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 #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 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 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 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 51 /* 52 * Notes on SG table design. 53 * 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. 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 */ 66 67 #define SG_MAGIC 0x87654321 68 #define SG_CHAIN 0x01UL 69 #define SG_END 0x02UL 70 71 /* 72 * We overload the LSB of the page pointer to indicate whether it's 73 * a valid sg entry, or whether it points to the start of a new scatterlist. 74 * Those low bits are there for everyone! (thanks mason :-) 75 */ 76 #define sg_is_chain(sg) ((sg)->page_link & SG_CHAIN) 77 #define sg_is_last(sg) ((sg)->page_link & SG_END) 78 #define sg_chain_ptr(sg) \ 79 ((struct scatterlist *) ((sg)->page_link & ~(SG_CHAIN | SG_END))) 80 81 /** 82 * sg_assign_page - Assign a given page to an SG entry 83 * @sg: SG entry 84 * @page: The page 85 * 86 * Description: 87 * Assign page to sg entry. Also see sg_set_page(), the most commonly used 88 * variant. 89 * 90 **/ 91 static inline void sg_assign_page(struct scatterlist *sg, struct page *page) 92 { 93 unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END); 94 95 /* 96 * In order for the low bit stealing approach to work, pages 97 * must be aligned at a 32-bit boundary as a minimum. 98 */ 99 BUG_ON((unsigned long) page & (SG_CHAIN | SG_END)); 100 #ifdef CONFIG_DEBUG_SG 101 BUG_ON(sg->sg_magic != SG_MAGIC); 102 BUG_ON(sg_is_chain(sg)); 103 #endif 104 sg->page_link = page_link | (unsigned long) page; 105 } 106 107 /** 108 * sg_set_page - Set sg entry to point at given page 109 * @sg: SG entry 110 * @page: The page 111 * @len: Length of data 112 * @offset: Offset into page 113 * 114 * Description: 115 * Use this function to set an sg entry pointing at a page, never assign 116 * the page directly. We encode sg table information in the lower bits 117 * of the page pointer. See sg_page() for looking up the page belonging 118 * to an sg entry. 119 * 120 **/ 121 static inline void sg_set_page(struct scatterlist *sg, struct page *page, 122 unsigned int len, unsigned int offset) 123 { 124 sg_assign_page(sg, page); 125 sg->offset = offset; 126 sg->length = len; 127 } 128 129 static inline struct page *sg_page(struct scatterlist *sg) 130 { 131 #ifdef CONFIG_DEBUG_SG 132 BUG_ON(sg->sg_magic != SG_MAGIC); 133 BUG_ON(sg_is_chain(sg)); 134 #endif 135 return (struct page *)((sg)->page_link & ~(SG_CHAIN | SG_END)); 136 } 137 138 /** 139 * sg_set_buf - Set sg entry to point at given data 140 * @sg: SG entry 141 * @buf: Data 142 * @buflen: Data length 143 * 144 **/ 145 static inline void sg_set_buf(struct scatterlist *sg, const void *buf, 146 unsigned int buflen) 147 { 148 #ifdef CONFIG_DEBUG_SG 149 BUG_ON(!virt_addr_valid(buf)); 150 #endif 151 sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); 152 } 153 154 /* 155 * Loop over each sg element, following the pointer to a new list if necessary 156 */ 157 #define for_each_sg(sglist, sg, nr, __i) \ 158 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) 159 160 /** 161 * sg_chain - Chain two sglists together 162 * @prv: First scatterlist 163 * @prv_nents: Number of entries in prv 164 * @sgl: Second scatterlist 165 * 166 * Description: 167 * Links @prv@ and @sgl@ together, to form a longer scatterlist. 168 * 169 **/ 170 static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, 171 struct scatterlist *sgl) 172 { 173 /* 174 * offset and length are unused for chain entry. Clear them. 175 */ 176 prv[prv_nents - 1].offset = 0; 177 prv[prv_nents - 1].length = 0; 178 179 /* 180 * Set lowest bit to indicate a link pointer, and make sure to clear 181 * the termination bit if it happens to be set. 182 */ 183 prv[prv_nents - 1].page_link = ((unsigned long) sgl | SG_CHAIN) 184 & ~SG_END; 185 } 186 187 /** 188 * sg_mark_end - Mark the end of the scatterlist 189 * @sg: SG entryScatterlist 190 * 191 * Description: 192 * Marks the passed in sg entry as the termination point for the sg 193 * table. A call to sg_next() on this entry will return NULL. 194 * 195 **/ 196 static inline void sg_mark_end(struct scatterlist *sg) 197 { 198 #ifdef CONFIG_DEBUG_SG 199 BUG_ON(sg->sg_magic != SG_MAGIC); 200 #endif 201 /* 202 * Set termination bit, clear potential chain bit 203 */ 204 sg->page_link |= SG_END; 205 sg->page_link &= ~SG_CHAIN; 206 } 207 208 /** 209 * sg_unmark_end - Undo setting the end of the scatterlist 210 * @sg: SG entryScatterlist 211 * 212 * Description: 213 * Removes the termination marker from the given entry of the scatterlist. 214 * 215 **/ 216 static inline void sg_unmark_end(struct scatterlist *sg) 217 { 218 #ifdef CONFIG_DEBUG_SG 219 BUG_ON(sg->sg_magic != SG_MAGIC); 220 #endif 221 sg->page_link &= ~SG_END; 222 } 223 224 /** 225 * sg_phys - Return physical address of an sg entry 226 * @sg: SG entry 227 * 228 * Description: 229 * This calls page_to_phys() on the page in this sg entry, and adds the 230 * sg offset. The caller must know that it is legal to call page_to_phys() 231 * on the sg page. 232 * 233 **/ 234 static inline dma_addr_t sg_phys(struct scatterlist *sg) 235 { 236 return page_to_phys(sg_page(sg)) + sg->offset; 237 } 238 239 /** 240 * sg_virt - Return virtual address of an sg entry 241 * @sg: SG entry 242 * 243 * Description: 244 * This calls page_address() on the page in this sg entry, and adds the 245 * sg offset. The caller must know that the sg page has a valid virtual 246 * mapping. 247 * 248 **/ 249 static inline void *sg_virt(struct scatterlist *sg) 250 { 251 return page_address(sg_page(sg)) + sg->offset; 252 } 253 254 /** 255 * sg_init_marker - Initialize markers in sg table 256 * @sgl: The SG table 257 * @nents: Number of entries in table 258 * 259 **/ 260 static inline void sg_init_marker(struct scatterlist *sgl, 261 unsigned int nents) 262 { 263 #ifdef CONFIG_DEBUG_SG 264 unsigned int i; 265 266 for (i = 0; i < nents; i++) 267 sgl[i].sg_magic = SG_MAGIC; 268 #endif 269 sg_mark_end(&sgl[nents - 1]); 270 } 271 272 int sg_nents(struct scatterlist *sg); 273 int sg_nents_for_len(struct scatterlist *sg, u64 len); 274 struct scatterlist *sg_next(struct scatterlist *); 275 struct scatterlist *sg_last(struct scatterlist *s, unsigned int); 276 void sg_init_table(struct scatterlist *, unsigned int); 277 void sg_init_one(struct scatterlist *, const void *, unsigned int); 278 int sg_split(struct scatterlist *in, const int in_mapped_nents, 279 const off_t skip, const int nb_splits, 280 const size_t *split_sizes, 281 struct scatterlist **out, int *out_mapped_nents, 282 gfp_t gfp_mask); 283 284 typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); 285 typedef void (sg_free_fn)(struct scatterlist *, unsigned int); 286 287 void __sg_free_table(struct sg_table *, unsigned int, bool, sg_free_fn *); 288 void sg_free_table(struct sg_table *); 289 int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, 290 struct scatterlist *, gfp_t, sg_alloc_fn *); 291 int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); 292 int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, 293 unsigned int n_pages, unsigned int offset, 294 unsigned long size, unsigned int max_segment, 295 gfp_t gfp_mask); 296 int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, 297 unsigned int n_pages, unsigned int offset, 298 unsigned long size, gfp_t gfp_mask); 299 300 #ifdef CONFIG_SGL_ALLOC 301 struct scatterlist *sgl_alloc_order(unsigned long long length, 302 unsigned int order, bool chainable, 303 gfp_t gfp, unsigned int *nent_p); 304 struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, 305 unsigned int *nent_p); 306 void sgl_free_n_order(struct scatterlist *sgl, int nents, int order); 307 void sgl_free_order(struct scatterlist *sgl, int order); 308 void sgl_free(struct scatterlist *sgl); 309 #endif /* CONFIG_SGL_ALLOC */ 310 311 size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, 312 size_t buflen, off_t skip, bool to_buffer); 313 314 size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, 315 const void *buf, size_t buflen); 316 size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, 317 void *buf, size_t buflen); 318 319 size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, 320 const void *buf, size_t buflen, off_t skip); 321 size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, 322 void *buf, size_t buflen, off_t skip); 323 size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, 324 size_t buflen, off_t skip); 325 326 /* 327 * Maximum number of entries that will be allocated in one piece, if 328 * a list larger than this is required then chaining will be utilized. 329 */ 330 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) 331 332 /* 333 * The maximum number of SG segments that we will put inside a 334 * scatterlist (unless chaining is used). Should ideally fit inside a 335 * single page, to avoid a higher order allocation. We could define this 336 * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The 337 * minimum value is 32 338 */ 339 #define SG_CHUNK_SIZE 128 340 341 /* 342 * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit 343 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios. 344 */ 345 #ifdef CONFIG_ARCH_HAS_SG_CHAIN 346 #define SG_MAX_SEGMENTS 2048 347 #else 348 #define SG_MAX_SEGMENTS SG_CHUNK_SIZE 349 #endif 350 351 #ifdef CONFIG_SG_POOL 352 void sg_free_table_chained(struct sg_table *table, bool first_chunk); 353 int sg_alloc_table_chained(struct sg_table *table, int nents, 354 struct scatterlist *first_chunk); 355 #endif 356 357 /* 358 * sg page iterator 359 * 360 * Iterates over sg entries page-by-page. On each successful iteration, 361 * you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter) 362 * to get the current page and its dma address. @piter->sg will point to the 363 * sg holding this page and @piter->sg_pgoffset to the page's page offset 364 * within the sg. The iteration will stop either when a maximum number of sg 365 * entries was reached or a terminating sg (sg_last(sg) == true) was reached. 366 */ 367 struct sg_page_iter { 368 struct scatterlist *sg; /* sg holding the page */ 369 unsigned int sg_pgoffset; /* page offset within the sg */ 370 371 /* these are internal states, keep away */ 372 unsigned int __nents; /* remaining sg entries */ 373 int __pg_advance; /* nr pages to advance at the 374 * next step */ 375 }; 376 377 bool __sg_page_iter_next(struct sg_page_iter *piter); 378 void __sg_page_iter_start(struct sg_page_iter *piter, 379 struct scatterlist *sglist, unsigned int nents, 380 unsigned long pgoffset); 381 /** 382 * sg_page_iter_page - get the current page held by the page iterator 383 * @piter: page iterator holding the page 384 */ 385 static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) 386 { 387 return nth_page(sg_page(piter->sg), piter->sg_pgoffset); 388 } 389 390 /** 391 * sg_page_iter_dma_address - get the dma address of the current page held by 392 * the page iterator. 393 * @piter: page iterator holding the page 394 */ 395 static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter) 396 { 397 return sg_dma_address(piter->sg) + (piter->sg_pgoffset << PAGE_SHIFT); 398 } 399 400 /** 401 * for_each_sg_page - iterate over the pages of the given sg list 402 * @sglist: sglist to iterate over 403 * @piter: page iterator to hold current page, sg, sg_pgoffset 404 * @nents: maximum number of sg entries to iterate over 405 * @pgoffset: starting page offset 406 */ 407 #define for_each_sg_page(sglist, piter, nents, pgoffset) \ 408 for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \ 409 __sg_page_iter_next(piter);) 410 411 /* 412 * Mapping sg iterator 413 * 414 * Iterates over sg entries mapping page-by-page. On each successful 415 * iteration, @miter->page points to the mapped page and 416 * @miter->length bytes of data can be accessed at @miter->addr. As 417 * long as an interation is enclosed between start and stop, the user 418 * is free to choose control structure and when to stop. 419 * 420 * @miter->consumed is set to @miter->length on each iteration. It 421 * can be adjusted if the user can't consume all the bytes in one go. 422 * Also, a stopped iteration can be resumed by calling next on it. 423 * This is useful when iteration needs to release all resources and 424 * continue later (e.g. at the next interrupt). 425 */ 426 427 #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ 428 #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */ 429 #define SG_MITER_FROM_SG (1 << 2) /* nop */ 430 431 struct sg_mapping_iter { 432 /* the following three fields can be accessed directly */ 433 struct page *page; /* currently mapped page */ 434 void *addr; /* pointer to the mapped area */ 435 size_t length; /* length of the mapped area */ 436 size_t consumed; /* number of consumed bytes */ 437 struct sg_page_iter piter; /* page iterator */ 438 439 /* these are internal states, keep away */ 440 unsigned int __offset; /* offset within page */ 441 unsigned int __remaining; /* remaining bytes on page */ 442 unsigned int __flags; 443 }; 444 445 void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, 446 unsigned int nents, unsigned int flags); 447 bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset); 448 bool sg_miter_next(struct sg_mapping_iter *miter); 449 void sg_miter_stop(struct sg_mapping_iter *miter); 450 451 #endif /* _LINUX_SCATTERLIST_H */ 452