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pci-dma-nommu.c

/* pci-dma-nommu.c: Dynamic DMA mapping support for the FRV
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Woodhouse (dwmw2@infradead.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.
 */

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <asm/io.h>

#if 1
#define DMA_SRAM_START  dma_coherent_mem_start
#define DMA_SRAM_END    dma_coherent_mem_end
#else // Use video RAM on Matrox
#define DMA_SRAM_START  0xe8900000
#define DMA_SRAM_END    0xe8a00000
#endif

00027 struct dma_alloc_record {
      struct list_head  list;
      unsigned long           ofs;
      unsigned long           len;
};

static DEFINE_SPINLOCK(dma_alloc_lock);
static LIST_HEAD(dma_alloc_list);

void *dma_alloc_coherent(struct device *hwdev, size_t size, dma_addr_t *dma_handle, gfp_t gfp)
{
      struct dma_alloc_record *new;
      struct list_head *this = &dma_alloc_list;
      unsigned long flags;
      unsigned long start = DMA_SRAM_START;
      unsigned long end;

      if (!DMA_SRAM_START) {
            printk("%s called without any DMA area reserved!\n", __func__);
            return NULL;
      }

      new = kmalloc(sizeof (*new), GFP_ATOMIC);
      if (!new)
            return NULL;

      /* Round up to a reasonable alignment */
      new->len = (size + 31) & ~31;

      spin_lock_irqsave(&dma_alloc_lock, flags);

      list_for_each (this, &dma_alloc_list) {
            struct dma_alloc_record *this_r = list_entry(this, struct dma_alloc_record, list);
            end = this_r->ofs;

            if (end - start >= size)
                  goto gotone;

            start = this_r->ofs + this_r->len;
      }
      /* Reached end of list. */
      end = DMA_SRAM_END;
      this = &dma_alloc_list;

      if (end - start >= size) {
      gotone:
            new->ofs = start;
            list_add_tail(&new->list, this);
            spin_unlock_irqrestore(&dma_alloc_lock, flags);

            *dma_handle = start;
            return (void *)start;
      }

      kfree(new);
      spin_unlock_irqrestore(&dma_alloc_lock, flags);
      return NULL;
}

EXPORT_SYMBOL(dma_alloc_coherent);

void dma_free_coherent(struct device *hwdev, size_t size, void *vaddr, dma_addr_t dma_handle)
{
      struct dma_alloc_record *rec;
      unsigned long flags;

      spin_lock_irqsave(&dma_alloc_lock, flags);

      list_for_each_entry(rec, &dma_alloc_list, list) {
            if (rec->ofs == dma_handle) {
                  list_del(&rec->list);
                  kfree(rec);
                  spin_unlock_irqrestore(&dma_alloc_lock, flags);
                  return;
            }
      }
      spin_unlock_irqrestore(&dma_alloc_lock, flags);
      BUG();
}

EXPORT_SYMBOL(dma_free_coherent);

/*
 * Map a single buffer of the indicated size for DMA in streaming mode.
 * The 32-bit bus address to use is returned.
 *
 * Once the device is given the dma address, the device owns this memory
 * until either dma_unmap_single or pci_dma_sync_single is performed.
 */
dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
                    enum dma_data_direction direction)
{
      BUG_ON(direction == DMA_NONE);

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

      return virt_to_bus(ptr);
}

EXPORT_SYMBOL(dma_map_single);

/*
 * Map a set of buffers described by scatterlist in streaming
 * mode for DMA.  This is the scather-gather version of the
 * above dma_map_single interface.  Here the scatter gather list
 * elements are each tagged with the appropriate dma address
 * and length.  They are obtained via sg_dma_{address,length}(SG).
 *
 * NOTE: An implementation may be able to use a smaller number of
 *       DMA address/length pairs than there are SG table elements.
 *       (for example via virtual mapping capabilities)
 *       The routine returns the number of addr/length pairs actually
 *       used, at most nents.
 *
 * Device ownership issues as mentioned above for dma_map_single are
 * the same here.
 */
int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
             enum dma_data_direction direction)
{
      int i;

      for (i=0; i<nents; i++)
            frv_cache_wback_inv(sg_dma_address(&sg[i]),
                            sg_dma_address(&sg[i]) + sg_dma_len(&sg[i]));

      BUG_ON(direction == DMA_NONE);

      return nents;
}

EXPORT_SYMBOL(dma_map_sg);

/*
 * Map a single page of the indicated size for DMA in streaming mode.
 * The 32-bit bus address to use is returned.
 *
 * Device ownership issues as mentioned above for dma_map_single are
 * the same here.
 */
dma_addr_t dma_map_page(struct device *dev, struct page *page, unsigned long offset,
                  size_t size, enum dma_data_direction direction)
{
      BUG_ON(direction == DMA_NONE);
      flush_dcache_page(page);
      return (dma_addr_t) page_to_phys(page) + offset;
}

EXPORT_SYMBOL(dma_map_page);

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