1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SCATTERLIST_H
3 #define _LINUX_SCATTERLIST_H
5 #include <linux/string.h>
6 #include <linux/types.h>
12 unsigned long page_link;
15 dma_addr_t dma_address;
16 #ifdef CONFIG_NEED_SG_DMA_LENGTH
17 unsigned int dma_length;
22 * These macros should be used after a dma_map_sg call has been done
23 * to get bus addresses of each of the SG entries and their lengths.
24 * You should only work with the number of sg entries dma_map_sg
25 * returns, or alternatively stop on the first sg_dma_len(sg) which
28 #define sg_dma_address(sg) ((sg)->dma_address)
30 #ifdef CONFIG_NEED_SG_DMA_LENGTH
31 #define sg_dma_len(sg) ((sg)->dma_length)
33 #define sg_dma_len(sg) ((sg)->length)
37 struct scatterlist *sgl; /* the list */
38 unsigned int nents; /* number of mapped entries */
39 unsigned int orig_nents; /* original size of list */
42 struct sg_append_table {
43 struct sg_table sgt; /* The scatter list table */
44 struct scatterlist *prv; /* last populated sge in the table */
45 unsigned int total_nents; /* Total entries in the table */
49 * Notes on SG table design.
51 * We use the unsigned long page_link field in the scatterlist struct to place
52 * the page pointer AND encode information about the sg table as well. The two
53 * lower bits are reserved for this information.
55 * If bit 0 is set, then the page_link contains a pointer to the next sg
56 * table list. Otherwise the next entry is at sg + 1.
58 * If bit 1 is set, then this sg entry is the last element in a list.
64 #define SG_CHAIN 0x01UL
68 * We overload the LSB of the page pointer to indicate whether it's
69 * a valid sg entry, or whether it points to the start of a new scatterlist.
70 * Those low bits are there for everyone! (thanks mason :-)
72 #define SG_PAGE_LINK_MASK (SG_CHAIN | SG_END)
74 static inline unsigned int __sg_flags(struct scatterlist *sg)
76 return sg->page_link & SG_PAGE_LINK_MASK;
79 static inline struct scatterlist *sg_chain_ptr(struct scatterlist *sg)
81 return (struct scatterlist *)(sg->page_link & ~SG_PAGE_LINK_MASK);
84 static inline bool sg_is_chain(struct scatterlist *sg)
86 return __sg_flags(sg) & SG_CHAIN;
89 static inline bool sg_is_last(struct scatterlist *sg)
91 return __sg_flags(sg) & SG_END;
95 * sg_assign_page - Assign a given page to an SG entry
100 * Assign page to sg entry. Also see sg_set_page(), the most commonly used
104 static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
106 unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END);
109 * In order for the low bit stealing approach to work, pages
110 * must be aligned at a 32-bit boundary as a minimum.
112 BUG_ON((unsigned long)page & SG_PAGE_LINK_MASK);
113 #ifdef CONFIG_DEBUG_SG
114 BUG_ON(sg_is_chain(sg));
116 sg->page_link = page_link | (unsigned long) page;
120 * sg_set_page - Set sg entry to point at given page
123 * @len: Length of data
124 * @offset: Offset into page
127 * Use this function to set an sg entry pointing at a page, never assign
128 * the page directly. We encode sg table information in the lower bits
129 * of the page pointer. See sg_page() for looking up the page belonging
133 static inline void sg_set_page(struct scatterlist *sg, struct page *page,
134 unsigned int len, unsigned int offset)
136 sg_assign_page(sg, page);
141 static inline struct page *sg_page(struct scatterlist *sg)
143 #ifdef CONFIG_DEBUG_SG
144 BUG_ON(sg_is_chain(sg));
146 return (struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK);
150 * sg_set_buf - Set sg entry to point at given data
153 * @buflen: Data length
156 static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
159 #ifdef CONFIG_DEBUG_SG
160 BUG_ON(!virt_addr_valid(buf));
162 sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
166 * Loop over each sg element, following the pointer to a new list if necessary
168 #define for_each_sg(sglist, sg, nr, __i) \
169 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
172 * Loop over each sg element in the given sg_table object.
174 #define for_each_sgtable_sg(sgt, sg, i) \
175 for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i)
178 * Loop over each sg element in the given *DMA mapped* sg_table object.
179 * Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses
180 * of the each element.
182 #define for_each_sgtable_dma_sg(sgt, sg, i) \
183 for_each_sg((sgt)->sgl, sg, (sgt)->nents, i)
185 static inline void __sg_chain(struct scatterlist *chain_sg,
186 struct scatterlist *sgl)
189 * offset and length are unused for chain entry. Clear them.
191 chain_sg->offset = 0;
192 chain_sg->length = 0;
195 * Set lowest bit to indicate a link pointer, and make sure to clear
196 * the termination bit if it happens to be set.
198 chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END;
202 * sg_chain - Chain two sglists together
203 * @prv: First scatterlist
204 * @prv_nents: Number of entries in prv
205 * @sgl: Second scatterlist
208 * Links @prv@ and @sgl@ together, to form a longer scatterlist.
211 static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
212 struct scatterlist *sgl)
214 __sg_chain(&prv[prv_nents - 1], sgl);
218 * sg_mark_end - Mark the end of the scatterlist
219 * @sg: SG entryScatterlist
222 * Marks the passed in sg entry as the termination point for the sg
223 * table. A call to sg_next() on this entry will return NULL.
226 static inline void sg_mark_end(struct scatterlist *sg)
229 * Set termination bit, clear potential chain bit
231 sg->page_link |= SG_END;
232 sg->page_link &= ~SG_CHAIN;
236 * sg_unmark_end - Undo setting the end of the scatterlist
237 * @sg: SG entryScatterlist
240 * Removes the termination marker from the given entry of the scatterlist.
243 static inline void sg_unmark_end(struct scatterlist *sg)
245 sg->page_link &= ~SG_END;
249 * sg_phys - Return physical address of an sg entry
253 * This calls page_to_phys() on the page in this sg entry, and adds the
254 * sg offset. The caller must know that it is legal to call page_to_phys()
258 static inline dma_addr_t sg_phys(struct scatterlist *sg)
260 return page_to_phys(sg_page(sg)) + sg->offset;
264 * sg_virt - Return virtual address of an sg entry
268 * This calls page_address() on the page in this sg entry, and adds the
269 * sg offset. The caller must know that the sg page has a valid virtual
273 static inline void *sg_virt(struct scatterlist *sg)
275 return page_address(sg_page(sg)) + sg->offset;
279 * sg_init_marker - Initialize markers in sg table
281 * @nents: Number of entries in table
284 static inline void sg_init_marker(struct scatterlist *sgl,
287 sg_mark_end(&sgl[nents - 1]);
290 int sg_nents(struct scatterlist *sg);
291 int sg_nents_for_len(struct scatterlist *sg, u64 len);
292 struct scatterlist *sg_next(struct scatterlist *);
293 struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
294 void sg_init_table(struct scatterlist *, unsigned int);
295 void sg_init_one(struct scatterlist *, const void *, unsigned int);
296 int sg_split(struct scatterlist *in, const int in_mapped_nents,
297 const off_t skip, const int nb_splits,
298 const size_t *split_sizes,
299 struct scatterlist **out, int *out_mapped_nents,
302 typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
303 typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
305 void __sg_free_table(struct sg_table *, unsigned int, unsigned int,
306 sg_free_fn *, unsigned int);
307 void sg_free_table(struct sg_table *);
308 void sg_free_append_table(struct sg_append_table *sgt);
309 int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
310 struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *);
311 int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
312 int sg_alloc_append_table_from_pages(struct sg_append_table *sgt,
313 struct page **pages, unsigned int n_pages,
314 unsigned int offset, unsigned long size,
315 unsigned int max_segment,
316 unsigned int left_pages, gfp_t gfp_mask);
317 int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages,
318 unsigned int n_pages, unsigned int offset,
320 unsigned int max_segment, gfp_t gfp_mask);
323 * sg_alloc_table_from_pages - Allocate and initialize an sg table from
325 * @sgt: The sg table header to use
326 * @pages: Pointer to an array of page pointers
327 * @n_pages: Number of pages in the pages array
328 * @offset: Offset from start of the first page to the start of a buffer
329 * @size: Number of valid bytes in the buffer (after offset)
330 * @gfp_mask: GFP allocation mask
333 * Allocate and initialize an sg table from a list of pages. Contiguous
334 * ranges of the pages are squashed into a single scatterlist node. A user
335 * may provide an offset at a start and a size of valid data in a buffer
336 * specified by the page array. The returned sg table is released by
340 * 0 on success, negative error on failure
342 static inline int sg_alloc_table_from_pages(struct sg_table *sgt,
344 unsigned int n_pages,
346 unsigned long size, gfp_t gfp_mask)
348 return sg_alloc_table_from_pages_segment(sgt, pages, n_pages, offset,
349 size, UINT_MAX, gfp_mask);
352 #ifdef CONFIG_SGL_ALLOC
353 struct scatterlist *sgl_alloc_order(unsigned long long length,
354 unsigned int order, bool chainable,
355 gfp_t gfp, unsigned int *nent_p);
356 struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
357 unsigned int *nent_p);
358 void sgl_free_n_order(struct scatterlist *sgl, int nents, int order);
359 void sgl_free_order(struct scatterlist *sgl, int order);
360 void sgl_free(struct scatterlist *sgl);
361 #endif /* CONFIG_SGL_ALLOC */
363 size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
364 size_t buflen, off_t skip, bool to_buffer);
366 size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
367 const void *buf, size_t buflen);
368 size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
369 void *buf, size_t buflen);
371 size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
372 const void *buf, size_t buflen, off_t skip);
373 size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
374 void *buf, size_t buflen, off_t skip);
375 size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
376 size_t buflen, off_t skip);
379 * Maximum number of entries that will be allocated in one piece, if
380 * a list larger than this is required then chaining will be utilized.
382 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
385 * The maximum number of SG segments that we will put inside a
386 * scatterlist (unless chaining is used). Should ideally fit inside a
387 * single page, to avoid a higher order allocation. We could define this
388 * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
389 * minimum value is 32
391 #define SG_CHUNK_SIZE 128
394 * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
395 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
397 #ifdef CONFIG_ARCH_NO_SG_CHAIN
398 #define SG_MAX_SEGMENTS SG_CHUNK_SIZE
400 #define SG_MAX_SEGMENTS 2048
403 #ifdef CONFIG_SG_POOL
404 void sg_free_table_chained(struct sg_table *table,
405 unsigned nents_first_chunk);
406 int sg_alloc_table_chained(struct sg_table *table, int nents,
407 struct scatterlist *first_chunk,
408 unsigned nents_first_chunk);
414 * Iterates over sg entries page-by-page. On each successful iteration, you
415 * can call sg_page_iter_page(@piter) to get the current page.
416 * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to
417 * the page's page offset within the sg. The iteration will stop either when a
418 * maximum number of sg entries was reached or a terminating sg
419 * (sg_last(sg) == true) was reached.
421 struct sg_page_iter {
422 struct scatterlist *sg; /* sg holding the page */
423 unsigned int sg_pgoffset; /* page offset within the sg */
425 /* these are internal states, keep away */
426 unsigned int __nents; /* remaining sg entries */
427 int __pg_advance; /* nr pages to advance at the
432 * sg page iterator for DMA addresses
434 * This is the same as sg_page_iter however you can call
435 * sg_page_iter_dma_address(@dma_iter) to get the page's DMA
436 * address. sg_page_iter_page() cannot be called on this iterator.
438 struct sg_dma_page_iter {
439 struct sg_page_iter base;
442 bool __sg_page_iter_next(struct sg_page_iter *piter);
443 bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter);
444 void __sg_page_iter_start(struct sg_page_iter *piter,
445 struct scatterlist *sglist, unsigned int nents,
446 unsigned long pgoffset);
448 * sg_page_iter_page - get the current page held by the page iterator
449 * @piter: page iterator holding the page
451 static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
453 return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
457 * sg_page_iter_dma_address - get the dma address of the current page held by
459 * @dma_iter: page iterator holding the page
461 static inline dma_addr_t
462 sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
464 return sg_dma_address(dma_iter->base.sg) +
465 (dma_iter->base.sg_pgoffset << PAGE_SHIFT);
469 * for_each_sg_page - iterate over the pages of the given sg list
470 * @sglist: sglist to iterate over
471 * @piter: page iterator to hold current page, sg, sg_pgoffset
472 * @nents: maximum number of sg entries to iterate over
473 * @pgoffset: starting page offset (in pages)
475 * Callers may use sg_page_iter_page() to get each page pointer.
476 * In each loop it operates on PAGE_SIZE unit.
478 #define for_each_sg_page(sglist, piter, nents, pgoffset) \
479 for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
480 __sg_page_iter_next(piter);)
483 * for_each_sg_dma_page - iterate over the pages of the given sg list
484 * @sglist: sglist to iterate over
485 * @dma_iter: DMA page iterator to hold current page
486 * @dma_nents: maximum number of sg entries to iterate over, this is the value
487 * returned from dma_map_sg
488 * @pgoffset: starting page offset (in pages)
490 * Callers may use sg_page_iter_dma_address() to get each page's DMA address.
491 * In each loop it operates on PAGE_SIZE unit.
493 #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \
494 for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \
496 __sg_page_iter_dma_next(dma_iter);)
499 * for_each_sgtable_page - iterate over all pages in the sg_table object
500 * @sgt: sg_table object to iterate over
501 * @piter: page iterator to hold current page
502 * @pgoffset: starting page offset (in pages)
504 * Iterates over the all memory pages in the buffer described by
505 * a scatterlist stored in the given sg_table object.
506 * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit.
508 #define for_each_sgtable_page(sgt, piter, pgoffset) \
509 for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset)
512 * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object
513 * @sgt: sg_table object to iterate over
514 * @dma_iter: DMA page iterator to hold current page
515 * @pgoffset: starting page offset (in pages)
517 * Iterates over the all DMA mapped pages in the buffer described by
518 * a scatterlist stored in the given sg_table object.
519 * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE
522 #define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \
523 for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset)
527 * Mapping sg iterator
529 * Iterates over sg entries mapping page-by-page. On each successful
530 * iteration, @miter->page points to the mapped page and
531 * @miter->length bytes of data can be accessed at @miter->addr. As
532 * long as an iteration is enclosed between start and stop, the user
533 * is free to choose control structure and when to stop.
535 * @miter->consumed is set to @miter->length on each iteration. It
536 * can be adjusted if the user can't consume all the bytes in one go.
537 * Also, a stopped iteration can be resumed by calling next on it.
538 * This is useful when iteration needs to release all resources and
539 * continue later (e.g. at the next interrupt).
542 #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
543 #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
544 #define SG_MITER_FROM_SG (1 << 2) /* nop */
546 struct sg_mapping_iter {
547 /* the following three fields can be accessed directly */
548 struct page *page; /* currently mapped page */
549 void *addr; /* pointer to the mapped area */
550 size_t length; /* length of the mapped area */
551 size_t consumed; /* number of consumed bytes */
552 struct sg_page_iter piter; /* page iterator */
554 /* these are internal states, keep away */
555 unsigned int __offset; /* offset within page */
556 unsigned int __remaining; /* remaining bytes on page */
557 unsigned int __flags;
560 void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
561 unsigned int nents, unsigned int flags);
562 bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
563 bool sg_miter_next(struct sg_mapping_iter *miter);
564 void sg_miter_stop(struct sg_mapping_iter *miter);
566 #endif /* _LINUX_SCATTERLIST_H */