ARK-OS/arkos/kernel/drivers/scsi/scsi_transport_spi.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* 
 *  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>
 */
#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 req_op op, void *buffer, unsigned int bufflen,
		       struct scsi_sense_hdr *sshdr)
{
	blk_opf_t opf = op | REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
			REQ_FAILFAST_DRIVER;
	struct scsi_failure failure_defs[] = {
		{
			.sense = UNIT_ATTENTION,
			.asc = SCMD_FAILURE_ASC_ANY,
			.ascq = SCMD_FAILURE_ASCQ_ANY,
			.allowed = DV_RETRIES,
			.result = SAM_STAT_CHECK_CONDITION,
		},
		{}
	};
	struct scsi_failures failures = {
		.failure_definitions = failure_defs,
	};
	const struct scsi_exec_args exec_args = {
		/* bypass the SDEV_QUIESCE state with BLK_MQ_REQ_PM */
		.req_flags = BLK_MQ_REQ_PM,
		.sshdr = sshdr,
		.failures = &failures,
	};

	return scsi_execute_cmd(sdev, cmd, opf, buffer, bufflen, DV_TIMEOUT, 1,
				&exec_args);
}

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, REQ_OP_DRV_OUT,
				     buffer, len, &sshdr);
		if (result || !scsi_device_online(sdev)) {

			scsi_device_set_state(sdev, SDEV_QUIESCE);
			if (result > 0 && 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, REQ_OP_DRV_IN,
			    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, REQ_OP_DRV_IN,
				     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, REQ_OP_DRV_IN,
				     NULL, 0, NULL);

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

	result = spi_execute(sdev, spi_read_buffer_descriptor, 
			     REQ_OP_DRV_IN, 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;
	const int len = SPI_MAX_ECHO_BUFFER_SIZE*2;
	unsigned int sleep_flags;
	u8 *buffer;

	/*
	 * 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.
	 */
	sleep_flags = lock_system_sleep();

	if (scsi_autopm_get_device(sdev))
		goto unlock_system_sleep;

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

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

	spi_dv_in_progress(starget) = 1;

	buffer = kzalloc(len, GFP_KERNEL);

	if (unlikely(!buffer))
		goto put_sdev;

	/* 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 free_buffer;

	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;

free_buffer:
	kfree(buffer);

put_sdev:
	spi_dv_in_progress(starget) = 0;
	scsi_device_put(sdev);
put_autopm:
	scsi_autopm_put_device(sdev);

unlock_system_sleep:
	unlock_system_sleep(sleep_flags);
}
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_obj(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++ = scsi_cmd_to_rq(cmd)->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_obj(struct spi_internal);

	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;
	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);