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 char *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 void *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        phys_addr_t pstart, pend;
 129
 130        pstart = virt_to_phys(io_tlb_start);
 131        pend = virt_to_phys(io_tlb_end);
 132
 133        printk(KERN_INFO "software IO TLB [mem %#010llx-%#010llx] (%luMB) mapped at [%p-%p]\n",
 134               (unsigned long long)pstart, (unsigned long long)pend - 1,
 135               bytes >> 20, io_tlb_start, io_tlb_end - 1);
 136}
 137
 138void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 139{
 140        unsigned long i, bytes;
 141
 142        bytes = nslabs << IO_TLB_SHIFT;
 143
 144        io_tlb_nslabs = nslabs;
 145        io_tlb_start = tlb;
 146        io_tlb_end = io_tlb_start + bytes;
 147
 148        /*
 149         * Allocate and initialize the free list array.  This array is used
 150         * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
 151         * between io_tlb_start and io_tlb_end.
 152         */
 153        io_tlb_list = alloc_bootmem_pages(PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
 154        for (i = 0; i < io_tlb_nslabs; i++)
 155                io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
 156        io_tlb_index = 0;
 157        io_tlb_orig_addr = alloc_bootmem_pages(PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
 158
 159        /*
 160         * Get the overflow emergency buffer
 161         */
 162        io_tlb_overflow_buffer = alloc_bootmem_low_pages(PAGE_ALIGN(io_tlb_overflow));
 163        if (!io_tlb_overflow_buffer)
 164                panic("Cannot allocate SWIOTLB overflow buffer!\n");
 165        if (verbose)
 166                swiotlb_print_info();
 167}
 168
 169/*
 170 * Statically reserve bounce buffer space and initialize bounce buffer data
 171 * structures for the software IO TLB used to implement the DMA API.
 172 */
 173void __init
 174swiotlb_init_with_default_size(size_t default_size, int verbose)
 175{
 176        unsigned long bytes;
 177
 178        if (!io_tlb_nslabs) {
 179                io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
 180                io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 181        }
 182
 183        bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 184
 185        /*
 186         * Get IO TLB memory from the low pages
 187         */
 188        io_tlb_start = alloc_bootmem_low_pages(PAGE_ALIGN(bytes));
 189        if (!io_tlb_start)
 190                panic("Cannot allocate SWIOTLB buffer");
 191
 192        swiotlb_init_with_tbl(io_tlb_start, io_tlb_nslabs, verbose);
 193}
 194
 195void __init
 196swiotlb_init(int verbose)
 197{
 198        swiotlb_init_with_default_size(64 * (1<<20), verbose);  /* default to 64MB */
 199}
 200
 201/*
 202 * Systems with larger DMA zones (those that don't support ISA) can
 203 * initialize the swiotlb later using the slab allocator if needed.
 204 * This should be just like above, but with some error catching.
 205 */
 206int
 207swiotlb_late_init_with_default_size(size_t default_size)
 208{
 209        unsigned long i, bytes, req_nslabs = io_tlb_nslabs;
 210        unsigned int order;
 211
 212        if (!io_tlb_nslabs) {
 213                io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
 214                io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 215        }
 216
 217        /*
 218         * Get IO TLB memory from the low pages
 219         */
 220        order = get_order(io_tlb_nslabs << IO_TLB_SHIFT);
 221        io_tlb_nslabs = SLABS_PER_PAGE << order;
 222        bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 223
 224        while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
 225                io_tlb_start = (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
 226                                                        order);
 227                if (io_tlb_start)
 228                        break;
 229                order--;
 230        }
 231
 232        if (!io_tlb_start)
 233                goto cleanup1;
 234
 235        if (order != get_order(bytes)) {
 236                printk(KERN_WARNING "Warning: only able to allocate %ld MB "
 237                       "for software IO TLB\n", (PAGE_SIZE << order) >> 20);
 238                io_tlb_nslabs = SLABS_PER_PAGE << order;
 239                bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 240        }
 241        io_tlb_end = io_tlb_start + bytes;
 242        memset(io_tlb_start, 0, bytes);
 243
 244        /*
 245         * Allocate and initialize the free list array.  This array is used
 246         * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
 247         * between io_tlb_start and io_tlb_end.
 248         */
 249        io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
 250                                      get_order(io_tlb_nslabs * sizeof(int)));
 251        if (!io_tlb_list)
 252                goto cleanup2;
 253
 254        for (i = 0; i < io_tlb_nslabs; i++)
 255                io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
 256        io_tlb_index = 0;
 257
 258        io_tlb_orig_addr = (phys_addr_t *)
 259                __get_free_pages(GFP_KERNEL,
 260                                 get_order(io_tlb_nslabs *
 261                                           sizeof(phys_addr_t)));
 262        if (!io_tlb_orig_addr)
 263                goto cleanup3;
 264
 265        memset(io_tlb_orig_addr, 0, io_tlb_nslabs * sizeof(phys_addr_t));
 266
 267        /*
 268         * Get the overflow emergency buffer
 269         */
 270        io_tlb_overflow_buffer = (void *)__get_free_pages(GFP_DMA,
 271                                                  get_order(io_tlb_overflow));
 272        if (!io_tlb_overflow_buffer)
 273                goto cleanup4;
 274
 275        swiotlb_print_info();
 276
 277        late_alloc = 1;
 278
 279        return 0;
 280
 281cleanup4:
 282        free_pages((unsigned long)io_tlb_orig_addr,
 283                   get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
 284        io_tlb_orig_addr = NULL;
 285cleanup3:
 286        free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
 287                                                         sizeof(int)));
 288        io_tlb_list = NULL;
 289cleanup2:
 290        io_tlb_end = NULL;
 291        free_pages((unsigned long)io_tlb_start, order);
 292        io_tlb_start = NULL;
 293cleanup1:
 294        io_tlb_nslabs = req_nslabs;
 295        return -ENOMEM;
 296}
 297
 298void __init swiotlb_free(void)
 299{
 300        if (!io_tlb_overflow_buffer)
 301                return;
 302
 303        if (late_alloc) {
 304                free_pages((unsigned long)io_tlb_overflow_buffer,
 305                           get_order(io_tlb_overflow));
 306                free_pages((unsigned long)io_tlb_orig_addr,
 307                           get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
 308                free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
 309                                                                 sizeof(int)));
 310                free_pages((unsigned long)io_tlb_start,
 311                           get_order(io_tlb_nslabs << IO_TLB_SHIFT));
 312        } else {
 313                free_bootmem_late(__pa(io_tlb_overflow_buffer),
 314                                  PAGE_ALIGN(io_tlb_overflow));
 315                free_bootmem_late(__pa(io_tlb_orig_addr),
 316                                  PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
 317                free_bootmem_late(__pa(io_tlb_list),
 318                                  PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
 319                free_bootmem_late(__pa(io_tlb_start),
 320                                  PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
 321        }
 322        io_tlb_nslabs = 0;
 323}
 324
 325static int is_swiotlb_buffer(phys_addr_t paddr)
 326{
 327        return paddr >= virt_to_phys(io_tlb_start) &&
 328                paddr < virt_to_phys(io_tlb_end);
 329}
 330
 331/*
 332 * Bounce: copy the swiotlb buffer back to the original dma location
 333 */
 334void swiotlb_bounce(phys_addr_t phys, char *dma_addr, size_t size,
 335                    enum dma_data_direction dir)
 336{
 337        unsigned long pfn = PFN_DOWN(phys);
 338
 339        if (PageHighMem(pfn_to_page(pfn))) {
 340                /* The buffer does not have a mapping.  Map it in and copy */
 341                unsigned int offset = phys & ~PAGE_MASK;
 342                char *buffer;
 343                unsigned int sz = 0;
 344                unsigned long flags;
 345
 346                while (size) {
 347                        sz = min_t(size_t, PAGE_SIZE - offset, size);
 348
 349                        local_irq_save(flags);
 350                        buffer = kmap_atomic(pfn_to_page(pfn));
 351                        if (dir == DMA_TO_DEVICE)
 352                                memcpy(dma_addr, buffer + offset, sz);
 353                        else
 354                                memcpy(buffer + offset, dma_addr, sz);
 355                        kunmap_atomic(buffer);
 356                        local_irq_restore(flags);
 357
 358                        size -= sz;
 359                        pfn++;
 360                        dma_addr += sz;
 361                        offset = 0;
 362                }
 363        } else {
 364                if (dir == DMA_TO_DEVICE)
 365                        memcpy(dma_addr, phys_to_virt(phys), size);
 366                else
 367                        memcpy(phys_to_virt(phys), dma_addr, size);
 368        }
 369}
 370EXPORT_SYMBOL_GPL(swiotlb_bounce);
 371
 372void *swiotlb_tbl_map_single(struct device *hwdev, dma_addr_t tbl_dma_addr,
 373                             phys_addr_t phys, size_t size,
 374                             enum dma_data_direction dir)
 375{
 376        unsigned long flags;
 377        char *dma_addr;
 378        unsigned int nslots, stride, index, wrap;
 379        int i;
 380        unsigned long mask;
 381        unsigned long offset_slots;
 382        unsigned long max_slots;
 383
 384        mask = dma_get_seg_boundary(hwdev);
 385
 386        tbl_dma_addr &= mask;
 387
 388        offset_slots = ALIGN(tbl_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 389
 390        /*
 391         * Carefully handle integer overflow which can occur when mask == ~0UL.
 392         */
 393        max_slots = mask + 1
 394                    ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT
 395                    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
 396
 397        /*
 398         * For mappings greater than a page, we limit the stride (and
 399         * hence alignment) to a page size.
 400         */
 401        nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 402        if (size > PAGE_SIZE)
 403                stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
 404        else
 405                stride = 1;
 406
 407        BUG_ON(!nslots);
 408
 409        /*
 410         * Find suitable number of IO TLB entries size that will fit this
 411         * request and allocate a buffer from that IO TLB pool.
 412         */
 413        spin_lock_irqsave(&io_tlb_lock, flags);
 414        index = ALIGN(io_tlb_index, stride);
 415        if (index >= io_tlb_nslabs)
 416                index = 0;
 417        wrap = index;
 418
 419        do {
 420                while (iommu_is_span_boundary(index, nslots, offset_slots,
 421                                              max_slots)) {
 422                        index += stride;
 423                        if (index >= io_tlb_nslabs)
 424                                index = 0;
 425                        if (index == wrap)
 426                                goto not_found;
 427                }
 428
 429                /*
 430                 * If we find a slot that indicates we have 'nslots' number of
 431                 * contiguous buffers, we allocate the buffers from that slot
 432                 * and mark the entries as '0' indicating unavailable.
 433                 */
 434                if (io_tlb_list[index] >= nslots) {
 435                        int count = 0;
 436
 437                        for (i = index; i < (int) (index + nslots); i++)
 438                                io_tlb_list[i] = 0;
 439                        for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
 440                                io_tlb_list[i] = ++count;
 441                        dma_addr = io_tlb_start + (index << IO_TLB_SHIFT);
 442
 443                        /*
 444                         * Update the indices to avoid searching in the next
 445                         * round.
 446                         */
 447                        io_tlb_index = ((index + nslots) < io_tlb_nslabs
 448                                        ? (index + nslots) : 0);
 449
 450                        goto found;
 451                }
 452                index += stride;
 453                if (index >= io_tlb_nslabs)
 454                        index = 0;
 455        } while (index != wrap);
 456
 457not_found:
 458        spin_unlock_irqrestore(&io_tlb_lock, flags);
 459        return NULL;
 460found:
 461        spin_unlock_irqrestore(&io_tlb_lock, flags);
 462
 463        /*
 464         * Save away the mapping from the original address to the DMA address.
 465         * This is needed when we sync the memory.  Then we sync the buffer if
 466         * needed.
 467         */
 468        for (i = 0; i < nslots; i++)
 469                io_tlb_orig_addr[index+i] = phys + (i << IO_TLB_SHIFT);
 470        if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
 471                swiotlb_bounce(phys, dma_addr, size, DMA_TO_DEVICE);
 472
 473        return dma_addr;
 474}
 475EXPORT_SYMBOL_GPL(swiotlb_tbl_map_single);
 476
 477/*
 478 * Allocates bounce buffer and returns its kernel virtual address.
 479 */
 480
 481static void *
 482map_single(struct device *hwdev, phys_addr_t phys, size_t size,
 483           enum dma_data_direction dir)
 484{
 485        dma_addr_t start_dma_addr = swiotlb_virt_to_bus(hwdev, io_tlb_start);
 486
 487        return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size, dir);
 488}
 489
 490/*
 491 * dma_addr is the kernel virtual address of the bounce buffer to unmap.
 492 */
 493void
 494swiotlb_tbl_unmap_single(struct device *hwdev, char *dma_addr, size_t size,
 495                        enum dma_data_direction dir)
 496{
 497        unsigned long flags;
 498        int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 499        int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
 500        phys_addr_t phys = io_tlb_orig_addr[index];
 501
 502        /*
 503         * First, sync the memory before unmapping the entry
 504         */
 505        if (phys && ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
 506                swiotlb_bounce(phys, dma_addr, size, DMA_FROM_DEVICE);
 507
 508        /*
 509         * Return the buffer to the free list by setting the corresponding
 510         * entries to indicate the number of contiguous entries available.
 511         * While returning the entries to the free list, we merge the entries
 512         * with slots below and above the pool being returned.
 513         */
 514        spin_lock_irqsave(&io_tlb_lock, flags);
 515        {
 516                count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
 517                         io_tlb_list[index + nslots] : 0);
 518                /*
 519                 * Step 1: return the slots to the free list, merging the
 520                 * slots with superceeding slots
 521                 */
 522                for (i = index + nslots - 1; i >= index; i--)
 523                        io_tlb_list[i] = ++count;
 524                /*
 525                 * Step 2: merge the returned slots with the preceding slots,
 526                 * if available (non zero)
 527                 */
 528                for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
 529                        io_tlb_list[i] = ++count;
 530        }
 531        spin_unlock_irqrestore(&io_tlb_lock, flags);
 532}
 533EXPORT_SYMBOL_GPL(swiotlb_tbl_unmap_single);
 534
 535void
 536swiotlb_tbl_sync_single(struct device *hwdev, char *dma_addr, size_t size,
 537                        enum dma_data_direction dir,
 538                        enum dma_sync_target target)
 539{
 540        int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
 541        phys_addr_t phys = io_tlb_orig_addr[index];
 542
 543        phys += ((unsigned long)dma_addr & ((1 << IO_TLB_SHIFT) - 1));
 544
 545        switch (target) {
 546        case SYNC_FOR_CPU:
 547                if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
 548                        swiotlb_bounce(phys, dma_addr, size, DMA_FROM_DEVICE);
 549                else
 550                        BUG_ON(dir != DMA_TO_DEVICE);
 551                break;
 552        case SYNC_FOR_DEVICE:
 553                if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
 554                        swiotlb_bounce(phys, dma_addr, size, DMA_TO_DEVICE);
 555                else
 556                        BUG_ON(dir != DMA_FROM_DEVICE);
 557                break;
 558        default:
 559                BUG();
 560        }
 561}
 562EXPORT_SYMBOL_GPL(swiotlb_tbl_sync_single);
 563
 564void *
 565swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 566                       dma_addr_t *dma_handle, gfp_t flags)
 567{
 568        dma_addr_t dev_addr;
 569        void *ret;
 570        int order = get_order(size);
 571        u64 dma_mask = DMA_BIT_MASK(32);
 572
 573        if (hwdev && hwdev->coherent_dma_mask)
 574                dma_mask = hwdev->coherent_dma_mask;
 575
 576        ret = (void *)__get_free_pages(flags, order);
 577        if (ret && swiotlb_virt_to_bus(hwdev, ret) + size - 1 > dma_mask) {
 578                /*
 579                 * The allocated memory isn't reachable by the device.
 580                 */
 581                free_pages((unsigned long) ret, order);
 582                ret = NULL;
 583        }
 584        if (!ret) {
 585                /*
 586                 * We are either out of memory or the device can't DMA to
 587                 * GFP_DMA memory; fall back on map_single(), which
 588                 * will grab memory from the lowest available address range.
 589                 */
 590                ret = map_single(hwdev, 0, size, DMA_FROM_DEVICE);
 591                if (!ret)
 592                        return NULL;
 593        }
 594
 595        memset(ret, 0, size);
 596        dev_addr = swiotlb_virt_to_bus(hwdev, ret);
 597
 598        /* Confirm address can be DMA'd by device */
 599        if (dev_addr + size - 1 > dma_mask) {
 600                printk("hwdev DMA mask = 0x%016Lx, dev_addr = 0x%016Lx\n",
 601                       (unsigned long long)dma_mask,
 602                       (unsigned long long)dev_addr);
 603
 604                /* DMA_TO_DEVICE to avoid memcpy in unmap_single */
 605                swiotlb_tbl_unmap_single(hwdev, ret, size, DMA_TO_DEVICE);
 606                return NULL;
 607        }
 608        *dma_handle = dev_addr;
 609        return ret;
 610}
 611EXPORT_SYMBOL(swiotlb_alloc_coherent);
 612
 613void
 614swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
 615                      dma_addr_t dev_addr)
 616{
 617        phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
 618
 619        WARN_ON(irqs_disabled());
 620        if (!is_swiotlb_buffer(paddr))
 621                free_pages((unsigned long)vaddr, get_order(size));
 622        else
 623                /* DMA_TO_DEVICE to avoid memcpy in swiotlb_tbl_unmap_single */
 624                swiotlb_tbl_unmap_single(hwdev, vaddr, size, DMA_TO_DEVICE);
 625}
 626EXPORT_SYMBOL(swiotlb_free_coherent);
 627
 628static void
 629swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir,
 630             int do_panic)
 631{
 632        /*
 633         * Ran out of IOMMU space for this operation. This is very bad.
 634         * Unfortunately the drivers cannot handle this operation properly.
 635         * unless they check for dma_mapping_error (most don't)
 636         * When the mapping is small enough return a static buffer to limit
 637         * the damage, or panic when the transfer is too big.
 638         */
 639        printk(KERN_ERR "DMA: Out of SW-IOMMU space for %zu bytes at "
 640               "device %s\n", size, dev ? dev_name(dev) : "?");
 641
 642        if (size <= io_tlb_overflow || !do_panic)
 643                return;
 644
 645        if (dir == DMA_BIDIRECTIONAL)
 646                panic("DMA: Random memory could be DMA accessed\n");
 647        if (dir == DMA_FROM_DEVICE)
 648                panic("DMA: Random memory could be DMA written\n");
 649        if (dir == DMA_TO_DEVICE)
 650                panic("DMA: Random memory could be DMA read\n");
 651}
 652
 653/*
 654 * Map a single buffer of the indicated size for DMA in streaming mode.  The
 655 * physical address to use is returned.
 656 *
 657 * Once the device is given the dma address, the device owns this memory until
 658 * either swiotlb_unmap_page or swiotlb_dma_sync_single is performed.
 659 */
 660dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 661                            unsigned long offset, size_t size,
 662                            enum dma_data_direction dir,
 663                            struct dma_attrs *attrs)
 664{
 665        phys_addr_t phys = page_to_phys(page) + offset;
 666        dma_addr_t dev_addr = phys_to_dma(dev, phys);
 667        void *map;
 668
 669        BUG_ON(dir == DMA_NONE);
 670        /*
 671         * If the address happens to be in the device's DMA window,
 672         * we can safely return the device addr and not worry about bounce
 673         * buffering it.
 674         */
 675        if (dma_capable(dev, dev_addr, size) && !swiotlb_force)
 676                return dev_addr;
 677
 678        /*
 679         * Oh well, have to allocate and map a bounce buffer.
 680         */
 681        map = map_single(dev, phys, size, dir);
 682        if (!map) {
 683                swiotlb_full(dev, size, dir, 1);
 684                map = io_tlb_overflow_buffer;
 685        }
 686
 687        dev_addr = swiotlb_virt_to_bus(dev, map);
 688
 689        /*
 690         * Ensure that the address returned is DMA'ble
 691         */
 692        if (!dma_capable(dev, dev_addr, size)) {
 693                swiotlb_tbl_unmap_single(dev, map, size, dir);
 694                dev_addr = swiotlb_virt_to_bus(dev, io_tlb_overflow_buffer);
 695        }
 696
 697        return dev_addr;
 698}
 699EXPORT_SYMBOL_GPL(swiotlb_map_page);
 700
 701/*
 702 * Unmap a single streaming mode DMA translation.  The dma_addr and size must
 703 * match what was provided for in a previous swiotlb_map_page call.  All
 704 * other usages are undefined.
 705 *
 706 * After this call, reads by the cpu to the buffer are guaranteed to see
 707 * whatever the device wrote there.
 708 */
 709static void unmap_single(struct device *hwdev, dma_addr_t dev_addr,
 710                         size_t size, enum dma_data_direction dir)
 711{
 712        phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
 713
 714        BUG_ON(dir == DMA_NONE);
 715
 716        if (is_swiotlb_buffer(paddr)) {
 717                swiotlb_tbl_unmap_single(hwdev, phys_to_virt(paddr), size, dir);
 718                return;
 719        }
 720
 721        if (dir != DMA_FROM_DEVICE)
 722                return;
 723
 724        /*
 725         * phys_to_virt doesn't work with hihgmem page but we could
 726         * call dma_mark_clean() with hihgmem page here. However, we
 727         * are fine since dma_mark_clean() is null on POWERPC. We can
 728         * make dma_mark_clean() take a physical address if necessary.
 729         */
 730        dma_mark_clean(phys_to_virt(paddr), size);
 731}
 732
 733void swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
 734                        size_t size, enum dma_data_direction dir,
 735                        struct dma_attrs *attrs)
 736{
 737        unmap_single(hwdev, dev_addr, size, dir);
 738}
 739EXPORT_SYMBOL_GPL(swiotlb_unmap_page);
 740
 741/*
 742 * Make physical memory consistent for a single streaming mode DMA translation
 743 * after a transfer.
 744 *
 745 * If you perform a swiotlb_map_page() but wish to interrogate the buffer
 746 * using the cpu, yet do not wish to teardown the dma mapping, you must
 747 * call this function before doing so.  At the next point you give the dma
 748 * address back to the card, you must first perform a
 749 * swiotlb_dma_sync_for_device, and then the device again owns the buffer
 750 */
 751static void
 752swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
 753                    size_t size, enum dma_data_direction dir,
 754                    enum dma_sync_target target)
 755{
 756        phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
 757
 758        BUG_ON(dir == DMA_NONE);
 759
 760        if (is_swiotlb_buffer(paddr)) {
 761                swiotlb_tbl_sync_single(hwdev, phys_to_virt(paddr), size, dir,
 762                                       target);
 763                return;
 764        }
 765
 766        if (dir != DMA_FROM_DEVICE)
 767                return;
 768
 769        dma_mark_clean(phys_to_virt(paddr), size);
 770}
 771
 772void
 773swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
 774                            size_t size, enum dma_data_direction dir)
 775{
 776        swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU);
 777}
 778EXPORT_SYMBOL(swiotlb_sync_single_for_cpu);
 779
 780void
 781swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
 782                               size_t size, enum dma_data_direction dir)
 783{
 784        swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE);
 785}
 786EXPORT_SYMBOL(swiotlb_sync_single_for_device);
 787
 788/*
 789 * Map a set of buffers described by scatterlist in streaming mode for DMA.
 790 * This is the scatter-gather version of the above swiotlb_map_page
 791 * interface.  Here the scatter gather list elements are each tagged with the
 792 * appropriate dma address and length.  They are obtained via
 793 * sg_dma_{address,length}(SG).
 794 *
 795 * NOTE: An implementation may be able to use a smaller number of
 796 *       DMA address/length pairs than there are SG table elements.
 797 *       (for example via virtual mapping capabilities)
 798 *       The routine returns the number of addr/length pairs actually
 799 *       used, at most nents.
 800 *
 801 * Device ownership issues as mentioned above for swiotlb_map_page are the
 802 * same here.
 803 */
 804int
 805swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
 806                     enum dma_data_direction dir, struct dma_attrs *attrs)
 807{
 808        struct scatterlist *sg;
 809        int i;
 810
 811        BUG_ON(dir == DMA_NONE);
 812
 813        for_each_sg(sgl, sg, nelems, i) {
 814                phys_addr_t paddr = sg_phys(sg);
 815                dma_addr_t dev_addr = phys_to_dma(hwdev, paddr);
 816
 817                if (swiotlb_force ||
 818                    !dma_capable(hwdev, dev_addr, sg->length)) {
 819                        void *map = map_single(hwdev, sg_phys(sg),
 820                                               sg->length, dir);
 821                        if (!map) {
 822                                /* Don't panic here, we expect map_sg users
 823                                   to do proper error handling. */
 824                                swiotlb_full(hwdev, sg->length, dir, 0);
 825                                swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
 826                                                       attrs);
 827                                sgl[0].dma_length = 0;
 828                                return 0;
 829                        }
 830                        sg->dma_address = swiotlb_virt_to_bus(hwdev, map);
 831                } else
 832                        sg->dma_address = dev_addr;
 833                sg->dma_length = sg->length;
 834        }
 835        return nelems;
 836}
 837EXPORT_SYMBOL(swiotlb_map_sg_attrs);
 838
 839int
 840swiotlb_map_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
 841               enum dma_data_direction dir)
 842{
 843        return swiotlb_map_sg_attrs(hwdev, sgl, nelems, dir, NULL);
 844}
 845EXPORT_SYMBOL(swiotlb_map_sg);
 846
 847/*
 848 * Unmap a set of streaming mode DMA translations.  Again, cpu read rules
 849 * concerning calls here are the same as for swiotlb_unmap_page() above.
 850 */
 851void
 852swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
 853                       int nelems, enum dma_data_direction dir, struct dma_attrs *attrs)
 854{
 855        struct scatterlist *sg;
 856        int i;
 857
 858        BUG_ON(dir == DMA_NONE);
 859
 860        for_each_sg(sgl, sg, nelems, i)
 861                unmap_single(hwdev, sg->dma_address, sg->dma_length, dir);
 862
 863}
 864EXPORT_SYMBOL(swiotlb_unmap_sg_attrs);
 865
 866void
 867swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sgl, int nelems,
 868                 enum dma_data_direction dir)
 869{
 870        return swiotlb_unmap_sg_attrs(hwdev, sgl, nelems, dir, NULL);
 871}
 872EXPORT_SYMBOL(swiotlb_unmap_sg);
 873
 874/*
 875 * Make physical memory consistent for a set of streaming mode DMA translations
 876 * after a transfer.
 877 *
 878 * The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
 879 * and usage.
 880 */
 881static void
 882swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl,
 883                int nelems, enum dma_data_direction dir,
 884                enum dma_sync_target target)
 885{
 886        struct scatterlist *sg;
 887        int i;
 888
 889        for_each_sg(sgl, sg, nelems, i)
 890                swiotlb_sync_single(hwdev, sg->dma_address,
 891                                    sg->dma_length, dir, target);
 892}
 893
 894void
 895swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
 896                        int nelems, enum dma_data_direction dir)
 897{
 898        swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU);
 899}
 900EXPORT_SYMBOL(swiotlb_sync_sg_for_cpu);
 901
 902void
 903swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
 904                           int nelems, enum dma_data_direction dir)
 905{
 906        swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
 907}
 908EXPORT_SYMBOL(swiotlb_sync_sg_for_device);
 909
 910int
 911swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
 912{
 913        return (dma_addr == swiotlb_virt_to_bus(hwdev, io_tlb_overflow_buffer));
 914}
 915EXPORT_SYMBOL(swiotlb_dma_mapping_error);
 916
 917/*
 918 * Return whether the given device DMA address mask can be supported
 919 * properly.  For example, if your device can only drive the low 24-bits
 920 * during bus mastering, then you would pass 0x00ffffff as the mask to
 921 * this function.
 922 */
 923int
 924swiotlb_dma_supported(struct device *hwdev, u64 mask)
 925{
 926        return swiotlb_virt_to_bus(hwdev, io_tlb_end - 1) <= mask;
 927}
 928EXPORT_SYMBOL(swiotlb_dma_supported);
 929
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