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 * Since the above length field is an unsigned int, below we define the maximum
23 * length in bytes that can be stored in one scatterlist entry.
25 #define SCATTERLIST_MAX_SEGMENT (UINT_MAX & PAGE_MASK)
28 * These macros should be used after a dma_map_sg call has been done
29 * to get bus addresses of each of the SG entries and their lengths.
30 * You should only work with the number of sg entries dma_map_sg
31 * returns, or alternatively stop on the first sg_dma_len(sg) which
34 #define sg_dma_address(sg) ((sg)->dma_address)
36 #ifdef CONFIG_NEED_SG_DMA_LENGTH
37 #define sg_dma_len(sg) ((sg)->dma_length)
39 #define sg_dma_len(sg) ((sg)->length)
43 struct scatterlist *sgl; /* the list */
44 unsigned int nents; /* number of mapped entries */
45 unsigned int orig_nents; /* original size of list */
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_is_chain(sg) ((sg)->page_link & SG_CHAIN)
73 #define sg_is_last(sg) ((sg)->page_link & SG_END)
74 #define sg_chain_ptr(sg) \
75 ((struct scatterlist *) ((sg)->page_link & ~(SG_CHAIN | SG_END)))
78 * sg_assign_page - Assign a given page to an SG entry
83 * Assign page to sg entry. Also see sg_set_page(), the most commonly used
87 static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
89 unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END);
92 * In order for the low bit stealing approach to work, pages
93 * must be aligned at a 32-bit boundary as a minimum.
95 BUG_ON((unsigned long) page & (SG_CHAIN | SG_END));
96 #ifdef CONFIG_DEBUG_SG
97 BUG_ON(sg_is_chain(sg));
99 sg->page_link = page_link | (unsigned long) page;
103 * sg_set_page - Set sg entry to point at given page
106 * @len: Length of data
107 * @offset: Offset into page
110 * Use this function to set an sg entry pointing at a page, never assign
111 * the page directly. We encode sg table information in the lower bits
112 * of the page pointer. See sg_page() for looking up the page belonging
116 static inline void sg_set_page(struct scatterlist *sg, struct page *page,
117 unsigned int len, unsigned int offset)
119 sg_assign_page(sg, page);
124 static inline struct page *sg_page(struct scatterlist *sg)
126 #ifdef CONFIG_DEBUG_SG
127 BUG_ON(sg_is_chain(sg));
129 return (struct page *)((sg)->page_link & ~(SG_CHAIN | SG_END));
133 * sg_set_buf - Set sg entry to point at given data
136 * @buflen: Data length
139 static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
142 #ifdef CONFIG_DEBUG_SG
143 BUG_ON(!virt_addr_valid(buf));
145 sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
149 * Loop over each sg element, following the pointer to a new list if necessary
151 #define for_each_sg(sglist, sg, nr, __i) \
152 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
155 * Loop over each sg element in the given sg_table object.
157 #define for_each_sgtable_sg(sgt, sg, i) \
158 for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i)
161 * Loop over each sg element in the given *DMA mapped* sg_table object.
162 * Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses
163 * of the each element.
165 #define for_each_sgtable_dma_sg(sgt, sg, i) \
166 for_each_sg((sgt)->sgl, sg, (sgt)->nents, i)
169 * sg_chain - Chain two sglists together
170 * @prv: First scatterlist
171 * @prv_nents: Number of entries in prv
172 * @sgl: Second scatterlist
175 * Links @prv@ and @sgl@ together, to form a longer scatterlist.
178 static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
179 struct scatterlist *sgl)
182 * offset and length are unused for chain entry. Clear them.
184 prv[prv_nents - 1].offset = 0;
185 prv[prv_nents - 1].length = 0;
188 * Set lowest bit to indicate a link pointer, and make sure to clear
189 * the termination bit if it happens to be set.
191 prv[prv_nents - 1].page_link = ((unsigned long) sgl | SG_CHAIN)
196 * sg_mark_end - Mark the end of the scatterlist
197 * @sg: SG entryScatterlist
200 * Marks the passed in sg entry as the termination point for the sg
201 * table. A call to sg_next() on this entry will return NULL.
204 static inline void sg_mark_end(struct scatterlist *sg)
207 * Set termination bit, clear potential chain bit
209 sg->page_link |= SG_END;
210 sg->page_link &= ~SG_CHAIN;
214 * sg_unmark_end - Undo setting the end of the scatterlist
215 * @sg: SG entryScatterlist
218 * Removes the termination marker from the given entry of the scatterlist.
221 static inline void sg_unmark_end(struct scatterlist *sg)
223 sg->page_link &= ~SG_END;
227 * sg_phys - Return physical address of an sg entry
231 * This calls page_to_phys() on the page in this sg entry, and adds the
232 * sg offset. The caller must know that it is legal to call page_to_phys()
236 static inline dma_addr_t sg_phys(struct scatterlist *sg)
238 return page_to_phys(sg_page(sg)) + sg->offset;
242 * sg_virt - Return virtual address of an sg entry
246 * This calls page_address() on the page in this sg entry, and adds the
247 * sg offset. The caller must know that the sg page has a valid virtual
251 static inline void *sg_virt(struct scatterlist *sg)
253 return page_address(sg_page(sg)) + sg->offset;
257 * sg_init_marker - Initialize markers in sg table
259 * @nents: Number of entries in table
262 static inline void sg_init_marker(struct scatterlist *sgl,
265 sg_mark_end(&sgl[nents - 1]);
268 int sg_nents(struct scatterlist *sg);
269 int sg_nents_for_len(struct scatterlist *sg, u64 len);
270 struct scatterlist *sg_next(struct scatterlist *);
271 struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
272 void sg_init_table(struct scatterlist *, unsigned int);
273 void sg_init_one(struct scatterlist *, const void *, unsigned int);
274 int sg_split(struct scatterlist *in, const int in_mapped_nents,
275 const off_t skip, const int nb_splits,
276 const size_t *split_sizes,
277 struct scatterlist **out, int *out_mapped_nents,
280 typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
281 typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
283 void __sg_free_table(struct sg_table *, unsigned int, unsigned int,
285 void sg_free_table(struct sg_table *);
286 int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
287 struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *);
288 int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
289 int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
290 unsigned int n_pages, unsigned int offset,
291 unsigned long size, unsigned int max_segment,
293 int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
294 unsigned int n_pages, unsigned int offset,
295 unsigned long size, gfp_t gfp_mask);
297 #ifdef CONFIG_SGL_ALLOC
298 struct scatterlist *sgl_alloc_order(unsigned long long length,
299 unsigned int order, bool chainable,
300 gfp_t gfp, unsigned int *nent_p);
301 struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
302 unsigned int *nent_p);
303 void sgl_free_n_order(struct scatterlist *sgl, int nents, int order);
304 void sgl_free_order(struct scatterlist *sgl, int order);
305 void sgl_free(struct scatterlist *sgl);
306 #endif /* CONFIG_SGL_ALLOC */
308 size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
309 size_t buflen, off_t skip, bool to_buffer);
311 size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
312 const void *buf, size_t buflen);
313 size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
314 void *buf, size_t buflen);
316 size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
317 const void *buf, size_t buflen, off_t skip);
318 size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
319 void *buf, size_t buflen, off_t skip);
320 size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
321 size_t buflen, off_t skip);
324 * Maximum number of entries that will be allocated in one piece, if
325 * a list larger than this is required then chaining will be utilized.
327 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
330 * The maximum number of SG segments that we will put inside a
331 * scatterlist (unless chaining is used). Should ideally fit inside a
332 * single page, to avoid a higher order allocation. We could define this
333 * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
334 * minimum value is 32
336 #define SG_CHUNK_SIZE 128
339 * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
340 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
342 #ifdef CONFIG_ARCH_NO_SG_CHAIN
343 #define SG_MAX_SEGMENTS SG_CHUNK_SIZE
345 #define SG_MAX_SEGMENTS 2048
348 #ifdef CONFIG_SG_POOL
349 void sg_free_table_chained(struct sg_table *table,
350 unsigned nents_first_chunk);
351 int sg_alloc_table_chained(struct sg_table *table, int nents,
352 struct scatterlist *first_chunk,
353 unsigned nents_first_chunk);
359 * Iterates over sg entries page-by-page. On each successful iteration, you
360 * can call sg_page_iter_page(@piter) to get the current page.
361 * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to
362 * the page's page offset within the sg. The iteration will stop either when a
363 * maximum number of sg entries was reached or a terminating sg
364 * (sg_last(sg) == true) was reached.
366 struct sg_page_iter {
367 struct scatterlist *sg; /* sg holding the page */
368 unsigned int sg_pgoffset; /* page offset within the sg */
370 /* these are internal states, keep away */
371 unsigned int __nents; /* remaining sg entries */
372 int __pg_advance; /* nr pages to advance at the
377 * sg page iterator for DMA addresses
379 * This is the same as sg_page_iter however you can call
380 * sg_page_iter_dma_address(@dma_iter) to get the page's DMA
381 * address. sg_page_iter_page() cannot be called on this iterator.
383 struct sg_dma_page_iter {
384 struct sg_page_iter base;
387 bool __sg_page_iter_next(struct sg_page_iter *piter);
388 bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter);
389 void __sg_page_iter_start(struct sg_page_iter *piter,
390 struct scatterlist *sglist, unsigned int nents,
391 unsigned long pgoffset);
393 * sg_page_iter_page - get the current page held by the page iterator
394 * @piter: page iterator holding the page
396 static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
398 return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
402 * sg_page_iter_dma_address - get the dma address of the current page held by
404 * @dma_iter: page iterator holding the page
406 static inline dma_addr_t
407 sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
409 return sg_dma_address(dma_iter->base.sg) +
410 (dma_iter->base.sg_pgoffset << PAGE_SHIFT);
414 * for_each_sg_page - iterate over the pages of the given sg list
415 * @sglist: sglist to iterate over
416 * @piter: page iterator to hold current page, sg, sg_pgoffset
417 * @nents: maximum number of sg entries to iterate over
418 * @pgoffset: starting page offset (in pages)
420 * Callers may use sg_page_iter_page() to get each page pointer.
421 * In each loop it operates on PAGE_SIZE unit.
423 #define for_each_sg_page(sglist, piter, nents, pgoffset) \
424 for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
425 __sg_page_iter_next(piter);)
428 * for_each_sg_dma_page - iterate over the pages of the given sg list
429 * @sglist: sglist to iterate over
430 * @dma_iter: DMA page iterator to hold current page
431 * @dma_nents: maximum number of sg entries to iterate over, this is the value
432 * returned from dma_map_sg
433 * @pgoffset: starting page offset (in pages)
435 * Callers may use sg_page_iter_dma_address() to get each page's DMA address.
436 * In each loop it operates on PAGE_SIZE unit.
438 #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \
439 for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \
441 __sg_page_iter_dma_next(dma_iter);)
444 * for_each_sgtable_page - iterate over all pages in the sg_table object
445 * @sgt: sg_table object to iterate over
446 * @piter: page iterator to hold current page
447 * @pgoffset: starting page offset (in pages)
449 * Iterates over the all memory pages in the buffer described by
450 * a scatterlist stored in the given sg_table object.
451 * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit.
453 #define for_each_sgtable_page(sgt, piter, pgoffset) \
454 for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset)
457 * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object
458 * @sgt: sg_table object to iterate over
459 * @dma_iter: DMA page iterator to hold current page
460 * @pgoffset: starting page offset (in pages)
462 * Iterates over the all DMA mapped pages in the buffer described by
463 * a scatterlist stored in the given sg_table object.
464 * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE
467 #define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \
468 for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset)
472 * Mapping sg iterator
474 * Iterates over sg entries mapping page-by-page. On each successful
475 * iteration, @miter->page points to the mapped page and
476 * @miter->length bytes of data can be accessed at @miter->addr. As
477 * long as an interation is enclosed between start and stop, the user
478 * is free to choose control structure and when to stop.
480 * @miter->consumed is set to @miter->length on each iteration. It
481 * can be adjusted if the user can't consume all the bytes in one go.
482 * Also, a stopped iteration can be resumed by calling next on it.
483 * This is useful when iteration needs to release all resources and
484 * continue later (e.g. at the next interrupt).
487 #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
488 #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
489 #define SG_MITER_FROM_SG (1 << 2) /* nop */
491 struct sg_mapping_iter {
492 /* the following three fields can be accessed directly */
493 struct page *page; /* currently mapped page */
494 void *addr; /* pointer to the mapped area */
495 size_t length; /* length of the mapped area */
496 size_t consumed; /* number of consumed bytes */
497 struct sg_page_iter piter; /* page iterator */
499 /* these are internal states, keep away */
500 unsigned int __offset; /* offset within page */
501 unsigned int __remaining; /* remaining bytes on page */
502 unsigned int __flags;
505 void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
506 unsigned int nents, unsigned int flags);
507 bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
508 bool sg_miter_next(struct sg_mapping_iter *miter);
509 void sg_miter_stop(struct sg_mapping_iter *miter);
511 #endif /* _LINUX_SCATTERLIST_H */