arch/arm/common/dmabounce.c

   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 discontigous
  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 DEBUG
  36 #undef STATS
  37
  38 #ifdef STATS
  39 #define DO_STATS(X) do { X ; } while (0)
  40 #else
  41 #define DO_STATS(X) do { } while (0)
  42 #endif
  43
  44 /* ************************************************** */
  45
  46 struct safe_buffer {
  47         struct list_head node;
  48
  49         /* original request */
  50         void            *ptr;
  51         size_t          size;
  52         int             direction;
  53
  54         /* safe buffer info */
  55         struct dmabounce_pool *pool;
  56         void            *safe;
  57         dma_addr_t      safe_dma_addr;
  58 };
  59
  60 struct dmabounce_pool {
  61         unsigned long   size;
  62         struct dma_pool *pool;
  63 #ifdef STATS
  64         unsigned long   allocs;
  65 #endif
  66 };
  67
  68 struct dmabounce_device_info {
  69         struct list_head node;
  70
  71         struct device *dev;
  72         struct list_head safe_buffers;
  73 #ifdef STATS
  74         unsigned long total_allocs;
  75         unsigned long map_op_count;
  76         unsigned long bounce_count;
  77 #endif
  78         struct dmabounce_pool   small;
  79         struct dmabounce_pool   large;
  80
  81         rwlock_t lock;
  82 };
  83
  84 static LIST_HEAD(dmabounce_devs);
  85
  86 #ifdef STATS
  87 static void print_alloc_stats(struct dmabounce_device_info *device_info)
  88 {
  89         printk(KERN_INFO
  90                 "%s: dmabounce: sbp: %lu, lbp: %lu, other: %lu, total: %lu\n",
  91                 device_info->dev->bus_id,
  92                 device_info->small.allocs, device_info->large.allocs,
  93                 device_info->total_allocs - device_info->small.allocs -
  94                         device_info->large.allocs,
  95                 device_info->total_allocs);
  96 }
  97 #endif
  98
  99 /* find the given device in the dmabounce device list */
 100 static inline struct dmabounce_device_info *
 101 find_dmabounce_dev(struct device *dev)
 102 {
 103         struct dmabounce_device_info *d;
 104
 105         list_for_each_entry(d, &dmabounce_devs, node)
 106                 if (d->dev == dev)
 107                         return d;
 108
 109         return NULL;
 110 }
 111
 112
 113 /* allocate a 'safe' buffer and keep track of it */
 114 static inline struct safe_buffer *
 115 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 116                   size_t size, enum dma_data_direction dir)
 117 {
 118         struct safe_buffer *buf;
 119         struct dmabounce_pool *pool;
 120         struct device *dev = device_info->dev;
 121         unsigned long flags;
 122
 123         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 124                 __func__, ptr, size, dir);
 125
 126         if (size <= device_info->small.size) {
 127                 pool = &device_info->small;
 128         } else if (size <= device_info->large.size) {
 129                 pool = &device_info->large;
 130         } else {
 131                 pool = NULL;
 132         }
 133
 134         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 135         if (buf == NULL) {
 136                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 137                 return NULL;
 138         }
 139
 140         buf->ptr = ptr;
 141         buf->size = size;
 142         buf->direction = dir;
 143         buf->pool = pool;
 144
 145         if (pool) {
 146                 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
 147                                            &buf->safe_dma_addr);
 148         } else {
 149                 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
 150                                                GFP_ATOMIC);
 151         }
 152
 153         if (buf->safe == NULL) {
 154                 dev_warn(dev,
 155                          "%s: could not alloc dma memory (size=%d)\n",
 156                          __func__, size);
 157                 kfree(buf);
 158                 return NULL;
 159         }
 160
 161 #ifdef STATS
 162         if (pool)
 163                 pool->allocs++;
 164         device_info->total_allocs++;
 165         if (device_info->total_allocs % 1000 == 0)
 166                 print_alloc_stats(device_info);
 167 #endif
 168
 169         write_lock_irqsave(&device_info->lock, flags);
 170
 171         list_add(&buf->node, &device_info->safe_buffers);
 172
 173         write_unlock_irqrestore(&device_info->lock, flags);
 174
 175         return buf;
 176 }
 177
 178 /* determine if a buffer is from our "safe" pool */
 179 static inline struct safe_buffer *
 180 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 181 {
 182         struct safe_buffer *b, *rb = NULL;
 183         unsigned long flags;
 184
 185         read_lock_irqsave(&device_info->lock, flags);
 186
 187         list_for_each_entry(b, &device_info->safe_buffers, node)
 188                 if (b->safe_dma_addr == safe_dma_addr) {
 189                         rb = b;
 190                         break;
 191                 }
 192
 193         read_unlock_irqrestore(&device_info->lock, flags);
 194         return rb;
 195 }
 196
 197 static inline void
 198 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 199 {
 200         unsigned long flags;
 201
 202         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 203
 204         write_lock_irqsave(&device_info->lock, flags);
 205
 206         list_del(&buf->node);
 207
 208         write_unlock_irqrestore(&device_info->lock, flags);
 209
 210         if (buf->pool)
 211                 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
 212         else
 213                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 214                                     buf->safe_dma_addr);
 215
 216         kfree(buf);
 217 }
 218
 219 /* ************************************************** */
 220
 221 #ifdef STATS
 222 static void print_map_stats(struct dmabounce_device_info *device_info)
 223 {
 224         dev_info(device_info->dev,
 225                 "dmabounce: map_op_count=%lu, bounce_count=%lu\n",
 226                 device_info->map_op_count, device_info->bounce_count);
 227 }
 228 #endif
 229
 230 static inline dma_addr_t
 231 map_single(struct device *dev, void *ptr, size_t size,
 232                 enum dma_data_direction dir)
 233 {
 234         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 235         dma_addr_t dma_addr;
 236         int needs_bounce = 0;
 237
 238         if (device_info)
 239                 DO_STATS ( device_info->map_op_count++ );
 240
 241         dma_addr = virt_to_dma(dev, ptr);
 242
 243         if (dev->dma_mask) {
 244                 unsigned long mask = *dev->dma_mask;
 245                 unsigned long limit;
 246
 247                 limit = (mask + 1) & ~mask;
 248                 if (limit && size > limit) {
 249                         dev_err(dev, "DMA mapping too big (requested %#x "
 250                                 "mask %#Lx)\n", size, *dev->dma_mask);
 251                         return ~0;
 252                 }
 253
 254                 /*
 255                  * Figure out if we need to bounce from the DMA mask.
 256                  */
 257                 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
 258         }
 259
 260         if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
 261                 struct safe_buffer *buf;
 262
 263                 buf = alloc_safe_buffer(device_info, ptr, size, dir);
 264                 if (buf == 0) {
 265                         dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 266                                __func__, ptr);
 267                         return 0;
 268                 }
 269
 270                 dev_dbg(dev,
 271                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 272                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 273                         buf->safe, (void *) buf->safe_dma_addr);
 274
 275                 if ((dir == DMA_TO_DEVICE) ||
 276                     (dir == DMA_BIDIRECTIONAL)) {
 277                         dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 278                                 __func__, ptr, buf->safe, size);
 279                         memcpy(buf->safe, ptr, size);
 280                 }
 281                 ptr = buf->safe;
 282
 283                 dma_addr = buf->safe_dma_addr;
 284         } else {
 285                 /*
 286                  * We don't need to sync the DMA buffer since
 287                  * it was allocated via the coherent allocators.
 288                  */
 289                 consistent_sync(ptr, size, dir);
 290         }
 291
 292         return dma_addr;
 293 }
 294
 295 static inline void
 296 unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 297                 enum dma_data_direction dir)
 298 {
 299         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 300         struct safe_buffer *buf = NULL;
 301
 302         /*
 303          * Trying to unmap an invalid mapping
 304          */
 305         if (dma_mapping_error(dma_addr)) {
 306                 dev_err(dev, "Trying to unmap invalid mapping\n");
 307                 return;
 308         }
 309
 310         if (device_info)
 311                 buf = find_safe_buffer(device_info, dma_addr);
 312
 313         if (buf) {
 314                 BUG_ON(buf->size != size);
 315
 316                 dev_dbg(dev,
 317                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 318                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 319                         buf->safe, (void *) buf->safe_dma_addr);
 320
 321                 DO_STATS ( device_info->bounce_count++ );
 322
 323                 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 324                         unsigned long ptr;
 325
 326                         dev_dbg(dev,
 327                                 "%s: copy back safe %p to unsafe %p size %d\n",
 328                                 __func__, buf->safe, buf->ptr, size);
 329                         memcpy(buf->ptr, buf->safe, size);
 330
 331                         /*
 332                          * DMA buffers must have the same cache properties
 333                          * as if they were really used for DMA - which means
 334                          * data must be written back to RAM.  Note that
 335                          * we don't use dmac_flush_range() here for the
 336                          * bidirectional case because we know the cache
 337                          * lines will be coherent with the data written.
 338                          */
 339                         ptr = (unsigned long)buf->ptr;
 340                         dmac_clean_range(ptr, ptr + size);
 341                 }
 342                 free_safe_buffer(device_info, buf);
 343         }
 344 }
 345
 346 static inline void
 347 sync_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 348                 enum dma_data_direction dir)
 349 {
 350         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 351         struct safe_buffer *buf = NULL;
 352
 353         if (device_info)
 354                 buf = find_safe_buffer(device_info, dma_addr);
 355
 356         if (buf) {
 357                 /*
 358                  * Both of these checks from original code need to be
 359                  * commented out b/c some drivers rely on the following:
 360                  *
 361                  * 1) Drivers may map a large chunk of memory into DMA space
 362                  *    but only sync a small portion of it. Good example is
 363                  *    allocating a large buffer, mapping it, and then
 364                  *    breaking it up into small descriptors. No point
 365                  *    in syncing the whole buffer if you only have to
 366                  *    touch one descriptor.
 367                  *
 368                  * 2) Buffers that are mapped as DMA_BIDIRECTIONAL are
 369                  *    usually only synced in one dir at a time.
 370                  *
 371                  * See drivers/net/eepro100.c for examples of both cases.
 372                  *
 373                  * -ds
 374                  *
 375                  * BUG_ON(buf->size != size);
 376                  * BUG_ON(buf->direction != dir);
 377                  */
 378
 379                 dev_dbg(dev,
 380                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 381                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 382                         buf->safe, (void *) buf->safe_dma_addr);
 383
 384                 DO_STATS ( device_info->bounce_count++ );
 385
 386                 switch (dir) {
 387                 case DMA_FROM_DEVICE:
 388                         dev_dbg(dev,
 389                                 "%s: copy back safe %p to unsafe %p size %d\n",
 390                                 __func__, buf->safe, buf->ptr, size);
 391                         memcpy(buf->ptr, buf->safe, size);
 392                         break;
 393                 case DMA_TO_DEVICE:
 394                         dev_dbg(dev,
 395                                 "%s: copy out unsafe %p to safe %p, size %d\n",
 396                                 __func__,buf->ptr, buf->safe, size);
 397                         memcpy(buf->safe, buf->ptr, size);
 398                         break;
 399                 case DMA_BIDIRECTIONAL:
 400                         BUG();  /* is this allowed?  what does it mean? */
 401                 default:
 402                         BUG();
 403                 }
 404                 /*
 405                  * No need to sync the safe buffer - it was allocated
 406                  * via the coherent allocators.
 407                  */
 408         } else {
 409                 consistent_sync(dma_to_virt(dev, dma_addr), size, dir);
 410         }
 411 }
 412
 413 /* ************************************************** */
 414
 415 /*
 416  * see if a buffer address is in an 'unsafe' range.  if it is
 417  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 418  * substitute the safe buffer for the unsafe one.
 419  * (basically move the buffer from an unsafe area to a safe one)
 420  */
 421 dma_addr_t
 422 dma_map_single(struct device *dev, void *ptr, size_t size,
 423                 enum dma_data_direction dir)
 424 {
 425         dma_addr_t dma_addr;
 426
 427         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 428                 __func__, ptr, size, dir);
 429
 430         BUG_ON(dir == DMA_NONE);
 431
 432         dma_addr = map_single(dev, ptr, size, dir);
 433
 434         return dma_addr;
 435 }
 436
 437 /*
 438  * see if a mapped address was really a "safe" buffer and if so, copy
 439  * the data from the safe buffer back to the unsafe buffer and free up
 440  * the safe buffer.  (basically return things back to the way they
 441  * should be)
 442  */
 443
 444 void
 445 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 446                         enum dma_data_direction dir)
 447 {
 448         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 449                 __func__, (void *) dma_addr, size, dir);
 450
 451         BUG_ON(dir == DMA_NONE);
 452
 453         unmap_single(dev, dma_addr, size, dir);
 454 }
 455
 456 int
 457 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 458                 enum dma_data_direction dir)
 459 {
 460         int i;
 461
 462         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 463                 __func__, sg, nents, dir);
 464
 465         BUG_ON(dir == DMA_NONE);
 466
 467         for (i = 0; i < nents; i++, sg++) {
 468                 struct page *page = sg->page;
 469                 unsigned int offset = sg->offset;
 470                 unsigned int length = sg->length;
 471                 void *ptr = page_address(page) + offset;
 472
 473                 sg->dma_address =
 474                         map_single(dev, ptr, length, dir);
 475         }
 476
 477         return nents;
 478 }
 479
 480 void
 481 dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 482                 enum dma_data_direction dir)
 483 {
 484         int i;
 485
 486         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 487                 __func__, sg, nents, dir);
 488
 489         BUG_ON(dir == DMA_NONE);
 490
 491         for (i = 0; i < nents; i++, sg++) {
 492                 dma_addr_t dma_addr = sg->dma_address;
 493                 unsigned int length = sg->length;
 494
 495                 unmap_single(dev, dma_addr, length, dir);
 496         }
 497 }
 498
 499 void
 500 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size,
 501                                 enum dma_data_direction dir)
 502 {
 503         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 504                 __func__, (void *) dma_addr, size, dir);
 505
 506         sync_single(dev, dma_addr, size, dir);
 507 }
 508
 509 void
 510 dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size,
 511                                 enum dma_data_direction dir)
 512 {
 513         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 514                 __func__, (void *) dma_addr, size, dir);
 515
 516         sync_single(dev, dma_addr, size, dir);
 517 }
 518
 519 void
 520 dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
 521                         enum dma_data_direction dir)
 522 {
 523         int i;
 524
 525         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 526                 __func__, sg, nents, dir);
 527
 528         BUG_ON(dir == DMA_NONE);
 529
 530         for (i = 0; i < nents; i++, sg++) {
 531                 dma_addr_t dma_addr = sg->dma_address;
 532                 unsigned int length = sg->length;
 533
 534                 sync_single(dev, dma_addr, length, dir);
 535         }
 536 }
 537
 538 void
 539 dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
 540                         enum dma_data_direction dir)
 541 {
 542         int i;
 543
 544         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 545                 __func__, sg, nents, dir);
 546
 547         BUG_ON(dir == DMA_NONE);
 548
 549         for (i = 0; i < nents; i++, sg++) {
 550                 dma_addr_t dma_addr = sg->dma_address;
 551                 unsigned int length = sg->length;
 552
 553                 sync_single(dev, dma_addr, length, dir);
 554         }
 555 }
 556
 557 static int
 558 dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev, const char *name,
 559                     unsigned long size)
 560 {
 561         pool->size = size;
 562         DO_STATS(pool->allocs = 0);
 563         pool->pool = dma_pool_create(name, dev, size,
 564                                      0 /* byte alignment */,
 565                                      0 /* no page-crossing issues */);
 566
 567         return pool->pool ? 0 : -ENOMEM;
 568 }
 569
 570 int
 571 dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 572                         unsigned long large_buffer_size)
 573 {
 574         struct dmabounce_device_info *device_info;
 575         int ret;
 576
 577         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 578         if (!device_info) {
 579                 printk(KERN_ERR
 580                         "Could not allocated dmabounce_device_info for %s",
 581                         dev->bus_id);
 582                 return -ENOMEM;
 583         }
 584
 585         ret = dmabounce_init_pool(&device_info->small, dev,
 586                                   "small_dmabounce_pool", small_buffer_size);
 587         if (ret) {
 588                 dev_err(dev,
 589                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 590                         small_buffer_size);
 591                 goto err_free;
 592         }
 593
 594         if (large_buffer_size) {
 595                 ret = dmabounce_init_pool(&device_info->large, dev,
 596                                           "large_dmabounce_pool",
 597                                           large_buffer_size);
 598                 if (ret) {
 599                         dev_err(dev,
 600                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 601                                 large_buffer_size);
 602                         goto err_destroy;
 603                 }
 604         }
 605
 606         device_info->dev = dev;
 607         INIT_LIST_HEAD(&device_info->safe_buffers);
 608         rwlock_init(&device_info->lock);
 609
 610 #ifdef STATS
 611         device_info->total_allocs = 0;
 612         device_info->map_op_count = 0;
 613         device_info->bounce_count = 0;
 614 #endif
 615
 616         list_add(&device_info->node, &dmabounce_devs);
 617
 618         printk(KERN_INFO "dmabounce: registered device %s on %s bus\n",
 619                 dev->bus_id, dev->bus->name);
 620
 621         return 0;
 622
 623  err_destroy:
 624         dma_pool_destroy(device_info->small.pool);
 625  err_free:
 626         kfree(device_info);
 627         return ret;
 628 }
 629
 630 void
 631 dmabounce_unregister_dev(struct device *dev)
 632 {
 633         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 634
 635         if (!device_info) {
 636                 printk(KERN_WARNING
 637                         "%s: Never registered with dmabounce but attempting" \
 638                         "to unregister!\n", dev->bus_id);
 639                 return;
 640         }
 641
 642         if (!list_empty(&device_info->safe_buffers)) {
 643                 printk(KERN_ERR
 644                         "%s: Removing from dmabounce with pending buffers!\n",
 645                         dev->bus_id);
 646                 BUG();
 647         }
 648
 649         if (device_info->small.pool)
 650                 dma_pool_destroy(device_info->small.pool);
 651         if (device_info->large.pool)
 652                 dma_pool_destroy(device_info->large.pool);
 653
 654 #ifdef STATS
 655         print_alloc_stats(device_info);
 656         print_map_stats(device_info);
 657 #endif
 658
 659         list_del(&device_info->node);
 660
 661         kfree(device_info);
 662
 663         printk(KERN_INFO "dmabounce: device %s on %s bus unregistered\n",
 664                 dev->bus_id, dev->bus->name);
 665 }
 666
 667
 668 EXPORT_SYMBOL(dma_map_single);
 669 EXPORT_SYMBOL(dma_unmap_single);
 670 EXPORT_SYMBOL(dma_map_sg);
 671 EXPORT_SYMBOL(dma_unmap_sg);
 672 EXPORT_SYMBOL(dma_sync_single_for_cpu);
 673 EXPORT_SYMBOL(dma_sync_single_for_device);
 674 EXPORT_SYMBOL(dma_sync_sg);
 675 EXPORT_SYMBOL(dmabounce_register_dev);
 676 EXPORT_SYMBOL(dmabounce_unregister_dev);
 677
 678 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 679 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 680 MODULE_LICENSE("GPL");