arch/blackfin/kernel/dma-mapping.c

   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 <asm/cacheflush.h>
  38 #include <asm/io.h>
  39 #include <asm/bfin-global.h>
  40
  41 static spinlock_t dma_page_lock;
  42 static unsigned int *dma_page;
  43 static unsigned int dma_pages;
  44 static unsigned long dma_base;
  45 static unsigned long dma_size;
  46 static unsigned int dma_initialized;
  47
  48 void dma_alloc_init(unsigned long start, unsigned long end)
  49 {
  50         spin_lock_init(&dma_page_lock);
  51         dma_initialized = 0;
  52
  53         dma_page = (unsigned int *)__get_free_page(GFP_KERNEL);
  54         memset(dma_page, 0, PAGE_SIZE);
  55         dma_base = PAGE_ALIGN(start);
  56         dma_size = PAGE_ALIGN(end) - PAGE_ALIGN(start);
  57         dma_pages = dma_size >> PAGE_SHIFT;
  58         memset((void *)dma_base, 0, DMA_UNCACHED_REGION);
  59         dma_initialized = 1;
  60
  61         printk(KERN_INFO "%s: dma_page @ 0x%p - %d pages at 0x%08lx\n", __FUNCTION__,
  62                dma_page, dma_pages, dma_base);
  63 }
  64
  65 static inline unsigned int get_pages(size_t size)
  66 {
  67         return ((size - 1) >> PAGE_SHIFT) + 1;
  68 }
  69
  70 static unsigned long __alloc_dma_pages(unsigned int pages)
  71 {
  72         unsigned long ret = 0, flags;
  73         int i, count = 0;
  74
  75         if (dma_initialized == 0)
  76                 dma_alloc_init(_ramend - DMA_UNCACHED_REGION, _ramend);
  77
  78         spin_lock_irqsave(&dma_page_lock, flags);
  79
  80         for (i = 0; i < dma_pages;) {
  81                 if (dma_page[i++] == 0) {
  82                         if (++count == pages) {
  83                                 while (count--)
  84                                         dma_page[--i] = 1;
  85                                 ret = dma_base + (i << PAGE_SHIFT);
  86                                 break;
  87                         }
  88                 } else
  89                         count = 0;
  90         }
  91         spin_unlock_irqrestore(&dma_page_lock, flags);
  92         return ret;
  93 }
  94
  95 static void __free_dma_pages(unsigned long addr, unsigned int pages)
  96 {
  97         unsigned long page = (addr - dma_base) >> PAGE_SHIFT;
  98         unsigned long flags;
  99         int i;
 100
 101         if ((page + pages) > dma_pages) {
 102                 printk(KERN_ERR "%s: freeing outside range.\n", __FUNCTION__);
 103                 BUG();
 104         }
 105
 106         spin_lock_irqsave(&dma_page_lock, flags);
 107         for (i = page; i < page + pages; i++) {
 108                 dma_page[i] = 0;
 109         }
 110         spin_unlock_irqrestore(&dma_page_lock, flags);
 111 }
 112
 113 void *dma_alloc_coherent(struct device *dev, size_t size,
 114                          dma_addr_t * dma_handle, gfp_t gfp)
 115 {
 116         void *ret;
 117
 118         ret = (void *)__alloc_dma_pages(get_pages(size));
 119
 120         if (ret) {
 121                 memset(ret, 0, size);
 122                 *dma_handle = virt_to_phys(ret);
 123         }
 124
 125         return ret;
 126 }
 127 EXPORT_SYMBOL(dma_alloc_coherent);
 128
 129 void
 130 dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 131                   dma_addr_t dma_handle)
 132 {
 133         __free_dma_pages((unsigned long)vaddr, get_pages(size));
 134 }
 135 EXPORT_SYMBOL(dma_free_coherent);
 136
 137 /*
 138  * Dummy functions defined for some existing drivers
 139  */
 140
 141 dma_addr_t
 142 dma_map_single(struct device *dev, void *ptr, size_t size,
 143                enum dma_data_direction direction)
 144 {
 145         BUG_ON(direction == DMA_NONE);
 146
 147         invalidate_dcache_range((unsigned long)ptr,
 148                         (unsigned long)ptr + size);
 149
 150         return (dma_addr_t) ptr;
 151 }
 152 EXPORT_SYMBOL(dma_map_single);
 153
 154 int
 155 dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 156            enum dma_data_direction direction)
 157 {
 158         int i;
 159
 160         BUG_ON(direction == DMA_NONE);
 161
 162         for (i = 0; i < nents; i++)
 163                 invalidate_dcache_range(sg_dma_address(&sg[i]),
 164                                         sg_dma_address(&sg[i]) +
 165                                         sg_dma_len(&sg[i]));
 166
 167         return nents;
 168 }
 169 EXPORT_SYMBOL(dma_map_sg);
 170
 171 void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
 172                 enum dma_data_direction direction)
 173 {
 174         BUG_ON(direction == DMA_NONE);
 175 }
 176 EXPORT_SYMBOL(dma_unmap_single);
 177
 178 void dma_unmap_sg(struct device *dev, struct scatterlist *sg,
 179                 int nhwentries, enum dma_data_direction direction)
 180 {
 181         BUG_ON(direction == DMA_NONE);
 182 }
 183 EXPORT_SYMBOL(dma_unmap_sg);