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1da177e4 LT |
1 | #ifndef _LINUX_SCATTERLIST_H |
2 | #define _LINUX_SCATTERLIST_H | |
3 | ||
85cdffcd | 4 | #include <asm/types.h> |
d32311fe HX |
5 | #include <asm/scatterlist.h> |
6 | #include <linux/mm.h> | |
7 | #include <linux/string.h> | |
18dabf47 JA |
8 | #include <asm/io.h> |
9 | ||
0db9299f JA |
10 | struct sg_table { |
11 | struct scatterlist *sgl; /* the list */ | |
12 | unsigned int nents; /* number of mapped entries */ | |
13 | unsigned int orig_nents; /* original size of list */ | |
14 | }; | |
15 | ||
18dabf47 JA |
16 | /* |
17 | * Notes on SG table design. | |
18 | * | |
19 | * Architectures must provide an unsigned long page_link field in the | |
20 | * scatterlist struct. We use that to place the page pointer AND encode | |
21 | * information about the sg table as well. The two lower bits are reserved | |
22 | * for this information. | |
23 | * | |
24 | * If bit 0 is set, then the page_link contains a pointer to the next sg | |
25 | * table list. Otherwise the next entry is at sg + 1. | |
26 | * | |
27 | * If bit 1 is set, then this sg entry is the last element in a list. | |
28 | * | |
29 | * See sg_next(). | |
30 | * | |
31 | */ | |
1da177e4 | 32 | |
d6ec0842 JA |
33 | #define SG_MAGIC 0x87654321 |
34 | ||
645a8d94 TH |
35 | /* |
36 | * We overload the LSB of the page pointer to indicate whether it's | |
37 | * a valid sg entry, or whether it points to the start of a new scatterlist. | |
38 | * Those low bits are there for everyone! (thanks mason :-) | |
39 | */ | |
40 | #define sg_is_chain(sg) ((sg)->page_link & 0x01) | |
41 | #define sg_is_last(sg) ((sg)->page_link & 0x02) | |
42 | #define sg_chain_ptr(sg) \ | |
43 | ((struct scatterlist *) ((sg)->page_link & ~0x03)) | |
44 | ||
82f66fbe | 45 | /** |
642f1490 JA |
46 | * sg_assign_page - Assign a given page to an SG entry |
47 | * @sg: SG entry | |
48 | * @page: The page | |
82f66fbe JA |
49 | * |
50 | * Description: | |
642f1490 JA |
51 | * Assign page to sg entry. Also see sg_set_page(), the most commonly used |
52 | * variant. | |
82f66fbe JA |
53 | * |
54 | **/ | |
642f1490 | 55 | static inline void sg_assign_page(struct scatterlist *sg, struct page *page) |
82f66fbe | 56 | { |
18dabf47 JA |
57 | unsigned long page_link = sg->page_link & 0x3; |
58 | ||
de26103d JA |
59 | /* |
60 | * In order for the low bit stealing approach to work, pages | |
61 | * must be aligned at a 32-bit boundary as a minimum. | |
62 | */ | |
63 | BUG_ON((unsigned long) page & 0x03); | |
d6ec0842 JA |
64 | #ifdef CONFIG_DEBUG_SG |
65 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
645a8d94 | 66 | BUG_ON(sg_is_chain(sg)); |
d6ec0842 | 67 | #endif |
18dabf47 | 68 | sg->page_link = page_link | (unsigned long) page; |
82f66fbe JA |
69 | } |
70 | ||
642f1490 JA |
71 | /** |
72 | * sg_set_page - Set sg entry to point at given page | |
73 | * @sg: SG entry | |
74 | * @page: The page | |
75 | * @len: Length of data | |
76 | * @offset: Offset into page | |
77 | * | |
78 | * Description: | |
79 | * Use this function to set an sg entry pointing at a page, never assign | |
80 | * the page directly. We encode sg table information in the lower bits | |
81 | * of the page pointer. See sg_page() for looking up the page belonging | |
82 | * to an sg entry. | |
83 | * | |
84 | **/ | |
85 | static inline void sg_set_page(struct scatterlist *sg, struct page *page, | |
86 | unsigned int len, unsigned int offset) | |
87 | { | |
88 | sg_assign_page(sg, page); | |
89 | sg->offset = offset; | |
90 | sg->length = len; | |
91 | } | |
92 | ||
645a8d94 TH |
93 | static inline struct page *sg_page(struct scatterlist *sg) |
94 | { | |
95 | #ifdef CONFIG_DEBUG_SG | |
96 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
97 | BUG_ON(sg_is_chain(sg)); | |
98 | #endif | |
99 | return (struct page *)((sg)->page_link & ~0x3); | |
100 | } | |
82f66fbe | 101 | |
18dabf47 JA |
102 | /** |
103 | * sg_set_buf - Set sg entry to point at given data | |
104 | * @sg: SG entry | |
105 | * @buf: Data | |
106 | * @buflen: Data length | |
107 | * | |
108 | **/ | |
03fd9cee | 109 | static inline void sg_set_buf(struct scatterlist *sg, const void *buf, |
d32311fe HX |
110 | unsigned int buflen) |
111 | { | |
642f1490 | 112 | sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); |
1da177e4 LT |
113 | } |
114 | ||
96b418c9 JA |
115 | /* |
116 | * Loop over each sg element, following the pointer to a new list if necessary | |
117 | */ | |
118 | #define for_each_sg(sglist, sg, nr, __i) \ | |
119 | for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) | |
120 | ||
70eb8040 JA |
121 | /** |
122 | * sg_chain - Chain two sglists together | |
123 | * @prv: First scatterlist | |
124 | * @prv_nents: Number of entries in prv | |
125 | * @sgl: Second scatterlist | |
126 | * | |
18dabf47 JA |
127 | * Description: |
128 | * Links @prv@ and @sgl@ together, to form a longer scatterlist. | |
70eb8040 | 129 | * |
18dabf47 | 130 | **/ |
70eb8040 JA |
131 | static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, |
132 | struct scatterlist *sgl) | |
133 | { | |
134 | #ifndef ARCH_HAS_SG_CHAIN | |
135 | BUG(); | |
136 | #endif | |
645a8d94 TH |
137 | |
138 | /* | |
139 | * offset and length are unused for chain entry. Clear them. | |
140 | */ | |
b801a1e7 RR |
141 | prv[prv_nents - 1].offset = 0; |
142 | prv[prv_nents - 1].length = 0; | |
645a8d94 | 143 | |
73fd546a JA |
144 | /* |
145 | * Set lowest bit to indicate a link pointer, and make sure to clear | |
146 | * the termination bit if it happens to be set. | |
147 | */ | |
148 | prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02; | |
70eb8040 JA |
149 | } |
150 | ||
82f66fbe JA |
151 | /** |
152 | * sg_mark_end - Mark the end of the scatterlist | |
c46f2334 | 153 | * @sg: SG entryScatterlist |
82f66fbe JA |
154 | * |
155 | * Description: | |
c46f2334 JA |
156 | * Marks the passed in sg entry as the termination point for the sg |
157 | * table. A call to sg_next() on this entry will return NULL. | |
82f66fbe JA |
158 | * |
159 | **/ | |
c46f2334 | 160 | static inline void sg_mark_end(struct scatterlist *sg) |
82f66fbe | 161 | { |
c46f2334 JA |
162 | #ifdef CONFIG_DEBUG_SG |
163 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
164 | #endif | |
165 | /* | |
166 | * Set termination bit, clear potential chain bit | |
167 | */ | |
18dabf47 | 168 | sg->page_link |= 0x02; |
c46f2334 | 169 | sg->page_link &= ~0x01; |
82f66fbe JA |
170 | } |
171 | ||
82f66fbe JA |
172 | /** |
173 | * sg_phys - Return physical address of an sg entry | |
174 | * @sg: SG entry | |
175 | * | |
176 | * Description: | |
177 | * This calls page_to_phys() on the page in this sg entry, and adds the | |
178 | * sg offset. The caller must know that it is legal to call page_to_phys() | |
179 | * on the sg page. | |
180 | * | |
181 | **/ | |
85cdffcd | 182 | static inline dma_addr_t sg_phys(struct scatterlist *sg) |
82f66fbe JA |
183 | { |
184 | return page_to_phys(sg_page(sg)) + sg->offset; | |
185 | } | |
186 | ||
187 | /** | |
188 | * sg_virt - Return virtual address of an sg entry | |
18dabf47 | 189 | * @sg: SG entry |
82f66fbe JA |
190 | * |
191 | * Description: | |
192 | * This calls page_address() on the page in this sg entry, and adds the | |
193 | * sg offset. The caller must know that the sg page has a valid virtual | |
194 | * mapping. | |
195 | * | |
196 | **/ | |
197 | static inline void *sg_virt(struct scatterlist *sg) | |
198 | { | |
199 | return page_address(sg_page(sg)) + sg->offset; | |
200 | } | |
201 | ||
0db9299f JA |
202 | struct scatterlist *sg_next(struct scatterlist *); |
203 | struct scatterlist *sg_last(struct scatterlist *s, unsigned int); | |
204 | void sg_init_table(struct scatterlist *, unsigned int); | |
205 | void sg_init_one(struct scatterlist *, const void *, unsigned int); | |
206 | ||
207 | typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); | |
208 | typedef void (sg_free_fn)(struct scatterlist *, unsigned int); | |
209 | ||
7cedb1f1 | 210 | void __sg_free_table(struct sg_table *, unsigned int, sg_free_fn *); |
0db9299f | 211 | void sg_free_table(struct sg_table *); |
7cedb1f1 JB |
212 | int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, gfp_t, |
213 | sg_alloc_fn *); | |
0db9299f JA |
214 | int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); |
215 | ||
b1adaf65 FT |
216 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
217 | void *buf, size_t buflen); | |
218 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
219 | void *buf, size_t buflen); | |
220 | ||
0db9299f JA |
221 | /* |
222 | * Maximum number of entries that will be allocated in one piece, if | |
223 | * a list larger than this is required then chaining will be utilized. | |
224 | */ | |
225 | #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) | |
226 | ||
137d3edb TH |
227 | |
228 | /* | |
229 | * Mapping sg iterator | |
230 | * | |
231 | * Iterates over sg entries mapping page-by-page. On each successful | |
232 | * iteration, @miter->page points to the mapped page and | |
233 | * @miter->length bytes of data can be accessed at @miter->addr. As | |
234 | * long as an interation is enclosed between start and stop, the user | |
235 | * is free to choose control structure and when to stop. | |
236 | * | |
237 | * @miter->consumed is set to @miter->length on each iteration. It | |
238 | * can be adjusted if the user can't consume all the bytes in one go. | |
239 | * Also, a stopped iteration can be resumed by calling next on it. | |
240 | * This is useful when iteration needs to release all resources and | |
241 | * continue later (e.g. at the next interrupt). | |
242 | */ | |
243 | ||
244 | #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ | |
245 | ||
246 | struct sg_mapping_iter { | |
247 | /* the following three fields can be accessed directly */ | |
248 | struct page *page; /* currently mapped page */ | |
249 | void *addr; /* pointer to the mapped area */ | |
250 | size_t length; /* length of the mapped area */ | |
251 | size_t consumed; /* number of consumed bytes */ | |
252 | ||
253 | /* these are internal states, keep away */ | |
254 | struct scatterlist *__sg; /* current entry */ | |
255 | unsigned int __nents; /* nr of remaining entries */ | |
256 | unsigned int __offset; /* offset within sg */ | |
257 | unsigned int __flags; | |
258 | }; | |
259 | ||
260 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, | |
261 | unsigned int nents, unsigned int flags); | |
262 | bool sg_miter_next(struct sg_mapping_iter *miter); | |
263 | void sg_miter_stop(struct sg_mapping_iter *miter); | |
264 | ||
1da177e4 | 265 | #endif /* _LINUX_SCATTERLIST_H */ |