drivers/parisc/iommu-helpers.h

   1 #include <linux/prefetch.h>
   2
   3 /**
   4  * iommu_fill_pdir - Insert coalesced scatter/gather chunks into the I/O Pdir.
   5  * @ioc: The I/O Controller.
   6  * @startsg: The scatter/gather list of coalesced chunks.
   7  * @nents: The number of entries in the scatter/gather list.
   8  * @hint: The DMA Hint.
   9  *
  10  * This function inserts the coalesced scatter/gather list chunks into the
  11  * I/O Controller's I/O Pdir.
  12  */
  13 static inline unsigned int
  14 iommu_fill_pdir(struct ioc *ioc, struct scatterlist *startsg, int nents,
  15                 unsigned long hint,
  16                 void (*iommu_io_pdir_entry)(u64 *, space_t, unsigned long,
  17                                             unsigned long))
  18 {
  19         struct scatterlist *dma_sg = startsg;   /* pointer to current DMA */
  20         unsigned int n_mappings = 0;
  21         unsigned long dma_offset = 0, dma_len = 0;
  22         u64 *pdirp = NULL;
  23
  24         /* Horrible hack.  For efficiency's sake, dma_sg starts one
  25          * entry below the true start (it is immediately incremented
  26          * in the loop) */
  27          dma_sg--;
  28
  29         while (nents-- > 0) {
  30                 unsigned long vaddr;
  31                 long size;
  32
  33                 DBG_RUN_SG(" %d : %08lx/%05x %p/%05x\n", nents,
  34                            (unsigned long)sg_dma_address(startsg), cnt,
  35                            sg_virt(startsg), startsg->length
  36                 );
  37
  38
  39                 /*
  40                 ** Look for the start of a new DMA stream
  41                 */
  42
  43                 if (sg_dma_address(startsg) & PIDE_FLAG) {
  44                         u32 pide = sg_dma_address(startsg) & ~PIDE_FLAG;
  45
  46                         BUG_ON(pdirp && (dma_len != sg_dma_len(dma_sg)));
  47
  48                         dma_sg++;
  49
  50                         dma_len = sg_dma_len(startsg);
  51                         sg_dma_len(startsg) = 0;
  52                         dma_offset = (unsigned long) pide & ~IOVP_MASK;
  53                         n_mappings++;
  54 #if defined(ZX1_SUPPORT)
  55                         /* Pluto IOMMU IO Virt Address is not zero based */
  56                         sg_dma_address(dma_sg) = pide | ioc->ibase;
  57 #else
  58                         /* SBA, ccio, and dino are zero based.
  59                          * Trying to save a few CPU cycles for most users.
  60                          */
  61                         sg_dma_address(dma_sg) = pide;
  62 #endif
  63                         pdirp = &(ioc->pdir_base[pide >> IOVP_SHIFT]);
  64                         prefetchw(pdirp);
  65                 }
  66
  67                 BUG_ON(pdirp == NULL);
  68
  69                 vaddr = (unsigned long)sg_virt(startsg);
  70                 sg_dma_len(dma_sg) += startsg->length;
  71                 size = startsg->length + dma_offset;
  72                 dma_offset = 0;
  73 #ifdef IOMMU_MAP_STATS
  74                 ioc->msg_pages += startsg->length >> IOVP_SHIFT;
  75 #endif
  76                 do {
  77                         iommu_io_pdir_entry(pdirp, KERNEL_SPACE,
  78                                             vaddr, hint);
  79                         vaddr += IOVP_SIZE;
  80                         size -= IOVP_SIZE;
  81                         pdirp++;
  82                 } while(unlikely(size > 0));
  83                 startsg++;
  84         }
  85         return(n_mappings);
  86 }
  87
  88
  89 /*
  90 ** First pass is to walk the SG list and determine where the breaks are
  91 ** in the DMA stream. Allocates PDIR entries but does not fill them.
  92 ** Returns the number of DMA chunks.
  93 **
  94 ** Doing the fill separate from the coalescing/allocation keeps the
  95 ** code simpler. Future enhancement could make one pass through
  96 ** the sglist do both.
  97 */
  98
  99 static inline unsigned int
 100 iommu_coalesce_chunks(struct ioc *ioc, struct device *dev,
 101                 struct scatterlist *startsg, int nents,
 102                 int (*iommu_alloc_range)(struct ioc *, struct device *, size_t))
 103 {
 104         struct scatterlist *contig_sg;     /* contig chunk head */
 105         unsigned long dma_offset, dma_len; /* start/len of DMA stream */
 106         unsigned int n_mappings = 0;
 107         unsigned int max_seg_size = min(dma_get_max_seg_size(dev),
 108                                         (unsigned)DMA_CHUNK_SIZE);
 109         unsigned int max_seg_boundary = dma_get_seg_boundary(dev) + 1;
 110         if (max_seg_boundary)   /* check if the addition above didn't overflow */
 111                 max_seg_size = min(max_seg_size, max_seg_boundary);
 112
 113         while (nents > 0) {
 114
 115                 /*
 116                 ** Prepare for first/next DMA stream
 117                 */
 118                 contig_sg = startsg;
 119                 dma_len = startsg->length;
 120                 dma_offset = startsg->offset;
 121
 122                 /* PARANOID: clear entries */
 123                 sg_dma_address(startsg) = 0;
 124                 sg_dma_len(startsg) = 0;
 125
 126                 /*
 127                 ** This loop terminates one iteration "early" since
 128                 ** it's always looking one "ahead".
 129                 */
 130                 while(--nents > 0) {
 131                         unsigned long prev_end, sg_start;
 132
 133                         prev_end = (unsigned long)sg_virt(startsg) +
 134                                                         startsg->length;
 135
 136                         startsg++;
 137                         sg_start = (unsigned long)sg_virt(startsg);
 138
 139                         /* PARANOID: clear entries */
 140                         sg_dma_address(startsg) = 0;
 141                         sg_dma_len(startsg) = 0;
 142
 143                         /*
 144                         ** First make sure current dma stream won't
 145                         ** exceed max_seg_size if we coalesce the
 146                         ** next entry.
 147                         */
 148                         if (unlikely(ALIGN(dma_len + dma_offset + startsg->length, IOVP_SIZE) >
 149                                      max_seg_size))
 150                                 break;
 151
 152                         /*
 153                         * Next see if we can append the next chunk (i.e.
 154                         * it must end on one page and begin on another, or
 155                         * it must start on the same address as the previous
 156                         * entry ended.
 157                         */
 158                         if (unlikely((prev_end != sg_start) ||
 159                                 ((prev_end | sg_start) & ~PAGE_MASK)))
 160                                 break;
 161
 162                         dma_len += startsg->length;
 163                 }
 164
 165                 /*
 166                 ** End of DMA Stream
 167                 ** Terminate last VCONTIG block.
 168                 ** Allocate space for DMA stream.
 169                 */
 170                 sg_dma_len(contig_sg) = dma_len;
 171                 dma_len = ALIGN(dma_len + dma_offset, IOVP_SIZE);
 172                 sg_dma_address(contig_sg) =
 173                         PIDE_FLAG
 174                         | (iommu_alloc_range(ioc, dev, dma_len) << IOVP_SHIFT)
 175                         | dma_offset;
 176                 n_mappings++;
 177         }
 178
 179         return n_mappings;
 180 }
 181