The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/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/6.3/sys/amd64/amd64/busdma_machdep.c 173886 2007-11-24 19:45:58Z cvs2svn $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/systm.h>
   32 #include <sys/malloc.h>
   33 #include <sys/bus.h>
   34 #include <sys/interrupt.h>
   35 #include <sys/kernel.h>
   36 #include <sys/ktr.h>
   37 #include <sys/lock.h>
   38 #include <sys/proc.h>
   39 #include <sys/mutex.h>
   40 #include <sys/mbuf.h>
   41 #include <sys/uio.h>
   42 #include <sys/sysctl.h>
   43 
   44 #include <vm/vm.h>
   45 #include <vm/vm_page.h>
   46 #include <vm/vm_map.h>
   47 
   48 #include <machine/atomic.h>
   49 #include <machine/bus.h>
   50 #include <machine/md_var.h>
   51 #include <machine/specialreg.h>
   52 
   53 #define MAX_BPAGES 8192
   54 
   55 struct bounce_zone;
   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_lock_t   *lockfunc;
   72         void             *lockfuncarg;
   73         bus_dma_segment_t *segments;
   74         struct bounce_zone *bounce_zone;
   75 };
   76 
   77 struct bounce_page {
   78         vm_offset_t     vaddr;          /* kva of bounce buffer */
   79         bus_addr_t      busaddr;        /* Physical address */
   80         vm_offset_t     datavaddr;      /* kva of client data */
   81         bus_size_t      datacount;      /* client data count */
   82         STAILQ_ENTRY(bounce_page) links;
   83 };
   84 
   85 int busdma_swi_pending;
   86 
   87 struct bounce_zone {
   88         STAILQ_ENTRY(bounce_zone) links;
   89         STAILQ_HEAD(bp_list, bounce_page) bounce_page_list;
   90         int             total_bpages;
   91         int             free_bpages;
   92         int             reserved_bpages;
   93         int             active_bpages;
   94         int             total_bounced;
   95         int             total_deferred;
   96         bus_size_t      alignment;
   97         bus_size_t      boundary;
   98         bus_addr_t      lowaddr;
   99         char            zoneid[8];
  100         char            lowaddrid[20];
  101         struct sysctl_ctx_list sysctl_tree;
  102         struct sysctl_oid *sysctl_tree_top;
  103 };
  104 
  105 static struct mtx bounce_lock;
  106 static int total_bpages;
  107 static int busdma_zonecount;
  108 static STAILQ_HEAD(, bounce_zone) bounce_zone_list;
  109 
  110 SYSCTL_NODE(_hw, OID_AUTO, busdma, CTLFLAG_RD, 0, "Busdma parameters");
  111 SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bpages, 0,
  112            "Total bounce pages");
  113 
  114 struct bus_dmamap {
  115         struct bp_list         bpages;
  116         int                    pagesneeded;
  117         int                    pagesreserved;
  118         bus_dma_tag_t          dmat;
  119         void                  *buf;             /* unmapped buffer pointer */
  120         bus_size_t             buflen;          /* unmapped buffer length */
  121         bus_dmamap_callback_t *callback;
  122         void                  *callback_arg;
  123         STAILQ_ENTRY(bus_dmamap) links;
  124 };
  125 
  126 static STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
  127 static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist;
  128 static struct bus_dmamap nobounce_dmamap;
  129 
  130 static void init_bounce_pages(void *dummy);
  131 static int alloc_bounce_zone(bus_dma_tag_t dmat);
  132 static int alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages);
  133 static int reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
  134                                 int commit);
  135 static bus_addr_t add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map,
  136                                    vm_offset_t vaddr, bus_size_t size);
  137 static void free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage);
  138 static __inline int run_filter(bus_dma_tag_t dmat, bus_addr_t paddr);
  139 
  140 /*
  141  * Return true if a match is made.
  142  *
  143  * To find a match walk the chain of bus_dma_tag_t's looking for 'paddr'.
  144  *
  145  * If paddr is within the bounds of the dma tag then call the filter callback
  146  * to check for a match, if there is no filter callback then assume a match.
  147  */
  148 static __inline int
  149 run_filter(bus_dma_tag_t dmat, bus_addr_t paddr)
  150 {
  151         int retval;
  152 
  153         retval = 0;
  154 
  155         do {
  156                 if (((paddr > dmat->lowaddr && paddr <= dmat->highaddr)
  157                  || ((paddr & (dmat->alignment - 1)) != 0))
  158                  && (dmat->filter == NULL
  159                   || (*dmat->filter)(dmat->filterarg, paddr) != 0))
  160                         retval = 1;
  161 
  162                 dmat = dmat->parent;            
  163         } while (retval == 0 && dmat != NULL);
  164         return (retval);
  165 }
  166 
  167 /*
  168  * Convenience function for manipulating driver locks from busdma (during
  169  * busdma_swi, for example).  Drivers that don't provide their own locks
  170  * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
  171  * non-mutex locking scheme don't have to use this at all.
  172  */
  173 void
  174 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)
  175 {
  176         struct mtx *dmtx;
  177 
  178         dmtx = (struct mtx *)arg;
  179         switch (op) {
  180         case BUS_DMA_LOCK:
  181                 mtx_lock(dmtx);
  182                 break;
  183         case BUS_DMA_UNLOCK:
  184                 mtx_unlock(dmtx);
  185                 break;
  186         default:
  187                 panic("Unknown operation 0x%x for busdma_lock_mutex!", op);
  188         }
  189 }
  190 
  191 /*
  192  * dflt_lock should never get called.  It gets put into the dma tag when
  193  * lockfunc == NULL, which is only valid if the maps that are associated
  194  * with the tag are meant to never be defered.
  195  * XXX Should have a way to identify which driver is responsible here.
  196  */
  197 static void
  198 dflt_lock(void *arg, bus_dma_lock_op_t op)
  199 {
  200         panic("driver error: busdma dflt_lock called");
  201 }
  202 
  203 #define BUS_DMA_COULD_BOUNCE    BUS_DMA_BUS3
  204 #define BUS_DMA_MIN_ALLOC_COMP  BUS_DMA_BUS4
  205 /*
  206  * Allocate a device specific dma_tag.
  207  */
  208 int
  209 bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
  210                    bus_size_t boundary, bus_addr_t lowaddr,
  211                    bus_addr_t highaddr, bus_dma_filter_t *filter,
  212                    void *filterarg, bus_size_t maxsize, int nsegments,
  213                    bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
  214                    void *lockfuncarg, bus_dma_tag_t *dmat)
  215 {
  216         bus_dma_tag_t newtag;
  217         int error = 0;
  218 
  219         /* Basic sanity checking */
  220         if (boundary != 0 && boundary < maxsegsz)
  221                 maxsegsz = boundary;
  222 
  223         /* Return a NULL tag on failure */
  224         *dmat = NULL;
  225 
  226         newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_DEVBUF,
  227             M_ZERO | M_NOWAIT);
  228         if (newtag == NULL) {
  229                 CTR4(KTR_BUSDMA, "%s returned tag %p tag flags 0x%x error %d",
  230                     __func__, newtag, 0, error);
  231                 return (ENOMEM);
  232         }
  233 
  234         newtag->parent = parent;
  235         newtag->alignment = alignment;
  236         newtag->boundary = boundary;
  237         newtag->lowaddr = trunc_page((vm_paddr_t)lowaddr) + (PAGE_SIZE - 1);
  238         newtag->highaddr = trunc_page((vm_paddr_t)highaddr) +
  239             (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         if (lockfunc != NULL) {
  249                 newtag->lockfunc = lockfunc;
  250                 newtag->lockfuncarg = lockfuncarg;
  251         } else {
  252                 newtag->lockfunc = dflt_lock;
  253                 newtag->lockfuncarg = NULL;
  254         }
  255         newtag->segments = NULL;
  256 
  257         /* Take into account any restrictions imposed by our parent tag */
  258         if (parent != NULL) {
  259                 newtag->lowaddr = MIN(parent->lowaddr, newtag->lowaddr);
  260                 newtag->highaddr = MAX(parent->highaddr, newtag->highaddr);
  261                 if (newtag->boundary == 0)
  262                         newtag->boundary = parent->boundary;
  263                 else if (parent->boundary != 0)
  264                         newtag->boundary = MIN(parent->boundary,
  265                                                newtag->boundary);
  266                 if (newtag->filter == NULL) {
  267                         /*
  268                          * Short circuit looking at our parent directly
  269                          * since we have encapsulated all of its information
  270                          */
  271                         newtag->filter = parent->filter;
  272                         newtag->filterarg = parent->filterarg;
  273                         newtag->parent = parent->parent;
  274                 }
  275                 if (newtag->parent != NULL)
  276                         atomic_add_int(&parent->ref_count, 1);
  277         }
  278 
  279         if (newtag->lowaddr < ptoa((vm_paddr_t)Maxmem)
  280          || newtag->alignment > 1)
  281                 newtag->flags |= BUS_DMA_COULD_BOUNCE;
  282 
  283         if (((newtag->flags & BUS_DMA_COULD_BOUNCE) != 0) &&
  284             (flags & BUS_DMA_ALLOCNOW) != 0) {
  285                 struct bounce_zone *bz;
  286 
  287                 /* Must bounce */
  288 
  289                 if ((error = alloc_bounce_zone(newtag)) != 0) {
  290                         free(newtag, M_DEVBUF);
  291                         return (error);
  292                 }
  293                 bz = newtag->bounce_zone;
  294 
  295                 if (ptoa(bz->total_bpages) < maxsize) {
  296                         int pages;
  297 
  298                         pages = atop(maxsize) - bz->total_bpages;
  299 
  300                         /* Add pages to our bounce pool */
  301                         if (alloc_bounce_pages(newtag, pages) < pages)
  302                                 error = ENOMEM;
  303                 }
  304                 /* Performed initial allocation */
  305                 newtag->flags |= BUS_DMA_MIN_ALLOC_COMP;
  306         }
  307         
  308         if (error != 0) {
  309                 free(newtag, M_DEVBUF);
  310         } else {
  311                 *dmat = newtag;
  312         }
  313         CTR4(KTR_BUSDMA, "%s returned tag %p tag flags 0x%x error %d",
  314             __func__, newtag, (newtag != NULL ? newtag->flags : 0), error);
  315         return (error);
  316 }
  317 
  318 int
  319 bus_dma_tag_destroy(bus_dma_tag_t dmat)
  320 {
  321         bus_dma_tag_t dmat_copy;
  322         int error;
  323 
  324         error = 0;
  325         dmat_copy = dmat;
  326 
  327         if (dmat != NULL) {
  328 
  329                 if (dmat->map_count != 0) {
  330                         error = EBUSY;
  331                         goto out;
  332                 }
  333 
  334                 while (dmat != NULL) {
  335                         bus_dma_tag_t parent;
  336 
  337                         parent = dmat->parent;
  338                         atomic_subtract_int(&dmat->ref_count, 1);
  339                         if (dmat->ref_count == 0) {
  340                                 if (dmat->segments != NULL)
  341                                         free(dmat->segments, M_DEVBUF);
  342                                 free(dmat, M_DEVBUF);
  343                                 /*
  344                                  * Last reference count, so
  345                                  * release our reference
  346                                  * count on our parent.
  347                                  */
  348                                 dmat = parent;
  349                         } else
  350                                 dmat = NULL;
  351                 }
  352         }
  353 out:
  354         CTR3(KTR_BUSDMA, "%s tag %p error %d", __func__, dmat_copy, error);
  355         return (error);
  356 }
  357 
  358 /*
  359  * Allocate a handle for mapping from kva/uva/physical
  360  * address space into bus device space.
  361  */
  362 int
  363 bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
  364 {
  365         int error;
  366 
  367         error = 0;
  368 
  369         if (dmat->segments == NULL) {
  370                 dmat->segments = (bus_dma_segment_t *)malloc(
  371                     sizeof(bus_dma_segment_t) * dmat->nsegments, M_DEVBUF,
  372                     M_NOWAIT);
  373                 if (dmat->segments == NULL) {
  374                         CTR3(KTR_BUSDMA, "%s: tag %p error %d",
  375                             __func__, dmat, ENOMEM);
  376                         return (ENOMEM);
  377                 }
  378         }
  379 
  380         /*
  381          * Bouncing might be required if the driver asks for an active
  382          * exclusion region, a data alignment that is stricter than 1, and/or
  383          * an active address boundary.
  384          */
  385         if (dmat->flags & BUS_DMA_COULD_BOUNCE) {
  386 
  387                 /* Must bounce */
  388                 struct bounce_zone *bz;
  389                 int maxpages;
  390 
  391                 if (dmat->bounce_zone == NULL) {
  392                         if ((error = alloc_bounce_zone(dmat)) != 0)
  393                                 return (error);
  394                 }
  395                 bz = dmat->bounce_zone;
  396 
  397                 *mapp = (bus_dmamap_t)malloc(sizeof(**mapp), M_DEVBUF,
  398                                              M_NOWAIT | M_ZERO);
  399                 if (*mapp == NULL) {
  400                         CTR3(KTR_BUSDMA, "%s: tag %p error %d",
  401                             __func__, dmat, ENOMEM);
  402                         return (ENOMEM);
  403                 }
  404 
  405                 /* Initialize the new map */
  406                 STAILQ_INIT(&((*mapp)->bpages));
  407 
  408                 /*
  409                  * Attempt to add pages to our pool on a per-instance
  410                  * basis up to a sane limit.
  411                  */
  412                 if (dmat->alignment > 1)
  413                         maxpages = MAX_BPAGES;
  414                 else
  415                         maxpages = MIN(MAX_BPAGES, Maxmem -atop(dmat->lowaddr));
  416                 if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
  417                  || (dmat->map_count > 0 && bz->total_bpages < maxpages)) {
  418                         int pages;
  419 
  420                         pages = MAX(atop(dmat->maxsize), 1);
  421                         pages = MIN(maxpages - bz->total_bpages, pages);
  422                         pages = MAX(pages, 1);
  423                         if (alloc_bounce_pages(dmat, pages) < pages)
  424                                 error = ENOMEM;
  425 
  426                         if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0) {
  427                                 if (error == 0)
  428                                         dmat->flags |= BUS_DMA_MIN_ALLOC_COMP;
  429                         } else {
  430                                 error = 0;
  431                         }
  432                 }
  433         } else {
  434                 *mapp = NULL;
  435         }
  436         if (error == 0)
  437                 dmat->map_count++;
  438         CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
  439             __func__, dmat, dmat->flags, error);
  440         return (error);
  441 }
  442 
  443 /*
  444  * Destroy a handle for mapping from kva/uva/physical
  445  * address space into bus device space.
  446  */
  447 int
  448 bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
  449 {
  450         if (map != NULL && map != &nobounce_dmamap) {
  451                 if (STAILQ_FIRST(&map->bpages) != NULL) {
  452                         CTR3(KTR_BUSDMA, "%s: tag %p error %d",
  453                             __func__, dmat, EBUSY);
  454                         return (EBUSY);
  455                 }
  456                 free(map, M_DEVBUF);
  457         }
  458         dmat->map_count--;
  459         CTR2(KTR_BUSDMA, "%s: tag %p error 0", __func__, dmat);
  460         return (0);
  461 }
  462 
  463 
  464 /*
  465  * Allocate a piece of memory that can be efficiently mapped into
  466  * bus device space based on the constraints lited in the dma tag.
  467  * A dmamap to for use with dmamap_load is also allocated.
  468  */
  469 int
  470 bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
  471                  bus_dmamap_t *mapp)
  472 {
  473         int mflags;
  474 
  475         if (flags & BUS_DMA_NOWAIT)
  476                 mflags = M_NOWAIT;
  477         else
  478                 mflags = M_WAITOK;
  479         if (flags & BUS_DMA_ZERO)
  480                 mflags |= M_ZERO;
  481 
  482         /* If we succeed, no mapping/bouncing will be required */
  483         *mapp = NULL;
  484 
  485         if (dmat->segments == NULL) {
  486                 dmat->segments = (bus_dma_segment_t *)malloc(
  487                     sizeof(bus_dma_segment_t) * dmat->nsegments, M_DEVBUF,
  488                     M_NOWAIT);
  489                 if (dmat->segments == NULL) {
  490                         CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
  491                             __func__, dmat, dmat->flags, ENOMEM);
  492                         return (ENOMEM);
  493                 }
  494         }
  495 
  496         /* 
  497          * XXX:
  498          * (dmat->alignment < dmat->maxsize) is just a quick hack; the exact
  499          * alignment guarantees of malloc need to be nailed down, and the
  500          * code below should be rewritten to take that into account.
  501          *
  502          * In the meantime, we'll warn the user if malloc gets it wrong.
  503          */
  504         if ((dmat->maxsize <= PAGE_SIZE) &&
  505            (dmat->alignment < dmat->maxsize) &&
  506             dmat->lowaddr >= ptoa((vm_paddr_t)Maxmem)) {
  507                 *vaddr = malloc(dmat->maxsize, M_DEVBUF, mflags);
  508         } else {
  509                 /*
  510                  * XXX Use Contigmalloc until it is merged into this facility
  511                  *     and handles multi-seg allocations.  Nobody is doing
  512                  *     multi-seg allocations yet though.
  513                  * XXX Certain AGP hardware does.
  514                  */
  515                 *vaddr = contigmalloc(dmat->maxsize, M_DEVBUF, mflags,
  516                     0ul, dmat->lowaddr, dmat->alignment? dmat->alignment : 1ul,
  517                     dmat->boundary);
  518         }
  519         if (*vaddr == NULL) {
  520                 CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
  521                     __func__, dmat, dmat->flags, ENOMEM);
  522                 return (ENOMEM);
  523         } else if ((uintptr_t)*vaddr & (dmat->alignment - 1)) {
  524                 printf("bus_dmamem_alloc failed to align memory properly.\n");
  525         }
  526         if (flags & BUS_DMA_NOCACHE)
  527                 pmap_change_attr((vm_offset_t)*vaddr, dmat->maxsize,
  528                     PAT_UNCACHEABLE);
  529         CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
  530             __func__, dmat, dmat->flags, 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         pmap_change_attr((vm_offset_t)vaddr, dmat->maxsize, PAT_WRITE_BACK);
  548         if ((dmat->maxsize <= PAGE_SIZE) &&
  549            (dmat->alignment < dmat->maxsize) &&
  550             dmat->lowaddr >= ptoa((vm_paddr_t)Maxmem))
  551                 free(vaddr, M_DEVBUF);
  552         else {
  553                 contigfree(vaddr, dmat->maxsize, M_DEVBUF);
  554         }
  555         CTR3(KTR_BUSDMA, "%s: tag %p flags 0x%x", __func__, dmat, dmat->flags);
  556 }
  557 
  558 /*
  559  * Utility function to load a linear buffer.  lastaddrp holds state
  560  * between invocations (for multiple-buffer loads).  segp contains
  561  * the starting segment on entrace, and the ending segment on exit.
  562  * first indicates if this is the first invocation of this function.
  563  */
  564 static __inline int
  565 _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
  566                         bus_dmamap_t map,
  567                         void *buf, bus_size_t buflen,
  568                         pmap_t pmap,
  569                         int flags,
  570                         bus_addr_t *lastaddrp,
  571                         bus_dma_segment_t *segs,
  572                         int *segp,
  573                         int first)
  574 {
  575         bus_size_t sgsize;
  576         bus_addr_t curaddr, lastaddr, baddr, bmask;
  577         vm_offset_t vaddr;
  578         bus_addr_t paddr;
  579         int needbounce = 0;
  580         int seg;
  581 
  582         if (map == NULL)
  583                 map = &nobounce_dmamap;
  584 
  585         if ((map != &nobounce_dmamap && map->pagesneeded == 0) 
  586          && ((dmat->flags & BUS_DMA_COULD_BOUNCE) != 0)) {
  587                 vm_offset_t     vendaddr;
  588 
  589                 CTR4(KTR_BUSDMA, "lowaddr= %d Maxmem= %d, boundary= %d, "
  590                     "alignment= %d", dmat->lowaddr, ptoa((vm_paddr_t)Maxmem),
  591                     dmat->boundary, dmat->alignment);
  592                 CTR3(KTR_BUSDMA, "map= %p, nobouncemap= %p, pagesneeded= %d",
  593                     map, &nobounce_dmamap, map->pagesneeded);
  594                 /*
  595                  * Count the number of bounce pages
  596                  * needed in order to complete this transfer
  597                  */
  598                 vaddr = trunc_page((vm_offset_t)buf);
  599                 vendaddr = (vm_offset_t)buf + buflen;
  600 
  601                 while (vaddr < vendaddr) {
  602                         paddr = pmap_kextract(vaddr);
  603                         if (run_filter(dmat, paddr) != 0) {
  604                                 needbounce = 1;
  605                                 map->pagesneeded++;
  606                         }
  607                         vaddr += PAGE_SIZE;
  608                 }
  609                 CTR1(KTR_BUSDMA, "pagesneeded= %d\n", map->pagesneeded);
  610         }
  611 
  612         /* Reserve Necessary Bounce Pages */
  613         if (map->pagesneeded != 0) {
  614                 mtx_lock(&bounce_lock);
  615                 if (flags & BUS_DMA_NOWAIT) {
  616                         if (reserve_bounce_pages(dmat, map, 0) != 0) {
  617                                 mtx_unlock(&bounce_lock);
  618                                 return (ENOMEM);
  619                         }
  620                 } else {
  621                         if (reserve_bounce_pages(dmat, map, 1) != 0) {
  622                                 /* Queue us for resources */
  623                                 map->dmat = dmat;
  624                                 map->buf = buf;
  625                                 map->buflen = buflen;
  626                                 STAILQ_INSERT_TAIL(&bounce_map_waitinglist,
  627                                     map, links);
  628                                 mtx_unlock(&bounce_lock);
  629                                 return (EINPROGRESS);
  630                         }
  631                 }
  632                 mtx_unlock(&bounce_lock);
  633         }
  634 
  635         vaddr = (vm_offset_t)buf;
  636         lastaddr = *lastaddrp;
  637         bmask = ~(dmat->boundary - 1);
  638 
  639         for (seg = *segp; buflen > 0 ; ) {
  640                 /*
  641                  * Get the physical address for this segment.
  642                  */
  643                 if (pmap)
  644                         curaddr = pmap_extract(pmap, vaddr);
  645                 else
  646                         curaddr = pmap_kextract(vaddr);
  647 
  648                 /*
  649                  * Compute the segment size, and adjust counts.
  650                  */
  651                 sgsize = PAGE_SIZE - ((u_long)curaddr & PAGE_MASK);
  652                 if (buflen < sgsize)
  653                         sgsize = buflen;
  654 
  655                 /*
  656                  * Make sure we don't cross any boundaries.
  657                  */
  658                 if (dmat->boundary > 0) {
  659                         baddr = (curaddr + dmat->boundary) & bmask;
  660                         if (sgsize > (baddr - curaddr))
  661                                 sgsize = (baddr - curaddr);
  662                 }
  663 
  664                 if (map->pagesneeded != 0 && run_filter(dmat, curaddr))
  665                         curaddr = add_bounce_page(dmat, map, vaddr, sgsize);
  666 
  667                 /*
  668                  * Insert chunk into a segment, coalescing with
  669                  * previous segment if possible.
  670                  */
  671                 if (first) {
  672                         segs[seg].ds_addr = curaddr;
  673                         segs[seg].ds_len = sgsize;
  674                         first = 0;
  675                 } else {
  676                         if (needbounce == 0 && curaddr == lastaddr &&
  677                             (segs[seg].ds_len + sgsize) <= dmat->maxsegsz &&
  678                             (dmat->boundary == 0 ||
  679                              (segs[seg].ds_addr & bmask) == (curaddr & bmask)))
  680                                 segs[seg].ds_len += sgsize;
  681                         else {
  682                                 if (++seg >= dmat->nsegments)
  683                                         break;
  684                                 segs[seg].ds_addr = curaddr;
  685                                 segs[seg].ds_len = sgsize;
  686                         }
  687                 }
  688 
  689                 lastaddr = curaddr + sgsize;
  690                 vaddr += sgsize;
  691                 buflen -= sgsize;
  692         }
  693 
  694         *segp = seg;
  695         *lastaddrp = lastaddr;
  696 
  697         /*
  698          * Did we fit?
  699          */
  700         return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
  701 }
  702 
  703 /*
  704  * Map the buffer buf into bus space using the dmamap map.
  705  */
  706 int
  707 bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
  708                 bus_size_t buflen, bus_dmamap_callback_t *callback,
  709                 void *callback_arg, int flags)
  710 {
  711         bus_addr_t              lastaddr = 0;
  712         int                     error, nsegs = 0;
  713 
  714         if (map != NULL) {
  715                 flags |= BUS_DMA_WAITOK;
  716                 map->callback = callback;
  717                 map->callback_arg = callback_arg;
  718         }
  719 
  720         error = _bus_dmamap_load_buffer(dmat, map, buf, buflen, NULL, flags,
  721              &lastaddr, dmat->segments, &nsegs, 1);
  722 
  723         CTR5(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d nsegs %d",
  724             __func__, dmat, dmat->flags, error, nsegs + 1);
  725 
  726         if (error == EINPROGRESS) {
  727                 return (error);
  728         }
  729 
  730         if (error)
  731                 (*callback)(callback_arg, dmat->segments, 0, error);
  732         else
  733                 (*callback)(callback_arg, dmat->segments, nsegs + 1, 0);
  734 
  735         /*
  736          * Return ENOMEM to the caller so that it can pass it up the stack.
  737          * This error only happens when NOWAIT is set, so deferal is disabled.
  738          */
  739         if (error == ENOMEM)
  740                 return (error);
  741 
  742         return (0);
  743 }
  744 
  745 
  746 /*
  747  * Like _bus_dmamap_load(), but for mbufs.
  748  */
  749 int
  750 bus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map,
  751                      struct mbuf *m0,
  752                      bus_dmamap_callback2_t *callback, void *callback_arg,
  753                      int flags)
  754 {
  755         int nsegs, error;
  756 
  757         M_ASSERTPKTHDR(m0);
  758 
  759         flags |= BUS_DMA_NOWAIT;
  760         nsegs = 0;
  761         error = 0;
  762         if (m0->m_pkthdr.len <= dmat->maxsize) {
  763                 int first = 1;
  764                 bus_addr_t lastaddr = 0;
  765                 struct mbuf *m;
  766 
  767                 for (m = m0; m != NULL && error == 0; m = m->m_next) {
  768                         if (m->m_len > 0) {
  769                                 error = _bus_dmamap_load_buffer(dmat, map,
  770                                                 m->m_data, m->m_len,
  771                                                 NULL, flags, &lastaddr,
  772                                                 dmat->segments, &nsegs, first);
  773                                 first = 0;
  774                         }
  775                 }
  776         } else {
  777                 error = EINVAL;
  778         }
  779 
  780         if (error) {
  781                 /* force "no valid mappings" in callback */
  782                 (*callback)(callback_arg, dmat->segments, 0, 0, error);
  783         } else {
  784                 (*callback)(callback_arg, dmat->segments,
  785                             nsegs+1, m0->m_pkthdr.len, error);
  786         }
  787         CTR5(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d nsegs %d",
  788             __func__, dmat, dmat->flags, error, nsegs + 1);
  789         return (error);
  790 }
  791 
  792 int
  793 bus_dmamap_load_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map,
  794                         struct mbuf *m0, bus_dma_segment_t *segs, int *nsegs,
  795                         int flags)
  796 {
  797         int error;
  798 
  799         M_ASSERTPKTHDR(m0);
  800 
  801         flags |= BUS_DMA_NOWAIT;
  802         *nsegs = 0;
  803         error = 0;
  804         if (m0->m_pkthdr.len <= dmat->maxsize) {
  805                 int first = 1;
  806                 bus_addr_t lastaddr = 0;
  807                 struct mbuf *m;
  808 
  809                 for (m = m0; m != NULL && error == 0; m = m->m_next) {
  810                         if (m->m_len > 0) {
  811                                 error = _bus_dmamap_load_buffer(dmat, map,
  812                                                 m->m_data, m->m_len,
  813                                                 NULL, flags, &lastaddr,
  814                                                 segs, nsegs, first);
  815                                 first = 0;
  816                         }
  817                 }
  818         } else {
  819                 error = EINVAL;
  820         }
  821 
  822         /* XXX FIXME: Having to increment nsegs is really annoying */
  823         ++*nsegs;
  824         CTR5(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d nsegs %d",
  825             __func__, dmat, dmat->flags, error, *nsegs);
  826         return (error);
  827 }
  828 
  829 /*
  830  * Like _bus_dmamap_load(), but for uios.
  831  */
  832 int
  833 bus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map,
  834                     struct uio *uio,
  835                     bus_dmamap_callback2_t *callback, void *callback_arg,
  836                     int flags)
  837 {
  838         bus_addr_t lastaddr;
  839         int nsegs, error, first, i;
  840         bus_size_t resid;
  841         struct iovec *iov;
  842         pmap_t pmap;
  843 
  844         flags |= BUS_DMA_NOWAIT;
  845         resid = uio->uio_resid;
  846         iov = uio->uio_iov;
  847 
  848         if (uio->uio_segflg == UIO_USERSPACE) {
  849                 KASSERT(uio->uio_td != NULL,
  850                         ("bus_dmamap_load_uio: USERSPACE but no proc"));
  851                 pmap = vmspace_pmap(uio->uio_td->td_proc->p_vmspace);
  852         } else
  853                 pmap = NULL;
  854 
  855         nsegs = 0;
  856         error = 0;
  857         first = 1;
  858         for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
  859                 /*
  860                  * Now at the first iovec to load.  Load each iovec
  861                  * until we have exhausted the residual count.
  862                  */
  863                 bus_size_t minlen =
  864                         resid < iov[i].iov_len ? resid : iov[i].iov_len;
  865                 caddr_t addr = (caddr_t) iov[i].iov_base;
  866 
  867                 if (minlen > 0) {
  868                         error = _bus_dmamap_load_buffer(dmat, map,
  869                                         addr, minlen, pmap, flags, &lastaddr,
  870                                         dmat->segments, &nsegs, first);
  871                         first = 0;
  872 
  873                         resid -= minlen;
  874                 }
  875         }
  876 
  877         if (error) {
  878                 /* force "no valid mappings" in callback */
  879                 (*callback)(callback_arg, dmat->segments, 0, 0, error);
  880         } else {
  881                 (*callback)(callback_arg, dmat->segments,
  882                             nsegs+1, uio->uio_resid, error);
  883         }
  884         CTR5(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d nsegs %d",
  885             __func__, dmat, dmat->flags, error, nsegs + 1);
  886         return (error);
  887 }
  888 
  889 /*
  890  * Release the mapping held by map.
  891  */
  892 void
  893 _bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
  894 {
  895         struct bounce_page *bpage;
  896 
  897         while ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
  898                 STAILQ_REMOVE_HEAD(&map->bpages, links);
  899                 free_bounce_page(dmat, bpage);
  900         }
  901 }
  902 
  903 void
  904 _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
  905 {
  906         struct bounce_page *bpage;
  907 
  908         if ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
  909                 /*
  910                  * Handle data bouncing.  We might also
  911                  * want to add support for invalidating
  912                  * the caches on broken hardware
  913                  */
  914                 dmat->bounce_zone->total_bounced++;
  915                 CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x op 0x%x "
  916                     "performing bounce", __func__, op, dmat, dmat->flags);
  917 
  918                 if (op & BUS_DMASYNC_PREWRITE) {
  919                         while (bpage != NULL) {
  920                                 bcopy((void *)bpage->datavaddr,
  921                                       (void *)bpage->vaddr,
  922                                       bpage->datacount);
  923                                 bpage = STAILQ_NEXT(bpage, links);
  924                         }
  925                 }
  926 
  927                 if (op & BUS_DMASYNC_POSTREAD) {
  928                         while (bpage != NULL) {
  929                                 bcopy((void *)bpage->vaddr,
  930                                       (void *)bpage->datavaddr,
  931                                       bpage->datacount);
  932                                 bpage = STAILQ_NEXT(bpage, links);
  933                         }
  934                 }
  935         }
  936 }
  937 
  938 static void
  939 init_bounce_pages(void *dummy __unused)
  940 {
  941 
  942         total_bpages = 0;
  943         STAILQ_INIT(&bounce_zone_list);
  944         STAILQ_INIT(&bounce_map_waitinglist);
  945         STAILQ_INIT(&bounce_map_callbacklist);
  946         mtx_init(&bounce_lock, "bounce pages lock", NULL, MTX_DEF);
  947 }
  948 SYSINIT(bpages, SI_SUB_LOCK, SI_ORDER_ANY, init_bounce_pages, NULL);
  949 
  950 static struct sysctl_ctx_list *
  951 busdma_sysctl_tree(struct bounce_zone *bz)
  952 {
  953         return (&bz->sysctl_tree);
  954 }
  955 
  956 static struct sysctl_oid *
  957 busdma_sysctl_tree_top(struct bounce_zone *bz)
  958 {
  959         return (bz->sysctl_tree_top);
  960 }
  961 
  962 static int
  963 alloc_bounce_zone(bus_dma_tag_t dmat)
  964 {
  965         struct bounce_zone *bz;
  966 
  967         /* Check to see if we already have a suitable zone */
  968         STAILQ_FOREACH(bz, &bounce_zone_list, links) {
  969                 if ((dmat->alignment <= bz->alignment)
  970                  && (dmat->boundary <= bz->boundary)
  971                  && (dmat->lowaddr >= bz->lowaddr)) {
  972                         dmat->bounce_zone = bz;
  973                         return (0);
  974                 }
  975         }
  976 
  977         if ((bz = (struct bounce_zone *)malloc(sizeof(*bz), M_DEVBUF,
  978             M_NOWAIT | M_ZERO)) == NULL)
  979                 return (ENOMEM);
  980 
  981         STAILQ_INIT(&bz->bounce_page_list);
  982         bz->free_bpages = 0;
  983         bz->reserved_bpages = 0;
  984         bz->active_bpages = 0;
  985         bz->lowaddr = dmat->lowaddr;
  986         bz->alignment = dmat->alignment;
  987         bz->boundary = dmat->boundary;
  988         snprintf(bz->zoneid, 8, "zone%d", busdma_zonecount);
  989         busdma_zonecount++;
  990         snprintf(bz->lowaddrid, 18, "%#jx", (uintmax_t)bz->lowaddr);
  991         STAILQ_INSERT_TAIL(&bounce_zone_list, bz, links);
  992         dmat->bounce_zone = bz;
  993 
  994         sysctl_ctx_init(&bz->sysctl_tree);
  995         bz->sysctl_tree_top = SYSCTL_ADD_NODE(&bz->sysctl_tree,
  996             SYSCTL_STATIC_CHILDREN(_hw_busdma), OID_AUTO, bz->zoneid,
  997             CTLFLAG_RD, 0, "");
  998         if (bz->sysctl_tree_top == NULL) {
  999                 sysctl_ctx_free(&bz->sysctl_tree);
 1000                 return (0);     /* XXX error code? */
 1001         }
 1002 
 1003         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1004             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1005             "total_bpages", CTLFLAG_RD, &bz->total_bpages, 0,
 1006             "Total bounce pages");
 1007         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1008             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1009             "free_bpages", CTLFLAG_RD, &bz->free_bpages, 0,
 1010             "Free bounce pages");
 1011         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1012             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1013             "reserved_bpages", CTLFLAG_RD, &bz->reserved_bpages, 0,
 1014             "Reserved bounce pages");
 1015         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1016             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1017             "active_bpages", CTLFLAG_RD, &bz->active_bpages, 0,
 1018             "Active bounce pages");
 1019         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1020             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1021             "total_bounced", CTLFLAG_RD, &bz->total_bounced, 0,
 1022             "Total bounce requests");
 1023         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1024             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1025             "total_deferred", CTLFLAG_RD, &bz->total_deferred, 0,
 1026             "Total bounce requests that were deferred");
 1027         SYSCTL_ADD_STRING(busdma_sysctl_tree(bz),
 1028             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1029             "lowaddr", CTLFLAG_RD, bz->lowaddrid, 0, "");
 1030         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1031             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1032             "alignment", CTLFLAG_RD, &bz->alignment, 0, "");
 1033         SYSCTL_ADD_INT(busdma_sysctl_tree(bz),
 1034             SYSCTL_CHILDREN(busdma_sysctl_tree_top(bz)), OID_AUTO,
 1035             "boundary", CTLFLAG_RD, &bz->boundary, 0, "");
 1036 
 1037         return (0);
 1038 }
 1039 
 1040 static int
 1041 alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages)
 1042 {
 1043         struct bounce_zone *bz;
 1044         int count;
 1045 
 1046         bz = dmat->bounce_zone;
 1047         count = 0;
 1048         while (numpages > 0) {
 1049                 struct bounce_page *bpage;
 1050 
 1051                 bpage = (struct bounce_page *)malloc(sizeof(*bpage), M_DEVBUF,
 1052                                                      M_NOWAIT | M_ZERO);
 1053 
 1054                 if (bpage == NULL)
 1055                         break;
 1056                 bpage->vaddr = (vm_offset_t)contigmalloc(PAGE_SIZE, M_DEVBUF,
 1057                                                          M_NOWAIT, 0ul,
 1058                                                          bz->lowaddr,
 1059                                                          PAGE_SIZE,
 1060                                                          bz->boundary);
 1061                 if (bpage->vaddr == 0) {
 1062                         free(bpage, M_DEVBUF);
 1063                         break;
 1064                 }
 1065                 bpage->busaddr = pmap_kextract(bpage->vaddr);
 1066                 mtx_lock(&bounce_lock);
 1067                 STAILQ_INSERT_TAIL(&bz->bounce_page_list, bpage, links);
 1068                 total_bpages++;
 1069                 bz->total_bpages++;
 1070                 bz->free_bpages++;
 1071                 mtx_unlock(&bounce_lock);
 1072                 count++;
 1073                 numpages--;
 1074         }
 1075         return (count);
 1076 }
 1077 
 1078 static int
 1079 reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int commit)
 1080 {
 1081         struct bounce_zone *bz;
 1082         int pages;
 1083 
 1084         mtx_assert(&bounce_lock, MA_OWNED);
 1085         bz = dmat->bounce_zone;
 1086         pages = MIN(bz->free_bpages, map->pagesneeded - map->pagesreserved);
 1087         if (commit == 0 && map->pagesneeded > (map->pagesreserved + pages))
 1088                 return (map->pagesneeded - (map->pagesreserved + pages));
 1089         bz->free_bpages -= pages;
 1090         bz->reserved_bpages += pages;
 1091         map->pagesreserved += pages;
 1092         pages = map->pagesneeded - map->pagesreserved;
 1093 
 1094         return (pages);
 1095 }
 1096 
 1097 static bus_addr_t
 1098 add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
 1099                 bus_size_t size)
 1100 {
 1101         struct bounce_zone *bz;
 1102         struct bounce_page *bpage;
 1103 
 1104         KASSERT(dmat->bounce_zone != NULL, ("no bounce zone in dma tag"));
 1105         KASSERT(map != NULL && map != &nobounce_dmamap,
 1106             ("add_bounce_page: bad map %p", map));
 1107 
 1108         bz = dmat->bounce_zone;
 1109         if (map->pagesneeded == 0)
 1110                 panic("add_bounce_page: map doesn't need any pages");
 1111         map->pagesneeded--;
 1112 
 1113         if (map->pagesreserved == 0)
 1114                 panic("add_bounce_page: map doesn't need any pages");
 1115         map->pagesreserved--;
 1116 
 1117         mtx_lock(&bounce_lock);
 1118         bpage = STAILQ_FIRST(&bz->bounce_page_list);
 1119         if (bpage == NULL)
 1120                 panic("add_bounce_page: free page list is empty");
 1121 
 1122         STAILQ_REMOVE_HEAD(&bz->bounce_page_list, links);
 1123         bz->reserved_bpages--;
 1124         bz->active_bpages++;
 1125         mtx_unlock(&bounce_lock);
 1126 
 1127         bpage->datavaddr = vaddr;
 1128         bpage->datacount = size;
 1129         STAILQ_INSERT_TAIL(&(map->bpages), bpage, links);
 1130         return (bpage->busaddr);
 1131 }
 1132 
 1133 static void
 1134 free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
 1135 {
 1136         struct bus_dmamap *map;
 1137         struct bounce_zone *bz;
 1138 
 1139         bz = dmat->bounce_zone;
 1140         bpage->datavaddr = 0;
 1141         bpage->datacount = 0;
 1142 
 1143         mtx_lock(&bounce_lock);
 1144         STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);
 1145         bz->free_bpages++;
 1146         bz->active_bpages--;
 1147         if ((map = STAILQ_FIRST(&bounce_map_waitinglist)) != NULL) {
 1148                 if (reserve_bounce_pages(map->dmat, map, 1) == 0) {
 1149                         STAILQ_REMOVE_HEAD(&bounce_map_waitinglist, links);
 1150                         STAILQ_INSERT_TAIL(&bounce_map_callbacklist,
 1151                                            map, links);
 1152                         busdma_swi_pending = 1;
 1153                         bz->total_deferred++;
 1154                         swi_sched(vm_ih, 0);
 1155                 }
 1156         }
 1157         mtx_unlock(&bounce_lock);
 1158 }
 1159 
 1160 void
 1161 busdma_swi(void)
 1162 {
 1163         bus_dma_tag_t dmat;
 1164         struct bus_dmamap *map;
 1165 
 1166         mtx_lock(&bounce_lock);
 1167         while ((map = STAILQ_FIRST(&bounce_map_callbacklist)) != NULL) {
 1168                 STAILQ_REMOVE_HEAD(&bounce_map_callbacklist, links);
 1169                 mtx_unlock(&bounce_lock);
 1170                 dmat = map->dmat;
 1171                 (dmat->lockfunc)(dmat->lockfuncarg, BUS_DMA_LOCK);
 1172                 bus_dmamap_load(map->dmat, map, map->buf, map->buflen,
 1173                                 map->callback, map->callback_arg, /*flags*/0);
 1174                 (dmat->lockfunc)(dmat->lockfuncarg, BUS_DMA_UNLOCK);
 1175                 mtx_lock(&bounce_lock);
 1176         }
 1177         mtx_unlock(&bounce_lock);
 1178 }

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