summaryrefslogtreecommitdiffstats
path: root/drivers/s390/scsi/zfcp_qdio.c
blob: cb08ca3cc0f993bcb6925ea7e007d0df2bdc78d7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
/*
 * 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 int zfcp_qdio_sbals_from_buffer
	(struct zfcp_fsf_req *, unsigned long, void *, unsigned long, int);

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

/*
 * Allocates BUFFER memory to each of the pointers of the qdio_buffer_t 
 * array in the adapter struct.
 * Cur_buf is the pointer array and count can be any number of required 
 * buffers, the page-fitting arithmetic is done entirely within this funciton.
 *
 * returns:	number of buffers allocated
 * locks:       must only be called with zfcp_data.config_sema taken
 */
static int
zfcp_qdio_buffers_enqueue(struct qdio_buffer **cur_buf, int count)
{
	int buf_pos;
	int qdio_buffers_per_page;
	int page_pos = 0;
	struct qdio_buffer *first_in_page = NULL;

	qdio_buffers_per_page = PAGE_SIZE / sizeof (struct qdio_buffer);
	ZFCP_LOG_TRACE("buffers_per_page=%d\n", qdio_buffers_per_page);

	for (buf_pos = 0; buf_pos < count; buf_pos++) {
		if (page_pos == 0) {
			cur_buf[buf_pos] = (struct qdio_buffer *)
			    get_zeroed_page(GFP_KERNEL);
			if (cur_buf[buf_pos] == NULL) {
				ZFCP_LOG_INFO("error: allocation of "
					      "QDIO buffer failed \n");
				goto out;
			}
			first_in_page = cur_buf[buf_pos];
		} else {
			cur_buf[buf_pos] = first_in_page + page_pos;

		}
		/* was initialised to zero */
		page_pos++;
		page_pos %= qdio_buffers_per_page;
	}
 out:
	return buf_pos;
}

/*
 * Frees BUFFER memory for each of the pointers of the struct qdio_buffer array
 * in the adapter struct cur_buf is the pointer array and count can be any
 * number of buffers in the array that should be freed starting from buffer 0
 *
 * locks:       must only be called with zfcp_data.config_sema taken
 */
static void
zfcp_qdio_buffers_dequeue(struct qdio_buffer **cur_buf, int count)
{
	int buf_pos;
	int qdio_buffers_per_page;

	qdio_buffers_per_page = PAGE_SIZE / sizeof (struct qdio_buffer);
	ZFCP_LOG_TRACE("buffers_per_page=%d\n", qdio_buffers_per_page);

	for (buf_pos = 0; buf_pos < count; buf_pos += qdio_buffers_per_page)
		free_page((unsigned long) cur_buf[buf_pos]);
	return;
}

/* locks:       must only be called with zfcp_data.config_sema taken */
int
zfcp_qdio_allocate_queues(struct zfcp_adapter *adapter)
{
	int buffer_count;
	int retval = 0;

	buffer_count =
	    zfcp_qdio_buffers_enqueue(&(adapter->request_queue.buffer[0]),
				      QDIO_MAX_BUFFERS_PER_Q);
	if (buffer_count < QDIO_MAX_BUFFERS_PER_Q) {
		ZFCP_LOG_DEBUG("only %d QDIO buffers allocated for request "
			       "queue\n", buffer_count);
		zfcp_qdio_buffers_dequeue(&(adapter->request_queue.buffer[0]),
					  buffer_count);
		retval = -ENOMEM;
		goto out;
	}

	buffer_count =
	    zfcp_qdio_buffers_enqueue(&(adapter->response_queue.buffer[0]),
				      QDIO_MAX_BUFFERS_PER_Q);
	if (buffer_count < QDIO_MAX_BUFFERS_PER_Q) {
		ZFCP_LOG_DEBUG("only %d QDIO buffers allocated for response "
			       "queue", buffer_count);
		zfcp_qdio_buffers_dequeue(&(adapter->response_queue.buffer[0]),
					  buffer_count);
		ZFCP_LOG_TRACE("freeing request_queue buffers\n");
		zfcp_qdio_buffers_dequeue(&(adapter->request_queue.buffer[0]),
					  QDIO_MAX_BUFFERS_PER_Q);
		retval = -ENOMEM;
		goto out;
	}
 out:
	return retval;
}

/* 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[0]),
				  QDIO_MAX_BUFFERS_PER_Q);

	ZFCP_LOG_TRACE("freeing response_queue buffers\n");
	zfcp_qdio_buffers_dequeue(&(adapter->response_queue.buffer[0]),
				  QDIO_MAX_BUFFERS_PER_Q);
}

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 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 lenght 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 *sg,	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 (sg_index = 0, sg_segment = sg, bytes = 0;
	     sg_index < sg_count;
	     sg_index++, sg_segment++) {
		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_buffer - fill SBALs from buffer
 * @fsf_req: request to be processed
 * @sbtype: SBALE flags
 * @buffer: data buffer
 * @length: length of buffer
 * @max_sbals: upper bound for number of SBALs to be used
 */
static int
zfcp_qdio_sbals_from_buffer(struct zfcp_fsf_req *fsf_req, unsigned long sbtype,
			    void *buffer, unsigned long length, int max_sbals)
{
	struct scatterlist sg_segment;

	zfcp_address_to_sg(buffer, &sg_segment);
	sg_segment.length = length;

	return zfcp_qdio_sbals_from_sg(fsf_req, sbtype, &sg_segment, 1,
                                       max_sbals);
}


/**
 * 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)
{
	if (scsi_cmnd->use_sg) {
		return zfcp_qdio_sbals_from_sg(fsf_req,	sbtype,
                                               (struct scatterlist *)
                                               scsi_cmnd->request_buffer,
                                               scsi_cmnd->use_sg,
                                               ZFCP_MAX_SBALS_PER_REQ);
	} else {
                return zfcp_qdio_sbals_from_buffer(fsf_req, sbtype,
                                                   scsi_cmnd->request_buffer,
                                                   scsi_cmnd->request_bufflen,
                                                   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