/*
 * scsi_sysfs.c
 *
 * SCSI sysfs interface routines.
 *
 * Created to pull SCSI mid layer sysfs routines into one file.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/device.h>
#include <linux/pm_runtime.h>

#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_driver.h>

#include "scsi_priv.h"
#include "scsi_logging.h"

static struct device_type scsi_dev_type;

static const struct {
	enum scsi_device_state	value;
	char			*name;
} sdev_states[] = {
	{ SDEV_CREATED, "created" },
	{ SDEV_RUNNING, "running" },
	{ SDEV_CANCEL, "cancel" },
	{ SDEV_DEL, "deleted" },
	{ SDEV_QUIESCE, "quiesce" },
	{ SDEV_OFFLINE,	"offline" },
	{ SDEV_BLOCK,	"blocked" },
	{ SDEV_CREATED_BLOCK, "created-blocked" },
};

const char *scsi_device_state_name(enum scsi_device_state state)
{
	int i;
	char *name = NULL;

	for (i = 0; i < ARRAY_SIZE(sdev_states); i++) {
		if (sdev_states[i].value == state) {
			name = sdev_states[i].name;
			break;
		}
	}
	return name;
}

static const struct {
	enum scsi_host_state	value;
	char			*name;
} shost_states[] = {
	{ SHOST_CREATED, "created" },
	{ SHOST_RUNNING, "running" },
	{ SHOST_CANCEL, "cancel" },
	{ SHOST_DEL, "deleted" },
	{ SHOST_RECOVERY, "recovery" },
	{ SHOST_CANCEL_RECOVERY, "cancel/recovery" },
	{ SHOST_DEL_RECOVERY, "deleted/recovery", },
};
const char *scsi_host_state_name(enum scsi_host_state state)
{
	int i;
	char *name = NULL;

	for (i = 0; i < ARRAY_SIZE(shost_states); i++) {
		if (shost_states[i].value == state) {
			name = shost_states[i].name;
			break;
		}
	}
	return name;
}

static int check_set(unsigned int *val, char *src)
{
	char *last;

	if (strncmp(src, "-", 20) == 0) {
		*val = SCAN_WILD_CARD;
	} else {
		/*
		 * Doesn't check for int overflow
		 */
		*val = simple_strtoul(src, &last, 0);
		if (*last != '\0')
			return 1;
	}
	return 0;
}

static int scsi_scan(struct Scsi_Host *shost, const char *str)
{
	char s1[15], s2[15], s3[15], junk;
	unsigned int channel, id, lun;
	int res;

	res = sscanf(str, "%10s %10s %10s %c", s1, s2, s3, &junk);
	if (res != 3)
		return -EINVAL;
	if (check_set(&channel, s1))
		return -EINVAL;
	if (check_set(&id, s2))
		return -EINVAL;
	if (check_set(&lun, s3))
		return -EINVAL;
	if (shost->transportt->user_scan)
		res = shost->transportt->user_scan(shost, channel, id, lun);
	else
		res = scsi_scan_host_selected(shost, channel, id, lun, 1);
	return res;
}

/*
 * shost_show_function: macro to create an attr function that can be used to
 * show a non-bit field.
 */
#define shost_show_function(name, field, format_string)			\
static ssize_t								\
show_##name (struct device *dev, struct device_attribute *attr, 	\
	     char *buf)							\
{									\
	struct Scsi_Host *shost = class_to_shost(dev);			\
	return snprintf (buf, 20, format_string, shost->field);		\
}

/*
 * shost_rd_attr: macro to create a function and attribute variable for a
 * read only field.
 */
#define shost_rd_attr2(name, field, format_string)			\
	shost_show_function(name, field, format_string)			\
static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL);

#define shost_rd_attr(field, format_string) \
shost_rd_attr2(field, field, format_string)

/*
 * Create the actual show/store functions and data structures.
 */

static ssize_t
store_scan(struct device *dev, struct device_attribute *attr,
	   const char *buf, size_t count)
{
	struct Scsi_Host *shost = class_to_shost(dev);
	int res;

	res = scsi_scan(shost, buf);
	if (res == 0)
		res = count;
	return res;
};
static DEVICE_ATTR(scan, S_IWUSR, NULL, store_scan);

static ssize_t
store_shost_state(struct device *dev, struct device_attribute *attr,
		  const char *buf, size_t count)
{
	int i;
	struct Scsi_Host *shost = class_to_shost(dev);
	enum scsi_host_state state = 0;

	for (i = 0; i < ARRAY_SIZE(shost_states); i++) {
		const int len = strlen(shost_states[i].name);
		if (strncmp(shost_states[i].name, buf, len) == 0 &&
		   buf[len] == '\n') {
			state = shost_states[i].value;
			break;
		}
	}
	if (!state)
		return -EINVAL;

	if (scsi_host_set_state(shost, state))
		return -EINVAL;
	return count;
}

static ssize_t
show_shost_state(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct Scsi_Host *shost = class_to_shost(dev);
	const char *name = scsi_host_state_name(shost->shost_state);

	if (!name)
		return -EINVAL;

	return snprintf(buf, 20, "%s\n", name);
}

/* DEVICE_ATTR(state) clashes with dev_attr_state for sdev */
struct device_attribute dev_attr_hstate =
	__ATTR(state, S_IRUGO | S_IWUSR, show_shost_state, store_shost_state);

static ssize_t
show_shost_mode(unsigned int mode, char *buf)
{
	ssize_t len = 0;

	if (mode & MODE_INITIATOR)
		len = sprintf(buf, "%s", "Initiator");

	if (mode & MODE_TARGET)
		len += sprintf(buf + len, "%s%s", len ? ", " : "", "Target");

	len += sprintf(buf + len, "\n");

	return len;
}

static ssize_t
show_shost_supported_mode(struct device *dev, struct device_attribute *attr,
			  char *buf)
{
	struct Scsi_Host *shost = class_to_shost(dev);
	unsigned int supported_mode = shost->hostt->supported_mode;

	if (supported_mode == MODE_UNKNOWN)
		/* by default this should be initiator */
		supported_mode = MODE_INITIATOR;

	return show_shost_mode(supported_mode, buf);
}

static DEVICE_ATTR(supported_mode, S_IRUGO | S_IWUSR, show_shost_supported_mode, NULL);

static ssize_t
show_shost_active_mode(struct device *dev,
		       struct device_attribute *attr, char *buf)
{
	struct Scsi_Host *shost = class_to_shost(dev);

	if (shost->active_mode == MODE_UNKNOWN)
		return snprintf(buf, 20, "unknown\n");
	else
		return show_shost_mode(shost->active_mode, buf);
}

static DEVICE_ATTR(active_mode, S_IRUGO | S_IWUSR, show_shost_active_mode, NULL);

static int check_reset_type(char *str)
{
	if (strncmp(str, "adapter", 10) == 0)
		return SCSI_ADAPTER_RESET;
	else if (strncmp(str, "firmware", 10) == 0)
		return SCSI_FIRMWARE_RESET;
	else
		return 0;
}

static ssize_t
store_host_reset(struct device *dev, struct device_attribute *attr,
		const char *buf, size_t count)
{
	struct Scsi_Host *shost = class_to_shost(dev);
	struct scsi_host_template *sht = shost->hostt;
	int ret = -EINVAL;
	char str[10];
	int type;

	sscanf(buf, "%s", str);
	type = check_reset_type(str);

	if (!type)
		goto exit_store_host_reset;

	if (sht->host_reset)
		ret = sht->host_reset(shost, type);

exit_store_host_reset:
	if (ret == 0)
		ret = count;
	return ret;
}

static DEVICE_ATTR(host_reset, S_IWUSR, NULL, store_host_reset);

shost_rd_attr(unique_id, "%u\n");
shost_rd_attr(host_busy, "%hu\n");
shost_rd_attr(cmd_per_lun, "%hd\n");
shost_rd_attr(can_queue, "%hd\n");
shost_rd_attr(sg_tablesize, "%hu\n");
shost_rd_attr(sg_prot_tablesize, "%hu\n");
shost_rd_attr(unchecked_isa_dma, "%d\n");
shost_rd_attr(prot_capabilities, "%u\n");
shost_rd_attr(prot_guard_type, "%hd\n");
shost_rd_attr2(proc_name, hostt->proc_name, "%s\n");

static struct attribute *scsi_sysfs_shost_attrs[] = {
	&dev_attr_unique_id.attr,
	&dev_attr_host_busy.attr,
	&dev_attr_cmd_per_lun.attr,
	&dev_attr_can_queue.attr,
	&dev_attr_sg_tablesize.attr,
	&dev_attr_sg_prot_tablesize.attr,
	&dev_attr_unchecked_isa_dma.attr,
	&dev_attr_proc_name.attr,
	&dev_attr_scan.attr,
	&dev_attr_hstate.attr,
	&dev_attr_supported_mode.attr,
	&dev_attr_active_mode.attr,
	&dev_attr_prot_capabilities.attr,
	&dev_attr_prot_guard_type.attr,
	&dev_attr_host_reset.attr,
	NULL
};

struct attribute_group scsi_shost_attr_group = {
	.attrs =	scsi_sysfs_shost_attrs,
};

const struct attribute_group *scsi_sysfs_shost_attr_groups[] = {
	&scsi_shost_attr_group,
	NULL
};

static void scsi_device_cls_release(struct device *class_dev)
{
	struct scsi_device *sdev;

	sdev = class_to_sdev(class_dev);
	put_device(&sdev->sdev_gendev);
}

static void scsi_device_dev_release_usercontext(struct work_struct *work)
{
	struct scsi_device *sdev;
	struct device *parent;
	struct scsi_target *starget;
	struct list_head *this, *tmp;
	unsigned long flags;

	sdev = container_of(work, struct scsi_device, ew.work);

	parent = sdev->sdev_gendev.parent;
	starget = to_scsi_target(parent);

	spin_lock_irqsave(sdev->host->host_lock, flags);
	starget->reap_ref++;
	list_del(&sdev->siblings);
	list_del(&sdev->same_target_siblings);
	list_del(&sdev->starved_entry);
	spin_unlock_irqrestore(sdev->host->host_lock, flags);

	cancel_work_sync(&sdev->event_work);

	list_for_each_safe(this, tmp, &sdev->event_list) {
		struct scsi_event *evt;

		evt = list_entry(this, struct scsi_event, node);
		list_del(&evt->node);
		kfree(evt);
	}

	blk_put_queue(sdev->request_queue);
	/* NULL queue means the device can't be used */
	sdev->request_queue = NULL;

	scsi_target_reap(scsi_target(sdev));

	kfree(sdev->inquiry);
	kfree(sdev);

	if (parent)
		put_device(parent);
}

static void scsi_device_dev_release(struct device *dev)
{
	struct scsi_device *sdp = to_scsi_device(dev);
	execute_in_process_context(scsi_device_dev_release_usercontext,
				   &sdp->ew);
}

static struct class sdev_class = {
	.name		= "scsi_device",
	.dev_release	= scsi_device_cls_release,
};

/* all probing is done in the individual ->probe routines */
static int scsi_bus_match(struct device *dev, struct device_driver *gendrv)
{
	struct scsi_device *sdp;

	if (dev->type != &scsi_dev_type)
		return 0;

	sdp = to_scsi_device(dev);
	if (sdp->no_uld_attach)
		return 0;
	return (sdp->inq_periph_qual == SCSI_INQ_PQ_CON)? 1: 0;
}

static int scsi_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	struct scsi_device *sdev;

	if (dev->type != &scsi_dev_type)
		return 0;

	sdev = to_scsi_device(dev);

	add_uevent_var(env, "MODALIAS=" SCSI_DEVICE_MODALIAS_FMT, sdev->type);
	return 0;
}

struct bus_type scsi_bus_type = {
        .name		= "scsi",
        .match		= scsi_bus_match,
	.uevent		= scsi_bus_uevent,
#ifdef CONFIG_PM
	.pm		= &scsi_bus_pm_ops,
#endif
};
EXPORT_SYMBOL_GPL(scsi_bus_type);

int scsi_sysfs_register(void)
{
	int error;

	error = bus_register(&scsi_bus_type);
	if (!error) {
		error = class_register(&sdev_class);
		if (error)
			bus_unregister(&scsi_bus_type);
	}

	return error;
}

void scsi_sysfs_unregister(void)
{
	class_unregister(&sdev_class);
	bus_unregister(&scsi_bus_type);
}

/*
 * sdev_show_function: macro to create an attr function that can be used to
 * show a non-bit field.
 */
#define sdev_show_function(field, format_string)				\
static ssize_t								\
sdev_show_##field (struct device *dev, struct device_attribute *attr,	\
		   char *buf)						\
{									\
	struct scsi_device *sdev;					\
	sdev = to_scsi_device(dev);					\
	return snprintf (buf, 20, format_string, sdev->field);		\
}									\

/*
 * sdev_rd_attr: macro to create a function and attribute variable for a
 * read only field.
 */
#define sdev_rd_attr(field, format_string)				\
	sdev_show_function(field, format_string)			\
static DEVICE_ATTR(field, S_IRUGO, sdev_show_##field, NULL);


/*
 * sdev_rw_attr: create a function and attribute variable for a
 * read/write field.
 */
#define sdev_rw_attr(field, format_string)				\
	sdev_show_function(field, format_string)				\
									\
static ssize_t								\
sdev_store_##field (struct device *dev, struct device_attribute *attr,	\
		    const char *buf, size_t count)			\
{									\
	struct scsi_device *sdev;					\
	sdev = to_scsi_device(dev);					\
	sscanf (buf, format_string, &sdev->field);			\
	return count;							\
}									\
static DEVICE_ATTR(field, S_IRUGO | S_IWUSR, sdev_show_##field, sdev_store_##field);

/* Currently we don't export bit fields, but we might in future,
 * so leave this code in */
#if 0
/*
 * sdev_rd_attr: create a function and attribute variable for a
 * read/write bit field.
 */
#define sdev_rw_attr_bit(field)						\
	sdev_show_function(field, "%d\n")					\
									\
static ssize_t								\
sdev_store_##field (struct device *dev, struct device_attribute *attr,	\
		    const char *buf, size_t count)			\
{									\
	int ret;							\
	struct scsi_device *sdev;					\
	ret = scsi_sdev_check_buf_bit(buf);				\
	if (ret >= 0)	{						\
		sdev = to_scsi_device(dev);				\
		sdev->field = ret;					\
		ret = count;						\
	}								\
	return ret;							\
}									\
static DEVICE_ATTR(field, S_IRUGO | S_IWUSR, sdev_show_##field, sdev_store_##field);

/*
 * scsi_sdev_check_buf_bit: return 0 if buf is "0", return 1 if buf is "1",
 * else return -EINVAL.
 */
static int scsi_sdev_check_buf_bit(const char *buf)
{
	if ((buf[1] == '\0') || ((buf[1] == '\n') && (buf[2] == '\0'))) {
		if (buf[0] == '1')
			return 1;
		else if (buf[0] == '0')
			return 0;
		else 
			return -EINVAL;
	} else
		return -EINVAL;
}
#endif
/*
 * Create the actual show/store functions and data structures.
 */
sdev_rd_attr (device_blocked, "%d\n");
sdev_rd_attr (queue_depth, "%d\n");
sdev_rd_attr (type, "%d\n");
sdev_rd_attr (scsi_level, "%d\n");
sdev_rd_attr (vendor, "%.8s\n");
sdev_rd_attr (model, "%.16s\n");
sdev_rd_attr (rev, "%.4s\n");

/*
 * TODO: can we make these symlinks to the block layer ones?
 */
static ssize_t
sdev_show_timeout (struct device *dev, struct device_attribute *attr, char *buf)
{
	struct scsi_device *sdev;
	sdev = to_scsi_device(dev);
	return snprintf(buf, 20, "%d\n", sdev->request_queue->rq_timeout / HZ);
}

static ssize_t
sdev_store_timeout (struct device *dev, struct device_attribute *attr,
		    const char *buf, size_t count)
{
	struct scsi_device *sdev;
	int timeout;
	sdev = to_scsi_device(dev);
	sscanf (buf, "%d\n", &timeout);
	blk_queue_rq_timeout(sdev->request_queue, timeout * HZ);
	return count;
}
static DEVICE_ATTR(timeout, S_IRUGO | S_IWUSR, sdev_show_timeout, sdev_store_timeout);

static ssize_t
store_rescan_field (struct device *dev, struct device_attribute *attr,
		    const char *buf, size_t count)
{
	scsi_rescan_device(dev);
	return count;
}
static DEVICE_ATTR(rescan, S_IWUSR, NULL, store_rescan_field);

static void sdev_store_delete_callback(struct device *dev)
{
	scsi_remove_device(to_scsi_device(dev));
}

static ssize_t
sdev_store_delete(struct device *dev, struct device_attribute *attr,
		  const char *buf, size_t count)
{
	int rc;

	/* An attribute cannot be unregistered by one of its own methods,
	 * so we have to use this roundabout approach.
	 */
	rc = device_schedule_callback(dev, sdev_store_delete_callback);
	if (rc)
		count = rc;
	return count;
};
static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);

static ssize_t
store_state_field(struct device *dev, struct device_attribute *attr,
		  const char *buf, size_t count)
{
	int i;
	struct scsi_device *sdev = to_scsi_device(dev);
	enum scsi_device_state state = 0;

	for (i = 0; i < ARRAY_SIZE(sdev_states); i++) {
		const int len = strlen(sdev_states[i].name);
		if (strncmp(sdev_states[i].name, buf, len) == 0 &&
		   buf[len] == '\n') {
			state = sdev_states[i].value;
			break;
		}
	}
	if (!state)
		return -EINVAL;

	if (scsi_device_set_state(sdev, state))
		return -EINVAL;
	return count;
}

static ssize_t
show_state_field(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct scsi_device *sdev = to_scsi_device(dev);
	const char *name = scsi_device_state_name(sdev->sdev_state);

	if (!name)
		return -EINVAL;

	return snprintf(buf, 20, "%s\n", name);
}

static DEVICE_ATTR(state, S_IRUGO | S_IWUSR, show_state_field, store_state_field);

static ssize_t
show_queue_type_field(struct device *dev, struct device_attribute *attr,
		      char *buf)
{
	struct scsi_device *sdev = to_scsi_device(dev);
	const char *name = "none";

	if (sdev->ordered_tags)
		name = "ordered";
	else if (sdev->simple_tags)
		name = "simple";

	return snprintf(buf, 20, "%s\n", name);
}

static DEVICE_ATTR(queue_type, S_IRUGO, show_queue_type_field, NULL);

static ssize_t
show_iostat_counterbits(struct device *dev, struct device_attribute *attr, 				char *buf)
{
	return snprintf(buf, 20, "%d\n", (int)sizeof(atomic_t) * 8);
}

static DEVICE_ATTR(iocounterbits, S_IRUGO, show_iostat_counterbits, NULL);

#define show_sdev_iostat(field)						\
static ssize_t								\
show_iostat_##field(struct device *dev, struct device_attribute *attr,	\
		    char *buf)						\
{									\
	struct scsi_device *sdev = to_scsi_device(dev);			\
	unsigned long long count = atomic_read(&sdev->field);		\
	return snprintf(buf, 20, "0x%llx\n", count);			\
}									\
static DEVICE_ATTR(field, S_IRUGO, show_iostat_##field, NULL)

show_sdev_iostat(iorequest_cnt);
show_sdev_iostat(iodone_cnt);
show_sdev_iostat(ioerr_cnt);

static ssize_t
sdev_show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct scsi_device *sdev;
	sdev = to_scsi_device(dev);
	return snprintf (buf, 20, SCSI_DEVICE_MODALIAS_FMT "\n", sdev->type);
}
static DEVICE_ATTR(modalias, S_IRUGO, sdev_show_modalias, NULL);

#define DECLARE_EVT_SHOW(name, Cap_name)				\
static ssize_t								\
sdev_show_evt_##name(struct device *dev, struct device_attribute *attr,	\
		     char *buf)						\
{									\
	struct scsi_device *sdev = to_scsi_device(dev);			\
	int val = test_bit(SDEV_EVT_##Cap_name, sdev->supported_events);\
	return snprintf(buf, 20, "%d\n", val);				\
}

#define DECLARE_EVT_STORE(name, Cap_name)				\
static ssize_t								\
sdev_store_evt_##name(struct device *dev, struct device_attribute *attr,\
		      const char *buf, size_t count)			\
{									\
	struct scsi_device *sdev = to_scsi_device(dev);			\
	int val = simple_strtoul(buf, NULL, 0);				\
	if (val == 0)							\
		clear_bit(SDEV_EVT_##Cap_name, sdev->supported_events);	\
	else if (val == 1)						\
		set_bit(SDEV_EVT_##Cap_name, sdev->supported_events);	\
	else								\
		return -EINVAL;						\
	return count;							\
}

#define DECLARE_EVT(name, Cap_name)					\
	DECLARE_EVT_SHOW(name, Cap_name)				\
	DECLARE_EVT_STORE(name, Cap_name)				\
	static DEVICE_ATTR(evt_##name, S_IRUGO, sdev_show_evt_##name,	\
			   sdev_store_evt_##name);
#define REF_EVT(name) &dev_attr_evt_##name.attr

DECLARE_EVT(media_change, MEDIA_CHANGE)

/* Default template for device attributes.  May NOT be modified */
static struct attribute *scsi_sdev_attrs[] = {
	&dev_attr_device_blocked.attr,
	&dev_attr_type.attr,
	&dev_attr_scsi_level.attr,
	&dev_attr_vendor.attr,
	&dev_attr_model.attr,
	&dev_attr_rev.attr,
	&dev_attr_rescan.attr,
	&dev_attr_delete.attr,
	&dev_attr_state.attr,
	&dev_attr_timeout.attr,
	&dev_attr_iocounterbits.attr,
	&dev_attr_iorequest_cnt.attr,
	&dev_attr_iodone_cnt.attr,
	&dev_attr_ioerr_cnt.attr,
	&dev_attr_modalias.attr,
	REF_EVT(media_change),
	NULL
};

static struct attribute_group scsi_sdev_attr_group = {
	.attrs =	scsi_sdev_attrs,
};

static const struct attribute_group *scsi_sdev_attr_groups[] = {
	&scsi_sdev_attr_group,
	NULL
};

static ssize_t
sdev_store_queue_depth_rw(struct device *dev, struct device_attribute *attr,
			  const char *buf, size_t count)
{
	int depth, retval;
	struct scsi_device *sdev = to_scsi_device(dev);
	struct scsi_host_template *sht = sdev->host->hostt;

	if (!sht->change_queue_depth)
		return -EINVAL;

	depth = simple_strtoul(buf, NULL, 0);

	if (depth < 1)
		return -EINVAL;

	retval = sht->change_queue_depth(sdev, depth,
					 SCSI_QDEPTH_DEFAULT);
	if (retval < 0)
		return retval;

	sdev->max_queue_depth = sdev->queue_depth;

	return count;
}

static struct device_attribute sdev_attr_queue_depth_rw =
	__ATTR(queue_depth, S_IRUGO | S_IWUSR, sdev_show_queue_depth,
	       sdev_store_queue_depth_rw);

static ssize_t
sdev_show_queue_ramp_up_period(struct device *dev,
			       struct device_attribute *attr,
			       char *buf)
{
	struct scsi_device *sdev;
	sdev = to_scsi_device(dev);
	return snprintf(buf, 20, "%u\n",
			jiffies_to_msecs(sdev->queue_ramp_up_period));
}

static ssize_t
sdev_store_queue_ramp_up_period(struct device *dev,
				struct device_attribute *attr,
				const char *buf, size_t count)
{
	struct scsi_device *sdev = to_scsi_device(dev);
	unsigned long period;

	if (strict_strtoul(buf, 10, &period))
		return -EINVAL;

	sdev->queue_ramp_up_period = msecs_to_jiffies(period);
	return period;
}

static struct device_attribute sdev_attr_queue_ramp_up_period =
	__ATTR(queue_ramp_up_period, S_IRUGO | S_IWUSR,
	       sdev_show_queue_ramp_up_period,
	       sdev_store_queue_ramp_up_period);

static ssize_t
sdev_store_queue_type_rw(struct device *dev, struct device_attribute *attr,
			 const char *buf, size_t count)
{
	struct scsi_device *sdev = to_scsi_device(dev);
	struct scsi_host_template *sht = sdev->host->hostt;
	int tag_type = 0, retval;
	int prev_tag_type = scsi_get_tag_type(sdev);

	if (!sdev->tagged_supported || !sht->change_queue_type)
		return -EINVAL;

	if (strncmp(buf, "ordered", 7) == 0)
		tag_type = MSG_ORDERED_TAG;
	else if (strncmp(buf, "simple", 6) == 0)
		tag_type = MSG_SIMPLE_TAG;
	else if (strncmp(buf, "none", 4) != 0)
		return -EINVAL;

	if (tag_type == prev_tag_type)
		return count;

	retval = sht->change_queue_type(sdev, tag_type);
	if (retval < 0)
		return retval;

	return count;
}

static int scsi_target_add(struct scsi_target *starget)
{
	int error;

	if (starget->state != STARGET_CREATED)
		return 0;

	error = device_add(&starget->dev);
	if (error) {
		dev_err(&starget->dev, "target device_add failed, error %d\n", error);
		return error;
	}
	transport_add_device(&starget->dev);
	starget->state = STARGET_RUNNING;

	pm_runtime_set_active(&starget->dev);
	pm_runtime_enable(&starget->dev);
	device_enable_async_suspend(&starget->dev);

	return 0;
}

static struct device_attribute sdev_attr_queue_type_rw =
	__ATTR(queue_type, S_IRUGO | S_IWUSR, show_queue_type_field,
	       sdev_store_queue_type_rw);

/**
 * scsi_sysfs_add_sdev - add scsi device to sysfs
 * @sdev:	scsi_device to add
 *
 * Return value:
 * 	0 on Success / non-zero on Failure
 **/
int scsi_sysfs_add_sdev(struct scsi_device *sdev)
{
	int error, i;
	struct request_queue *rq = sdev->request_queue;
	struct scsi_target *starget = sdev->sdev_target;

	error = scsi_device_set_state(sdev, SDEV_RUNNING);
	if (error)
		return error;

	error = scsi_target_add(starget);
	if (error)
		return error;

	transport_configure_device(&starget->dev);

	device_enable_async_suspend(&sdev->sdev_gendev);
	scsi_autopm_get_target(starget);
	pm_runtime_set_active(&sdev->sdev_gendev);
	pm_runtime_forbid(&sdev->sdev_gendev);
	pm_runtime_enable(&sdev->sdev_gendev);
	scsi_autopm_put_target(starget);

	/* The following call will keep sdev active indefinitely, until
	 * its driver does a corresponding scsi_autopm_pm_device().  Only
	 * drivers supporting autosuspend will do this.
	 */
	scsi_autopm_get_device(sdev);

	error = device_add(&sdev->sdev_gendev);
	if (error) {
		sdev_printk(KERN_INFO, sdev,
				"failed to add device: %d\n", error);
		return error;
	}
	device_enable_async_suspend(&sdev->sdev_dev);
	error = device_add(&sdev->sdev_dev);
	if (error) {
		sdev_printk(KERN_INFO, sdev,
				"failed to add class device: %d\n", error);
		device_del(&sdev->sdev_gendev);
		return error;
	}
	transport_add_device(&sdev->sdev_gendev);
	sdev->is_visible = 1;

	/* create queue files, which may be writable, depending on the host */
	if (sdev->host->hostt->change_queue_depth) {
		error = device_create_file(&sdev->sdev_gendev,
					   &sdev_attr_queue_depth_rw);
		error = device_create_file(&sdev->sdev_gendev,
					   &sdev_attr_queue_ramp_up_period);
	}
	else
		error = device_create_file(&sdev->sdev_gendev, &dev_attr_queue_depth);
	if (error)
		return error;

	if (sdev->host->hostt->change_queue_type)
		error = device_create_file(&sdev->sdev_gendev, &sdev_attr_queue_type_rw);
	else
		error = device_create_file(&sdev->sdev_gendev, &dev_attr_queue_type);
	if (error)
		return error;

	error = bsg_register_queue(rq, &sdev->sdev_gendev, NULL, NULL);

	if (error)
		/* we're treating error on bsg register as non-fatal,
		 * so pretend nothing went wrong */
		sdev_printk(KERN_INFO, sdev,
			    "Failed to register bsg queue, errno=%d\n", error);

	/* add additional host specific attributes */
	if (sdev->host->hostt->sdev_attrs) {
		for (i = 0; sdev->host->hostt->sdev_attrs[i]; i++) {
			error = device_create_file(&sdev->sdev_gendev,
					sdev->host->hostt->sdev_attrs[i]);
			if (error)
				return error;
		}
	}

	return error;
}

void __scsi_remove_device(struct scsi_device *sdev)
{
	struct device *dev = &sdev->sdev_gendev;

	if (sdev->is_visible) {
		if (scsi_device_set_state(sdev, SDEV_CANCEL) != 0)
			return;

		bsg_unregister_queue(sdev->request_queue);
		device_unregister(&sdev->sdev_dev);
		transport_remove_device(dev);
		device_del(dev);
	} else
		put_device(&sdev->sdev_dev);
	scsi_device_set_state(sdev, SDEV_DEL);
	if (sdev->host->hostt->slave_destroy)
		sdev->host->hostt->slave_destroy(sdev);
	transport_destroy_device(dev);

	/* cause the request function to reject all I/O requests */
	sdev->request_queue->queuedata = NULL;

	/* Freeing the queue signals to block that we're done */
	scsi_free_queue(sdev->request_queue);
	put_device(dev);
}

/**
 * scsi_remove_device - unregister a device from the scsi bus
 * @sdev:	scsi_device to unregister
 **/
void scsi_remove_device(struct scsi_device *sdev)
{
	struct Scsi_Host *shost = sdev->host;

	mutex_lock(&shost->scan_mutex);
	__scsi_remove_device(sdev);
	mutex_unlock(&shost->scan_mutex);
}
EXPORT_SYMBOL(scsi_remove_device);

static void __scsi_remove_target(struct scsi_target *starget)
{
	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
	unsigned long flags;
	struct scsi_device *sdev;

	spin_lock_irqsave(shost->host_lock, flags);
	starget->reap_ref++;
 restart:
	list_for_each_entry(sdev, &shost->__devices, siblings) {
		if (sdev->channel != starget->channel ||
		    sdev->id != starget->id ||
		    scsi_device_get(sdev))
			continue;
		spin_unlock_irqrestore(shost->host_lock, flags);
		scsi_remove_device(sdev);
		scsi_device_put(sdev);
		spin_lock_irqsave(shost->host_lock, flags);
		goto restart;
	}
	spin_unlock_irqrestore(shost->host_lock, flags);
	scsi_target_reap(starget);
}

static int __remove_child (struct device * dev, void * data)
{
	if (scsi_is_target_device(dev))
		__scsi_remove_target(to_scsi_target(dev));
	return 0;
}

/**
 * scsi_remove_target - try to remove a target and all its devices
 * @dev: generic starget or parent of generic stargets to be removed
 *
 * Note: This is slightly racy.  It is possible that if the user
 * requests the addition of another device then the target won't be
 * removed.
 */
void scsi_remove_target(struct device *dev)
{
	if (scsi_is_target_device(dev)) {
		__scsi_remove_target(to_scsi_target(dev));
		return;
	}

	get_device(dev);
	device_for_each_child(dev, NULL, __remove_child);
	put_device(dev);
}
EXPORT_SYMBOL(scsi_remove_target);

int scsi_register_driver(struct device_driver *drv)
{
	drv->bus = &scsi_bus_type;

	return driver_register(drv);
}
EXPORT_SYMBOL(scsi_register_driver);

int scsi_register_interface(struct class_interface *intf)
{
	intf->class = &sdev_class;

	return class_interface_register(intf);
}
EXPORT_SYMBOL(scsi_register_interface);

/**
 * scsi_sysfs_add_host - add scsi host to subsystem
 * @shost:     scsi host struct to add to subsystem
 **/
int scsi_sysfs_add_host(struct Scsi_Host *shost)
{
	int error, i;

	/* add host specific attributes */
	if (shost->hostt->shost_attrs) {
		for (i = 0; shost->hostt->shost_attrs[i]; i++) {
			error = device_create_file(&shost->shost_dev,
					shost->hostt->shost_attrs[i]);
			if (error)
				return error;
		}
	}

	transport_register_device(&shost->shost_gendev);
	transport_configure_device(&shost->shost_gendev);
	return 0;
}

static struct device_type scsi_dev_type = {
	.name =		"scsi_device",
	.release =	scsi_device_dev_release,
	.groups =	scsi_sdev_attr_groups,
};

void scsi_sysfs_device_initialize(struct scsi_device *sdev)
{
	unsigned long flags;
	struct Scsi_Host *shost = sdev->host;
	struct scsi_target  *starget = sdev->sdev_target;

	device_initialize(&sdev->sdev_gendev);
	sdev->sdev_gendev.bus = &scsi_bus_type;
	sdev->sdev_gendev.type = &scsi_dev_type;
	dev_set_name(&sdev->sdev_gendev, "%d:%d:%d:%d",
		     sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);

	device_initialize(&sdev->sdev_dev);
	sdev->sdev_dev.parent = get_device(&sdev->sdev_gendev);
	sdev->sdev_dev.class = &sdev_class;
	dev_set_name(&sdev->sdev_dev, "%d:%d:%d:%d",
		     sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);
	sdev->scsi_level = starget->scsi_level;
	transport_setup_device(&sdev->sdev_gendev);
	spin_lock_irqsave(shost->host_lock, flags);
	list_add_tail(&sdev->same_target_siblings, &starget->devices);
	list_add_tail(&sdev->siblings, &shost->__devices);
	spin_unlock_irqrestore(shost->host_lock, flags);
}

int scsi_is_sdev_device(const struct device *dev)
{
	return dev->type == &scsi_dev_type;
}
EXPORT_SYMBOL(scsi_is_sdev_device);

/* A blank transport template that is used in drivers that don't
 * yet implement Transport Attributes */
struct scsi_transport_template blank_transport_template = { { { {NULL, }, }, }, };