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
__sg_flags(struct scatterlist * sg)77 static inline unsigned int __sg_flags(struct scatterlist *sg)
78 {
79 return sg->page_link & SG_PAGE_LINK_MASK;
80 }
81
sg_chain_ptr(struct scatterlist * sg)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
sg_is_chain(struct scatterlist * sg)87 static inline bool sg_is_chain(struct scatterlist *sg)
88 {
89 return __sg_flags(sg) & SG_CHAIN;
90 }
91
sg_is_last(struct scatterlist * sg)92 static inline bool sg_is_last(struct scatterlist *sg)
93 {
94 return __sg_flags(sg) & SG_END;
95 }
96
97 /**
98 * sg_next - return the next scatterlist entry in a list
99 * @sg: The current sg entry
100 *
101 * Description:
102 * Usually the next entry will be @sg + 1, but if this sg element is part
103 * of a chained scatterlist, it could jump to the start of a new
104 * scatterlist array.
105 *
106 **/
sg_next(struct scatterlist * sg)107 static inline struct scatterlist *sg_next(struct scatterlist *sg)
108 {
109 if (sg_is_last(sg))
110 return NULL;
111
112 sg++;
113 if (unlikely(sg_is_chain(sg)))
114 sg = sg_chain_ptr(sg);
115
116 return sg;
117 }
118
119 /**
120 * sg_assign_page - Assign a given page to an SG entry
121 * @sg: SG entry
122 * @page: The page
123 *
124 * Description:
125 * Assign page to sg entry. Also see sg_set_page(), the most commonly used
126 * variant.
127 *
128 **/
sg_assign_page(struct scatterlist * sg,struct page * page)129 static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
130 {
131 unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END);
132
133 /*
134 * In order for the low bit stealing approach to work, pages
135 * must be aligned at a 32-bit boundary as a minimum.
136 */
137 BUG_ON((unsigned long)page & SG_PAGE_LINK_MASK);
138 #ifdef CONFIG_DEBUG_SG
139 BUG_ON(sg_is_chain(sg));
140 #endif
141 sg->page_link = page_link | (unsigned long) page;
142 }
143
144 /**
145 * sg_set_page - Set sg entry to point at given page
146 * @sg: SG entry
147 * @page: The page
148 * @len: Length of data
149 * @offset: Offset into page
150 *
151 * Description:
152 * Use this function to set an sg entry pointing at a page, never assign
153 * the page directly. We encode sg table information in the lower bits
154 * of the page pointer. See sg_page() for looking up the page belonging
155 * to an sg entry.
156 *
157 **/
sg_set_page(struct scatterlist * sg,struct page * page,unsigned int len,unsigned int offset)158 static inline void sg_set_page(struct scatterlist *sg, struct page *page,
159 unsigned int len, unsigned int offset)
160 {
161 sg_assign_page(sg, page);
162 sg->offset = offset;
163 sg->length = len;
164 }
165
166 /**
167 * sg_set_folio - Set sg entry to point at given folio
168 * @sg: SG entry
169 * @folio: The folio
170 * @len: Length of data
171 * @offset: Offset into folio
172 *
173 * Description:
174 * Use this function to set an sg entry pointing at a folio, never assign
175 * the folio directly. We encode sg table information in the lower bits
176 * of the folio pointer. See sg_page() for looking up the page belonging
177 * to an sg entry.
178 *
179 **/
sg_set_folio(struct scatterlist * sg,struct folio * folio,size_t len,size_t offset)180 static inline void sg_set_folio(struct scatterlist *sg, struct folio *folio,
181 size_t len, size_t offset)
182 {
183 WARN_ON_ONCE(len > UINT_MAX);
184 WARN_ON_ONCE(offset > UINT_MAX);
185 sg_assign_page(sg, &folio->page);
186 sg->offset = offset;
187 sg->length = len;
188 }
189
sg_page(struct scatterlist * sg)190 static inline struct page *sg_page(struct scatterlist *sg)
191 {
192 #ifdef CONFIG_DEBUG_SG
193 BUG_ON(sg_is_chain(sg));
194 #endif
195 return (struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK);
196 }
197
198 /**
199 * sg_set_buf - Set sg entry to point at given data
200 * @sg: SG entry
201 * @buf: Data
202 * @buflen: Data length
203 *
204 **/
sg_set_buf(struct scatterlist * sg,const void * buf,unsigned int buflen)205 static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
206 unsigned int buflen)
207 {
208 #ifdef CONFIG_DEBUG_SG
209 BUG_ON(!virt_addr_valid(buf));
210 #endif
211 sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
212 }
213
214 /*
215 * Loop over each sg element, following the pointer to a new list if necessary
216 */
217 #define for_each_sg(sglist, sg, nr, __i) \
218 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
219
220 /*
221 * Loop over each sg element in the given sg_table object.
222 */
223 #define for_each_sgtable_sg(sgt, sg, i) \
224 for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i)
225
226 /*
227 * Loop over each sg element in the given *DMA mapped* sg_table object.
228 * Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses
229 * of the each element.
230 */
231 #define for_each_sgtable_dma_sg(sgt, sg, i) \
232 for_each_sg((sgt)->sgl, sg, (sgt)->nents, i)
233
__sg_chain(struct scatterlist * chain_sg,struct scatterlist * sgl)234 static inline void __sg_chain(struct scatterlist *chain_sg,
235 struct scatterlist *sgl)
236 {
237 /*
238 * offset and length are unused for chain entry. Clear them.
239 */
240 chain_sg->offset = 0;
241 chain_sg->length = 0;
242
243 /*
244 * Set lowest bit to indicate a link pointer, and make sure to clear
245 * the termination bit if it happens to be set.
246 */
247 chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END;
248 }
249
250 /**
251 * sg_chain - Chain two sglists together
252 * @prv: First scatterlist
253 * @prv_nents: Number of entries in prv
254 * @sgl: Second scatterlist
255 *
256 * Description:
257 * Links @prv and @sgl together, to form a longer scatterlist.
258 *
259 **/
sg_chain(struct scatterlist * prv,unsigned int prv_nents,struct scatterlist * sgl)260 static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
261 struct scatterlist *sgl)
262 {
263 __sg_chain(&prv[prv_nents - 1], sgl);
264 }
265
266 /**
267 * sg_mark_end - Mark the end of the scatterlist
268 * @sg: SG entryScatterlist
269 *
270 * Description:
271 * Marks the passed in sg entry as the termination point for the sg
272 * table. A call to sg_next() on this entry will return NULL.
273 *
274 **/
sg_mark_end(struct scatterlist * sg)275 static inline void sg_mark_end(struct scatterlist *sg)
276 {
277 /*
278 * Set termination bit, clear potential chain bit
279 */
280 sg->page_link |= SG_END;
281 sg->page_link &= ~SG_CHAIN;
282 }
283
284 /**
285 * sg_unmark_end - Undo setting the end of the scatterlist
286 * @sg: SG entryScatterlist
287 *
288 * Description:
289 * Removes the termination marker from the given entry of the scatterlist.
290 *
291 **/
sg_unmark_end(struct scatterlist * sg)292 static inline void sg_unmark_end(struct scatterlist *sg)
293 {
294 sg->page_link &= ~SG_END;
295 }
296
297 /*
298 * On 64-bit architectures there is a 4-byte padding in struct scatterlist
299 * (assuming also CONFIG_NEED_SG_DMA_LENGTH is set). Use this padding for DMA
300 * flags bits to indicate when a specific dma address is a bus address or the
301 * buffer may have been bounced via SWIOTLB.
302 */
303 #ifdef CONFIG_NEED_SG_DMA_FLAGS
304
305 #define SG_DMA_BUS_ADDRESS (1 << 0)
306 #define SG_DMA_SWIOTLB (1 << 1)
307
308 /**
309 * sg_dma_is_bus_address - Return whether a given segment was marked
310 * as a bus address
311 * @sg: SG entry
312 *
313 * Description:
314 * Returns true if sg_dma_mark_bus_address() has been called on
315 * this segment.
316 **/
sg_dma_is_bus_address(struct scatterlist * sg)317 static inline bool sg_dma_is_bus_address(struct scatterlist *sg)
318 {
319 return sg->dma_flags & SG_DMA_BUS_ADDRESS;
320 }
321
322 /**
323 * sg_dma_mark_bus_address - Mark the scatterlist entry as a bus address
324 * @sg: SG entry
325 *
326 * Description:
327 * Marks the passed in sg entry to indicate that the dma_address is
328 * a bus address and doesn't need to be unmapped. This should only be
329 * used by dma_map_sg() implementations to mark bus addresses
330 * so they can be properly cleaned up in dma_unmap_sg().
331 **/
sg_dma_mark_bus_address(struct scatterlist * sg)332 static inline void sg_dma_mark_bus_address(struct scatterlist *sg)
333 {
334 sg->dma_flags |= SG_DMA_BUS_ADDRESS;
335 }
336
337 /**
338 * sg_dma_unmark_bus_address - Unmark the scatterlist entry as a bus address
339 * @sg: SG entry
340 *
341 * Description:
342 * Clears the bus address mark.
343 **/
sg_dma_unmark_bus_address(struct scatterlist * sg)344 static inline void sg_dma_unmark_bus_address(struct scatterlist *sg)
345 {
346 sg->dma_flags &= ~SG_DMA_BUS_ADDRESS;
347 }
348
349 /**
350 * sg_dma_is_swiotlb - Return whether the scatterlist was marked for SWIOTLB
351 * bouncing
352 * @sg: SG entry
353 *
354 * Description:
355 * Returns true if the scatterlist was marked for SWIOTLB bouncing. Not all
356 * elements may have been bounced, so the caller would have to check
357 * individual SG entries with swiotlb_find_pool().
358 */
sg_dma_is_swiotlb(struct scatterlist * sg)359 static inline bool sg_dma_is_swiotlb(struct scatterlist *sg)
360 {
361 return sg->dma_flags & SG_DMA_SWIOTLB;
362 }
363
364 /**
365 * sg_dma_mark_swiotlb - Mark the scatterlist for SWIOTLB bouncing
366 * @sg: SG entry
367 *
368 * Description:
369 * Marks a a scatterlist for SWIOTLB bounce. Not all SG entries may be
370 * bounced.
371 */
sg_dma_mark_swiotlb(struct scatterlist * sg)372 static inline void sg_dma_mark_swiotlb(struct scatterlist *sg)
373 {
374 sg->dma_flags |= SG_DMA_SWIOTLB;
375 }
376
377 #else
378
sg_dma_is_bus_address(struct scatterlist * sg)379 static inline bool sg_dma_is_bus_address(struct scatterlist *sg)
380 {
381 return false;
382 }
sg_dma_mark_bus_address(struct scatterlist * sg)383 static inline void sg_dma_mark_bus_address(struct scatterlist *sg)
384 {
385 }
sg_dma_unmark_bus_address(struct scatterlist * sg)386 static inline void sg_dma_unmark_bus_address(struct scatterlist *sg)
387 {
388 }
sg_dma_is_swiotlb(struct scatterlist * sg)389 static inline bool sg_dma_is_swiotlb(struct scatterlist *sg)
390 {
391 return false;
392 }
sg_dma_mark_swiotlb(struct scatterlist * sg)393 static inline void sg_dma_mark_swiotlb(struct scatterlist *sg)
394 {
395 }
396
397 #endif /* CONFIG_NEED_SG_DMA_FLAGS */
398
399 /**
400 * sg_phys - Return physical address of an sg entry
401 * @sg: SG entry
402 *
403 * Description:
404 * This calls page_to_phys() on the page in this sg entry, and adds the
405 * sg offset. The caller must know that it is legal to call page_to_phys()
406 * on the sg page.
407 *
408 **/
sg_phys(struct scatterlist * sg)409 static inline dma_addr_t sg_phys(struct scatterlist *sg)
410 {
411 return page_to_phys(sg_page(sg)) + sg->offset;
412 }
413
414 /**
415 * sg_virt - Return virtual address of an sg entry
416 * @sg: SG entry
417 *
418 * Description:
419 * This calls page_address() on the page in this sg entry, and adds the
420 * sg offset. The caller must know that the sg page has a valid virtual
421 * mapping.
422 *
423 **/
sg_virt(struct scatterlist * sg)424 static inline void *sg_virt(struct scatterlist *sg)
425 {
426 return page_address(sg_page(sg)) + sg->offset;
427 }
428
429 /**
430 * sg_init_marker - Initialize markers in sg table
431 * @sgl: The SG table
432 * @nents: Number of entries in table
433 *
434 **/
sg_init_marker(struct scatterlist * sgl,unsigned int nents)435 static inline void sg_init_marker(struct scatterlist *sgl,
436 unsigned int nents)
437 {
438 sg_mark_end(&sgl[nents - 1]);
439 }
440
441 int sg_nents(struct scatterlist *sg);
442 int sg_nents_for_len(struct scatterlist *sg, u64 len);
443 struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
444 void sg_init_table(struct scatterlist *, unsigned int);
445 void sg_init_one(struct scatterlist *, const void *, unsigned int);
446 int sg_split(struct scatterlist *in, const int in_mapped_nents,
447 const off_t skip, const int nb_splits,
448 const size_t *split_sizes,
449 struct scatterlist **out, int *out_mapped_nents,
450 gfp_t gfp_mask);
451
452 typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
453 typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
454
455 void __sg_free_table(struct sg_table *, unsigned int, unsigned int,
456 sg_free_fn *, unsigned int);
457 void sg_free_table(struct sg_table *);
458 void sg_free_append_table(struct sg_append_table *sgt);
459 int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
460 struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *);
461 int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
462 int sg_alloc_append_table_from_pages(struct sg_append_table *sgt,
463 struct page **pages, unsigned int n_pages,
464 unsigned int offset, unsigned long size,
465 unsigned int max_segment,
466 unsigned int left_pages, gfp_t gfp_mask);
467 int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages,
468 unsigned int n_pages, unsigned int offset,
469 unsigned long size,
470 unsigned int max_segment, gfp_t gfp_mask);
471
472 /**
473 * sg_alloc_table_from_pages - Allocate and initialize an sg table from
474 * an array of pages
475 * @sgt: The sg table header to use
476 * @pages: Pointer to an array of page pointers
477 * @n_pages: Number of pages in the pages array
478 * @offset: Offset from start of the first page to the start of a buffer
479 * @size: Number of valid bytes in the buffer (after offset)
480 * @gfp_mask: GFP allocation mask
481 *
482 * Description:
483 * Allocate and initialize an sg table from a list of pages. Contiguous
484 * ranges of the pages are squashed into a single scatterlist node. A user
485 * may provide an offset at a start and a size of valid data in a buffer
486 * specified by the page array. The returned sg table is released by
487 * sg_free_table.
488 *
489 * Returns:
490 * 0 on success, negative error on failure
491 */
sg_alloc_table_from_pages(struct sg_table * sgt,struct page ** pages,unsigned int n_pages,unsigned int offset,unsigned long size,gfp_t gfp_mask)492 static inline int sg_alloc_table_from_pages(struct sg_table *sgt,
493 struct page **pages,
494 unsigned int n_pages,
495 unsigned int offset,
496 unsigned long size, gfp_t gfp_mask)
497 {
498 return sg_alloc_table_from_pages_segment(sgt, pages, n_pages, offset,
499 size, UINT_MAX, gfp_mask);
500 }
501
502 #ifdef CONFIG_SGL_ALLOC
503 struct scatterlist *sgl_alloc_order(unsigned long long length,
504 unsigned int order, bool chainable,
505 gfp_t gfp, unsigned int *nent_p);
506 struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
507 unsigned int *nent_p);
508 void sgl_free_n_order(struct scatterlist *sgl, int nents, int order);
509 void sgl_free_order(struct scatterlist *sgl, int order);
510 void sgl_free(struct scatterlist *sgl);
511 #endif /* CONFIG_SGL_ALLOC */
512
513 size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
514 size_t buflen, off_t skip, bool to_buffer);
515
516 size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
517 const void *buf, size_t buflen);
518 size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
519 void *buf, size_t buflen);
520
521 size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
522 const void *buf, size_t buflen, off_t skip);
523 size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
524 void *buf, size_t buflen, off_t skip);
525 size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
526 size_t buflen, off_t skip);
527
528 /*
529 * Maximum number of entries that will be allocated in one piece, if
530 * a list larger than this is required then chaining will be utilized.
531 */
532 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
533
534 /*
535 * The maximum number of SG segments that we will put inside a
536 * scatterlist (unless chaining is used). Should ideally fit inside a
537 * single page, to avoid a higher order allocation. We could define this
538 * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
539 * minimum value is 32
540 */
541 #define SG_CHUNK_SIZE 128
542
543 /*
544 * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
545 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
546 */
547 #ifdef CONFIG_ARCH_NO_SG_CHAIN
548 #define SG_MAX_SEGMENTS SG_CHUNK_SIZE
549 #else
550 #define SG_MAX_SEGMENTS 2048
551 #endif
552
553 #ifdef CONFIG_SG_POOL
554 void sg_free_table_chained(struct sg_table *table,
555 unsigned nents_first_chunk);
556 int sg_alloc_table_chained(struct sg_table *table, int nents,
557 struct scatterlist *first_chunk,
558 unsigned nents_first_chunk);
559 #endif
560
561 /*
562 * sg page iterator
563 *
564 * Iterates over sg entries page-by-page. On each successful iteration, you
565 * can call sg_page_iter_page(@piter) to get the current page.
566 * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to
567 * the page's page offset within the sg. The iteration will stop either when a
568 * maximum number of sg entries was reached or a terminating sg
569 * (sg_last(sg) == true) was reached.
570 */
571 struct sg_page_iter {
572 struct scatterlist *sg; /* sg holding the page */
573 unsigned int sg_pgoffset; /* page offset within the sg */
574
575 /* these are internal states, keep away */
576 unsigned int __nents; /* remaining sg entries */
577 int __pg_advance; /* nr pages to advance at the
578 * next step */
579 };
580
581 /*
582 * sg page iterator for DMA addresses
583 *
584 * This is the same as sg_page_iter however you can call
585 * sg_page_iter_dma_address(@dma_iter) to get the page's DMA
586 * address. sg_page_iter_page() cannot be called on this iterator.
587 */
588 struct sg_dma_page_iter {
589 struct sg_page_iter base;
590 };
591
592 bool __sg_page_iter_next(struct sg_page_iter *piter);
593 bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter);
594 void __sg_page_iter_start(struct sg_page_iter *piter,
595 struct scatterlist *sglist, unsigned int nents,
596 unsigned long pgoffset);
597 /**
598 * sg_page_iter_page - get the current page held by the page iterator
599 * @piter: page iterator holding the page
600 */
sg_page_iter_page(struct sg_page_iter * piter)601 static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
602 {
603 return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
604 }
605
606 /**
607 * sg_page_iter_dma_address - get the dma address of the current page held by
608 * the page iterator.
609 * @dma_iter: page iterator holding the page
610 */
611 static inline dma_addr_t
sg_page_iter_dma_address(struct sg_dma_page_iter * dma_iter)612 sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
613 {
614 return sg_dma_address(dma_iter->base.sg) +
615 (dma_iter->base.sg_pgoffset << PAGE_SHIFT);
616 }
617
618 /**
619 * for_each_sg_page - iterate over the pages of the given sg list
620 * @sglist: sglist to iterate over
621 * @piter: page iterator to hold current page, sg, sg_pgoffset
622 * @nents: maximum number of sg entries to iterate over
623 * @pgoffset: starting page offset (in pages)
624 *
625 * Callers may use sg_page_iter_page() to get each page pointer.
626 * In each loop it operates on PAGE_SIZE unit.
627 */
628 #define for_each_sg_page(sglist, piter, nents, pgoffset) \
629 for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
630 __sg_page_iter_next(piter);)
631
632 /**
633 * for_each_sg_dma_page - iterate over the pages of the given sg list
634 * @sglist: sglist to iterate over
635 * @dma_iter: DMA page iterator to hold current page
636 * @dma_nents: maximum number of sg entries to iterate over, this is the value
637 * returned from dma_map_sg
638 * @pgoffset: starting page offset (in pages)
639 *
640 * Callers may use sg_page_iter_dma_address() to get each page's DMA address.
641 * In each loop it operates on PAGE_SIZE unit.
642 */
643 #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \
644 for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \
645 pgoffset); \
646 __sg_page_iter_dma_next(dma_iter);)
647
648 /**
649 * for_each_sgtable_page - iterate over all pages in the sg_table object
650 * @sgt: sg_table object to iterate over
651 * @piter: page iterator to hold current page
652 * @pgoffset: starting page offset (in pages)
653 *
654 * Iterates over the all memory pages in the buffer described by
655 * a scatterlist stored in the given sg_table object.
656 * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit.
657 */
658 #define for_each_sgtable_page(sgt, piter, pgoffset) \
659 for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset)
660
661 /**
662 * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object
663 * @sgt: sg_table object to iterate over
664 * @dma_iter: DMA page iterator to hold current page
665 * @pgoffset: starting page offset (in pages)
666 *
667 * Iterates over the all DMA mapped pages in the buffer described by
668 * a scatterlist stored in the given sg_table object.
669 * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE
670 * unit.
671 */
672 #define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \
673 for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset)
674
675
676 /*
677 * Mapping sg iterator
678 *
679 * Iterates over sg entries mapping page-by-page. On each successful
680 * iteration, @miter->page points to the mapped page and
681 * @miter->length bytes of data can be accessed at @miter->addr. As
682 * long as an iteration is enclosed between start and stop, the user
683 * is free to choose control structure and when to stop.
684 *
685 * @miter->consumed is set to @miter->length on each iteration. It
686 * can be adjusted if the user can't consume all the bytes in one go.
687 * Also, a stopped iteration can be resumed by calling next on it.
688 * This is useful when iteration needs to release all resources and
689 * continue later (e.g. at the next interrupt).
690 */
691
692 #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
693 #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
694 #define SG_MITER_FROM_SG (1 << 2) /* nop */
695 #define SG_MITER_LOCAL (1 << 3) /* use kmap_local */
696
697 struct sg_mapping_iter {
698 /* the following three fields can be accessed directly */
699 struct page *page; /* currently mapped page */
700 void *addr; /* pointer to the mapped area */
701 size_t length; /* length of the mapped area */
702 size_t consumed; /* number of consumed bytes */
703 struct sg_page_iter piter; /* page iterator */
704
705 /* these are internal states, keep away */
706 unsigned int __offset; /* offset within page */
707 unsigned int __remaining; /* remaining bytes on page */
708 unsigned int __flags;
709 };
710
711 void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
712 unsigned int nents, unsigned int flags);
713 bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
714 bool sg_miter_next(struct sg_mapping_iter *miter);
715 void sg_miter_stop(struct sg_mapping_iter *miter);
716
717 #endif /* _LINUX_SCATTERLIST_H */
718