// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2012 Intel Corporation
 * Author: Josh Triplett <josh@joshtriplett.org>
 *
 * Based on the bgrt driver:
 * Copyright 2012 Red Hat, Inc <mjg@redhat.com>
 * Author: Matthew Garrett
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/acpi.h>
#include <linux/efi.h>
#include <linux/efi-bgrt.h>

struct acpi_table_bgrt bgrt_tab;
size_t bgrt_image_size;

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

void __init efi_bgrt_init(struct acpi_table_header *table)
{
        void *image;
        struct bmp_header bmp_header;
        struct acpi_table_bgrt *bgrt = &bgrt_tab;
        int mem_type;

        if (acpi_disabled)
                return;

        if (!efi_enabled(EFI_MEMMAP) && !efi_enabled(EFI_PARAVIRT))
                return;

        if (table->length < sizeof(bgrt_tab)) {
                pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n",
                       table->length, sizeof(bgrt_tab));
                return;
        }
        *bgrt = *(struct acpi_table_bgrt *)table;
        /*
         * Only version 1 is defined but some older laptops (seen on Lenovo
         * Ivy Bridge models) have a correct version 1 BGRT table with the
         * version set to 0, so we accept version 0 and 1.
         */
        if (bgrt->version > 1) {
                pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n",
                       bgrt->version);
                goto out;
        }
        if (bgrt->image_type != 0) {
                pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n",
                       bgrt->image_type);
                goto out;
        }
        if (!bgrt->image_address) {
                pr_notice("Ignoring BGRT: null image address\n");
                goto out;
        }

        mem_type = efi_mem_type(bgrt->image_address);
        if (mem_type != EFI_BOOT_SERVICES_DATA &&
            mem_type != EFI_ACPI_RECLAIM_MEMORY) {
                pr_notice("Ignoring BGRT: invalid image address\n");
                goto out;
        }
        image = early_memremap(bgrt->image_address, sizeof(bmp_header));
        if (!image) {
                pr_notice("Ignoring BGRT: failed to map image header memory\n");
                goto out;
        }

        memcpy(&bmp_header, image, sizeof(bmp_header));
        early_memunmap(image, sizeof(bmp_header));
        if (bmp_header.id != 0x4d42) {
                pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n",
                        bmp_header.id);
                goto out;
        }
        bgrt_image_size = bmp_header.size;
        efi_mem_reserve(bgrt->image_address, bgrt_image_size);

        return;
out:
        memset(bgrt, 0, sizeof(bgrt_tab));
}