efi-bgrt.c

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/*
 * Copyright 2012 Intel Corporation
 * Author: Josh Triplett <[email protected]>
 *
 * Based on the bgrt driver:
 * Copyright 2012 Red Hat, Inc <[email protected]>
 * Author: Matthew Garrett
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/kernel.h>
#include <linux/acpi.h>
#include <linux/efi.h>
#include <linux/efi-bgrt.h>

struct acpi_table_bgrt *bgrt_tab;
void *bgrt_image;
size_t bgrt_image_size;

struct bmp_header {
    u16 id;
    u32 size;
} __packed;

void efi_bgrt_init(void)
{
    acpi_status status;
    void __iomem *image;
    bool ioremapped = false;
    struct bmp_header bmp_header;

    if (acpi_disabled)
        return;

    status = acpi_get_table("BGRT", 0,
                            (struct acpi_table_header **)&bgrt_tab);
    if (ACPI_FAILURE(status))
        return;

    if (bgrt_tab->version != 1)
        return;
    if (bgrt_tab->image_type != 0 || !bgrt_tab->image_address)
        return;

    image = efi_lookup_mapped_addr(bgrt_tab->image_address);
    if (!image) {
        image = ioremap(bgrt_tab->image_address, sizeof(bmp_header));
        ioremapped = true;
        if (!image)
            return;
    }

    memcpy_fromio(&bmp_header, image, sizeof(bmp_header));
    if (ioremapped)
        iounmap(image);
    bgrt_image_size = bmp_header.size;

    bgrt_image = kmalloc(bgrt_image_size, GFP_KERNEL);
    if (!bgrt_image)
        return;

    if (ioremapped) {
        image = ioremap(bgrt_tab->image_address, bmp_header.size);
        if (!image) {
            kfree(bgrt_image);
            bgrt_image = NULL;
            return;
        }
    }

    memcpy_fromio(bgrt_image, image, bgrt_image_size);
    if (ioremapped)
        iounmap(image);
}