linux/lib/swiotlb.c
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   1/*
   2 * Dynamic DMA mapping support.
   3 *
   4 * This implementation is a fallback for platforms that do not support
   5 * I/O TLBs (aka DMA address translation hardware).
   6 * Copyright (C) 2000 Asit Mallick <Asit.K.Mallick@intel.com>
   7 * Copyright (C) 2000 Goutham Rao <goutham.rao@intel.com>
   8 * Copyright (C) 2000, 2003 Hewlett-Packard Co
   9 *      David Mosberger-Tang <davidm@hpl.hp.com>
  10 *
  11 * 03/05/07 davidm      Switch from PCI-DMA to generic device DMA API.
  12 * 00/12/13 davidm      Rename to swiotlb.c and add mark_clean() to avoid
  13 *                      unnecessary i-cache flushing.
  14 * 04/07/.. ak          Better overflow handling. Assorted fixes.
  15 * 05/09/10 linville    Add support for syncing ranges, support syncing for
  16 *                      DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
  17 * 08/12/11 beckyb      Add highmem support
  18 */
  19
  20#include <linux/cache.h>
  21#include <linux/dma-mapping.h>
  22#include <linux/mm.h>
  23#include <linux/export.h>
  24#include <linux/spinlock.h>
  25#include <linux/string.h>
  26#include <linux/swiotlb.h>
  27#include <linux/pfn.h>
  28#include <linux/types.h>
  29#include <linux/ctype.h>
  30#include <linux/highmem.h>
  31#include <linux/gfp.h>
  32
  33#include <asm/io.h>
  34#include <asm/dma.h>
  35#include <asm/scatterlist.h>
  36
  37#include <linux/init.h>
  38#include <linux/bootmem.h>
  39#include <linux/iommu-helper.h>
  40
  41#define OFFSET(val,align) ((unsigned long)      \
  42                           ( (val) & ( (align) - 1)))
  43
  44#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
  45
  46/*
  47 * Minimum IO TLB size to bother booting with.  Systems with mainly
  48 * 64bit capable cards will only lightly use the swiotlb.  If we can't
  49 * allocate a contiguous 1MB, we're probably in trouble anyway.
  50 */
  51#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
  52
  53int swiotlb_force;
  54
  55/*
  56 * Used to do a quick range check in swiotlb_tbl_unmap_single and
  57 * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
  58 * API.
  59 */
  60static phys_addr_t io_tlb_start, io_tlb_end;
  61
  62/*
  63 * The number of IO TLB blocks (in groups of 64) between io_tlb_start and
  64 * io_tlb_end.  This is command line adjustable via setup_io_tlb_npages.
  65 */
  66static unsigned long io_tlb_nslabs;
  67
  68/*
  69 * When the IOMMU overflows we return a fallback buffer. This sets the size.
  70 */
  71static unsigned long io_tlb_overflow = 32*1024;
  72
  73static phys_addr_t io_tlb_overflow_buffer;
  74
  75/*
  76 * This is a free list describing the number of free entries available from
  77 * each index
  78 */
  79static unsigned int *io_tlb_list;
  80static unsigned int io_tlb_index;
  81
  82/*
  83 * We need to save away the original address corresponding to a mapped entry
  84 * for the sync operations.
  85 */
  86static phys_addr_t *io_tlb_orig_addr;
  87
  88/*
  89 * Protect the above data structures in the map and unmap calls
  90 */
  91static DEFINE_SPINLOCK(io_tlb_lock);
  92
  93static int late_alloc;
  94
  95static int __init
  96setup_io_tlb_npages(char *str)
  97{
  98        if (isdigit(*str)) {
  99                io_tlb_nslabs = simple_strtoul(str, &str, 0);
 100                /* avoid tail segment of size < IO_TLB_SEGSIZE */
 101                io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 102        }
 103        if (*str == ',')
 104                ++str;
 105        if (!strcmp(str, "force"))
 106                swiotlb_force = 1;
 107
 108        return 1;
 109}
 110__setup("swiotlb=", setup_io_tlb_npages);
 111/* make io_tlb_overflow tunable too? */
 112
 113unsigned long swiotlb_nr_tbl(void)
 114{
 115        return io_tlb_nslabs;
 116}
 117EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
 118/* Note that this doesn't work with highmem page */
 119static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
 120                                      volatile void *address)
 121{
 122        return phys_to_dma(hwdev, virt_to_phys(address));
 123}
 124
 125void swiotlb_print_info(void)
 126{
 127        unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 128        unsigned char *vstart, *vend;
 129
 130        vstart = phys_to_virt(io_tlb_start);
 131        vend = phys_to_virt(io_tlb_end);
 132
 133        printk(KERN_INFO "software IO TLB [mem %#010llx-%#010llx] (%luMB) mapped at [%p-%p]\n",
 134               (unsigned long long)io_tlb_start,
 135               (unsigned long long)io_tlb_end,
 136               bytes >> 20, vstart, vend - 1);
 137}
 138
 139void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 140{
 141        void *v_overflow_buffer;
 142        unsigned long i, bytes;
 143
 144        bytes = nslabs << IO_TLB_SHIFT;
 145
 146        io_tlb_nslabs = nslabs;
 147        io_tlb_start = __pa(tlb);
 148        io_tlb_end = io_tlb_start + bytes;
 149
 150        /*
 151         * Get the overflow emergency buffer
 152         */
 153        v_overflow_buffer = alloc_bootmem_low_pages(PAGE_ALIGN(io_tlb_overflow));
 154        if (!v_overflow_buffer)
 155                panic("Cannot allocate SWIOTLB overflow buffer!\n");
 156
 157        io_tlb_overflow_buffer = __pa(v_overflow_buffer);
 158
 159        /*
 160         * Allocate and initialize the free list array.  This array is used
 161         * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
 162         * between io_tlb_start and io_tlb_end.
 163         */
 164        io_tlb_list = alloc_bootmem_pages(PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
 165        for (i = 0; i < io_tlb_nslabs; i++)
 166                io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
 167        io_tlb_index = 0;
 168        io_tlb_orig_addr = alloc_bootmem_pages(PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
 169
 170        if (verbose)
 171                swiotlb_print_info();
 172}
 173
 174/*
 175 * Statically reserve bounce buffer space and initialize bounce buffer data
 176 * structures for the software IO TLB used to implement the DMA API.
 177 */
 178static void __init
 179swiotlb_init_with_default_size(size_t default_size, int verbose)
 180{
 181        unsigned char *vstart;
 182        unsigned long bytes;
 183
 184        if (!io_tlb_nslabs) {
 185                io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
 186                io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 187        }
 188
 189        bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 190
 191        /*
 192         * Get IO TLB memory from the low pages
 193         */
 194        vstart = alloc_bootmem_low_pages(PAGE_ALIGN(bytes));
 195        if (!vstart)
 196                panic("Cannot allocate SWIOTLB buffer");
 197
 198        swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose);
 199}
 200
 201void __init
 202swiotlb_init(int verbose)
 203{
 204        swiotlb_init_with_default_size(64 * (1<<20), verbose);  /* default to 64MB */
 205}
 206
 207/*
 208 * Systems with larger DMA zones (those that don't support ISA) can
 209 * initialize the swiotlb later using the slab allocator if needed.
 210 * This should be just like above, but with some error catching.
 211 */
 212int
 213swiotlb_late_init_with_default_size(size_t default_size)
 214{
 215        unsigned long bytes, req_nslabs = io_tlb_nslabs;
 216        unsigned char *vstart = NULL;
 217        unsigned int order;
 218        int rc = 0;
 219
 220        if (!io_tlb_nslabs) {
 221                io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
 222                io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 223        }
 224
 225        /*
 226         * Get IO TLB memory from the low pages
 227         */
 228        order = get_order(io_tlb_nslabs << IO_TLB_SHIFT);
 229        io_tlb_nslabs = SLABS_PER_PAGE << order;
 230        bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 231
 232        while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
 233                vstart = (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
 234                                                  order);
 235                if (vstart)
 236                        break;
 237                order--;
 238        }
 239
 240        if (!vstart) {
 241                io_tlb_nslabs = req_nslabs;
 242                return -ENOMEM;
 243        }
 244        if (order != get_order(bytes)) {
 245                printk(KERN_WARNING "Warning: only able to allocate %ld MB "
 246                       "for software IO TLB\n", (PAGE_SIZE << order) >> 20);
 247                io_tlb_nslabs = SLABS_PER_PAGE << order;
 248        }
 249        rc = swiotlb_late_init_with_tbl(vstart, io_tlb_nslabs);
 250        if (rc)
 251                free_pages((unsigned long)vstart, order);
 252        return rc;
 253}
 254
 255int
 256swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 257{
 258        unsigned long i, bytes;
 259        unsigned char *v_overflow_buffer;
 260
 261        bytes = nslabs << IO_TLB_SHIFT;
 262
 263        io_tlb_nslabs = nslabs;
 264        io_tlb_start = virt_to_phys(tlb);
 265        io_tlb_end = io_tlb_start + bytes;
 266
 267        memset(tlb, 0, bytes);
 268
 269        /*
 270         * Get the overflow emergency buffer
 271         */
 272        v_overflow_buffer = (void *)__get_free_pages(GFP_DMA,
 273                                                     get_order(io_tlb_overflow));
 274        if (!v_overflow_buffer)
 275                goto cleanup2;
 276
 277        io_tlb_overflow_buffer = virt_to_phys(v_overflow_buffer);
 278
 279        /*
 280         * Allocate and initialize the free list array.  This array is used
 281         * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
 282         * between io_tlb_start and io_tlb_end.
 283         */
 284        io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
 285                                      get_order(io_tlb_nslabs * sizeof(int)));
 286        if (!io_tlb_list)
 287                goto cleanup3;
 288
 289        for (i = 0; i < io_tlb_nslabs; i++)
 290                io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
 291        io_tlb_index = 0;
 292
 293        io_tlb_orig_addr = (phys_addr_t *)
 294                __get_free_pages(GFP_KERNEL,
 295                                 get_order(io_tlb_nslabs *
 296                                           sizeof(phys_addr_t)));
 297        if (!io_tlb_orig_addr)
 298                goto cleanup4;
 299
 300        memset(io_tlb_orig_addr, 0, io_tlb_nslabs * sizeof(phys_addr_t));
 301
 302        swiotlb_print_info();
 303
 304        late_alloc = 1;
 305
 306        return 0;
 307
 308cleanup4:
 309        free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
 310                                                         sizeof(int)));
 311        io_tlb_list = NULL;
 312cleanup3:
 313        free_pages((unsigned long)v_overflow_buffer,
 314                   get_order(io_tlb_overflow));
 315        io_tlb_overflow_buffer = 0;
 316cleanup2:
 317        io_tlb_end = 0;
 318        io_tlb_start = 0;
 319        io_tlb_nslabs = 0;
 320        return -ENOMEM;
 321}
 322
 323void __init swiotlb_free(void)
 324{
 325        if (!io_tlb_orig_addr)
 326                return;
 327
 328        if (late_alloc) {
 329                free_pages((unsigned long)phys_to_virt(io_tlb_overflow_buffer),
 330                           get_order(io_tlb_overflow));
 331                free_pages((unsigned long)io_tlb_orig_addr,
 332                           get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
 333                free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
 334                                                                 sizeof(int)));
 335                free_pages((unsigned long)phys_to_virt(io_tlb_start),
 336                           get_order(io_tlb_nslabs << IO_TLB_SHIFT));
 337        } else {
 338                free_bootmem_late(io_tlb_overflow_buffer,
 339                                  PAGE_ALIGN(io_tlb_overflow));
 340                free_bootmem_late(__pa(io_tlb_orig_addr),
 341                                  PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
 342                free_bootmem_late(__pa(io_tlb_list),
 343                                  PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
 344                free_bootmem_late(io_tlb_start,
 345                                  PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
 346        }
 347        io_tlb_nslabs = 0;
 348}
 349
 350static int is_swiotlb_buffer(phys_addr_t paddr)
 351{
 352        return paddr >= io_tlb_start && paddr < io_tlb_end;
 353}
 354
 355/*
 356 * Bounce: copy the swiotlb buffer back to the original dma location
 357 */
 358static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
 359                           size_t size, enum dma_data_direction dir)
 360{
 361        unsigned long pfn = PFN_DOWN(orig_addr);
 362        unsigned char *vaddr = phys_to_virt(tlb_addr);
 363
 364        if (PageHighMem(pfn_to_page(pfn))) {
 365                /* The buffer does not have a mapping.  Map it in and copy */
 366                unsigned int offset = orig_addr & ~PAGE_MASK;
 367                char *buffer;
 368                unsigned int sz = 0;
 369                unsigned long flags;
 370
 371                while (size) {
 372                        sz = min_t(size_t, PAGE_SIZE - offset, size);
 373
 374                        local_irq_save(flags);
 375                        buffer = kmap_atomic(pfn_to_page(pfn));
 376                        if (dir == DMA_TO_DEVICE)
 377                                memcpy(vaddr, buffer + offset, sz);
 378                        else
 379                                memcpy(buffer + offset, vaddr, sz);
 380                        kunmap_atomic(buffer);
 381                        local_irq_restore(flags);
 382
 383                        size -= sz;
 384                        pfn++;
 385                        vaddr += sz;
 386                        offset = 0;
 387                }
 388        } else if (dir == DMA_TO_DEVICE) {
 389                memcpy(vaddr, phys_to_virt(orig_addr), size);
 390        } else {
 391                memcpy(phys_to_virt(orig_addr), vaddr, size);
 392        }
 393}
 394
 395phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
 396                                   dma_addr_t tbl_dma_addr,
 397                                   phys_addr_t orig_addr, size_t size,
 398                                   enum dma_data_direction dir)
 399{
 400        unsigned long flags;
 401        phys_addr_t tlb_addr;
 402        unsigned int nslots, stride, index, wrap;
 403        int i;
 404        unsigned long mask;
 405        unsigned long offset_slots;
 406        unsigned long max_slots;
 407
 408        mask = dma_get_seg_boundary(hwdev);
 409
 410        tbl_dma_addr &= mask;
 411
 412        offset_slots = ALIGN(tbl_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 413
 414        /*
 415         * Carefully handle integer overflow which can occur when mask == ~0UL.
 416         */
 417        max_slots = mask + 1
 418                    ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT
 419                    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
 420
 421        /*
 422         * For mappings greater than a page, we limit the stride (and
 423         * hence alignment) to a page size.
 424         */
 425        nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 426        if (size > PAGE_SIZE)
 427                stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
 428        else
 429                stride = 1;
 430
 431        BUG_ON(!nslots);
 432
 433        /*
 434         * Find suitable number of IO TLB entries size that will fit this
 435         * request and allocate a buffer from that IO TLB pool.
 436         */
 437        spin_lock_irqsave(&io_tlb_lock, flags);
 438        index = ALIGN(io_tlb_index, stride);
 439        if (index >= io_tlb_nslabs)
 440                index = 0;
 441        wrap = index;
 442
 443        do {
 444                while (iommu_is_span_boundary(index, nslots, offset_slots,
 445                                              max_slots)) {
 446                        index += stride;
 447                        if (index >= io_tlb_nslabs)
 448                                index = 0;
 449                        if (index == wrap)
 450                                goto not_found;
 451                }
 452
 453                /*
 454                 * If we find a slot that indicates we have 'nslots' number of
 455                 * contiguous buffers, we allocate the buffers from that slot
 456                 * and mark the entries as '0' indicating unavailable.
 457                 */
 458                if (io_tlb_list[index] >= nslots) {
 459                        int count = 0;
 460
 461                        for (i = index; i < (int) (index + nslots); i++)
 462                                io_tlb_list[i] = 0;
 463                        for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
 464                                io_tlb_list[i] = ++count;
 465                        tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
 466
 467                        /*
 468                         * Update the indices to avoid searching in the next
 469                         * round.
 470                         */
 471                        io_tlb_index = ((index + nslots) < io_tlb_nslabs
 472                                        ? (index + nslots) : 0);
 473
 474                        goto found;
 475                }
 476                index += stride;
 477                if (index >= io_tlb_nslabs)
 478                        index = 0;
 479        } while (index != wrap);
 480
 481not_found:
 482        spin_unlock_irqrestore(&io_tlb_lock, flags);
 483        return SWIOTLB_MAP_ERROR;
 484found:
 485        spin_unlock_irqrestore(&io_tlb_lock, flags);
 486
 487        /*
 488         * Save away the mapping from the original address to the DMA address.
 489         * This is needed when we sync the memory.  Then we sync the buffer if
 490         * needed.
 491         */
 492        for (i = 0; i < nslots; i++)
 493                io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
 494        if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
 495                swiotlb_bounce(orig_addr, tlb_addr, size, DMA_TO_DEVICE);
 496
 497        return tlb_addr;
 498}
 499EXPORT_SYMBOL_GPL(swiotlb_tbl_map_single);
 500
 501/*
 502 * Allocates bounce buffer and returns its kernel virtual address.
 503 */
 504
 505phys_addr_t map_single(struct device *hwdev, phys_addr_t phys, size_t size,
 506                       enum dma_data_direction dir)
 507{
 508        dma_addr_t start_dma_addr = phys_to_dma(hwdev, io_tlb_start);
 509
 510        return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size, dir);
 511}
 512
 513/*
 514 * dma_addr is the kernel virtual address of the bounce buffer to unmap.
 515 */
 516void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 517                              size_t size, enum dma_data_direction dir)
 518{
 519        unsigned long flags;
 520        int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 521        int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
 522        phys_addr_t orig_addr = io_tlb_orig_addr[index];
 523
 524        /*
 525         * First, sync the memory before unmapping the entry
 526         */
 527        if (orig_addr && ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
 528                swiotlb_bounce(orig_addr, tlb_addr, size, DMA_FROM_DEVICE);
 529
 530        /*
 531         * Return the buffer to the free list by setting the corresponding
 532         * entries to indicate the number of contiguous entries available.
 533         * While returning the entries to the free list, we merge the entries
 534         * with slots below and above the pool being returned.
 535         */
 536        spin_lock_irqsave(&io_tlb_lock, flags);
 537        {
 538                count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
 539                         io_tlb_list[index + nslots] : 0);
 540                /*
 541                 * Step 1: return the slots to the free list, merging the
 542                 * slots with superceeding slots
 543                 */
 544                for (i = index + nslots - 1; i >= index; i--)
 545                        io_tlb_list[i] = ++count;
 546                /*
 547                 * Step 2: merge the returned slots with the preceding slots,
 548                 * if available (non zero)
 549                 */
 550                for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
 551                        io_tlb_list[i] = ++count;
 552        }
 553        spin_unlock_irqrestore(&io_tlb_lock, flags);
 554}
 555EXPORT_SYMBOL_GPL(swiotlb_tbl_unmap_single);
 556
 557void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
 558                             size_t size, enum dma_data_direction dir,
 559                             enum dma_sync_target target)
 560{
 561        int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
 562        phys_addr_t orig_addr = io_tlb_orig_addr[index];
 563
 564        orig_addr += (unsigned long)tlb_addr & ((1 << IO_TLB_SHIFT) - 1);
 565
 566        switch (target) {
 567        case SYNC_FOR_CPU:
 568                if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
 569                        swiotlb_bounce(orig_addr, tlb_addr,
 570                                       size, DMA_FROM_DEVICE);
 571                else
 572                        BUG_ON(dir != DMA_TO_DEVICE);
 573                break;
 574        case SYNC_FOR_DEVICE:
 575                if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
 576                        swiotlb_bounce(orig_addr, tlb_addr,
 577                                       size, DMA_TO_DEVICE);
 578                else
 579                        BUG_ON(dir != DMA_FROM_DEVICE);
 580                break;
 581        default:
 582                BUG();
 583        }
 584}
 585EXPORT_SYMBOL_GPL(swiotlb_tbl_sync_single);
 586
 587void *
 588swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 589                       dma_addr_t *dma_handle, gfp_t flags)
 590{
 591        dma_addr_t dev_addr;
 592        void *ret;
 593        int order = get_order(size);
 594        u64 dma_mask = DMA_BIT_MASK(32);
 595
 596        if (hwdev && hwdev->coherent_dma_mask)
 597                dma_mask = hwdev->coherent_dma_mask;
 598
 599        ret = (void *)__get_free_pages(flags, order);
 600        if (ret) {
 601                dev_addr = swiotlb_virt_to_bus(hwdev, ret);
 602                if (dev_addr + size - 1 > dma_mask) {
 603                        /*
 604                         * The allocated memory isn't reachable by the device.
 605                         */
 606                        free_pages((unsigned long) ret, order);
 607                        ret = NULL;
 608                }
 609        }
 610        if (!ret) {
 611                /*
 612                 * We are either out of memory or the device can't DMA to
 613                 * GFP_DMA memory; fall back on map_single(), which
 614                 * will grab memory from the lowest available address range.
 615                 */
 616                phys_addr_t paddr = map_single(hwdev, 0, size, DMA_FROM_DEVICE);
 617                if (paddr == SWIOTLB_MAP_ERROR)
 618                        return NULL;
 619
 620                ret = phys_to_virt(paddr);
 621                dev_addr = phys_to_dma(hwdev, paddr);
 622
 623                /* Confirm address can be DMA'd by device */
 624                if (dev_addr + size - 1 > dma_mask) {
 625                        printk("hwdev DMA mask = 0x%016Lx, dev_addr = 0x%016Lx\n",
 626                               (unsigned long long)dma_mask,
 627                               (unsigned long long)dev_addr);
 628
 629                        /* DMA_TO_DEVICE to avoid memcpy in unmap_single */
 630                        swiotlb_tbl_unmap_single(hwdev, paddr,
 631                                                 size, DMA_TO_DEVICE);
 632                        return NULL;
 633                }
 634        }
 635
 636        *dma_handle = dev_addr;
 637        memset(ret, 0, size);
 638
 639        return ret;
 640}
 641EXPORT_SYMBOL(swiotlb_alloc_coherent);
 642
 643void
 644swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
 645                      dma_addr_t dev_addr)
 646{
 647        phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
 648
 649        WARN_ON(irqs_disabled());
 650        if (!is_swiotlb_buffer(paddr))
 651                free_pages((unsigned long)vaddr, get_order(size));
 652        else
 653                /* DMA_TO_DEVICE to avoid memcpy in swiotlb_tbl_unmap_single */
 654                swiotlb_tbl_unmap_single(hwdev, paddr, size, DMA_TO_DEVICE);
 655}
 656EXPORT_SYMBOL(swiotlb_free_coherent);
 657
 658static void
 659swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir,
 660             int do_panic)
 661{
 662        /*
 663         * Ran out of IOMMU space for this operation. This is very bad.
 664         * Unfortunately the drivers cannot handle this operation properly.
 665         * unless they check for dma_mapping_error (most don't)
 666         * When the mapping is small enough return a static buffer to limit
 667         * the damage, or panic when the transfer is too big.
 668         */
 669        printk(KERN_ERR "DMA: Out of SW-IOMMU space for %zu bytes at "
 670               "device %s\n", size, dev ? dev_name(dev) : "?");
 671
 672        if (size <= io_tlb_overflow || !do_panic)
 673                return;
 674
 675        if (dir == DMA_BIDIRECTIONAL)
 676                panic("DMA: Random memory could be DMA accessed\n");
 677        if (dir == DMA_FROM_DEVICE)
 678                panic("DMA: Random memory could be DMA written\n");
 679        if (dir == DMA_TO_DEVICE)
 680                panic("DMA: Random memory could be DMA read\n");
 681}
 682
 683/*
 684 * Map a single buffer of the indicated size for DMA in streaming mode.  The
 685 * physical address to use is returned.
 686 *
 687 * Once the device is given the dma address, the device owns this memory until
 688 * either swiotlb_unmap_page or swiotlb_dma_sync_single is performed.
 689 */
 690dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 691                            unsigned long offset, size_t size,
 692                            enum dma_data_direction dir,
 693                            struct dma_attrs *attrs)
 694{
 695        phys_addr_t map, phys = page_to_phys(page) + offset;
 696        dma_addr_t dev_addr = phys_to_dma(dev, phys);
 697
 698        BUG_ON(dir == DMA_NONE);
 699        /*
 700         * If the address happens to be in the device's DMA window,
 701         * we can safely return the device addr and not worry about bounce
 702         * buffering it.
 703         */
 704        if (dma_capable(dev, dev_addr, size) && !swiotlb_force)
 705                return dev_addr;
 706
 707        /* Oh well, have to allocate and map a bounce buffer. */
 708        map = map_single(dev, phys, size, dir);
 709        if (map == SWIOTLB_MAP_ERROR) {
 710                swiotlb_full(dev, size, dir, 1);
 711                return phys_to_dma(dev, io_tlb_overflow_buffer);
 712        }
 713
 714        dev_addr = phys_to_dma(dev, map);
 715
 716        /* Ensure that the address returned is DMA'ble */
 717        if (!dma_capable(dev, dev_addr, size)) {
 718                swiotlb_tbl_unmap_single(dev, map, size, dir);
 719                return phys_to_dma(dev, io_tlb_overflow_buffer);
 720        }
 721
 722        return dev_addr;
 723}
 724EXPORT_SYMBOL_GPL(swiotlb_map_page);
 725
 726/*
 727 * Unmap a single streaming mode DMA translation.  The dma_addr and size must
 728 * match what was provided for in a previous swiotlb_map_page call.  All
 729 * other usages are undefined.
 730 *
 731 * After this call, reads by the cpu to the buffer are guaranteed to see
 732 * whatever the device wrote there.
 733 */
 734static void unmap_single(struct device *hwdev, dma_addr_t dev_addr,
 735                         size_t size, enum dma_data_direction dir)
 736{
 737        phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
 738
 739        BUG_ON(dir == DMA_NONE);
 740
 741        if (is_swiotlb_buffer(paddr)) {
 742                swiotlb_tbl_unmap_single(hwdev, paddr, size, dir);
 743                return;
 744        }
 745
 746        if (dir != DMA_FROM_DEVICE)
 747                return;
 748
 749        /*
 750         * phys_to_virt doesn't work with hihgmem page but we could
 751         * call dma_mark_clean() with hihgmem page here. However, we
 752         * are fine since dma_mark_clean() is null on POWERPC. We can
 753         * make dma_mark_clean() take a physical address if necessary.
 754         */
 755        dma_mark_clean(phys_to_virt(paddr), size);
 756}
 757
 758void swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
 759                        size_t size, enum dma_data_direction dir,
 760                        struct dma_attrs *attrs)
 761{
 762        unmap_single(hwdev, dev_addr, size, dir);
 763}
 764EXPORT_SYMBOL_GPL(swiotlb_unmap_page);
 765
 766/*
 767 * Make physical memory consistent for a single streaming mode DMA translation
 768 * after a transfer.
 769 *
 770 * If you perform a swiotlb_map_page() but wish to interrogate the buffer
 771 * using the cpu, yet do not wish to teardown the dma mapping, you must
 772 * call this function before doing so.  At the next point you give the dma
 773 * address back to the card, you must first perform a
 774 * swiotlb_dma_sync_for_device, and then the device again owns the buffer
 775 */
 776static void
 777swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
 778                    size_t size, enum dma_data_direction dir,
 779                    enum dma_sync_target target)
 780{
 781        phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
 782
 783        BUG_ON(dir == DMA_NONE);
 784
 785        if (is_swiotlb_buffer(paddr)) {
 786                swiotlb_tbl_sync_single(hwdev, paddr, size, dir, target);
 787                return;
 788        }
 789
 790        if (dir != DMA_FROM_DEVICE)
 791                return;
 792
 793        dma_mark_clean(phys_to_virt(paddr), size);
 794}
 795
 796void
 797swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
 798                            size_t size, enum dma_data_direction dir)
 799{
 800        swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU);
 801}
 802EXPORT_SYMBOL(swiotlb_sync_single_for_cpu);
 803
 804void
 805swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
 806                               size_t size, enum dma_data_direction dir)
 807{
 808        swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE);
 809}
 810EXPORT_SYMBOL(swiotlb_sync_single_for_device);
 811
 812/*
 813 * Map a set of buffers described by scatterlist in streaming mode for DMA.
 814 * This is the scatter-gather version of the above swiotlb_map_page
 815 * interface.  Here the scatter gather list elements are each tagged with the
 816 * appropriate dma address and length.  They are obtained via
 817 * sg_dma_{address,length}(SG).
 818 *
 819 * NOTE: An implementation may be able to use a smaller number of
 820 *       DMA address/length pairs than there are SG table elements.
 821 *       (for example via virtual mapping capabilities)
 822 *       The routine returns the number of addr/length pairs actually
 823 *       used, at most nents.
 824 *
 825 * Device ownership issues as mentioned above for swiotlb_map_page are the
 826 * same here.
 827 */
 828int
 829swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
 830                     enum dma_data_direction dir, struct dma_attrs *attrs)
 831{
 832        struct scatterlist *sg;
 833        int i;
 834
 835        BUG_ON(dir == DMA_NONE);
 836
 837        for_each_sg(sgl, sg, nelems, i) {
 838                phys_addr_t paddr = sg_phys(sg);
 839                dma_addr_t dev_addr = phys_to_dma(hwdev, paddr);
 840
 841                if (swiotlb_force ||
 842                    !dma_capable(hwdev, dev_addr, sg->length)) {
 843                        phys_addr_t map = map_single(hwdev, sg_phys(sg),
 844                                                     sg->length, dir);
 845                        if (map == SWIOTLB_MAP_ERROR) {
 846                                /* Don't panic here, we expect map_sg users
 847                                   to do proper error handling. */
 848                                swiotlb_full(hwdev, sg->length, dir, 0);
 849                                swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
 850                                                       attrs);
 851                                sgl[0].dma_length = 0;
 852                                return 0;
 853                        }
 854                        sg->dma_address = phys_to_dma(hwdev, map);
 855                } else
 856                        sg->dma_address = dev_addr;
 857                sg->dma_length = sg->length;
 858        }
 859        return nelems;
 860}
 861EXPORT_SYMBOL(swiotlb_map_sg_attrs);
 862
 863int
 864swiotlb_map_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
 865               enum dma_data_direction dir)
 866{
 867        return swiotlb_map_sg_attrs(hwdev, sgl, nelems, dir, NULL);
 868}
 869EXPORT_SYMBOL(swiotlb_map_sg);
 870
 871/*
 872 * Unmap a set of streaming mode DMA translations.  Again, cpu read rules
 873 * concerning calls here are the same as for swiotlb_unmap_page() above.
 874 */
 875void
 876swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
 877                       int nelems, enum dma_data_direction dir, struct dma_attrs *attrs)
 878{
 879        struct scatterlist *sg;
 880        int i;
 881
 882        BUG_ON(dir == DMA_NONE);
 883
 884        for_each_sg(sgl, sg, nelems, i)
 885                unmap_single(hwdev, sg->dma_address, sg->dma_length, dir);
 886
 887}
 888EXPORT_SYMBOL(swiotlb_unmap_sg_attrs);
 889
 890void
 891swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
 892                 enum dma_data_direction dir)
 893{
 894        return swiotlb_unmap_sg_attrs(hwdev, sgl, nelems, dir, NULL);
 895}
 896EXPORT_SYMBOL(swiotlb_unmap_sg);
 897
 898/*
 899 * Make physical memory consistent for a set of streaming mode DMA translations
 900 * after a transfer.
 901 *
 902 * The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
 903 * and usage.
 904 */
 905static void
 906swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl,
 907                int nelems, enum dma_data_direction dir,
 908                enum dma_sync_target target)
 909{
 910        struct scatterlist *sg;
 911        int i;
 912
 913        for_each_sg(sgl, sg, nelems, i)
 914                swiotlb_sync_single(hwdev, sg->dma_address,
 915                                    sg->dma_length, dir, target);
 916}
 917
 918void
 919swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
 920                        int nelems, enum dma_data_direction dir)
 921{
 922        swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU);
 923}
 924EXPORT_SYMBOL(swiotlb_sync_sg_for_cpu);
 925
 926void
 927swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
 928                           int nelems, enum dma_data_direction dir)
 929{
 930        swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
 931}
 932EXPORT_SYMBOL(swiotlb_sync_sg_for_device);
 933
 934int
 935swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
 936{
 937        return (dma_addr == phys_to_dma(hwdev, io_tlb_overflow_buffer));
 938}
 939EXPORT_SYMBOL(swiotlb_dma_mapping_error);
 940
 941/*
 942 * Return whether the given device DMA address mask can be supported
 943 * properly.  For example, if your device can only drive the low 24-bits
 944 * during bus mastering, then you would pass 0x00ffffff as the mask to
 945 * this function.
 946 */
 947int
 948swiotlb_dma_supported(struct device *hwdev, u64 mask)
 949{
 950        return phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
 951}
 952EXPORT_SYMBOL(swiotlb_dma_supported);
 953
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