The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/busdma_machdep.c

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    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 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/6.2/sys/i386/i386/busdma_machdep.c 163579 2006-10-21 16:26:53Z hrs $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/kdb.h>
   32 #include <ddb/ddb.h>
   33 #include <ddb/db_output.h>
   34 #include <sys/systm.h>
   35 #include <sys/malloc.h>
   36 #include <sys/bus.h>
   37 #include <sys/interrupt.h>
   38 #include <sys/kernel.h>
   39 #include <sys/ktr.h>
   40 #include <sys/lock.h>
   41 #include <sys/proc.h>
   42 #include <sys/mutex.h>
   43 #include <sys/mbuf.h>
   44 #include <sys/uio.h>
   45 #include <sys/sysctl.h>
   46 
   47 #include <vm/vm.h>
   48 #include <vm/vm_page.h>
   49 #include <vm/vm_map.h>
   50 
   51 #include <machine/atomic.h>
   52 #include <machine/bus.h>
   53 #include <machine/md_var.h>
   54 
   55 #define MAX_BPAGES 512
   56 
   57 struct bounce_zone;
   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_lock_t   *lockfunc;
   74         void             *lockfuncarg;
   75         bus_dma_segment_t *segments;
   76         struct bounce_zone *bounce_zone;
   77 };
   78 
   79 struct bounce_page {
   80         vm_offset_t     vaddr;          /* kva of bounce buffer */
   81         bus_addr_t      busaddr;        /* Physical address */
   82         vm_offset_t     datavaddr;      /* kva of client data */
   83         bus_size_t      datacount;      /* client data count */
   84         STAILQ_ENTRY(bounce_page) links;
   85 };
   86 
   87 int busdma_swi_pending;
   88 
   89 struct bounce_zone {
   90         STAILQ_ENTRY(bounce_zone) links;
   91         STAILQ_HEAD(bp_list, bounce_page) bounce_page_list;
   92         int             total_bpages;
   93         int             free_bpages;
   94         int             reserved_bpages;
   95         int             active_bpages;
   96         int             total_bounced;
   97         int             total_deferred;
   98         bus_size_t      alignment;
   99         bus_size_t      boundary;
  100         bus_addr_t      lowaddr;
  101         char            zoneid[8];
  102         char            lowaddrid[20];
  103         struct sysctl_ctx_list sysctl_tree;
  104         struct sysctl_oid *sysctl_tree_top;
  105 };
  106 
  107 static struct mtx bounce_lock;
  108 static int total_bpages;
  109 static int busdma_zonecount;
  110 static STAILQ_HEAD(, bounce_zone) bounce_zone_list;
  111 
  112 SYSCTL_NODE(_hw, OID_AUTO, busdma, CTLFLAG_RD, 0, "Busdma parameters");
  113 SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bpages, 0,
  114            "Total bounce pages");
  115 
  116 struct bus_dmamap {
  117         struct bp_list         bpages;
  118         int                    pagesneeded;
  119         int                    pagesreserved;
  120         bus_dma_tag_t          dmat;
  121         void                  *buf;             /* unmapped buffer pointer */
  122         bus_size_t             buflen;          /* unmapped buffer length */
  123         bus_dmamap_callback_t *callback;
  124         void                  *callback_arg;
  125         STAILQ_ENTRY(bus_dmamap) links;
  126 };
  127 
  128 static STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
  129 static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist;
  130 static struct bus_dmamap nobounce_dmamap;
  131 
  132 static void init_bounce_pages(void *dummy);
  133 static int alloc_bounce_zone(bus_dma_tag_t dmat);
  134 static int alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages);
  135 static int reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
  136                                 int commit);
  137 static bus_addr_t add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map,
  138                                    vm_offset_t vaddr, bus_size_t size);
  139 static void free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage);
  140 static __inline int run_filter(bus_dma_tag_t dmat, bus_addr_t paddr);
  141 
  142 /*
  143  * Return true if a match is made.
  144  *
  145  * To find a match walk the chain of bus_dma_tag_t's looking for 'paddr'.
  146  *
  147  * If paddr is within the bounds of the dma tag then call the filter callback
  148  * to check for a match, if there is no filter callback then assume a match.
  149  */
  150 static __inline int
  151 run_filter(bus_dma_tag_t dmat, bus_addr_t paddr)
  152 {
  153         int retval;
  154 
  155         retval = 0;
  156 
  157         do {
  158                 if (((paddr > dmat->lowaddr && paddr <= dmat->highaddr)
  159                  || ((paddr & (dmat->alignment - 1)) != 0))
  160                  && (dmat->filter == NULL
  161                   || (*dmat->filter)(dmat->filterarg, paddr) != 0))
  162                         retval = 1;
  163 
  164                 dmat = dmat->parent;            
  165         } while (retval == 0 && dmat != NULL);
  166         return (retval);
  167 }
  168 
  169 /*
  170  * Convenience function for manipulating driver locks from busdma (during
  171  * busdma_swi, for example).  Drivers that don't provide their own locks
  172  * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
  173  * non-mutex locking scheme don't have to use this at all.
  174  */
  175 void
  176 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)
  177 {
  178         struct mtx *dmtx;
  179 
  180         dmtx = (struct mtx *)arg;
  181         switch (op) {
  182         case BUS_DMA_LOCK:
  183                 mtx_lock(dmtx);
  184                 break;
  185         case BUS_DMA_UNLOCK:
  186                 mtx_unlock(dmtx);
  187                 break;
  188         default:
  189                 panic("Unknown operation 0x%x for busdma_lock_mutex!", op);
  190         }
  191 }
  192 
  193 /*
  194  * dflt_lock should never get called.  It gets put into the dma tag when
  195  * lockfunc == NULL, which is only valid if the maps that are associated
  196  * with the tag are meant to never be defered.
  197  * XXX Should have a way to identify which driver is responsible here.
  198  */
  199 static void
  200 dflt_lock(void *arg, bus_dma_lock_op_t op)
  201 {
  202         panic("driver error: busdma dflt_lock called");
  203 }
  204 
  205 #define BUS_DMA_COULD_BOUNCE    BUS_DMA_BUS3
  206 #define BUS_DMA_MIN_ALLOC_COMP  BUS_DMA_BUS4
  207 /*
  208  * Allocate a device specific dma_tag.
  209  */
  210 int
  211 bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
  212                    bus_size_t boundary, bus_addr_t lowaddr,
  213                    bus_addr_t highaddr, bus_dma_filter_t *filter,
  214                    void *filterarg, bus_size_t maxsize, int nsegments,
  215                    bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
  216                    void *lockfuncarg, bus_dma_tag_t *dmat)
  217 {
  218         bus_dma_tag_t newtag;
  219         int error = 0;
  220 
  221         /* Basic sanity checking */
  222         if (boundary != 0 && boundary < maxsegsz)
  223                 maxsegsz = boundary;
  224 
  225         /* Return a NULL tag on failure */
  226         *dmat = NULL;
  227 
  228         newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_DEVBUF,
  229             M_ZERO | M_NOWAIT);
  230         if (newtag == NULL) {
  231                 CTR4(KTR_BUSDMA, "%s returned tag %p tag flags 0x%x error %d",
  232                     __func__, newtag, 0, error);
  233                 return (ENOMEM);
  234         }
  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) +
  241             (PAGE_SIZE - 1);
  242         newtag->filter = filter;
  243         newtag->filterarg = filterarg;
  244         newtag->maxsize = maxsize;
  245         newtag->nsegments = nsegments;
  246         newtag->maxsegsz = maxsegsz;
  247         newtag->flags = flags;
  248         newtag->ref_count = 1; /* Count ourself */
  249         newtag->map_count = 0;
  250         if (lockfunc != NULL) {
  251                 newtag->lockfunc = lockfunc;
  252                 newtag->lockfuncarg = lockfuncarg;
  253         } else {
  254                 newtag->lockfunc = dflt_lock;
  255                 newtag->lockfuncarg = NULL;
  256         }
  257         newtag->segments = NULL;
  258 
  259         /* Take into account any restrictions imposed by our parent tag */
  260         if (parent != NULL) {
  261                 newtag->lowaddr = MIN(parent->lowaddr, newtag->lowaddr);
  262                 newtag->highaddr = MAX(parent->highaddr, newtag->highaddr);
  263                 if (newtag->boundary == 0)
  264                         newtag->boundary = parent->boundary;
  265                 else if (parent->boundary != 0)
  266                         newtag->boundary = MIN(parent->boundary,
  267                                                newtag->boundary);
  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                         atomic_add_int(&parent->ref_count, 1);
  279         }
  280 
  281         if (newtag->lowaddr < ptoa((vm_paddr_t)Maxmem)
  282          || newtag->alignment > 1)
  283                 newtag->flags |= BUS_DMA_COULD_BOUNCE;
  284 
  285         if (((newtag->flags & BUS_DMA_COULD_BOUNCE) != 0) &&
  286             (flags & BUS_DMA_ALLOCNOW) != 0) {
  287                 struct bounce_zone *bz;
  288 
  289                 /* Must bounce */
  290 
  291                 if ((error = alloc_bounce_zone(newtag)) != 0) {
  292                         free(newtag, M_DEVBUF);
  293                         return (error);
  294                 }
  295                 bz = newtag->bounce_zone;
  296 
  297                 if (ptoa(bz->total_bpages) < maxsize) {
  298                         int pages;
  299 
  300                         pages = atop(maxsize) - bz->total_bpages;
  301 
  302                         /* Add pages to our bounce pool */
  303                         if (alloc_bounce_pages(newtag, pages) < pages)
  304                                 error = ENOMEM;
  305                 }
  306                 /* Performed initial allocation */
  307                 newtag->flags |= BUS_DMA_MIN_ALLOC_COMP;
  308         }
  309         
  310         if (error != 0) {
  311                 free(newtag, M_DEVBUF);
  312         } else {
  313                 *dmat = newtag;
  314         }
  315         CTR4(KTR_BUSDMA, "%s returned tag %p tag flags 0x%x error %d",
  316             __func__, newtag, (newtag != NULL ? newtag->flags : 0), error);
  317         return (error);
  318 }
  319 
  320 int
  321 bus_dma_tag_destroy(bus_dma_tag_t dmat)
  322 {
  323         bus_dma_tag_t dmat_copy;
  324         int error;
  325 
  326         error = 0;
  327         dmat_copy = dmat;
  328 
  329         if (dmat != NULL) {
  330 
  331                 if (dmat->map_count != 0) {
  332                         error = EBUSY;
  333                         goto out;
  334                 }
  335 
  336                 while (dmat != NULL) {
  337                         bus_dma_tag_t parent;
  338 
  339                         parent = dmat->parent;
  340                         atomic_subtract_int(&dmat->ref_count, 1);
  341                         if (dmat->ref_count == 0) {
  342                                 if (dmat->segments != NULL)
  343                                         free(dmat->segments, M_DEVBUF);
  344                                 free(dmat, M_DEVBUF);
  345                                 /*
  346                                  * Last reference count, so
  347                                  * release our reference
  348                                  * count on our parent.
  349                                  */
  350                                 dmat = parent;
  351                         } else
  352                                 dmat = NULL;
  353                 }
  354         }
  355 out:
  356         CTR3(KTR_BUSDMA, "%s tag %p error %d", __func__, dmat_copy, error);
  357         return (error);
  358 }
  359 
  360 /*
  361  * Allocate a handle for mapping from kva/uva/physical
  362  * address space into bus device space.
  363  */
  364 int
  365 bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
  366 {
  367         int error;
  368 
  369         error = 0;
  370 
  371         if (dmat->segments == NULL) {
  372                 dmat->segments = (bus_dma_segment_t *)malloc(
  373                     sizeof(bus_dma_segment_t) * dmat->nsegments, M_DEVBUF,
  374                     M_NOWAIT);
  375                 if (dmat->segments == NULL) {
  376                         CTR3(KTR_BUSDMA, "%s: tag %p error %d",
  377                             __func__, dmat, ENOMEM);
  378                         return (ENOMEM);
  379                 }
  380         }
  381 
  382         /*
  383          * Bouncing might be required if the driver asks for an active
  384          * exclusion region, a data alignment that is stricter than 1, and/or
  385          * an active address boundary.
  386          */
  387         if (dmat->flags & BUS_DMA_COULD_BOUNCE) {
  388 
  389                 /* Must bounce */
  390                 struct bounce_zone *bz;
  391                 int maxpages;
  392 
  393                 if (dmat->bounce_zone == NULL) {
  394                         if ((error = alloc_bounce_zone(dmat)) != 0)
  395                                 return (error);
  396                 }
  397                 bz = dmat->bounce_zone;
  398 
  399                 *mapp = (bus_dmamap_t)malloc(sizeof(**mapp), M_DEVBUF,
  400                                              M_NOWAIT | M_ZERO);
  401                 if (*mapp == NULL) {
  402                         CTR3(KTR_BUSDMA, "%s: tag %p error %d",
  403                             __func__, dmat, ENOMEM);
  404                         return (ENOMEM);
  405                 }
  406 
  407                 /* Initialize the new map */
  408                 STAILQ_INIT(&((*mapp)->bpages));
  409 
  410                 /*
  411                  * Attempt to add pages to our pool on a per-instance
  412                  * basis up to a sane limit.
  413                  */
  414                 if (dmat->alignment > 1)
  415                         maxpages = MAX_BPAGES;
  416                 else
  417                         maxpages = MIN(MAX_BPAGES, Maxmem -atop(dmat->lowaddr));
  418                 if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
  419                  || (dmat->map_count > 0 && bz->total_bpages < maxpages)) {
  420                         int pages;
  421 
  422                         pages = MAX(atop(dmat->maxsize), 1);
  423                         pages = MIN(maxpages - bz->total_bpages, pages);
  424                         pages = MAX(pages, 1);
  425                         if (alloc_bounce_pages(dmat, pages) < pages)
  426                                 error = ENOMEM;
  427 
  428                         if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0) {
  429                                 if (error == 0)
  430                                         dmat->flags |= BUS_DMA_MIN_ALLOC_COMP;
  431                         } else {
  432                                 error = 0;
  433                         }
  434                 }
  435         } else {
  436                 *mapp = NULL;
  437         }
  438         if (error == 0)
  439                 dmat->map_count++;
  440         CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
  441             __func__, dmat, dmat->flags, error);
  442         return (error);
  443 }
  444 
  445 /*
  446  * Destroy a handle for mapping from kva/uva/physical
  447  * address space into bus device space.
  448  */
  449 int
  450 bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
  451 {
  452         if (map != NULL && map != &nobounce_dmamap) {
  453                 if (STAILQ_FIRST(&map->bpages) != NULL) {
  454                         CTR3(KTR_BUSDMA, "%s: tag %p error %d",
  455                             __func__, dmat, EBUSY);
  456                         return (EBUSY);
  457                 }
  458                 free(map, M_DEVBUF);
  459         }
  460         dmat->map_count--;
  461         CTR2(KTR_BUSDMA, "%s: tag %p error 0", __func__, dmat);
  462         return (0);
  463 }
  464 
  465 
  466 /*
  467  * Allocate a piece of memory that can be efficiently mapped into
  468  * bus device space based on the constraints lited in the dma tag.
  469  * A dmamap to for use with dmamap_load is also allocated.
  470  */
  471 int
  472 bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
  473                  bus_dmamap_t *mapp)
  474 {
  475         int mflags;
  476 
  477         if (flags & BUS_DMA_NOWAIT)
  478                 mflags = M_NOWAIT;
  479         else
  480                 mflags = M_WAITOK;
  481         if (flags & BUS_DMA_ZERO)
  482                 mflags |= M_ZERO;
  483 
  484         /* If we succeed, no mapping/bouncing will be required */
  485         *mapp = NULL;
  486 
  487         if (dmat->segments == NULL) {
  488                 dmat->segments = (bus_dma_segment_t *)malloc(
  489                     sizeof(bus_dma_segment_t) * dmat->nsegments, M_DEVBUF,
  490                     M_NOWAIT);
  491                 if (dmat->segments == NULL) {
  492                         CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
  493                             __func__, dmat, dmat->flags, ENOMEM);
  494                         return (ENOMEM);
  495                 }
  496         }
  497 
  498         /* 
  499          * XXX:
  500          * (dmat->alignment < dmat->maxsize) is just a quick hack; the exact
  501          * alignment guarantees of malloc need to be nailed down, and the
  502          * code below should be rewritten to take that into account.
  503          *
  504          * In the meantime, we'll warn the user if malloc gets it wrong.
  505          */
  506         if ((dmat->maxsize <= PAGE_SIZE) &&
  507            (dmat->alignment < dmat->maxsize) &&
  508             dmat->lowaddr >= ptoa((vm_paddr_t)Maxmem)) {
  509                 *vaddr = malloc(dmat->maxsize, M_DEVBUF, mflags);
  510         } else {
  511                 /*
  512                  * XXX Use Contigmalloc until it is merged into this facility
  513                  *     and handles multi-seg allocations.  Nobody is doing
  514                  *     multi-seg allocations yet though.
  515                  * XXX Certain AGP hardware does.
  516                  */
  517                 *vaddr = contigmalloc(dmat->maxsize, M_DEVBUF, mflags,
  518                     0ul, dmat->lowaddr, dmat->alignment? dmat->alignment : 1ul,
  519                     dmat->boundary);
  520         }
  521         if (*vaddr == NULL) {
  522                 CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
  523                     __func__, dmat, dmat->flags, ENOMEM);
  524                 return (ENOMEM);
  525         } else if ((uintptr_t)*vaddr & (dmat->alignment - 1)) {
  526                 printf("bus_dmamem_alloc failed to align memory properly.\n");
  527         }
  528         CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
  529             __func__, dmat, dmat->flags, ENOMEM);
  530         return (0);
  531 }
  532 
  533 /*
  534  * Free a piece of memory and it's allociated dmamap, that was allocated
  535  * via bus_dmamem_alloc.  Make the same choice for free/contigfree.
  536  */
  537 void
  538 bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
  539 {
  540         /*
  541          * dmamem does not need to be bounced, so the map should be
  542          * NULL
  543          */
  544         if (map != NULL)
  545                 panic("bus_dmamem_free: Invalid map freed\n");
  546         if ((dmat->maxsize <= PAGE_SIZE) &&
  547            (dmat->alignment < dmat->maxsize) &&
  548             dmat->lowaddr >= ptoa((vm_paddr_t)Maxmem))
  549                 free(vaddr, M_DEVBUF);
  550         else {
  551                 contigfree(vaddr, dmat->maxsize, M_DEVBUF);
  552         }
  553         CTR3(KTR_BUSDMA, "%s: tag %p flags 0x%x", __func__, dmat, dmat->flags);
  554 }
  555 
  556 /*
  557  * Utility function to load a linear buffer.  lastaddrp holds state
  558  * between invocations (for multiple-buffer loads).  segp contains
  559  * the starting segment on entrace, and the ending segment on exit.
  560  * first indicates if this is the first invocation of this function.
  561  */
  562 static __inline int
  563 _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
  564                         bus_dmamap_t map,
  565                         void *buf, bus_size_t buflen,
  566                         pmap_t pmap,
  567                         int flags,
  568                         bus_addr_t *lastaddrp,
  569                         bus_dma_segment_t *segs,
  570                         int *segp,
  571                         int first)
  572 {
  573         bus_size_t sgsize;
  574         bus_addr_t curaddr, lastaddr, baddr, bmask;
  575         vm_offset_t vaddr;
  576         bus_addr_t paddr;
  577         int needbounce = 0;
  578         int seg;
  579 
  580         if (map == NULL)
  581                 map = &nobounce_dmamap;
  582 
  583         if ((map != &nobounce_dmamap && map->pagesneeded == 0) 
  584          && ((dmat->flags & BUS_DMA_COULD_BOUNCE) != 0)) {
  585                 vm_offset_t     vendaddr;
  586 
  587                 CTR4(KTR_BUSDMA, "lowaddr= %d Maxmem= %d, boundary= %d, "
  588                     "alignment= %d", dmat->lowaddr, ptoa((vm_paddr_t)Maxmem),
  589                     dmat->boundary, dmat->alignment);
  590                 CTR3(KTR_BUSDMA, "map= %p, nobouncemap= %p, pagesneeded= %d",
  591                     map, &nobounce_dmamap, map->pagesneeded);
  592                 /*
  593                  * Count the number of bounce pages
  594                  * needed in order to complete this transfer
  595                  */
  596                 vaddr = trunc_page((vm_offset_t)buf);
  597                 vendaddr = (vm_offset_t)buf + buflen;
  598 
  599                 while (vaddr < vendaddr) {
  600                         paddr = pmap_kextract(vaddr);
  601                         if (run_filter(dmat, paddr) != 0) {
  602                                 needbounce = 1;
  603                                 map->pagesneeded++;
  604                         }
  605                         vaddr += PAGE_SIZE;
  606                 }
  607                 CTR1(KTR_BUSDMA, "pagesneeded= %d\n", map->pagesneeded);
  608         }
  609 
  610         /* Reserve Necessary Bounce Pages */
  611         if (map->pagesneeded != 0) {
  612                 mtx_lock(&bounce_lock);
  613                 if (flags & BUS_DMA_NOWAIT) {
  614                         if (reserve_bounce_pages(dmat, map, 0) != 0) {
  615                                 mtx_unlock(&bounce_lock);
  616                                 return (ENOMEM);
  617                         }
  618                 } else {
  619                         if (reserve_bounce_pages(dmat, map, 1) != 0) {
  620                                 /* Queue us for resources */
  621                                 map->dmat = dmat;
  622                                 map->buf = buf;
  623                                 map->buflen = buflen;
  624                                 STAILQ_INSERT_TAIL(&bounce_map_waitinglist,
  625                                     map, links);
  626                                 mtx_unlock(&bounce_lock);
  627                                 return (EINPROGRESS);
  628                         }
  629                 }
  630                 mtx_unlock(&bounce_lock);
  631         }
  632 
  633         vaddr = (vm_offset_t)buf;
  634         lastaddr = *lastaddrp;
  635         bmask = ~(dmat->boundary - 1);
  636 
  637         for (seg = *segp; buflen > 0 ; ) {
  638                 /*
  639                  * Get the physical address for this segment.
  640                  */
  641                 if (pmap)
  642                         curaddr = pmap_extract(pmap, vaddr);
  643                 else
  644                         curaddr = pmap_kextract(vaddr);
  645 
  646                 /*
  647                  * Compute the segment size, and adjust counts.
  648                  */
  649                 sgsize = PAGE_SIZE - ((u_long)curaddr & PAGE_MASK);
  650                 if (buflen < sgsize)
  651                         sgsize = buflen;
  652 
  653                 /*
  654                  * Make sure we don't cross any boundaries.
  655                  */
  656                 if (dmat->boundary > 0) {
  657                         baddr = (curaddr + dmat->boundary) & bmask;
  658                         if (sgsize > (baddr - curaddr))
  659                                 sgsize = (baddr - curaddr);
  660                 }
  661 
  662                 if (map->pagesneeded != 0 && run_filter(dmat, curaddr))
  663                         curaddr = add_bounce_page(dmat, map, vaddr, sgsize);
  664 
  665                 /*
  666                  * Insert chunk into a segment, coalescing with
  667                  * previous segment if possible.
  668                  */
  669                 if (first) {
  670                         segs[seg].ds_addr = curaddr;
  671                         segs[seg].ds_len = sgsize;
  672                         first = 0;
  673                 } else {
  674                         if (needbounce == 0 && curaddr == lastaddr &&
  675                             (segs[seg].ds_len + sgsize) <= dmat->maxsegsz &&
  676                             (dmat->boundary == 0 ||
  677                              (segs[seg].ds_addr & bmask) == (curaddr & bmask)))
  678                                 segs[seg].ds_len += sgsize;
  679                         else {
  680                                 if (++seg >= dmat->nsegments)
  681                                         break;
  682                                 segs[seg].ds_addr = curaddr;
  683                                 segs[seg].ds_len = sgsize;
  684                         }
  685                 }
  686 
  687                 lastaddr = curaddr + sgsize;
  688                 vaddr += sgsize;
  689                 buflen -= sgsize;
  690         }
  691 
  692         *segp = seg;
  693         *lastaddrp = lastaddr;
  694 
  695         /*
  696          * Did we fit?
  697          */
  698         return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
  699 }
  700 
  701 /*
  702  * Map the buffer buf into bus space using the dmamap map.
  703  */
  704 int
  705 bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
  706                 bus_size_t buflen, bus_dmamap_callback_t *callback,
  707                 void *callback_arg, int flags)
  708 {
  709         bus_addr_t              lastaddr = 0;
  710         int                     error, nsegs = 0;
  711 
  712         if (map != NULL) {
  713                 flags |= BUS_DMA_WAITOK;
  714                 map->callback = callback;
  715                 map->callback_arg = callback_arg;
  716         }
  717 
  718         error = _bus_dmamap_load_buffer(dmat, map, buf, buflen, NULL, flags,
  719              &lastaddr, dmat->segments, &nsegs, 1);
  720 
  721         CTR5(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d nsegs %d",
  722             __func__, dmat, dmat->flags, error, nsegs + 1);
  723 
  724         if (error == EINPROGRESS) {
  725                 return (error);
  726         }
  727 
  728         if (error)
  729                 (*callback)(callback_arg, dmat->segments, 0, error);
  730         else
  731                 (*callback)(callback_arg, dmat->segments, nsegs + 1, 0);
  732 
  733         /*
  734          * Return ENOMEM to the caller so that it can pass it up the stack.
  735          * This error only happens when NOWAIT is set, so deferal is disabled.
  736          */
  737         if (error == ENOMEM)
  738                 return (error);
  739 
  740         return (0);
  741 }
  742 
  743 
  744 /*
  745  * Like _bus_dmamap_load(), but for mbufs.
  746  */
  747 int
  748 bus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map,
  749                      struct mbuf *m0,
  750                      bus_dmamap_callback2_t *callback, void *callback_arg,
  751                      int flags)
  752 {
  753         int nsegs, error;
  754 
  755         M_ASSERTPKTHDR(m0);
  756 
  757         flags |= BUS_DMA_NOWAIT;
  758         nsegs = 0;
  759         error = 0;
  760         if (m0->m_pkthdr.len <= dmat->maxsize) {
  761                 int first = 1;
  762                 bus_addr_t lastaddr = 0;
  763                 struct mbuf *m;
  764 
  765                 for (m = m0; m != NULL && error == 0; m = m->m_next) {
  766                         if (m->m_len > 0) {
  767                                 error = _bus_dmamap_load_buffer(dmat, map,
  768                                                 m->m_data, m->m_len,
  769                                                 NULL, flags, &lastaddr,
  770                                                 dmat->segments, &nsegs, first);
  771                                 first = 0;
  772                         }
  773                 }
  774         } else {
  775                 error = EINVAL;
  776         }
  777 
  778         if (error) {
  779                 /* force "no valid mappings" in callback */
  780                 (*callback)(callback_arg, dmat->segments, 0, 0, error);
  781         } else {
  782                 (*callback)(callback_arg, dmat->segments,
  783                             nsegs+1, m0->m_pkthdr.len, error);
  784         }
  785         CTR5(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d nsegs %d",
  786             __func__, dmat, dmat->flags, error, nsegs + 1);
  787         return (error);
  788 }
  789 
  790 int
  791 bus_dmamap_load_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map,
  792                         struct mbuf *m0, bus_dma_segment_t *segs, int *nsegs,
  793                         int flags)
  794 {
  795         int error;
  796 
  797         M_ASSERTPKTHDR(m0);
  798 
  799         flags |= BUS_DMA_NOWAIT;
  800         *nsegs = 0;
  801         error = 0;
  802         if (m0->m_pkthdr.len <= dmat->maxsize) {
  803                 int first = 1;
  804                 bus_addr_t lastaddr = 0;
  805                 struct mbuf *m;
  806 
  807                 for (m = m0; m != NULL && error == 0; m = m->m_next) {
  808                         if (m->m_len > 0) {
  809                                 error = _bus_dmamap_load_buffer(dmat, map,
  810                                                 m->m_data, m->m_len,
  811                                                 NULL, flags, &lastaddr,
  812                                                 segs, nsegs, first);
  813                                 first = 0;
  814                         }
  815                 }
  816         } else {
  817                 error = EINVAL;
  818         }
  819 
  820         /* XXX FIXME: Having to increment nsegs is really annoying */
  821         ++*nsegs;
  822         CTR5(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d nsegs %d",
  823             __func__, dmat, dmat->flags, error, *nsegs);
  824         return (error);
  825 }
  826 
  827 /*
  828  * Like _bus_dmamap_load(), but for uios.
  829  */
  830 int
  831 bus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map,
  832                     struct uio *uio,
  833                     bus_dmamap_callback2_t *callback, void *callback_arg,
  834                     int flags)
  835 {
  836         bus_addr_t lastaddr;
  837         int nsegs, error, first, i;
  838         bus_size_t resid;
  839         struct iovec *iov;
  840         pmap_t pmap;
  841 
  842         flags |= BUS_DMA_NOWAIT;
  843         resid = uio->uio_resid;
  844         iov = uio->uio_iov;
  845 
  846         if (uio->uio_segflg == UIO_USERSPACE) {
  847                 KASSERT(uio->uio_td != NULL,
  848                         ("bus_dmamap_load_uio: USERSPACE but no proc"));
  849                 pmap = vmspace_pmap(uio->uio_td->td_proc->p_vmspace);
  850         } else
  851                 pmap = NULL;
  852 
  853         nsegs = 0;
  854         error = 0;
  855         first = 1;
  856         for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
  857                 /*
  858                  * Now at the first iovec to load.  Load each iovec
  859                  * until we have exhausted the residual count.
  860                  */
  861                 bus_size_t minlen =
  862                         resid < iov[i].iov_len ? resid : iov[i].iov_len;
  863                 caddr_t addr = (caddr_t) iov[i].iov_base;
  864 
  865                 if (minlen > 0) {
  866                         error = _bus_dmamap_load_buffer(dmat, map,
  867                                         addr, minlen, pmap, flags, &lastaddr,
  868                                         dmat->segments, &nsegs, first);
  869                         first = 0;
  870 
  871                         resid -= minlen;
  872                 }
  873         }
  874 
  875         if (error) {
  876                 /* force "no valid mappings" in callback */
  877                 (*callback)(callback_arg, dmat->segments, 0, 0, error);
  878         } else {
  879                 (*callback)(callback_arg, dmat->segments,
  880                             nsegs+1, uio->uio_resid, error);
  881         }
  882         CTR5(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d nsegs %d",
  883             __func__, dmat, dmat->flags, error, nsegs + 1);
  884         return (error);
  885 }
  886 
  887 /*
  888  * Release the mapping held by map.
  889  */
  890 void
  891 _bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
  892 {
  893         struct bounce_page *bpage;
  894 
  895         while ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
  896                 STAILQ_REMOVE_HEAD(&map->bpages, links);
  897                 free_bounce_page(dmat, bpage);
  898         }
  899 }
  900 
  901 void
  902 _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
  903 {
  904         struct bounce_page *bpage;
  905 
  906         if ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
  907                 /*
  908                  * Handle data bouncing.  We might also
  909                  * want to add support for invalidating
  910                  * the caches on broken hardware
  911                  */
  912                 dmat->bounce_zone->total_bounced++;
  913                 CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x op 0x%x "
  914                     "performing bounce", __func__, op, dmat, dmat->flags);
  915 
  916                 if (op & BUS_DMASYNC_PREWRITE) {
  917                         while (bpage != NULL) {
  918                                 bcopy((void *)bpage->datavaddr,
  919                                       (void *)bpage->vaddr,
  920                                       bpage->datacount);
  921                                 bpage = STAILQ_NEXT(bpage, links);
  922                         }
  923                 }
  924 
  925                 if (op & BUS_DMASYNC_POSTREAD) {
  926                         while (bpage != NULL) {
  927                                 bcopy((void *)bpage->vaddr,
  928                                       (void *)bpage->datavaddr,
  929                                       bpage->datacount);
  930                                 bpage = STAILQ_NEXT(bpage, links);
  931                         }
  932                 }
  933         }
  934 }
  935 
  936 static void
  937 init_bounce_pages(void *dummy __unused)
  938 {
  939 
  940         total_bpages = 0;
  941         STAILQ_INIT(&bounce_zone_list);
  942         STAILQ_INIT(&bounce_map_waitinglist);
  943         STAILQ_INIT(&bounce_map_callbacklist);
  944         mtx_init(&bounce_lock, "bounce pages lock", NULL, MTX_DEF);
  945 }
  946 SYSINIT(bpages, SI_SUB_LOCK, SI_ORDER_ANY, init_bounce_pages, NULL);
  947 
  948 static struct sysctl_ctx_list *
  949 busdma_sysctl_tree(struct bounce_zone *bz)
  950 {
  951         return (&bz->sysctl_tree);
  952 }
  953 
  954 static struct sysctl_oid *
  955 busdma_sysctl_tree_top(struct bounce_zone *bz)
  956 {
  957         return (bz->sysctl_tree_top);
  958 }
  959 
  960 static int
  961 alloc_bounce_zone(bus_dma_tag_t dmat)
  962 {
  963         struct bounce_zone *bz;
  964 
  965         /* Check to see if we already have a suitable zone */
  966         STAILQ_FOREACH(bz, &bounce_zone_list, links) {
  967                 if ((dmat->alignment <= bz->alignment)
  968                  && (dmat->boundary <= bz->boundary)
  969                  && (dmat->lowaddr >= bz->lowaddr)) {
  970                         dmat->bounce_zone = bz;
  971                         return (0);
  972                 }
  973         }
  974 
  975         if ((bz = (struct bounce_zone *)malloc(sizeof(*bz), M_DEVBUF,
  976             M_NOWAIT | M_ZERO)) == NULL)
  977                 return (ENOMEM);
  978 
  979         STAILQ_INIT(&bz->bounce_page_list);
  980         bz->free_bpages = 0;
  981         bz->reserved_bpages = 0;
  982         bz->active_bpages = 0;
  983         bz->lowaddr = dmat->lowaddr;
  984         bz->alignment = dmat->alignment;
  985         bz->boundary = dmat->boundary;
  986         snprintf(bz->zoneid, 8, "zone%d", busdma_zonecount);
  987         busdma_zonecount++;
  988         snprintf(bz->lowaddrid, 18, "%#jx", (uintmax_t)bz->lowaddr);
  989         STAILQ_INSERT_TAIL(&bounce_zone_list, bz, links);
  990         dmat->bounce_zone = bz;
  991 
  992         sysctl_ctx_init(&bz->sysctl_tree);
  993         bz->sysctl_tree_top = SYSCTL_ADD_NODE(&bz->sysctl_tree,
  994             SYSCTL_STATIC_CHILDREN(_hw_busdma), OID_AUTO, bz->zoneid,
  995             CTLFLAG_RD, 0, "");
  996         if (bz->sysctl_tree_top == NULL) {
  997                 sysctl_ctx_free(&bz->sysctl_tree);
  998                 return (0);     /* XXX error code? */
  999         }
 1000 
 1001         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1002             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1003             "total_bpages", CTLFLAG_RD, &bz->total_bpages, 0,
 1004             "Total bounce pages");
 1005         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1006             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1007             "free_bpages", CTLFLAG_RD, &bz->free_bpages, 0,
 1008             "Free bounce pages");
 1009         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1010             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1011             "reserved_bpages", CTLFLAG_RD, &bz->reserved_bpages, 0,
 1012             "Reserved bounce pages");
 1013         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1014             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1015             "active_bpages", CTLFLAG_RD, &bz->active_bpages, 0,
 1016             "Active bounce pages");
 1017         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1018             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1019             "total_bounced", CTLFLAG_RD, &bz->total_bounced, 0,
 1020             "Total bounce requests");
 1021         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1022             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1023             "total_deferred", CTLFLAG_RD, &bz->total_deferred, 0,
 1024             "Total bounce requests that were deferred");
 1025         SYSCTL_ADD_STRING(busdma_sysctl_tree(bz),
 1026             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1027             "lowaddr", CTLFLAG_RD, bz->lowaddrid, 0, "");
 1028         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1029             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1030             "alignment", CTLFLAG_RD, &bz->alignment, 0, "");
 1031         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1032             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1033             "boundary", CTLFLAG_RD, &bz->boundary, 0, "");
 1034 
 1035         return (0);
 1036 }
 1037 
 1038 static int
 1039 alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages)
 1040 {
 1041         struct bounce_zone *bz;
 1042         int count;
 1043 
 1044         bz = dmat->bounce_zone;
 1045         count = 0;
 1046         while (numpages > 0) {
 1047                 struct bounce_page *bpage;
 1048 
 1049                 bpage = (struct bounce_page *)malloc(sizeof(*bpage), M_DEVBUF,
 1050                                                      M_NOWAIT | M_ZERO);
 1051 
 1052                 if (bpage == NULL)
 1053                         break;
 1054                 bpage->vaddr = (vm_offset_t)contigmalloc(PAGE_SIZE, M_DEVBUF,
 1055                                                          M_NOWAIT, 0ul,
 1056                                                          bz->lowaddr,
 1057                                                          PAGE_SIZE,
 1058                                                          bz->boundary);
 1059                 if (bpage->vaddr == 0) {
 1060                         free(bpage, M_DEVBUF);
 1061                         break;
 1062                 }
 1063                 bpage->busaddr = pmap_kextract(bpage->vaddr);
 1064                 mtx_lock(&bounce_lock);
 1065                 STAILQ_INSERT_TAIL(&bz->bounce_page_list, bpage, links);
 1066                 total_bpages++;
 1067                 bz->total_bpages++;
 1068                 bz->free_bpages++;
 1069                 mtx_unlock(&bounce_lock);
 1070                 count++;
 1071                 numpages--;
 1072         }
 1073         return (count);
 1074 }
 1075 
 1076 static int
 1077 reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int commit)
 1078 {
 1079         struct bounce_zone *bz;
 1080         int pages;
 1081 
 1082         mtx_assert(&bounce_lock, MA_OWNED);
 1083         bz = dmat->bounce_zone;
 1084         pages = MIN(bz->free_bpages, map->pagesneeded - map->pagesreserved);
 1085         if (commit == 0 && map->pagesneeded > (map->pagesreserved + pages))
 1086                 return (map->pagesneeded - (map->pagesreserved + pages));
 1087         bz->free_bpages -= pages;
 1088         bz->reserved_bpages += pages;
 1089         map->pagesreserved += pages;
 1090         pages = map->pagesneeded - map->pagesreserved;
 1091 
 1092         return (pages);
 1093 }
 1094 
 1095 static bus_addr_t
 1096 add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
 1097                 bus_size_t size)
 1098 {
 1099         struct bounce_zone *bz;
 1100         struct bounce_page *bpage;
 1101 
 1102         KASSERT(dmat->bounce_zone != NULL, ("no bounce zone in dma tag"));
 1103         KASSERT(map != NULL && map != &nobounce_dmamap,
 1104             ("add_bounce_page: bad map %p", map));
 1105 
 1106         bz = dmat->bounce_zone;
 1107         if (map->pagesneeded == 0)
 1108                 panic("add_bounce_page: map doesn't need any pages");
 1109         map->pagesneeded--;
 1110 
 1111         if (map->pagesreserved == 0)
 1112                 panic("add_bounce_page: map doesn't need any pages");
 1113         map->pagesreserved--;
 1114 
 1115         mtx_lock(&bounce_lock);
 1116         bpage = STAILQ_FIRST(&bz->bounce_page_list);
 1117         if (bpage == NULL)
 1118                 panic("add_bounce_page: free page list is empty");
 1119 
 1120         STAILQ_REMOVE_HEAD(&bz->bounce_page_list, links);
 1121         bz->reserved_bpages--;
 1122         bz->active_bpages++;
 1123         mtx_unlock(&bounce_lock);
 1124 
 1125         bpage->datavaddr = vaddr;
 1126         bpage->datacount = size;
 1127         STAILQ_INSERT_TAIL(&(map->bpages), bpage, links);
 1128         return (bpage->busaddr);
 1129 }
 1130 
 1131 static void
 1132 free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
 1133 {
 1134         struct bus_dmamap *map;
 1135         struct bounce_zone *bz;
 1136 
 1137         bz = dmat->bounce_zone;
 1138         bpage->datavaddr = 0;
 1139         bpage->datacount = 0;
 1140 
 1141         mtx_lock(&bounce_lock);
 1142         STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
 1143         bz->free_bpages++;
 1144         bz->active_bpages--;
 1145         if ((map = STAILQ_FIRST(&bounce_map_waitinglist)) != NULL) {
 1146                 if (reserve_bounce_pages(map->dmat, map, 1) == 0) {
 1147                         STAILQ_REMOVE_HEAD(&bounce_map_waitinglist, links);
 1148                         STAILQ_INSERT_TAIL(&bounce_map_callbacklist,
 1149                                            map, links);
 1150                         busdma_swi_pending = 1;
 1151                         bz->total_deferred++;
 1152                         swi_sched(vm_ih, 0);
 1153                 }
 1154         }
 1155         mtx_unlock(&bounce_lock);
 1156 }
 1157 
 1158 void
 1159 busdma_swi(void)
 1160 {
 1161         bus_dma_tag_t dmat;
 1162         struct bus_dmamap *map;
 1163 
 1164         mtx_lock(&bounce_lock);
 1165         while ((map = STAILQ_FIRST(&bounce_map_callbacklist)) != NULL) {
 1166                 STAILQ_REMOVE_HEAD(&bounce_map_callbacklist, links);
 1167                 mtx_unlock(&bounce_lock);
 1168                 dmat = map->dmat;
 1169                 (dmat->lockfunc)(dmat->lockfuncarg, BUS_DMA_LOCK);
 1170                 bus_dmamap_load(map->dmat, map, map->buf, map->buflen,
 1171                                 map->callback, map->callback_arg, /*flags*/0);
 1172                 (dmat->lockfunc)(dmat->lockfuncarg, BUS_DMA_UNLOCK);
 1173                 mtx_lock(&bounce_lock);
 1174         }
 1175         mtx_unlock(&bounce_lock);
 1176 }

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