1/* 2 * arch/arm/common/dmabounce.c 3 * 4 * Special dma_{map/unmap/dma_sync}_* routines for systems that have 5 * limited DMA windows. These functions utilize bounce buffers to 6 * copy data to/from buffers located outside the DMA region. This 7 * only works for systems in which DMA memory is at the bottom of 8 * RAM, the remainder of memory is at the top and the DMA memory 9 * can be marked as ZONE_DMA. Anything beyond that such as discontiguous 10 * DMA windows will require custom implementations that reserve memory 11 * areas at early bootup. 12 * 13 * Original version by Brad Parker (brad@heeltoe.com) 14 * Re-written by Christopher Hoover <ch@murgatroid.com> 15 * Made generic by Deepak Saxena <dsaxena@plexity.net> 16 * 17 * Copyright (C) 2002 Hewlett Packard Company. 18 * Copyright (C) 2004 MontaVista Software, Inc. 19 * 20 * This program is free software; you can redistribute it and/or 21 * modify it under the terms of the GNU General Public License 22 * version 2 as published by the Free Software Foundation. 23 */ 24 25#include <linux/module.h> 26#include <linux/init.h> 27#include <linux/slab.h> 28#include <linux/page-flags.h> 29#include <linux/device.h> 30#include <linux/dma-mapping.h> 31#include <linux/dmapool.h> 32#include <linux/list.h> 33#include <linux/scatterlist.h> 34 35#include <asm/cacheflush.h> 36 37#undef STATS 38 39#ifdef STATS 40#define DO_STATS(X) do { X ; } while (0) 41#else 42#define DO_STATS(X) do { } while (0) 43#endif 44 45/* ************************************************** */ 46 47struct safe_buffer { 48 struct list_head node; 49 50 /* original request */ 51 void *ptr; 52 size_t size; 53 int direction; 54 55 /* safe buffer info */ 56 struct dmabounce_pool *pool; 57 void *safe; 58 dma_addr_t safe_dma_addr; 59}; 60 61struct dmabounce_pool { 62 unsigned long size; 63 struct dma_pool *pool; 64#ifdef STATS 65 unsigned long allocs; 66#endif 67}; 68 69struct dmabounce_device_info { 70 struct device *dev; 71 struct list_head safe_buffers; 72#ifdef STATS 73 unsigned long total_allocs; 74 unsigned long map_op_count; 75 unsigned long bounce_count; 76 int attr_res; 77#endif 78 struct dmabounce_pool small; 79 struct dmabounce_pool large; 80 81 rwlock_t lock; 82 83 int (*needs_bounce)(struct device *, dma_addr_t, size_t); 84}; 85 86#ifdef STATS 87static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr, 88 char *buf) 89{ 90 struct dmabounce_device_info *device_info = dev->archdata.dmabounce; 91 return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n", 92 device_info->small.allocs, 93 device_info->large.allocs, 94 device_info->total_allocs - device_info->small.allocs - 95 device_info->large.allocs, 96 device_info->total_allocs, 97 device_info->map_op_count, 98 device_info->bounce_count); 99} 100 101static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL); 102#endif 103 104 105/* allocate a 'safe' buffer and keep track of it */ 106static inline struct safe_buffer * 107alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr, 108 size_t size, enum dma_data_direction dir) 109{ 110 struct safe_buffer *buf; 111 struct dmabounce_pool *pool; 112 struct device *dev = device_info->dev; 113 unsigned long flags; 114 115 dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n", 116 __func__, ptr, size, dir); 117 118 if (size <= device_info->small.size) { 119 pool = &device_info->small; 120 } else if (size <= device_info->large.size) { 121 pool = &device_info->large; 122 } else { 123 pool = NULL; 124 } 125 126 buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC); 127 if (buf == NULL) { 128 dev_warn(dev, "%s: kmalloc failed\n", __func__); 129 return NULL; 130 } 131 132 buf->ptr = ptr; 133 buf->size = size; 134 buf->direction = dir; 135 buf->pool = pool; 136 137 if (pool) { 138 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC, 139 &buf->safe_dma_addr); 140 } else { 141 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr, 142 GFP_ATOMIC); 143 } 144 145 if (buf->safe == NULL) { 146 dev_warn(dev, 147 "%s: could not alloc dma memory (size=%d)\n", 148 __func__, size); 149 kfree(buf); 150 return NULL; 151 } 152 153#ifdef STATS 154 if (pool) 155 pool->allocs++; 156 device_info->total_allocs++; 157#endif 158 159 write_lock_irqsave(&device_info->lock, flags); 160 list_add(&buf->node, &device_info->safe_buffers); 161 write_unlock_irqrestore(&device_info->lock, flags); 162 163 return buf; 164} 165 166/* determine if a buffer is from our "safe" pool */ 167static inline struct safe_buffer * 168find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr) 169{ 170 struct safe_buffer *b, *rb = NULL; 171 unsigned long flags; 172 173 read_lock_irqsave(&device_info->lock, flags); 174 175 list_for_each_entry(b, &device_info->safe_buffers, node) 176 if (b->safe_dma_addr <= safe_dma_addr && 177 b->safe_dma_addr + b->size > safe_dma_addr) { 178 rb = b; 179 break; 180 } 181 182 read_unlock_irqrestore(&device_info->lock, flags); 183 return rb; 184} 185 186static inline void 187free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf) 188{ 189 unsigned long flags; 190 191 dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf); 192 193 write_lock_irqsave(&device_info->lock, flags); 194 195 list_del(&buf->node); 196 197 write_unlock_irqrestore(&device_info->lock, flags); 198 199 if (buf->pool) 200 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr); 201 else 202 dma_free_coherent(device_info->dev, buf->size, buf->safe, 203 buf->safe_dma_addr); 204 205 kfree(buf); 206} 207 208/* ************************************************** */ 209 210static struct safe_buffer *find_safe_buffer_dev(struct device *dev, 211 dma_addr_t dma_addr, const char *where) 212{ 213 if (!dev || !dev->archdata.dmabounce) 214 return NULL; 215 if (dma_mapping_error(dev, dma_addr)) { 216 dev_err(dev, "Trying to %s invalid mapping\n", where); 217 return NULL; 218 } 219 return find_safe_buffer(dev->archdata.dmabounce, dma_addr); 220} 221 222static int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size) 223{ 224 if (!dev || !dev->archdata.dmabounce) 225 return 0; 226 227 if (dev->dma_mask) { 228 unsigned long limit, mask = *dev->dma_mask; 229 230 limit = (mask + 1) & ~mask; 231 if (limit && size > limit) { 232 dev_err(dev, "DMA mapping too big (requested %#x " 233 "mask %#Lx)\n", size, *dev->dma_mask); 234 return -E2BIG; 235 } 236 237 /* Figure out if we need to bounce from the DMA mask. */ 238 if ((dma_addr | (dma_addr + size - 1)) & ~mask) 239 return 1; 240 } 241 242 return !!dev->archdata.dmabounce->needs_bounce(dev, dma_addr, size); 243} 244 245static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size, 246 enum dma_data_direction dir) 247{ 248 struct dmabounce_device_info *device_info = dev->archdata.dmabounce; 249 struct safe_buffer *buf; 250 251 if (device_info) 252 DO_STATS ( device_info->map_op_count++ ); 253 254 buf = alloc_safe_buffer(device_info, ptr, size, dir); 255 if (buf == NULL) { 256 dev_err(dev, "%s: unable to map unsafe buffer %p!\n", 257 __func__, ptr); 258 return DMA_ERROR_CODE; 259 } 260 261 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n", 262 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), 263 buf->safe, buf->safe_dma_addr); 264 265 if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) { 266 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n", 267 __func__, ptr, buf->safe, size); 268 memcpy(buf->safe, ptr, size); 269 } 270 271 return buf->safe_dma_addr; 272} 273 274static inline void unmap_single(struct device *dev, struct safe_buffer *buf, 275 size_t size, enum dma_data_direction dir) 276{ 277 BUG_ON(buf->size != size); 278 BUG_ON(buf->direction != dir); 279 280 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n", 281 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), 282 buf->safe, buf->safe_dma_addr); 283 284 DO_STATS(dev->archdata.dmabounce->bounce_count++); 285 286 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) { 287 void *ptr = buf->ptr; 288 289 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n", 290 __func__, buf->safe, ptr, size); 291 memcpy(ptr, buf->safe, size); 292 293 /* 294 * Since we may have written to a page cache page, 295 * we need to ensure that the data will be coherent 296 * with user mappings. 297 */ 298 __cpuc_flush_dcache_area(ptr, size); 299 } 300 free_safe_buffer(dev->archdata.dmabounce, buf); 301} 302 303/* ************************************************** */ 304 305/* 306 * see if a buffer address is in an 'unsafe' range. if it is 307 * allocate a 'safe' buffer and copy the unsafe buffer into it. 308 * substitute the safe buffer for the unsafe one. 309 * (basically move the buffer from an unsafe area to a safe one) 310 */ 311static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page, 312 unsigned long offset, size_t size, enum dma_data_direction dir, 313 struct dma_attrs *attrs) 314{ 315 dma_addr_t dma_addr; 316 int ret; 317 318 dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n", 319 __func__, page, offset, size, dir); 320 321 dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset; 322 323 ret = needs_bounce(dev, dma_addr, size); 324 if (ret < 0) 325 return DMA_ERROR_CODE; 326 327 if (ret == 0) { 328 arm_dma_ops.sync_single_for_device(dev, dma_addr, size, dir); 329 return dma_addr; 330 } 331 332 if (PageHighMem(page)) { 333 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n"); 334 return DMA_ERROR_CODE; 335 } 336 337 return map_single(dev, page_address(page) + offset, size, dir); 338} 339 340/* 341 * see if a mapped address was really a "safe" buffer and if so, copy 342 * the data from the safe buffer back to the unsafe buffer and free up 343 * the safe buffer. (basically return things back to the way they 344 * should be) 345 */ 346static void dmabounce_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size, 347 enum dma_data_direction dir, struct dma_attrs *attrs) 348{ 349 struct safe_buffer *buf; 350 351 dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n", 352 __func__, dma_addr, size, dir); 353 354 buf = find_safe_buffer_dev(dev, dma_addr, __func__); 355 if (!buf) { 356 arm_dma_ops.sync_single_for_cpu(dev, dma_addr, size, dir); 357 return; 358 } 359 360 unmap_single(dev, buf, size, dir); 361} 362 363static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr, 364 size_t sz, enum dma_data_direction dir) 365{ 366 struct safe_buffer *buf; 367 unsigned long off; 368 369 dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n", 370 __func__, addr, sz, dir); 371 372 buf = find_safe_buffer_dev(dev, addr, __func__); 373 if (!buf) 374 return 1; 375 376 off = addr - buf->safe_dma_addr; 377 378 BUG_ON(buf->direction != dir); 379 380 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n", 381 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off, 382 buf->safe, buf->safe_dma_addr); 383 384 DO_STATS(dev->archdata.dmabounce->bounce_count++); 385 386 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) { 387 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n", 388 __func__, buf->safe + off, buf->ptr + off, sz); 389 memcpy(buf->ptr + off, buf->safe + off, sz); 390 } 391 return 0; 392} 393 394static void dmabounce_sync_for_cpu(struct device *dev, 395 dma_addr_t handle, size_t size, enum dma_data_direction dir) 396{ 397 if (!__dmabounce_sync_for_cpu(dev, handle, size, dir)) 398 return; 399 400 arm_dma_ops.sync_single_for_cpu(dev, handle, size, dir); 401} 402 403static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr, 404 size_t sz, enum dma_data_direction dir) 405{ 406 struct safe_buffer *buf; 407 unsigned long off; 408 409 dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n", 410 __func__, addr, sz, dir); 411 412 buf = find_safe_buffer_dev(dev, addr, __func__); 413 if (!buf) 414 return 1; 415 416 off = addr - buf->safe_dma_addr; 417 418 BUG_ON(buf->direction != dir); 419 420 dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n", 421 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off, 422 buf->safe, buf->safe_dma_addr); 423 424 DO_STATS(dev->archdata.dmabounce->bounce_count++); 425 426 if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) { 427 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n", 428 __func__,buf->ptr + off, buf->safe + off, sz); 429 memcpy(buf->safe + off, buf->ptr + off, sz); 430 } 431 return 0; 432} 433 434static void dmabounce_sync_for_device(struct device *dev, 435 dma_addr_t handle, size_t size, enum dma_data_direction dir) 436{ 437 if (!__dmabounce_sync_for_device(dev, handle, size, dir)) 438 return; 439 440 arm_dma_ops.sync_single_for_device(dev, handle, size, dir); 441} 442 443static int dmabounce_set_mask(struct device *dev, u64 dma_mask) 444{ 445 if (dev->archdata.dmabounce) 446 return 0; 447 448 return arm_dma_ops.set_dma_mask(dev, dma_mask); 449} 450 451static struct dma_map_ops dmabounce_ops = { 452 .alloc = arm_dma_alloc, 453 .free = arm_dma_free, 454 .mmap = arm_dma_mmap, 455 .get_sgtable = arm_dma_get_sgtable, 456 .map_page = dmabounce_map_page, 457 .unmap_page = dmabounce_unmap_page, 458 .sync_single_for_cpu = dmabounce_sync_for_cpu, 459 .sync_single_for_device = dmabounce_sync_for_device, 460 .map_sg = arm_dma_map_sg, 461 .unmap_sg = arm_dma_unmap_sg, 462 .sync_sg_for_cpu = arm_dma_sync_sg_for_cpu, 463 .sync_sg_for_device = arm_dma_sync_sg_for_device, 464 .set_dma_mask = dmabounce_set_mask, 465}; 466 467static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev, 468 const char *name, unsigned long size) 469{ 470 pool->size = size; 471 DO_STATS(pool->allocs = 0); 472 pool->pool = dma_pool_create(name, dev, size, 473 0 /* byte alignment */, 474 0 /* no page-crossing issues */); 475 476 return pool->pool ? 0 : -ENOMEM; 477} 478 479int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size, 480 unsigned long large_buffer_size, 481 int (*needs_bounce_fn)(struct device *, dma_addr_t, size_t)) 482{ 483 struct dmabounce_device_info *device_info; 484 int ret; 485 486 device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC); 487 if (!device_info) { 488 dev_err(dev, 489 "Could not allocated dmabounce_device_info\n"); 490 return -ENOMEM; 491 } 492 493 ret = dmabounce_init_pool(&device_info->small, dev, 494 "small_dmabounce_pool", small_buffer_size); 495 if (ret) { 496 dev_err(dev, 497 "dmabounce: could not allocate DMA pool for %ld byte objects\n", 498 small_buffer_size); 499 goto err_free; 500 } 501 502 if (large_buffer_size) { 503 ret = dmabounce_init_pool(&device_info->large, dev, 504 "large_dmabounce_pool", 505 large_buffer_size); 506 if (ret) { 507 dev_err(dev, 508 "dmabounce: could not allocate DMA pool for %ld byte objects\n", 509 large_buffer_size); 510 goto err_destroy; 511 } 512 } 513 514 device_info->dev = dev; 515 INIT_LIST_HEAD(&device_info->safe_buffers); 516 rwlock_init(&device_info->lock); 517 device_info->needs_bounce = needs_bounce_fn; 518 519#ifdef STATS 520 device_info->total_allocs = 0; 521 device_info->map_op_count = 0; 522 device_info->bounce_count = 0; 523 device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats); 524#endif 525 526 dev->archdata.dmabounce = device_info; 527 set_dma_ops(dev, &dmabounce_ops); 528 529 dev_info(dev, "dmabounce: registered device\n"); 530 531 return 0; 532 533 err_destroy: 534 dma_pool_destroy(device_info->small.pool); 535 err_free: 536 kfree(device_info); 537 return ret; 538} 539EXPORT_SYMBOL(dmabounce_register_dev); 540 541void dmabounce_unregister_dev(struct device *dev) 542{ 543 struct dmabounce_device_info *device_info = dev->archdata.dmabounce; 544 545 dev->archdata.dmabounce = NULL; 546 set_dma_ops(dev, NULL); 547 548 if (!device_info) { 549 dev_warn(dev, 550 "Never registered with dmabounce but attempting" 551 "to unregister!\n"); 552 return; 553 } 554 555 if (!list_empty(&device_info->safe_buffers)) { 556 dev_err(dev, 557 "Removing from dmabounce with pending buffers!\n"); 558 BUG(); 559 } 560 561 if (device_info->small.pool) 562 dma_pool_destroy(device_info->small.pool); 563 if (device_info->large.pool) 564 dma_pool_destroy(device_info->large.pool); 565 566#ifdef STATS 567 if (device_info->attr_res == 0) 568 device_remove_file(dev, &dev_attr_dmabounce_stats); 569#endif 570 571 kfree(device_info); 572 573 dev_info(dev, "dmabounce: device unregistered\n"); 574} 575EXPORT_SYMBOL(dmabounce_unregister_dev); 576 577MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>"); 578MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows"); 579MODULE_LICENSE("GPL"); 580