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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | #ifndef _LINUX_SCATTERLIST_H |
3 | #define _LINUX_SCATTERLIST_H | |
4 | ||
187f1882 | 5 | #include <linux/string.h> |
84be456f | 6 | #include <linux/types.h> |
187f1882 PG |
7 | #include <linux/bug.h> |
8 | #include <linux/mm.h> | |
18dabf47 JA |
9 | #include <asm/io.h> |
10 | ||
84be456f CH |
11 | struct scatterlist { |
12 | #ifdef CONFIG_DEBUG_SG | |
13 | unsigned long sg_magic; | |
14 | #endif | |
15 | unsigned long page_link; | |
16 | unsigned int offset; | |
17 | unsigned int length; | |
18 | dma_addr_t dma_address; | |
19 | #ifdef CONFIG_NEED_SG_DMA_LENGTH | |
20 | unsigned int dma_length; | |
21 | #endif | |
22 | }; | |
23 | ||
c125906b TU |
24 | /* |
25 | * Since the above length field is an unsigned int, below we define the maximum | |
26 | * length in bytes that can be stored in one scatterlist entry. | |
27 | */ | |
28 | #define SCATTERLIST_MAX_SEGMENT (UINT_MAX & PAGE_MASK) | |
29 | ||
84be456f CH |
30 | /* |
31 | * These macros should be used after a dma_map_sg call has been done | |
32 | * to get bus addresses of each of the SG entries and their lengths. | |
33 | * You should only work with the number of sg entries dma_map_sg | |
34 | * returns, or alternatively stop on the first sg_dma_len(sg) which | |
35 | * is 0. | |
36 | */ | |
37 | #define sg_dma_address(sg) ((sg)->dma_address) | |
38 | ||
39 | #ifdef CONFIG_NEED_SG_DMA_LENGTH | |
40 | #define sg_dma_len(sg) ((sg)->dma_length) | |
41 | #else | |
42 | #define sg_dma_len(sg) ((sg)->length) | |
43 | #endif | |
44 | ||
0db9299f JA |
45 | struct sg_table { |
46 | struct scatterlist *sgl; /* the list */ | |
47 | unsigned int nents; /* number of mapped entries */ | |
48 | unsigned int orig_nents; /* original size of list */ | |
49 | }; | |
50 | ||
18dabf47 JA |
51 | /* |
52 | * Notes on SG table design. | |
53 | * | |
84be456f CH |
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. | |
18dabf47 JA |
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 | */ | |
1da177e4 | 66 | |
d6ec0842 JA |
67 | #define SG_MAGIC 0x87654321 |
68 | ||
645a8d94 TH |
69 | /* |
70 | * We overload the LSB of the page pointer to indicate whether it's | |
71 | * a valid sg entry, or whether it points to the start of a new scatterlist. | |
72 | * Those low bits are there for everyone! (thanks mason :-) | |
73 | */ | |
74 | #define sg_is_chain(sg) ((sg)->page_link & 0x01) | |
75 | #define sg_is_last(sg) ((sg)->page_link & 0x02) | |
76 | #define sg_chain_ptr(sg) \ | |
77 | ((struct scatterlist *) ((sg)->page_link & ~0x03)) | |
78 | ||
82f66fbe | 79 | /** |
642f1490 JA |
80 | * sg_assign_page - Assign a given page to an SG entry |
81 | * @sg: SG entry | |
82 | * @page: The page | |
82f66fbe JA |
83 | * |
84 | * Description: | |
642f1490 JA |
85 | * Assign page to sg entry. Also see sg_set_page(), the most commonly used |
86 | * variant. | |
82f66fbe JA |
87 | * |
88 | **/ | |
642f1490 | 89 | static inline void sg_assign_page(struct scatterlist *sg, struct page *page) |
82f66fbe | 90 | { |
18dabf47 JA |
91 | unsigned long page_link = sg->page_link & 0x3; |
92 | ||
de26103d JA |
93 | /* |
94 | * In order for the low bit stealing approach to work, pages | |
95 | * must be aligned at a 32-bit boundary as a minimum. | |
96 | */ | |
97 | BUG_ON((unsigned long) page & 0x03); | |
d6ec0842 JA |
98 | #ifdef CONFIG_DEBUG_SG |
99 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
645a8d94 | 100 | BUG_ON(sg_is_chain(sg)); |
d6ec0842 | 101 | #endif |
18dabf47 | 102 | sg->page_link = page_link | (unsigned long) page; |
82f66fbe JA |
103 | } |
104 | ||
642f1490 JA |
105 | /** |
106 | * sg_set_page - Set sg entry to point at given page | |
107 | * @sg: SG entry | |
108 | * @page: The page | |
109 | * @len: Length of data | |
110 | * @offset: Offset into page | |
111 | * | |
112 | * Description: | |
113 | * Use this function to set an sg entry pointing at a page, never assign | |
114 | * the page directly. We encode sg table information in the lower bits | |
115 | * of the page pointer. See sg_page() for looking up the page belonging | |
116 | * to an sg entry. | |
117 | * | |
118 | **/ | |
119 | static inline void sg_set_page(struct scatterlist *sg, struct page *page, | |
120 | unsigned int len, unsigned int offset) | |
121 | { | |
122 | sg_assign_page(sg, page); | |
123 | sg->offset = offset; | |
124 | sg->length = len; | |
125 | } | |
126 | ||
645a8d94 TH |
127 | static inline struct page *sg_page(struct scatterlist *sg) |
128 | { | |
129 | #ifdef CONFIG_DEBUG_SG | |
130 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
131 | BUG_ON(sg_is_chain(sg)); | |
132 | #endif | |
133 | return (struct page *)((sg)->page_link & ~0x3); | |
134 | } | |
82f66fbe | 135 | |
18dabf47 JA |
136 | /** |
137 | * sg_set_buf - Set sg entry to point at given data | |
138 | * @sg: SG entry | |
139 | * @buf: Data | |
140 | * @buflen: Data length | |
141 | * | |
142 | **/ | |
03fd9cee | 143 | static inline void sg_set_buf(struct scatterlist *sg, const void *buf, |
d32311fe HX |
144 | unsigned int buflen) |
145 | { | |
ac4e97ab RR |
146 | #ifdef CONFIG_DEBUG_SG |
147 | BUG_ON(!virt_addr_valid(buf)); | |
148 | #endif | |
642f1490 | 149 | sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); |
1da177e4 LT |
150 | } |
151 | ||
96b418c9 JA |
152 | /* |
153 | * Loop over each sg element, following the pointer to a new list if necessary | |
154 | */ | |
155 | #define for_each_sg(sglist, sg, nr, __i) \ | |
156 | for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) | |
157 | ||
70eb8040 JA |
158 | /** |
159 | * sg_chain - Chain two sglists together | |
160 | * @prv: First scatterlist | |
161 | * @prv_nents: Number of entries in prv | |
162 | * @sgl: Second scatterlist | |
163 | * | |
18dabf47 JA |
164 | * Description: |
165 | * Links @prv@ and @sgl@ together, to form a longer scatterlist. | |
70eb8040 | 166 | * |
18dabf47 | 167 | **/ |
70eb8040 JA |
168 | static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, |
169 | struct scatterlist *sgl) | |
170 | { | |
645a8d94 TH |
171 | /* |
172 | * offset and length are unused for chain entry. Clear them. | |
173 | */ | |
b801a1e7 RR |
174 | prv[prv_nents - 1].offset = 0; |
175 | prv[prv_nents - 1].length = 0; | |
645a8d94 | 176 | |
73fd546a JA |
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 | prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02; | |
70eb8040 JA |
182 | } |
183 | ||
82f66fbe JA |
184 | /** |
185 | * sg_mark_end - Mark the end of the scatterlist | |
c46f2334 | 186 | * @sg: SG entryScatterlist |
82f66fbe JA |
187 | * |
188 | * Description: | |
c46f2334 JA |
189 | * Marks the passed in sg entry as the termination point for the sg |
190 | * table. A call to sg_next() on this entry will return NULL. | |
82f66fbe JA |
191 | * |
192 | **/ | |
c46f2334 | 193 | static inline void sg_mark_end(struct scatterlist *sg) |
82f66fbe | 194 | { |
c46f2334 JA |
195 | #ifdef CONFIG_DEBUG_SG |
196 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
197 | #endif | |
198 | /* | |
199 | * Set termination bit, clear potential chain bit | |
200 | */ | |
18dabf47 | 201 | sg->page_link |= 0x02; |
c46f2334 | 202 | sg->page_link &= ~0x01; |
82f66fbe JA |
203 | } |
204 | ||
c8164d89 PB |
205 | /** |
206 | * sg_unmark_end - Undo setting the end of the scatterlist | |
207 | * @sg: SG entryScatterlist | |
208 | * | |
209 | * Description: | |
210 | * Removes the termination marker from the given entry of the scatterlist. | |
211 | * | |
212 | **/ | |
213 | static inline void sg_unmark_end(struct scatterlist *sg) | |
214 | { | |
215 | #ifdef CONFIG_DEBUG_SG | |
216 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
217 | #endif | |
218 | sg->page_link &= ~0x02; | |
219 | } | |
220 | ||
82f66fbe JA |
221 | /** |
222 | * sg_phys - Return physical address of an sg entry | |
223 | * @sg: SG entry | |
224 | * | |
225 | * Description: | |
226 | * This calls page_to_phys() on the page in this sg entry, and adds the | |
227 | * sg offset. The caller must know that it is legal to call page_to_phys() | |
228 | * on the sg page. | |
229 | * | |
230 | **/ | |
85cdffcd | 231 | static inline dma_addr_t sg_phys(struct scatterlist *sg) |
82f66fbe JA |
232 | { |
233 | return page_to_phys(sg_page(sg)) + sg->offset; | |
234 | } | |
235 | ||
236 | /** | |
237 | * sg_virt - Return virtual address of an sg entry | |
18dabf47 | 238 | * @sg: SG entry |
82f66fbe JA |
239 | * |
240 | * Description: | |
241 | * This calls page_address() on the page in this sg entry, and adds the | |
242 | * sg offset. The caller must know that the sg page has a valid virtual | |
243 | * mapping. | |
244 | * | |
245 | **/ | |
246 | static inline void *sg_virt(struct scatterlist *sg) | |
247 | { | |
248 | return page_address(sg_page(sg)) + sg->offset; | |
249 | } | |
250 | ||
2e484610 | 251 | int sg_nents(struct scatterlist *sg); |
cfaed10d | 252 | int sg_nents_for_len(struct scatterlist *sg, u64 len); |
0db9299f JA |
253 | struct scatterlist *sg_next(struct scatterlist *); |
254 | struct scatterlist *sg_last(struct scatterlist *s, unsigned int); | |
255 | void sg_init_table(struct scatterlist *, unsigned int); | |
256 | void sg_init_one(struct scatterlist *, const void *, unsigned int); | |
f8bcbe62 RJ |
257 | int sg_split(struct scatterlist *in, const int in_mapped_nents, |
258 | const off_t skip, const int nb_splits, | |
259 | const size_t *split_sizes, | |
260 | struct scatterlist **out, int *out_mapped_nents, | |
261 | gfp_t gfp_mask); | |
0db9299f JA |
262 | |
263 | typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); | |
264 | typedef void (sg_free_fn)(struct scatterlist *, unsigned int); | |
265 | ||
c53c6d6a | 266 | void __sg_free_table(struct sg_table *, unsigned int, bool, sg_free_fn *); |
0db9299f | 267 | void sg_free_table(struct sg_table *); |
c53c6d6a CH |
268 | int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, |
269 | struct scatterlist *, gfp_t, sg_alloc_fn *); | |
0db9299f | 270 | int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); |
89d8589c TU |
271 | int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, |
272 | unsigned int n_pages, unsigned int offset, | |
273 | unsigned long size, unsigned int max_segment, | |
274 | gfp_t gfp_mask); | |
275 | int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, | |
276 | unsigned int n_pages, unsigned int offset, | |
277 | unsigned long size, gfp_t gfp_mask); | |
0db9299f | 278 | |
2b08897b BVA |
279 | #ifdef CONFIG_SGL_ALLOC |
280 | struct scatterlist *sgl_alloc_order(unsigned long long length, | |
281 | unsigned int order, bool chainable, | |
282 | gfp_t gfp, unsigned int *nent_p); | |
283 | struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, | |
284 | unsigned int *nent_p); | |
285 | void sgl_free_order(struct scatterlist *sgl, int order); | |
286 | void sgl_free(struct scatterlist *sgl); | |
287 | #endif /* CONFIG_SGL_ALLOC */ | |
288 | ||
386ecb12 DG |
289 | size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, |
290 | size_t buflen, off_t skip, bool to_buffer); | |
291 | ||
b1adaf65 | 292 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
2a1bf8f9 | 293 | const void *buf, size_t buflen); |
b1adaf65 FT |
294 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, |
295 | void *buf, size_t buflen); | |
296 | ||
df642cea | 297 | size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, |
2a1bf8f9 | 298 | const void *buf, size_t buflen, off_t skip); |
df642cea AM |
299 | size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, |
300 | void *buf, size_t buflen, off_t skip); | |
0945e569 JT |
301 | size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, |
302 | size_t buflen, off_t skip); | |
df642cea | 303 | |
0db9299f JA |
304 | /* |
305 | * Maximum number of entries that will be allocated in one piece, if | |
306 | * a list larger than this is required then chaining will be utilized. | |
307 | */ | |
308 | #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) | |
309 | ||
9b1d6c89 ML |
310 | /* |
311 | * The maximum number of SG segments that we will put inside a | |
312 | * scatterlist (unless chaining is used). Should ideally fit inside a | |
313 | * single page, to avoid a higher order allocation. We could define this | |
314 | * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The | |
315 | * minimum value is 32 | |
316 | */ | |
317 | #define SG_CHUNK_SIZE 128 | |
318 | ||
319 | /* | |
320 | * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit | |
321 | * is totally arbitrary, a setting of 2048 will get you at least 8mb ios. | |
322 | */ | |
323 | #ifdef CONFIG_ARCH_HAS_SG_CHAIN | |
324 | #define SG_MAX_SEGMENTS 2048 | |
325 | #else | |
326 | #define SG_MAX_SEGMENTS SG_CHUNK_SIZE | |
327 | #endif | |
328 | ||
329 | #ifdef CONFIG_SG_POOL | |
330 | void sg_free_table_chained(struct sg_table *table, bool first_chunk); | |
331 | int sg_alloc_table_chained(struct sg_table *table, int nents, | |
332 | struct scatterlist *first_chunk); | |
333 | #endif | |
334 | ||
a321e91b ID |
335 | /* |
336 | * sg page iterator | |
337 | * | |
338 | * Iterates over sg entries page-by-page. On each successful iteration, | |
2db76d7c ID |
339 | * you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter) |
340 | * to get the current page and its dma address. @piter->sg will point to the | |
341 | * sg holding this page and @piter->sg_pgoffset to the page's page offset | |
342 | * within the sg. The iteration will stop either when a maximum number of sg | |
343 | * entries was reached or a terminating sg (sg_last(sg) == true) was reached. | |
a321e91b ID |
344 | */ |
345 | struct sg_page_iter { | |
a321e91b ID |
346 | struct scatterlist *sg; /* sg holding the page */ |
347 | unsigned int sg_pgoffset; /* page offset within the sg */ | |
348 | ||
349 | /* these are internal states, keep away */ | |
350 | unsigned int __nents; /* remaining sg entries */ | |
351 | int __pg_advance; /* nr pages to advance at the | |
352 | * next step */ | |
353 | }; | |
354 | ||
355 | bool __sg_page_iter_next(struct sg_page_iter *piter); | |
356 | void __sg_page_iter_start(struct sg_page_iter *piter, | |
357 | struct scatterlist *sglist, unsigned int nents, | |
358 | unsigned long pgoffset); | |
2db76d7c ID |
359 | /** |
360 | * sg_page_iter_page - get the current page held by the page iterator | |
361 | * @piter: page iterator holding the page | |
362 | */ | |
363 | static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) | |
364 | { | |
365 | return nth_page(sg_page(piter->sg), piter->sg_pgoffset); | |
366 | } | |
367 | ||
368 | /** | |
369 | * sg_page_iter_dma_address - get the dma address of the current page held by | |
370 | * the page iterator. | |
371 | * @piter: page iterator holding the page | |
372 | */ | |
373 | static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter) | |
374 | { | |
375 | return sg_dma_address(piter->sg) + (piter->sg_pgoffset << PAGE_SHIFT); | |
376 | } | |
a321e91b ID |
377 | |
378 | /** | |
379 | * for_each_sg_page - iterate over the pages of the given sg list | |
380 | * @sglist: sglist to iterate over | |
381 | * @piter: page iterator to hold current page, sg, sg_pgoffset | |
382 | * @nents: maximum number of sg entries to iterate over | |
383 | * @pgoffset: starting page offset | |
384 | */ | |
385 | #define for_each_sg_page(sglist, piter, nents, pgoffset) \ | |
386 | for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \ | |
387 | __sg_page_iter_next(piter);) | |
137d3edb TH |
388 | |
389 | /* | |
390 | * Mapping sg iterator | |
391 | * | |
392 | * Iterates over sg entries mapping page-by-page. On each successful | |
393 | * iteration, @miter->page points to the mapped page and | |
394 | * @miter->length bytes of data can be accessed at @miter->addr. As | |
395 | * long as an interation is enclosed between start and stop, the user | |
396 | * is free to choose control structure and when to stop. | |
397 | * | |
398 | * @miter->consumed is set to @miter->length on each iteration. It | |
399 | * can be adjusted if the user can't consume all the bytes in one go. | |
400 | * Also, a stopped iteration can be resumed by calling next on it. | |
401 | * This is useful when iteration needs to release all resources and | |
402 | * continue later (e.g. at the next interrupt). | |
403 | */ | |
404 | ||
405 | #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ | |
6de7e356 SAS |
406 | #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */ |
407 | #define SG_MITER_FROM_SG (1 << 2) /* nop */ | |
137d3edb TH |
408 | |
409 | struct sg_mapping_iter { | |
410 | /* the following three fields can be accessed directly */ | |
411 | struct page *page; /* currently mapped page */ | |
412 | void *addr; /* pointer to the mapped area */ | |
413 | size_t length; /* length of the mapped area */ | |
414 | size_t consumed; /* number of consumed bytes */ | |
4225fc85 | 415 | struct sg_page_iter piter; /* page iterator */ |
137d3edb TH |
416 | |
417 | /* these are internal states, keep away */ | |
4225fc85 ID |
418 | unsigned int __offset; /* offset within page */ |
419 | unsigned int __remaining; /* remaining bytes on page */ | |
137d3edb TH |
420 | unsigned int __flags; |
421 | }; | |
422 | ||
423 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, | |
424 | unsigned int nents, unsigned int flags); | |
0d6077f8 | 425 | bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset); |
137d3edb TH |
426 | bool sg_miter_next(struct sg_mapping_iter *miter); |
427 | void sg_miter_stop(struct sg_mapping_iter *miter); | |
428 | ||
1da177e4 | 429 | #endif /* _LINUX_SCATTERLIST_H */ |