1 /* 2 * efi.c - EFI subsystem 3 * 4 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com> 5 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com> 6 * Copyright (C) 2013 Tom Gundersen <teg@jklm.no> 7 * 8 * This code registers /sys/firmware/efi{,/efivars} when EFI is supported, 9 * allowing the efivarfs to be mounted or the efivars module to be loaded. 10 * The existance of /sys/firmware/efi may also be used by userspace to 11 * determine that the system supports EFI. 12 * 13 * This file is released under the GPLv2. 14 */ 15 16 #include <linux/kobject.h> 17 #include <linux/module.h> 18 #include <linux/init.h> 19 #include <linux/device.h> 20 #include <linux/efi.h> 21 22 static struct kobject *efi_kobj; 23 static struct kobject *efivars_kobj; 24 25 /* 26 * Let's not leave out systab information that snuck into 27 * the efivars driver 28 */ 29 static ssize_t systab_show(struct kobject *kobj, 30 struct kobj_attribute *attr, char *buf) 31 { 32 char *str = buf; 33 34 if (!kobj || !buf) 35 return -EINVAL; 36 37 if (efi.mps != EFI_INVALID_TABLE_ADDR) 38 str += sprintf(str, "MPS=0x%lx\n", efi.mps); 39 if (efi.acpi20 != EFI_INVALID_TABLE_ADDR) 40 str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20); 41 if (efi.acpi != EFI_INVALID_TABLE_ADDR) 42 str += sprintf(str, "ACPI=0x%lx\n", efi.acpi); 43 if (efi.smbios != EFI_INVALID_TABLE_ADDR) 44 str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios); 45 if (efi.hcdp != EFI_INVALID_TABLE_ADDR) 46 str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp); 47 if (efi.boot_info != EFI_INVALID_TABLE_ADDR) 48 str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info); 49 if (efi.uga != EFI_INVALID_TABLE_ADDR) 50 str += sprintf(str, "UGA=0x%lx\n", efi.uga); 51 52 return str - buf; 53 } 54 55 static struct kobj_attribute efi_attr_systab = 56 __ATTR(systab, 0400, systab_show, NULL); 57 58 static struct attribute *efi_subsys_attrs[] = { 59 &efi_attr_systab.attr, 60 NULL, /* maybe more in the future? */ 61 }; 62 63 static struct attribute_group efi_subsys_attr_group = { 64 .attrs = efi_subsys_attrs, 65 }; 66 67 static struct efivars generic_efivars; 68 static struct efivar_operations generic_ops; 69 70 static int generic_ops_register(void) 71 { 72 generic_ops.get_variable = efi.get_variable; 73 generic_ops.set_variable = efi.set_variable; 74 generic_ops.get_next_variable = efi.get_next_variable; 75 generic_ops.query_variable_store = efi_query_variable_store; 76 77 return efivars_register(&generic_efivars, &generic_ops, efi_kobj); 78 } 79 80 static void generic_ops_unregister(void) 81 { 82 efivars_unregister(&generic_efivars); 83 } 84 85 /* 86 * We register the efi subsystem with the firmware subsystem and the 87 * efivars subsystem with the efi subsystem, if the system was booted with 88 * EFI. 89 */ 90 static int __init efisubsys_init(void) 91 { 92 int error; 93 94 if (!efi_enabled(EFI_BOOT)) 95 return 0; 96 97 /* We register the efi directory at /sys/firmware/efi */ 98 efi_kobj = kobject_create_and_add("efi", firmware_kobj); 99 if (!efi_kobj) { 100 pr_err("efi: Firmware registration failed.\n"); 101 return -ENOMEM; 102 } 103 104 error = generic_ops_register(); 105 if (error) 106 goto err_put; 107 108 error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group); 109 if (error) { 110 pr_err("efi: Sysfs attribute export failed with error %d.\n", 111 error); 112 goto err_unregister; 113 } 114 115 /* and the standard mountpoint for efivarfs */ 116 efivars_kobj = kobject_create_and_add("efivars", efi_kobj); 117 if (!efivars_kobj) { 118 pr_err("efivars: Subsystem registration failed.\n"); 119 error = -ENOMEM; 120 goto err_remove_group; 121 } 122 123 return 0; 124 125 err_remove_group: 126 sysfs_remove_group(efi_kobj, &efi_subsys_attr_group); 127 err_unregister: 128 generic_ops_unregister(); 129 err_put: 130 kobject_put(efi_kobj); 131 return error; 132 } 133 134 subsys_initcall(efisubsys_init); 135