kernel/arch/blackfin/kernel/dma-mapping.c

   1 /*
   2  * Dynamic DMA mapping support
   3  *
   4  * Copyright 2005-2009 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/gfp.h>
  11 #include <linux/string.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/dma-mapping.h>
  14 #include <linux/scatterlist.h>
  15 #include <linux/export.h>
  16 #include <linux/bitmap.h>
  17
  18 static spinlock_t dma_page_lock;
  19 static unsigned long *dma_page;
  20 static unsigned int dma_pages;
  21 static unsigned long dma_base;
  22 static unsigned long dma_size;
  23 static unsigned int dma_initialized;
  24
  25 static void dma_alloc_init(unsigned long start, unsigned long end)
  26 {
  27         spin_lock_init(&dma_page_lock);
  28         dma_initialized = 0;
  29
  30         dma_page = (unsigned long *)__get_free_page(GFP_KERNEL);
  31         memset(dma_page, 0, PAGE_SIZE);
  32         dma_base = PAGE_ALIGN(start);
  33         dma_size = PAGE_ALIGN(end) - PAGE_ALIGN(start);
  34         dma_pages = dma_size >> PAGE_SHIFT;
  35         memset((void *)dma_base, 0, DMA_UNCACHED_REGION);
  36         dma_initialized = 1;
  37
  38         printk(KERN_INFO "%s: dma_page @ 0x%p - %d pages at 0x%08lx\n", __func__,
  39                dma_page, dma_pages, dma_base);
  40 }
  41
  42 static inline unsigned int get_pages(size_t size)
  43 {
  44         return ((size - 1) >> PAGE_SHIFT) + 1;
  45 }
  46
  47 static unsigned long __alloc_dma_pages(unsigned int pages)
  48 {
  49         unsigned long ret = 0, flags;
  50         unsigned long start;
  51
  52         if (dma_initialized == 0)
  53                 dma_alloc_init(_ramend - DMA_UNCACHED_REGION, _ramend);
  54
  55         spin_lock_irqsave(&dma_page_lock, flags);
  56
  57         start = bitmap_find_next_zero_area(dma_page, dma_pages, 0, pages, 0);
  58         if (start < dma_pages) {
  59                 ret = dma_base + (start << PAGE_SHIFT);
  60                 bitmap_set(dma_page, start, pages);
  61         }
  62         spin_unlock_irqrestore(&dma_page_lock, flags);
  63         return ret;
  64 }
  65
  66 static void __free_dma_pages(unsigned long addr, unsigned int pages)
  67 {
  68         unsigned long page = (addr - dma_base) >> PAGE_SHIFT;
  69         unsigned long flags;
  70
  71         if ((page + pages) > dma_pages) {
  72                 printk(KERN_ERR "%s: freeing outside range.\n", __func__);
  73                 BUG();
  74         }
  75
  76         spin_lock_irqsave(&dma_page_lock, flags);
  77         bitmap_clear(dma_page, page, pages);
  78         spin_unlock_irqrestore(&dma_page_lock, flags);
  79 }
  80
  81 void *dma_alloc_coherent(struct device *dev, size_t size,
  82                          dma_addr_t *dma_handle, gfp_t gfp)
  83 {
  84         void *ret;
  85
  86         ret = (void *)__alloc_dma_pages(get_pages(size));
  87
  88         if (ret) {
  89                 memset(ret, 0, size);
  90                 *dma_handle = virt_to_phys(ret);
  91         }
  92
  93         return ret;
  94 }
  95 EXPORT_SYMBOL(dma_alloc_coherent);
  96
  97 void
  98 dma_free_coherent(struct device *dev, size_t size, void *vaddr,
  99                   dma_addr_t dma_handle)
 100 {
 101         __free_dma_pages((unsigned long)vaddr, get_pages(size));
 102 }
 103 EXPORT_SYMBOL(dma_free_coherent);
 104
 105 /*
 106  * Streaming DMA mappings
 107  */
 108 void __dma_sync(dma_addr_t addr, size_t size,
 109                 enum dma_data_direction dir)
 110 {
 111         __dma_sync_inline(addr, size, dir);
 112 }
 113 EXPORT_SYMBOL(__dma_sync);
 114
 115 int
 116 dma_map_sg(struct device *dev, struct scatterlist *sg_list, int nents,
 117            enum dma_data_direction direction)
 118 {
 119         struct scatterlist *sg;
 120         int i;
 121
 122         for_each_sg(sg_list, sg, nents, i) {
 123                 sg->dma_address = (dma_addr_t) sg_virt(sg);
 124                 __dma_sync(sg_dma_address(sg), sg_dma_len(sg), direction);
 125         }
 126
 127         return nents;
 128 }
 129 EXPORT_SYMBOL(dma_map_sg);
 130
 131 void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg_list,
 132                             int nelems, enum dma_data_direction direction)
 133 {
 134         struct scatterlist *sg;
 135         int i;
 136
 137         for_each_sg(sg_list, sg, nelems, i) {
 138                 sg->dma_address = (dma_addr_t) sg_virt(sg);
 139                 __dma_sync(sg_dma_address(sg), sg_dma_len(sg), direction);
 140         }
 141 }
 142 EXPORT_SYMBOL(dma_sync_sg_for_device);