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