// SPDX-License-Identifier: GPL-2.0-only
/* 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_DEBUG_EVENT         0x00000800
#define ESP_DEBUG_COMMAND       0x00001000

#define esp_log_intr(f, a...) \
do {    if (esp_debug & ESP_DEBUG_INTR) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_reset(f, a...) \
do {    if (esp_debug & ESP_DEBUG_RESET) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_msgin(f, a...) \
do {    if (esp_debug & ESP_DEBUG_MSGIN) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_msgout(f, a...) \
do {    if (esp_debug & ESP_DEBUG_MSGOUT) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_cmddone(f, a...) \
do {    if (esp_debug & ESP_DEBUG_CMDDONE) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_disconnect(f, a...) \
do {    if (esp_debug & ESP_DEBUG_DISCONNECT) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_datastart(f, a...) \
do {    if (esp_debug & ESP_DEBUG_DATASTART) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_datadone(f, a...) \
do {    if (esp_debug & ESP_DEBUG_DATADONE) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_reconnect(f, a...) \
do {    if (esp_debug & ESP_DEBUG_RECONNECT) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_autosense(f, a...) \
do {    if (esp_debug & ESP_DEBUG_AUTOSENSE) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_event(f, a...) \
do {   if (esp_debug & ESP_DEBUG_EVENT) \
                shost_printk(KERN_DEBUG, esp->host, f, ## a);   \
} while (0)

#define esp_log_command(f, a...) \
do {   if (esp_debug & ESP_DEBUG_COMMAND)       \
                shost_printk(KERN_DEBUG, esp->host, 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_log_command("cmd[%02x]\n", val);
        esp_write8(val, ESP_CMD);
}
EXPORT_SYMBOL(scsi_esp_cmd);

static void esp_send_dma_cmd(struct esp *esp, int len, int max_len, int cmd)
{
        if (esp->flags & ESP_FLAG_USE_FIFO) {
                int i;

                scsi_esp_cmd(esp, ESP_CMD_FLUSH);
                for (i = 0; i < len; i++)
                        esp_write8(esp->command_block[i], ESP_FDATA);
                scsi_esp_cmd(esp, cmd);
        } else {
                if (esp->rev == FASHME)
                        scsi_esp_cmd(esp, ESP_CMD_FLUSH);
                cmd |= ESP_CMD_DMA;
                esp->ops->send_dma_cmd(esp, esp->command_block_dma,
                                       len, max_len, 0, 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;

        shost_printk(KERN_INFO, esp->host, "Dumping command log\n");
        do {
                struct esp_event_ent *p = &esp->esp_event_log[idx];

                shost_printk(KERN_INFO, esp->host,
                             "ent[%d] %s val[%02x] sreg[%02x] seqreg[%02x] "
                             "sreg2[%02x] ireg[%02x] ss[%02x] event[%02x]\n",
                             idx,
                             p->type == ESP_EVENT_TYPE_CMD ? "CMD" : "EVENT",
                             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) {
                                shost_printk(KERN_ALERT, esp->host,
                                             "ESP_FF_BYTES will not clear!\n");
                                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)
{
        /* Now reset the ESP chip */
        scsi_esp_cmd(esp, ESP_CMD_RC);
        scsi_esp_cmd(esp, ESP_CMD_NULL | ESP_CMD_DMA);
        if (esp->rev == FAST)
                esp_write8(ESP_CONFIG2_FENAB, ESP_CFG2);
        scsi_esp_cmd(esp, ESP_CMD_NULL | ESP_CMD_DMA);

        /* 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) {
                u8 family_code = ESP_FAMILY(esp_read8(ESP_UID));

                if (family_code == ESP_UID_F236) {
                        esp->rev = FAS236;
                } else if (family_code == ESP_UID_HME) {
                        esp->rev = FASHME; /* Version is usually '5'. */
                } else if (family_code == ESP_UID_FSC) {
                        esp->rev = FSC;
                        /* Enable Active Negation */
                        esp_write8(ESP_CONFIG4_RADE, ESP_CFG4);
                } else {
                        esp->rev = FAS100A;
                }
                esp->min_period = ((4 * esp->ccycle) / 1000);
        } else {
                esp->min_period = ((5 * esp->ccycle) / 1000);
        }
        if (esp->rev == FAS236) {
                /*
                 * The AM53c974 chip returns the same ID as FAS236;
                 * try to configure glitch eater.
                 */
                u8 config4 = ESP_CONFIG4_GE1;
                esp_write8(config4, ESP_CFG4);
                config4 = esp_read8(ESP_CFG4);
                if (config4 & ESP_CONFIG4_GE1) {
                        esp->rev = PCSCSI;
                        esp_write8(esp->config4, ESP_CFG4);
                }
        }
        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:
        case PCSCSI:
        case FSC:
                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;
        }

        /* 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);

        /* 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 total = 0, i;
        struct scatterlist *s;

        if (cmd->sc_data_direction == DMA_NONE)
                return;

        if (esp->flags & ESP_FLAG_NO_DMA_MAP) {
                /*
                 * For pseudo DMA and PIO we need the virtual address instead of
                 * a dma address, so perform an identity mapping.
                 */
                spriv->num_sg = scsi_sg_count(cmd);

                scsi_for_each_sg(cmd, s, spriv->num_sg, i) {
                        s->dma_address = (uintptr_t)sg_virt(s);
                        total += sg_dma_len(s);
                }
        } else {
                spriv->num_sg = scsi_dma_map(cmd);
                scsi_for_each_sg(cmd, s, spriv->num_sg, i)
                        total += sg_dma_len(s);
        }
        spriv->cur_residue = sg_dma_len(sg);
        spriv->prv_sg = NULL;
        spriv->cur_sg = sg;
        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) {
                shost_printk(KERN_ERR, esp->host,
                             "Data transfer overflow.\n");
                shost_printk(KERN_ERR, esp->host,
                             "cur_residue[%d] tot_residue[%d] len[%u]\n",
                             p->cur_residue, p->tot_residue, len);
                p->cur_residue = 0;
                p->tot_residue = 0;
        }
        if (!p->cur_residue && p->tot_residue) {
                p->prv_sg = p->cur_sg;
                p->cur_sg = sg_next(p->cur_sg);
                p->cur_residue = sg_dma_len(p->cur_sg);
        }
}

static void esp_unmap_dma(struct esp *esp, struct scsi_cmnd *cmd)
{
        if (!(esp->flags & ESP_FLAG_NO_DMA_MAP))
                scsi_dma_unmap(cmd);
}

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_prv_sg = spriv->prv_sg;
        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->prv_sg = ent->saved_prv_sg;
        spriv->cur_sg = ent->saved_cur_sg;
        spriv->tot_residue = ent->saved_tot_residue;
}

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->orig_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;
        }

        /* Tagged command. Check that it isn't blocked by a non-tagged one. */
        if (lp->non_tagged_cmd || lp->hold)
                return -EBUSY;

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

        lp->tagged_cmds[ent->orig_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->orig_tag[0]) {
                BUG_ON(lp->tagged_cmds[ent->orig_tag[1]] != ent);
                lp->tagged_cmds[ent->orig_tag[1]] = NULL;
                lp->num_tagged--;
        } else {
                BUG_ON(lp->non_tagged_cmd != ent);
                lp->non_tagged_cmd = NULL;
        }
}

static void esp_map_sense(struct esp *esp, struct esp_cmd_entry *ent)
{
        ent->sense_ptr = ent->cmd->sense_buffer;
        if (esp->flags & ESP_FLAG_NO_DMA_MAP) {
                ent->sense_dma = (uintptr_t)ent->sense_ptr;
                return;
        }

        ent->sense_dma = dma_map_single(esp->dev, ent->sense_ptr,
                                        SCSI_SENSE_BUFFERSIZE, DMA_FROM_DEVICE);
}

static void esp_unmap_sense(struct esp *esp, struct esp_cmd_entry *ent)
{
        if (!(esp->flags & ESP_FLAG_NO_DMA_MAP))
                dma_unmap_single(esp->dev, ent->sense_dma,
                                 SCSI_SENSE_BUFFERSIZE, DMA_FROM_DEVICE);
        ent->sense_ptr = NULL;
}

/* When a contingent allegiance condition 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("Doing auto-sense for tgt[%d] lun[%d]\n",
                                  tgt, lun);
                esp_map_sense(esp, ent);
        }
        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);

        esp_send_dma_cmd(esp, val, 16, 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 (!spi_populate_tag_msg(&ent->tag[0], cmd)) {
                        ent->tag[0] = 0;
                        ent->tag[1] = 0;
                }
                ent->orig_tag[0] = ent->tag[0];
                ent->orig_tag[1] = ent->tag[1];

                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 scsi_device *dev;
        struct scsi_cmnd *cmd;
        struct esp_cmd_entry *ent;
        bool select_and_stop = false;
        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];

        list_move(&ent->list, &esp->active_cmds);

        esp->active_cmd = ent;

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

        if (!(cmd->cmd_len == 6 || cmd->cmd_len == 10 || cmd->cmd_len == 12))
                select_and_stop = true;

        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;
                }

                /* If there are multiple message bytes, use Select and Stop */
                if (esp->msg_out_len)
                        select_and_stop = true;
        }

build_identify:
        *p++ = IDENTIFY(tp->flags & ESP_TGT_DISCONNECT, lun);

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

        if (select_and_stop) {
                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_SELAS;
                esp->select_state = ESP_SELECT_MSGOUT;
        } else {
                start_cmd = ESP_CMD_SELA;
                if (ent->tag[0]) {
                        *p++ = ent->tag[0];
                        *p++ = ent->tag[1];

                        start_cmd = ESP_CMD_SA3;
                }

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

                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_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");
        }

        esp_send_dma_cmd(esp, val, 16, 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 char host_byte)
{
        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 = 0;
        set_host_byte(cmd, host_byte);
        if (host_byte == DID_OK)
                set_status_byte(cmd, ent->status);

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

        if (ent->flags & ESP_CMD_FLAG_AUTOSENSE) {
                esp_unmap_sense(esp, ent);

                /* Restore the message/status bytes to what we actually
                 * saw originally.  Also, report that we are providing
                 * the sense data.
                 */
                cmd->result = SAM_STAT_CHECK_CONDITION;

                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 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_lck(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->num_sg = 0;

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

        esp_maybe_execute_command(esp);

        return 0;
}

static DEF_SCSI_QCMD(esp_queuecommand)

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
                 */
                shost_printk(KERN_ERR, esp->host,
                             "Gross error sreg[%02x]\n", 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)) {
                        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)) {
                                shost_printk(KERN_ERR, esp->host,
                                             "Spurious irq, sreg=%02x.\n",
                                             esp->sreg);
                                return -1;
                        }

                        shost_printk(KERN_ERR, esp->host, "DMA error\n");

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

        return 0;
}

static void esp_schedule_reset(struct esp *esp)
{
        esp_log_reset("esp_schedule_reset() from %ps\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) {
                shost_printk(KERN_ERR, esp->host,
                             "Reconnect w/num_tagged==0\n");
                return NULL;
        }

        esp_log_reconnect("reconnect tag, ");

        for (i = 0; i < ESP_QUICKIRQ_LIMIT; i++) {
                if (esp->ops->irq_pending(esp))
                        break;
        }
        if (i == ESP_QUICKIRQ_LIMIT) {
                shost_printk(KERN_ERR, esp->host,
                             "Reconnect IRQ1 timeout\n");
                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) {
                shost_printk(KERN_ERR, esp->host,
                             "Reconnect, got disconnect.\n");
                return NULL;
        }

        if ((esp->sreg & ESP_STAT_PMASK) != ESP_MIP) {
                shost_printk(KERN_ERR, esp->host,
                             "Reconnect, not MIP sreg[%02x].\n", 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 message.  */
        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) {
                shost_printk(KERN_ERR, esp->host, "Reconnect IRQ2 timeout\n");
                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) {
                shost_printk(KERN_ERR, esp->host,
                             "Reconnect, bad tag type %02x.\n",
                             esp->command_block[0]);
                return NULL;
        }

        ent = lp->tagged_cmds[esp->command_block[1]];
        if (!ent) {
                shost_printk(KERN_ERR, esp->host,
                             "Reconnect, no entry for tag %02x.\n",
                             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) {
                shost_printk(KERN_ERR, esp->host,
                             "Reconnect, no lp tgt[%u] lun[%u]\n",
                             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;

        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;

        /* 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);
                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->cmd_bytes_ptr = NULL;
                        esp->cmd_bytes_left = 0;
                } else {
                        esp_unmap_sense(esp, ent);
                }

                /* Now that the state is unwound properly, put back onto
                 * the issue queue.  This command is no longer active.
                 */
                list_move(&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);
                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 Select And Stop 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;
        }

        shost_printk(KERN_INFO, esp->host,
                     "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;
                if (esp->rev == PCSCSI && (esp->config2 & ESP_CONFIG2_FENAB))
                        ecount |= ((unsigned int)esp_read8(ESP_TCHI)) << 16;
        }

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

        /*
         * The am53c974 has a DMA 'peculiarity'. The doc states:
         * In some odd byte conditions, one residual byte will
         * be left in the SCSI FIFO, and the FIFO Flags will
         * never count to '0 '. When this happens, the residual
         * byte should be retrieved via PIO following completion
         * of the BLAST operation.
         */
        if (fifo_cnt == 1 && ent->flags & ESP_CMD_FLAG_RESIDUAL) {
                size_t count = 1;
                size_t offset = bytes_sent;
                u8 bval = esp_read8(ESP_FDATA);

                if (ent->flags & ESP_CMD_FLAG_AUTOSENSE)
                        ent->sense_ptr[bytes_sent] = bval;
                else {
                        struct esp_cmd_priv *p = ESP_CMD_PRIV(cmd);
                        u8 *ptr;

                        ptr = scsi_kmap_atomic_sg(p->cur_sg, p->num_sg,
                                                  &offset, &count);
                        if (likely(ptr)) {
                                *(ptr + offset) = bval;
                                scsi_kunmap_atomic_sg(ptr);
                        }
                }
                bytes_sent += fifo_cnt;
                ent->flags &= ~ESP_CMD_FLAG_RESIDUAL;
        }
        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;
        }

        shost_printk(KERN_INFO, esp->host, "Unexpected MESSAGE REJECT\n");
        esp_schedule_reset(esp);
}

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 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;
                stp = DIV_ROUND_UP(period << 2, one_clock);
                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;
        }

        shost_printk(KERN_INFO, esp->host,
                     "Unexpected extended msg type %x\n", esp->msg_in[2]);

        esp->msg_out[0] = MESSAGE_REJECT;
        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 */
                shost_printk(KERN_INFO, esp->host,
                             "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->prv_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, i;

again:
        write = 0;
        esp_log_event("process event %d phase %x\n",
                      esp->event, esp->sreg & ESP_STAT_PMASK);
        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:
                        shost_printk(KERN_INFO, esp->host,
                                     "Unexpected phase, sreg=%02x\n",
                                     esp->sreg);
                        esp_schedule_reset(esp);
                        return 0;
                }
                goto again;

        case ESP_EVENT_DATA_IN:
                write = 1;
                fallthrough;

        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;

                if (esp->ops->dma_length_limit)
                        dma_len = esp->ops->dma_length_limit(esp, dma_addr,
                                                             dma_len);
                else
                        dma_len = esp_dma_length_limit(esp, dma_addr, dma_len);

                esp->data_dma_len = dma_len;

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

                esp_log_datastart("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)) {
                        shost_printk(KERN_INFO, esp->host,
                                     "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.
                         */
                        shost_printk(KERN_INFO, esp->host,
                                     "data done, not BSERV, resetting\n");
                        esp_schedule_reset(esp);
                        return 0;
                }

                bytes_sent = esp_data_bytes_sent(esp, ent, cmd);

                esp_log_datadone("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;
        }

        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) {
                        shost_printk(KERN_INFO, esp->host,
                                     "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("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, DID_OK);
                        }
                } else if (ent->message == DISCONNECT) {
                        esp_log_disconnect("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 {
                        shost_printk(KERN_INFO, esp->host,
                                     "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 if (esp->flags & ESP_FLAG_USE_FIFO) {
                                for (i = 0; i < esp->msg_out_len; i++)
                                        esp_write8(esp->msg_out[i], 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);

                        /* XXX if the chip went into disconnected mode,
                         * we can't run the phase state machine anyway.
                         */
                        if (!(esp->ireg & ESP_INTR_DC))
                                scsi_esp_cmd(esp, ESP_CMD_NULL);
                }

                esp->msg_out_len = 0;

                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("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);

                        /* Check whether a bus reset is to be done next */
                        if (esp->event == ESP_EVENT_RESET)
                                return 0;

                        if (esp->event != ESP_EVENT_FREE_BUS)
                                esp_event(esp, ESP_EVENT_CHECK_PHASE);
                } else {
                        shost_printk(KERN_INFO, esp->host,
                                     "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);
                esp_send_dma_cmd(esp, esp->cmd_bytes_left, 16, 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;

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

        default:
                shost_printk(KERN_INFO, esp->host,
                             "Unexpected event %x, resetting\n", esp->event);
                esp_schedule_reset(esp);
                return 0;
        }
        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_unmap_sense(esp, ent);

        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;

       /*
        * Once INTRPT is read STATUS and SSTEP are cleared.
        */
        esp->sreg = esp_read8(ESP_STATUS);
        esp->seqreg = esp_read8(ESP_SSTEP);
        esp->ireg = esp_read8(ESP_INTRPT);

        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;
        }

        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("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)) {
                shost_printk(KERN_INFO, esp->host,
                             "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) {
                        if (esp->active_cmd)
                                (void) esp_finish_select(esp);
                        intr_done = esp_reconnect(esp);
                } else {
                        /* Some combination of FDONE, BSERV, DC. */
                        if (esp->select_state != ESP_SELECT_NONE)
                                intr_done = esp_finish_select(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));
        if (esp->config2 == 0) {
                esp->config2 = (ESP_CONFIG2_SCSI2ENAB | ESP_CONFIG2_REGPARITY);
                esp_write8(esp->config2, ESP_CFG2);

                val = esp_read8(ESP_CFG2);
                val &= ~ESP_CONFIG2_MAGIC;

                esp->config2 = 0;
                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;
                        return;
                }
        }

        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;
                }
        }
}

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 fhz;
        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.
         */
        fhz = esp->cfreq;

        ccf = ((fhz / 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 (fhz <= 5000000 || ccf < 1 || ccf > 8) {
                fhz = 20000000;
                ccf = 4;
        }

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

static const char *esp_chip_names[] = {
        "ESP100",
        "ESP100A",
        "ESP236",
        "FAS236",
        "AM53C974",
        "53CF9x-2",
        "FAS100A",
        "FAST",
        "FASHME",
};

static struct scsi_transport_template *esp_transport_template;

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

        if (!esp->num_tags)
                esp->num_tags = ESP_DEFAULT_TAGS;
        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);

        dev_printk(KERN_INFO, esp->dev, "esp%u: regs[%1p:%1p] irq[%u]\n",
                   esp->host->unique_id, esp->regs, esp->dma_regs,
                   esp->host->irq);
        dev_printk(KERN_INFO, esp->dev,
                   "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, esp->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_target_alloc(struct scsi_target *starget)
{
        struct esp *esp = shost_priv(dev_to_shost(&starget->dev));
        struct esp_target_data *tp = &esp->target[starget->id];

        tp->starget = starget;

        return 0;
}

static void esp_target_destroy(struct scsi_target *starget)
{
        struct esp *esp = shost_priv(dev_to_shost(&starget->dev));
        struct esp_target_data *tp = &esp->target[starget->id];

        tp->starget = NULL;
}

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;

        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];

        if (dev->tagged_supported)
                scsi_change_queue_depth(dev, esp->num_tags);

        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);
        shost_printk(KERN_ERR, esp->host, "Aborting command [%p:%02x]\n",
                     cmd, cmd->cmnd[0]);
        ent = esp->active_cmd;
        if (ent)
                shost_printk(KERN_ERR, esp->host,
                             "Current command [%p:%02x]\n",
                             ent->cmd, ent->cmd->cmnd[0]);
        list_for_each_entry(ent, &esp->queued_cmds, list) {
                shost_printk(KERN_ERR, esp->host, "Queued command [%p:%02x]\n",
                             ent->cmd, ent->cmd->cmnd[0]);
        }
        list_for_each_entry(ent, &esp->active_cmds, list) {
                shost_printk(KERN_ERR, esp->host, " Active command [%p:%02x]\n",
                             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,
        .target_alloc           = esp_target_alloc,
        .target_destroy         = esp_target_destroy,
        .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,
        .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];

        if (esp->flags & ESP_FLAG_DISABLE_SYNC)
                tp->nego_goal_offset = 0;
        else
                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);

#ifdef CONFIG_SCSI_ESP_PIO
static inline unsigned int esp_wait_for_fifo(struct esp *esp)
{
        int i = 500000;

        do {
                unsigned int fbytes = esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES;

                if (fbytes)
                        return fbytes;

                udelay(1);
        } while (--i);

        shost_printk(KERN_ERR, esp->host, "FIFO is empty. sreg [%02x]\n",
                     esp_read8(ESP_STATUS));
        return 0;
}

static inline int esp_wait_for_intr(struct esp *esp)
{
        int i = 500000;

        do {
                esp->sreg = esp_read8(ESP_STATUS);
                if (esp->sreg & ESP_STAT_INTR)
                        return 0;

                udelay(1);
        } while (--i);

        shost_printk(KERN_ERR, esp->host, "IRQ timeout. sreg [%02x]\n",
                     esp->sreg);
        return 1;
}

#define ESP_FIFO_SIZE 16

void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
                      u32 dma_count, int write, u8 cmd)
{
        u8 phase = esp->sreg & ESP_STAT_PMASK;

        cmd &= ~ESP_CMD_DMA;
        esp->send_cmd_error = 0;

        if (write) {
                u8 *dst = (u8 *)addr;
                u8 mask = ~(phase == ESP_MIP ? ESP_INTR_FDONE : ESP_INTR_BSERV);

                scsi_esp_cmd(esp, cmd);

                while (1) {
                        if (!esp_wait_for_fifo(esp))
                                break;

                        *dst++ = readb(esp->fifo_reg);
                        --esp_count;

                        if (!esp_count)
                                break;

                        if (esp_wait_for_intr(esp)) {
                                esp->send_cmd_error = 1;
                                break;
                        }

                        if ((esp->sreg & ESP_STAT_PMASK) != phase)
                                break;

                        esp->ireg = esp_read8(ESP_INTRPT);
                        if (esp->ireg & mask) {
                                esp->send_cmd_error = 1;
                                break;
                        }

                        if (phase == ESP_MIP)
                                esp_write8(ESP_CMD_MOK, ESP_CMD);

                        esp_write8(ESP_CMD_TI, ESP_CMD);
                }
        } else {
                unsigned int n = ESP_FIFO_SIZE;
                u8 *src = (u8 *)addr;

                scsi_esp_cmd(esp, ESP_CMD_FLUSH);

                if (n > esp_count)
                        n = esp_count;
                writesb(esp->fifo_reg, src, n);
                src += n;
                esp_count -= n;

                scsi_esp_cmd(esp, cmd);

                while (esp_count) {
                        if (esp_wait_for_intr(esp)) {
                                esp->send_cmd_error = 1;
                                break;
                        }

                        if ((esp->sreg & ESP_STAT_PMASK) != phase)
                                break;

                        esp->ireg = esp_read8(ESP_INTRPT);
                        if (esp->ireg & ~ESP_INTR_BSERV) {
                                esp->send_cmd_error = 1;
                                break;
                        }

                        n = ESP_FIFO_SIZE -
                            (esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES);

                        if (n > esp_count)
                                n = esp_count;
                        writesb(esp->fifo_reg, src, n);
                        src += n;
                        esp_count -= n;

                        esp_write8(ESP_CMD_TI, ESP_CMD);
                }
        }

        esp->send_cmd_residual = esp_count;
}
EXPORT_SYMBOL(esp_send_pio_cmd);
#endif