arch/arm/mm/dma-mapping.c

   1 /*
   2  *  linux/arch/arm/mm/dma-mapping.c
   3  *
   4  *  Copyright (C) 2000-2004 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  DMA uncached mapping support.
  11  */
  12 #include <linux/module.h>
  13 #include <linux/mm.h>
  14 #include <linux/gfp.h>
  15 #include <linux/errno.h>
  16 #include <linux/list.h>
  17 #include <linux/init.h>
  18 #include <linux/device.h>
  19 #include <linux/dma-mapping.h>
  20 #include <linux/highmem.h>
  21
  22 #include <asm/memory.h>
  23 #include <asm/highmem.h>
  24 #include <asm/cacheflush.h>
  25 #include <asm/tlbflush.h>
  26 #include <asm/sizes.h>
  27
  28 static u64 get_coherent_dma_mask(struct device *dev)
  29 {
  30         u64 mask = ISA_DMA_THRESHOLD;
  31
  32         if (dev) {
  33                 mask = dev->coherent_dma_mask;
  34
  35                 /*
  36                  * Sanity check the DMA mask - it must be non-zero, and
  37                  * must be able to be satisfied by a DMA allocation.
  38                  */
  39                 if (mask == 0) {
  40                         dev_warn(dev, "coherent DMA mask is unset\n");
  41                         return 0;
  42                 }
  43
  44                 if ((~mask) & ISA_DMA_THRESHOLD) {
  45                         dev_warn(dev, "coherent DMA mask %#llx is smaller "
  46                                  "than system GFP_DMA mask %#llx\n",
  47                                  mask, (unsigned long long)ISA_DMA_THRESHOLD);
  48                         return 0;
  49                 }
  50         }
  51
  52         return mask;
  53 }
  54
  55 /*
  56  * Allocate a DMA buffer for 'dev' of size 'size' using the
  57  * specified gfp mask.  Note that 'size' must be page aligned.
  58  */
  59 static struct page *__dma_alloc_buffer(struct device *dev, size_t size, gfp_t gfp)
  60 {
  61         unsigned long order = get_order(size);
  62         struct page *page, *p, *e;
  63         void *ptr;
  64         u64 mask = get_coherent_dma_mask(dev);
  65
  66 #ifdef CONFIG_DMA_API_DEBUG
  67         u64 limit = (mask + 1) & ~mask;
  68         if (limit && size >= limit) {
  69                 dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n",
  70                         size, mask);
  71                 return NULL;
  72         }
  73 #endif
  74
  75         if (!mask)
  76                 return NULL;
  77
  78         if (mask < 0xffffffffULL)
  79                 gfp |= GFP_DMA;
  80
  81         page = alloc_pages(gfp, order);
  82         if (!page)
  83                 return NULL;
  84
  85         /*
  86          * Now split the huge page and free the excess pages
  87          */
  88         split_page(page, order);
  89         for (p = page + (size >> PAGE_SHIFT), e = page + (1 << order); p < e; p++)
  90                 __free_page(p);
  91
  92         /*
  93          * Ensure that the allocated pages are zeroed, and that any data
  94          * lurking in the kernel direct-mapped region is invalidated.
  95          */
  96         ptr = page_address(page);
  97         memset(ptr, 0, size);
  98         dmac_flush_range(ptr, ptr + size);
  99         outer_flush_range(__pa(ptr), __pa(ptr) + size);
 100
 101         return page;
 102 }
 103
 104 /*
 105  * Free a DMA buffer.  'size' must be page aligned.
 106  */
 107 static void __dma_free_buffer(struct page *page, size_t size)
 108 {
 109         struct page *e = page + (size >> PAGE_SHIFT);
 110
 111         while (page < e) {
 112                 __free_page(page);
 113                 page++;
 114         }
 115 }
 116
 117 #ifdef CONFIG_MMU
 118 /* Sanity check size */
 119 #if (CONSISTENT_DMA_SIZE % SZ_2M)
 120 #error "CONSISTENT_DMA_SIZE must be multiple of 2MiB"
 121 #endif
 122
 123 #define CONSISTENT_OFFSET(x)    (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
 124 #define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PGDIR_SHIFT)
 125 #define NUM_CONSISTENT_PTES (CONSISTENT_DMA_SIZE >> PGDIR_SHIFT)
 126
 127 /*
 128  * These are the page tables (2MB each) covering uncached, DMA consistent allocations
 129  */
 130 static pte_t *consistent_pte[NUM_CONSISTENT_PTES];
 131
 132 #include "vmregion.h"
 133
 134 static struct arm_vmregion_head consistent_head = {
 135         .vm_lock        = __SPIN_LOCK_UNLOCKED(&consistent_head.vm_lock),
 136         .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
 137         .vm_start       = CONSISTENT_BASE,
 138         .vm_end         = CONSISTENT_END,
 139 };
 140
 141 #ifdef CONFIG_HUGETLB_PAGE
 142 #error ARM Coherent DMA allocator does not (yet) support huge TLB
 143 #endif
 144
 145 /*
 146  * Initialise the consistent memory allocation.
 147  */
 148 static int __init consistent_init(void)
 149 {
 150         int ret = 0;
 151         pgd_t *pgd;
 152         pmd_t *pmd;
 153         pte_t *pte;
 154         int i = 0;
 155         u32 base = CONSISTENT_BASE;
 156
 157         do {
 158                 pgd = pgd_offset(&init_mm, base);
 159                 pmd = pmd_alloc(&init_mm, pgd, base);
 160                 if (!pmd) {
 161                         printk(KERN_ERR "%s: no pmd tables\n", __func__);
 162                         ret = -ENOMEM;
 163                         break;
 164                 }
 165                 WARN_ON(!pmd_none(*pmd));
 166
 167                 pte = pte_alloc_kernel(pmd, base);
 168                 if (!pte) {
 169                         printk(KERN_ERR "%s: no pte tables\n", __func__);
 170                         ret = -ENOMEM;
 171                         break;
 172                 }
 173
 174                 consistent_pte[i++] = pte;
 175                 base += (1 << PGDIR_SHIFT);
 176         } while (base < CONSISTENT_END);
 177
 178         return ret;
 179 }
 180
 181 core_initcall(consistent_init);
 182
 183 static void *
 184 __dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
 185 {
 186         struct arm_vmregion *c;
 187         size_t align;
 188         int bit;
 189
 190         if (!consistent_pte[0]) {
 191                 printk(KERN_ERR "%s: not initialised\n", __func__);
 192                 dump_stack();
 193                 return NULL;
 194         }
 195
 196         /*
 197          * Align the virtual region allocation - maximum alignment is
 198          * a section size, minimum is a page size.  This helps reduce
 199          * fragmentation of the DMA space, and also prevents allocations
 200          * smaller than a section from crossing a section boundary.
 201          */
 202         bit = fls(size - 1);
 203         if (bit > SECTION_SHIFT)
 204                 bit = SECTION_SHIFT;
 205         align = 1 << bit;
 206
 207         /*
 208          * Allocate a virtual address in the consistent mapping region.
 209          */
 210         c = arm_vmregion_alloc(&consistent_head, align, size,
 211                             gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
 212         if (c) {
 213                 pte_t *pte;
 214                 int idx = CONSISTENT_PTE_INDEX(c->vm_start);
 215                 u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 216
 217                 pte = consistent_pte[idx] + off;
 218                 c->vm_pages = page;
 219
 220                 do {
 221                         BUG_ON(!pte_none(*pte));
 222
 223                         set_pte_ext(pte, mk_pte(page, prot), 0);
 224                         page++;
 225                         pte++;
 226                         off++;
 227                         if (off >= PTRS_PER_PTE) {
 228                                 off = 0;
 229                                 pte = consistent_pte[++idx];
 230                         }
 231                 } while (size -= PAGE_SIZE);
 232
 233                 dsb();
 234
 235                 return (void *)c->vm_start;
 236         }
 237         return NULL;
 238 }
 239
 240 static void __dma_free_remap(void *cpu_addr, size_t size)
 241 {
 242         struct arm_vmregion *c;
 243         unsigned long addr;
 244         pte_t *ptep;
 245         int idx;
 246         u32 off;
 247
 248         c = arm_vmregion_find_remove(&consistent_head, (unsigned long)cpu_addr);
 249         if (!c) {
 250                 printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
 251                        __func__, cpu_addr);
 252                 dump_stack();
 253                 return;
 254         }
 255
 256         if ((c->vm_end - c->vm_start) != size) {
 257                 printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
 258                        __func__, c->vm_end - c->vm_start, size);
 259                 dump_stack();
 260                 size = c->vm_end - c->vm_start;
 261         }
 262
 263         idx = CONSISTENT_PTE_INDEX(c->vm_start);
 264         off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 265         ptep = consistent_pte[idx] + off;
 266         addr = c->vm_start;
 267         do {
 268                 pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
 269
 270                 ptep++;
 271                 addr += PAGE_SIZE;
 272                 off++;
 273                 if (off >= PTRS_PER_PTE) {
 274                         off = 0;
 275                         ptep = consistent_pte[++idx];
 276                 }
 277
 278                 if (pte_none(pte) || !pte_present(pte))
 279                         printk(KERN_CRIT "%s: bad page in kernel page table\n",
 280                                __func__);
 281         } while (size -= PAGE_SIZE);
 282
 283         flush_tlb_kernel_range(c->vm_start, c->vm_end);
 284
 285         arm_vmregion_free(&consistent_head, c);
 286 }
 287
 288 #else   /* !CONFIG_MMU */
 289
 290 #define __dma_alloc_remap(page, size, gfp, prot)        page_address(page)
 291 #define __dma_free_remap(addr, size)                    do { } while (0)
 292
 293 #endif  /* CONFIG_MMU */
 294
 295 static void *
 296 __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
 297             pgprot_t prot)
 298 {
 299         struct page *page;
 300         void *addr;
 301
 302         *handle = ~0;
 303         size = PAGE_ALIGN(size);
 304
 305         page = __dma_alloc_buffer(dev, size, gfp);
 306         if (!page)
 307                 return NULL;
 308
 309         if (!arch_is_coherent())
 310                 addr = __dma_alloc_remap(page, size, gfp, prot);
 311         else
 312                 addr = page_address(page);
 313
 314         if (addr)
 315                 *handle = pfn_to_dma(dev, page_to_pfn(page));
 316
 317         return addr;
 318 }
 319
 320 /*
 321  * Allocate DMA-coherent memory space and return both the kernel remapped
 322  * virtual and bus address for that space.
 323  */
 324 void *
 325 dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 326 {
 327         void *memory;
 328
 329         if (dma_alloc_from_coherent(dev, size, handle, &memory))
 330                 return memory;
 331
 332         return __dma_alloc(dev, size, handle, gfp,
 333                            pgprot_dmacoherent(pgprot_kernel));
 334 }
 335 EXPORT_SYMBOL(dma_alloc_coherent);
 336
 337 /*
 338  * Allocate a writecombining region, in much the same way as
 339  * dma_alloc_coherent above.
 340  */
 341 void *
 342 dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 343 {
 344         return __dma_alloc(dev, size, handle, gfp,
 345                            pgprot_writecombine(pgprot_kernel));
 346 }
 347 EXPORT_SYMBOL(dma_alloc_writecombine);
 348
 349 static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
 350                     void *cpu_addr, dma_addr_t dma_addr, size_t size)
 351 {
 352         int ret = -ENXIO;
 353 #ifdef CONFIG_MMU
 354         unsigned long user_size, kern_size;
 355         struct arm_vmregion *c;
 356
 357         user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 358
 359         c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
 360         if (c) {
 361                 unsigned long off = vma->vm_pgoff;
 362
 363                 kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
 364
 365                 if (off < kern_size &&
 366                     user_size <= (kern_size - off)) {
 367                         ret = remap_pfn_range(vma, vma->vm_start,
 368                                               page_to_pfn(c->vm_pages) + off,
 369                                               user_size << PAGE_SHIFT,
 370                                               vma->vm_page_prot);
 371                 }
 372         }
 373 #endif  /* CONFIG_MMU */
 374
 375         return ret;
 376 }
 377
 378 int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
 379                       void *cpu_addr, dma_addr_t dma_addr, size_t size)
 380 {
 381         vma->vm_page_prot = pgprot_dmacoherent(vma->vm_page_prot);
 382         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 383 }
 384 EXPORT_SYMBOL(dma_mmap_coherent);
 385
 386 int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
 387                           void *cpu_addr, dma_addr_t dma_addr, size_t size)
 388 {
 389         vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 390         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 391 }
 392 EXPORT_SYMBOL(dma_mmap_writecombine);
 393
 394 /*
 395  * free a page as defined by the above mapping.
 396  * Must not be called with IRQs disabled.
 397  */
 398 void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
 399 {
 400         WARN_ON(irqs_disabled());
 401
 402         if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
 403                 return;
 404
 405         size = PAGE_ALIGN(size);
 406
 407         if (!arch_is_coherent())
 408                 __dma_free_remap(cpu_addr, size);
 409
 410         __dma_free_buffer(pfn_to_page(dma_to_pfn(dev, handle)), size);
 411 }
 412 EXPORT_SYMBOL(dma_free_coherent);
 413
 414 /*
 415  * Make an area consistent for devices.
 416  * Note: Drivers should NOT use this function directly, as it will break
 417  * platforms with CONFIG_DMABOUNCE.
 418  * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
 419  */
 420 void ___dma_single_cpu_to_dev(const void *kaddr, size_t size,
 421         enum dma_data_direction dir)
 422 {
 423         unsigned long paddr;
 424
 425         BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));
 426
 427         dmac_map_area(kaddr, size, dir);
 428
 429         paddr = __pa(kaddr);
 430         if (dir == DMA_FROM_DEVICE) {
 431                 outer_inv_range(paddr, paddr + size);
 432         } else {
 433                 outer_clean_range(paddr, paddr + size);
 434         }
 435         /* FIXME: non-speculating: flush on bidirectional mappings? */
 436 }
 437 EXPORT_SYMBOL(___dma_single_cpu_to_dev);
 438
 439 void ___dma_single_dev_to_cpu(const void *kaddr, size_t size,
 440         enum dma_data_direction dir)
 441 {
 442         BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));
 443
 444         /* FIXME: non-speculating: not required */
 445         /* don't bother invalidating if DMA to device */
 446         if (dir != DMA_TO_DEVICE) {
 447                 unsigned long paddr = __pa(kaddr);
 448                 outer_inv_range(paddr, paddr + size);
 449         }
 450
 451         dmac_unmap_area(kaddr, size, dir);
 452 }
 453 EXPORT_SYMBOL(___dma_single_dev_to_cpu);
 454
 455 static void dma_cache_maint_page(struct page *page, unsigned long offset,
 456         size_t size, enum dma_data_direction dir,
 457         void (*op)(const void *, size_t, int))
 458 {
 459         /*
 460          * A single sg entry may refer to multiple physically contiguous
 461          * pages.  But we still need to process highmem pages individually.
 462          * If highmem is not configured then the bulk of this loop gets
 463          * optimized out.
 464          */
 465         size_t left = size;
 466         do {
 467                 size_t len = left;
 468                 void *vaddr;
 469
 470                 if (PageHighMem(page)) {
 471                         if (len + offset > PAGE_SIZE) {
 472                                 if (offset >= PAGE_SIZE) {
 473                                         page += offset / PAGE_SIZE;
 474                                         offset %= PAGE_SIZE;
 475                                 }
 476                                 len = PAGE_SIZE - offset;
 477                         }
 478                         vaddr = kmap_high_get(page);
 479                         if (vaddr) {
 480                                 vaddr += offset;
 481                                 op(vaddr, len, dir);
 482                                 kunmap_high(page);
 483                         } else if (cache_is_vipt()) {
 484                                 /* unmapped pages might still be cached */
 485                                 vaddr = kmap_atomic(page);
 486                                 op(vaddr + offset, len, dir);
 487                                 kunmap_atomic(vaddr);
 488                         }
 489                 } else {
 490                         vaddr = page_address(page) + offset;
 491                         op(vaddr, len, dir);
 492                 }
 493                 offset = 0;
 494                 page++;
 495                 left -= len;
 496         } while (left);
 497 }
 498
 499 void ___dma_page_cpu_to_dev(struct page *page, unsigned long off,
 500         size_t size, enum dma_data_direction dir)
 501 {
 502         unsigned long paddr;
 503
 504         dma_cache_maint_page(page, off, size, dir, dmac_map_area);
 505
 506         paddr = page_to_phys(page) + off;
 507         if (dir == DMA_FROM_DEVICE) {
 508                 outer_inv_range(paddr, paddr + size);
 509         } else {
 510                 outer_clean_range(paddr, paddr + size);
 511         }
 512         /* FIXME: non-speculating: flush on bidirectional mappings? */
 513 }
 514 EXPORT_SYMBOL(___dma_page_cpu_to_dev);
 515
 516 void ___dma_page_dev_to_cpu(struct page *page, unsigned long off,
 517         size_t size, enum dma_data_direction dir)
 518 {
 519         unsigned long paddr = page_to_phys(page) + off;
 520
 521         /* FIXME: non-speculating: not required */
 522         /* don't bother invalidating if DMA to device */
 523         if (dir != DMA_TO_DEVICE)
 524                 outer_inv_range(paddr, paddr + size);
 525
 526         dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);
 527
 528         /*
 529          * Mark the D-cache clean for this page to avoid extra flushing.
 530          */
 531         if (dir != DMA_TO_DEVICE && off == 0 && size >= PAGE_SIZE)
 532                 set_bit(PG_dcache_clean, &page->flags);
 533 }
 534 EXPORT_SYMBOL(___dma_page_dev_to_cpu);
 535
 536 /**
 537  * dma_map_sg - map a set of SG buffers for streaming mode DMA
 538  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 539  * @sg: list of buffers
 540  * @nents: number of buffers to map
 541  * @dir: DMA transfer direction
 542  *
 543  * Map a set of buffers described by scatterlist in streaming mode for DMA.
 544  * This is the scatter-gather version of the dma_map_single interface.
 545  * Here the scatter gather list elements are each tagged with the
 546  * appropriate dma address and length.  They are obtained via
 547  * sg_dma_{address,length}.
 548  *
 549  * Device ownership issues as mentioned for dma_map_single are the same
 550  * here.
 551  */
 552 int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 553                 enum dma_data_direction dir)
 554 {
 555         struct scatterlist *s;
 556         int i, j;
 557
 558         BUG_ON(!valid_dma_direction(dir));
 559
 560         for_each_sg(sg, s, nents, i) {
 561                 s->dma_address = __dma_map_page(dev, sg_page(s), s->offset,
 562                                                 s->length, dir);
 563                 if (dma_mapping_error(dev, s->dma_address))
 564                         goto bad_mapping;
 565         }
 566         debug_dma_map_sg(dev, sg, nents, nents, dir);
 567         return nents;
 568
 569  bad_mapping:
 570         for_each_sg(sg, s, i, j)
 571                 __dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
 572         return 0;
 573 }
 574 EXPORT_SYMBOL(dma_map_sg);
 575
 576 /**
 577  * dma_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
 578  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 579  * @sg: list of buffers
 580  * @nents: number of buffers to unmap (same as was passed to dma_map_sg)
 581  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 582  *
 583  * Unmap a set of streaming mode DMA translations.  Again, CPU access
 584  * rules concerning calls here are the same as for dma_unmap_single().
 585  */
 586 void dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 587                 enum dma_data_direction dir)
 588 {
 589         struct scatterlist *s;
 590         int i;
 591
 592         debug_dma_unmap_sg(dev, sg, nents, dir);
 593
 594         for_each_sg(sg, s, nents, i)
 595                 __dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
 596 }
 597 EXPORT_SYMBOL(dma_unmap_sg);
 598
 599 /**
 600  * dma_sync_sg_for_cpu
 601  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 602  * @sg: list of buffers
 603  * @nents: number of buffers to map (returned from dma_map_sg)
 604  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 605  */
 606 void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
 607                         int nents, enum dma_data_direction dir)
 608 {
 609         struct scatterlist *s;
 610         int i;
 611
 612         for_each_sg(sg, s, nents, i) {
 613                 if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
 614                                             sg_dma_len(s), dir))
 615                         continue;
 616
 617                 __dma_page_dev_to_cpu(sg_page(s), s->offset,
 618                                       s->length, dir);
 619         }
 620
 621         debug_dma_sync_sg_for_cpu(dev, sg, nents, dir);
 622 }
 623 EXPORT_SYMBOL(dma_sync_sg_for_cpu);
 624
 625 /**
 626  * dma_sync_sg_for_device
 627  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 628  * @sg: list of buffers
 629  * @nents: number of buffers to map (returned from dma_map_sg)
 630  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 631  */
 632 void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 633                         int nents, enum dma_data_direction dir)
 634 {
 635         struct scatterlist *s;
 636         int i;
 637
 638         for_each_sg(sg, s, nents, i) {
 639                 if (!dmabounce_sync_for_device(dev, sg_dma_address(s), 0,
 640                                         sg_dma_len(s), dir))
 641                         continue;
 642
 643                 __dma_page_cpu_to_dev(sg_page(s), s->offset,
 644                                       s->length, dir);
 645         }
 646
 647         debug_dma_sync_sg_for_device(dev, sg, nents, dir);
 648 }
 649 EXPORT_SYMBOL(dma_sync_sg_for_device);
 650
 651 #define PREALLOC_DMA_DEBUG_ENTRIES      4096
 652
 653 static int __init dma_debug_do_init(void)
 654 {
 655         dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
 656         return 0;
 657 }
 658 fs_initcall(dma_debug_do_init);