1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_SCATTERLIST_H |
3 | #define _LINUX_SCATTERLIST_H |
4 | |
5 | #include <linux/string.h> |
6 | #include <linux/types.h> |
7 | #include <linux/bug.h> |
8 | #include <linux/mm.h> |
9 | #include <asm/io.h> |
10 | |
11 | struct scatterlist { |
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 | #ifdef CONFIG_PCI_P2PDMA |
20 | unsigned int dma_flags; |
21 | #endif |
22 | }; |
23 | |
24 | /* |
25 | * These macros should be used after a dma_map_sg call has been done |
26 | * to get bus addresses of each of the SG entries and their lengths. |
27 | * You should only work with the number of sg entries dma_map_sg |
28 | * returns, or alternatively stop on the first sg_dma_len(sg) which |
29 | * is 0. |
30 | */ |
31 | #define sg_dma_address(sg) ((sg)->dma_address) |
32 | |
33 | #ifdef CONFIG_NEED_SG_DMA_LENGTH |
34 | #define sg_dma_len(sg) ((sg)->dma_length) |
35 | #else |
36 | #define sg_dma_len(sg) ((sg)->length) |
37 | #endif |
38 | |
39 | struct sg_table { |
40 | struct scatterlist *sgl; /* the list */ |
41 | unsigned int nents; /* number of mapped entries */ |
42 | unsigned int orig_nents; /* original size of list */ |
43 | }; |
44 | |
45 | struct sg_append_table { |
46 | struct sg_table sgt; /* The scatter list table */ |
47 | struct scatterlist *prv; /* last populated sge in the table */ |
48 | unsigned int total_nents; /* Total entries in the table */ |
49 | }; |
50 | |
51 | /* |
52 | * Notes on SG table design. |
53 | * |
54 | * We use the unsigned long page_link field in the scatterlist struct to place |
55 | * the page pointer AND encode information about the sg table as well. The two |
56 | * lower bits are reserved for this information. |
57 | * |
58 | * If bit 0 is set, then the page_link contains a pointer to the next sg |
59 | * table list. Otherwise the next entry is at sg + 1. |
60 | * |
61 | * If bit 1 is set, then this sg entry is the last element in a list. |
62 | * |
63 | * See sg_next(). |
64 | * |
65 | */ |
66 | |
67 | #define SG_CHAIN 0x01UL |
68 | #define SG_END 0x02UL |
69 | |
70 | /* |
71 | * We overload the LSB of the page pointer to indicate whether it's |
72 | * a valid sg entry, or whether it points to the start of a new scatterlist. |
73 | * Those low bits are there for everyone! (thanks mason :-) |
74 | */ |
75 | #define SG_PAGE_LINK_MASK (SG_CHAIN | SG_END) |
76 | |
77 | static inline unsigned int __sg_flags(struct scatterlist *sg) |
78 | { |
79 | return sg->page_link & SG_PAGE_LINK_MASK; |
80 | } |
81 | |
82 | static inline struct scatterlist *sg_chain_ptr(struct scatterlist *sg) |
83 | { |
84 | return (struct scatterlist *)(sg->page_link & ~SG_PAGE_LINK_MASK); |
85 | } |
86 | |
87 | static inline bool sg_is_chain(struct scatterlist *sg) |
88 | { |
89 | return __sg_flags(sg) & SG_CHAIN; |
90 | } |
91 | |
92 | static inline bool sg_is_last(struct scatterlist *sg) |
93 | { |
94 | return __sg_flags(sg) & SG_END; |
95 | } |
96 | |
97 | /** |
98 | * sg_assign_page - Assign a given page to an SG entry |
99 | * @sg: SG entry |
100 | * @page: The page |
101 | * |
102 | * Description: |
103 | * Assign page to sg entry. Also see sg_set_page(), the most commonly used |
104 | * variant. |
105 | * |
106 | **/ |
107 | static inline void sg_assign_page(struct scatterlist *sg, struct page *page) |
108 | { |
109 | unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END); |
110 | |
111 | /* |
112 | * In order for the low bit stealing approach to work, pages |
113 | * must be aligned at a 32-bit boundary as a minimum. |
114 | */ |
115 | BUG_ON((unsigned long)page & SG_PAGE_LINK_MASK); |
116 | #ifdef CONFIG_DEBUG_SG |
117 | BUG_ON(sg_is_chain(sg)); |
118 | #endif |
119 | sg->page_link = page_link | (unsigned long) page; |
120 | } |
121 | |
122 | /** |
123 | * sg_set_page - Set sg entry to point at given page |
124 | * @sg: SG entry |
125 | * @page: The page |
126 | * @len: Length of data |
127 | * @offset: Offset into page |
128 | * |
129 | * Description: |
130 | * Use this function to set an sg entry pointing at a page, never assign |
131 | * the page directly. We encode sg table information in the lower bits |
132 | * of the page pointer. See sg_page() for looking up the page belonging |
133 | * to an sg entry. |
134 | * |
135 | **/ |
136 | static inline void sg_set_page(struct scatterlist *sg, struct page *page, |
137 | unsigned int len, unsigned int offset) |
138 | { |
139 | sg_assign_page(sg, page); |
140 | sg->offset = offset; |
141 | sg->length = len; |
142 | } |
143 | |
144 | static inline struct page *sg_page(struct scatterlist *sg) |
145 | { |
146 | #ifdef CONFIG_DEBUG_SG |
147 | BUG_ON(sg_is_chain(sg)); |
148 | #endif |
149 | return (struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK); |
150 | } |
151 | |
152 | /** |
153 | * sg_set_buf - Set sg entry to point at given data |
154 | * @sg: SG entry |
155 | * @buf: Data |
156 | * @buflen: Data length |
157 | * |
158 | **/ |
159 | static inline void sg_set_buf(struct scatterlist *sg, const void *buf, |
160 | unsigned int buflen) |
161 | { |
162 | #ifdef CONFIG_DEBUG_SG |
163 | BUG_ON(!virt_addr_valid(buf)); |
164 | #endif |
165 | sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); |
166 | } |
167 | |
168 | /* |
169 | * Loop over each sg element, following the pointer to a new list if necessary |
170 | */ |
171 | #define for_each_sg(sglist, sg, nr, __i) \ |
172 | for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) |
173 | |
174 | /* |
175 | * Loop over each sg element in the given sg_table object. |
176 | */ |
177 | #define for_each_sgtable_sg(sgt, sg, i) \ |
178 | for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i) |
179 | |
180 | /* |
181 | * Loop over each sg element in the given *DMA mapped* sg_table object. |
182 | * Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses |
183 | * of the each element. |
184 | */ |
185 | #define for_each_sgtable_dma_sg(sgt, sg, i) \ |
186 | for_each_sg((sgt)->sgl, sg, (sgt)->nents, i) |
187 | |
188 | static inline void __sg_chain(struct scatterlist *chain_sg, |
189 | struct scatterlist *sgl) |
190 | { |
191 | /* |
192 | * offset and length are unused for chain entry. Clear them. |
193 | */ |
194 | chain_sg->offset = 0; |
195 | chain_sg->length = 0; |
196 | |
197 | /* |
198 | * Set lowest bit to indicate a link pointer, and make sure to clear |
199 | * the termination bit if it happens to be set. |
200 | */ |
201 | chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END; |
202 | } |
203 | |
204 | /** |
205 | * sg_chain - Chain two sglists together |
206 | * @prv: First scatterlist |
207 | * @prv_nents: Number of entries in prv |
208 | * @sgl: Second scatterlist |
209 | * |
210 | * Description: |
211 | * Links @prv@ and @sgl@ together, to form a longer scatterlist. |
212 | * |
213 | **/ |
214 | static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, |
215 | struct scatterlist *sgl) |
216 | { |
217 | __sg_chain(&prv[prv_nents - 1], sgl); |
218 | } |
219 | |
220 | /** |
221 | * sg_mark_end - Mark the end of the scatterlist |
222 | * @sg: SG entryScatterlist |
223 | * |
224 | * Description: |
225 | * Marks the passed in sg entry as the termination point for the sg |
226 | * table. A call to sg_next() on this entry will return NULL. |
227 | * |
228 | **/ |
229 | static inline void sg_mark_end(struct scatterlist *sg) |
230 | { |
231 | /* |
232 | * Set termination bit, clear potential chain bit |
233 | */ |
234 | sg->page_link |= SG_END; |
235 | sg->page_link &= ~SG_CHAIN; |
236 | } |
237 | |
238 | /** |
239 | * sg_unmark_end - Undo setting the end of the scatterlist |
240 | * @sg: SG entryScatterlist |
241 | * |
242 | * Description: |
243 | * Removes the termination marker from the given entry of the scatterlist. |
244 | * |
245 | **/ |
246 | static inline void sg_unmark_end(struct scatterlist *sg) |
247 | { |
248 | sg->page_link &= ~SG_END; |
249 | } |
250 | |
251 | /* |
252 | * CONFGI_PCI_P2PDMA depends on CONFIG_64BIT which means there is 4 bytes |
253 | * in struct scatterlist (assuming also CONFIG_NEED_SG_DMA_LENGTH is set). |
254 | * Use this padding for DMA flags bits to indicate when a specific |
255 | * dma address is a bus address. |
256 | */ |
257 | #ifdef CONFIG_PCI_P2PDMA |
258 | |
259 | #define SG_DMA_BUS_ADDRESS (1 << 0) |
260 | |
261 | /** |
262 | * sg_dma_is_bus address - Return whether a given segment was marked |
263 | * as a bus address |
264 | * @sg: SG entry |
265 | * |
266 | * Description: |
267 | * Returns true if sg_dma_mark_bus_address() has been called on |
268 | * this segment. |
269 | **/ |
270 | static inline bool sg_is_dma_bus_address(struct scatterlist *sg) |
271 | { |
272 | return sg->dma_flags & SG_DMA_BUS_ADDRESS; |
273 | } |
274 | |
275 | /** |
276 | * sg_dma_mark_bus address - Mark the scatterlist entry as a bus address |
277 | * @sg: SG entry |
278 | * |
279 | * Description: |
280 | * Marks the passed in sg entry to indicate that the dma_address is |
281 | * a bus address and doesn't need to be unmapped. This should only be |
282 | * used by dma_map_sg() implementations to mark bus addresses |
283 | * so they can be properly cleaned up in dma_unmap_sg(). |
284 | **/ |
285 | static inline void sg_dma_mark_bus_address(struct scatterlist *sg) |
286 | { |
287 | sg->dma_flags |= SG_DMA_BUS_ADDRESS; |
288 | } |
289 | |
290 | /** |
291 | * sg_unmark_bus_address - Unmark the scatterlist entry as a bus address |
292 | * @sg: SG entry |
293 | * |
294 | * Description: |
295 | * Clears the bus address mark. |
296 | **/ |
297 | static inline void sg_dma_unmark_bus_address(struct scatterlist *sg) |
298 | { |
299 | sg->dma_flags &= ~SG_DMA_BUS_ADDRESS; |
300 | } |
301 | |
302 | #else |
303 | |
304 | static inline bool sg_is_dma_bus_address(struct scatterlist *sg) |
305 | { |
306 | return false; |
307 | } |
308 | static inline void sg_dma_mark_bus_address(struct scatterlist *sg) |
309 | { |
310 | } |
311 | static inline void sg_dma_unmark_bus_address(struct scatterlist *sg) |
312 | { |
313 | } |
314 | |
315 | #endif |
316 | |
317 | /** |
318 | * sg_phys - Return physical address of an sg entry |
319 | * @sg: SG entry |
320 | * |
321 | * Description: |
322 | * This calls page_to_phys() on the page in this sg entry, and adds the |
323 | * sg offset. The caller must know that it is legal to call page_to_phys() |
324 | * on the sg page. |
325 | * |
326 | **/ |
327 | static inline dma_addr_t sg_phys(struct scatterlist *sg) |
328 | { |
329 | return page_to_phys(sg_page(sg)) + sg->offset; |
330 | } |
331 | |
332 | /** |
333 | * sg_virt - Return virtual address of an sg entry |
334 | * @sg: SG entry |
335 | * |
336 | * Description: |
337 | * This calls page_address() on the page in this sg entry, and adds the |
338 | * sg offset. The caller must know that the sg page has a valid virtual |
339 | * mapping. |
340 | * |
341 | **/ |
342 | static inline void *sg_virt(struct scatterlist *sg) |
343 | { |
344 | return page_address(sg_page(sg)) + sg->offset; |
345 | } |
346 | |
347 | /** |
348 | * sg_init_marker - Initialize markers in sg table |
349 | * @sgl: The SG table |
350 | * @nents: Number of entries in table |
351 | * |
352 | **/ |
353 | static inline void sg_init_marker(struct scatterlist *sgl, |
354 | unsigned int nents) |
355 | { |
356 | sg_mark_end(&sgl[nents - 1]); |
357 | } |
358 | |
359 | int sg_nents(struct scatterlist *sg); |
360 | int sg_nents_for_len(struct scatterlist *sg, u64 len); |
361 | struct scatterlist *sg_next(struct scatterlist *); |
362 | struct scatterlist *sg_last(struct scatterlist *s, unsigned int); |
363 | void sg_init_table(struct scatterlist *, unsigned int); |
364 | void sg_init_one(struct scatterlist *, const void *, unsigned int); |
365 | int sg_split(struct scatterlist *in, const int in_mapped_nents, |
366 | const off_t skip, const int nb_splits, |
367 | const size_t *split_sizes, |
368 | struct scatterlist **out, int *out_mapped_nents, |
369 | gfp_t gfp_mask); |
370 | |
371 | typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); |
372 | typedef void (sg_free_fn)(struct scatterlist *, unsigned int); |
373 | |
374 | void __sg_free_table(struct sg_table *, unsigned int, unsigned int, |
375 | sg_free_fn *, unsigned int); |
376 | void sg_free_table(struct sg_table *); |
377 | void sg_free_append_table(struct sg_append_table *sgt); |
378 | int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, |
379 | struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *); |
380 | int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); |
381 | int sg_alloc_append_table_from_pages(struct sg_append_table *sgt, |
382 | struct page **pages, unsigned int n_pages, |
383 | unsigned int offset, unsigned long size, |
384 | unsigned int max_segment, |
385 | unsigned int left_pages, gfp_t gfp_mask); |
386 | int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages, |
387 | unsigned int n_pages, unsigned int offset, |
388 | unsigned long size, |
389 | unsigned int max_segment, gfp_t gfp_mask); |
390 | |
391 | /** |
392 | * sg_alloc_table_from_pages - Allocate and initialize an sg table from |
393 | * an array of pages |
394 | * @sgt: The sg table header to use |
395 | * @pages: Pointer to an array of page pointers |
396 | * @n_pages: Number of pages in the pages array |
397 | * @offset: Offset from start of the first page to the start of a buffer |
398 | * @size: Number of valid bytes in the buffer (after offset) |
399 | * @gfp_mask: GFP allocation mask |
400 | * |
401 | * Description: |
402 | * Allocate and initialize an sg table from a list of pages. Contiguous |
403 | * ranges of the pages are squashed into a single scatterlist node. A user |
404 | * may provide an offset at a start and a size of valid data in a buffer |
405 | * specified by the page array. The returned sg table is released by |
406 | * sg_free_table. |
407 | * |
408 | * Returns: |
409 | * 0 on success, negative error on failure |
410 | */ |
411 | static inline int sg_alloc_table_from_pages(struct sg_table *sgt, |
412 | struct page **pages, |
413 | unsigned int n_pages, |
414 | unsigned int offset, |
415 | unsigned long size, gfp_t gfp_mask) |
416 | { |
417 | return sg_alloc_table_from_pages_segment(sgt, pages, n_pages, offset, |
418 | size, UINT_MAX, gfp_mask); |
419 | } |
420 | |
421 | #ifdef CONFIG_SGL_ALLOC |
422 | struct scatterlist *sgl_alloc_order(unsigned long long length, |
423 | unsigned int order, bool chainable, |
424 | gfp_t gfp, unsigned int *nent_p); |
425 | struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, |
426 | unsigned int *nent_p); |
427 | void sgl_free_n_order(struct scatterlist *sgl, int nents, int order); |
428 | void sgl_free_order(struct scatterlist *sgl, int order); |
429 | void sgl_free(struct scatterlist *sgl); |
430 | #endif /* CONFIG_SGL_ALLOC */ |
431 | |
432 | size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, |
433 | size_t buflen, off_t skip, bool to_buffer); |
434 | |
435 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
436 | const void *buf, size_t buflen); |
437 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, |
438 | void *buf, size_t buflen); |
439 | |
440 | size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
441 | const void *buf, size_t buflen, off_t skip); |
442 | size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, |
443 | void *buf, size_t buflen, off_t skip); |
444 | size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, |
445 | size_t buflen, off_t skip); |
446 | |
447 | /* |
448 | * Maximum number of entries that will be allocated in one piece, if |
449 | * a list larger than this is required then chaining will be utilized. |
450 | */ |
451 | #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) |
452 | |
453 | /* |
454 | * The maximum number of SG segments that we will put inside a |
455 | * scatterlist (unless chaining is used). Should ideally fit inside a |
456 | * single page, to avoid a higher order allocation. We could define this |
457 | * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The |
458 | * minimum value is 32 |
459 | */ |
460 | #define SG_CHUNK_SIZE 128 |
461 | |
462 | /* |
463 | * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit |
464 | * is totally arbitrary, a setting of 2048 will get you at least 8mb ios. |
465 | */ |
466 | #ifdef CONFIG_ARCH_NO_SG_CHAIN |
467 | #define SG_MAX_SEGMENTS SG_CHUNK_SIZE |
468 | #else |
469 | #define SG_MAX_SEGMENTS 2048 |
470 | #endif |
471 | |
472 | #ifdef CONFIG_SG_POOL |
473 | void sg_free_table_chained(struct sg_table *table, |
474 | unsigned nents_first_chunk); |
475 | int sg_alloc_table_chained(struct sg_table *table, int nents, |
476 | struct scatterlist *first_chunk, |
477 | unsigned nents_first_chunk); |
478 | #endif |
479 | |
480 | /* |
481 | * sg page iterator |
482 | * |
483 | * Iterates over sg entries page-by-page. On each successful iteration, you |
484 | * can call sg_page_iter_page(@piter) to get the current page. |
485 | * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to |
486 | * the page's page offset within the sg. The iteration will stop either when a |
487 | * maximum number of sg entries was reached or a terminating sg |
488 | * (sg_last(sg) == true) was reached. |
489 | */ |
490 | struct sg_page_iter { |
491 | struct scatterlist *sg; /* sg holding the page */ |
492 | unsigned int sg_pgoffset; /* page offset within the sg */ |
493 | |
494 | /* these are internal states, keep away */ |
495 | unsigned int __nents; /* remaining sg entries */ |
496 | int __pg_advance; /* nr pages to advance at the |
497 | * next step */ |
498 | }; |
499 | |
500 | /* |
501 | * sg page iterator for DMA addresses |
502 | * |
503 | * This is the same as sg_page_iter however you can call |
504 | * sg_page_iter_dma_address(@dma_iter) to get the page's DMA |
505 | * address. sg_page_iter_page() cannot be called on this iterator. |
506 | */ |
507 | struct sg_dma_page_iter { |
508 | struct sg_page_iter base; |
509 | }; |
510 | |
511 | bool __sg_page_iter_next(struct sg_page_iter *piter); |
512 | bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter); |
513 | void __sg_page_iter_start(struct sg_page_iter *piter, |
514 | struct scatterlist *sglist, unsigned int nents, |
515 | unsigned long pgoffset); |
516 | /** |
517 | * sg_page_iter_page - get the current page held by the page iterator |
518 | * @piter: page iterator holding the page |
519 | */ |
520 | static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) |
521 | { |
522 | return nth_page(sg_page(piter->sg), piter->sg_pgoffset); |
523 | } |
524 | |
525 | /** |
526 | * sg_page_iter_dma_address - get the dma address of the current page held by |
527 | * the page iterator. |
528 | * @dma_iter: page iterator holding the page |
529 | */ |
530 | static inline dma_addr_t |
531 | sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter) |
532 | { |
533 | return sg_dma_address(dma_iter->base.sg) + |
534 | (dma_iter->base.sg_pgoffset << PAGE_SHIFT); |
535 | } |
536 | |
537 | /** |
538 | * for_each_sg_page - iterate over the pages of the given sg list |
539 | * @sglist: sglist to iterate over |
540 | * @piter: page iterator to hold current page, sg, sg_pgoffset |
541 | * @nents: maximum number of sg entries to iterate over |
542 | * @pgoffset: starting page offset (in pages) |
543 | * |
544 | * Callers may use sg_page_iter_page() to get each page pointer. |
545 | * In each loop it operates on PAGE_SIZE unit. |
546 | */ |
547 | #define for_each_sg_page(sglist, piter, nents, pgoffset) \ |
548 | for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \ |
549 | __sg_page_iter_next(piter);) |
550 | |
551 | /** |
552 | * for_each_sg_dma_page - iterate over the pages of the given sg list |
553 | * @sglist: sglist to iterate over |
554 | * @dma_iter: DMA page iterator to hold current page |
555 | * @dma_nents: maximum number of sg entries to iterate over, this is the value |
556 | * returned from dma_map_sg |
557 | * @pgoffset: starting page offset (in pages) |
558 | * |
559 | * Callers may use sg_page_iter_dma_address() to get each page's DMA address. |
560 | * In each loop it operates on PAGE_SIZE unit. |
561 | */ |
562 | #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \ |
563 | for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \ |
564 | pgoffset); \ |
565 | __sg_page_iter_dma_next(dma_iter);) |
566 | |
567 | /** |
568 | * for_each_sgtable_page - iterate over all pages in the sg_table object |
569 | * @sgt: sg_table object to iterate over |
570 | * @piter: page iterator to hold current page |
571 | * @pgoffset: starting page offset (in pages) |
572 | * |
573 | * Iterates over the all memory pages in the buffer described by |
574 | * a scatterlist stored in the given sg_table object. |
575 | * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit. |
576 | */ |
577 | #define for_each_sgtable_page(sgt, piter, pgoffset) \ |
578 | for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset) |
579 | |
580 | /** |
581 | * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object |
582 | * @sgt: sg_table object to iterate over |
583 | * @dma_iter: DMA page iterator to hold current page |
584 | * @pgoffset: starting page offset (in pages) |
585 | * |
586 | * Iterates over the all DMA mapped pages in the buffer described by |
587 | * a scatterlist stored in the given sg_table object. |
588 | * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE |
589 | * unit. |
590 | */ |
591 | #define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \ |
592 | for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset) |
593 | |
594 | |
595 | /* |
596 | * Mapping sg iterator |
597 | * |
598 | * Iterates over sg entries mapping page-by-page. On each successful |
599 | * iteration, @miter->page points to the mapped page and |
600 | * @miter->length bytes of data can be accessed at @miter->addr. As |
601 | * long as an iteration is enclosed between start and stop, the user |
602 | * is free to choose control structure and when to stop. |
603 | * |
604 | * @miter->consumed is set to @miter->length on each iteration. It |
605 | * can be adjusted if the user can't consume all the bytes in one go. |
606 | * Also, a stopped iteration can be resumed by calling next on it. |
607 | * This is useful when iteration needs to release all resources and |
608 | * continue later (e.g. at the next interrupt). |
609 | */ |
610 | |
611 | #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ |
612 | #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */ |
613 | #define SG_MITER_FROM_SG (1 << 2) /* nop */ |
614 | |
615 | struct sg_mapping_iter { |
616 | /* the following three fields can be accessed directly */ |
617 | struct page *page; /* currently mapped page */ |
618 | void *addr; /* pointer to the mapped area */ |
619 | size_t length; /* length of the mapped area */ |
620 | size_t consumed; /* number of consumed bytes */ |
621 | struct sg_page_iter piter; /* page iterator */ |
622 | |
623 | /* these are internal states, keep away */ |
624 | unsigned int __offset; /* offset within page */ |
625 | unsigned int __remaining; /* remaining bytes on page */ |
626 | unsigned int __flags; |
627 | }; |
628 | |
629 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, |
630 | unsigned int nents, unsigned int flags); |
631 | bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset); |
632 | bool sg_miter_next(struct sg_mapping_iter *miter); |
633 | void sg_miter_stop(struct sg_mapping_iter *miter); |
634 | |
635 | #endif /* _LINUX_SCATTERLIST_H */ |
636 | |