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