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/device.h> 29#include <linux/dma-mapping.h> 30#include <linux/dmapool.h> 31#include <linux/list.h> 32 33#include <asm/cacheflush.h> 34 35#undef STATS 36 37#ifdef STATS 38#define DO_STATS(X) do { X ; } while (0) 39#else 40#define DO_STATS(X) do { } while (0) 41#endif 42 43/* ************************************************** */ 44 45struct safe_buffer { 46 struct list_head node; 47 48 /* original request */ 49 void *ptr; 50 size_t size; 51 int direction; 52 53 /* safe buffer info */ 54 struct dmabounce_pool *pool; 55 void *safe; 56 dma_addr_t safe_dma_addr; 57}; 58 59struct dmabounce_pool { 60 unsigned long size; 61 struct dma_pool *pool; 62#ifdef STATS 63 unsigned long allocs; 64#endif 65}; 66 67struct dmabounce_device_info { 68 struct device *dev; 69 struct list_head safe_buffers; 70#ifdef STATS 71 unsigned long total_allocs; 72 unsigned long map_op_count; 73 unsigned long bounce_count; 74 int attr_res; 75#endif 76 struct dmabounce_pool small; 77 struct dmabounce_pool large; 78 79 rwlock_t lock; 80}; 81 82#ifdef STATS 83static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr, 84 char *buf) 85{ 86 struct dmabounce_device_info *device_info = dev->archdata.dmabounce; 87 return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n", 88 device_info->small.allocs, 89 device_info->large.allocs, 90 device_info->total_allocs - device_info->small.allocs - 91 device_info->large.allocs, 92 device_info->total_allocs, 93 device_info->map_op_count, 94 device_info->bounce_count); 95} 96 97static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL); 98#endif 99 100 101/* allocate a 'safe' buffer and keep track of it */ 102static inline struct safe_buffer * 103alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr, 104 size_t size, enum dma_data_direction dir) 105{ 106 struct safe_buffer *buf; 107 struct dmabounce_pool *pool; 108 struct device *dev = device_info->dev; 109 unsigned long flags; 110 111 dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n", 112 __func__, ptr, size, dir); 113 114 if (size <= device_info->small.size) { 115 pool = &device_info->small; 116 } else if (size <= device_info->large.size) { 117 pool = &device_info->large; 118 } else { 119 pool = NULL; 120 } 121 122 buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC); 123 if (buf == NULL) { 124 dev_warn(dev, "%s: kmalloc failed\n", __func__); 125 return NULL; 126 } 127 128 buf->ptr = ptr; 129 buf->size = size; 130 buf->direction = dir; 131 buf->pool = pool; 132 133 if (pool) { 134 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC, 135 &buf->safe_dma_addr); 136 } else { 137 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr, 138 GFP_ATOMIC); 139 } 140 141 if (buf->safe == NULL) { 142 dev_warn(dev, 143 "%s: could not alloc dma memory (size=%d)\n", 144 __func__, size); 145 kfree(buf); 146 return NULL; 147 } 148 149#ifdef STATS 150 if (pool) 151 pool->allocs++; 152 device_info->total_allocs++; 153#endif 154 155 write_lock_irqsave(&device_info->lock, flags); 156 157 list_add(&buf->node, &device_info->safe_buffers); 158 159 write_unlock_irqrestore(&device_info->lock, flags); 160 161 return buf; 162} 163 164/* determine if a buffer is from our "safe" pool */ 165static inline struct safe_buffer * 166find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr) 167{ 168 struct safe_buffer *b, *rb = NULL; 169 unsigned long flags; 170 171 read_lock_irqsave(&device_info->lock, flags); 172 173 list_for_each_entry(b, &device_info->safe_buffers, node) 174 if (b->safe_dma_addr == safe_dma_addr) { 175 rb = b; 176 break; 177 } 178 179 read_unlock_irqrestore(&device_info->lock, flags); 180 return rb; 181} 182 183static inline void 184free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf) 185{ 186 unsigned long flags; 187 188 dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf); 189 190 write_lock_irqsave(&device_info->lock, flags); 191 192 list_del(&buf->node); 193 194 write_unlock_irqrestore(&device_info->lock, flags); 195 196 if (buf->pool) 197 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr); 198 else 199 dma_free_coherent(device_info->dev, buf->size, buf->safe, 200 buf->safe_dma_addr); 201 202 kfree(buf); 203} 204 205/* ************************************************** */ 206 207static inline dma_addr_t 208map_single(struct device *dev, void *ptr, size_t size, 209 enum dma_data_direction dir) 210{ 211 struct dmabounce_device_info *device_info = dev->archdata.dmabounce; 212 dma_addr_t dma_addr; 213 int needs_bounce = 0; 214 215 if (device_info) 216 DO_STATS ( device_info->map_op_count++ ); 217 218 dma_addr = virt_to_dma(dev, ptr); 219 220 if (dev->dma_mask) { 221 unsigned long mask = *dev->dma_mask; 222 unsigned long limit; 223 224 limit = (mask + 1) & ~mask; 225 if (limit && size > limit) { 226 dev_err(dev, "DMA mapping too big (requested %#x " 227 "mask %#Lx)\n", size, *dev->dma_mask); 228 return ~0; 229 } 230 231 /* 232 * Figure out if we need to bounce from the DMA mask. 233 */ 234 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask; 235 } 236 237 if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) { 238 struct safe_buffer *buf; 239 240 buf = alloc_safe_buffer(device_info, ptr, size, dir); 241 if (buf == 0) { 242 dev_err(dev, "%s: unable to map unsafe buffer %p!\n", 243 __func__, ptr); 244 return 0; 245 } 246 247 dev_dbg(dev, 248 "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n", 249 __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr), 250 buf->safe, (void *) buf->safe_dma_addr); 251 252 if ((dir == DMA_TO_DEVICE) || 253 (dir == DMA_BIDIRECTIONAL)) { 254 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n", 255 __func__, ptr, buf->safe, size); 256 memcpy(buf->safe, ptr, size); 257 } 258 ptr = buf->safe; 259 260 dma_addr = buf->safe_dma_addr; 261 } else { 262 /* 263 * We don't need to sync the DMA buffer since 264 * it was allocated via the coherent allocators. 265 */ 266 consistent_sync(ptr, size, dir); 267 } 268 269 return dma_addr; 270} 271 272static inline void 273unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size, 274 enum dma_data_direction dir) 275{ 276 struct dmabounce_device_info *device_info = dev->archdata.dmabounce; 277 struct safe_buffer *buf = NULL; 278 279 /* 280 * Trying to unmap an invalid mapping 281 */ 282 if (dma_mapping_error(dma_addr)) { 283 dev_err(dev, "Trying to unmap invalid mapping\n"); 284 return; 285 } 286 287 if (device_info) 288 buf = find_safe_buffer(device_info, dma_addr); 289 290 if (buf) { 291 BUG_ON(buf->size != size); 292 293 dev_dbg(dev, 294 "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n", 295 __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr), 296 buf->safe, (void *) buf->safe_dma_addr); 297 298 DO_STATS ( device_info->bounce_count++ ); 299 300 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) { 301 void *ptr = buf->ptr; 302 303 dev_dbg(dev, 304 "%s: copy back safe %p to unsafe %p size %d\n", 305 __func__, buf->safe, ptr, size); 306 memcpy(ptr, buf->safe, size); 307 308 /* 309 * DMA buffers must have the same cache properties 310 * as if they were really used for DMA - which means 311 * data must be written back to RAM. Note that 312 * we don't use dmac_flush_range() here for the 313 * bidirectional case because we know the cache 314 * lines will be coherent with the data written. 315 */ 316 dmac_clean_range(ptr, ptr + size); 317 outer_clean_range(__pa(ptr), __pa(ptr) + size); 318 } 319 free_safe_buffer(device_info, buf); 320 } 321} 322 323static inline void 324sync_single(struct device *dev, dma_addr_t dma_addr, size_t size, 325 enum dma_data_direction dir) 326{ 327 struct dmabounce_device_info *device_info = dev->archdata.dmabounce; 328 struct safe_buffer *buf = NULL; 329 330 if (device_info) 331 buf = find_safe_buffer(device_info, dma_addr); 332 333 if (buf) { 334 /* 335 * Both of these checks from original code need to be 336 * commented out b/c some drivers rely on the following: 337 * 338 * 1) Drivers may map a large chunk of memory into DMA space 339 * but only sync a small portion of it. Good example is 340 * allocating a large buffer, mapping it, and then 341 * breaking it up into small descriptors. No point 342 * in syncing the whole buffer if you only have to 343 * touch one descriptor. 344 * 345 * 2) Buffers that are mapped as DMA_BIDIRECTIONAL are 346 * usually only synced in one dir at a time. 347 * 348 * See drivers/net/eepro100.c for examples of both cases. 349 * 350 * -ds 351 * 352 * BUG_ON(buf->size != size); 353 * BUG_ON(buf->direction != dir); 354 */ 355 356 dev_dbg(dev, 357 "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n", 358 __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr), 359 buf->safe, (void *) buf->safe_dma_addr); 360 361 DO_STATS ( device_info->bounce_count++ ); 362 363 switch (dir) { 364 case DMA_FROM_DEVICE: 365 dev_dbg(dev, 366 "%s: copy back safe %p to unsafe %p size %d\n", 367 __func__, buf->safe, buf->ptr, size); 368 memcpy(buf->ptr, buf->safe, size); 369 break; 370 case DMA_TO_DEVICE: 371 dev_dbg(dev, 372 "%s: copy out unsafe %p to safe %p, size %d\n", 373 __func__,buf->ptr, buf->safe, size); 374 memcpy(buf->safe, buf->ptr, size); 375 break; 376 case DMA_BIDIRECTIONAL: 377 BUG(); /* is this allowed? what does it mean? */ 378 default: 379 BUG(); 380 } 381 /* 382 * No need to sync the safe buffer - it was allocated 383 * via the coherent allocators. 384 */ 385 } else { 386 consistent_sync(dma_to_virt(dev, dma_addr), size, dir); 387 } 388} 389 390/* ************************************************** */ 391 392/* 393 * see if a buffer address is in an 'unsafe' range. if it is 394 * allocate a 'safe' buffer and copy the unsafe buffer into it. 395 * substitute the safe buffer for the unsafe one. 396 * (basically move the buffer from an unsafe area to a safe one) 397 */ 398dma_addr_t 399dma_map_single(struct device *dev, void *ptr, size_t size, 400 enum dma_data_direction dir) 401{ 402 dma_addr_t dma_addr; 403 404 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n", 405 __func__, ptr, size, dir); 406 407 BUG_ON(dir == DMA_NONE); 408 409 dma_addr = map_single(dev, ptr, size, dir); 410 411 return dma_addr; 412} 413 414/* 415 * see if a mapped address was really a "safe" buffer and if so, copy 416 * the data from the safe buffer back to the unsafe buffer and free up 417 * the safe buffer. (basically return things back to the way they 418 * should be) 419 */ 420 421void 422dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size, 423 enum dma_data_direction dir) 424{ 425 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n", 426 __func__, (void *) dma_addr, size, dir); 427 428 BUG_ON(dir == DMA_NONE); 429 430 unmap_single(dev, dma_addr, size, dir); 431} 432 433int 434dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, 435 enum dma_data_direction dir) 436{ 437 int i; 438 439 dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n", 440 __func__, sg, nents, dir); 441 442 BUG_ON(dir == DMA_NONE); 443 444 for (i = 0; i < nents; i++, sg++) { 445 struct page *page = sg->page; 446 unsigned int offset = sg->offset; 447 unsigned int length = sg->length; 448 void *ptr = page_address(page) + offset; 449 450 sg->dma_address = 451 map_single(dev, ptr, length, dir); 452 } 453 454 return nents; 455} 456 457void 458dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents, 459 enum dma_data_direction dir) 460{ 461 int i; 462 463 dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n", 464 __func__, sg, nents, dir); 465 466 BUG_ON(dir == DMA_NONE); 467 468 for (i = 0; i < nents; i++, sg++) { 469 dma_addr_t dma_addr = sg->dma_address; 470 unsigned int length = sg->length; 471 472 unmap_single(dev, dma_addr, length, dir); 473 } 474} 475 476void 477dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size, 478 enum dma_data_direction dir) 479{ 480 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n", 481 __func__, (void *) dma_addr, size, dir); 482 483 sync_single(dev, dma_addr, size, dir); 484} 485 486void 487dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size, 488 enum dma_data_direction dir) 489{ 490 dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n", 491 __func__, (void *) dma_addr, size, dir); 492 493 sync_single(dev, dma_addr, size, dir); 494} 495 496void 497dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents, 498 enum dma_data_direction dir) 499{ 500 int i; 501 502 dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n", 503 __func__, sg, nents, dir); 504 505 BUG_ON(dir == DMA_NONE); 506 507 for (i = 0; i < nents; i++, sg++) { 508 dma_addr_t dma_addr = sg->dma_address; 509 unsigned int length = sg->length; 510 511 sync_single(dev, dma_addr, length, dir); 512 } 513} 514 515void 516dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents, 517 enum dma_data_direction dir) 518{ 519 int i; 520 521 dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n", 522 __func__, sg, nents, dir); 523 524 BUG_ON(dir == DMA_NONE); 525 526 for (i = 0; i < nents; i++, sg++) { 527 dma_addr_t dma_addr = sg->dma_address; 528 unsigned int length = sg->length; 529 530 sync_single(dev, dma_addr, length, dir); 531 } 532} 533 534static int 535dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev, const char *name, 536 unsigned long size) 537{ 538 pool->size = size; 539 DO_STATS(pool->allocs = 0); 540 pool->pool = dma_pool_create(name, dev, size, 541 0 /* byte alignment */, 542 0 /* no page-crossing issues */); 543 544 return pool->pool ? 0 : -ENOMEM; 545} 546 547int 548dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size, 549 unsigned long large_buffer_size) 550{ 551 struct dmabounce_device_info *device_info; 552 int ret; 553 554 device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC); 555 if (!device_info) { 556 printk(KERN_ERR 557 "Could not allocated dmabounce_device_info for %s", 558 dev->bus_id); 559 return -ENOMEM; 560 } 561 562 ret = dmabounce_init_pool(&device_info->small, dev, 563 "small_dmabounce_pool", small_buffer_size); 564 if (ret) { 565 dev_err(dev, 566 "dmabounce: could not allocate DMA pool for %ld byte objects\n", 567 small_buffer_size); 568 goto err_free; 569 } 570 571 if (large_buffer_size) { 572 ret = dmabounce_init_pool(&device_info->large, dev, 573 "large_dmabounce_pool", 574 large_buffer_size); 575 if (ret) { 576 dev_err(dev, 577 "dmabounce: could not allocate DMA pool for %ld byte objects\n", 578 large_buffer_size); 579 goto err_destroy; 580 } 581 } 582 583 device_info->dev = dev; 584 INIT_LIST_HEAD(&device_info->safe_buffers); 585 rwlock_init(&device_info->lock); 586 587#ifdef STATS 588 device_info->total_allocs = 0; 589 device_info->map_op_count = 0; 590 device_info->bounce_count = 0; 591 device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats); 592#endif 593 594 dev->archdata.dmabounce = device_info; 595 596 printk(KERN_INFO "dmabounce: registered device %s on %s bus\n", 597 dev->bus_id, dev->bus->name); 598 599 return 0; 600 601 err_destroy: 602 dma_pool_destroy(device_info->small.pool); 603 err_free: 604 kfree(device_info); 605 return ret; 606} 607 608void 609dmabounce_unregister_dev(struct device *dev) 610{ 611 struct dmabounce_device_info *device_info = dev->archdata.dmabounce; 612 613 dev->archdata.dmabounce = NULL; 614 615 if (!device_info) { 616 printk(KERN_WARNING 617 "%s: Never registered with dmabounce but attempting" \ 618 "to unregister!\n", dev->bus_id); 619 return; 620 } 621 622 if (!list_empty(&device_info->safe_buffers)) { 623 printk(KERN_ERR 624 "%s: Removing from dmabounce with pending buffers!\n", 625 dev->bus_id); 626 BUG(); 627 } 628 629 if (device_info->small.pool) 630 dma_pool_destroy(device_info->small.pool); 631 if (device_info->large.pool) 632 dma_pool_destroy(device_info->large.pool); 633 634#ifdef STATS 635 if (device_info->attr_res == 0) 636 device_remove_file(dev, &dev_attr_dmabounce_stats); 637#endif 638 639 kfree(device_info); 640 641 printk(KERN_INFO "dmabounce: device %s on %s bus unregistered\n", 642 dev->bus_id, dev->bus->name); 643} 644 645 646EXPORT_SYMBOL(dma_map_single); 647EXPORT_SYMBOL(dma_unmap_single); 648EXPORT_SYMBOL(dma_map_sg); 649EXPORT_SYMBOL(dma_unmap_sg); 650EXPORT_SYMBOL(dma_sync_single_for_cpu); 651EXPORT_SYMBOL(dma_sync_single_for_device); 652EXPORT_SYMBOL(dma_sync_sg); 653EXPORT_SYMBOL(dmabounce_register_dev); 654EXPORT_SYMBOL(dmabounce_unregister_dev); 655 656MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>"); 657MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows"); 658MODULE_LICENSE("GPL"); 659