arch/openrisc/kernel/dma.c

   1 /*
   2  * OpenRISC Linux
   3  *
   4  * Linux architectural port borrowing liberally from similar works of
   5  * others.  All original copyrights apply as per the original source
   6  * declaration.
   7  *
   8  * Modifications for the OpenRISC architecture:
   9  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  10  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  *
  17  * DMA mapping callbacks...
  18  * As alloc_coherent is the only DMA callback being used currently, that's
  19  * the only thing implemented properly.  The rest need looking into...
  20  */
  21
  22 #include <linux/dma-mapping.h>
  23 #include <linux/dma-debug.h>
  24 #include <linux/export.h>
  25 #include <linux/dma-attrs.h>
  26
  27 #include <asm/cpuinfo.h>
  28 #include <asm/spr_defs.h>
  29 #include <asm/tlbflush.h>
  30
  31 static int
  32 page_set_nocache(pte_t *pte, unsigned long addr,
  33                  unsigned long next, struct mm_walk *walk)
  34 {
  35         unsigned long cl;
  36
  37         pte_val(*pte) |= _PAGE_CI;
  38
  39         /*
  40          * Flush the page out of the TLB so that the new page flags get
  41          * picked up next time there's an access
  42          */
  43         flush_tlb_page(NULL, addr);
  44
  45         /* Flush page out of dcache */
  46         for (cl = __pa(addr); cl < __pa(next); cl += cpuinfo.dcache_block_size)
  47                 mtspr(SPR_DCBFR, cl);
  48
  49         return 0;
  50 }
  51
  52 static int
  53 page_clear_nocache(pte_t *pte, unsigned long addr,
  54                    unsigned long next, struct mm_walk *walk)
  55 {
  56         pte_val(*pte) &= ~_PAGE_CI;
  57
  58         /*
  59          * Flush the page out of the TLB so that the new page flags get
  60          * picked up next time there's an access
  61          */
  62         flush_tlb_page(NULL, addr);
  63
  64         return 0;
  65 }
  66
  67 /*
  68  * Alloc "coherent" memory, which for OpenRISC means simply uncached.
  69  *
  70  * This function effectively just calls __get_free_pages, sets the
  71  * cache-inhibit bit on those pages, and makes sure that the pages are
  72  * flushed out of the cache before they are used.
  73  *
  74  * If the NON_CONSISTENT attribute is set, then this function just
  75  * returns "normal", cachable memory.
  76  *
  77  * There are additional flags WEAK_ORDERING and WRITE_COMBINE to take
  78  * into consideration here, too.  All current known implementations of
  79  * the OR1K support only strongly ordered memory accesses, so that flag
  80  * is being ignored for now; uncached but write-combined memory is a
  81  * missing feature of the OR1K.
  82  */
  83 static void *
  84 or1k_dma_alloc(struct device *dev, size_t size,
  85                dma_addr_t *dma_handle, gfp_t gfp,
  86                struct dma_attrs *attrs)
  87 {
  88         unsigned long va;
  89         void *page;
  90         struct mm_walk walk = {
  91                 .pte_entry = page_set_nocache,
  92                 .mm = &init_mm
  93         };
  94
  95         page = alloc_pages_exact(size, gfp);
  96         if (!page)
  97                 return NULL;
  98
  99         /* This gives us the real physical address of the first page. */
 100         *dma_handle = __pa(page);
 101
 102         va = (unsigned long)page;
 103
 104         if (!dma_get_attr(DMA_ATTR_NON_CONSISTENT, attrs)) {
 105                 /*
 106                  * We need to iterate through the pages, clearing the dcache for
 107                  * them and setting the cache-inhibit bit.
 108                  */
 109                 if (walk_page_range(va, va + size, &walk)) {
 110                         free_pages_exact(page, size);
 111                         return NULL;
 112                 }
 113         }
 114
 115         return (void *)va;
 116 }
 117
 118 static void
 119 or1k_dma_free(struct device *dev, size_t size, void *vaddr,
 120               dma_addr_t dma_handle, struct dma_attrs *attrs)
 121 {
 122         unsigned long va = (unsigned long)vaddr;
 123         struct mm_walk walk = {
 124                 .pte_entry = page_clear_nocache,
 125                 .mm = &init_mm
 126         };
 127
 128         if (!dma_get_attr(DMA_ATTR_NON_CONSISTENT, attrs)) {
 129                 /* walk_page_range shouldn't be able to fail here */
 130                 WARN_ON(walk_page_range(va, va + size, &walk));
 131         }
 132
 133         free_pages_exact(vaddr, size);
 134 }
 135
 136 static dma_addr_t
 137 or1k_map_page(struct device *dev, struct page *page,
 138               unsigned long offset, size_t size,
 139               enum dma_data_direction dir,
 140               struct dma_attrs *attrs)
 141 {
 142         unsigned long cl;
 143         dma_addr_t addr = page_to_phys(page) + offset;
 144
 145         switch (dir) {
 146         case DMA_TO_DEVICE:
 147                 /* Flush the dcache for the requested range */
 148                 for (cl = addr; cl < addr + size;
 149                      cl += cpuinfo.dcache_block_size)
 150                         mtspr(SPR_DCBFR, cl);
 151                 break;
 152         case DMA_FROM_DEVICE:
 153                 /* Invalidate the dcache for the requested range */
 154                 for (cl = addr; cl < addr + size;
 155                      cl += cpuinfo.dcache_block_size)
 156                         mtspr(SPR_DCBIR, cl);
 157                 break;
 158         default:
 159                 /*
 160                  * NOTE: If dir == DMA_BIDIRECTIONAL then there's no need to
 161                  * flush nor invalidate the cache here as the area will need
 162                  * to be manually synced anyway.
 163                  */
 164                 break;
 165         }
 166
 167         return addr;
 168 }
 169
 170 static void
 171 or1k_unmap_page(struct device *dev, dma_addr_t dma_handle,
 172                 size_t size, enum dma_data_direction dir,
 173                 struct dma_attrs *attrs)
 174 {
 175         /* Nothing special to do here... */
 176 }
 177
 178 static int
 179 or1k_map_sg(struct device *dev, struct scatterlist *sg,
 180             int nents, enum dma_data_direction dir,
 181             struct dma_attrs *attrs)
 182 {
 183         struct scatterlist *s;
 184         int i;
 185
 186         for_each_sg(sg, s, nents, i) {
 187                 s->dma_address = or1k_map_page(dev, sg_page(s), s->offset,
 188                                                s->length, dir, NULL);
 189         }
 190
 191         return nents;
 192 }
 193
 194 static void
 195 or1k_unmap_sg(struct device *dev, struct scatterlist *sg,
 196               int nents, enum dma_data_direction dir,
 197               struct dma_attrs *attrs)
 198 {
 199         struct scatterlist *s;
 200         int i;
 201
 202         for_each_sg(sg, s, nents, i) {
 203                 or1k_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir, NULL);
 204         }
 205 }
 206
 207 static void
 208 or1k_sync_single_for_cpu(struct device *dev,
 209                          dma_addr_t dma_handle, size_t size,
 210                          enum dma_data_direction dir)
 211 {
 212         unsigned long cl;
 213         dma_addr_t addr = dma_handle;
 214
 215         /* Invalidate the dcache for the requested range */
 216         for (cl = addr; cl < addr + size; cl += cpuinfo.dcache_block_size)
 217                 mtspr(SPR_DCBIR, cl);
 218 }
 219
 220 static void
 221 or1k_sync_single_for_device(struct device *dev,
 222                             dma_addr_t dma_handle, size_t size,
 223                             enum dma_data_direction dir)
 224 {
 225         unsigned long cl;
 226         dma_addr_t addr = dma_handle;
 227
 228         /* Flush the dcache for the requested range */
 229         for (cl = addr; cl < addr + size; cl += cpuinfo.dcache_block_size)
 230                 mtspr(SPR_DCBFR, cl);
 231 }
 232
 233 struct dma_map_ops or1k_dma_map_ops = {
 234         .alloc = or1k_dma_alloc,
 235         .free = or1k_dma_free,
 236         .map_page = or1k_map_page,
 237         .unmap_page = or1k_unmap_page,
 238         .map_sg = or1k_map_sg,
 239         .unmap_sg = or1k_unmap_sg,
 240         .sync_single_for_cpu = or1k_sync_single_for_cpu,
 241         .sync_single_for_device = or1k_sync_single_for_device,
 242 };
 243 EXPORT_SYMBOL(or1k_dma_map_ops);
 244
 245 /* Number of entries preallocated for DMA-API debugging */
 246 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
 247
 248 static int __init dma_init(void)
 249 {
 250         dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
 251
 252         return 0;
 253 }
 254 fs_initcall(dma_init);