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                 if (dev)
 214                         dev_err(dev, "Trying to %s invalid mapping\n", where);
 215                 else
 216                         pr_err("unknown device: 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 dma_needs_bounce(dev, dma_addr, size) ? 1 : 0;
 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 == 0) {
 256                 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 257                        __func__, ptr);
 258                 return ~0;
 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 dma_addr_t __dma_map_page(struct device *dev, struct page *page,
 312                 unsigned long offset, size_t size, enum dma_data_direction dir)
 313 {
 314         dma_addr_t dma_addr;
 315         int ret;
 316
 317         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
 318                 __func__, page, offset, size, dir);
 319
 320         dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset;
 321
 322         ret = needs_bounce(dev, dma_addr, size);
 323         if (ret < 0)
 324                 return ~0;
 325
 326         if (ret == 0) {
 327                 __dma_page_cpu_to_dev(page, offset, size, dir);
 328                 return dma_addr;
 329         }
 330
 331         if (PageHighMem(page)) {
 332                 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
 333                 return ~0;
 334         }
 335
 336         return map_single(dev, page_address(page) + offset, size, dir);
 337 }
 338 EXPORT_SYMBOL(__dma_map_page);
 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 void __dma_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
 347                 enum dma_data_direction dir)
 348 {
 349         struct safe_buffer *buf;
 350
 351         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 352                 __func__, (void *) dma_addr, size, dir);
 353
 354         buf = find_safe_buffer_dev(dev, dma_addr, __func__);
 355         if (!buf) {
 356                 __dma_page_dev_to_cpu(pfn_to_page(dma_to_pfn(dev, dma_addr)),
 357                         dma_addr & ~PAGE_MASK, size, dir);
 358                 return;
 359         }
 360
 361         unmap_single(dev, buf, size, dir);
 362 }
 363 EXPORT_SYMBOL(__dma_unmap_page);
 364
 365 int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 366                 unsigned long off, size_t sz, enum dma_data_direction dir)
 367 {
 368         struct safe_buffer *buf;
 369
 370         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 371                 __func__, addr, off, sz, dir);
 372
 373         buf = find_safe_buffer_dev(dev, addr, __func__);
 374         if (!buf)
 375                 return 1;
 376
 377         BUG_ON(buf->direction != dir);
 378
 379         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 380                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 381                 buf->safe, buf->safe_dma_addr);
 382
 383         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 384
 385         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 386                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 387                         __func__, buf->safe + off, buf->ptr + off, sz);
 388                 memcpy(buf->ptr + off, buf->safe + off, sz);
 389         }
 390         return 0;
 391 }
 392 EXPORT_SYMBOL(dmabounce_sync_for_cpu);
 393
 394 int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 395                 unsigned long off, size_t sz, enum dma_data_direction dir)
 396 {
 397         struct safe_buffer *buf;
 398
 399         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 400                 __func__, addr, off, sz, dir);
 401
 402         buf = find_safe_buffer_dev(dev, addr, __func__);
 403         if (!buf)
 404                 return 1;
 405
 406         BUG_ON(buf->direction != dir);
 407
 408         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 409                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 410                 buf->safe, buf->safe_dma_addr);
 411
 412         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 413
 414         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
 415                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
 416                         __func__,buf->ptr + off, buf->safe + off, sz);
 417                 memcpy(buf->safe + off, buf->ptr + off, sz);
 418         }
 419         return 0;
 420 }
 421 EXPORT_SYMBOL(dmabounce_sync_for_device);
 422
 423 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
 424                 const char *name, unsigned long size)
 425 {
 426         pool->size = size;
 427         DO_STATS(pool->allocs = 0);
 428         pool->pool = dma_pool_create(name, dev, size,
 429                                      0 /* byte alignment */,
 430                                      0 /* no page-crossing issues */);
 431
 432         return pool->pool ? 0 : -ENOMEM;
 433 }
 434
 435 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 436                 unsigned long large_buffer_size)
 437 {
 438         struct dmabounce_device_info *device_info;
 439         int ret;
 440
 441         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 442         if (!device_info) {
 443                 dev_err(dev,
 444                         "Could not allocated dmabounce_device_info\n");
 445                 return -ENOMEM;
 446         }
 447
 448         ret = dmabounce_init_pool(&device_info->small, dev,
 449                                   "small_dmabounce_pool", small_buffer_size);
 450         if (ret) {
 451                 dev_err(dev,
 452                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 453                         small_buffer_size);
 454                 goto err_free;
 455         }
 456
 457         if (large_buffer_size) {
 458                 ret = dmabounce_init_pool(&device_info->large, dev,
 459                                           "large_dmabounce_pool",
 460                                           large_buffer_size);
 461                 if (ret) {
 462                         dev_err(dev,
 463                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 464                                 large_buffer_size);
 465                         goto err_destroy;
 466                 }
 467         }
 468
 469         device_info->dev = dev;
 470         INIT_LIST_HEAD(&device_info->safe_buffers);
 471         rwlock_init(&device_info->lock);
 472
 473 #ifdef STATS
 474         device_info->total_allocs = 0;
 475         device_info->map_op_count = 0;
 476         device_info->bounce_count = 0;
 477         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 478 #endif
 479
 480         dev->archdata.dmabounce = device_info;
 481
 482         dev_info(dev, "dmabounce: registered device\n");
 483
 484         return 0;
 485
 486  err_destroy:
 487         dma_pool_destroy(device_info->small.pool);
 488  err_free:
 489         kfree(device_info);
 490         return ret;
 491 }
 492 EXPORT_SYMBOL(dmabounce_register_dev);
 493
 494 void dmabounce_unregister_dev(struct device *dev)
 495 {
 496         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 497
 498         dev->archdata.dmabounce = NULL;
 499
 500         if (!device_info) {
 501                 dev_warn(dev,
 502                          "Never registered with dmabounce but attempting"
 503                          "to unregister!\n");
 504                 return;
 505         }
 506
 507         if (!list_empty(&device_info->safe_buffers)) {
 508                 dev_err(dev,
 509                         "Removing from dmabounce with pending buffers!\n");
 510                 BUG();
 511         }
 512
 513         if (device_info->small.pool)
 514                 dma_pool_destroy(device_info->small.pool);
 515         if (device_info->large.pool)
 516                 dma_pool_destroy(device_info->large.pool);
 517
 518 #ifdef STATS
 519         if (device_info->attr_res == 0)
 520                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 521 #endif
 522
 523         kfree(device_info);
 524
 525         dev_info(dev, "dmabounce: device unregistered\n");
 526 }
 527 EXPORT_SYMBOL(dmabounce_unregister_dev);
 528
 529 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 530 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 531 MODULE_LICENSE("GPL");