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 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 STATS
  36
  37 #ifdef STATS
  38 #define DO_STATS(X) do { X ; } while (0)
  39 #else
  40 #define DO_STATS(X) do { } while (0)
  41 #endif
  42
  43 /* ************************************************** */
  44
  45 struct safe_buffer {
  46         struct list_head node;
  47
  48         /* original request */
  49         void            *ptr;
  50         size_t          size;
  51         int             direction;
  52
  53         /* safe buffer info */
  54         struct dmabounce_pool *pool;
  55         void            *safe;
  56         dma_addr_t      safe_dma_addr;
  57 };
  58
  59 struct dmabounce_pool {
  60         unsigned long   size;
  61         struct dma_pool *pool;
  62 #ifdef STATS
  63         unsigned long   allocs;
  64 #endif
  65 };
  66
  67 struct dmabounce_device_info {
  68         struct device *dev;
  69         struct list_head safe_buffers;
  70 #ifdef STATS
  71         unsigned long total_allocs;
  72         unsigned long map_op_count;
  73         unsigned long bounce_count;
  74         int attr_res;
  75 #endif
  76         struct dmabounce_pool   small;
  77         struct dmabounce_pool   large;
  78
  79         rwlock_t lock;
  80 };
  81
  82 #ifdef STATS
  83 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
  84                               char *buf)
  85 {
  86         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
  87         return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
  88                 device_info->small.allocs,
  89                 device_info->large.allocs,
  90                 device_info->total_allocs - device_info->small.allocs -
  91                         device_info->large.allocs,
  92                 device_info->total_allocs,
  93                 device_info->map_op_count,
  94                 device_info->bounce_count);
  95 }
  96
  97 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
  98 #endif
  99
 100
 101 /* allocate a 'safe' buffer and keep track of it */
 102 static inline struct safe_buffer *
 103 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 104                   size_t size, enum dma_data_direction dir)
 105 {
 106         struct safe_buffer *buf;
 107         struct dmabounce_pool *pool;
 108         struct device *dev = device_info->dev;
 109         unsigned long flags;
 110
 111         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 112                 __func__, ptr, size, dir);
 113
 114         if (size <= device_info->small.size) {
 115                 pool = &device_info->small;
 116         } else if (size <= device_info->large.size) {
 117                 pool = &device_info->large;
 118         } else {
 119                 pool = NULL;
 120         }
 121
 122         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 123         if (buf == NULL) {
 124                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 125                 return NULL;
 126         }
 127
 128         buf->ptr = ptr;
 129         buf->size = size;
 130         buf->direction = dir;
 131         buf->pool = pool;
 132
 133         if (pool) {
 134                 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
 135                                            &buf->safe_dma_addr);
 136         } else {
 137                 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
 138                                                GFP_ATOMIC);
 139         }
 140
 141         if (buf->safe == NULL) {
 142                 dev_warn(dev,
 143                          "%s: could not alloc dma memory (size=%d)\n",
 144                          __func__, size);
 145                 kfree(buf);
 146                 return NULL;
 147         }
 148
 149 #ifdef STATS
 150         if (pool)
 151                 pool->allocs++;
 152         device_info->total_allocs++;
 153 #endif
 154
 155         write_lock_irqsave(&device_info->lock, flags);
 156
 157         list_add(&buf->node, &device_info->safe_buffers);
 158
 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 inline dma_addr_t
 208 map_single(struct device *dev, void *ptr, size_t size,
 209                 enum dma_data_direction dir)
 210 {
 211         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 212         dma_addr_t dma_addr;
 213         int needs_bounce = 0;
 214
 215         if (device_info)
 216                 DO_STATS ( device_info->map_op_count++ );
 217
 218         dma_addr = virt_to_dma(dev, ptr);
 219
 220         if (dev->dma_mask) {
 221                 unsigned long mask = *dev->dma_mask;
 222                 unsigned long limit;
 223
 224                 limit = (mask + 1) & ~mask;
 225                 if (limit && size > limit) {
 226                         dev_err(dev, "DMA mapping too big (requested %#x "
 227                                 "mask %#Lx)\n", size, *dev->dma_mask);
 228                         return ~0;
 229                 }
 230
 231                 /*
 232                  * Figure out if we need to bounce from the DMA mask.
 233                  */
 234                 needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
 235         }
 236
 237         if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
 238                 struct safe_buffer *buf;
 239
 240                 buf = alloc_safe_buffer(device_info, ptr, size, dir);
 241                 if (buf == 0) {
 242                         dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 243                                __func__, ptr);
 244                         return 0;
 245                 }
 246
 247                 dev_dbg(dev,
 248                         "%s: unsafe buffer %p (phy=%p) mapped to %p (phy=%p)\n",
 249                         __func__, buf->ptr, (void *) virt_to_dma(dev, buf->ptr),
 250                         buf->safe, (void *) buf->safe_dma_addr);
 251
 252                 if ((dir == DMA_TO_DEVICE) ||
 253                     (dir == DMA_BIDIRECTIONAL)) {
 254                         dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 255                                 __func__, ptr, buf->safe, size);
 256                         memcpy(buf->safe, ptr, size);
 257                 }
 258                 ptr = buf->safe;
 259
 260                 dma_addr = buf->safe_dma_addr;
 261         } else {
 262                 /*
 263                  * We don't need to sync the DMA buffer since
 264                  * it was allocated via the coherent allocators.
 265                  */
 266                 consistent_sync(ptr, size, dir);
 267         }
 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 = dev->archdata.dmabounce;
 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                         void *ptr = buf->ptr;
 302
 303                         dev_dbg(dev,
 304                                 "%s: copy back safe %p to unsafe %p size %d\n",
 305                                 __func__, buf->safe, ptr, size);
 306                         memcpy(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                         dmac_clean_range(ptr, ptr + size);
 317                         outer_clean_range(__pa(ptr), __pa(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 = dev->archdata.dmabounce;
 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                 /*
 382                  * No need to sync the safe buffer - it was allocated
 383                  * via the coherent allocators.
 384                  */
 385         } else {
 386                 consistent_sync(dma_to_virt(dev, dma_addr), size, dir);
 387         }
 388 }
 389
 390 /* ************************************************** */
 391
 392 /*
 393  * see if a buffer address is in an 'unsafe' range.  if it is
 394  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 395  * substitute the safe buffer for the unsafe one.
 396  * (basically move the buffer from an unsafe area to a safe one)
 397  */
 398 dma_addr_t
 399 dma_map_single(struct device *dev, void *ptr, size_t size,
 400                 enum dma_data_direction dir)
 401 {
 402         dma_addr_t dma_addr;
 403
 404         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 405                 __func__, ptr, size, dir);
 406
 407         BUG_ON(dir == DMA_NONE);
 408
 409         dma_addr = map_single(dev, ptr, size, dir);
 410
 411         return dma_addr;
 412 }
 413
 414 /*
 415  * see if a mapped address was really a "safe" buffer and if so, copy
 416  * the data from the safe buffer back to the unsafe buffer and free up
 417  * the safe buffer.  (basically return things back to the way they
 418  * should be)
 419  */
 420
 421 void
 422 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 423                         enum dma_data_direction dir)
 424 {
 425         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 426                 __func__, (void *) dma_addr, size, dir);
 427
 428         BUG_ON(dir == DMA_NONE);
 429
 430         unmap_single(dev, dma_addr, size, dir);
 431 }
 432
 433 int
 434 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 435                 enum dma_data_direction dir)
 436 {
 437         int i;
 438
 439         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 440                 __func__, sg, nents, dir);
 441
 442         BUG_ON(dir == DMA_NONE);
 443
 444         for (i = 0; i < nents; i++, sg++) {
 445                 struct page *page = sg->page;
 446                 unsigned int offset = sg->offset;
 447                 unsigned int length = sg->length;
 448                 void *ptr = page_address(page) + offset;
 449
 450                 sg->dma_address =
 451                         map_single(dev, ptr, length, dir);
 452         }
 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         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         for (i = 0; i < nents; i++, sg++) {
 469                 dma_addr_t dma_addr = sg->dma_address;
 470                 unsigned int length = sg->length;
 471
 472                 unmap_single(dev, dma_addr, length, dir);
 473         }
 474 }
 475
 476 void
 477 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_addr, size_t size,
 478                                 enum dma_data_direction dir)
 479 {
 480         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 481                 __func__, (void *) dma_addr, size, dir);
 482
 483         sync_single(dev, dma_addr, size, dir);
 484 }
 485
 486 void
 487 dma_sync_single_for_device(struct device *dev, dma_addr_t dma_addr, size_t size,
 488                                 enum dma_data_direction dir)
 489 {
 490         dev_dbg(dev, "%s(ptr=%p,size=%d,dir=%x)\n",
 491                 __func__, (void *) dma_addr, size, dir);
 492
 493         sync_single(dev, dma_addr, size, dir);
 494 }
 495
 496 void
 497 dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nents,
 498                         enum dma_data_direction dir)
 499 {
 500         int i;
 501
 502         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 503                 __func__, sg, nents, dir);
 504
 505         BUG_ON(dir == DMA_NONE);
 506
 507         for (i = 0; i < nents; i++, sg++) {
 508                 dma_addr_t dma_addr = sg->dma_address;
 509                 unsigned int length = sg->length;
 510
 511                 sync_single(dev, dma_addr, length, dir);
 512         }
 513 }
 514
 515 void
 516 dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
 517                         enum dma_data_direction dir)
 518 {
 519         int i;
 520
 521         dev_dbg(dev, "%s(sg=%p,nents=%d,dir=%x)\n",
 522                 __func__, sg, nents, dir);
 523
 524         BUG_ON(dir == DMA_NONE);
 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
 534 static int
 535 dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev, const char *name,
 536                     unsigned long size)
 537 {
 538         pool->size = size;
 539         DO_STATS(pool->allocs = 0);
 540         pool->pool = dma_pool_create(name, dev, size,
 541                                      0 /* byte alignment */,
 542                                      0 /* no page-crossing issues */);
 543
 544         return pool->pool ? 0 : -ENOMEM;
 545 }
 546
 547 int
 548 dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 549                         unsigned long large_buffer_size)
 550 {
 551         struct dmabounce_device_info *device_info;
 552         int ret;
 553
 554         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 555         if (!device_info) {
 556                 printk(KERN_ERR
 557                         "Could not allocated dmabounce_device_info for %s",
 558                         dev->bus_id);
 559                 return -ENOMEM;
 560         }
 561
 562         ret = dmabounce_init_pool(&device_info->small, dev,
 563                                   "small_dmabounce_pool", small_buffer_size);
 564         if (ret) {
 565                 dev_err(dev,
 566                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 567                         small_buffer_size);
 568                 goto err_free;
 569         }
 570
 571         if (large_buffer_size) {
 572                 ret = dmabounce_init_pool(&device_info->large, dev,
 573                                           "large_dmabounce_pool",
 574                                           large_buffer_size);
 575                 if (ret) {
 576                         dev_err(dev,
 577                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 578                                 large_buffer_size);
 579                         goto err_destroy;
 580                 }
 581         }
 582
 583         device_info->dev = dev;
 584         INIT_LIST_HEAD(&device_info->safe_buffers);
 585         rwlock_init(&device_info->lock);
 586
 587 #ifdef STATS
 588         device_info->total_allocs = 0;
 589         device_info->map_op_count = 0;
 590         device_info->bounce_count = 0;
 591         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 592 #endif
 593
 594         dev->archdata.dmabounce = device_info;
 595
 596         printk(KERN_INFO "dmabounce: registered device %s on %s bus\n",
 597                 dev->bus_id, dev->bus->name);
 598
 599         return 0;
 600
 601  err_destroy:
 602         dma_pool_destroy(device_info->small.pool);
 603  err_free:
 604         kfree(device_info);
 605         return ret;
 606 }
 607
 608 void
 609 dmabounce_unregister_dev(struct device *dev)
 610 {
 611         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 612
 613         dev->archdata.dmabounce = NULL;
 614
 615         if (!device_info) {
 616                 printk(KERN_WARNING
 617                         "%s: Never registered with dmabounce but attempting" \
 618                         "to unregister!\n", dev->bus_id);
 619                 return;
 620         }
 621
 622         if (!list_empty(&device_info->safe_buffers)) {
 623                 printk(KERN_ERR
 624                         "%s: Removing from dmabounce with pending buffers!\n",
 625                         dev->bus_id);
 626                 BUG();
 627         }
 628
 629         if (device_info->small.pool)
 630                 dma_pool_destroy(device_info->small.pool);
 631         if (device_info->large.pool)
 632                 dma_pool_destroy(device_info->large.pool);
 633
 634 #ifdef STATS
 635         if (device_info->attr_res == 0)
 636                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 637 #endif
 638
 639         kfree(device_info);
 640
 641         printk(KERN_INFO "dmabounce: device %s on %s bus unregistered\n",
 642                 dev->bus_id, dev->bus->name);
 643 }
 644
 645
 646 EXPORT_SYMBOL(dma_map_single);
 647 EXPORT_SYMBOL(dma_unmap_single);
 648 EXPORT_SYMBOL(dma_map_sg);
 649 EXPORT_SYMBOL(dma_unmap_sg);
 650 EXPORT_SYMBOL(dma_sync_single_for_cpu);
 651 EXPORT_SYMBOL(dma_sync_single_for_device);
 652 EXPORT_SYMBOL(dma_sync_sg);
 653 EXPORT_SYMBOL(dmabounce_register_dev);
 654 EXPORT_SYMBOL(dmabounce_unregister_dev);
 655
 656 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 657 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 658 MODULE_LICENSE("GPL");