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 #include "mm.h"
  29
  30 static u64 get_coherent_dma_mask(struct device *dev)
  31 {
  32         u64 mask = (u64)arm_dma_limit;
  33
  34         if (dev) {
  35                 mask = dev->coherent_dma_mask;
  36
  37                 /*
  38                  * Sanity check the DMA mask - it must be non-zero, and
  39                  * must be able to be satisfied by a DMA allocation.
  40                  */
  41                 if (mask == 0) {
  42                         dev_warn(dev, "coherent DMA mask is unset\n");
  43                         return 0;
  44                 }
  45
  46                 if ((~mask) & (u64)arm_dma_limit) {
  47                         dev_warn(dev, "coherent DMA mask %#llx is smaller "
  48                                  "than system GFP_DMA mask %#llx\n",
  49                                  mask, (u64)arm_dma_limit);
  50                         return 0;
  51                 }
  52         }
  53
  54         return mask;
  55 }
  56
  57 /*
  58  * Allocate a DMA buffer for 'dev' of size 'size' using the
  59  * specified gfp mask.  Note that 'size' must be page aligned.
  60  */
  61 static struct page *__dma_alloc_buffer(struct device *dev, size_t size, gfp_t gfp)
  62 {
  63         unsigned long order = get_order(size);
  64         struct page *page, *p, *e;
  65         void *ptr;
  66         u64 mask = get_coherent_dma_mask(dev);
  67
  68 #ifdef CONFIG_DMA_API_DEBUG
  69         u64 limit = (mask + 1) & ~mask;
  70         if (limit && size >= limit) {
  71                 dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n",
  72                         size, mask);
  73                 return NULL;
  74         }
  75 #endif
  76
  77         if (!mask)
  78                 return NULL;
  79
  80         if (mask < 0xffffffffULL)
  81                 gfp |= GFP_DMA;
  82
  83         page = alloc_pages(gfp, order);
  84         if (!page)
  85                 return NULL;
  86
  87         /*
  88          * Now split the huge page and free the excess pages
  89          */
  90         split_page(page, order);
  91         for (p = page + (size >> PAGE_SHIFT), e = page + (1 << order); p < e; p++)
  92                 __free_page(p);
  93
  94         /*
  95          * Ensure that the allocated pages are zeroed, and that any data
  96          * lurking in the kernel direct-mapped region is invalidated.
  97          */
  98         ptr = page_address(page);
  99         memset(ptr, 0, size);
 100         dmac_flush_range(ptr, ptr + size);
 101         outer_flush_range(__pa(ptr), __pa(ptr) + size);
 102
 103         return page;
 104 }
 105
 106 /*
 107  * Free a DMA buffer.  'size' must be page aligned.
 108  */
 109 static void __dma_free_buffer(struct page *page, size_t size)
 110 {
 111         struct page *e = page + (size >> PAGE_SHIFT);
 112
 113         while (page < e) {
 114                 __free_page(page);
 115                 page++;
 116         }
 117 }
 118
 119 #ifdef CONFIG_MMU
 120 /* Sanity check size */
 121 #if (CONSISTENT_DMA_SIZE % SZ_2M)
 122 #error "CONSISTENT_DMA_SIZE must be multiple of 2MiB"
 123 #endif
 124
 125 #define CONSISTENT_OFFSET(x)    (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
 126 #define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PMD_SHIFT)
 127 #define NUM_CONSISTENT_PTES (CONSISTENT_DMA_SIZE >> PMD_SHIFT)
 128
 129 /*
 130  * These are the page tables (2MB each) covering uncached, DMA consistent allocations
 131  */
 132 static pte_t *consistent_pte[NUM_CONSISTENT_PTES];
 133
 134 #include "vmregion.h"
 135
 136 static struct arm_vmregion_head consistent_head = {
 137         .vm_lock        = __SPIN_LOCK_UNLOCKED(&consistent_head.vm_lock),
 138         .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
 139         .vm_start       = CONSISTENT_BASE,
 140         .vm_end         = CONSISTENT_END,
 141 };
 142
 143 #ifdef CONFIG_HUGETLB_PAGE
 144 #error ARM Coherent DMA allocator does not (yet) support huge TLB
 145 #endif
 146
 147 /*
 148  * Initialise the consistent memory allocation.
 149  */
 150 static int __init consistent_init(void)
 151 {
 152         int ret = 0;
 153         pgd_t *pgd;
 154         pud_t *pud;
 155         pmd_t *pmd;
 156         pte_t *pte;
 157         int i = 0;
 158         u32 base = CONSISTENT_BASE;
 159
 160         do {
 161                 pgd = pgd_offset(&init_mm, base);
 162
 163                 pud = pud_alloc(&init_mm, pgd, base);
 164                 if (!pud) {
 165                         printk(KERN_ERR "%s: no pud tables\n", __func__);
 166                         ret = -ENOMEM;
 167                         break;
 168                 }
 169
 170                 pmd = pmd_alloc(&init_mm, pud, base);
 171                 if (!pmd) {
 172                         printk(KERN_ERR "%s: no pmd tables\n", __func__);
 173                         ret = -ENOMEM;
 174                         break;
 175                 }
 176                 WARN_ON(!pmd_none(*pmd));
 177
 178                 pte = pte_alloc_kernel(pmd, base);
 179                 if (!pte) {
 180                         printk(KERN_ERR "%s: no pte tables\n", __func__);
 181                         ret = -ENOMEM;
 182                         break;
 183                 }
 184
 185                 consistent_pte[i++] = pte;
 186                 base += (1 << PMD_SHIFT);
 187         } while (base < CONSISTENT_END);
 188
 189         return ret;
 190 }
 191
 192 core_initcall(consistent_init);
 193
 194 static void *
 195 __dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
 196 {
 197         struct arm_vmregion *c;
 198         size_t align;
 199         int bit;
 200
 201         if (!consistent_pte[0]) {
 202                 printk(KERN_ERR "%s: not initialised\n", __func__);
 203                 dump_stack();
 204                 return NULL;
 205         }
 206
 207         /*
 208          * Align the virtual region allocation - maximum alignment is
 209          * a section size, minimum is a page size.  This helps reduce
 210          * fragmentation of the DMA space, and also prevents allocations
 211          * smaller than a section from crossing a section boundary.
 212          */
 213         bit = fls(size - 1);
 214         if (bit > SECTION_SHIFT)
 215                 bit = SECTION_SHIFT;
 216         align = 1 << bit;
 217
 218         /*
 219          * Allocate a virtual address in the consistent mapping region.
 220          */
 221         c = arm_vmregion_alloc(&consistent_head, align, size,
 222                             gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
 223         if (c) {
 224                 pte_t *pte;
 225                 int idx = CONSISTENT_PTE_INDEX(c->vm_start);
 226                 u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 227
 228                 pte = consistent_pte[idx] + off;
 229                 c->vm_pages = page;
 230
 231                 do {
 232                         BUG_ON(!pte_none(*pte));
 233
 234                         set_pte_ext(pte, mk_pte(page, prot), 0);
 235                         page++;
 236                         pte++;
 237                         off++;
 238                         if (off >= PTRS_PER_PTE) {
 239                                 off = 0;
 240                                 pte = consistent_pte[++idx];
 241                         }
 242                 } while (size -= PAGE_SIZE);
 243
 244                 dsb();
 245
 246                 return (void *)c->vm_start;
 247         }
 248         return NULL;
 249 }
 250
 251 static void __dma_free_remap(void *cpu_addr, size_t size)
 252 {
 253         struct arm_vmregion *c;
 254         unsigned long addr;
 255         pte_t *ptep;
 256         int idx;
 257         u32 off;
 258
 259         c = arm_vmregion_find_remove(&consistent_head, (unsigned long)cpu_addr);
 260         if (!c) {
 261                 printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
 262                        __func__, cpu_addr);
 263                 dump_stack();
 264                 return;
 265         }
 266
 267         if ((c->vm_end - c->vm_start) != size) {
 268                 printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
 269                        __func__, c->vm_end - c->vm_start, size);
 270                 dump_stack();
 271                 size = c->vm_end - c->vm_start;
 272         }
 273
 274         idx = CONSISTENT_PTE_INDEX(c->vm_start);
 275         off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 276         ptep = consistent_pte[idx] + off;
 277         addr = c->vm_start;
 278         do {
 279                 pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
 280
 281                 ptep++;
 282                 addr += PAGE_SIZE;
 283                 off++;
 284                 if (off >= PTRS_PER_PTE) {
 285                         off = 0;
 286                         ptep = consistent_pte[++idx];
 287                 }
 288
 289                 if (pte_none(pte) || !pte_present(pte))
 290                         printk(KERN_CRIT "%s: bad page in kernel page table\n",
 291                                __func__);
 292         } while (size -= PAGE_SIZE);
 293
 294         flush_tlb_kernel_range(c->vm_start, c->vm_end);
 295
 296         arm_vmregion_free(&consistent_head, c);
 297 }
 298
 299 #else   /* !CONFIG_MMU */
 300
 301 #define __dma_alloc_remap(page, size, gfp, prot)        page_address(page)
 302 #define __dma_free_remap(addr, size)                    do { } while (0)
 303
 304 #endif  /* CONFIG_MMU */
 305
 306 static void *
 307 __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
 308             pgprot_t prot)
 309 {
 310         struct page *page;
 311         void *addr;
 312
 313         *handle = ~0;
 314         size = PAGE_ALIGN(size);
 315
 316         page = __dma_alloc_buffer(dev, size, gfp);
 317         if (!page)
 318                 return NULL;
 319
 320         if (!arch_is_coherent())
 321                 addr = __dma_alloc_remap(page, size, gfp, prot);
 322         else
 323                 addr = page_address(page);
 324
 325         if (addr)
 326                 *handle = pfn_to_dma(dev, page_to_pfn(page));
 327
 328         return addr;
 329 }
 330
 331 /*
 332  * Allocate DMA-coherent memory space and return both the kernel remapped
 333  * virtual and bus address for that space.
 334  */
 335 void *
 336 dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 337 {
 338         void *memory;
 339
 340         if (dma_alloc_from_coherent(dev, size, handle, &memory))
 341                 return memory;
 342
 343         return __dma_alloc(dev, size, handle, gfp,
 344                            pgprot_dmacoherent(pgprot_kernel));
 345 }
 346 EXPORT_SYMBOL(dma_alloc_coherent);
 347
 348 /*
 349  * Allocate a writecombining region, in much the same way as
 350  * dma_alloc_coherent above.
 351  */
 352 void *
 353 dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 354 {
 355         return __dma_alloc(dev, size, handle, gfp,
 356                            pgprot_writecombine(pgprot_kernel));
 357 }
 358 EXPORT_SYMBOL(dma_alloc_writecombine);
 359
 360 static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
 361                     void *cpu_addr, dma_addr_t dma_addr, size_t size)
 362 {
 363         int ret = -ENXIO;
 364 #ifdef CONFIG_MMU
 365         unsigned long user_size, kern_size;
 366         struct arm_vmregion *c;
 367
 368         user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 369
 370         c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
 371         if (c) {
 372                 unsigned long off = vma->vm_pgoff;
 373
 374                 kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
 375
 376                 if (off < kern_size &&
 377                     user_size <= (kern_size - off)) {
 378                         ret = remap_pfn_range(vma, vma->vm_start,
 379                                               page_to_pfn(c->vm_pages) + off,
 380                                               user_size << PAGE_SHIFT,
 381                                               vma->vm_page_prot);
 382                 }
 383         }
 384 #endif  /* CONFIG_MMU */
 385
 386         return ret;
 387 }
 388
 389 int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
 390                       void *cpu_addr, dma_addr_t dma_addr, size_t size)
 391 {
 392         vma->vm_page_prot = pgprot_dmacoherent(vma->vm_page_prot);
 393         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 394 }
 395 EXPORT_SYMBOL(dma_mmap_coherent);
 396
 397 int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
 398                           void *cpu_addr, dma_addr_t dma_addr, size_t size)
 399 {
 400         vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 401         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 402 }
 403 EXPORT_SYMBOL(dma_mmap_writecombine);
 404
 405 /*
 406  * free a page as defined by the above mapping.
 407  * Must not be called with IRQs disabled.
 408  */
 409 void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
 410 {
 411         WARN_ON(irqs_disabled());
 412
 413         if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
 414                 return;
 415
 416         size = PAGE_ALIGN(size);
 417
 418         if (!arch_is_coherent())
 419                 __dma_free_remap(cpu_addr, size);
 420
 421         __dma_free_buffer(pfn_to_page(dma_to_pfn(dev, handle)), size);
 422 }
 423 EXPORT_SYMBOL(dma_free_coherent);
 424
 425 /*
 426  * Make an area consistent for devices.
 427  * Note: Drivers should NOT use this function directly, as it will break
 428  * platforms with CONFIG_DMABOUNCE.
 429  * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
 430  */
 431 void ___dma_single_cpu_to_dev(const void *kaddr, size_t size,
 432         enum dma_data_direction dir)
 433 {
 434         unsigned long paddr;
 435
 436         BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));
 437
 438         dmac_map_area(kaddr, size, dir);
 439
 440         paddr = __pa(kaddr);
 441         if (dir == DMA_FROM_DEVICE) {
 442                 outer_inv_range(paddr, paddr + size);
 443         } else {
 444                 outer_clean_range(paddr, paddr + size);
 445         }
 446         /* FIXME: non-speculating: flush on bidirectional mappings? */
 447 }
 448 EXPORT_SYMBOL(___dma_single_cpu_to_dev);
 449
 450 void ___dma_single_dev_to_cpu(const void *kaddr, size_t size,
 451         enum dma_data_direction dir)
 452 {
 453         BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));
 454
 455         /* FIXME: non-speculating: not required */
 456         /* don't bother invalidating if DMA to device */
 457         if (dir != DMA_TO_DEVICE) {
 458                 unsigned long paddr = __pa(kaddr);
 459                 outer_inv_range(paddr, paddr + size);
 460         }
 461
 462         dmac_unmap_area(kaddr, size, dir);
 463 }
 464 EXPORT_SYMBOL(___dma_single_dev_to_cpu);
 465
 466 static void dma_cache_maint_page(struct page *page, unsigned long offset,
 467         size_t size, enum dma_data_direction dir,
 468         void (*op)(const void *, size_t, int))
 469 {
 470         /*
 471          * A single sg entry may refer to multiple physically contiguous
 472          * pages.  But we still need to process highmem pages individually.
 473          * If highmem is not configured then the bulk of this loop gets
 474          * optimized out.
 475          */
 476         size_t left = size;
 477         do {
 478                 size_t len = left;
 479                 void *vaddr;
 480
 481                 if (PageHighMem(page)) {
 482                         if (len + offset > PAGE_SIZE) {
 483                                 if (offset >= PAGE_SIZE) {
 484                                         page += offset / PAGE_SIZE;
 485                                         offset %= PAGE_SIZE;
 486                                 }
 487                                 len = PAGE_SIZE - offset;
 488                         }
 489                         vaddr = kmap_high_get(page);
 490                         if (vaddr) {
 491                                 vaddr += offset;
 492                                 op(vaddr, len, dir);
 493                                 kunmap_high(page);
 494                         } else if (cache_is_vipt()) {
 495                                 /* unmapped pages might still be cached */
 496                                 vaddr = kmap_atomic(page);
 497                                 op(vaddr + offset, len, dir);
 498                                 kunmap_atomic(vaddr);
 499                         }
 500                 } else {
 501                         vaddr = page_address(page) + offset;
 502                         op(vaddr, len, dir);
 503                 }
 504                 offset = 0;
 505                 page++;
 506                 left -= len;
 507         } while (left);
 508 }
 509
 510 void ___dma_page_cpu_to_dev(struct page *page, unsigned long off,
 511         size_t size, enum dma_data_direction dir)
 512 {
 513         unsigned long paddr;
 514
 515         dma_cache_maint_page(page, off, size, dir, dmac_map_area);
 516
 517         paddr = page_to_phys(page) + off;
 518         if (dir == DMA_FROM_DEVICE) {
 519                 outer_inv_range(paddr, paddr + size);
 520         } else {
 521                 outer_clean_range(paddr, paddr + size);
 522         }
 523         /* FIXME: non-speculating: flush on bidirectional mappings? */
 524 }
 525 EXPORT_SYMBOL(___dma_page_cpu_to_dev);
 526
 527 void ___dma_page_dev_to_cpu(struct page *page, unsigned long off,
 528         size_t size, enum dma_data_direction dir)
 529 {
 530         unsigned long paddr = page_to_phys(page) + off;
 531
 532         /* FIXME: non-speculating: not required */
 533         /* don't bother invalidating if DMA to device */
 534         if (dir != DMA_TO_DEVICE)
 535                 outer_inv_range(paddr, paddr + size);
 536
 537         dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);
 538
 539         /*
 540          * Mark the D-cache clean for this page to avoid extra flushing.
 541          */
 542         if (dir != DMA_TO_DEVICE && off == 0 && size >= PAGE_SIZE)
 543                 set_bit(PG_dcache_clean, &page->flags);
 544 }
 545 EXPORT_SYMBOL(___dma_page_dev_to_cpu);
 546
 547 /**
 548  * dma_map_sg - map a set of SG buffers for streaming mode DMA
 549  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 550  * @sg: list of buffers
 551  * @nents: number of buffers to map
 552  * @dir: DMA transfer direction
 553  *
 554  * Map a set of buffers described by scatterlist in streaming mode for DMA.
 555  * This is the scatter-gather version of the dma_map_single interface.
 556  * Here the scatter gather list elements are each tagged with the
 557  * appropriate dma address and length.  They are obtained via
 558  * sg_dma_{address,length}.
 559  *
 560  * Device ownership issues as mentioned for dma_map_single are the same
 561  * here.
 562  */
 563 int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 564                 enum dma_data_direction dir)
 565 {
 566         struct scatterlist *s;
 567         int i, j;
 568
 569         BUG_ON(!valid_dma_direction(dir));
 570
 571         for_each_sg(sg, s, nents, i) {
 572                 s->dma_address = __dma_map_page(dev, sg_page(s), s->offset,
 573                                                 s->length, dir);
 574                 if (dma_mapping_error(dev, s->dma_address))
 575                         goto bad_mapping;
 576         }
 577         debug_dma_map_sg(dev, sg, nents, nents, dir);
 578         return nents;
 579
 580  bad_mapping:
 581         for_each_sg(sg, s, i, j)
 582                 __dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
 583         return 0;
 584 }
 585 EXPORT_SYMBOL(dma_map_sg);
 586
 587 /**
 588  * dma_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
 589  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 590  * @sg: list of buffers
 591  * @nents: number of buffers to unmap (same as was passed to dma_map_sg)
 592  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 593  *
 594  * Unmap a set of streaming mode DMA translations.  Again, CPU access
 595  * rules concerning calls here are the same as for dma_unmap_single().
 596  */
 597 void dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 598                 enum dma_data_direction dir)
 599 {
 600         struct scatterlist *s;
 601         int i;
 602
 603         debug_dma_unmap_sg(dev, sg, nents, dir);
 604
 605         for_each_sg(sg, s, nents, i)
 606                 __dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
 607 }
 608 EXPORT_SYMBOL(dma_unmap_sg);
 609
 610 /**
 611  * dma_sync_sg_for_cpu
 612  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 613  * @sg: list of buffers
 614  * @nents: number of buffers to map (returned from dma_map_sg)
 615  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 616  */
 617 void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
 618                         int nents, enum dma_data_direction dir)
 619 {
 620         struct scatterlist *s;
 621         int i;
 622
 623         for_each_sg(sg, s, nents, i) {
 624                 if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
 625                                             sg_dma_len(s), dir))
 626                         continue;
 627
 628                 __dma_page_dev_to_cpu(sg_page(s), s->offset,
 629                                       s->length, dir);
 630         }
 631
 632         debug_dma_sync_sg_for_cpu(dev, sg, nents, dir);
 633 }
 634 EXPORT_SYMBOL(dma_sync_sg_for_cpu);
 635
 636 /**
 637  * dma_sync_sg_for_device
 638  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 639  * @sg: list of buffers
 640  * @nents: number of buffers to map (returned from dma_map_sg)
 641  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 642  */
 643 void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 644                         int nents, enum dma_data_direction dir)
 645 {
 646         struct scatterlist *s;
 647         int i;
 648
 649         for_each_sg(sg, s, nents, i) {
 650                 if (!dmabounce_sync_for_device(dev, sg_dma_address(s), 0,
 651                                         sg_dma_len(s), dir))
 652                         continue;
 653
 654                 __dma_page_cpu_to_dev(sg_page(s), s->offset,
 655                                       s->length, dir);
 656         }
 657
 658         debug_dma_sync_sg_for_device(dev, sg, nents, dir);
 659 }
 660 EXPORT_SYMBOL(dma_sync_sg_for_device);
 661
 662 /*
 663  * Return whether the given device DMA address mask can be supported
 664  * properly.  For example, if your device can only drive the low 24-bits
 665  * during bus mastering, then you would pass 0x00ffffff as the mask
 666  * to this function.
 667  */
 668 int dma_supported(struct device *dev, u64 mask)
 669 {
 670         if (mask < (u64)arm_dma_limit)
 671                 return 0;
 672         return 1;
 673 }
 674 EXPORT_SYMBOL(dma_supported);
 675
 676 int dma_set_mask(struct device *dev, u64 dma_mask)
 677 {
 678         if (!dev->dma_mask || !dma_supported(dev, dma_mask))
 679                 return -EIO;
 680
 681 #ifndef CONFIG_DMABOUNCE
 682         *dev->dma_mask = dma_mask;
 683 #endif
 684
 685         return 0;
 686 }
 687 EXPORT_SYMBOL(dma_set_mask);
 688
 689 #define PREALLOC_DMA_DEBUG_ENTRIES      4096
 690
 691 static int __init dma_debug_do_init(void)
 692 {
 693         dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
 694         return 0;
 695 }
 696 fs_initcall(dma_debug_do_init);