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 };
20
21 /*
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
26 * is 0.
27 */
28 #define sg_dma_address(sg) ((sg)->dma_address)
29
30 #ifdef CONFIG_NEED_SG_DMA_LENGTH
31 #define sg_dma_len(sg) ((sg)->dma_length)
32 #else
33 #define sg_dma_len(sg) ((sg)->length)
34 #endif
35
36 struct sg_table {
37 struct scatterlist *sgl; /* the list */
38 unsigned int nents; /* number of mapped entries */
39 unsigned int orig_nents; /* original size of list */
40 };
41
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 */
46 };
47
48 /*
49 * Notes on SG table design.
50 *
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.
54 *
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.
57 *
58 * If bit 1 is set, then this sg entry is the last element in a list.
59 *
60 * See sg_next().
61 *
62 */
63
64 #define SG_CHAIN 0x01UL
65 #define SG_END 0x02UL
66
67 /*
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 :-)
71 */
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)))
76
77 /**
78 * sg_assign_page - Assign a given page to an SG entry
79 * @sg: SG entry
80 * @page: The page
81 *
82 * Description:
83 * Assign page to sg entry. Also see sg_set_page(), the most commonly used
84 * variant.
85 *
86 **/
sg_assign_page(struct scatterlist * sg,struct page * page)87 static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
88 {
89 unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END);
90
91 /*
92 * In order for the low bit stealing approach to work, pages
93 * must be aligned at a 32-bit boundary as a minimum.
94 */
95 BUG_ON((unsigned long) page & (SG_CHAIN | SG_END));
96 #ifdef CONFIG_DEBUG_SG
97 BUG_ON(sg_is_chain(sg));
98 #endif
99 sg->page_link = page_link | (unsigned long) page;
100 }
101
102 /**
103 * sg_set_page - Set sg entry to point at given page
104 * @sg: SG entry
105 * @page: The page
106 * @len: Length of data
107 * @offset: Offset into page
108 *
109 * Description:
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
113 * to an sg entry.
114 *
115 **/
sg_set_page(struct scatterlist * sg,struct page * page,unsigned int len,unsigned int offset)116 static inline void sg_set_page(struct scatterlist *sg, struct page *page,
117 unsigned int len, unsigned int offset)
118 {
119 sg_assign_page(sg, page);
120 sg->offset = offset;
121 sg->length = len;
122 }
123
sg_page(struct scatterlist * sg)124 static inline struct page *sg_page(struct scatterlist *sg)
125 {
126 #ifdef CONFIG_DEBUG_SG
127 BUG_ON(sg_is_chain(sg));
128 #endif
129 return (struct page *)((sg)->page_link & ~(SG_CHAIN | SG_END));
130 }
131
132 /**
133 * sg_set_buf - Set sg entry to point at given data
134 * @sg: SG entry
135 * @buf: Data
136 * @buflen: Data length
137 *
138 **/
sg_set_buf(struct scatterlist * sg,const void * buf,unsigned int buflen)139 static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
140 unsigned int buflen)
141 {
142 #ifdef CONFIG_DEBUG_SG
143 BUG_ON(!virt_addr_valid(buf));
144 #endif
145 sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
146 }
147
148 /*
149 * Loop over each sg element, following the pointer to a new list if necessary
150 */
151 #define for_each_sg(sglist, sg, nr, __i) \
152 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
153
154 /*
155 * Loop over each sg element in the given sg_table object.
156 */
157 #define for_each_sgtable_sg(sgt, sg, i) \
158 for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i)
159
160 /*
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.
164 */
165 #define for_each_sgtable_dma_sg(sgt, sg, i) \
166 for_each_sg((sgt)->sgl, sg, (sgt)->nents, i)
167
__sg_chain(struct scatterlist * chain_sg,struct scatterlist * sgl)168 static inline void __sg_chain(struct scatterlist *chain_sg,
169 struct scatterlist *sgl)
170 {
171 /*
172 * offset and length are unused for chain entry. Clear them.
173 */
174 chain_sg->offset = 0;
175 chain_sg->length = 0;
176
177 /*
178 * Set lowest bit to indicate a link pointer, and make sure to clear
179 * the termination bit if it happens to be set.
180 */
181 chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END;
182 }
183
184 /**
185 * sg_chain - Chain two sglists together
186 * @prv: First scatterlist
187 * @prv_nents: Number of entries in prv
188 * @sgl: Second scatterlist
189 *
190 * Description:
191 * Links @prv@ and @sgl@ together, to form a longer scatterlist.
192 *
193 **/
sg_chain(struct scatterlist * prv,unsigned int prv_nents,struct scatterlist * sgl)194 static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
195 struct scatterlist *sgl)
196 {
197 __sg_chain(&prv[prv_nents - 1], sgl);
198 }
199
200 /**
201 * sg_mark_end - Mark the end of the scatterlist
202 * @sg: SG entryScatterlist
203 *
204 * Description:
205 * Marks the passed in sg entry as the termination point for the sg
206 * table. A call to sg_next() on this entry will return NULL.
207 *
208 **/
sg_mark_end(struct scatterlist * sg)209 static inline void sg_mark_end(struct scatterlist *sg)
210 {
211 /*
212 * Set termination bit, clear potential chain bit
213 */
214 sg->page_link |= SG_END;
215 sg->page_link &= ~SG_CHAIN;
216 }
217
218 /**
219 * sg_unmark_end - Undo setting the end of the scatterlist
220 * @sg: SG entryScatterlist
221 *
222 * Description:
223 * Removes the termination marker from the given entry of the scatterlist.
224 *
225 **/
sg_unmark_end(struct scatterlist * sg)226 static inline void sg_unmark_end(struct scatterlist *sg)
227 {
228 sg->page_link &= ~SG_END;
229 }
230
231 /**
232 * sg_phys - Return physical address of an sg entry
233 * @sg: SG entry
234 *
235 * Description:
236 * This calls page_to_phys() on the page in this sg entry, and adds the
237 * sg offset. The caller must know that it is legal to call page_to_phys()
238 * on the sg page.
239 *
240 **/
sg_phys(struct scatterlist * sg)241 static inline dma_addr_t sg_phys(struct scatterlist *sg)
242 {
243 return page_to_phys(sg_page(sg)) + sg->offset;
244 }
245
246 /**
247 * sg_virt - Return virtual address of an sg entry
248 * @sg: SG entry
249 *
250 * Description:
251 * This calls page_address() on the page in this sg entry, and adds the
252 * sg offset. The caller must know that the sg page has a valid virtual
253 * mapping.
254 *
255 **/
sg_virt(struct scatterlist * sg)256 static inline void *sg_virt(struct scatterlist *sg)
257 {
258 return page_address(sg_page(sg)) + sg->offset;
259 }
260
261 /**
262 * sg_init_marker - Initialize markers in sg table
263 * @sgl: The SG table
264 * @nents: Number of entries in table
265 *
266 **/
sg_init_marker(struct scatterlist * sgl,unsigned int nents)267 static inline void sg_init_marker(struct scatterlist *sgl,
268 unsigned int nents)
269 {
270 sg_mark_end(&sgl[nents - 1]);
271 }
272
273 int sg_nents(struct scatterlist *sg);
274 int sg_nents_for_len(struct scatterlist *sg, u64 len);
275 struct scatterlist *sg_next(struct scatterlist *);
276 struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
277 void sg_init_table(struct scatterlist *, unsigned int);
278 void sg_init_one(struct scatterlist *, const void *, unsigned int);
279 int sg_split(struct scatterlist *in, const int in_mapped_nents,
280 const off_t skip, const int nb_splits,
281 const size_t *split_sizes,
282 struct scatterlist **out, int *out_mapped_nents,
283 gfp_t gfp_mask);
284
285 typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
286 typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
287
288 void __sg_free_table(struct sg_table *, unsigned int, unsigned int,
289 sg_free_fn *, unsigned int);
290 void sg_free_table(struct sg_table *);
291 void sg_free_append_table(struct sg_append_table *sgt);
292 int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
293 struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *);
294 int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
295 int sg_alloc_append_table_from_pages(struct sg_append_table *sgt,
296 struct page **pages, unsigned int n_pages,
297 unsigned int offset, unsigned long size,
298 unsigned int max_segment,
299 unsigned int left_pages, gfp_t gfp_mask);
300 int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages,
301 unsigned int n_pages, unsigned int offset,
302 unsigned long size,
303 unsigned int max_segment, gfp_t gfp_mask);
304
305 /**
306 * sg_alloc_table_from_pages - Allocate and initialize an sg table from
307 * an array of pages
308 * @sgt: The sg table header to use
309 * @pages: Pointer to an array of page pointers
310 * @n_pages: Number of pages in the pages array
311 * @offset: Offset from start of the first page to the start of a buffer
312 * @size: Number of valid bytes in the buffer (after offset)
313 * @gfp_mask: GFP allocation mask
314 *
315 * Description:
316 * Allocate and initialize an sg table from a list of pages. Contiguous
317 * ranges of the pages are squashed into a single scatterlist node. A user
318 * may provide an offset at a start and a size of valid data in a buffer
319 * specified by the page array. The returned sg table is released by
320 * sg_free_table.
321 *
322 * Returns:
323 * 0 on success, negative error on failure
324 */
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)325 static inline int sg_alloc_table_from_pages(struct sg_table *sgt,
326 struct page **pages,
327 unsigned int n_pages,
328 unsigned int offset,
329 unsigned long size, gfp_t gfp_mask)
330 {
331 return sg_alloc_table_from_pages_segment(sgt, pages, n_pages, offset,
332 size, UINT_MAX, gfp_mask);
333 }
334
335 #ifdef CONFIG_SGL_ALLOC
336 struct scatterlist *sgl_alloc_order(unsigned long long length,
337 unsigned int order, bool chainable,
338 gfp_t gfp, unsigned int *nent_p);
339 struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
340 unsigned int *nent_p);
341 void sgl_free_n_order(struct scatterlist *sgl, int nents, int order);
342 void sgl_free_order(struct scatterlist *sgl, int order);
343 void sgl_free(struct scatterlist *sgl);
344 #endif /* CONFIG_SGL_ALLOC */
345
346 size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
347 size_t buflen, off_t skip, bool to_buffer);
348
349 size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
350 const void *buf, size_t buflen);
351 size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
352 void *buf, size_t buflen);
353
354 size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
355 const void *buf, size_t buflen, off_t skip);
356 size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
357 void *buf, size_t buflen, off_t skip);
358 size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
359 size_t buflen, off_t skip);
360
361 /*
362 * Maximum number of entries that will be allocated in one piece, if
363 * a list larger than this is required then chaining will be utilized.
364 */
365 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
366
367 /*
368 * The maximum number of SG segments that we will put inside a
369 * scatterlist (unless chaining is used). Should ideally fit inside a
370 * single page, to avoid a higher order allocation. We could define this
371 * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
372 * minimum value is 32
373 */
374 #define SG_CHUNK_SIZE 128
375
376 /*
377 * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
378 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
379 */
380 #ifdef CONFIG_ARCH_NO_SG_CHAIN
381 #define SG_MAX_SEGMENTS SG_CHUNK_SIZE
382 #else
383 #define SG_MAX_SEGMENTS 2048
384 #endif
385
386 #ifdef CONFIG_SG_POOL
387 void sg_free_table_chained(struct sg_table *table,
388 unsigned nents_first_chunk);
389 int sg_alloc_table_chained(struct sg_table *table, int nents,
390 struct scatterlist *first_chunk,
391 unsigned nents_first_chunk);
392 #endif
393
394 /*
395 * sg page iterator
396 *
397 * Iterates over sg entries page-by-page. On each successful iteration, you
398 * can call sg_page_iter_page(@piter) to get the current page.
399 * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to
400 * the page's page offset within the sg. The iteration will stop either when a
401 * maximum number of sg entries was reached or a terminating sg
402 * (sg_last(sg) == true) was reached.
403 */
404 struct sg_page_iter {
405 struct scatterlist *sg; /* sg holding the page */
406 unsigned int sg_pgoffset; /* page offset within the sg */
407
408 /* these are internal states, keep away */
409 unsigned int __nents; /* remaining sg entries */
410 int __pg_advance; /* nr pages to advance at the
411 * next step */
412 };
413
414 /*
415 * sg page iterator for DMA addresses
416 *
417 * This is the same as sg_page_iter however you can call
418 * sg_page_iter_dma_address(@dma_iter) to get the page's DMA
419 * address. sg_page_iter_page() cannot be called on this iterator.
420 */
421 struct sg_dma_page_iter {
422 struct sg_page_iter base;
423 };
424
425 bool __sg_page_iter_next(struct sg_page_iter *piter);
426 bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter);
427 void __sg_page_iter_start(struct sg_page_iter *piter,
428 struct scatterlist *sglist, unsigned int nents,
429 unsigned long pgoffset);
430 /**
431 * sg_page_iter_page - get the current page held by the page iterator
432 * @piter: page iterator holding the page
433 */
sg_page_iter_page(struct sg_page_iter * piter)434 static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
435 {
436 return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
437 }
438
439 /**
440 * sg_page_iter_dma_address - get the dma address of the current page held by
441 * the page iterator.
442 * @dma_iter: page iterator holding the page
443 */
444 static inline dma_addr_t
sg_page_iter_dma_address(struct sg_dma_page_iter * dma_iter)445 sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
446 {
447 return sg_dma_address(dma_iter->base.sg) +
448 (dma_iter->base.sg_pgoffset << PAGE_SHIFT);
449 }
450
451 /**
452 * for_each_sg_page - iterate over the pages of the given sg list
453 * @sglist: sglist to iterate over
454 * @piter: page iterator to hold current page, sg, sg_pgoffset
455 * @nents: maximum number of sg entries to iterate over
456 * @pgoffset: starting page offset (in pages)
457 *
458 * Callers may use sg_page_iter_page() to get each page pointer.
459 * In each loop it operates on PAGE_SIZE unit.
460 */
461 #define for_each_sg_page(sglist, piter, nents, pgoffset) \
462 for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
463 __sg_page_iter_next(piter);)
464
465 /**
466 * for_each_sg_dma_page - iterate over the pages of the given sg list
467 * @sglist: sglist to iterate over
468 * @dma_iter: DMA page iterator to hold current page
469 * @dma_nents: maximum number of sg entries to iterate over, this is the value
470 * returned from dma_map_sg
471 * @pgoffset: starting page offset (in pages)
472 *
473 * Callers may use sg_page_iter_dma_address() to get each page's DMA address.
474 * In each loop it operates on PAGE_SIZE unit.
475 */
476 #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \
477 for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \
478 pgoffset); \
479 __sg_page_iter_dma_next(dma_iter);)
480
481 /**
482 * for_each_sgtable_page - iterate over all pages in the sg_table object
483 * @sgt: sg_table object to iterate over
484 * @piter: page iterator to hold current page
485 * @pgoffset: starting page offset (in pages)
486 *
487 * Iterates over the all memory pages in the buffer described by
488 * a scatterlist stored in the given sg_table object.
489 * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit.
490 */
491 #define for_each_sgtable_page(sgt, piter, pgoffset) \
492 for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset)
493
494 /**
495 * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object
496 * @sgt: sg_table object to iterate over
497 * @dma_iter: DMA page iterator to hold current page
498 * @pgoffset: starting page offset (in pages)
499 *
500 * Iterates over the all DMA mapped pages in the buffer described by
501 * a scatterlist stored in the given sg_table object.
502 * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE
503 * unit.
504 */
505 #define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \
506 for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset)
507
508
509 /*
510 * Mapping sg iterator
511 *
512 * Iterates over sg entries mapping page-by-page. On each successful
513 * iteration, @miter->page points to the mapped page and
514 * @miter->length bytes of data can be accessed at @miter->addr. As
515 * long as an iteration is enclosed between start and stop, the user
516 * is free to choose control structure and when to stop.
517 *
518 * @miter->consumed is set to @miter->length on each iteration. It
519 * can be adjusted if the user can't consume all the bytes in one go.
520 * Also, a stopped iteration can be resumed by calling next on it.
521 * This is useful when iteration needs to release all resources and
522 * continue later (e.g. at the next interrupt).
523 */
524
525 #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
526 #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
527 #define SG_MITER_FROM_SG (1 << 2) /* nop */
528
529 struct sg_mapping_iter {
530 /* the following three fields can be accessed directly */
531 struct page *page; /* currently mapped page */
532 void *addr; /* pointer to the mapped area */
533 size_t length; /* length of the mapped area */
534 size_t consumed; /* number of consumed bytes */
535 struct sg_page_iter piter; /* page iterator */
536
537 /* these are internal states, keep away */
538 unsigned int __offset; /* offset within page */
539 unsigned int __remaining; /* remaining bytes on page */
540 unsigned int __flags;
541 };
542
543 void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
544 unsigned int nents, unsigned int flags);
545 bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
546 bool sg_miter_next(struct sg_mapping_iter *miter);
547 void sg_miter_stop(struct sg_mapping_iter *miter);
548
549 #endif /* _LINUX_SCATTERLIST_H */
550