scatterlist.h revision 271127 
1/*-
2 * Copyright (c) 2010 Isilon Systems, Inc.
3 * Copyright (c) 2010 iX Systems, Inc.
4 * Copyright (c) 2010 Panasas, Inc.
5 * Copyright (c) 2013, 2014 Mellanox Technologies, Ltd.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice unmodified, this list of conditions, and the following
13 *    disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30#ifndef	_LINUX_SCATTERLIST_H_
31#define	_LINUX_SCATTERLIST_H_
32
33#include <linux/page.h>
34
35struct scatterlist {
36	union {
37		struct page		*page;
38		struct scatterlist	*sg;
39	} sl_un;
40	dma_addr_t	address;
41	unsigned long	offset;
42	uint32_t	length;
43	uint32_t	flags;
44};
45
46struct sg_table {
47	struct scatterlist *sgl;        /* the list */
48	unsigned int nents;             /* number of mapped entries */
49	unsigned int orig_nents;        /* original size of list */
50};
51
52#define	sg_dma_address(sg)	(sg)->address
53#define	sg_dma_len(sg)		(sg)->length
54#define	sg_page(sg)		(sg)->sl_un.page
55#define	sg_scatternext(sg)	(sg)->sl_un.sg
56
57#define	SG_END		0x01
58#define	SG_CHAIN	0x02
59
60static inline void
61sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len,
62    unsigned int offset)
63{
64	sg_page(sg) = page;
65	sg_dma_len(sg) = len;
66	sg->offset = offset;
67	if (offset > PAGE_SIZE)
68		panic("sg_set_page: Invalid offset %d\n", offset);
69}
70
71static inline void
72sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen)
73{
74	sg_set_page(sg, virt_to_page(buf), buflen,
75	    ((uintptr_t)buf) & ~PAGE_MASK);
76}
77
78static inline void
79sg_init_table(struct scatterlist *sg, unsigned int nents)
80{
81	bzero(sg, sizeof(*sg) * nents);
82	sg[nents - 1].flags = SG_END;
83}
84
85static inline struct scatterlist *
86sg_next(struct scatterlist *sg)
87{
88	if (sg->flags & SG_END)
89		return (NULL);
90	sg++;
91	if (sg->flags & SG_CHAIN)
92		sg = sg_scatternext(sg);
93	return (sg);
94}
95
96static inline vm_paddr_t
97sg_phys(struct scatterlist *sg)
98{
99	return sg_page(sg)->phys_addr + sg->offset;
100}
101
102#define	for_each_sg(sglist, sg, sgmax, _itr)				\
103	for (_itr = 0, sg = (sglist); _itr < (sgmax); _itr++, sg = sg_next(sg))
104
105#endif	/* _LINUX_SCATTERLIST_H_ */
106