1 /*- 2 * Copyright (c) 2010 Isilon Systems, Inc. 3 * Copyright (c) 2010 iX Systems, Inc. 4 * Copyright (c) 2010 Panasas, Inc. 5 * Copyright (c) 2013, 2014 Mellanox Technologies, Ltd. 6 * Copyright (c) 2015 Matthew Dillon <dillon@backplane.com> 7 * Copyright (c) 2016 Matt Macy <mmacy@nextbsd.org> 8 * All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice unmodified, this list of conditions, and the following 15 * disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #ifndef _LINUX_SCATTERLIST_H_ 33 #define _LINUX_SCATTERLIST_H_ 34 35 #include <linux/string.h> 36 #include <linux/types.h> 37 #include <linux/bug.h> 38 #include <linux/mm.h> 39 #include <asm/io.h> 40 41 /* 42 * SG table design. 43 * 44 * If flags bit 0 is set, then the sg field contains a pointer to the next sg 45 * table list. Otherwise the next entry is at sg + 1, can be determined using 46 * the sg_is_chain() function. 47 * 48 * If flags bit 1 is set, then this sg entry is the last element in a list, 49 * can be determined using the sg_is_last() function. 50 * 51 * See sg_next(). 52 * 53 */ 54 55 struct scatterlist { 56 union { 57 struct vm_page *page; 58 struct scatterlist *sg; 59 } sl_un; 60 unsigned long offset; 61 uint32_t length; 62 dma_addr_t dma_address; 63 uint32_t flags; 64 }; 65 66 struct sg_table { 67 struct scatterlist *sgl; /* the list */ 68 unsigned int nents; /* number of mapped entries */ 69 unsigned int orig_nents; /* original size of list */ 70 }; 71 72 struct sg_page_iter { 73 struct scatterlist *sg; 74 unsigned int sg_pgoffset; /* page index */ 75 unsigned int maxents; 76 unsigned int __nents; 77 int __pg_advance; 78 }; 79 80 81 /* 82 * Maximum number of entries that will be allocated in one piece, if 83 * a list larger than this is required then chaining will be utilized. 84 */ 85 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) 86 87 #define sg_dma_address(sg) (sg)->dma_address 88 #define sg_dma_len(sg) (sg)->length 89 #define sg_page(sg) (sg)->sl_un.page 90 #define sg_scatternext(sg) (sg)->sl_un.sg 91 92 #define SG_END 0x01 93 #define SG_CHAIN 0x02 94 95 static inline void 96 sg_set_page(struct scatterlist *sg, struct vm_page *page, unsigned int len, 97 unsigned int offset) 98 { 99 sg_page(sg) = page; 100 sg_dma_len(sg) = len; 101 sg->offset = offset; 102 if (offset > PAGE_SIZE) 103 panic("sg_set_page: Invalid offset %d\n", offset); 104 } 105 106 #if 0 107 static inline void 108 sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen) 109 { 110 sg_set_page(sg, virt_to_page(buf), buflen, 111 ((uintptr_t)buf) & ~PAGE_MASK); 112 } 113 #endif 114 115 static inline void 116 sg_init_table(struct scatterlist *sg, unsigned int nents) 117 { 118 bzero(sg, sizeof(*sg) * nents); 119 sg[nents - 1].flags = SG_END; 120 } 121 122 static inline struct scatterlist * 123 sg_next(struct scatterlist *sg) 124 { 125 if (sg->flags & SG_END) 126 return (NULL); 127 sg++; 128 if (sg->flags & SG_CHAIN) 129 sg = sg_scatternext(sg); 130 return (sg); 131 } 132 133 static inline vm_paddr_t 134 sg_phys(struct scatterlist *sg) 135 { 136 return sg_page(sg)->phys_addr + sg->offset; 137 } 138 139 /** 140 * sg_chain - Chain two sglists together 141 * @prv: First scatterlist 142 * @prv_nents: Number of entries in prv 143 * @sgl: Second scatterlist 144 * 145 * Description: 146 * Links @prv@ and @sgl@ together, to form a longer scatterlist. 147 * 148 **/ 149 static inline void 150 sg_chain(struct scatterlist *prv, unsigned int prv_nents, 151 struct scatterlist *sgl) 152 { 153 /* 154 * offset and length are unused for chain entry. Clear them. 155 */ 156 struct scatterlist *sg = &prv[prv_nents - 1]; 157 158 sg->offset = 0; 159 sg->length = 0; 160 161 /* 162 * Indicate a link pointer, and set the link to the second list. 163 */ 164 sg->flags = SG_CHAIN; 165 sg->sl_un.sg = sgl; 166 } 167 168 /** 169 * sg_mark_end - Mark the end of the scatterlist 170 * @sg: SG entryScatterlist 171 * 172 * Description: 173 * Marks the passed in sg entry as the termination point for the sg 174 * table. A call to sg_next() on this entry will return NULL. 175 * 176 **/ 177 static inline void sg_mark_end(struct scatterlist *sg) 178 { 179 sg->flags = SG_END; 180 } 181 182 /** 183 * __sg_free_table - Free a previously mapped sg table 184 * @table: The sg table header to use 185 * @max_ents: The maximum number of entries per single scatterlist 186 * 187 * Description: 188 * Free an sg table previously allocated and setup with 189 * __sg_alloc_table(). The @max_ents value must be identical to 190 * that previously used with __sg_alloc_table(). 191 * 192 **/ 193 static inline void 194 __sg_free_table(struct sg_table *table, unsigned int max_ents) 195 { 196 struct scatterlist *sgl, *next; 197 198 if (unlikely(!table->sgl)) 199 return; 200 201 sgl = table->sgl; 202 while (table->orig_nents) { 203 unsigned int alloc_size = table->orig_nents; 204 unsigned int sg_size; 205 206 /* 207 * If we have more than max_ents segments left, 208 * then assign 'next' to the sg table after the current one. 209 * sg_size is then one less than alloc size, since the last 210 * element is the chain pointer. 211 */ 212 if (alloc_size > max_ents) { 213 next = sgl[max_ents - 1].sl_un.sg; 214 alloc_size = max_ents; 215 sg_size = alloc_size - 1; 216 } else { 217 sg_size = alloc_size; 218 next = NULL; 219 } 220 221 table->orig_nents -= sg_size; 222 kfree(sgl); 223 sgl = next; 224 } 225 226 table->sgl = NULL; 227 } 228 229 /** 230 * sg_free_table - Free a previously allocated sg table 231 * @table: The mapped sg table header 232 * 233 **/ 234 static inline void 235 sg_free_table(struct sg_table *table) 236 { 237 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 238 } 239 240 /** 241 * __sg_alloc_table - Allocate and initialize an sg table with given allocator 242 * @table: The sg table header to use 243 * @nents: Number of entries in sg list 244 * @max_ents: The maximum number of entries the allocator returns per call 245 * @gfp_mask: GFP allocation mask 246 * 247 * Description: 248 * This function returns a @table @nents long. The allocator is 249 * defined to return scatterlist chunks of maximum size @max_ents. 250 * Thus if @nents is bigger than @max_ents, the scatterlists will be 251 * chained in units of @max_ents. 252 * 253 * Notes: 254 * If this function returns non-0 (eg failure), the caller must call 255 * __sg_free_table() to cleanup any leftover allocations. 256 * 257 **/ 258 static inline int 259 __sg_alloc_table(struct sg_table *table, unsigned int nents, 260 unsigned int max_ents, gfp_t gfp_mask) 261 { 262 struct scatterlist *sg, *prv; 263 unsigned int left; 264 265 memset(table, 0, sizeof(*table)); 266 267 if (nents == 0) 268 return -EINVAL; 269 left = nents; 270 prv = NULL; 271 do { 272 unsigned int sg_size, alloc_size = left; 273 274 if (alloc_size > max_ents) { 275 alloc_size = max_ents; 276 sg_size = alloc_size - 1; 277 } else 278 sg_size = alloc_size; 279 280 left -= sg_size; 281 282 sg = kmalloc(alloc_size * sizeof(struct scatterlist), M_DRM, gfp_mask); 283 if (unlikely(!sg)) { 284 /* 285 * Adjust entry count to reflect that the last 286 * entry of the previous table won't be used for 287 * linkage. Without this, sg_kfree() may get 288 * confused. 289 */ 290 if (prv) 291 table->nents = ++table->orig_nents; 292 293 return -ENOMEM; 294 } 295 296 sg_init_table(sg, alloc_size); 297 table->nents = table->orig_nents += sg_size; 298 299 /* 300 * If this is the first mapping, assign the sg table header. 301 * If this is not the first mapping, chain previous part. 302 */ 303 if (prv) 304 sg_chain(prv, max_ents, sg); 305 else 306 table->sgl = sg; 307 308 /* 309 * If no more entries after this one, mark the end 310 */ 311 if (!left) 312 sg_mark_end(&sg[sg_size - 1]); 313 314 prv = sg; 315 } while (left); 316 317 return 0; 318 } 319 320 /** 321 * sg_alloc_table - Allocate and initialize an sg table 322 * @table: The sg table header to use 323 * @nents: Number of entries in sg list 324 * @gfp_mask: GFP allocation mask 325 * 326 * Description: 327 * Allocate and initialize an sg table. If @nents@ is larger than 328 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. 329 * 330 **/ 331 332 static inline int 333 sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) 334 { 335 int ret; 336 337 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, 338 gfp_mask); 339 if (unlikely(ret)) 340 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 341 342 return ret; 343 } 344 345 static inline int 346 sg_nents(struct scatterlist *sg) 347 { 348 int nents; 349 for (nents = 0; sg; sg = sg_next(sg)) 350 nents++; 351 return nents; 352 } 353 354 static inline void 355 __sg_page_iter_start(struct sg_page_iter *piter, 356 struct scatterlist *sglist, unsigned int nents, 357 unsigned long pgoffset) 358 { 359 piter->__pg_advance = 0; 360 piter->__nents = nents; 361 362 piter->sg = sglist; 363 piter->sg_pgoffset = pgoffset; 364 } 365 366 /* 367 * Iterate pages in sg list. 368 */ 369 static inline void 370 _sg_iter_next(struct sg_page_iter *iter) 371 { 372 struct scatterlist *sg; 373 unsigned int pgcount; 374 375 sg = iter->sg; 376 pgcount = (sg->offset + sg->length + PAGE_MASK) >> PAGE_SHIFT; 377 378 ++iter->sg_pgoffset; 379 while (iter->sg_pgoffset >= pgcount) { 380 iter->sg_pgoffset -= pgcount; 381 sg = sg_next(sg); 382 --iter->maxents; 383 if (sg == NULL || iter->maxents == 0) 384 break; 385 pgcount = (sg->offset + sg->length + PAGE_MASK) >> PAGE_SHIFT; 386 } 387 iter->sg = sg; 388 } 389 390 static inline int 391 sg_page_count(struct scatterlist *sg) 392 { 393 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; 394 } 395 396 static inline bool 397 __sg_page_iter_next(struct sg_page_iter *piter) 398 { 399 if (piter->__nents == 0) 400 return (false); 401 if (piter->sg == NULL) 402 return (false); 403 404 piter->sg_pgoffset += piter->__pg_advance; 405 piter->__pg_advance = 1; 406 407 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { 408 piter->sg_pgoffset -= sg_page_count(piter->sg); 409 piter->sg = sg_next(piter->sg); 410 if (--piter->__nents == 0) 411 return (false); 412 if (piter->sg == NULL) 413 return (false); 414 } 415 return (true); 416 } 417 418 /* 419 * NOTE: pgoffset is really a page index, not a byte offset. 420 */ 421 static inline void 422 _sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter, 423 unsigned int nents, unsigned long pgoffset) 424 { 425 if (nents) { 426 /* 427 * Nominal case. Note subtract 1 from starting page index 428 * for initial _sg_iter_next() call. 429 */ 430 iter->sg = sgl; 431 iter->sg_pgoffset = pgoffset - 1; 432 iter->maxents = nents; 433 _sg_iter_next(iter); 434 } else { 435 /* 436 * Degenerate case 437 */ 438 iter->sg = NULL; 439 iter->sg_pgoffset = 0; 440 iter->maxents = 0; 441 } 442 } 443 444 static inline struct vm_page * 445 sg_page_iter_page(struct sg_page_iter *piter) 446 { 447 return nth_page(sg_page(piter->sg), piter->sg_pgoffset); 448 } 449 450 static inline dma_addr_t 451 sg_page_iter_dma_address(struct sg_page_iter *spi) 452 { 453 return spi->sg->dma_address + (spi->sg_pgoffset << PAGE_SHIFT); 454 } 455 456 #define for_each_sg_page(sgl, iter, nents, pgoffset) \ 457 for (_sg_iter_init(sgl, iter, nents, pgoffset); \ 458 (iter)->sg; _sg_iter_next(iter)) 459 460 #define for_each_sg(sglist, sg, sgmax, _itr) \ 461 for (_itr = 0, sg = (sglist); _itr < (sgmax); _itr++, sg = sg_next(sg)) 462 463 #endif /* _LINUX_SCATTERLIST_H_ */ 464