1 /* $OpenBSD: scatterlist.h,v 1.7 2024/01/06 09:33:08 kettenis Exp $ */
2 /*
3 * Copyright (c) 2013, 2014, 2015 Mark Kettenis
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #ifndef _LINUX_SCATTERLIST_H
19 #define _LINUX_SCATTERLIST_H
20
21 #include <sys/types.h>
22 #include <sys/param.h>
23 #include <uvm/uvm_extern.h>
24
25 #include <linux/mm.h>
26 #include <linux/fwnode.h> /* via asm/io.h -> logic_pio.h */
27
28 struct scatterlist {
29 struct vm_page *__page;
30 dma_addr_t dma_address;
31 unsigned int offset;
32 unsigned int length;
33 bool end;
34 };
35
36 struct sg_table {
37 struct scatterlist *sgl;
38 unsigned int nents;
39 unsigned int orig_nents;
40 bus_dmamap_t dmamap;
41 };
42
43 struct sg_page_iter {
44 struct scatterlist *sg;
45 unsigned int sg_pgoffset;
46 unsigned int __nents;
47 };
48
49 #define sg_is_chain(sg) false
50 #define sg_is_last(sg) ((sg)->end)
51 #define sg_chain_ptr(sg) NULL
52
53 static inline struct scatterlist *
sg_next(struct scatterlist * sgl)54 sg_next(struct scatterlist *sgl)
55 {
56 return sg_is_last(sgl) ? NULL : ++sgl;
57 }
58
59 int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
60 void sg_free_table(struct sg_table *);
61
62 static inline void
sg_mark_end(struct scatterlist * sgl)63 sg_mark_end(struct scatterlist *sgl)
64 {
65 sgl->end = true;
66 }
67
68 static inline void
__sg_page_iter_start(struct sg_page_iter * iter,struct scatterlist * sgl,unsigned int nents,unsigned long pgoffset)69 __sg_page_iter_start(struct sg_page_iter *iter, struct scatterlist *sgl,
70 unsigned int nents, unsigned long pgoffset)
71 {
72 iter->sg = sgl;
73 iter->sg_pgoffset = pgoffset - 1;
74 iter->__nents = nents;
75 }
76
77 static inline bool
__sg_page_iter_next(struct sg_page_iter * iter)78 __sg_page_iter_next(struct sg_page_iter *iter)
79 {
80 iter->sg_pgoffset++;
81 while (iter->__nents > 0 &&
82 iter->sg_pgoffset >= (iter->sg->length / PAGE_SIZE)) {
83 iter->sg_pgoffset -= (iter->sg->length / PAGE_SIZE);
84 iter->sg++;
85 iter->__nents--;
86 }
87
88 return (iter->__nents > 0);
89 }
90
91 static inline paddr_t
sg_page_iter_dma_address(struct sg_page_iter * iter)92 sg_page_iter_dma_address(struct sg_page_iter *iter)
93 {
94 return iter->sg->dma_address + (iter->sg_pgoffset << PAGE_SHIFT);
95 }
96
97 static inline struct vm_page *
sg_page_iter_page(struct sg_page_iter * iter)98 sg_page_iter_page(struct sg_page_iter *iter)
99 {
100 return PHYS_TO_VM_PAGE(sg_page_iter_dma_address(iter));
101 }
102
103 static inline struct vm_page *
sg_page(struct scatterlist * sgl)104 sg_page(struct scatterlist *sgl)
105 {
106 return sgl->__page;
107 }
108
109 static inline void
sg_assign_page(struct scatterlist * sgl,struct vm_page * page)110 sg_assign_page(struct scatterlist *sgl, struct vm_page *page)
111 {
112 sgl->__page = page;
113 }
114
115 static inline void
sg_set_page(struct scatterlist * sgl,struct vm_page * page,unsigned int length,unsigned int offset)116 sg_set_page(struct scatterlist *sgl, struct vm_page *page,
117 unsigned int length, unsigned int offset)
118 {
119 sgl->__page = page;
120 sgl->dma_address = page ? VM_PAGE_TO_PHYS(page) : 0;
121 sgl->offset = offset;
122 sgl->length = length;
123 }
124
125 #define sg_dma_address(sg) ((sg)->dma_address)
126 #define sg_dma_len(sg) ((sg)->length)
127
128 #define for_each_sg(sgl, sg, nents, i) \
129 for (i = 0, sg = (sgl); i < (nents); i++, sg = sg_next(sg))
130
131 #define for_each_sg_page(sgl, iter, nents, pgoffset) \
132 __sg_page_iter_start((iter), (sgl), (nents), (pgoffset)); \
133 while (__sg_page_iter_next(iter))
134
135 #define for_each_sgtable_page(st, iter, pgoffset) \
136 for_each_sg_page((st)->sgl, iter, (st)->orig_nents, pgoffset)
137
138 size_t sg_copy_from_buffer(struct scatterlist *, unsigned int,
139 const void *, size_t);
140
141 #endif
142