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 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 #include <linux/scatterlist.h>
  33
  34 #include <asm/cacheflush.h>
  35
  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 device *dev;
  70         struct list_head safe_buffers;
  71 #ifdef STATS
  72         unsigned long total_allocs;
  73         unsigned long map_op_count;
  74         unsigned long bounce_count;
  75         int attr_res;
  76 #endif
  77         struct dmabounce_pool   small;
  78         struct dmabounce_pool   large;
  79
  80         rwlock_t lock;
  81 };
  82
  83 #ifdef STATS
  84 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
  85                               char *buf)
  86 {
  87         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
  88         return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
  89                 device_info->small.allocs,
  90                 device_info->large.allocs,
  91                 device_info->total_allocs - device_info->small.allocs -
  92                         device_info->large.allocs,
  93                 device_info->total_allocs,
  94                 device_info->map_op_count,
  95                 device_info->bounce_count);
  96 }
  97
  98 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
  99 #endif
 100
 101
 102 /* allocate a 'safe' buffer and keep track of it */
 103 static inline struct safe_buffer *
 104 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 105                   size_t size, enum dma_data_direction dir)
 106 {
 107         struct safe_buffer *buf;
 108         struct dmabounce_pool *pool;
 109         struct device *dev = device_info->dev;
 110         unsigned long flags;
 111
 112         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 113                 __func__, ptr, size, dir);
 114
 115         if (size <= device_info->small.size) {
 116                 pool = &device_info->small;
 117         } else if (size <= device_info->large.size) {
 118                 pool = &device_info->large;
 119         } else {
 120                 pool = NULL;
 121         }
 122
 123         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 124         if (buf == NULL) {
 125                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 126                 return NULL;
 127         }
 128
 129         buf->ptr = ptr;
 130         buf->size = size;
 131         buf->direction = dir;
 132         buf->pool = pool;
 133
 134         if (pool) {
 135                 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
 136                                            &buf->safe_dma_addr);
 137         } else {
 138                 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
 139                                                GFP_ATOMIC);
 140         }
 141
 142         if (buf->safe == NULL) {
 143                 dev_warn(dev,
 144                          "%s: could not alloc dma memory (size=%d)\n",
 145                          __func__, size);
 146                 kfree(buf);
 147                 return NULL;
 148         }
 149
 150 #ifdef STATS
 151         if (pool)
 152                 pool->allocs++;
 153         device_info->total_allocs++;
 154 #endif
 155
 156         write_lock_irqsave(&device_info->lock, flags);
 157
 158         list_add(&buf->node, &device_info->safe_buffers);
 159
 160         write_unlock_irqrestore(&device_info->lock, flags);
 161
 162         return buf;
 163 }
 164
 165 /* determine if a buffer is from our "safe" pool */
 166 static inline struct safe_buffer *
 167 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 168 {
 169         struct safe_buffer *b, *rb = NULL;
 170         unsigned long flags;
 171
 172         read_lock_irqsave(&device_info->lock, flags);
 173
 174         list_for_each_entry(b, &device_info->safe_buffers, node)
 175                 if (b->safe_dma_addr == safe_dma_addr) {
 176                         rb = b;
 177                         break;
 178                 }
 179
 180         read_unlock_irqrestore(&device_info->lock, flags);
 181         return rb;
 182 }
 183
 184 static inline void
 185 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 186 {
 187         unsigned long flags;
 188
 189         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 190
 191         write_lock_irqsave(&device_info->lock, flags);
 192
 193         list_del(&buf->node);
 194
 195         write_unlock_irqrestore(&device_info->lock, flags);
 196
 197         if (buf->pool)
 198                 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
 199         else
 200                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 201                                     buf->safe_dma_addr);
 202
 203         kfree(buf);
 204 }
 205
 206 /* ************************************************** */
 207
 208 static inline dma_addr_t
 209 map_single(struct device *dev, void *ptr, size_t size,
 210                 enum dma_data_direction dir)
 211 {
 212         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 213         dma_addr_t dma_addr;
 214         int needs_bounce = 0;
 215
 216         if (device_info)
 217                 DO_STATS ( device_info->map_op_count++ );
 218
 219         dma_addr = virt_to_dma(dev, ptr);
 220
 221         if (dev->dma_mask) {
 222                 unsigned long mask = *dev->dma_mask;
 223                 unsigned long limit;
 224
 225                 limit = (mask + 1) & ~mask;
 226                 if (limit && size > limit) {
 227                         dev_err(dev, "DMA mapping too big (requested %#x "
 228                                 "mask %#Lx)\n", size, *dev->dma_mask);
 229                         return ~0;
 230                 }
 231
 232                 /*
 233                  * Figure out if we need to bounce from the DMA mask.
 234                  */
 235                 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
 236         }
 237
 238         if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
 239                 struct safe_buffer *buf;
 240
 241                 buf = alloc_safe_buffer(device_info, ptr, size, dir);
 242                 if (buf == 0) {
 243                         dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 244                                __func__, ptr);
 245                         return 0;
 246                 }
 247
 248                 dev_dbg(dev,
 249                         "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 250                         __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 251                         buf->safe, buf->safe_dma_addr);
 252
 253                 if ((dir == DMA_TO_DEVICE) ||
 254                     (dir == DMA_BIDIRECTIONAL)) {
 255                         dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 256                                 __func__, ptr, buf->safe, size);
 257                         memcpy(buf->safe, ptr, size);
 258                 }
 259                 ptr = buf->safe;
 260
 261                 dma_addr = buf->safe_dma_addr;
 262         } else {
 263                 /*
 264                  * We don't need to sync the DMA buffer since
 265                  * it was allocated via the coherent allocators.
 266                  */
 267                 dma_cache_maint(ptr, size, dir);
 268         }
 269
 270         return dma_addr;
 271 }
 272
 273 static inline void
 274 unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 275                 enum dma_data_direction dir)
 276 {
 277         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 278         struct safe_buffer *buf = NULL;
 279
 280         /*
 281          * Trying to unmap an invalid mapping
 282          */
 283         if (dma_mapping_error(dev, dma_addr)) {
 284                 dev_err(dev, "Trying to unmap invalid mapping\n");
 285                 return;
 286         }
 287
 288         if (device_info)
 289                 buf = find_safe_buffer(device_info, dma_addr);
 290
 291         if (buf) {
 292                 BUG_ON(buf->size != size);
 293
 294                 dev_dbg(dev,
 295                         "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 296                         __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 297                         buf->safe, buf->safe_dma_addr);
 298
 299                 DO_STATS ( device_info->bounce_count++ );
 300
 301                 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 302                         void *ptr = buf->ptr;
 303
 304                         dev_dbg(dev,
 305                                 "%s: copy back safe %p to unsafe %p size %d\n",
 306                                 __func__, buf->safe, ptr, size);
 307                         memcpy(ptr, buf->safe, size);
 308
 309                         /*
 310                          * DMA buffers must have the same cache properties
 311                          * as if they were really used for DMA - which means
 312                          * data must be written back to RAM.  Note that
 313                          * we don't use dmac_flush_range() here for the
 314                          * bidirectional case because we know the cache
 315                          * lines will be coherent with the data written.
 316                          */
 317                         dmac_clean_range(ptr, ptr + size);
 318                         outer_clean_range(__pa(ptr), __pa(ptr) + size);
 319                 }
 320                 free_safe_buffer(device_info, buf);
 321         }
 322 }
 323
 324 static int sync_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 (dma=%#x) mapped to %p (dma=%#x)\n",
 358                         __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 359                         buf->safe, 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                 return 0;
 386         } else {
 387                 return 1;
 388         }
 389 }
 390
 391 /* ************************************************** */
 392
 393 /*
 394  * see if a buffer address is in an 'unsafe' range.  if it is
 395  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 396  * substitute the safe buffer for the unsafe one.
 397  * (basically move the buffer from an unsafe area to a safe one)
 398  */
 399 dma_addr_t
 400 dma_map_single(struct device *dev, void *ptr, size_t size,
 401                 enum dma_data_direction dir)
 402 {
 403         dma_addr_t dma_addr;
 404
 405         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 406                 __func__, ptr, size, dir);
 407
 408         BUG_ON(dir == DMA_NONE);
 409
 410         dma_addr = map_single(dev, ptr, size, dir);
 411
 412         return dma_addr;
 413 }
 414
 415 dma_addr_t dma_map_page(struct device *dev, struct page *page,
 416                         unsigned long offset, size_t size,
 417                         enum dma_data_direction dir)
 418 {
 419         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
 420                 __func__, page, offset, size, dir);
 421
 422         BUG_ON(dir == DMA_NONE);
 423
 424         return map_single(dev, page_address(page) + offset, size, dir);
 425 }
 426 EXPORT_SYMBOL(dma_map_page);
 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 void dma_sync_single_range_for_cpu(struct device *dev, dma_addr_t dma_addr,
 448                                    unsigned long offset, size_t size,
 449                                    enum dma_data_direction dir)
 450 {
 451         dev_dbg(dev, "%s(dma=%#x,off=%#lx,size=%zx,dir=%x)\n",
 452                 __func__, dma_addr, offset, size, dir);
 453
 454         if (sync_single(dev, dma_addr, offset + size, dir))
 455                 dma_cache_maint(dma_to_virt(dev, dma_addr) + offset, size, dir);
 456 }
 457 EXPORT_SYMBOL(dma_sync_single_range_for_cpu);
 458
 459 void dma_sync_single_range_for_device(struct device *dev, dma_addr_t dma_addr,
 460                                       unsigned long offset, size_t size,
 461                                       enum dma_data_direction dir)
 462 {
 463         dev_dbg(dev, "%s(dma=%#x,off=%#lx,size=%zx,dir=%x)\n",
 464                 __func__, dma_addr, offset, size, dir);
 465
 466         if (sync_single(dev, dma_addr, offset + size, dir))
 467                 dma_cache_maint(dma_to_virt(dev, dma_addr) + offset, size, dir);
 468 }
 469 EXPORT_SYMBOL(dma_sync_single_range_for_device);
 470
 471 int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 472                 unsigned long off, size_t sz, enum dma_data_direction dir)
 473 {
 474         dev_dbg(dev, "%s(dma=%#lx,off=%#lx,sz=%zx,dir=%x)\n",
 475                 __func__, addr, off, sz, dir);
 476         return sync_single(dev, addr, off + sz, dir);
 477 }
 478 EXPORT_SYMBOL(dmabounce_sync_for_cpu);
 479
 480 int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 481                 unsigned long off, size_t sz, enum dma_data_direction dir)
 482 {
 483         dev_dbg(dev, "%s(dma=%#lx,off=%#lx,sz=%zx,dir=%x)\n",
 484                 __func__, addr, off, sz, dir);
 485         return sync_single(dev, addr, off + sz, dir);
 486 }
 487 EXPORT_SYMBOL(dmabounce_sync_for_device);
 488
 489 static int
 490 dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev, const char *name,
 491                     unsigned long size)
 492 {
 493         pool->size = size;
 494         DO_STATS(pool->allocs = 0);
 495         pool->pool = dma_pool_create(name, dev, size,
 496                                      0 /* byte alignment */,
 497                                      0 /* no page-crossing issues */);
 498
 499         return pool->pool ? 0 : -ENOMEM;
 500 }
 501
 502 int
 503 dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 504                         unsigned long large_buffer_size)
 505 {
 506         struct dmabounce_device_info *device_info;
 507         int ret;
 508
 509         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 510         if (!device_info) {
 511                 dev_err(dev,
 512                         "Could not allocated dmabounce_device_info\n");
 513                 return -ENOMEM;
 514         }
 515
 516         ret = dmabounce_init_pool(&device_info->small, dev,
 517                                   "small_dmabounce_pool", small_buffer_size);
 518         if (ret) {
 519                 dev_err(dev,
 520                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 521                         small_buffer_size);
 522                 goto err_free;
 523         }
 524
 525         if (large_buffer_size) {
 526                 ret = dmabounce_init_pool(&device_info->large, dev,
 527                                           "large_dmabounce_pool",
 528                                           large_buffer_size);
 529                 if (ret) {
 530                         dev_err(dev,
 531                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 532                                 large_buffer_size);
 533                         goto err_destroy;
 534                 }
 535         }
 536
 537         device_info->dev = dev;
 538         INIT_LIST_HEAD(&device_info->safe_buffers);
 539         rwlock_init(&device_info->lock);
 540
 541 #ifdef STATS
 542         device_info->total_allocs = 0;
 543         device_info->map_op_count = 0;
 544         device_info->bounce_count = 0;
 545         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 546 #endif
 547
 548         dev->archdata.dmabounce = device_info;
 549
 550         dev_info(dev, "dmabounce: registered device\n");
 551
 552         return 0;
 553
 554  err_destroy:
 555         dma_pool_destroy(device_info->small.pool);
 556  err_free:
 557         kfree(device_info);
 558         return ret;
 559 }
 560
 561 void
 562 dmabounce_unregister_dev(struct device *dev)
 563 {
 564         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 565
 566         dev->archdata.dmabounce = NULL;
 567
 568         if (!device_info) {
 569                 dev_warn(dev,
 570                          "Never registered with dmabounce but attempting"
 571                          "to unregister!\n");
 572                 return;
 573         }
 574
 575         if (!list_empty(&device_info->safe_buffers)) {
 576                 dev_err(dev,
 577                         "Removing from dmabounce with pending buffers!\n");
 578                 BUG();
 579         }
 580
 581         if (device_info->small.pool)
 582                 dma_pool_destroy(device_info->small.pool);
 583         if (device_info->large.pool)
 584                 dma_pool_destroy(device_info->large.pool);
 585
 586 #ifdef STATS
 587         if (device_info->attr_res == 0)
 588                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 589 #endif
 590
 591         kfree(device_info);
 592
 593         dev_info(dev, "dmabounce: device unregistered\n");
 594 }
 595
 596
 597 EXPORT_SYMBOL(dma_map_single);
 598 EXPORT_SYMBOL(dma_unmap_single);
 599 EXPORT_SYMBOL(dmabounce_register_dev);
 600 EXPORT_SYMBOL(dmabounce_unregister_dev);
 601
 602 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 603 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 604 MODULE_LICENSE("GPL");