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1 | #ifndef _LINUX_SCATTERLIST_H | |
2 | #define _LINUX_SCATTERLIST_H | |
3 | ||
4 | #include <linux/string.h> | |
5 | #include <linux/types.h> | |
6 | #include <linux/bug.h> | |
7 | #include <linux/mm.h> | |
8 | #include <asm/io.h> | |
9 | ||
10 | struct scatterlist { | |
11 | #ifdef CONFIG_DEBUG_SG | |
12 | unsigned long sg_magic; | |
13 | #endif | |
14 | unsigned long page_link; | |
15 | unsigned int offset; | |
16 | unsigned int length; | |
17 | dma_addr_t dma_address; | |
18 | #ifdef CONFIG_NEED_SG_DMA_LENGTH | |
19 | unsigned int dma_length; | |
20 | #endif | |
21 | }; | |
22 | ||
23 | /* | |
24 | * These macros should be used after a dma_map_sg call has been done | |
25 | * to get bus addresses of each of the SG entries and their lengths. | |
26 | * You should only work with the number of sg entries dma_map_sg | |
27 | * returns, or alternatively stop on the first sg_dma_len(sg) which | |
28 | * is 0. | |
29 | */ | |
30 | #define sg_dma_address(sg) ((sg)->dma_address) | |
31 | ||
32 | #ifdef CONFIG_NEED_SG_DMA_LENGTH | |
33 | #define sg_dma_len(sg) ((sg)->dma_length) | |
34 | #else | |
35 | #define sg_dma_len(sg) ((sg)->length) | |
36 | #endif | |
37 | ||
38 | struct sg_table { | |
39 | struct scatterlist *sgl; /* the list */ | |
40 | unsigned int nents; /* number of mapped entries */ | |
41 | unsigned int orig_nents; /* original size of list */ | |
42 | }; | |
43 | ||
44 | /* | |
45 | * Notes on SG table design. | |
46 | * | |
47 | * We use the unsigned long page_link field in the scatterlist struct to place | |
48 | * the page pointer AND encode information about the sg table as well. The two | |
49 | * lower bits are reserved for this information. | |
50 | * | |
51 | * If bit 0 is set, then the page_link contains a pointer to the next sg | |
52 | * table list. Otherwise the next entry is at sg + 1. | |
53 | * | |
54 | * If bit 1 is set, then this sg entry is the last element in a list. | |
55 | * | |
56 | * See sg_next(). | |
57 | * | |
58 | */ | |
59 | ||
60 | #define SG_MAGIC 0x87654321 | |
61 | ||
62 | /* | |
63 | * We overload the LSB of the page pointer to indicate whether it's | |
64 | * a valid sg entry, or whether it points to the start of a new scatterlist. | |
65 | * Those low bits are there for everyone! (thanks mason :-) | |
66 | */ | |
67 | #define sg_is_chain(sg) ((sg)->page_link & 0x01) | |
68 | #define sg_is_last(sg) ((sg)->page_link & 0x02) | |
69 | #define sg_chain_ptr(sg) \ | |
70 | ((struct scatterlist *) ((sg)->page_link & ~0x03)) | |
71 | ||
72 | /** | |
73 | * sg_assign_page - Assign a given page to an SG entry | |
74 | * @sg: SG entry | |
75 | * @page: The page | |
76 | * | |
77 | * Description: | |
78 | * Assign page to sg entry. Also see sg_set_page(), the most commonly used | |
79 | * variant. | |
80 | * | |
81 | **/ | |
82 | static inline void sg_assign_page(struct scatterlist *sg, struct page *page) | |
83 | { | |
84 | unsigned long page_link = sg->page_link & 0x3; | |
85 | ||
86 | /* | |
87 | * In order for the low bit stealing approach to work, pages | |
88 | * must be aligned at a 32-bit boundary as a minimum. | |
89 | */ | |
90 | BUG_ON((unsigned long) page & 0x03); | |
91 | #ifdef CONFIG_DEBUG_SG | |
92 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
93 | BUG_ON(sg_is_chain(sg)); | |
94 | #endif | |
95 | sg->page_link = page_link | (unsigned long) page; | |
96 | } | |
97 | ||
98 | /** | |
99 | * sg_set_page - Set sg entry to point at given page | |
100 | * @sg: SG entry | |
101 | * @page: The page | |
102 | * @len: Length of data | |
103 | * @offset: Offset into page | |
104 | * | |
105 | * Description: | |
106 | * Use this function to set an sg entry pointing at a page, never assign | |
107 | * the page directly. We encode sg table information in the lower bits | |
108 | * of the page pointer. See sg_page() for looking up the page belonging | |
109 | * to an sg entry. | |
110 | * | |
111 | **/ | |
112 | static inline void sg_set_page(struct scatterlist *sg, struct page *page, | |
113 | unsigned int len, unsigned int offset) | |
114 | { | |
115 | sg_assign_page(sg, page); | |
116 | sg->offset = offset; | |
117 | sg->length = len; | |
118 | } | |
119 | ||
120 | static inline struct page *sg_page(struct scatterlist *sg) | |
121 | { | |
122 | #ifdef CONFIG_DEBUG_SG | |
123 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
124 | BUG_ON(sg_is_chain(sg)); | |
125 | #endif | |
126 | return (struct page *)((sg)->page_link & ~0x3); | |
127 | } | |
128 | ||
129 | /** | |
130 | * sg_set_buf - Set sg entry to point at given data | |
131 | * @sg: SG entry | |
132 | * @buf: Data | |
133 | * @buflen: Data length | |
134 | * | |
135 | **/ | |
136 | static inline void sg_set_buf(struct scatterlist *sg, const void *buf, | |
137 | unsigned int buflen) | |
138 | { | |
139 | #ifdef CONFIG_DEBUG_SG | |
140 | BUG_ON(!virt_addr_valid(buf)); | |
141 | #endif | |
142 | sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); | |
143 | } | |
144 | ||
145 | /* | |
146 | * Loop over each sg element, following the pointer to a new list if necessary | |
147 | */ | |
148 | #define for_each_sg(sglist, sg, nr, __i) \ | |
149 | for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) | |
150 | ||
151 | /** | |
152 | * sg_chain - Chain two sglists together | |
153 | * @prv: First scatterlist | |
154 | * @prv_nents: Number of entries in prv | |
155 | * @sgl: Second scatterlist | |
156 | * | |
157 | * Description: | |
158 | * Links @prv@ and @sgl@ together, to form a longer scatterlist. | |
159 | * | |
160 | **/ | |
161 | static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, | |
162 | struct scatterlist *sgl) | |
163 | { | |
164 | /* | |
165 | * offset and length are unused for chain entry. Clear them. | |
166 | */ | |
167 | prv[prv_nents - 1].offset = 0; | |
168 | prv[prv_nents - 1].length = 0; | |
169 | ||
170 | /* | |
171 | * Set lowest bit to indicate a link pointer, and make sure to clear | |
172 | * the termination bit if it happens to be set. | |
173 | */ | |
174 | prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02; | |
175 | } | |
176 | ||
177 | /** | |
178 | * sg_mark_end - Mark the end of the scatterlist | |
179 | * @sg: SG entryScatterlist | |
180 | * | |
181 | * Description: | |
182 | * Marks the passed in sg entry as the termination point for the sg | |
183 | * table. A call to sg_next() on this entry will return NULL. | |
184 | * | |
185 | **/ | |
186 | static inline void sg_mark_end(struct scatterlist *sg) | |
187 | { | |
188 | #ifdef CONFIG_DEBUG_SG | |
189 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
190 | #endif | |
191 | /* | |
192 | * Set termination bit, clear potential chain bit | |
193 | */ | |
194 | sg->page_link |= 0x02; | |
195 | sg->page_link &= ~0x01; | |
196 | } | |
197 | ||
198 | /** | |
199 | * sg_unmark_end - Undo setting the end of the scatterlist | |
200 | * @sg: SG entryScatterlist | |
201 | * | |
202 | * Description: | |
203 | * Removes the termination marker from the given entry of the scatterlist. | |
204 | * | |
205 | **/ | |
206 | static inline void sg_unmark_end(struct scatterlist *sg) | |
207 | { | |
208 | #ifdef CONFIG_DEBUG_SG | |
209 | BUG_ON(sg->sg_magic != SG_MAGIC); | |
210 | #endif | |
211 | sg->page_link &= ~0x02; | |
212 | } | |
213 | ||
214 | /** | |
215 | * sg_phys - Return physical address of an sg entry | |
216 | * @sg: SG entry | |
217 | * | |
218 | * Description: | |
219 | * This calls page_to_phys() on the page in this sg entry, and adds the | |
220 | * sg offset. The caller must know that it is legal to call page_to_phys() | |
221 | * on the sg page. | |
222 | * | |
223 | **/ | |
224 | static inline dma_addr_t sg_phys(struct scatterlist *sg) | |
225 | { | |
226 | return page_to_phys(sg_page(sg)) + sg->offset; | |
227 | } | |
228 | ||
229 | /** | |
230 | * sg_virt - Return virtual address of an sg entry | |
231 | * @sg: SG entry | |
232 | * | |
233 | * Description: | |
234 | * This calls page_address() on the page in this sg entry, and adds the | |
235 | * sg offset. The caller must know that the sg page has a valid virtual | |
236 | * mapping. | |
237 | * | |
238 | **/ | |
239 | static inline void *sg_virt(struct scatterlist *sg) | |
240 | { | |
241 | return page_address(sg_page(sg)) + sg->offset; | |
242 | } | |
243 | ||
244 | int sg_nents(struct scatterlist *sg); | |
245 | int sg_nents_for_len(struct scatterlist *sg, u64 len); | |
246 | struct scatterlist *sg_next(struct scatterlist *); | |
247 | struct scatterlist *sg_last(struct scatterlist *s, unsigned int); | |
248 | void sg_init_table(struct scatterlist *, unsigned int); | |
249 | void sg_init_one(struct scatterlist *, const void *, unsigned int); | |
250 | int sg_split(struct scatterlist *in, const int in_mapped_nents, | |
251 | const off_t skip, const int nb_splits, | |
252 | const size_t *split_sizes, | |
253 | struct scatterlist **out, int *out_mapped_nents, | |
254 | gfp_t gfp_mask); | |
255 | ||
256 | typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); | |
257 | typedef void (sg_free_fn)(struct scatterlist *, unsigned int); | |
258 | ||
259 | void __sg_free_table(struct sg_table *, unsigned int, bool, sg_free_fn *); | |
260 | void sg_free_table(struct sg_table *); | |
261 | int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, | |
262 | struct scatterlist *, gfp_t, sg_alloc_fn *); | |
263 | int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); | |
264 | int sg_alloc_table_from_pages(struct sg_table *sgt, | |
265 | struct page **pages, unsigned int n_pages, | |
266 | unsigned long offset, unsigned long size, | |
267 | gfp_t gfp_mask); | |
268 | ||
269 | size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, | |
270 | size_t buflen, off_t skip, bool to_buffer); | |
271 | ||
272 | size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
273 | const void *buf, size_t buflen); | |
274 | size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
275 | void *buf, size_t buflen); | |
276 | ||
277 | size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, | |
278 | const void *buf, size_t buflen, off_t skip); | |
279 | size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, | |
280 | void *buf, size_t buflen, off_t skip); | |
281 | size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, | |
282 | size_t buflen, off_t skip); | |
283 | ||
284 | /* | |
285 | * Maximum number of entries that will be allocated in one piece, if | |
286 | * a list larger than this is required then chaining will be utilized. | |
287 | */ | |
288 | #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) | |
289 | ||
290 | /* | |
291 | * The maximum number of SG segments that we will put inside a | |
292 | * scatterlist (unless chaining is used). Should ideally fit inside a | |
293 | * single page, to avoid a higher order allocation. We could define this | |
294 | * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The | |
295 | * minimum value is 32 | |
296 | */ | |
297 | #define SG_CHUNK_SIZE 128 | |
298 | ||
299 | /* | |
300 | * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit | |
301 | * is totally arbitrary, a setting of 2048 will get you at least 8mb ios. | |
302 | */ | |
303 | #ifdef CONFIG_ARCH_HAS_SG_CHAIN | |
304 | #define SG_MAX_SEGMENTS 2048 | |
305 | #else | |
306 | #define SG_MAX_SEGMENTS SG_CHUNK_SIZE | |
307 | #endif | |
308 | ||
309 | #ifdef CONFIG_SG_POOL | |
310 | void sg_free_table_chained(struct sg_table *table, bool first_chunk); | |
311 | int sg_alloc_table_chained(struct sg_table *table, int nents, | |
312 | struct scatterlist *first_chunk); | |
313 | #endif | |
314 | ||
315 | /* | |
316 | * sg page iterator | |
317 | * | |
318 | * Iterates over sg entries page-by-page. On each successful iteration, | |
319 | * you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter) | |
320 | * to get the current page and its dma address. @piter->sg will point to the | |
321 | * sg holding this page and @piter->sg_pgoffset to the page's page offset | |
322 | * within the sg. The iteration will stop either when a maximum number of sg | |
323 | * entries was reached or a terminating sg (sg_last(sg) == true) was reached. | |
324 | */ | |
325 | struct sg_page_iter { | |
326 | struct scatterlist *sg; /* sg holding the page */ | |
327 | unsigned int sg_pgoffset; /* page offset within the sg */ | |
328 | ||
329 | /* these are internal states, keep away */ | |
330 | unsigned int __nents; /* remaining sg entries */ | |
331 | int __pg_advance; /* nr pages to advance at the | |
332 | * next step */ | |
333 | }; | |
334 | ||
335 | bool __sg_page_iter_next(struct sg_page_iter *piter); | |
336 | void __sg_page_iter_start(struct sg_page_iter *piter, | |
337 | struct scatterlist *sglist, unsigned int nents, | |
338 | unsigned long pgoffset); | |
339 | /** | |
340 | * sg_page_iter_page - get the current page held by the page iterator | |
341 | * @piter: page iterator holding the page | |
342 | */ | |
343 | static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) | |
344 | { | |
345 | return nth_page(sg_page(piter->sg), piter->sg_pgoffset); | |
346 | } | |
347 | ||
348 | /** | |
349 | * sg_page_iter_dma_address - get the dma address of the current page held by | |
350 | * the page iterator. | |
351 | * @piter: page iterator holding the page | |
352 | */ | |
353 | static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter) | |
354 | { | |
355 | return sg_dma_address(piter->sg) + (piter->sg_pgoffset << PAGE_SHIFT); | |
356 | } | |
357 | ||
358 | /** | |
359 | * for_each_sg_page - iterate over the pages of the given sg list | |
360 | * @sglist: sglist to iterate over | |
361 | * @piter: page iterator to hold current page, sg, sg_pgoffset | |
362 | * @nents: maximum number of sg entries to iterate over | |
363 | * @pgoffset: starting page offset | |
364 | */ | |
365 | #define for_each_sg_page(sglist, piter, nents, pgoffset) \ | |
366 | for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \ | |
367 | __sg_page_iter_next(piter);) | |
368 | ||
369 | /* | |
370 | * Mapping sg iterator | |
371 | * | |
372 | * Iterates over sg entries mapping page-by-page. On each successful | |
373 | * iteration, @miter->page points to the mapped page and | |
374 | * @miter->length bytes of data can be accessed at @miter->addr. As | |
375 | * long as an interation is enclosed between start and stop, the user | |
376 | * is free to choose control structure and when to stop. | |
377 | * | |
378 | * @miter->consumed is set to @miter->length on each iteration. It | |
379 | * can be adjusted if the user can't consume all the bytes in one go. | |
380 | * Also, a stopped iteration can be resumed by calling next on it. | |
381 | * This is useful when iteration needs to release all resources and | |
382 | * continue later (e.g. at the next interrupt). | |
383 | */ | |
384 | ||
385 | #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ | |
386 | #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */ | |
387 | #define SG_MITER_FROM_SG (1 << 2) /* nop */ | |
388 | ||
389 | struct sg_mapping_iter { | |
390 | /* the following three fields can be accessed directly */ | |
391 | struct page *page; /* currently mapped page */ | |
392 | void *addr; /* pointer to the mapped area */ | |
393 | size_t length; /* length of the mapped area */ | |
394 | size_t consumed; /* number of consumed bytes */ | |
395 | struct sg_page_iter piter; /* page iterator */ | |
396 | ||
397 | /* these are internal states, keep away */ | |
398 | unsigned int __offset; /* offset within page */ | |
399 | unsigned int __remaining; /* remaining bytes on page */ | |
400 | unsigned int __flags; | |
401 | }; | |
402 | ||
403 | void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, | |
404 | unsigned int nents, unsigned int flags); | |
405 | bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset); | |
406 | bool sg_miter_next(struct sg_mapping_iter *miter); | |
407 | void sg_miter_stop(struct sg_mapping_iter *miter); | |
408 | ||
409 | #endif /* _LINUX_SCATTERLIST_H */ |