drivers/parisc/iommu-helpers.h

   1 /**
   2  * iommu_fill_pdir - Insert coalesced scatter/gather chunks into the I/O Pdir.
   3  * @ioc: The I/O Controller.
   4  * @startsg: The scatter/gather list of coalesced chunks.
   5  * @nents: The number of entries in the scatter/gather list.
   6  * @hint: The DMA Hint.
   7  *
   8  * This function inserts the coalesced scatter/gather list chunks into the
   9  * I/O Controller's I/O Pdir.
  10  */
  11 static inline unsigned int
  12 iommu_fill_pdir(struct ioc *ioc, struct scatterlist *startsg, int nents,
  13                 unsigned long hint,
  14                 void (*iommu_io_pdir_entry)(u64 *, space_t, unsigned long,
  15                                             unsigned long))
  16 {
  17         struct scatterlist *dma_sg = startsg;   /* pointer to current DMA */
  18         unsigned int n_mappings = 0;
  19         unsigned long dma_offset = 0, dma_len = 0;
  20         u64 *pdirp = NULL;
  21
  22         /* Horrible hack.  For efficiency's sake, dma_sg starts one
  23          * entry below the true start (it is immediately incremented
  24          * in the loop) */
  25          dma_sg--;
  26
  27         while (nents-- > 0) {
  28                 unsigned long vaddr;
  29                 long size;
  30
  31                 DBG_RUN_SG(" %d : %08lx/%05x %08lx/%05x\n", nents,
  32                            (unsigned long)sg_dma_address(startsg), cnt,
  33                            sg_virt_addr(startsg), startsg->length
  34                 );
  35
  36
  37                 /*
  38                 ** Look for the start of a new DMA stream
  39                 */
  40
  41                 if (sg_dma_address(startsg) & PIDE_FLAG) {
  42                         u32 pide = sg_dma_address(startsg) & ~PIDE_FLAG;
  43
  44                         BUG_ON(pdirp && (dma_len != sg_dma_len(dma_sg)));
  45
  46                         dma_sg++;
  47
  48                         dma_len = sg_dma_len(startsg);
  49                         sg_dma_len(startsg) = 0;
  50                         dma_offset = (unsigned long) pide & ~IOVP_MASK;
  51                         n_mappings++;
  52                         sg_dma_address(dma_sg) = pide;
  53                         pdirp = &(ioc->pdir_base[pide >> IOVP_SHIFT]);
  54                         prefetchw(pdirp);
  55                 }
  56
  57                 BUG_ON(pdirp == NULL);
  58
  59                 vaddr = sg_virt_addr(startsg);
  60                 sg_dma_len(dma_sg) += startsg->length;
  61                 size = startsg->length + dma_offset;
  62                 dma_offset = 0;
  63 #ifdef IOMMU_MAP_STATS
  64                 ioc->msg_pages += startsg->length >> IOVP_SHIFT;
  65 #endif
  66                 do {
  67                         iommu_io_pdir_entry(pdirp, KERNEL_SPACE,
  68                                             vaddr, hint);
  69                         vaddr += IOVP_SIZE;
  70                         size -= IOVP_SIZE;
  71                         pdirp++;
  72                 } while(unlikely(size > 0));
  73                 startsg++;
  74         }
  75         return(n_mappings);
  76 }
  77
  78
  79 /*
  80 ** First pass is to walk the SG list and determine where the breaks are
  81 ** in the DMA stream. Allocates PDIR entries but does not fill them.
  82 ** Returns the number of DMA chunks.
  83 **
  84 ** Doing the fill separate from the coalescing/allocation keeps the
  85 ** code simpler. Future enhancement could make one pass through
  86 ** the sglist do both.
  87 */
  88
  89 static inline unsigned int
  90 iommu_coalesce_chunks(struct ioc *ioc, struct scatterlist *startsg, int nents,
  91                       int (*iommu_alloc_range)(struct ioc *, size_t))
  92 {
  93         struct scatterlist *contig_sg;     /* contig chunk head */
  94         unsigned long dma_offset, dma_len; /* start/len of DMA stream */
  95         unsigned int n_mappings = 0;
  96
  97         while (nents > 0) {
  98
  99                 /*
 100                 ** Prepare for first/next DMA stream
 101                 */
 102                 contig_sg = startsg;
 103                 dma_len = startsg->length;
 104                 dma_offset = sg_virt_addr(startsg) & ~IOVP_MASK;
 105
 106                 /* PARANOID: clear entries */
 107                 sg_dma_address(startsg) = 0;
 108                 sg_dma_len(startsg) = 0;
 109
 110                 /*
 111                 ** This loop terminates one iteration "early" since
 112                 ** it's always looking one "ahead".
 113                 */
 114                 while(--nents > 0) {
 115                         unsigned long prevstartsg_end, startsg_end;
 116
 117                         prevstartsg_end = sg_virt_addr(startsg) +
 118                                 startsg->length;
 119
 120                         startsg++;
 121                         startsg_end = sg_virt_addr(startsg) +
 122                                 startsg->length;
 123
 124                         /* PARANOID: clear entries */
 125                         sg_dma_address(startsg) = 0;
 126                         sg_dma_len(startsg) = 0;
 127
 128                         /*
 129                         ** First make sure current dma stream won't
 130                         ** exceed DMA_CHUNK_SIZE if we coalesce the
 131                         ** next entry.
 132                         */
 133                         if(unlikely(ROUNDUP(dma_len + dma_offset + startsg->length,
 134                                             IOVP_SIZE) > DMA_CHUNK_SIZE))
 135                                 break;
 136
 137                         /*
 138                         ** Next see if we can append the next chunk (i.e.
 139                         ** it must end on one page and begin on another
 140                         */
 141                         if (unlikely(((prevstartsg_end | sg_virt_addr(startsg)) & ~PAGE_MASK) != 0))
 142                                 break;
 143
 144                         dma_len += startsg->length;
 145                 }
 146
 147                 /*
 148                 ** End of DMA Stream
 149                 ** Terminate last VCONTIG block.
 150                 ** Allocate space for DMA stream.
 151                 */
 152                 sg_dma_len(contig_sg) = dma_len;
 153                 dma_len = ROUNDUP(dma_len + dma_offset, IOVP_SIZE);
 154                 sg_dma_address(contig_sg) =
 155                         PIDE_FLAG
 156                         | (iommu_alloc_range(ioc, dma_len) << IOVP_SHIFT)
 157                         | dma_offset;
 158                 n_mappings++;
 159         }
 160
 161         return n_mappings;
 162 }
 163