pci-dma.c

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/*
 * arch/xtensa/kernel/pci-dma.c
 *
 * DMA coherent memory allocation.
 *
 * 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.
 *
 * Copyright (C) 2002 - 2005 Tensilica Inc.
 *
 * Based on version for i386.
 *
 * Chris Zankel <[email protected]>
 * Joe Taylor <[email protected], [email protected]>
 */

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

/*
 * Note: We assume that the full memory space is always mapped to 'kseg'
 *   Otherwise we have to use page attributes (not implemented).
 */

void *
dma_alloc_coherent(struct device *dev,size_t size,dma_addr_t *handle,gfp_t flag)
{
    unsigned long ret;
    unsigned long uncached = 0;

    /* ignore region speicifiers */

    flag &= ~(__GFP_DMA | __GFP_HIGHMEM);

    if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
        flag |= GFP_DMA;
    ret = (unsigned long)__get_free_pages(flag, get_order(size));

    if (ret == 0)
        return NULL;

    /* We currently don't support coherent memory outside KSEG */

    if (ret < XCHAL_KSEG_CACHED_VADDR
        || ret >= XCHAL_KSEG_CACHED_VADDR + XCHAL_KSEG_SIZE)
        BUG();


    if (ret != 0) {
        memset((void*) ret, 0, size);
        uncached = ret+XCHAL_KSEG_BYPASS_VADDR-XCHAL_KSEG_CACHED_VADDR;
        *handle = virt_to_bus((void*)ret);
        __flush_invalidate_dcache_range(ret, size);
    }

    return (void*)uncached;
}
EXPORT_SYMBOL(dma_alloc_coherent);

void dma_free_coherent(struct device *hwdev, size_t size,
             void *vaddr, dma_addr_t dma_handle)
{
    long addr=(long)vaddr+XCHAL_KSEG_CACHED_VADDR-XCHAL_KSEG_BYPASS_VADDR;

    if (addr < 0 || addr >= XCHAL_KSEG_SIZE)
        BUG();

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


void consistent_sync(void *vaddr, size_t size, int direction)
{
    switch (direction) {
    case PCI_DMA_NONE:
        BUG();
    case PCI_DMA_FROMDEVICE:        /* invalidate only */
        __invalidate_dcache_range((unsigned long)vaddr,
                          (unsigned long)size);
        break;

    case PCI_DMA_TODEVICE:          /* writeback only */
    case PCI_DMA_BIDIRECTIONAL:     /* writeback and invalidate */
        __flush_invalidate_dcache_range((unsigned long)vaddr,
                            (unsigned long)size);
        break;
    }
}
EXPORT_SYMBOL(consistent_sync);