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 (!efi_enabled(EFI_BOOT)) 40 return; 41 42 if (table->length < sizeof(bgrt_tab)) { 43 pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n", 44 table->length, sizeof(bgrt_tab)); 45 return; 46 } 47 *bgrt = *(struct acpi_table_bgrt *)table; 48 if (bgrt->version != 1) { 49 pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n", 50 bgrt->version); 51 goto out; 52 } 53 if (bgrt->status & 0xfe) { 54 pr_notice("Ignoring BGRT: reserved status bits are non-zero %u\n", 55 bgrt->status); 56 goto out; 57 } 58 if (bgrt->image_type != 0) { 59 pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n", 60 bgrt->image_type); 61 goto out; 62 } 63 if (!bgrt->image_address) { 64 pr_notice("Ignoring BGRT: null image address\n"); 65 goto out; 66 } 67 68 image = early_memremap(bgrt->image_address, sizeof(bmp_header)); 69 if (!image) { 70 pr_notice("Ignoring BGRT: failed to map image header memory\n"); 71 goto out; 72 } 73 74 memcpy(&bmp_header, image, sizeof(bmp_header)); 75 early_memunmap(image, sizeof(bmp_header)); 76 if (bmp_header.id != 0x4d42) { 77 pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n", 78 bmp_header.id); 79 goto out; 80 } 81 bgrt_image_size = bmp_header.size; 82 efi_mem_reserve(bgrt->image_address, bgrt_image_size); 83 84 return; 85 out: 86 memset(bgrt, 0, sizeof(bgrt_tab)); 87 } 88