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/page-flags.h>
  29 #include <linux/device.h>
  30 #include <linux/dma-mapping.h>
  31 #include <linux/dmapool.h>
  32 #include <linux/list.h>
  33 #include <linux/scatterlist.h>
  34
  35 #include <asm/cacheflush.h>
  36 #include <asm/dma-iommu.h>
  37
  38 #undef STATS
  39
  40 #ifdef STATS
  41 #define DO_STATS(X) do { X ; } while (0)
  42 #else
  43 #define DO_STATS(X) do { } while (0)
  44 #endif
  45
  46 /* ************************************************** */
  47
  48 struct safe_buffer {
  49         struct list_head node;
  50
  51         /* original request */
  52         void            *ptr;
  53         size_t          size;
  54         int             direction;
  55
  56         /* safe buffer info */
  57         struct dmabounce_pool *pool;
  58         void            *safe;
  59         dma_addr_t      safe_dma_addr;
  60 };
  61
  62 struct dmabounce_pool {
  63         unsigned long   size;
  64         struct dma_pool *pool;
  65 #ifdef STATS
  66         unsigned long   allocs;
  67 #endif
  68 };
  69
  70 struct dmabounce_device_info {
  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         int attr_res;
  78 #endif
  79         struct dmabounce_pool   small;
  80         struct dmabounce_pool   large;
  81
  82         rwlock_t lock;
  83
  84         int (*needs_bounce)(struct device *, dma_addr_t, size_t);
  85 };
  86
  87 #ifdef STATS
  88 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
  89                               char *buf)
  90 {
  91         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
  92         return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
  93                 device_info->small.allocs,
  94                 device_info->large.allocs,
  95                 device_info->total_allocs - device_info->small.allocs -
  96                         device_info->large.allocs,
  97                 device_info->total_allocs,
  98                 device_info->map_op_count,
  99                 device_info->bounce_count);
 100 }
 101
 102 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
 103 #endif
 104
 105
 106 /* allocate a 'safe' buffer and keep track of it */
 107 static inline struct safe_buffer *
 108 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 109                   size_t size, enum dma_data_direction dir)
 110 {
 111         struct safe_buffer *buf;
 112         struct dmabounce_pool *pool;
 113         struct device *dev = device_info->dev;
 114         unsigned long flags;
 115
 116         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 117                 __func__, ptr, size, dir);
 118
 119         if (size <= device_info->small.size) {
 120                 pool = &device_info->small;
 121         } else if (size <= device_info->large.size) {
 122                 pool = &device_info->large;
 123         } else {
 124                 pool = NULL;
 125         }
 126
 127         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 128         if (buf == NULL) {
 129                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 130                 return NULL;
 131         }
 132
 133         buf->ptr = ptr;
 134         buf->size = size;
 135         buf->direction = dir;
 136         buf->pool = pool;
 137
 138         if (pool) {
 139                 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
 140                                            &buf->safe_dma_addr);
 141         } else {
 142                 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
 143                                                GFP_ATOMIC);
 144         }
 145
 146         if (buf->safe == NULL) {
 147                 dev_warn(dev,
 148                          "%s: could not alloc dma memory (size=%d)\n",
 149                          __func__, size);
 150                 kfree(buf);
 151                 return NULL;
 152         }
 153
 154 #ifdef STATS
 155         if (pool)
 156                 pool->allocs++;
 157         device_info->total_allocs++;
 158 #endif
 159
 160         write_lock_irqsave(&device_info->lock, flags);
 161         list_add(&buf->node, &device_info->safe_buffers);
 162         write_unlock_irqrestore(&device_info->lock, flags);
 163
 164         return buf;
 165 }
 166
 167 /* determine if a buffer is from our "safe" pool */
 168 static inline struct safe_buffer *
 169 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 170 {
 171         struct safe_buffer *b, *rb = NULL;
 172         unsigned long flags;
 173
 174         read_lock_irqsave(&device_info->lock, flags);
 175
 176         list_for_each_entry(b, &device_info->safe_buffers, node)
 177                 if (b->safe_dma_addr <= safe_dma_addr &&
 178                     b->safe_dma_addr + b->size > safe_dma_addr) {
 179                         rb = b;
 180                         break;
 181                 }
 182
 183         read_unlock_irqrestore(&device_info->lock, flags);
 184         return rb;
 185 }
 186
 187 static inline void
 188 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 189 {
 190         unsigned long flags;
 191
 192         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 193
 194         write_lock_irqsave(&device_info->lock, flags);
 195
 196         list_del(&buf->node);
 197
 198         write_unlock_irqrestore(&device_info->lock, flags);
 199
 200         if (buf->pool)
 201                 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
 202         else
 203                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 204                                     buf->safe_dma_addr);
 205
 206         kfree(buf);
 207 }
 208
 209 /* ************************************************** */
 210
 211 static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
 212                 dma_addr_t dma_addr, const char *where)
 213 {
 214         if (!dev || !dev->archdata.dmabounce)
 215                 return NULL;
 216         if (dma_mapping_error(dev, dma_addr)) {
 217                 dev_err(dev, "Trying to %s invalid mapping\n", where);
 218                 return NULL;
 219         }
 220         return find_safe_buffer(dev->archdata.dmabounce, dma_addr);
 221 }
 222
 223 static int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
 224 {
 225         if (!dev || !dev->archdata.dmabounce)
 226                 return 0;
 227
 228         if (dev->dma_mask) {
 229                 unsigned long limit, mask = *dev->dma_mask;
 230
 231                 limit = (mask + 1) & ~mask;
 232                 if (limit && size > limit) {
 233                         dev_err(dev, "DMA mapping too big (requested %#x "
 234                                 "mask %#Lx)\n", size, *dev->dma_mask);
 235                         return -E2BIG;
 236                 }
 237
 238                 /* Figure out if we need to bounce from the DMA mask. */
 239                 if ((dma_addr | (dma_addr + size - 1)) & ~mask)
 240                         return 1;
 241         }
 242
 243         return !!dev->archdata.dmabounce->needs_bounce(dev, dma_addr, size);
 244 }
 245
 246 static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
 247                                     enum dma_data_direction dir,
 248                                     unsigned long attrs)
 249 {
 250         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 251         struct safe_buffer *buf;
 252
 253         if (device_info)
 254                 DO_STATS ( device_info->map_op_count++ );
 255
 256         buf = alloc_safe_buffer(device_info, ptr, size, dir);
 257         if (buf == NULL) {
 258                 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 259                        __func__, ptr);
 260                 return DMA_MAPPING_ERROR;
 261         }
 262
 263         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 264                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 265                 buf->safe, buf->safe_dma_addr);
 266
 267         if ((dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) &&
 268             !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
 269                 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 270                         __func__, ptr, buf->safe, size);
 271                 memcpy(buf->safe, ptr, size);
 272         }
 273
 274         return buf->safe_dma_addr;
 275 }
 276
 277 static inline void unmap_single(struct device *dev, struct safe_buffer *buf,
 278                                 size_t size, enum dma_data_direction dir,
 279                                 unsigned long attrs)
 280 {
 281         BUG_ON(buf->size != size);
 282         BUG_ON(buf->direction != dir);
 283
 284         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 285                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 286                 buf->safe, buf->safe_dma_addr);
 287
 288         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 289
 290         if ((dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) &&
 291             !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
 292                 void *ptr = buf->ptr;
 293
 294                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 295                         __func__, buf->safe, ptr, size);
 296                 memcpy(ptr, buf->safe, size);
 297
 298                 /*
 299                  * Since we may have written to a page cache page,
 300                  * we need to ensure that the data will be coherent
 301                  * with user mappings.
 302                  */
 303                 __cpuc_flush_dcache_area(ptr, size);
 304         }
 305         free_safe_buffer(dev->archdata.dmabounce, buf);
 306 }
 307
 308 /* ************************************************** */
 309
 310 /*
 311  * see if a buffer address is in an 'unsafe' range.  if it is
 312  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 313  * substitute the safe buffer for the unsafe one.
 314  * (basically move the buffer from an unsafe area to a safe one)
 315  */
 316 static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page,
 317                 unsigned long offset, size_t size, enum dma_data_direction dir,
 318                 unsigned long attrs)
 319 {
 320         dma_addr_t dma_addr;
 321         int ret;
 322
 323         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
 324                 __func__, page, offset, size, dir);
 325
 326         dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset;
 327
 328         ret = needs_bounce(dev, dma_addr, size);
 329         if (ret < 0)
 330                 return DMA_MAPPING_ERROR;
 331
 332         if (ret == 0) {
 333                 arm_dma_ops.sync_single_for_device(dev, dma_addr, size, dir);
 334                 return dma_addr;
 335         }
 336
 337         if (PageHighMem(page)) {
 338                 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
 339                 return DMA_MAPPING_ERROR;
 340         }
 341
 342         return map_single(dev, page_address(page) + offset, size, dir, attrs);
 343 }
 344
 345 /*
 346  * see if a mapped address was really a "safe" buffer and if so, copy
 347  * the data from the safe buffer back to the unsafe buffer and free up
 348  * the safe buffer.  (basically return things back to the way they
 349  * should be)
 350  */
 351 static void dmabounce_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
 352                 enum dma_data_direction dir, unsigned long attrs)
 353 {
 354         struct safe_buffer *buf;
 355
 356         dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n",
 357                 __func__, dma_addr, size, dir);
 358
 359         buf = find_safe_buffer_dev(dev, dma_addr, __func__);
 360         if (!buf) {
 361                 arm_dma_ops.sync_single_for_cpu(dev, dma_addr, size, dir);
 362                 return;
 363         }
 364
 365         unmap_single(dev, buf, size, dir, attrs);
 366 }
 367
 368 static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 369                 size_t sz, enum dma_data_direction dir)
 370 {
 371         struct safe_buffer *buf;
 372         unsigned long off;
 373
 374         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
 375                 __func__, addr, sz, dir);
 376
 377         buf = find_safe_buffer_dev(dev, addr, __func__);
 378         if (!buf)
 379                 return 1;
 380
 381         off = addr - buf->safe_dma_addr;
 382
 383         BUG_ON(buf->direction != dir);
 384
 385         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
 386                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
 387                 buf->safe, buf->safe_dma_addr);
 388
 389         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 390
 391         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 392                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 393                         __func__, buf->safe + off, buf->ptr + off, sz);
 394                 memcpy(buf->ptr + off, buf->safe + off, sz);
 395         }
 396         return 0;
 397 }
 398
 399 static void dmabounce_sync_for_cpu(struct device *dev,
 400                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 401 {
 402         if (!__dmabounce_sync_for_cpu(dev, handle, size, dir))
 403                 return;
 404
 405         arm_dma_ops.sync_single_for_cpu(dev, handle, size, dir);
 406 }
 407
 408 static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 409                 size_t sz, enum dma_data_direction dir)
 410 {
 411         struct safe_buffer *buf;
 412         unsigned long off;
 413
 414         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
 415                 __func__, addr, sz, dir);
 416
 417         buf = find_safe_buffer_dev(dev, addr, __func__);
 418         if (!buf)
 419                 return 1;
 420
 421         off = addr - buf->safe_dma_addr;
 422
 423         BUG_ON(buf->direction != dir);
 424
 425         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
 426                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
 427                 buf->safe, buf->safe_dma_addr);
 428
 429         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 430
 431         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
 432                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
 433                         __func__,buf->ptr + off, buf->safe + off, sz);
 434                 memcpy(buf->safe + off, buf->ptr + off, sz);
 435         }
 436         return 0;
 437 }
 438
 439 static void dmabounce_sync_for_device(struct device *dev,
 440                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 441 {
 442         if (!__dmabounce_sync_for_device(dev, handle, size, dir))
 443                 return;
 444
 445         arm_dma_ops.sync_single_for_device(dev, handle, size, dir);
 446 }
 447
 448 static int dmabounce_dma_supported(struct device *dev, u64 dma_mask)
 449 {
 450         if (dev->archdata.dmabounce)
 451                 return 0;
 452
 453         return arm_dma_ops.dma_supported(dev, dma_mask);
 454 }
 455
 456 static const struct dma_map_ops dmabounce_ops = {
 457         .alloc                  = arm_dma_alloc,
 458         .free                   = arm_dma_free,
 459         .mmap                   = arm_dma_mmap,
 460         .get_sgtable            = arm_dma_get_sgtable,
 461         .map_page               = dmabounce_map_page,
 462         .unmap_page             = dmabounce_unmap_page,
 463         .sync_single_for_cpu    = dmabounce_sync_for_cpu,
 464         .sync_single_for_device = dmabounce_sync_for_device,
 465         .map_sg                 = arm_dma_map_sg,
 466         .unmap_sg               = arm_dma_unmap_sg,
 467         .sync_sg_for_cpu        = arm_dma_sync_sg_for_cpu,
 468         .sync_sg_for_device     = arm_dma_sync_sg_for_device,
 469         .dma_supported          = dmabounce_dma_supported,
 470 };
 471
 472 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
 473                 const char *name, unsigned long size)
 474 {
 475         pool->size = size;
 476         DO_STATS(pool->allocs = 0);
 477         pool->pool = dma_pool_create(name, dev, size,
 478                                      0 /* byte alignment */,
 479                                      0 /* no page-crossing issues */);
 480
 481         return pool->pool ? 0 : -ENOMEM;
 482 }
 483
 484 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 485                 unsigned long large_buffer_size,
 486                 int (*needs_bounce_fn)(struct device *, dma_addr_t, size_t))
 487 {
 488         struct dmabounce_device_info *device_info;
 489         int ret;
 490
 491         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 492         if (!device_info) {
 493                 dev_err(dev,
 494                         "Could not allocated dmabounce_device_info\n");
 495                 return -ENOMEM;
 496         }
 497
 498         ret = dmabounce_init_pool(&device_info->small, dev,
 499                                   "small_dmabounce_pool", small_buffer_size);
 500         if (ret) {
 501                 dev_err(dev,
 502                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 503                         small_buffer_size);
 504                 goto err_free;
 505         }
 506
 507         if (large_buffer_size) {
 508                 ret = dmabounce_init_pool(&device_info->large, dev,
 509                                           "large_dmabounce_pool",
 510                                           large_buffer_size);
 511                 if (ret) {
 512                         dev_err(dev,
 513                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 514                                 large_buffer_size);
 515                         goto err_destroy;
 516                 }
 517         }
 518
 519         device_info->dev = dev;
 520         INIT_LIST_HEAD(&device_info->safe_buffers);
 521         rwlock_init(&device_info->lock);
 522         device_info->needs_bounce = needs_bounce_fn;
 523
 524 #ifdef STATS
 525         device_info->total_allocs = 0;
 526         device_info->map_op_count = 0;
 527         device_info->bounce_count = 0;
 528         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 529 #endif
 530
 531         dev->archdata.dmabounce = device_info;
 532         set_dma_ops(dev, &dmabounce_ops);
 533
 534         dev_info(dev, "dmabounce: registered device\n");
 535
 536         return 0;
 537
 538  err_destroy:
 539         dma_pool_destroy(device_info->small.pool);
 540  err_free:
 541         kfree(device_info);
 542         return ret;
 543 }
 544 EXPORT_SYMBOL(dmabounce_register_dev);
 545
 546 void dmabounce_unregister_dev(struct device *dev)
 547 {
 548         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 549
 550         dev->archdata.dmabounce = NULL;
 551         set_dma_ops(dev, NULL);
 552
 553         if (!device_info) {
 554                 dev_warn(dev,
 555                          "Never registered with dmabounce but attempting"
 556                          "to unregister!\n");
 557                 return;
 558         }
 559
 560         if (!list_empty(&device_info->safe_buffers)) {
 561                 dev_err(dev,
 562                         "Removing from dmabounce with pending buffers!\n");
 563                 BUG();
 564         }
 565
 566         if (device_info->small.pool)
 567                 dma_pool_destroy(device_info->small.pool);
 568         if (device_info->large.pool)
 569                 dma_pool_destroy(device_info->large.pool);
 570
 571 #ifdef STATS
 572         if (device_info->attr_res == 0)
 573                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 574 #endif
 575
 576         kfree(device_info);
 577
 578         dev_info(dev, "dmabounce: device unregistered\n");
 579 }
 580 EXPORT_SYMBOL(dmabounce_unregister_dev);
 581
 582 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 583 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 584 MODULE_LICENSE("GPL");