dma-alloc.c

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/* MN10300 Dynamic DMA mapping support
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 * Derived from: arch/i386/kernel/pci-dma.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/pci.h>
#include <linux/gfp.h>
#include <linux/export.h>
#include <asm/io.h>

static unsigned long pci_sram_allocated = 0xbc000000;

void *dma_alloc_coherent(struct device *dev, size_t size,
             dma_addr_t *dma_handle, int gfp)
{
    unsigned long addr;
    void *ret;

    pr_debug("dma_alloc_coherent(%s,%zu,%x)\n",
         dev ? dev_name(dev) : "?", size, gfp);

    if (0xbe000000 - pci_sram_allocated >= size) {
        size = (size + 255) & ~255;
        addr = pci_sram_allocated;
        pci_sram_allocated += size;
        ret = (void *) addr;
        goto done;
    }

    /* ignore region specifiers */
    gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);

    if (dev == NULL || dev->coherent_dma_mask < 0xffffffff)
        gfp |= GFP_DMA;

    addr = __get_free_pages(gfp, get_order(size));
    if (!addr)
        return NULL;

    /* map the coherent memory through the uncached memory window */
    ret = (void *) (addr | 0x20000000);

    /* fill the memory with obvious rubbish */
    memset((void *) addr, 0xfb, size);

    /* write back and evict all cache lines covering this region */
    mn10300_dcache_flush_inv_range2(virt_to_phys((void *) addr), PAGE_SIZE);

done:
    *dma_handle = virt_to_bus((void *) addr);
    printk("dma_alloc_coherent() = %p [%x]\n", ret, *dma_handle);
    return ret;
}
EXPORT_SYMBOL(dma_alloc_coherent);

void dma_free_coherent(struct device *dev, size_t size, void *vaddr,
               dma_addr_t dma_handle)
{
    unsigned long addr = (unsigned long) vaddr & ~0x20000000;

    if (addr >= 0x9c000000)
        return;

    free_pages(addr, get_order(size));
}
EXPORT_SYMBOL(dma_free_coherent);