summaryrefslogtreecommitdiff
path: root/include/linux/qed/qed_chain.h
blob: 2dd0a9ed5b361472fbb1794b3b77f96fc69780ce (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
/* QLogic qed NIC Driver
 * Copyright (c) 2015-2017  QLogic Corporation
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and /or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef _QED_CHAIN_H
#define _QED_CHAIN_H

#include <linux/types.h>
#include <asm/byteorder.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/qed/common_hsi.h>

enum qed_chain_mode {
	/* Each Page contains a next pointer at its end */
	QED_CHAIN_MODE_NEXT_PTR,

	/* Chain is a single page (next ptr) is unrequired */
	QED_CHAIN_MODE_SINGLE,

	/* Page pointers are located in a side list */
	QED_CHAIN_MODE_PBL,
};

enum qed_chain_use_mode {
	QED_CHAIN_USE_TO_PRODUCE,		/* Chain starts empty */
	QED_CHAIN_USE_TO_CONSUME,		/* Chain starts full */
	QED_CHAIN_USE_TO_CONSUME_PRODUCE,	/* Chain starts empty */
};

enum qed_chain_cnt_type {
	/* The chain's size/prod/cons are kept in 16-bit variables */
	QED_CHAIN_CNT_TYPE_U16,

	/* The chain's size/prod/cons are kept in 32-bit variables  */
	QED_CHAIN_CNT_TYPE_U32,
};

struct qed_chain_next {
	struct regpair	next_phys;
	void		*next_virt;
};

struct qed_chain_pbl_u16 {
	u16 prod_page_idx;
	u16 cons_page_idx;
};

struct qed_chain_pbl_u32 {
	u32 prod_page_idx;
	u32 cons_page_idx;
};

struct qed_chain_ext_pbl {
	dma_addr_t p_pbl_phys;
	void *p_pbl_virt;
};

struct qed_chain_u16 {
	/* Cyclic index of next element to produce/consme */
	u16 prod_idx;
	u16 cons_idx;
};

struct qed_chain_u32 {
	/* Cyclic index of next element to produce/consme */
	u32 prod_idx;
	u32 cons_idx;
};

struct qed_chain {
	/* fastpath portion of the chain - required for commands such
	 * as produce / consume.
	 */
	/* Point to next element to produce/consume */
	void *p_prod_elem;
	void *p_cons_elem;

	/* Fastpath portions of the PBL [if exists] */
	struct {
		/* Table for keeping the virtual addresses of the chain pages,
		 * respectively to the physical addresses in the pbl table.
		 */
		void **pp_virt_addr_tbl;

		union {
			struct qed_chain_pbl_u16 u16;
			struct qed_chain_pbl_u32 u32;
		} c;
	} pbl;

	union {
		struct qed_chain_u16 chain16;
		struct qed_chain_u32 chain32;
	} u;

	/* Capacity counts only usable elements */
	u32 capacity;
	u32 page_cnt;

	enum qed_chain_mode mode;

	/* Elements information for fast calculations */
	u16 elem_per_page;
	u16 elem_per_page_mask;
	u16 elem_size;
	u16 next_page_mask;
	u16 usable_per_page;
	u8 elem_unusable;

	u8 cnt_type;

	/* Slowpath of the chain - required for initialization and destruction,
	 * but isn't involved in regular functionality.
	 */

	/* Base address of a pre-allocated buffer for pbl */
	struct {
		dma_addr_t p_phys_table;
		void *p_virt_table;
	} pbl_sp;

	/* Address of first page of the chain - the address is required
	 * for fastpath operation [consume/produce] but only for the the SINGLE
	 * flavour which isn't considered fastpath [== SPQ].
	 */
	void *p_virt_addr;
	dma_addr_t p_phys_addr;

	/* Total number of elements [for entire chain] */
	u32 size;

	u8 intended_use;

	bool b_external_pbl;
};

#define QED_CHAIN_PBL_ENTRY_SIZE        (8)
#define QED_CHAIN_PAGE_SIZE             (0x1000)
#define ELEMS_PER_PAGE(elem_size)       (QED_CHAIN_PAGE_SIZE / (elem_size))

#define UNUSABLE_ELEMS_PER_PAGE(elem_size, mode)	 \
	(((mode) == QED_CHAIN_MODE_NEXT_PTR) ?		 \
	 (u8)(1 + ((sizeof(struct qed_chain_next) - 1) / \
		   (elem_size))) : 0)

#define USABLE_ELEMS_PER_PAGE(elem_size, mode) \
	((u32)(ELEMS_PER_PAGE(elem_size) -     \
	       UNUSABLE_ELEMS_PER_PAGE(elem_size, mode)))

#define QED_CHAIN_PAGE_CNT(elem_cnt, elem_size, mode) \
	DIV_ROUND_UP(elem_cnt, USABLE_ELEMS_PER_PAGE(elem_size, mode))

#define is_chain_u16(p) ((p)->cnt_type == QED_CHAIN_CNT_TYPE_U16)
#define is_chain_u32(p) ((p)->cnt_type == QED_CHAIN_CNT_TYPE_U32)

/* Accessors */
static inline u16 qed_chain_get_prod_idx(struct qed_chain *p_chain)
{
	return p_chain->u.chain16.prod_idx;
}

static inline u16 qed_chain_get_cons_idx(struct qed_chain *p_chain)
{
	return p_chain->u.chain16.cons_idx;
}

static inline u32 qed_chain_get_cons_idx_u32(struct qed_chain *p_chain)
{
	return p_chain->u.chain32.cons_idx;
}

static inline u16 qed_chain_get_elem_left(struct qed_chain *p_chain)
{
	u16 used;

	used = (u16) (((u32)0x10000 +
		       (u32)p_chain->u.chain16.prod_idx) -
		      (u32)p_chain->u.chain16.cons_idx);
	if (p_chain->mode == QED_CHAIN_MODE_NEXT_PTR)
		used -= p_chain->u.chain16.prod_idx / p_chain->elem_per_page -
		    p_chain->u.chain16.cons_idx / p_chain->elem_per_page;

	return (u16)(p_chain->capacity - used);
}

static inline u32 qed_chain_get_elem_left_u32(struct qed_chain *p_chain)
{
	u32 used;

	used = (u32) (((u64)0x100000000ULL +
		       (u64)p_chain->u.chain32.prod_idx) -
		      (u64)p_chain->u.chain32.cons_idx);
	if (p_chain->mode == QED_CHAIN_MODE_NEXT_PTR)
		used -= p_chain->u.chain32.prod_idx / p_chain->elem_per_page -
		    p_chain->u.chain32.cons_idx / p_chain->elem_per_page;

	return p_chain->capacity - used;
}

static inline u16 qed_chain_get_usable_per_page(struct qed_chain *p_chain)
{
	return p_chain->usable_per_page;
}

static inline u8 qed_chain_get_unusable_per_page(struct qed_chain *p_chain)
{
	return p_chain->elem_unusable;
}

static inline u32 qed_chain_get_page_cnt(struct qed_chain *p_chain)
{
	return p_chain->page_cnt;
}

static inline dma_addr_t qed_chain_get_pbl_phys(struct qed_chain *p_chain)
{
	return p_chain->pbl_sp.p_phys_table;
}

/**
 * @brief qed_chain_advance_page -
 *
 * Advance the next element accros pages for a linked chain
 *
 * @param p_chain
 * @param p_next_elem
 * @param idx_to_inc
 * @param page_to_inc
 */
static inline void
qed_chain_advance_page(struct qed_chain *p_chain,
		       void **p_next_elem, void *idx_to_inc, void *page_to_inc)
{
	struct qed_chain_next *p_next = NULL;
	u32 page_index = 0;

	switch (p_chain->mode) {
	case QED_CHAIN_MODE_NEXT_PTR:
		p_next = *p_next_elem;
		*p_next_elem = p_next->next_virt;
		if (is_chain_u16(p_chain))
			*(u16 *)idx_to_inc += p_chain->elem_unusable;
		else
			*(u32 *)idx_to_inc += p_chain->elem_unusable;
		break;
	case QED_CHAIN_MODE_SINGLE:
		*p_next_elem = p_chain->p_virt_addr;
		break;

	case QED_CHAIN_MODE_PBL:
		if (is_chain_u16(p_chain)) {
			if (++(*(u16 *)page_to_inc) == p_chain->page_cnt)
				*(u16 *)page_to_inc = 0;
			page_index = *(u16 *)page_to_inc;
		} else {
			if (++(*(u32 *)page_to_inc) == p_chain->page_cnt)
				*(u32 *)page_to_inc = 0;
			page_index = *(u32 *)page_to_inc;
		}
		*p_next_elem = p_chain->pbl.pp_virt_addr_tbl[page_index];
	}
}

#define is_unusable_idx(p, idx)	\
	(((p)->u.chain16.idx & (p)->elem_per_page_mask) == (p)->usable_per_page)

#define is_unusable_idx_u32(p, idx) \
	(((p)->u.chain32.idx & (p)->elem_per_page_mask) == (p)->usable_per_page)
#define is_unusable_next_idx(p, idx)				 \
	((((p)->u.chain16.idx + 1) & (p)->elem_per_page_mask) == \
	 (p)->usable_per_page)

#define is_unusable_next_idx_u32(p, idx)			 \
	((((p)->u.chain32.idx + 1) & (p)->elem_per_page_mask) == \
	 (p)->usable_per_page)

#define test_and_skip(p, idx)						   \
	do {						\
		if (is_chain_u16(p)) {					   \
			if (is_unusable_idx(p, idx))			   \
				(p)->u.chain16.idx += (p)->elem_unusable;  \
		} else {						   \
			if (is_unusable_idx_u32(p, idx))		   \
				(p)->u.chain32.idx += (p)->elem_unusable;  \
		}					\
	} while (0)

/**
 * @brief qed_chain_return_produced -
 *
 * A chain in which the driver "Produces" elements should use this API
 * to indicate previous produced elements are now consumed.
 *
 * @param p_chain
 */
static inline void qed_chain_return_produced(struct qed_chain *p_chain)
{
	if (is_chain_u16(p_chain))
		p_chain->u.chain16.cons_idx++;
	else
		p_chain->u.chain32.cons_idx++;
	test_and_skip(p_chain, cons_idx);
}

/**
 * @brief qed_chain_produce -
 *
 * A chain in which the driver "Produces" elements should use this to get
 * a pointer to the next element which can be "Produced". It's driver
 * responsibility to validate that the chain has room for new element.
 *
 * @param p_chain
 *
 * @return void*, a pointer to next element
 */
static inline void *qed_chain_produce(struct qed_chain *p_chain)
{
	void *p_ret = NULL, *p_prod_idx, *p_prod_page_idx;

	if (is_chain_u16(p_chain)) {
		if ((p_chain->u.chain16.prod_idx &
		     p_chain->elem_per_page_mask) == p_chain->next_page_mask) {
			p_prod_idx = &p_chain->u.chain16.prod_idx;
			p_prod_page_idx = &p_chain->pbl.c.u16.prod_page_idx;
			qed_chain_advance_page(p_chain, &p_chain->p_prod_elem,
					       p_prod_idx, p_prod_page_idx);
		}
		p_chain->u.chain16.prod_idx++;
	} else {
		if ((p_chain->u.chain32.prod_idx &
		     p_chain->elem_per_page_mask) == p_chain->next_page_mask) {
			p_prod_idx = &p_chain->u.chain32.prod_idx;
			p_prod_page_idx = &p_chain->pbl.c.u32.prod_page_idx;
			qed_chain_advance_page(p_chain, &p_chain->p_prod_elem,
					       p_prod_idx, p_prod_page_idx);
		}
		p_chain->u.chain32.prod_idx++;
	}

	p_ret = p_chain->p_prod_elem;
	p_chain->p_prod_elem = (void *)(((u8 *)p_chain->p_prod_elem) +
					p_chain->elem_size);

	return p_ret;
}

/**
 * @brief qed_chain_get_capacity -
 *
 * Get the maximum number of BDs in chain
 *
 * @param p_chain
 * @param num
 *
 * @return number of unusable BDs
 */
static inline u32 qed_chain_get_capacity(struct qed_chain *p_chain)
{
	return p_chain->capacity;
}

/**
 * @brief qed_chain_recycle_consumed -
 *
 * Returns an element which was previously consumed;
 * Increments producers so they could be written to FW.
 *
 * @param p_chain
 */
static inline void qed_chain_recycle_consumed(struct qed_chain *p_chain)
{
	test_and_skip(p_chain, prod_idx);
	if (is_chain_u16(p_chain))
		p_chain->u.chain16.prod_idx++;
	else
		p_chain->u.chain32.prod_idx++;
}

/**
 * @brief qed_chain_consume -
 *
 * A Chain in which the driver utilizes data written by a different source
 * (i.e., FW) should use this to access passed buffers.
 *
 * @param p_chain
 *
 * @return void*, a pointer to the next buffer written
 */
static inline void *qed_chain_consume(struct qed_chain *p_chain)
{
	void *p_ret = NULL, *p_cons_idx, *p_cons_page_idx;

	if (is_chain_u16(p_chain)) {
		if ((p_chain->u.chain16.cons_idx &
		     p_chain->elem_per_page_mask) == p_chain->next_page_mask) {
			p_cons_idx = &p_chain->u.chain16.cons_idx;
			p_cons_page_idx = &p_chain->pbl.c.u16.cons_page_idx;
			qed_chain_advance_page(p_chain, &p_chain->p_cons_elem,
					       p_cons_idx, p_cons_page_idx);
		}
		p_chain->u.chain16.cons_idx++;
	} else {
		if ((p_chain->u.chain32.cons_idx &
		     p_chain->elem_per_page_mask) == p_chain->next_page_mask) {
			p_cons_idx = &p_chain->u.chain32.cons_idx;
			p_cons_page_idx = &p_chain->pbl.c.u32.cons_page_idx;
			qed_chain_advance_page(p_chain, &p_chain->p_cons_elem,
					       p_cons_idx, p_cons_page_idx);
		}
		p_chain->u.chain32.cons_idx++;
	}

	p_ret = p_chain->p_cons_elem;
	p_chain->p_cons_elem = (void *)(((u8 *)p_chain->p_cons_elem) +
					p_chain->elem_size);

	return p_ret;
}

/**
 * @brief qed_chain_reset - Resets the chain to its start state
 *
 * @param p_chain pointer to a previously allocted chain
 */
static inline void qed_chain_reset(struct qed_chain *p_chain)
{
	u32 i;

	if (is_chain_u16(p_chain)) {
		p_chain->u.chain16.prod_idx = 0;
		p_chain->u.chain16.cons_idx = 0;
	} else {
		p_chain->u.chain32.prod_idx = 0;
		p_chain->u.chain32.cons_idx = 0;
	}
	p_chain->p_cons_elem = p_chain->p_virt_addr;
	p_chain->p_prod_elem = p_chain->p_virt_addr;

	if (p_chain->mode == QED_CHAIN_MODE_PBL) {
		/* Use (page_cnt - 1) as a reset value for the prod/cons page's
		 * indices, to avoid unnecessary page advancing on the first
		 * call to qed_chain_produce/consume. Instead, the indices
		 * will be advanced to page_cnt and then will be wrapped to 0.
		 */
		u32 reset_val = p_chain->page_cnt - 1;

		if (is_chain_u16(p_chain)) {
			p_chain->pbl.c.u16.prod_page_idx = (u16)reset_val;
			p_chain->pbl.c.u16.cons_page_idx = (u16)reset_val;
		} else {
			p_chain->pbl.c.u32.prod_page_idx = reset_val;
			p_chain->pbl.c.u32.cons_page_idx = reset_val;
		}
	}

	switch (p_chain->intended_use) {
	case QED_CHAIN_USE_TO_CONSUME:
		/* produce empty elements */
		for (i = 0; i < p_chain->capacity; i++)
			qed_chain_recycle_consumed(p_chain);
		break;

	case QED_CHAIN_USE_TO_CONSUME_PRODUCE:
	case QED_CHAIN_USE_TO_PRODUCE:
	default:
		/* Do nothing */
		break;
	}
}

/**
 * @brief qed_chain_init - Initalizes a basic chain struct
 *
 * @param p_chain
 * @param p_virt_addr
 * @param p_phys_addr	physical address of allocated buffer's beginning
 * @param page_cnt	number of pages in the allocated buffer
 * @param elem_size	size of each element in the chain
 * @param intended_use
 * @param mode
 */
static inline void qed_chain_init_params(struct qed_chain *p_chain,
					 u32 page_cnt,
					 u8 elem_size,
					 enum qed_chain_use_mode intended_use,
					 enum qed_chain_mode mode,
					 enum qed_chain_cnt_type cnt_type)
{
	/* chain fixed parameters */
	p_chain->p_virt_addr = NULL;
	p_chain->p_phys_addr = 0;
	p_chain->elem_size	= elem_size;
	p_chain->intended_use = (u8)intended_use;
	p_chain->mode		= mode;
	p_chain->cnt_type = (u8)cnt_type;

	p_chain->elem_per_page = ELEMS_PER_PAGE(elem_size);
	p_chain->usable_per_page = USABLE_ELEMS_PER_PAGE(elem_size, mode);
	p_chain->elem_per_page_mask = p_chain->elem_per_page - 1;
	p_chain->elem_unusable = UNUSABLE_ELEMS_PER_PAGE(elem_size, mode);
	p_chain->next_page_mask = (p_chain->usable_per_page &
				   p_chain->elem_per_page_mask);

	p_chain->page_cnt = page_cnt;
	p_chain->capacity = p_chain->usable_per_page * page_cnt;
	p_chain->size = p_chain->elem_per_page * page_cnt;

	p_chain->pbl_sp.p_phys_table = 0;
	p_chain->pbl_sp.p_virt_table = NULL;
	p_chain->pbl.pp_virt_addr_tbl = NULL;
}

/**
 * @brief qed_chain_init_mem -
 *
 * Initalizes a basic chain struct with its chain buffers
 *
 * @param p_chain
 * @param p_virt_addr	virtual address of allocated buffer's beginning
 * @param p_phys_addr	physical address of allocated buffer's beginning
 *
 */
static inline void qed_chain_init_mem(struct qed_chain *p_chain,
				      void *p_virt_addr, dma_addr_t p_phys_addr)
{
	p_chain->p_virt_addr = p_virt_addr;
	p_chain->p_phys_addr = p_phys_addr;
}

/**
 * @brief qed_chain_init_pbl_mem -
 *
 * Initalizes a basic chain struct with its pbl buffers
 *
 * @param p_chain
 * @param p_virt_pbl	pointer to a pre allocated side table which will hold
 *                      virtual page addresses.
 * @param p_phys_pbl	pointer to a pre-allocated side table which will hold
 *                      physical page addresses.
 * @param pp_virt_addr_tbl
 *                      pointer to a pre-allocated side table which will hold
 *                      the virtual addresses of the chain pages.
 *
 */
static inline void qed_chain_init_pbl_mem(struct qed_chain *p_chain,
					  void *p_virt_pbl,
					  dma_addr_t p_phys_pbl,
					  void **pp_virt_addr_tbl)
{
	p_chain->pbl_sp.p_phys_table = p_phys_pbl;
	p_chain->pbl_sp.p_virt_table = p_virt_pbl;
	p_chain->pbl.pp_virt_addr_tbl = pp_virt_addr_tbl;
}

/**
 * @brief qed_chain_init_next_ptr_elem -
 *
 * Initalizes a next pointer element
 *
 * @param p_chain
 * @param p_virt_curr	virtual address of a chain page of which the next
 *                      pointer element is initialized
 * @param p_virt_next	virtual address of the next chain page
 * @param p_phys_next	physical address of the next chain page
 *
 */
static inline void
qed_chain_init_next_ptr_elem(struct qed_chain *p_chain,
			     void *p_virt_curr,
			     void *p_virt_next, dma_addr_t p_phys_next)
{
	struct qed_chain_next *p_next;
	u32 size;

	size = p_chain->elem_size * p_chain->usable_per_page;
	p_next = (struct qed_chain_next *)((u8 *)p_virt_curr + size);

	DMA_REGPAIR_LE(p_next->next_phys, p_phys_next);

	p_next->next_virt = p_virt_next;
}

/**
 * @brief qed_chain_get_last_elem -
 *
 * Returns a pointer to the last element of the chain
 *
 * @param p_chain
 *
 * @return void*
 */
static inline void *qed_chain_get_last_elem(struct qed_chain *p_chain)
{
	struct qed_chain_next *p_next = NULL;
	void *p_virt_addr = NULL;
	u32 size, last_page_idx;

	if (!p_chain->p_virt_addr)
		goto out;

	switch (p_chain->mode) {
	case QED_CHAIN_MODE_NEXT_PTR:
		size = p_chain->elem_size * p_chain->usable_per_page;
		p_virt_addr = p_chain->p_virt_addr;
		p_next = (struct qed_chain_next *)((u8 *)p_virt_addr + size);
		while (p_next->next_virt != p_chain->p_virt_addr) {
			p_virt_addr = p_next->next_virt;
			p_next = (struct qed_chain_next *)((u8 *)p_virt_addr +
							   size);
		}
		break;
	case QED_CHAIN_MODE_SINGLE:
		p_virt_addr = p_chain->p_virt_addr;
		break;
	case QED_CHAIN_MODE_PBL:
		last_page_idx = p_chain->page_cnt - 1;
		p_virt_addr = p_chain->pbl.pp_virt_addr_tbl[last_page_idx];
		break;
	}
	/* p_virt_addr points at this stage to the last page of the chain */
	size = p_chain->elem_size * (p_chain->usable_per_page - 1);
	p_virt_addr = (u8 *)p_virt_addr + size;
out:
	return p_virt_addr;
}

/**
 * @brief qed_chain_set_prod - sets the prod to the given value
 *
 * @param prod_idx
 * @param p_prod_elem
 */
static inline void qed_chain_set_prod(struct qed_chain *p_chain,
				      u32 prod_idx, void *p_prod_elem)
{
	if (p_chain->mode == QED_CHAIN_MODE_PBL) {
		u32 cur_prod, page_mask, page_cnt, page_diff;

		cur_prod = is_chain_u16(p_chain) ? p_chain->u.chain16.prod_idx :
			   p_chain->u.chain32.prod_idx;

		/* Assume that number of elements in a page is power of 2 */
		page_mask = ~p_chain->elem_per_page_mask;

		/* Use "cur_prod - 1" and "prod_idx - 1" since producer index
		 * reaches the first element of next page before the page index
		 * is incremented. See qed_chain_produce().
		 * Index wrap around is not a problem because the difference
		 * between current and given producer indices is always
		 * positive and lower than the chain's capacity.
		 */
		page_diff = (((cur_prod - 1) & page_mask) -
			     ((prod_idx - 1) & page_mask)) /
			    p_chain->elem_per_page;

		page_cnt = qed_chain_get_page_cnt(p_chain);
		if (is_chain_u16(p_chain))
			p_chain->pbl.c.u16.prod_page_idx =
				(p_chain->pbl.c.u16.prod_page_idx -
				 page_diff + page_cnt) % page_cnt;
		else
			p_chain->pbl.c.u32.prod_page_idx =
				(p_chain->pbl.c.u32.prod_page_idx -
				 page_diff + page_cnt) % page_cnt;
	}

	if (is_chain_u16(p_chain))
		p_chain->u.chain16.prod_idx = (u16) prod_idx;
	else
		p_chain->u.chain32.prod_idx = prod_idx;
	p_chain->p_prod_elem = p_prod_elem;
}

/**
 * @brief qed_chain_pbl_zero_mem - set chain memory to 0
 *
 * @param p_chain
 */
static inline void qed_chain_pbl_zero_mem(struct qed_chain *p_chain)
{
	u32 i, page_cnt;

	if (p_chain->mode != QED_CHAIN_MODE_PBL)
		return;

	page_cnt = qed_chain_get_page_cnt(p_chain);

	for (i = 0; i < page_cnt; i++)
		memset(p_chain->pbl.pp_virt_addr_tbl[i], 0,
		       QED_CHAIN_PAGE_SIZE);
}

#endif