arch/avr32/mm/dma-coherent.c

   1 /*
   2  *  Copyright (C) 2004-2006 Atmel Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/dma-mapping.h>
  10
  11 #include <asm/addrspace.h>
  12 #include <asm/cacheflush.h>
  13
  14 void dma_cache_sync(void *vaddr, size_t size, int direction)
  15 {
  16         /*
  17          * No need to sync an uncached area
  18          */
  19         if (PXSEG(vaddr) == P2SEG)
  20                 return;
  21
  22         switch (direction) {
  23         case DMA_FROM_DEVICE:           /* invalidate only */
  24                 dma_cache_inv(vaddr, size);
  25                 break;
  26         case DMA_TO_DEVICE:             /* writeback only */
  27                 dma_cache_wback(vaddr, size);
  28                 break;
  29         case DMA_BIDIRECTIONAL:         /* writeback and invalidate */
  30                 dma_cache_wback_inv(vaddr, size);
  31                 break;
  32         default:
  33                 BUG();
  34         }
  35 }
  36 EXPORT_SYMBOL(dma_cache_sync);
  37
  38 static struct page *__dma_alloc(struct device *dev, size_t size,
  39                                 dma_addr_t *handle, gfp_t gfp)
  40 {
  41         struct page *page, *free, *end;
  42         int order;
  43
  44         size = PAGE_ALIGN(size);
  45         order = get_order(size);
  46
  47         page = alloc_pages(gfp, order);
  48         if (!page)
  49                 return NULL;
  50         split_page(page, order);
  51
  52         /*
  53          * When accessing physical memory with valid cache data, we
  54          * get a cache hit even if the virtual memory region is marked
  55          * as uncached.
  56          *
  57          * Since the memory is newly allocated, there is no point in
  58          * doing a writeback. If the previous owner cares, he should
  59          * have flushed the cache before releasing the memory.
  60          */
  61         invalidate_dcache_region(phys_to_virt(page_to_phys(page)), size);
  62
  63         *handle = page_to_bus(page);
  64         free = page + (size >> PAGE_SHIFT);
  65         end = page + (1 << order);
  66
  67         /*
  68          * Free any unused pages
  69          */
  70         while (free < end) {
  71                 __free_page(free);
  72                 free++;
  73         }
  74
  75         return page;
  76 }
  77
  78 static void __dma_free(struct device *dev, size_t size,
  79                        struct page *page, dma_addr_t handle)
  80 {
  81         struct page *end = page + (PAGE_ALIGN(size) >> PAGE_SHIFT);
  82
  83         while (page < end)
  84                 __free_page(page++);
  85 }
  86
  87 void *dma_alloc_coherent(struct device *dev, size_t size,
  88                          dma_addr_t *handle, gfp_t gfp)
  89 {
  90         struct page *page;
  91         void *ret = NULL;
  92
  93         page = __dma_alloc(dev, size, handle, gfp);
  94         if (page)
  95                 ret = phys_to_uncached(page_to_phys(page));
  96
  97         return ret;
  98 }
  99 EXPORT_SYMBOL(dma_alloc_coherent);
 100
 101 void dma_free_coherent(struct device *dev, size_t size,
 102                        void *cpu_addr, dma_addr_t handle)
 103 {
 104         void *addr = phys_to_cached(uncached_to_phys(cpu_addr));
 105         struct page *page;
 106
 107         pr_debug("dma_free_coherent addr %p (phys %08lx) size %u\n",
 108                  cpu_addr, (unsigned long)handle, (unsigned)size);
 109         BUG_ON(!virt_addr_valid(addr));
 110         page = virt_to_page(addr);
 111         __dma_free(dev, size, page, handle);
 112 }
 113 EXPORT_SYMBOL(dma_free_coherent);
 114
 115 #if 0
 116 void *dma_alloc_writecombine(struct device *dev, size_t size,
 117                              dma_addr_t *handle, gfp_t gfp)
 118 {
 119         struct page *page;
 120
 121         page = __dma_alloc(dev, size, handle, gfp);
 122
 123         /* Now, map the page into P3 with write-combining turned on */
 124         return __ioremap(page_to_phys(page), size, _PAGE_BUFFER);
 125 }
 126 EXPORT_SYMBOL(dma_alloc_writecombine);
 127
 128 void dma_free_writecombine(struct device *dev, size_t size,
 129                            void *cpu_addr, dma_addr_t handle)
 130 {
 131         struct page *page;
 132
 133         iounmap(cpu_addr);
 134
 135         page = bus_to_page(handle);
 136         __dma_free(dev, size, page, handle);
 137 }
 138 EXPORT_SYMBOL(dma_free_writecombine);
 139 #endif