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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | #ifndef _LINUX_SCATTERLIST_H |
3 | #define _LINUX_SCATTERLIST_H | |
4 | ||
187f1882 | 5 | #include <linux/string.h> |
84be456f | 6 | #include <linux/types.h> |
187f1882 PG |
7 | #include <linux/bug.h> |
8 | #include <linux/mm.h> | |
18dabf47 JA |
9 | #include <asm/io.h> |
10 | ||
84be456f | 11 | struct scatterlist { |
84be456f CH |
12 | unsigned long page_link; |
13 | unsigned int offset; | |
14 | unsigned int length; | |
15 | dma_addr_t dma_address; | |
16 | #ifdef CONFIG_NEED_SG_DMA_LENGTH | |
17 | unsigned int dma_length; | |
18 | #endif | |
19 | }; | |
20 | ||
21 | /* | |
22 | * These macros should be used after a dma_map_sg call has been done | |
23 | * to get bus addresses of each of the SG entries and their lengths. | |
24 | * You should only work with the number of sg entries dma_map_sg | |
25 | * returns, or alternatively stop on the first sg_dma_len(sg) which | |
26 | * is 0. | |
27 | */ | |
28 | #define sg_dma_address(sg) ((sg)->dma_address) | |
29 | ||
30 | #ifdef CONFIG_NEED_SG_DMA_LENGTH | |
31 | #define sg_dma_len(sg) ((sg)->dma_length) | |
32 | #else | |
33 | #define sg_dma_len(sg) ((sg)->length) | |
34 | #endif | |
35 | ||
0db9299f JA |
36 | struct sg_table { |
37 | struct scatterlist *sgl; /* the list */ | |
38 | unsigned int nents; /* number of mapped entries */ | |
39 | unsigned int orig_nents; /* original size of list */ | |
40 | }; | |
41 | ||
18dabf47 JA |
42 | /* |
43 | * Notes on SG table design. | |
44 | * | |
84be456f CH |
45 | * We use the unsigned long page_link field in the scatterlist struct to place |
46 | * the page pointer AND encode information about the sg table as well. The two | |
47 | * lower bits are reserved for this information. | |
18dabf47 JA |
48 | * |
49 | * If bit 0 is set, then the page_link contains a pointer to the next sg | |
50 | * table list. Otherwise the next entry is at sg + 1. | |
51 | * | |
52 | * If bit 1 is set, then this sg entry is the last element in a list. | |
53 | * | |
54 | * See sg_next(). | |
55 | * | |
56 | */ | |
1da177e4 | 57 | |
723fbf56 AK |
58 | #define SG_CHAIN 0x01UL |
59 | #define SG_END 0x02UL | |
d6ec0842 | 60 | |
645a8d94 TH |
61 | /* |
62 | * We overload the LSB of the page pointer to indicate whether it's | |
63 | * a valid sg entry, or whether it points to the start of a new scatterlist. | |
64 | * Those low bits are there for everyone! (thanks mason :-) | |
65 | */ | |
723fbf56 AK |
66 | #define sg_is_chain(sg) ((sg)->page_link & SG_CHAIN) |
67 | #define sg_is_last(sg) ((sg)->page_link & SG_END) | |
645a8d94 | 68 | #define sg_chain_ptr(sg) \ |
723fbf56 | 69 | ((struct scatterlist *) ((sg)->page_link & ~(SG_CHAIN | SG_END))) |
645a8d94 | 70 | |
82f66fbe | 71 | /** |
642f1490 JA |
72 | * sg_assign_page - Assign a given page to an SG entry |
73 | * @sg: SG entry | |
74 | * @page: The page | |
82f66fbe JA |
75 | * |
76 | * Description: | |
642f1490 JA |
77 | * Assign page to sg entry. Also see sg_set_page(), the most commonly used |
78 | * variant. | |
82f66fbe JA |
79 | * |
80 | **/ | |
642f1490 | 81 | static inline void sg_assign_page(struct scatterlist *sg, struct page *page) |
82f66fbe | 82 | { |
723fbf56 | 83 | unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END); |
18dabf47 | 84 | |
de26103d JA |
85 | /* |
86 | * In order for the low bit stealing approach to work, pages | |
87 | * must be aligned at a 32-bit boundary as a minimum. | |
88 | */ | |
723fbf56 | 89 | BUG_ON((unsigned long) page & (SG_CHAIN | SG_END)); |
d6ec0842 | 90 | #ifdef CONFIG_DEBUG_SG |
645a8d94 | 91 | BUG_ON(sg_is_chain(sg)); |
d6ec0842 | 92 | #endif |
18dabf47 | 93 | sg->page_link = page_link | (unsigned long) page; |
82f66fbe JA |
94 | } |
95 | ||
642f1490 JA |
96 | /** |
97 | * sg_set_page - Set sg entry to point at given page | |
98 | * @sg: SG entry | |
99 | * @page: The page | |
100 | * @len: Length of data | |
101 | * @offset: Offset into page | |
102 | * | |
103 | * Description: | |
104 | * Use this function to set an sg entry pointing at a page, never assign | |
105 | * the page directly. We encode sg table information in the lower bits | |
106 | * of the page pointer. See sg_page() for looking up the page belonging | |
107 | * to an sg entry. | |
108 | * | |
109 | **/ | |
110 | static inline void sg_set_page(struct scatterlist *sg, struct page *page, | |
111 | unsigned int len, unsigned int offset) | |
112 | { | |
113 | sg_assign_page(sg, page); | |
114 | sg->offset = offset; | |
115 | sg->length = len; | |
116 | } | |
117 | ||
645a8d94 TH |
118 | static inline struct page *sg_page(struct scatterlist *sg) |
119 | { | |
120 | #ifdef CONFIG_DEBUG_SG | |
645a8d94 TH |
121 | BUG_ON(sg_is_chain(sg)); |
122 | #endif | |
723fbf56 | 123 | return (struct page *)((sg)->page_link & ~(SG_CHAIN | SG_END)); |
645a8d94 | 124 | } |
82f66fbe | 125 | |
18dabf47 JA |
126 | /** |
127 | * sg_set_buf - Set sg entry to point at given data | |
128 | * @sg: SG entry | |
129 | * @buf: Data | |
130 | * @buflen: Data length | |
131 | * | |
132 | **/ | |
03fd9cee | 133 | static inline void sg_set_buf(struct scatterlist *sg, const void *buf, |
d32311fe HX |
134 | unsigned int buflen) |
135 | { | |
ac4e97ab RR |
136 | #ifdef CONFIG_DEBUG_SG |
137 | BUG_ON(!virt_addr_valid(buf)); | |
138 | #endif | |
642f1490 | 139 | sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); |
1da177e4 LT |
140 | } |
141 | ||
96b418c9 JA |
142 | /* |
143 | * Loop over each sg element, following the pointer to a new list if necessary | |
144 | */ | |
145 | #define for_each_sg(sglist, sg, nr, __i) \ | |
146 | for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) | |
147 | ||
709d6d73 MS |
148 | /* |
149 | * Loop over each sg element in the given sg_table object. | |
150 | */ | |
151 | #define for_each_sgtable_sg(sgt, sg, i) \ | |
68d23705 | 152 | for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i) |
709d6d73 MS |
153 | |
154 | /* | |
155 | * Loop over each sg element in the given *DMA mapped* sg_table object. | |
156 | * Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses | |
157 | * of the each element. | |
158 | */ | |
159 | #define for_each_sgtable_dma_sg(sgt, sg, i) \ | |
68d23705 | 160 | for_each_sg((sgt)->sgl, sg, (sgt)->nents, i) |
709d6d73 | 161 | |
07da1223 MG |
162 | static inline void __sg_chain(struct scatterlist *chain_sg, |
163 | struct scatterlist *sgl) | |
164 | { | |
165 | /* | |
166 | * offset and length are unused for chain entry. Clear them. | |
167 | */ | |
168 | chain_sg->offset = 0; | |
169 | chain_sg->length = 0; | |
170 | ||
171 | /* | |
172 | * Set lowest bit to indicate a link pointer, and make sure to clear | |
173 | * the termination bit if it happens to be set. | |
174 | */ | |
175 | chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END; | |
176 | } | |
177 | ||
70eb8040 JA |
178 | /** |
179 | * sg_chain - Chain two sglists together | |
180 | * @prv: First scatterlist | |
181 | * @prv_nents: Number of entries in prv | |
182 | * @sgl: Second scatterlist | |
183 | * | |
18dabf47 JA |
184 | * Description: |
185 | * Links @prv@ and @sgl@ together, to form a longer scatterlist. | |
70eb8040 | 186 | * |
18dabf47 | 187 | **/ |
70eb8040 JA |
188 | static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, |
189 | struct scatterlist *sgl) | |
190 | { | |
07da1223 | 191 | __sg_chain(&prv[prv_nents - 1], sgl); |
70eb8040 JA |
192 | } |
193 | ||
82f66fbe JA |
194 | /** |
195 | * sg_mark_end - Mark the end of the scatterlist | |
c46f2334 | 196 | * @sg: SG entryScatterlist |
82f66fbe JA |
197 | * |
198 | * Description: | |
c46f2334 JA |
199 | * Marks the passed in sg entry as the termination point for the sg |
200 | * table. A call to sg_next() on this entry will return NULL. | |
82f66fbe JA |
201 | * |
202 | **/ | |
c46f2334 | 203 | static inline void sg_mark_end(struct scatterlist *sg) |
82f66fbe | 204 | { |
c46f2334 JA |
205 | /* |
206 | * Set termination bit, clear potential chain bit | |
207 | */ | |
723fbf56 AK |
208 | sg->page_link |= SG_END; |
209 | sg->page_link &= ~SG_CHAIN; | |
82f66fbe JA |
210 | } |
211 | ||
c8164d89 PB |
212 | /** |
213 | * sg_unmark_end - Undo setting the end of the scatterlist | |
214 | * @sg: SG entryScatterlist | |
215 | * | |
216 | * Description: | |
217 | * Removes the termination marker from the given entry of the scatterlist. | |
218 | * | |
219 | **/ | |
220 | static inline void sg_unmark_end(struct scatterlist *sg) | |
221 | { | |
723fbf56 | 222 | sg->page_link &= ~SG_END; |
c8164d89 PB |
223 | } |
224 | ||
82f66fbe JA |
225 | /** |
226 | * sg_phys - Return physical address of an sg entry | |
227 | * @sg: SG entry | |
228 | * | |
229 | * Description: | |
230 | * This calls page_to_phys() on the page in this sg entry, and adds the | |
231 | * sg offset. The caller must know that it is legal to call page_to_phys() | |
232 | * on the sg page. | |
233 | * | |
234 | **/ | |
85cdffcd | 235 | static inline dma_addr_t sg_phys(struct scatterlist *sg) |
82f66fbe JA |
236 | { |
237 | return page_to_phys(sg_page(sg)) + sg->offset; | |
238 | } | |
239 | ||
240 | /** | |
241 | * sg_virt - Return virtual address of an sg entry | |
18dabf47 | 242 | * @sg: SG entry |
82f66fbe JA |
243 | * |
244 | * Description: | |
245 | * This calls page_address() on the page in this sg entry, and adds the | |
246 | * sg offset. The caller must know that the sg page has a valid virtual | |
247 | * mapping. | |
248 | * | |
249 | **/ | |
250 | static inline void *sg_virt(struct scatterlist *sg) | |
251 | { | |
252 | return page_address(sg_page(sg)) + sg->offset; | |
253 | } | |
254 | ||
f3851786 PB |
255 | /** |
256 | * sg_init_marker - Initialize markers in sg table | |
257 | * @sgl: The SG table | |
258 | * @nents: Number of entries in table | |
259 | * | |
260 | **/ | |
261 | static inline void sg_init_marker(struct scatterlist *sgl, | |
262 | unsigned int nents) | |
263 | { | |
f3851786 PB |
264 | sg_mark_end(&sgl[nents - 1]); |
265 | } | |
266 | ||
2e484610 | 267 | int sg_nents(struct scatterlist *sg); |
cfaed10d | 268 | int sg_nents_for_len(struct scatterlist *sg, u64 len); |
0db9299f JA |
269 | struct scatterlist *sg_next(struct scatterlist *); |
270 | struct scatterlist *sg_last(struct scatterlist *s, unsigned int); | |
271 | void sg_init_table(struct scatterlist *, unsigned int); | |
272 | void sg_init_one(struct scatterlist *, const void *, unsigned int); | |
f8bcbe62 RJ |
273 | int sg_split(struct scatterlist *in, const int in_mapped_nents, |
274 | const off_t skip, const int nb_splits, | |
275 | const size_t *split_sizes, | |
276 | struct scatterlist **out, int *out_mapped_nents, | |
277 | gfp_t gfp_mask); | |
0db9299f JA |
278 | |
279 | typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); | |
280 | typedef void (sg_free_fn)(struct scatterlist *, unsigned int); | |
281 | ||
4635873c ML |
282 | void __sg_free_table(struct sg_table *, unsigned int, unsigned int, |
283 | sg_free_fn *); | |
0db9299f | 284 | void sg_free_table(struct sg_table *); |
c53c6d6a | 285 | int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, |
4635873c | 286 | struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *); |
0db9299f | 287 | int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); |
07da1223 MG |
288 | struct scatterlist *__sg_alloc_table_from_pages(struct sg_table *sgt, |
289 | struct page **pages, unsigned int n_pages, unsigned int offset, | |
290 | unsigned long size, unsigned int max_segment, | |
291 | struct scatterlist *prv, unsigned int left_pages, | |
292 | gfp_t gfp_mask); | |
89d8589c TU |
293 | int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, |
294 | unsigned int n_pages, unsigned int offset, | |
295 | unsigned long size, gfp_t gfp_mask); | |
0db9299f | 296 | |
e80a0af4 BVA |
297 | #ifdef CONFIG_SGL_ALLOC |
298 | struct scatterlist *sgl_alloc_order(unsigned long long length, | |
299 | unsigned int order, bool chainable, | |
300 | gfp_t gfp, unsigned int *nent_p); | |
301 | struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, | |
302 | unsigned int *nent_p); | |
8c7a8d1c | 303 | void sgl_free_n_order(struct scatterlist *sgl, int nents, int order); |
e80a0af4 BVA |
304 | void sgl_free_order(struct scatterlist *sgl, int order); |
305 | void sgl_free(struct scatterlist *sgl); | |
306 | #endif /* CONFIG_SGL_ALLOC */ | |
307 | ||
386ecb12 DG |
308 | size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, |
309 | size_t buflen, off_t skip, bool to_buffer); | |
310 | ||
b1adaf65 | 311 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
2a1bf8f9 | 312 | const void *buf, size_t buflen); |
b1adaf65 FT |
313 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, |
314 | void *buf, size_t buflen); | |
315 | ||
df642cea | 316 | size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
2a1bf8f9 | 317 | const void *buf, size_t buflen, off_t skip); |
df642cea AM |
318 | size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, |
319 | void *buf, size_t buflen, off_t skip); | |
0945e569 JT |
320 | size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, |
321 | size_t buflen, off_t skip); | |
df642cea | 322 | |
0db9299f JA |
323 | /* |
324 | * Maximum number of entries that will be allocated in one piece, if | |
325 | * a list larger than this is required then chaining will be utilized. | |
326 | */ | |
327 | #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) | |
328 | ||
9b1d6c89 ML |
329 | /* |
330 | * The maximum number of SG segments that we will put inside a | |
331 | * scatterlist (unless chaining is used). Should ideally fit inside a | |
332 | * single page, to avoid a higher order allocation. We could define this | |
333 | * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The | |
334 | * minimum value is 32 | |
335 | */ | |
336 | #define SG_CHUNK_SIZE 128 | |
337 | ||
338 | /* | |
339 | * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit | |
340 | * is totally arbitrary, a setting of 2048 will get you at least 8mb ios. | |
341 | */ | |
7c703e54 | 342 | #ifdef CONFIG_ARCH_NO_SG_CHAIN |
9b1d6c89 | 343 | #define SG_MAX_SEGMENTS SG_CHUNK_SIZE |
7c703e54 CH |
344 | #else |
345 | #define SG_MAX_SEGMENTS 2048 | |
9b1d6c89 ML |
346 | #endif |
347 | ||
348 | #ifdef CONFIG_SG_POOL | |
4635873c ML |
349 | void sg_free_table_chained(struct sg_table *table, |
350 | unsigned nents_first_chunk); | |
9b1d6c89 | 351 | int sg_alloc_table_chained(struct sg_table *table, int nents, |
4635873c ML |
352 | struct scatterlist *first_chunk, |
353 | unsigned nents_first_chunk); | |
9b1d6c89 ML |
354 | #endif |
355 | ||
a321e91b ID |
356 | /* |
357 | * sg page iterator | |
358 | * | |
d901b276 | 359 | * Iterates over sg entries page-by-page. On each successful iteration, you |
d2c4ada1 GP |
360 | * can call sg_page_iter_page(@piter) to get the current page. |
361 | * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to | |
362 | * the page's page offset within the sg. The iteration will stop either when a | |
363 | * maximum number of sg entries was reached or a terminating sg | |
364 | * (sg_last(sg) == true) was reached. | |
a321e91b ID |
365 | */ |
366 | struct sg_page_iter { | |
a321e91b ID |
367 | struct scatterlist *sg; /* sg holding the page */ |
368 | unsigned int sg_pgoffset; /* page offset within the sg */ | |
369 | ||
370 | /* these are internal states, keep away */ | |
371 | unsigned int __nents; /* remaining sg entries */ | |
372 | int __pg_advance; /* nr pages to advance at the | |
373 | * next step */ | |
374 | }; | |
375 | ||
d901b276 JG |
376 | /* |
377 | * sg page iterator for DMA addresses | |
378 | * | |
379 | * This is the same as sg_page_iter however you can call | |
380 | * sg_page_iter_dma_address(@dma_iter) to get the page's DMA | |
381 | * address. sg_page_iter_page() cannot be called on this iterator. | |
382 | */ | |
383 | struct sg_dma_page_iter { | |
384 | struct sg_page_iter base; | |
385 | }; | |
386 | ||
a321e91b | 387 | bool __sg_page_iter_next(struct sg_page_iter *piter); |
d901b276 | 388 | bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter); |
a321e91b ID |
389 | void __sg_page_iter_start(struct sg_page_iter *piter, |
390 | struct scatterlist *sglist, unsigned int nents, | |
391 | unsigned long pgoffset); | |
2db76d7c ID |
392 | /** |
393 | * sg_page_iter_page - get the current page held by the page iterator | |
394 | * @piter: page iterator holding the page | |
395 | */ | |
396 | static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) | |
397 | { | |
398 | return nth_page(sg_page(piter->sg), piter->sg_pgoffset); | |
399 | } | |
400 | ||
401 | /** | |
402 | * sg_page_iter_dma_address - get the dma address of the current page held by | |
403 | * the page iterator. | |
d901b276 | 404 | * @dma_iter: page iterator holding the page |
2db76d7c | 405 | */ |
d901b276 JG |
406 | static inline dma_addr_t |
407 | sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter) | |
2db76d7c | 408 | { |
d901b276 JG |
409 | return sg_dma_address(dma_iter->base.sg) + |
410 | (dma_iter->base.sg_pgoffset << PAGE_SHIFT); | |
2db76d7c | 411 | } |
a321e91b ID |
412 | |
413 | /** | |
414 | * for_each_sg_page - iterate over the pages of the given sg list | |
415 | * @sglist: sglist to iterate over | |
416 | * @piter: page iterator to hold current page, sg, sg_pgoffset | |
417 | * @nents: maximum number of sg entries to iterate over | |
709d6d73 | 418 | * @pgoffset: starting page offset (in pages) |
d901b276 JG |
419 | * |
420 | * Callers may use sg_page_iter_page() to get each page pointer. | |
709d6d73 | 421 | * In each loop it operates on PAGE_SIZE unit. |
a321e91b ID |
422 | */ |
423 | #define for_each_sg_page(sglist, piter, nents, pgoffset) \ | |
424 | for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \ | |
425 | __sg_page_iter_next(piter);) | |
137d3edb | 426 | |
d901b276 JG |
427 | /** |
428 | * for_each_sg_dma_page - iterate over the pages of the given sg list | |
429 | * @sglist: sglist to iterate over | |
709d6d73 | 430 | * @dma_iter: DMA page iterator to hold current page |
d901b276 JG |
431 | * @dma_nents: maximum number of sg entries to iterate over, this is the value |
432 | * returned from dma_map_sg | |
709d6d73 | 433 | * @pgoffset: starting page offset (in pages) |
d901b276 JG |
434 | * |
435 | * Callers may use sg_page_iter_dma_address() to get each page's DMA address. | |
709d6d73 | 436 | * In each loop it operates on PAGE_SIZE unit. |
d901b276 JG |
437 | */ |
438 | #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \ | |
439 | for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \ | |
440 | pgoffset); \ | |
441 | __sg_page_iter_dma_next(dma_iter);) | |
442 | ||
709d6d73 MS |
443 | /** |
444 | * for_each_sgtable_page - iterate over all pages in the sg_table object | |
445 | * @sgt: sg_table object to iterate over | |
446 | * @piter: page iterator to hold current page | |
447 | * @pgoffset: starting page offset (in pages) | |
448 | * | |
449 | * Iterates over the all memory pages in the buffer described by | |
450 | * a scatterlist stored in the given sg_table object. | |
451 | * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit. | |
452 | */ | |
453 | #define for_each_sgtable_page(sgt, piter, pgoffset) \ | |
68d23705 | 454 | for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset) |
709d6d73 MS |
455 | |
456 | /** | |
457 | * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object | |
458 | * @sgt: sg_table object to iterate over | |
459 | * @dma_iter: DMA page iterator to hold current page | |
460 | * @pgoffset: starting page offset (in pages) | |
461 | * | |
462 | * Iterates over the all DMA mapped pages in the buffer described by | |
463 | * a scatterlist stored in the given sg_table object. | |
464 | * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE | |
465 | * unit. | |
466 | */ | |
467 | #define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \ | |
68d23705 | 468 | for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset) |
709d6d73 MS |
469 | |
470 | ||
137d3edb TH |
471 | /* |
472 | * Mapping sg iterator | |
473 | * | |
474 | * Iterates over sg entries mapping page-by-page. On each successful | |
475 | * iteration, @miter->page points to the mapped page and | |
476 | * @miter->length bytes of data can be accessed at @miter->addr. As | |
477 | * long as an interation is enclosed between start and stop, the user | |
478 | * is free to choose control structure and when to stop. | |
479 | * | |
480 | * @miter->consumed is set to @miter->length on each iteration. It | |
481 | * can be adjusted if the user can't consume all the bytes in one go. | |
482 | * Also, a stopped iteration can be resumed by calling next on it. | |
483 | * This is useful when iteration needs to release all resources and | |
484 | * continue later (e.g. at the next interrupt). | |
485 | */ | |
486 | ||
487 | #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ | |
6de7e356 SAS |
488 | #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */ |
489 | #define SG_MITER_FROM_SG (1 << 2) /* nop */ | |
137d3edb TH |
490 | |
491 | struct sg_mapping_iter { | |
492 | /* the following three fields can be accessed directly */ | |
493 | struct page *page; /* currently mapped page */ | |
494 | void *addr; /* pointer to the mapped area */ | |
495 | size_t length; /* length of the mapped area */ | |
496 | size_t consumed; /* number of consumed bytes */ | |
4225fc85 | 497 | struct sg_page_iter piter; /* page iterator */ |
137d3edb TH |
498 | |
499 | /* these are internal states, keep away */ | |
4225fc85 ID |
500 | unsigned int __offset; /* offset within page */ |
501 | unsigned int __remaining; /* remaining bytes on page */ | |
137d3edb TH |
502 | unsigned int __flags; |
503 | }; | |
504 | ||
505 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, | |
506 | unsigned int nents, unsigned int flags); | |
0d6077f8 | 507 | bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset); |
137d3edb TH |
508 | bool sg_miter_next(struct sg_mapping_iter *miter); |
509 | void sg_miter_stop(struct sg_mapping_iter *miter); | |
510 | ||
1da177e4 | 511 | #endif /* _LINUX_SCATTERLIST_H */ |