/* 
 *  Parallel SCSI (SPI) transport specific attributes exported to sysfs.
 *
 *  Copyright (c) 2003 Silicon Graphics, Inc.  All rights reserved.
 *  Copyright (c) 2004, 2005 James Bottomley <James.Bottomley@SteelEye.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/workqueue.h>
#include <linux/blkdev.h>
#include <linux/mutex.h>
#include <linux/sysfs.h>
#include <linux/slab.h>
#include <linux/suspend.h>
#include <scsi/scsi.h>
#include "scsi_priv.h"
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_spi.h>

#define SPI_NUM_ATTRS 14        /* increase this if you add attributes */
#define SPI_OTHER_ATTRS 1       /* Increase this if you add "always
                                 * on" attributes */
#define SPI_HOST_ATTRS  1

#define SPI_MAX_ECHO_BUFFER_SIZE        4096

#define DV_LOOPS        3
#define DV_TIMEOUT      (10*HZ)
#define DV_RETRIES      3       /* should only need at most 
                                 * two cc/ua clears */

/* Our blacklist flags */
enum {
        SPI_BLIST_NOIUS = (__force blist_flags_t)0x1,
};

/* blacklist table, modelled on scsi_devinfo.c */
static struct {
        char *vendor;
        char *model;
        blist_flags_t flags;
} spi_static_device_list[] __initdata = {
        {"HP", "Ultrium 3-SCSI", SPI_BLIST_NOIUS },
        {"IBM", "ULTRIUM-TD3", SPI_BLIST_NOIUS },
        {NULL, NULL, 0}
};

/* Private data accessors (keep these out of the header file) */
#define spi_dv_in_progress(x) (((struct spi_transport_attrs *)&(x)->starget_data)->dv_in_progress)
#define spi_dv_mutex(x) (((struct spi_transport_attrs *)&(x)->starget_data)->dv_mutex)

struct spi_internal {
        struct scsi_transport_template t;
        struct spi_function_template *f;
};

#define to_spi_internal(tmpl)   container_of(tmpl, struct spi_internal, t)

static const int ppr_to_ps[] = {
        /* The PPR values 0-6 are reserved, fill them in when
         * the committee defines them */
        -1,                     /* 0x00 */
        -1,                     /* 0x01 */
        -1,                     /* 0x02 */
        -1,                     /* 0x03 */
        -1,                     /* 0x04 */
        -1,                     /* 0x05 */
        -1,                     /* 0x06 */
         3125,                  /* 0x07 */
         6250,                  /* 0x08 */
        12500,                  /* 0x09 */
        25000,                  /* 0x0a */
        30300,                  /* 0x0b */
        50000,                  /* 0x0c */
};
/* The PPR values at which you calculate the period in ns by multiplying
 * by 4 */
#define SPI_STATIC_PPR  0x0c

static int sprint_frac(char *dest, int value, int denom)
{
        int frac = value % denom;
        int result = sprintf(dest, "%d", value / denom);

        if (frac == 0)
                return result;
        dest[result++] = '.';

        do {
                denom /= 10;
                sprintf(dest + result, "%d", frac / denom);
                result++;
                frac %= denom;
        } while (frac);

        dest[result++] = '\0';
        return result;
}

static int spi_execute(struct scsi_device *sdev, const void *cmd,
                       enum dma_data_direction dir,
                       void *buffer, unsigned bufflen,
                       struct scsi_sense_hdr *sshdr)
{
        int i, result;
        unsigned char sense[SCSI_SENSE_BUFFERSIZE];
        struct scsi_sense_hdr sshdr_tmp;

        if (!sshdr)
                sshdr = &sshdr_tmp;

        for(i = 0; i < DV_RETRIES; i++) {
                result = scsi_execute(sdev, cmd, dir, buffer, bufflen, sense,
                                      sshdr, DV_TIMEOUT, /* retries */ 1,
                                      REQ_FAILFAST_DEV |
                                      REQ_FAILFAST_TRANSPORT |
                                      REQ_FAILFAST_DRIVER,
                                      0, NULL);
                if (!(driver_byte(result) & DRIVER_SENSE) ||
                    sshdr->sense_key != UNIT_ATTENTION)
                        break;
        }
        return result;
}

static struct {
        enum spi_signal_type    value;
        char                    *name;
} signal_types[] = {
        { SPI_SIGNAL_UNKNOWN, "unknown" },
        { SPI_SIGNAL_SE, "SE" },
        { SPI_SIGNAL_LVD, "LVD" },
        { SPI_SIGNAL_HVD, "HVD" },
};

static inline const char *spi_signal_to_string(enum spi_signal_type type)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(signal_types); i++) {
                if (type == signal_types[i].value)
                        return signal_types[i].name;
        }
        return NULL;
}
static inline enum spi_signal_type spi_signal_to_value(const char *name)
{
        int i, len;

        for (i = 0; i < ARRAY_SIZE(signal_types); i++) {
                len =  strlen(signal_types[i].name);
                if (strncmp(name, signal_types[i].name, len) == 0 &&
                    (name[len] == '\n' || name[len] == '\0'))
                        return signal_types[i].value;
        }
        return SPI_SIGNAL_UNKNOWN;
}

static int spi_host_setup(struct transport_container *tc, struct device *dev,
                          struct device *cdev)
{
        struct Scsi_Host *shost = dev_to_shost(dev);

        spi_signalling(shost) = SPI_SIGNAL_UNKNOWN;

        return 0;
}

static int spi_host_configure(struct transport_container *tc,
                              struct device *dev,
                              struct device *cdev);

static DECLARE_TRANSPORT_CLASS(spi_host_class,
                               "spi_host",
                               spi_host_setup,
                               NULL,
                               spi_host_configure);

static int spi_host_match(struct attribute_container *cont,
                          struct device *dev)
{
        struct Scsi_Host *shost;

        if (!scsi_is_host_device(dev))
                return 0;

        shost = dev_to_shost(dev);
        if (!shost->transportt  || shost->transportt->host_attrs.ac.class
            != &spi_host_class.class)
                return 0;

        return &shost->transportt->host_attrs.ac == cont;
}

static int spi_target_configure(struct transport_container *tc,
                                struct device *dev,
                                struct device *cdev);

static int spi_device_configure(struct transport_container *tc,
                                struct device *dev,
                                struct device *cdev)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        struct scsi_target *starget = sdev->sdev_target;
        blist_flags_t bflags;

        bflags = scsi_get_device_flags_keyed(sdev, &sdev->inquiry[8],
                                             &sdev->inquiry[16],
                                             SCSI_DEVINFO_SPI);

        /* Populate the target capability fields with the values
         * gleaned from the device inquiry */

        spi_support_sync(starget) = scsi_device_sync(sdev);
        spi_support_wide(starget) = scsi_device_wide(sdev);
        spi_support_dt(starget) = scsi_device_dt(sdev);
        spi_support_dt_only(starget) = scsi_device_dt_only(sdev);
        spi_support_ius(starget) = scsi_device_ius(sdev);
        if (bflags & SPI_BLIST_NOIUS) {
                dev_info(dev, "Information Units disabled by blacklist\n");
                spi_support_ius(starget) = 0;
        }
        spi_support_qas(starget) = scsi_device_qas(sdev);

        return 0;
}

static int spi_setup_transport_attrs(struct transport_container *tc,
                                     struct device *dev,
                                     struct device *cdev)
{
        struct scsi_target *starget = to_scsi_target(dev);

        spi_period(starget) = -1;       /* illegal value */
        spi_min_period(starget) = 0;
        spi_offset(starget) = 0;        /* async */
        spi_max_offset(starget) = 255;
        spi_width(starget) = 0; /* narrow */
        spi_max_width(starget) = 1;
        spi_iu(starget) = 0;    /* no IU */
        spi_max_iu(starget) = 1;
        spi_dt(starget) = 0;    /* ST */
        spi_qas(starget) = 0;
        spi_max_qas(starget) = 1;
        spi_wr_flow(starget) = 0;
        spi_rd_strm(starget) = 0;
        spi_rti(starget) = 0;
        spi_pcomp_en(starget) = 0;
        spi_hold_mcs(starget) = 0;
        spi_dv_pending(starget) = 0;
        spi_dv_in_progress(starget) = 0;
        spi_initial_dv(starget) = 0;
        mutex_init(&spi_dv_mutex(starget));

        return 0;
}

#define spi_transport_show_simple(field, format_string)                 \
                                                                        \
static ssize_t                                                          \
show_spi_transport_##field(struct device *dev,                  \
                           struct device_attribute *attr, char *buf)    \
{                                                                       \
        struct scsi_target *starget = transport_class_to_starget(dev);  \
        struct spi_transport_attrs *tp;                                 \
                                                                        \
        tp = (struct spi_transport_attrs *)&starget->starget_data;      \
        return snprintf(buf, 20, format_string, tp->field);             \
}

#define spi_transport_store_simple(field, format_string)                \
                                                                        \
static ssize_t                                                          \
store_spi_transport_##field(struct device *dev,                         \
                            struct device_attribute *attr,              \
                            const char *buf, size_t count)              \
{                                                                       \
        int val;                                                        \
        struct scsi_target *starget = transport_class_to_starget(dev);  \
        struct spi_transport_attrs *tp;                                 \
                                                                        \
        tp = (struct spi_transport_attrs *)&starget->starget_data;      \
        val = simple_strtoul(buf, NULL, 0);                             \
        tp->field = val;                                                \
        return count;                                                   \
}

#define spi_transport_show_function(field, format_string)               \
                                                                        \
static ssize_t                                                          \
show_spi_transport_##field(struct device *dev,                  \
                           struct device_attribute *attr, char *buf)    \
{                                                                       \
        struct scsi_target *starget = transport_class_to_starget(dev);  \
        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);    \
        struct spi_transport_attrs *tp;                                 \
        struct spi_internal *i = to_spi_internal(shost->transportt);    \
        tp = (struct spi_transport_attrs *)&starget->starget_data;      \
        if (i->f->get_##field)                                          \
                i->f->get_##field(starget);                             \
        return snprintf(buf, 20, format_string, tp->field);             \
}

#define spi_transport_store_function(field, format_string)              \
static ssize_t                                                          \
store_spi_transport_##field(struct device *dev,                         \
                            struct device_attribute *attr,              \
                            const char *buf, size_t count)              \
{                                                                       \
        int val;                                                        \
        struct scsi_target *starget = transport_class_to_starget(dev);  \
        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);    \
        struct spi_internal *i = to_spi_internal(shost->transportt);    \
                                                                        \
        if (!i->f->set_##field)                                         \
                return -EINVAL;                                         \
        val = simple_strtoul(buf, NULL, 0);                             \
        i->f->set_##field(starget, val);                                \
        return count;                                                   \
}

#define spi_transport_store_max(field, format_string)                   \
static ssize_t                                                          \
store_spi_transport_##field(struct device *dev,                         \
                            struct device_attribute *attr,              \
                            const char *buf, size_t count)              \
{                                                                       \
        int val;                                                        \
        struct scsi_target *starget = transport_class_to_starget(dev);  \
        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);    \
        struct spi_internal *i = to_spi_internal(shost->transportt);    \
        struct spi_transport_attrs *tp                                  \
                = (struct spi_transport_attrs *)&starget->starget_data; \
                                                                        \
        if (i->f->set_##field)                                          \
                return -EINVAL;                                         \
        val = simple_strtoul(buf, NULL, 0);                             \
        if (val > tp->max_##field)                                      \
                val = tp->max_##field;                                  \
        i->f->set_##field(starget, val);                                \
        return count;                                                   \
}

#define spi_transport_rd_attr(field, format_string)                     \
        spi_transport_show_function(field, format_string)               \
        spi_transport_store_function(field, format_string)              \
static DEVICE_ATTR(field, S_IRUGO,                              \
                   show_spi_transport_##field,                  \
                   store_spi_transport_##field);

#define spi_transport_simple_attr(field, format_string)                 \
        spi_transport_show_simple(field, format_string)                 \
        spi_transport_store_simple(field, format_string)                \
static DEVICE_ATTR(field, S_IRUGO,                              \
                   show_spi_transport_##field,                  \
                   store_spi_transport_##field);

#define spi_transport_max_attr(field, format_string)                    \
        spi_transport_show_function(field, format_string)               \
        spi_transport_store_max(field, format_string)                   \
        spi_transport_simple_attr(max_##field, format_string)           \
static DEVICE_ATTR(field, S_IRUGO,                              \
                   show_spi_transport_##field,                  \
                   store_spi_transport_##field);

/* The Parallel SCSI Tranport Attributes: */
spi_transport_max_attr(offset, "%d\n");
spi_transport_max_attr(width, "%d\n");
spi_transport_max_attr(iu, "%d\n");
spi_transport_rd_attr(dt, "%d\n");
spi_transport_max_attr(qas, "%d\n");
spi_transport_rd_attr(wr_flow, "%d\n");
spi_transport_rd_attr(rd_strm, "%d\n");
spi_transport_rd_attr(rti, "%d\n");
spi_transport_rd_attr(pcomp_en, "%d\n");
spi_transport_rd_attr(hold_mcs, "%d\n");

/* we only care about the first child device that's a real SCSI device
 * so we return 1 to terminate the iteration when we find it */
static int child_iter(struct device *dev, void *data)
{
        if (!scsi_is_sdev_device(dev))
                return 0;

        spi_dv_device(to_scsi_device(dev));
        return 1;
}

static ssize_t
store_spi_revalidate(struct device *dev, struct device_attribute *attr,
                     const char *buf, size_t count)
{
        struct scsi_target *starget = transport_class_to_starget(dev);

        device_for_each_child(&starget->dev, NULL, child_iter);
        return count;
}
static DEVICE_ATTR(revalidate, S_IWUSR, NULL, store_spi_revalidate);

/* Translate the period into ns according to the current spec
 * for SDTR/PPR messages */
static int period_to_str(char *buf, int period)
{
        int len, picosec;

        if (period < 0 || period > 0xff) {
                picosec = -1;
        } else if (period <= SPI_STATIC_PPR) {
                picosec = ppr_to_ps[period];
        } else {
                picosec = period * 4000;
        }

        if (picosec == -1) {
                len = sprintf(buf, "reserved");
        } else {
                len = sprint_frac(buf, picosec, 1000);
        }

        return len;
}

static ssize_t
show_spi_transport_period_helper(char *buf, int period)
{
        int len = period_to_str(buf, period);
        buf[len++] = '\n';
        buf[len] = '\0';
        return len;
}

static ssize_t
store_spi_transport_period_helper(struct device *dev, const char *buf,
                                  size_t count, int *periodp)
{
        int j, picosec, period = -1;
        char *endp;

        picosec = simple_strtoul(buf, &endp, 10) * 1000;
        if (*endp == '.') {
                int mult = 100;
                do {
                        endp++;
                        if (!isdigit(*endp))
                                break;
                        picosec += (*endp - '0') * mult;
                        mult /= 10;
                } while (mult > 0);
        }

        for (j = 0; j <= SPI_STATIC_PPR; j++) {
                if (ppr_to_ps[j] < picosec)
                        continue;
                period = j;
                break;
        }

        if (period == -1)
                period = picosec / 4000;

        if (period > 0xff)
                period = 0xff;

        *periodp = period;

        return count;
}

static ssize_t
show_spi_transport_period(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        struct scsi_target *starget = transport_class_to_starget(dev);
        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
        struct spi_internal *i = to_spi_internal(shost->transportt);
        struct spi_transport_attrs *tp =
                (struct spi_transport_attrs *)&starget->starget_data;

        if (i->f->get_period)
                i->f->get_period(starget);

        return show_spi_transport_period_helper(buf, tp->period);
}

static ssize_t
store_spi_transport_period(struct device *cdev, struct device_attribute *attr,
                           const char *buf, size_t count)
{
        struct scsi_target *starget = transport_class_to_starget(cdev);
        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
        struct spi_internal *i = to_spi_internal(shost->transportt);
        struct spi_transport_attrs *tp =
                (struct spi_transport_attrs *)&starget->starget_data;
        int period, retval;

        if (!i->f->set_period)
                return -EINVAL;

        retval = store_spi_transport_period_helper(cdev, buf, count, &period);

        if (period < tp->min_period)
                period = tp->min_period;

        i->f->set_period(starget, period);

        return retval;
}

static DEVICE_ATTR(period, S_IRUGO,
                   show_spi_transport_period,
                   store_spi_transport_period);

static ssize_t
show_spi_transport_min_period(struct device *cdev,
                              struct device_attribute *attr, char *buf)
{
        struct scsi_target *starget = transport_class_to_starget(cdev);
        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
        struct spi_internal *i = to_spi_internal(shost->transportt);
        struct spi_transport_attrs *tp =
                (struct spi_transport_attrs *)&starget->starget_data;

        if (!i->f->set_period)
                return -EINVAL;

        return show_spi_transport_period_helper(buf, tp->min_period);
}

static ssize_t
store_spi_transport_min_period(struct device *cdev,
                               struct device_attribute *attr,
                               const char *buf, size_t count)
{
        struct scsi_target *starget = transport_class_to_starget(cdev);
        struct spi_transport_attrs *tp =
                (struct spi_transport_attrs *)&starget->starget_data;

        return store_spi_transport_period_helper(cdev, buf, count,
                                                 &tp->min_period);
}


static DEVICE_ATTR(min_period, S_IRUGO,
                   show_spi_transport_min_period,
                   store_spi_transport_min_period);


static ssize_t show_spi_host_signalling(struct device *cdev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct Scsi_Host *shost = transport_class_to_shost(cdev);
        struct spi_internal *i = to_spi_internal(shost->transportt);

        if (i->f->get_signalling)
                i->f->get_signalling(shost);

        return sprintf(buf, "%s\n", spi_signal_to_string(spi_signalling(shost)));
}
static ssize_t store_spi_host_signalling(struct device *dev,
                                         struct device_attribute *attr,
                                         const char *buf, size_t count)
{
        struct Scsi_Host *shost = transport_class_to_shost(dev);
        struct spi_internal *i = to_spi_internal(shost->transportt);
        enum spi_signal_type type = spi_signal_to_value(buf);

        if (!i->f->set_signalling)
                return -EINVAL;

        if (type != SPI_SIGNAL_UNKNOWN)
                i->f->set_signalling(shost, type);

        return count;
}
static DEVICE_ATTR(signalling, S_IRUGO,
                   show_spi_host_signalling,
                   store_spi_host_signalling);

static ssize_t show_spi_host_width(struct device *cdev,
                                      struct device_attribute *attr,
                                      char *buf)
{
        struct Scsi_Host *shost = transport_class_to_shost(cdev);

        return sprintf(buf, "%s\n", shost->max_id == 16 ? "wide" : "narrow");
}
static DEVICE_ATTR(host_width, S_IRUGO,
                   show_spi_host_width, NULL);

static ssize_t show_spi_host_hba_id(struct device *cdev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct Scsi_Host *shost = transport_class_to_shost(cdev);

        return sprintf(buf, "%d\n", shost->this_id);
}
static DEVICE_ATTR(hba_id, S_IRUGO,
                   show_spi_host_hba_id, NULL);

#define DV_SET(x, y)                    \
        if(i->f->set_##x)               \
                i->f->set_##x(sdev->sdev_target, y)

enum spi_compare_returns {
        SPI_COMPARE_SUCCESS,
        SPI_COMPARE_FAILURE,
        SPI_COMPARE_SKIP_TEST,
};


/* This is for read/write Domain Validation:  If the device supports
 * an echo buffer, we do read/write tests to it */
static enum spi_compare_returns
spi_dv_device_echo_buffer(struct scsi_device *sdev, u8 *buffer,
                          u8 *ptr, const int retries)
{
        int len = ptr - buffer;
        int j, k, r, result;
        unsigned int pattern = 0x0000ffff;
        struct scsi_sense_hdr sshdr;

        const char spi_write_buffer[] = {
                WRITE_BUFFER, 0x0a, 0, 0, 0, 0, 0, len >> 8, len & 0xff, 0
        };
        const char spi_read_buffer[] = {
                READ_BUFFER, 0x0a, 0, 0, 0, 0, 0, len >> 8, len & 0xff, 0
        };

        /* set up the pattern buffer.  Doesn't matter if we spill
         * slightly beyond since that's where the read buffer is */
        for (j = 0; j < len; ) {

                /* fill the buffer with counting (test a) */
                for ( ; j < min(len, 32); j++)
                        buffer[j] = j;
                k = j;
                /* fill the buffer with alternating words of 0x0 and
                 * 0xffff (test b) */
                for ( ; j < min(len, k + 32); j += 2) {
                        u16 *word = (u16 *)&buffer[j];
                        
                        *word = (j & 0x02) ? 0x0000 : 0xffff;
                }
                k = j;
                /* fill with crosstalk (alternating 0x5555 0xaaa)
                 * (test c) */
                for ( ; j < min(len, k + 32); j += 2) {
                        u16 *word = (u16 *)&buffer[j];

                        *word = (j & 0x02) ? 0x5555 : 0xaaaa;
                }
                k = j;
                /* fill with shifting bits (test d) */
                for ( ; j < min(len, k + 32); j += 4) {
                        u32 *word = (unsigned int *)&buffer[j];
                        u32 roll = (pattern & 0x80000000) ? 1 : 0;
                        
                        *word = pattern;
                        pattern = (pattern << 1) | roll;
                }
                /* don't bother with random data (test e) */
        }

        for (r = 0; r < retries; r++) {
                result = spi_execute(sdev, spi_write_buffer, DMA_TO_DEVICE,
                                     buffer, len, &sshdr);
                if(result || !scsi_device_online(sdev)) {

                        scsi_device_set_state(sdev, SDEV_QUIESCE);
                        if (scsi_sense_valid(&sshdr)
                            && sshdr.sense_key == ILLEGAL_REQUEST
                            /* INVALID FIELD IN CDB */
                            && sshdr.asc == 0x24 && sshdr.ascq == 0x00)
                                /* This would mean that the drive lied
                                 * to us about supporting an echo
                                 * buffer (unfortunately some Western
                                 * Digital drives do precisely this)
                                 */
                                return SPI_COMPARE_SKIP_TEST;


                        sdev_printk(KERN_ERR, sdev, "Write Buffer failure %x\n", result);
                        return SPI_COMPARE_FAILURE;
                }

                memset(ptr, 0, len);
                spi_execute(sdev, spi_read_buffer, DMA_FROM_DEVICE,
                            ptr, len, NULL);
                scsi_device_set_state(sdev, SDEV_QUIESCE);

                if (memcmp(buffer, ptr, len) != 0)
                        return SPI_COMPARE_FAILURE;
        }
        return SPI_COMPARE_SUCCESS;
}

/* This is for the simplest form of Domain Validation: a read test
 * on the inquiry data from the device */
static enum spi_compare_returns
spi_dv_device_compare_inquiry(struct scsi_device *sdev, u8 *buffer,
                              u8 *ptr, const int retries)
{
        int r, result;
        const int len = sdev->inquiry_len;
        const char spi_inquiry[] = {
                INQUIRY, 0, 0, 0, len, 0
        };

        for (r = 0; r < retries; r++) {
                memset(ptr, 0, len);

                result = spi_execute(sdev, spi_inquiry, DMA_FROM_DEVICE,
                                     ptr, len, NULL);
                
                if(result || !scsi_device_online(sdev)) {
                        scsi_device_set_state(sdev, SDEV_QUIESCE);
                        return SPI_COMPARE_FAILURE;
                }

                /* If we don't have the inquiry data already, the
                 * first read gets it */
                if (ptr == buffer) {
                        ptr += len;
                        --r;
                        continue;
                }

                if (memcmp(buffer, ptr, len) != 0)
                        /* failure */
                        return SPI_COMPARE_FAILURE;
        }
        return SPI_COMPARE_SUCCESS;
}

static enum spi_compare_returns
spi_dv_retrain(struct scsi_device *sdev, u8 *buffer, u8 *ptr,
               enum spi_compare_returns 
               (*compare_fn)(struct scsi_device *, u8 *, u8 *, int))
{
        struct spi_internal *i = to_spi_internal(sdev->host->transportt);
        struct scsi_target *starget = sdev->sdev_target;
        int period = 0, prevperiod = 0; 
        enum spi_compare_returns retval;


        for (;;) {
                int newperiod;
                retval = compare_fn(sdev, buffer, ptr, DV_LOOPS);

                if (retval == SPI_COMPARE_SUCCESS
                    || retval == SPI_COMPARE_SKIP_TEST)
                        break;

                /* OK, retrain, fallback */
                if (i->f->get_iu)
                        i->f->get_iu(starget);
                if (i->f->get_qas)
                        i->f->get_qas(starget);
                if (i->f->get_period)
                        i->f->get_period(sdev->sdev_target);

                /* Here's the fallback sequence; first try turning off
                 * IU, then QAS (if we can control them), then finally
                 * fall down the periods */
                if (i->f->set_iu && spi_iu(starget)) {
                        starget_printk(KERN_ERR, starget, "Domain Validation Disabling Information Units\n");
                        DV_SET(iu, 0);
                } else if (i->f->set_qas && spi_qas(starget)) {
                        starget_printk(KERN_ERR, starget, "Domain Validation Disabling Quick Arbitration and Selection\n");
                        DV_SET(qas, 0);
                } else {
                        newperiod = spi_period(starget);
                        period = newperiod > period ? newperiod : period;
                        if (period < 0x0d)
                                period++;
                        else
                                period += period >> 1;

                        if (unlikely(period > 0xff || period == prevperiod)) {
                                /* Total failure; set to async and return */
                                starget_printk(KERN_ERR, starget, "Domain Validation Failure, dropping back to Asynchronous\n");
                                DV_SET(offset, 0);
                                return SPI_COMPARE_FAILURE;
                        }
                        starget_printk(KERN_ERR, starget, "Domain Validation detected failure, dropping back\n");
                        DV_SET(period, period);
                        prevperiod = period;
                }
        }
        return retval;
}

static int
spi_dv_device_get_echo_buffer(struct scsi_device *sdev, u8 *buffer)
{
        int l, result;

        /* first off do a test unit ready.  This can error out 
         * because of reservations or some other reason.  If it
         * fails, the device won't let us write to the echo buffer
         * so just return failure */
        
        static const char spi_test_unit_ready[] = {
                TEST_UNIT_READY, 0, 0, 0, 0, 0
        };

        static const char spi_read_buffer_descriptor[] = {
                READ_BUFFER, 0x0b, 0, 0, 0, 0, 0, 0, 4, 0
        };

        
        /* We send a set of three TURs to clear any outstanding 
         * unit attention conditions if they exist (Otherwise the
         * buffer tests won't be happy).  If the TUR still fails
         * (reservation conflict, device not ready, etc) just
         * skip the write tests */
        for (l = 0; ; l++) {
                result = spi_execute(sdev, spi_test_unit_ready, DMA_NONE, 
                                     NULL, 0, NULL);

                if(result) {
                        if(l >= 3)
                                return 0;
                } else {
                        /* TUR succeeded */
                        break;
                }
        }

        result = spi_execute(sdev, spi_read_buffer_descriptor, 
                             DMA_FROM_DEVICE, buffer, 4, NULL);

        if (result)
                /* Device has no echo buffer */
                return 0;

        return buffer[3] + ((buffer[2] & 0x1f) << 8);
}

static void
spi_dv_device_internal(struct scsi_device *sdev, u8 *buffer)
{
        struct spi_internal *i = to_spi_internal(sdev->host->transportt);
        struct scsi_target *starget = sdev->sdev_target;
        struct Scsi_Host *shost = sdev->host;
        int len = sdev->inquiry_len;
        int min_period = spi_min_period(starget);
        int max_width = spi_max_width(starget);
        /* first set us up for narrow async */
        DV_SET(offset, 0);
        DV_SET(width, 0);

        if (spi_dv_device_compare_inquiry(sdev, buffer, buffer, DV_LOOPS)
            != SPI_COMPARE_SUCCESS) {
                starget_printk(KERN_ERR, starget, "Domain Validation Initial Inquiry Failed\n");
                /* FIXME: should probably offline the device here? */
                return;
        }

        if (!spi_support_wide(starget)) {
                spi_max_width(starget) = 0;
                max_width = 0;
        }

        /* test width */
        if (i->f->set_width && max_width) {
                i->f->set_width(starget, 1);

                if (spi_dv_device_compare_inquiry(sdev, buffer,
                                                   buffer + len,
                                                   DV_LOOPS)
                    != SPI_COMPARE_SUCCESS) {
                        starget_printk(KERN_ERR, starget, "Wide Transfers Fail\n");
                        i->f->set_width(starget, 0);
                        /* Make sure we don't force wide back on by asking
                         * for a transfer period that requires it */
                        max_width = 0;
                        if (min_period < 10)
                                min_period = 10;
                }
        }

        if (!i->f->set_period)
                return;

        /* device can't handle synchronous */
        if (!spi_support_sync(starget) && !spi_support_dt(starget))
                return;

        /* len == -1 is the signal that we need to ascertain the
         * presence of an echo buffer before trying to use it.  len ==
         * 0 means we don't have an echo buffer */
        len = -1;

 retry:

        /* now set up to the maximum */
        DV_SET(offset, spi_max_offset(starget));
        DV_SET(period, min_period);

        /* try QAS requests; this should be harmless to set if the
         * target supports it */
        if (spi_support_qas(starget) && spi_max_qas(starget)) {
                DV_SET(qas, 1);
        } else {
                DV_SET(qas, 0);
        }

        if (spi_support_ius(starget) && spi_max_iu(starget) &&
            min_period < 9) {
                /* This u320 (or u640). Set IU transfers */
                DV_SET(iu, 1);
                /* Then set the optional parameters */
                DV_SET(rd_strm, 1);
                DV_SET(wr_flow, 1);
                DV_SET(rti, 1);
                if (min_period == 8)
                        DV_SET(pcomp_en, 1);
        } else {
                DV_SET(iu, 0);
        }

        /* now that we've done all this, actually check the bus
         * signal type (if known).  Some devices are stupid on
         * a SE bus and still claim they can try LVD only settings */
        if (i->f->get_signalling)
                i->f->get_signalling(shost);
        if (spi_signalling(shost) == SPI_SIGNAL_SE ||
            spi_signalling(shost) == SPI_SIGNAL_HVD ||
            !spi_support_dt(starget)) {
                DV_SET(dt, 0);
        } else {
                DV_SET(dt, 1);
        }
        /* set width last because it will pull all the other
         * parameters down to required values */
        DV_SET(width, max_width);

        /* Do the read only INQUIRY tests */
        spi_dv_retrain(sdev, buffer, buffer + sdev->inquiry_len,
                       spi_dv_device_compare_inquiry);
        /* See if we actually managed to negotiate and sustain DT */
        if (i->f->get_dt)
                i->f->get_dt(starget);

        /* see if the device has an echo buffer.  If it does we can do
         * the SPI pattern write tests.  Because of some broken
         * devices, we *only* try this on a device that has actually
         * negotiated DT */

        if (len == -1 && spi_dt(starget))
                len = spi_dv_device_get_echo_buffer(sdev, buffer);

        if (len <= 0) {
                starget_printk(KERN_INFO, starget, "Domain Validation skipping write tests\n");
                return;
        }

        if (len > SPI_MAX_ECHO_BUFFER_SIZE) {
                starget_printk(KERN_WARNING, starget, "Echo buffer size %d is too big, trimming to %d\n", len, SPI_MAX_ECHO_BUFFER_SIZE);
                len = SPI_MAX_ECHO_BUFFER_SIZE;
        }

        if (spi_dv_retrain(sdev, buffer, buffer + len,
                           spi_dv_device_echo_buffer)
            == SPI_COMPARE_SKIP_TEST) {
                /* OK, the stupid drive can't do a write echo buffer
                 * test after all, fall back to the read tests */
                len = 0;
                goto retry;
        }
}


/**     spi_dv_device - Do Domain Validation on the device
 *      @sdev:          scsi device to validate
 *
 *      Performs the domain validation on the given device in the

 *      current execution thread.  Since DV operations may sleep,
 *      the current thread must have user context.  Also no SCSI
 *      related locks that would deadlock I/O issued by the DV may
 *      be held.
 */
void
spi_dv_device(struct scsi_device *sdev)
{
        struct scsi_target *starget = sdev->sdev_target;
        u8 *buffer;
        const int len = SPI_MAX_ECHO_BUFFER_SIZE*2;

        /*
         * Because this function and the power management code both call
         * scsi_device_quiesce(), it is not safe to perform domain validation
         * while suspend or resume is in progress. Hence the
         * lock/unlock_system_sleep() calls.
         */
        lock_system_sleep();

        if (unlikely(spi_dv_in_progress(starget)))
                goto unlock;

        if (unlikely(scsi_device_get(sdev)))
                goto unlock;

        spi_dv_in_progress(starget) = 1;

        buffer = kzalloc(len, GFP_KERNEL);

        if (unlikely(!buffer))
                goto out_put;

        /* We need to verify that the actual device will quiesce; the
         * later target quiesce is just a nice to have */
        if (unlikely(scsi_device_quiesce(sdev)))
                goto out_free;

        scsi_target_quiesce(starget);

        spi_dv_pending(starget) = 1;
        mutex_lock(&spi_dv_mutex(starget));

        starget_printk(KERN_INFO, starget, "Beginning Domain Validation\n");

        spi_dv_device_internal(sdev, buffer);

        starget_printk(KERN_INFO, starget, "Ending Domain Validation\n");

        mutex_unlock(&spi_dv_mutex(starget));
        spi_dv_pending(starget) = 0;

        scsi_target_resume(starget);

        spi_initial_dv(starget) = 1;

 out_free:
        kfree(buffer);
 out_put:
        spi_dv_in_progress(starget) = 0;
        scsi_device_put(sdev);
unlock:
        unlock_system_sleep();
}
EXPORT_SYMBOL(spi_dv_device);

struct work_queue_wrapper {
        struct work_struct      work;
        struct scsi_device      *sdev;
};

static void
spi_dv_device_work_wrapper(struct work_struct *work)
{
        struct work_queue_wrapper *wqw =
                container_of(work, struct work_queue_wrapper, work);
        struct scsi_device *sdev = wqw->sdev;

        kfree(wqw);
        spi_dv_device(sdev);
        spi_dv_pending(sdev->sdev_target) = 0;
        scsi_device_put(sdev);
}


/**
 *      spi_schedule_dv_device - schedule domain validation to occur on the device
 *      @sdev:  The device to validate
 *
 *      Identical to spi_dv_device() above, except that the DV will be
 *      scheduled to occur in a workqueue later.  All memory allocations
 *      are atomic, so may be called from any context including those holding
 *      SCSI locks.
 */
void
spi_schedule_dv_device(struct scsi_device *sdev)
{
        struct work_queue_wrapper *wqw =
                kmalloc(sizeof(struct work_queue_wrapper), GFP_ATOMIC);

        if (unlikely(!wqw))
                return;

        if (unlikely(spi_dv_pending(sdev->sdev_target))) {
                kfree(wqw);
                return;
        }
        /* Set pending early (dv_device doesn't check it, only sets it) */
        spi_dv_pending(sdev->sdev_target) = 1;
        if (unlikely(scsi_device_get(sdev))) {
                kfree(wqw);
                spi_dv_pending(sdev->sdev_target) = 0;
                return;
        }

        INIT_WORK(&wqw->work, spi_dv_device_work_wrapper);
        wqw->sdev = sdev;

        schedule_work(&wqw->work);
}
EXPORT_SYMBOL(spi_schedule_dv_device);

/**
 * spi_display_xfer_agreement - Print the current target transfer agreement
 * @starget: The target for which to display the agreement
 *
 * Each SPI port is required to maintain a transfer agreement for each
 * other port on the bus.  This function prints a one-line summary of
 * the current agreement; more detailed information is available in sysfs.
 */
void spi_display_xfer_agreement(struct scsi_target *starget)
{
        struct spi_transport_attrs *tp;
        tp = (struct spi_transport_attrs *)&starget->starget_data;

        if (tp->offset > 0 && tp->period > 0) {
                unsigned int picosec, kb100;
                char *scsi = "FAST-?";
                char tmp[8];

                if (tp->period <= SPI_STATIC_PPR) {
                        picosec = ppr_to_ps[tp->period];
                        switch (tp->period) {
                                case  7: scsi = "FAST-320"; break;
                                case  8: scsi = "FAST-160"; break;
                                case  9: scsi = "FAST-80"; break;
                                case 10:
                                case 11: scsi = "FAST-40"; break;
                                case 12: scsi = "FAST-20"; break;
                        }
                } else {
                        picosec = tp->period * 4000;
                        if (tp->period < 25)
                                scsi = "FAST-20";
                        else if (tp->period < 50)
                                scsi = "FAST-10";
                        else
                                scsi = "FAST-5";
                }

                kb100 = (10000000 + picosec / 2) / picosec;
                if (tp->width)
                        kb100 *= 2;
                sprint_frac(tmp, picosec, 1000);

                dev_info(&starget->dev,
                         "%s %sSCSI %d.%d MB/s %s%s%s%s%s%s%s%s (%s ns, offset %d)\n",
                         scsi, tp->width ? "WIDE " : "", kb100/10, kb100 % 10,
                         tp->dt ? "DT" : "ST",
                         tp->iu ? " IU" : "",
                         tp->qas  ? " QAS" : "",
                         tp->rd_strm ? " RDSTRM" : "",
                         tp->rti ? " RTI" : "",
                         tp->wr_flow ? " WRFLOW" : "",
                         tp->pcomp_en ? " PCOMP" : "",
                         tp->hold_mcs ? " HMCS" : "",
                         tmp, tp->offset);
        } else {
                dev_info(&starget->dev, "%sasynchronous\n",
                                tp->width ? "wide " : "");
        }
}
EXPORT_SYMBOL(spi_display_xfer_agreement);

int spi_populate_width_msg(unsigned char *msg, int width)
{
        msg[0] = EXTENDED_MESSAGE;
        msg[1] = 2;
        msg[2] = EXTENDED_WDTR;
        msg[3] = width;
        return 4;
}
EXPORT_SYMBOL_GPL(spi_populate_width_msg);

int spi_populate_sync_msg(unsigned char *msg, int period, int offset)
{
        msg[0] = EXTENDED_MESSAGE;
        msg[1] = 3;
        msg[2] = EXTENDED_SDTR;
        msg[3] = period;
        msg[4] = offset;
        return 5;
}
EXPORT_SYMBOL_GPL(spi_populate_sync_msg);

int spi_populate_ppr_msg(unsigned char *msg, int period, int offset,
                int width, int options)
{
        msg[0] = EXTENDED_MESSAGE;
        msg[1] = 6;
        msg[2] = EXTENDED_PPR;
        msg[3] = period;
        msg[4] = 0;
        msg[5] = offset;
        msg[6] = width;
        msg[7] = options;
        return 8;
}
EXPORT_SYMBOL_GPL(spi_populate_ppr_msg);

/**
 * spi_populate_tag_msg - place a tag message in a buffer
 * @msg:        pointer to the area to place the tag
 * @cmd:        pointer to the scsi command for the tag
 *
 * Notes:
 *      designed to create the correct type of tag message for the 
 *      particular request.  Returns the size of the tag message.
 *      May return 0 if TCQ is disabled for this device.
 **/
int spi_populate_tag_msg(unsigned char *msg, struct scsi_cmnd *cmd)
{
        if (cmd->flags & SCMD_TAGGED) {
                *msg++ = SIMPLE_QUEUE_TAG;
                *msg++ = cmd->request->tag;
                return 2;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(spi_populate_tag_msg);

#ifdef CONFIG_SCSI_CONSTANTS
static const char * const one_byte_msgs[] = {
/* 0x00 */ "Task Complete", NULL /* Extended Message */, "Save Pointers",
/* 0x03 */ "Restore Pointers", "Disconnect", "Initiator Error", 
/* 0x06 */ "Abort Task Set", "Message Reject", "Nop", "Message Parity Error",
/* 0x0a */ "Linked Command Complete", "Linked Command Complete w/flag",
/* 0x0c */ "Target Reset", "Abort Task", "Clear Task Set", 
/* 0x0f */ "Initiate Recovery", "Release Recovery",
/* 0x11 */ "Terminate Process", "Continue Task", "Target Transfer Disable",
/* 0x14 */ NULL, NULL, "Clear ACA", "LUN Reset"
};

static const char * const two_byte_msgs[] = {
/* 0x20 */ "Simple Queue Tag", "Head of Queue Tag", "Ordered Queue Tag",
/* 0x23 */ "Ignore Wide Residue", "ACA"
};

static const char * const extended_msgs[] = {
/* 0x00 */ "Modify Data Pointer", "Synchronous Data Transfer Request",
/* 0x02 */ "SCSI-I Extended Identify", "Wide Data Transfer Request",
/* 0x04 */ "Parallel Protocol Request", "Modify Bidirectional Data Pointer"
};

static void print_nego(const unsigned char *msg, int per, int off, int width)
{
        if (per) {
                char buf[20];
                period_to_str(buf, msg[per]);
                printk("period = %s ns ", buf);
        }

        if (off)
                printk("offset = %d ", msg[off]);
        if (width)
                printk("width = %d ", 8 << msg[width]);
}

static void print_ptr(const unsigned char *msg, int msb, const char *desc)
{
        int ptr = (msg[msb] << 24) | (msg[msb+1] << 16) | (msg[msb+2] << 8) |
                        msg[msb+3];
        printk("%s = %d ", desc, ptr);
}

int spi_print_msg(const unsigned char *msg)
{
        int len = 1, i;
        if (msg[0] == EXTENDED_MESSAGE) {
                len = 2 + msg[1];
                if (len == 2)
                        len += 256;
                if (msg[2] < ARRAY_SIZE(extended_msgs))
                        printk ("%s ", extended_msgs[msg[2]]); 
                else 
                        printk ("Extended Message, reserved code (0x%02x) ",
                                (int) msg[2]);
                switch (msg[2]) {
                case EXTENDED_MODIFY_DATA_POINTER:
                        print_ptr(msg, 3, "pointer");
                        break;
                case EXTENDED_SDTR:
                        print_nego(msg, 3, 4, 0);
                        break;
                case EXTENDED_WDTR:
                        print_nego(msg, 0, 0, 3);
                        break;
                case EXTENDED_PPR:
                        print_nego(msg, 3, 5, 6);
                        break;
                case EXTENDED_MODIFY_BIDI_DATA_PTR:
                        print_ptr(msg, 3, "out");
                        print_ptr(msg, 7, "in");
                        break;
                default:
                for (i = 2; i < len; ++i) 
                        printk("%02x ", msg[i]);
                }
        /* Identify */
        } else if (msg[0] & 0x80) {
                printk("Identify disconnect %sallowed %s %d ",
                        (msg[0] & 0x40) ? "" : "not ",
                        (msg[0] & 0x20) ? "target routine" : "lun",
                        msg[0] & 0x7);
        /* Normal One byte */
        } else if (msg[0] < 0x1f) {
                if (msg[0] < ARRAY_SIZE(one_byte_msgs) && one_byte_msgs[msg[0]])
                        printk("%s ", one_byte_msgs[msg[0]]);
                else
                        printk("reserved (%02x) ", msg[0]);
        } else if (msg[0] == 0x55) {
                printk("QAS Request ");
        /* Two byte */
        } else if (msg[0] <= 0x2f) {
                if ((msg[0] - 0x20) < ARRAY_SIZE(two_byte_msgs))
                        printk("%s %02x ", two_byte_msgs[msg[0] - 0x20], 
                                msg[1]);
                else 
                        printk("reserved two byte (%02x %02x) ", 
                                msg[0], msg[1]);
                len = 2;
        } else 
                printk("reserved ");
        return len;
}
EXPORT_SYMBOL(spi_print_msg);

#else  /* ifndef CONFIG_SCSI_CONSTANTS */

int spi_print_msg(const unsigned char *msg)
{
        int len = 1, i;

        if (msg[0] == EXTENDED_MESSAGE) {
                len = 2 + msg[1];
                if (len == 2)
                        len += 256;
                for (i = 0; i < len; ++i)
                        printk("%02x ", msg[i]);
        /* Identify */
        } else if (msg[0] & 0x80) {
                printk("%02x ", msg[0]);
        /* Normal One byte */
        } else if ((msg[0] < 0x1f) || (msg[0] == 0x55)) {
                printk("%02x ", msg[0]);
        /* Two byte */
        } else if (msg[0] <= 0x2f) {
                printk("%02x %02x", msg[0], msg[1]);
                len = 2;
        } else 
                printk("%02x ", msg[0]);
        return len;
}
EXPORT_SYMBOL(spi_print_msg);
#endif /* ! CONFIG_SCSI_CONSTANTS */

static int spi_device_match(struct attribute_container *cont,
                            struct device *dev)
{
        struct scsi_device *sdev;
        struct Scsi_Host *shost;
        struct spi_internal *i;

        if (!scsi_is_sdev_device(dev))
                return 0;

        sdev = to_scsi_device(dev);
        shost = sdev->host;
        if (!shost->transportt  || shost->transportt->host_attrs.ac.class
            != &spi_host_class.class)
                return 0;
        /* Note: this class has no device attributes, so it has
         * no per-HBA allocation and thus we don't need to distinguish
         * the attribute containers for the device */
        i = to_spi_internal(shost->transportt);
        if (i->f->deny_binding && i->f->deny_binding(sdev->sdev_target))
                return 0;
        return 1;
}

static int spi_target_match(struct attribute_container *cont,
                            struct device *dev)
{
        struct Scsi_Host *shost;
        struct scsi_target *starget;
        struct spi_internal *i;

        if (!scsi_is_target_device(dev))
                return 0;

        shost = dev_to_shost(dev->parent);
        if (!shost->transportt  || shost->transportt->host_attrs.ac.class
            != &spi_host_class.class)
                return 0;

        i = to_spi_internal(shost->transportt);
        starget = to_scsi_target(dev);

        if (i->f->deny_binding && i->f->deny_binding(starget))
                return 0;

        return &i->t.target_attrs.ac == cont;
}

static DECLARE_TRANSPORT_CLASS(spi_transport_class,
                               "spi_transport",
                               spi_setup_transport_attrs,
                               NULL,
                               spi_target_configure);

static DECLARE_ANON_TRANSPORT_CLASS(spi_device_class,
                                    spi_device_match,
                                    spi_device_configure);

static struct attribute *host_attributes[] = {
        &dev_attr_signalling.attr,
        &dev_attr_host_width.attr,
        &dev_attr_hba_id.attr,
        NULL
};

static struct attribute_group host_attribute_group = {
        .attrs = host_attributes,
};

static int spi_host_configure(struct transport_container *tc,
                              struct device *dev,
                              struct device *cdev)
{
        struct kobject *kobj = &cdev->kobj;
        struct Scsi_Host *shost = transport_class_to_shost(cdev);
        struct spi_internal *si = to_spi_internal(shost->transportt);
        struct attribute *attr = &dev_attr_signalling.attr;
        int rc = 0;

        if (si->f->set_signalling)
                rc = sysfs_chmod_file(kobj, attr, attr->mode | S_IWUSR);

        return rc;
}

/* returns true if we should be showing the variable.  Also
 * overloads the return by setting 1<<1 if the attribute should
 * be writeable */
#define TARGET_ATTRIBUTE_HELPER(name) \
        (si->f->show_##name ? S_IRUGO : 0) | \
        (si->f->set_##name ? S_IWUSR : 0)

static umode_t target_attribute_is_visible(struct kobject *kobj,
                                          struct attribute *attr, int i)
{
        struct device *cdev = container_of(kobj, struct device, kobj);
        struct scsi_target *starget = transport_class_to_starget(cdev);
        struct Scsi_Host *shost = transport_class_to_shost(cdev);
        struct spi_internal *si = to_spi_internal(shost->transportt);

        if (attr == &dev_attr_period.attr &&
            spi_support_sync(starget))
                return TARGET_ATTRIBUTE_HELPER(period);
        else if (attr == &dev_attr_min_period.attr &&
                 spi_support_sync(starget))
                return TARGET_ATTRIBUTE_HELPER(period);
        else if (attr == &dev_attr_offset.attr &&
                 spi_support_sync(starget))
                return TARGET_ATTRIBUTE_HELPER(offset);
        else if (attr == &dev_attr_max_offset.attr &&
                 spi_support_sync(starget))
                return TARGET_ATTRIBUTE_HELPER(offset);
        else if (attr == &dev_attr_width.attr &&
                 spi_support_wide(starget))
                return TARGET_ATTRIBUTE_HELPER(width);
        else if (attr == &dev_attr_max_width.attr &&
                 spi_support_wide(starget))
                return TARGET_ATTRIBUTE_HELPER(width);
        else if (attr == &dev_attr_iu.attr &&
                 spi_support_ius(starget))
                return TARGET_ATTRIBUTE_HELPER(iu);
        else if (attr == &dev_attr_max_iu.attr &&
                 spi_support_ius(starget))
                return TARGET_ATTRIBUTE_HELPER(iu);
        else if (attr == &dev_attr_dt.attr &&
                 spi_support_dt(starget))
                return TARGET_ATTRIBUTE_HELPER(dt);
        else if (attr == &dev_attr_qas.attr &&
                 spi_support_qas(starget))
                return TARGET_ATTRIBUTE_HELPER(qas);
        else if (attr == &dev_attr_max_qas.attr &&
                 spi_support_qas(starget))
                return TARGET_ATTRIBUTE_HELPER(qas);
        else if (attr == &dev_attr_wr_flow.attr &&
                 spi_support_ius(starget))
                return TARGET_ATTRIBUTE_HELPER(wr_flow);
        else if (attr == &dev_attr_rd_strm.attr &&
                 spi_support_ius(starget))
                return TARGET_ATTRIBUTE_HELPER(rd_strm);
        else if (attr == &dev_attr_rti.attr &&
                 spi_support_ius(starget))
                return TARGET_ATTRIBUTE_HELPER(rti);
        else if (attr == &dev_attr_pcomp_en.attr &&
                 spi_support_ius(starget))
                return TARGET_ATTRIBUTE_HELPER(pcomp_en);
        else if (attr == &dev_attr_hold_mcs.attr &&
                 spi_support_ius(starget))
                return TARGET_ATTRIBUTE_HELPER(hold_mcs);
        else if (attr == &dev_attr_revalidate.attr)
                return S_IWUSR;

        return 0;
}

static struct attribute *target_attributes[] = {
        &dev_attr_period.attr,
        &dev_attr_min_period.attr,
        &dev_attr_offset.attr,
        &dev_attr_max_offset.attr,
        &dev_attr_width.attr,
        &dev_attr_max_width.attr,
        &dev_attr_iu.attr,
        &dev_attr_max_iu.attr,
        &dev_attr_dt.attr,
        &dev_attr_qas.attr,
        &dev_attr_max_qas.attr,
        &dev_attr_wr_flow.attr,
        &dev_attr_rd_strm.attr,
        &dev_attr_rti.attr,
        &dev_attr_pcomp_en.attr,
        &dev_attr_hold_mcs.attr,
        &dev_attr_revalidate.attr,
        NULL
};

static struct attribute_group target_attribute_group = {
        .attrs = target_attributes,
        .is_visible = target_attribute_is_visible,
};

static int spi_target_configure(struct transport_container *tc,
                                struct device *dev,
                                struct device *cdev)
{
        struct kobject *kobj = &cdev->kobj;

        /* force an update based on parameters read from the device */
        sysfs_update_group(kobj, &target_attribute_group);

        return 0;
}

struct scsi_transport_template *
spi_attach_transport(struct spi_function_template *ft)
{
        struct spi_internal *i = kzalloc(sizeof(struct spi_internal),
                                         GFP_KERNEL);

        if (unlikely(!i))
                return NULL;

        i->t.target_attrs.ac.class = &spi_transport_class.class;
        i->t.target_attrs.ac.grp = &target_attribute_group;
        i->t.target_attrs.ac.match = spi_target_match;
        transport_container_register(&i->t.target_attrs);
        i->t.target_size = sizeof(struct spi_transport_attrs);
        i->t.host_attrs.ac.class = &spi_host_class.class;
        i->t.host_attrs.ac.grp = &host_attribute_group;
        i->t.host_attrs.ac.match = spi_host_match;
        transport_container_register(&i->t.host_attrs);
        i->t.host_size = sizeof(struct spi_host_attrs);
        i->f = ft;

        return &i->t;
}
EXPORT_SYMBOL(spi_attach_transport);

void spi_release_transport(struct scsi_transport_template *t)
{
        struct spi_internal *i = to_spi_internal(t);

        transport_container_unregister(&i->t.target_attrs);
        transport_container_unregister(&i->t.host_attrs);

        kfree(i);
}
EXPORT_SYMBOL(spi_release_transport);

static __init int spi_transport_init(void)
{
        int error = scsi_dev_info_add_list(SCSI_DEVINFO_SPI,
                                           "SCSI Parallel Transport Class");
        if (!error) {
                int i;

                for (i = 0; spi_static_device_list[i].vendor; i++)
                        scsi_dev_info_list_add_keyed(1, /* compatible */
                                                     spi_static_device_list[i].vendor,
                                                     spi_static_device_list[i].model,
                                                     NULL,
                                                     spi_static_device_list[i].flags,
                                                     SCSI_DEVINFO_SPI);
        }

        error = transport_class_register(&spi_transport_class);
        if (error)
                return error;
        error = anon_transport_class_register(&spi_device_class);
        return transport_class_register(&spi_host_class);
}

static void __exit spi_transport_exit(void)
{
        transport_class_unregister(&spi_transport_class);
        anon_transport_class_unregister(&spi_device_class);
        transport_class_unregister(&spi_host_class);
        scsi_dev_info_remove_list(SCSI_DEVINFO_SPI);
}

MODULE_AUTHOR("Martin Hicks");
MODULE_DESCRIPTION("SPI Transport Attributes");
MODULE_LICENSE("GPL");

module_init(spi_transport_init);
module_exit(spi_transport_exit);