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