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  * $DragonFly: src/sys/platform/pc32/i386/busdma_machdep.c,v 1.23 2008/06/05 18:06:32 swildner Exp $
  28  */
  29
  30 #include <sys/param.h>
  31 #include <sys/systm.h>
  32 #include <sys/malloc.h>
  33 #include <sys/mbuf.h>
  34 #include <sys/uio.h>
  35 #include <sys/bus_dma.h>
  36 #include <sys/kernel.h>
  37 #include <sys/sysctl.h>
  38 #include <sys/lock.h>
  39
  40 #include <sys/thread2.h>
  41 #include <sys/spinlock2.h>
  42 #include <sys/mplock2.h>
  43
  44 #include <vm/vm.h>
  45 #include <vm/vm_page.h>
  46
  47 /* XXX needed for to access pmap to convert per-proc virtual to physical */
  48 #include <sys/proc.h>
  49 #include <sys/lock.h>
  50 #include <vm/vm_map.h>
  51
  52 #include <machine/md_var.h>
  53
  54 #define MAX_BPAGES      1024
  55
  56 struct bounce_zone;
  57 struct bus_dmamap;
  58
  59 struct bus_dma_tag {
  60         bus_dma_tag_t   parent;
  61         bus_size_t      alignment;
  62         bus_size_t      boundary;
  63         bus_addr_t      lowaddr;
  64         bus_addr_t      highaddr;
  65         bus_dma_filter_t *filter;
  66         void            *filterarg;
  67         bus_size_t      maxsize;
  68         u_int           nsegments;
  69         bus_size_t      maxsegsz;
  70         int             flags;
  71         int             ref_count;
  72         int             map_count;
  73         bus_dma_segment_t *segments;
  74         struct bounce_zone *bounce_zone;
  75 };
  76
  77 /*
  78  * bus_dma_tag private flags
  79  */
  80 #define BUS_DMA_BOUNCE_ALIGN    BUS_DMA_BUS2
  81 #define BUS_DMA_BOUNCE_LOWADDR  BUS_DMA_BUS3
  82 #define BUS_DMA_MIN_ALLOC_COMP  BUS_DMA_BUS4
  83
  84 #define BUS_DMA_COULD_BOUNCE    (BUS_DMA_BOUNCE_LOWADDR | BUS_DMA_BOUNCE_ALIGN)
  85
  86 #define BUS_DMAMEM_KMALLOC(dmat) \
  87         ((dmat)->maxsize <= PAGE_SIZE && \
  88          (dmat)->alignment <= PAGE_SIZE && \
  89          (dmat)->lowaddr >= ptoa(Maxmem))
  90
  91 struct bounce_page {
  92         vm_offset_t     vaddr;          /* kva of bounce buffer */
  93         bus_addr_t      busaddr;        /* Physical address */
  94         vm_offset_t     datavaddr;      /* kva of client data */
  95         bus_size_t      datacount;      /* client data count */
  96         STAILQ_ENTRY(bounce_page) links;
  97 };
  98
  99 struct bounce_zone {
 100         STAILQ_ENTRY(bounce_zone) links;
 101         STAILQ_HEAD(bp_list, bounce_page) bounce_page_list;
 102         STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
 103 #ifdef SMP
 104         struct spinlock spin;
 105 #else
 106         int             unused0;
 107 #endif
 108         int             total_bpages;
 109         int             free_bpages;
 110         int             reserved_bpages;
 111         int             active_bpages;
 112         int             total_bounced;
 113         int             total_deferred;
 114         int             reserve_failed;
 115         bus_size_t      alignment;
 116         bus_addr_t      lowaddr;
 117         char            zoneid[8];
 118         char            lowaddrid[20];
 119         struct sysctl_ctx_list sysctl_ctx;
 120         struct sysctl_oid *sysctl_tree;
 121 };
 122
 123 #ifdef SMP
 124 #define BZ_LOCK(bz)     spin_lock_wr(&(bz)->spin)
 125 #define BZ_UNLOCK(bz)   spin_unlock_wr(&(bz)->spin)
 126 #else
 127 #define BZ_LOCK(bz)     crit_enter()
 128 #define BZ_UNLOCK(bz)   crit_exit()
 129 #endif
 130
 131 static struct lwkt_token bounce_zone_tok =
 132         LWKT_TOKEN_INITIALIZER(bounce_zone_tok);
 133 static int busdma_zonecount;
 134 static STAILQ_HEAD(, bounce_zone) bounce_zone_list =
 135         STAILQ_HEAD_INITIALIZER(bounce_zone_list);
 136
 137 int busdma_swi_pending;
 138 static int total_bounce_pages;
 139 static int max_bounce_pages = MAX_BPAGES;
 140 static int bounce_alignment = 1; /* XXX temporary */
 141
 142 TUNABLE_INT("hw.busdma.max_bpages", &max_bounce_pages);
 143 TUNABLE_INT("hw.busdma.bounce_alignment", &bounce_alignment);
 144
 145 struct bus_dmamap {
 146         struct bp_list  bpages;
 147         int             pagesneeded;
 148         int             pagesreserved;
 149         bus_dma_tag_t   dmat;
 150         void            *buf;           /* unmapped buffer pointer */
 151         bus_size_t      buflen;         /* unmapped buffer length */
 152         bus_dmamap_callback_t *callback;
 153         void            *callback_arg;
 154         STAILQ_ENTRY(bus_dmamap) links;
 155 };
 156
 157 static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist =
 158         STAILQ_HEAD_INITIALIZER(bounce_map_callbacklist);
 159
 160 static struct bus_dmamap nobounce_dmamap;
 161
 162 static int              alloc_bounce_zone(bus_dma_tag_t);
 163 static int              alloc_bounce_pages(bus_dma_tag_t, u_int, int);
 164 static int              reserve_bounce_pages(bus_dma_tag_t, bus_dmamap_t, int);
 165 static void             return_bounce_pages(bus_dma_tag_t, bus_dmamap_t);
 166 static bus_addr_t       add_bounce_page(bus_dma_tag_t, bus_dmamap_t,
 167                             vm_offset_t, bus_size_t);
 168 static void             free_bounce_page(bus_dma_tag_t, struct bounce_page *);
 169
 170 static bus_dmamap_t     get_map_waiting(bus_dma_tag_t);
 171 static void             add_map_callback(bus_dmamap_t);
 172
 173 SYSCTL_NODE(_hw, OID_AUTO, busdma, CTLFLAG_RD, 0, "Busdma parameters");
 174 SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bounce_pages,
 175            0, "Total bounce pages");
 176 SYSCTL_INT(_hw_busdma, OID_AUTO, max_bpages, CTLFLAG_RD, &max_bounce_pages,
 177            0, "Max bounce pages per bounce zone");
 178 SYSCTL_INT(_hw_busdma, OID_AUTO, bounce_alignment, CTLFLAG_RD,
 179            &bounce_alignment, 0, "Obey alignment constraint");
 180
 181 static __inline int
 182 run_filter(bus_dma_tag_t dmat, bus_addr_t paddr)
 183 {
 184         int retval;
 185
 186         retval = 0;
 187         do {
 188                 if (((paddr > dmat->lowaddr && paddr <= dmat->highaddr) ||
 189                      (bounce_alignment && (paddr & (dmat->alignment - 1)) != 0))
 190                  && (dmat->filter == NULL ||
 191                      dmat->filter(dmat->filterarg, paddr) != 0))
 192                         retval = 1;
 193
 194                 dmat = dmat->parent;
 195         } while (retval == 0 && dmat != NULL);
 196         return (retval);
 197 }
 198
 199 /*
 200  * Allocate a device specific dma_tag.
 201  */
 202 int
 203 bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 204                    bus_size_t boundary, bus_addr_t lowaddr,
 205                    bus_addr_t highaddr, bus_dma_filter_t *filter,
 206                    void *filterarg, bus_size_t maxsize, int nsegments,
 207                    bus_size_t maxsegsz, int flags, bus_dma_tag_t *dmat)
 208 {
 209         bus_dma_tag_t newtag;
 210         int error = 0;
 211
 212         /*
 213          * Sanity checks
 214          */
 215
 216         if (alignment == 0)
 217                 alignment = 1;
 218         if (alignment & (alignment - 1))
 219                 panic("alignment must be power of 2\n");
 220
 221         if (boundary != 0) {
 222                 if (boundary & (boundary - 1))
 223                         panic("boundary must be power of 2\n");
 224                 if (boundary < maxsegsz) {
 225                         kprintf("boundary < maxsegsz:\n");
 226                         print_backtrace();
 227                         maxsegsz = boundary;
 228                 }
 229         }
 230
 231         /* Return a NULL tag on failure */
 232         *dmat = NULL;
 233
 234         newtag = kmalloc(sizeof(*newtag), M_DEVBUF, M_INTWAIT);
 235
 236         newtag->parent = parent;
 237         newtag->alignment = alignment;
 238         newtag->boundary = boundary;
 239         newtag->lowaddr = trunc_page((vm_paddr_t)lowaddr) + (PAGE_SIZE - 1);
 240         newtag->highaddr = trunc_page((vm_paddr_t)highaddr) + (PAGE_SIZE - 1);
 241         newtag->filter = filter;
 242         newtag->filterarg = filterarg;
 243         newtag->maxsize = maxsize;
 244         newtag->nsegments = nsegments;
 245         newtag->maxsegsz = maxsegsz;
 246         newtag->flags = flags;
 247         newtag->ref_count = 1; /* Count ourself */
 248         newtag->map_count = 0;
 249         newtag->segments = NULL;
 250         newtag->bounce_zone = NULL;
 251
 252         /* Take into account any restrictions imposed by our parent tag */
 253         if (parent != NULL) {
 254                 newtag->lowaddr = MIN(parent->lowaddr, newtag->lowaddr);
 255                 newtag->highaddr = MAX(parent->highaddr, newtag->highaddr);
 256
 257                 if (newtag->boundary == 0) {
 258                         newtag->boundary = parent->boundary;
 259                 } else if (parent->boundary != 0) {
 260                         newtag->boundary = MIN(parent->boundary,
 261                                                newtag->boundary);
 262                 }
 263
 264 #ifdef notyet
 265                 newtag->alignment = MAX(parent->alignment, newtag->alignment);
 266 #endif
 267
 268                 if (newtag->filter == NULL) {
 269                         /*
 270                          * Short circuit looking at our parent directly
 271                          * since we have encapsulated all of its information
 272                          */
 273                         newtag->filter = parent->filter;
 274                         newtag->filterarg = parent->filterarg;
 275                         newtag->parent = parent->parent;
 276                 }
 277                 if (newtag->parent != NULL)
 278                         parent->ref_count++;
 279         }
 280
 281         if (newtag->lowaddr < ptoa(Maxmem))
 282                 newtag->flags |= BUS_DMA_BOUNCE_LOWADDR;
 283         if (bounce_alignment && newtag->alignment > 1 &&
 284             !(newtag->flags & BUS_DMA_ALIGNED))
 285                 newtag->flags |= BUS_DMA_BOUNCE_ALIGN;
 286
 287         if ((newtag->flags & BUS_DMA_COULD_BOUNCE) &&
 288             (flags & BUS_DMA_ALLOCNOW) != 0) {
 289                 struct bounce_zone *bz;
 290
 291                 /* Must bounce */
 292
 293                 error = alloc_bounce_zone(newtag);
 294                 if (error)
 295                         goto back;
 296                 bz = newtag->bounce_zone;
 297
 298                 if (ptoa(bz->total_bpages) < maxsize) {
 299                         int pages;
 300
 301                         if (flags & BUS_DMA_ONEBPAGE) {
 302                                 pages = 1;
 303                         } else {
 304                                 pages = atop(round_page(maxsize)) -
 305                                         bz->total_bpages;
 306                                 pages = MAX(pages, 1);
 307                         }
 308
 309                         /* Add pages to our bounce pool */
 310                         if (alloc_bounce_pages(newtag, pages, flags) < pages)
 311                                 error = ENOMEM;
 312
 313                         /* Performed initial allocation */
 314                         newtag->flags |= BUS_DMA_MIN_ALLOC_COMP;
 315                 }
 316         }
 317 back:
 318         if (error)
 319                 kfree(newtag, M_DEVBUF);
 320         else
 321                 *dmat = newtag;
 322         return error;
 323 }
 324
 325 int
 326 bus_dma_tag_destroy(bus_dma_tag_t dmat)
 327 {
 328         if (dmat != NULL) {
 329                 if (dmat->map_count != 0)
 330                         return (EBUSY);
 331
 332                 while (dmat != NULL) {
 333                         bus_dma_tag_t parent;
 334
 335                         parent = dmat->parent;
 336                         dmat->ref_count--;
 337                         if (dmat->ref_count == 0) {
 338                                 if (dmat->segments != NULL)
 339                                         kfree(dmat->segments, M_DEVBUF);
 340                                 kfree(dmat, M_DEVBUF);
 341                                 /*
 342                                  * Last reference count, so
 343                                  * release our reference
 344                                  * count on our parent.
 345                                  */
 346                                 dmat = parent;
 347                         } else
 348                                 dmat = NULL;
 349                 }
 350         }
 351         return (0);
 352 }
 353
 354 /*
 355  * Allocate a handle for mapping from kva/uva/physical
 356  * address space into bus device space.
 357  */
 358 int
 359 bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
 360 {
 361         int error;
 362
 363         error = 0;
 364
 365         if (dmat->segments == NULL) {
 366                 KKASSERT(dmat->nsegments && dmat->nsegments < 16384);
 367                 dmat->segments = kmalloc(sizeof(bus_dma_segment_t) *
 368                                         dmat->nsegments, M_DEVBUF, M_INTWAIT);
 369         }
 370
 371         if (dmat->flags & BUS_DMA_COULD_BOUNCE) {
 372                 struct bounce_zone *bz;
 373                 int maxpages;
 374
 375                 /* Must bounce */
 376
 377                 if (dmat->bounce_zone == NULL) {
 378                         error = alloc_bounce_zone(dmat);
 379                         if (error)
 380                                 return error;
 381                 }
 382                 bz = dmat->bounce_zone;
 383
 384                 *mapp = kmalloc(sizeof(**mapp), M_DEVBUF, M_INTWAIT | M_ZERO);
 385
 386                 /* Initialize the new map */
 387                 STAILQ_INIT(&((*mapp)->bpages));
 388
 389                 /*
 390                  * Attempt to add pages to our pool on a per-instance
 391                  * basis up to a sane limit.
 392                  */
 393                 if (dmat->flags & BUS_DMA_BOUNCE_ALIGN) {
 394                         maxpages = max_bounce_pages;
 395                 } else {
 396                         maxpages = MIN(max_bounce_pages,
 397                                        Maxmem - atop(dmat->lowaddr));
 398                 }
 399                 if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
 400                  || (dmat->map_count > 0
 401                   && bz->total_bpages < maxpages)) {
 402                         int pages;
 403
 404                         if (flags & BUS_DMA_ONEBPAGE) {
 405                                 pages = 1;
 406                         } else {
 407                                 pages = atop(round_page(dmat->maxsize));
 408                                 pages = MIN(maxpages - bz->total_bpages, pages);
 409                                 pages = MAX(pages, 1);
 410                         }
 411                         if (alloc_bounce_pages(dmat, pages, flags) < pages)
 412                                 error = ENOMEM;
 413
 414                         if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0) {
 415                                 if (!error)
 416                                         dmat->flags |= BUS_DMA_MIN_ALLOC_COMP;
 417                         } else {
 418                                 error = 0;
 419                         }
 420                 }
 421         } else {
 422                 *mapp = NULL;
 423         }
 424         if (!error)
 425                 dmat->map_count++;
 426         return error;
 427 }
 428
 429 /*
 430  * Destroy a handle for mapping from kva/uva/physical
 431  * address space into bus device space.
 432  */
 433 int
 434 bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
 435 {
 436         if (map != NULL) {
 437                 if (STAILQ_FIRST(&map->bpages) != NULL)
 438                         return (EBUSY);
 439                 kfree(map, M_DEVBUF);
 440         }
 441         dmat->map_count--;
 442         return (0);
 443 }
 444
 445 static __inline bus_size_t
 446 check_kmalloc(bus_dma_tag_t dmat, const void *vaddr0, int verify)
 447 {
 448         bus_size_t maxsize = 0;
 449         uintptr_t vaddr = (uintptr_t)vaddr0;
 450
 451         if ((vaddr ^ (vaddr + dmat->maxsize - 1)) & ~PAGE_MASK) {
 452                 if (verify || bootverbose)
 453                         kprintf("boundary check failed\n");
 454                 if (verify)
 455                         print_backtrace(); /* XXX panic */
 456                 maxsize = dmat->maxsize;
 457         }
 458         if (vaddr & (dmat->alignment - 1)) {
 459                 if (verify || bootverbose)
 460                         kprintf("alignment check failed\n");
 461                 if (verify)
 462                         print_backtrace(); /* XXX panic */
 463                 if (dmat->maxsize < dmat->alignment)
 464                         maxsize = dmat->alignment;
 465                 else
 466                         maxsize = dmat->maxsize;
 467         }
 468         return maxsize;
 469 }
 470
 471 /*
 472  * Allocate a piece of memory that can be efficiently mapped into
 473  * bus device space based on the constraints lited in the dma tag.
 474  *
 475  * mapp is degenerate.  By definition this allocation should not require
 476  * bounce buffers so do not allocate a dma map.
 477  */
 478 int
 479 bus_dmamem_alloc(bus_dma_tag_t dmat, void **vaddr, int flags,
 480                  bus_dmamap_t *mapp)
 481 {
 482         int mflags;
 483
 484         /* If we succeed, no mapping/bouncing will be required */
 485         *mapp = NULL;
 486
 487         if (dmat->segments == NULL) {
 488                 KKASSERT(dmat->nsegments < 16384);
 489                 dmat->segments = kmalloc(sizeof(bus_dma_segment_t) *
 490                                         dmat->nsegments, M_DEVBUF, M_INTWAIT);
 491         }
 492
 493         if (flags & BUS_DMA_NOWAIT)
 494                 mflags = M_NOWAIT;
 495         else
 496                 mflags = M_WAITOK;
 497         if (flags & BUS_DMA_ZERO)
 498                 mflags |= M_ZERO;
 499
 500         if (BUS_DMAMEM_KMALLOC(dmat)) {
 501                 bus_size_t maxsize;
 502
 503                 *vaddr = kmalloc(dmat->maxsize, M_DEVBUF, mflags);
 504
 505                 /*
 506                  * XXX
 507                  * Check whether the allocation
 508                  * - crossed a page boundary
 509                  * - was not aligned
 510                  * Retry with power-of-2 alignment in the above cases.
 511                  */
 512                 maxsize = check_kmalloc(dmat, *vaddr, 0);
 513                 if (maxsize) {
 514                         size_t size;
 515
 516                         kfree(*vaddr, M_DEVBUF);
 517                         /* XXX check for overflow? */
 518                         for (size = 1; size <= maxsize; size <<= 1)
 519                                 ;
 520                         *vaddr = kmalloc(size, M_DEVBUF, mflags);
 521                         check_kmalloc(dmat, *vaddr, 1);
 522                 }
 523         } else {
 524                 /*
 525                  * XXX Use Contigmalloc until it is merged into this facility
 526                  *     and handles multi-seg allocations.  Nobody is doing
 527                  *     multi-seg allocations yet though.
 528                  */
 529                 *vaddr = contigmalloc(dmat->maxsize, M_DEVBUF, mflags,
 530                     0ul, dmat->lowaddr, dmat->alignment, dmat->boundary);
 531         }
 532         if (*vaddr == NULL)
 533                 return (ENOMEM);
 534         return (0);
 535 }
 536
 537 /*
 538  * Free a piece of memory and it's allociated dmamap, that was allocated
 539  * via bus_dmamem_alloc.  Make the same choice for free/contigfree.
 540  */
 541 void
 542 bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
 543 {
 544         /*
 545          * dmamem does not need to be bounced, so the map should be
 546          * NULL
 547          */
 548         if (map != NULL)
 549                 panic("bus_dmamem_free: Invalid map freed\n");
 550         if (BUS_DMAMEM_KMALLOC(dmat))
 551                 kfree(vaddr, M_DEVBUF);
 552         else
 553                 contigfree(vaddr, dmat->maxsize, M_DEVBUF);
 554 }
 555
 556 static __inline vm_paddr_t
 557 _bus_dma_extract(pmap_t pmap, vm_offset_t vaddr)
 558 {
 559         if (pmap)
 560                 return pmap_extract(pmap, vaddr);
 561         else
 562                 return pmap_kextract(vaddr);
 563 }
 564
 565 /*
 566  * Utility function to load a linear buffer.  lastaddrp holds state
 567  * between invocations (for multiple-buffer loads).  segp contains
 568  * the segment following the starting one on entrace, and the ending
 569  * segment on exit.  first indicates if this is the first invocation
 570  * of this function.
 571  */
 572 static int
 573 _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
 574                         bus_dmamap_t map,
 575                         void *buf, bus_size_t buflen,
 576                         bus_dma_segment_t *segments,
 577                         int nsegments,
 578                         pmap_t pmap,
 579                         int flags,
 580                         vm_paddr_t *lastpaddrp,
 581                         int *segp,
 582                         int first)
 583 {
 584         vm_offset_t vaddr;
 585         vm_paddr_t paddr, nextpaddr;
 586         bus_dma_segment_t *sg;
 587         bus_addr_t bmask;
 588         int seg, error = 0;
 589
 590         if (map == NULL)
 591                 map = &nobounce_dmamap;
 592
 593 #ifdef INVARIANTS
 594         if (dmat->flags & BUS_DMA_ALIGNED)
 595                 KKASSERT(((uintptr_t)buf & (dmat->alignment - 1)) == 0);
 596 #endif
 597
 598         /*
 599          * If we are being called during a callback, pagesneeded will
 600          * be non-zero, so we can avoid doing the work twice.
 601          */
 602         if ((dmat->flags & BUS_DMA_COULD_BOUNCE) &&
 603             map != &nobounce_dmamap && map->pagesneeded == 0) {
 604                 vm_offset_t vendaddr;
 605
 606                 /*
 607                  * Count the number of bounce pages
 608                  * needed in order to complete this transfer
 609                  */
 610                 vaddr = (vm_offset_t)buf;
 611                 vendaddr = (vm_offset_t)buf + buflen;
 612
 613                 while (vaddr < vendaddr) {
 614                         paddr = _bus_dma_extract(pmap, vaddr);
 615                         if (run_filter(dmat, paddr) != 0)
 616                                 map->pagesneeded++;
 617                         vaddr += (PAGE_SIZE - ((vm_offset_t)vaddr & PAGE_MASK));
 618                 }
 619         }
 620
 621         /* Reserve Necessary Bounce Pages */
 622         if (map->pagesneeded != 0) {
 623                 struct bounce_zone *bz;
 624
 625                 bz = dmat->bounce_zone;
 626                 BZ_LOCK(bz);
 627                 if (flags & BUS_DMA_NOWAIT) {
 628                         if (reserve_bounce_pages(dmat, map, 0) != 0) {
 629                                 BZ_UNLOCK(bz);
 630                                 error = ENOMEM;
 631                                 goto free_bounce;
 632                         }
 633                 } else {
 634                         if (reserve_bounce_pages(dmat, map, 1) != 0) {
 635                                 /* Queue us for resources */
 636                                 map->dmat = dmat;
 637                                 map->buf = buf;
 638                                 map->buflen = buflen;
 639
 640                                 STAILQ_INSERT_TAIL(
 641                                     &dmat->bounce_zone->bounce_map_waitinglist,
 642                                     map, links);
 643                                 BZ_UNLOCK(bz);
 644
 645                                 return (EINPROGRESS);
 646                         }
 647                 }
 648                 BZ_UNLOCK(bz);
 649         }
 650
 651         KKASSERT(*segp >= 1 && *segp <= nsegments);
 652         seg = *segp;
 653         sg = &segments[seg - 1];
 654
 655         vaddr = (vm_offset_t)buf;
 656         nextpaddr = *lastpaddrp;
 657         bmask = ~(dmat->boundary - 1);  /* note: will be 0 if boundary is 0 */
 658
 659         /* force at least one segment */
 660         do {
 661                 bus_size_t size;
 662
 663                 /*
 664                  * Per-page main loop
 665                  */
 666                 paddr = _bus_dma_extract(pmap, vaddr);
 667                 size = PAGE_SIZE - (paddr & PAGE_MASK);
 668                 if (size > buflen)
 669                         size = buflen;
 670                 if (map->pagesneeded != 0 && run_filter(dmat, paddr)) {
 671                         /*
 672                          * note: this paddr has the same in-page offset
 673                          * as vaddr and thus the paddr above, so the
 674                          * size does not have to be recalculated
 675                          */
 676                         paddr = add_bounce_page(dmat, map, vaddr, size);
 677                 }
 678
 679                 /*
 680                  * Fill in the bus_dma_segment
 681                  */
 682                 if (first) {
 683                         sg->ds_addr = paddr;
 684                         sg->ds_len = size;
 685                         first = 0;
 686                 } else if (paddr == nextpaddr) {
 687                         sg->ds_len += size;
 688                 } else {
 689                         sg++;
 690                         seg++;
 691                         if (seg > nsegments)
 692                                 break;
 693                         sg->ds_addr = paddr;
 694                         sg->ds_len = size;
 695                 }
 696                 nextpaddr = paddr + size;
 697
 698                 /*
 699                  * Handle maxsegsz and boundary issues with a nested loop
 700                  */
 701                 for (;;) {
 702                         bus_size_t tmpsize;
 703
 704                         /*
 705                          * Limit to the boundary and maximum segment size
 706                          */
 707                         if (((nextpaddr - 1) ^ sg->ds_addr) & bmask) {
 708                                 tmpsize = dmat->boundary -
 709                                           (sg->ds_addr & ~bmask);
 710                                 if (tmpsize > dmat->maxsegsz)
 711                                         tmpsize = dmat->maxsegsz;
 712                                 KKASSERT(tmpsize < sg->ds_len);
 713                         } else if (sg->ds_len > dmat->maxsegsz) {
 714                                 tmpsize = dmat->maxsegsz;
 715                         } else {
 716                                 break;
 717                         }
 718
 719                         /*
 720                          * Futz, split the data into a new segment.
 721                          */
 722                         if (seg >= nsegments)
 723                                 goto fail;
 724                         sg[1].ds_len = sg[0].ds_len - tmpsize;
 725                         sg[1].ds_addr = sg[0].ds_addr + tmpsize;
 726                         sg[0].ds_len = tmpsize;
 727                         sg++;
 728                         seg++;
 729                 }
 730
 731                 /*
 732                  * Adjust for loop
 733                  */
 734                 buflen -= size;
 735                 vaddr += size;
 736         } while (buflen > 0);
 737 fail:
 738         if (buflen != 0)
 739                 error = EFBIG;
 740
 741         *segp = seg;
 742         *lastpaddrp = nextpaddr;
 743
 744 free_bounce:
 745         if (error && (dmat->flags & BUS_DMA_COULD_BOUNCE) &&
 746             map != &nobounce_dmamap) {
 747                 _bus_dmamap_unload(dmat, map);
 748                 return_bounce_pages(dmat, map);
 749         }
 750         return error;
 751 }
 752
 753 /*
 754  * Map the buffer buf into bus space using the dmamap map.
 755  */
 756 int
 757 bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
 758                 bus_size_t buflen, bus_dmamap_callback_t *callback,
 759                 void *callback_arg, int flags)
 760 {
 761         vm_paddr_t lastaddr = 0;
 762         int error, nsegs = 1;
 763
 764         if (map != NULL) {
 765                 /*
 766                  * XXX
 767                  * Follow old semantics.  Once all of the callers are fixed,
 768                  * we should get rid of these internal flag "adjustment".
 769                  */
 770                 flags &= ~BUS_DMA_NOWAIT;
 771                 flags |= BUS_DMA_WAITOK;
 772
 773                 map->callback = callback;
 774                 map->callback_arg = callback_arg;
 775         }
 776
 777         error = _bus_dmamap_load_buffer(dmat, map, buf, buflen,
 778                         dmat->segments, dmat->nsegments,
 779                         NULL, flags, &lastaddr, &nsegs, 1);
 780         if (error == EINPROGRESS)
 781                 return error;
 782
 783         callback(callback_arg, dmat->segments, nsegs, error);
 784         return 0;
 785 }
 786
 787 /*
 788  * Like _bus_dmamap_load(), but for mbufs.
 789  */
 790 int
 791 bus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map,
 792                      struct mbuf *m0,
 793                      bus_dmamap_callback2_t *callback, void *callback_arg,
 794                      int flags)
 795 {
 796         int nsegs, error;
 797
 798         /*
 799          * XXX
 800          * Follow old semantics.  Once all of the callers are fixed,
 801          * we should get rid of these internal flag "adjustment".
 802          */
 803         flags &= ~BUS_DMA_WAITOK;
 804         flags |= BUS_DMA_NOWAIT;
 805
 806         error = bus_dmamap_load_mbuf_segment(dmat, map, m0,
 807                         dmat->segments, dmat->nsegments, &nsegs, flags);
 808         if (error) {
 809                 /* force "no valid mappings" in callback */
 810                 callback(callback_arg, dmat->segments, 0, 0, error);
 811         } else {
 812                 callback(callback_arg, dmat->segments, nsegs,
 813                          m0->m_pkthdr.len, error);
 814         }
 815         return error;
 816 }
 817
 818 int
 819 bus_dmamap_load_mbuf_segment(bus_dma_tag_t dmat, bus_dmamap_t map,
 820                              struct mbuf *m0,
 821                              bus_dma_segment_t *segs, int maxsegs,
 822                              int *nsegs, int flags)
 823 {
 824         int error;
 825
 826         M_ASSERTPKTHDR(m0);
 827
 828         KASSERT(maxsegs >= 1, ("invalid maxsegs %d\n", maxsegs));
 829         KASSERT(maxsegs <= dmat->nsegments,
 830                 ("%d too many segments, dmat only support %d segments\n",
 831                  maxsegs, dmat->nsegments));
 832         KASSERT(flags & BUS_DMA_NOWAIT,
 833                 ("only BUS_DMA_NOWAIT is supported\n"));
 834
 835         if (m0->m_pkthdr.len <= dmat->maxsize) {
 836                 int first = 1;
 837                 vm_paddr_t lastaddr = 0;
 838                 struct mbuf *m;
 839
 840                 *nsegs = 1;
 841                 error = 0;
 842                 for (m = m0; m != NULL && error == 0; m = m->m_next) {
 843                         if (m->m_len == 0)
 844                                 continue;
 845
 846                         error = _bus_dmamap_load_buffer(dmat, map,
 847                                         m->m_data, m->m_len,
 848                                         segs, maxsegs,
 849                                         NULL, flags, &lastaddr,
 850                                         nsegs, first);
 851                         if (error == ENOMEM && !first) {
 852                                 /*
 853                                  * Out of bounce pages due to too many
 854                                  * fragments in the mbuf chain; return
 855                                  * EFBIG instead.
 856                                  */
 857                                 error = EFBIG;
 858                         }
 859                         first = 0;
 860                 }
 861 #ifdef INVARIANTS
 862                 if (!error)
 863                         KKASSERT(*nsegs <= maxsegs && *nsegs >= 1);
 864 #endif
 865         } else {
 866                 *nsegs = 0;
 867                 error = EINVAL;
 868         }
 869         KKASSERT(error != EINPROGRESS);
 870         return error;
 871 }
 872
 873 /*
 874  * Like _bus_dmamap_load(), but for uios.
 875  */
 876 int
 877 bus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map,
 878                     struct uio *uio,
 879                     bus_dmamap_callback2_t *callback, void *callback_arg,
 880                     int flags)
 881 {
 882         vm_paddr_t lastaddr;
 883         int nsegs, error, first, i;
 884         bus_size_t resid;
 885         struct iovec *iov;
 886         pmap_t pmap;
 887
 888         /*
 889          * XXX
 890          * Follow old semantics.  Once all of the callers are fixed,
 891          * we should get rid of these internal flag "adjustment".
 892          */
 893         flags &= ~BUS_DMA_WAITOK;
 894         flags |= BUS_DMA_NOWAIT;
 895
 896         resid = (bus_size_t)uio->uio_resid;
 897         iov = uio->uio_iov;
 898
 899         if (uio->uio_segflg == UIO_USERSPACE) {
 900                 struct thread *td;
 901
 902                 td = uio->uio_td;
 903                 KASSERT(td != NULL && td->td_proc != NULL,
 904                         ("bus_dmamap_load_uio: USERSPACE but no proc"));
 905                 pmap = vmspace_pmap(td->td_proc->p_vmspace);
 906         } else {
 907                 pmap = NULL;
 908         }
 909
 910         error = 0;
 911         nsegs = 1;
 912         first = 1;
 913         lastaddr = 0;
 914         for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
 915                 /*
 916                  * Now at the first iovec to load.  Load each iovec
 917                  * until we have exhausted the residual count.
 918                  */
 919                 bus_size_t minlen =
 920                         resid < iov[i].iov_len ? resid : iov[i].iov_len;
 921                 caddr_t addr = (caddr_t) iov[i].iov_base;
 922
 923                 error = _bus_dmamap_load_buffer(dmat, map, addr, minlen,
 924                                 dmat->segments, dmat->nsegments,
 925                                 pmap, flags, &lastaddr, &nsegs, first);
 926                 first = 0;
 927
 928                 resid -= minlen;
 929         }
 930
 931         if (error) {
 932                 /* force "no valid mappings" in callback */
 933                 callback(callback_arg, dmat->segments, 0, 0, error);
 934         } else {
 935                 callback(callback_arg, dmat->segments, nsegs,
 936                          (bus_size_t)uio->uio_resid, error);
 937         }
 938         return error;
 939 }
 940
 941 /*
 942  * Release the mapping held by map.
 943  */
 944 void
 945 _bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
 946 {
 947         struct bounce_page *bpage;
 948
 949         while ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
 950                 STAILQ_REMOVE_HEAD(&map->bpages, links);
 951                 free_bounce_page(dmat, bpage);
 952         }
 953 }
 954
 955 void
 956 _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
 957 {
 958         struct bounce_page *bpage;
 959
 960         if ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
 961                 /*
 962                  * Handle data bouncing.  We might also
 963                  * want to add support for invalidating
 964                  * the caches on broken hardware
 965                  */
 966                 switch (op) {
 967                 case BUS_DMASYNC_PREWRITE:
 968                         while (bpage != NULL) {
 969                                 bcopy((void *)bpage->datavaddr,
 970                                       (void *)bpage->vaddr,
 971                                       bpage->datacount);
 972                                 bpage = STAILQ_NEXT(bpage, links);
 973                         }
 974                         dmat->bounce_zone->total_bounced++;
 975                         break;
 976
 977                 case BUS_DMASYNC_POSTREAD:
 978                         while (bpage != NULL) {
 979                                 bcopy((void *)bpage->vaddr,
 980                                       (void *)bpage->datavaddr,
 981                                       bpage->datacount);
 982                                 bpage = STAILQ_NEXT(bpage, links);
 983                         }
 984                         dmat->bounce_zone->total_bounced++;
 985                         break;
 986
 987                 case BUS_DMASYNC_PREREAD:
 988                 case BUS_DMASYNC_POSTWRITE:
 989                         /* No-ops */
 990                         break;
 991                 }
 992         }
 993 }
 994
 995 static int
 996 alloc_bounce_zone(bus_dma_tag_t dmat)
 997 {
 998         struct bounce_zone *bz, *new_bz;
 999         lwkt_tokref ref;
1000
1001         KASSERT(dmat->bounce_zone == NULL,
1002                 ("bounce zone was already assigned\n"));
1003
1004         new_bz = kmalloc(sizeof(*new_bz), M_DEVBUF, M_INTWAIT | M_ZERO);
1005
1006         lwkt_gettoken(&ref, &bounce_zone_tok);
1007
1008         /* Check to see if we already have a suitable zone */
1009         STAILQ_FOREACH(bz, &bounce_zone_list, links) {
1010                 if (dmat->alignment <= bz->alignment &&
1011                     dmat->lowaddr >= bz->lowaddr) {
1012                         lwkt_reltoken(&ref);
1013
1014                         dmat->bounce_zone = bz;
1015                         kfree(new_bz, M_DEVBUF);
1016                         return 0;
1017                 }
1018         }
1019         bz = new_bz;
1020
1021 #ifdef SMP
1022         spin_init(&bz->spin);
1023 #endif
1024         STAILQ_INIT(&bz->bounce_page_list);
1025         STAILQ_INIT(&bz->bounce_map_waitinglist);
1026         bz->free_bpages = 0;
1027         bz->reserved_bpages = 0;
1028         bz->active_bpages = 0;
1029         bz->lowaddr = dmat->lowaddr;
1030         bz->alignment = round_page(dmat->alignment);
1031         ksnprintf(bz->zoneid, 8, "zone%d", busdma_zonecount);
1032         busdma_zonecount++;
1033         ksnprintf(bz->lowaddrid, 18, "%#jx", (uintmax_t)bz->lowaddr);
1034         STAILQ_INSERT_TAIL(&bounce_zone_list, bz, links);
1035
1036         lwkt_reltoken(&ref);
1037
1038         dmat->bounce_zone = bz;
1039
1040         sysctl_ctx_init(&bz->sysctl_ctx);
1041         bz->sysctl_tree = SYSCTL_ADD_NODE(&bz->sysctl_ctx,
1042             SYSCTL_STATIC_CHILDREN(_hw_busdma), OID_AUTO, bz->zoneid,
1043             CTLFLAG_RD, 0, "");
1044         if (bz->sysctl_tree == NULL) {
1045                 sysctl_ctx_free(&bz->sysctl_ctx);
1046                 return 0;       /* XXX error code? */
1047         }
1048
1049         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1050             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1051             "total_bpages", CTLFLAG_RD, &bz->total_bpages, 0,
1052             "Total bounce pages");
1053         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1054             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1055             "free_bpages", CTLFLAG_RD, &bz->free_bpages, 0,
1056             "Free bounce pages");
1057         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1058             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1059             "reserved_bpages", CTLFLAG_RD, &bz->reserved_bpages, 0,
1060             "Reserved bounce pages");
1061         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1062             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1063             "active_bpages", CTLFLAG_RD, &bz->active_bpages, 0,
1064             "Active bounce pages");
1065         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1066             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1067             "total_bounced", CTLFLAG_RD, &bz->total_bounced, 0,
1068             "Total bounce requests");
1069         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1070             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1071             "total_deferred", CTLFLAG_RD, &bz->total_deferred, 0,
1072             "Total bounce requests that were deferred");
1073         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1074             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1075             "reserve_failed", CTLFLAG_RD, &bz->reserve_failed, 0,
1076             "Total bounce page reservations that were failed");
1077         SYSCTL_ADD_STRING(&bz->sysctl_ctx,
1078             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1079             "lowaddr", CTLFLAG_RD, bz->lowaddrid, 0, "");
1080         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1081             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1082             "alignment", CTLFLAG_RD, &bz->alignment, 0, "");
1083
1084         return 0;
1085 }
1086
1087 static int
1088 alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages, int flags)
1089 {
1090         struct bounce_zone *bz = dmat->bounce_zone;
1091         int count = 0, mflags;
1092
1093         if (flags & BUS_DMA_NOWAIT)
1094                 mflags = M_NOWAIT;
1095         else
1096                 mflags = M_WAITOK;
1097
1098         while (numpages > 0) {
1099                 struct bounce_page *bpage;
1100
1101                 bpage = kmalloc(sizeof(*bpage), M_DEVBUF, M_INTWAIT | M_ZERO);
1102
1103                 bpage->vaddr = (vm_offset_t)contigmalloc(PAGE_SIZE, M_DEVBUF,
1104                                                          mflags, 0ul,
1105                                                          bz->lowaddr,
1106                                                          bz->alignment, 0);
1107                 if (bpage->vaddr == 0) {
1108                         kfree(bpage, M_DEVBUF);
1109                         break;
1110                 }
1111                 bpage->busaddr = pmap_kextract(bpage->vaddr);
1112
1113                 BZ_LOCK(bz);
1114                 STAILQ_INSERT_TAIL(&bz->bounce_page_list, bpage, links);
1115                 total_bounce_pages++;
1116                 bz->total_bpages++;
1117                 bz->free_bpages++;
1118                 BZ_UNLOCK(bz);
1119
1120                 count++;
1121                 numpages--;
1122         }
1123         return count;
1124 }
1125
1126 /* Assume caller holds bounce zone spinlock */
1127 static int
1128 reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int commit)
1129 {
1130         struct bounce_zone *bz = dmat->bounce_zone;
1131         int pages;
1132
1133         pages = MIN(bz->free_bpages, map->pagesneeded - map->pagesreserved);
1134         if (!commit && map->pagesneeded > (map->pagesreserved + pages)) {
1135                 bz->reserve_failed++;
1136                 return (map->pagesneeded - (map->pagesreserved + pages));
1137         }
1138
1139         bz->free_bpages -= pages;
1140
1141         bz->reserved_bpages += pages;
1142         KKASSERT(bz->reserved_bpages <= bz->total_bpages);
1143
1144         map->pagesreserved += pages;
1145         pages = map->pagesneeded - map->pagesreserved;
1146
1147         return pages;
1148 }
1149
1150 static void
1151 return_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map)
1152 {
1153         struct bounce_zone *bz = dmat->bounce_zone;
1154         int reserved = map->pagesreserved;
1155         bus_dmamap_t wait_map;
1156
1157         map->pagesreserved = 0;
1158         map->pagesneeded = 0;
1159
1160         if (reserved == 0)
1161                 return;
1162
1163         BZ_LOCK(bz);
1164
1165         bz->free_bpages += reserved;
1166         KKASSERT(bz->free_bpages <= bz->total_bpages);
1167
1168         KKASSERT(bz->reserved_bpages >= reserved);
1169         bz->reserved_bpages -= reserved;
1170
1171         wait_map = get_map_waiting(dmat);
1172
1173         BZ_UNLOCK(bz);
1174
1175         if (wait_map != NULL)
1176                 add_map_callback(map);
1177 }
1178
1179 static bus_addr_t
1180 add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
1181                 bus_size_t size)
1182 {
1183         struct bounce_zone *bz = dmat->bounce_zone;
1184         struct bounce_page *bpage;
1185
1186         KASSERT(map->pagesneeded > 0, ("map doesn't need any pages"));
1187         map->pagesneeded--;
1188
1189         KASSERT(map->pagesreserved > 0, ("map doesn't reserve any pages"));
1190         map->pagesreserved--;
1191
1192         BZ_LOCK(bz);
1193
1194         bpage = STAILQ_FIRST(&bz->bounce_page_list);
1195         KASSERT(bpage != NULL, ("free page list is empty"));
1196         STAILQ_REMOVE_HEAD(&bz->bounce_page_list, links);
1197
1198         KKASSERT(bz->reserved_bpages > 0);
1199         bz->reserved_bpages--;
1200
1201         bz->active_bpages++;
1202         KKASSERT(bz->active_bpages <= bz->total_bpages);
1203
1204         BZ_UNLOCK(bz);
1205
1206         bpage->datavaddr = vaddr;
1207         bpage->datacount = size;
1208         STAILQ_INSERT_TAIL(&map->bpages, bpage, links);
1209         return bpage->busaddr;
1210 }
1211
1212 static void
1213 free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
1214 {
1215         struct bounce_zone *bz = dmat->bounce_zone;
1216         bus_dmamap_t map;
1217
1218         bpage->datavaddr = 0;
1219         bpage->datacount = 0;
1220
1221         BZ_LOCK(bz);
1222
1223         STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
1224
1225         bz->free_bpages++;
1226         KKASSERT(bz->free_bpages <= bz->total_bpages);
1227
1228         KKASSERT(bz->active_bpages > 0);
1229         bz->active_bpages--;
1230
1231         map = get_map_waiting(dmat);
1232
1233         BZ_UNLOCK(bz);
1234
1235         if (map != NULL)
1236                 add_map_callback(map);
1237 }
1238
1239 /* Assume caller holds bounce zone spinlock */
1240 static bus_dmamap_t
1241 get_map_waiting(bus_dma_tag_t dmat)
1242 {
1243         struct bounce_zone *bz = dmat->bounce_zone;
1244         bus_dmamap_t map;
1245
1246         map = STAILQ_FIRST(&bz->bounce_map_waitinglist);
1247         if (map != NULL) {
1248                 if (reserve_bounce_pages(map->dmat, map, 1) == 0) {
1249                         STAILQ_REMOVE_HEAD(&bz->bounce_map_waitinglist, links);
1250                         bz->total_deferred++;
1251                 } else {
1252                         map = NULL;
1253                 }
1254         }
1255         return map;
1256 }
1257
1258 static void
1259 add_map_callback(bus_dmamap_t map)
1260 {
1261 #ifdef notyet
1262         /* XXX callbacklist is not MPSAFE */
1263         crit_enter();
1264         get_mplock();
1265         STAILQ_INSERT_TAIL(&bounce_map_callbacklist, map, links);
1266         busdma_swi_pending = 1;
1267         setsoftvm();
1268         rel_mplock();
1269         crit_exit();
1270 #else
1271         panic("%s uncoded\n", __func__);
1272 #endif
1273 }
1274
1275 #ifdef notyet
1276 void
1277 busdma_swi(void)
1278 {
1279         bus_dmamap_t map;
1280
1281         crit_enter();
1282         while ((map = STAILQ_FIRST(&bounce_map_callbacklist)) != NULL) {
1283                 STAILQ_REMOVE_HEAD(&bounce_map_callbacklist, links);
1284                 crit_exit();
1285                 bus_dmamap_load(map->dmat, map, map->buf, map->buflen,
1286                                 map->callback, map->callback_arg, /*flags*/0);
1287                 crit_enter();
1288         }
1289         crit_exit();
1290 }
1291 #endif