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