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
  16 static spinlock_t dma_page_lock;
  17 static unsigned long *dma_page;
  18 static unsigned int dma_pages;
  19 static unsigned long dma_base;
  20 static unsigned long dma_size;
  21 static unsigned int dma_initialized;
  22
  23 static void dma_alloc_init(unsigned long start, unsigned long end)
  24 {
  25         spin_lock_init(&dma_page_lock);
  26         dma_initialized = 0;
  27
  28         dma_page = (unsigned long *)__get_free_page(GFP_KERNEL);
  29         memset(dma_page, 0, PAGE_SIZE);
  30         dma_base = PAGE_ALIGN(start);
  31         dma_size = PAGE_ALIGN(end) - PAGE_ALIGN(start);
  32         dma_pages = dma_size >> PAGE_SHIFT;
  33         memset((void *)dma_base, 0, DMA_UNCACHED_REGION);
  34         dma_initialized = 1;
  35
  36         printk(KERN_INFO "%s: dma_page @ 0x%p - %d pages at 0x%08lx\n", __func__,
  37                dma_page, dma_pages, dma_base);
  38 }
  39
  40 static inline unsigned int get_pages(size_t size)
  41 {
  42         return ((size - 1) >> PAGE_SHIFT) + 1;
  43 }
  44
  45 static unsigned long __alloc_dma_pages(unsigned int pages)
  46 {
  47         unsigned long ret = 0, flags;
  48         int i, count = 0;
  49
  50         if (dma_initialized == 0)
  51                 dma_alloc_init(_ramend - DMA_UNCACHED_REGION, _ramend);
  52
  53         spin_lock_irqsave(&dma_page_lock, flags);
  54
  55         for (i = 0; i < dma_pages;) {
  56                 if (test_bit(i++, dma_page) == 0) {
  57                         if (++count == pages) {
  58                                 while (count--)
  59                                         __set_bit(--i, dma_page);
  60
  61                                 ret = dma_base + (i << PAGE_SHIFT);
  62                                 break;
  63                         }
  64                 } else
  65                         count = 0;
  66         }
  67         spin_unlock_irqrestore(&dma_page_lock, flags);
  68         return ret;
  69 }
  70
  71 static void __free_dma_pages(unsigned long addr, unsigned int pages)
  72 {
  73         unsigned long page = (addr - dma_base) >> PAGE_SHIFT;
  74         unsigned long flags;
  75         int i;
  76
  77         if ((page + pages) > dma_pages) {
  78                 printk(KERN_ERR "%s: freeing outside range.\n", __func__);
  79                 BUG();
  80         }
  81
  82         spin_lock_irqsave(&dma_page_lock, flags);
  83         for (i = page; i < page + pages; i++)
  84                 __clear_bit(i, dma_page);
  85
  86         spin_unlock_irqrestore(&dma_page_lock, flags);
  87 }
  88
  89 void *dma_alloc_coherent(struct device *dev, size_t size,
  90                          dma_addr_t *dma_handle, gfp_t gfp)
  91 {
  92         void *ret;
  93
  94         ret = (void *)__alloc_dma_pages(get_pages(size));
  95
  96         if (ret) {
  97                 memset(ret, 0, size);
  98                 *dma_handle = virt_to_phys(ret);
  99         }
 100
 101         return ret;
 102 }
 103 EXPORT_SYMBOL(dma_alloc_coherent);
 104
 105 void
 106 dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 107                   dma_addr_t dma_handle)
 108 {
 109         __free_dma_pages((unsigned long)vaddr, get_pages(size));
 110 }
 111 EXPORT_SYMBOL(dma_free_coherent);
 112
 113 /*
 114  * Streaming DMA mappings
 115  */
 116 void __dma_sync(dma_addr_t addr, size_t size,
 117                 enum dma_data_direction dir)
 118 {
 119         __dma_sync_inline(addr, size, dir);
 120 }
 121 EXPORT_SYMBOL(__dma_sync);
 122
 123 int
 124 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 125            enum dma_data_direction direction)
 126 {
 127         int i;
 128
 129         for (i = 0; i < nents; i++, sg++) {
 130                 sg->dma_address = (dma_addr_t) sg_virt(sg);
 131                 __dma_sync(sg_dma_address(sg), sg_dma_len(sg), direction);
 132         }
 133
 134         return nents;
 135 }
 136 EXPORT_SYMBOL(dma_map_sg);
 137
 138 void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 139                             int nelems, enum dma_data_direction direction)
 140 {
 141         int i;
 142
 143         for (i = 0; i < nelems; i++, sg++) {
 144                 sg->dma_address = (dma_addr_t) sg_virt(sg);
 145                 __dma_sync(sg_dma_address(sg), sg_dma_len(sg), direction);
 146         }
 147 }
 148 EXPORT_SYMBOL(dma_sync_sg_for_device);