi_max_offset(tp->starget) = 15;

      if (esp->flags & ESP_FLAG_WIDE_CAPABLE)
            spi_max_width(tp->starget) = 1;
      else
            spi_max_width(tp->starget) = 0;

      return 0;
}

static int esp_slave_configure(struct scsi_device *dev)
{
      struct esp *esp = shost_priv(dev->host);
      struct esp_target_data *tp = &esp->target[dev->id];
      int goal_tags, queue_depth;

      goal_tags = 0;

      if (dev->tagged_supported) {
            /* XXX make this configurable somehow XXX */
            goal_tags = ESP_DEFAULT_TAGS;

            if (goal_tags > ESP_MAX_TAG)
                  goal_tags = ESP_MAX_TAG;
      }

      queue_depth = goal_tags;
      if (queue_depth < dev->host->cmd_per_lun)
            queue_depth = dev->host->cmd_per_lun;

      if (goal_tags) {
            scsi_set_tag_type(dev, MSG_ORDERED_TAG);
            scsi_activate_tcq(dev, queue_depth);
      } else {
            scsi_deactivate_tcq(dev, queue_depth);
      }
      tp->flags |= ESP_TGT_DISCONNECT;

      if (!spi_initial_dv(dev->sdev_target))
            spi_dv_device(dev);

      return 0;
}

static void esp_slave_destroy(struct scsi_device *dev)
{
      struct esp_lun_data *lp = dev->hostdata;

      kfree(lp);
      dev->hostdata = NULL;
}

static int esp_eh_abort_handler(struct scsi_cmnd *cmd)
{
      struct esp *esp = shost_priv(cmd->device->host);
      struct esp_cmd_entry *ent, *tmp;
      struct completion eh_done;
      unsigned long flags;

      /* XXX This helps a lot with debugging but might be a bit
       * XXX much for the final driver.
       */
      spin_lock_irqsave(esp->host->host_lock, flags);
      printk(KERN_ERR PFX "esp%d: Aborting command [%p:%02x]\n",
             esp->host->unique_id, cmd, cmd->cmnd[0]);
      ent = esp->active_cmd;
      if (ent)
            printk(KERN_ERR PFX "esp%d: Current command [%p:%02x]\n",
                   esp->host->unique_id, ent->cmd, ent->cmd->cmnd[0]);
      list_for_each_entry(ent, &esp->queued_cmds, list) {
            printk(KERN_ERR PFX "esp%d: Queued command [%p:%02x]\n",
                   esp->host->unique_id, ent->cmd, ent->cmd->cmnd[0]);
      }
      list_for_each_entry(ent, &esp->active_cmds, list) {
            printk(KERN_ERR PFX "esp%d: Active command [%p:%02x]\n",
                   esp->host->unique_id, ent->cmd, ent->cmd->cmnd[0]);
      }
      esp_dump_cmd_log(esp);
      spin_unlock_irqrestore(esp->host->host_lock, flags);

      spin_lock_irqsave(esp->host->host_lock, flags);

      ent = NULL;
      list_for_each_entry(tmp, &esp->queued_cmds, list) {
            if (tmp->cmd == cmd) {
                  ent = tmp;
                  break;
            }
      }

      if (ent) {
            /* Easiest case, we didn't even issue the command
             * yet so it is trivial to abort.
             */
            list_del(&ent->list);

            cmd->result = DID_ABORT << 16;
            cmd->scsi_done(cmd);

            esp_put_ent(esp, ent);

            goto out_success;
      }

      init_completion(&eh_done);

      ent = esp->active_cmd;
      if (ent && ent->cmd == cmd) {
            /* Command is the currently active command on
             * the bus.  If we already have an output message
             * pending, no dice.
             */
            if (esp->msg_out_len)
                  goto out_failure;

            /* Send out an abort, encouraging the target to
             * go to MSGOUT phase by asserting ATN.
             */
            esp->msg_out[0] = ABORT_TASK_SET;
            esp->msg_out_len = 1;
            ent->eh_done = &eh_done;

            scsi_esp_cmd(esp, ESP_CMD_SATN);
      } else {
            /* The command is disconnected.  This is not easy to
             * abort.  For now we fail and let the scsi error
             * handling layer go try a scsi bus reset or host
             * reset.
             *
             * What we could do is put together a scsi command
             * solely for the purpose of sending an abort message
             * to the target.  Coming up with all the code to
             * cook up scsi commands, special case them everywhere,
             * etc. is for questionable gain and it would be better
             * if the generic scsi error handling layer could do at
             * least some of that for us.
             *
             * Anyways this is an area for potential future improvement
             * in this driver.
             */
            goto out_failure;
      }

      spin_unlock_irqrestore(esp->host->host_lock, flags);

      if (!wait_for_completion_timeout(&eh_done, 5 * HZ)) {
            spin_lock_irqsave(esp->host->host_lock, flags);
            ent->eh_done = NULL;
            spin_unlock_irqrestore(esp->host->host_lock, flags);

            return FAILED;
      }

      return SUCCESS;

out_success:
      spin_unlock_irqrestore(esp->host->host_lock, flags);
      return SUCCESS;

out_failure:
      /* XXX This might be a good location to set ESP_TGT_BROKEN
       * XXX since we know which target/lun in particular is
       * XXX causing trouble.
       */
      spin_unlock_irqrestore(esp->host->host_lock, flags);
      return FAILED;
}

static int esp_eh_bus_reset_handler(struct scsi_cmnd *cmd)
{
      struct esp *esp = shost_priv(cmd->device->host);
      struct completion eh_reset;
      unsigned long flags;

      init_completion(&eh_reset);

      spin_lock_irqsave(esp->host->host_lock, flags);

      esp->eh_reset = &eh_reset;

      /* XXX This is too simple... We should add lots of
       * XXX checks here so that if we find that the chip is
       * XXX very wedged we return failure immediately so
       * XXX that we can perform a full chip reset.
       */
      esp->flags |= ESP_FLAG_RESETTING;
      scsi_esp_cmd(esp, ESP_CMD_RS);

      spin_unlock_irqrestore(esp->host->host_lock, flags);

      ssleep(esp_bus_reset_settle);

      if (!wait_for_completion_timeout(&eh_reset, 5 * HZ)) {
            spin_lock_irqsave(esp->host->host_lock, flags);
            esp->eh_reset = NULL;
            spin_unlock_irqrestore(esp->host->host_lock, flags);

            return FAILED;
      }

      return SUCCESS;
}

/* All bets are off, reset the entire device.  */
static int esp_eh_host_reset_handler(struct scsi_cmnd *cmd)
{
      struct esp *esp = shost_priv(cmd->device->host);
      unsigned long flags;

      spin_lock_irqsave(esp->host->host_lock, flags);
      esp_bootup_reset(esp);
      esp_reset_cleanup(esp);
      spin_unlock_irqrestore(esp->host->host_lock, flags);

      ssleep(esp_bus_reset_settle);

      return SUCCESS;
}

static const char *esp_info(struct Scsi_Host *host)
{
      return "esp";
}

struct scsi_host_template scsi_esp_template = {
      .module                 = THIS_MODULE,
      .name             = "esp",
      .info             = esp_info,
      .queuecommand           = esp_queuecommand,
      .slave_alloc            = esp_slave_alloc,
      .slave_configure  = esp_slave_configure,
      .slave_destroy          = esp_slave_destroy,
      .eh_abort_handler = esp_eh_abort_handler,
      .eh_bus_reset_handler   = esp_eh_bus_reset_handler,
      .eh_host_reset_handler  = esp_eh_host_reset_handler,
      .can_queue        = 7,
      .this_id          = 7,
      .sg_tablesize           = SG_ALL,
      .use_clustering         = ENABLE_CLUSTERING,
      .max_sectors            = 0xffff,
      .skip_settle_delay      = 1,
};
EXPORT_SYMBOL(scsi_esp_template);

static void esp_get_signalling(struct Scsi_Host *host)
{
      struct esp *esp = shost_priv(host);
      enum spi_signal_type type;

      if (esp->flags & ESP_FLAG_DIFFERENTIAL)
            type = SPI_SIGNAL_HVD;
      else
            type = SPI_SIGNAL_SE;

      spi_signalling(host) = type;
}

static void esp_set_offset(struct scsi_target *target, int offset)
{
      struct Scsi_Host *host = dev_to_shost(target->dev.parent);
      struct esp *esp = shost_priv(host);
      struct esp_target_data *tp = &esp->target[target->id];

      tp->nego_goal_offset = offset;
      tp->flags |= ESP_TGT_CHECK_NEGO;
}

static void esp_set_period(struct scsi_target *target, int period)
{
      struct Scsi_Host *host = dev_to_shost(target->dev.parent);
      struct esp *esp = shost_priv(host);
      struct esp_target_data *tp = &esp->target[target->id];

      tp->nego_goal_period = period;
      tp->flags |= ESP_TGT_CHECK_NEGO;
}

static void esp_set_width(struct scsi_target *target, int width)
{
      struct Scsi_Host *host = dev_to_shost(target->dev.parent);
      struct esp *esp = shost_priv(host);
      struct esp_target_data *tp = &esp->target[target->id];

      tp->nego_goal_width = (width ? 1 : 0);
      tp->flags |= ESP_TGT_CHECK_NEGO;
}

static struct spi_function_template esp_transport_ops = {
      .set_offset       = esp_set_offset,
      .show_offset            = 1,
      .set_period       = esp_set_period,
      .show_period            = 1,
      .set_width        = esp_set_width,
      .show_width       = 1,
      .get_signalling         = esp_get_signalling,
};

static int __init esp_init(void)
{
      BUILD_BUG_ON(sizeof(struct scsi_pointer) <
                 sizeof(struct esp_cmd_priv));

      esp_transport_template = spi_attach_transport(&esp_transport_ops);
      if (!esp_transport_template)
            return -ENODEV;

      return 0;
}

static void __exit esp_exit(void)
{
      spi_release_transport(esp_transport_template);
}

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

module_param(esp_bus_reset_settle, int, 0);
MODULE_PARM_DESC(esp_bus_reset_settle,
             "ESP scsi bus reset delay in seconds");

module_param(esp_debug, int, 0);
MODULE_PARM_DESC(esp_debug,
"ESP bitmapped debugging message enable value:\n"
"     0x00000001  Log interrupt events\n"
"     0x00000002  Log scsi commands\n"
"     0x00000004  Log resets\n"
"     0x00000008  Log message in events\n"
"     0x00000010  Log message out events\n"
"     0x00000020  Log command completion\n"
"     0x00000040  Log disconnects\n"
"     0x00000080  Log data start\n"
"     0x00000100  Log data done\n"
"     0x00000200  Log reconnects\n"
"     0x00000400  Log auto-sense data\n"
);

module_init(esp_init);
module_exit(esp_exit);

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