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         list_add(&buf->node, &device_info->safe_buffers);
 158         write_unlock_irqrestore(&device_info->lock, flags);
 159
 160         return buf;
 161 }
 162
 163 /* determine if a buffer is from our "safe" pool */
 164 static inline struct safe_buffer *
 165 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 166 {
 167         struct safe_buffer *b, *rb = NULL;
 168         unsigned long flags;
 169
 170         read_lock_irqsave(&device_info->lock, flags);
 171
 172         list_for_each_entry(b, &device_info->safe_buffers, node)
 173                 if (b->safe_dma_addr == safe_dma_addr) {
 174                         rb = b;
 175                         break;
 176                 }
 177
 178         read_unlock_irqrestore(&device_info->lock, flags);
 179         return rb;
 180 }
 181
 182 static inline void
 183 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 184 {
 185         unsigned long flags;
 186
 187         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 188
 189         write_lock_irqsave(&device_info->lock, flags);
 190
 191         list_del(&buf->node);
 192
 193         write_unlock_irqrestore(&device_info->lock, flags);
 194
 195         if (buf->pool)
 196                 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
 197         else
 198                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 199                                     buf->safe_dma_addr);
 200
 201         kfree(buf);
 202 }
 203
 204 /* ************************************************** */
 205
 206 static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
 207                 dma_addr_t dma_addr, const char *where)
 208 {
 209         if (!dev || !dev->archdata.dmabounce)
 210                 return NULL;
 211         if (dma_mapping_error(dev, dma_addr)) {
 212                 if (dev)
 213                         dev_err(dev, "Trying to %s invalid mapping\n", where);
 214                 else
 215                         pr_err("unknown device: Trying to %s invalid mapping\n", where);
 216                 return NULL;
 217         }
 218         return find_safe_buffer(dev->archdata.dmabounce, dma_addr);
 219 }
 220
 221 static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
 222                 enum dma_data_direction dir)
 223 {
 224         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 225         dma_addr_t dma_addr;
 226         int needs_bounce = 0;
 227
 228         if (device_info)
 229                 DO_STATS ( device_info->map_op_count++ );
 230
 231         dma_addr = virt_to_dma(dev, ptr);
 232
 233         if (dev->dma_mask) {
 234                 unsigned long mask = *dev->dma_mask;
 235                 unsigned long limit;
 236
 237                 limit = (mask + 1) & ~mask;
 238                 if (limit && size > limit) {
 239                         dev_err(dev, "DMA mapping too big (requested %#x "
 240                                 "mask %#Lx)\n", size, *dev->dma_mask);
 241                         return ~0;
 242                 }
 243
 244                 /*
 245                  * Figure out if we need to bounce from the DMA mask.
 246                  */
 247                 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
 248         }
 249
 250         if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
 251                 struct safe_buffer *buf;
 252
 253                 buf = alloc_safe_buffer(device_info, ptr, size, dir);
 254                 if (buf == 0) {
 255                         dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 256                                __func__, ptr);
 257                         return 0;
 258                 }
 259
 260                 dev_dbg(dev,
 261                         "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 262                         __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 263                         buf->safe, buf->safe_dma_addr);
 264
 265                 if ((dir == DMA_TO_DEVICE) ||
 266                     (dir == DMA_BIDIRECTIONAL)) {
 267                         dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 268                                 __func__, ptr, buf->safe, size);
 269                         memcpy(buf->safe, ptr, size);
 270                 }
 271                 ptr = buf->safe;
 272
 273                 dma_addr = buf->safe_dma_addr;
 274         } else {
 275                 /*
 276                  * We don't need to sync the DMA buffer since
 277                  * it was allocated via the coherent allocators.
 278                  */
 279                 dma_cache_maint(ptr, size, dir);
 280         }
 281
 282         return dma_addr;
 283 }
 284
 285 static inline void unmap_single(struct device *dev, dma_addr_t dma_addr,
 286                 size_t size, enum dma_data_direction dir)
 287 {
 288         struct safe_buffer *buf = find_safe_buffer_dev(dev, dma_addr, "unmap");
 289
 290         if (buf) {
 291                 BUG_ON(buf->size != size);
 292
 293                 dev_dbg(dev,
 294                         "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 295                         __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 296                         buf->safe, buf->safe_dma_addr);
 297
 298                 DO_STATS(dev->archdata.dmabounce->bounce_count++);
 299
 300                 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 301                         void *ptr = buf->ptr;
 302
 303                         dev_dbg(dev,
 304                                 "%s: copy back safe %p to unsafe %p size %d\n",
 305                                 __func__, buf->safe, ptr, size);
 306                         memcpy(ptr, buf->safe, size);
 307
 308                         /*
 309                          * DMA buffers must have the same cache properties
 310                          * as if they were really used for DMA - which means
 311                          * data must be written back to RAM.  Note that
 312                          * we don't use dmac_flush_range() here for the
 313                          * bidirectional case because we know the cache
 314                          * lines will be coherent with the data written.
 315                          */
 316                         dmac_clean_range(ptr, ptr + size);
 317                         outer_clean_range(__pa(ptr), __pa(ptr) + size);
 318                 }
 319                 free_safe_buffer(dev->archdata.dmabounce, buf);
 320         }
 321 }
 322
 323 /* ************************************************** */
 324
 325 /*
 326  * see if a buffer address is in an 'unsafe' range.  if it is
 327  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 328  * substitute the safe buffer for the unsafe one.
 329  * (basically move the buffer from an unsafe area to a safe one)
 330  */
 331 dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
 332                 enum dma_data_direction dir)
 333 {
 334         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 335                 __func__, ptr, size, dir);
 336
 337         BUG_ON(dir == DMA_NONE);
 338
 339         return map_single(dev, ptr, size, dir);
 340 }
 341 EXPORT_SYMBOL(dma_map_single);
 342
 343 dma_addr_t dma_map_page(struct device *dev, struct page *page,
 344                 unsigned long offset, size_t size, enum dma_data_direction dir)
 345 {
 346         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
 347                 __func__, page, offset, size, dir);
 348
 349         BUG_ON(dir == DMA_NONE);
 350
 351         return map_single(dev, page_address(page) + offset, size, dir);
 352 }
 353 EXPORT_SYMBOL(dma_map_page);
 354
 355 /*
 356  * see if a mapped address was really a "safe" buffer and if so, copy
 357  * the data from the safe buffer back to the unsafe buffer and free up
 358  * the safe buffer.  (basically return things back to the way they
 359  * should be)
 360  */
 361
 362 void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 363                 enum dma_data_direction dir)
 364 {
 365         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 366                 __func__, (void *) dma_addr, size, dir);
 367
 368         BUG_ON(dir == DMA_NONE);
 369
 370         unmap_single(dev, dma_addr, size, dir);
 371 }
 372 EXPORT_SYMBOL(dma_unmap_single);
 373
 374 int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 375                 unsigned long off, size_t sz, enum dma_data_direction dir)
 376 {
 377         struct safe_buffer *buf;
 378
 379         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 380                 __func__, addr, off, sz, dir);
 381
 382         buf = find_safe_buffer_dev(dev, addr, __func__);
 383         if (!buf)
 384                 return 1;
 385
 386         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 387                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 388                 buf->safe, buf->safe_dma_addr);
 389
 390         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 391
 392         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 393                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 394                         __func__, buf->safe + off, buf->ptr + off, sz);
 395                 memcpy(buf->ptr + off, buf->safe + off, sz);
 396         }
 397         return 0;
 398 }
 399 EXPORT_SYMBOL(dmabounce_sync_for_cpu);
 400
 401 int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 402                 unsigned long off, size_t sz, enum dma_data_direction dir)
 403 {
 404         struct safe_buffer *buf;
 405
 406         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 407                 __func__, addr, off, sz, dir);
 408
 409         buf = find_safe_buffer_dev(dev, addr, __func__);
 410         if (!buf)
 411                 return 1;
 412
 413         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 414                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 415                 buf->safe, buf->safe_dma_addr);
 416
 417         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 418
 419         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
 420                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
 421                         __func__,buf->ptr + off, buf->safe + off, sz);
 422                 memcpy(buf->safe + off, buf->ptr + off, sz);
 423         }
 424         return 0;
 425 }
 426 EXPORT_SYMBOL(dmabounce_sync_for_device);
 427
 428 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
 429                 const char *name, unsigned long size)
 430 {
 431         pool->size = size;
 432         DO_STATS(pool->allocs = 0);
 433         pool->pool = dma_pool_create(name, dev, size,
 434                                      0 /* byte alignment */,
 435                                      0 /* no page-crossing issues */);
 436
 437         return pool->pool ? 0 : -ENOMEM;
 438 }
 439
 440 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 441                 unsigned long large_buffer_size)
 442 {
 443         struct dmabounce_device_info *device_info;
 444         int ret;
 445
 446         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 447         if (!device_info) {
 448                 dev_err(dev,
 449                         "Could not allocated dmabounce_device_info\n");
 450                 return -ENOMEM;
 451         }
 452
 453         ret = dmabounce_init_pool(&device_info->small, dev,
 454                                   "small_dmabounce_pool", small_buffer_size);
 455         if (ret) {
 456                 dev_err(dev,
 457                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 458                         small_buffer_size);
 459                 goto err_free;
 460         }
 461
 462         if (large_buffer_size) {
 463                 ret = dmabounce_init_pool(&device_info->large, dev,
 464                                           "large_dmabounce_pool",
 465                                           large_buffer_size);
 466                 if (ret) {
 467                         dev_err(dev,
 468                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 469                                 large_buffer_size);
 470                         goto err_destroy;
 471                 }
 472         }
 473
 474         device_info->dev = dev;
 475         INIT_LIST_HEAD(&device_info->safe_buffers);
 476         rwlock_init(&device_info->lock);
 477
 478 #ifdef STATS
 479         device_info->total_allocs = 0;
 480         device_info->map_op_count = 0;
 481         device_info->bounce_count = 0;
 482         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 483 #endif
 484
 485         dev->archdata.dmabounce = device_info;
 486
 487         dev_info(dev, "dmabounce: registered device\n");
 488
 489         return 0;
 490
 491  err_destroy:
 492         dma_pool_destroy(device_info->small.pool);
 493  err_free:
 494         kfree(device_info);
 495         return ret;
 496 }
 497 EXPORT_SYMBOL(dmabounce_register_dev);
 498
 499 void dmabounce_unregister_dev(struct device *dev)
 500 {
 501         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 502
 503         dev->archdata.dmabounce = NULL;
 504
 505         if (!device_info) {
 506                 dev_warn(dev,
 507                          "Never registered with dmabounce but attempting"
 508                          "to unregister!\n");
 509                 return;
 510         }
 511
 512         if (!list_empty(&device_info->safe_buffers)) {
 513                 dev_err(dev,
 514                         "Removing from dmabounce with pending buffers!\n");
 515                 BUG();
 516         }
 517
 518         if (device_info->small.pool)
 519                 dma_pool_destroy(device_info->small.pool);
 520         if (device_info->large.pool)
 521                 dma_pool_destroy(device_info->large.pool);
 522
 523 #ifdef STATS
 524         if (device_info->attr_res == 0)
 525                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 526 #endif
 527
 528         kfree(device_info);
 529
 530         dev_info(dev, "dmabounce: device unregistered\n");
 531 }
 532 EXPORT_SYMBOL(dmabounce_unregister_dev);
 533
 534 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 535 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 536 MODULE_LICENSE("GPL");