/* 
 * 
 * linux/drivers/s390/scsi/zfcp_scsi.c
 * 
 * FCP adapter driver for IBM eServer zSeries 
 * 
 * (C) Copyright IBM Corp. 2002, 2004
 *
 * Author(s): Martin Peschke <mpeschke@de.ibm.com> 
 *            Raimund Schroeder <raimund.schroeder@de.ibm.com> 
 *            Aron Zeh
 *            Wolfgang Taphorn
 *            Stefan Bader <stefan.bader@de.ibm.com> 
 *            Heiko Carstens <heiko.carstens@de.ibm.com> 
 *            Andreas Herrmann <aherrman@de.ibm.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, 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., 675 Mass Ave, Cambridge, MA 02139, USA. 
 */

#define ZFCP_LOG_AREA			ZFCP_LOG_AREA_SCSI

#define ZFCP_SCSI_REVISION "$Revision: 1.74 $"

#include "zfcp_ext.h"

static void zfcp_scsi_slave_destroy(struct scsi_device *sdp);
static int zfcp_scsi_slave_alloc(struct scsi_device *sdp);
static int zfcp_scsi_slave_configure(struct scsi_device *sdp);
static int zfcp_scsi_queuecommand(struct scsi_cmnd *,
				  void (*done) (struct scsi_cmnd *));
static int zfcp_scsi_eh_abort_handler(struct scsi_cmnd *);
static int zfcp_scsi_eh_device_reset_handler(struct scsi_cmnd *);
static int zfcp_scsi_eh_bus_reset_handler(struct scsi_cmnd *);
static int zfcp_scsi_eh_host_reset_handler(struct scsi_cmnd *);
static int zfcp_task_management_function(struct zfcp_unit *, u8);

static struct zfcp_unit *zfcp_unit_lookup(struct zfcp_adapter *, int, scsi_id_t,
					  scsi_lun_t);
static struct zfcp_port *zfcp_port_lookup(struct zfcp_adapter *, int,
					  scsi_id_t);

static struct device_attribute *zfcp_sysfs_sdev_attrs[];

struct scsi_transport_template *zfcp_transport_template;

struct zfcp_data zfcp_data = {
	.scsi_host_template = {
	      name:	               ZFCP_NAME,
	      proc_name:               "zfcp",
	      proc_info:               NULL,
	      detect:	               NULL,
	      slave_alloc:             zfcp_scsi_slave_alloc,
	      slave_configure:         zfcp_scsi_slave_configure,
	      slave_destroy:           zfcp_scsi_slave_destroy,
	      queuecommand:            zfcp_scsi_queuecommand,
	      eh_abort_handler:        zfcp_scsi_eh_abort_handler,
	      eh_device_reset_handler: zfcp_scsi_eh_device_reset_handler,
	      eh_bus_reset_handler:    zfcp_scsi_eh_bus_reset_handler,
	      eh_host_reset_handler:   zfcp_scsi_eh_host_reset_handler,
			               /* FIXME(openfcp): Tune */
	      can_queue:               4096,
	      this_id:	               0,
	      /*
	       * FIXME:
	       * one less? can zfcp_create_sbale cope with it?
	       */
	      sg_tablesize:            ZFCP_MAX_SBALES_PER_REQ,
	      cmd_per_lun:             1,
	      unchecked_isa_dma:       0,
	      use_clustering:          1,
	      sdev_attrs:              zfcp_sysfs_sdev_attrs,
	},
	.driver_version = ZFCP_VERSION,
	/* rest initialised with zeros */
};

/* Find start of Response Information in FCP response unit*/
char *
zfcp_get_fcp_rsp_info_ptr(struct fcp_rsp_iu *fcp_rsp_iu)
{
	char *fcp_rsp_info_ptr;

	fcp_rsp_info_ptr =
	    (unsigned char *) fcp_rsp_iu + (sizeof (struct fcp_rsp_iu));

	return fcp_rsp_info_ptr;
}

/* Find start of Sense Information in FCP response unit*/
char *
zfcp_get_fcp_sns_info_ptr(struct fcp_rsp_iu *fcp_rsp_iu)
{
	char *fcp_sns_info_ptr;

	fcp_sns_info_ptr =
	    (unsigned char *) fcp_rsp_iu + (sizeof (struct fcp_rsp_iu));
	if (fcp_rsp_iu->validity.bits.fcp_rsp_len_valid)
		fcp_sns_info_ptr = (char *) fcp_sns_info_ptr +
		    fcp_rsp_iu->fcp_rsp_len;

	return fcp_sns_info_ptr;
}

fcp_dl_t *
zfcp_get_fcp_dl_ptr(struct fcp_cmnd_iu * fcp_cmd)
{
	int additional_length = fcp_cmd->add_fcp_cdb_length << 2;
	fcp_dl_t *fcp_dl_addr;

	fcp_dl_addr = (fcp_dl_t *)
		((unsigned char *) fcp_cmd +
		 sizeof (struct fcp_cmnd_iu) + additional_length);
	/*
	 * fcp_dl_addr = start address of fcp_cmnd structure + 
	 * size of fixed part + size of dynamically sized add_dcp_cdb field
	 * SEE FCP-2 documentation
	 */
	return fcp_dl_addr;
}

fcp_dl_t
zfcp_get_fcp_dl(struct fcp_cmnd_iu * fcp_cmd)
{
	return *zfcp_get_fcp_dl_ptr(fcp_cmd);
}

void
zfcp_set_fcp_dl(struct fcp_cmnd_iu *fcp_cmd, fcp_dl_t fcp_dl)
{
	*zfcp_get_fcp_dl_ptr(fcp_cmd) = fcp_dl;
}

/*
 * note: it's a bit-or operation not an assignment
 * regarding the specified byte
 */
static inline void
set_byte(u32 * result, char status, char pos)
{
	*result |= status << (pos * 8);
}

void
set_host_byte(u32 * result, char status)
{
	set_byte(result, status, 2);
}

void
set_driver_byte(u32 * result, char status)
{
	set_byte(result, status, 3);
}

/*
 * function:	zfcp_scsi_slave_alloc
 *
 * purpose:
 *
 * returns:
 */

static int
zfcp_scsi_slave_alloc(struct scsi_device *sdp)
{
	struct zfcp_adapter *adapter;
	struct zfcp_unit *unit;
	unsigned long flags;
	int retval = -ENODEV;

	adapter = (struct zfcp_adapter *) sdp->host->hostdata[0];
	if (!adapter)
		goto out;

	read_lock_irqsave(&zfcp_data.config_lock, flags);
	unit = zfcp_unit_lookup(adapter, sdp->channel, sdp->id, sdp->lun);
	if (unit) {
		sdp->hostdata = unit;
		unit->device = sdp;
		zfcp_unit_get(unit);
		retval = 0;
	}
	read_unlock_irqrestore(&zfcp_data.config_lock, flags);
 out:
	return retval;
}

/*
 * function:	zfcp_scsi_slave_destroy
 *
 * purpose:
 *
 * returns:
 */

static void
zfcp_scsi_slave_destroy(struct scsi_device *sdpnt)
{
	struct zfcp_unit *unit = (struct zfcp_unit *) sdpnt->hostdata;

	if (unit) {
		sdpnt->hostdata = NULL;
		unit->device = NULL;
		zfcp_unit_put(unit);
	} else {
		ZFCP_LOG_NORMAL("bug: no unit associated with SCSI device at "
				"address %p\n", sdpnt);
	}
}

/* 
 * called from scsi midlayer to allow finetuning of a device.
 */
static int
zfcp_scsi_slave_configure(struct scsi_device *sdp)
{
	if (sdp->tagged_supported)
		scsi_adjust_queue_depth(sdp, MSG_SIMPLE_TAG, ZFCP_CMND_PER_LUN);
	else
		scsi_adjust_queue_depth(sdp, 0, 1);
	return 0;
}

/**
 * zfcp_scsi_command_fail - set result in scsi_cmnd and call scsi_done function
 * @scpnt: pointer to struct scsi_cmnd where result is set
 * @result: result to be set in scpnt (e.g. DID_ERROR)
 */
static void
zfcp_scsi_command_fail(struct scsi_cmnd *scpnt, int result)
{
	set_host_byte(&scpnt->result, result);
	zfcp_cmd_dbf_event_scsi("failing", scpnt);
	/* return directly */
	scpnt->scsi_done(scpnt);
}

/**
 * zfcp_scsi_command_async - worker for zfcp_scsi_queuecommand and
 *	zfcp_scsi_command_sync
 * @adapter: adapter where scsi command is issued
 * @unit: unit to which scsi command is sent
 * @scpnt: scsi command to be sent
 * @timer: timer to be started if request is successfully initiated
 *
 * Note: In scsi_done function must be set in scpnt.
 */
int
zfcp_scsi_command_async(struct zfcp_adapter *adapter, struct zfcp_unit *unit,
			struct scsi_cmnd *scpnt, struct timer_list *timer)
{
	int tmp;
	int retval;

	retval = 0;

	BUG_ON((adapter == NULL) || (adapter != unit->port->adapter));
	BUG_ON(scpnt->scsi_done == NULL);

	if (unlikely(NULL == unit)) {
		zfcp_scsi_command_fail(scpnt, DID_NO_CONNECT);
		goto out;
	}

	if (unlikely(
	      atomic_test_mask(ZFCP_STATUS_COMMON_ERP_FAILED, &unit->status) ||
	     !atomic_test_mask(ZFCP_STATUS_COMMON_RUNNING, &unit->status))) {
		ZFCP_LOG_DEBUG("stopping SCSI I/O on unit 0x%016Lx on port "
			       "0x%016Lx on adapter %s\n",
			       unit->fcp_lun, unit->port->wwpn,
			       zfcp_get_busid_by_adapter(adapter));
		zfcp_scsi_command_fail(scpnt, DID_ERROR);
		goto out;
	}

	if (unlikely(
	     !atomic_test_mask(ZFCP_STATUS_COMMON_UNBLOCKED, &unit->status))) {
		ZFCP_LOG_DEBUG("adapter %s not ready or unit 0x%016Lx "
			       "on port 0x%016Lx in recovery\n",
			       zfcp_get_busid_by_unit(unit),
			       unit->fcp_lun, unit->port->wwpn);
		retval = SCSI_MLQUEUE_DEVICE_BUSY;
		goto out;
	}

	tmp = zfcp_fsf_send_fcp_command_task(adapter, unit, scpnt, timer,
					     ZFCP_REQ_AUTO_CLEANUP);

	if (unlikely(tmp < 0)) {
		ZFCP_LOG_DEBUG("error: initiation of Send FCP Cmnd failed\n");
		retval = SCSI_MLQUEUE_HOST_BUSY;
	}

out:
	return retval;
}

void
zfcp_scsi_command_sync_handler(struct scsi_cmnd *scpnt)
{
	struct completion *wait = (struct completion *) scpnt->SCp.ptr;
	complete(wait);
}


/**
 * zfcp_scsi_command_sync - send a SCSI command and wait for completion
 * @unit: unit where command is sent to
 * @scpnt: scsi command to be sent
 * @timer: timer to be started if request is successfully initiated
 * Return: 0
 *
 * Errors are indicated in scpnt->result
 */
int
zfcp_scsi_command_sync(struct zfcp_unit *unit, struct scsi_cmnd *scpnt,
		       struct timer_list *timer)
{
	int ret;
	DECLARE_COMPLETION(wait);

	scpnt->SCp.ptr = (void *) &wait;  /* silent re-use */
	scpnt->scsi_done = zfcp_scsi_command_sync_handler;
	ret = zfcp_scsi_command_async(unit->port->adapter, unit, scpnt, timer);
	if (ret == 0)
		wait_for_completion(&wait);

	scpnt->SCp.ptr = NULL;

	return 0;
}

/*
 * function:	zfcp_scsi_queuecommand
 *
 * purpose:	enqueues a SCSI command to the specified target device
 *
 * returns:	0 - success, SCSI command enqueued
 *		!0 - failure
 */
int
zfcp_scsi_queuecommand(struct scsi_cmnd *scpnt,
		       void (*done) (struct scsi_cmnd *))
{
	struct zfcp_unit *unit;
	struct zfcp_adapter *adapter;

	/* reset the status for this request */
	scpnt->result = 0;
	scpnt->host_scribble = NULL;
	scpnt->scsi_done = done;

	/*
	 * figure out adapter and target device
	 * (stored there by zfcp_scsi_slave_alloc)
	 */
	adapter = (struct zfcp_adapter *) scpnt->device->host->hostdata[0];
	unit = (struct zfcp_unit *) scpnt->device->hostdata;

	return zfcp_scsi_command_async(adapter, unit, scpnt, NULL);
}

/*
 * function:    zfcp_unit_lookup
 *
 * purpose:
 *
 * returns:
 *
 * context:	
 */
static struct zfcp_unit *
zfcp_unit_lookup(struct zfcp_adapter *adapter, int channel, scsi_id_t id,
		 scsi_lun_t lun)
{
	struct zfcp_port *port;
	struct zfcp_unit *unit, *retval = NULL;

	list_for_each_entry(port, &adapter->port_list_head, list) {
		if (id != port->scsi_id)
			continue;
		list_for_each_entry(unit, &port->unit_list_head, list) {
			if (lun == unit->scsi_lun) {
				retval = unit;
				goto out;
			}
		}
	}
 out:
	return retval;
}

static struct zfcp_port *
zfcp_port_lookup(struct zfcp_adapter *adapter, int channel, scsi_id_t id)
{
	struct zfcp_port *port;

	list_for_each_entry(port, &adapter->port_list_head, list) {
		if (id == port->scsi_id)
			return port;
	}
	return (struct zfcp_port *) NULL;
}

/*
 * function:	zfcp_scsi_eh_abort_handler
 *
 * purpose:	tries to abort the specified (timed out) SCSI command
 *
 * note: 	We do not need to care for a SCSI command which completes
 *		normally but late during this abort routine runs.
 *		We are allowed to return late commands to the SCSI stack.
 *		It tracks the state of commands and will handle late commands.
 *		(Usually, the normal completion of late commands is ignored with
 *		respect to the running abort operation. Grep for 'done_late'
 *		in the SCSI stacks sources.)
 *
 * returns:	SUCCESS	- command has been aborted and cleaned up in internal
 *			  bookkeeping,
 *			  SCSI stack won't be called for aborted command
 *		FAILED	- otherwise
 */
int
__zfcp_scsi_eh_abort_handler(struct scsi_cmnd *scpnt)
{
	int retval = SUCCESS;
	struct zfcp_fsf_req *new_fsf_req, *old_fsf_req;
	struct zfcp_adapter *adapter = (struct zfcp_adapter *) scpnt->device->host->hostdata[0];
	struct zfcp_unit *unit = (struct zfcp_unit *) scpnt->device->hostdata;
	struct zfcp_port *port = unit->port;
	struct Scsi_Host *scsi_host = scpnt->device->host;
	union zfcp_req_data *req_data = NULL;
	unsigned long flags;
	u32 status = 0;

	/* the components of a abort_dbf record (fixed size record) */
	u64 dbf_scsi_cmnd = (unsigned long) scpnt;
	char dbf_opcode[ZFCP_ABORT_DBF_LENGTH];
	wwn_t dbf_wwn = port->wwpn;
	fcp_lun_t dbf_fcp_lun = unit->fcp_lun;
	u64 dbf_retries = scpnt->retries;
	u64 dbf_allowed = scpnt->allowed;
	u64 dbf_timeout = 0;
	u64 dbf_fsf_req = 0;
	u64 dbf_fsf_status = 0;
	u64 dbf_fsf_qual[2] = { 0, 0 };
	char dbf_result[ZFCP_ABORT_DBF_LENGTH] = "##undef";

	memset(dbf_opcode, 0, ZFCP_ABORT_DBF_LENGTH);
	memcpy(dbf_opcode,
	       scpnt->cmnd,
	       min(scpnt->cmd_len, (unsigned char) ZFCP_ABORT_DBF_LENGTH));

	ZFCP_LOG_INFO("aborting scsi_cmnd=%p on adapter %s\n",
		      scpnt, zfcp_get_busid_by_adapter(adapter));

	spin_unlock_irq(scsi_host->host_lock);

	/*
	 * Race condition between normal (late) completion and abort has
	 * to be avoided.
	 * The entirity of all accesses to scsi_req have to be atomic.
	 * scsi_req is usually part of the fsf_req and thus we block the
	 * release of fsf_req as long as we need to access scsi_req.
	 */
	write_lock_irqsave(&adapter->abort_lock, flags);

	/*
	 * Check whether command has just completed and can not be aborted.
	 * Even if the command has just been completed late, we can access
	 * scpnt since the SCSI stack does not release it at least until
	 * this routine returns. (scpnt is parameter passed to this routine
	 * and must not disappear during abort even on late completion.)
	 */
	req_data = (union zfcp_req_data *) scpnt->host_scribble;
	/* DEBUG */
	ZFCP_LOG_DEBUG("req_data=%p\n", req_data);
	if (!req_data) {
		ZFCP_LOG_DEBUG("late command completion overtook abort\n");
		/*
		 * That's it.
		 * Do not initiate abort but return SUCCESS.
		 */
		write_unlock_irqrestore(&adapter->abort_lock, flags);
		retval = SUCCESS;
		strncpy(dbf_result, "##late1", ZFCP_ABORT_DBF_LENGTH);
		goto out;
	}

	/* Figure out which fsf_req needs to be aborted. */
	old_fsf_req = req_data->send_fcp_command_task.fsf_req;

	dbf_fsf_req = (unsigned long) old_fsf_req;
	dbf_timeout =
	    (jiffies - req_data->send_fcp_command_task.start_jiffies) / HZ;

	ZFCP_LOG_DEBUG("old_fsf_req=%p\n", old_fsf_req);
	if (!old_fsf_req) {
		write_unlock_irqrestore(&adapter->abort_lock, flags);
		ZFCP_LOG_NORMAL("bug: no old fsf request found\n");
		ZFCP_LOG_NORMAL("req_data:\n");
		ZFCP_HEX_DUMP(ZFCP_LOG_LEVEL_NORMAL,
			      (char *) req_data, sizeof (union zfcp_req_data));
		ZFCP_LOG_NORMAL("scsi_cmnd:\n");
		ZFCP_HEX_DUMP(ZFCP_LOG_LEVEL_NORMAL,
			      (char *) scpnt, sizeof (struct scsi_cmnd));
		retval = FAILED;
		strncpy(dbf_result, "##bug:r", ZFCP_ABORT_DBF_LENGTH);
		goto out;
	}
	old_fsf_req->data.send_fcp_command_task.scsi_cmnd = NULL;
	/* mark old request as being aborted */
	old_fsf_req->status |= ZFCP_STATUS_FSFREQ_ABORTING;
	/*
	 * We have to collect all information (e.g. unit) needed by 
	 * zfcp_fsf_abort_fcp_command before calling that routine
	 * since that routine is not allowed to access
	 * fsf_req which it is going to abort.
	 * This is because of we need to release fsf_req_list_lock
	 * before calling zfcp_fsf_abort_fcp_command.
	 * Since this lock will not be held, fsf_req may complete
	 * late and may be released meanwhile.
	 */
	ZFCP_LOG_DEBUG("unit 0x%016Lx (%p)\n", unit->fcp_lun, unit);

	/*
	 * We block (call schedule)
	 * That's why we must release the lock and enable the
	 * interrupts before.
	 * On the other hand we do not need the lock anymore since
	 * all critical accesses to scsi_req are done.
	 */
	write_unlock_irqrestore(&adapter->abort_lock, flags);
	/* call FSF routine which does the abort */
	new_fsf_req = zfcp_fsf_abort_fcp_command((unsigned long) old_fsf_req,
						 adapter, unit, 0);
	ZFCP_LOG_DEBUG("new_fsf_req=%p\n", new_fsf_req);
	if (!new_fsf_req) {
		retval = FAILED;
		ZFCP_LOG_NORMAL("error: initiation of Abort FCP Cmnd "
				"failed\n");
		strncpy(dbf_result, "##nores", ZFCP_ABORT_DBF_LENGTH);
		goto out;
	}

	/* wait for completion of abort */
	ZFCP_LOG_DEBUG("waiting for cleanup...\n");
#if 1
	/*
	 * FIXME:
	 * copying zfcp_fsf_req_wait_and_cleanup code is not really nice
	 */
	__wait_event(new_fsf_req->completion_wq,
		     new_fsf_req->status & ZFCP_STATUS_FSFREQ_COMPLETED);
	status = new_fsf_req->status;
	dbf_fsf_status = new_fsf_req->qtcb->header.fsf_status;
	/*
	 * Ralphs special debug load provides timestamps in the FSF
	 * status qualifier. This might be specified later if being
	 * useful for debugging aborts.
	 */
	dbf_fsf_qual[0] =
	    *(u64 *) & new_fsf_req->qtcb->header.fsf_status_qual.word[0];
	dbf_fsf_qual[1] =
	    *(u64 *) & new_fsf_req->qtcb->header.fsf_status_qual.word[2];
	zfcp_fsf_req_free(new_fsf_req);
#else
	retval = zfcp_fsf_req_wait_and_cleanup(new_fsf_req,
					       ZFCP_UNINTERRUPTIBLE, &status);
#endif
	ZFCP_LOG_DEBUG("Waiting for cleanup complete, status=0x%x\n", status);
	/* status should be valid since signals were not permitted */
	if (status & ZFCP_STATUS_FSFREQ_ABORTSUCCEEDED) {
		retval = SUCCESS;
		strncpy(dbf_result, "##succ", ZFCP_ABORT_DBF_LENGTH);
	} else if (status & ZFCP_STATUS_FSFREQ_ABORTNOTNEEDED) {
		retval = SUCCESS;
		strncpy(dbf_result, "##late2", ZFCP_ABORT_DBF_LENGTH);
	} else {
		retval = FAILED;
		strncpy(dbf_result, "##fail", ZFCP_ABORT_DBF_LENGTH);
	}

 out:
	debug_event(adapter->abort_dbf, 1, &dbf_scsi_cmnd, sizeof (u64));
	debug_event(adapter->abort_dbf, 1, &dbf_opcode, ZFCP_ABORT_DBF_LENGTH);
	debug_event(adapter->abort_dbf, 1, &dbf_wwn, sizeof (wwn_t));
	debug_event(adapter->abort_dbf, 1, &dbf_fcp_lun, sizeof (fcp_lun_t));
	debug_event(adapter->abort_dbf, 1, &dbf_retries, sizeof (u64));
	debug_event(adapter->abort_dbf, 1, &dbf_allowed, sizeof (u64));
	debug_event(adapter->abort_dbf, 1, &dbf_timeout, sizeof (u64));
	debug_event(adapter->abort_dbf, 1, &dbf_fsf_req, sizeof (u64));
	debug_event(adapter->abort_dbf, 1, &dbf_fsf_status, sizeof (u64));
	debug_event(adapter->abort_dbf, 1, &dbf_fsf_qual[0], sizeof (u64));
	debug_event(adapter->abort_dbf, 1, &dbf_fsf_qual[1], sizeof (u64));
	debug_text_event(adapter->abort_dbf, 1, dbf_result);

	spin_lock_irq(scsi_host->host_lock);
	return retval;
}

int
zfcp_scsi_eh_abort_handler(struct scsi_cmnd *scpnt)
{
	int rc;
	struct Scsi_Host *scsi_host = scpnt->device->host;
	spin_lock_irq(scsi_host->host_lock);
	rc = __zfcp_scsi_eh_abort_handler(scpnt);
	spin_unlock_irq(scsi_host->host_lock);
	return rc;
}

/*
 * function:	zfcp_scsi_eh_device_reset_handler
 *
 * purpose:
 *
 * returns:
 */
int
zfcp_scsi_eh_device_reset_handler(struct scsi_cmnd *scpnt)
{
	int retval;
	struct zfcp_unit *unit = (struct zfcp_unit *) scpnt->device->hostdata;
	struct Scsi_Host *scsi_host = scpnt->device->host;

	if (!unit) {
		ZFCP_LOG_NORMAL("bug: Tried reset for nonexistent unit\n");
		retval = SUCCESS;
		goto out;
	}
	ZFCP_LOG_NORMAL("resetting unit 0x%016Lx\n", unit->fcp_lun);

	/*
	 * If we do not know whether the unit supports 'logical unit reset'
	 * then try 'logical unit reset' and proceed with 'target reset'
	 * if 'logical unit reset' fails.
	 * If the unit is known not to support 'logical unit reset' then
	 * skip 'logical unit reset' and try 'target reset' immediately.
	 */
	if (!atomic_test_mask(ZFCP_STATUS_UNIT_NOTSUPPUNITRESET,
			      &unit->status)) {
		retval =
		    zfcp_task_management_function(unit, FCP_LOGICAL_UNIT_RESET);
		if (retval) {
			ZFCP_LOG_DEBUG("unit reset failed (unit=%p)\n", unit);
			if (retval == -ENOTSUPP)
				atomic_set_mask
				    (ZFCP_STATUS_UNIT_NOTSUPPUNITRESET,
				     &unit->status);
			/* fall through and try 'target reset' next */
		} else {
			ZFCP_LOG_DEBUG("unit reset succeeded (unit=%p)\n",
				       unit);
			/* avoid 'target reset' */
			retval = SUCCESS;
			goto out;
		}
	}
	retval = zfcp_task_management_function(unit, FCP_TARGET_RESET);
	if (retval) {
		ZFCP_LOG_DEBUG("target reset failed (unit=%p)\n", unit);
		retval = FAILED;
	} else {
		ZFCP_LOG_DEBUG("target reset succeeded (unit=%p)\n", unit);
		retval = SUCCESS;
	}
 out:
	return retval;
}

static int
zfcp_task_management_function(struct zfcp_unit *unit, u8 tm_flags)
{
	struct zfcp_adapter *adapter = unit->port->adapter;
	int retval;
	int status;
	struct zfcp_fsf_req *fsf_req;

	/* issue task management function */
	fsf_req = zfcp_fsf_send_fcp_command_task_management
		(adapter, unit, tm_flags, 0);
	if (!fsf_req) {
		ZFCP_LOG_INFO("error: creation of task management request "
			      "failed for unit 0x%016Lx on port 0x%016Lx on  "
			      "adapter %s\n", unit->fcp_lun, unit->port->wwpn,
			      zfcp_get_busid_by_adapter(adapter));
		retval = -ENOMEM;
		goto out;
	}

	retval = zfcp_fsf_req_wait_and_cleanup(fsf_req,
					       ZFCP_UNINTERRUPTIBLE, &status);
	/*
	 * check completion status of task management function
	 * (status should always be valid since no signals permitted)
	 */
	if (status & ZFCP_STATUS_FSFREQ_TMFUNCFAILED)
		retval = -EIO;
	else if (status & ZFCP_STATUS_FSFREQ_TMFUNCNOTSUPP)
		retval = -ENOTSUPP;
	else
		retval = 0;
 out:
	return retval;
}

/*
 * function:	zfcp_scsi_eh_bus_reset_handler
 *
 * purpose:
 *
 * returns:
 */
int
zfcp_scsi_eh_bus_reset_handler(struct scsi_cmnd *scpnt)
{
	int retval = 0;
	struct zfcp_unit *unit;
	struct Scsi_Host *scsi_host = scpnt->device->host;

	unit = (struct zfcp_unit *) scpnt->device->hostdata;
	ZFCP_LOG_NORMAL("bus reset because of problems with "
			"unit 0x%016Lx\n", unit->fcp_lun);
	zfcp_erp_adapter_reopen(unit->port->adapter, 0);
	zfcp_erp_wait(unit->port->adapter);
	retval = SUCCESS;

	return retval;
}

/*
 * function:	zfcp_scsi_eh_host_reset_handler
 *
 * purpose:
 *
 * returns:
 */
int
zfcp_scsi_eh_host_reset_handler(struct scsi_cmnd *scpnt)
{
	int retval = 0;
	struct zfcp_unit *unit;
	struct Scsi_Host *scsi_host = scpnt->device->host;

	unit = (struct zfcp_unit *) scpnt->device->hostdata;
	ZFCP_LOG_NORMAL("host reset because of problems with "
			"unit 0x%016Lx\n", unit->fcp_lun);
	zfcp_erp_adapter_reopen(unit->port->adapter, 0);
	zfcp_erp_wait(unit->port->adapter);
	retval = SUCCESS;

	return retval;
}

/*
 * function:	
 *
 * purpose:	
 *
 * returns:
 */
int
zfcp_adapter_scsi_register(struct zfcp_adapter *adapter)
{
	int retval = 0;
	static unsigned int unique_id = 0;

	/* register adapter as SCSI host with mid layer of SCSI stack */
	adapter->scsi_host = scsi_host_alloc(&zfcp_data.scsi_host_template,
					     sizeof (struct zfcp_adapter *));
	if (!adapter->scsi_host) {
		ZFCP_LOG_NORMAL("error: registration with SCSI stack failed "
				"for adapter %s ",
				zfcp_get_busid_by_adapter(adapter));
		retval = -EIO;
		goto out;
	}
	ZFCP_LOG_DEBUG("host registered, scsi_host=%p\n", adapter->scsi_host);

	/* tell the SCSI stack some characteristics of this adapter */
	adapter->scsi_host->max_id = 1;
	adapter->scsi_host->max_lun = 1;
	adapter->scsi_host->max_channel = 0;
	adapter->scsi_host->unique_id = unique_id++;	/* FIXME */
	adapter->scsi_host->max_cmd_len = ZFCP_MAX_SCSI_CMND_LENGTH;
	adapter->scsi_host->transportt = zfcp_transport_template;
	/*
	 * Reverse mapping of the host number to avoid race condition
	 */
	adapter->scsi_host_no = adapter->scsi_host->host_no;

	/*
	 * save a pointer to our own adapter data structure within
	 * hostdata field of SCSI host data structure
	 */
	adapter->scsi_host->hostdata[0] = (unsigned long) adapter;

	if (scsi_add_host(adapter->scsi_host, &adapter->ccw_device->dev)) {
		scsi_host_put(adapter->scsi_host);
		retval = -EIO;
		goto out;
	}
	atomic_set_mask(ZFCP_STATUS_ADAPTER_REGISTERED, &adapter->status);
 out:
	return retval;
}

/*
 * function:	
 *
 * purpose:	
 *
 * returns:
 */
void
zfcp_adapter_scsi_unregister(struct zfcp_adapter *adapter)
{
	struct Scsi_Host *shost;

	shost = adapter->scsi_host;
	if (!shost)
		return;
	scsi_remove_host(shost);
	scsi_host_put(shost);
	adapter->scsi_host = NULL;
	adapter->scsi_host_no = 0;
	atomic_clear_mask(ZFCP_STATUS_ADAPTER_REGISTERED, &adapter->status);

	return;
}


void
zfcp_fsf_start_scsi_er_timer(struct zfcp_adapter *adapter)
{
	adapter->scsi_er_timer.function = zfcp_fsf_scsi_er_timeout_handler;
	adapter->scsi_er_timer.data = (unsigned long) adapter;
	adapter->scsi_er_timer.expires = jiffies + ZFCP_SCSI_ER_TIMEOUT;
	add_timer(&adapter->scsi_er_timer);
}

/*
 * Support functions for FC transport class
 */
static void
zfcp_get_port_id(struct scsi_target *starget)
{
	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
	struct zfcp_adapter *adapter = (struct zfcp_adapter *)shost->hostdata[0];
	struct zfcp_port *port;
	unsigned long flags;

	read_lock_irqsave(&zfcp_data.config_lock, flags);
	port = zfcp_port_lookup(adapter, starget->channel, starget->id);
	if (port)
		fc_starget_port_id(starget) = port->d_id;
	else
		fc_starget_port_id(starget) = -1;
	read_unlock_irqrestore(&zfcp_data.config_lock, flags);
}

static void
zfcp_get_port_name(struct scsi_target *starget)
{
	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
	struct zfcp_adapter *adapter = (struct zfcp_adapter *)shost->hostdata[0];
	struct zfcp_port *port;
	unsigned long flags;

	read_lock_irqsave(&zfcp_data.config_lock, flags);
	port = zfcp_port_lookup(adapter, starget->channel, starget->id);
	if (port)
		fc_starget_port_name(starget) = port->wwpn;
	else
		fc_starget_port_name(starget) = -1;
	read_unlock_irqrestore(&zfcp_data.config_lock, flags);
}

static void
zfcp_get_node_name(struct scsi_target *starget)
{
	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
	struct zfcp_adapter *adapter = (struct zfcp_adapter *)shost->hostdata[0];
	struct zfcp_port *port;
	unsigned long flags;

	read_lock_irqsave(&zfcp_data.config_lock, flags);
	port = zfcp_port_lookup(adapter, starget->channel, starget->id);
	if (port)
		fc_starget_node_name(starget) = port->wwnn;
	else
		fc_starget_node_name(starget) = -1;
	read_unlock_irqrestore(&zfcp_data.config_lock, flags);
}

struct fc_function_template zfcp_transport_functions = {
	.get_starget_port_id = zfcp_get_port_id,
	.get_starget_port_name = zfcp_get_port_name,
	.get_starget_node_name = zfcp_get_node_name,
	.show_starget_port_id = 1,
	.show_starget_port_name = 1,
	.show_starget_node_name = 1,
};

/**
 * ZFCP_DEFINE_SCSI_ATTR
 * @_name:   name of show attribute
 * @_format: format string
 * @_value:  value to print
 *
 * Generates attribute for a unit.
 */
#define ZFCP_DEFINE_SCSI_ATTR(_name, _format, _value)                    \
static ssize_t zfcp_sysfs_scsi_##_name##_show(struct device *dev, struct device_attribute *attr,        \
                                              char *buf)                 \
{                                                                        \
        struct scsi_device *sdev;                                        \
        struct zfcp_unit *unit;                                          \
                                                                         \
        sdev = to_scsi_device(dev);                                      \
        unit = sdev->hostdata;                                           \
        return sprintf(buf, _format, _value);                            \
}                                                                        \
                                                                         \
static DEVICE_ATTR(_name, S_IRUGO, zfcp_sysfs_scsi_##_name##_show, NULL);

ZFCP_DEFINE_SCSI_ATTR(hba_id, "%s\n", zfcp_get_busid_by_unit(unit));
ZFCP_DEFINE_SCSI_ATTR(wwpn, "0x%016llx\n", unit->port->wwpn);
ZFCP_DEFINE_SCSI_ATTR(fcp_lun, "0x%016llx\n", unit->fcp_lun);

static struct device_attribute *zfcp_sysfs_sdev_attrs[] = {
	&dev_attr_fcp_lun,
	&dev_attr_wwpn,
	&dev_attr_hba_id,
	NULL
};

#undef ZFCP_LOG_AREA