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dma-mapping.c

/*
 * File:         arch/blackfin/kernel/dma-mapping.c
 * Based on:
 * Author:
 *
 * Created:
 * Description:  Dynamic DMA mapping support.
 *
 * Modified:
 *               Copyright 2004-2006 Analog Devices Inc.
 *
 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/bootmem.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/io.h>
#include <linux/scatterlist.h>
#include <asm/cacheflush.h>
#include <asm/bfin-global.h>

static spinlock_t dma_page_lock;
static unsigned int *dma_page;
static unsigned int dma_pages;
static unsigned long dma_base;
static unsigned long dma_size;
static unsigned int dma_initialized;

void dma_alloc_init(unsigned long start, unsigned long end)
{
      spin_lock_init(&dma_page_lock);
      dma_initialized = 0;

      dma_page = (unsigned int *)__get_free_page(GFP_KERNEL);
      memset(dma_page, 0, PAGE_SIZE);
      dma_base = PAGE_ALIGN(start);
      dma_size = PAGE_ALIGN(end) - PAGE_ALIGN(start);
      dma_pages = dma_size >> PAGE_SHIFT;
      memset((void *)dma_base, 0, DMA_UNCACHED_REGION);
      dma_initialized = 1;

      printk(KERN_INFO "%s: dma_page @ 0x%p - %d pages at 0x%08lx\n", __FUNCTION__,
             dma_page, dma_pages, dma_base);
}

static inline unsigned int get_pages(size_t size)
{
      return ((size - 1) >> PAGE_SHIFT) + 1;
}

static unsigned long __alloc_dma_pages(unsigned int pages)
{
      unsigned long ret = 0, flags;
      int i, count = 0;

      if (dma_initialized == 0)
            dma_alloc_init(_ramend - DMA_UNCACHED_REGION, _ramend);

      spin_lock_irqsave(&dma_page_lock, flags);

      for (i = 0; i < dma_pages;) {
            if (dma_page[i++] == 0) {
                  if (++count == pages) {
                        while (count--)
                              dma_page[--i] = 1;
                        ret = dma_base + (i << PAGE_SHIFT);
                        break;
                  }
            } else
                  count = 0;
      }
      spin_unlock_irqrestore(&dma_page_lock, flags);
      return ret;
}

static void __free_dma_pages(unsigned long addr, unsigned int pages)
{
      unsigned long page = (addr - dma_base) >> PAGE_SHIFT;
      unsigned long flags;
      int i;

      if ((page + pages) > dma_pages) {
            printk(KERN_ERR "%s: freeing outside range.\n", __FUNCTION__);
            BUG();
      }

      spin_lock_irqsave(&dma_page_lock, flags);
      for (i = page; i < page + pages; i++) {
            dma_page[i] = 0;
      }
      spin_unlock_irqrestore(&dma_page_lock, flags);
}

void *dma_alloc_coherent(struct device *dev, size_t size,
                   dma_addr_t * dma_handle, gfp_t gfp)
{
      void *ret;

      ret = (void *)__alloc_dma_pages(get_pages(size));

      if (ret) {
            memset(ret, 0, size);
            *dma_handle = virt_to_phys(ret);
      }

      return ret;
}
EXPORT_SYMBOL(dma_alloc_coherent);

void
dma_free_coherent(struct device *dev, size_t size, void *vaddr,
              dma_addr_t dma_handle)
{
      __free_dma_pages((unsigned long)vaddr, get_pages(size));
}
EXPORT_SYMBOL(dma_free_coherent);

/*
 * Dummy functions defined for some existing drivers
 */

dma_addr_t
dma_map_single(struct device *dev, void *ptr, size_t size,
             enum dma_data_direction direction)
{
      BUG_ON(direction == DMA_NONE);

      invalidate_dcache_range((unsigned long)ptr,
                  (unsigned long)ptr + size);

      return (dma_addr_t) ptr;
}
EXPORT_SYMBOL(dma_map_single);

int
dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
         enum dma_data_direction direction)
{
      int i;

      BUG_ON(direction == DMA_NONE);

      for (i = 0; i < nents; i++, sg++) {
            sg->dma_address = (dma_addr_t) sg_virt(sg);

            invalidate_dcache_range(sg_dma_address(sg),
                              sg_dma_address(sg) +
                              sg_dma_len(sg));
      }

      return nents;
}
EXPORT_SYMBOL(dma_map_sg);

void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
            enum dma_data_direction direction)
{
      BUG_ON(direction == DMA_NONE);
}
EXPORT_SYMBOL(dma_unmap_single);

void dma_unmap_sg(struct device *dev, struct scatterlist *sg,
            int nhwentries, enum dma_data_direction direction)
{
      BUG_ON(direction == DMA_NONE);
}
EXPORT_SYMBOL(dma_unmap_sg);

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