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 and the remainder of memory is at the top an the DMA memory
   9  *  can be marked as ZONE_DMA. Anything beyond that such as discontigous
  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
  33 #undef DEBUG
  34
  35 #undef STATS
  36 #ifdef STATS
  37 #define DO_STATS(X) do { X ; } while (0)
  38 #else
  39 #define DO_STATS(X) do { } while (0)
  40 #endif
  41
  42 /* ************************************************** */
  43
  44 struct safe_buffer {
  45         struct list_head node;
  46
  47         /* original request */
  48         void            *ptr;
  49         size_t          size;
  50         int             direction;
  51
  52         /* safe buffer info */
  53         struct dma_pool *pool;
  54         void            *safe;
  55         dma_addr_t      safe_dma_addr;
  56 };
  57
  58 struct dmabounce_device_info {
  59         struct list_head node;
  60
  61         struct device *dev;
  62         struct dma_pool *small_buffer_pool;
  63         struct dma_pool *large_buffer_pool;
  64         struct list_head safe_buffers;
  65         unsigned long small_buffer_size, large_buffer_size;
  66 #ifdef STATS
  67         unsigned long sbp_allocs;
  68         unsigned long lbp_allocs;
  69         unsigned long total_allocs;
  70         unsigned long map_op_count;
  71         unsigned long bounce_count;
  72 #endif
  73 };
  74
  75 static LIST_HEAD(dmabounce_devs);
  76
  77 #ifdef STATS
  78 static void print_alloc_stats(struct dmabounce_device_info *device_info)
  79 {
  80         printk(KERN_INFO
  81                 "%s: dmabounce: sbp: %lu, lbp: %lu, other: %lu, total: %lu\n",
  82                 device_info->dev->bus_id,
  83                 device_info->sbp_allocs, device_info->lbp_allocs,
  84                 device_info->total_allocs - device_info->sbp_allocs -
  85                         device_info->lbp_allocs,
  86                 device_info->total_allocs);
  87 }
  88 #endif
  89
  90 /* find the given device in the dmabounce device list */
  91 static inline struct dmabounce_device_info *
  92 find_dmabounce_dev(struct device *dev)
  93 {
  94         struct list_head *entry;
  95
  96         list_for_each(entry, &dmabounce_devs) {
  97                 struct dmabounce_device_info *d =
  98                         list_entry(entry, struct dmabounce_device_info, node);
  99
 100                 if (d->dev == dev)
 101                         return d;
 102         }
 103         return NULL;
 104 }
 105
 106
 107 /* allocate a 'safe' buffer and keep track of it */
 108 static inline struct safe_buffer *
 109 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 110                         size_t size, enum dma_data_direction dir)
 111 {
 112         struct safe_buffer *buf;
 113         struct dma_pool *pool;
 114         struct device *dev = device_info->dev;
 115         void *safe;
 116         dma_addr_t safe_dma_addr;
 117
 118         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 119                 __func__, ptr, size, dir);
 120
 121         DO_STATS ( device_info->total_allocs++ );
 122
 123         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 124         if (buf == 0) {
 125                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 126                 return 0;
 127         }
 128
 129         if (size <= device_info->small_buffer_size) {
 130                 pool = device_info->small_buffer_pool;
 131                 safe = dma_pool_alloc(pool, GFP_ATOMIC, &safe_dma_addr);
 132
 133                 DO_STATS ( device_info->sbp_allocs++ );
 134         } else if (size <= device_info->large_buffer_size) {
 135                 pool = device_info->large_buffer_pool;
 136                 safe = dma_pool_alloc(pool, GFP_ATOMIC, &safe_dma_addr);
 137
 138                 DO_STATS ( device_info->lbp_allocs++ );
 139         } else {
 140                 pool = 0;
 141                 safe = dma_alloc_coherent(dev, size, &safe_dma_addr, GFP_ATOMIC);
 142         }
 143
 144         if (safe == 0) {
 145                 dev_warn(device_info->dev,
 146                         "%s: could not alloc dma memory (size=%d)\n",
 147                        __func__, size);
 148                 kfree(buf);
 149                 return 0;
 150         }
 151
 152 #ifdef STATS
 153         if (device_info->total_allocs % 1000 == 0)
 154                 print_alloc_stats(device_info);
 155 #endif
 156
 157         buf->ptr = ptr;
 158         buf->size = size;
 159         buf->direction = dir;
 160         buf->pool = pool;
 161         buf->safe = safe;
 162         buf->safe_dma_addr = safe_dma_addr;
 163
 164         list_add(&buf->node, &device_info->safe_buffers);
 165
 166         return buf;
 167 }
 168
 169 /* determine if a buffer is from our "safe" pool */
 170 static inline struct safe_buffer *
 171 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 172 {
 173         struct list_head *entry;
 174
 175         list_for_each(entry, &device_info->safe_buffers) {
 176                 struct safe_buffer *b =
 177                         list_entry(entry, struct safe_buffer, node);
 178
 179                 if (b->safe_dma_addr == safe_dma_addr)
 180                         return b;
 181         }
 182
 183         return NULL;
 184 }
 185
 186 static inline void
 187 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 188 {
 189         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 190
 191         list_del(&buf->node);
 192
 193         if (buf->pool)
 194                 dma_pool_free(buf->pool, buf->safe, buf->safe_dma_addr);
 195         else
 196                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 197                                     buf->safe_dma_addr);
 198
 199         kfree(buf);
 200 }
 201
 202 /* ************************************************** */
 203
 204 #ifdef STATS
 205
 206 static void print_map_stats(struct dmabounce_device_info *device_info)
 207 {
 208         printk(KERN_INFO
 209                 "%s: dmabounce: map_op_count=%lu, bounce_count=%lu\n",
 210                 device_info->dev->bus_id,
 211                 device_info->map_op_count, device_info->bounce_count);
 212 }
 213 #endif
 214
 215 static inline dma_addr_t
 216 map_single(struct device *dev, void *ptr, size_t size,
 217                 enum dma_data_direction dir)
 218 {
 219         dma_addr_t dma_addr;
 220         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 221
 222         if (device_info)
 223                 DO_STATS ( device_info->map_op_count++ );
 224
 225         if (dev->dma_mask) {
 226                 unsigned long limit;
 227
 228                 limit = (*dev->dma_mask + 1) & ~(*dev->dma_mask);
 229                 if (limit && (size > limit)) {
 230                         dev_err(dev, "DMA mapping too big "
 231                                 "(requested %#x mask %#Lx)\n",
 232                                 size, *dev->dma_mask);
 233                         return ~0;
 234                 }
 235         }
 236
 237         dma_addr = virt_to_bus(ptr);
 238
 239         if (device_info && dma_needs_bounce(dev, dma_addr, size)) {
 240                 struct safe_buffer *buf;
 241
 242                 buf = alloc_safe_buffer(device_info, ptr, size, dir);
 243                 if (buf == 0) {
 244                         dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 245                                __func__, ptr);
 246                         return 0;
 247                 }
 248
 249                 dev_dbg(dev,
 250                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 251                         __func__, buf->ptr, (void *) virt_to_bus(buf->ptr),
 252                         buf->safe, (void *) buf->safe_dma_addr);
 253
 254                 if ((dir == DMA_TO_DEVICE) ||
 255                     (dir == DMA_BIDIRECTIONAL)) {
 256                         dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 257                                 __func__, ptr, buf->safe, size);
 258                         memcpy(buf->safe, ptr, size);
 259                 }
 260                 consistent_sync(buf->safe, size, dir);
 261
 262                 dma_addr = buf->safe_dma_addr;
 263         } else {
 264                 consistent_sync(ptr, size, dir);
 265         }
 266
 267         return dma_addr;
 268 }
 269
 270 static inline void
 271 unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 272                 enum dma_data_direction dir)
 273 {
 274         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 275         struct safe_buffer *buf = NULL;
 276
 277         /*
 278          * Trying to unmap an invalid mapping
 279          */
 280         if (dma_addr == ~0) {
 281                 dev_err(dev, "Trying to unmap invalid mapping\n");
 282                 return;
 283         }
 284
 285         if (device_info)
 286                 buf = find_safe_buffer(device_info, dma_addr);
 287
 288         if (buf) {
 289                 BUG_ON(buf->size != size);
 290
 291                 dev_dbg(dev,
 292                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 293                         __func__, buf->ptr, (void *) virt_to_bus(buf->ptr),
 294                         buf->safe, (void *) buf->safe_dma_addr);
 295
 296
 297                 DO_STATS ( device_info->bounce_count++ );
 298
 299                 if ((dir == DMA_FROM_DEVICE) ||
 300                     (dir == DMA_BIDIRECTIONAL)) {
 301                         dev_dbg(dev,
 302                                 "%s: copy back safe %p to unsafe %p size %d\n",
 303                                 __func__, buf->safe, buf->ptr, size);
 304                         memcpy(buf->ptr, buf->safe, size);
 305                 }
 306                 free_safe_buffer(device_info, buf);
 307         }
 308 }
 309
 310 static inline void
 311 sync_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 312                 enum dma_data_direction dir)
 313 {
 314         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 315         struct safe_buffer *buf = NULL;
 316
 317         if (device_info)
 318                 buf = find_safe_buffer(device_info, dma_addr);
 319
 320         if (buf) {
 321                 /*
 322                  * Both of these checks from original code need to be
 323                  * commented out b/c some drivers rely on the following:
 324                  *
 325                  * 1) Drivers may map a large chunk of memory into DMA space
 326                  *    but only sync a small portion of it. Good example is
 327                  *    allocating a large buffer, mapping it, and then
 328                  *    breaking it up into small descriptors. No point
 329                  *    in syncing the whole buffer if you only have to
 330                  *    touch one descriptor.
 331                  *
 332                  * 2) Buffers that are mapped as DMA_BIDIRECTIONAL are
 333                  *    usually only synced in one dir at a time.
 334                  *
 335                  * See drivers/net/eepro100.c for examples of both cases.
 336                  *
 337                  * -ds
 338                  *
 339                  * BUG_ON(buf->size != size);
 340                  * BUG_ON(buf->direction != dir);
 341                  */
 342
 343                 dev_dbg(dev,
 344                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 345                         __func__, buf->ptr, (void *) virt_to_bus(buf->ptr),
 346                         buf->safe, (void *) buf->safe_dma_addr);
 347
 348                 DO_STATS ( device_info->bounce_count++ );
 349
 350                 switch (dir) {
 351                 case DMA_FROM_DEVICE:
 352                         dev_dbg(dev,
 353                                 "%s: copy back safe %p to unsafe %p size %d\n",
 354                                 __func__, buf->safe, buf->ptr, size);
 355                         memcpy(buf->ptr, buf->safe, size);
 356                         break;
 357                 case DMA_TO_DEVICE:
 358                         dev_dbg(dev,
 359                                 "%s: copy out unsafe %p to safe %p, size %d\n",
 360                                 __func__,buf->ptr, buf->safe, size);
 361                         memcpy(buf->safe, buf->ptr, size);
 362                         break;
 363                 case DMA_BIDIRECTIONAL:
 364                         BUG();  /* is this allowed?  what does it mean? */
 365                 default:
 366                         BUG();
 367                 }
 368                 consistent_sync(buf->safe, size, dir);
 369         } else {
 370                 consistent_sync(bus_to_virt(dma_addr), size, dir);
 371         }
 372 }
 373
 374 /* ************************************************** */
 375
 376 /*
 377  * see if a buffer address is in an 'unsafe' range.  if it is
 378  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 379  * substitute the safe buffer for the unsafe one.
 380  * (basically move the buffer from an unsafe area to a safe one)
 381  */
 382 dma_addr_t
 383 dma_map_single(struct device *dev, void *ptr, size_t size,
 384                 enum dma_data_direction dir)
 385 {
 386         unsigned long flags;
 387         dma_addr_t dma_addr;
 388
 389         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 390                 __func__, ptr, size, dir);
 391
 392         BUG_ON(dir == DMA_NONE);
 393
 394         local_irq_save(flags);
 395
 396         dma_addr = map_single(dev, ptr, size, dir);
 397
 398         local_irq_restore(flags);
 399
 400         return dma_addr;
 401 }
 402
 403 /*
 404  * see if a mapped address was really a "safe" buffer and if so, copy
 405  * the data from the safe buffer back to the unsafe buffer and free up
 406  * the safe buffer.  (basically return things back to the way they
 407  * should be)
 408  */
 409
 410 void
 411 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 412                         enum dma_data_direction dir)
 413 {
 414         unsigned long flags;
 415
 416         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 417                 __func__, (void *) dma_addr, size, dir);
 418
 419         BUG_ON(dir == DMA_NONE);
 420
 421         local_irq_save(flags);
 422
 423         unmap_single(dev, dma_addr, size, dir);
 424
 425         local_irq_restore(flags);
 426 }
 427
 428 int
 429 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 430                 enum dma_data_direction dir)
 431 {
 432         unsigned long flags;
 433         int i;
 434
 435         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 436                 __func__, sg, nents, dir);
 437
 438         BUG_ON(dir == DMA_NONE);
 439
 440         local_irq_save(flags);
 441
 442         for (i = 0; i < nents; i++, sg++) {
 443                 struct page *page = sg->page;
 444                 unsigned int offset = sg->offset;
 445                 unsigned int length = sg->length;
 446                 void *ptr = page_address(page) + offset;
 447
 448                 sg->dma_address =
 449                         map_single(dev, ptr, length, dir);
 450         }
 451
 452         local_irq_restore(flags);
 453
 454         return nents;
 455 }
 456
 457 void
 458 dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 459                 enum dma_data_direction dir)
 460 {
 461         unsigned long flags;
 462         int i;
 463
 464         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 465                 __func__, sg, nents, dir);
 466
 467         BUG_ON(dir == DMA_NONE);
 468
 469         local_irq_save(flags);
 470
 471         for (i = 0; i < nents; i++, sg++) {
 472                 dma_addr_t dma_addr = sg->dma_address;
 473                 unsigned int length = sg->length;
 474
 475                 unmap_single(dev, dma_addr, length, dir);
 476         }
 477
 478         local_irq_restore(flags);
 479 }
 480
 481 void
 482 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size,
 483                                 enum dma_data_direction dir)
 484 {
 485         unsigned long flags;
 486
 487         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 488                 __func__, (void *) dma_addr, size, dir);
 489
 490         local_irq_save(flags);
 491
 492         sync_single(dev, dma_addr, size, dir);
 493
 494         local_irq_restore(flags);
 495 }
 496
 497 void
 498 dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size,
 499                                 enum dma_data_direction dir)
 500 {
 501         unsigned long flags;
 502
 503         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 504                 __func__, (void *) dma_addr, size, dir);
 505
 506         local_irq_save(flags);
 507
 508         sync_single(dev, dma_addr, size, dir);
 509
 510         local_irq_restore(flags);
 511 }
 512
 513 void
 514 dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
 515                         enum dma_data_direction dir)
 516 {
 517         unsigned long flags;
 518         int i;
 519
 520         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 521                 __func__, sg, nents, dir);
 522
 523         BUG_ON(dir == DMA_NONE);
 524
 525         local_irq_save(flags);
 526
 527         for (i = 0; i < nents; i++, sg++) {
 528                 dma_addr_t dma_addr = sg->dma_address;
 529                 unsigned int length = sg->length;
 530
 531                 sync_single(dev, dma_addr, length, dir);
 532         }
 533
 534         local_irq_restore(flags);
 535 }
 536
 537 void
 538 dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
 539                         enum dma_data_direction dir)
 540 {
 541         unsigned long flags;
 542         int i;
 543
 544         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 545                 __func__, sg, nents, dir);
 546
 547         BUG_ON(dir == DMA_NONE);
 548
 549         local_irq_save(flags);
 550
 551         for (i = 0; i < nents; i++, sg++) {
 552                 dma_addr_t dma_addr = sg->dma_address;
 553                 unsigned int length = sg->length;
 554
 555                 sync_single(dev, dma_addr, length, dir);
 556         }
 557
 558         local_irq_restore(flags);
 559 }
 560
 561 int
 562 dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 563                         unsigned long large_buffer_size)
 564 {
 565         struct dmabounce_device_info *device_info;
 566
 567         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 568         if (!device_info) {
 569                 printk(KERN_ERR
 570                         "Could not allocated dmabounce_device_info for %s",
 571                         dev->bus_id);
 572                 return -ENOMEM;
 573         }
 574
 575         device_info->small_buffer_pool =
 576                 dma_pool_create("small_dmabounce_pool",
 577                                 dev,
 578                                 small_buffer_size,
 579                                 0 /* byte alignment */,
 580                                 0 /* no page-crossing issues */);
 581         if (!device_info->small_buffer_pool) {
 582                 printk(KERN_ERR
 583                         "dmabounce: could not allocate small DMA pool for %s\n",
 584                         dev->bus_id);
 585                 kfree(device_info);
 586                 return -ENOMEM;
 587         }
 588
 589         if (large_buffer_size) {
 590                 device_info->large_buffer_pool =
 591                         dma_pool_create("large_dmabounce_pool",
 592                                         dev,
 593                                         large_buffer_size,
 594                                         0 /* byte alignment */,
 595                                         0 /* no page-crossing issues */);
 596                 if (!device_info->large_buffer_pool) {
 597                 printk(KERN_ERR
 598                         "dmabounce: could not allocate large DMA pool for %s\n",
 599                         dev->bus_id);
 600                         dma_pool_destroy(device_info->small_buffer_pool);
 601
 602                         return -ENOMEM;
 603                 }
 604         }
 605
 606         device_info->dev = dev;
 607         device_info->small_buffer_size = small_buffer_size;
 608         device_info->large_buffer_size = large_buffer_size;
 609         INIT_LIST_HEAD(&device_info->safe_buffers);
 610
 611 #ifdef STATS
 612         device_info->sbp_allocs = 0;
 613         device_info->lbp_allocs = 0;
 614         device_info->total_allocs = 0;
 615         device_info->map_op_count = 0;
 616         device_info->bounce_count = 0;
 617 #endif
 618
 619         list_add(&device_info->node, &dmabounce_devs);
 620
 621         printk(KERN_INFO "dmabounce: registered device %s on %s bus\n",
 622                 dev->bus_id, dev->bus->name);
 623
 624         return 0;
 625 }
 626
 627 void
 628 dmabounce_unregister_dev(struct device *dev)
 629 {
 630         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 631
 632         if (!device_info) {
 633                 printk(KERN_WARNING
 634                         "%s: Never registered with dmabounce but attempting" \
 635                         "to unregister!\n", dev->bus_id);
 636                 return;
 637         }
 638
 639         if (!list_empty(&device_info->safe_buffers)) {
 640                 printk(KERN_ERR
 641                         "%s: Removing from dmabounce with pending buffers!\n",
 642                         dev->bus_id);
 643                 BUG();
 644         }
 645
 646         if (device_info->small_buffer_pool)
 647                 dma_pool_destroy(device_info->small_buffer_pool);
 648         if (device_info->large_buffer_pool)
 649                 dma_pool_destroy(device_info->large_buffer_pool);
 650
 651 #ifdef STATS
 652         print_alloc_stats(device_info);
 653         print_map_stats(device_info);
 654 #endif
 655
 656         list_del(&device_info->node);
 657
 658         kfree(device_info);
 659
 660         printk(KERN_INFO "dmabounce: device %s on %s bus unregistered\n",
 661                 dev->bus_id, dev->bus->name);
 662 }
 663
 664
 665 EXPORT_SYMBOL(dma_map_single);
 666 EXPORT_SYMBOL(dma_unmap_single);
 667 EXPORT_SYMBOL(dma_map_sg);
 668 EXPORT_SYMBOL(dma_unmap_sg);
 669 EXPORT_SYMBOL(dma_sync_single);
 670 EXPORT_SYMBOL(dma_sync_sg);
 671 EXPORT_SYMBOL(dmabounce_register_dev);
 672 EXPORT_SYMBOL(dmabounce_unregister_dev);
 673
 674 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 675 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 676 MODULE_LICENSE("GPL");