kernel/dma/swiotlb.c

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This source file includes following definitions.
setup_io_tlb_npages
swiotlb_nr_tbl
swiotlb_max_segment
swiotlb_set_max_segment
swiotlb_size_or_default
swiotlb_print_info
swiotlb_update_mem_attributes
swiotlb_init_with_tbl
swiotlb_init
swiotlb_late_init_with_default_size
swiotlb_cleanup
swiotlb_late_init_with_tbl
swiotlb_exit
swiotlb_bounce
swiotlb_tbl_map_single
swiotlb_tbl_unmap_single
swiotlb_tbl_sync_single
swiotlb_map
swiotlb_max_mapping_size
is_swiotlb_active
swiotlb_create_debugfs
   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 
  64 enum 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  */
  71 phys_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  */
  77 static unsigned long io_tlb_nslabs;
  78 
  79 /*
  80  * The number of used IO TLB block
  81  */
  82 static 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  */
  88 static unsigned int *io_tlb_list;
  89 static 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  */
  95 unsigned 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)
 102 static phys_addr_t *io_tlb_orig_addr;
 103 
 104 /*
 105  * Protect the above data structures in the map and unmap calls
 106  */
 107 static DEFINE_SPINLOCK(io_tlb_lock);
 108 
 109 static int late_alloc;
 110 
 111 static int __init
 112 setup_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 }
 130 early_param("swiotlb", setup_io_tlb_npages);
 131 
 132 static bool no_iotlb_memory;
 133 
 134 unsigned long swiotlb_nr_tbl(void)
 135 {
 136         return unlikely(no_iotlb_memory) ? 0 : io_tlb_nslabs;
 137 }
 138 EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
 139 
 140 unsigned int swiotlb_max_segment(void)
 141 {
 142         return unlikely(no_iotlb_memory) ? 0 : max_segment;
 143 }
 144 EXPORT_SYMBOL_GPL(swiotlb_max_segment);
 145 
 146 void 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)
 156 unsigned 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 
 165 void 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  */
 186 void __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 
 200 int __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  */
 245 void  __init
 246 swiotlb_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  */
 276 int
 277 swiotlb_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 
 320 static 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 
 328 int
 329 swiotlb_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 
 373 cleanup4:
 374         free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
 375                                                          sizeof(int)));
 376         io_tlb_list = NULL;
 377 cleanup3:
 378         swiotlb_cleanup();
 379         return -ENOMEM;
 380 }
 381 
 382 void __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  */
 408 static 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 
 445 phys_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 
 551 not_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;
 559 found:
 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  */
 580 void 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 
 627 void 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  */
 662 bool 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 
 690 size_t swiotlb_max_mapping_size(struct device *dev)
 691 {
 692         return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
 693 }
 694 
 695 bool 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 
 706 static 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 
 716 late_initcall(swiotlb_create_debugfs);
 717 
 718 #endif
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root/kernel/dma/swiotlb.c

DEFINITIONS
