drivers/parisc/iommu-helpers.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #include <linux/prefetch.h>
   3
   4 /**
   5  * iommu_fill_pdir - Insert coalesced scatter/gather chunks into the I/O Pdir.
   6  * @ioc: The I/O Controller.
   7  * @startsg: The scatter/gather list of coalesced chunks.
   8  * @nents: The number of entries in the scatter/gather list.
   9  * @hint: The DMA Hint.
  10  *
  11  * This function inserts the coalesced scatter/gather list chunks into the
  12  * I/O Controller's I/O Pdir.
  13  */
  14 static inline unsigned int
  15 iommu_fill_pdir(struct ioc *ioc, struct scatterlist *startsg, int nents,
  16                 unsigned long hint,
  17                 void (*iommu_io_pdir_entry)(__le64 *, space_t, unsigned long,
  18                                             unsigned long))
  19 {
  20         struct scatterlist *dma_sg = startsg;   /* pointer to current DMA */
  21         unsigned int n_mappings = 0;
  22         unsigned long dma_offset = 0, dma_len = 0;
  23         __le64 *pdirp = NULL;
  24
  25         /* Horrible hack.  For efficiency's sake, dma_sg starts one
  26          * entry below the true start (it is immediately incremented
  27          * in the loop) */
  28          dma_sg--;
  29
  30         while (nents-- > 0) {
  31                 unsigned long vaddr;
  32                 long size;
  33
  34                 DBG_RUN_SG(" %d : %08lx %p/%05x\n", nents,
  35                            (unsigned long)sg_dma_address(startsg),
  36                            sg_virt(startsg), startsg->length
  37                 );
  38
  39
  40                 /*
  41                 ** Look for the start of a new DMA stream
  42                 */
  43
  44                 if (sg_dma_address(startsg) & PIDE_FLAG) {
  45                         u32 pide = sg_dma_address(startsg) & ~PIDE_FLAG;
  46
  47                         BUG_ON(pdirp && (dma_len != sg_dma_len(dma_sg)));
  48
  49                         dma_sg++;
  50
  51                         dma_len = sg_dma_len(startsg);
  52                         sg_dma_len(startsg) = 0;
  53                         dma_offset = (unsigned long) pide & ~IOVP_MASK;
  54                         n_mappings++;
  55 #if defined(ZX1_SUPPORT)
  56                         /* Pluto IOMMU IO Virt Address is not zero based */
  57                         sg_dma_address(dma_sg) = pide | ioc->ibase;
  58 #else
  59                         /* SBA, ccio, and dino are zero based.
  60                          * Trying to save a few CPU cycles for most users.
  61                          */
  62                         sg_dma_address(dma_sg) = pide;
  63 #endif
  64                         pdirp = &(ioc->pdir_base[pide >> IOVP_SHIFT]);
  65                         prefetchw(pdirp);
  66                 }
  67
  68                 BUG_ON(pdirp == NULL);
  69
  70                 vaddr = (unsigned long)sg_virt(startsg);
  71                 sg_dma_len(dma_sg) += startsg->length;
  72                 size = startsg->length + dma_offset;
  73                 dma_offset = 0;
  74 #ifdef IOMMU_MAP_STATS
  75                 ioc->msg_pages += startsg->length >> IOVP_SHIFT;
  76 #endif
  77                 do {
  78                         iommu_io_pdir_entry(pdirp, KERNEL_SPACE,
  79                                             vaddr, hint);
  80                         vaddr += IOVP_SIZE;
  81                         size -= IOVP_SIZE;
  82                         pdirp++;
  83                 } while(unlikely(size > 0));
  84                 startsg++;
  85         }
  86         return(n_mappings);
  87 }
  88
  89
  90 /*
  91 ** First pass is to walk the SG list and determine where the breaks are
  92 ** in the DMA stream. Allocates PDIR entries but does not fill them.
  93 ** Returns the number of DMA chunks.
  94 **
  95 ** Doing the fill separate from the coalescing/allocation keeps the
  96 ** code simpler. Future enhancement could make one pass through
  97 ** the sglist do both.
  98 */
  99
 100 static inline unsigned int
 101 iommu_coalesce_chunks(struct ioc *ioc, struct device *dev,
 102                 struct scatterlist *startsg, int nents,
 103                 int (*iommu_alloc_range)(struct ioc *, struct device *, size_t))
 104 {
 105         struct scatterlist *contig_sg;     /* contig chunk head */
 106         unsigned long dma_offset, dma_len; /* start/len of DMA stream */
 107         unsigned int n_mappings = 0;
 108         unsigned int max_seg_size = min(dma_get_max_seg_size(dev),
 109                                         (unsigned)DMA_CHUNK_SIZE);
 110         unsigned int max_seg_boundary = dma_get_seg_boundary(dev) + 1;
 111         if (max_seg_boundary)   /* check if the addition above didn't overflow */
 112                 max_seg_size = min(max_seg_size, max_seg_boundary);
 113
 114         while (nents > 0) {
 115
 116                 /*
 117                 ** Prepare for first/next DMA stream
 118                 */
 119                 contig_sg = startsg;
 120                 dma_len = startsg->length;
 121                 dma_offset = startsg->offset;
 122
 123                 /* PARANOID: clear entries */
 124                 sg_dma_address(startsg) = 0;
 125                 sg_dma_len(startsg) = 0;
 126
 127                 /*
 128                 ** This loop terminates one iteration "early" since
 129                 ** it's always looking one "ahead".
 130                 */
 131                 while(--nents > 0) {
 132                         unsigned long prev_end, sg_start;
 133
 134                         prev_end = (unsigned long)sg_virt(startsg) +
 135                                                         startsg->length;
 136
 137                         startsg++;
 138                         sg_start = (unsigned long)sg_virt(startsg);
 139
 140                         /* PARANOID: clear entries */
 141                         sg_dma_address(startsg) = 0;
 142                         sg_dma_len(startsg) = 0;
 143
 144                         /*
 145                         ** First make sure current dma stream won't
 146                         ** exceed max_seg_size if we coalesce the
 147                         ** next entry.
 148                         */
 149                         if (unlikely(ALIGN(dma_len + dma_offset + startsg->length, IOVP_SIZE) >
 150                                      max_seg_size))
 151                                 break;
 152
 153                         /*
 154                         * Next see if we can append the next chunk (i.e.
 155                         * it must end on one page and begin on another, or
 156                         * it must start on the same address as the previous
 157                         * entry ended.
 158                         */
 159                         if (unlikely((prev_end != sg_start) ||
 160                                 ((prev_end | sg_start) & ~PAGE_MASK)))
 161                                 break;
 162
 163                         dma_len += startsg->length;
 164                 }
 165
 166                 /*
 167                 ** End of DMA Stream
 168                 ** Terminate last VCONTIG block.
 169                 ** Allocate space for DMA stream.
 170                 */
 171                 sg_dma_len(contig_sg) = dma_len;
 172                 dma_len = ALIGN(dma_len + dma_offset, IOVP_SIZE);
 173                 sg_dma_address(contig_sg) =
 174                         PIDE_FLAG
 175                         | (iommu_alloc_range(ioc, dev, dma_len) << IOVP_SHIFT)
 176                         | dma_offset;
 177                 n_mappings++;
 178         }
 179
 180         return n_mappings;
 181 }
 182