Tom Gundersen | a9499fa | 2013-02-08 15:37:06 +0000 | [diff] [blame] | 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; |
Matt Fleming | a614e19 | 2013-04-30 11:30:24 +0100 | [diff] [blame] | 75 | generic_ops.query_variable_store = efi_query_variable_store; |
Tom Gundersen | a9499fa | 2013-02-08 15:37:06 +0000 | [diff] [blame] | 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); |