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                 BUG_ON(buf->direction != dir);
 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(dev->archdata.dmabounce->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(dev->archdata.dmabounce, buf);
 321         }
 322 }
 323
 324 /* ************************************************** */
 325
 326 /*
 327  * see if a buffer address is in an 'unsafe' range.  if it is
 328  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 329  * substitute the safe buffer for the unsafe one.
 330  * (basically move the buffer from an unsafe area to a safe one)
 331  */
 332 dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
 333                 enum dma_data_direction dir)
 334 {
 335         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 336                 __func__, ptr, size, dir);
 337
 338         BUG_ON(!valid_dma_direction(dir));
 339
 340         return map_single(dev, ptr, size, dir);
 341 }
 342 EXPORT_SYMBOL(dma_map_single);
 343
 344 dma_addr_t dma_map_page(struct device *dev, struct page *page,
 345                 unsigned long offset, size_t size, enum dma_data_direction dir)
 346 {
 347         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
 348                 __func__, page, offset, size, dir);
 349
 350         BUG_ON(!valid_dma_direction(dir));
 351
 352         return map_single(dev, page_address(page) + offset, size, dir);
 353 }
 354 EXPORT_SYMBOL(dma_map_page);
 355
 356 /*
 357  * see if a mapped address was really a "safe" buffer and if so, copy
 358  * the data from the safe buffer back to the unsafe buffer and free up
 359  * the safe buffer.  (basically return things back to the way they
 360  * should be)
 361  */
 362
 363 void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 364                 enum dma_data_direction dir)
 365 {
 366         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 367                 __func__, (void *) dma_addr, size, dir);
 368
 369         unmap_single(dev, dma_addr, size, dir);
 370 }
 371 EXPORT_SYMBOL(dma_unmap_single);
 372
 373 int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 374                 unsigned long off, size_t sz, enum dma_data_direction dir)
 375 {
 376         struct safe_buffer *buf;
 377
 378         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 379                 __func__, addr, off, sz, dir);
 380
 381         buf = find_safe_buffer_dev(dev, addr, __func__);
 382         if (!buf)
 383                 return 1;
 384
 385         BUG_ON(buf->direction != dir);
 386
 387         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 388                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 389                 buf->safe, buf->safe_dma_addr);
 390
 391         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 392
 393         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 394                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 395                         __func__, buf->safe + off, buf->ptr + off, sz);
 396                 memcpy(buf->ptr + off, buf->safe + off, sz);
 397         }
 398         return 0;
 399 }
 400 EXPORT_SYMBOL(dmabounce_sync_for_cpu);
 401
 402 int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 403                 unsigned long off, size_t sz, enum dma_data_direction dir)
 404 {
 405         struct safe_buffer *buf;
 406
 407         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 408                 __func__, addr, off, sz, dir);
 409
 410         buf = find_safe_buffer_dev(dev, addr, __func__);
 411         if (!buf)
 412                 return 1;
 413
 414         BUG_ON(buf->direction != dir);
 415
 416         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 417                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 418                 buf->safe, buf->safe_dma_addr);
 419
 420         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 421
 422         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
 423                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
 424                         __func__,buf->ptr + off, buf->safe + off, sz);
 425                 memcpy(buf->safe + off, buf->ptr + off, sz);
 426         }
 427         return 0;
 428 }
 429 EXPORT_SYMBOL(dmabounce_sync_for_device);
 430
 431 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
 432                 const char *name, unsigned long size)
 433 {
 434         pool->size = size;
 435         DO_STATS(pool->allocs = 0);
 436         pool->pool = dma_pool_create(name, dev, size,
 437                                      0 /* byte alignment */,
 438                                      0 /* no page-crossing issues */);
 439
 440         return pool->pool ? 0 : -ENOMEM;
 441 }
 442
 443 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 444                 unsigned long large_buffer_size)
 445 {
 446         struct dmabounce_device_info *device_info;
 447         int ret;
 448
 449         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 450         if (!device_info) {
 451                 dev_err(dev,
 452                         "Could not allocated dmabounce_device_info\n");
 453                 return -ENOMEM;
 454         }
 455
 456         ret = dmabounce_init_pool(&device_info->small, dev,
 457                                   "small_dmabounce_pool", small_buffer_size);
 458         if (ret) {
 459                 dev_err(dev,
 460                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 461                         small_buffer_size);
 462                 goto err_free;
 463         }
 464
 465         if (large_buffer_size) {
 466                 ret = dmabounce_init_pool(&device_info->large, dev,
 467                                           "large_dmabounce_pool",
 468                                           large_buffer_size);
 469                 if (ret) {
 470                         dev_err(dev,
 471                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 472                                 large_buffer_size);
 473                         goto err_destroy;
 474                 }
 475         }
 476
 477         device_info->dev = dev;
 478         INIT_LIST_HEAD(&device_info->safe_buffers);
 479         rwlock_init(&device_info->lock);
 480
 481 #ifdef STATS
 482         device_info->total_allocs = 0;
 483         device_info->map_op_count = 0;
 484         device_info->bounce_count = 0;
 485         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 486 #endif
 487
 488         dev->archdata.dmabounce = device_info;
 489
 490         dev_info(dev, "dmabounce: registered device\n");
 491
 492         return 0;
 493
 494  err_destroy:
 495         dma_pool_destroy(device_info->small.pool);
 496  err_free:
 497         kfree(device_info);
 498         return ret;
 499 }
 500 EXPORT_SYMBOL(dmabounce_register_dev);
 501
 502 void dmabounce_unregister_dev(struct device *dev)
 503 {
 504         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 505
 506         dev->archdata.dmabounce = NULL;
 507
 508         if (!device_info) {
 509                 dev_warn(dev,
 510                          "Never registered with dmabounce but attempting"
 511                          "to unregister!\n");
 512                 return;
 513         }
 514
 515         if (!list_empty(&device_info->safe_buffers)) {
 516                 dev_err(dev,
 517                         "Removing from dmabounce with pending buffers!\n");
 518                 BUG();
 519         }
 520
 521         if (device_info->small.pool)
 522                 dma_pool_destroy(device_info->small.pool);
 523         if (device_info->large.pool)
 524                 dma_pool_destroy(device_info->large.pool);
 525
 526 #ifdef STATS
 527         if (device_info->attr_res == 0)
 528                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 529 #endif
 530
 531         kfree(device_info);
 532
 533         dev_info(dev, "dmabounce: device unregistered\n");
 534 }
 535 EXPORT_SYMBOL(dmabounce_unregister_dev);
 536
 537 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 538 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 539 MODULE_LICENSE("GPL");