drivers/firmware/efi/efi-bgrt.c

   1 /*
   2  * Copyright 2012 Intel Corporation
   3  * Author: Josh Triplett <josh@joshtriplett.org>
   4  *
   5  * Based on the bgrt driver:
   6  * Copyright 2012 Red Hat, Inc <mjg@redhat.com>
   7  * Author: Matthew Garrett
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/acpi.h>
  19 #include <linux/efi.h>
  20 #include <linux/efi-bgrt.h>
  21
  22 struct acpi_table_bgrt bgrt_tab;
  23 size_t __initdata bgrt_image_size;
  24
  25 struct bmp_header {
  26         u16 id;
  27         u32 size;
  28 } __packed;
  29
  30 void __init efi_bgrt_init(struct acpi_table_header *table)
  31 {
  32         void *image;
  33         struct bmp_header bmp_header;
  34         struct acpi_table_bgrt *bgrt = &bgrt_tab;
  35
  36         if (acpi_disabled)
  37                 return;
  38
  39         if (table->length < sizeof(bgrt_tab)) {
  40                 pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n",
  41                        table->length, sizeof(bgrt_tab));
  42                 return;
  43         }
  44         *bgrt = *(struct acpi_table_bgrt *)table;
  45         if (bgrt->version != 1) {
  46                 pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n",
  47                        bgrt->version);
  48                 goto out;
  49         }
  50         if (bgrt->status & 0xfe) {
  51                 pr_notice("Ignoring BGRT: reserved status bits are non-zero %u\n",
  52                        bgrt->status);
  53                 goto out;
  54         }
  55         if (bgrt->image_type != 0) {
  56                 pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n",
  57                        bgrt->image_type);
  58                 goto out;
  59         }
  60         if (!bgrt->image_address) {
  61                 pr_notice("Ignoring BGRT: null image address\n");
  62                 goto out;
  63         }
  64
  65         image = early_memremap(bgrt->image_address, sizeof(bmp_header));
  66         if (!image) {
  67                 pr_notice("Ignoring BGRT: failed to map image header memory\n");
  68                 goto out;
  69         }
  70
  71         memcpy(&bmp_header, image, sizeof(bmp_header));
  72         early_memunmap(image, sizeof(bmp_header));
  73         if (bmp_header.id != 0x4d42) {
  74                 pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n",
  75                         bmp_header.id);
  76                 goto out;
  77         }
  78         bgrt_image_size = bmp_header.size;
  79         efi_mem_reserve(bgrt->image_address, bgrt_image_size);
  80
  81         return;
  82 out:
  83         memset(bgrt, 0, sizeof(bgrt_tab));
  84 }