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-direct.h>
  28 #include <linux/dma-map-ops.h>
  29 #include <linux/dmapool.h>
  30 #include <linux/list.h>
  31 #include <linux/scatterlist.h>
  32
  33 #include <asm/cacheflush.h>
  34 #include <asm/dma-iommu.h>
  35
  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 device *dev;
  70         struct list_head safe_buffers;
  71 #ifdef STATS
  72         unsigned long total_allocs;
  73         unsigned long map_op_count;
  74         unsigned long bounce_count;
  75         int attr_res;
  76 #endif
  77         struct dmabounce_pool   small;
  78         struct dmabounce_pool   large;
  79
  80         rwlock_t lock;
  81
  82         int (*needs_bounce)(struct device *, dma_addr_t, size_t);
  83 };
  84
  85 #ifdef STATS
  86 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
  87                               char *buf)
  88 {
  89         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
  90         return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
  91                 device_info->small.allocs,
  92                 device_info->large.allocs,
  93                 device_info->total_allocs - device_info->small.allocs -
  94                         device_info->large.allocs,
  95                 device_info->total_allocs,
  96                 device_info->map_op_count,
  97                 device_info->bounce_count);
  98 }
  99
 100 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
 101 #endif
 102
 103
 104 /* allocate a 'safe' buffer and keep track of it */
 105 static inline struct safe_buffer *
 106 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 107                   size_t size, enum dma_data_direction dir)
 108 {
 109         struct safe_buffer *buf;
 110         struct dmabounce_pool *pool;
 111         struct device *dev = device_info->dev;
 112         unsigned long flags;
 113
 114         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 115                 __func__, ptr, size, dir);
 116
 117         if (size <= device_info->small.size) {
 118                 pool = &device_info->small;
 119         } else if (size <= device_info->large.size) {
 120                 pool = &device_info->large;
 121         } else {
 122                 pool = NULL;
 123         }
 124
 125         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 126         if (buf == NULL) {
 127                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 128                 return NULL;
 129         }
 130
 131         buf->ptr = ptr;
 132         buf->size = size;
 133         buf->direction = dir;
 134         buf->pool = pool;
 135
 136         if (pool) {
 137                 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
 138                                            &buf->safe_dma_addr);
 139         } else {
 140                 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
 141                                                GFP_ATOMIC);
 142         }
 143
 144         if (buf->safe == NULL) {
 145                 dev_warn(dev,
 146                          "%s: could not alloc dma memory (size=%d)\n",
 147                          __func__, size);
 148                 kfree(buf);
 149                 return NULL;
 150         }
 151
 152 #ifdef STATS
 153         if (pool)
 154                 pool->allocs++;
 155         device_info->total_allocs++;
 156 #endif
 157
 158         write_lock_irqsave(&device_info->lock, flags);
 159         list_add(&buf->node, &device_info->safe_buffers);
 160         write_unlock_irqrestore(&device_info->lock, flags);
 161
 162         return buf;
 163 }
 164
 165 /* determine if a buffer is from our "safe" pool */
 166 static inline struct safe_buffer *
 167 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 168 {
 169         struct safe_buffer *b, *rb = NULL;
 170         unsigned long flags;
 171
 172         read_lock_irqsave(&device_info->lock, flags);
 173
 174         list_for_each_entry(b, &device_info->safe_buffers, node)
 175                 if (b->safe_dma_addr <= safe_dma_addr &&
 176                     b->safe_dma_addr + b->size > safe_dma_addr) {
 177                         rb = b;
 178                         break;
 179                 }
 180
 181         read_unlock_irqrestore(&device_info->lock, flags);
 182         return rb;
 183 }
 184
 185 static inline void
 186 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 187 {
 188         unsigned long flags;
 189
 190         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 191
 192         write_lock_irqsave(&device_info->lock, flags);
 193
 194         list_del(&buf->node);
 195
 196         write_unlock_irqrestore(&device_info->lock, flags);
 197
 198         if (buf->pool)
 199                 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
 200         else
 201                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 202                                     buf->safe_dma_addr);
 203
 204         kfree(buf);
 205 }
 206
 207 /* ************************************************** */
 208
 209 static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
 210                 dma_addr_t dma_addr, const char *where)
 211 {
 212         if (!dev || !dev->archdata.dmabounce)
 213                 return NULL;
 214         if (dma_mapping_error(dev, dma_addr)) {
 215                 dev_err(dev, "Trying to %s invalid mapping\n", where);
 216                 return NULL;
 217         }
 218         return find_safe_buffer(dev->archdata.dmabounce, dma_addr);
 219 }
 220
 221 static int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
 222 {
 223         if (!dev || !dev->archdata.dmabounce)
 224                 return 0;
 225
 226         if (dev->dma_mask) {
 227                 unsigned long limit, mask = *dev->dma_mask;
 228
 229                 limit = (mask + 1) & ~mask;
 230                 if (limit && size > limit) {
 231                         dev_err(dev, "DMA mapping too big (requested %#x "
 232                                 "mask %#Lx)\n", size, *dev->dma_mask);
 233                         return -E2BIG;
 234                 }
 235
 236                 /* Figure out if we need to bounce from the DMA mask. */
 237                 if ((dma_addr | (dma_addr + size - 1)) & ~mask)
 238                         return 1;
 239         }
 240
 241         return !!dev->archdata.dmabounce->needs_bounce(dev, dma_addr, size);
 242 }
 243
 244 static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
 245                                     enum dma_data_direction dir,
 246                                     unsigned long attrs)
 247 {
 248         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 249         struct safe_buffer *buf;
 250
 251         if (device_info)
 252                 DO_STATS ( device_info->map_op_count++ );
 253
 254         buf = alloc_safe_buffer(device_info, ptr, size, dir);
 255         if (buf == NULL) {
 256                 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 257                        __func__, ptr);
 258                 return DMA_MAPPING_ERROR;
 259         }
 260
 261         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 262                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 263                 buf->safe, buf->safe_dma_addr);
 264
 265         if ((dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) &&
 266             !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
 267                 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 268                         __func__, ptr, buf->safe, size);
 269                 memcpy(buf->safe, ptr, size);
 270         }
 271
 272         return buf->safe_dma_addr;
 273 }
 274
 275 static inline void unmap_single(struct device *dev, struct safe_buffer *buf,
 276                                 size_t size, enum dma_data_direction dir,
 277                                 unsigned long attrs)
 278 {
 279         BUG_ON(buf->size != size);
 280         BUG_ON(buf->direction != dir);
 281
 282         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 283                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 284                 buf->safe, buf->safe_dma_addr);
 285
 286         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 287
 288         if ((dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) &&
 289             !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
 290                 void *ptr = buf->ptr;
 291
 292                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 293                         __func__, buf->safe, ptr, size);
 294                 memcpy(ptr, buf->safe, size);
 295
 296                 /*
 297                  * Since we may have written to a page cache page,
 298                  * we need to ensure that the data will be coherent
 299                  * with user mappings.
 300                  */
 301                 __cpuc_flush_dcache_area(ptr, size);
 302         }
 303         free_safe_buffer(dev->archdata.dmabounce, buf);
 304 }
 305
 306 /* ************************************************** */
 307
 308 /*
 309  * see if a buffer address is in an 'unsafe' range.  if it is
 310  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 311  * substitute the safe buffer for the unsafe one.
 312  * (basically move the buffer from an unsafe area to a safe one)
 313  */
 314 static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page,
 315                 unsigned long offset, size_t size, enum dma_data_direction dir,
 316                 unsigned long attrs)
 317 {
 318         dma_addr_t dma_addr;
 319         int ret;
 320
 321         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
 322                 __func__, page, offset, size, dir);
 323
 324         dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset;
 325
 326         ret = needs_bounce(dev, dma_addr, size);
 327         if (ret < 0)
 328                 return DMA_MAPPING_ERROR;
 329
 330         if (ret == 0) {
 331                 arm_dma_ops.sync_single_for_device(dev, dma_addr, size, dir);
 332                 return dma_addr;
 333         }
 334
 335         if (PageHighMem(page)) {
 336                 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
 337                 return DMA_MAPPING_ERROR;
 338         }
 339
 340         return map_single(dev, page_address(page) + offset, size, dir, attrs);
 341 }
 342
 343 /*
 344  * see if a mapped address was really a "safe" buffer and if so, copy
 345  * the data from the safe buffer back to the unsafe buffer and free up
 346  * the safe buffer.  (basically return things back to the way they
 347  * should be)
 348  */
 349 static void dmabounce_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
 350                 enum dma_data_direction dir, unsigned long attrs)
 351 {
 352         struct safe_buffer *buf;
 353
 354         dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n",
 355                 __func__, dma_addr, size, dir);
 356
 357         buf = find_safe_buffer_dev(dev, dma_addr, __func__);
 358         if (!buf) {
 359                 arm_dma_ops.sync_single_for_cpu(dev, dma_addr, size, dir);
 360                 return;
 361         }
 362
 363         unmap_single(dev, buf, size, dir, attrs);
 364 }
 365
 366 static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 367                 size_t sz, enum dma_data_direction dir)
 368 {
 369         struct safe_buffer *buf;
 370         unsigned long off;
 371
 372         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
 373                 __func__, addr, sz, dir);
 374
 375         buf = find_safe_buffer_dev(dev, addr, __func__);
 376         if (!buf)
 377                 return 1;
 378
 379         off = addr - buf->safe_dma_addr;
 380
 381         BUG_ON(buf->direction != dir);
 382
 383         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
 384                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
 385                 buf->safe, buf->safe_dma_addr);
 386
 387         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 388
 389         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 390                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 391                         __func__, buf->safe + off, buf->ptr + off, sz);
 392                 memcpy(buf->ptr + off, buf->safe + off, sz);
 393         }
 394         return 0;
 395 }
 396
 397 static void dmabounce_sync_for_cpu(struct device *dev,
 398                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 399 {
 400         if (!__dmabounce_sync_for_cpu(dev, handle, size, dir))
 401                 return;
 402
 403         arm_dma_ops.sync_single_for_cpu(dev, handle, size, dir);
 404 }
 405
 406 static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 407                 size_t sz, enum dma_data_direction dir)
 408 {
 409         struct safe_buffer *buf;
 410         unsigned long off;
 411
 412         dev_dbg(dev, "%s(dma=%#x,sz=%zx,dir=%x)\n",
 413                 __func__, addr, sz, dir);
 414
 415         buf = find_safe_buffer_dev(dev, addr, __func__);
 416         if (!buf)
 417                 return 1;
 418
 419         off = addr - buf->safe_dma_addr;
 420
 421         BUG_ON(buf->direction != dir);
 422
 423         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n",
 424                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,
 425                 buf->safe, buf->safe_dma_addr);
 426
 427         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 428
 429         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
 430                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
 431                         __func__,buf->ptr + off, buf->safe + off, sz);
 432                 memcpy(buf->safe + off, buf->ptr + off, sz);
 433         }
 434         return 0;
 435 }
 436
 437 static void dmabounce_sync_for_device(struct device *dev,
 438                 dma_addr_t handle, size_t size, enum dma_data_direction dir)
 439 {
 440         if (!__dmabounce_sync_for_device(dev, handle, size, dir))
 441                 return;
 442
 443         arm_dma_ops.sync_single_for_device(dev, handle, size, dir);
 444 }
 445
 446 static int dmabounce_dma_supported(struct device *dev, u64 dma_mask)
 447 {
 448         if (dev->archdata.dmabounce)
 449                 return 0;
 450
 451         return arm_dma_ops.dma_supported(dev, dma_mask);
 452 }
 453
 454 static const struct dma_map_ops dmabounce_ops = {
 455         .alloc                  = arm_dma_alloc,
 456         .free                   = arm_dma_free,
 457         .mmap                   = arm_dma_mmap,
 458         .get_sgtable            = arm_dma_get_sgtable,
 459         .map_page               = dmabounce_map_page,
 460         .unmap_page             = dmabounce_unmap_page,
 461         .sync_single_for_cpu    = dmabounce_sync_for_cpu,
 462         .sync_single_for_device = dmabounce_sync_for_device,
 463         .map_sg                 = arm_dma_map_sg,
 464         .unmap_sg               = arm_dma_unmap_sg,
 465         .sync_sg_for_cpu        = arm_dma_sync_sg_for_cpu,
 466         .sync_sg_for_device     = arm_dma_sync_sg_for_device,
 467         .dma_supported          = dmabounce_dma_supported,
 468 };
 469
 470 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
 471                 const char *name, unsigned long size)
 472 {
 473         pool->size = size;
 474         DO_STATS(pool->allocs = 0);
 475         pool->pool = dma_pool_create(name, dev, size,
 476                                      0 /* byte alignment */,
 477                                      0 /* no page-crossing issues */);
 478
 479         return pool->pool ? 0 : -ENOMEM;
 480 }
 481
 482 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 483                 unsigned long large_buffer_size,
 484                 int (*needs_bounce_fn)(struct device *, dma_addr_t, size_t))
 485 {
 486         struct dmabounce_device_info *device_info;
 487         int ret;
 488
 489         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 490         if (!device_info) {
 491                 dev_err(dev,
 492                         "Could not allocated dmabounce_device_info\n");
 493                 return -ENOMEM;
 494         }
 495
 496         ret = dmabounce_init_pool(&device_info->small, dev,
 497                                   "small_dmabounce_pool", small_buffer_size);
 498         if (ret) {
 499                 dev_err(dev,
 500                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 501                         small_buffer_size);
 502                 goto err_free;
 503         }
 504
 505         if (large_buffer_size) {
 506                 ret = dmabounce_init_pool(&device_info->large, dev,
 507                                           "large_dmabounce_pool",
 508                                           large_buffer_size);
 509                 if (ret) {
 510                         dev_err(dev,
 511                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 512                                 large_buffer_size);
 513                         goto err_destroy;
 514                 }
 515         }
 516
 517         device_info->dev = dev;
 518         INIT_LIST_HEAD(&device_info->safe_buffers);
 519         rwlock_init(&device_info->lock);
 520         device_info->needs_bounce = needs_bounce_fn;
 521
 522 #ifdef STATS
 523         device_info->total_allocs = 0;
 524         device_info->map_op_count = 0;
 525         device_info->bounce_count = 0;
 526         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 527 #endif
 528
 529         dev->archdata.dmabounce = device_info;
 530         set_dma_ops(dev, &dmabounce_ops);
 531
 532         dev_info(dev, "dmabounce: registered device\n");
 533
 534         return 0;
 535
 536  err_destroy:
 537         dma_pool_destroy(device_info->small.pool);
 538  err_free:
 539         kfree(device_info);
 540         return ret;
 541 }
 542 EXPORT_SYMBOL(dmabounce_register_dev);
 543
 544 void dmabounce_unregister_dev(struct device *dev)
 545 {
 546         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 547
 548         dev->archdata.dmabounce = NULL;
 549         set_dma_ops(dev, NULL);
 550
 551         if (!device_info) {
 552                 dev_warn(dev,
 553                          "Never registered with dmabounce but attempting"
 554                          "to unregister!\n");
 555                 return;
 556         }
 557
 558         if (!list_empty(&device_info->safe_buffers)) {
 559                 dev_err(dev,
 560                         "Removing from dmabounce with pending buffers!\n");
 561                 BUG();
 562         }
 563
 564         if (device_info->small.pool)
 565                 dma_pool_destroy(device_info->small.pool);
 566         if (device_info->large.pool)
 567                 dma_pool_destroy(device_info->large.pool);
 568
 569 #ifdef STATS
 570         if (device_info->attr_res == 0)
 571                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 572 #endif
 573
 574         kfree(device_info);
 575
 576         dev_info(dev, "dmabounce: device unregistered\n");
 577 }
 578 EXPORT_SYMBOL(dmabounce_unregister_dev);
 579
 580 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 581 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 582 MODULE_LICENSE("GPL");