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