sys/platform/vkernel64/platform/busdma_machdep.c

   1 /*
   2  * Copyright (c) 1997, 1998 Justin T. Gibbs.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions, and the following disclaimer,
  10  *    without modification, immediately at the beginning of the file.
  11  * 2. The name of the author may not be used to endorse or promote products
  12  *    derived from this software without specific prior written permission.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
  18  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/i386/i386/busdma_machdep.c,v 1.94 2008/08/15 20:51:31 kmacy Exp $
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/systm.h>
  31 #include <sys/malloc.h>
  32 #include <sys/mbuf.h>
  33 #include <sys/uio.h>
  34 #include <sys/thread2.h>
  35 #include <sys/bus_dma.h>
  36 #include <sys/kernel.h>
  37 #include <sys/sysctl.h>
  38 #include <sys/lock.h>
  39 #include <sys/spinlock2.h>
  40
  41 #include <vm/vm.h>
  42 #include <vm/vm_page.h>
  43
  44 /* XXX needed for to access pmap to convert per-proc virtual to physical */
  45 #include <sys/proc.h>
  46 #include <sys/lock.h>
  47 #include <vm/vm_map.h>
  48
  49 #include <machine/md_var.h>
  50
  51 #define MAX_BPAGES      1024
  52
  53 struct bounce_zone;
  54 struct bus_dmamap;
  55
  56 struct bus_dma_tag {
  57         bus_dma_tag_t   parent;
  58         bus_size_t      alignment;
  59         bus_size_t      boundary;
  60         bus_addr_t      lowaddr;
  61         bus_addr_t      highaddr;
  62         bus_dma_filter_t *filter;
  63         void            *filterarg;
  64         bus_size_t      maxsize;
  65         u_int           nsegments;
  66         bus_size_t      maxsegsz;
  67         int             flags;
  68         int             ref_count;
  69         int             map_count;
  70         bus_dma_segment_t *segments;
  71         struct bounce_zone *bounce_zone;
  72 };
  73
  74 /*
  75  * bus_dma_tag private flags
  76  */
  77 #define BUS_DMA_BOUNCE_ALIGN    BUS_DMA_BUS2
  78 #define BUS_DMA_BOUNCE_LOWADDR  BUS_DMA_BUS3
  79 #define BUS_DMA_MIN_ALLOC_COMP  BUS_DMA_BUS4
  80
  81 #define BUS_DMA_COULD_BOUNCE    (BUS_DMA_BOUNCE_LOWADDR | BUS_DMA_BOUNCE_ALIGN)
  82
  83 #define BUS_DMAMEM_KMALLOC(dmat) \
  84         ((dmat)->maxsize <= PAGE_SIZE && \
  85          (dmat)->alignment <= PAGE_SIZE && \
  86          (dmat)->lowaddr >= ptoa(Maxmem))
  87
  88 struct bounce_page {
  89         vm_offset_t     vaddr;          /* kva of bounce buffer */
  90         bus_addr_t      busaddr;        /* Physical address */
  91         vm_offset_t     datavaddr;      /* kva of client data */
  92         bus_size_t      datacount;      /* client data count */
  93         STAILQ_ENTRY(bounce_page) links;
  94 };
  95
  96 struct bounce_zone {
  97         STAILQ_ENTRY(bounce_zone) links;
  98         STAILQ_HEAD(bp_list, bounce_page) bounce_page_list;
  99         STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
 100 #ifdef SMP
 101         struct spinlock spin;
 102 #else
 103         int             unused0;
 104 #endif
 105         int             total_bpages;
 106         int             free_bpages;
 107         int             reserved_bpages;
 108         int             active_bpages;
 109         int             total_bounced;
 110         int             total_deferred;
 111         int             reserve_failed;
 112         bus_size_t      alignment;
 113         bus_addr_t      lowaddr;
 114         char            zoneid[8];
 115         char            lowaddrid[20];
 116         struct sysctl_ctx_list sysctl_ctx;
 117         struct sysctl_oid *sysctl_tree;
 118 };
 119
 120 #ifdef SMP
 121 #define BZ_LOCK(bz)     spin_lock(&(bz)->spin)
 122 #define BZ_UNLOCK(bz)   spin_unlock(&(bz)->spin)
 123 #else
 124 #define BZ_LOCK(bz)     crit_enter()
 125 #define BZ_UNLOCK(bz)   crit_exit()
 126 #endif
 127
 128 static struct lwkt_token bounce_zone_tok =
 129         LWKT_TOKEN_INITIALIZER(bounce_zone_token);
 130 static int busdma_zonecount;
 131 static STAILQ_HEAD(, bounce_zone) bounce_zone_list =
 132         STAILQ_HEAD_INITIALIZER(bounce_zone_list);
 133
 134 int busdma_swi_pending;
 135 static int total_bounce_pages;
 136 static int max_bounce_pages = MAX_BPAGES;
 137 static int bounce_alignment = 1; /* XXX temporary */
 138
 139 TUNABLE_INT("hw.busdma.max_bpages", &max_bounce_pages);
 140 TUNABLE_INT("hw.busdma.bounce_alignment", &bounce_alignment);
 141
 142 struct bus_dmamap {
 143         struct bp_list  bpages;
 144         int             pagesneeded;
 145         int             pagesreserved;
 146         bus_dma_tag_t   dmat;
 147         void            *buf;           /* unmapped buffer pointer */
 148         bus_size_t      buflen;         /* unmapped buffer length */
 149         bus_dmamap_callback_t *callback;
 150         void            *callback_arg;
 151         STAILQ_ENTRY(bus_dmamap) links;
 152 };
 153
 154 static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist =
 155         STAILQ_HEAD_INITIALIZER(bounce_map_callbacklist);
 156
 157 static struct bus_dmamap nobounce_dmamap;
 158
 159 static int              alloc_bounce_zone(bus_dma_tag_t);
 160 static int              alloc_bounce_pages(bus_dma_tag_t, u_int, int);
 161 static int              reserve_bounce_pages(bus_dma_tag_t, bus_dmamap_t, int);
 162 static void             return_bounce_pages(bus_dma_tag_t, bus_dmamap_t);
 163 static bus_addr_t       add_bounce_page(bus_dma_tag_t, bus_dmamap_t,
 164                             vm_offset_t, bus_size_t);
 165 static void             free_bounce_page(bus_dma_tag_t, struct bounce_page *);
 166
 167 static bus_dmamap_t     get_map_waiting(bus_dma_tag_t);
 168 static void             add_map_callback(bus_dmamap_t);
 169
 170 SYSCTL_NODE(_hw, OID_AUTO, busdma, CTLFLAG_RD, 0, "Busdma parameters");
 171 SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bounce_pages,
 172            0, "Total bounce pages");
 173 SYSCTL_INT(_hw_busdma, OID_AUTO, max_bpages, CTLFLAG_RD, &max_bounce_pages,
 174            0, "Max bounce pages per bounce zone");
 175 SYSCTL_INT(_hw_busdma, OID_AUTO, bounce_alignment, CTLFLAG_RD,
 176            &bounce_alignment, 0, "Obey alignment constraint");
 177
 178 static __inline int
 179 run_filter(bus_dma_tag_t dmat, bus_addr_t paddr)
 180 {
 181         int retval;
 182
 183         retval = 0;
 184         do {
 185                 if (((paddr > dmat->lowaddr && paddr <= dmat->highaddr) ||
 186                      (bounce_alignment && (paddr & (dmat->alignment - 1)) != 0))
 187                  && (dmat->filter == NULL ||
 188                      dmat->filter(dmat->filterarg, paddr) != 0))
 189                         retval = 1;
 190
 191                 dmat = dmat->parent;
 192         } while (retval == 0 && dmat != NULL);
 193         return (retval);
 194 }
 195
 196 /*
 197  * Allocate a device specific dma_tag.
 198  */
 199 int
 200 bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 201                    bus_size_t boundary, bus_addr_t lowaddr,
 202                    bus_addr_t highaddr, bus_dma_filter_t *filter,
 203                    void *filterarg, bus_size_t maxsize, int nsegments,
 204                    bus_size_t maxsegsz, int flags, bus_dma_tag_t *dmat)
 205 {
 206         bus_dma_tag_t newtag;
 207         int error = 0;
 208
 209         /*
 210          * Sanity checks
 211          */
 212
 213         if (alignment == 0)
 214                 alignment = 1;
 215         if (alignment & (alignment - 1))
 216                 panic("alignment must be power of 2");
 217
 218         if (boundary != 0) {
 219                 if (boundary & (boundary - 1))
 220                         panic("boundary must be power of 2");
 221                 if (boundary < maxsegsz) {
 222                         kprintf("boundary < maxsegsz:\n");
 223                         print_backtrace(-1);
 224                         maxsegsz = boundary;
 225                 }
 226         }
 227
 228         /* Return a NULL tag on failure */
 229         *dmat = NULL;
 230
 231         newtag = kmalloc(sizeof(*newtag), M_DEVBUF, M_INTWAIT);
 232
 233         newtag->parent = parent;
 234         newtag->alignment = alignment;
 235         newtag->boundary = boundary;
 236         newtag->lowaddr = trunc_page((vm_paddr_t)lowaddr) + (PAGE_SIZE - 1);
 237         newtag->highaddr = trunc_page((vm_paddr_t)highaddr) + (PAGE_SIZE - 1);
 238         newtag->filter = filter;
 239         newtag->filterarg = filterarg;
 240         newtag->maxsize = maxsize;
 241         newtag->nsegments = nsegments;
 242         newtag->maxsegsz = maxsegsz;
 243         newtag->flags = flags;
 244         newtag->ref_count = 1; /* Count ourself */
 245         newtag->map_count = 0;
 246         newtag->segments = NULL;
 247         newtag->bounce_zone = NULL;
 248
 249         /* Take into account any restrictions imposed by our parent tag */
 250         if (parent != NULL) {
 251                 newtag->lowaddr = MIN(parent->lowaddr, newtag->lowaddr);
 252                 newtag->highaddr = MAX(parent->highaddr, newtag->highaddr);
 253
 254                 if (newtag->boundary == 0) {
 255                         newtag->boundary = parent->boundary;
 256                 } else if (parent->boundary != 0) {
 257                         newtag->boundary = MIN(parent->boundary,
 258                                                newtag->boundary);
 259                 }
 260
 261 #ifdef notyet
 262                 newtag->alignment = MAX(parent->alignment, newtag->alignment);
 263 #endif
 264
 265                 if (newtag->filter == NULL) {
 266                         /*
 267                          * Short circuit looking at our parent directly
 268                          * since we have encapsulated all of its information
 269                          */
 270                         newtag->filter = parent->filter;
 271                         newtag->filterarg = parent->filterarg;
 272                         newtag->parent = parent->parent;
 273                 }
 274                 if (newtag->parent != NULL)
 275                         parent->ref_count++;
 276         }
 277
 278         if (newtag->lowaddr < ptoa(Maxmem))
 279                 newtag->flags |= BUS_DMA_BOUNCE_LOWADDR;
 280         if (bounce_alignment && newtag->alignment > 1 &&
 281             !(newtag->flags & BUS_DMA_ALIGNED))
 282                 newtag->flags |= BUS_DMA_BOUNCE_ALIGN;
 283
 284         if ((newtag->flags & BUS_DMA_COULD_BOUNCE) &&
 285             (flags & BUS_DMA_ALLOCNOW) != 0) {
 286                 struct bounce_zone *bz;
 287
 288                 /* Must bounce */
 289
 290                 error = alloc_bounce_zone(newtag);
 291                 if (error)
 292                         goto back;
 293                 bz = newtag->bounce_zone;
 294
 295                 if (ptoa(bz->total_bpages) < maxsize) {
 296                         int pages;
 297
 298                         if (flags & BUS_DMA_ONEBPAGE) {
 299                                 pages = 1;
 300                         } else {
 301                                 pages = atop(round_page(maxsize)) -
 302                                         bz->total_bpages;
 303                                 pages = MAX(pages, 1);
 304                         }
 305
 306                         /* Add pages to our bounce pool */
 307                         if (alloc_bounce_pages(newtag, pages, flags) < pages)
 308                                 error = ENOMEM;
 309
 310                         /* Performed initial allocation */
 311                         newtag->flags |= BUS_DMA_MIN_ALLOC_COMP;
 312                 }
 313         }
 314 back:
 315         if (error)
 316                 kfree(newtag, M_DEVBUF);
 317         else
 318                 *dmat = newtag;
 319         return error;
 320 }
 321
 322 int
 323 bus_dma_tag_destroy(bus_dma_tag_t dmat)
 324 {
 325         if (dmat != NULL) {
 326                 if (dmat->map_count != 0)
 327                         return (EBUSY);
 328
 329                 while (dmat != NULL) {
 330                         bus_dma_tag_t parent;
 331
 332                         parent = dmat->parent;
 333                         dmat->ref_count--;
 334                         if (dmat->ref_count == 0) {
 335                                 if (dmat->segments != NULL)
 336                                         kfree(dmat->segments, M_DEVBUF);
 337                                 kfree(dmat, M_DEVBUF);
 338                                 /*
 339                                  * Last reference count, so
 340                                  * release our reference
 341                                  * count on our parent.
 342                                  */
 343                                 dmat = parent;
 344                         } else
 345                                 dmat = NULL;
 346                 }
 347         }
 348         return (0);
 349 }
 350
 351 /*
 352  * Allocate a handle for mapping from kva/uva/physical
 353  * address space into bus device space.
 354  */
 355 int
 356 bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
 357 {
 358         int error;
 359
 360         error = 0;
 361
 362         if (dmat->segments == NULL) {
 363                 KKASSERT(dmat->nsegments && dmat->nsegments < 16384);
 364                 dmat->segments = kmalloc(sizeof(bus_dma_segment_t) *
 365                                         dmat->nsegments, M_DEVBUF, M_INTWAIT);
 366         }
 367
 368         if (dmat->flags & BUS_DMA_COULD_BOUNCE) {
 369                 struct bounce_zone *bz;
 370                 int maxpages;
 371
 372                 /* Must bounce */
 373
 374                 if (dmat->bounce_zone == NULL) {
 375                         error = alloc_bounce_zone(dmat);
 376                         if (error)
 377                                 return error;
 378                 }
 379                 bz = dmat->bounce_zone;
 380
 381                 *mapp = kmalloc(sizeof(**mapp), M_DEVBUF, M_INTWAIT | M_ZERO);
 382
 383                 /* Initialize the new map */
 384                 STAILQ_INIT(&((*mapp)->bpages));
 385
 386                 /*
 387                  * Attempt to add pages to our pool on a per-instance
 388                  * basis up to a sane limit.
 389                  */
 390                 if (dmat->flags & BUS_DMA_BOUNCE_ALIGN) {
 391                         maxpages = max_bounce_pages;
 392                 } else {
 393                         maxpages = MIN(max_bounce_pages,
 394                                        Maxmem - atop(dmat->lowaddr));
 395                 }
 396                 if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
 397                  || (dmat->map_count > 0
 398                   && bz->total_bpages < maxpages)) {
 399                         int pages;
 400
 401                         if (flags & BUS_DMA_ONEBPAGE) {
 402                                 pages = 1;
 403                         } else {
 404                                 pages = atop(round_page(dmat->maxsize));
 405                                 pages = MIN(maxpages - bz->total_bpages, pages);
 406                                 pages = MAX(pages, 1);
 407                         }
 408                         if (alloc_bounce_pages(dmat, pages, flags) < pages)
 409                                 error = ENOMEM;
 410
 411                         if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0) {
 412                                 if (!error)
 413                                         dmat->flags |= BUS_DMA_MIN_ALLOC_COMP;
 414                         } else {
 415                                 error = 0;
 416                         }
 417                 }
 418         } else {
 419                 *mapp = NULL;
 420         }
 421         if (!error)
 422                 dmat->map_count++;
 423         return error;
 424 }
 425
 426 /*
 427  * Destroy a handle for mapping from kva/uva/physical
 428  * address space into bus device space.
 429  */
 430 int
 431 bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
 432 {
 433         if (map != NULL) {
 434                 if (STAILQ_FIRST(&map->bpages) != NULL)
 435                         return (EBUSY);
 436                 kfree(map, M_DEVBUF);
 437         }
 438         dmat->map_count--;
 439         return (0);
 440 }
 441
 442 static __inline bus_size_t
 443 check_kmalloc(bus_dma_tag_t dmat, const void *vaddr0, int verify)
 444 {
 445         bus_size_t maxsize = 0;
 446         uintptr_t vaddr = (uintptr_t)vaddr0;
 447
 448         if ((vaddr ^ (vaddr + dmat->maxsize - 1)) & ~PAGE_MASK) {
 449                 kprintf("boundary check failed\n");
 450                 if (verify)
 451                         print_backtrace(-1); /* XXX panic */
 452                 maxsize = dmat->maxsize;
 453         }
 454         if (vaddr & (dmat->alignment - 1)) {
 455                 kprintf("alignment check failed\n");
 456                 if (verify)
 457                         print_backtrace(-1); /* XXX panic */
 458                 if (dmat->maxsize < dmat->alignment)
 459                         maxsize = dmat->alignment;
 460                 else
 461                         maxsize = dmat->maxsize;
 462         }
 463         return maxsize;
 464 }
 465
 466 /*
 467  * Allocate a piece of memory that can be efficiently mapped into
 468  * bus device space based on the constraints lited in the dma tag.
 469  *
 470  * mapp is degenerate.  By definition this allocation should not require
 471  * bounce buffers so do not allocate a dma map.
 472  */
 473 int
 474 bus_dmamem_alloc(bus_dma_tag_t dmat, void **vaddr, int flags,
 475                  bus_dmamap_t *mapp)
 476 {
 477         int mflags;
 478
 479         /* If we succeed, no mapping/bouncing will be required */
 480         *mapp = NULL;
 481
 482         if (dmat->segments == NULL) {
 483                 KKASSERT(dmat->nsegments < 16384);
 484                 dmat->segments = kmalloc(sizeof(bus_dma_segment_t) *
 485                                         dmat->nsegments, M_DEVBUF, M_INTWAIT);
 486         }
 487
 488         if (flags & BUS_DMA_NOWAIT)
 489                 mflags = M_NOWAIT;
 490         else
 491                 mflags = M_WAITOK;
 492         if (flags & BUS_DMA_ZERO)
 493                 mflags |= M_ZERO;
 494
 495         if (BUS_DMAMEM_KMALLOC(dmat)) {
 496                 bus_size_t maxsize;
 497
 498                 *vaddr = kmalloc(dmat->maxsize, M_DEVBUF, mflags);
 499
 500                 /*
 501                  * XXX
 502                  * Check whether the allocation
 503                  * - crossed a page boundary
 504                  * - was not aligned
 505                  * Retry with power-of-2 alignment in the above cases.
 506                  */
 507                 maxsize = check_kmalloc(dmat, *vaddr, 0);
 508                 if (maxsize) {
 509                         size_t size;
 510
 511                         kfree(*vaddr, M_DEVBUF);
 512                         /* XXX check for overflow? */
 513                         for (size = 1; size <= maxsize; size <<= 1)
 514                                 ;
 515                         *vaddr = kmalloc(size, M_DEVBUF, mflags);
 516                         check_kmalloc(dmat, *vaddr, 1);
 517                 }
 518         } else {
 519                 /*
 520                  * XXX Use Contigmalloc until it is merged into this facility
 521                  *     and handles multi-seg allocations.  Nobody is doing
 522                  *     multi-seg allocations yet though.
 523                  */
 524                 *vaddr = contigmalloc(dmat->maxsize, M_DEVBUF, mflags,
 525                     0ul, dmat->lowaddr, dmat->alignment, dmat->boundary);
 526         }
 527         if (*vaddr == NULL)
 528                 return (ENOMEM);
 529         return (0);
 530 }
 531
 532 /*
 533  * Free a piece of memory and it's allociated dmamap, that was allocated
 534  * via bus_dmamem_alloc.  Make the same choice for free/contigfree.
 535  */
 536 void
 537 bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
 538 {
 539         /*
 540          * dmamem does not need to be bounced, so the map should be
 541          * NULL
 542          */
 543         if (map != NULL)
 544                 panic("bus_dmamem_free: Invalid map freed");
 545         if (BUS_DMAMEM_KMALLOC(dmat))
 546                 kfree(vaddr, M_DEVBUF);
 547         else
 548                 contigfree(vaddr, dmat->maxsize, M_DEVBUF);
 549 }
 550
 551 static __inline vm_paddr_t
 552 _bus_dma_extract(pmap_t pmap, vm_offset_t vaddr)
 553 {
 554         if (pmap)
 555                 return pmap_extract(pmap, vaddr);
 556         else
 557                 return pmap_kextract(vaddr);
 558 }
 559
 560 /*
 561  * Utility function to load a linear buffer.  lastaddrp holds state
 562  * between invocations (for multiple-buffer loads).  segp contains
 563  * the segment following the starting one on entrace, and the ending
 564  * segment on exit.  first indicates if this is the first invocation
 565  * of this function.
 566  */
 567 static int
 568 _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
 569                         bus_dmamap_t map,
 570                         void *buf, bus_size_t buflen,
 571                         bus_dma_segment_t *segments,
 572                         int nsegments,
 573                         pmap_t pmap,
 574                         int flags,
 575                         vm_paddr_t *lastpaddrp,
 576                         int *segp,
 577                         int first)
 578 {
 579         vm_offset_t vaddr;
 580         vm_paddr_t paddr, nextpaddr;
 581         bus_dma_segment_t *sg;
 582         bus_addr_t bmask;
 583         int seg, error = 0;
 584
 585         if (map == NULL)
 586                 map = &nobounce_dmamap;
 587
 588 #ifdef INVARIANTS
 589         if (dmat->flags & BUS_DMA_ALIGNED)
 590                 KKASSERT(((uintptr_t)buf & (dmat->alignment - 1)) == 0);
 591 #endif
 592
 593         /*
 594          * If we are being called during a callback, pagesneeded will
 595          * be non-zero, so we can avoid doing the work twice.
 596          */
 597         if ((dmat->flags & BUS_DMA_COULD_BOUNCE) &&
 598             map != &nobounce_dmamap && map->pagesneeded == 0) {
 599                 vm_offset_t vendaddr;
 600
 601                 /*
 602                  * Count the number of bounce pages
 603                  * needed in order to complete this transfer
 604                  */
 605                 vaddr = (vm_offset_t)buf;
 606                 vendaddr = (vm_offset_t)buf + buflen;
 607
 608                 while (vaddr < vendaddr) {
 609                         paddr = _bus_dma_extract(pmap, vaddr);
 610                         if (run_filter(dmat, paddr) != 0)
 611                                 map->pagesneeded++;
 612                         vaddr += (PAGE_SIZE - (vaddr & PAGE_MASK));
 613                 }
 614         }
 615
 616         /* Reserve Necessary Bounce Pages */
 617         if (map->pagesneeded != 0) {
 618                 struct bounce_zone *bz;
 619
 620                 bz = dmat->bounce_zone;
 621                 BZ_LOCK(bz);
 622                 if (flags & BUS_DMA_NOWAIT) {
 623                         if (reserve_bounce_pages(dmat, map, 0) != 0) {
 624                                 BZ_UNLOCK(bz);
 625                                 error = ENOMEM;
 626                                 goto free_bounce;
 627                         }
 628                 } else {
 629                         if (reserve_bounce_pages(dmat, map, 1) != 0) {
 630                                 /* Queue us for resources */
 631                                 map->dmat = dmat;
 632                                 map->buf = buf;
 633                                 map->buflen = buflen;
 634
 635                                 STAILQ_INSERT_TAIL(
 636                                     &dmat->bounce_zone->bounce_map_waitinglist,
 637                                     map, links);
 638                                 BZ_UNLOCK(bz);
 639
 640                                 return (EINPROGRESS);
 641                         }
 642                 }
 643                 BZ_UNLOCK(bz);
 644         }
 645
 646         KKASSERT(*segp >= 1 && *segp <= nsegments);
 647         seg = *segp;
 648         sg = &segments[seg - 1];
 649
 650         vaddr = (vm_offset_t)buf;
 651         nextpaddr = *lastpaddrp;
 652         bmask = ~(dmat->boundary - 1);  /* note: will be 0 if boundary is 0 */
 653
 654         /* force at least one segment */
 655         do {
 656                 bus_size_t size;
 657
 658                 /*
 659                  * Per-page main loop
 660                  */
 661                 paddr = _bus_dma_extract(pmap, vaddr);
 662                 size = PAGE_SIZE - (paddr & PAGE_MASK);
 663                 if (size > buflen)
 664                         size = buflen;
 665                 if (map->pagesneeded != 0 && run_filter(dmat, paddr)) {
 666                         /*
 667                          * note: this paddr has the same in-page offset
 668                          * as vaddr and thus the paddr above, so the
 669                          * size does not have to be recalculated
 670                          */
 671                         paddr = add_bounce_page(dmat, map, vaddr, size);
 672                 }
 673
 674                 /*
 675                  * Fill in the bus_dma_segment
 676                  */
 677                 if (first) {
 678                         sg->ds_addr = paddr;
 679                         sg->ds_len = size;
 680                         first = 0;
 681                 } else if (paddr == nextpaddr) {
 682                         sg->ds_len += size;
 683                 } else {
 684                         sg++;
 685                         seg++;
 686                         if (seg > nsegments)
 687                                 break;
 688                         sg->ds_addr = paddr;
 689                         sg->ds_len = size;
 690                 }
 691                 nextpaddr = paddr + size;
 692
 693                 /*
 694                  * Handle maxsegsz and boundary issues with a nested loop
 695                  */
 696                 for (;;) {
 697                         bus_size_t tmpsize;
 698
 699                         /*
 700                          * Limit to the boundary and maximum segment size
 701                          */
 702                         if (((nextpaddr - 1) ^ sg->ds_addr) & bmask) {
 703                                 tmpsize = dmat->boundary -
 704                                           (sg->ds_addr & ~bmask);
 705                                 if (tmpsize > dmat->maxsegsz)
 706                                         tmpsize = dmat->maxsegsz;
 707                                 KKASSERT(tmpsize < sg->ds_len);
 708                         } else if (sg->ds_len > dmat->maxsegsz) {
 709                                 tmpsize = dmat->maxsegsz;
 710                         } else {
 711                                 break;
 712                         }
 713
 714                         /*
 715                          * Futz, split the data into a new segment.
 716                          */
 717                         if (seg >= nsegments)
 718                                 goto fail;
 719                         sg[1].ds_len = sg[0].ds_len - tmpsize;
 720                         sg[1].ds_addr = sg[0].ds_addr + tmpsize;
 721                         sg[0].ds_len = tmpsize;
 722                         sg++;
 723                         seg++;
 724                 }
 725
 726                 /*
 727                  * Adjust for loop
 728                  */
 729                 buflen -= size;
 730                 vaddr += size;
 731         } while (buflen > 0);
 732 fail:
 733         if (buflen != 0)
 734                 error = EFBIG;
 735
 736         *segp = seg;
 737         *lastpaddrp = nextpaddr;
 738
 739 free_bounce:
 740         if (error && (dmat->flags & BUS_DMA_COULD_BOUNCE) &&
 741             map != &nobounce_dmamap) {
 742                 _bus_dmamap_unload(dmat, map);
 743                 return_bounce_pages(dmat, map);
 744         }
 745         return error;
 746 }
 747
 748 /*
 749  * Map the buffer buf into bus space using the dmamap map.
 750  */
 751 int
 752 bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
 753                 bus_size_t buflen, bus_dmamap_callback_t *callback,
 754                 void *callback_arg, int flags)
 755 {
 756         vm_paddr_t lastaddr = 0;
 757         int error, nsegs = 1;
 758
 759         if (map != NULL) {
 760                 /*
 761                  * XXX
 762                  * Follow old semantics.  Once all of the callers are fixed,
 763                  * we should get rid of these internal flag "adjustment".
 764                  */
 765                 flags &= ~BUS_DMA_NOWAIT;
 766                 flags |= BUS_DMA_WAITOK;
 767
 768                 map->callback = callback;
 769                 map->callback_arg = callback_arg;
 770         }
 771
 772         error = _bus_dmamap_load_buffer(dmat, map, buf, buflen,
 773                         dmat->segments, dmat->nsegments,
 774                         NULL, flags, &lastaddr, &nsegs, 1);
 775         if (error == EINPROGRESS)
 776                 return error;
 777
 778         callback(callback_arg, dmat->segments, nsegs, error);
 779         return 0;
 780 }
 781
 782 /*
 783  * Like _bus_dmamap_load(), but for mbufs.
 784  */
 785 int
 786 bus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map,
 787                      struct mbuf *m0,
 788                      bus_dmamap_callback2_t *callback, void *callback_arg,
 789                      int flags)
 790 {
 791         int nsegs, error;
 792
 793         /*
 794          * XXX
 795          * Follow old semantics.  Once all of the callers are fixed,
 796          * we should get rid of these internal flag "adjustment".
 797          */
 798         flags &= ~BUS_DMA_WAITOK;
 799         flags |= BUS_DMA_NOWAIT;
 800
 801         error = bus_dmamap_load_mbuf_segment(dmat, map, m0,
 802                         dmat->segments, dmat->nsegments, &nsegs, flags);
 803         if (error) {
 804                 /* force "no valid mappings" in callback */
 805                 callback(callback_arg, dmat->segments, 0, 0, error);
 806         } else {
 807                 callback(callback_arg, dmat->segments, nsegs,
 808                          m0->m_pkthdr.len, error);
 809         }
 810         return error;
 811 }
 812
 813 int
 814 bus_dmamap_load_mbuf_segment(bus_dma_tag_t dmat, bus_dmamap_t map,
 815                              struct mbuf *m0,
 816                              bus_dma_segment_t *segs, int maxsegs,
 817                              int *nsegs, int flags)
 818 {
 819         int error;
 820
 821         M_ASSERTPKTHDR(m0);
 822
 823         KASSERT(maxsegs >= 1, ("invalid maxsegs %d", maxsegs));
 824         KASSERT(maxsegs <= dmat->nsegments,
 825                 ("%d too many segments, dmat only supports %d segments",
 826                  maxsegs, dmat->nsegments));
 827         KASSERT(flags & BUS_DMA_NOWAIT,
 828                 ("only BUS_DMA_NOWAIT is supported"));
 829
 830         if (m0->m_pkthdr.len <= dmat->maxsize) {
 831                 int first = 1;
 832                 vm_paddr_t lastaddr = 0;
 833                 struct mbuf *m;
 834
 835                 *nsegs = 1;
 836                 error = 0;
 837                 for (m = m0; m != NULL && error == 0; m = m->m_next) {
 838                         if (m->m_len == 0)
 839                                 continue;
 840
 841                         error = _bus_dmamap_load_buffer(dmat, map,
 842                                         m->m_data, m->m_len,
 843                                         segs, maxsegs,
 844                                         NULL, flags, &lastaddr,
 845                                         nsegs, first);
 846                         if (error == ENOMEM && !first) {
 847                                 /*
 848                                  * Out of bounce pages due to too many
 849                                  * fragments in the mbuf chain; return
 850                                  * EFBIG instead.
 851                                  */
 852                                 error = EFBIG;
 853                         }
 854                         first = 0;
 855                 }
 856 #ifdef INVARIANTS
 857                 if (!error)
 858                         KKASSERT(*nsegs <= maxsegs && *nsegs >= 1);
 859 #endif
 860         } else {
 861                 *nsegs = 0;
 862                 error = EINVAL;
 863         }
 864         KKASSERT(error != EINPROGRESS);
 865         return error;
 866 }
 867
 868 /*
 869  * Like _bus_dmamap_load(), but for uios.
 870  */
 871 int
 872 bus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map,
 873                     struct uio *uio,
 874                     bus_dmamap_callback2_t *callback, void *callback_arg,
 875                     int flags)
 876 {
 877         vm_paddr_t lastaddr;
 878         int nsegs, error, first, i;
 879         bus_size_t resid;
 880         struct iovec *iov;
 881         pmap_t pmap;
 882
 883         /*
 884          * XXX
 885          * Follow old semantics.  Once all of the callers are fixed,
 886          * we should get rid of these internal flag "adjustment".
 887          */
 888         flags &= ~BUS_DMA_WAITOK;
 889         flags |= BUS_DMA_NOWAIT;
 890
 891         resid = (bus_size_t)uio->uio_resid;
 892         iov = uio->uio_iov;
 893
 894         if (uio->uio_segflg == UIO_USERSPACE) {
 895                 struct thread *td;
 896
 897                 td = uio->uio_td;
 898                 KASSERT(td != NULL && td->td_proc != NULL,
 899                         ("bus_dmamap_load_uio: USERSPACE but no proc"));
 900                 pmap = vmspace_pmap(td->td_proc->p_vmspace);
 901         } else {
 902                 pmap = NULL;
 903         }
 904
 905         error = 0;
 906         nsegs = 1;
 907         first = 1;
 908         lastaddr = 0;
 909         for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
 910                 /*
 911                  * Now at the first iovec to load.  Load each iovec
 912                  * until we have exhausted the residual count.
 913                  */
 914                 bus_size_t minlen =
 915                         resid < iov[i].iov_len ? resid : iov[i].iov_len;
 916                 caddr_t addr = (caddr_t) iov[i].iov_base;
 917
 918                 error = _bus_dmamap_load_buffer(dmat, map, addr, minlen,
 919                                 dmat->segments, dmat->nsegments,
 920                                 pmap, flags, &lastaddr, &nsegs, first);
 921                 first = 0;
 922
 923                 resid -= minlen;
 924         }
 925
 926         if (error) {
 927                 /* force "no valid mappings" in callback */
 928                 callback(callback_arg, dmat->segments, 0, 0, error);
 929         } else {
 930                 callback(callback_arg, dmat->segments, nsegs,
 931                          (bus_size_t)uio->uio_resid, error);
 932         }
 933         return error;
 934 }
 935
 936 /*
 937  * Release the mapping held by map.
 938  */
 939 void
 940 _bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
 941 {
 942         struct bounce_page *bpage;
 943
 944         while ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
 945                 STAILQ_REMOVE_HEAD(&map->bpages, links);
 946                 free_bounce_page(dmat, bpage);
 947         }
 948 }
 949
 950 void
 951 _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
 952 {
 953         struct bounce_page *bpage;
 954
 955         if ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
 956                 /*
 957                  * Handle data bouncing.  We might also
 958                  * want to add support for invalidating
 959                  * the caches on broken hardware
 960                  */
 961                 switch (op) {
 962                 case BUS_DMASYNC_PREWRITE:
 963                         while (bpage != NULL) {
 964                                 bcopy((void *)bpage->datavaddr,
 965                                       (void *)bpage->vaddr,
 966                                       bpage->datacount);
 967                                 bpage = STAILQ_NEXT(bpage, links);
 968                         }
 969                         dmat->bounce_zone->total_bounced++;
 970                         break;
 971
 972                 case BUS_DMASYNC_POSTREAD:
 973                         while (bpage != NULL) {
 974                                 bcopy((void *)bpage->vaddr,
 975                                       (void *)bpage->datavaddr,
 976                                       bpage->datacount);
 977                                 bpage = STAILQ_NEXT(bpage, links);
 978                         }
 979                         dmat->bounce_zone->total_bounced++;
 980                         break;
 981
 982                 case BUS_DMASYNC_PREREAD:
 983                 case BUS_DMASYNC_POSTWRITE:
 984                         /* No-ops */
 985                         break;
 986                 }
 987         }
 988 }
 989
 990 static int
 991 alloc_bounce_zone(bus_dma_tag_t dmat)
 992 {
 993         struct bounce_zone *bz, *new_bz;
 994
 995         KASSERT(dmat->bounce_zone == NULL,
 996                 ("bounce zone was already assigned"));
 997
 998         new_bz = kmalloc(sizeof(*new_bz), M_DEVBUF, M_INTWAIT | M_ZERO);
 999
1000         lwkt_gettoken(&bounce_zone_tok);
1001
1002         /* Check to see if we already have a suitable zone */
1003         STAILQ_FOREACH(bz, &bounce_zone_list, links) {
1004                 if (dmat->alignment <= bz->alignment &&
1005                     dmat->lowaddr >= bz->lowaddr) {
1006                         lwkt_reltoken(&bounce_zone_tok);
1007
1008                         dmat->bounce_zone = bz;
1009                         kfree(new_bz, M_DEVBUF);
1010                         return 0;
1011                 }
1012         }
1013         bz = new_bz;
1014
1015 #ifdef SMP
1016         spin_init(&bz->spin);
1017 #endif
1018         STAILQ_INIT(&bz->bounce_page_list);
1019         STAILQ_INIT(&bz->bounce_map_waitinglist);
1020         bz->free_bpages = 0;
1021         bz->reserved_bpages = 0;
1022         bz->active_bpages = 0;
1023         bz->lowaddr = dmat->lowaddr;
1024         bz->alignment = round_page(dmat->alignment);
1025         ksnprintf(bz->zoneid, 8, "zone%d", busdma_zonecount);
1026         busdma_zonecount++;
1027         ksnprintf(bz->lowaddrid, 18, "%#jx", (uintmax_t)bz->lowaddr);
1028         STAILQ_INSERT_TAIL(&bounce_zone_list, bz, links);
1029
1030         lwkt_reltoken(&bounce_zone_tok);
1031
1032         dmat->bounce_zone = bz;
1033
1034         sysctl_ctx_init(&bz->sysctl_ctx);
1035         bz->sysctl_tree = SYSCTL_ADD_NODE(&bz->sysctl_ctx,
1036             SYSCTL_STATIC_CHILDREN(_hw_busdma), OID_AUTO, bz->zoneid,
1037             CTLFLAG_RD, 0, "");
1038         if (bz->sysctl_tree == NULL) {
1039                 sysctl_ctx_free(&bz->sysctl_ctx);
1040                 return 0;       /* XXX error code? */
1041         }
1042
1043         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1044             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1045             "total_bpages", CTLFLAG_RD, &bz->total_bpages, 0,
1046             "Total bounce pages");
1047         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1048             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1049             "free_bpages", CTLFLAG_RD, &bz->free_bpages, 0,
1050             "Free bounce pages");
1051         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1052             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1053             "reserved_bpages", CTLFLAG_RD, &bz->reserved_bpages, 0,
1054             "Reserved bounce pages");
1055         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1056             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1057             "active_bpages", CTLFLAG_RD, &bz->active_bpages, 0,
1058             "Active bounce pages");
1059         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1060             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1061             "total_bounced", CTLFLAG_RD, &bz->total_bounced, 0,
1062             "Total bounce requests");
1063         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1064             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1065             "total_deferred", CTLFLAG_RD, &bz->total_deferred, 0,
1066             "Total bounce requests that were deferred");
1067         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1068             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1069             "reserve_failed", CTLFLAG_RD, &bz->reserve_failed, 0,
1070             "Total bounce page reservations that were failed");
1071         SYSCTL_ADD_STRING(&bz->sysctl_ctx,
1072             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1073             "lowaddr", CTLFLAG_RD, bz->lowaddrid, 0, "");
1074         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1075             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1076             "alignment", CTLFLAG_RD, &bz->alignment, 0, "");
1077
1078         return 0;
1079 }
1080
1081 static int
1082 alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages, int flags)
1083 {
1084         struct bounce_zone *bz = dmat->bounce_zone;
1085         int count = 0, mflags;
1086
1087         if (flags & BUS_DMA_NOWAIT)
1088                 mflags = M_NOWAIT;
1089         else
1090                 mflags = M_WAITOK;
1091
1092         while (numpages > 0) {
1093                 struct bounce_page *bpage;
1094
1095                 bpage = kmalloc(sizeof(*bpage), M_DEVBUF, M_INTWAIT | M_ZERO);
1096
1097                 bpage->vaddr = (vm_offset_t)contigmalloc(PAGE_SIZE, M_DEVBUF,
1098                                                          mflags, 0ul,
1099                                                          bz->lowaddr,
1100                                                          bz->alignment, 0);
1101                 if (bpage->vaddr == 0) {
1102                         kfree(bpage, M_DEVBUF);
1103                         break;
1104                 }
1105                 bpage->busaddr = pmap_kextract(bpage->vaddr);
1106
1107                 BZ_LOCK(bz);
1108                 STAILQ_INSERT_TAIL(&bz->bounce_page_list, bpage, links);
1109                 total_bounce_pages++;
1110                 bz->total_bpages++;
1111                 bz->free_bpages++;
1112                 BZ_UNLOCK(bz);
1113
1114                 count++;
1115                 numpages--;
1116         }
1117         return count;
1118 }
1119
1120 /* Assume caller holds bounce zone spinlock */
1121 static int
1122 reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int commit)
1123 {
1124         struct bounce_zone *bz = dmat->bounce_zone;
1125         int pages;
1126
1127         pages = MIN(bz->free_bpages, map->pagesneeded - map->pagesreserved);
1128         if (!commit && map->pagesneeded > (map->pagesreserved + pages)) {
1129                 bz->reserve_failed++;
1130                 return (map->pagesneeded - (map->pagesreserved + pages));
1131         }
1132
1133         bz->free_bpages -= pages;
1134
1135         bz->reserved_bpages += pages;
1136         KKASSERT(bz->reserved_bpages <= bz->total_bpages);
1137
1138         map->pagesreserved += pages;
1139         pages = map->pagesneeded - map->pagesreserved;
1140
1141         return pages;
1142 }
1143
1144 static void
1145 return_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map)
1146 {
1147         struct bounce_zone *bz = dmat->bounce_zone;
1148         int reserved = map->pagesreserved;
1149         bus_dmamap_t wait_map;
1150
1151         map->pagesreserved = 0;
1152         map->pagesneeded = 0;
1153
1154         if (reserved == 0)
1155                 return;
1156
1157         BZ_LOCK(bz);
1158
1159         bz->free_bpages += reserved;
1160         KKASSERT(bz->free_bpages <= bz->total_bpages);
1161
1162         KKASSERT(bz->reserved_bpages >= reserved);
1163         bz->reserved_bpages -= reserved;
1164
1165         wait_map = get_map_waiting(dmat);
1166
1167         BZ_UNLOCK(bz);
1168
1169         if (wait_map != NULL)
1170                 add_map_callback(map);
1171 }
1172
1173 static bus_addr_t
1174 add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
1175                 bus_size_t size)
1176 {
1177         struct bounce_zone *bz = dmat->bounce_zone;
1178         struct bounce_page *bpage;
1179
1180         KASSERT(map->pagesneeded > 0, ("map doesn't need any pages"));
1181         map->pagesneeded--;
1182
1183         KASSERT(map->pagesreserved > 0, ("map doesn't reserve any pages"));
1184         map->pagesreserved--;
1185
1186         BZ_LOCK(bz);
1187
1188         bpage = STAILQ_FIRST(&bz->bounce_page_list);
1189         KASSERT(bpage != NULL, ("free page list is empty"));
1190         STAILQ_REMOVE_HEAD(&bz->bounce_page_list, links);
1191
1192         KKASSERT(bz->reserved_bpages > 0);
1193         bz->reserved_bpages--;
1194
1195         bz->active_bpages++;
1196         KKASSERT(bz->active_bpages <= bz->total_bpages);
1197
1198         BZ_UNLOCK(bz);
1199
1200         bpage->datavaddr = vaddr;
1201         bpage->datacount = size;
1202         STAILQ_INSERT_TAIL(&map->bpages, bpage, links);
1203         return bpage->busaddr;
1204 }
1205
1206 static void
1207 free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
1208 {
1209         struct bounce_zone *bz = dmat->bounce_zone;
1210         bus_dmamap_t map;
1211
1212         bpage->datavaddr = 0;
1213         bpage->datacount = 0;
1214
1215         BZ_LOCK(bz);
1216
1217         STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
1218
1219         bz->free_bpages++;
1220         KKASSERT(bz->free_bpages <= bz->total_bpages);
1221
1222         KKASSERT(bz->active_bpages > 0);
1223         bz->active_bpages--;
1224
1225         map = get_map_waiting(dmat);
1226
1227         BZ_UNLOCK(bz);
1228
1229         if (map != NULL)
1230                 add_map_callback(map);
1231 }
1232
1233 /* Assume caller holds bounce zone spinlock */
1234 static bus_dmamap_t
1235 get_map_waiting(bus_dma_tag_t dmat)
1236 {
1237         struct bounce_zone *bz = dmat->bounce_zone;
1238         bus_dmamap_t map;
1239
1240         map = STAILQ_FIRST(&bz->bounce_map_waitinglist);
1241         if (map != NULL) {
1242                 if (reserve_bounce_pages(map->dmat, map, 1) == 0) {
1243                         STAILQ_REMOVE_HEAD(&bz->bounce_map_waitinglist, links);
1244                         bz->total_deferred++;
1245                 } else {
1246                         map = NULL;
1247                 }
1248         }
1249         return map;
1250 }
1251
1252 static void
1253 add_map_callback(bus_dmamap_t map)
1254 {
1255 #ifdef notyet
1256         /* XXX callbacklist is not MPSAFE */
1257         crit_enter();
1258         get_mplock();
1259         STAILQ_INSERT_TAIL(&bounce_map_callbacklist, map, links);
1260         busdma_swi_pending = 1;
1261         setsoftvm();
1262         rel_mplock();
1263         crit_exit();
1264 #else
1265         panic("%s uncoded", __func__);
1266 #endif
1267 }
1268
1269 #ifdef notyet
1270 void
1271 busdma_swi(void)
1272 {
1273         bus_dmamap_t map;
1274
1275         crit_enter();
1276         while ((map = STAILQ_FIRST(&bounce_map_callbacklist)) != NULL) {
1277                 STAILQ_REMOVE_HEAD(&bounce_map_callbacklist, links);
1278                 crit_exit();
1279                 bus_dmamap_load(map->dmat, map, map->buf, map->buflen,
1280                                 map->callback, map->callback_arg, /*flags*/0);
1281                 crit_enter();
1282         }
1283         crit_exit();
1284 }
1285 #endif