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 #include <linux/slab.h>
  22
  23 #include <asm/memory.h>
  24 #include <asm/highmem.h>
  25 #include <asm/cacheflush.h>
  26 #include <asm/tlbflush.h>
  27 #include <asm/sizes.h>
  28 #include <asm/mach/arch.h>
  29
  30 #include "mm.h"
  31
  32 static u64 get_coherent_dma_mask(struct device *dev)
  33 {
  34         u64 mask = (u64)arm_dma_limit;
  35
  36         if (dev) {
  37                 mask = dev->coherent_dma_mask;
  38
  39                 /*
  40                  * Sanity check the DMA mask - it must be non-zero, and
  41                  * must be able to be satisfied by a DMA allocation.
  42                  */
  43                 if (mask == 0) {
  44                         dev_warn(dev, "coherent DMA mask is unset\n");
  45                         return 0;
  46                 }
  47
  48                 if ((~mask) & (u64)arm_dma_limit) {
  49                         dev_warn(dev, "coherent DMA mask %#llx is smaller "
  50                                  "than system GFP_DMA mask %#llx\n",
  51                                  mask, (u64)arm_dma_limit);
  52                         return 0;
  53                 }
  54         }
  55
  56         return mask;
  57 }
  58
  59 /*
  60  * Allocate a DMA buffer for 'dev' of size 'size' using the
  61  * specified gfp mask.  Note that 'size' must be page aligned.
  62  */
  63 static struct page *__dma_alloc_buffer(struct device *dev, size_t size, gfp_t gfp)
  64 {
  65         unsigned long order = get_order(size);
  66         struct page *page, *p, *e;
  67         void *ptr;
  68         u64 mask = get_coherent_dma_mask(dev);
  69
  70 #ifdef CONFIG_DMA_API_DEBUG
  71         u64 limit = (mask + 1) & ~mask;
  72         if (limit && size >= limit) {
  73                 dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n",
  74                         size, mask);
  75                 return NULL;
  76         }
  77 #endif
  78
  79         if (!mask)
  80                 return NULL;
  81
  82         if (mask < 0xffffffffULL)
  83                 gfp |= GFP_DMA;
  84
  85         page = alloc_pages(gfp, order);
  86         if (!page)
  87                 return NULL;
  88
  89         /*
  90          * Now split the huge page and free the excess pages
  91          */
  92         split_page(page, order);
  93         for (p = page + (size >> PAGE_SHIFT), e = page + (1 << order); p < e; p++)
  94                 __free_page(p);
  95
  96         /*
  97          * Ensure that the allocated pages are zeroed, and that any data
  98          * lurking in the kernel direct-mapped region is invalidated.
  99          */
 100         ptr = page_address(page);
 101         memset(ptr, 0, size);
 102         dmac_flush_range(ptr, ptr + size);
 103         outer_flush_range(__pa(ptr), __pa(ptr) + size);
 104
 105         return page;
 106 }
 107
 108 /*
 109  * Free a DMA buffer.  'size' must be page aligned.
 110  */
 111 static void __dma_free_buffer(struct page *page, size_t size)
 112 {
 113         struct page *e = page + (size >> PAGE_SHIFT);
 114
 115         while (page < e) {
 116                 __free_page(page);
 117                 page++;
 118         }
 119 }
 120
 121 #ifdef CONFIG_MMU
 122
 123 #define CONSISTENT_OFFSET(x)    (((unsigned long)(x) - consistent_base) >> PAGE_SHIFT)
 124 #define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - consistent_base) >> PMD_SHIFT)
 125
 126 /*
 127  * These are the page tables (2MB each) covering uncached, DMA consistent allocations
 128  */
 129 static pte_t **consistent_pte;
 130
 131 #define DEFAULT_CONSISTENT_DMA_SIZE SZ_2M
 132
 133 unsigned long consistent_base = CONSISTENT_END - DEFAULT_CONSISTENT_DMA_SIZE;
 134
 135 void __init init_consistent_dma_size(unsigned long size)
 136 {
 137         unsigned long base = CONSISTENT_END - ALIGN(size, SZ_2M);
 138
 139         BUG_ON(consistent_pte); /* Check we're called before DMA region init */
 140         BUG_ON(base < VMALLOC_END);
 141
 142         /* Grow region to accommodate specified size  */
 143         if (base < consistent_base)
 144                 consistent_base = base;
 145 }
 146
 147 #include "vmregion.h"
 148
 149 static struct arm_vmregion_head consistent_head = {
 150         .vm_lock        = __SPIN_LOCK_UNLOCKED(&consistent_head.vm_lock),
 151         .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
 152         .vm_end         = CONSISTENT_END,
 153 };
 154
 155 #ifdef CONFIG_HUGETLB_PAGE
 156 #error ARM Coherent DMA allocator does not (yet) support huge TLB
 157 #endif
 158
 159 /*
 160  * Initialise the consistent memory allocation.
 161  */
 162 static int __init consistent_init(void)
 163 {
 164         int ret = 0;
 165         pgd_t *pgd;
 166         pud_t *pud;
 167         pmd_t *pmd;
 168         pte_t *pte;
 169         int i = 0;
 170         unsigned long base = consistent_base;
 171         unsigned long num_ptes = (CONSISTENT_END - base) >> PGDIR_SHIFT;
 172
 173         consistent_pte = kmalloc(num_ptes * sizeof(pte_t), GFP_KERNEL);
 174         if (!consistent_pte) {
 175                 pr_err("%s: no memory\n", __func__);
 176                 return -ENOMEM;
 177         }
 178
 179         pr_debug("DMA memory: 0x%08lx - 0x%08lx:\n", base, CONSISTENT_END);
 180         consistent_head.vm_start = base;
 181
 182         do {
 183                 pgd = pgd_offset(&init_mm, base);
 184
 185                 pud = pud_alloc(&init_mm, pgd, base);
 186                 if (!pud) {
 187                         printk(KERN_ERR "%s: no pud tables\n", __func__);
 188                         ret = -ENOMEM;
 189                         break;
 190                 }
 191
 192                 pmd = pmd_alloc(&init_mm, pud, base);
 193                 if (!pmd) {
 194                         printk(KERN_ERR "%s: no pmd tables\n", __func__);
 195                         ret = -ENOMEM;
 196                         break;
 197                 }
 198                 WARN_ON(!pmd_none(*pmd));
 199
 200                 pte = pte_alloc_kernel(pmd, base);
 201                 if (!pte) {
 202                         printk(KERN_ERR "%s: no pte tables\n", __func__);
 203                         ret = -ENOMEM;
 204                         break;
 205                 }
 206
 207                 consistent_pte[i++] = pte;
 208                 base += PMD_SIZE;
 209         } while (base < CONSISTENT_END);
 210
 211         return ret;
 212 }
 213
 214 core_initcall(consistent_init);
 215
 216 static void *
 217 __dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
 218 {
 219         struct arm_vmregion *c;
 220         size_t align;
 221         int bit;
 222
 223         if (!consistent_pte) {
 224                 printk(KERN_ERR "%s: not initialised\n", __func__);
 225                 dump_stack();
 226                 return NULL;
 227         }
 228
 229         /*
 230          * Align the virtual region allocation - maximum alignment is
 231          * a section size, minimum is a page size.  This helps reduce
 232          * fragmentation of the DMA space, and also prevents allocations
 233          * smaller than a section from crossing a section boundary.
 234          */
 235         bit = fls(size - 1);
 236         if (bit > SECTION_SHIFT)
 237                 bit = SECTION_SHIFT;
 238         align = 1 << bit;
 239
 240         /*
 241          * Allocate a virtual address in the consistent mapping region.
 242          */
 243         c = arm_vmregion_alloc(&consistent_head, align, size,
 244                             gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
 245         if (c) {
 246                 pte_t *pte;
 247                 int idx = CONSISTENT_PTE_INDEX(c->vm_start);
 248                 u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 249
 250                 pte = consistent_pte[idx] + off;
 251                 c->vm_pages = page;
 252
 253                 do {
 254                         BUG_ON(!pte_none(*pte));
 255
 256                         set_pte_ext(pte, mk_pte(page, prot), 0);
 257                         page++;
 258                         pte++;
 259                         off++;
 260                         if (off >= PTRS_PER_PTE) {
 261                                 off = 0;
 262                                 pte = consistent_pte[++idx];
 263                         }
 264                 } while (size -= PAGE_SIZE);
 265
 266                 dsb();
 267
 268                 return (void *)c->vm_start;
 269         }
 270         return NULL;
 271 }
 272
 273 static void __dma_free_remap(void *cpu_addr, size_t size)
 274 {
 275         struct arm_vmregion *c;
 276         unsigned long addr;
 277         pte_t *ptep;
 278         int idx;
 279         u32 off;
 280
 281         c = arm_vmregion_find_remove(&consistent_head, (unsigned long)cpu_addr);
 282         if (!c) {
 283                 printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
 284                        __func__, cpu_addr);
 285                 dump_stack();
 286                 return;
 287         }
 288
 289         if ((c->vm_end - c->vm_start) != size) {
 290                 printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
 291                        __func__, c->vm_end - c->vm_start, size);
 292                 dump_stack();
 293                 size = c->vm_end - c->vm_start;
 294         }
 295
 296         idx = CONSISTENT_PTE_INDEX(c->vm_start);
 297         off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 298         ptep = consistent_pte[idx] + off;
 299         addr = c->vm_start;
 300         do {
 301                 pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
 302
 303                 ptep++;
 304                 addr += PAGE_SIZE;
 305                 off++;
 306                 if (off >= PTRS_PER_PTE) {
 307                         off = 0;
 308                         ptep = consistent_pte[++idx];
 309                 }
 310
 311                 if (pte_none(pte) || !pte_present(pte))
 312                         printk(KERN_CRIT "%s: bad page in kernel page table\n",
 313                                __func__);
 314         } while (size -= PAGE_SIZE);
 315
 316         flush_tlb_kernel_range(c->vm_start, c->vm_end);
 317
 318         arm_vmregion_free(&consistent_head, c);
 319 }
 320
 321 #else   /* !CONFIG_MMU */
 322
 323 #define __dma_alloc_remap(page, size, gfp, prot)        page_address(page)
 324 #define __dma_free_remap(addr, size)                    do { } while (0)
 325
 326 #endif  /* CONFIG_MMU */
 327
 328 static void *
 329 __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
 330             pgprot_t prot)
 331 {
 332         struct page *page;
 333         void *addr;
 334
 335         *handle = ~0;
 336         size = PAGE_ALIGN(size);
 337
 338         page = __dma_alloc_buffer(dev, size, gfp);
 339         if (!page)
 340                 return NULL;
 341
 342         if (!arch_is_coherent())
 343                 addr = __dma_alloc_remap(page, size, gfp, prot);
 344         else
 345                 addr = page_address(page);
 346
 347         if (addr)
 348                 *handle = pfn_to_dma(dev, page_to_pfn(page));
 349
 350         return addr;
 351 }
 352
 353 /*
 354  * Allocate DMA-coherent memory space and return both the kernel remapped
 355  * virtual and bus address for that space.
 356  */
 357 void *
 358 dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 359 {
 360         void *memory;
 361
 362         if (dma_alloc_from_coherent(dev, size, handle, &memory))
 363                 return memory;
 364
 365         return __dma_alloc(dev, size, handle, gfp,
 366                            pgprot_dmacoherent(pgprot_kernel));
 367 }
 368 EXPORT_SYMBOL(dma_alloc_coherent);
 369
 370 /*
 371  * Allocate a writecombining region, in much the same way as
 372  * dma_alloc_coherent above.
 373  */
 374 void *
 375 dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 376 {
 377         return __dma_alloc(dev, size, handle, gfp,
 378                            pgprot_writecombine(pgprot_kernel));
 379 }
 380 EXPORT_SYMBOL(dma_alloc_writecombine);
 381
 382 static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
 383                     void *cpu_addr, dma_addr_t dma_addr, size_t size)
 384 {
 385         int ret = -ENXIO;
 386 #ifdef CONFIG_MMU
 387         unsigned long user_size, kern_size;
 388         struct arm_vmregion *c;
 389
 390         user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 391
 392         c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
 393         if (c) {
 394                 unsigned long off = vma->vm_pgoff;
 395
 396                 kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
 397
 398                 if (off < kern_size &&
 399                     user_size <= (kern_size - off)) {
 400                         ret = remap_pfn_range(vma, vma->vm_start,
 401                                               page_to_pfn(c->vm_pages) + off,
 402                                               user_size << PAGE_SHIFT,
 403                                               vma->vm_page_prot);
 404                 }
 405         }
 406 #endif  /* CONFIG_MMU */
 407
 408         return ret;
 409 }
 410
 411 int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
 412                       void *cpu_addr, dma_addr_t dma_addr, size_t size)
 413 {
 414         vma->vm_page_prot = pgprot_dmacoherent(vma->vm_page_prot);
 415         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 416 }
 417 EXPORT_SYMBOL(dma_mmap_coherent);
 418
 419 int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
 420                           void *cpu_addr, dma_addr_t dma_addr, size_t size)
 421 {
 422         vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 423         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 424 }
 425 EXPORT_SYMBOL(dma_mmap_writecombine);
 426
 427 /*
 428  * free a page as defined by the above mapping.
 429  * Must not be called with IRQs disabled.
 430  */
 431 void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
 432 {
 433         WARN_ON(irqs_disabled());
 434
 435         if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
 436                 return;
 437
 438         size = PAGE_ALIGN(size);
 439
 440         if (!arch_is_coherent())
 441                 __dma_free_remap(cpu_addr, size);
 442
 443         __dma_free_buffer(pfn_to_page(dma_to_pfn(dev, handle)), size);
 444 }
 445 EXPORT_SYMBOL(dma_free_coherent);
 446
 447 /*
 448  * Make an area consistent for devices.
 449  * Note: Drivers should NOT use this function directly, as it will break
 450  * platforms with CONFIG_DMABOUNCE.
 451  * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
 452  */
 453 void ___dma_single_cpu_to_dev(const void *kaddr, size_t size,
 454         enum dma_data_direction dir)
 455 {
 456         unsigned long paddr;
 457
 458         BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));
 459
 460         dmac_map_area(kaddr, size, dir);
 461
 462         paddr = __pa(kaddr);
 463         if (dir == DMA_FROM_DEVICE) {
 464                 outer_inv_range(paddr, paddr + size);
 465         } else {
 466                 outer_clean_range(paddr, paddr + size);
 467         }
 468         /* FIXME: non-speculating: flush on bidirectional mappings? */
 469 }
 470 EXPORT_SYMBOL(___dma_single_cpu_to_dev);
 471
 472 void ___dma_single_dev_to_cpu(const void *kaddr, size_t size,
 473         enum dma_data_direction dir)
 474 {
 475         BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));
 476
 477         /* FIXME: non-speculating: not required */
 478         /* don't bother invalidating if DMA to device */
 479         if (dir != DMA_TO_DEVICE) {
 480                 unsigned long paddr = __pa(kaddr);
 481                 outer_inv_range(paddr, paddr + size);
 482         }
 483
 484         dmac_unmap_area(kaddr, size, dir);
 485 }
 486 EXPORT_SYMBOL(___dma_single_dev_to_cpu);
 487
 488 static void dma_cache_maint_page(struct page *page, unsigned long offset,
 489         size_t size, enum dma_data_direction dir,
 490         void (*op)(const void *, size_t, int))
 491 {
 492         /*
 493          * A single sg entry may refer to multiple physically contiguous
 494          * pages.  But we still need to process highmem pages individually.
 495          * If highmem is not configured then the bulk of this loop gets
 496          * optimized out.
 497          */
 498         size_t left = size;
 499         do {
 500                 size_t len = left;
 501                 void *vaddr;
 502
 503                 if (PageHighMem(page)) {
 504                         if (len + offset > PAGE_SIZE) {
 505                                 if (offset >= PAGE_SIZE) {
 506                                         page += offset / PAGE_SIZE;
 507                                         offset %= PAGE_SIZE;
 508                                 }
 509                                 len = PAGE_SIZE - offset;
 510                         }
 511                         vaddr = kmap_high_get(page);
 512                         if (vaddr) {
 513                                 vaddr += offset;
 514                                 op(vaddr, len, dir);
 515                                 kunmap_high(page);
 516                         } else if (cache_is_vipt()) {
 517                                 /* unmapped pages might still be cached */
 518                                 vaddr = kmap_atomic(page);
 519                                 op(vaddr + offset, len, dir);
 520                                 kunmap_atomic(vaddr);
 521                         }
 522                 } else {
 523                         vaddr = page_address(page) + offset;
 524                         op(vaddr, len, dir);
 525                 }
 526                 offset = 0;
 527                 page++;
 528                 left -= len;
 529         } while (left);
 530 }
 531
 532 void ___dma_page_cpu_to_dev(struct page *page, unsigned long off,
 533         size_t size, enum dma_data_direction dir)
 534 {
 535         unsigned long paddr;
 536
 537         dma_cache_maint_page(page, off, size, dir, dmac_map_area);
 538
 539         paddr = page_to_phys(page) + off;
 540         if (dir == DMA_FROM_DEVICE) {
 541                 outer_inv_range(paddr, paddr + size);
 542         } else {
 543                 outer_clean_range(paddr, paddr + size);
 544         }
 545         /* FIXME: non-speculating: flush on bidirectional mappings? */
 546 }
 547 EXPORT_SYMBOL(___dma_page_cpu_to_dev);
 548
 549 void ___dma_page_dev_to_cpu(struct page *page, unsigned long off,
 550         size_t size, enum dma_data_direction dir)
 551 {
 552         unsigned long paddr = page_to_phys(page) + off;
 553
 554         /* FIXME: non-speculating: not required */
 555         /* don't bother invalidating if DMA to device */
 556         if (dir != DMA_TO_DEVICE)
 557                 outer_inv_range(paddr, paddr + size);
 558
 559         dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);
 560
 561         /*
 562          * Mark the D-cache clean for this page to avoid extra flushing.
 563          */
 564         if (dir != DMA_TO_DEVICE && off == 0 && size >= PAGE_SIZE)
 565                 set_bit(PG_dcache_clean, &page->flags);
 566 }
 567 EXPORT_SYMBOL(___dma_page_dev_to_cpu);
 568
 569 /**
 570  * dma_map_sg - map a set of SG buffers for streaming mode DMA
 571  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 572  * @sg: list of buffers
 573  * @nents: number of buffers to map
 574  * @dir: DMA transfer direction
 575  *
 576  * Map a set of buffers described by scatterlist in streaming mode for DMA.
 577  * This is the scatter-gather version of the dma_map_single interface.
 578  * Here the scatter gather list elements are each tagged with the
 579  * appropriate dma address and length.  They are obtained via
 580  * sg_dma_{address,length}.
 581  *
 582  * Device ownership issues as mentioned for dma_map_single are the same
 583  * here.
 584  */
 585 int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 586                 enum dma_data_direction dir)
 587 {
 588         struct scatterlist *s;
 589         int i, j;
 590
 591         BUG_ON(!valid_dma_direction(dir));
 592
 593         for_each_sg(sg, s, nents, i) {
 594                 s->dma_address = __dma_map_page(dev, sg_page(s), s->offset,
 595                                                 s->length, dir);
 596                 if (dma_mapping_error(dev, s->dma_address))
 597                         goto bad_mapping;
 598         }
 599         debug_dma_map_sg(dev, sg, nents, nents, dir);
 600         return nents;
 601
 602  bad_mapping:
 603         for_each_sg(sg, s, i, j)
 604                 __dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
 605         return 0;
 606 }
 607 EXPORT_SYMBOL(dma_map_sg);
 608
 609 /**
 610  * dma_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
 611  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 612  * @sg: list of buffers
 613  * @nents: number of buffers to unmap (same as was passed to dma_map_sg)
 614  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 615  *
 616  * Unmap a set of streaming mode DMA translations.  Again, CPU access
 617  * rules concerning calls here are the same as for dma_unmap_single().
 618  */
 619 void dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 620                 enum dma_data_direction dir)
 621 {
 622         struct scatterlist *s;
 623         int i;
 624
 625         debug_dma_unmap_sg(dev, sg, nents, dir);
 626
 627         for_each_sg(sg, s, nents, i)
 628                 __dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
 629 }
 630 EXPORT_SYMBOL(dma_unmap_sg);
 631
 632 /**
 633  * dma_sync_sg_for_cpu
 634  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 635  * @sg: list of buffers
 636  * @nents: number of buffers to map (returned from dma_map_sg)
 637  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 638  */
 639 void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
 640                         int nents, enum dma_data_direction dir)
 641 {
 642         struct scatterlist *s;
 643         int i;
 644
 645         for_each_sg(sg, s, nents, i) {
 646                 if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
 647                                             sg_dma_len(s), dir))
 648                         continue;
 649
 650                 __dma_page_dev_to_cpu(sg_page(s), s->offset,
 651                                       s->length, dir);
 652         }
 653
 654         debug_dma_sync_sg_for_cpu(dev, sg, nents, dir);
 655 }
 656 EXPORT_SYMBOL(dma_sync_sg_for_cpu);
 657
 658 /**
 659  * dma_sync_sg_for_device
 660  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
 661  * @sg: list of buffers
 662  * @nents: number of buffers to map (returned from dma_map_sg)
 663  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
 664  */
 665 void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 666                         int nents, enum dma_data_direction dir)
 667 {
 668         struct scatterlist *s;
 669         int i;
 670
 671         for_each_sg(sg, s, nents, i) {
 672                 if (!dmabounce_sync_for_device(dev, sg_dma_address(s), 0,
 673                                         sg_dma_len(s), dir))
 674                         continue;
 675
 676                 __dma_page_cpu_to_dev(sg_page(s), s->offset,
 677                                       s->length, dir);
 678         }
 679
 680         debug_dma_sync_sg_for_device(dev, sg, nents, dir);
 681 }
 682 EXPORT_SYMBOL(dma_sync_sg_for_device);
 683
 684 /*
 685  * Return whether the given device DMA address mask can be supported
 686  * properly.  For example, if your device can only drive the low 24-bits
 687  * during bus mastering, then you would pass 0x00ffffff as the mask
 688  * to this function.
 689  */
 690 int dma_supported(struct device *dev, u64 mask)
 691 {
 692         if (mask < (u64)arm_dma_limit)
 693                 return 0;
 694         return 1;
 695 }
 696 EXPORT_SYMBOL(dma_supported);
 697
 698 int dma_set_mask(struct device *dev, u64 dma_mask)
 699 {
 700         if (!dev->dma_mask || !dma_supported(dev, dma_mask))
 701                 return -EIO;
 702
 703 #ifndef CONFIG_DMABOUNCE
 704         *dev->dma_mask = dma_mask;
 705 #endif
 706
 707         return 0;
 708 }
 709 EXPORT_SYMBOL(dma_set_mask);
 710
 711 #define PREALLOC_DMA_DEBUG_ENTRIES      4096
 712
 713 static int __init dma_debug_do_init(void)
 714 {
 715         dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
 716         return 0;
 717 }
 718 fs_initcall(dma_debug_do_init);