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