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