sys/platform/vkernel/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/bus_dma.h>
  35 #include <sys/kernel.h>
  36 #include <sys/sysctl.h>
  37 #include <sys/lock.h>
  38
  39 #include <sys/thread2.h>
  40 #include <sys/spinlock2.h>
  41 #include <sys/mplock2.h>
  42
  43 #include <vm/vm.h>
  44 #include <vm/vm_page.h>
  45
  46 /* XXX needed for to access pmap to convert per-proc virtual to physical */
  47 #include <sys/proc.h>
  48 #include <sys/lock.h>
  49 #include <vm/vm_map.h>
  50
  51 #include <machine/md_var.h>
  52
  53 #define MAX_BPAGES      1024
  54
  55 struct bounce_zone;
  56 struct bus_dmamap;
  57
  58 struct bus_dma_tag {
  59         bus_dma_tag_t   parent;
  60         bus_size_t      alignment;
  61         bus_size_t      boundary;
  62         bus_addr_t      lowaddr;
  63         bus_addr_t      highaddr;
  64         bus_dma_filter_t *filter;
  65         void            *filterarg;
  66         bus_size_t      maxsize;
  67         u_int           nsegments;
  68         bus_size_t      maxsegsz;
  69         int             flags;
  70         int             ref_count;
  71         int             map_count;
  72         bus_dma_segment_t *segments;
  73         struct bounce_zone *bounce_zone;
  74 };
  75
  76 /*
  77  * bus_dma_tag private flags
  78  */
  79 #define BUS_DMA_BOUNCE_ALIGN    BUS_DMA_BUS2
  80 #define BUS_DMA_BOUNCE_LOWADDR  BUS_DMA_BUS3
  81 #define BUS_DMA_MIN_ALLOC_COMP  BUS_DMA_BUS4
  82
  83 #define BUS_DMA_COULD_BOUNCE    (BUS_DMA_BOUNCE_LOWADDR | BUS_DMA_BOUNCE_ALIGN)
  84
  85 #define BUS_DMAMEM_KMALLOC(dmat) \
  86         ((dmat)->maxsize <= PAGE_SIZE && \
  87          (dmat)->alignment <= PAGE_SIZE && \
  88          (dmat)->lowaddr >= ptoa(Maxmem))
  89
  90 struct bounce_page {
  91         vm_offset_t     vaddr;          /* kva of bounce buffer */
  92         bus_addr_t      busaddr;        /* Physical address */
  93         vm_offset_t     datavaddr;      /* kva of client data */
  94         bus_size_t      datacount;      /* client data count */
  95         STAILQ_ENTRY(bounce_page) links;
  96 };
  97
  98 struct bounce_zone {
  99         STAILQ_ENTRY(bounce_zone) links;
 100         STAILQ_HEAD(bp_list, bounce_page) bounce_page_list;
 101         STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
 102 #ifdef SMP
 103         struct spinlock spin;
 104 #else
 105         int             unused0;
 106 #endif
 107         int             total_bpages;
 108         int             free_bpages;
 109         int             reserved_bpages;
 110         int             active_bpages;
 111         int             total_bounced;
 112         int             total_deferred;
 113         int             reserve_failed;
 114         bus_size_t      alignment;
 115         bus_addr_t      lowaddr;
 116         char            zoneid[8];
 117         char            lowaddrid[20];
 118         struct sysctl_ctx_list sysctl_ctx;
 119         struct sysctl_oid *sysctl_tree;
 120 };
 121
 122 #ifdef SMP
 123 #define BZ_LOCK(bz)     spin_lock(&(bz)->spin)
 124 #define BZ_UNLOCK(bz)   spin_unlock(&(bz)->spin)
 125 #else
 126 #define BZ_LOCK(bz)     crit_enter()
 127 #define BZ_UNLOCK(bz)   crit_exit()
 128 #endif
 129
 130 static struct lwkt_token bounce_zone_tok =
 131         LWKT_TOKEN_INITIALIZER(bounce_zone_token);
 132 static int busdma_zonecount;
 133 static STAILQ_HEAD(, bounce_zone) bounce_zone_list =
 134         STAILQ_HEAD_INITIALIZER(bounce_zone_list);
 135
 136 int busdma_swi_pending;
 137 static int total_bounce_pages;
 138 static int max_bounce_pages = MAX_BPAGES;
 139 static int bounce_alignment = 1; /* XXX temporary */
 140
 141 TUNABLE_INT("hw.busdma.max_bpages", &max_bounce_pages);
 142 TUNABLE_INT("hw.busdma.bounce_alignment", &bounce_alignment);
 143
 144 struct bus_dmamap {
 145         struct bp_list  bpages;
 146         int             pagesneeded;
 147         int             pagesreserved;
 148         bus_dma_tag_t   dmat;
 149         void            *buf;           /* unmapped buffer pointer */
 150         bus_size_t      buflen;         /* unmapped buffer length */
 151         bus_dmamap_callback_t *callback;
 152         void            *callback_arg;
 153         STAILQ_ENTRY(bus_dmamap) links;
 154 };
 155
 156 static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist =
 157         STAILQ_HEAD_INITIALIZER(bounce_map_callbacklist);
 158
 159 static struct bus_dmamap nobounce_dmamap;
 160
 161 static int              alloc_bounce_zone(bus_dma_tag_t);
 162 static int              alloc_bounce_pages(bus_dma_tag_t, u_int, int);
 163 static int              reserve_bounce_pages(bus_dma_tag_t, bus_dmamap_t, int);
 164 static void             return_bounce_pages(bus_dma_tag_t, bus_dmamap_t);
 165 static bus_addr_t       add_bounce_page(bus_dma_tag_t, bus_dmamap_t,
 166                             vm_offset_t, bus_size_t);
 167 static void             free_bounce_page(bus_dma_tag_t, struct bounce_page *);
 168
 169 static bus_dmamap_t     get_map_waiting(bus_dma_tag_t);
 170 static void             add_map_callback(bus_dmamap_t);
 171
 172 SYSCTL_NODE(_hw, OID_AUTO, busdma, CTLFLAG_RD, 0, "Busdma parameters");
 173 SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bounce_pages,
 174            0, "Total bounce pages");
 175 SYSCTL_INT(_hw_busdma, OID_AUTO, max_bpages, CTLFLAG_RD, &max_bounce_pages,
 176            0, "Max bounce pages per bounce zone");
 177 SYSCTL_INT(_hw_busdma, OID_AUTO, bounce_alignment, CTLFLAG_RD,
 178            &bounce_alignment, 0, "Obey alignment constraint");
 179
 180 static __inline int
 181 run_filter(bus_dma_tag_t dmat, bus_addr_t paddr)
 182 {
 183         int retval;
 184
 185         retval = 0;
 186         do {
 187                 if (((paddr > dmat->lowaddr && paddr <= dmat->highaddr) ||
 188                      (bounce_alignment && (paddr & (dmat->alignment - 1)) != 0))
 189                  && (dmat->filter == NULL ||
 190                      dmat->filter(dmat->filterarg, paddr) != 0))
 191                         retval = 1;
 192
 193                 dmat = dmat->parent;
 194         } while (retval == 0 && dmat != NULL);
 195         return (retval);
 196 }
 197
 198 /*
 199  * Allocate a device specific dma_tag.
 200  */
 201 int
 202 bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 203                    bus_size_t boundary, bus_addr_t lowaddr,
 204                    bus_addr_t highaddr, bus_dma_filter_t *filter,
 205                    void *filterarg, bus_size_t maxsize, int nsegments,
 206                    bus_size_t maxsegsz, int flags, bus_dma_tag_t *dmat)
 207 {
 208         bus_dma_tag_t newtag;
 209         int error = 0;
 210
 211         /*
 212          * Sanity checks
 213          */
 214
 215         if (alignment == 0)
 216                 alignment = 1;
 217         if (alignment & (alignment - 1))
 218                 panic("alignment must be power of 2");
 219
 220         if (boundary != 0) {
 221                 if (boundary & (boundary - 1))
 222                         panic("boundary must be power of 2");
 223                 if (boundary < maxsegsz) {
 224                         kprintf("boundary < maxsegsz:\n");
 225                         print_backtrace(-1);
 226                         maxsegsz = boundary;
 227                 }
 228         }
 229
 230         /* Return a NULL tag on failure */
 231         *dmat = NULL;
 232
 233         newtag = kmalloc(sizeof(*newtag), M_DEVBUF, M_INTWAIT);
 234
 235         newtag->parent = parent;
 236         newtag->alignment = alignment;
 237         newtag->boundary = boundary;
 238         newtag->lowaddr = trunc_page((vm_paddr_t)lowaddr) + (PAGE_SIZE - 1);
 239         newtag->highaddr = trunc_page((vm_paddr_t)highaddr) + (PAGE_SIZE - 1);
 240         newtag->filter = filter;
 241         newtag->filterarg = filterarg;
 242         newtag->maxsize = maxsize;
 243         newtag->nsegments = nsegments;
 244         newtag->maxsegsz = maxsegsz;
 245         newtag->flags = flags;
 246         newtag->ref_count = 1; /* Count ourself */
 247         newtag->map_count = 0;
 248         newtag->segments = NULL;
 249         newtag->bounce_zone = NULL;
 250
 251         /* Take into account any restrictions imposed by our parent tag */
 252         if (parent != NULL) {
 253                 newtag->lowaddr = MIN(parent->lowaddr, newtag->lowaddr);
 254                 newtag->highaddr = MAX(parent->highaddr, newtag->highaddr);
 255
 256                 if (newtag->boundary == 0) {
 257                         newtag->boundary = parent->boundary;
 258                 } else if (parent->boundary != 0) {
 259                         newtag->boundary = MIN(parent->boundary,
 260                                                newtag->boundary);
 261                 }
 262
 263 #ifdef notyet
 264                 newtag->alignment = MAX(parent->alignment, newtag->alignment);
 265 #endif
 266
 267                 if (newtag->filter == NULL) {
 268                         /*
 269                          * Short circuit looking at our parent directly
 270                          * since we have encapsulated all of its information
 271                          */
 272                         newtag->filter = parent->filter;
 273                         newtag->filterarg = parent->filterarg;
 274                         newtag->parent = parent->parent;
 275                 }
 276                 if (newtag->parent != NULL)
 277                         parent->ref_count++;
 278         }
 279
 280         if (newtag->lowaddr < ptoa(Maxmem))
 281                 newtag->flags |= BUS_DMA_BOUNCE_LOWADDR;
 282         if (bounce_alignment && newtag->alignment > 1 &&
 283             !(newtag->flags & BUS_DMA_ALIGNED))
 284                 newtag->flags |= BUS_DMA_BOUNCE_ALIGN;
 285
 286         if ((newtag->flags & BUS_DMA_COULD_BOUNCE) &&
 287             (flags & BUS_DMA_ALLOCNOW) != 0) {
 288                 struct bounce_zone *bz;
 289
 290                 /* Must bounce */
 291
 292                 error = alloc_bounce_zone(newtag);
 293                 if (error)
 294                         goto back;
 295                 bz = newtag->bounce_zone;
 296
 297                 if (ptoa(bz->total_bpages) < maxsize) {
 298                         int pages;
 299
 300                         if (flags & BUS_DMA_ONEBPAGE) {
 301                                 pages = 1;
 302                         } else {
 303                                 pages = atop(round_page(maxsize)) -
 304                                         bz->total_bpages;
 305                                 pages = MAX(pages, 1);
 306                         }
 307
 308                         /* Add pages to our bounce pool */
 309                         if (alloc_bounce_pages(newtag, pages, flags) < pages)
 310                                 error = ENOMEM;
 311
 312                         /* Performed initial allocation */
 313                         newtag->flags |= BUS_DMA_MIN_ALLOC_COMP;
 314                 }
 315         }
 316 back:
 317         if (error)
 318                 kfree(newtag, M_DEVBUF);
 319         else
 320                 *dmat = newtag;
 321         return error;
 322 }
 323
 324 int
 325 bus_dma_tag_destroy(bus_dma_tag_t dmat)
 326 {
 327         if (dmat != NULL) {
 328                 if (dmat->map_count != 0)
 329                         return (EBUSY);
 330
 331                 while (dmat != NULL) {
 332                         bus_dma_tag_t parent;
 333
 334                         parent = dmat->parent;
 335                         dmat->ref_count--;
 336                         if (dmat->ref_count == 0) {
 337                                 if (dmat->segments != NULL)
 338                                         kfree(dmat->segments, M_DEVBUF);
 339                                 kfree(dmat, M_DEVBUF);
 340                                 /*
 341                                  * Last reference count, so
 342                                  * release our reference
 343                                  * count on our parent.
 344                                  */
 345                                 dmat = parent;
 346                         } else
 347                                 dmat = NULL;
 348                 }
 349         }
 350         return (0);
 351 }
 352
 353 /*
 354  * Allocate a handle for mapping from kva/uva/physical
 355  * address space into bus device space.
 356  */
 357 int
 358 bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
 359 {
 360         int error;
 361
 362         error = 0;
 363
 364         if (dmat->segments == NULL) {
 365                 KKASSERT(dmat->nsegments && dmat->nsegments < 16384);
 366                 dmat->segments = kmalloc(sizeof(bus_dma_segment_t) *
 367                                         dmat->nsegments, M_DEVBUF, M_INTWAIT);
 368         }
 369
 370         if (dmat->flags & BUS_DMA_COULD_BOUNCE) {
 371                 struct bounce_zone *bz;
 372                 int maxpages;
 373
 374                 /* Must bounce */
 375
 376                 if (dmat->bounce_zone == NULL) {
 377                         error = alloc_bounce_zone(dmat);
 378                         if (error)
 379                                 return error;
 380                 }
 381                 bz = dmat->bounce_zone;
 382
 383                 *mapp = kmalloc(sizeof(**mapp), M_DEVBUF, M_INTWAIT | M_ZERO);
 384
 385                 /* Initialize the new map */
 386                 STAILQ_INIT(&((*mapp)->bpages));
 387
 388                 /*
 389                  * Attempt to add pages to our pool on a per-instance
 390                  * basis up to a sane limit.
 391                  */
 392                 if (dmat->flags & BUS_DMA_BOUNCE_ALIGN) {
 393                         maxpages = max_bounce_pages;
 394                 } else {
 395                         maxpages = MIN(max_bounce_pages,
 396                                        Maxmem - atop(dmat->lowaddr));
 397                 }
 398                 if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
 399                  || (dmat->map_count > 0
 400                   && bz->total_bpages < maxpages)) {
 401                         int pages;
 402
 403                         if (flags & BUS_DMA_ONEBPAGE) {
 404                                 pages = 1;
 405                         } else {
 406                                 pages = atop(round_page(dmat->maxsize));
 407                                 pages = MIN(maxpages - bz->total_bpages, pages);
 408                                 pages = MAX(pages, 1);
 409                         }
 410                         if (alloc_bounce_pages(dmat, pages, flags) < pages)
 411                                 error = ENOMEM;
 412
 413                         if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0) {
 414                                 if (!error)
 415                                         dmat->flags |= BUS_DMA_MIN_ALLOC_COMP;
 416                         } else {
 417                                 error = 0;
 418                         }
 419                 }
 420         } else {
 421                 *mapp = NULL;
 422         }
 423         if (!error)
 424                 dmat->map_count++;
 425         return error;
 426 }
 427
 428 /*
 429  * Destroy a handle for mapping from kva/uva/physical
 430  * address space into bus device space.
 431  */
 432 int
 433 bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
 434 {
 435         if (map != NULL) {
 436                 if (STAILQ_FIRST(&map->bpages) != NULL)
 437                         return (EBUSY);
 438                 kfree(map, M_DEVBUF);
 439         }
 440         dmat->map_count--;
 441         return (0);
 442 }
 443
 444 static __inline bus_size_t
 445 check_kmalloc(bus_dma_tag_t dmat, const void *vaddr0, int verify)
 446 {
 447         bus_size_t maxsize = 0;
 448         uintptr_t vaddr = (uintptr_t)vaddr0;
 449
 450         if ((vaddr ^ (vaddr + dmat->maxsize - 1)) & ~PAGE_MASK) {
 451                 if (verify || bootverbose)
 452                         kprintf("boundary check failed\n");
 453                 if (verify)
 454                         print_backtrace(-1); /* XXX panic */
 455                 maxsize = dmat->maxsize;
 456         }
 457         if (vaddr & (dmat->alignment - 1)) {
 458                 if (verify || bootverbose)
 459                         kprintf("alignment check failed\n");
 460                 if (verify)
 461                         print_backtrace(-1); /* XXX panic */
 462                 if (dmat->maxsize < dmat->alignment)
 463                         maxsize = dmat->alignment;
 464                 else
 465                         maxsize = dmat->maxsize;
 466         }
 467         return maxsize;
 468 }
 469
 470 /*
 471  * Allocate a piece of memory that can be efficiently mapped into
 472  * bus device space based on the constraints lited in the dma tag.
 473  *
 474  * mapp is degenerate.  By definition this allocation should not require
 475  * bounce buffers so do not allocate a dma map.
 476  */
 477 int
 478 bus_dmamem_alloc(bus_dma_tag_t dmat, void **vaddr, int flags,
 479                  bus_dmamap_t *mapp)
 480 {
 481         int mflags;
 482
 483         /* If we succeed, no mapping/bouncing will be required */
 484         *mapp = NULL;
 485
 486         if (dmat->segments == NULL) {
 487                 KKASSERT(dmat->nsegments < 16384);
 488                 dmat->segments = kmalloc(sizeof(bus_dma_segment_t) *
 489                                         dmat->nsegments, M_DEVBUF, M_INTWAIT);
 490         }
 491
 492         if (flags & BUS_DMA_NOWAIT)
 493                 mflags = M_NOWAIT;
 494         else
 495                 mflags = M_WAITOK;
 496         if (flags & BUS_DMA_ZERO)
 497                 mflags |= M_ZERO;
 498
 499         if (BUS_DMAMEM_KMALLOC(dmat)) {
 500                 bus_size_t maxsize;
 501
 502                 *vaddr = kmalloc(dmat->maxsize, M_DEVBUF, mflags);
 503
 504                 /*
 505                  * XXX
 506                  * Check whether the allocation
 507                  * - crossed a page boundary
 508                  * - was not aligned
 509                  * Retry with power-of-2 alignment in the above cases.
 510                  */
 511                 maxsize = check_kmalloc(dmat, *vaddr, 0);
 512                 if (maxsize) {
 513                         size_t size;
 514
 515                         kfree(*vaddr, M_DEVBUF);
 516                         /* XXX check for overflow? */
 517                         for (size = 1; size <= maxsize; size <<= 1)
 518                                 ;
 519                         *vaddr = kmalloc(size, M_DEVBUF, mflags);
 520                         check_kmalloc(dmat, *vaddr, 1);
 521                 }
 522         } else {
 523                 /*
 524                  * XXX Use Contigmalloc until it is merged into this facility
 525                  *     and handles multi-seg allocations.  Nobody is doing
 526                  *     multi-seg allocations yet though.
 527                  */
 528                 *vaddr = contigmalloc(dmat->maxsize, M_DEVBUF, mflags,
 529                     0ul, dmat->lowaddr, dmat->alignment, dmat->boundary);
 530         }
 531         if (*vaddr == NULL)
 532                 return (ENOMEM);
 533         return (0);
 534 }
 535
 536 /*
 537  * Free a piece of memory and it's allociated dmamap, that was allocated
 538  * via bus_dmamem_alloc.  Make the same choice for free/contigfree.
 539  */
 540 void
 541 bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
 542 {
 543         /*
 544          * dmamem does not need to be bounced, so the map should be
 545          * NULL
 546          */
 547         if (map != NULL)
 548                 panic("bus_dmamem_free: Invalid map freed");
 549         if (BUS_DMAMEM_KMALLOC(dmat))
 550                 kfree(vaddr, M_DEVBUF);
 551         else
 552                 contigfree(vaddr, dmat->maxsize, M_DEVBUF);
 553 }
 554
 555 static __inline vm_paddr_t
 556 _bus_dma_extract(pmap_t pmap, vm_offset_t vaddr)
 557 {
 558         if (pmap)
 559                 return pmap_extract(pmap, vaddr);
 560         else
 561                 return pmap_kextract(vaddr);
 562 }
 563
 564 /*
 565  * Utility function to load a linear buffer.  lastaddrp holds state
 566  * between invocations (for multiple-buffer loads).  segp contains
 567  * the segment following the starting one on entrace, and the ending
 568  * segment on exit.  first indicates if this is the first invocation
 569  * of this function.
 570  */
 571 static int
 572 _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
 573                         bus_dmamap_t map,
 574                         void *buf, bus_size_t buflen,
 575                         bus_dma_segment_t *segments,
 576                         int nsegments,
 577                         pmap_t pmap,
 578                         int flags,
 579                         vm_paddr_t *lastpaddrp,
 580                         int *segp,
 581                         int first)
 582 {
 583         vm_offset_t vaddr;
 584         vm_paddr_t paddr, nextpaddr;
 585         bus_dma_segment_t *sg;
 586         bus_addr_t bmask;
 587         int seg, error = 0;
 588
 589         if (map == NULL)
 590                 map = &nobounce_dmamap;
 591
 592 #ifdef INVARIANTS
 593         if (dmat->flags & BUS_DMA_ALIGNED)
 594                 KKASSERT(((uintptr_t)buf & (dmat->alignment - 1)) == 0);
 595 #endif
 596
 597         /*
 598          * If we are being called during a callback, pagesneeded will
 599          * be non-zero, so we can avoid doing the work twice.
 600          */
 601         if ((dmat->flags & BUS_DMA_COULD_BOUNCE) &&
 602             map != &nobounce_dmamap && map->pagesneeded == 0) {
 603                 vm_offset_t vendaddr;
 604
 605                 /*
 606                  * Count the number of bounce pages
 607                  * needed in order to complete this transfer
 608                  */
 609                 vaddr = (vm_offset_t)buf;
 610                 vendaddr = (vm_offset_t)buf + buflen;
 611
 612                 while (vaddr < vendaddr) {
 613                         paddr = _bus_dma_extract(pmap, vaddr);
 614                         if (run_filter(dmat, paddr) != 0)
 615                                 map->pagesneeded++;
 616                         vaddr += (PAGE_SIZE - (vaddr & PAGE_MASK));
 617                 }
 618         }
 619
 620         /* Reserve Necessary Bounce Pages */
 621         if (map->pagesneeded != 0) {
 622                 struct bounce_zone *bz;
 623
 624                 bz = dmat->bounce_zone;
 625                 BZ_LOCK(bz);
 626                 if (flags & BUS_DMA_NOWAIT) {
 627                         if (reserve_bounce_pages(dmat, map, 0) != 0) {
 628                                 BZ_UNLOCK(bz);
 629                                 error = ENOMEM;
 630                                 goto free_bounce;
 631                         }
 632                 } else {
 633                         if (reserve_bounce_pages(dmat, map, 1) != 0) {
 634                                 /* Queue us for resources */
 635                                 map->dmat = dmat;
 636                                 map->buf = buf;
 637                                 map->buflen = buflen;
 638
 639                                 STAILQ_INSERT_TAIL(
 640                                     &dmat->bounce_zone->bounce_map_waitinglist,
 641                                     map, links);
 642                                 BZ_UNLOCK(bz);
 643
 644                                 return (EINPROGRESS);
 645                         }
 646                 }
 647                 BZ_UNLOCK(bz);
 648         }
 649
 650         KKASSERT(*segp >= 1 && *segp <= nsegments);
 651         seg = *segp;
 652         sg = &segments[seg - 1];
 653
 654         vaddr = (vm_offset_t)buf;
 655         nextpaddr = *lastpaddrp;
 656         bmask = ~(dmat->boundary - 1);  /* note: will be 0 if boundary is 0 */
 657
 658         /* force at least one segment */
 659         do {
 660                 bus_size_t size;
 661
 662                 /*
 663                  * Per-page main loop
 664                  */
 665                 paddr = _bus_dma_extract(pmap, vaddr);
 666                 size = PAGE_SIZE - (paddr & PAGE_MASK);
 667                 if (size > buflen)
 668                         size = buflen;
 669                 if (map->pagesneeded != 0 && run_filter(dmat, paddr)) {
 670                         /*
 671                          * note: this paddr has the same in-page offset
 672                          * as vaddr and thus the paddr above, so the
 673                          * size does not have to be recalculated
 674                          */
 675                         paddr = add_bounce_page(dmat, map, vaddr, size);
 676                 }
 677
 678                 /*
 679                  * Fill in the bus_dma_segment
 680                  */
 681                 if (first) {
 682                         sg->ds_addr = paddr;
 683                         sg->ds_len = size;
 684                         first = 0;
 685                 } else if (paddr == nextpaddr) {
 686                         sg->ds_len += size;
 687                 } else {
 688                         sg++;
 689                         seg++;
 690                         if (seg > nsegments)
 691                                 break;
 692                         sg->ds_addr = paddr;
 693                         sg->ds_len = size;
 694                 }
 695                 nextpaddr = paddr + size;
 696
 697                 /*
 698                  * Handle maxsegsz and boundary issues with a nested loop
 699                  */
 700                 for (;;) {
 701                         bus_size_t tmpsize;
 702
 703                         /*
 704                          * Limit to the boundary and maximum segment size
 705                          */
 706                         if (((nextpaddr - 1) ^ sg->ds_addr) & bmask) {
 707                                 tmpsize = dmat->boundary -
 708                                           (sg->ds_addr & ~bmask);
 709                                 if (tmpsize > dmat->maxsegsz)
 710                                         tmpsize = dmat->maxsegsz;
 711                                 KKASSERT(tmpsize < sg->ds_len);
 712                         } else if (sg->ds_len > dmat->maxsegsz) {
 713                                 tmpsize = dmat->maxsegsz;
 714                         } else {
 715                                 break;
 716                         }
 717
 718                         /*
 719                          * Futz, split the data into a new segment.
 720                          */
 721                         if (seg >= nsegments)
 722                                 goto fail;
 723                         sg[1].ds_len = sg[0].ds_len - tmpsize;
 724                         sg[1].ds_addr = sg[0].ds_addr + tmpsize;
 725                         sg[0].ds_len = tmpsize;
 726                         sg++;
 727                         seg++;
 728                 }
 729
 730                 /*
 731                  * Adjust for loop
 732                  */
 733                 buflen -= size;
 734                 vaddr += size;
 735         } while (buflen > 0);
 736 fail:
 737         if (buflen != 0)
 738                 error = EFBIG;
 739
 740         *segp = seg;
 741         *lastpaddrp = nextpaddr;
 742
 743 free_bounce:
 744         if (error && (dmat->flags & BUS_DMA_COULD_BOUNCE) &&
 745             map != &nobounce_dmamap) {
 746                 _bus_dmamap_unload(dmat, map);
 747                 return_bounce_pages(dmat, map);
 748         }
 749         return error;
 750 }
 751
 752 /*
 753  * Map the buffer buf into bus space using the dmamap map.
 754  */
 755 int
 756 bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
 757                 bus_size_t buflen, bus_dmamap_callback_t *callback,
 758                 void *callback_arg, int flags)
 759 {
 760         vm_paddr_t lastaddr = 0;
 761         int error, nsegs = 1;
 762
 763         if (map != NULL) {
 764                 /*
 765                  * XXX
 766                  * Follow old semantics.  Once all of the callers are fixed,
 767                  * we should get rid of these internal flag "adjustment".
 768                  */
 769                 flags &= ~BUS_DMA_NOWAIT;
 770                 flags |= BUS_DMA_WAITOK;
 771
 772                 map->callback = callback;
 773                 map->callback_arg = callback_arg;
 774         }
 775
 776         error = _bus_dmamap_load_buffer(dmat, map, buf, buflen,
 777                         dmat->segments, dmat->nsegments,
 778                         NULL, flags, &lastaddr, &nsegs, 1);
 779         if (error == EINPROGRESS)
 780                 return error;
 781
 782         callback(callback_arg, dmat->segments, nsegs, error);
 783         return 0;
 784 }
 785
 786 /*
 787  * Like _bus_dmamap_load(), but for mbufs.
 788  */
 789 int
 790 bus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map,
 791                      struct mbuf *m0,
 792                      bus_dmamap_callback2_t *callback, void *callback_arg,
 793                      int flags)
 794 {
 795         int nsegs, error;
 796
 797         /*
 798          * XXX
 799          * Follow old semantics.  Once all of the callers are fixed,
 800          * we should get rid of these internal flag "adjustment".
 801          */
 802         flags &= ~BUS_DMA_WAITOK;
 803         flags |= BUS_DMA_NOWAIT;
 804
 805         error = bus_dmamap_load_mbuf_segment(dmat, map, m0,
 806                         dmat->segments, dmat->nsegments, &nsegs, flags);
 807         if (error) {
 808                 /* force "no valid mappings" in callback */
 809                 callback(callback_arg, dmat->segments, 0, 0, error);
 810         } else {
 811                 callback(callback_arg, dmat->segments, nsegs,
 812                          m0->m_pkthdr.len, error);
 813         }
 814         return error;
 815 }
 816
 817 int
 818 bus_dmamap_load_mbuf_segment(bus_dma_tag_t dmat, bus_dmamap_t map,
 819                              struct mbuf *m0,
 820                              bus_dma_segment_t *segs, int maxsegs,
 821                              int *nsegs, int flags)
 822 {
 823         int error;
 824
 825         M_ASSERTPKTHDR(m0);
 826
 827         KASSERT(maxsegs >= 1, ("invalid maxsegs %d", maxsegs));
 828         KASSERT(maxsegs <= dmat->nsegments,
 829                 ("%d too many segments, dmat only supports %d segments",
 830                  maxsegs, dmat->nsegments));
 831         KASSERT(flags & BUS_DMA_NOWAIT,
 832                 ("only BUS_DMA_NOWAIT is supported"));
 833
 834         if (m0->m_pkthdr.len <= dmat->maxsize) {
 835                 int first = 1;
 836                 vm_paddr_t lastaddr = 0;
 837                 struct mbuf *m;
 838
 839                 *nsegs = 1;
 840                 error = 0;
 841                 for (m = m0; m != NULL && error == 0; m = m->m_next) {
 842                         if (m->m_len == 0)
 843                                 continue;
 844
 845                         error = _bus_dmamap_load_buffer(dmat, map,
 846                                         m->m_data, m->m_len,
 847                                         segs, maxsegs,
 848                                         NULL, flags, &lastaddr,
 849                                         nsegs, first);
 850                         if (error == ENOMEM && !first) {
 851                                 /*
 852                                  * Out of bounce pages due to too many
 853                                  * fragments in the mbuf chain; return
 854                                  * EFBIG instead.
 855                                  */
 856                                 error = EFBIG;
 857                         }
 858                         first = 0;
 859                 }
 860 #ifdef INVARIANTS
 861                 if (!error)
 862                         KKASSERT(*nsegs <= maxsegs && *nsegs >= 1);
 863 #endif
 864         } else {
 865                 *nsegs = 0;
 866                 error = EINVAL;
 867         }
 868         KKASSERT(error != EINPROGRESS);
 869         return error;
 870 }
 871
 872 /*
 873  * Like _bus_dmamap_load(), but for uios.
 874  */
 875 int
 876 bus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map,
 877                     struct uio *uio,
 878                     bus_dmamap_callback2_t *callback, void *callback_arg,
 879                     int flags)
 880 {
 881         vm_paddr_t lastaddr;
 882         int nsegs, error, first, i;
 883         bus_size_t resid;
 884         struct iovec *iov;
 885         pmap_t pmap;
 886
 887         /*
 888          * XXX
 889          * Follow old semantics.  Once all of the callers are fixed,
 890          * we should get rid of these internal flag "adjustment".
 891          */
 892         flags &= ~BUS_DMA_WAITOK;
 893         flags |= BUS_DMA_NOWAIT;
 894
 895         resid = (bus_size_t)uio->uio_resid;
 896         iov = uio->uio_iov;
 897
 898         if (uio->uio_segflg == UIO_USERSPACE) {
 899                 struct thread *td;
 900
 901                 td = uio->uio_td;
 902                 KASSERT(td != NULL && td->td_proc != NULL,
 903                         ("bus_dmamap_load_uio: USERSPACE but no proc"));
 904                 pmap = vmspace_pmap(td->td_proc->p_vmspace);
 905         } else {
 906                 pmap = NULL;
 907         }
 908
 909         error = 0;
 910         nsegs = 1;
 911         first = 1;
 912         lastaddr = 0;
 913         for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
 914                 /*
 915                  * Now at the first iovec to load.  Load each iovec
 916                  * until we have exhausted the residual count.
 917                  */
 918                 bus_size_t minlen =
 919                         resid < iov[i].iov_len ? resid : iov[i].iov_len;
 920                 caddr_t addr = (caddr_t) iov[i].iov_base;
 921
 922                 error = _bus_dmamap_load_buffer(dmat, map, addr, minlen,
 923                                 dmat->segments, dmat->nsegments,
 924                                 pmap, flags, &lastaddr, &nsegs, first);
 925                 first = 0;
 926
 927                 resid -= minlen;
 928         }
 929
 930         if (error) {
 931                 /* force "no valid mappings" in callback */
 932                 callback(callback_arg, dmat->segments, 0, 0, error);
 933         } else {
 934                 callback(callback_arg, dmat->segments, nsegs,
 935                          (bus_size_t)uio->uio_resid, error);
 936         }
 937         return error;
 938 }
 939
 940 /*
 941  * Release the mapping held by map.
 942  */
 943 void
 944 _bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
 945 {
 946         struct bounce_page *bpage;
 947
 948         while ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
 949                 STAILQ_REMOVE_HEAD(&map->bpages, links);
 950                 free_bounce_page(dmat, bpage);
 951         }
 952 }
 953
 954 void
 955 _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
 956 {
 957         struct bounce_page *bpage;
 958
 959         if ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
 960                 /*
 961                  * Handle data bouncing.  We might also
 962                  * want to add support for invalidating
 963                  * the caches on broken hardware
 964                  */
 965                 switch (op) {
 966                 case BUS_DMASYNC_PREWRITE:
 967                         while (bpage != NULL) {
 968                                 bcopy((void *)bpage->datavaddr,
 969                                       (void *)bpage->vaddr,
 970                                       bpage->datacount);
 971                                 bpage = STAILQ_NEXT(bpage, links);
 972                         }
 973                         dmat->bounce_zone->total_bounced++;
 974                         break;
 975
 976                 case BUS_DMASYNC_POSTREAD:
 977                         while (bpage != NULL) {
 978                                 bcopy((void *)bpage->vaddr,
 979                                       (void *)bpage->datavaddr,
 980                                       bpage->datacount);
 981                                 bpage = STAILQ_NEXT(bpage, links);
 982                         }
 983                         dmat->bounce_zone->total_bounced++;
 984                         break;
 985
 986                 case BUS_DMASYNC_PREREAD:
 987                 case BUS_DMASYNC_POSTWRITE:
 988                         /* No-ops */
 989                         break;
 990                 }
 991         }
 992 }
 993
 994 static int
 995 alloc_bounce_zone(bus_dma_tag_t dmat)
 996 {
 997         struct bounce_zone *bz, *new_bz;
 998
 999         KASSERT(dmat->bounce_zone == NULL,
1000                 ("bounce zone was already assigned"));
1001
1002         new_bz = kmalloc(sizeof(*new_bz), M_DEVBUF, M_INTWAIT | M_ZERO);
1003
1004         lwkt_gettoken(&bounce_zone_tok);
1005
1006         /* Check to see if we already have a suitable zone */
1007         STAILQ_FOREACH(bz, &bounce_zone_list, links) {
1008                 if (dmat->alignment <= bz->alignment &&
1009                     dmat->lowaddr >= bz->lowaddr) {
1010                         lwkt_reltoken(&bounce_zone_tok);
1011
1012                         dmat->bounce_zone = bz;
1013                         kfree(new_bz, M_DEVBUF);
1014                         return 0;
1015                 }
1016         }
1017         bz = new_bz;
1018
1019 #ifdef SMP
1020         spin_init(&bz->spin);
1021 #endif
1022         STAILQ_INIT(&bz->bounce_page_list);
1023         STAILQ_INIT(&bz->bounce_map_waitinglist);
1024         bz->free_bpages = 0;
1025         bz->reserved_bpages = 0;
1026         bz->active_bpages = 0;
1027         bz->lowaddr = dmat->lowaddr;
1028         bz->alignment = round_page(dmat->alignment);
1029         ksnprintf(bz->zoneid, 8, "zone%d", busdma_zonecount);
1030         busdma_zonecount++;
1031         ksnprintf(bz->lowaddrid, 18, "%#jx", (uintmax_t)bz->lowaddr);
1032         STAILQ_INSERT_TAIL(&bounce_zone_list, bz, links);
1033
1034         lwkt_reltoken(&bounce_zone_tok);
1035
1036         dmat->bounce_zone = bz;
1037
1038         sysctl_ctx_init(&bz->sysctl_ctx);
1039         bz->sysctl_tree = SYSCTL_ADD_NODE(&bz->sysctl_ctx,
1040             SYSCTL_STATIC_CHILDREN(_hw_busdma), OID_AUTO, bz->zoneid,
1041             CTLFLAG_RD, 0, "");
1042         if (bz->sysctl_tree == NULL) {
1043                 sysctl_ctx_free(&bz->sysctl_ctx);
1044                 return 0;       /* XXX error code? */
1045         }
1046
1047         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1048             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1049             "total_bpages", CTLFLAG_RD, &bz->total_bpages, 0,
1050             "Total bounce pages");
1051         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1052             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1053             "free_bpages", CTLFLAG_RD, &bz->free_bpages, 0,
1054             "Free bounce pages");
1055         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1056             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1057             "reserved_bpages", CTLFLAG_RD, &bz->reserved_bpages, 0,
1058             "Reserved bounce pages");
1059         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1060             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1061             "active_bpages", CTLFLAG_RD, &bz->active_bpages, 0,
1062             "Active bounce pages");
1063         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1064             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1065             "total_bounced", CTLFLAG_RD, &bz->total_bounced, 0,
1066             "Total bounce requests");
1067         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1068             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1069             "total_deferred", CTLFLAG_RD, &bz->total_deferred, 0,
1070             "Total bounce requests that were deferred");
1071         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1072             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1073             "reserve_failed", CTLFLAG_RD, &bz->reserve_failed, 0,
1074             "Total bounce page reservations that were failed");
1075         SYSCTL_ADD_STRING(&bz->sysctl_ctx,
1076             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1077             "lowaddr", CTLFLAG_RD, bz->lowaddrid, 0, "");
1078         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1079             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1080             "alignment", CTLFLAG_RD, &bz->alignment, 0, "");
1081
1082         return 0;
1083 }
1084
1085 static int
1086 alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages, int flags)
1087 {
1088         struct bounce_zone *bz = dmat->bounce_zone;
1089         int count = 0, mflags;
1090
1091         if (flags & BUS_DMA_NOWAIT)
1092                 mflags = M_NOWAIT;
1093         else
1094                 mflags = M_WAITOK;
1095
1096         while (numpages > 0) {
1097                 struct bounce_page *bpage;
1098
1099                 bpage = kmalloc(sizeof(*bpage), M_DEVBUF, M_INTWAIT | M_ZERO);
1100
1101                 bpage->vaddr = (vm_offset_t)contigmalloc(PAGE_SIZE, M_DEVBUF,
1102                                                          mflags, 0ul,
1103                                                          bz->lowaddr,
1104                                                          bz->alignment, 0);
1105                 if (bpage->vaddr == 0) {
1106                         kfree(bpage, M_DEVBUF);
1107                         break;
1108                 }
1109                 bpage->busaddr = pmap_kextract(bpage->vaddr);
1110
1111                 BZ_LOCK(bz);
1112                 STAILQ_INSERT_TAIL(&bz->bounce_page_list, bpage, links);
1113                 total_bounce_pages++;
1114                 bz->total_bpages++;
1115                 bz->free_bpages++;
1116                 BZ_UNLOCK(bz);
1117
1118                 count++;
1119                 numpages--;
1120         }
1121         return count;
1122 }
1123
1124 /* Assume caller holds bounce zone spinlock */
1125 static int
1126 reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int commit)
1127 {
1128         struct bounce_zone *bz = dmat->bounce_zone;
1129         int pages;
1130
1131         pages = MIN(bz->free_bpages, map->pagesneeded - map->pagesreserved);
1132         if (!commit && map->pagesneeded > (map->pagesreserved + pages)) {
1133                 bz->reserve_failed++;
1134                 return (map->pagesneeded - (map->pagesreserved + pages));
1135         }
1136
1137         bz->free_bpages -= pages;
1138
1139         bz->reserved_bpages += pages;
1140         KKASSERT(bz->reserved_bpages <= bz->total_bpages);
1141
1142         map->pagesreserved += pages;
1143         pages = map->pagesneeded - map->pagesreserved;
1144
1145         return pages;
1146 }
1147
1148 static void
1149 return_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map)
1150 {
1151         struct bounce_zone *bz = dmat->bounce_zone;
1152         int reserved = map->pagesreserved;
1153         bus_dmamap_t wait_map;
1154
1155         map->pagesreserved = 0;
1156         map->pagesneeded = 0;
1157
1158         if (reserved == 0)
1159                 return;
1160
1161         BZ_LOCK(bz);
1162
1163         bz->free_bpages += reserved;
1164         KKASSERT(bz->free_bpages <= bz->total_bpages);
1165
1166         KKASSERT(bz->reserved_bpages >= reserved);
1167         bz->reserved_bpages -= reserved;
1168
1169         wait_map = get_map_waiting(dmat);
1170
1171         BZ_UNLOCK(bz);
1172
1173         if (wait_map != NULL)
1174                 add_map_callback(map);
1175 }
1176
1177 static bus_addr_t
1178 add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
1179                 bus_size_t size)
1180 {
1181         struct bounce_zone *bz = dmat->bounce_zone;
1182         struct bounce_page *bpage;
1183
1184         KASSERT(map->pagesneeded > 0, ("map doesn't need any pages"));
1185         map->pagesneeded--;
1186
1187         KASSERT(map->pagesreserved > 0, ("map doesn't reserve any pages"));
1188         map->pagesreserved--;
1189
1190         BZ_LOCK(bz);
1191
1192         bpage = STAILQ_FIRST(&bz->bounce_page_list);
1193         KASSERT(bpage != NULL, ("free page list is empty"));
1194         STAILQ_REMOVE_HEAD(&bz->bounce_page_list, links);
1195
1196         KKASSERT(bz->reserved_bpages > 0);
1197         bz->reserved_bpages--;
1198
1199         bz->active_bpages++;
1200         KKASSERT(bz->active_bpages <= bz->total_bpages);
1201
1202         BZ_UNLOCK(bz);
1203
1204         bpage->datavaddr = vaddr;
1205         bpage->datacount = size;
1206         STAILQ_INSERT_TAIL(&map->bpages, bpage, links);
1207         return bpage->busaddr;
1208 }
1209
1210 static void
1211 free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
1212 {
1213         struct bounce_zone *bz = dmat->bounce_zone;
1214         bus_dmamap_t map;
1215
1216         bpage->datavaddr = 0;
1217         bpage->datacount = 0;
1218
1219         BZ_LOCK(bz);
1220
1221         STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
1222
1223         bz->free_bpages++;
1224         KKASSERT(bz->free_bpages <= bz->total_bpages);
1225
1226         KKASSERT(bz->active_bpages > 0);
1227         bz->active_bpages--;
1228
1229         map = get_map_waiting(dmat);
1230
1231         BZ_UNLOCK(bz);
1232
1233         if (map != NULL)
1234                 add_map_callback(map);
1235 }
1236
1237 /* Assume caller holds bounce zone spinlock */
1238 static bus_dmamap_t
1239 get_map_waiting(bus_dma_tag_t dmat)
1240 {
1241         struct bounce_zone *bz = dmat->bounce_zone;
1242         bus_dmamap_t map;
1243
1244         map = STAILQ_FIRST(&bz->bounce_map_waitinglist);
1245         if (map != NULL) {
1246                 if (reserve_bounce_pages(map->dmat, map, 1) == 0) {
1247                         STAILQ_REMOVE_HEAD(&bz->bounce_map_waitinglist, links);
1248                         bz->total_deferred++;
1249                 } else {
1250                         map = NULL;
1251                 }
1252         }
1253         return map;
1254 }
1255
1256 static void
1257 add_map_callback(bus_dmamap_t map)
1258 {
1259 #ifdef notyet
1260         /* XXX callbacklist is not MPSAFE */
1261         crit_enter();
1262         get_mplock();
1263         STAILQ_INSERT_TAIL(&bounce_map_callbacklist, map, links);
1264         busdma_swi_pending = 1;
1265         setsoftvm();
1266         rel_mplock();
1267         crit_exit();
1268 #else
1269         panic("%s uncoded", __func__);
1270 #endif
1271 }
1272
1273 #ifdef notyet
1274 void
1275 busdma_swi(void)
1276 {
1277         bus_dmamap_t map;
1278
1279         crit_enter();
1280         while ((map = STAILQ_FIRST(&bounce_map_callbacklist)) != NULL) {
1281                 STAILQ_REMOVE_HEAD(&bounce_map_callbacklist, links);
1282                 crit_exit();
1283                 bus_dmamap_load(map->dmat, map, map->buf, map->buflen,
1284                                 map->callback, map->callback_arg, /*flags*/0);
1285                 crit_enter();
1286         }
1287         crit_exit();
1288 }
1289 #endif