FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_busdma.c

     /*
      * Copyright (c) 2009 The DragonFly Project.  All rights reserved.
      *
      * This code is derived from software contributed to The DragonFly Project
      * by Sepherosa Ziehau <sepherosa@gmail.com>
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     *
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in
     *    the documentation and/or other materials provided with the
     *    distribution.
     * 3. Neither the name of The DragonFly Project nor the names of its
     *    contributors may be used to endorse or promote products derived
     *    from this software without specific, prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
     * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
     * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus_dma.h>
    #include <sys/mbuf.h>
    
    static void
    _bus_dmamem_coherent_cb(void *arg, bus_dma_segment_t *segs, int nseg, int error)
    {
            bus_addr_t *addr = arg;
    
            if (error)
                    return;
    
            KASSERT(nseg == 1, ("too many DMA segments, %d should be 1", nseg));
            *addr = segs->ds_addr;
    }
    
    int
    bus_dmamem_coherent(bus_dma_tag_t parent,
                        bus_size_t alignment, bus_size_t boundary,
                        bus_addr_t lowaddr, bus_addr_t highaddr,
                        bus_size_t maxsize, int flags,
                        bus_dmamem_t *dmem)
    {
            int error;
    
            bzero(dmem, sizeof(*dmem));
    
            error = bus_dma_tag_create(parent, alignment, boundary,
                                       lowaddr, highaddr, NULL, NULL,
                                       maxsize, 1, maxsize, 0,
                                       &dmem->dmem_tag);
            if (error)
                    return error;
    
            error = bus_dmamem_alloc(dmem->dmem_tag, &dmem->dmem_addr,
                                     flags | BUS_DMA_COHERENT, &dmem->dmem_map);
            if (error) {
                    bus_dma_tag_destroy(dmem->dmem_tag);
                    bzero(dmem, sizeof(*dmem));
                    return error;
            }
    
            error = bus_dmamap_load(dmem->dmem_tag, dmem->dmem_map,
                                    dmem->dmem_addr, maxsize,
                                    _bus_dmamem_coherent_cb, &dmem->dmem_busaddr,
                                    flags & BUS_DMA_NOWAIT);
            if (error) {
                    if (error == EINPROGRESS) {
                            panic("DMA coherent memory loading is still "
                                  "in progress\n");
                    }
                    bus_dmamem_free(dmem->dmem_tag, dmem->dmem_addr,
                                    dmem->dmem_map);
                    bus_dma_tag_destroy(dmem->dmem_tag);
                    bzero(dmem, sizeof(*dmem));
                    return error;
            }
            return 0;
    }
    
    void *
    bus_dmamem_coherent_any(bus_dma_tag_t parent,
                            bus_size_t alignment, bus_size_t size, int flags,
                            bus_dma_tag_t *dtag, bus_dmamap_t *dmap,
                           bus_addr_t *busaddr)
   {
           bus_dmamem_t dmem;
           int error;
   
           error = bus_dmamem_coherent(parent, alignment, 0,
                                       BUS_SPACE_MAXADDR, BUS_SPACE_MAXADDR,
                                       size, flags, &dmem);
           if (error)
                   return NULL;
   
           *dtag = dmem.dmem_tag;
           *dmap = dmem.dmem_map;
           *busaddr = dmem.dmem_busaddr;
   
           return dmem.dmem_addr;
   }
   
   int
   bus_dmamap_load_mbuf_defrag(bus_dma_tag_t dmat, bus_dmamap_t map,
                               struct mbuf **m_head,
                               bus_dma_segment_t *segs, int maxsegs,
                               int *nsegs, int flags)
   {
           struct mbuf *m = *m_head;
           int error;
   
           error = bus_dmamap_load_mbuf_segment(dmat, map, m,
                           segs, maxsegs, nsegs, flags);
           if (error == EFBIG) {
                   struct mbuf *m_new;
   
                   m_new = m_defrag(m, MB_DONTWAIT);
                   if (m_new == NULL)
                           return ENOBUFS;
                   else
                           *m_head = m = m_new;
   
                   error = bus_dmamap_load_mbuf_segment(dmat, map, m,
                                   segs, maxsegs, nsegs, flags);
           }
           return error;
   }

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