arch/arm/common/dmabounce.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  arch/arm/common/dmabounce.c
   4  *
   5  *  Special dma_{map/unmap/dma_sync}_* routines for systems that have
   6  *  limited DMA windows. These functions utilize bounce buffers to
   7  *  copy data to/from buffers located outside the DMA region. This
   8  *  only works for systems in which DMA memory is at the bottom of
   9  *  RAM, the remainder of memory is at the top and the DMA memory
  10  *  can be marked as ZONE_DMA. Anything beyond that such as discontiguous
  11  *  DMA windows will require custom implementations that reserve memory
  12  *  areas at early bootup.
  13  *
  14  *  Original version by Brad Parker (brad@heeltoe.com)
  15  *  Re-written by Christopher Hoover <ch@murgatroid.com>
  16  *  Made generic by Deepak Saxena <dsaxena@plexity.net>
  17  *
  18  *  Copyright (C) 2002 Hewlett Packard Company.
  19  *  Copyright (C) 2004 MontaVista Software, Inc.
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/init.h>
  24 #include <linux/slab.h>
  25 #include <linux/page-flags.h>
  26 #include <linux/device.h>
  27 #include <linux/dma-mapping.h>
  28 #include <linux/dmapool.h>
  29 #include <linux/list.h>
  30 #include <linux/scatterlist.h>
  31
  32 #include <asm/cacheflush.h>
  33 #include <asm/dma-iommu.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         int (*needs_bounce)(struct device *, dma_addr_t, size_t);
  82 };
  83
  84 #ifdef STATS
  85 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
  86                               char *buf)
  87 {
  88         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
  89         return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
  90                 device_info->small.allocs,
  91                 device_info->large.allocs,
  92                 device_info->total_allocs - device_info->small.allocs -
  93                         device_info->large.allocs,
  94                 device_info->total_allocs,
  95                 device_info->map_op_count,
  96                 device_info->bounce_count);
  97 }
  98
  99 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
 100 #endif
 101
 102
 103 /* allocate a 'safe' buffer and keep track of it */
 104 static inline struct safe_buffer *
 105 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 106                   size_t size, enum dma_data_direction dir)
 107 {
 108         struct safe_buffer *buf;
 109         struct dmabounce_pool *pool;
 110         struct device *dev = device_info->dev;
 111         unsigned long flags;
 112
 113         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 114                 __func__, ptr, size, dir);
 115
 116         if (size <= device_info->small.size) {
 117                 pool = &device_info->small;
 118         } else if (size <= device_info->large.size) {
 119                 pool = &device_info->large;
 120         } else {
 121                 pool = NULL;
 122         }
 123
 124         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 125         if (buf == NULL) {
 126                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 127                 return NULL;
 128         }
 129
 130         buf->ptr = ptr;
 131         buf->size = size;
 132         buf->direction = dir;
 133         buf->pool = pool;
 134
 135         if (pool) {
 136                 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
 137                                            &buf->safe_dma_addr);
 138         } else {
 139                 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
 140                                                GFP_ATOMIC);
 141         }
 142
 143         if (buf->safe == NULL) {
 144                 dev_warn(dev,
 145                          "%s: could not alloc dma memory (size=%d)\n",
 146                          __func__, size);
 147                 kfree(buf);
 148                 return NULL;
 149         }
 150
 151 #ifdef STATS
 152         if (pool)
 153                 pool->allocs++;
 154         device_info->total_allocs++;
 155 #endif
 156
 157         write_lock_irqsave(&device_info->lock, flags);
 158         list_add(&buf->node, &device_info->safe_buffers);
 159         write_unlock_irqrestore(&device_info->lock, flags);
 160
 161         return buf;
 162 }
 163
 164 /* determine if a buffer is from our "safe" pool */
 165 static inline struct safe_buffer *
 166 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 167 {
 168         struct safe_buffer *b, *rb = NULL;
 169         unsigned long flags;
 170
 171         read_lock_irqsave(&device_info->lock, flags);
 172
 173         list_for_each_entry(b, &device_info->safe_buffers, node)
 174                 if (b->safe_dma_addr <= safe_dma_addr &&
 175                     b->safe_dma_addr + b->size > safe_dma_addr) {
 176                         rb = b;
 177                         break;
 178                 }
 179
 180         read_unlock_irqrestore(&device_info->lock, flags);
 181         return rb;
 182 }
 183
 184 static inline void
 185 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 186 {
 187         unsigned long flags;
 188
 189         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 190
 191         write_lock_irqsave(&device_info->lock, flags);
 192
 193         list_del(&buf->node);
 194
 195         write_unlock_irqrestore(&device_info->lock, flags);
 196
 197         if (buf->pool)
 198                 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
 199         else
 200                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 201                                     buf->safe_dma_addr);
 202
 203         kfree(buf);
 204 }
 205
 206 /* ************************************************** */
 207
 208 static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
 209                 dma_addr_t dma_addr, const char *where)
 210 {
 211         if (!dev || !dev->archdata.dmabounce)
 212                 return NULL;
 213         if (dma_mapping_error(dev, dma_addr)) {
 214                 dev_err(dev, "Trying to %s invalid mapping\n", where);
 215                 return NULL;
 216         }
 217         return find_safe_buffer(dev->archdata.dmabounce, dma_addr);
 218 }
 219
 220 static int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
 221 {
 222         if (!dev || !dev->archdata.dmabounce)
 223                 return 0;
 224
 225         if (dev->dma_mask) {
 226                 unsigned long limit, mask = *dev->dma_mask;
 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 -E2BIG;
 233                 }
 234
 235                 /* Figure out if we need to bounce from the DMA mask. */
 236                 if ((dma_addr | (dma_addr + size - 1)) & ~mask)
 237                         return 1;
 238         }
 239
 240         return !!dev->archdata.dmabounce->needs_bounce(dev, dma_addr, size);
 241 }
 242
 243 static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
 244                                     enum dma_data_direction dir,
 245                                     unsigned long attrs)
 246 {
 247         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 248         struct safe_buffer *buf;
 249
 250         if (device_info)
 251                 DO_STATS ( device_info->map_op_count++ );
 252
 253         buf = alloc_safe_buffer(device_info, ptr, size, dir);
 254         if (buf == NULL) {
 255                 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 256                        __func__, ptr);
 257                 return DMA_MAPPING_ERROR;
 258         }
 259
 260         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 261                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 262                 buf->safe, buf->safe_dma_addr);
 263
 264         if ((dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) &&
 265             !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
 266                 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 267                         __func__, ptr, buf->safe, size);
 268                 memcpy(buf->safe, ptr, size);
 269         }
 270
 271         return buf->safe_dma_addr;
 272 }
 273
 274 static inline void unmap_single(struct device *dev, struct safe_buffer *buf,
 275                                 size_t size, enum dma_data_direction dir,
 276                                 unsigned long attrs)
 277 {
 278         BUG_ON(buf->size != size);
 279         BUG_ON(buf->direction != dir);
 280
 281         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 282                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 283                 buf->safe, buf->safe_dma_addr);
 284
 285         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 286
 287         if ((dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) &&
 288             !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
 289                 void *ptr = buf->ptr;
 290
 291                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 292                         __func__, buf->safe, ptr, size);
 293                 memcpy(ptr, buf->safe, size);
 294
 295                 /*
 296                  * Since we may have written to a page cache page,
 297                  * we need to ensure that the data will be coherent
 298                  * with user mappings.
 299                  */
 300                 __cpuc_flush_dcache_area(ptr, size);
 301         }
 302         free_safe_buffer(dev->archdata.dmabounce, buf);
 303 }
 304
 305 /* ************************************************** */
 306
 307 /*
 308  * see if a buffer address is in an 'unsafe' range.  if it is
 309  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 310  * substitute the safe buffer for the unsafe one.
 311  * (basically move the buffer from an unsafe area to a safe one)
 312  */
 313 static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page,
 314                 unsigned long offset, size_t size, enum dma_data_direction dir,
 315                 unsigned long attrs)
 316 {
 317         dma_addr_t dma_addr;
 318         int ret;
 319
 320         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
 321                 __func__, page, offset, size, dir);
 322
 323         dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset;
 324
 325         ret = needs_bounce(dev, dma_addr, size);
 326         if (ret < 0)
 327                 return DMA_MAPPING_ERROR;
 328
 329         if (ret == 0) {
 330                 arm_dma_ops.sync_single_for_device(dev, dma_addr, size, dir);
 331                 return dma_addr;
 332         }
 333
 334         if (PageHighMem(page)) {
 335                 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
 336                 return DMA_MAPPING_ERROR;
 337         }
 338
 339         return map_single(dev, page_address(page) + offset, size, dir, attrs);
 340 }
 341
 342 /*
 343  * see if a mapped address was really a "safe" buffer and if so, copy
 344  * the data from the safe buffer back to the unsafe buffer and free up
 345  * the safe buffer.  (basically return things back to the way they
 346  * should be)
 347  */
 348 static void dmabounce_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
 349                 enum dma_data_direction dir, unsigned long attrs)
 350 {
 351         struct safe_buffer *buf;
 352
 353         dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n",
 354                 __func__, dma_addr, size, dir);
 355
 356         buf = find_safe_buffer_dev(dev, dma_addr, __func__);
 357         if (!buf) {
 358                 arm_dma_ops.sync_single_for_cpu(dev, dma_addr, size, dir);
 359                 return;
 360         }
 361
 362         unmap_single(dev, buf, size, dir, attrs);
 363 }
 364
 365 static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 366                 size_t sz, enum dma_data_direction dir)
 367 {
 368         struct safe_buffer *buf;
 369         unsigned long off;
 370
 371         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
 372                 __func__, addr, sz, dir);
 373
 374         buf = find_safe_buffer_dev(dev, addr, __func__);
 375         if (!buf)
 376                 return 1;
 377
 378         off = addr - buf->safe_dma_addr;
 379
 380         BUG_ON(buf->direction != dir);
 381
 382         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
 383                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
 384                 buf->safe, buf->safe_dma_addr);
 385
 386         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 387
 388         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 389                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 390                         __func__, buf->safe + off, buf->ptr + off, sz);
 391                 memcpy(buf->ptr + off, buf->safe + off, sz);
 392         }
 393         return 0;
 394 }
 395
 396 static void dmabounce_sync_for_cpu(struct device *dev,
 397                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 398 {
 399         if (!__dmabounce_sync_for_cpu(dev, handle, size, dir))
 400                 return;
 401
 402         arm_dma_ops.sync_single_for_cpu(dev, handle, size, dir);
 403 }
 404
 405 static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 406                 size_t sz, enum dma_data_direction dir)
 407 {
 408         struct safe_buffer *buf;
 409         unsigned long off;
 410
 411         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
 412                 __func__, addr, sz, dir);
 413
 414         buf = find_safe_buffer_dev(dev, addr, __func__);
 415         if (!buf)
 416                 return 1;
 417
 418         off = addr - buf->safe_dma_addr;
 419
 420         BUG_ON(buf->direction != dir);
 421
 422         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
 423                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
 424                 buf->safe, buf->safe_dma_addr);
 425
 426         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 427
 428         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
 429                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
 430                         __func__,buf->ptr + off, buf->safe + off, sz);
 431                 memcpy(buf->safe + off, buf->ptr + off, sz);
 432         }
 433         return 0;
 434 }
 435
 436 static void dmabounce_sync_for_device(struct device *dev,
 437                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 438 {
 439         if (!__dmabounce_sync_for_device(dev, handle, size, dir))
 440                 return;
 441
 442         arm_dma_ops.sync_single_for_device(dev, handle, size, dir);
 443 }
 444
 445 static int dmabounce_dma_supported(struct device *dev, u64 dma_mask)
 446 {
 447         if (dev->archdata.dmabounce)
 448                 return 0;
 449
 450         return arm_dma_ops.dma_supported(dev, dma_mask);
 451 }
 452
 453 static const struct dma_map_ops dmabounce_ops = {
 454         .alloc                  = arm_dma_alloc,
 455         .free                   = arm_dma_free,
 456         .mmap                   = arm_dma_mmap,
 457         .get_sgtable            = arm_dma_get_sgtable,
 458         .map_page               = dmabounce_map_page,
 459         .unmap_page             = dmabounce_unmap_page,
 460         .sync_single_for_cpu    = dmabounce_sync_for_cpu,
 461         .sync_single_for_device = dmabounce_sync_for_device,
 462         .map_sg                 = arm_dma_map_sg,
 463         .unmap_sg               = arm_dma_unmap_sg,
 464         .sync_sg_for_cpu        = arm_dma_sync_sg_for_cpu,
 465         .sync_sg_for_device     = arm_dma_sync_sg_for_device,
 466         .dma_supported          = dmabounce_dma_supported,
 467 };
 468
 469 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
 470                 const char *name, unsigned long size)
 471 {
 472         pool->size = size;
 473         DO_STATS(pool->allocs = 0);
 474         pool->pool = dma_pool_create(name, dev, size,
 475                                      0 /* byte alignment */,
 476                                      0 /* no page-crossing issues */);
 477
 478         return pool->pool ? 0 : -ENOMEM;
 479 }
 480
 481 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 482                 unsigned long large_buffer_size,
 483                 int (*needs_bounce_fn)(struct device *, dma_addr_t, size_t))
 484 {
 485         struct dmabounce_device_info *device_info;
 486         int ret;
 487
 488         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 489         if (!device_info) {
 490                 dev_err(dev,
 491                         "Could not allocated dmabounce_device_info\n");
 492                 return -ENOMEM;
 493         }
 494
 495         ret = dmabounce_init_pool(&device_info->small, dev,
 496                                   "small_dmabounce_pool", small_buffer_size);
 497         if (ret) {
 498                 dev_err(dev,
 499                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 500                         small_buffer_size);
 501                 goto err_free;
 502         }
 503
 504         if (large_buffer_size) {
 505                 ret = dmabounce_init_pool(&device_info->large, dev,
 506                                           "large_dmabounce_pool",
 507                                           large_buffer_size);
 508                 if (ret) {
 509                         dev_err(dev,
 510                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 511                                 large_buffer_size);
 512                         goto err_destroy;
 513                 }
 514         }
 515
 516         device_info->dev = dev;
 517         INIT_LIST_HEAD(&device_info->safe_buffers);
 518         rwlock_init(&device_info->lock);
 519         device_info->needs_bounce = needs_bounce_fn;
 520
 521 #ifdef STATS
 522         device_info->total_allocs = 0;
 523         device_info->map_op_count = 0;
 524         device_info->bounce_count = 0;
 525         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 526 #endif
 527
 528         dev->archdata.dmabounce = device_info;
 529         set_dma_ops(dev, &dmabounce_ops);
 530
 531         dev_info(dev, "dmabounce: registered device\n");
 532
 533         return 0;
 534
 535  err_destroy:
 536         dma_pool_destroy(device_info->small.pool);
 537  err_free:
 538         kfree(device_info);
 539         return ret;
 540 }
 541 EXPORT_SYMBOL(dmabounce_register_dev);
 542
 543 void dmabounce_unregister_dev(struct device *dev)
 544 {
 545         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 546
 547         dev->archdata.dmabounce = NULL;
 548         set_dma_ops(dev, NULL);
 549
 550         if (!device_info) {
 551                 dev_warn(dev,
 552                          "Never registered with dmabounce but attempting"
 553                          "to unregister!\n");
 554                 return;
 555         }
 556
 557         if (!list_empty(&device_info->safe_buffers)) {
 558                 dev_err(dev,
 559                         "Removing from dmabounce with pending buffers!\n");
 560                 BUG();
 561         }
 562
 563         if (device_info->small.pool)
 564                 dma_pool_destroy(device_info->small.pool);
 565         if (device_info->large.pool)
 566                 dma_pool_destroy(device_info->large.pool);
 567
 568 #ifdef STATS
 569         if (device_info->attr_res == 0)
 570                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 571 #endif
 572
 573         kfree(device_info);
 574
 575         dev_info(dev, "dmabounce: device unregistered\n");
 576 }
 577 EXPORT_SYMBOL(dmabounce_unregister_dev);
 578
 579 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 580 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 581 MODULE_LICENSE("GPL");