LXR linux/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 <linux/io.h>
  38#include <linux/scatterlist.h>
  39#include <asm/cacheflush.h>
  40#include <asm/bfin-global.h>
  41
  42static spinlock_t dma_page_lock;
  43static unsigned int *dma_page;
  44static unsigned int dma_pages;
  45static unsigned long dma_base;
  46static unsigned long dma_size;
  47static unsigned int dma_initialized;
  48
  49void 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
  66static inline unsigned int get_pages(size_t size)
  67{
  68        return ((size - 1) >> PAGE_SHIFT) + 1;
  69}
  70
  71static 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
  96static 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
 114void *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}
 128EXPORT_SYMBOL(dma_alloc_coherent);
 129
 130void
 131dma_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}
 136EXPORT_SYMBOL(dma_free_coherent);
 137
 138/*
 139 * Dummy functions defined for some existing drivers
 140 */
 141
 142dma_addr_t
 143dma_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}
 153EXPORT_SYMBOL(dma_map_single);
 154
 155int
 156dma_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}
 173EXPORT_SYMBOL(dma_map_sg);
 174
 175void 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}
 180EXPORT_SYMBOL(dma_unmap_single);
 181
 182void 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}
 187EXPORT_SYMBOL(dma_unmap_sg);
 188