drivers/s390/scsi/zfcp_qdio.c - kernel/msm-4.9 - Gitiles

 /*
  * This file is part of the zfcp device driver for
  * FCP adapters for IBM System z9 and zSeries.
  *
  * (C) Copyright IBM Corp. 2002, 2006
  *
  * 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.
  */

 #include "zfcp_ext.h"

 static void zfcp_qdio_sbal_limit(struct zfcp_fsf_req *, int);
 static inline volatile struct qdio_buffer_element *zfcp_qdio_sbale_get
 	(struct zfcp_qdio_queue *, int, int);
 static inline volatile struct qdio_buffer_element *zfcp_qdio_sbale_resp
 	(struct zfcp_fsf_req *, int, int);
 static volatile struct qdio_buffer_element *zfcp_qdio_sbal_chain
 	(struct zfcp_fsf_req *, unsigned long);
 static volatile struct qdio_buffer_element *zfcp_qdio_sbale_next
 	(struct zfcp_fsf_req *, unsigned long);
 static int zfcp_qdio_sbals_zero(struct zfcp_qdio_queue *, int, int);
 static inline int zfcp_qdio_sbals_wipe(struct zfcp_fsf_req *);
 static void zfcp_qdio_sbale_fill
 	(struct zfcp_fsf_req *, unsigned long, void *, int);
 static int zfcp_qdio_sbals_from_segment
 	(struct zfcp_fsf_req *, unsigned long, void *, unsigned long);

 static qdio_handler_t zfcp_qdio_request_handler;
 static qdio_handler_t zfcp_qdio_response_handler;
 static int zfcp_qdio_handler_error_check(struct zfcp_adapter *,
 	unsigned int, unsigned int, unsigned int, int, int);

 #define ZFCP_LOG_AREA                   ZFCP_LOG_AREA_QDIO

 /*
  * Frees BUFFER memory for each of the pointers of the struct qdio_buffer array
  * in the adapter struct sbuf is the pointer array.
  *
  * locks:       must only be called with zfcp_data.config_sema taken
  */
 static void
 zfcp_qdio_buffers_dequeue(struct qdio_buffer **sbuf)
 {
 	int pos;

 	for (pos = 0; pos < QDIO_MAX_BUFFERS_PER_Q; pos += QBUFF_PER_PAGE)
 		free_page((unsigned long) sbuf[pos]);
 }

 /*
  * Allocates BUFFER memory to each of the pointers of the qdio_buffer_t
  * array in the adapter struct.
  * Cur_buf is the pointer array
  *
  * returns:	zero on success else -ENOMEM
  * locks:       must only be called with zfcp_data.config_sema taken
  */
 static int
 zfcp_qdio_buffers_enqueue(struct qdio_buffer **sbuf)
 {
 	int pos;

 	for (pos = 0; pos < QDIO_MAX_BUFFERS_PER_Q; pos += QBUFF_PER_PAGE) {
 		sbuf[pos] = (struct qdio_buffer *) get_zeroed_page(GFP_KERNEL);
 		if (!sbuf[pos]) {
 			zfcp_qdio_buffers_dequeue(sbuf);
 			return -ENOMEM;
 		}
 	}
 	for (pos = 0; pos < QDIO_MAX_BUFFERS_PER_Q; pos++)
 		if (pos % QBUFF_PER_PAGE)
 			sbuf[pos] = sbuf[pos - 1] + 1;
 	return 0;
 }

 /* locks:       must only be called with zfcp_data.config_sema taken */
 int
 zfcp_qdio_allocate_queues(struct zfcp_adapter *adapter)
 {
 	int ret;

 	ret = zfcp_qdio_buffers_enqueue(adapter->request_queue.buffer);
 	if (ret)
 		return ret;
 	return zfcp_qdio_buffers_enqueue(adapter->response_queue.buffer);
 }

 /* locks:       must only be called with zfcp_data.config_sema taken */
 void
 zfcp_qdio_free_queues(struct zfcp_adapter *adapter)
 {
 	ZFCP_LOG_TRACE("freeing request_queue buffers\n");
 	zfcp_qdio_buffers_dequeue(adapter->request_queue.buffer);

 	ZFCP_LOG_TRACE("freeing response_queue buffers\n");
 	zfcp_qdio_buffers_dequeue(adapter->response_queue.buffer);
 }

 int
 zfcp_qdio_allocate(struct zfcp_adapter *adapter)
 {
 	struct qdio_initialize *init_data;

 	init_data = &adapter->qdio_init_data;

 	init_data->cdev = adapter->ccw_device;
 	init_data->q_format = QDIO_SCSI_QFMT;
 	memcpy(init_data->adapter_name, zfcp_get_busid_by_adapter(adapter), 8);
 	ASCEBC(init_data->adapter_name, 8);
 	init_data->qib_param_field_format = 0;
 	init_data->qib_param_field = NULL;
 	init_data->input_slib_elements = NULL;
 	init_data->output_slib_elements = NULL;
 	init_data->min_input_threshold = ZFCP_MIN_INPUT_THRESHOLD;
 	init_data->max_input_threshold = ZFCP_MAX_INPUT_THRESHOLD;
 	init_data->min_output_threshold = ZFCP_MIN_OUTPUT_THRESHOLD;
 	init_data->max_output_threshold = ZFCP_MAX_OUTPUT_THRESHOLD;
 	init_data->no_input_qs = 1;
 	init_data->no_output_qs = 1;
 	init_data->input_handler = zfcp_qdio_response_handler;
 	init_data->output_handler = zfcp_qdio_request_handler;
 	init_data->int_parm = (unsigned long) adapter;
 	init_data->flags = QDIO_INBOUND_0COPY_SBALS |
 	    QDIO_OUTBOUND_0COPY_SBALS | QDIO_USE_OUTBOUND_PCIS;
 	init_data->input_sbal_addr_array =
 	    (void **) (adapter->response_queue.buffer);
 	init_data->output_sbal_addr_array =
 	    (void **) (adapter->request_queue.buffer);

 	return qdio_allocate(init_data);
 }

 /*
  * function:   	zfcp_qdio_handler_error_check
  *
  * purpose:     called by the response handler to determine error condition
  *
  * returns:	error flag
  *
  */
 static int
 zfcp_qdio_handler_error_check(struct zfcp_adapter *adapter, unsigned int status,
 			      unsigned int qdio_error, unsigned int siga_error,
 			      int first_element, int elements_processed)
 {
 	int retval = 0;

 	if (unlikely(status & QDIO_STATUS_LOOK_FOR_ERROR)) {
 		retval = -EIO;

 		ZFCP_LOG_INFO("QDIO problem occurred (status=0x%x, "
 			      "qdio_error=0x%x, siga_error=0x%x)\n",
 			      status, qdio_error, siga_error);

 		zfcp_hba_dbf_event_qdio(adapter, status, qdio_error, siga_error,
 				first_element, elements_processed);
                /*
                	* Restarting IO on the failed adapter from scratch.
                 * Since we have been using this adapter, it is save to assume
                 * that it is not failed but recoverable. The card seems to
                 * report link-up events by self-initiated queue shutdown.
                 * That is why we need to clear the link-down flag
                 * which is set again in case we have missed by a mile.
                 */
 		zfcp_erp_adapter_reopen(adapter,
 				       ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED |
 				       ZFCP_STATUS_COMMON_ERP_FAILED);
 	}
 	return retval;
 }

 /*
  * function:    zfcp_qdio_request_handler
  *
  * purpose:	is called by QDIO layer for completed SBALs in request queue
  *
  * returns:	(void)
  */
 static void
 zfcp_qdio_request_handler(struct ccw_device *ccw_device,
 			  unsigned int status,
 			  unsigned int qdio_error,
 			  unsigned int siga_error,
 			  unsigned int queue_number,
 			  int first_element,
 			  int elements_processed,
 			  unsigned long int_parm)
 {
 	struct zfcp_adapter *adapter;
 	struct zfcp_qdio_queue *queue;

 	adapter = (struct zfcp_adapter *) int_parm;
 	queue = &adapter->request_queue;

 	ZFCP_LOG_DEBUG("adapter %s, first=%d, elements_processed=%d\n",
 		       zfcp_get_busid_by_adapter(adapter),
 		       first_element, elements_processed);

 	if (unlikely(zfcp_qdio_handler_error_check(adapter, status, qdio_error,
 						   siga_error, first_element,
 						   elements_processed)))
 		goto out;
 	/*
 	 * we stored address of struct zfcp_adapter  data structure
 	 * associated with irq in int_parm
 	 */

 	/* cleanup all SBALs being program-owned now */
 	zfcp_qdio_zero_sbals(queue->buffer, first_element, elements_processed);

 	/* increase free space in outbound queue */
 	atomic_add(elements_processed, &queue->free_count);
 	ZFCP_LOG_DEBUG("free_count=%d\n", atomic_read(&queue->free_count));
 	wake_up(&adapter->request_wq);
 	ZFCP_LOG_DEBUG("elements_processed=%d, free count=%d\n",
 		       elements_processed, atomic_read(&queue->free_count));
  out:
 	return;
 }

 /**
  * zfcp_qdio_reqid_check - checks for valid reqids.
  */
 static void zfcp_qdio_reqid_check(struct zfcp_adapter *adapter,
 				  unsigned long req_id)
 {
 	struct zfcp_fsf_req *fsf_req;
 	unsigned long flags;

 	debug_long_event(adapter->erp_dbf, 4, req_id);

 	spin_lock_irqsave(&adapter->req_list_lock, flags);
 	fsf_req = zfcp_reqlist_find(adapter, req_id);

 	if (!fsf_req)
 		/*
 		 * Unknown request means that we have potentially memory
 		 * corruption and must stop the machine immediatly.
 		 */
 		panic("error: unknown request id (%ld) on adapter %s.\n",
 		      req_id, zfcp_get_busid_by_adapter(adapter));

 	zfcp_reqlist_remove(adapter, fsf_req);
 	atomic_dec(&adapter->reqs_active);
 	spin_unlock_irqrestore(&adapter->req_list_lock, flags);

 	/* finish the FSF request */
 	zfcp_fsf_req_complete(fsf_req);
 }

 /*
  * function:   	zfcp_qdio_response_handler
  *
  * purpose:	is called by QDIO layer for completed SBALs in response queue
  *
  * returns:	(void)
  */
 static void
 zfcp_qdio_response_handler(struct ccw_device *ccw_device,
 			   unsigned int status,
 			   unsigned int qdio_error,
 			   unsigned int siga_error,
 			   unsigned int queue_number,
 			   int first_element,
 			   int elements_processed,
 			   unsigned long int_parm)
 {
 	struct zfcp_adapter *adapter;
 	struct zfcp_qdio_queue *queue;
 	int buffer_index;
 	int i;
 	struct qdio_buffer *buffer;
 	int retval = 0;
 	u8 count;
 	u8 start;
 	volatile struct qdio_buffer_element *buffere = NULL;
 	int buffere_index;

 	adapter = (struct zfcp_adapter *) int_parm;
 	queue = &adapter->response_queue;

 	if (unlikely(zfcp_qdio_handler_error_check(adapter, status, qdio_error,
 						   siga_error, first_element,
 						   elements_processed)))
 		goto out;

 	/*
 	 * we stored address of struct zfcp_adapter  data structure
 	 * associated with irq in int_parm
 	 */

 	buffere = &(queue->buffer[first_element]->element[0]);
 	ZFCP_LOG_DEBUG("first BUFFERE flags=0x%x\n", buffere->flags);
 	/*
 	 * go through all SBALs from input queue currently
 	 * returned by QDIO layer
 	 */

 	for (i = 0; i < elements_processed; i++) {

 		buffer_index = first_element + i;
 		buffer_index %= QDIO_MAX_BUFFERS_PER_Q;
 		buffer = queue->buffer[buffer_index];

 		/* go through all SBALEs of SBAL */
 		for (buffere_index = 0;
 		     buffere_index < QDIO_MAX_ELEMENTS_PER_BUFFER;
 		     buffere_index++) {

 			/* look for QDIO request identifiers in SB */
 			buffere = &buffer->element[buffere_index];
 			zfcp_qdio_reqid_check(adapter,
 					      (unsigned long) buffere->addr);

 			/*
 			 * A single used SBALE per inbound SBALE has been
 			 * implemented by QDIO so far. Hope they will
 			 * do some optimisation. Will need to change to
 			 * unlikely() then.
 			 */
 			if (likely(buffere->flags & SBAL_FLAGS_LAST_ENTRY))
 				break;
 		};

 		if (unlikely(!(buffere->flags & SBAL_FLAGS_LAST_ENTRY))) {
 			ZFCP_LOG_NORMAL("bug: End of inbound data "
 					"not marked!\n");
 		}
 	}

 	/*
 	 * put range of SBALs back to response queue
 	 * (including SBALs which have already been free before)
 	 */
 	count = atomic_read(&queue->free_count) + elements_processed;
 	start = queue->free_index;

 	ZFCP_LOG_TRACE("calling do_QDIO on adapter %s (flags=0x%x, "
 		       "queue_no=%i, index_in_queue=%i, count=%i, "
 		       "buffers=0x%lx\n",
 		       zfcp_get_busid_by_adapter(adapter),
 		       QDIO_FLAG_SYNC_INPUT | QDIO_FLAG_UNDER_INTERRUPT,
 		       0, start, count, (unsigned long) &queue->buffer[start]);

 	retval = do_QDIO(ccw_device,
 			 QDIO_FLAG_SYNC_INPUT | QDIO_FLAG_UNDER_INTERRUPT,
 			 0, start, count, NULL);

 	if (unlikely(retval)) {
 		atomic_set(&queue->free_count, count);
 		ZFCP_LOG_DEBUG("clearing of inbound data regions failed, "
 			       "queues may be down "
 			       "(count=%d, start=%d, retval=%d)\n",
 			       count, start, retval);
 	} else {
 		queue->free_index += count;
 		queue->free_index %= QDIO_MAX_BUFFERS_PER_Q;
 		atomic_set(&queue->free_count, 0);
 		ZFCP_LOG_TRACE("%i buffers enqueued to response "
 			       "queue at position %i\n", count, start);
 	}
  out:
 	return;
 }

 /**
  * zfcp_qdio_sbale_get - return pointer to SBALE of qdio_queue
  * @queue: queue from which SBALE should be returned
  * @sbal: specifies number of SBAL in queue
  * @sbale: specifes number of SBALE in SBAL
  */
 static inline volatile struct qdio_buffer_element *
 zfcp_qdio_sbale_get(struct zfcp_qdio_queue *queue, int sbal, int sbale)
 {
 	return &queue->buffer[sbal]->element[sbale];
 }

 /**
  * zfcp_qdio_sbale_req - return pointer to SBALE of request_queue for
  *	a struct zfcp_fsf_req
  */
 volatile struct qdio_buffer_element *
 zfcp_qdio_sbale_req(struct zfcp_fsf_req *fsf_req, int sbal, int sbale)
 {
 	return zfcp_qdio_sbale_get(&fsf_req->adapter->request_queue,
 				   sbal, sbale);
 }

 /**
  * zfcp_qdio_sbale_resp - return pointer to SBALE of response_queue for
  *	a struct zfcp_fsf_req
  */
 static inline volatile struct qdio_buffer_element *
 zfcp_qdio_sbale_resp(struct zfcp_fsf_req *fsf_req, int sbal, int sbale)
 {
 	return zfcp_qdio_sbale_get(&fsf_req->adapter->response_queue,
 				   sbal, sbale);
 }

 /**
  * zfcp_qdio_sbale_curr - return current SBALE on request_queue for
  *	a struct zfcp_fsf_req
  */
 volatile struct qdio_buffer_element *
 zfcp_qdio_sbale_curr(struct zfcp_fsf_req *fsf_req)
 {
 	return zfcp_qdio_sbale_req(fsf_req, fsf_req->sbal_curr,
 				   fsf_req->sbale_curr);
 }

 /**
  * zfcp_qdio_sbal_limit - determine maximum number of SBALs that can be used
  *	on the request_queue for a struct zfcp_fsf_req
  * @fsf_req: the number of the last SBAL that can be used is stored herein
  * @max_sbals: used to pass an upper limit for the number of SBALs
  *
  * Note: We can assume at least one free SBAL in the request_queue when called.
  */
 static void
 zfcp_qdio_sbal_limit(struct zfcp_fsf_req *fsf_req, int max_sbals)
 {
 	int count = atomic_read(&fsf_req->adapter->request_queue.free_count);
 	count = min(count, max_sbals);
 	fsf_req->sbal_last  = fsf_req->sbal_first;
 	fsf_req->sbal_last += (count - 1);
 	fsf_req->sbal_last %= QDIO_MAX_BUFFERS_PER_Q;
 }

 /**
  * zfcp_qdio_sbal_chain - chain SBALs if more than one SBAL is needed for a
  *	request
  * @fsf_req: zfcp_fsf_req to be processed
  * @sbtype: SBAL flags which have to be set in first SBALE of new SBAL
  *
  * This function changes sbal_curr, sbale_curr, sbal_number of fsf_req.
  */
 static volatile struct qdio_buffer_element *
 zfcp_qdio_sbal_chain(struct zfcp_fsf_req *fsf_req, unsigned long sbtype)
 {
 	volatile struct qdio_buffer_element *sbale;

 	/* set last entry flag in current SBALE of current SBAL */
 	sbale = zfcp_qdio_sbale_curr(fsf_req);
 	sbale->flags |= SBAL_FLAGS_LAST_ENTRY;

 	/* don't exceed last allowed SBAL */
 	if (fsf_req->sbal_curr == fsf_req->sbal_last)
 		return NULL;

 	/* set chaining flag in first SBALE of current SBAL */
 	sbale = zfcp_qdio_sbale_req(fsf_req, fsf_req->sbal_curr, 0);
 	sbale->flags |= SBAL_FLAGS0_MORE_SBALS;

 	/* calculate index of next SBAL */
 	fsf_req->sbal_curr++;
 	fsf_req->sbal_curr %= QDIO_MAX_BUFFERS_PER_Q;

 	/* keep this requests number of SBALs up-to-date */
 	fsf_req->sbal_number++;

 	/* start at first SBALE of new SBAL */
 	fsf_req->sbale_curr = 0;

 	/* set storage-block type for new SBAL */
 	sbale = zfcp_qdio_sbale_curr(fsf_req);
 	sbale->flags |= sbtype;

 	return sbale;
 }

 /**
  * zfcp_qdio_sbale_next - switch to next SBALE, chain SBALs if needed
  */
 static volatile struct qdio_buffer_element *
 zfcp_qdio_sbale_next(struct zfcp_fsf_req *fsf_req, unsigned long sbtype)
 {
 	if (fsf_req->sbale_curr == ZFCP_LAST_SBALE_PER_SBAL)
 		return zfcp_qdio_sbal_chain(fsf_req, sbtype);

 	fsf_req->sbale_curr++;

 	return zfcp_qdio_sbale_curr(fsf_req);
 }

 /**
  * zfcp_qdio_sbals_zero - initialize SBALs between first and last in queue
  *	with zero from
  */
 static int
 zfcp_qdio_sbals_zero(struct zfcp_qdio_queue *queue, int first, int last)
 {
 	struct qdio_buffer **buf = queue->buffer;
 	int curr = first;
 	int count = 0;

 	for(;;) {
 		curr %= QDIO_MAX_BUFFERS_PER_Q;
 		count++;
 		memset(buf[curr], 0, sizeof(struct qdio_buffer));
 		if (curr == last)
 			break;
 		curr++;
 	}
 	return count;
 }


 /**
  * zfcp_qdio_sbals_wipe - reset all changes in SBALs for an fsf_req
  */
 static inline int
 zfcp_qdio_sbals_wipe(struct zfcp_fsf_req *fsf_req)
 {
 	return zfcp_qdio_sbals_zero(&fsf_req->adapter->request_queue,
 				    fsf_req->sbal_first, fsf_req->sbal_curr);
 }


 /**
  * zfcp_qdio_sbale_fill - set address and length in current SBALE
  *	on request_queue
  */
 static void
 zfcp_qdio_sbale_fill(struct zfcp_fsf_req *fsf_req, unsigned long sbtype,
 		     void *addr, int length)
 {
 	volatile struct qdio_buffer_element *sbale;

 	sbale = zfcp_qdio_sbale_curr(fsf_req);
 	sbale->addr = addr;
 	sbale->length = length;
 }

 /**
  * zfcp_qdio_sbals_from_segment - map memory segment to SBALE(s)
  * @fsf_req: request to be processed
  * @sbtype: SBALE flags
  * @start_addr: address of memory segment
  * @total_length: length of memory segment
  *
  * Alignment and length of the segment determine how many SBALEs are needed
  * for the memory segment.
  */
 static int
 zfcp_qdio_sbals_from_segment(struct zfcp_fsf_req *fsf_req, unsigned long sbtype,
 			     void *start_addr, unsigned long total_length)
 {
 	unsigned long remaining, length;
 	void *addr;

 	/* split segment up heeding page boundaries */
 	for (addr = start_addr, remaining = total_length; remaining > 0;
 	     addr += length, remaining -= length) {
 		/* get next free SBALE for new piece */
 		if (NULL == zfcp_qdio_sbale_next(fsf_req, sbtype)) {
 			/* no SBALE left, clean up and leave */
 			zfcp_qdio_sbals_wipe(fsf_req);
 			return -EINVAL;
 		}
 		/* calculate length of new piece */
 		length = min(remaining,
 			     (PAGE_SIZE - ((unsigned long) addr &
 					   (PAGE_SIZE - 1))));
 		/* fill current SBALE with calculated piece */
 		zfcp_qdio_sbale_fill(fsf_req, sbtype, addr, length);
 	}
 	return total_length;
 }


 /**
  * zfcp_qdio_sbals_from_sg - fill SBALs from scatter-gather list
  * @fsf_req: request to be processed
  * @sbtype: SBALE flags
  * @sg: scatter-gather list
  * @sg_count: number of elements in scatter-gather list
  * @max_sbals: upper bound for number of SBALs to be used
  */
 int
 zfcp_qdio_sbals_from_sg(struct zfcp_fsf_req *fsf_req, unsigned long sbtype,
                         struct scatterlist *sgl, int sg_count, int max_sbals)
 {
 	int sg_index;
 	struct scatterlist *sg_segment;
 	int retval;
 	volatile struct qdio_buffer_element *sbale;
 	int bytes = 0;

 	/* figure out last allowed SBAL */
 	zfcp_qdio_sbal_limit(fsf_req, max_sbals);

 	/* set storage-block type for current SBAL */
 	sbale = zfcp_qdio_sbale_req(fsf_req, fsf_req->sbal_curr, 0);
 	sbale->flags |= sbtype;

 	/* process all segements of scatter-gather list */
 	for_each_sg(sgl, sg_segment, sg_count, sg_index) {
 		retval = zfcp_qdio_sbals_from_segment(
 				fsf_req,
 				sbtype,
 				zfcp_sg_to_address(sg_segment),
 				sg_segment->length);
 		if (retval < 0) {
 			bytes = retval;
 			goto out;
 		} else
                         bytes += retval;
 	}
 	/* assume that no other SBALEs are to follow in the same SBAL */
 	sbale = zfcp_qdio_sbale_curr(fsf_req);
 	sbale->flags |= SBAL_FLAGS_LAST_ENTRY;
 out:
 	return bytes;
 }


 /**
  * zfcp_qdio_sbals_from_scsicmnd - fill SBALs from scsi command
  * @fsf_req: request to be processed
  * @sbtype: SBALE flags
  * @scsi_cmnd: either scatter-gather list or buffer contained herein is used
  *	to fill SBALs
  */
 int
 zfcp_qdio_sbals_from_scsicmnd(struct zfcp_fsf_req *fsf_req,
 			      unsigned long sbtype, struct scsi_cmnd *scsi_cmnd)
 {
 	return zfcp_qdio_sbals_from_sg(fsf_req,	sbtype, scsi_sglist(scsi_cmnd),
 				       scsi_sg_count(scsi_cmnd),
 				       ZFCP_MAX_SBALS_PER_REQ);
 }

 /**
  * zfcp_qdio_determine_pci - set PCI flag in first SBALE on qdio queue if needed
  */
 int
 zfcp_qdio_determine_pci(struct zfcp_qdio_queue *req_queue,
 			struct zfcp_fsf_req *fsf_req)
 {
 	int new_distance_from_int;
 	int pci_pos;
 	volatile struct qdio_buffer_element *sbale;

 	new_distance_from_int = req_queue->distance_from_int +
                 fsf_req->sbal_number;

 	if (unlikely(new_distance_from_int >= ZFCP_QDIO_PCI_INTERVAL)) {
 		new_distance_from_int %= ZFCP_QDIO_PCI_INTERVAL;
                 pci_pos  = fsf_req->sbal_first;
 		pci_pos += fsf_req->sbal_number;
 		pci_pos -= new_distance_from_int;
 		pci_pos -= 1;
 		pci_pos %= QDIO_MAX_BUFFERS_PER_Q;
 		sbale = zfcp_qdio_sbale_req(fsf_req, pci_pos, 0);
 		sbale->flags |= SBAL_FLAGS0_PCI;
 	}
 	return new_distance_from_int;
 }

 /*
  * function:	zfcp_zero_sbals
  *
  * purpose:	zeros specified range of SBALs
  *
  * returns:
  */
 void
 zfcp_qdio_zero_sbals(struct qdio_buffer *buf[], int first, int clean_count)
 {
 	int cur_pos;
 	int index;

 	for (cur_pos = first; cur_pos < (first + clean_count); cur_pos++) {
 		index = cur_pos % QDIO_MAX_BUFFERS_PER_Q;
 		memset(buf[index], 0, sizeof (struct qdio_buffer));
 		ZFCP_LOG_TRACE("zeroing BUFFER %d at address %p\n",
 			       index, buf[index]);
 	}
 }

 #undef ZFCP_LOG_AREA
	/*
	* This file is part of the zfcp device driver for
	* FCP adapters for IBM System z9 and zSeries.
	*
	* (C) Copyright IBM Corp. 2002, 2006
	*
	* 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.
	*/

	#include "zfcp_ext.h"

	static void zfcp_qdio_sbal_limit(struct zfcp_fsf_req *, int);
	static inline volatile struct qdio_buffer_element *zfcp_qdio_sbale_get
	(struct zfcp_qdio_queue *, int, int);
	static inline volatile struct qdio_buffer_element *zfcp_qdio_sbale_resp
	(struct zfcp_fsf_req *, int, int);
	static volatile struct qdio_buffer_element *zfcp_qdio_sbal_chain
	(struct zfcp_fsf_req *, unsigned long);
	static volatile struct qdio_buffer_element *zfcp_qdio_sbale_next
	(struct zfcp_fsf_req *, unsigned long);
	static int zfcp_qdio_sbals_zero(struct zfcp_qdio_queue *, int, int);
	static inline int zfcp_qdio_sbals_wipe(struct zfcp_fsf_req *);
	static void zfcp_qdio_sbale_fill
	(struct zfcp_fsf_req , unsigned long, void , int);
	static int zfcp_qdio_sbals_from_segment
	(struct zfcp_fsf_req , unsigned long, void , unsigned long);

	static qdio_handler_t zfcp_qdio_request_handler;
	static qdio_handler_t zfcp_qdio_response_handler;
	static int zfcp_qdio_handler_error_check(struct zfcp_adapter *,
	unsigned int, unsigned int, unsigned int, int, int);

	#define ZFCP_LOG_AREA ZFCP_LOG_AREA_QDIO

	/*
	* Frees BUFFER memory for each of the pointers of the struct qdio_buffer array
	* in the adapter struct sbuf is the pointer array.
	*
	* locks: must only be called with zfcp_data.config_sema taken
	*/
	static void
	zfcp_qdio_buffers_dequeue(struct qdio_buffer **sbuf)
	{
	int pos;

	for (pos = 0; pos < QDIO_MAX_BUFFERS_PER_Q; pos += QBUFF_PER_PAGE)
	free_page((unsigned long) sbuf[pos]);
	}

	/*
	* Allocates BUFFER memory to each of the pointers of the qdio_buffer_t
	* array in the adapter struct.
	* Cur_buf is the pointer array
	*
	* returns: zero on success else -ENOMEM
	* locks: must only be called with zfcp_data.config_sema taken
	*/
	static int
	zfcp_qdio_buffers_enqueue(struct qdio_buffer **sbuf)
	{
	int pos;

	for (pos = 0; pos < QDIO_MAX_BUFFERS_PER_Q; pos += QBUFF_PER_PAGE) {
	sbuf[pos] = (struct qdio_buffer *) get_zeroed_page(GFP_KERNEL);
	if (!sbuf[pos]) {
	zfcp_qdio_buffers_dequeue(sbuf);
	return -ENOMEM;
	}
	}
	for (pos = 0; pos < QDIO_MAX_BUFFERS_PER_Q; pos++)
	if (pos % QBUFF_PER_PAGE)
	sbuf[pos] = sbuf[pos - 1] + 1;
	return 0;
	}

	/* locks: must only be called with zfcp_data.config_sema taken */
	int
	zfcp_qdio_allocate_queues(struct zfcp_adapter *adapter)
	{
	int ret;

	ret = zfcp_qdio_buffers_enqueue(adapter->request_queue.buffer);
	if (ret)
	return ret;
	return zfcp_qdio_buffers_enqueue(adapter->response_queue.buffer);
	}

	/* locks: must only be called with zfcp_data.config_sema taken */
	void
	zfcp_qdio_free_queues(struct zfcp_adapter *adapter)
	{
	ZFCP_LOG_TRACE("freeing request_queue buffers\n");
	zfcp_qdio_buffers_dequeue(adapter->request_queue.buffer);

	ZFCP_LOG_TRACE("freeing response_queue buffers\n");
	zfcp_qdio_buffers_dequeue(adapter->response_queue.buffer);
	}

	int
	zfcp_qdio_allocate(struct zfcp_adapter *adapter)
	{
	struct qdio_initialize *init_data;

	init_data = &adapter->qdio_init_data;

	init_data->cdev = adapter->ccw_device;
	init_data->q_format = QDIO_SCSI_QFMT;
	memcpy(init_data->adapter_name, zfcp_get_busid_by_adapter(adapter), 8);
	ASCEBC(init_data->adapter_name, 8);
	init_data->qib_param_field_format = 0;
	init_data->qib_param_field = NULL;
	init_data->input_slib_elements = NULL;
	init_data->output_slib_elements = NULL;
	init_data->min_input_threshold = ZFCP_MIN_INPUT_THRESHOLD;
	init_data->max_input_threshold = ZFCP_MAX_INPUT_THRESHOLD;
	init_data->min_output_threshold = ZFCP_MIN_OUTPUT_THRESHOLD;
	init_data->max_output_threshold = ZFCP_MAX_OUTPUT_THRESHOLD;
	init_data->no_input_qs = 1;
	init_data->no_output_qs = 1;
	init_data->input_handler = zfcp_qdio_response_handler;
	init_data->output_handler = zfcp_qdio_request_handler;
	init_data->int_parm = (unsigned long) adapter;
	init_data->flags = QDIO_INBOUND_0COPY_SBALS \|
	QDIO_OUTBOUND_0COPY_SBALS \| QDIO_USE_OUTBOUND_PCIS;
	init_data->input_sbal_addr_array =
	(void **) (adapter->response_queue.buffer);
	init_data->output_sbal_addr_array =
	(void **) (adapter->request_queue.buffer);

	return qdio_allocate(init_data);
	}

	/*
	* function: zfcp_qdio_handler_error_check
	*
	* purpose: called by the response handler to determine error condition
	*
	* returns: error flag
	*
	*/
	static int
	zfcp_qdio_handler_error_check(struct zfcp_adapter *adapter, unsigned int status,
	unsigned int qdio_error, unsigned int siga_error,
	int first_element, int elements_processed)
	{
	int retval = 0;

	if (unlikely(status & QDIO_STATUS_LOOK_FOR_ERROR)) {
	retval = -EIO;

	ZFCP_LOG_INFO("QDIO problem occurred (status=0x%x, "
	"qdio_error=0x%x, siga_error=0x%x)\n",
	status, qdio_error, siga_error);

	zfcp_hba_dbf_event_qdio(adapter, status, qdio_error, siga_error,
	first_element, elements_processed);
	/*
	* Restarting IO on the failed adapter from scratch.
	* Since we have been using this adapter, it is save to assume
	* that it is not failed but recoverable. The card seems to
	* report link-up events by self-initiated queue shutdown.
	* That is why we need to clear the link-down flag
	* which is set again in case we have missed by a mile.
	*/
	zfcp_erp_adapter_reopen(adapter,
	ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED \|
	ZFCP_STATUS_COMMON_ERP_FAILED);
	}
	return retval;
	}

	/*
	* function: zfcp_qdio_request_handler
	*
	* purpose: is called by QDIO layer for completed SBALs in request queue
	*
	* returns: (void)
	*/
	static void
	zfcp_qdio_request_handler(struct ccw_device *ccw_device,
	unsigned int status,
	unsigned int qdio_error,
	unsigned int siga_error,
	unsigned int queue_number,
	int first_element,
	int elements_processed,
	unsigned long int_parm)
	{
	struct zfcp_adapter *adapter;
	struct zfcp_qdio_queue *queue;

	adapter = (struct zfcp_adapter *) int_parm;
	queue = &adapter->request_queue;

	ZFCP_LOG_DEBUG("adapter %s, first=%d, elements_processed=%d\n",
	zfcp_get_busid_by_adapter(adapter),
	first_element, elements_processed);

	if (unlikely(zfcp_qdio_handler_error_check(adapter, status, qdio_error,
	siga_error, first_element,
	elements_processed)))
	goto out;
	/*
	* we stored address of struct zfcp_adapter data structure
	* associated with irq in int_parm
	*/

	/* cleanup all SBALs being program-owned now */
	zfcp_qdio_zero_sbals(queue->buffer, first_element, elements_processed);

	/* increase free space in outbound queue */
	atomic_add(elements_processed, &queue->free_count);
	ZFCP_LOG_DEBUG("free_count=%d\n", atomic_read(&queue->free_count));
	wake_up(&adapter->request_wq);
	ZFCP_LOG_DEBUG("elements_processed=%d, free count=%d\n",
	elements_processed, atomic_read(&queue->free_count));
	out:
	return;
	}

	/**
	* zfcp_qdio_reqid_check - checks for valid reqids.
	*/
	static void zfcp_qdio_reqid_check(struct zfcp_adapter *adapter,
	unsigned long req_id)
	{
	struct zfcp_fsf_req *fsf_req;
	unsigned long flags;

	debug_long_event(adapter->erp_dbf, 4, req_id);

	spin_lock_irqsave(&adapter->req_list_lock, flags);
	fsf_req = zfcp_reqlist_find(adapter, req_id);

	if (!fsf_req)
	/*
	* Unknown request means that we have potentially memory
	* corruption and must stop the machine immediatly.
	*/
	panic("error: unknown request id (%ld) on adapter %s.\n",
	req_id, zfcp_get_busid_by_adapter(adapter));

	zfcp_reqlist_remove(adapter, fsf_req);
	atomic_dec(&adapter->reqs_active);
	spin_unlock_irqrestore(&adapter->req_list_lock, flags);

	/* finish the FSF request */
	zfcp_fsf_req_complete(fsf_req);
	}

	/*
	* function: zfcp_qdio_response_handler
	*
	* purpose: is called by QDIO layer for completed SBALs in response queue
	*
	* returns: (void)
	*/
	static void
	zfcp_qdio_response_handler(struct ccw_device *ccw_device,
	unsigned int status,
	unsigned int qdio_error,
	unsigned int siga_error,
	unsigned int queue_number,
	int first_element,
	int elements_processed,
	unsigned long int_parm)
	{
	struct zfcp_adapter *adapter;
	struct zfcp_qdio_queue *queue;
	int buffer_index;
	int i;
	struct qdio_buffer *buffer;
	int retval = 0;
	u8 count;
	u8 start;
	volatile struct qdio_buffer_element *buffere = NULL;
	int buffere_index;

	adapter = (struct zfcp_adapter *) int_parm;
	queue = &adapter->response_queue;

	if (unlikely(zfcp_qdio_handler_error_check(adapter, status, qdio_error,
	siga_error, first_element,
	elements_processed)))
	goto out;

	/*
	* we stored address of struct zfcp_adapter data structure
	* associated with irq in int_parm
	*/

	buffere = &(queue->buffer[first_element]->element[0]);
	ZFCP_LOG_DEBUG("first BUFFERE flags=0x%x\n", buffere->flags);
	/*
	* go through all SBALs from input queue currently
	* returned by QDIO layer
	*/

	for (i = 0; i < elements_processed; i++) {

	buffer_index = first_element + i;
	buffer_index %= QDIO_MAX_BUFFERS_PER_Q;
	buffer = queue->buffer[buffer_index];

	/* go through all SBALEs of SBAL */
	for (buffere_index = 0;
	buffere_index < QDIO_MAX_ELEMENTS_PER_BUFFER;
	buffere_index++) {

	/* look for QDIO request identifiers in SB */
	buffere = &buffer->element[buffere_index];
	zfcp_qdio_reqid_check(adapter,
	(unsigned long) buffere->addr);

	/*
	* A single used SBALE per inbound SBALE has been
	* implemented by QDIO so far. Hope they will
	* do some optimisation. Will need to change to
	* unlikely() then.
	*/
	if (likely(buffere->flags & SBAL_FLAGS_LAST_ENTRY))
	break;
	};

	if (unlikely(!(buffere->flags & SBAL_FLAGS_LAST_ENTRY))) {
	ZFCP_LOG_NORMAL("bug: End of inbound data "
	"not marked!\n");
	}
	}

	/*
	* put range of SBALs back to response queue
	* (including SBALs which have already been free before)
	*/
	count = atomic_read(&queue->free_count) + elements_processed;
	start = queue->free_index;

	ZFCP_LOG_TRACE("calling do_QDIO on adapter %s (flags=0x%x, "
	"queue_no=%i, index_in_queue=%i, count=%i, "
	"buffers=0x%lx\n",
	zfcp_get_busid_by_adapter(adapter),
	QDIO_FLAG_SYNC_INPUT \| QDIO_FLAG_UNDER_INTERRUPT,
	0, start, count, (unsigned long) &queue->buffer[start]);

	retval = do_QDIO(ccw_device,
	QDIO_FLAG_SYNC_INPUT \| QDIO_FLAG_UNDER_INTERRUPT,
	0, start, count, NULL);

	if (unlikely(retval)) {
	atomic_set(&queue->free_count, count);
	ZFCP_LOG_DEBUG("clearing of inbound data regions failed, "
	"queues may be down "
	"(count=%d, start=%d, retval=%d)\n",
	count, start, retval);
	} else {
	queue->free_index += count;
	queue->free_index %= QDIO_MAX_BUFFERS_PER_Q;
	atomic_set(&queue->free_count, 0);
	ZFCP_LOG_TRACE("%i buffers enqueued to response "
	"queue at position %i\n", count, start);
	}
	out:
	return;
	}

	/**
	* zfcp_qdio_sbale_get - return pointer to SBALE of qdio_queue
	* @queue: queue from which SBALE should be returned
	* @sbal: specifies number of SBAL in queue
	* @sbale: specifes number of SBALE in SBAL
	*/
	static inline volatile struct qdio_buffer_element *
	zfcp_qdio_sbale_get(struct zfcp_qdio_queue *queue, int sbal, int sbale)
	{
	return &queue->buffer[sbal]->element[sbale];
	}

	/**
	* zfcp_qdio_sbale_req - return pointer to SBALE of request_queue for
	* a struct zfcp_fsf_req
	*/
	volatile struct qdio_buffer_element *
	zfcp_qdio_sbale_req(struct zfcp_fsf_req *fsf_req, int sbal, int sbale)
	{
	return zfcp_qdio_sbale_get(&fsf_req->adapter->request_queue,
	sbal, sbale);
	}

	/**
	* zfcp_qdio_sbale_resp - return pointer to SBALE of response_queue for
	* a struct zfcp_fsf_req
	*/
	static inline volatile struct qdio_buffer_element *
	zfcp_qdio_sbale_resp(struct zfcp_fsf_req *fsf_req, int sbal, int sbale)
	{
	return zfcp_qdio_sbale_get(&fsf_req->adapter->response_queue,
	sbal, sbale);
	}

	/**
	* zfcp_qdio_sbale_curr - return current SBALE on request_queue for
	* a struct zfcp_fsf_req
	*/
	volatile struct qdio_buffer_element *
	zfcp_qdio_sbale_curr(struct zfcp_fsf_req *fsf_req)
	{
	return zfcp_qdio_sbale_req(fsf_req, fsf_req->sbal_curr,
	fsf_req->sbale_curr);
	}

	/**
	* zfcp_qdio_sbal_limit - determine maximum number of SBALs that can be used
	* on the request_queue for a struct zfcp_fsf_req
	* @fsf_req: the number of the last SBAL that can be used is stored herein
	* @max_sbals: used to pass an upper limit for the number of SBALs
	*
	* Note: We can assume at least one free SBAL in the request_queue when called.
	*/
	static void
	zfcp_qdio_sbal_limit(struct zfcp_fsf_req *fsf_req, int max_sbals)
	{
	int count = atomic_read(&fsf_req->adapter->request_queue.free_count);
	count = min(count, max_sbals);
	fsf_req->sbal_last = fsf_req->sbal_first;
	fsf_req->sbal_last += (count - 1);
	fsf_req->sbal_last %= QDIO_MAX_BUFFERS_PER_Q;
	}

	/**
	* zfcp_qdio_sbal_chain - chain SBALs if more than one SBAL is needed for a
	* request
	* @fsf_req: zfcp_fsf_req to be processed
	* @sbtype: SBAL flags which have to be set in first SBALE of new SBAL
	*
	* This function changes sbal_curr, sbale_curr, sbal_number of fsf_req.
	*/
	static volatile struct qdio_buffer_element *
	zfcp_qdio_sbal_chain(struct zfcp_fsf_req *fsf_req, unsigned long sbtype)
	{
	volatile struct qdio_buffer_element *sbale;

	/* set last entry flag in current SBALE of current SBAL */
	sbale = zfcp_qdio_sbale_curr(fsf_req);
	sbale->flags \|= SBAL_FLAGS_LAST_ENTRY;

	/* don't exceed last allowed SBAL */
	if (fsf_req->sbal_curr == fsf_req->sbal_last)
	return NULL;

	/* set chaining flag in first SBALE of current SBAL */
	sbale = zfcp_qdio_sbale_req(fsf_req, fsf_req->sbal_curr, 0);
	sbale->flags \|= SBAL_FLAGS0_MORE_SBALS;

	/* calculate index of next SBAL */
	fsf_req->sbal_curr++;
	fsf_req->sbal_curr %= QDIO_MAX_BUFFERS_PER_Q;

	/* keep this requests number of SBALs up-to-date */
	fsf_req->sbal_number++;

	/* start at first SBALE of new SBAL */
	fsf_req->sbale_curr = 0;

	/* set storage-block type for new SBAL */
	sbale = zfcp_qdio_sbale_curr(fsf_req);
	sbale->flags \|= sbtype;

	return sbale;
	}

	/**
	* zfcp_qdio_sbale_next - switch to next SBALE, chain SBALs if needed
	*/
	static volatile struct qdio_buffer_element *
	zfcp_qdio_sbale_next(struct zfcp_fsf_req *fsf_req, unsigned long sbtype)
	{
	if (fsf_req->sbale_curr == ZFCP_LAST_SBALE_PER_SBAL)
	return zfcp_qdio_sbal_chain(fsf_req, sbtype);

	fsf_req->sbale_curr++;

	return zfcp_qdio_sbale_curr(fsf_req);
	}

	/**
	* zfcp_qdio_sbals_zero - initialize SBALs between first and last in queue
	* with zero from
	*/
	static int
	zfcp_qdio_sbals_zero(struct zfcp_qdio_queue *queue, int first, int last)
	{
	struct qdio_buffer **buf = queue->buffer;
	int curr = first;
	int count = 0;

	for(;;) {
	curr %= QDIO_MAX_BUFFERS_PER_Q;
	count++;
	memset(buf[curr], 0, sizeof(struct qdio_buffer));
	if (curr == last)
	break;
	curr++;
	}
	return count;
	}


	/**
	* zfcp_qdio_sbals_wipe - reset all changes in SBALs for an fsf_req
	*/
	static inline int
	zfcp_qdio_sbals_wipe(struct zfcp_fsf_req *fsf_req)
	{
	return zfcp_qdio_sbals_zero(&fsf_req->adapter->request_queue,
	fsf_req->sbal_first, fsf_req->sbal_curr);
	}


	/**
	* zfcp_qdio_sbale_fill - set address and length in current SBALE
	* on request_queue
	*/
	static void
	zfcp_qdio_sbale_fill(struct zfcp_fsf_req *fsf_req, unsigned long sbtype,
	void *addr, int length)
	{
	volatile struct qdio_buffer_element *sbale;

	sbale = zfcp_qdio_sbale_curr(fsf_req);
	sbale->addr = addr;
	sbale->length = length;
	}

	/**
	* zfcp_qdio_sbals_from_segment - map memory segment to SBALE(s)
	* @fsf_req: request to be processed
	* @sbtype: SBALE flags
	* @start_addr: address of memory segment
	* @total_length: length of memory segment
	*
	* Alignment and length of the segment determine how many SBALEs are needed
	* for the memory segment.
	*/
	static int
	zfcp_qdio_sbals_from_segment(struct zfcp_fsf_req *fsf_req, unsigned long sbtype,
	void *start_addr, unsigned long total_length)
	{
	unsigned long remaining, length;
	void *addr;

	/* split segment up heeding page boundaries */
	for (addr = start_addr, remaining = total_length; remaining > 0;
	addr += length, remaining -= length) {
	/* get next free SBALE for new piece */
	if (NULL == zfcp_qdio_sbale_next(fsf_req, sbtype)) {
	/* no SBALE left, clean up and leave */
	zfcp_qdio_sbals_wipe(fsf_req);
	return -EINVAL;
	}
	/* calculate length of new piece */
	length = min(remaining,
	(PAGE_SIZE - ((unsigned long) addr &
	(PAGE_SIZE - 1))));
	/* fill current SBALE with calculated piece */
	zfcp_qdio_sbale_fill(fsf_req, sbtype, addr, length);
	}
	return total_length;
	}


	/**
	* zfcp_qdio_sbals_from_sg - fill SBALs from scatter-gather list
	* @fsf_req: request to be processed
	* @sbtype: SBALE flags
	* @sg: scatter-gather list
	* @sg_count: number of elements in scatter-gather list
	* @max_sbals: upper bound for number of SBALs to be used
	*/
	int
	zfcp_qdio_sbals_from_sg(struct zfcp_fsf_req *fsf_req, unsigned long sbtype,
	struct scatterlist *sgl, int sg_count, int max_sbals)
	{
	int sg_index;
	struct scatterlist *sg_segment;
	int retval;
	volatile struct qdio_buffer_element *sbale;
	int bytes = 0;

	/* figure out last allowed SBAL */
	zfcp_qdio_sbal_limit(fsf_req, max_sbals);

	/* set storage-block type for current SBAL */
	sbale = zfcp_qdio_sbale_req(fsf_req, fsf_req->sbal_curr, 0);
	sbale->flags \|= sbtype;

	/* process all segements of scatter-gather list */
	for_each_sg(sgl, sg_segment, sg_count, sg_index) {
	retval = zfcp_qdio_sbals_from_segment(
	fsf_req,
	sbtype,
	zfcp_sg_to_address(sg_segment),
	sg_segment->length);
	if (retval < 0) {
	bytes = retval;
	goto out;
	} else
	bytes += retval;
	}
	/* assume that no other SBALEs are to follow in the same SBAL */
	sbale = zfcp_qdio_sbale_curr(fsf_req);
	sbale->flags \|= SBAL_FLAGS_LAST_ENTRY;
	out:
	return bytes;
	}


	/**
	* zfcp_qdio_sbals_from_scsicmnd - fill SBALs from scsi command
	* @fsf_req: request to be processed
	* @sbtype: SBALE flags
	* @scsi_cmnd: either scatter-gather list or buffer contained herein is used
	* to fill SBALs
	*/
	int
	zfcp_qdio_sbals_from_scsicmnd(struct zfcp_fsf_req *fsf_req,
	unsigned long sbtype, struct scsi_cmnd *scsi_cmnd)
	{
	return zfcp_qdio_sbals_from_sg(fsf_req, sbtype, scsi_sglist(scsi_cmnd),
	scsi_sg_count(scsi_cmnd),
	ZFCP_MAX_SBALS_PER_REQ);
	}

	/**
	* zfcp_qdio_determine_pci - set PCI flag in first SBALE on qdio queue if needed
	*/
	int
	zfcp_qdio_determine_pci(struct zfcp_qdio_queue *req_queue,
	struct zfcp_fsf_req *fsf_req)
	{
	int new_distance_from_int;
	int pci_pos;
	volatile struct qdio_buffer_element *sbale;

	new_distance_from_int = req_queue->distance_from_int +
	fsf_req->sbal_number;

	if (unlikely(new_distance_from_int >= ZFCP_QDIO_PCI_INTERVAL)) {
	new_distance_from_int %= ZFCP_QDIO_PCI_INTERVAL;
	pci_pos = fsf_req->sbal_first;
	pci_pos += fsf_req->sbal_number;
	pci_pos -= new_distance_from_int;
	pci_pos -= 1;
	pci_pos %= QDIO_MAX_BUFFERS_PER_Q;
	sbale = zfcp_qdio_sbale_req(fsf_req, pci_pos, 0);
	sbale->flags \|= SBAL_FLAGS0_PCI;
	}
	return new_distance_from_int;
	}

	/*
	* function: zfcp_zero_sbals
	*
	* purpose: zeros specified range of SBALs
	*
	* returns:
	*/
	void
	zfcp_qdio_zero_sbals(struct qdio_buffer *buf[], int first, int clean_count)
	{
	int cur_pos;
	int index;

	for (cur_pos = first; cur_pos < (first + clean_count); cur_pos++) {
	index = cur_pos % QDIO_MAX_BUFFERS_PER_Q;
	memset(buf[index], 0, sizeof (struct qdio_buffer));
	ZFCP_LOG_TRACE("zeroing BUFFER %d at address %p\n",
	index, buf[index]);
	}
	}

	#undef ZFCP_LOG_AREA