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 #include <asm/cacheflush.h>
  34
  35 #undef DEBUG
  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 list_head node;
  70
  71         struct device *dev;
  72         struct list_head safe_buffers;
  73 #ifdef STATS
  74         unsigned long total_allocs;
  75         unsigned long map_op_count;
  76         unsigned long bounce_count;
  77 #endif
  78         struct dmabounce_pool   small;
  79         struct dmabounce_pool   large;
  80 };
  81
  82 static LIST_HEAD(dmabounce_devs);
  83
  84 #ifdef STATS
  85 static void print_alloc_stats(struct dmabounce_device_info *device_info)
  86 {
  87         printk(KERN_INFO
  88                 "%s: dmabounce: sbp: %lu, lbp: %lu, other: %lu, total: %lu\n",
  89                 device_info->dev->bus_id,
  90                 device_info->small.allocs, device_info->large.allocs,
  91                 device_info->total_allocs - device_info->small.allocs -
  92                         device_info->large.allocs,
  93                 device_info->total_allocs);
  94 }
  95 #endif
  96
  97 /* find the given device in the dmabounce device list */
  98 static inline struct dmabounce_device_info *
  99 find_dmabounce_dev(struct device *dev)
 100 {
 101         struct dmabounce_device_info *d;
 102
 103         list_for_each_entry(d, &dmabounce_devs, node)
 104                 if (d->dev == dev)
 105                         return d;
 106
 107         return NULL;
 108 }
 109
 110
 111 /* allocate a 'safe' buffer and keep track of it */
 112 static inline struct safe_buffer *
 113 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 114                   size_t size, enum dma_data_direction dir)
 115 {
 116         struct safe_buffer *buf;
 117         struct dmabounce_pool *pool;
 118         struct device *dev = device_info->dev;
 119
 120         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 121                 __func__, ptr, size, dir);
 122
 123         if (size <= device_info->small.size) {
 124                 pool = &device_info->small;
 125         } else if (size <= device_info->large.size) {
 126                 pool = &device_info->large;
 127         } else {
 128                 pool = NULL;
 129         }
 130
 131         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 132         if (buf == NULL) {
 133                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 134                 return NULL;
 135         }
 136
 137         buf->ptr = ptr;
 138         buf->size = size;
 139         buf->direction = dir;
 140         buf->pool = pool;
 141
 142         if (pool) {
 143                 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
 144                                            &buf->safe_dma_addr);
 145         } else {
 146                 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
 147                                                GFP_ATOMIC);
 148         }
 149
 150         if (buf->safe == NULL) {
 151                 dev_warn(dev,
 152                          "%s: could not alloc dma memory (size=%d)\n",
 153                          __func__, size);
 154                 kfree(buf);
 155                 return NULL;
 156         }
 157
 158 #ifdef STATS
 159         if (pool)
 160                 pool->allocs++;
 161         device_info->total_allocs++;
 162         if (device_info->total_allocs % 1000 == 0)
 163                 print_alloc_stats(device_info);
 164 #endif
 165
 166         list_add(&buf->node, &device_info->safe_buffers);
 167
 168         return buf;
 169 }
 170
 171 /* determine if a buffer is from our "safe" pool */
 172 static inline struct safe_buffer *
 173 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 174 {
 175         struct safe_buffer *b;
 176
 177         list_for_each_entry(b, &device_info->safe_buffers, node)
 178                 if (b->safe_dma_addr == safe_dma_addr)
 179                         return b;
 180
 181         return NULL;
 182 }
 183
 184 static inline void
 185 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 186 {
 187         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 188
 189         list_del(&buf->node);
 190
 191         if (buf->pool)
 192                 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
 193         else
 194                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 195                                     buf->safe_dma_addr);
 196
 197         kfree(buf);
 198 }
 199
 200 /* ************************************************** */
 201
 202 #ifdef STATS
 203 static void print_map_stats(struct dmabounce_device_info *device_info)
 204 {
 205         dev_info(device_info->dev,
 206                 "dmabounce: map_op_count=%lu, bounce_count=%lu\n",
 207                 device_info->map_op_count, device_info->bounce_count);
 208 }
 209 #endif
 210
 211 static inline dma_addr_t
 212 map_single(struct device *dev, void *ptr, size_t size,
 213                 enum dma_data_direction dir)
 214 {
 215         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 216         dma_addr_t dma_addr;
 217         int needs_bounce = 0;
 218
 219         if (device_info)
 220                 DO_STATS ( device_info->map_op_count++ );
 221
 222         dma_addr = virt_to_dma(dev, ptr);
 223
 224         if (dev->dma_mask) {
 225                 unsigned long mask = *dev->dma_mask;
 226                 unsigned long limit;
 227
 228                 limit = (mask + 1) & ~mask;
 229                 if (limit && size > limit) {
 230                         dev_err(dev, "DMA mapping too big (requested %#x "
 231                                 "mask %#Lx)\n", size, *dev->dma_mask);
 232                         return ~0;
 233                 }
 234
 235                 /*
 236                  * Figure out if we need to bounce from the DMA mask.
 237                  */
 238                 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
 239         }
 240
 241         if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
 242                 struct safe_buffer *buf;
 243
 244                 buf = alloc_safe_buffer(device_info, ptr, size, dir);
 245                 if (buf == 0) {
 246                         dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 247                                __func__, ptr);
 248                         return 0;
 249                 }
 250
 251                 dev_dbg(dev,
 252                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 253                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 254                         buf->safe, (void *) buf->safe_dma_addr);
 255
 256                 if ((dir == DMA_TO_DEVICE) ||
 257                     (dir == DMA_BIDIRECTIONAL)) {
 258                         dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 259                                 __func__, ptr, buf->safe, size);
 260                         memcpy(buf->safe, ptr, size);
 261                 }
 262                 ptr = buf->safe;
 263
 264                 dma_addr = buf->safe_dma_addr;
 265         }
 266
 267         consistent_sync(ptr, size, dir);
 268
 269         return dma_addr;
 270 }
 271
 272 static inline void
 273 unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 274                 enum dma_data_direction dir)
 275 {
 276         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 277         struct safe_buffer *buf = NULL;
 278
 279         /*
 280          * Trying to unmap an invalid mapping
 281          */
 282         if (dma_mapping_error(dma_addr)) {
 283                 dev_err(dev, "Trying to unmap invalid mapping\n");
 284                 return;
 285         }
 286
 287         if (device_info)
 288                 buf = find_safe_buffer(device_info, dma_addr);
 289
 290         if (buf) {
 291                 BUG_ON(buf->size != size);
 292
 293                 dev_dbg(dev,
 294                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 295                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 296                         buf->safe, (void *) buf->safe_dma_addr);
 297
 298                 DO_STATS ( device_info->bounce_count++ );
 299
 300                 if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 301                         unsigned long ptr;
 302
 303                         dev_dbg(dev,
 304                                 "%s: copy back safe %p to unsafe %p size %d\n",
 305                                 __func__, buf->safe, buf->ptr, size);
 306                         memcpy(buf->ptr, buf->safe, size);
 307
 308                         /*
 309                          * DMA buffers must have the same cache properties
 310                          * as if they were really used for DMA - which means
 311                          * data must be written back to RAM.  Note that
 312                          * we don't use dmac_flush_range() here for the
 313                          * bidirectional case because we know the cache
 314                          * lines will be coherent with the data written.
 315                          */
 316                         ptr = (unsigned long)buf->ptr;
 317                         dmac_clean_range(ptr, ptr + size);
 318                 }
 319                 free_safe_buffer(device_info, buf);
 320         }
 321 }
 322
 323 static inline void
 324 sync_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 325                 enum dma_data_direction dir)
 326 {
 327         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 328         struct safe_buffer *buf = NULL;
 329
 330         if (device_info)
 331                 buf = find_safe_buffer(device_info, dma_addr);
 332
 333         if (buf) {
 334                 /*
 335                  * Both of these checks from original code need to be
 336                  * commented out b/c some drivers rely on the following:
 337                  *
 338                  * 1) Drivers may map a large chunk of memory into DMA space
 339                  *    but only sync a small portion of it. Good example is
 340                  *    allocating a large buffer, mapping it, and then
 341                  *    breaking it up into small descriptors. No point
 342                  *    in syncing the whole buffer if you only have to
 343                  *    touch one descriptor.
 344                  *
 345                  * 2) Buffers that are mapped as DMA_BIDIRECTIONAL are
 346                  *    usually only synced in one dir at a time.
 347                  *
 348                  * See drivers/net/eepro100.c for examples of both cases.
 349                  *
 350                  * -ds
 351                  *
 352                  * BUG_ON(buf->size != size);
 353                  * BUG_ON(buf->direction != dir);
 354                  */
 355
 356                 dev_dbg(dev,
 357                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 358                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 359                         buf->safe, (void *) buf->safe_dma_addr);
 360
 361                 DO_STATS ( device_info->bounce_count++ );
 362
 363                 switch (dir) {
 364                 case DMA_FROM_DEVICE:
 365                         dev_dbg(dev,
 366                                 "%s: copy back safe %p to unsafe %p size %d\n",
 367                                 __func__, buf->safe, buf->ptr, size);
 368                         memcpy(buf->ptr, buf->safe, size);
 369                         break;
 370                 case DMA_TO_DEVICE:
 371                         dev_dbg(dev,
 372                                 "%s: copy out unsafe %p to safe %p, size %d\n",
 373                                 __func__,buf->ptr, buf->safe, size);
 374                         memcpy(buf->safe, buf->ptr, size);
 375                         break;
 376                 case DMA_BIDIRECTIONAL:
 377                         BUG();  /* is this allowed?  what does it mean? */
 378                 default:
 379                         BUG();
 380                 }
 381                 consistent_sync(buf->safe, size, dir);
 382         } else {
 383                 consistent_sync(dma_to_virt(dev, dma_addr), size, dir);
 384         }
 385 }
 386
 387 /* ************************************************** */
 388
 389 /*
 390  * see if a buffer address is in an 'unsafe' range.  if it is
 391  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 392  * substitute the safe buffer for the unsafe one.
 393  * (basically move the buffer from an unsafe area to a safe one)
 394  */
 395 dma_addr_t
 396 dma_map_single(struct device *dev, void *ptr, size_t size,
 397                 enum dma_data_direction dir)
 398 {
 399         unsigned long flags;
 400         dma_addr_t dma_addr;
 401
 402         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 403                 __func__, ptr, size, dir);
 404
 405         BUG_ON(dir == DMA_NONE);
 406
 407         local_irq_save(flags);
 408
 409         dma_addr = map_single(dev, ptr, size, dir);
 410
 411         local_irq_restore(flags);
 412
 413         return dma_addr;
 414 }
 415
 416 /*
 417  * see if a mapped address was really a "safe" buffer and if so, copy
 418  * the data from the safe buffer back to the unsafe buffer and free up
 419  * the safe buffer.  (basically return things back to the way they
 420  * should be)
 421  */
 422
 423 void
 424 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 425                         enum dma_data_direction dir)
 426 {
 427         unsigned long flags;
 428
 429         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 430                 __func__, (void *) dma_addr, size, dir);
 431
 432         BUG_ON(dir == DMA_NONE);
 433
 434         local_irq_save(flags);
 435
 436         unmap_single(dev, dma_addr, size, dir);
 437
 438         local_irq_restore(flags);
 439 }
 440
 441 int
 442 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 443                 enum dma_data_direction dir)
 444 {
 445         unsigned long flags;
 446         int i;
 447
 448         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 449                 __func__, sg, nents, dir);
 450
 451         BUG_ON(dir == DMA_NONE);
 452
 453         local_irq_save(flags);
 454
 455         for (i = 0; i < nents; i++, sg++) {
 456                 struct page *page = sg->page;
 457                 unsigned int offset = sg->offset;
 458                 unsigned int length = sg->length;
 459                 void *ptr = page_address(page) + offset;
 460
 461                 sg->dma_address =
 462                         map_single(dev, ptr, length, dir);
 463         }
 464
 465         local_irq_restore(flags);
 466
 467         return nents;
 468 }
 469
 470 void
 471 dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 472                 enum dma_data_direction dir)
 473 {
 474         unsigned long flags;
 475         int i;
 476
 477         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 478                 __func__, sg, nents, dir);
 479
 480         BUG_ON(dir == DMA_NONE);
 481
 482         local_irq_save(flags);
 483
 484         for (i = 0; i < nents; i++, sg++) {
 485                 dma_addr_t dma_addr = sg->dma_address;
 486                 unsigned int length = sg->length;
 487
 488                 unmap_single(dev, dma_addr, length, dir);
 489         }
 490
 491         local_irq_restore(flags);
 492 }
 493
 494 void
 495 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size,
 496                                 enum dma_data_direction dir)
 497 {
 498         unsigned long flags;
 499
 500         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 501                 __func__, (void *) dma_addr, size, dir);
 502
 503         local_irq_save(flags);
 504
 505         sync_single(dev, dma_addr, size, dir);
 506
 507         local_irq_restore(flags);
 508 }
 509
 510 void
 511 dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size,
 512                                 enum dma_data_direction dir)
 513 {
 514         unsigned long flags;
 515
 516         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 517                 __func__, (void *) dma_addr, size, dir);
 518
 519         local_irq_save(flags);
 520
 521         sync_single(dev, dma_addr, size, dir);
 522
 523         local_irq_restore(flags);
 524 }
 525
 526 void
 527 dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
 528                         enum dma_data_direction dir)
 529 {
 530         unsigned long flags;
 531         int i;
 532
 533         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 534                 __func__, sg, nents, dir);
 535
 536         BUG_ON(dir == DMA_NONE);
 537
 538         local_irq_save(flags);
 539
 540         for (i = 0; i < nents; i++, sg++) {
 541                 dma_addr_t dma_addr = sg->dma_address;
 542                 unsigned int length = sg->length;
 543
 544                 sync_single(dev, dma_addr, length, dir);
 545         }
 546
 547         local_irq_restore(flags);
 548 }
 549
 550 void
 551 dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
 552                         enum dma_data_direction dir)
 553 {
 554         unsigned long flags;
 555         int i;
 556
 557         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 558                 __func__, sg, nents, dir);
 559
 560         BUG_ON(dir == DMA_NONE);
 561
 562         local_irq_save(flags);
 563
 564         for (i = 0; i < nents; i++, sg++) {
 565                 dma_addr_t dma_addr = sg->dma_address;
 566                 unsigned int length = sg->length;
 567
 568                 sync_single(dev, dma_addr, length, dir);
 569         }
 570
 571         local_irq_restore(flags);
 572 }
 573
 574 static int
 575 dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev, const char *name,
 576                     unsigned long size)
 577 {
 578         pool->size = size;
 579         DO_STATS(pool->allocs = 0);
 580         pool->pool = dma_pool_create(name, dev, size,
 581                                      0 /* byte alignment */,
 582                                      0 /* no page-crossing issues */);
 583
 584         return pool->pool ? 0 : -ENOMEM;
 585 }
 586
 587 int
 588 dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 589                         unsigned long large_buffer_size)
 590 {
 591         struct dmabounce_device_info *device_info;
 592         int ret;
 593
 594         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 595         if (!device_info) {
 596                 printk(KERN_ERR
 597                         "Could not allocated dmabounce_device_info for %s",
 598                         dev->bus_id);
 599                 return -ENOMEM;
 600         }
 601
 602         ret = dmabounce_init_pool(&device_info->small, dev,
 603                                   "small_dmabounce_pool", small_buffer_size);
 604         if (ret) {
 605                 dev_err(dev,
 606                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 607                         small_buffer_size);
 608                 goto err_free;
 609         }
 610
 611         if (large_buffer_size) {
 612                 ret = dmabounce_init_pool(&device_info->large, dev,
 613                                           "large_dmabounce_pool",
 614                                           large_buffer_size);
 615                 if (ret) {
 616                         dev_err(dev,
 617                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 618                                 large_buffer_size);
 619                         goto err_destroy;
 620                 }
 621         }
 622
 623         device_info->dev = dev;
 624         INIT_LIST_HEAD(&device_info->safe_buffers);
 625
 626 #ifdef STATS
 627         device_info->total_allocs = 0;
 628         device_info->map_op_count = 0;
 629         device_info->bounce_count = 0;
 630 #endif
 631
 632         list_add(&device_info->node, &dmabounce_devs);
 633
 634         printk(KERN_INFO "dmabounce: registered device %s on %s bus\n",
 635                 dev->bus_id, dev->bus->name);
 636
 637         return 0;
 638
 639  err_destroy:
 640         dma_pool_destroy(device_info->small.pool);
 641  err_free:
 642         kfree(device_info);
 643         return ret;
 644 }
 645
 646 void
 647 dmabounce_unregister_dev(struct device *dev)
 648 {
 649         struct dmabounce_device_info *device_info = find_dmabounce_dev(dev);
 650
 651         if (!device_info) {
 652                 printk(KERN_WARNING
 653                         "%s: Never registered with dmabounce but attempting" \
 654                         "to unregister!\n", dev->bus_id);
 655                 return;
 656         }
 657
 658         if (!list_empty(&device_info->safe_buffers)) {
 659                 printk(KERN_ERR
 660                         "%s: Removing from dmabounce with pending buffers!\n",
 661                         dev->bus_id);
 662                 BUG();
 663         }
 664
 665         if (device_info->small.pool)
 666                 dma_pool_destroy(device_info->small.pool);
 667         if (device_info->large.pool)
 668                 dma_pool_destroy(device_info->large.pool);
 669
 670 #ifdef STATS
 671         print_alloc_stats(device_info);
 672         print_map_stats(device_info);
 673 #endif
 674
 675         list_del(&device_info->node);
 676
 677         kfree(device_info);
 678
 679         printk(KERN_INFO "dmabounce: device %s on %s bus unregistered\n",
 680                 dev->bus_id, dev->bus->name);
 681 }
 682
 683
 684 EXPORT_SYMBOL(dma_map_single);
 685 EXPORT_SYMBOL(dma_unmap_single);
 686 EXPORT_SYMBOL(dma_map_sg);
 687 EXPORT_SYMBOL(dma_unmap_sg);
 688 EXPORT_SYMBOL(dma_sync_single);
 689 EXPORT_SYMBOL(dma_sync_sg);
 690 EXPORT_SYMBOL(dmabounce_register_dev);
 691 EXPORT_SYMBOL(dmabounce_unregister_dev);
 692
 693 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 694 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 695 MODULE_LICENSE("GPL");