sys/platform/pc32/i386/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 1.16.2.2 2003/01/23 00:55:27 scottl 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/thread2.h>
  36 #include <sys/bus_dma.h>
  37 #include <sys/kernel.h>
  38 #include <sys/sysctl.h>
  39 #include <sys/lock.h>
  40 #include <sys/spinlock2.h>
  41
  42 #include <vm/vm.h>
  43 #include <vm/vm_page.h>
  44
  45 /* XXX needed for to access pmap to convert per-proc virtual to physical */
  46 #include <sys/proc.h>
  47 #include <sys/lock.h>
  48 #include <vm/vm_map.h>
  49
  50 #include <machine/md_var.h>
  51
  52 #define MAX_BPAGES      1024
  53
  54 struct bounce_zone;
  55 struct bus_dmamap;
  56
  57 struct bus_dma_tag {
  58         bus_dma_tag_t   parent;
  59         bus_size_t      alignment;
  60         bus_size_t      boundary;
  61         bus_addr_t      lowaddr;
  62         bus_addr_t      highaddr;
  63         bus_dma_filter_t *filter;
  64         void            *filterarg;
  65         bus_size_t      maxsize;
  66         u_int           nsegments;
  67         bus_size_t      maxsegsz;
  68         int             flags;
  69         int             ref_count;
  70         int             map_count;
  71         bus_dma_segment_t *segments;
  72         struct bounce_zone *bounce_zone;
  73 };
  74
  75 /*
  76  * bus_dma_tag private flags
  77  */
  78 #define BUS_DMA_BOUNCE_ALIGN    BUS_DMA_BUS2
  79 #define BUS_DMA_BOUNCE_LOWADDR  BUS_DMA_BUS3
  80 #define BUS_DMA_MIN_ALLOC_COMP  BUS_DMA_BUS4
  81
  82 #define BUS_DMA_COULD_BOUNCE    (BUS_DMA_BOUNCE_LOWADDR | BUS_DMA_BOUNCE_ALIGN)
  83
  84 #define BUS_DMAMEM_KMALLOC(dmat) \
  85         ((dmat)->maxsize <= PAGE_SIZE && \
  86          (dmat)->alignment <= PAGE_SIZE && \
  87          (dmat)->lowaddr >= ptoa(Maxmem))
  88
  89 struct bounce_page {
  90         vm_offset_t     vaddr;          /* kva of bounce buffer */
  91         bus_addr_t      busaddr;        /* Physical address */
  92         vm_offset_t     datavaddr;      /* kva of client data */
  93         bus_size_t      datacount;      /* client data count */
  94         STAILQ_ENTRY(bounce_page) links;
  95 };
  96
  97 struct bounce_zone {
  98         STAILQ_ENTRY(bounce_zone) links;
  99         STAILQ_HEAD(bp_list, bounce_page) bounce_page_list;
 100         STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
 101 #ifdef SMP
 102         struct spinlock spin;
 103 #else
 104         int             unused0;
 105 #endif
 106         int             total_bpages;
 107         int             free_bpages;
 108         int             reserved_bpages;
 109         int             active_bpages;
 110         int             total_bounced;
 111         int             total_deferred;
 112         int             reserve_failed;
 113         bus_size_t      alignment;
 114         bus_size_t      boundary;
 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_wr(&(bz)->spin)
 124 #define BZ_UNLOCK(bz)   spin_unlock_wr(&(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_tok);
 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 = 0; /* 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, alignment, CTLFLAG_RD, &bounce_alignment,
 178            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\n");
 219
 220         if (boundary != 0) {
 221                 if (boundary & (boundary - 1))
 222                         panic("boundary must be power of 2\n");
 223                 if (boundary < maxsegsz) {
 224                         kprintf("boundary < maxsegsz:\n");
 225                         backtrace();
 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                 kprintf("boundary check failed\n");
 452                 if (verify)
 453                         backtrace(); /* XXX panic */
 454                 maxsize = dmat->maxsize;
 455         }
 456         if (vaddr & (dmat->alignment - 1)) {
 457                 kprintf("alignment check failed\n");
 458                 if (verify)
 459                         backtrace(); /* XXX panic */
 460                 if (dmat->maxsize < dmat->alignment)
 461                         maxsize = dmat->alignment;
 462                 else
 463                         maxsize = dmat->maxsize;
 464         }
 465         return maxsize;
 466 }
 467
 468 /*
 469  * Allocate a piece of memory that can be efficiently mapped into
 470  * bus device space based on the constraints lited in the dma tag.
 471  *
 472  * mapp is degenerate.  By definition this allocation should not require
 473  * bounce buffers so do not allocate a dma map.
 474  */
 475 int
 476 bus_dmamem_alloc(bus_dma_tag_t dmat, void **vaddr, int flags,
 477                  bus_dmamap_t *mapp)
 478 {
 479         int mflags;
 480
 481         /* If we succeed, no mapping/bouncing will be required */
 482         *mapp = NULL;
 483
 484         if (dmat->segments == NULL) {
 485                 KKASSERT(dmat->nsegments < 16384);
 486                 dmat->segments = kmalloc(sizeof(bus_dma_segment_t) *
 487                                         dmat->nsegments, M_DEVBUF, M_INTWAIT);
 488         }
 489
 490         if (flags & BUS_DMA_NOWAIT)
 491                 mflags = M_NOWAIT;
 492         else
 493                 mflags = M_WAITOK;
 494         if (flags & BUS_DMA_ZERO)
 495                 mflags |= M_ZERO;
 496
 497         if (BUS_DMAMEM_KMALLOC(dmat)) {
 498                 bus_size_t maxsize;
 499
 500                 *vaddr = kmalloc(dmat->maxsize, M_DEVBUF, mflags);
 501
 502                 /*
 503                  * XXX
 504                  * Check whether the allocation
 505                  * - crossed a page boundary
 506                  * - was not aligned
 507                  * Retry with power-of-2 alignment in the above cases.
 508                  */
 509                 maxsize = check_kmalloc(dmat, *vaddr, 0);
 510                 if (maxsize) {
 511                         size_t size;
 512
 513                         kfree(*vaddr, M_DEVBUF);
 514                         /* XXX check for overflow? */
 515                         for (size = 1; size <= maxsize; size <<= 1)
 516                                 ;
 517                         *vaddr = kmalloc(size, M_DEVBUF, mflags);
 518                         check_kmalloc(dmat, *vaddr, 1);
 519                 }
 520         } else {
 521                 /*
 522                  * XXX Use Contigmalloc until it is merged into this facility
 523                  *     and handles multi-seg allocations.  Nobody is doing
 524                  *     multi-seg allocations yet though.
 525                  */
 526                 *vaddr = contigmalloc(dmat->maxsize, M_DEVBUF, mflags,
 527                     0ul, dmat->lowaddr, dmat->alignment, dmat->boundary);
 528         }
 529         if (*vaddr == NULL)
 530                 return (ENOMEM);
 531         return (0);
 532 }
 533
 534 /*
 535  * Free a piece of memory and it's allociated dmamap, that was allocated
 536  * via bus_dmamem_alloc.  Make the same choice for free/contigfree.
 537  */
 538 void
 539 bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
 540 {
 541         /*
 542          * dmamem does not need to be bounced, so the map should be
 543          * NULL
 544          */
 545         if (map != NULL)
 546                 panic("bus_dmamem_free: Invalid map freed\n");
 547         if (BUS_DMAMEM_KMALLOC(dmat))
 548                 kfree(vaddr, M_DEVBUF);
 549         else
 550                 contigfree(vaddr, dmat->maxsize, M_DEVBUF);
 551 }
 552
 553 static __inline vm_paddr_t
 554 _bus_dma_extract(pmap_t pmap, vm_offset_t vaddr)
 555 {
 556         if (pmap)
 557                 return pmap_extract(pmap, vaddr);
 558         else
 559                 return pmap_kextract(vaddr);
 560 }
 561
 562 /*
 563  * Utility function to load a linear buffer.  lastaddrp holds state
 564  * between invocations (for multiple-buffer loads).  segp contains
 565  * the segment following the starting one on entrace, and the ending
 566  * segment on exit.  first indicates if this is the first invocation
 567  * of this function.
 568  */
 569 static int
 570 _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
 571                         bus_dmamap_t map,
 572                         void *buf, bus_size_t buflen,
 573                         bus_dma_segment_t *segments,
 574                         int nsegments,
 575                         pmap_t pmap,
 576                         int flags,
 577                         vm_paddr_t *lastpaddrp,
 578                         int *segp,
 579                         int first)
 580 {
 581         vm_offset_t vaddr;
 582         vm_paddr_t paddr, nextpaddr;
 583         bus_dma_segment_t *sg;
 584         bus_addr_t bmask;
 585         int seg, error = 0;
 586
 587         if (map == NULL)
 588                 map = &nobounce_dmamap;
 589
 590 #ifdef INVARIANTS
 591         if (dmat->flags & BUS_DMA_ALIGNED)
 592                 KKASSERT(((uintptr_t)buf & (dmat->alignment - 1)) == 0);
 593 #endif
 594
 595         /*
 596          * If we are being called during a callback, pagesneeded will
 597          * be non-zero, so we can avoid doing the work twice.
 598          */
 599         if ((dmat->flags & BUS_DMA_COULD_BOUNCE) &&
 600             map != &nobounce_dmamap && map->pagesneeded == 0) {
 601                 vm_offset_t vendaddr;
 602
 603                 /*
 604                  * Count the number of bounce pages
 605                  * needed in order to complete this transfer
 606                  */
 607                 vaddr = (vm_offset_t)buf;
 608                 vendaddr = (vm_offset_t)buf + buflen;
 609
 610                 while (vaddr < vendaddr) {
 611                         paddr = _bus_dma_extract(pmap, vaddr);
 612                         if (run_filter(dmat, paddr) != 0)
 613                                 map->pagesneeded++;
 614                         vaddr += (PAGE_SIZE - ((vm_offset_t)vaddr & PAGE_MASK));
 615                 }
 616         }
 617
 618         /* Reserve Necessary Bounce Pages */
 619         if (map->pagesneeded != 0) {
 620                 struct bounce_zone *bz;
 621
 622                 bz = dmat->bounce_zone;
 623                 BZ_LOCK(bz);
 624                 if (flags & BUS_DMA_NOWAIT) {
 625                         if (reserve_bounce_pages(dmat, map, 0) != 0) {
 626                                 BZ_UNLOCK(bz);
 627                                 error = ENOMEM;
 628                                 goto free_bounce;
 629                         }
 630                 } else {
 631                         if (reserve_bounce_pages(dmat, map, 1) != 0) {
 632                                 /* Queue us for resources */
 633                                 map->dmat = dmat;
 634                                 map->buf = buf;
 635                                 map->buflen = buflen;
 636
 637                                 STAILQ_INSERT_TAIL(
 638                                     &dmat->bounce_zone->bounce_map_waitinglist,
 639                                     map, links);
 640                                 BZ_UNLOCK(bz);
 641
 642                                 return (EINPROGRESS);
 643                         }
 644                 }
 645                 BZ_UNLOCK(bz);
 646         }
 647
 648         KKASSERT(*segp >= 1 && *segp <= nsegments);
 649         seg = *segp;
 650         sg = &segments[seg - 1];
 651
 652         vaddr = (vm_offset_t)buf;
 653         nextpaddr = *lastpaddrp;
 654         bmask = ~(dmat->boundary - 1);  /* note: will be 0 if boundary is 0 */
 655
 656         /* force at least one segment */
 657         do {
 658                 bus_size_t size;
 659
 660                 /*
 661                  * Per-page main loop
 662                  */
 663                 paddr = _bus_dma_extract(pmap, vaddr);
 664                 size = PAGE_SIZE - (paddr & PAGE_MASK);
 665                 if (size > buflen)
 666                         size = buflen;
 667                 if (map->pagesneeded != 0 && run_filter(dmat, paddr)) {
 668                         /*
 669                          * note: this paddr has the same in-page offset
 670                          * as vaddr and thus the paddr above, so the
 671                          * size does not have to be recalculated
 672                          */
 673                         paddr = add_bounce_page(dmat, map, vaddr, size);
 674                 }
 675
 676                 /*
 677                  * Fill in the bus_dma_segment
 678                  */
 679                 if (first) {
 680                         sg->ds_addr = paddr;
 681                         sg->ds_len = size;
 682                         first = 0;
 683                 } else if (paddr == nextpaddr) {
 684                         sg->ds_len += size;
 685                 } else {
 686                         sg++;
 687                         seg++;
 688                         if (seg > nsegments)
 689                                 break;
 690                         sg->ds_addr = paddr;
 691                         sg->ds_len = size;
 692                 }
 693                 nextpaddr = paddr + size;
 694
 695                 /*
 696                  * Handle maxsegsz and boundary issues with a nested loop
 697                  */
 698                 for (;;) {
 699                         bus_size_t tmpsize;
 700
 701                         /*
 702                          * Limit to the boundary and maximum segment size
 703                          */
 704                         if (((nextpaddr - 1) ^ sg->ds_addr) & bmask) {
 705                                 tmpsize = dmat->boundary -
 706                                           (sg->ds_addr & ~bmask);
 707                                 if (tmpsize > dmat->maxsegsz)
 708                                         tmpsize = dmat->maxsegsz;
 709                                 KKASSERT(tmpsize < sg->ds_len);
 710                         } else if (sg->ds_len > dmat->maxsegsz) {
 711                                 tmpsize = dmat->maxsegsz;
 712                         } else {
 713                                 break;
 714                         }
 715
 716                         /*
 717                          * Futz, split the data into a new segment.
 718                          */
 719                         if (seg >= nsegments)
 720                                 goto fail;
 721                         sg[1].ds_len = sg[0].ds_len - tmpsize;
 722                         sg[1].ds_addr = sg[0].ds_addr + tmpsize;
 723                         sg[0].ds_len = tmpsize;
 724                         sg++;
 725                         seg++;
 726                 }
 727
 728                 /*
 729                  * Adjust for loop
 730                  */
 731                 buflen -= size;
 732                 vaddr += size;
 733         } while (buflen > 0);
 734 fail:
 735         if (buflen != 0)
 736                 error = EFBIG;
 737
 738         *segp = seg;
 739         *lastpaddrp = nextpaddr;
 740
 741 free_bounce:
 742         if (error && (dmat->flags & BUS_DMA_COULD_BOUNCE) &&
 743             map != &nobounce_dmamap) {
 744                 _bus_dmamap_unload(dmat, map);
 745                 return_bounce_pages(dmat, map);
 746         }
 747         return error;
 748 }
 749
 750 /*
 751  * Map the buffer buf into bus space using the dmamap map.
 752  */
 753 int
 754 bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
 755                 bus_size_t buflen, bus_dmamap_callback_t *callback,
 756                 void *callback_arg, int flags)
 757 {
 758         vm_paddr_t lastaddr = 0;
 759         int error, nsegs = 1;
 760
 761         if (map != NULL) {
 762                 /*
 763                  * XXX
 764                  * Follow old semantics.  Once all of the callers are fixed,
 765                  * we should get rid of these internal flag "adjustment".
 766                  */
 767                 flags &= ~BUS_DMA_NOWAIT;
 768                 flags |= BUS_DMA_WAITOK;
 769
 770                 map->callback = callback;
 771                 map->callback_arg = callback_arg;
 772         }
 773
 774         error = _bus_dmamap_load_buffer(dmat, map, buf, buflen,
 775                         dmat->segments, dmat->nsegments,
 776                         NULL, flags, &lastaddr, &nsegs, 1);
 777         if (error == EINPROGRESS)
 778                 return error;
 779
 780         callback(callback_arg, dmat->segments, nsegs, error);
 781         return 0;
 782 }
 783
 784 /*
 785  * Like _bus_dmamap_load(), but for mbufs.
 786  */
 787 int
 788 bus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map,
 789                      struct mbuf *m0,
 790                      bus_dmamap_callback2_t *callback, void *callback_arg,
 791                      int flags)
 792 {
 793         int nsegs, error;
 794
 795         /*
 796          * XXX
 797          * Follow old semantics.  Once all of the callers are fixed,
 798          * we should get rid of these internal flag "adjustment".
 799          */
 800         flags &= ~BUS_DMA_WAITOK;
 801         flags |= BUS_DMA_NOWAIT;
 802
 803         error = bus_dmamap_load_mbuf_segment(dmat, map, m0,
 804                         dmat->segments, dmat->nsegments, &nsegs, flags);
 805         if (error) {
 806                 /* force "no valid mappings" in callback */
 807                 callback(callback_arg, dmat->segments, 0, 0, error);
 808         } else {
 809                 callback(callback_arg, dmat->segments, nsegs,
 810                          m0->m_pkthdr.len, error);
 811         }
 812         return error;
 813 }
 814
 815 int
 816 bus_dmamap_load_mbuf_segment(bus_dma_tag_t dmat, bus_dmamap_t map,
 817                              struct mbuf *m0,
 818                              bus_dma_segment_t *segs, int maxsegs,
 819                              int *nsegs, int flags)
 820 {
 821         int error;
 822
 823         M_ASSERTPKTHDR(m0);
 824
 825         KASSERT(maxsegs >= 1, ("invalid maxsegs %d\n", maxsegs));
 826         KASSERT(maxsegs <= dmat->nsegments,
 827                 ("%d too many segments, dmat only support %d segments\n",
 828                  maxsegs, dmat->nsegments));
 829         KASSERT(flags & BUS_DMA_NOWAIT,
 830                 ("only BUS_DMA_NOWAIT is supported\n"));
 831
 832         if (m0->m_pkthdr.len <= dmat->maxsize) {
 833                 int first = 1;
 834                 vm_paddr_t lastaddr = 0;
 835                 struct mbuf *m;
 836
 837                 *nsegs = 1;
 838                 error = 0;
 839                 for (m = m0; m != NULL && error == 0; m = m->m_next) {
 840                         if (m->m_len == 0)
 841                                 continue;
 842
 843                         error = _bus_dmamap_load_buffer(dmat, map,
 844                                         m->m_data, m->m_len,
 845                                         segs, maxsegs,
 846                                         NULL, flags, &lastaddr,
 847                                         nsegs, first);
 848                         if (error == ENOMEM && !first) {
 849                                 /*
 850                                  * Out of bounce pages due to too many
 851                                  * fragments in the mbuf chain; return
 852                                  * EFBIG instead.
 853                                  */
 854                                 error = EFBIG;
 855                         }
 856                         first = 0;
 857                 }
 858 #ifdef INVARIANTS
 859                 if (!error)
 860                         KKASSERT(*nsegs <= maxsegs && *nsegs >= 1);
 861 #endif
 862         } else {
 863                 *nsegs = 0;
 864                 error = EINVAL;
 865         }
 866         KKASSERT(error != EINPROGRESS);
 867         return error;
 868 }
 869
 870 /*
 871  * Like _bus_dmamap_load(), but for uios.
 872  */
 873 int
 874 bus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map,
 875                     struct uio *uio,
 876                     bus_dmamap_callback2_t *callback, void *callback_arg,
 877                     int flags)
 878 {
 879         vm_paddr_t lastaddr;
 880         int nsegs, error, first, i;
 881         bus_size_t resid;
 882         struct iovec *iov;
 883         pmap_t pmap;
 884
 885         /*
 886          * XXX
 887          * Follow old semantics.  Once all of the callers are fixed,
 888          * we should get rid of these internal flag "adjustment".
 889          */
 890         flags &= ~BUS_DMA_WAITOK;
 891         flags |= BUS_DMA_NOWAIT;
 892
 893         resid = uio->uio_resid;
 894         iov = uio->uio_iov;
 895
 896         if (uio->uio_segflg == UIO_USERSPACE) {
 897                 struct thread *td;
 898
 899                 td = uio->uio_td;
 900                 KASSERT(td != NULL && td->td_proc != NULL,
 901                         ("bus_dmamap_load_uio: USERSPACE but no proc"));
 902                 pmap = vmspace_pmap(td->td_proc->p_vmspace);
 903         } else {
 904                 pmap = NULL;
 905         }
 906
 907         error = 0;
 908         nsegs = 1;
 909         first = 1;
 910         lastaddr = 0;
 911         for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
 912                 /*
 913                  * Now at the first iovec to load.  Load each iovec
 914                  * until we have exhausted the residual count.
 915                  */
 916                 bus_size_t minlen =
 917                         resid < iov[i].iov_len ? resid : iov[i].iov_len;
 918                 caddr_t addr = (caddr_t) iov[i].iov_base;
 919
 920                 error = _bus_dmamap_load_buffer(dmat, map, addr, minlen,
 921                                 dmat->segments, dmat->nsegments,
 922                                 pmap, flags, &lastaddr, &nsegs, first);
 923                 first = 0;
 924
 925                 resid -= minlen;
 926         }
 927
 928         if (error) {
 929                 /* force "no valid mappings" in callback */
 930                 callback(callback_arg, dmat->segments, 0, 0, error);
 931         } else {
 932                 callback(callback_arg, dmat->segments, nsegs,
 933                          uio->uio_resid, error);
 934         }
 935         return error;
 936 }
 937
 938 /*
 939  * Release the mapping held by map.
 940  */
 941 void
 942 _bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
 943 {
 944         struct bounce_page *bpage;
 945
 946         while ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
 947                 STAILQ_REMOVE_HEAD(&map->bpages, links);
 948                 free_bounce_page(dmat, bpage);
 949         }
 950 }
 951
 952 void
 953 _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
 954 {
 955         struct bounce_page *bpage;
 956
 957         if ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
 958                 /*
 959                  * Handle data bouncing.  We might also
 960                  * want to add support for invalidating
 961                  * the caches on broken hardware
 962                  */
 963                 switch (op) {
 964                 case BUS_DMASYNC_PREWRITE:
 965                         while (bpage != NULL) {
 966                                 bcopy((void *)bpage->datavaddr,
 967                                       (void *)bpage->vaddr,
 968                                       bpage->datacount);
 969                                 bpage = STAILQ_NEXT(bpage, links);
 970                         }
 971                         dmat->bounce_zone->total_bounced++;
 972                         break;
 973
 974                 case BUS_DMASYNC_POSTREAD:
 975                         while (bpage != NULL) {
 976                                 bcopy((void *)bpage->vaddr,
 977                                       (void *)bpage->datavaddr,
 978                                       bpage->datacount);
 979                                 bpage = STAILQ_NEXT(bpage, links);
 980                         }
 981                         dmat->bounce_zone->total_bounced++;
 982                         break;
 983
 984                 case BUS_DMASYNC_PREREAD:
 985                 case BUS_DMASYNC_POSTWRITE:
 986                         /* No-ops */
 987                         break;
 988                 }
 989         }
 990 }
 991
 992 static int
 993 alloc_bounce_zone(bus_dma_tag_t dmat)
 994 {
 995         struct bounce_zone *bz, *new_bz;
 996         lwkt_tokref ref;
 997
 998         KASSERT(dmat->bounce_zone == NULL,
 999                 ("bounce zone was already assigned\n"));
1000
1001         new_bz = kmalloc(sizeof(*new_bz), M_DEVBUF, M_INTWAIT | M_ZERO);
1002
1003         lwkt_gettoken(&ref, &bounce_zone_tok);
1004
1005         /* Check to see if we already have a suitable zone */
1006         STAILQ_FOREACH(bz, &bounce_zone_list, links) {
1007                 if (dmat->alignment <= bz->alignment &&
1008                     dmat->boundary <= bz->boundary &&
1009                     dmat->lowaddr >= bz->lowaddr) {
1010                         lwkt_reltoken(&ref);
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         bz->boundary = round_page(dmat->boundary);
1030         if (bz->boundary == 0)
1031                 bz->boundary = PAGE_SIZE;
1032         ksnprintf(bz->zoneid, 8, "zone%d", busdma_zonecount);
1033         busdma_zonecount++;
1034         ksnprintf(bz->lowaddrid, 18, "%#jx", (uintmax_t)bz->lowaddr);
1035         STAILQ_INSERT_TAIL(&bounce_zone_list, bz, links);
1036
1037         lwkt_reltoken(&ref);
1038
1039         dmat->bounce_zone = bz;
1040
1041         sysctl_ctx_init(&bz->sysctl_ctx);
1042         bz->sysctl_tree = SYSCTL_ADD_NODE(&bz->sysctl_ctx,
1043             SYSCTL_STATIC_CHILDREN(_hw_busdma), OID_AUTO, bz->zoneid,
1044             CTLFLAG_RD, 0, "");
1045         if (bz->sysctl_tree == NULL) {
1046                 sysctl_ctx_free(&bz->sysctl_ctx);
1047                 return 0;       /* XXX error code? */
1048         }
1049
1050         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1051             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1052             "total_bpages", CTLFLAG_RD, &bz->total_bpages, 0,
1053             "Total bounce pages");
1054         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1055             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1056             "free_bpages", CTLFLAG_RD, &bz->free_bpages, 0,
1057             "Free bounce pages");
1058         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1059             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1060             "reserved_bpages", CTLFLAG_RD, &bz->reserved_bpages, 0,
1061             "Reserved bounce pages");
1062         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1063             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1064             "active_bpages", CTLFLAG_RD, &bz->active_bpages, 0,
1065             "Active bounce pages");
1066         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1067             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1068             "total_bounced", CTLFLAG_RD, &bz->total_bounced, 0,
1069             "Total bounce requests");
1070         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1071             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1072             "total_deferred", CTLFLAG_RD, &bz->total_deferred, 0,
1073             "Total bounce requests that were deferred");
1074         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1075             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1076             "reserve_failed", CTLFLAG_RD, &bz->reserve_failed, 0,
1077             "Total bounce page reservations that were failed");
1078         SYSCTL_ADD_STRING(&bz->sysctl_ctx,
1079             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1080             "lowaddr", CTLFLAG_RD, bz->lowaddrid, 0, "");
1081         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1082             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1083             "alignment", CTLFLAG_RD, &bz->alignment, 0, "");
1084         SYSCTL_ADD_INT(&bz->sysctl_ctx,
1085             SYSCTL_CHILDREN(bz->sysctl_tree), OID_AUTO,
1086             "boundary", CTLFLAG_RD, &bz->boundary, 0, "");
1087
1088         return 0;
1089 }
1090
1091 static int
1092 alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages, int flags)
1093 {
1094         struct bounce_zone *bz = dmat->bounce_zone;
1095         int count = 0, mflags;
1096
1097         if (flags & BUS_DMA_NOWAIT)
1098                 mflags = M_NOWAIT;
1099         else
1100                 mflags = M_WAITOK;
1101
1102         while (numpages > 0) {
1103                 struct bounce_page *bpage;
1104
1105                 bpage = kmalloc(sizeof(*bpage), M_DEVBUF, M_INTWAIT | M_ZERO);
1106
1107                 bpage->vaddr = (vm_offset_t)contigmalloc(PAGE_SIZE, M_DEVBUF,
1108                                                          mflags, 0ul,
1109                                                          bz->lowaddr,
1110                                                          bz->alignment,
1111                                                          bz->boundary);
1112                 if (bpage->vaddr == 0) {
1113                         kfree(bpage, M_DEVBUF);
1114                         break;
1115                 }
1116                 bpage->busaddr = pmap_kextract(bpage->vaddr);
1117
1118                 BZ_LOCK(bz);
1119                 STAILQ_INSERT_TAIL(&bz->bounce_page_list, bpage, links);
1120                 total_bounce_pages++;
1121                 bz->total_bpages++;
1122                 bz->free_bpages++;
1123                 BZ_UNLOCK(bz);
1124
1125                 count++;
1126                 numpages--;
1127         }
1128         return count;
1129 }
1130
1131 /* Assume caller holds bounce zone spinlock */
1132 static int
1133 reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int commit)
1134 {
1135         struct bounce_zone *bz = dmat->bounce_zone;
1136         int pages;
1137
1138         pages = MIN(bz->free_bpages, map->pagesneeded - map->pagesreserved);
1139         if (!commit && map->pagesneeded > (map->pagesreserved + pages)) {
1140                 bz->reserve_failed++;
1141                 return (map->pagesneeded - (map->pagesreserved + pages));
1142         }
1143
1144         bz->free_bpages -= pages;
1145
1146         bz->reserved_bpages += pages;
1147         KKASSERT(bz->reserved_bpages <= bz->total_bpages);
1148
1149         map->pagesreserved += pages;
1150         pages = map->pagesneeded - map->pagesreserved;
1151
1152         return pages;
1153 }
1154
1155 static void
1156 return_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map)
1157 {
1158         struct bounce_zone *bz = dmat->bounce_zone;
1159         int reserved = map->pagesreserved;
1160         bus_dmamap_t wait_map;
1161
1162         map->pagesreserved = 0;
1163         map->pagesneeded = 0;
1164
1165         if (reserved == 0)
1166                 return;
1167
1168         BZ_LOCK(bz);
1169
1170         bz->free_bpages += reserved;
1171         KKASSERT(bz->free_bpages <= bz->total_bpages);
1172
1173         KKASSERT(bz->reserved_bpages >= reserved);
1174         bz->reserved_bpages -= reserved;
1175
1176         wait_map = get_map_waiting(dmat);
1177
1178         BZ_UNLOCK(bz);
1179
1180         if (wait_map != NULL)
1181                 add_map_callback(map);
1182 }
1183
1184 static bus_addr_t
1185 add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
1186                 bus_size_t size)
1187 {
1188         struct bounce_zone *bz = dmat->bounce_zone;
1189         struct bounce_page *bpage;
1190
1191         KASSERT(map->pagesneeded > 0, ("map doesn't need any pages"));
1192         map->pagesneeded--;
1193
1194         KASSERT(map->pagesreserved > 0, ("map doesn't reserve any pages"));
1195         map->pagesreserved--;
1196
1197         BZ_LOCK(bz);
1198
1199         bpage = STAILQ_FIRST(&bz->bounce_page_list);
1200         KASSERT(bpage != NULL, ("free page list is empty"));
1201         STAILQ_REMOVE_HEAD(&bz->bounce_page_list, links);
1202
1203         KKASSERT(bz->reserved_bpages > 0);
1204         bz->reserved_bpages--;
1205
1206         bz->active_bpages++;
1207         KKASSERT(bz->active_bpages <= bz->total_bpages);
1208
1209         BZ_UNLOCK(bz);
1210
1211         bpage->datavaddr = vaddr;
1212         bpage->datacount = size;
1213         STAILQ_INSERT_TAIL(&map->bpages, bpage, links);
1214         return bpage->busaddr;
1215 }
1216
1217 static void
1218 free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
1219 {
1220         struct bounce_zone *bz = dmat->bounce_zone;
1221         bus_dmamap_t map;
1222
1223         bpage->datavaddr = 0;
1224         bpage->datacount = 0;
1225
1226         BZ_LOCK(bz);
1227
1228         STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
1229
1230         bz->free_bpages++;
1231         KKASSERT(bz->free_bpages <= bz->total_bpages);
1232
1233         KKASSERT(bz->active_bpages > 0);
1234         bz->active_bpages--;
1235
1236         map = get_map_waiting(dmat);
1237
1238         BZ_UNLOCK(bz);
1239
1240         if (map != NULL)
1241                 add_map_callback(map);
1242 }
1243
1244 /* Assume caller holds bounce zone spinlock */
1245 static bus_dmamap_t
1246 get_map_waiting(bus_dma_tag_t dmat)
1247 {
1248         struct bounce_zone *bz = dmat->bounce_zone;
1249         bus_dmamap_t map;
1250
1251         map = STAILQ_FIRST(&bz->bounce_map_waitinglist);
1252         if (map != NULL) {
1253                 if (reserve_bounce_pages(map->dmat, map, 1) == 0) {
1254                         STAILQ_REMOVE_HEAD(&bz->bounce_map_waitinglist, links);
1255                         bz->total_deferred++;
1256                 } else {
1257                         map = NULL;
1258                 }
1259         }
1260         return map;
1261 }
1262
1263 static void
1264 add_map_callback(bus_dmamap_t map)
1265 {
1266         /* XXX callbacklist is not MPSAFE */
1267         crit_enter();
1268         get_mplock();
1269         STAILQ_INSERT_TAIL(&bounce_map_callbacklist, map, links);
1270         busdma_swi_pending = 1;
1271         setsoftvm();
1272         rel_mplock();
1273         crit_exit();
1274 }
1275
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 }