linux/drivers/parisc/iommu-helpers.h
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   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 */ 
  13static inline unsigned int
  14iommu_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 %08lx/%05x\n", nents,
  34                           (unsigned long)sg_dma_address(startsg), cnt,
  35                           sg_virt_addr(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 = sg_virt_addr(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
  99static inline unsigned int
 100iommu_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 = dma_get_max_seg_size(dev);
 108
 109        while (nents > 0) {
 110
 111                /*
 112                ** Prepare for first/next DMA stream
 113                */
 114                contig_sg = startsg;
 115                dma_len = startsg->length;
 116                dma_offset = sg_virt_addr(startsg) & ~IOVP_MASK;
 117
 118                /* PARANOID: clear entries */
 119                sg_dma_address(startsg) = 0;
 120                sg_dma_len(startsg) = 0;
 121
 122                /*
 123                ** This loop terminates one iteration "early" since
 124                ** it's always looking one "ahead".
 125                */
 126                while(--nents > 0) {
 127                        unsigned long prevstartsg_end, startsg_end;
 128
 129                        prevstartsg_end = sg_virt_addr(startsg) +
 130                                startsg->length;
 131
 132                        startsg++;
 133                        startsg_end = sg_virt_addr(startsg) + 
 134                                startsg->length;
 135
 136                        /* PARANOID: clear entries */
 137                        sg_dma_address(startsg) = 0;
 138                        sg_dma_len(startsg) = 0;
 139
 140                        /*
 141                        ** First make sure current dma stream won't
 142                        ** exceed DMA_CHUNK_SIZE if we coalesce the
 143                        ** next entry.
 144                        */   
 145                        if(unlikely(ALIGN(dma_len + dma_offset + startsg->length,
 146                                            IOVP_SIZE) > DMA_CHUNK_SIZE))
 147                                break;
 148
 149                        if (startsg->length + dma_len > 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
 155                        */
 156                        if (unlikely(((prevstartsg_end | sg_virt_addr(startsg)) & ~PAGE_MASK) != 0))
 157                                break;
 158                        
 159                        dma_len += startsg->length;
 160                }
 161
 162                /*
 163                ** End of DMA Stream
 164                ** Terminate last VCONTIG block.
 165                ** Allocate space for DMA stream.
 166                */
 167                sg_dma_len(contig_sg) = dma_len;
 168                dma_len = ALIGN(dma_len + dma_offset, IOVP_SIZE);
 169                sg_dma_address(contig_sg) =
 170                        PIDE_FLAG 
 171                        | (iommu_alloc_range(ioc, dev, dma_len) << IOVP_SHIFT)
 172                        | dma_offset;
 173                n_mappings++;
 174        }
 175
 176        return n_mappings;
 177}
 178
 179
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