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/mm.h>
  11 #include <linux/string.h>
  12 #include <linux/bootmem.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/device.h>
  15 #include <linux/dma-mapping.h>
  16 #include <linux/io.h>
  17 #include <linux/scatterlist.h>
  18 #include <asm/cacheflush.h>
  19 #include <asm/bfin-global.h>
  20
  21 static spinlock_t dma_page_lock;
  22 static unsigned int *dma_page;
  23 static unsigned int dma_pages;
  24 static unsigned long dma_base;
  25 static unsigned long dma_size;
  26 static unsigned int dma_initialized;
  27
  28 void dma_alloc_init(unsigned long start, unsigned long end)
  29 {
  30         spin_lock_init(&dma_page_lock);
  31         dma_initialized = 0;
  32
  33         dma_page = (unsigned int *)__get_free_page(GFP_KERNEL);
  34         memset(dma_page, 0, PAGE_SIZE);
  35         dma_base = PAGE_ALIGN(start);
  36         dma_size = PAGE_ALIGN(end) - PAGE_ALIGN(start);
  37         dma_pages = dma_size >> PAGE_SHIFT;
  38         memset((void *)dma_base, 0, DMA_UNCACHED_REGION);
  39         dma_initialized = 1;
  40
  41         printk(KERN_INFO "%s: dma_page @ 0x%p - %d pages at 0x%08lx\n", __func__,
  42                dma_page, dma_pages, dma_base);
  43 }
  44
  45 static inline unsigned int get_pages(size_t size)
  46 {
  47         return ((size - 1) >> PAGE_SHIFT) + 1;
  48 }
  49
  50 static unsigned long __alloc_dma_pages(unsigned int pages)
  51 {
  52         unsigned long ret = 0, flags;
  53         int i, count = 0;
  54
  55         if (dma_initialized == 0)
  56                 dma_alloc_init(_ramend - DMA_UNCACHED_REGION, _ramend);
  57
  58         spin_lock_irqsave(&dma_page_lock, flags);
  59
  60         for (i = 0; i < dma_pages;) {
  61                 if (dma_page[i++] == 0) {
  62                         if (++count == pages) {
  63                                 while (count--)
  64                                         dma_page[--i] = 1;
  65                                 ret = dma_base + (i << PAGE_SHIFT);
  66                                 break;
  67                         }
  68                 } else
  69                         count = 0;
  70         }
  71         spin_unlock_irqrestore(&dma_page_lock, flags);
  72         return ret;
  73 }
  74
  75 static void __free_dma_pages(unsigned long addr, unsigned int pages)
  76 {
  77         unsigned long page = (addr - dma_base) >> PAGE_SHIFT;
  78         unsigned long flags;
  79         int i;
  80
  81         if ((page + pages) > dma_pages) {
  82                 printk(KERN_ERR "%s: freeing outside range.\n", __func__);
  83                 BUG();
  84         }
  85
  86         spin_lock_irqsave(&dma_page_lock, flags);
  87         for (i = page; i < page + pages; i++) {
  88                 dma_page[i] = 0;
  89         }
  90         spin_unlock_irqrestore(&dma_page_lock, flags);
  91 }
  92
  93 void *dma_alloc_coherent(struct device *dev, size_t size,
  94                          dma_addr_t * dma_handle, gfp_t gfp)
  95 {
  96         void *ret;
  97
  98         ret = (void *)__alloc_dma_pages(get_pages(size));
  99
 100         if (ret) {
 101                 memset(ret, 0, size);
 102                 *dma_handle = virt_to_phys(ret);
 103         }
 104
 105         return ret;
 106 }
 107 EXPORT_SYMBOL(dma_alloc_coherent);
 108
 109 void
 110 dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 111                   dma_addr_t dma_handle)
 112 {
 113         __free_dma_pages((unsigned long)vaddr, get_pages(size));
 114 }
 115 EXPORT_SYMBOL(dma_free_coherent);
 116
 117 /*
 118  * Dummy functions defined for some existing drivers
 119  */
 120
 121 dma_addr_t
 122 dma_map_single(struct device *dev, void *ptr, size_t size,
 123                enum dma_data_direction direction)
 124 {
 125         BUG_ON(direction == DMA_NONE);
 126
 127         invalidate_dcache_range((unsigned long)ptr,
 128                         (unsigned long)ptr + size);
 129
 130         return (dma_addr_t) ptr;
 131 }
 132 EXPORT_SYMBOL(dma_map_single);
 133
 134 int
 135 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 136            enum dma_data_direction direction)
 137 {
 138         int i;
 139
 140         BUG_ON(direction == DMA_NONE);
 141
 142         for (i = 0; i < nents; i++, sg++) {
 143                 sg->dma_address = (dma_addr_t) sg_virt(sg);
 144
 145                 invalidate_dcache_range(sg_dma_address(sg),
 146                                         sg_dma_address(sg) +
 147                                         sg_dma_len(sg));
 148         }
 149
 150         return nents;
 151 }
 152 EXPORT_SYMBOL(dma_map_sg);
 153
 154 void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 155                 enum dma_data_direction direction)
 156 {
 157         BUG_ON(direction == DMA_NONE);
 158 }
 159 EXPORT_SYMBOL(dma_unmap_single);
 160
 161 void dma_unmap_sg(struct device *dev, struct scatterlist *sg,
 162                 int nhwentries, enum dma_data_direction direction)
 163 {
 164         BUG_ON(direction == DMA_NONE);
 165 }
 166 EXPORT_SYMBOL(dma_unmap_sg);