consistent.c

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/*
 * arch/sh/mm/consistent.c
 *
 * Copyright (C) 2004 - 2007  Paul Mundt
 *
 * Declared coherent memory functions based on arch/x86/kernel/pci-dma_32.c
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/dma-debug.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/gfp.h>
#include <asm/cacheflush.h>
#include <asm/addrspace.h>

#define PREALLOC_DMA_DEBUG_ENTRIES  4096

struct dma_map_ops *dma_ops;
EXPORT_SYMBOL(dma_ops);

static int __init dma_init(void)
{
    dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
    return 0;
}
fs_initcall(dma_init);

void *dma_generic_alloc_coherent(struct device *dev, size_t size,
                 dma_addr_t *dma_handle, gfp_t gfp,
                 struct dma_attrs *attrs)
{
    void *ret, *ret_nocache;
    int order = get_order(size);

    gfp |= __GFP_ZERO;

    ret = (void *)__get_free_pages(gfp, order);
    if (!ret)
        return NULL;

    /*
     * Pages from the page allocator may have data present in
     * cache. So flush the cache before using uncached memory.
     */
    dma_cache_sync(dev, ret, size, DMA_BIDIRECTIONAL);

    ret_nocache = (void __force *)ioremap_nocache(virt_to_phys(ret), size);
    if (!ret_nocache) {
        free_pages((unsigned long)ret, order);
        return NULL;
    }

    split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order);

    *dma_handle = virt_to_phys(ret);

    return ret_nocache;
}

void dma_generic_free_coherent(struct device *dev, size_t size,
                   void *vaddr, dma_addr_t dma_handle,
                   struct dma_attrs *attrs)
{
    int order = get_order(size);
    unsigned long pfn = dma_handle >> PAGE_SHIFT;
    int k;

    for (k = 0; k < (1 << order); k++)
        __free_pages(pfn_to_page(pfn + k), 0);

    iounmap(vaddr);
}

void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
            enum dma_data_direction direction)
{
    void *addr;

    addr = __in_29bit_mode() ?
           (void *)CAC_ADDR((unsigned long)vaddr) : vaddr;

    switch (direction) {
    case DMA_FROM_DEVICE:       /* invalidate only */
        __flush_invalidate_region(addr, size);
        break;
    case DMA_TO_DEVICE:     /* writeback only */
        __flush_wback_region(addr, size);
        break;
    case DMA_BIDIRECTIONAL:     /* writeback and invalidate */
        __flush_purge_region(addr, size);
        break;
    default:
        BUG();
    }
}
EXPORT_SYMBOL(dma_cache_sync);

static int __init memchunk_setup(char *str)
{
    return 1; /* accept anything that begins with "memchunk." */
}
__setup("memchunk.", memchunk_setup);

static void __init memchunk_cmdline_override(char *name, unsigned long *sizep)
{
    char *p = boot_command_line;
    int k = strlen(name);

    while ((p = strstr(p, "memchunk."))) {
        p += 9; /* strlen("memchunk.") */
        if (!strncmp(name, p, k) && p[k] == '=') {
            p += k + 1;
            *sizep = memparse(p, NULL);
            pr_info("%s: forcing memory chunk size to 0x%08lx\n",
                name, *sizep);
            break;
        }
    }
}

int __init platform_resource_setup_memory(struct platform_device *pdev,
                      char *name, unsigned long memsize)
{
    struct resource *r;
    dma_addr_t dma_handle;
    void *buf;

    r = pdev->resource + pdev->num_resources - 1;
    if (r->flags) {
        pr_warning("%s: unable to find empty space for resource\n",
            name);
        return -EINVAL;
    }

    memchunk_cmdline_override(name, &memsize);
    if (!memsize)
        return 0;

    buf = dma_alloc_coherent(NULL, memsize, &dma_handle, GFP_KERNEL);
    if (!buf) {
        pr_warning("%s: unable to allocate memory\n", name);
        return -ENOMEM;
    }

    memset(buf, 0, memsize);

    r->flags = IORESOURCE_MEM;
    r->start = dma_handle;
    r->end = r->start + memsize - 1;
    r->name = name;
    return 0;
}