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_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 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 : 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 0 : 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 0 : 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 0 : chain_sg->offset = 0;
195 0 : 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 0 : 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 0 : __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 0 : sg->page_link |= SG_END;
235 0 : 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 0 : 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 0 : 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 0 : 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 0 : 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 0 : return sg_dma_address(dma_iter->base.sg) +
534 0 : (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 */
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