linux/kernel/dma/swiotlb.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Dynamic DMA mapping support.
   4 *
   5 * This implementation is a fallback for platforms that do not support
   6 * I/O TLBs (aka DMA address translation hardware).
   7 * Copyright (C) 2000 Asit Mallick <Asit.K.Mallick@intel.com>
   8 * Copyright (C) 2000 Goutham Rao <goutham.rao@intel.com>
   9 * Copyright (C) 2000, 2003 Hewlett-Packard Co
  10 *      David Mosberger-Tang <davidm@hpl.hp.com>
  11 *
  12 * 03/05/07 davidm      Switch from PCI-DMA to generic device DMA API.
  13 * 00/12/13 davidm      Rename to swiotlb.c and add mark_clean() to avoid
  14 *                      unnecessary i-cache flushing.
  15 * 04/07/.. ak          Better overflow handling. Assorted fixes.
  16 * 05/09/10 linville    Add support for syncing ranges, support syncing for
  17 *                      DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
  18 * 08/12/11 beckyb      Add highmem support
  19 */
  20
  21#define pr_fmt(fmt) "software IO TLB: " fmt
  22
  23#include <linux/cache.h>
  24#include <linux/dma-direct.h>
  25#include <linux/mm.h>
  26#include <linux/export.h>
  27#include <linux/spinlock.h>
  28#include <linux/string.h>
  29#include <linux/swiotlb.h>
  30#include <linux/pfn.h>
  31#include <linux/types.h>
  32#include <linux/ctype.h>
  33#include <linux/highmem.h>
  34#include <linux/gfp.h>
  35#include <linux/scatterlist.h>
  36#include <linux/mem_encrypt.h>
  37#include <linux/set_memory.h>
  38#ifdef CONFIG_DEBUG_FS
  39#include <linux/debugfs.h>
  40#endif
  41
  42#include <asm/io.h>
  43#include <asm/dma.h>
  44
  45#include <linux/init.h>
  46#include <linux/memblock.h>
  47#include <linux/iommu-helper.h>
  48
  49#define CREATE_TRACE_POINTS
  50#include <trace/events/swiotlb.h>
  51
  52#define OFFSET(val,align) ((unsigned long)      \
  53                           ( (val) & ( (align) - 1)))
  54
  55#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
  56
  57/*
  58 * Minimum IO TLB size to bother booting with.  Systems with mainly
  59 * 64bit capable cards will only lightly use the swiotlb.  If we can't
  60 * allocate a contiguous 1MB, we're probably in trouble anyway.
  61 */
  62#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
  63
  64enum swiotlb_force swiotlb_force;
  65
  66/*
  67 * Used to do a quick range check in swiotlb_tbl_unmap_single and
  68 * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
  69 * API.
  70 */
  71phys_addr_t io_tlb_start, io_tlb_end;
  72
  73/*
  74 * The number of IO TLB blocks (in groups of 64) between io_tlb_start and
  75 * io_tlb_end.  This is command line adjustable via setup_io_tlb_npages.
  76 */
  77static unsigned long io_tlb_nslabs;
  78
  79/*
  80 * The number of used IO TLB block
  81 */
  82static unsigned long io_tlb_used;
  83
  84/*
  85 * This is a free list describing the number of free entries available from
  86 * each index
  87 */
  88static unsigned int *io_tlb_list;
  89static unsigned int io_tlb_index;
  90
  91/*
  92 * Max segment that we can provide which (if pages are contingous) will
  93 * not be bounced (unless SWIOTLB_FORCE is set).
  94 */
  95unsigned int max_segment;
  96
  97/*
  98 * We need to save away the original address corresponding to a mapped entry
  99 * for the sync operations.
 100 */
 101#define INVALID_PHYS_ADDR (~(phys_addr_t)0)
 102static phys_addr_t *io_tlb_orig_addr;
 103
 104/*
 105 * Protect the above data structures in the map and unmap calls
 106 */
 107static DEFINE_SPINLOCK(io_tlb_lock);
 108
 109static int late_alloc;
 110
 111static int __init
 112setup_io_tlb_npages(char *str)
 113{
 114        if (isdigit(*str)) {
 115                io_tlb_nslabs = simple_strtoul(str, &str, 0);
 116                /* avoid tail segment of size < IO_TLB_SEGSIZE */
 117                io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 118        }
 119        if (*str == ',')
 120                ++str;
 121        if (!strcmp(str, "force")) {
 122                swiotlb_force = SWIOTLB_FORCE;
 123        } else if (!strcmp(str, "noforce")) {
 124                swiotlb_force = SWIOTLB_NO_FORCE;
 125                io_tlb_nslabs = 1;
 126        }
 127
 128        return 0;
 129}
 130early_param("swiotlb", setup_io_tlb_npages);
 131
 132static bool no_iotlb_memory;
 133
 134unsigned long swiotlb_nr_tbl(void)
 135{
 136        return unlikely(no_iotlb_memory) ? 0 : io_tlb_nslabs;
 137}
 138EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
 139
 140unsigned int swiotlb_max_segment(void)
 141{
 142        return unlikely(no_iotlb_memory) ? 0 : max_segment;
 143}
 144EXPORT_SYMBOL_GPL(swiotlb_max_segment);
 145
 146void swiotlb_set_max_segment(unsigned int val)
 147{
 148        if (swiotlb_force == SWIOTLB_FORCE)
 149                max_segment = 1;
 150        else
 151                max_segment = rounddown(val, PAGE_SIZE);
 152}
 153
 154/* default to 64MB */
 155#define IO_TLB_DEFAULT_SIZE (64UL<<20)
 156unsigned long swiotlb_size_or_default(void)
 157{
 158        unsigned long size;
 159
 160        size = io_tlb_nslabs << IO_TLB_SHIFT;
 161
 162        return size ? size : (IO_TLB_DEFAULT_SIZE);
 163}
 164
 165void swiotlb_print_info(void)
 166{
 167        unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 168
 169        if (no_iotlb_memory) {
 170                pr_warn("No low mem\n");
 171                return;
 172        }
 173
 174        pr_info("mapped [mem %#010llx-%#010llx] (%luMB)\n",
 175               (unsigned long long)io_tlb_start,
 176               (unsigned long long)io_tlb_end,
 177               bytes >> 20);
 178}
 179
 180/*
 181 * Early SWIOTLB allocation may be too early to allow an architecture to
 182 * perform the desired operations.  This function allows the architecture to
 183 * call SWIOTLB when the operations are possible.  It needs to be called
 184 * before the SWIOTLB memory is used.
 185 */
 186void __init swiotlb_update_mem_attributes(void)
 187{
 188        void *vaddr;
 189        unsigned long bytes;
 190
 191        if (no_iotlb_memory || late_alloc)
 192                return;
 193
 194        vaddr = phys_to_virt(io_tlb_start);
 195        bytes = PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT);
 196        set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
 197        memset(vaddr, 0, bytes);
 198}
 199
 200int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 201{
 202        unsigned long i, bytes;
 203        size_t alloc_size;
 204
 205        bytes = nslabs << IO_TLB_SHIFT;
 206
 207        io_tlb_nslabs = nslabs;
 208        io_tlb_start = __pa(tlb);
 209        io_tlb_end = io_tlb_start + bytes;
 210
 211        /*
 212         * Allocate and initialize the free list array.  This array is used
 213         * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
 214         * between io_tlb_start and io_tlb_end.
 215         */
 216        alloc_size = PAGE_ALIGN(io_tlb_nslabs * sizeof(int));
 217        io_tlb_list = memblock_alloc(alloc_size, PAGE_SIZE);
 218        if (!io_tlb_list)
 219                panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
 220                      __func__, alloc_size, PAGE_SIZE);
 221
 222        alloc_size = PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t));
 223        io_tlb_orig_addr = memblock_alloc(alloc_size, PAGE_SIZE);
 224        if (!io_tlb_orig_addr)
 225                panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
 226                      __func__, alloc_size, PAGE_SIZE);
 227
 228        for (i = 0; i < io_tlb_nslabs; i++) {
 229                io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
 230                io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
 231        }
 232        io_tlb_index = 0;
 233
 234        if (verbose)
 235                swiotlb_print_info();
 236
 237        swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);
 238        return 0;
 239}
 240
 241/*
 242 * Statically reserve bounce buffer space and initialize bounce buffer data
 243 * structures for the software IO TLB used to implement the DMA API.
 244 */
 245void  __init
 246swiotlb_init(int verbose)
 247{
 248        size_t default_size = IO_TLB_DEFAULT_SIZE;
 249        unsigned char *vstart;
 250        unsigned long bytes;
 251
 252        if (!io_tlb_nslabs) {
 253                io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
 254                io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 255        }
 256
 257        bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 258
 259        /* Get IO TLB memory from the low pages */
 260        vstart = memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE);
 261        if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
 262                return;
 263
 264        if (io_tlb_start)
 265                memblock_free_early(io_tlb_start,
 266                                    PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
 267        pr_warn("Cannot allocate buffer");
 268        no_iotlb_memory = true;
 269}
 270
 271/*
 272 * Systems with larger DMA zones (those that don't support ISA) can
 273 * initialize the swiotlb later using the slab allocator if needed.
 274 * This should be just like above, but with some error catching.
 275 */
 276int
 277swiotlb_late_init_with_default_size(size_t default_size)
 278{
 279        unsigned long bytes, req_nslabs = io_tlb_nslabs;
 280        unsigned char *vstart = NULL;
 281        unsigned int order;
 282        int rc = 0;
 283
 284        if (!io_tlb_nslabs) {
 285                io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
 286                io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 287        }
 288
 289        /*
 290         * Get IO TLB memory from the low pages
 291         */
 292        order = get_order(io_tlb_nslabs << IO_TLB_SHIFT);
 293        io_tlb_nslabs = SLABS_PER_PAGE << order;
 294        bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 295
 296        while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
 297                vstart = (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
 298                                                  order);
 299                if (vstart)
 300                        break;
 301                order--;
 302        }
 303
 304        if (!vstart) {
 305                io_tlb_nslabs = req_nslabs;
 306                return -ENOMEM;
 307        }
 308        if (order != get_order(bytes)) {
 309                pr_warn("only able to allocate %ld MB\n",
 310                        (PAGE_SIZE << order) >> 20);
 311                io_tlb_nslabs = SLABS_PER_PAGE << order;
 312        }
 313        rc = swiotlb_late_init_with_tbl(vstart, io_tlb_nslabs);
 314        if (rc)
 315                free_pages((unsigned long)vstart, order);
 316
 317        return rc;
 318}
 319
 320static void swiotlb_cleanup(void)
 321{
 322        io_tlb_end = 0;
 323        io_tlb_start = 0;
 324        io_tlb_nslabs = 0;
 325        max_segment = 0;
 326}
 327
 328int
 329swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 330{
 331        unsigned long i, bytes;
 332
 333        bytes = nslabs << IO_TLB_SHIFT;
 334
 335        io_tlb_nslabs = nslabs;
 336        io_tlb_start = virt_to_phys(tlb);
 337        io_tlb_end = io_tlb_start + bytes;
 338
 339        set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT);
 340        memset(tlb, 0, bytes);
 341
 342        /*
 343         * Allocate and initialize the free list array.  This array is used
 344         * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
 345         * between io_tlb_start and io_tlb_end.
 346         */
 347        io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
 348                                      get_order(io_tlb_nslabs * sizeof(int)));
 349        if (!io_tlb_list)
 350                goto cleanup3;
 351
 352        io_tlb_orig_addr = (phys_addr_t *)
 353                __get_free_pages(GFP_KERNEL,
 354                                 get_order(io_tlb_nslabs *
 355                                           sizeof(phys_addr_t)));
 356        if (!io_tlb_orig_addr)
 357                goto cleanup4;
 358
 359        for (i = 0; i < io_tlb_nslabs; i++) {
 360                io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
 361                io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
 362        }
 363        io_tlb_index = 0;
 364
 365        swiotlb_print_info();
 366
 367        late_alloc = 1;
 368
 369        swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);
 370
 371        return 0;
 372
 373cleanup4:
 374        free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
 375                                                         sizeof(int)));
 376        io_tlb_list = NULL;
 377cleanup3:
 378        swiotlb_cleanup();
 379        return -ENOMEM;
 380}
 381
 382void __init swiotlb_exit(void)
 383{
 384        if (!io_tlb_orig_addr)
 385                return;
 386
 387        if (late_alloc) {
 388                free_pages((unsigned long)io_tlb_orig_addr,
 389                           get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
 390                free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
 391                                                                 sizeof(int)));
 392                free_pages((unsigned long)phys_to_virt(io_tlb_start),
 393                           get_order(io_tlb_nslabs << IO_TLB_SHIFT));
 394        } else {
 395                memblock_free_late(__pa(io_tlb_orig_addr),
 396                                   PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
 397                memblock_free_late(__pa(io_tlb_list),
 398                                   PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
 399                memblock_free_late(io_tlb_start,
 400                                   PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
 401        }
 402        swiotlb_cleanup();
 403}
 404
 405/*
 406 * Bounce: copy the swiotlb buffer from or back to the original dma location
 407 */
 408static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
 409                           size_t size, enum dma_data_direction dir)
 410{
 411        unsigned long pfn = PFN_DOWN(orig_addr);
 412        unsigned char *vaddr = phys_to_virt(tlb_addr);
 413
 414        if (PageHighMem(pfn_to_page(pfn))) {
 415                /* The buffer does not have a mapping.  Map it in and copy */
 416                unsigned int offset = orig_addr & ~PAGE_MASK;
 417                char *buffer;
 418                unsigned int sz = 0;
 419                unsigned long flags;
 420
 421                while (size) {
 422                        sz = min_t(size_t, PAGE_SIZE - offset, size);
 423
 424                        local_irq_save(flags);
 425                        buffer = kmap_atomic(pfn_to_page(pfn));
 426                        if (dir == DMA_TO_DEVICE)
 427                                memcpy(vaddr, buffer + offset, sz);
 428                        else
 429                                memcpy(buffer + offset, vaddr, sz);
 430                        kunmap_atomic(buffer);
 431                        local_irq_restore(flags);
 432
 433                        size -= sz;
 434                        pfn++;
 435                        vaddr += sz;
 436                        offset = 0;
 437                }
 438        } else if (dir == DMA_TO_DEVICE) {
 439                memcpy(vaddr, phys_to_virt(orig_addr), size);
 440        } else {
 441                memcpy(phys_to_virt(orig_addr), vaddr, size);
 442        }
 443}
 444
 445phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
 446                                   dma_addr_t tbl_dma_addr,
 447                                   phys_addr_t orig_addr,
 448                                   size_t mapping_size,
 449                                   size_t alloc_size,
 450                                   enum dma_data_direction dir,
 451                                   unsigned long attrs)
 452{
 453        unsigned long flags;
 454        phys_addr_t tlb_addr;
 455        unsigned int nslots, stride, index, wrap;
 456        int i;
 457        unsigned long mask;
 458        unsigned long offset_slots;
 459        unsigned long max_slots;
 460        unsigned long tmp_io_tlb_used;
 461
 462        if (no_iotlb_memory)
 463                panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
 464
 465        if (mem_encrypt_active())
 466                pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
 467
 468        if (mapping_size > alloc_size) {
 469                dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)",
 470                              mapping_size, alloc_size);
 471                return (phys_addr_t)DMA_MAPPING_ERROR;
 472        }
 473
 474        mask = dma_get_seg_boundary(hwdev);
 475
 476        tbl_dma_addr &= mask;
 477
 478        offset_slots = ALIGN(tbl_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 479
 480        /*
 481         * Carefully handle integer overflow which can occur when mask == ~0UL.
 482         */
 483        max_slots = mask + 1
 484                    ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT
 485                    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
 486
 487        /*
 488         * For mappings greater than or equal to a page, we limit the stride
 489         * (and hence alignment) to a page size.
 490         */
 491        nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 492        if (alloc_size >= PAGE_SIZE)
 493                stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
 494        else
 495                stride = 1;
 496
 497        BUG_ON(!nslots);
 498
 499        /*
 500         * Find suitable number of IO TLB entries size that will fit this
 501         * request and allocate a buffer from that IO TLB pool.
 502         */
 503        spin_lock_irqsave(&io_tlb_lock, flags);
 504
 505        if (unlikely(nslots > io_tlb_nslabs - io_tlb_used))
 506                goto not_found;
 507
 508        index = ALIGN(io_tlb_index, stride);
 509        if (index >= io_tlb_nslabs)
 510                index = 0;
 511        wrap = index;
 512
 513        do {
 514                while (iommu_is_span_boundary(index, nslots, offset_slots,
 515                                              max_slots)) {
 516                        index += stride;
 517                        if (index >= io_tlb_nslabs)
 518                                index = 0;
 519                        if (index == wrap)
 520                                goto not_found;
 521                }
 522
 523                /*
 524                 * If we find a slot that indicates we have 'nslots' number of
 525                 * contiguous buffers, we allocate the buffers from that slot
 526                 * and mark the entries as '0' indicating unavailable.
 527                 */
 528                if (io_tlb_list[index] >= nslots) {
 529                        int count = 0;
 530
 531                        for (i = index; i < (int) (index + nslots); i++)
 532                                io_tlb_list[i] = 0;
 533                        for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
 534                                io_tlb_list[i] = ++count;
 535                        tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
 536
 537                        /*
 538                         * Update the indices to avoid searching in the next
 539                         * round.
 540                         */
 541                        io_tlb_index = ((index + nslots) < io_tlb_nslabs
 542                                        ? (index + nslots) : 0);
 543
 544                        goto found;
 545                }
 546                index += stride;
 547                if (index >= io_tlb_nslabs)
 548                        index = 0;
 549        } while (index != wrap);
 550
 551not_found:
 552        tmp_io_tlb_used = io_tlb_used;
 553
 554        spin_unlock_irqrestore(&io_tlb_lock, flags);
 555        if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
 556                dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
 557                         alloc_size, io_tlb_nslabs, tmp_io_tlb_used);
 558        return (phys_addr_t)DMA_MAPPING_ERROR;
 559found:
 560        io_tlb_used += nslots;
 561        spin_unlock_irqrestore(&io_tlb_lock, flags);
 562
 563        /*
 564         * Save away the mapping from the original address to the DMA address.
 565         * This is needed when we sync the memory.  Then we sync the buffer if
 566         * needed.
 567         */
 568        for (i = 0; i < nslots; i++)
 569                io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
 570        if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
 571            (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
 572                swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
 573
 574        return tlb_addr;
 575}
 576
 577/*
 578 * tlb_addr is the physical address of the bounce buffer to unmap.
 579 */
 580void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
 581                              size_t mapping_size, size_t alloc_size,
 582                              enum dma_data_direction dir, unsigned long attrs)
 583{
 584        unsigned long flags;
 585        int i, count, nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 586        int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
 587        phys_addr_t orig_addr = io_tlb_orig_addr[index];
 588
 589        /*
 590         * First, sync the memory before unmapping the entry
 591         */
 592        if (orig_addr != INVALID_PHYS_ADDR &&
 593            !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
 594            ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
 595                swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_FROM_DEVICE);
 596
 597        /*
 598         * Return the buffer to the free list by setting the corresponding
 599         * entries to indicate the number of contiguous entries available.
 600         * While returning the entries to the free list, we merge the entries
 601         * with slots below and above the pool being returned.
 602         */
 603        spin_lock_irqsave(&io_tlb_lock, flags);
 604        {
 605                count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
 606                         io_tlb_list[index + nslots] : 0);
 607                /*
 608                 * Step 1: return the slots to the free list, merging the
 609                 * slots with superceeding slots
 610                 */
 611                for (i = index + nslots - 1; i >= index; i--) {
 612                        io_tlb_list[i] = ++count;
 613                        io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
 614                }
 615                /*
 616                 * Step 2: merge the returned slots with the preceding slots,
 617                 * if available (non zero)
 618                 */
 619                for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
 620                        io_tlb_list[i] = ++count;
 621
 622                io_tlb_used -= nslots;
 623        }
 624        spin_unlock_irqrestore(&io_tlb_lock, flags);
 625}
 626
 627void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
 628                             size_t size, enum dma_data_direction dir,
 629                             enum dma_sync_target target)
 630{
 631        int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
 632        phys_addr_t orig_addr = io_tlb_orig_addr[index];
 633
 634        if (orig_addr == INVALID_PHYS_ADDR)
 635                return;
 636        orig_addr += (unsigned long)tlb_addr & ((1 << IO_TLB_SHIFT) - 1);
 637
 638        switch (target) {
 639        case SYNC_FOR_CPU:
 640                if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
 641                        swiotlb_bounce(orig_addr, tlb_addr,
 642                                       size, DMA_FROM_DEVICE);
 643                else
 644                        BUG_ON(dir != DMA_TO_DEVICE);
 645                break;
 646        case SYNC_FOR_DEVICE:
 647                if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
 648                        swiotlb_bounce(orig_addr, tlb_addr,
 649                                       size, DMA_TO_DEVICE);
 650                else
 651                        BUG_ON(dir != DMA_FROM_DEVICE);
 652                break;
 653        default:
 654                BUG();
 655        }
 656}
 657
 658/*
 659 * Create a swiotlb mapping for the buffer at @phys, and in case of DMAing
 660 * to the device copy the data into it as well.
 661 */
 662bool swiotlb_map(struct device *dev, phys_addr_t *phys, dma_addr_t *dma_addr,
 663                size_t size, enum dma_data_direction dir, unsigned long attrs)
 664{
 665        trace_swiotlb_bounced(dev, *dma_addr, size, swiotlb_force);
 666
 667        if (unlikely(swiotlb_force == SWIOTLB_NO_FORCE)) {
 668                dev_warn_ratelimited(dev,
 669                        "Cannot do DMA to address %pa\n", phys);
 670                return false;
 671        }
 672
 673        /* Oh well, have to allocate and map a bounce buffer. */
 674        *phys = swiotlb_tbl_map_single(dev, __phys_to_dma(dev, io_tlb_start),
 675                        *phys, size, size, dir, attrs);
 676        if (*phys == (phys_addr_t)DMA_MAPPING_ERROR)
 677                return false;
 678
 679        /* Ensure that the address returned is DMA'ble */
 680        *dma_addr = __phys_to_dma(dev, *phys);
 681        if (unlikely(!dma_capable(dev, *dma_addr, size))) {
 682                swiotlb_tbl_unmap_single(dev, *phys, size, size, dir,
 683                        attrs | DMA_ATTR_SKIP_CPU_SYNC);
 684                return false;
 685        }
 686
 687        return true;
 688}
 689
 690size_t swiotlb_max_mapping_size(struct device *dev)
 691{
 692        return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
 693}
 694
 695bool is_swiotlb_active(void)
 696{
 697        /*
 698         * When SWIOTLB is initialized, even if io_tlb_start points to physical
 699         * address zero, io_tlb_end surely doesn't.
 700         */
 701        return io_tlb_end != 0;
 702}
 703
 704#ifdef CONFIG_DEBUG_FS
 705
 706static int __init swiotlb_create_debugfs(void)
 707{
 708        struct dentry *root;
 709
 710        root = debugfs_create_dir("swiotlb", NULL);
 711        debugfs_create_ulong("io_tlb_nslabs", 0400, root, &io_tlb_nslabs);
 712        debugfs_create_ulong("io_tlb_used", 0400, root, &io_tlb_used);
 713        return 0;
 714}
 715
 716late_initcall(swiotlb_create_debugfs);
 717
 718#endif
 719