Line data Source code
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_NEED_SG_DMA_FLAGS
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 0 : return sg->page_link & SG_PAGE_LINK_MASK;
80 : }
81 :
82 : static inline struct scatterlist *sg_chain_ptr(struct scatterlist *sg)
83 : {
84 0 : return (struct scatterlist *)(sg->page_link & ~SG_PAGE_LINK_MASK);
85 : }
86 :
87 : static inline bool sg_is_chain(struct scatterlist *sg)
88 : {
89 0 : return __sg_flags(sg) & SG_CHAIN;
90 : }
91 :
92 : static inline bool sg_is_last(struct scatterlist *sg)
93 : {
94 0 : 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 0 : static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
108 : {
109 0 : 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 0 : BUG_ON((unsigned long)page & SG_PAGE_LINK_MASK);
116 : #ifdef CONFIG_DEBUG_SG
117 : BUG_ON(sg_is_chain(sg));
118 : #endif
119 0 : sg->page_link = page_link | (unsigned long) page;
120 0 : }
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 0 : sg_assign_page(sg, page);
140 0 : sg->offset = offset;
141 0 : sg->length = len;
142 : }
143 :
144 : /**
145 : * sg_set_folio - Set sg entry to point at given folio
146 : * @sg: SG entry
147 : * @folio: The folio
148 : * @len: Length of data
149 : * @offset: Offset into folio
150 : *
151 : * Description:
152 : * Use this function to set an sg entry pointing at a folio, never assign
153 : * the folio directly. We encode sg table information in the lower bits
154 : * of the folio pointer. See sg_page() for looking up the page belonging
155 : * to an sg entry.
156 : *
157 : **/
158 : static inline void sg_set_folio(struct scatterlist *sg, struct folio *folio,
159 : size_t len, size_t offset)
160 : {
161 : WARN_ON_ONCE(len > UINT_MAX);
162 : WARN_ON_ONCE(offset > UINT_MAX);
163 : sg_assign_page(sg, &folio->page);
164 : sg->offset = offset;
165 : sg->length = len;
166 : }
167 :
168 : static inline struct page *sg_page(struct scatterlist *sg)
169 : {
170 : #ifdef CONFIG_DEBUG_SG
171 : BUG_ON(sg_is_chain(sg));
172 : #endif
173 0 : return (struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK);
174 : }
175 :
176 : /**
177 : * sg_set_buf - Set sg entry to point at given data
178 : * @sg: SG entry
179 : * @buf: Data
180 : * @buflen: Data length
181 : *
182 : **/
183 : static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
184 : unsigned int buflen)
185 : {
186 : #ifdef CONFIG_DEBUG_SG
187 : BUG_ON(!virt_addr_valid(buf));
188 : #endif
189 0 : sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
190 : }
191 :
192 : /*
193 : * Loop over each sg element, following the pointer to a new list if necessary
194 : */
195 : #define for_each_sg(sglist, sg, nr, __i) \
196 : for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
197 :
198 : /*
199 : * Loop over each sg element in the given sg_table object.
200 : */
201 : #define for_each_sgtable_sg(sgt, sg, i) \
202 : for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i)
203 :
204 : /*
205 : * Loop over each sg element in the given *DMA mapped* sg_table object.
206 : * Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses
207 : * of the each element.
208 : */
209 : #define for_each_sgtable_dma_sg(sgt, sg, i) \
210 : for_each_sg((sgt)->sgl, sg, (sgt)->nents, i)
211 :
212 : static inline void __sg_chain(struct scatterlist *chain_sg,
213 : struct scatterlist *sgl)
214 : {
215 : /*
216 : * offset and length are unused for chain entry. Clear them.
217 : */
218 0 : chain_sg->offset = 0;
219 0 : chain_sg->length = 0;
220 :
221 : /*
222 : * Set lowest bit to indicate a link pointer, and make sure to clear
223 : * the termination bit if it happens to be set.
224 : */
225 0 : chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END;
226 : }
227 :
228 : /**
229 : * sg_chain - Chain two sglists together
230 : * @prv: First scatterlist
231 : * @prv_nents: Number of entries in prv
232 : * @sgl: Second scatterlist
233 : *
234 : * Description:
235 : * Links @prv@ and @sgl@ together, to form a longer scatterlist.
236 : *
237 : **/
238 : static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
239 : struct scatterlist *sgl)
240 : {
241 0 : __sg_chain(&prv[prv_nents - 1], sgl);
242 : }
243 :
244 : /**
245 : * sg_mark_end - Mark the end of the scatterlist
246 : * @sg: SG entryScatterlist
247 : *
248 : * Description:
249 : * Marks the passed in sg entry as the termination point for the sg
250 : * table. A call to sg_next() on this entry will return NULL.
251 : *
252 : **/
253 : static inline void sg_mark_end(struct scatterlist *sg)
254 : {
255 : /*
256 : * Set termination bit, clear potential chain bit
257 : */
258 0 : sg->page_link |= SG_END;
259 0 : sg->page_link &= ~SG_CHAIN;
260 : }
261 :
262 : /**
263 : * sg_unmark_end - Undo setting the end of the scatterlist
264 : * @sg: SG entryScatterlist
265 : *
266 : * Description:
267 : * Removes the termination marker from the given entry of the scatterlist.
268 : *
269 : **/
270 : static inline void sg_unmark_end(struct scatterlist *sg)
271 : {
272 0 : sg->page_link &= ~SG_END;
273 : }
274 :
275 : /*
276 : * One 64-bit architectures there is a 4-byte padding in struct scatterlist
277 : * (assuming also CONFIG_NEED_SG_DMA_LENGTH is set). Use this padding for DMA
278 : * flags bits to indicate when a specific dma address is a bus address or the
279 : * buffer may have been bounced via SWIOTLB.
280 : */
281 : #ifdef CONFIG_NEED_SG_DMA_FLAGS
282 :
283 : #define SG_DMA_BUS_ADDRESS (1 << 0)
284 : #define SG_DMA_SWIOTLB (1 << 1)
285 :
286 : /**
287 : * sg_dma_is_bus_address - Return whether a given segment was marked
288 : * as a bus address
289 : * @sg: SG entry
290 : *
291 : * Description:
292 : * Returns true if sg_dma_mark_bus_address() has been called on
293 : * this segment.
294 : **/
295 : static inline bool sg_dma_is_bus_address(struct scatterlist *sg)
296 : {
297 : return sg->dma_flags & SG_DMA_BUS_ADDRESS;
298 : }
299 :
300 : /**
301 : * sg_dma_mark_bus_address - Mark the scatterlist entry as a bus address
302 : * @sg: SG entry
303 : *
304 : * Description:
305 : * Marks the passed in sg entry to indicate that the dma_address is
306 : * a bus address and doesn't need to be unmapped. This should only be
307 : * used by dma_map_sg() implementations to mark bus addresses
308 : * so they can be properly cleaned up in dma_unmap_sg().
309 : **/
310 : static inline void sg_dma_mark_bus_address(struct scatterlist *sg)
311 : {
312 : sg->dma_flags |= SG_DMA_BUS_ADDRESS;
313 : }
314 :
315 : /**
316 : * sg_unmark_bus_address - Unmark the scatterlist entry as a bus address
317 : * @sg: SG entry
318 : *
319 : * Description:
320 : * Clears the bus address mark.
321 : **/
322 : static inline void sg_dma_unmark_bus_address(struct scatterlist *sg)
323 : {
324 : sg->dma_flags &= ~SG_DMA_BUS_ADDRESS;
325 : }
326 :
327 : /**
328 : * sg_dma_is_swiotlb - Return whether the scatterlist was marked for SWIOTLB
329 : * bouncing
330 : * @sg: SG entry
331 : *
332 : * Description:
333 : * Returns true if the scatterlist was marked for SWIOTLB bouncing. Not all
334 : * elements may have been bounced, so the caller would have to check
335 : * individual SG entries with is_swiotlb_buffer().
336 : */
337 : static inline bool sg_dma_is_swiotlb(struct scatterlist *sg)
338 : {
339 : return sg->dma_flags & SG_DMA_SWIOTLB;
340 : }
341 :
342 : /**
343 : * sg_dma_mark_swiotlb - Mark the scatterlist for SWIOTLB bouncing
344 : * @sg: SG entry
345 : *
346 : * Description:
347 : * Marks a a scatterlist for SWIOTLB bounce. Not all SG entries may be
348 : * bounced.
349 : */
350 : static inline void sg_dma_mark_swiotlb(struct scatterlist *sg)
351 : {
352 : sg->dma_flags |= SG_DMA_SWIOTLB;
353 : }
354 :
355 : #else
356 :
357 : static inline bool sg_dma_is_bus_address(struct scatterlist *sg)
358 : {
359 : return false;
360 : }
361 : static inline void sg_dma_mark_bus_address(struct scatterlist *sg)
362 : {
363 : }
364 : static inline void sg_dma_unmark_bus_address(struct scatterlist *sg)
365 : {
366 : }
367 : static inline bool sg_dma_is_swiotlb(struct scatterlist *sg)
368 : {
369 : return false;
370 : }
371 : static inline void sg_dma_mark_swiotlb(struct scatterlist *sg)
372 : {
373 : }
374 :
375 : #endif /* CONFIG_NEED_SG_DMA_FLAGS */
376 :
377 : /**
378 : * sg_phys - Return physical address of an sg entry
379 : * @sg: SG entry
380 : *
381 : * Description:
382 : * This calls page_to_phys() on the page in this sg entry, and adds the
383 : * sg offset. The caller must know that it is legal to call page_to_phys()
384 : * on the sg page.
385 : *
386 : **/
387 : static inline dma_addr_t sg_phys(struct scatterlist *sg)
388 : {
389 0 : return page_to_phys(sg_page(sg)) + sg->offset;
390 : }
391 :
392 : /**
393 : * sg_virt - Return virtual address of an sg entry
394 : * @sg: SG entry
395 : *
396 : * Description:
397 : * This calls page_address() on the page in this sg entry, and adds the
398 : * sg offset. The caller must know that the sg page has a valid virtual
399 : * mapping.
400 : *
401 : **/
402 : static inline void *sg_virt(struct scatterlist *sg)
403 : {
404 : return page_address(sg_page(sg)) + sg->offset;
405 : }
406 :
407 : /**
408 : * sg_init_marker - Initialize markers in sg table
409 : * @sgl: The SG table
410 : * @nents: Number of entries in table
411 : *
412 : **/
413 : static inline void sg_init_marker(struct scatterlist *sgl,
414 : unsigned int nents)
415 : {
416 0 : sg_mark_end(&sgl[nents - 1]);
417 : }
418 :
419 : int sg_nents(struct scatterlist *sg);
420 : int sg_nents_for_len(struct scatterlist *sg, u64 len);
421 : struct scatterlist *sg_next(struct scatterlist *);
422 : struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
423 : void sg_init_table(struct scatterlist *, unsigned int);
424 : void sg_init_one(struct scatterlist *, const void *, unsigned int);
425 : int sg_split(struct scatterlist *in, const int in_mapped_nents,
426 : const off_t skip, const int nb_splits,
427 : const size_t *split_sizes,
428 : struct scatterlist **out, int *out_mapped_nents,
429 : gfp_t gfp_mask);
430 :
431 : typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
432 : typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
433 :
434 : void __sg_free_table(struct sg_table *, unsigned int, unsigned int,
435 : sg_free_fn *, unsigned int);
436 : void sg_free_table(struct sg_table *);
437 : void sg_free_append_table(struct sg_append_table *sgt);
438 : int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
439 : struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *);
440 : int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
441 : int sg_alloc_append_table_from_pages(struct sg_append_table *sgt,
442 : struct page **pages, unsigned int n_pages,
443 : unsigned int offset, unsigned long size,
444 : unsigned int max_segment,
445 : unsigned int left_pages, gfp_t gfp_mask);
446 : int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages,
447 : unsigned int n_pages, unsigned int offset,
448 : unsigned long size,
449 : unsigned int max_segment, gfp_t gfp_mask);
450 :
451 : /**
452 : * sg_alloc_table_from_pages - Allocate and initialize an sg table from
453 : * an array of pages
454 : * @sgt: The sg table header to use
455 : * @pages: Pointer to an array of page pointers
456 : * @n_pages: Number of pages in the pages array
457 : * @offset: Offset from start of the first page to the start of a buffer
458 : * @size: Number of valid bytes in the buffer (after offset)
459 : * @gfp_mask: GFP allocation mask
460 : *
461 : * Description:
462 : * Allocate and initialize an sg table from a list of pages. Contiguous
463 : * ranges of the pages are squashed into a single scatterlist node. A user
464 : * may provide an offset at a start and a size of valid data in a buffer
465 : * specified by the page array. The returned sg table is released by
466 : * sg_free_table.
467 : *
468 : * Returns:
469 : * 0 on success, negative error on failure
470 : */
471 : static inline int sg_alloc_table_from_pages(struct sg_table *sgt,
472 : struct page **pages,
473 : unsigned int n_pages,
474 : unsigned int offset,
475 : unsigned long size, gfp_t gfp_mask)
476 : {
477 : return sg_alloc_table_from_pages_segment(sgt, pages, n_pages, offset,
478 : size, UINT_MAX, gfp_mask);
479 : }
480 :
481 : #ifdef CONFIG_SGL_ALLOC
482 : struct scatterlist *sgl_alloc_order(unsigned long long length,
483 : unsigned int order, bool chainable,
484 : gfp_t gfp, unsigned int *nent_p);
485 : struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
486 : unsigned int *nent_p);
487 : void sgl_free_n_order(struct scatterlist *sgl, int nents, int order);
488 : void sgl_free_order(struct scatterlist *sgl, int order);
489 : void sgl_free(struct scatterlist *sgl);
490 : #endif /* CONFIG_SGL_ALLOC */
491 :
492 : size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
493 : size_t buflen, off_t skip, bool to_buffer);
494 :
495 : size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
496 : const void *buf, size_t buflen);
497 : size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
498 : void *buf, size_t buflen);
499 :
500 : size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
501 : const void *buf, size_t buflen, off_t skip);
502 : size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
503 : void *buf, size_t buflen, off_t skip);
504 : size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
505 : size_t buflen, off_t skip);
506 :
507 : /*
508 : * Maximum number of entries that will be allocated in one piece, if
509 : * a list larger than this is required then chaining will be utilized.
510 : */
511 : #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
512 :
513 : /*
514 : * The maximum number of SG segments that we will put inside a
515 : * scatterlist (unless chaining is used). Should ideally fit inside a
516 : * single page, to avoid a higher order allocation. We could define this
517 : * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
518 : * minimum value is 32
519 : */
520 : #define SG_CHUNK_SIZE 128
521 :
522 : /*
523 : * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
524 : * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
525 : */
526 : #ifdef CONFIG_ARCH_NO_SG_CHAIN
527 : #define SG_MAX_SEGMENTS SG_CHUNK_SIZE
528 : #else
529 : #define SG_MAX_SEGMENTS 2048
530 : #endif
531 :
532 : #ifdef CONFIG_SG_POOL
533 : void sg_free_table_chained(struct sg_table *table,
534 : unsigned nents_first_chunk);
535 : int sg_alloc_table_chained(struct sg_table *table, int nents,
536 : struct scatterlist *first_chunk,
537 : unsigned nents_first_chunk);
538 : #endif
539 :
540 : /*
541 : * sg page iterator
542 : *
543 : * Iterates over sg entries page-by-page. On each successful iteration, you
544 : * can call sg_page_iter_page(@piter) to get the current page.
545 : * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to
546 : * the page's page offset within the sg. The iteration will stop either when a
547 : * maximum number of sg entries was reached or a terminating sg
548 : * (sg_last(sg) == true) was reached.
549 : */
550 : struct sg_page_iter {
551 : struct scatterlist *sg; /* sg holding the page */
552 : unsigned int sg_pgoffset; /* page offset within the sg */
553 :
554 : /* these are internal states, keep away */
555 : unsigned int __nents; /* remaining sg entries */
556 : int __pg_advance; /* nr pages to advance at the
557 : * next step */
558 : };
559 :
560 : /*
561 : * sg page iterator for DMA addresses
562 : *
563 : * This is the same as sg_page_iter however you can call
564 : * sg_page_iter_dma_address(@dma_iter) to get the page's DMA
565 : * address. sg_page_iter_page() cannot be called on this iterator.
566 : */
567 : struct sg_dma_page_iter {
568 : struct sg_page_iter base;
569 : };
570 :
571 : bool __sg_page_iter_next(struct sg_page_iter *piter);
572 : bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter);
573 : void __sg_page_iter_start(struct sg_page_iter *piter,
574 : struct scatterlist *sglist, unsigned int nents,
575 : unsigned long pgoffset);
576 : /**
577 : * sg_page_iter_page - get the current page held by the page iterator
578 : * @piter: page iterator holding the page
579 : */
580 : static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
581 : {
582 0 : return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
583 : }
584 :
585 : /**
586 : * sg_page_iter_dma_address - get the dma address of the current page held by
587 : * the page iterator.
588 : * @dma_iter: page iterator holding the page
589 : */
590 : static inline dma_addr_t
591 : sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
592 : {
593 0 : return sg_dma_address(dma_iter->base.sg) +
594 0 : (dma_iter->base.sg_pgoffset << PAGE_SHIFT);
595 : }
596 :
597 : /**
598 : * for_each_sg_page - iterate over the pages of the given sg list
599 : * @sglist: sglist to iterate over
600 : * @piter: page iterator to hold current page, sg, sg_pgoffset
601 : * @nents: maximum number of sg entries to iterate over
602 : * @pgoffset: starting page offset (in pages)
603 : *
604 : * Callers may use sg_page_iter_page() to get each page pointer.
605 : * In each loop it operates on PAGE_SIZE unit.
606 : */
607 : #define for_each_sg_page(sglist, piter, nents, pgoffset) \
608 : for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
609 : __sg_page_iter_next(piter);)
610 :
611 : /**
612 : * for_each_sg_dma_page - iterate over the pages of the given sg list
613 : * @sglist: sglist to iterate over
614 : * @dma_iter: DMA page iterator to hold current page
615 : * @dma_nents: maximum number of sg entries to iterate over, this is the value
616 : * returned from dma_map_sg
617 : * @pgoffset: starting page offset (in pages)
618 : *
619 : * Callers may use sg_page_iter_dma_address() to get each page's DMA address.
620 : * In each loop it operates on PAGE_SIZE unit.
621 : */
622 : #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \
623 : for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \
624 : pgoffset); \
625 : __sg_page_iter_dma_next(dma_iter);)
626 :
627 : /**
628 : * for_each_sgtable_page - iterate over all pages in the sg_table object
629 : * @sgt: sg_table object to iterate over
630 : * @piter: page iterator to hold current page
631 : * @pgoffset: starting page offset (in pages)
632 : *
633 : * Iterates over the all memory pages in the buffer described by
634 : * a scatterlist stored in the given sg_table object.
635 : * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit.
636 : */
637 : #define for_each_sgtable_page(sgt, piter, pgoffset) \
638 : for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset)
639 :
640 : /**
641 : * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object
642 : * @sgt: sg_table object to iterate over
643 : * @dma_iter: DMA page iterator to hold current page
644 : * @pgoffset: starting page offset (in pages)
645 : *
646 : * Iterates over the all DMA mapped pages in the buffer described by
647 : * a scatterlist stored in the given sg_table object.
648 : * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE
649 : * unit.
650 : */
651 : #define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \
652 : for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset)
653 :
654 :
655 : /*
656 : * Mapping sg iterator
657 : *
658 : * Iterates over sg entries mapping page-by-page. On each successful
659 : * iteration, @miter->page points to the mapped page and
660 : * @miter->length bytes of data can be accessed at @miter->addr. As
661 : * long as an iteration is enclosed between start and stop, the user
662 : * is free to choose control structure and when to stop.
663 : *
664 : * @miter->consumed is set to @miter->length on each iteration. It
665 : * can be adjusted if the user can't consume all the bytes in one go.
666 : * Also, a stopped iteration can be resumed by calling next on it.
667 : * This is useful when iteration needs to release all resources and
668 : * continue later (e.g. at the next interrupt).
669 : */
670 :
671 : #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
672 : #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
673 : #define SG_MITER_FROM_SG (1 << 2) /* nop */
674 :
675 : struct sg_mapping_iter {
676 : /* the following three fields can be accessed directly */
677 : struct page *page; /* currently mapped page */
678 : void *addr; /* pointer to the mapped area */
679 : size_t length; /* length of the mapped area */
680 : size_t consumed; /* number of consumed bytes */
681 : struct sg_page_iter piter; /* page iterator */
682 :
683 : /* these are internal states, keep away */
684 : unsigned int __offset; /* offset within page */
685 : unsigned int __remaining; /* remaining bytes on page */
686 : unsigned int __flags;
687 : };
688 :
689 : void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
690 : unsigned int nents, unsigned int flags);
691 : bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
692 : bool sg_miter_next(struct sg_mapping_iter *miter);
693 : void sg_miter_stop(struct sg_mapping_iter *miter);
694 :
695 : #endif /* _LINUX_SCATTERLIST_H */
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