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 struct safe_buffer *find_safe_buffer_dev(struct device *dev,
 209                 dma_addr_t dma_addr, const char *where)
 210 {
 211         if (!dev || !dev->archdata.dmabounce)
 212                 return NULL;
 213         if (dma_mapping_error(dev, dma_addr)) {
 214                 if (dev)
 215                         dev_err(dev, "Trying to %s invalid mapping\n", where);
 216                 else
 217                         pr_err("unknown device: 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 inline dma_addr_t
 224 map_single(struct device *dev, void *ptr, size_t size,
 225                 enum dma_data_direction dir)
 226 {
 227         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 228         dma_addr_t dma_addr;
 229         int needs_bounce = 0;
 230
 231         if (device_info)
 232                 DO_STATS ( device_info->map_op_count++ );
 233
 234         dma_addr = virt_to_dma(dev, ptr);
 235
 236         if (dev->dma_mask) {
 237                 unsigned long mask = *dev->dma_mask;
 238                 unsigned long limit;
 239
 240                 limit = (mask + 1) & ~mask;
 241                 if (limit && size > limit) {
 242                         dev_err(dev, "DMA mapping too big (requested %#x "
 243                                 "mask %#Lx)\n", size, *dev->dma_mask);
 244                         return ~0;
 245                 }
 246
 247                 /*
 248                  * Figure out if we need to bounce from the DMA mask.
 249                  */
 250                 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
 251         }
 252
 253         if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
 254                 struct safe_buffer *buf;
 255
 256                 buf = alloc_safe_buffer(device_info, ptr, size, dir);
 257                 if (buf == 0) {
 258                         dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 259                                __func__, ptr);
 260                         return 0;
 261                 }
 262
 263                 dev_dbg(dev,
 264                         "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 265                         __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 266                         buf->safe, buf->safe_dma_addr);
 267
 268                 if ((dir == DMA_TO_DEVICE) ||
 269                     (dir == DMA_BIDIRECTIONAL)) {
 270                         dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 271                                 __func__, ptr, buf->safe, size);
 272                         memcpy(buf->safe, ptr, size);
 273                 }
 274                 ptr = buf->safe;
 275
 276                 dma_addr = buf->safe_dma_addr;
 277         } else {
 278                 /*
 279                  * We don't need to sync the DMA buffer since
 280                  * it was allocated via the coherent allocators.
 281                  */
 282                 dma_cache_maint(ptr, size, dir);
 283         }
 284
 285         return dma_addr;
 286 }
 287
 288 static inline void
 289 unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 290                 enum dma_data_direction dir)
 291 {
 292         struct safe_buffer *buf = find_safe_buffer_dev(dev, dma_addr, "unmap");
 293
 294         if (buf) {
 295                 BUG_ON(buf->size != size);
 296
 297                 dev_dbg(dev,
 298                         "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 299                         __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 300                         buf->safe, buf->safe_dma_addr);
 301
 302                 DO_STATS(dev->archdata.dmabounce->bounce_count++);
 303
 304                 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 305                         void *ptr = buf->ptr;
 306
 307                         dev_dbg(dev,
 308                                 "%s: copy back safe %p to unsafe %p size %d\n",
 309                                 __func__, buf->safe, ptr, size);
 310                         memcpy(ptr, buf->safe, size);
 311
 312                         /*
 313                          * DMA buffers must have the same cache properties
 314                          * as if they were really used for DMA - which means
 315                          * data must be written back to RAM.  Note that
 316                          * we don't use dmac_flush_range() here for the
 317                          * bidirectional case because we know the cache
 318                          * lines will be coherent with the data written.
 319                          */
 320                         dmac_clean_range(ptr, ptr + size);
 321                         outer_clean_range(__pa(ptr), __pa(ptr) + size);
 322                 }
 323                 free_safe_buffer(dev->archdata.dmabounce, buf);
 324         }
 325 }
 326
 327 /* ************************************************** */
 328
 329 /*
 330  * see if a buffer address is in an 'unsafe' range.  if it is
 331  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 332  * substitute the safe buffer for the unsafe one.
 333  * (basically move the buffer from an unsafe area to a safe one)
 334  */
 335 dma_addr_t
 336 dma_map_single(struct device *dev, void *ptr, size_t size,
 337                 enum dma_data_direction dir)
 338 {
 339         dma_addr_t dma_addr;
 340
 341         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 342                 __func__, ptr, size, dir);
 343
 344         BUG_ON(dir == DMA_NONE);
 345
 346         dma_addr = map_single(dev, ptr, size, dir);
 347
 348         return dma_addr;
 349 }
 350
 351 dma_addr_t dma_map_page(struct device *dev, struct page *page,
 352                         unsigned long offset, size_t size,
 353                         enum dma_data_direction dir)
 354 {
 355         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
 356                 __func__, page, offset, size, dir);
 357
 358         BUG_ON(dir == DMA_NONE);
 359
 360         return map_single(dev, page_address(page) + offset, size, dir);
 361 }
 362 EXPORT_SYMBOL(dma_map_page);
 363
 364 /*
 365  * see if a mapped address was really a "safe" buffer and if so, copy
 366  * the data from the safe buffer back to the unsafe buffer and free up
 367  * the safe buffer.  (basically return things back to the way they
 368  * should be)
 369  */
 370
 371 void
 372 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 373                         enum dma_data_direction dir)
 374 {
 375         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 376                 __func__, (void *) dma_addr, size, dir);
 377
 378         BUG_ON(dir == DMA_NONE);
 379
 380         unmap_single(dev, dma_addr, size, dir);
 381 }
 382
 383 int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 384                 unsigned long off, size_t sz, enum dma_data_direction dir)
 385 {
 386         struct safe_buffer *buf;
 387
 388         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 389                 __func__, addr, off, sz, dir);
 390
 391         buf = find_safe_buffer_dev(dev, addr, __func__);
 392         if (!buf)
 393                 return 1;
 394
 395         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 396                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 397                 buf->safe, buf->safe_dma_addr);
 398
 399         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 400
 401         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 402                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 403                         __func__, buf->safe + off, buf->ptr + off, sz);
 404                 memcpy(buf->ptr + off, buf->safe + off, sz);
 405         }
 406         return 0;
 407 }
 408 EXPORT_SYMBOL(dmabounce_sync_for_cpu);
 409
 410 int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 411                 unsigned long off, size_t sz, enum dma_data_direction dir)
 412 {
 413         struct safe_buffer *buf;
 414
 415         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 416                 __func__, addr, off, sz, dir);
 417
 418         buf = find_safe_buffer_dev(dev, addr, __func__);
 419         if (!buf)
 420                 return 1;
 421
 422         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 423                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 424                 buf->safe, buf->safe_dma_addr);
 425
 426         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 427
 428         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
 429                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
 430                         __func__,buf->ptr + off, buf->safe + off, sz);
 431                 memcpy(buf->safe + off, buf->ptr + off, sz);
 432         }
 433         return 0;
 434 }
 435 EXPORT_SYMBOL(dmabounce_sync_for_device);
 436
 437 static int
 438 dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev, const char *name,
 439                     unsigned long size)
 440 {
 441         pool->size = size;
 442         DO_STATS(pool->allocs = 0);
 443         pool->pool = dma_pool_create(name, dev, size,
 444                                      0 /* byte alignment */,
 445                                      0 /* no page-crossing issues */);
 446
 447         return pool->pool ? 0 : -ENOMEM;
 448 }
 449
 450 int
 451 dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 452                         unsigned long large_buffer_size)
 453 {
 454         struct dmabounce_device_info *device_info;
 455         int ret;
 456
 457         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 458         if (!device_info) {
 459                 dev_err(dev,
 460                         "Could not allocated dmabounce_device_info\n");
 461                 return -ENOMEM;
 462         }
 463
 464         ret = dmabounce_init_pool(&device_info->small, dev,
 465                                   "small_dmabounce_pool", small_buffer_size);
 466         if (ret) {
 467                 dev_err(dev,
 468                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 469                         small_buffer_size);
 470                 goto err_free;
 471         }
 472
 473         if (large_buffer_size) {
 474                 ret = dmabounce_init_pool(&device_info->large, dev,
 475                                           "large_dmabounce_pool",
 476                                           large_buffer_size);
 477                 if (ret) {
 478                         dev_err(dev,
 479                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 480                                 large_buffer_size);
 481                         goto err_destroy;
 482                 }
 483         }
 484
 485         device_info->dev = dev;
 486         INIT_LIST_HEAD(&device_info->safe_buffers);
 487         rwlock_init(&device_info->lock);
 488
 489 #ifdef STATS
 490         device_info->total_allocs = 0;
 491         device_info->map_op_count = 0;
 492         device_info->bounce_count = 0;
 493         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 494 #endif
 495
 496         dev->archdata.dmabounce = device_info;
 497
 498         dev_info(dev, "dmabounce: registered device\n");
 499
 500         return 0;
 501
 502  err_destroy:
 503         dma_pool_destroy(device_info->small.pool);
 504  err_free:
 505         kfree(device_info);
 506         return ret;
 507 }
 508
 509 void
 510 dmabounce_unregister_dev(struct device *dev)
 511 {
 512         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 513
 514         dev->archdata.dmabounce = NULL;
 515
 516         if (!device_info) {
 517                 dev_warn(dev,
 518                          "Never registered with dmabounce but attempting"
 519                          "to unregister!\n");
 520                 return;
 521         }
 522
 523         if (!list_empty(&device_info->safe_buffers)) {
 524                 dev_err(dev,
 525                         "Removing from dmabounce with pending buffers!\n");
 526                 BUG();
 527         }
 528
 529         if (device_info->small.pool)
 530                 dma_pool_destroy(device_info->small.pool);
 531         if (device_info->large.pool)
 532                 dma_pool_destroy(device_info->large.pool);
 533
 534 #ifdef STATS
 535         if (device_info->attr_res == 0)
 536                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 537 #endif
 538
 539         kfree(device_info);
 540
 541         dev_info(dev, "dmabounce: device unregistered\n");
 542 }
 543
 544
 545 EXPORT_SYMBOL(dma_map_single);
 546 EXPORT_SYMBOL(dma_unmap_single);
 547 EXPORT_SYMBOL(dmabounce_register_dev);
 548 EXPORT_SYMBOL(dmabounce_unregister_dev);
 549
 550 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 551 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 552 MODULE_LICENSE("GPL");