pci-dma-nommu.c

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

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);

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);

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);

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);