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   1 /*
   2  * File:         arch/blackfin/kernel/dma-mapping.c
   3  * Based on:
   4  * Author:
   5  *
   6  * Created:
   7  * Description:  Dynamic DMA mapping support.
   8  *
   9  * Modified:
  10  *               Copyright 2004-2006 Analog Devices Inc.
  11  *
  12  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, see the file COPYING, or write
  26  * to the Free Software Foundation, Inc.,
  27  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  28  */
  29
  30 #include <linux/types.h>
  31 #include <linux/mm.h>
  32 #include <linux/string.h>
  33 #include <linux/bootmem.h>
  34 #include <linux/spinlock.h>
  35 #include <linux/device.h>
  36 #include <linux/dma-mapping.h>
  37 #include <linux/io.h>
  38 #include <linux/scatterlist.h>
  39 #include <asm/cacheflush.h>
  40 #include <asm/bfin-global.h>
  41
  42 static spinlock_t dma_page_lock;
  43 static unsigned int *dma_page;
  44 static unsigned int dma_pages;
  45 static unsigned long dma_base;
  46 static unsigned long dma_size;
  47 static unsigned int dma_initialized;
  48
  49 void dma_alloc_init(unsigned long start, unsigned long end)
  50 {
  51         spin_lock_init(&dma_page_lock);
  52         dma_initialized = 0;
  53
  54         dma_page = (unsigned int *)__get_free_page(GFP_KERNEL);
  55         memset(dma_page, 0, PAGE_SIZE);
  56         dma_base = PAGE_ALIGN(start);
  57         dma_size = PAGE_ALIGN(end) - PAGE_ALIGN(start);
  58         dma_pages = dma_size >> PAGE_SHIFT;
  59         memset((void *)dma_base, 0, DMA_UNCACHED_REGION);
  60         dma_initialized = 1;
  61
  62         printk(KERN_INFO "%s: dma_page @ 0x%p - %d pages at 0x%08lx\n", __func__,
  63                dma_page, dma_pages, dma_base);
  64 }
  65
  66 static inline unsigned int get_pages(size_t size)
  67 {
  68         return ((size - 1) >> PAGE_SHIFT) + 1;
  69 }
  70
  71 static unsigned long __alloc_dma_pages(unsigned int pages)
  72 {
  73         unsigned long ret = 0, flags;
  74         int i, count = 0;
  75
  76         if (dma_initialized == 0)
  77                 dma_alloc_init(_ramend - DMA_UNCACHED_REGION, _ramend);
  78
  79         spin_lock_irqsave(&dma_page_lock, flags);
  80
  81         for (i = 0; i < dma_pages;) {
  82                 if (dma_page[i++] == 0) {
  83                         if (++count == pages) {
  84                                 while (count--)
  85                                         dma_page[--i] = 1;
  86                                 ret = dma_base + (i << PAGE_SHIFT);
  87                                 break;
  88                         }
  89                 } else
  90                         count = 0;
  91         }
  92         spin_unlock_irqrestore(&dma_page_lock, flags);
  93         return ret;
  94 }
  95
  96 static void __free_dma_pages(unsigned long addr, unsigned int pages)
  97 {
  98         unsigned long page = (addr - dma_base) >> PAGE_SHIFT;
  99         unsigned long flags;
 100         int i;
 101
 102         if ((page + pages) > dma_pages) {
 103                 printk(KERN_ERR "%s: freeing outside range.\n", __func__);
 104                 BUG();
 105         }
 106
 107         spin_lock_irqsave(&dma_page_lock, flags);
 108         for (i = page; i < page + pages; i++) {
 109                 dma_page[i] = 0;
 110         }
 111         spin_unlock_irqrestore(&dma_page_lock, flags);
 112 }
 113
 114 void *dma_alloc_coherent(struct device *dev, size_t size,
 115                          dma_addr_t * dma_handle, gfp_t gfp)
 116 {
 117         void *ret;
 118
 119         ret = (void *)__alloc_dma_pages(get_pages(size));
 120
 121         if (ret) {
 122                 memset(ret, 0, size);
 123                 *dma_handle = virt_to_phys(ret);
 124         }
 125
 126         return ret;
 127 }
 128 EXPORT_SYMBOL(dma_alloc_coherent);
 129
 130 void
 131 dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 132                   dma_addr_t dma_handle)
 133 {
 134         __free_dma_pages((unsigned long)vaddr, get_pages(size));
 135 }
 136 EXPORT_SYMBOL(dma_free_coherent);
 137
 138 /*
 139  * Dummy functions defined for some existing drivers
 140  */
 141
 142 dma_addr_t
 143 dma_map_single(struct device *dev, void *ptr, size_t size,
 144                enum dma_data_direction direction)
 145 {
 146         BUG_ON(direction == DMA_NONE);
 147
 148         invalidate_dcache_range((unsigned long)ptr,
 149                         (unsigned long)ptr + size);
 150
 151         return (dma_addr_t) ptr;
 152 }
 153 EXPORT_SYMBOL(dma_map_single);
 154
 155 int
 156 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 157            enum dma_data_direction direction)
 158 {
 159         int i;
 160
 161         BUG_ON(direction == DMA_NONE);
 162
 163         for (i = 0; i < nents; i++, sg++) {
 164                 sg->dma_address = (dma_addr_t) sg_virt(sg);
 165
 166                 invalidate_dcache_range(sg_dma_address(sg),
 167                                         sg_dma_address(sg) +
 168                                         sg_dma_len(sg));
 169         }
 170
 171         return nents;
 172 }
 173 EXPORT_SYMBOL(dma_map_sg);
 174
 175 void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 176                 enum dma_data_direction direction)
 177 {
 178         BUG_ON(direction == DMA_NONE);
 179 }
 180 EXPORT_SYMBOL(dma_unmap_single);
 181
 182 void dma_unmap_sg(struct device *dev, struct scatterlist *sg,
 183                 int nhwentries, enum dma_data_direction direction)
 184 {
 185         BUG_ON(direction == DMA_NONE);
 186 }
 187 EXPORT_SYMBOL(dma_unmap_sg);